Science.gov

Sample records for dwarf surf clam

  1. 50 CFR 648.72 - Minimum surf clam size.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Minimum surf clam size. 648.72 Section... Atlantic Surf Clam and Ocean Quahog Fisheries 648.72 Minimum surf clam size. Link to an amendment published at 76 FR 60622, Sept. 29, 2011. (a) Minimum length. The minimum length for surf clams is...

  2. 50 CFR 648.72 - Minimum surf clam size.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Minimum surf clam size. 648.72 Section 648... Atlantic Surf Clam and Ocean Quahog Fisheries 648.72 Minimum surf clam size. (a) Minimum length. The minimum length for surf clams is 4.75 inches (12.065 cm). (b) Determination of compliance. No more than...

  3. The antioxidant potential of the New Zealand surf clams.

    PubMed

    Odeleye, Tinu; Li, Yan; White, William Lindsey; Nie, Shaoping; Chen, Shuping; Wang, Junqiao; Lu, Jun

    2016-08-01

    The antioxidant action of three New Zealand surf clams was evaluated for the first time. Aqueous (cd) and ethanolic extracts from Diamond shell - Crassula aequilatera, Storm shell - Mactra murchisoni, and Tua tua - Paphies donacina were studied for their antioxidant potentials using two in vitro assays. The ethanolic extracts were further fractioned into four parts; petroleum ether (pe), ethyl acetate (ea), n-butanol (nb), and the final aqueous fraction (w). Comparing among all fractions tested, the ea fraction of P. donacina showed the strongest free radical scavenging power, with a radical scavenging activity of 76.14% at 20μg/mL. The ea fraction of C. aequilatera had the highest copper reducing activity with an absorbance of 1.596 at 20μg/mL. Results from this study suggest that some bioactive compounds with significant antioxidant effects may exist in the New Zealand surf clams, and could potentially reduce oxidative stress to deliver health benefits or to produce functional foods. PMID:26988487

  4. 76 FR 65180 - Proposed Information Collection; Comment Request; Application to Shuck Surf Clams/Ocean Quahogs...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-20

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration Proposed Information Collection; Comment Request; Application to Shuck Surf Clams/Ocean Quahogs at Sea AGENCY: National Oceanic and Atmospheric...

  5. Transformation of paralytic shellfish poisoning toxins in UK surf clams (Spisula solida) for targeted production of reference materials.

    PubMed

    Turner, Andrew D; Lewis, Adam M; O'Neil, Alison; Hatfield, Robert G

    2013-04-01

    The periodic occurrence of Paralytic Shellfish Poisoning (PSP) toxins in UK surf clams and the recent move away from biological assays for PSP testing resulted in the need to determine method performance characteristics for the replacement analytical method in this species. With the requirement for laboratory reference materials to aid this validation together with known issues relating to toxin transformation in live clams and homogenised tissue, there was the need to assess the toxin transformation characteristics of PSP toxins in surf clam tissue. Initial work examined the rates of toxin transformation in UK surf clam tissue incubated with toxin standards, showing rapid transformation of N-sulfocarbamoyl toxins with slower transformation of carbamate toxins. Full transformational pathways were determined using a combination of three different analytical methods and confirmed the major expected transformations involving decarbamoylation, with some evidence for additional reaction pathways. Results obtained from the analysis of surf clam and oyster tissues incubated with varying concentrations of toxic Alexandrium algae highlighted expected transformation reactions, although significant differences were observed in the extent of the transformations amongst the range of toxins studied, with less efficient transformation of N-hydroxylated toxins as compared with other carbamate and N-sulfocarbamoyl toxins. Analysis of PSP-toxic incurred oyster, scallop and mussel tissues incubated with variable proportions of surf clam tissue showed large differences in the extent of the transformations. Total conversion of N-sulfocarbamoyl toxins was confirmed at low relative proportions of surf clam tissue in all three species, whereas transformation of carbamate toxins was found to occur only in the presence of higher proportions of surf clam tissue in oysters and mussels in comparison with scallops. Results enabled the production of three laboratory reference materials prepared following incubation of incurred homogenates with optimum proportions of surf clam tissue, resulting in materials containing a large number of PSP toxins. Stability experiments provided good preliminary evidence for the stability of these targeted materials under storage conditions. The work therefore provides both additional information relating to the transformational activity in UK surf clams and highlights a good potential method for the targeted production of reference materials which include a wider range of toxins than normally present in naturally incurred shellfish. PMID:23369833

  6. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic). Surf Clam

    SciTech Connect

    Fay, C.W.; Neves, R.J.; Pardue, G.B.

    1983-10-01

    The surf clam (Spisula solidissima) is a dominant clam species in the mid-Atlantic region, and contributed 71.8% of all clam meats consumed in the United States between 1970 and 1974; total landings in 1981 were 20.9 thousand metric tons (46.1 million lb). Surf clams live in the coastal zone from the Gulf of Maine to Cape Hatteras, North Carolina; they are most common in the breaker zone, but occur to depths of 70 m (230 ft). They reach sexual maturity in 2 years and spawn in the mid-Atlantic region from mid-July through mid-October, often with two spawning peaks per year. Larval stages are planktonic; upon settlement, they metamorphose into juvenile clams. Adults live buried in sandy or gravel substrates, with siphons extended above the bottom for feeding and respiration. Surf clams may live up to 25 years and reach a size of 225 mm (8.9 inches). Larvae tolerate water temperatures of 14/sup 0/ to 30/sup 0/F (57/sup 0/) to 86/sup 0/F), and salinities as low as 16 ppt. Adults tolerate 0/sup 0/ to 28/sup 0/C (32/sup 0/ to 82/sup 0/F) and 12.5 ppt salinity or higher. Depletion of dissolved oxygen in ocean bottom waters was the major cause for large-scale surf clam mortalities off New York and New Jersey over the last two decades. Sewage, sludge, and heavy metals often cause accumulation of toxic materials in surf clam meats and force closure of beds to fishing to prevent human consumption of these toxic materials. 98 references, 2 figures, 3 tables.

  7. The calibration of photographic and spectroscopic films. The utilization of the digital image processor in the determination of aging of the surf clam (Spisula solidissima)

    NASA Technical Reports Server (NTRS)

    Peters, Kevin A.; Hammond, Ernest C., Jr.

    1987-01-01

    The age of the surf clam (Spisula solidissima) can be determined with the use of the Digital Image Processor. This technique is used in conjunction with a modified method for aging, refined by John Ropes of the Woods Hole Laboratory, Massachusetts. This method utilizes a thinned sectioned chondrophore of the surf clam which contains annual rings. The rings of the chondrophore are then counted to determine age. By digitizing the chondrophore, the Digital Image Processor is clearly able to separate these annual rings more accurately. This technique produces an easier and more efficient way to count annual rings to determine the age of the surf clam.

  8. Performance Characteristics of AOAC Method 2005.06 for the Determination of Paralytic Shellfish Toxins in Manila Clams, European Otter Clams, Grooved Carpet Shell Clams, Surf Clams, and Processed King Scallops.

    PubMed

    O'Neill, Alison; Turner, Andrew D

    2015-01-01

    An approach was developed for the verification of method performance of the AOAC 2005.06 LC-fluorescence detector (FLD) method for determination of paralytic shellfish poisoning (PSP) toxins in bivalve shellfish. This was developed following advice published by the Analytical Laboratory Accreditation Criteria Committee and applied to shellfish species that had not been previously subjected to a full single-laboratory validation scheme. The refined approach was developed following the need to assess performance in a number of shellfish species infrequently monitored through the UK statutory monitoring program, while reducing the impact and cost of the studies, most notably in terms of the use of valuable reference standards. The species assessed were manila clams (Ruditapes philippinarum), European otter clams (Lutraria lutraria), grooved carpet shell clams (R. decussatus), surf clams (Spisula solida), and king scallops (Pecten maximus) presented as adductor only or adductor plus roe. The method was assessed for sensitivity in terms of LOD and LOQ, toxin recovery, and method precision in each species. It incorporated the PSP toxins deemed toxic and/or prevalent in UK samples and commercially available as certified reference standards. The toxins studied included GTX1-5, dcSTX, STX, C1&2, and NEO. The toxins dcGTX2&3 were included for surf clams due to the prevalence of these toxins in this species as a result of toxin decarbamoylation. Method performance targets were met for each of the characteristics investigated. Consequently, the method was deemed fit for purpose for the screening and quantification of these clam and scallop species for PSP toxins by AOAC Method 2005.06 LC-FLD. PMID:26024751

  9. Non-destructive detection of methionine sulfoxide in the resilium of a surf clam by solid-state 13C-NMR spectroscopy.

    PubMed

    Kikuchi, Y; Tamiya, N; Nozawa, T; Hatano, M

    1982-07-01

    Methionine sulfoxide was detected in the resilium (internal hinge ligament) of a surf clam by high-resolution solid-state 13C-NMR spectroscopy involving cross-polarization and magic angle spinning, using no chemical procedure. The results support the previous report [Kikuchi, Y. and Tamiya, N. (1981) J. Biochem. (Tokyo) 89, 1975-1976] on a high content of methionine sulfoxide observed by chemical methods in the resilium protein of surf clam species. PMID:7117255

  10. Composition and Dynamics of the Nucleolinus, a Link between the Nucleolus and Cell Division Apparatus in Surf Clam (Spisula) Oocytes*

    PubMed Central

    Alliegro, Mark C.; Hartson, Steven; Alliegro, Mary Anne

    2012-01-01

    The nucleolinus is a little-known cellular structure, discovered over 150 years ago (Agassiz, L. (1857) Contributions to the Natural History of the United States of America, First Monograph, Part IIL, Little, Brown and Co., Boston) and thought by some investigators in the late 19th to mid-20th century to function in the formation of the centrosomes or spindle. A role for the nucleolinus in formation of the cell division apparatus has recently been confirmed in oocytes of the surf clam, Spisula solidissima (Alliegro, M. A., Henry, J. J., and Alliegro, M. C. (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 13718–13723). However, we know so little about the composition and dynamics of this compartment, it is difficult to construct mechanistic hypotheses or even to be sure that prior reports were describing analogous structures in the cells of mammals, amphibians, plants, and other organisms where it was observed. Surf clam oocytes are an attractive model to approach this problem because the nucleolinus is easily visible by light microscopy, making it accessible by laser microsurgery as well as isolation by common cell fractionation techniques. In this report, we analyze the macromolecular composition of isolated Spisula nucleolini and examine the relationship of this structure to the nucleolus and cell division apparatus. Analysis of nucleolinar RNA and protein revealed a set of molecules that overlaps with but is nevertheless distinct from the nucleolus. The proteins identified were primarily ones involved in nucleic acid metabolism and cell cycle regulation. Monoclonal antibodies generated against isolated nucleolini revealed centrosomal forerunners in the oocyte cytoplasm. Finally, induction of damage to the nucleolinus by laser microsurgery altered the trafficking of α- and γ-tubulin after fertilization. These observations strongly support a role for the nucleolinus in cell division and represent our first clues regarding mechanism. PMID:22219192

  11. Population structure, growth and production of the surf clam Donax serra (Bivalvia, Donacidae) on two Namibian sandy beaches

    NASA Astrophysics Data System (ADS)

    Laudien, J.; Brey, T.; Arntz, W. E.

    2003-10-01

    Population structure, growth and production of the surf clam Donax serra (Bivalvia, Donacidae), inhabiting highly exposed sandy beaches of Namibia, were investigated between November 1997 and December 1999. From length-frequency distribution and tagging-recapture data, a von Bertalanffy growth function with an asymptotic length ( L ?) of 82 mm and a growth constant ( K) of 0.274 yr -1 was established. Regarding growth performance of Donacidae, D. serra fits in a group of species inhabiting cold temperate and upwelling regions. The intertidal biomass of the studied population ranged between 141 and 546 g ash-free dry mass (AFDM) m -2 yr -1. Individual production was maximal at 56.5 mm shell length (0.83 g AFDM ind. -1 yr -1), and annual production ranged between 167 and 637 g AFDM m -2 yr -1, resulting in productivity values (P/ B) between 1.167 and 1.589 yr -1. These data underline the importance of D. serra for the beach/surf ecosystem. Further, the findings of this study are crucial to support future aquaculture or exploitation activities and management.

  12. Identification and expression of antioxidant and immune defense genes in the surf clam Mesodesma donacium challenged with Vibrio anguillarum.

    PubMed

    Maldonado-Aguayo, W; Lafarga-De la Cruz, F; Gallardo-Escrate, C

    2015-02-01

    The immune system in marine invertebrates is mediated through cellular and humoral components, which act together to address the action of potential pathogenic microorganisms. In bivalve mollusks biomolecules implicated in oxidative stress and recognition of pathogens have been involved in the innate immune response. To better understand the molecular basis of the immune response of surf clam Mesodesma donacium, qPCR approaches were used to identify genes related to its immune response against Vibrio anguillarum infection. Genes related to oxidative stress response and recognition of pathogens like superoxide dismutase (MdSOD), catalase (MdCAT), ferritin (MdFER) and filamin (MdFLMN) were identified from 454-pyrosequencing cDNA library of M. donacium and were evaluated in mantle, adductor muscle and gills. The results for transcripts expression indicated that MdSOD, MdFLMN and MdFER were primarily expressed in the muscle, while MdCAT was more expressed in gills. Challenge experiments with the pathogen V. anguillarum had showed that levels of transcript expression for MdSOD, MdCAT, MdFER, and MdFLMN were positively regulated by pathogen, following a time-dependent expression pattern with significant statistical differences between control and challenge group responses (p<0.05). These results suggest that superoxide dismutase, catalase, ferritin and filamin, could be contributing to the innate immune response of M. donacium against the pathogen V. anguillarum. PMID:25481276

  13. Identification of functional genes involved in Cd(2+) response of Chinese surf clam (Mactra chinensis) through transcriptome sequencing.

    PubMed

    Zhang, Jingjing; Li, Hongjun; Qin, Yanjie; Ye, Sheng; Liu, Min

    2016-01-01

    The Chinese surf clam Mactra chinensis is an economically important bivalve species in the coastal waters of Liaoning and Shandong Province, China. In this study, we carried out transcriptome sequencing to develop molecular resources for M. chinensis and conducted an acute test of Cd(2+) stimulation through quantitative real-time PCR (qRT-PCR) to analyze the relative expression of six functional genes. A total of 100,839 transcripts and 56,712 unigenes were obtained from 39.9 million filtered reads and 21,305 unigenes were annotated by hitting against NCBI database. According to the results of qRT-PCR, heat shock protein 22 (Hsp22) and cytochrome P450 (CYP450(2C31)) were inhibited in the low concentration, and induced in the high concentration of Cd(2+); thioredoxin peroxidase (TPx-A) was at normal level in low concentration, but induced in high concentration of Cd(2+); glutathione peroxidase A (GPA), glutathione peroxidase 1 (GPA1) and Mn superoxide dismutase gene (MnSOD) were down-regulated when exposed to any treatment groups. Expression levels of the six functional genes following Cd(2+) exposure indicated that these genes were linked to environmental stress. Moreover, the present work enriched the molecule genetic data of M. chinensis. PMID:26674114

  14. Population subdivision of the surf clam Mactra chinensis in the East China Sea: Changjiang River outflow is not the sole driver.

    PubMed

    Ni, Gang; Li, Qi; Ni, Lehai; Kong, Lingfeng; Yu, Hong

    2015-01-01

    The northwestern Pacific, characterized by unique tectonic and hydrological settings, has greatly intrigued marine phylogeographers. However, current studies mostly focus on the influence of Pleistocene isolation of sea basins in population structure of species in the region, leaving the contribution of other factors (such as freshwater outflow and environmental gradients) largely unexploited. Here we shed light on the question by investigating phylogeography of the surf clam Mactra chinensis in the East China Sea (ECS). Genetic information was acquired from 501 specimens collected from its main distribution in the region, represented by mitochondrial cytochrome oxidase I (COI) and nine polymorphic microsatellite loci. A shallow and star-like phylogeny was revealed for all COI haplotypes, indicating the origin of populations from a single refugium. Although no divergent lineages existed, population subdivision was detected in both data sets. The most striking pattern was the significant differentiation between populations north and south of a biogeographic boundary-the Changjiang Estuary, suggesting a barrier effect of the freshwater outflow to gene flow. For the northern group, substructure was revealed by COI result as one southernmost population was significant different from other ones. Clear latitude gradations in allele frequencies were revealed by microsatellite analyses, likely influenced by environmental gradient factors such as temperature. Our results demonstrate that genetic subdivision can arise for populations within the ECS despite they have a single origin, and multiple mechanisms including Changjiang River outflow, environmental gradient factors and life-history traits may act in combination in the process. PMID:26468432

  15. Population subdivision of the surf clam Mactra chinensis in the East China Sea: Changjiang River outflow is not the sole driver

    PubMed Central

    Ni, Gang; Ni, Lehai; Kong, Lingfeng; Yu, Hong

    2015-01-01

    The northwestern Pacific, characterized by unique tectonic and hydrological settings, has greatly intrigued marine phylogeographers. However, current studies mostly focus on the influence of Pleistocene isolation of sea basins in population structure of species in the region, leaving the contribution of other factors (such as freshwater outflow and environmental gradients) largely unexploited. Here we shed light on the question by investigating phylogeography of the surf clam Mactra chinensis in the East China Sea (ECS). Genetic information was acquired from 501 specimens collected from its main distribution in the region, represented by mitochondrial cytochrome oxidase I (COI) and nine polymorphic microsatellite loci. A shallow and star-like phylogeny was revealed for all COI haplotypes, indicating the origin of populations from a single refugium. Although no divergent lineages existed, population subdivision was detected in both data sets. The most striking pattern was the significant differentiation between populations north and south of a biogeographic boundary—the Changjiang Estuary, suggesting a barrier effect of the freshwater outflow to gene flow. For the northern group, substructure was revealed by COI result as one southernmost population was significant different from other ones. Clear latitude gradations in allele frequencies were revealed by microsatellite analyses, likely influenced by environmental gradient factors such as temperature. Our results demonstrate that genetic subdivision can arise for populations within the ECS despite they have a single origin, and multiple mechanisms including Changjiang River outflow, environmental gradient factors and life-history traits may act in combination in the process. PMID:26468432

  16. Delineation of surf scoter habitat in Chesapeake Bay, Maryland: macrobenthic and sediment composition of surf scoter feeding sites

    USGS Publications Warehouse

    Kidwell, D.M.; Perry, M.C.

    2005-01-01

    Surveys of surf scoters (Melanitta perspicillata) along the Atlantic coast of the United States have shown population declines in recent decades. The Chesapeake Bay has traditionally been a key wintering area for surf scoters. Past and present research has shown that bivalves constitute a major food item for seaducks in the Chesapeake Bay, with surf scoters feeding primarily on hooked mussel (Ischadium recurvum) and dwarf surf clam (Mulinia lateralis). Degraded water quality conditions in the Chesapeake Bay have been well documented and have been shown to greatly influence the composition of benthic communities. Large concentrations of feeding surf scoters (>500 individuals) in the Bay were determined through monthly boat surveys. Locations consistently lacking surf scoters were also determined. Macrobenthos were seasonally sampled at 3 locations containing scoters and 3 locations without scoters. A 1 kilometer square grid was superimposed over each location using GIS and sampling sites within the square were randomly chosen. Benthos were sampled at each site using SCUBA and a meter square quadrat. Biomass and size class estimates were determined for all bivalves within each kilometer square. Results indicated that scoter feeding sites contained significantly greater biomass of M. lateralis, I. recurvum, and Gemma gemma than locations where no scoters were present. Substrate differences were also detected, with scoter feeding sites being composed of a sand/shell mix while non-scoter sites consisted primarily of mud. This data indicates that surf scoters in the Chesapeake Bay are selecting areas with high densities of preferred food items, potentially maximizing there foraging energetics. In addition, two scoter feeding sites also contained a patchwork of eastern oyster (Crassostrea virginica) and oyster shell, on which much of the I. recurvum was attached. This suggests the possibility that surf scoters utilize eastern oyster habitat and the dramatic depletion of oysters in the Bay could be a possible factor in surf scoter decline. More research is needed into the possible relationship between surf scoters and the eastern oyster.

  17. Molecular characterization of two kazal-type serine proteinase inhibitor genes in the surf clam Mesodesma donacium exposed to Vibrio anguillarum.

    PubMed

    Maldonado-Aguayo, Waleska; Nez-Acua, Gustavo; Valenzuela-Muoz, Valentina; Chvez-Mardones, Jacqueline; Gallardo-Escrate, Cristian

    2013-06-01

    This study reports two kazal-type serine protease inhibitors (KPI) identified in a cDNA library from the surf clam Mesodesma donacium, and characterized through Rapid Amplification of cDNA Ends (RACE). The KPIs, denoted as MdSPI-1 and MdSPI-2, presented full sequences of 1139 bp and 781 bp respectively. MdSPI-1 had a 5'untranslated region (UTR) of 175 bp, a 3'UTR of 283 bp and an open reading frame (ORF) of 681 pb that encodes for 227 amino acids. MdSPI-2 showed a 5'UTR of 70 bp, a 3'UTR of 279 bp and an ORF of 432 bp that encodes for 144 amino acids. Both sequences presented two kazal-type tandem domains. Phylogenetic analysis of MdSPI-1 and MdSPI-2 shows a main clade composed by other bivalve species and closely related crustaceans. Real time PCR analysis showed that MdSPI-1 is mainly up-regulated in mantle, foot, gills and muscle tissues, while MdSPI-2 is expressed principally in foot tissue. Moreover, to evaluate the immune response of MdSPI-1 and MdSPI-2, infections with Vibrio anguillarum were performed. Herein, MdSPI-1 and MdSPI-2 transcription expression were significantly up-regulated at 2 and 8 h post-challenge. Our results suggest that MdSPI-1 and MdSPI-2 are important humoral factors of innate immunity in M. donacium. PMID:23528874

  18. CLAMS Data and Information

    Atmospheric Science Data Center

    2015-05-27

    ... CLAMS Data and Information The Chesapeake Lighthouse and Aircraft Measurements for Satellites ( CLAMS ) field campaign ... Data CLAMS Home Page Chesapeake Lighthouse and Aircraft An Overview of the CLAMS Experiment ...

  19. Surf Tourism, Artificial Surfing Reefs, and Environmental Sustainability

    NASA Astrophysics Data System (ADS)

    Slotkin, Michael H.; Chambliss, Karen; Vamosi, Alexander R.; Lindo, Chris

    2009-07-01

    This paper explores the confluence of surf tourism, artificial surfing reefs, and sustainability. Surfing is an ascendant recreational and tourism industry and artificial surfing reefs are a new and innovative technology and product. Presented within the context of Florida's Space Coast, empirical details on surf tourism are discussed along with the possible implications for sustainability.

  20. Surfing wave climate variability

    NASA Astrophysics Data System (ADS)

    Espejo, Antonio; Losada, Iigo J.; Mndez, Fernando J.

    2014-10-01

    International surfing destinations are highly dependent on specific combinations of wind-wave formation, thermal conditions and local bathymetry. Surf quality depends on a vast number of geophysical variables, and analyses of surf quality require the consideration of the seasonal, interannual and long-term variability of surf conditions on a global scale. A multivariable standardized index based on expert judgment is proposed for this purpose. This index makes it possible to analyze surf conditions objectively over a global domain. A summary of global surf resources based on a new index integrating existing wave, wind, tides and sea surface temperature databases is presented. According to general atmospheric circulation and swell propagation patterns, results show that west-facing low to middle-latitude coasts are more suitable for surfing, especially those in the Southern Hemisphere. Month-to-month analysis reveals strong seasonal variations in the occurrence of surfable events, enhancing the frequency of such events in the North Atlantic and the North Pacific. Interannual variability was investigated by comparing occurrence values with global and regional modes of low-frequency climate variability such as El Nio and the North Atlantic Oscillation, revealing their strong influence at both the global and the regional scale. Results of the long-term trends demonstrate an increase in the probability of surfable events on west-facing coasts around the world in recent years. The resulting maps provide useful information for surfers, the surf tourism industry and surf-related coastal planners and stakeholders.

  1. Surfing on the Spectrum

    ERIC Educational Resources Information Center

    Apel, Laura

    2007-01-01

    Israel Paskowitz loves surfing. As a former competitive surfer, he has spent much of his life in the ocean and absorbed in a community of athletes that share a special connection with the water. Surfing is often thought of as a spiritual hobby that brings peace and relaxation to those who experience it. However, it was not until Israel's son,

  2. Medical Aspects of Surfing.

    ERIC Educational Resources Information Center

    Renneker, Mark

    1987-01-01

    The medical aspects of surfing include ear and eye injuries and sprains and strains of the lower back and neck, as well as skin cancer from exposure to the sun. Treatment, rehabilitation, and prevention of these problems are discussed. Surfing is recommended as part of an exercise program for reasonably healthy people. (Author/MT)

  3. SURF: Submm User Reduction Facility

    NASA Astrophysics Data System (ADS)

    Jenness, Tim; Lightfoot, John

    2014-03-01

    SURF reduces data from the SCUBA instrument from the James Clerk Maxwell Telescope. Facilities are provided for reducing all the SCUBA observing modes including jiggle, scan and photometry modes. SURF uses the Starlink environment (ascl:1110.012).

  4. An Adaptive Surfing Apparatus.

    ERIC Educational Resources Information Center

    Bond, Gregory

    Reported is a study in which the effectiveness of an adapted surfing apparatus was evaluated for eight adolescents with upper extremity physical impairments. Related literature is reviewed, and a detailed analysis of the adapted device is presented. Case studies of the individual Ss are provided to demonstrate test performance in a pool and the

  5. Face recognition using SURF features

    NASA Astrophysics Data System (ADS)

    Du, Geng; Su, Fei; Cai, Anni

    2009-10-01

    The Scale Invariant Feature Transform (SIFT) proposed by David G. Lowe has been used in face recognition and proved to perform well. Recently, a new detector and descriptor, named Speed-Up Robust Features (SURF) suggested by Herbert Bay, attracts people's attentions. SURF is a scale and in-plane rotation invariant detector and descriptor with comparable or even better performance with SIFT. Because each of SURF feature has only 64 dimensions in general and an indexing scheme is built by using the sign of the Laplacian, SURF is much faster than the 128-dimensional SIFT at the matching step. Thus based on the above advantages of SURF, we propose to exploit SURF features in face recognition in this paper.

  6. Shock-wave surfing

    SciTech Connect

    Laurence, Stuart J; Deiterding, Ralf

    2011-01-01

    A phenomenon referred to as shock-wave surfing , in which a body moves in such a way as to follow the shock wave generated by another upstream body, is investigated numerically and theoretically. This process can lead to the downstream body accumulating a significantly higher lateral velocity than would otherwise be possible, and thus is of importance in situations such as meteoroid fragmentation, in which the fragment separation behaviour following disruption is determined to a large extent by aerodynamic effects. The surfing effect is first investigated in the context of interactions between a sphere and a planar oblique shock. Numerical simulations are performed and a simple theoretical model is developed to determine the forces acting on the sphere. A phase-plane description is employed to elucidate features of the system dynamics. The theoretical model is then generalised to the more complex situation of aerodynamic interactions between two spheres, and, through comparisons with further computations, is shown to adequately predict, in particular, the final separation velocity of the surfing sphere in initially touching configurations. Both numerical simulations and theory indicate a strong influence of the body radius ratio on the separation process and predict a critical radius ratio for initially touching fragments that delineates entrainment of the smaller fragment within the larger fragment s shock from expulsion; this critical ratio also results in the most extended surfing. Further, these results show that an earlier prediction for the separation velocity to scale with the square root of the radius ratio does not accurately describe the separation behaviour. The theoretical model is then employed to investigate initial configurations with varying relative sphere positions and initial velocities. A phase-space description is also shown to be useful in elucidating the dynamics of the sphere-sphere system. With regard to meteoroid fragmentation, it is shown that a large fraction of the variation in the separation behaviour deduced by previous authors from an analysis of terrestrial crater fields can be explained by a combination of surfing and a modest rotation rate of the parent body. Finally, a selection effect for multiple fragments travelling together, e.g., immediately following atmospheric disruption, is predicted, whereby larger fragments repel one another whereas smaller fragments are entrained within the shocks of larger bodies.

  7. CLAMS_CV580_CAR

    Atmospheric Science Data Center

    2014-04-28

    CLAMS_CV580_CAR Project Title: CLAMS Discipline: Field ... Radiance in 14 spectral bands Order Data: ASDC Order Tool: Order Data Relevant Documents: CV580 Flight Tracks CAR Home Page Readme Files: Readme CAR ...

  8. Surfing the Internet.

    PubMed

    Clay, A T

    1995-08-01

    More physicians are surfing the Internet than ever before, thanks to the recent launch of MSMSNET, the Michigan State Medical Society's new online service for physician members. If words like World Wide Web, E-mail, and Hypertext links send you into a state of confusion, then read on. This month's cover story discusses MSMS's launch into the information superhighway and training programs MSMS has in store for physician members. Also included is an examination of the Internet--past, present and future--by the president of Voyager Information Networks, Inc., a Michigan corporation specializing in Internet services for Michigan trade groups and other organizations, including MSMS. This cover story marks the beginning of a series of articles on the Internet which will appear in future issues of Michigan Medicine. Hop on board and enjoy the ride! PMID:7565165

  9. Guide to Healthy Web Surfing

    MedlinePLUS

    ... gov/medlineplus/healthywebsurfing.html MedlinePlus Guide to Healthy Web Surfing To use the sharing features on this ... the site, use caution. Focus on quality--All Web sites are not created equal Does the site ...

  10. Surfing Electrons in Quantum Computers?

    NASA Astrophysics Data System (ADS)

    Pomeau, Y.

    I take this opportunity of writing a piece of science for my friend Manuel G. Velarde to discuss things dear to his heart: surfing of electrons on acoustic waves. It has been claimed recently, but not by him, that transport of electrons by surf could be used to carry quantum information in quantum computers. This is physically impossible because this would require to maintain the quantum coherence linked to localisation, a coherence decaying very fastly in the real world.

  11. Burrowing saves Lake Erie clams

    USGS Publications Warehouse

    Nichols, S. Jerrine; Wilcox, Douglas A.

    1997-01-01

    Freshwater unionid clams in North America have been virtually eliminated from waters that are colonized by zebra mussels. Near total mortality has been reported in western Lake Erie, but we have discovered a large population of native clams in a Lake Erie wetland that shows little sign of infestation. Field observations and laboratory experiments show that warm summer water temperatures and soft, silt-clay sediments trigger burowing by clams. This discourages infestation and physically removes any attached zebra mussels.

  12. Plans for conversion of SURF II to SURF III

    SciTech Connect

    Hamilton, A.D.; Furst, M.L.; Hughey, L.R.; Madden, R.P.; OBrian, T.R.; Proctor, J.E.

    1996-09-01

    The Synchrotron Ultraviolet Radiation Facility (SURF II) at the National Institute of Standards and Technology, Gaithersburg, MD, USA, has served as a primary radiometric standard in the vacuum ultraviolet region since its conversion from a synchrotron to an electron storage ring in 1974. The magnet iron, however, dates back to an original betatron design of the late 1940s. The advent of both modern materials and methods of finite element analysis have made possible the design of magnets offering far greater dc performance than the existing SURF system. In this paper we discuss the general design and plans to convert SURF II to SURF III, which will offer reduced radiometric uncertainty, an increase in energy from 300 MeV to 385 MeV, a modernized control system, and two new beamlines, which are not presently possible. Anticipated new beamline activities include a substantial new effort devoted to radiometric improvements from IR to far UV and development of stations for microspectoscopy and electroreflectance. {copyright} {ital 1996 American Institute of Physics.}

  13. 21 CFR 102.49 - Fried clams made from minced clams.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Fried clams made from minced clams. 102.49 Section... Nonstandardized Foods 102.49 Fried clams made from minced clams. (a) The common or usual name of the food product that resembles and is of the same composition as fried clams, except that it is composed...

  14. 21 CFR 102.49 - Fried clams made from minced clams.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Fried clams made from minced clams. 102.49 Section... Nonstandardized Foods 102.49 Fried clams made from minced clams. (a) The common or usual name of the food product that resembles and is of the same composition as fried clams, except that it is composed...

  15. 21 CFR 102.49 - Fried clams made from minced clams.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Fried clams made from minced clams. 102.49 Section... Nonstandardized Foods 102.49 Fried clams made from minced clams. (a) The common or usual name of the food product that resembles and is of the same composition as fried clams, except that it is composed...

  16. 21 CFR 102.49 - Fried clams made from minced clams.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Fried clams made from minced clams. 102.49 Section... Nonstandardized Foods 102.49 Fried clams made from minced clams. (a) The common or usual name of the food product that resembles and is of the same composition as fried clams, except that it is composed...

  17. 21 CFR 102.49 - Fried clams made from minced clams.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 2 2013-04-01 2013-04-01 false Fried clams made from minced clams. 102.49 Section... Nonstandardized Foods 102.49 Fried clams made from minced clams. (a) The common or usual name of the food product that resembles and is of the same composition as fried clams, except that it is composed...

  18. Lightcurve Analysis of 5181 Surf

    NASA Astrophysics Data System (ADS)

    Hayes-Gehrke, Melissa N.; Afe, Adeseye; Cha, Daniel; Cotton, Ayana; Diedrick, Jasmine; Liu, Kevin; Livas, Matthew; Melone, Katelyn; Mistry, Samirbhai; Murphy, Jacob; Ren, Xin; Romano, Philip; Scearce, Michael; Smith, Andrew; Summers, Brian

    2015-10-01

    A lightcurve was determined for the main-belt asteroid 5181 SURF. The asteroid was observed for seven nights over the course of two months during 2015 March-April. The rotation period was found to be 6.111 0.001 h.

  19. WATERSHED INFORMATION - SURF YOUR WATERSHED

    EPA Science Inventory

    Surf Your Watershed is both a database of urls to world wide web pages associated with the watershed approach of environmental management and also data sets of relevant environmental information that can be queried. It is designed for citizens and decision makers across the count...

  20. Situated Learning in an Australian Surf Club

    ERIC Educational Resources Information Center

    Light, Richard

    2006-01-01

    The article examines learning and identity formation for young people in an Australian surf club. Drawing on Lave and Wenger's notion of situated learning, it identifies how membership in the surf club from an early age involves highly significant and meaningful learning and identity formation, where learning is co-constructed with other members

  1. Composition, shell strength, and metabolizable energy of Mulinia lateralis and Ischadium recurvum as food for wintering surf scoters (Melanitta perspicillata)

    USGS Publications Warehouse

    Berlin, Alicia; Perry, Matthew; Kohn, R.A.; Paynter, K.T., Jr.; Ottinger, Mary Ann

    2015-01-01

    Decline in surf scoter (Melanitta perspicillata) waterfowl populations wintering in the Chesapeake Bay has been associated with changes in the availability of benthic bivalves. The Bay has become more eutrophic, causing changes in the benthos available to surf scoters. The subsequent decline in oyster beds (Crassostrea virginica) has reduced the hard substrate needed by the hooked mussel (Ischadium recurvum), one of the primary prey items for surf scoters, causing the surf scoter to switch to a more opportune species, the dwarf surfclam (Mulinia lateralis). The composition (macronutrients, minerals, and amino acids), shell strength (N), and metabolizable energy (kJ) of these prey items were quantified to determine the relative foraging values for wintering scoters. Pooled samples of each prey item were analyzed to determine composition. Shell strength (N) was measured using a shell crack compression test. Total collection digestibility trials were conducted on eight captive surf scoters. For the prey size range commonly consumed by surf scoters (6-12 mm for M. lateralis and 18-24 mm for I. recurvum), I. recurvum contained higher ash, protein, lipid, and energy per individual organism than M. lateralis. I. recurvum required significantly greater force to crack the shell relative to M. lateralis. No difference in metabolized energy was observed for these prey items in wintering surf scoters, despite I. recurvum's higher ash content and harder shell than M. lateralis. Therefore, wintering surf scoters were able to obtain the same amount of energy from each prey item, implying that they can sustain themselves if forced to switch prey.

  2. Composition, Shell Strength, and Metabolizable Energy of Mulinia lateralis and Ischadium recurvum as Food for Wintering Surf Scoters (Melanitta perspicillata)

    PubMed Central

    Wells-Berlin, Alicia M.; Perry, Matthew C.; Kohn, Richard A.; Paynter, Kennedy T.; Ottinger, Mary Ann

    2015-01-01

    Decline in surf scoter (Melanitta perspicillata) waterfowl populations wintering in the Chesapeake Bay has been associated with changes in the availability of benthic bivalves. The Bay has become more eutrophic, causing changes in the benthos available to surf scoters. The subsequent decline in oyster beds (Crassostrea virginica) has reduced the hard substrate needed by the hooked mussel (Ischadium recurvum), one of the primary prey items for surf scoters, causing the surf scoter to switch to a more opportune species, the dwarf surfclam (Mulinia lateralis). The composition (macronutrients, minerals, and amino acids), shell strength (N), and metabolizable energy (kJ) of these prey items were quantified to determine the relative foraging values for wintering scoters. Pooled samples of each prey item were analyzed to determine composition. Shell strength (N) was measured using a shell crack compression test. Total collection digestibility trials were conducted on eight captive surf scoters. For the prey size range commonly consumed by surf scoters (612 mm for M. lateralis and 1824 mm for I. recurvum), I. recurvum contained higher ash, protein, lipid, and energy per individual organism than M. lateralis. I. recurvum required significantly greater force to crack the shell relative to M. lateralis. No difference in metabolized energy was observed for these prey items in wintering surf scoters, despite I. recurvums higher ash content and harder shell than M. lateralis. Therefore, wintering surf scoters were able to obtain the same amount of energy from each prey item, implying that they can sustain themselves if forced to switch prey. PMID:25978636

  3. Composition, Shell Strength, and Metabolizable Energy of Mulinia lateralis and Ischadium recurvum as Food for Wintering Surf Scoters (Melanitta perspicillata).

    PubMed

    Wells-Berlin, Alicia M; Perry, Matthew C; Kohn, Richard A; Paynter, Kennedy T; Ottinger, Mary Ann

    2015-01-01

    Decline in surf scoter (Melanitta perspicillata) waterfowl populations wintering in the Chesapeake Bay has been associated with changes in the availability of benthic bivalves. The Bay has become more eutrophic, causing changes in the benthos available to surf scoters. The subsequent decline in oyster beds (Crassostrea virginica) has reduced the hard substrate needed by the hooked mussel (Ischadium recurvum), one of the primary prey items for surf scoters, causing the surf scoter to switch to a more opportune species, the dwarf surfclam (Mulinia lateralis). The composition (macronutrients, minerals, and amino acids), shell strength (N), and metabolizable energy (kJ) of these prey items were quantified to determine the relative foraging values for wintering scoters. Pooled samples of each prey item were analyzed to determine composition. Shell strength (N) was measured using a shell crack compression test. Total collection digestibility trials were conducted on eight captive surf scoters. For the prey size range commonly consumed by surf scoters (6-12 mm for M. lateralis and 18-24 mm for I. recurvum), I. recurvum contained higher ash, protein, lipid, and energy per individual organism than M. lateralis. I. recurvum required significantly greater force to crack the shell relative to M. lateralis. No difference in metabolized energy was observed for these prey items in wintering surf scoters, despite I. recurvum's higher ash content and harder shell than M. lateralis. Therefore, wintering surf scoters were able to obtain the same amount of energy from each prey item, implying that they can sustain themselves if forced to switch prey. PMID:25978636

  4. The clam 3' UTR masking element-binding protein p82 is a member of the CPEB family.

    PubMed Central

    Walker, J; Minshall, N; Hake, L; Richter, J; Standart, N

    1999-01-01

    During early development gene expression is controlled principally at the translational level. Oocytes of the surf clam Spisula solidissima contain large stockpiles of maternal mRNAs that are translationally dormant or masked until meiotic maturation. Activation of the oocyte by fertilization leads to translational activation of the abundant cyclin and ribonucleotide reductase mRNAs at a time when they undergo cytoplasmic polyadenylation. In vitro unmasking assays have defined U-rich regions located approximately centrally in the 3' UTRs of these mRNAs as translational masking elements. A clam oocyte protein of 82 kDa, p82, which selectively binds the masking elements, has been proposed to act as a translational repressor. Importantly, mRNA-specific unmasking in vitro occurs in the absence of poly(A) extension. Here we show that clam p82 is related to Xenopus CPEB, an RNA-binding protein that interacts with the U-rich cytoplasmic polyadenylation elements (CPEs) of maternal mRNAs and promotes their polyadenylation. Cloned clam p82/CPEB shows extensive homology to Xenopus CPEB and related polypeptides from mouse, goldfish, Drosophila and Caenorhabditis elegans, particularly in their RNA-binding C-terminal halves. Two short N-terminal islands of sequence, of unknown function, are common to vertebrate CPEBs and clam p82. p82 undergoes rapid phosphorylation either directly or indirectly by cdc2 kinase after fertilization in meiotically maturing clam oocytes, prior to its degradation during the first cell cleavage. Phosphorylation precedes and, according to inhibitor studies, may be required for translational activation of maternal mRNA. These data suggest that clam p82 may be a functional homolog of Xenopus CPEB. PMID:9917063

  5. Asiatic clam invasion: causes and effects

    SciTech Connect

    Cherry, D.S.; Cairns, J.; Graney, R.L.

    1980-01-01

    The recent introduction and subsequent invasion of the Asiatic clam has offered a new problem of infestation in power plant intake systems that conventional intermittent chlorination procedures may not resolve. These clam invasions adversely affect intake systems and irrigation works by clogging the systems and causing erosion of pipes. Heated power plant discharges were found to be a source of thermal enrichment for the clams. Methods of temperature control followed by chlorination appear to offer short-term solutions; harvesting of the clams for protein and calcium contents present an additional solution.

  6. Depuration and anatomical distribution of domoic acid in the surf clam Mesodesma donacium.

    PubMed

    lvarez, Gonzalo; Uribe, Eduardo; Regueiro, Jorge; Martin, Helena; Gajardo, Teresa; Jara, Lorena; Blanco, Juan

    2015-08-01

    In northern Chile, domoic acid (DA) has been detected in several bivalve species. In Mesodesma donacium, one of the most important commercial species for local fishermen, no information is available on depuration, or on the anatomical distribution of this toxin and its potential use as a palliative measure to minimize the consequences of ASP outbreaks. Deputation of DA is very fast in M.donacium, and can be adequately described by means of a two-compartment model. The estimated rates for the first and second compartments were 1.27d(-1) and 0.24d(-1), respectively, with a transfer rate between compartments of 0.75. Having high depuration rates protects this species from being affected by Pseudo-nitzschia blooms for an extended period of time. Taking this into account, the time in which the bivalves are unsafe for consumers is very short, and therefore the economic losses that could result by the DA outbreaks in local fisheries should be moderate. In relation to anatomical distribution, at least during the uptake phase, the toxin was evenly distributed within the soft tissues, with a total toxin burden corresponding to 27%, 32% and 41% for Digestive Gland (DG), Foot (FT) and Other Body Fractions (OBF), respectively. Since the contribution of each organ to the toxin concentration is a function of both weight contribution and toxin burden, the pattern of toxin distribution showed the following trend: "all other body fractions" (OBF)>Foot (FT)>Digestive Gland (DG). Thus, the highest concentration of DA, with a contribution close to 72%, corresponds to the edible tissues (OBF+FT), while the DG (non-edible tissue) only contributes the remaining 28%. Consequently, in view of the anatomical distribution of domoic acid in M.donacium, the elimination of the digestive gland does not substantially reduce the toxicity of the final product and therefore selective evisceration would not improve their quality for human consumption. PMID:26003793

  7. Aurora B kinase maintains chromatin organization during the MI to MII transition in surf clam oocytes.

    PubMed

    George, Olivia; Johnston, Mantissa A; Shuster, Charles B

    2006-11-01

    Meiosis represents a specialized cell cycle whereby cells undergo two reductive divisions without an intervening S phase. In oocytes, the transition from meiosis I to II is brief, with paired sister chromatids remaining condensed throughout the interkinesis period. This stands in contrast to mitotic divisions where cytokinesis and the return to interphase is always accompanied by chromatin decondensation and nuclear envelope reformation. Because other aspects of M phase exit are normal, we probed the mechanisms that allow for polar body extrusion while retaining chromatin condensation in Spisula solidissima oocytes. If oocytes were activated in the presence of protein synthesis inhibitors, oocytes progressed normally through MI, but arrested in interkinesis with condensed chromatin, phosphorylated histone H3 and a disorganized MII spindle. Neither inhibition of CDK1- nor MAPK activity in arrested oocytes was sufficient to drive chromatin decondensation or nuclear envelope reformation, suggesting that these kinases were not responsible for the maintenance of chromatin condensation. However, inhibition of Aurora B kinase activity resulted in chromatin decondensation, loss of histone H3 phosphorylation and reformation of the nuclear envelope. Inhibition of Aurora B activity following MI also resulted in chromosome segregation defects during MII and blocked polar body formation, consistent with Aurora B's well-established role in cytokinesis. Together, these results suggest that extended Aurora B activity between meiotic divisions maintains chromatin condensation, thus allowing for the rapid reassembly of the MII spindle and progression through meiosis. PMID:17172833

  8. Juvenile Surf Smelt Surveys in Central Puget Sound, Washington

    USGS Multimedia Gallery

    Three size classes of juvenile surf smelt collected in a beach seine by USGS Western Fisheries Research Center scientists while conducting a survey for juvenile surf smelt on Bainbridge Island, WA. ...

  9. 6. Elevated view toward corner of Stillwell Avenue and Surf ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Elevated view toward corner of Stillwell Avenue and Surf Avenue showing association with Coney Island Amusement Park. Looking southeast. - Stillwell Avenue Station, Intersection of Stillwell & Surf Avenues, Brooklyn, Kings County, NY

  10. Development of Operational Surf Forecasting with Delft3D in the Conformation of Navy Standard Surf Output (SURF 3.2)

    NASA Astrophysics Data System (ADS)

    Choi, J.; Allard, R.

    2012-12-01

    The one-dimensional Navy Standard Surf Model (NSSM or SURF 3.2) has been implemented and used as an operational surf model at the Naval Oceanographic Office to provide accurate forecasts of surf conditions to support amphibious operations. Though NSSM shows its robustness, it can produce inaccurate wave and longshore current estimations for areas with complex bottom topography. NSSM assumes parallel bottom contours in the surf zone, and it can not account for longshore variations of bathymetry or forcing. Two- or three-dimensional models should be used to accommodate such variations. The Delft3D modeling suite, developed by Delft Hydraulics, is a fully integrated three-dimensional hydrodynamic modeling system, capable of simulations of flows, waves, water quality, morphological developments, and ecology. Delft3D produces two- and three-dimensional forecasting output for many nearshore wave and flow parameters with a wave-current interaction capability. While Delft3D does not produce NSSM formats, we have implemented software that computes the standard surf parameters of NSSM such as maximum and significant breaker heights, breaker type statistics, percent of breaking, surf zone width, number of surf lines, and modified surf index (MSI). Surf forecasting can be extended in continuous alongshore direction because complex coastlines can be well resolved with the curvilinear, boundary-fitted grid system of Delft3D. Examples of nearshore modeling with Delft3D will be presented.

  11. Surfing Global Change: Negotiating Sustainable Solutions

    ERIC Educational Resources Information Center

    Ahamer, Gilbert

    2006-01-01

    SURFING GLOBAL CHANGE (SGC) serves as a procedural shell for attaining sustainable solutions for any interdisciplinary issue and is intended for use in advanced university courses. The participants' activities evolve through five levels from individual argumentation to molding one's own views for the "common good." The paradigm of "ethics of…

  12. Surfing Global Change: Negotiating Sustainable Solutions

    ERIC Educational Resources Information Center

    Ahamer, Gilbert

    2006-01-01

    SURFING GLOBAL CHANGE (SGC) serves as a procedural shell for attaining sustainable solutions for any interdisciplinary issue and is intended for use in advanced university courses. The participants' activities evolve through five levels from individual argumentation to molding one's own views for the "common good." The paradigm of "ethics of

  13. Turbulent viscosity in natural surf zones

    NASA Astrophysics Data System (ADS)

    Grasso, F.; Ruessink, B. G.

    2012-12-01

    Waves breaking in the shallow surf zone near the shoreline inject turbulence into the water column that may reach the bed to suspend sediment. Breaking-wave turbulence in the surf zone is, however, poorly understood, which is one of the reasons why many process-based coastal-evolution models predict coastal change during severe storms inadequately. Here, we use data collected in two natural surf zones to derive a new parameterization for the stability function C? that determines the magnitude of the eddy viscosity ?t in two-equation turbulent-viscosity models, ?t = C?k2/?, where k is turbulent kinetic energy and ? is the turbulence dissipation rate. In both data sets, the ratio of turbulence production to dissipation is small (?0.15), while vertical turbulence diffusion is significant. This differs from assumptions underlying existing C? parameterizations, which we show to severely overpredict observed C? for most conditions. Additionally, we rewrite our new C? parameterization into a formulation that accurately reproduces our Reynolds-stress based estimates of turbulence production. This formulation is linear with strain, consistent with earlier theoritical work for large strain rates. Also, it does not depend on ? and can, therefore, also be applied in one-equation turbulent-viscosity models. We anticipate our work to improve turbulence modeling in natural surf zones and to eventually lead to more reliable predictions of coastal evolution in response to severe storms.

  14. Clam-associated vibriosis, USA, 19882010

    PubMed Central

    Slayton, R. B.; Newton, A. E.; Depaola, A.; Jones, J. L.; Mahon, B. E.

    2015-01-01

    SUMMARY Infections with Vibrio spp. have frequently been associated with consumption of bivalve molluscs, especially oysters, but illness associated with clams has also been well documented. We describe the 2312 domestically acquired foodborne Vibrio infections reported to the Cholera and Other Vibrio Illness Surveillance system from 1988 to 2010. Clams were associated with at least 4% (93 persons, only clams) and possibly as many as 24% (556 persons, any clams) of foodborne cases. Of those who consumed only clams, 77% of infections were caused by V. parahaemolyticus. Clam-associated illnesses were generally similar to those associated with other seafood consumption. Clams associated with these illnesses were most frequently harvested from the Atlantic coastal states and eaten raw. Our study describes the contribution of clams to the overall burden of foodborne vibriosis and indicates that a comprehensive programme to prevent foodborne vibriosis need to address the risks associated with clams. PMID:23920418

  15. Quantifying the Dynamics of Bacterial Crowd Surfing

    NASA Astrophysics Data System (ADS)

    Moscaritolo, Robert; Kinley, Matt; White, Robin; Kelly, Corey; Giuliani, Maximiliano; Burrows, Lori; Dutcher, John

    2013-03-01

    Type IV pili (TFP) are thin (several nanometers in diameter) adhesive protein filaments that can be extended and retracted by certain classes of Gram-negative bacteria including P. aeruginosa PAO1. The motion of bacteria on surfaces by TFP is referred to as twitching motility because of its jerky nature, and it leads to complex, collective motion of large numbers of cells. When non-motile mutants of P. aeruginosa cells, which do not have pili and therefore cannot twitch, are mixed with motile, wild type cells, we observed the non-motile cells being carried along (``crowd surfing'') by the moving wild type cells. Crowd surfing extends to other non-motile species as well as inert particles and can lead to unexpected transport of non-motile, pathogenic bacterial cells, with direct implications for the spread of bacterial infections. We have developed a protocol for tracking and analyzing the trajectories of moving bacterial cells. Using a custom built, temperature and humidity controlled environmental chamber, we characterize the crowd surfing phenomenon under different environmental conditions.

  16. Vertical structure of the undertow outside the surf zone

    NASA Astrophysics Data System (ADS)

    Putrevu, Uday; Svendsen, Ib A.

    1993-12-01

    The vertical structure of the undertow in the shoaling region outside the surf zone is quite different from that inside the surf zone. Inside the surf zone the undertow typically has a large seaward directed velocity near the bottom and either a shoreward directed or a small seaward directed velocity at trough level. Measurements show that outside the surf zone the undertow has a small seaward directed velocity near the bed and a large seaward directed velocity at trough level. In this paper we develop theoretical expressions for the undertow outside the surf zone and show that the steady streaming from the bottom boundary layer which was earlier found to have a negligible effect in the surf zone (Svendsen et al., 1987) does have a significant influence on the vertical structure of the undertow in that region.

  17. 33 CFR 117.323 - Outer Clam Bay

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Outer Clam Bay 117.323 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Florida 117.323 Outer Clam Bay The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on signal if at least 30 minutes advance notice is given....

  18. 33 CFR 117.323 - Outer Clam Bay

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Outer Clam Bay 117.323 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Florida 117.323 Outer Clam Bay The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on signal if at least 30 minutes advance notice is given....

  19. The Clam Trail: Blending Science Education, Public Art, and Tourism

    ERIC Educational Resources Information Center

    Muscio, Cara; Flimlin, Gef; Bushnell, Rick

    2011-01-01

    The Barnegat Bay Shellfish Restoration's Clam Trail is an award-winning scavenger hunt that combines science education, public art, and tourism. This family adventure has participants seeking out giant painted fiberglass clams, upweller clam nurseries, and points of interest in search of science facts to record on their forms. Upon returning these…

  20. 33 CFR 117.323 - Outer Clam Bay.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Outer Clam Bay. 117.323 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Florida 117.323 Outer Clam Bay. The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on signal if at least 30 minutes advance notice is given....

  1. 33 CFR 117.323 - Outer Clam Bay

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Outer Clam Bay 117.323 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Florida 117.323 Outer Clam Bay The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on signal if at least 30 minutes advance notice is given....

  2. 33 CFR 117.323 - Outer Clam Bay.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Outer Clam Bay. 117.323 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Florida 117.323 Outer Clam Bay. The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on signal if at least 30 minutes advance notice is given....

  3. The Clam Trail: Blending Science Education, Public Art, and Tourism

    ERIC Educational Resources Information Center

    Muscio, Cara; Flimlin, Gef; Bushnell, Rick

    2011-01-01

    The Barnegat Bay Shellfish Restoration's Clam Trail is an award-winning scavenger hunt that combines science education, public art, and tourism. This family adventure has participants seeking out giant painted fiberglass clams, upweller clam nurseries, and points of interest in search of science facts to record on their forms. Upon returning these

  4. Juvenile Surf Smelt Surveys in Central Puget Sound, Washington

    USGS Multimedia Gallery

    Juvenile sand lance collected in a beach seine by USGS Western Fisheries Research Center scientists while conducting a survey for juvenile surf smelt on Bainbridge Island, WA.  Like surf smelt, sand lance are an important forage fish in Puget Sound.  ...

  5. Sea-spray aerosol particles generated in the surf zone

    NASA Astrophysics Data System (ADS)

    van Eijk, A. M. J.; Kusmierczyk-Michulec, J. T.; Francius, M. J.; Tedeschi, G.; Piazzola, J.; Merritt, D. L.; Fontana, J. D.

    2011-10-01

    To assess the properties of aerosol particles generated over the surf zone, two experiments were held at the pier of Scripps Institution of Oceanography (SIO), La Jolla CA, and at the pier of the U.S. Army Corps of Engineers Field Research Facility (FRF) in Duck NC. On both sites concentrations of surf-generated sea spray particles, wave parameters and meteorological conditions were measured. The surf-aerosol concentrations in the diameter range 0.2-10 microns were obtained from the difference in aerosol size distributions measured upwind and downwind of the surf zone. It was found that the flux of surf-generated particles at diameters at formation can be expressed in terms of wave energy dissipation, which itself is related to the properties of the incoming wavefield and the bathymetry of the beach. Although the flux can also be modeled in terms of wind speed, this relation is considered to be not universal and limited to low- to medium wind speeds. In Duck NC, two transport experiments were performed under offshore flow conditions. In this case, the surf-aerosol concentrations were obtained from the differences in three aerosol size distributions, measured just before and just behind the surf zone and up to 16 km downwind (out to sea). No significant decrease in concentration was observed at the farthest range, which suggests that an appreciable amount of surf-generated aerosols is advected over tens of kilometers.

  6. Unique sled rig plugs oil leaking wells in surf zone

    SciTech Connect

    Zylstra, L.P. )

    1994-01-10

    Several leaking oil wells drilled in the late 1800s in the surf zone in Southern California required a specially built rig and platform for proper abandonment. The abandonment operations were complicated because the beach is heavily used by the public and the condition of the wells was unknown. A mobile sled was designed to support a drilling rig safely in the rough surf zone. The surf sled vehicle has a modular design for efficient assembly on the beach with minimal disturbance of the environment. No structures had to be built on the beach or in the surf zone to access the wellheads, thereby reducing costs and environmental impact. The surf sled vehicle used special equipment to keep the drilling rig level and to prevent oil spills or contamination during the drilling and abandonment procedures. The wells were abandoned safely and in a timely manner, despite the challenges of working in such a sensitive area. This paper describes the equipment and procedures used.

  7. Surfing into spirituality and a new, aquatic nature religion.

    PubMed

    Taylor, Bron

    2007-01-01

    "Soul surfers" consider surfing to be a profoundly meaningful practice that brings physical, psychological, and spiritual benefits. They generally agree on where surfing initially developed, that it assumed a religious character, was suppressed for religious reasons, has been undergoing a revival, and enjoins reverence for and protection of nature. This subset of the global surfing community should be understood as a new religious movement-a globalizing, hybridized, and increasingly influential example of what I call aquatic nature religion. For these individuals, surfing is a religious form in which a specific sensual practice constitutes its sacred center, and the corresponding experiences are constructed in a way that leads to a belief in nature as powerful, transformative, healing, and sacred. I advance this argument by analyzing these experiences, as well as the myths, rites, symbols, terminology, technology, material culture, and ethical mores that are found within surfing subcultures. PMID:20681093

  8. User's Manual for Space Debris Surfaces (SD_SURF)

    NASA Technical Reports Server (NTRS)

    Elfer, N. C.

    1996-01-01

    A unique collection of computer codes, Space Debris Surfaces (SD_SURF), have been developed to assist in the design and analysis of space debris protection systems. SD_SURF calculates and summarizes a vehicle's vulnerability to space debris as a function of impact velocity and obliquity. An SD_SURF analysis will show which velocities and obliquities are the most probable to cause a penetration. This determination can help the analyst select a shield design which is best suited to the predominant penetration mechanism. The analysis also indicates the most suitable parameters for development or verification testing. The SD_SURF programs offer the option of either FORTRAN programs and Microsoft EXCEL spreadsheets and macros. The FORTRAN programs work with BUMPERII version 1.2a or 1.3 (Cosmic released). The EXCEL spreadsheets and macros can be used independently or with selected output from the SD_SURF FORTRAN programs.

  9. SURF1 deficiency causes demyelinating Charcot-Marie-Tooth disease

    PubMed Central

    Ghezzi, Daniele; Chassagne, Maïté; Mayençon, Martine; Padet, Sylvie; Melchionda, Laura; Rouvet, Isabelle; Lannes, Béatrice; Bozon, Dominique; Latour, Philippe; Zeviani, Massimo; Mousson de Camaret, Bénédicte

    2013-01-01

    Objective: To investigate whether mutations in the SURF1 gene are a cause of Charcot-Marie-Tooth (CMT) disease. Methods: We describe 2 patients from a consanguineous family with demyelinating autosomal recessive CMT disease (CMT4) associated with the homozygous splice site mutation c.107-2A>G in the SURF1 gene, encoding an assembly factor of the mitochondrial respiratory chain complex IV. This observation led us to hypothesize that mutations in SURF1 might be an unrecognized cause of CMT4, and we investigated SURF1 in a total of 40 unrelated patients with CMT4 after exclusion of mutations in known CMT4 genes. The functional impact of c.107-2A>G on splicing, amount of SURF1 protein, and on complex IV activity and assembly was analyzed. Results: Another patient with CMT4 was found to harbor 2 additional SURF1 mutations. All 3 patients with SURF1-associated CMT4 presented with severe childhood-onset neuropathy, motor nerve conduction velocities <25 m/s, and lactic acidosis. Two patients had brain MRI abnormalities, including putaminal and periaqueductal lesions, and developed cerebellar ataxia years after polyneuropathy. The c.107-2A>G mutation produced no normally spliced transcript, leading to SURF1 absence. However, complex IV remained partially functional in muscle and fibroblasts. Conclusions: We found SURF1 mutations in 5% of families (2/41) presenting with CMT4. SURF1 should be systematically screened in patients with childhood-onset severe demyelinating neuropathy and additional features such as lactic acidosis, brain MRI abnormalities, and cerebellar ataxia developing years after polyneuropathy. PMID:24027061

  10. 76 FR 8651 - Special Local Regulation; Mavericks Surf Competition, Half Moon Bay, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-15

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation; Mavericks Surf Competition... the Mavericks Surf Competition. This special local regulation is necessary to ensure the safety of... dangers posed by the surf conditions during the Mavericks Surf Competition, the special local...

  11. Wave transformation across the inner surf zone

    NASA Astrophysics Data System (ADS)

    Raubenheimer, B.; Guza, R. T.; Elgar, Steve

    1996-11-01

    Sea and swell wave heights observed on transects crossing the mid and inner surf zone on three beaches (a steep concave-up beach, a gently sloped approximately planar beach, and a beach with an approximately flat terrace adjacent to a steep foreshore) were depth limited (i.e., approximately independent of the offshore wave height), consistent with previous observations. The wave evolution is well predicted by a numerical model based on the one-dimensional nonlinear shallow water equations with bore dissipation. The model is initialized with the time series of sea surface elevation and cross-shore current observed at the most offshore sensors (located about 50 to 120 m from the mean shoreline in mean water depths 0.80 to 2.10 m). The model accurately predicts the cross-shore variation of energy at both infragravity (nominally 0.004 < f < 0.05 Hz) and sea swell (here 0.05 < f ≤ 0.18 Hz) frequencies. In models of surf zone hydrodynamics, wave energy dissipation is frequently parameterized in terms of γs, the ratio of the sea swell significant wave height to the local mean water depth. The observed and predicted values of γs increase with increasing beach slope β and decreasing normalized (by a characteristic wavenumber k) water depth kh and are well correlated with β/kh, a measure of the fractional change in water depth over a wavelength. Errors in the predicted individual values of γs, are typically less than 20%. It has been suggested that infragravity motions affect waves in the sea swell band and hence γs, but this speculation is difficult to test with field observations. Numerical simulations suggest that for the range of conditions considered here, γs is insensitive to infragravity energy levels.

  12. Dwarf novae

    NASA Technical Reports Server (NTRS)

    Ladous, Constanze

    1993-01-01

    Dwarf novae are defined on grounds of their semi-regular brightness variations of some two to five magnitudes on time scales of typically 10 to 100 days. Historically several different classification schemes have been used. Today, dwarf novae are divided into three sub-classes: the U Geminorum stars, the SU Ursae Majoris stars, and the Z Camelopardalis stars. Outbursts of dwarf novae occur at semi-periodic intervals of time, typically every 10 to 100 days; amplitudes range from typically 2 to 5 mag. Within certain limits values are characteristic for each object. Relations between the outburst amplitude, or the total energy released during outburst, and the recurrence time have been found, as well as relations between the orbital period and the outburst decay time, the absolute magnitude during outburst maximum, and the widths of long and short outbursts, respectively. Some dwarf novae are known to have suspended their normal outburst activity altogether for a while. They later resumed it without having undergone any observable changes. The optical colors of dwarf novae all are quite similar during outburst, considerably bluer than during the quiescent state. During the outburst cycle, characteristic loops in the two color diagram are performed. At a time resolution on the order of minutes, strictly periodic photometric changes due to orbital motion become visible in the light curves of dwarf novae. These are characteristic for each system. Remarkably little is known about orbital variations during the course of an outburst. On time-scales of minutes and seconds, further more or less periodic types of variability are seen in dwarf novae. Appreciable flux is emitted by dwarf novae at all wavelengths from the X-rays to the longest IR wavelengths, and in some cases even in the radio. Most dwarf novae exhibit strong emission line spectra in the optical and UV during quiescence, although some have only very weak emissions in the optical and/or weak absorptions at UV wavelengths.

  13. From the Director: Surfing the Web for Health Information

    MedlinePLUS

    ... Issue Past Issues From the Director: Surfing the Web for Health Information Past Issues / Spring 2007 Table ... all information on the Internet is reliable. Some Web sites post inaccurate or biased medical information. Others ...

  14. A role for heparan sulfate in viral surfing

    SciTech Connect

    Oh, Myung-Jin; Akhtar, Jihan; Desai, Prashant; Shukla, Deepak; Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL 60612

    2010-01-01

    Heparan sulfate (HS) moieties on cell surfaces are known to provide attachment sites for many viruses including herpes simplex virus type-1 (HSV-1). Here, we demonstrate that cells respond to HSV-1 infection by enhancing filopodia formation. Filopodia express HS and are subsequently utilized for the transport of HSV-1 virions to cell bodies in a surfing-like phenomenon, which is facilitated by the underlying actin cytoskeleton and is regulated by transient activation of a small Rho GTPase, Cdc42. We also demonstrate that interaction between a highly conserved herpesvirus envelope glycoprotein B (gB) and HS is required for surfing. A HSV-1 mutant that lacks gB fails to surf and quantum dots conjugated with gB demonstrate surfing-like movements. Our data demonstrates a novel use of a common receptor, HS, which could also be exploited by multiple viruses and quite possibly, many additional ligands for transport along the plasma membrane.

  15. Uniaxial diffusion bonding of CLAM/CLAM steels: Microstructure and mechanical performance

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaosheng; Liu, Yongchang; Yu, Liming; Liu, Chenxi; Sui, Guofa; Yang, Jianguo

    2015-06-01

    By performing a two-step uniaxial diffusion bonding, the reliable joining between CLAM/CLAM steels has been attained. The microstructures at the vicinity of the joint region and in base material were respectively investigated through OM, SEM and TEM. The joint interface was integrated, and no microstructural defects were observed. In the base material, small amount of austenite is retained as thin films between martensite laths, which was suggested to be related to the compressive deformation in diffusion bonding. As a candidate structural material for the first wall in fusion energy systems, the radiation resistance of CLAM steel would be deteriorated by the retained austenite. Tensile and impact tests were carried out to assess the reliability of the joints subjected to post bond heat treatment. All the tensile specimens fractured in the base CLAM steel, meaning the good joining between CLAM steels. However, due to the low impact absorbed energy of the joints, efforts should still be made to optimize the bonding technology and the post bond heat treatment further.

  16. Continuous cooling transformation behaviors of CLAM steel

    NASA Astrophysics Data System (ADS)

    Wu, Qing-sheng; Zheng, Shu-hui; Huang, Qun-ying; Liu, Shao-jun; Han, Yang-yang

    2013-11-01

    The continuous cooling transformation (CCT) behaviors of CLAM (China Low Activation Martensitic) steel were studied, the CCT diagram was constructed, and the influence of cooling rates on the microstructures was also investigated. The microstructures were investigated using optical microscopy (OM) and microhardness tests were also carried out. The results showed that CLAM steel possessed high hardenability and there were ferrite and martensite transformation regions only. The maximum cooling rate to form ferrite microstructure was found to be 10-12 K/min. In order to obtain fully ferrite microstructure, the cooling rate should be lower than 1 K/min. The CCT diagram also gave relevant parameters such as the transformation temperatures, i.e., Ac1, Ac3, Ms and Mf were 1124 K, 1193 K, 705 K and 593 K, respectively. The diagram made it possible to predict the microstructures and properties of CLAM steel with different cooling rates. When the cooling rates ranged from 240 K/min to 12 K/min, fully martensitic transformations were achieved and the cooling rate had very little influence on the microstructure and microhardness of the martensite. The maximum cooling rate to form ferrite was 10-12 K/min. The critical cooling rate to achieve 100% ferrite was found to be lower than 1 K/min. The average temperatures of the Ac1, Ac3, Ms and Mf were 1193 K, 1124 K, 705 K and 593 K, respectively. The CCT diagram of CLAM steel was constructed with only ferrite and martensite transformation regions.

  17. Complex IV Deficient Surf1?/? Mice Initiate Mitochondrial Stress Responses

    PubMed Central

    Pulliam, Daniel A.; Deepa, Sathyaseelan S.; Liu, Yuhong; Hill, Shauna; Lin, Ai-Ling; Bhattacharya, Arunabh; Shi, Yun; Sloane, Lauren; Viscomi, Carlo; Zeviani, Massimo; Van Remmen, Holly

    2014-01-01

    Summary Mutations in SURF1 cytochrome c oxidase (COX) assembly protein are associated with Leighs syndrome, a human mitochondrial disorder that manifests as severe mitochondrial phenotypes and early lethality. In contrast, mice lacking the Surf1 protein (Surf1?/?) are viable and were previously shown to have enhanced longevity and a greater than 50% reduction in COX activity. We measured mitochondrial function in heart and skeletal muscle, and despite the significant reduction in COX activity, we found little or no difference in reactive oxygen species (ROS) generation, membrane potential, ATP production or respiration in isolated mitochondria from Surf1?/? mice compared to wild-type. However, blood lactate levels are elevated and Surf1?/? mice have reduced running endurance, suggesting compromised mitochondrial energy metabolism in vivo. Decreased COX activity in Surf1?/? mice is associated with increased markers of mitochondrial biogenesis (PGC-1? and VDAC) in both heart and skeletal muscle. While mitochondrial biogenesis is a common response in the two tissues, skeletal muscle have an up-regulation of the mitochondrial unfolded protein response (UPRMT) and heart exhibits induction of the Nrf2 antioxidant response pathway. These data are the first to report induction of the UPRMT in a mammalian model of diminished COX activity. In addition our results suggest that impaired mitochondrial function can lead to induction of mitochondrial stress pathways to confer protective effects on cellular homeostasis. Loss of complex IV assembly factor Surf1 in mice results in compensatory responses including mitochondrial biogenesis, the nrf2 pathway and the mitochondrial unfolded protein response. This compensatory response may contribute to the lack of deleterious phenotypes under basal conditions. PMID:24911525

  18. INTEGRATED SYSTEM FOR MICROALGAE NURSERY SEED CLAM CULTURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A PC-controlled integrated system for the production of algae and culture of northern quahog seed was constructed. The diatom, Chaetoceros muelleri, was cultured in covered 550-liter tanks. The harvested alga was the food source for the land-based nursery seed clam system. The nursery clam system...

  19. Freshwater clams as bioconcentrators of avian influenza virus in water.

    PubMed

    Huyvaert, Kathryn P; Carlson, Jenny S; Bentler, Kevin T; Cobble, Kacy R; Nolte, Dale L; Franklin, Alan B

    2012-10-01

    We report experimental evidence for bioconcentration of a low-pathogenicity avian influenza virus (H6N8) in the tissue of freshwater clams. Our results support the concept that freshwater clams may provide an effective tool for use in the early detection of influenza A viruses in aquatic environments. PMID:22925022

  20. Toxicity of fishery chemicals to the asiatic clam, Corbicula manilensis

    USGS Publications Warehouse

    Chandler, Jack H.; Marking, L.L.

    1979-01-01

    The Asiatic clam (Corbicula manilensis), a species introduced into U. S. waters, has spread rapidly, and its ability to survive, reproduce, and spread has caused concern. Aquatic biologists suspect that the clams may crowd out indigenous mollusks, and the animals sometimes plug water intakes and leave shell deposits that interfere with sand and gravel operations. The toxicity of 20 commonly used fishery chemicals to the Asiatic clam was determined to evaluate hazards to a nontarget aquatic invertebrate and to assess the potential of the chemicals for controlling clam populations. Among six piscicides and two lampricides tested, antimycin was most toxic to the clam; the 96-h LC50 was 0.065 mg/L. Among three therapeutants and two disinfectants tested, nifurpirinol was the most toxic; the 96-h LC50 was 7.60 mg/L. All of the compounds were less toxic to the clam than to fish. As a nontarget organism, this clam would be safe in water treated with any of the tested fishery chemicals at recommended use pattern concentrations. None of the chemicals have potential for controlling unwanted populations of these clams.

  1. Stopover habitats of spring migrating surf scoters in southeast Alaska

    USGS Publications Warehouse

    Lok, E.K.; Esler, Daniel; Takekawa, J.Y.; De La Cruz, S.W.; Sean, Boyd W.; Nysewander, D.R.; Evenson, J.R.; Ward, D.H.

    2011-01-01

    Habitat conditions and nutrient reserve levels during spring migration have been suggested as important factors affecting population declines in waterfowl, emphasizing the need to identify key sites used during spring and understand habitat features and resource availability at stopover sites. We used satellite telemetry to identify stopover sites used by surf scoters migrating through southeast Alaska during spring. We then contrasted habitat features of these sites to those of random sites to determine habitat attributes corresponding to use by migrating scoters. We identified 14 stopover sites based on use by satellite tagged surf scoters from several wintering sites. We identified Lynn Canal as a particularly important stopover site for surf scoters originating throughout the Pacific winter range; approximately half of tagged coastally migrating surf scoters used this site, many for extended periods. Stopover sites were farther from the mainland coast and closer to herring spawn sites than random sites, whereas physical shoreline habitat attributes were generally poor predictors of site use. The geography and resource availability within southeast Alaska provides unique and potentially critical stopover habitat for spring migrating surf scoters. Our work identifies specific sites and habitat resources that deserve conservation and management consideration. Aggregations of birds are vulnerable to human activity impacts such as contaminant spills and resource management decisions. This information is of value to agencies and organizations responsible for emergency response planning, herring fisheries management, and bird and ecosystem conservation. Copyright ?? 2011 The Wildlife Society.

  2. Uptake of 14C-chlorpyrifos by clams.

    PubMed

    Kale, S P; Sherkhane, P D; Murthy, N B K

    2002-11-01

    The uptake of 14C-chlorpyrifos by clams (Katalysia opima) was studied to determine the bioaccumulation potential over a period of five days. Chlorpyrifos was applied to a model ecosystem in beakers at the rate of 3 mg l(-1) of seawater. Clams showed a maximum uptake of 14C-chlorpyrifos in the first 8 hours of exposure. Subsequently these residues decreased significantly and at the end of 5 days about 1.5% of the applied activity could be recovered from the clam samples. The half-life of chlorpyrifos in this marine water system was about a day. However, after 5 days about 28% of the applied 14C-activity was present in water. This may be significant and could possibly play a role in finding the residue of this insecticide in water bodies. Clams brought about rapid degradation of chlorpyrifos in the first 48 hours. The stabilised residues in water were reflected later in clams. PMID:12472162

  3. The behaviour of giant clams (Bivalvia: Cardiidae: Tridacninae).

    PubMed

    Soo, Pamela; Todd, Peter A

    2014-01-01

    Giant clams, the largest living bivalves, live in close association with coral reefs throughout the Indo-Pacific. These iconic invertebrates perform numerous important ecological roles as well as serve as flagship species-drawing attention to the ongoing destruction of coral reefs and their associated biodiversity. To date, no review of giant clams has focussed on their behaviour, yet this component of their autecology is critical to their life history and hence conservation. Almost 100 articles published between 1865 and 2014 include behavioural observations, and these have been collated and synthesised into five sections: spawning, locomotion, feeding, anti-predation, and stress responses. Even though the exact cues for spawning in the wild have yet to be elucidated, giant clams appear to display diel and lunar periodicities in reproduction, and for some species, peak breeding seasons have been established. Perhaps surprisingly, giant clams have considerable mobility, ranging from swimming and gliding as larvae to crawling in juveniles and adults. Chemotaxis and geotaxis have been established, but giant clams are not phototactic. At least one species exhibits clumping behaviour, which may enhance physical stabilisation, facilitate reproduction, or provide protection from predators. Giant clams undergo several shifts in their mode of acquiring nutrition; starting with a lecithotrophic and planktotrophic diet as larvae, switching to pedal feeding after metamorphosis followed by the transition to a dual mode of filter feeding and phototrophy once symbiosis with zooxanthellae (Symbiodinium spp.) is established. Because of their shell weight and/or byssal attachment, adult giant clams are unable to escape rapidly from threats using locomotion. Instead, they exhibit a suite of visually mediated anti-predation behaviours that include sudden contraction of the mantle, valve adduction, and squirting of water. Knowledge on the behaviour of giant clams will benefit conservation and restocking efforts and help fine-tune mariculture techniques. Understanding the repertoire of giant clam behaviours will also facilitate the prediction of threshold levels for sustainable exploitation as well as recovery rates of depleted clam populations. PMID:25414524

  4. The Sanford Underground Research Facility at Homestake (SURF)

    NASA Astrophysics Data System (ADS)

    Lesko, K. T.

    The former Homestake gold mine in Lead, South Dakota is being transformed into a dedicated laboratory to pursue underground research in rare-process physics, as well as offering research opportunities in other disciplines. A key component of the Sanford Underground Research Facility (SURF) is the Davis Campus, which is in operation at the 4850-foot level (4300 m.w.e) and currently hosts three projects: the LUX dark matter experiment, the MAJORANA DEMONSTRATOR neutrinoless double-beta decay experiment and the Berkeley and CUBED low-background counters. Plans for possible future experiments at SURF are well underway and include long baseline neutrino oscillation experiments, future dark matter experiments as well as nuclear astrophysics accelerators. Facility upgrades to accommodate some of these future projects have already started. SURF is a dedicated facility with significant expansion capability. These plans include a Generation-2 Dark Matter experiment and the US flagship neutrino experiment, LBNE.

  5. The Sanford Underground Research Facility at Homestake (SURF)

    DOE PAGESBeta

    Lesko, K. T.

    2015-03-24

    The former Homestake gold mine in Lead, South Dakota is being transformed into a dedicated laboratory to pursue underground research in rare-process physics, as well as offering research opportunities in other disciplines. A key component of the Sanford Underground Research Facility (SURF) is the Davis Campus, which is in operation at the 4850-foot level (4300 m.w.e) and currently hosts three projects: the LUX dark matter experiment, the Majorana Demonstrator neutrinoless double-beta decay experiment and the Berkeley and CUBED low-background counters. Plans for possible future experiments at SURF are well underway and include long baseline neutrino oscillation experiments, future dark mattermore » experiments as well as nuclear astrophysics accelerators. Facility upgrades to accommodate some of these future projects have already started. SURF is a dedicated facility with significant expansion capability. These plans include a Generation-2 Dark Matter experiment and the US flagship neutrino experiment, LBNE.« less

  6. The Sanford Underground Research Facility at Homestake (SURF)

    SciTech Connect

    Lesko, K. T.

    2015-03-24

    The former Homestake gold mine in Lead, South Dakota is being transformed into a dedicated laboratory to pursue underground research in rare-process physics, as well as offering research opportunities in other disciplines. A key component of the Sanford Underground Research Facility (SURF) is the Davis Campus, which is in operation at the 4850-foot level (4300 m.w.e) and currently hosts three projects: the LUX dark matter experiment, the Majorana Demonstrator neutrinoless double-beta decay experiment and the Berkeley and CUBED low-background counters. Plans for possible future experiments at SURF are well underway and include long baseline neutrino oscillation experiments, future dark matter experiments as well as nuclear astrophysics accelerators. Facility upgrades to accommodate some of these future projects have already started. SURF is a dedicated facility with significant expansion capability. These plans include a Generation-2 Dark Matter experiment and the US flagship neutrino experiment, LBNE.

  7. Synchrotron ultraviolet radiation facility (SURF II) radiometric instrumentation calibration facility

    SciTech Connect

    Furst, M.L.; Graves, R.M.; Madden, R.P. )

    1993-11-01

    Spectrometer calibrations have been performed at the National Institute of Standards and Technology (formerly the National Bureau of Standards) for over 10 yr using the calculable synchrotron radiation from the SURF 2 electron storage ring. SURF 2 is not a high-performance storage ring that can operate at electron energies up to 300 MeV and with over 250 mA of stored current. One beam line, operationally supported by the National Aeronautics and Space Administration (NASA), is dedicated for use as a radiometric instrumentation calibration facility for outside users.

  8. Manila clam Venerupis philippinarum as a biomonitor to metal pollution

    NASA Astrophysics Data System (ADS)

    Wu, Huifeng; Ji, Chenglong; Wang, Qing; Liu, Xiaoli; Zhao, Jianmin; Feng, Jianghua

    2013-01-01

    The Manila clam Venerupis philippinarum is a good biomonitor/bioindicator to marine metal pollution and is frequently used in aquatic toxicology. Two dominant pedigrees (white and zebra) of clam are distributed in the Bohai Sea; however, little attention has been paid to potential biological differences between these two pedigrees. In this study, we tested the sensitivity of both pedigrees to marine metal (cadmium and zinc) pollution biomonitoring and marine environmental toxicology. Results demonstrate significant biological differences in gills of white and zebra clams based on metabolic profiles and antioxidant enzyme activities. In addition, we found that hypotaurine, malonate and homarine were relatively high in white clam gills, while alanine, arginine, glutamate, succinate, 4-aminobutyrate, taurine and betaine were high in zebra clam gills. Zebra clam gills were also more sensitive to a mixture of Cd and Zn, as shown by antioxidant enzyme activities and metabolic profiles, but white clam gills could accumulate more Zn. Therefore, we suggest that the white pedigree can be used as a biomonitor to marine Zn pollution, whereas the zebra pedigree can be used for toxicology studies on Cd and Zn mixed pollution.

  9. Gaia and white dwarf - brown dwarf binaries .

    NASA Astrophysics Data System (ADS)

    Casewell, S. L.

    White dwarf-brown dwarf binaries are excellent benchmark systems, as the white dwarf provides an accurate (although model dependent) age calibrator for the brown dwarf. While these systems are rare, with authors suggesting the frequency to be between 0.5 and 2 %, they are being used to provide ages for the coolest brown dwarfs (e.g. WD0806-661) and also as testbeds for irradiated atmospheres. Gaia is estimated to detect ˜2000 of these systems using astrometry, enlarging the sample, and allowing limits to be placed on the brown dwarf desert.

  10. Internet Surfing for Kindergarten Children: A Feasibility Study

    ERIC Educational Resources Information Center

    Loo, Alfred

    2012-01-01

    The Internet is an effective learning tool for gifted children because it allows them to independently select the areas in which they have talent. The Internet also enables children to discover and maximize their potential. However, younger children might not have a large enough vocabulary to surf the Internet, even if they are gifted. For

  11. "Surfing Global Change": How Didactic Visions Can Be Implemented

    ERIC Educational Resources Information Center

    Ahamer, Gilbert

    2005-01-01

    Purpose: Aims to examine a negotiation-oriented and partly web-based game "Surfing Global Change" (SGC) invented by the author based on didactics of self-managed learning and successfully implemented in WebCT. Design/methodology/approach: Along three historic generations of web-based teaching (WBT), the key functionalities of any platform…

  12. Collaboration on ICT in Dutch Higher Education: The SURF Approach

    ERIC Educational Resources Information Center

    Boezerooy, Petra; Cordewener, Bas; Liebrand, Wim

    2007-01-01

    In "Thinking Ahead: A Vision of the Role of ICT in Education and Research in the Future, 2007-2010," the higher education institutions in the Netherlands agreed on future strategy. Under the direction of SURF, the Dutch national organization, a collaborative strategy for the application of information and communications technology (ICT) was

  13. Safety Strategies While Surfing Online in the Classroom.

    ERIC Educational Resources Information Center

    Demirbilek, Muhammet; Cilesiz, Sebnem; Tozoglu, Dogan

    The Internet has become an indispensable medium of the 21st century. Millions of people are using the Internet for exchanging information, surfing for information on virtually any topic, communicating all over the world, participating in discussion groups, shopping, traveling, and many other online activities. The World Wide Web is constantly

  14. Assimilation of Remote Sensing Observations to Estimate Surf Zone Bathymetry

    NASA Astrophysics Data System (ADS)

    Wilson, G.; zkan-Haller, H. T.; Holman, R. A.

    2012-12-01

    The surf zone (defined as the coastal ocean region where wave breaking dominates the dynamics) is a highly energetic region with large spatial/temporal variability - a challenging environment for in-situ observation. Hence, remote sensing (usually land-based) plays an important role in surf zone research. Recent progress in surf zone remote sensing shows a trend towards increasingly quantitative data products, for example remotely sensed estimates of wavefield properties and time-averaged currents - data which can be directly compared to numerical model predictions. As these new products become mature, it is easy to envision them being integrated into forecasts of surf zone waves and currents. In particular, one wonders whether such data can help to reduce uncertainty in nearshore bathymetry, which is a key source of error in models due to its rapid evolution and complex physics. To that end, we have developed an ensemble-based sequential data assimilation system which corrects for bathymetric error by assimilating remote sensing observations of waves and currents. Data (both in-situ and remotely sensed) from a 2010 field experiment at Duck, NC, has been used to calibrate and test this system, showing it is capable of reducing bathymetric error over time and improving forecasts. We present these results, as well as the details of the modeling system and the data.

  15. Internet Surfing for Kindergarten Children: A Feasibility Study

    ERIC Educational Resources Information Center

    Loo, Alfred

    2012-01-01

    The Internet is an effective learning tool for gifted children because it allows them to independently select the areas in which they have talent. The Internet also enables children to discover and maximize their potential. However, younger children might not have a large enough vocabulary to surf the Internet, even if they are gifted. For…

  16. CoBrowser: Surfing the Web Using a Standard Browser.

    ERIC Educational Resources Information Center

    Maly, K.; Zubair, M.; Li, L.

    Co-browsing is a synchronous class of collaborative applications, which allows a group of users to surf the Web together. Such an application can be deployed in an education environment in several ways. One example of where it can be used would be in courses that are project-oriented. Students would be required to collectively research or explore…

  17. Women's Recreational Surfing: A Patronising Experience

    ERIC Educational Resources Information Center

    Olive, Rebecca; McCuaig, Louise; Phillips, Murray G.

    2015-01-01

    Research analysing the operation of power within sport and physical activity has exposed the marginalisation and exclusion of women's sport in explicit and institutionalised ways. However, for women in recreational and alternative physical activities like surfing, sporting experiences lie outside institutionalised structures, thus requiring…

  18. Women's Recreational Surfing: A Patronising Experience

    ERIC Educational Resources Information Center

    Olive, Rebecca; McCuaig, Louise; Phillips, Murray G.

    2015-01-01

    Research analysing the operation of power within sport and physical activity has exposed the marginalisation and exclusion of women's sport in explicit and institutionalised ways. However, for women in recreational and alternative physical activities like surfing, sporting experiences lie outside institutionalised structures, thus requiring

  19. Juvenile Surf Smelt Surveys in Central Puget Sound, Washington

    USGS Multimedia Gallery

    USGS Western Fisheries Research Center scientists Lisa Gee, Collin Smith, and Ryan Tomka display a bycatch of perch collected in a beach seine while conducting a survey for juvenile surf smelt on Bainbridge Island, WA. Washington's Puget Sound is a complex ecosystem directly adjacent to a robust me...

  20. Juvenile Surf Smelt Surveys in Central Puget Sound, Washington

    USGS Multimedia Gallery

    USGS Western Fisheries Research Center scientists haul a beach seine over an eelgrass bed while conducting a survey for juvenile surf smelt on Bainbridge Island, WA. Washington's Puget Sound is a complex ecosystem directly adjacent to a robust metropolitan area that scientists from the USGS Western...

  1. Juvenile Surf Smelt Surveys in Central Puget Sound, Washington

    USGS Multimedia Gallery

    USGS Western Fisheries Research Center scientists identify fish collected in a beach seine while conducting a survey for juvenile surf smelt on Bainbridge Island, WA. Washington's Puget Sound is a complex ecosystem directly adjacent to a robust metropolitan area that scientists from the USGS Wester...

  2. Razor clam to RoboClam: burrowing drag reduction mechanisms and their robotic adaptation.

    PubMed

    Winter, A G; V; Deits, R L H; Dorsch, D S; Slocum, A H; Hosoi, A E

    2014-09-01

    Estimates based on the strength, size, and shape of the Atlantic razor clam (Ensis directus) indicate that the animal's burrow depth should be physically limited to a few centimeters; yet razor clams can dig as deep as 70cm. By measuring soil deformations around burrowing E. directus, we have found the animal reduces drag by contracting its valves to initially fail, and then fluidize, the surrounding substrate. The characteristic contraction time to achieve fluidization can be calculated directly from soil properties. The geometry of the fluidized zone is dictated by two commonly-measured geotechnical parameters: coefficient of lateral earth pressure and friction angle. Calculations using full ranges for both parameters indicate that the fluidized zone is a local effect, occurring between 1-5 body radii away from the animal. The energy associated with motion through fluidized substrate-characterized by a depth-independent density and viscosity-scales linearly with depth. In contrast, moving through static soil requires energy that scales with depth squared. For E. directus, this translates to a 10X reduction in the energy required to reach observed burrow depths. For engineers, localized fluidization offers a mechanically simple and purely kinematic method to dramatically reduce energy costs associated with digging. This concept is demonstrated with RoboClam, an E. directus-inspired robot. Using a genetic algorithm to find optimal digging kinematics, RoboClam has achieved localized fluidization burrowing performance comparable to that of the animal, with a linear energy-depth relationship, in both idealized granular glass beads and E. directus' native cohesive mudflat habitat. PMID:24713848

  3. Modeling surf zone-inner shelf exchange: Interaction of rip currents and stratification

    NASA Astrophysics Data System (ADS)

    Kumar, N.; Feddersen, F.

    2014-12-01

    Transient rip currents on alongshore uniform beaches develop from the coalescence of surf zone eddies, exchanging tracers between the surf zone and the potentially stratified inner shelf. The interaction of stratification and transient rip currents has not yet been investigated. Surf zone eddies responsible for transient rip currents are generated by short-crested wave breaking, a process included in wave-resolving (WR) Boussinesq models. However, WR models are depth-integrated and cannot account for stratification and vertically sheared flows. Wave-averaged (WA) models can simulate these processes, but cannot create surf zone eddies. A combination of WR and WA models is required to accurately simulate surf zone-inner shelf exchange. Here, WR depth-integrated Boussinessq model funwaveC is coupled to the stratification and depth-resolving WA Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system. The surf zone eddy generation forcing is extracted from a funwaveC simulation of normally incident waves on a planar beach, and provided to COAWST as a depth-uniform surf zone force. COAWST model simulations resolving the surf zone to mid-shelf are conducted with surf zone eddy forcing, idealistic surface heating/cooling, stratification, and Coriolis effects. These simulations provide three-dimensional evolution of velocity and temperature, diagnosed to quantify the role of surf zone eddy forcing in surf zone-inner shelf exchange. The impact of stratification on rip currents and exchange is studied by varying the stratification. Funded by the Office of Naval Research.

  4. A Lagrangian stochastic model of surf zone drifter dispersion

    NASA Astrophysics Data System (ADS)

    Spydell, Matthew S.; Feddersen, Falk

    2012-03-01

    Drifter-derived cross-shore and alongshore surf zone diffusivities were previously estimated on an alongshore uniform beach over 1000 s for five Huntington Beach, California, 2006 (HB06) experiment release days. The cross-shore diffusivity Kx had a nonmonotonic time dependence, potentially due to the shoreline or to weaker diffusivity seaward of the surf zone. The alongshore diffusivities Ky were qualitatively consistent with shear dispersion but differed from the classic Taylor laminar theory. Here, modeled and analytic diffusivities for the five release days are derived from a Lagrangian stochastic model (LSM) that uses the drifter-derived bulk (cross-shore averaged) velocity variance and cross-shore-dependent mean alongshore current. The LSM modeled and analytic cross-shore diffusivities are nonmonotonic due to the shoreline and strongly suggest that the observed cross-shore diffusivity is shoreline affected. The LSM typically reproduce well the observed Kx with Lagrangian time scale between 75 and 200 s, consistent with surf zone eddy time scales. HB06 drifter trajectories were too short to observe the analytic long-time Kx limit, and weaker diffusivity seaward of the surf zone may be important at longer times (>1000 s). On all release days, the LSM model and analytic alongshore diffusivity reproduce well the observed Ky with alongshore Lagrangian time scales between 95 and 155 s. The isolated shear-induced diffusivity is very well represented by an analytic theory which incorporates a nonzero Lagrangian time scale. Many of the stochastic model parameters can be specified a priori with reasonable assumptions to predict surf zone dispersion of an initial value problem pollution spill.

  5. Characterisation of the secretome of the clam parasite, QPX.

    PubMed

    Rubin, Ewelina; Pales Espinosa, Emmanuelle; Koller, Antonius; Allam, Bassem

    2015-02-01

    Secreted and cell surface-associated molecules play a major role in disease development processes and host-pathogen interactions, and usually determine the virulence of invading organisms. In this study, we investigated proteins secreted by quahog parasite unknown, a thraustochytrid protist that infects the hard clam, Mercenaria mercenaria. In silico analysis of quahog parasite unknown transcripts predicted over 1200 proteins to possess an amino-terminal signal peptide which directs proteins into the classical eukaryotic secretory pathway. Proteomic analysis using LC/MS technology identified 56 proteins present in the extracellular secretion of quahog parasite unknown cells grown in vitro, including six mucin-like molecules, four glycosyl hydrolases and eight peptidases. Transcription levels of 19 quahog parasite unknown extracellular proteins were investigated in clam tissue lesions (in vivo) using quantitative PCR. The overexpression of six of these extracellular proteins in clam tissues compared with in vitro cultures suggests that they are involved in interaction with the clam host. PMID:25558055

  6. Clam predator protection is effective and necessary for food production.

    PubMed

    Munroe, Daphne; Kraeuter, John; Beal, Brian; Chew, Ken; Luckenbach, Mark; Peterson, Charles P

    2015-11-15

    Shellfish aquaculture is a widely practiced way of producing food for human consumption in coastal areas. When farming intertidal clams, farmers commonly protect young seedling clams from predatory losses by covering farmed plots with netting or screening. Recent discussion of the effectiveness of protective nets or screens and their environmental effects has raised questions concerning the utility of the practice. We provide data based on a review of more than 35 peer-reviewed articles, as well as our own research that demonstrates the efficacy of predator protection for clam farms in various habitats around the world. In addition, we evaluate the effects of screening on temperature, and comment on ancient practices of clam gardening as conducted in the Pacific Northwest. PMID:26433775

  7. Detection of multiple human sapoviruses from imported frozen individual clams.

    PubMed

    Iizuka, Setsuko; Takai-Todaka, Reiko; Ohshiro, Hitoshi; Kitajima, Masaaki; Wang, Qiuhong; Saif, Linda J; Wakita, Takaji; Noda, Mamoru; Katayama, Kazuhiko; Oka, Tomoichiro

    2013-06-01

    Sapovirus (SaV), a member of the family Caliciviridae, is an important acute gastroenteritis pathogen in humans. Consumption of raw or inadequately cooked clams is one transmission route of human SaV. Sixty individual clams (Ruditapes philippinarum) were from market and tested for human SaVs using two nested reverse transcription-polymerase chain reaction (RT-PCR) assays, one of which was recently developed and effectively detected human SaV from environmental water samples. The nested RT-PCR effective for water samples showed a higher detection rate (68.3 %, 41 of 60 clams) than the other nested RT-PCR (43.3 %, 26 of 60 clams). Based on the sequence analysis of the partial capsid region, SaV strains detected in this study were classified into nine genotypes: GI.1, GI.3, GI.5, GI.6, GI.7, GII.3, GII.4, GIV.1, and GV.1. We demonstrated for the first time the presence of multiple genogroups and/or genotypes of SaV strains in the individual clams. Using a more sensitive assay such as we described to test individual clam samples will help to identify the source of a SaV-gastroenteritis outbreak. PMID:23526313

  8. Brown Dwarf Companions to White Dwarfs

    NASA Astrophysics Data System (ADS)

    Burleigh, Matt R.; Steele, Paul R.; Dobbie, Paul D.; Farihi, Jay; Napiwotzki, Ralf; Maxted, Pierre F. L.; Barstow, Martin A.; Jameson, Richard F.; Casewell, Sarah L.; Gaensicke, Boris T.; Marsh, Tom R.

    2011-03-01

    Brown dwarf companions to white dwarfs are rare, but recent infra-red surveys are slowly revealing examples. We present new observations of the post-common envelope binary WD0137-349, which reveals the effects of irradiation on the ~0.05Msolar secondary, and new observations of GD1400 which show that it too is a close, post-common envelope system. We also present the latest results in a near-infrared photometric search for unresolved ultra-cool companions and to white dwarfs with UKIDSS. Twenty five DA white dwarfs were identified as having photometric excesses indicative of a low mass companion, with 8-10 of these having a predicted mass in the range associated with brown dwarfs. The results of this survey show that the unresolved (<2'') brown dwarf companion fraction to DA white dwarfs is 0.3<=ƒWD+BD<=1.3%.

  9. Ultraviolet degradation study of photomultiplier tubes at SURF III

    NASA Astrophysics Data System (ADS)

    Hum, Lindsay; Shaw, Ping-Shine; Li, Zhigang; Lykke, Keith R.; Bishop, Michael L.

    2009-05-01

    Photomultiplier tubes (PMTs) are used in biological detection systems in order to detect the presence of biological warfare agents. To ensure proper operation of these biological detection systems, the performance of PMTs must be characterized in terms of their responsivity and long-term stability. We report a technique for PMT calibration at the Synchrotron Ultraviolet Radiation Facility (SURF III) at the National Institute of Standards and Technology (NIST). SURF III provides synchrotron radiation with a smooth and continuous spectrum covering the entire UV range for accurate PMT measurements. By taking advantage of the ten decade variability in the flux of the synchrotron radiation, we studied properties of commercial PMTs such as the linearity, spatial uniformity, and spectral responsivity. We demonstrate the degradation of PMTs by comparing new PMTs with PMTs that were used and operated in a biological detection system for a long period of time. The observed degradation is discussed.

  10. Region duplication forgery detection technique based on SURF and HAC.

    PubMed

    Mishra, Parul; Mishra, Nishchol; Sharma, Sanjeev; Patel, Ravindra

    2013-01-01

    Region duplication forgery detection is a special type of forgery detection approach and widely used research topic under digital image forensics. In copy move forgery, a specific area is copied and then pasted into any other region of the image. Due to the availability of sophisticated image processing tools, it becomes very hard to detect forgery with naked eyes. From the forged region of an image no visual clues are often detected. For making the tampering more robust, various transformations like scaling, rotation, illumination changes, JPEG compression, noise addition, gamma correction, and blurring are applied. So there is a need for a method which performs efficiently in the presence of all such attacks. This paper presents a detection method based on speeded up robust features (SURF) and hierarchical agglomerative clustering (HAC). SURF detects the keypoints and their corresponding features. From these sets of keypoints, grouping is performed on the matched keypoints by HAC that shows copied and pasted regions. PMID:24311972

  11. UV/VUV radiometric calibrations at SURF II

    NASA Technical Reports Server (NTRS)

    Furst, Mitchell L.; Canfield, L. R.

    1993-01-01

    Since 1981 more than 150 instrument calibrations have been performed on the radiometric instrumentation calibration beamline at the Synchrotron Ultraviolet Radiation Facility (SURF II) at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland. This 300 MeV electron storage ring operates routinely at electron currents greater than 250 mA. The spectrometer calibration beamline provides a continuum of radiation from 4 nm through the visual spectral region in the form of an intense beam with total angular divergence of 1.2 mrad. The probable uncertainty for the flux ranges from about 5 percent at 4 nm to less than 2 percent above 20 nm. The new system will radiometrically trace to SURF II, and thus is expected to reduce the calibration uncertainty for diodes in this region by a factor of five to the 1-2 percent level.

  12. Distinguishing high surf from volcanic long-period earthquakes

    NASA Astrophysics Data System (ADS)

    Lyons, John J.; Haney, Matthew M.; Fee, David; Paskievitch, John F.

    2014-02-01

    Repeating long-period (LP) earthquakes are observed at active volcanoes worldwide and are typically attributed to unsteady pressure fluctuations associated with fluid migration through the volcanic plumbing system. Nonvolcanic sources of LP signals include ice movement and glacial outburst floods, and the waveform characteristics and frequency content of these events often make them difficult to distinguish from volcanic LP events. We analyze seismic and infrasound data from an LP swarm recorded at Pagan volcano on 12-14 October 2013 and compare the results to ocean wave data from a nearby buoy. We demonstrate that although the events show strong similarity to volcanic LP signals, the events are not volcanic but due to intense surf generated by a passing typhoon. Seismo-acoustic methods allow for rapid distinction of volcanic LP signals from those generated by large surf and other sources, a critical task for volcano monitoring.

  13. The surf zone heat budget: The effect of wave heating

    NASA Astrophysics Data System (ADS)

    Sinnett, Gregory; Feddersen, Falk

    2014-10-01

    Surf zone incident wave energy flux is dissipated by wave breaking which through viscosity generates heat. This effect is not present in shelf heat budgets and has not previously been considered. Pier-based observations of water temperature in 1-4 m depth, meteorology, and waves are used to test a surf zone heat budget, which closes on diurnal and longer time scales. Wave energy flux is the second most variable term with mean contribution one fourth of the mean short-wave radiation. The heat budget residual has semidiurnal and higher-frequency variability and net cooling. Cross-shore advective heat flux driven by internal wave events, rip currents, and undertow contribute to this residual variability and net cooling. In locations with large waves, steeper beaches, or less solar radiation, the ratio of wave energy flux to short-wave radiation may be >1.

  14. SURF IA Conflict Detection and Resolution Algorithm Evaluation

    NASA Technical Reports Server (NTRS)

    Jones, Denise R.; Chartrand, Ryan C.; Wilson, Sara R.; Commo, Sean A.; Barker, Glover D.

    2012-01-01

    The Enhanced Traffic Situational Awareness on the Airport Surface with Indications and Alerts (SURF IA) algorithm was evaluated in a fast-time batch simulation study at the National Aeronautics and Space Administration (NASA) Langley Research Center. SURF IA is designed to increase flight crew situation awareness of the runway environment and facilitate an appropriate and timely response to potential conflict situations. The purpose of the study was to evaluate the performance of the SURF IA algorithm under various runway scenarios, multiple levels of conflict detection and resolution (CD&R) system equipage, and various levels of horizontal position accuracy. This paper gives an overview of the SURF IA concept, simulation study, and results. Runway incursions are a serious aviation safety hazard. As such, the FAA is committed to reducing the severity, number, and rate of runway incursions by implementing a combination of guidance, education, outreach, training, technology, infrastructure, and risk identification and mitigation initiatives [1]. Progress has been made in reducing the number of serious incursions - from a high of 67 in Fiscal Year (FY) 2000 to 6 in FY2010. However, the rate of all incursions has risen steadily over recent years - from a rate of 12.3 incursions per million operations in FY2005 to a rate of 18.9 incursions per million operations in FY2010 [1, 2]. The National Transportation Safety Board (NTSB) also considers runway incursions to be a serious aviation safety hazard, listing runway incursion prevention as one of their most wanted transportation safety improvements [3]. The NTSB recommends that immediate warning of probable collisions/incursions be given directly to flight crews in the cockpit [4].

  15. Fatal accidents due to train surfing in Berlin.

    PubMed

    Strauch, H; Wirth, I; Geserick, G

    1998-06-01

    This study was undertaken for the purpose of analysing under the aspect of legal medicine, fatal accidents due to train surfing in the local transport system of Berlin (S-Bahn and underground). The period of investigation was from 1989 through 1995, with 41 train surfing accidents, among them 18 with fatal outcome. Evaluation included those 14 deaths which were forensically autopsied. It was based on autopsy records of Berlin-based university institutes (Humboldt University and Free University) as well as the Brandenburg State Institute of Legal Medicine. Also used were data obtained from the Berlin Transport Police Record. The casualties were aged between 13 and 25 years, most of them between 16 and 20. The male-female gender ratio was 13:1. Accidents occurred above all in the warmer season of the year, most of them between 20:00 h and midnight. More than 50% of all cases were affected by alcohol, but centrally acting medicaments or other addictive drugs were not noticed at all. Most of the fatal accidents occurred to users of the Berlin S-Bahn network. Older train models were the preferred surfing objects due to their structural peculiarities. Collision with close-to-track obstacles and slipping from the train proved to be the major sources of danger. An analysis of injuries revealed polytraumatisation but for one exception, with craniocerebral injuries being the most common and severest events. The longest survival time amounted to 24 h. As the psychosocial causes of high-risk behaviour of adolescents will hardly be controllable, withdrawal of technical, that is structural design possibilities appears to be the most important approach to prevention of accidents in the future. This demand is met by the new series of the Berlin S-Bahn. The model of the old series, suitable for surfing, still accounts for about 10% of the rolling stock and is to be decommissioned in 1998. PMID:9670490

  16. Stern-Gerlach surfing in laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Flood, Stephen P.; Burton, David A.

    2015-09-01

    We investigate the effects of a Stern-Gerlach-type addition to the Lorentz force on electrons in a laser wakefield accelerator. The Stern-Gerlach-type terms are found to generate a family of trajectories describing electrons that 'surf' along the plasma density wave driven by a laser pulse. Such trajectories could lead to an increase in the size of an electron bunch, which may have implications for attempts to exploit such bunches in future free electron lasers.

  17. MISR Browse Images: Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS)

    Atmospheric Science Data Center

    2013-03-22

    MISR Browse Images: Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) ... visual overview of the region observed during the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) field campaign. ...

  18. Sea spray aerosol and wave energy dissipation in the surf zone

    NASA Astrophysics Data System (ADS)

    Francius, M. J.; Piazolla, J.; Forget, P.; Le Calve, O.; Kusmierczyk-Michulec, J.

    2007-09-01

    Results from a quantitative model for the prediction of the sea-salt mass flux produced in the surf zone are presented in this paper. The model relates the surf zone sea salt mass flux to the amount of wave energy dissipated in the surf zone. In order to apply this aerosol emission model, a wave numerical model is required to obtain estimates for the total wave energy dissipated in the surf zone, as well as for the width of the surf zone. In the present work, we show using different wave models that the aerosol emission model is not sensitive to the details of the formulation of the wave model, provided a clear definition for the width of surf zone is adopted and the calibration of the numerical models is properly done.

  19. Ancient Clam Gardens Increased Shellfish Production: Adaptive Strategies from the Past Can Inform Food Security Today

    PubMed Central

    Groesbeck, Amy S.; Rowell, Kirsten; Lepofsky, Dana; Salomon, Anne K.

    2014-01-01

    Maintaining food production while sustaining productive ecosystems is among the central challenges of our time, yet, it has been for millennia. Ancient clam gardens, intertidal rock-walled terraces constructed by humans during the late Holocene, are thought to have improved the growing conditions for clams. We tested this hypothesis by comparing the beach slope, intertidal height, and biomass and density of bivalves at replicate clam garden and non-walled clam beaches in British Columbia, Canada. We also quantified the variation in growth and survival rates of littleneck clams (Leukoma staminea) we experimentally transplanted across these two beach types. We found that clam gardens had significantly shallower slopes than non-walled beaches and greater densities of L. staminea and Saxidomus giganteus, particularly at smaller size classes. Overall, clam gardens contained 4 times as many butter clams and over twice as many littleneck clams relative to non-walled beaches. As predicted, this relationship varied as a function of intertidal height, whereby clam density and biomass tended to be greater in clam gardens compared to non-walled beaches at relatively higher intertidal heights. Transplanted juvenile L. staminea grew 1.7 times faster and smaller size classes were more likely to survive in clam gardens than non-walled beaches, specifically at the top and bottom of beaches. Consequently, we provide strong evidence that ancient clam gardens likely increased clam productivity by altering the slope of soft-sediment beaches, expanding optimal intertidal clam habitat, thereby enhancing growing conditions for clams. These results reveal how ancient shellfish aquaculture practices may have supported food security strategies in the past and provide insight into tools for the conservation, management, and governance of intertidal seascapes today. PMID:24618748

  20. A real-time FPGA-based architecture for OpenSURF

    NASA Astrophysics Data System (ADS)

    Chen, Chaoxiu; Yong, Huang; Zhong, Sheng; Yan, Luxin

    2015-12-01

    This paper proposes a low-cost FPGA architecture of Speed-Up Robust Features (SURF) algorithm based on OpenSURF. It optimizes the computing architecture for the steps of feature detection and feature description involved in SURF to reduce the resource utilization and improve processing speed. As a result, this architecture can detect feature and extract descriptor from video streams of 800x600 resolutions at 60 frames per second (60fps). Extensive experiments have demonstrated its efficiency and effectiveness.

  1. 40 CFR 408.240 - Applicability; description of the mechanized clam processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... mechanized clam processing subcategory. 408.240 Section 408.240 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Clam Processing Subcategory 408.240 Applicability; description of the mechanized clam processing subcategory. The provisions of this subpart are applicable to discharges...

  2. 40 CFR 408.240 - Applicability; description of the mechanized clam processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... mechanized clam processing subcategory. 408.240 Section 408.240 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Clam Processing Subcategory 408.240 Applicability; description of the mechanized clam processing subcategory. The provisions of this subpart are applicable to discharges...

  3. 40 CFR 408.230 - Applicability; description of the hand-shucked clam processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-shucked clam processing subcategory. 408.230 Section 408.230 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Hand-Shucked Clam Processing Subcategory 408.230 Applicability; description of the hand-shucked clam processing subcategory. The provisions of this subpart are applicable to discharges...

  4. 40 CFR 408.230 - Applicability; description of the hand-shucked clam processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-shucked clam processing subcategory. 408.230 Section 408.230 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Hand-Shucked Clam Processing Subcategory 408.230 Applicability; description of the hand-shucked clam processing subcategory. The provisions of this subpart are applicable to discharges...

  5. 40 CFR 408.240 - Applicability; description of the mechanized clam processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... mechanized clam processing subcategory. 408.240 Section 408.240 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Clam Processing Subcategory 408.240 Applicability; description of the mechanized clam processing subcategory. The provisions of this subpart are applicable to discharges...

  6. 40 CFR 408.230 - Applicability; description of the hand-shucked clam processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-shucked clam processing subcategory. 408.230 Section 408.230 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Hand-Shucked Clam Processing Subcategory 408.230 Applicability; description of the hand-shucked clam processing subcategory. The provisions of this subpart are applicable to discharges...

  7. 40 CFR 408.240 - Applicability; description of the mechanized clam processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... mechanized clam processing subcategory. 408.240 Section 408.240 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Clam Processing Subcategory 408.240 Applicability; description of the mechanized clam processing subcategory. The provisions of this subpart are applicable to discharges...

  8. 40 CFR 408.240 - Applicability; description of the mechanized clam processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... mechanized clam processing subcategory. 408.240 Section 408.240 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Clam Processing Subcategory 408.240 Applicability; description of the mechanized clam processing subcategory. The provisions of this subpart are applicable to discharges...

  9. 40 CFR 408.230 - Applicability; description of the hand-shucked clam processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-shucked clam processing subcategory. 408.230 Section 408.230 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Hand-Shucked Clam Processing Subcategory 408.230 Applicability; description of the hand-shucked clam processing subcategory. The provisions of this subpart are applicable to discharges...

  10. 40 CFR 408.230 - Applicability; description of the hand-shucked clam processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-shucked clam processing subcategory. 408.230 Section 408.230 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Hand-Shucked Clam Processing Subcategory 408.230 Applicability; description of the hand-shucked clam processing subcategory. The provisions of this subpart are applicable to discharges...

  11. An efficient method of noroviruses recovery from oysters and clams

    NASA Astrophysics Data System (ADS)

    Zhou, Deqing; Ma, Liping; Zhao, Feng; Yao, Lin; Su, Laijin; Li, Xinguang

    2013-03-01

    Noroviruses (NoVs) are widespread causes of nonbacterial gastroenteritis. Outbreaks of NoVs caused diseases are commonly ascribed to the consumption of contaminated shellfish. The concentration and RNA extraction of NoVs are crucial steps of detecting NoVs in shellfish. This study aimed to select a simple, rapid and highly efficient recovery method of NoVs detection with real-time RT-PCR. Four methods of recovering GI.3 and GII.4 NoVs from spiked digestive tissues of oysters and clams, respectively, were compared, of them, the method involving proteinase K and PEG 8000 was found the most efficient. With this method, 9.3% and 13.1% of GI.3 and GII.4 NoVs were recovered from oysters and 9.6% and 12.3% of GI.3 and GII.4 NoVs were recovered from clams, respectively. This method was further used to detect NoVs in 84 oysters ( Crassostrea gigas) and 86 clams ( Ruditapes philippinarum) collected from 10 coastal cities in China from Jan. 2011 to Feb. 2012. The NoVs isolation rates were 10.47% of clams (9/86) and 7.14% of oysters (6/84). All the detected NoVs belonged to genotype GII. The NoVs recovery method selected is efficient for NoVs detection in oysters and clams.

  12. Toxicity of a traditional molluscicide to asian clam veligers

    USGS Publications Warehouse

    Layhee, Megan J.; Miho Yoshioka; Miho Yoshioka; Bahram Farokhkish; Bahram Farokhkish; Gross, Jackson A.; Sepulveda, Adam J.

    2014-01-01

    Aquaculture and hatchery industries are in need of effective control methods to reduce the risk of spreading aquatic invasive species, such as the Asian clam Corbicula fluminea, through aquaculture and hatchery activities. The planktonic nature of Asian clam veligers enables this life stage to enter water-based infrastructure undetected, including hatchery trucks used to stock fish. Once in hatchery trucks, veligers can disperse overland and establish in previously uninvaded habitats. As a result, there is a need to develop techniques that result in veliger mortality but do not harm fish. In September 2012, we conducted laboratory trials to determine if a molluscicide (750 mg/L potassium chloride and 25 mg/L formalin) commonly used to kill zebra mussel (Dreissena polymorpha) veligers in hatchery trucks can also effectively kill Asian clam veligers. We exposed Asian clam veligers to this molluscicide for 1, 3, and 5 h in each of two water types: deionized water and filtered lake water. We found ,20% mortality at the 1-h exposure period and 100% mortality at both the 3-h and 5-h exposure periods, regardless of water type. This laboratory study represents an important step toward reducing the spread of Asian clams by aquaculture facilities.

  13. Effect of low salinity on the yellow clam Mesodesma mactroides.

    PubMed

    Carvalho, Y B M; Romano, L A; Poersch, L H S

    2015-01-01

    The aim of this study was to determine the lethal salinity (LC50) for the yellow clam Mesodesma mactroides (Bivalvia: Mesodesmatidae) and identify histopathological alterations that could be used to diagnose structural changes in clam tissue. Clams in two size classes (adults and juveniles) were placed in 10 L chambers and exposed to salinities of 35, 30, 25, 20, 15, 10, and 5 g/L. There were triplicate chambers with seven clams each for each salinity. The LC50 values for a 48 h exposure were 6.5 g/L and 5.7 g/L for adults and juveniles, respectively. For a 96 h exposure, the LC50 values were 10.5 g/L for adults and 8.8 g/L for juveniles. The histological examination of yellow clams exposed to 10 g/L for 96 h showed intercellular oedema and necrotic foci in the epithelium of the digestive gland and occlusion of the lumen of the digestive gland. In conclusion, M. mactroides can be characterised as a moderately euryhaline species, tolerating salinities from 35 to 15 g/L. PMID:25945615

  14. Deployed bivalves (oysters and clams) as indicators of estuarine condition

    SciTech Connect

    Ringwood, A.H.; Holland, A.F.; Keppler, C.; Wert, M.; Hyland, J.

    1995-12-31

    Hatchery-reared bivalves, oysters (Crassostrea virginica) and clams (Mercenaria mercenaria), were deployed simultaneously at reference and degraded sites in SC estuaries for approximately 1 month. Juvenile bivalves with endogenously high growth rates were used because effects on growth can be detected in a short time frame. The effects on growth and bioaccumulation of metal contaminants, as well as two biochemical indices (expression of metallothioneins, MT, and multi-xenobiotic transporting proteins, {at}R) were evaluated. Metal concentrations of sediments were also measured. Adverse effects on growth of both species were observed at degraded sites. However, oysters tended to grow more rapidly than clams, and adverse effects on oysters were more pronounced than in clams. Many of the sediments were characterized by elevated concentrations of multiple metals (Cu, Pb, Cr, etc.). However, increases in metal concentrations of oyster tissues were observed primarily with Cu, suggesting that many of the other metals had low bioavailability. There was little evidence of bioconcentration of any metals in clams. There was a significant correlation between sediment Cu and Cu in oyster tissues, but not in clams. Alterations in MT and MXR expression were also observed in oysters deployed at degraded sites. These studies suggest that oysters may be better in-situ indicators of habitat condition because they have more rapid growth rates and greater bioaccumulation potentials.

  15. Tissue- and species-specific differences in cytochrome c oxidase assembly induced by SURF1 defects

    PubMed Central

    Kovářová, Nikola; Pecina, Petr; Nůsková, Hana; Vrbacký, Marek; Zeviani, Massimo; Mráček, Tomáš; Viscomi, Carlo; Houštěk, Josef

    2016-01-01

    Mitochondrial protein SURF1 is a specific assembly factor of cytochrome c oxidase (COX), but its function is poorly understood. SURF1 gene mutations cause a severe COX deficiency manifesting as the Leigh syndrome in humans, whereas in mice SURF1−/− knockout leads only to a mild COX defect. We used SURF1−/− mouse model for detailed analysis of disturbed COX assembly and COX ability to incorporate into respiratory supercomplexes (SCs) in different tissues and fibroblasts. Furthermore, we compared fibroblasts from SURF1−/− mouse and SURF1 patients to reveal interspecies differences in kinetics of COX biogenesis using 2D electrophoresis, immunodetection, arrest of mitochondrial proteosynthesis and pulse-chase metabolic labeling. The crucial differences observed are an accumulation of abundant COX1 assembly intermediates, low content of COX monomer and preferential recruitment of COX into I–III2–IVn SCs in SURF1 patient fibroblasts, whereas SURF1−/− mouse fibroblasts were characterized by low content of COX1 assembly intermediates and milder decrease in COX monomer, which appeared more stable. This pattern was even less pronounced in SURF1−/− mouse liver and brain. Both the control and SURF1−/− mice revealed only negligible formation of the I–III2–IVn SCs and marked tissue differences in the contents of COX dimer and III2–IV SCs, also less noticeable in liver and brain than in heart and muscle. Our studies support the view that COX assembly is much more dependent on SURF1 in humans than in mice. We also demonstrate markedly lower ability of mouse COX to form I–III2–IVn supercomplexes, pointing to tissue-specific and species-specific differences in COX biogenesis. PMID:26804654

  16. Tissue- and species-specific differences in cytochrome c oxidase assembly induced by SURF1 defects.

    PubMed

    Kovářová, Nikola; Pecina, Petr; Nůsková, Hana; Vrbacký, Marek; Zeviani, Massimo; Mráček, Tomáš; Viscomi, Carlo; Houštěk, Josef

    2016-04-01

    Mitochondrial protein SURF1 is a specific assembly factor of cytochrome c oxidase (COX), but its function is poorly understood. SURF1 gene mutations cause a severe COX deficiency manifesting as the Leigh syndrome in humans, whereas in mice SURF1(-/-) knockout leads only to a mild COX defect. We used SURF1(-/-) mouse model for detailed analysis of disturbed COX assembly and COX ability to incorporate into respiratory supercomplexes (SCs) in different tissues and fibroblasts. Furthermore, we compared fibroblasts from SURF1(-/-) mouse and SURF1 patients to reveal interspecies differences in kinetics of COX biogenesis using 2D electrophoresis, immunodetection, arrest of mitochondrial proteosynthesis and pulse-chase metabolic labeling. The crucial differences observed are an accumulation of abundant COX1 assembly intermediates, low content of COX monomer and preferential recruitment of COX into I-III2-IVn SCs in SURF1 patient fibroblasts, whereas SURF1(-/-) mouse fibroblasts were characterized by low content of COX1 assembly intermediates and milder decrease in COX monomer, which appeared more stable. This pattern was even less pronounced in SURF1(-/-) mouse liver and brain. Both the control and SURF1(-/-) mice revealed only negligible formation of the I-III2-IVn SCs and marked tissue differences in the contents of COX dimer and III2-IV SCs, also less noticeable in liver and brain than in heart and muscle. Our studies support the view that COX assembly is much more dependent on SURF1 in humans than in mice. We also demonstrate markedly lower ability of mouse COX to form I-III2-IVn supercomplexes, pointing to tissue-specific and species-specific differences in COX biogenesis. PMID:26804654

  17. Significance of brown dwarfs

    NASA Technical Reports Server (NTRS)

    Black, D. C.

    1986-01-01

    The significance of brown dwarfs for resolving some major problems in astronomy is discussed. The importance of brown dwarfs for models of star formation by fragmentation of molecular clouds and for obtaining independent measurements of the ages of stars in binary systems is addressed. The relationship of brown dwarfs to planets is considered.

  18. Liquid-bubble Interaction under Surf Zone Breaking Waves

    NASA Astrophysics Data System (ADS)

    Derakhti, M.; Kirby, J. T., Jr.

    2014-12-01

    Liquid-bubble interaction, especially in complex two-phase bubbly flow under breaking waves, is still poorly understood. Derakhti and Kirby (2014a,b) have recently studied bubble entrainment and turbulence modulation by dispersed bubbles under isolated unsteady breaking waves along with extensive model verifications and convergence tests. In this presentation, we continue this examination with attention turned to the simulation of periodic surf zone breaking waves. In addition, the relative importance of preferential accumulation of dispersed bubbles in coherent vortex cores is investigated. Heavier-than-liquid particles, i.e. sediment, tend to accumulate in regions of high strain rate and avoid regions of intense vorticity. In contrast, lighter-than-liquid particles such as bubbles tend to congregate in vortical regions. We perform a three dimensional (3D) large-eddy simulation (LES) using a Navier-Stokes solver extended to incorporate entrained bubble populations, using an Eulerian-Eulerian formulation for the polydisperse bubble phase. The volume of fluid (VOF) method is used for free surface tracking. The model accounts for momentum exchange between dispersed bubbles and liquid phase as well as bubble-induced dissipation. We investigate the formation and evolution of breaking-induced turbulent coherent structures (BTCS) under both plunging and spilling periodic breaking waves as well as BTCS's role on the intermittent 3D distributions of bubble void fraction in the surf zone. We particularly examine the correlation between bubble void fractions and Q-criterion values to quantify this interaction. Also, the vertical transport of dispersed bubbles by downburst type coherent structures in the transition region is compared to that by obliquely descending eddies. All the results are summarized at different zones from outer to inner surf zone.

  19. Learning and Identity in Overlapping Communities of Practice: Surf Club, School and Sports Clubs

    ERIC Educational Resources Information Center

    Light, Richard; Nash, Melanie

    2006-01-01

    Large numbers of children and young people spend their weekends and holidays engaged in the activities of over 300 surf clubs across Australia each summer. Long term membership in these clubs, beginning from as young as five years of age, forms a significant part of children's and young people's development yet surf clubs have yet to receive

  20. The effects of surfing behaviour on the development of external auditory canal exostosis.

    PubMed

    Alexander, V; Lau, A; Beaumont, E; Hope, A

    2015-07-01

    To examine how individual surfing behaviour affects the development of external auditory canal exostosis and to produce a model to predict exostosis severity. A standardised questionnaire was completed and each participant underwent an otoscopic examination. Surfers were recruited from August to October 2011 from surfing competitions and from colleges in the South West of England. 207 surfers were included, 53 % had evidence of external auditory canal; exostosis: grade 1, 23%; grade 2, 16%, grade 3, 16%. This risk of exostosis significantly increased with (1) surfing for 6 or more years, (2) surfing in the winter months, (3) surfing five or more times per month in the winter and (4) reported ear symptoms. Interestingly, participation in other water sports and wearing earplugs or a hood reduced the risk of developing exostosis. Surfers who surf in England are at significant risk of exostosis. A probability model was designed, incorporating different surfing behaviours and ear symptoms, the first of its kind in exostosis research. This model will be a useful tool for raising awareness of external ear canal exostosis in the surfing community and in assessing individual need for surgical intervention. PMID:24619201

  1. Downscaling surfing conditions in nearshore areas: seasonal, interannual and long term variability

    NASA Astrophysics Data System (ADS)

    Losada, I.; Espejo, A.; Mendez, F.

    2012-12-01

    During the last years several artificial surf reefs have been constructed. Most of them have had slight effect on improving surf quality and in some cases the results have not been enough satisfactory. One cause of this lack of success can be blamed to an incipient design and construction technique but also because the location of these structures responds to socio-economic principles rather than in oceanographic ones. This work describes a hybrid downscaling method used to get detailed tracing spectral wave and wind data in order to determine historical surf quality time series in a regional (10-200 km) or a local scale. Our assessment is conducted by means of an objective and standardized index on the basis of expert judgment that takes into account the multivariate character of the surf resource. The availability of long hourly time series (more than 60 years) of the surf quality allows the statistical analysis at any particular spot. Thus, we offer a reliable tool for identifying optimum reef location, and determining spatial patterns of surf consistency in terms of seasonal, interannual and long term variability. This method have been applied in the north-eastern coast of Spain identifying world class spots like Mundaka and other places where in spite of occurring good wave-wind conditions there is no bathymetric anomalies able to produce peeling waves. This method provides the decision making process when planning an artificial surf reef construction and at the same time offers useful information for coastal management and surf related stakeholders.

  2. The Ocean as a Unique Therapeutic Environment: Developing a Surfing Program

    ERIC Educational Resources Information Center

    Clapham, Emily D.; Armitano, Cortney N.; Lamont, Linda S.; Audette, Jennifer G.

    2014-01-01

    Educational aquatic programming offers necessary physical activity opportunities to children with disabilities and the benefits of aquatic activities are more pronounced for children with disabilities than for their able-bodied peers. Similar benefits could potentially be derived from surfing in the ocean. This article describes an adapted surfing

  3. Habitat use by larval fishes in a temperate South African surf zone

    NASA Astrophysics Data System (ADS)

    Watt-Pringle, Peter; Strydom, Nadine A.

    2003-12-01

    Larval fishes were sampled in the Kwaaihoek surf zone on the south east coast of South Africa. On six occasions between February and May 2002, larval fishes were collected in two habitat types identified in the inner surf zone using a modified beach-seine net. The surf zone habitats were classified as either sheltered trough areas or adjacent exposed surf areas. Temperature, depth and current measurements were taken at all sites. Trough habitats consisted of a depression in surf topography characterised by reduced current velocities and greater average depth than adjacent surf areas. In total, 325 larval fishes were collected. Of these, 229 were collected in trough and 96 in surf habitats. At least 22 families and 37 species were represented in the catch. Dominant families were the Mugilidae, Sparidae, Atherinidae, and Engraulidae. Dominant species included Liza tricuspidens and Liza richardsonii (Mugilidae), Rhabdosargus holubi and Sarpa salpa (Sparidae), Atherina breviceps (Atherinidae) and Engraulis japonicus (Engraulide). Mean CPUE of postflexion larvae of estuary-dependent species was significantly greater in trough areas. The proportion of postflexion larval fishes in trough habitat was significantly greater than that of preflexion stages, a result that was not apparent in surf habitat sampled. CPUE of postflexion larvae of estuary-dependent fishes was negatively correlated with current magnitude and positively correlated with habitat depth. Mean body length of larval fishes was significantly greater in trough than in surf habitats. These results provide evidence that the CPUE of postflexion larvae of estuary-dependent fishes is higher in trough habitat in the surf zone and this may be indicative of active habitat selection for areas of reduced current velocity/wave action. The implications of this behaviour for estuarine recruitment processes are discussed.

  4. Wave Acceleration Induced Sediment Transport in the Surf Zone

    NASA Astrophysics Data System (ADS)

    Hoefel, F.; Elgar, S.

    2002-12-01

    A bedload sediment transport formulation (Drake and Calantoni, 2001) that accounts for the effects of near-bottom wave-orbital velocity acceleration skewness predicts onshore sandbar migration observed near Duck, NC. Including acceleration effects in an energetics sediment transport model results in improved skill in reproducing cross-shore sandbar migration patterns observed over a 40 day period during which the bar moved both offshore in storms and onshore between storms. These results suggest that skewed acceleration time series, associated with the pitched forward shapes of nearly breaking and broken waves, play an important role in wave-induced sediment transport in the surf zone. The passage of steep wave fronts results in spikes in acceleration when orbital velocities are directed onshore, producing strong horizontal pressure gradient forces that act on the sediment. In contrast to velocity skewness, which remains approximately constant across the surf zone, acceleration skewness is observed to increase from small values offshore to a maximum near the bar crest, and then to decrease toward the shoreline, producing cross-shore spatial gradients in acceleration-driven transport that are consistent with erosion offshore and accretion onshore of the bar crest. As the sandbar migrates shoreward, the maximum of acceleration skewness also moves onshore, causing a positive feedback mechanism that promotes continued onshore sediment transport motion provided the forcing remains constant. Funded by ARO, ONR, and NOPP.

  5. Information surfing with the JHU/APL coherent imager

    NASA Astrophysics Data System (ADS)

    Ratto, Christopher R.; Shipley, Kara R.; Beagley, Nathaniel; Wolfe, Kevin C.

    2015-05-01

    The ability to perform remote forensics in situ is an important application of autonomous undersea vehicles (AUVs). Forensics objectives may include remediation of mines and/or unexploded ordnance, as well as monitoring of seafloor infrastructure. At JHU/APL, digital holography is being explored for the potential application to underwater imaging and integration with an AUV. In previous work, a feature-based approach was developed for processing the holographic imagery and performing object recognition. In this work, the results of the image processing method were incorporated into a Bayesian framework for autonomous path planning referred to as information surfing. The framework was derived assuming that the location of the object of interest is known a priori, but the type of object and its pose are unknown. The path-planning algorithm adaptively modifies the trajectory of the sensing platform based on historical performance of object and pose classification. The algorithm is called information surfing because the direction of motion is governed by the local information gradient. Simulation experiments were carried out using holographic imagery collected from submerged objects. The autonomous sensing algorithm was compared to a deterministic sensing CONOPS, and demonstrated improved accuracy and faster convergence in several cases.

  6. Photosymbiotic giant clams are transformers of solar flux

    PubMed Central

    Holt, Amanda L.; Vahidinia, Sanaz; Gagnon, Yakir Luc; Morse, Daniel E.; Sweeney, Alison M.

    2014-01-01

    ‘Giant’ tridacnid clams have evolved a three-dimensional, spatially efficient, photodamage-preventing system for photosymbiosis. We discovered that the mantle tissue of giant clams, which harbours symbiotic nutrition-providing microalgae, contains a layer of iridescent cells called iridocytes that serve to distribute photosynthetically productive wavelengths by lateral and forward-scattering of light into the tissue while back-reflecting non-productive wavelengths with a Bragg mirror. The wavelength- and angle-dependent scattering from the iridocytes is geometrically coupled to the vertically pillared microalgae, resulting in an even re-distribution of the incoming light along the sides of the pillars, thus enabling photosynthesis deep in the tissue. There is a physical analogy between the evolved function of the clam system and an electric transformer, which changes energy flux per area in a system while conserving total energy. At incident light levels found on shallow coral reefs, this arrangement may allow algae within the clam system to both efficiently use all incident solar energy and avoid the photodamage and efficiency losses due to non-photochemical quenching that occur in the reef-building coral photosymbiosis. Both intra-tissue radiometry and multiscale optical modelling support our interpretation of the system's photophysics. This highly evolved ‘three-dimensional’ biophotonic system suggests a strategy for more efficient, damage-resistant photovoltaic materials and more spatially efficient solar production of algal biofuels, foods and chemicals. PMID:25401182

  7. Photosymbiotic giant clams are transformers of solar flux.

    PubMed

    Holt, Amanda L; Vahidinia, Sanaz; Gagnon, Yakir Luc; Morse, Daniel E; Sweeney, Alison M

    2014-12-01

    'Giant' tridacnid clams have evolved a three-dimensional, spatially efficient, photodamage-preventing system for photosymbiosis. We discovered that the mantle tissue of giant clams, which harbours symbiotic nutrition-providing microalgae, contains a layer of iridescent cells called iridocytes that serve to distribute photosynthetically productive wavelengths by lateral and forward-scattering of light into the tissue while back-reflecting non-productive wavelengths with a Bragg mirror. The wavelength- and angle-dependent scattering from the iridocytes is geometrically coupled to the vertically pillared microalgae, resulting in an even re-distribution of the incoming light along the sides of the pillars, thus enabling photosynthesis deep in the tissue. There is a physical analogy between the evolved function of the clam system and an electric transformer, which changes energy flux per area in a system while conserving total energy. At incident light levels found on shallow coral reefs, this arrangement may allow algae within the clam system to both efficiently use all incident solar energy and avoid the photodamage and efficiency losses due to non-photochemical quenching that occur in the reef-building coral photosymbiosis. Both intra-tissue radiometry and multiscale optical modelling support our interpretation of the system's photophysics. This highly evolved 'three-dimensional' biophotonic system suggests a strategy for more efficient, damage-resistant photovoltaic materials and more spatially efficient solar production of algal biofuels, foods and chemicals. PMID:25401182

  8. Development status of CLAM steel for fusion application

    NASA Astrophysics Data System (ADS)

    Huang, Qunying

    2014-12-01

    The China low activation martensitic (CLAM) steel is being developed at the Institute of Nuclear Energy Safety Technology (INEST) under wide collaboration within China. Significant R&D work on CLAM steel was carried out to help make it suitable for industrial applications. The effect of refining processes and thermal aging on composition, microstructures and mechanical properties were investigated. Material properties before irradiation including impact, fracture toughness, thermal aging, creep and fatigue properties etc. were assessed. A series of irradiation tests in the fission reactor HFETR in Chengdu up to 2 dpa and in the spallation neutron source SINQ in Paul Scherrer Institute up to 20 dpa were performed. PbLi corrosion tests for more than 10,000 h were done in the DRAGON-I and PICOLO loops. Fabrication techniques for a test blanket module (TBM) are being developed and a 1/3 scale TBM prototype is being fabricated with CLAM steel. Recent progresses on the development status of this steel are presented here. The code qualification of CLAM steel is under plan for its final application in ITER-TBM and DEMO in the future.

  9. Measurement and analysis of SHCCT diagram for CLAM steel

    NASA Astrophysics Data System (ADS)

    Huang, Yuming; Chen, Xizhang; Shen, Zheng; Madigan, Bruce; Yucheng, Lei; Zhou, Jianzhong

    2013-01-01

    China Low Activation Martensitic (CLAM) steel is a leading candidate material for construction of the Chinese fusion reactor Test Blanket Module. The Simulated HAZ Continuous Cooling Transformation (SHCCT) diagram is developed via physical simulation, and the effects of thermal history on the microstructure and mechanical properties of the weld coarse-grain heat-affected zone (CGHAZ) in CLAM steel are evaluated. The results of thermal cycle simulation show that grain size increases and hardness decreases gradually with increasing heat input. Under certain conditions, especially when cooling times from 800 C to 500 C (T8/5) are larger than 136 s, delta ferrite may form which is deleterious for the TBM application. The amounts of delta ferrite are given under different T8/5. A SHCCT diagram of CLAM steel is developed using dilatometry and it predicts the AC1, AC3 and the Ms temperatures. With decreased cooling rate (larger T8/5), martensite laths widen and carbide precipitates grow. The results indicate that welding heat input should be taken into consideration and controlled in practical CLAM steel welding process applications.

  10. The Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) Experiment

    NASA Technical Reports Server (NTRS)

    Smith, William L., Jr.; Charlock, Thomas; Wielicki, Bruce; Kahn, Ralph; Martins, J. Vanderlei; Gatebe, Charles; Hobbs, Peter V.; Purgold, G. Carl; Redemann, Jens; Remer, Lorraine

    2004-01-01

    NASA has developed an Earth Observing System (EOS) consisting of a series of satellites designed to study global change from space. The EOS flagship is the EOS TERRA satellite, launched in December 1999, equipped with five unique sensors to monitor and study the Earth s heat budget and many of the key controlling variables governing the Earth's climate system. CLAMS, the Chesapeake Lighthouse and Aircraft Measurements for Satellites field campaign was conducted from NASA Wallops Flight Facility and successfully executed over the middle Atlantic eastern seaboard from July 10 August 2, 2001. CLAMS is primarily a shortwave closure experiment designed to validate and improve EOS TERRA satellite data products being derived from three sensors: CERES (Clouds and Earth's Radiant Energy System), MISR (Multi-angle Imaging Spectro-Radiometer) and MODIS (MODerate Resolution Imaging Spectroradiometer). CLAMS is jointly sponsored by the CERES, MISR and MODIS instrument teams and the NASA GEWEX Global Aerosol Climatology Project (GACP). CLAMS primary objectives are to validate satellite-based retrievals of aerosol properties and vertical profiles of radiative flux, temperature and water vapor. Central to CLAMS measurement strategy is the Chesapeake Lighthouse, a stable sea platform located in the Atlantic Ocean, 13 miles east of Virginia Beach near the mouth of the Chesapeake Bay and the site of an ongoing CERES Ocean Validation Experiment (COVE). Six research aircraft were deployed to make detailed measurements of the atmosphere and ocean surface in the vicinity of COVE, over the surrounding ocean, over nearby NOAA buoys and over a few land sites. The measurements are used to validate and provide ground truth for simultaneous products being derived from TERRA data, a key step toward an improved understanding and ability to predict changes in the Earth's climate. One of the two CERES instruments on-board TERRA was programmed for Rotating Azimuth Plane Scans (RAPS) during CLAMS, increasing the CERES coverage over COVE by a factor of 10. Nine coordinated aircraft missions and numerous additional sorties were flown under a variety of atmospheric conditions and aerosol loadings. On one golden day, July 17, all six aircraft flew coordinated patterns, vertically stacked between 100 ft and 65,000 ft over the COVE site as the TERRA satellite orbited overhead. A summary of CLAMS measurement campaign and a description of the platforms and measurements is given.

  11. Vesicomyid Clams Alter Biogeochemical Processes at Pacific Methane Seeps

    NASA Astrophysics Data System (ADS)

    Bertics, V. J.; Treude, T.; Ziebis, W.

    2007-12-01

    There exists a close relationship between fluid flow, biogeochemistry, and biota in seep sediments. Upwelling of methane and sulfide-rich fluids supports abundant macrofauna species harboring thiotrophic or methanotrophic symbionts. Variations in fluid flow, thus supply of methane and sulfide, are considered key factors controlling benthic communities. Vesicomyid clams harbor thiotrophic symbionts in their gills, which are supplied with oxygen from the surrounding water and hydrogen sulfide from the sediment. The clams are capable of extending their foot into the sediment to tap sulfide sources in deeper layers, consequently affecting water-sediment solute exchange. Because seep fluids are generally depleted in sulfate compared to seawater, this bioturbation activity may enhance the supply of sulfate to otherwise sulfate-limited sediments, thus boosting microbial activity of sulfate reduction (SR) coupled to anaerobic oxidation of methane (AOM). The goal of this study was to investigate the activity of three species of vesicomyid clams ( Calyptogena pacifica, C. kilmeri, C. gigas) from three methane seep habitats (Eel River Basin, Hydrate Ridge, Monterey Bay Canyon) and to evaluate its effect on biogeochemical processes. Sediment cores and clams were collected using the submersible Alvin or the ROV Jason, during three cruises with the R/V Atlantis in July and October 2006 and July 2007 (AT 15-7, AT 15-11, and AT 15-20). We performed high-resolution measurements of geochemical gradients in intact sediment cores using microsensors (O2, H2S, pH, redox potential). The cores were then sliced (1 cm intervals) for detailed chemical and microbiological analyses. Parallel cores were used to determine microbial activity (AOM, SR) with radioactive tracers. For detailed laboratory investigations, clams were kept in narrow aquaria (15 cm x 20 cm x 5 cm) in the ship's cold room. The front of the aquaria was perforated with holes at 1 cm resolution. These silicone-filled holes served as sampling ports or for direct microsensor measurements. Vertical and horizontal microprofiles were measured, pore water samples were extracted, and small sediment cores were taken along the length of the aquaria for microbial rate measurements and chemical and microbiological analyses. We documented different bioturbation activity for the three species of vesicomyid clam that related to distinct geochemical gradients and differences in microbial activity. Sulfate reduction, thus sulfide production, was significantly enhanced in the presence of clams compared to the control.

  12. Patterns in Clam Excurrent Siphon Velocity According to External Environmental Cues

    NASA Astrophysics Data System (ADS)

    Webster, D. R.; Delavan, S. K.

    2010-11-01

    This study attempts to determine the patterns and/or randomness of the excurrent velocity of actively feeding clams, Mercenaria mercenaria. We hypothesize that clams alter their feeding current velocity patterns or randomness according to external cues in the environment such as hydrodynamic characteristics, density of the clam patch, and presence of predators in the upstream flow. A PIV system measured vector fields for two-dimensional planes that bisect the clam excurrent siphons, and time records were extracted at the siphon exit position. Fractal and lacunarity analysis of the jet velocity time records revealed that clams alter their jet excurrent velocity unsteadiness according to the horizontal crossflow velocity. The results also reveal that the effect of clam patch density on the feeding activity was dependent on the size of the organism. This size/density dependent relationship suggests that predation by blue crabs dominates the system since larger clams are no longer susceptible to blue crab predation, whereas clams of all sizes are susceptible to whelk predation. Finally, clams increase the randomness of their excurrent jet velocity values when predator cues are located in the upstream flume flow. This suggests that the presence of predators elicits clam behavior that promotes the mixing and dilution of their chemical metabolites.

  13. Leigh syndrome in Drosophila melanogaster: morphological and biochemical characterization of Surf1 post-transcriptional silencing.

    PubMed

    Da-R, Caterina; von Stockum, Sophia; Biscontin, Alberto; Millino, Caterina; Cisotto, Paola; Zordan, Mauro A; Zeviani, Massimo; Bernardi, Paolo; De Pitt, Cristiano; Costa, Rodolfo

    2014-10-17

    Leigh Syndrome (LS) is the most common early-onset, progressive mitochondrial encephalopathy usually leading to early death. The single most prevalent cause of LS is occurrence of mutations in the SURF1 gene, and LS(Surf1) patients show a ubiquitous and specific decrease in the activity of mitochondrial respiratory chain complex IV (cytochrome c oxidase, COX). SURF1 encodes an inner membrane mitochondrial protein involved in COX assembly. We established a Drosophila melanogaster model of LS based on the post-transcriptional silencing of CG9943, the Drosophila homolog of SURF1. Knockdown of Surf1 was induced ubiquitously in larvae and adults, which led to lethality; in the mesodermal derivatives, which led to pupal lethality; or in the central nervous system, which allowed survival. A biochemical characterization was carried out in knockdown individuals, which revealed that larvae unexpectedly displayed defects in all complexes of the mitochondrial respiratory chain and in the F-ATP synthase, while adults had a COX-selective impairment. Silencing of Surf1 expression in Drosophila S2R(+) cells led to selective loss of COX activity associated with decreased oxygen consumption and respiratory reserve. We conclude that Surf1 is essential for COX activity and mitochondrial function in D. melanogaster, thus providing a new tool that may help clarify the pathogenic mechanisms of LS. PMID:25164807

  14. Global assessment of surfing conditions: seasonal, interannual and long-term variability

    NASA Astrophysics Data System (ADS)

    Espejo, A.; Losada, I.; Mendez, F.

    2012-12-01

    International surfing destinations owe a great debt to specific combinations of wind-wave, thermal conditions and local bathymetry. As surf quality depends on a vast number of geophysical variables, a multivariable standardized index on the basis of expert judgment is proposed to analyze surf resource in a worldwide domain. Data needed is obtained by combining several datasets (reanalyses): 60-year satellite-calibrated spectral wave hindcast (GOW, WaveWatchIII), wind fields from NCEP/NCAR, global sea surface temperature from ERSST.v3b, and global tides from TPXO7.1. A summary of the global surf resource is presented, which highlights the high degree of variability in surfable events. According to general atmospheric circulation, results show that west facing low to middle latitude coasts are more suitable for surfing, especially those in Southern Hemisphere. Month to month analysis reveals strong seasonal changes in the occurrence of surfable events, enhancing those in North Atlantic or North Pacific. Interannual variability is investigated by comparing occurrence values with global and regional climate patterns showing a great influence at both, global and regional scales. Analysis of long term trends shows an increase in the probability of surfable events over the west facing coasts on the planet (i.e. + 30 hours/year in California). The resulting maps provide useful information for surfers and surf related stakeholders, coastal planning, education, and basic research.; Figure 1. Global distribution of medium quality (a) and high quality surf conditions probability (b).

  15. White Dwarfs in UKIDSS

    NASA Astrophysics Data System (ADS)

    Steele, P. R.; Burleigh, M. R.; Farihi, J.; Gänsicke, B.; Jameson, R. F.; Dobbie, P. D.; Barstow, M. A.

    We present a near-infrared photometric search for low mass stellar and substellar companions, and for debris disks around white dwarfs in the UKIDSS Large Area Survey DR5. A cross correlation of the SDSS DR4 and McCook and Sion catalogues of white dwarfs gave near-infrared photometry for 1,161 stars. Atmospheric models are fitted to the optical and near-infrared photometry of the matched stars to identify those with a photometric excess consistent with an unresolved companion or debris disk. In total 7 new potential white dwarf + brown dwarf binary candidates have been identified. We present follow-up spectroscopy of a previously identified candidate; PHL5038. We confirm that this system is a resolved white dwarf + L8 brown dwarf binary.

  16. Surf zone diatoms: A review of the drivers, patterns and role in sandy beaches food chains

    NASA Astrophysics Data System (ADS)

    Odebrecht, Clarisse; Du Preez, Derek R.; Abreu, Paulo Cesar; Campbell, Eileen E.

    2014-10-01

    The accumulation of high biomass of diatoms in the surf zone is a characteristic feature of some sandy beaches where the wave energy is sufficiently high. A few species of diatoms, called surf diatoms, thrive in this harsh environment. The main processes driving the spatial and temporal distribution of surf diatoms as well as their standing biomass and growth were described twenty to thirty years ago based on studies conducted on the western coast of the United States of America and South African beaches. Since then, over fifty locations around the world have been reported to have surf diatom accumulations with most (three-quarters) of these being in the southern hemisphere. Their occurrence is controlled by physical and chemical factors, including wave energy, beach slope and length, water circulation patterns in the surf zone and the availability of nutrients to sustain the high biomass. The main forces driving the patterns of temporal variability of surf diatom accumulations are meteorological. In the short term (hours), the action of wind stress and wave energy controls the diatom accumulation. In the intermediate time scale (weeks to months), seasonal onshore winds of sufficient strength, as well as storm events are important. Furthermore, anthropogenic disturbances that influence the beach ecosystem as well as large-scale events, such as the El Nio Southern Oscillation, may lead to significant changes in surf diatom populations in the long term (inter-annual). Surf diatoms form the base of a short and very productive food chain in the inshore of the sandy beaches where they occur. However, the role of surf diatoms in the microbial food web is not clear and deserves further studies.

  17. Surfing Plasma Waves: A New Paradigm for Particle Accelerators

    NASA Astrophysics Data System (ADS)

    Joshi, Chandrashekhar

    Accelerator-based experiments have produced key breakthroughs in our understanding of the physical world. New accelerators, to explore the frontiers of Tera-scale Physics, appear possible, based on concepts developed over the last three decades in multi-disciplinary endeavors. The Plasma-Based Particle Accelerator is one concept that has made spectacular advances in the last few years. In this scheme, electrons or positrons gain energy by surfing the electric field of a plasma wave that is produced by the passage of an intense laser pulse or an electron beam through the plasma. This talk reviews the principles of this new technique and prognosticates how it is likely to impact science and technology in the future.

  18. Droplets move over viscoelastic substrates by surfing a ridge

    NASA Astrophysics Data System (ADS)

    Karpitschka, S.; Das, S.; van Gorcum, M.; Perrin, H.; Andreotti, B.; Snoeijer, J. H.

    2015-08-01

    Liquid drops on soft solids generate strong deformations below the contact line, resulting from a balance of capillary and elastic forces. The movement of these drops may cause strong, potentially singular dissipation in the soft solid. Here we show that a drop on a soft substrate moves by surfing a ridge: the initially flat solid surface is deformed into a sharp ridge whose orientation angle depends on the contact line velocity. We measure this angle for water on a silicone gel and develop a theory based on the substrate rheology. We quantitatively recover the dynamic contact angle and provide a mechanism for stick-slip motion when a drop is forced strongly: the contact line depins and slides down the wetting ridge, forming a new one after a transient. We anticipate that our theory will have implications in problems such as self-organization of cell tissues or the design of capillarity-based microrheometers.

  19. Droplets move over viscoelastic substrates by surfing a ridge.

    PubMed

    Karpitschka, S; Das, S; van Gorcum, M; Perrin, H; Andreotti, B; Snoeijer, J H

    2015-01-01

    Liquid drops on soft solids generate strong deformations below the contact line, resulting from a balance of capillary and elastic forces. The movement of these drops may cause strong, potentially singular dissipation in the soft solid. Here we show that a drop on a soft substrate moves by surfing a ridge: the initially flat solid surface is deformed into a sharp ridge whose orientation angle depends on the contact line velocity. We measure this angle for water on a silicone gel and develop a theory based on the substrate rheology. We quantitatively recover the dynamic contact angle and provide a mechanism for stick-slip motion when a drop is forced strongly: the contact line depins and slides down the wetting ridge, forming a new one after a transient. We anticipate that our theory will have implications in problems such as self-organization of cell tissues or the design of capillarity-based microrheometers. PMID:26238436

  20. Droplets move over viscoelastic substrates by surfing a ridge

    PubMed Central

    Karpitschka, S.; Das, S.; van Gorcum, M.; Perrin, H.; Andreotti, B.; Snoeijer, J. H.

    2015-01-01

    Liquid drops on soft solids generate strong deformations below the contact line, resulting from a balance of capillary and elastic forces. The movement of these drops may cause strong, potentially singular dissipation in the soft solid. Here we show that a drop on a soft substrate moves by surfing a ridge: the initially flat solid surface is deformed into a sharp ridge whose orientation angle depends on the contact line velocity. We measure this angle for water on a silicone gel and develop a theory based on the substrate rheology. We quantitatively recover the dynamic contact angle and provide a mechanism for stickslip motion when a drop is forced strongly: the contact line depins and slides down the wetting ridge, forming a new one after a transient. We anticipate that our theory will have implications in problems such as self-organization of cell tissues or the design of capillarity-based microrheometers. PMID:26238436

  1. Image characterization and target recognition in the surf zone environment

    NASA Astrophysics Data System (ADS)

    Nevis, Andrew J.

    1996-05-01

    The surf zone environment represents a very difficult challenge for electro-optic surveillance programs. Data from these programs have been shown to contain dense clutter from vegetation, biological factors (fish), and man-made objects, and is further complicated by the water to land transition which has a significant impact on target signal-to-noise ratios (SNR). Also, targets can be geometrically warped from the sea surface and by occlusion from sand and breaking waves. The Program Executive Office Mine Warfare (PMO-210) recently sponsored a test under the Magic Lantern Adaptation (MLA) program to collect surf zone data. Analysis of the data revealed a dilemma for automatic target recognition algorithms; threshold target features high enough to reduce high false alarm rates from land clutter or low enough to detect and classify underwater targets. Land image typically have high SNR clutter with crisp edges while underwater images have lower SNR clutter with blurred edges. In an attempt to help distinguish between land and underwater images, target feature thresholds were made to vary as a function of the SNR of image features within images and as a function of a measure of the edge crispness of the image features. The feasibility of varying target feature thresholds to reduce false alarm rates was demonstrated on a target recognition program using a small set of MLA data. Four features were developed based on expected target shape and resolution: a contrast difference measure between circular targets and their local backgrounds, a signal-to-noise ratio, a normalized correlation, and a target circularity measure. Results showed a target probability of detection and classification (Pdc) of 50 - 78% with false alarms per frame of less than 4%.

  2. Surfing through Hyperspace - Understanding Higher Universes in Six Easy Lessons

    NASA Astrophysics Data System (ADS)

    Pickover, Clifford A.

    2001-05-01

    Do a little armchair time-travel, rub elbows with a four-dimensional intelligent life form, or stretch your mind to the furthest corner of an uncharted universe. With this astonishing guidebook, Surfing Through Hyperspace , you need not be a mathematician or an astrophysicist to explore the all-but-unfathomable concepts of hyperspace and higher-dimensional geometry.No subject in mathematics has intrigued both children and adults as much as the idea of a fourth dimension. Philosophers and parapsychologists have meditated on this mysterious space that no one can point to but may be all around us. Yet this extra dimension has a very real, practical value to mathematicians and physicists who use it every day in their calculations. In the tradition of Flatland , and with an infectious enthusiasm, Clifford Pickover tackles the problems inherent in our 3-D brains trying to visualize a 4-D world, muses on the religious implications of the existence of higher-dimensional consciousness, and urges all curious readers to venture into "the unexplored territory lying beyond the prison of the obvious." Pickover alternates sections that explain the science of hyperspace with sections that dramatize mind-expanding concepts through a fictional dialogue between two futuristic FBI agents who dabble in the fourth dimension as a matter of national security. This highly accessible and entertaining approach turns an intimidating subject into a scientific game open to all dreamers.Surfing Through Hyperspace concludes with a number of puzzles, computer experiments and formulas for further exploration, inviting readers to extend their minds across this inexhaustibly intriguing scientific terrain.

  3. Surfing through Hyperspace - Understanding Higher Universes in Six Easy Lessons

    NASA Astrophysics Data System (ADS)

    Pickover, Clifford A.

    1999-09-01

    Do a little armchair time-travel, rub elbows with a four-dimensional intelligent life form, or stretch your mind to the furthest corner of an uncharted universe. With this astonishing guidebook, Surfing Through Hyperspace , you need not be a mathematician or an astrophysicist to explore the all-but-unfathomable concepts of hyperspace and higher-dimensional geometry.No subject in mathematics has intrigued both children and adults as much as the idea of a fourth dimension. Philosophers and parapsychologists have meditated on this mysterious space that no one can point to but may be all around us. Yet this extra dimension has a very real, practical value to mathematicians and physicists who use it every day in their calculations. In the tradtion of Flatland , and with an infectious enthusiasm, Clifford Pickover tackles the problems inherent in our 3-D brains trying to visualize a 4-D world, muses on the religious implications of the existence of higher-dimensional consciousness, and urges all curious readers to venture into "the unexplored territory lying beyond the prison of the obvious." Pickover alternates sections that explain the science of hyperspace with sections that dramatize mind-expanding concepts through a fictional dialogue between two futuristic FBI agents who dabble in the fourth dimension as a matter of national security. This highly accessible and entertaining approach turns an intimidating subject into a scientific game open to all dreamers.Surfing Through Hyperspace concludes with a number of puzzles, computer experiments and formulas for further exploration, inviting readers to extend their minds across this inexhaustibly intriguing scientific terrain.

  4. Military personnel recognition system using texture, colour, and SURF features

    NASA Astrophysics Data System (ADS)

    Irhebhude, Martins E.; Edirisinghe, Eran A.

    2014-06-01

    This paper presents an automatic, machine vision based, military personnel identification and classification system. Classification is done using a Support Vector Machine (SVM) on sets of Army, Air Force and Navy camouflage uniform personnel datasets. In the proposed system, the arm of service of personnel is recognised by the camouflage of a persons uniform, type of cap and the type of badge/logo. The detailed analysis done include; camouflage cap and plain cap differentiation using gray level co-occurrence matrix (GLCM) texture feature; classification on Army, Air Force and Navy camouflaged uniforms using GLCM texture and colour histogram bin features; plain cap badge classification into Army, Air Force and Navy using Speed Up Robust Feature (SURF). The proposed method recognised camouflage personnel arm of service on sets of data retrieved from google images and selected military websites. Correlation-based Feature Selection (CFS) was used to improve recognition and reduce dimensionality, thereby speeding the classification process. With this method success rates recorded during the analysis include 93.8% for camouflage appearance category, 100%, 90% and 100% rates of plain cap and camouflage cap categories for Army, Air Force and Navy categories, respectively. Accurate recognition was recorded using SURF for the plain cap badge category. Substantial analysis has been carried out and results prove that the proposed method can correctly classify military personnel into various arms of service. We show that the proposed method can be integrated into a face recognition system, which will recognise personnel in addition to determining the arm of service which the personnel belong. Such a system can be used to enhance the security of a military base or facility.

  5. Characteristics of vesicomyid clams and their environment at the Blake Ridge cold seep, South Carolina, USA

    USGS Publications Warehouse

    Heyl, Taylor P.; Gilhooly, William P.; Chambers, Randolph M.; Gilchrist, George W.; Macko, Stephen A.; Ruppel, Carolyn D.; Van Dover, Cindy L.

    2007-01-01

    Spatial distributions and patchiness of dominant megafaunal invertebrates in deep-sea seep environments may indicate heterogeneities in the flux of reduced chemical compounds. At the Blake Ridge seep off South Carolina, USA, the invertebrate assemblage includes dense populations of live vesicomyid clams (an undescribed species) as well as extensive clam shell beds (i.e. dead clams). In the present study, we characterized clam parameters (density, size-frequency distribution, reproductive condition) in relation to sulfur chemistry (sulfide and sulfate concentrations and isotopic compositions, pyrite and elemental sulfur concentrations) and other sedimentary metrics (grain size, organic content). For clams >5 mm, clam density was highest where the total dissolved sulfide concentration at 10 cm depth (?H2S10cm) was 0.4 to 1.1 mmol l1; juvenile clams (2S10cm was lowest. Clams were reproductively capable across a broad range of ?H2S10cm (0.1 to 6.4 mmol l1), and females in the sampled populations displayed asynchronous gametogenesis. Sulfide concentrations in porewaters at the shellsediment interface of cores from shell beds were high, 3.3 to 12.1 mmol l1, compared to 1 sulfide concentrations at the clamsediment interface in live clam beds. Concentration profiles for sulfide and sulfate in shell beds were typical of those expected where there is active microbial sulfate reduction. In clam beds, profiles of sulfide and sulfate concentrations were also consistent with rapid uptake of sulfide by the clams. Sulfate in shell beds was systematically enriched in 34S relative to that in clam beds due to microbial fractionation during sulfate reduction, but in clam beds, sulfate ?34S matched that of seawater (~20). Residual sulfide values in clam and shell beds were correspondingly depleted in 34S. Based on porewater sulfide concentrations in shell beds at the time of sampling, we suggest that clam mortality may have been due to an abrupt increase in sulfide concentration and sulfide toxicity, but other alternatives cannot be eliminated.

  6. Hsp 70 in the soft shell clam (Mya arenaria): Potential as a biomarker of field contamination

    SciTech Connect

    Clayton, M.E.; Dworak, H.A.; McDowell, J.E.

    1995-12-31

    Soft shell clams (Mya arenaria) were collected from 2 contaminated and 2 control sites in Massachusetts at 4 time periods, extending over a 30{degree}C temperature range. Populations at New Bedford Harbor were exposed to PCBs, PAHs, and heavy metals and populations at the Cotuit Bay Shores Beach Club were exposed to an unknown quantity and composition of petroleum hydrocarbons. Heat shock protein (hsp) 70 was measured in the gill of 20 clams per site by ELISA, using a commercially available monoclonal antibody. Expression of hsp 70 was variable between individual clams collected from the same site. Significance of the variables site and month was tested by one-way and two-way ANOVA; site, month, and site by month interaction were all significant. The significant interaction term meant that it was necessary to hold the month variable constant in order to test the hypothesis that clams from the contaminated sites contained more heat shock proteins than clams from the corresponding control sites. In general, the contaminated clams contained a higher concentration of hsp 70 than clams from the control sites, with New Bedford Harbor exhibiting the highest levels. Seasonal differences which could be responsible for the month effect include heat shock, food availability, and reproductive condition. In order to use heat shock protein expression as a biomarker of exposure to contaminants in the field, it is necessary to compare clams from contaminated sites to clams from control sites sampled at the same time.

  7. Infection of Manila clams Ruditapes philippinarum from Galicia (NW Spain) with a Mikrocytos-like parasite.

    PubMed

    Ramilo, Andrea; Iglesias, David; Abollo, Elvira; Gonzlez, Mar; Darriba, Susana; Villalba, Antonio

    2014-07-24

    The name 'microcells' is frequently used to refer to small-sized unicellular stages of molluscan parasites of the genera Bonamia (Rhizaria, Haplosporidia) and Mikrocytos (Rhizaria). Histological examination of Manila clams Ruditapes philippinarum revealed microcells in the connective tissue of adductor muscle, foot, mantle, gills, siphon and visceral mass. The clams had been collected from 4 beds on the coast of Galicia, Spain. The prevalence of these microcells ranged from 73 to 93% in surface clams and from 3 to 33% in buried clams. However, the detection of brown ring disease signs in clams from every bed prevented us from making the assumption that the microcells alone were responsible for clam mortality. PCR assays using primer pairs designed to detect Bonamia spp. and haplosporidians gave negative results, whereas positive results were obtained with primers for the genus Mikrocytos. A consensus sequence of 1670 bp of the ribosomal gene complex of the microcells was obtained. It contained a section of the 18S region, the whole first internal transcribed spacer, the 5.8S region, the second internal transcribed spacer and a section of the 28S region. Comparison of this sequence with those of M. mackini infecting Crassostrea gigas and Mikrocytos sp. infecting Ostrea edulis showed that the microcells of Galician clams were the most divergent among the compared parasites. This is the first report of a Mikrocytos-like parasite infecting Manila clams. Care must be taken to avoid the spread of this parasite through Manila clam transfers. PMID:25060499

  8. The effects of surfing and the natural environment on the well-being of combat veterans.

    PubMed

    Caddick, Nick; Smith, Brett; Phoenix, Cassandra

    2015-01-01

    Although researchers have identified the benefits of physical activity on well-being, there is little evidence concerning the effects of nature-based physical activity. We investigated the effect of one nature-based activity-surfing-on the well-being of combat veterans experiencing posttraumatic stress disorder (PTSD). We conducted interviews and participant observations with a group of combat veterans belonging to a United Kingdom-based veterans' surfing charity. Our primary analytical approach was dialogical narrative analysis. Based on our rigorous analysis and findings, we suggest that surfing facilitated a sense of respite from PTSD. Respite was a fully embodied feeling of release from suffering that was cultivated through surfing and shaped by the stories veterans told of their experiences. We significantly extend previous knowledge on physical activity, combat veterans, and PTSD by highlighting how nature-based physical activity, encapsulated in the conceptual notion of the "blue gym," can promote well-being among combat veterans. PMID:25189537

  9. Sandy beach surf zones: An alternative nursery habitat for 0-age Chinook salmon

    NASA Astrophysics Data System (ADS)

    Marin Jarrin, J. R.; Miller, J. A.

    2013-12-01

    The role of each habitat fish use is of great importance to the dynamics of populations. During their early marine residence, Chinook salmon (Oncorhynchus tshawytscha), an anadromous fish species, mostly inhabit estuaries but also use sandy beach surf zones and the coastal ocean. However, the role of surf zones in the early life history of Chinook salmon is unclear. We hypothesized that surf zones serve as an alternative nursery habitat, defined as a habitat that consistently provides a proportion of a population with foraging and growth rates similar to those experienced in the primary nursery. First, we confirmed that juvenile Chinook salmon cohorts are simultaneously using both habitats by combining field collections with otolith chemical and structural analysis to directly compare size and migration patterns of juveniles collected in two Oregon (USA) estuaries and surf zones during three years. We then compared juvenile catch, diet and growth in estuaries and surf zones. Juveniles were consistently caught in both habitats throughout summer. Catches were significantly higher in estuaries (average ± SD = 34.3 ± 19.7 ind. 100 m-2) than surf zones (1.0 ± 1.5 ind. 100 m-2) and were positively correlated (r = 0.92). Size at capture (103 ± 15 mm fork length, FL), size at marine entry (76 ± 13 mm FL), stomach fullness (2 ± 2% body weight) and growth rates (0.4 ± 0.0 mm day-1) were similar between habitats. Our results suggest that when large numbers of 0-age Chinook salmon inhabit estuaries, juveniles concurrently use surf zones, which serve as an alternative nursery habitat. Therefore, surf zones expand the available rearing habitat for Chinook salmon during early marine residence, a critical period in the life history.

  10. The Rate of Beneficial Mutations Surfing on the Wave of a Range Expansion

    PubMed Central

    Lehe, Rmi; Hallatschek, Oskar; Peliti, Luca

    2012-01-01

    Many theoretical and experimental studies suggest that range expansions can have severe consequences for the gene pool of the expanding population. Due to strongly enhanced genetic drift at the advancing frontier, neutral and weakly deleterious mutations can reach large frequencies in the newly colonized regions, as if they were surfing the front of the range expansion. These findings raise the question of how frequently beneficial mutations successfully surf at shifting range margins, thereby promoting adaptation towards a range-expansion phenotype. Here, we use individual-based simulations to study the surfing statistics of recurrent beneficial mutations on wave-like range expansions in linear habitats. We show that the rate of surfing depends on two strongly antagonistic factors, the probability of surfing given the spatial location of a novel mutation and the rate of occurrence of mutations at that location. The surfing probability strongly increases towards the tip of the wave. Novel mutations are unlikely to surf unless they enjoy a spatial head start compared to the bulk of the population. The needed head start is shown to be proportional to the inverse fitness of the mutant type, and only weakly dependent on the carrying capacity. The precise location dependence of surfing probabilities is derived from the non-extinction probability of a branching process within a moving field of growth rates. The second factor is the mutation occurrence which strongly decreases towards the tip of the wave. Thus, most successful mutations arise at an intermediate position in the front of the wave. We present an analytic theory for the tradeoff between these factors that allows to predict how frequently substitutions by beneficial mutations occur at invasion fronts. We find that small amounts of genetic drift increase the fixation rate of beneficial mutations at the advancing front, and thus could be important for adaptation during species invasions. PMID:22479175

  11. Surfing depth on a behaviour change website: predictors and effects on behaviour.

    PubMed

    Jacobs, Nele; De Bourdeaudhuij, Ilse; Claes, Neree

    2010-03-01

    The primary objectives of the present study were to gain insight into website use and to predict the surfing depth on a behaviour change website and its effect on behaviour. Two hundred eight highly educated adults from the intervention condition of a randomised trial received access to a medical intervention, individual coaching (by e-mail, post, telephone or face-to-face) and a behaviour change website. Website use (e.g. surfing depth, page view duration) was registered. Online questionnaires for physical activity and fat intake were filled out at baseline and after 6 months. Hierarchical linear regression was used to predict surfing depth and its effect on behaviour. Seventy-five per cent of the participants visited the website. Fifty-one and fifty-six per cent consulted the physical activity and fat intake feedback, respectively. The median surfing depth was 2. The total duration of interventions by e-mail predicted deeper surfing (beta=0.36; p<0.001). Surfing depth did not predict changes in fat intake (beta=-0.07; p=0.45) or physical activity (beta=-0.03; p=0.72). Consulting the physical activity feedback led to more physical activity (beta=0.23; p=0.01). The findings from the present study can be used to guide future website development and improve the information architecture of behaviour change websites. PMID:20726734

  12. Qualitative Task Analysis to Enhance Sports Characterization: A Surfing Case Study

    PubMed Central

    Moreira, Miguel; Peixoto, Csar

    2014-01-01

    The aim of this study was to develop a Matrix of Analysis for Sports Tasks (MAST), regardless of the sports activity, based on practice classification and task analysis. Being this a qualitative research our main question was: in assessing sports structure is it possible to make the characterization of any discipline through context and individuals behaviours? The sample was within a surf discipline in a competition flowing having 5 of the top 16 Portuguese surfers training together. Based on a qualitative method, studying the surf as the main activity was an interpretative study case. The MAST was applied in four phases: taxonomy; tasks and context description; task analysis; teaching and performance strategies. Its application allowed the activities characterization through the observation, surfers opinions and bibliographical support. The triangulation of the data was used as an information data treatment. The elements were classified by the challenges proposed to the practitioners and the taxonomy was constituted by the sport activities, group, modality and discipline. Surf is a discipline of surfing which is a sliding sport modality, therefore, a nature sport. In the context description, we had the waves components and constraints and the surfboards qualities. Through task analysis we obtained a taxonomy of surf manoeuvres. The structural and functional analysis allowed finding solutions for learning of surf techniques with trampoline and skateboards because these fit in sliding sports. MAST makes possible the development of strategies that benefit teaching and performance intervention. PMID:25414757

  13. CONTAMINATED SEDIMENT TESTING WITH THE BIVALVE, MULINA LATERALIS: CULTURE REFINEMENT FOR ORGANISM AVAILABILITY

    EPA Science Inventory

    Availability of test species for estuarine benthic assessment is limited; therefore, a method was developed by the U.S. Environmental Protection Agency for using the dwarf surf clam (Mulinia lateralis) to identify adverse biological effects of bulk estuarine sediments. A multilab...

  14. CONTAMINATED SEDIMENT TESTING WITH THE BIVLVE, MULINIA LATERLALIS: CULTURE REFINEMENT FOR ORGANISM AVAILABILITY

    EPA Science Inventory

    Availability of test species for estuarine benthic assessment is limited; therefore, a method was developed by the U.S. Environmental Protection Agency for utilizing the dwarf surf clam, Mulinia lateralis, to identify adverse biological effects of bulk estuarine sediments. A mult...

  15. Star Formation in Dwarf-Dwarf Mergers: Fueling Hierarchical Assembly

    NASA Astrophysics Data System (ADS)

    Stierwalt, Sabrina; Johnson, K. E.; Kallivayalil, N.; Patton, D. R.; Putman, M. E.; Besla, G.; Geha, M. C.

    2014-01-01

    We present early results from the first systematic study a sample of isolated interacting dwarf pairs and the mechanisms governing their star formation. Low mass dwarf galaxies are ubiquitous in the local universe, yet the efficiency of gas removal and the enhancement of star formation in dwarfs via pre-processing (i.e. dwarf-dwarf interactions occurring before the accretion by a massive host) are currently unconstrained. Studies of Local Group dwarfs credit stochastic internal processes for their complicated star formation histories, but a few intriguing examples suggest interactions among dwarfs may produce enhanced star formation. We combine archival UV imaging from GALEX with deep optical broad- and narrow-band (Halpha) imaging taken with the pre- One Degree Imager (pODI) on the WIYN 3.5-m telescope and with the 2.3-m Bok telescope at Steward Observatory to confirm the presence of stellar bridges and tidal tails and to determine whether dwarf-dwarf interactions alone can trigger significant levels of star formation. We investigate star formation rates and global galaxy colors as a function of dwarf pair separation (i.e. the dwarf merger sequence) and dwarf-dwarf mass ratio. This project is a precursor to an ongoing effort to obtain high spatial resolution HI imaging to assess the importance of sequential triggering caused by dwarf-dwarf interactions and the subsequent affect on the more massive hosts that later accrete the low mass systems.

  16. M dwarfs: Theoretical work

    NASA Technical Reports Server (NTRS)

    Mullan, Dermott J.

    1987-01-01

    Theoretical work on the atmospheres of M dwarfs has progressed along lines parallel to those followed in the study of other classes of stars. Such models have become increasingly sophisticated as improvements in opacities, in the equation of state, and in the treatment of convection were incorporated during the last 15 to 20 years. As a result, spectrophotometric data on M dwarfs can now be fitted rather well by current models. The various attempts at modeling M dwarf photospheres in purely thermal terms are summarized. Some extensions of these models to include the effects of microturbulence and magnetic inhomogeneities are presented.

  17. GERMINOMAS AND TERATOID SIPHON ANOMALIES IN SOFTSHELL CLAMS, MYA ARENARIA, ENVIRONMENTALLY EXPOSED TO HERBICIDES

    EPA Science Inventory

    Seminomas and dysgerminomas are episodic in softshell clams, Mya arenaria, from three Maine estuaries contaminated with herbicides. he first epizootic was discovered in 22% of clams collected as Searsport near Long Cove Brook and three culverts that conveyed heating oil and jet f...

  18. 50 CFR 17.45 - Special rules-snails and clams. [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 2 2012-10-01 2012-10-01 false Special rules-snails and clams. 17.45 Section 17.45 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR... Special rules—snails and clams....

  19. 50 CFR 17.45 - Special rules-snails and clams. [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 2 2010-10-01 2010-10-01 false Special rules-snails and clams. 17.45 Section 17.45 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR... Special rules—snails and clams....

  20. 50 CFR 17.45 - Special rules-snails and clams. [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 2 2014-10-01 2014-10-01 false Special rules-snails and clams. 17.45 Section 17.45 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR... Special rules—snails and clams....

  1. 50 CFR 17.45 - Special rules-snails and clams. [Reserved

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 2 2013-10-01 2013-10-01 false Special rules-snails and clams. 17.45 Section 17.45 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR... Special rules—snails and clams....

  2. EFFECTS OF ELEVATED AMMONIA LEVELS ON THE FINGERNAIL CLAM, 'MUSCULIUM TRANSVERSUM', IN OUTDOOR EXPERIMENTAL STREAMS

    EPA Science Inventory

    The effects of ammonia on survival, growth, and reproduction of the fingernail clam. Musculium transversum were tested in outdoor experimental streams. In the summers of 1983 and 1984 caged clams were exposed in the streams. During the 1983 studies, the weekly mean NH 3 ranges in...

  3. Factors affecting growth and survival of the asiatic clam Corbicula sp. under controlled laboratory conditions

    SciTech Connect

    Double, D.D.; Daly, D.S.; Abernethy, C.S.

    1983-04-01

    Growth of Corbicula sp. was determined in relation to food supply, water temperature, and clam size as an aid to researchers conducting chronic effects toxicity studies. Water temperatures for the two 84-day test series were 10, 20, and 30/sup 0/C. Linear models provided good relationships (r/sup 2/ > 0.90) between clam shell length (SL), total weight (TW), and wet/dry tissue weights. Clam growth was minimal during low phytoplankton densities (approx. 300 cells/ml), and all three size groups lost weight at 20 and 30/sup 0/C. Mortality of small clams at 30/sup 0/C was 100% after 71 days. At phytoplankton densities > 1000 cells/ml, overall differences in growth with respect to clam size and temperature were detectable at p < 0.01; growth of all clam groups was greatest at 30/sup 0/C. Small clams exhibited the greatest absolute increase in mean shell length at all test temperatures, and weight gains were similar to those of medium and large clams.

  4. Photon surfing and magic speed revisited: Translucent effect

    NASA Astrophysics Data System (ADS)

    Fukue, Jun

    2014-02-01

    Under the radiative environment of the intense radiation field around active phenomena such as black hole accretion disks, gaseous particles receive a strong radiative flux, which accelerates them, while they suffer from radiation drag by aberrated photons, which decelerates them. As a result, the acceleration of gaseous particles-photon surfing-would terminate at some magical speed ?m(=v/c); (4-?7)/3 0.45 for acceleration above an infinite flat radiator (Icke 1989, A&A, 216, 294). In a realistic gaseous cloud, part of the radiation would be absorbed by the cloud, some would be reflected, and some transmitted. We examine these translucent effects for a geometrically thin gaseous cloud (stratus). When the optical depth of the stratus is sufficiently large, the terminal speed is the well known magical speed ?m for a particle. When the optical depth is around or less than unity, on the other hand, the terminal magical speed becomes large, up to 0.7c. This is just the translucent effect; the aberrated photons from the top of the stratus transmit the stratus much more than the direct photons from the bottom of the stratus facing the source.

  5. Multiple biomarkers of biological effects induced by cadmium in clam Ruditapes philippinarum.

    PubMed

    Ji, Chenglong; Wu, Huifeng; Zhou, Mo; Zhao, Jianmin

    2015-06-01

    Cadmium (Cd) is a known heavy metal pollutant in the Bohai Sea. Manila clam Ruditapes philippinarum is an important fishery species along the Bohai coast. In this study, the biological effects induced by two concentrations (20 and 200 ?g/L) of Cd were characterized using multiple biochemical indices in the digestive glands of clam R. philippinarum. The total hemocyte counts, reactive oxygen species productions and antioxidant enzyme activities exhibited that Cd induced dose-dependent immune and oxidative stresses in clam digestive glands. Metabolic responses indicated that both Cd exposures caused immune stress marked by the elevated branched chain amino acids (valine, leucine and isoleucine), together with the disturbance in energy metabolism. The differential metabolic biomarkers related to osmotic stress, including homarine, betaine, tyrosine and phenylalanine, suggested the differential responsive mechanisms in clam digestive glands induced by Cd exposures. In addition, both Cd treatments enhanced the anaerobiosis metabolism in clam digestive glands via differential metabolic pathways. PMID:25804494

  6. Mercury accumulation in the clam, Galatea paradoxa (Born 1778) at the Volta estuary, Ghana.

    PubMed

    Obirikorang, K A; Amisah, S; Adjei-Boateng, D; Madkour, H A; Otchere, F A

    2010-11-01

    The concentration of mercury in the tissues of the clam, Galatea paradoxa at in the Volta estuary, Ghana, were analysed over an 18-month period, from March 2008 to August 2009. The concentrations were well below the International Human Consumption Advisory Limit of THg (0.5 ?g/g wet weight). The concentrations in the tissues of the different clam size classes were between 6 and 18 times lower than the WHO Safety Reference Standard. Variation in the mean mercury concentration in the different clam size classes was not significant (p > 0.05) for clams from Aveglo but were highly significant (p < 0.0001) for clams from Ada, indicating a possible effect of size on accumulation. G. paradoxa is therefore suitable for human consumption based on the WHO Safety Reference Standards. PMID:20972534

  7. Surf zone entrainment, along-shore transport, and human health implications of pollution from tidal outlets

    NASA Astrophysics Data System (ADS)

    Grant, S. B.; Kim, J. H.; Jones, B. H.; Jenkins, S. A.; Wasyl, J.; Cudaback, C.

    2005-10-01

    Field experiments and modeling studies were carried out to characterize the surf zone entrainment and along-shore transport of pollution from two tidal outlets that drain into Huntington Beach and Newport Beach, popular public beaches in southern California. The surf zone entrainment and near-shore transport of pollutants from these tidal outlets appears to be controlled by prevailing wave conditions and coastal currents, and fine-scale features of the flow field around the outlets. An analysis of data from dye experiments and fecal indicator bacteria monitoring studies reveals that the along-shore flux of surf zone water is at least 50 to 300 times larger than the cross-shore flux of surf zone water. As a result, pollutants entrained in the surf zone hug the shore, where they travel significant distances parallel to the beach before diluting to extinction. Under the assumption that all surf zone pollution at Huntington Beach originates from two tidal outlets, the Santa Ana River and Talbert Marsh outlets, models of mass and momentum transport in the surf zone approximately capture the observed tidal phasing and magnitude of certain fecal indicator bacteria groups (total coliform) but not others (Escherichia coli and enterococci), implying the existence of multiple sources of, and/or multiple transport pathways for, fecal pollution at this site. The intersection of human recreation and near-shore pollution pathways implies that, from a human health perspective, special care should be taken to reduce the discharge of harmful pollutants from land-side sources of surface water runoff, such as tidal outlets and storm drains.

  8. Relationships between intertidal clam population and health status of the soft-shell clam Mya arenaria in the St. Lawrence Estuary and Saguenay Fjord (Qubec, Canada).

    PubMed

    Gagn, F; Blaise, C; Pellerin, J; Fournier, M; Durand, M J; Talbot, A

    2008-01-01

    The purpose of this study was to examine the impacts of anthropogenic activity on the health status of intertidal clam populations of the Saguenay Fjord and the St. Lawrence Estuary (Qubec, Canada). Clams were collected during low tide at sites subject to direct contamination and at sites far from human activity. Clams were analyzed for tributyltin and dibutyltin total levels and toxic stress (glutathione S-transferase, gonadal lipid peroxidation and DNA strand breaks), immunocompetence (phagocytic activity, hemocyte count and viability), reproduction (gonado-somatic index, gamete maturation, and vitellogenin-like proteins), energy status (temperature-dependent mitochondrial electron transport, and gonad lipids), and individual status (age, condition factor, and growth index). These responses were compared against population characteristics such as live clam density, number of empty shells, and sex ratio. The results show that clam density decreased with distance from the estuary (high salinity level) to upstream of the fjord (low salinity). There was no clear relationship between the number of empty shells and distance or site quality. Clam density values corrected against distance were significantly correlated with hemocyte viability, phagocytic activity, mitochondrial electron transport (MET), DNA damage in gonad, and temperature-dependent mitochondrial electron transport activity. A canonical analysis of the various groups of biomarkers revealed that population metrics were more strongly related with immunocompetence, followed by energy status and temperature-dependent mitochondrial electron transport activity. However, toxic stress biomarkers were strongly associated with energy status and reproduction. This was further confirmed by non-linear modeling using adaptive artificial neural networks (genetic selection and back propagation learning paradigms), where the following parameters were able to predict population parameters with <20% error: gonad maturation and somatic index, MET (at 4 degrees C), gonad LPO, DNA damage, and phagocytic capacity. Intertidal clam populations were influenced by a distance gradient effect (salinity), where immunocompetence, in addition to energy status, was the strongest physiological parameter related to clam population metrics. PMID:17825412

  9. Understanding Brown Dwarf Variability

    NASA Technical Reports Server (NTRS)

    Marley, Mark S.

    2013-01-01

    Surveys of brown dwarf variability continue to find that roughly half of all brown dwarfs are variable. While variability is observed amongst all types of brown dwarfs, amplitudes are typically greatest for L-T transition objects. In my talk I will discuss the possible physical mechanisms that are responsible for the observed variability. I will particularly focus on comparing and contrasting the effects of changes in atmospheric thermal profile and cloud opacity. The two different mechanisms will produce different variability signatures and I will discuss the extent to which the current datasets constrain both mechanisms. By combining constraints from studies of variability with existing spectral and photometric datasets we can begin to construct and test self-consistent models of brown dwarf atmospheres. These models not only aid in the interpretation of existing objects but also inform studies of directly imaged giant planets.

  10. Prevalence and distribution of QPX, Quahog Parasite Unknown, in hard clams Mercenaria mercenaria in Virginia, USA.

    PubMed

    Ragone Calvo, L M; Walker, J G; Burreson, E M

    1998-07-30

    In July 1996, the Virginia Institute of Marine Science initiated a sampling program to examine wild and cultured hard clams Mercenaria mercenaria for QPX, Quahog Parasite Unknown, a protistan parasite associated with severe mortalities of hard clams in localized areas in maritime Canada and Massachusetts, USA. The sampling program set out to seasonally monitor wild clams from one site, James River, Virginia, and cultured clams from 2 sites, Chincoteague Bay and Mattawoman Creek, Virginia. Histological examination of initial samples revealed 8% prevalence of the parasite in 1-2 yr old cultured clams in Chincoteague Bay. This is the first documentation of QPX in Virginia. To ascertain the distribution of the parasite in Virginia, the survey was expanded between August 1996 and July 1997 to include 16 additional sites. A total of 1305 wild and cultured clams was sampled from Chesapeake Bay tributaries and coastal areas where harvest and culture occur. QPX was not found in Chesapeake Bay, but was present in cultured clams from 3 coastal embayments--the original Chincoteague Bay site, Burton Bay and Quinby Inlet. The parasite was found in Chincoteague Bay at each sample period at prevalences ranging from 8 to 48%. Infections were generally light to moderate intensity and were most often observed in mantle and gill tissues. The maximum prevalence was observed in May 1997 and coincided with notable clam mortalities. QPX prevalences at the other sites were low, ranging from 4 to 15%. To date QPX has not had a significant impact on Virginia's hard clam fishery and aquaculture industry; however, the presence of the pathogen in 3 of the state's most productive hard clam growout areas warrants continued monitoring and research. PMID:9745718

  11. Declining populations of the fingernail clam Musculium transversum in the upper Mississippi River

    USGS Publications Warehouse

    Wilson, D.M.; Naimo, T.J.; Weiner, J.G.; Anderson, R.V.; Sandheinrich, M.B.; Sparks, R.E.

    1995-01-01

    We examined recent temporal trends in the abundance of fingernail clams Musculium transversum (formerly Sphaerium transversum) in the upper Mississippi River. Historical data on densities of fingernail clams were obtained from regional scientists and published literature. We also sampled benthos in six navigation pools in summer 1991, finding very few fingernail clams. The combined data set, including historical data and sampling results, extended from 1973 to 1992 and was sufficient to statistically evaluate trends in densities of fingernail clams in eight pools. Populations of fingernail clams declined significantly in five of the eight pools examined (Pools 2, 5, 7, 9, and 19), which spanned a 700-km reach of river from St. Paul, Minnesota, to Keokuk, Iowa. Densities in Pool 19, which had the longest historical record on fingernail clam abundance, averaged 30 000 m super(-2) in 1985 and progressively declined to zero in 1990. Combined data from all eight pools showed a significant decline in abundance of fingernail clams. An evaluation of potential causal factors led us to hypothesize that the population declines in Pools 2 to 9 were linked to point-source pollution rather than to dredging activity or commercial navigation traffic. In Pool 19, the declines of fingernail clams may have resulted from low-flow conditions during drought periods, but the causal mechanisms by which low flow influences fingernail clam abundance are unclear. The decrease in fingernail clam populations may adversely affect certain fish and wildlife, such as migrating lesser scaup Aythya affinis, which feed heavily on the small mollusk. Moreover, the decreases in populations of this pollution-sensitive mollusk may signal a large-scale deterioration in the health of this riverine ecosystem.

  12. Mechanical properties and microstructure evolution of CLAM Steel in tube fabrication and test blanket module assembly

    NASA Astrophysics Data System (ADS)

    Huang, Bo; Huang, Qunying; Li, Yanfen; Li, Chunjing; Wu, Qingsheng; FDS Team

    2013-11-01

    The first wall of the China dual functional lithium lead-test blanket module (DFLL-TBM) will be assembled with China low activation martensitic (CLAM) steel rectangular tubes and plates by hot isostatic pressing (HIP) - diffusion welding. The objective of this study is to evaluate CLAM rectangular tubes and investigate mechanical property and microstructure evolution of CLAM steel in tube fabrication and TBM assembly. In this work, CLAM rectangular tubes with lengths of 1500 mm were fabricated, and the dimensional accuracy met the requirement for HIP joining. In the tube fabrication process, the CLAM steel was annealed to improve its ductility. In addition, the anisotropy in mechanical properties and microstructure introduced by tube rolling was eliminated according to the simulation of HIP heat treatment in TBM preparation. The tensile strength of the CLAM tubes with final heat treatment was slightly higher than that of CLAM steel with the published standard heat treatment, while the total elongation was reduced. This revealed that a post-HIP heat treatment was required before the final heat treatment. An annealing treatment at 1253 K transformed martensite to ferrite, decreased the tensile strength, and increase the ductility; Rolling deformation introduced microstructural anisotropy, increased the Vickers hardness, and created an inhomogeneous hardness distribution; A simulated HIP heat treatment schedule removed these differences in hardness and tensile strength due to the anisotropy; The tensile strength of CLAM tube material given the published standard heat treatment (with the simulated HIP heat treatment) was higher than that of previously published CLAM steel results and the elongation was reduced. Therefore, a post-HIP heat treatment for CLAM tube material appears to be required before applying a final heat treatment based on the prior standard heat treatment in order to preserve the overall tensile elongation.

  13. Dwarfs in ancient Egypt.

    PubMed

    Kozma, Chahira

    2006-02-15

    Ancient Egypt was one of the most advanced and productive civilizations in antiquity, spanning 3000 years before the "Christian" era. Ancient Egyptians built colossal temples and magnificent tombs to honor their gods and religious leaders. Their hieroglyphic language, system of organization, and recording of events give contemporary researchers insights into their daily activities. Based on the record left by their art, the ancient Egyptians documented the presence of dwarfs in almost every facet of life. Due to the hot dry climate and natural and artificial mummification, Egypt is a major source of information on achondroplasia in the old world. The remains of dwarfs are abundant and include complete and partial skeletons. Dwarfs were employed as personal attendants, animal tenders, jewelers, and entertainers. Several high-ranking dwarfs especially from the Old Kingdom (2700-2190 BCE) achieved important status and had lavish burial places close to the pyramids. Their costly tombs in the royal cemeteries and the inscriptions on their statutes indicate their high-ranking position in Egyptian society and their close relation to the king. Some of them were Seneb, Pereniankh, Khnumhotpe, and Djeder. There were at least two dwarf gods, Ptah and Bes. The god Ptah was associated with regeneration and rejuvenation. The god Bes was a protector of sexuality, childbirth, women, and children. He was a favored deity particularly during the Greco-Roman period. His temple was recently excavated in the Baharia oasis in the middle of Egypt. The burial sites and artistic sources provide glimpses of the positions of dwarfs in daily life in ancient Egypt. Dwarfs were accepted in ancient Egypt; their recorded daily activities suggest assimilation into daily life, and their disorder was not shown as a physical handicap. Wisdom writings and moral teachings in ancient Egypt commanded respect for dwarfs and other individuals with disabilities. PMID:16380966

  14. Arctic stratospheric ice nucleation and dehydration within CLaMS

    NASA Astrophysics Data System (ADS)

    Tritscher, Ines; Groo, Jens-Uwe; Mller, Rolf

    2015-04-01

    Polar stratospheric clouds (PSCs) provide the surface for heterogeneous reactions enhancing concentrations of active, ozone destroying chlorine and thereby cause polar ozone loss in late winter and early spring. The understanding of PSC microphysics is therefore essential to simulate polar ozone accurately. The Chemical Lagrangian Model of the Stratosphere (CLaMS) allows growth, evaporation, and gravitational settling of individual cloud particles to be calculated along their trajectories. Particles consisting of nitric acid trihydrate (NAT) were the focus of previous work and are known for their potential to denitrify the polar stratosphere by sedimentation. This study goes a step further and deals with the nucleation of ice particles and related dehydration, i.e. irreversible redistribution of water vapor. Homogeneous and heterogeneous nucleation of ice particles have been considered. Finally, we will also include NAT formation downwind of ice clouds. To start with, we concentrate on the Arctic winter 2009/2010, which is already well characterized because of the RECONCILE campaign and connected work. Unusually low temperatures at stratospheric levels led to the formation of synoptic-scale ice PSCs for a week-long period. We present CLaMS results in comparison to PSC observations from the cloud-aerosol lidar CALIOP. Moreover, we juxtapose CLaMS simulations of water vapor with single balloon-borne measurements as well as with vortex-wide MLS observations. The hemispheric picture allows tracking dehydrated air masses around the vortex. Changes in the denitrification pattern, which might arise due to the implementation of ice particles, will be discussed.

  15. Solar winds surfs waves in the Sun's atmosphere!

    NASA Astrophysics Data System (ADS)

    1999-06-01

    The fact that this electrified plasma speeds up to almost 3 million kilometres per hour as it leaves the Sun - twice as fast as originally predicted - has been known for years. The interpretation of how it happens is the real and surprising novelty: "The waves in the Sun's atmosphere are produced by vibrating solar magnetic field lines, which give solar wind particles a push just like an ocean wave gives a surfer a ride" said Dr John Kohl, principal investigator for the Ultraviolet Coronal Spectrometer (UVCS) - the instrument among the 12 aboard SOHO which gathered the data - and for the Spartan 201 mission. The outermost solar atmosphere, or corona, is only seen from Earth during a total eclipse of the Sun, when it appears as a shimmering, white veil surrounding the black lunar disc. The corona is an extremely tenuous, electrically charged gas, known as plasma, that flows throughout the solar system as the solar wind. The waves are formed by rapidly vibrating magnetic fields in the coronal plasma. They are called magneto - hydro - dynamic (MHD) waves and are believed to accelerate the solar wind. The solar wind is made up of electrons and ions, electrically charged atoms that have lost electrons. The electric charge of the solar wind particles forces them to travel along invisible lines of magnetic force in the corona. The particles spiral around the magnetic field lines as they rush into space. "The magnetic field acts like a violin string: when it's touched, it vibrates. When the Sun's magnetic field vibrates with a frequency equal to that of the particle spiraling around the magnetic field, it heats it up, producing a force that accelerates the particle upward and away from the Sun," says Dr. Ester Antonucci, an astronomer at the observatory of Turin, Italy, and co-investigator for SOHO's UVCS an instrument developed with considerable financial support by the Italian Space Agency, ASI. In a way this is similar to what happens if two people hold a string at opposite ends after threading it through an object, like a ring. If one person wiggles the string rapidly up and down, waves form in the string that move toward the person at the other end. The ring will "surf" these waves and move toward the other person as well. Try it! "Even with this major discovery, there are questions left to answer. The observations have made it abundantly clear that heavy particles like oxygen 'surf' on the waves, and there is also mounting evidence that waves are responsible for accelerating the hydrogen atoms, the most common constituent of the solar wind. Future observations are needed to establish this fact. Many other kinds of particles, such as helium (second most common) have never been observed in the accelerating part of the corona, and new observations are also needed to refine our understanding of how the waves interact with the solar wind as a whole," said Dr. Steven Cranmer of the Harvard-Smithsonian Center for Astrophysics, lead author of the research to be published in the Astrophysical Journal*. Nevertheless, SOHO has again been able to reveal another of the Sun's mysteries: "This is another triumph for SOHO, stealing a long-held secret from our Sun", said Dr Martin Huber, Head of ESA Space Science Department and co-investigator for UVCS. *Ref. Article by S.Cranmer, G.B. Field and J.L. Kohl on Astrophysical Journal ( June 20, Vol 518, p. 937-947) available on the web at: http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v518n2/39802/sc0.html

  16. Solar winds surfs waves in the Sun's atmosphere!

    NASA Astrophysics Data System (ADS)

    1999-07-01

    The fact that this electrified plasma speeds up to almost 3 million kilometres per hour as it leaves the Sun - twice as fast as originally predicted - has been known for years. The interpretation of how it happens is the real and surprising novelty: "The waves in the Sun's atmosphere are produced by vibrating solar magnetic field lines, which give solar wind particles a push just like an ocean wave gives a surfer a ride" said Dr John Kohl, principal investigator for the Ultraviolet Coronal Spectrometer (UVCS) - the instrument among the 12 aboard SOHO which gathered the data - and for the Spartan 201 mission. The outermost solar atmosphere, or corona, is only seen from Earth during a total eclipse of the Sun, when it appears as a shimmering, white veil surrounding the black lunar disc. The corona is an extremely tenuous, electrically charged gas, known as plasma, that flows throughout the solar system as the solar wind. The waves are formed by rapidly vibrating magnetic fields in the coronal plasma. They are called magneto - hydro - dynamic (MHD) waves and are believed to accelerate the solar wind. The solar wind is made up of electrons and ions, electrically charged atoms that have lost electrons. The electric charge of the solar wind particles forces them to travel along invisible lines of magnetic force in the corona. The particles spiral around the magnetic field lines as they rush into space. "The magnetic field acts like a violin string: when it's touched, it vibrates. When the Sun's magnetic field vibrates with a frequency equal to that of the particle spiraling around the magnetic field, it heats it up, producing a force that accelerates the particle upward and away from the Sun," says Dr. Ester Antonucci, an astronomer at the observatory of Turin, Italy, and co-investigator for SOHO's UVCS an instrument developed with considerable financial support by the Italian Space Agency, ASI. In a way this is similar to what happens if two people hold a string at opposite ends after threading it through an object, like a ring. If one person wiggles the string rapidly up and down, waves form in the string that move toward the person at the other end. The ring will "surf" these waves and move toward the other person as well. Try it! "Even with this major discovery, there are questions left to answer. The observations have made it abundantly clear that heavy particles like oxygen 'surf' on the waves, and there is also mounting evidence that waves are responsible for accelerating the hydrogen atoms, the most common constituent of the solar wind. Future observations are needed to establish this fact. Many other kinds of particles, such as helium (second most common) have never been observed in the accelerating part of the corona, and new observations are also needed to refine our understanding of how the waves interact with the solar wind as a whole," said Dr. Steven Cranmer of the Harvard-Smithsonian Center for Astrophysics, lead author of the research to be published in the Astrophysical Journal*. Nevertheless, SOHO has again been able to reveal another of the Sun's mysteries: "This is another triumph for SOHO, stealing a long-held secret from our Sun", said Dr Martin Huber, Head of ESA Space Science Department and co-investigator for UVCS. *Ref. Article by S.Cranmer, G.B. Field and J.L. Kohl on Astrophysical Journal ( June 20, Vol 518, p. 937-947) available on the web at: http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v518n2/39802/sc0.html

  17. Comparative investigations on the biological effects of As (III) and As (V) in clam Ruditapes philippinarum using multiple biomarkers.

    PubMed

    Ji, Chenglong; Xu, Hai'e; Wang, Qing; Zhao, Jianmin; Wu, Huifeng

    2015-11-01

    Inorganic arsenic is a known pollutant with two chemical forms, arsenite (As (III)) and arsenate (As (V)), in marine environment. Clam Ruditapes philippinarum is an important fishery species along the Bohai coast. In this study, the biological effects induced by the two arsenic chemical forms (arsenite and arsenate) were compared using multiple biochemical indices in the digestive glands of clam R. philippinarum. The production of reactive oxygen species, antioxidant enzyme activities and metabolic responses exhibited that both As (III) and As (V) induced immune, oxidative and osmotic stresses in clam digestive glands. The differential metabolic biomarkers, histidine and taurine, indicated the differential responsive mechanisms in osmotic regulation in clam digestive glands. In addition, both arsenic treatments enhanced the anaerobiosis metabolism in clam digestive glands. Overall, this work illustrated that arsenite and arsenate induced similar biological effects in clams, which might be accounted for the biological transformation of arsenate to arsenite in clams. PMID:26327115

  18. Cluster of Leptospirosis Acquired Through River Surfing in Switzerland.

    PubMed

    Schreiber, Peter W; Aceto, Leonardo; Korach, Raphael; Marreros, Nelson; Ryser-Degiorgis, Marie-Pierre; Günthard, Huldrych F

    2015-09-01

    Background.  In Switzerland, leptospirosis is still considered as a travel-associated disease. After the surprising diagnosis of leptospirosis in a patient who was initially suspected as having primary human immunodeficiency virus infection, we recognized that acquisition of leptospirosis occurred through recreational activities and we identified additional affected individuals. Methods.  Detailed anamnesis, excluding occupational exposure, acquisition abroad, and pet contacts, enabled us to detect the source of infection and identify a cluster of leptospirosis. Convalescent sera testing was performed to confirm Leptospira infection. Microscopic agglutination tests were used to determine the infecting serovar. Results.  We identified a cluster of leptospirosis in young, previously healthy persons. Acquisition of leptospirosis was traced back to a surfing spot on a river in Switzerland (Reuss, Aargau). Clinical presentation was indistinct. Two of the 3 reported cases required hospitalization, and 1 case even suffered from meningitis. Serologic tests indicated infection with the serovar Grippotyphosa in all cases. With the exception of the case with meningitis, no antibiotics were administered, because leptospirosis was diagnosed after spontaneous resolution of most symptoms. Despite a prolonged period of convalescence in 2 cases, full recovery was achieved. Recent reports on beavers suffering from leptospirosis in this region underline the possible water-borne infection of the 3 cases and raise the question of potential wildlife reservoirs. Conclusions.  Insufficient awareness of caregivers, which may be promoted by the missing obligation to report human leptospirosis, combined with the multifaceted presentation of the disease result in significant underdiagnosis. More frequent consideration of leptospirosis as differential diagnosis is inevitable, particularly as veterinary data suggest re-emergence of the disease. PMID:26269796

  19. Cluster of Leptospirosis Acquired Through River Surfing in Switzerland

    PubMed Central

    Schreiber, Peter W.; Aceto, Leonardo; Korach, Raphael; Marreros, Nelson; Ryser-Degiorgis, Marie-Pierre; Günthard, Huldrych F.

    2015-01-01

    Background. In Switzerland, leptospirosis is still considered as a travel-associated disease. After the surprising diagnosis of leptospirosis in a patient who was initially suspected as having primary human immunodeficiency virus infection, we recognized that acquisition of leptospirosis occurred through recreational activities and we identified additional affected individuals. Methods. Detailed anamnesis, excluding occupational exposure, acquisition abroad, and pet contacts, enabled us to detect the source of infection and identify a cluster of leptospirosis. Convalescent sera testing was performed to confirm Leptospira infection. Microscopic agglutination tests were used to determine the infecting serovar. Results. We identified a cluster of leptospirosis in young, previously healthy persons. Acquisition of leptospirosis was traced back to a surfing spot on a river in Switzerland (Reuss, Aargau). Clinical presentation was indistinct. Two of the 3 reported cases required hospitalization, and 1 case even suffered from meningitis. Serologic tests indicated infection with the serovar Grippotyphosa in all cases. With the exception of the case with meningitis, no antibiotics were administered, because leptospirosis was diagnosed after spontaneous resolution of most symptoms. Despite a prolonged period of convalescence in 2 cases, full recovery was achieved. Recent reports on beavers suffering from leptospirosis in this region underline the possible water-borne infection of the 3 cases and raise the question of potential wildlife reservoirs. Conclusions. Insufficient awareness of caregivers, which may be promoted by the missing obligation to report human leptospirosis, combined with the multifaceted presentation of the disease result in significant underdiagnosis. More frequent consideration of leptospirosis as differential diagnosis is inevitable, particularly as veterinary data suggest re-emergence of the disease. PMID:26269796

  20. Predicting coexistence and predominance patterns between the introduced Manila clam (Ruditapes philippinarum) and the European native clam (Ruditapes decussatus)

    NASA Astrophysics Data System (ADS)

    Bidegain, Gorka; Bárcena, Javier Francisco; García, Andrés; Juanes, José Antonio

    2015-01-01

    In several European estuaries, the introduced Manila clam (Ruditapes philippinarum) has become a widespread and predominating species supplanting the native carpet shell clam (Ruditapes decussatus) whereas in other estuaries such as the Bay of Santander (Gulf of Biscay) this pattern has not been detected. Using this estuary as a case study, the potential coexistence/predominance patterns between these two species were explored with the objective of providing insight into the capacity of expansion of R. philippinarum. Firstly, the Ecological Niche Factor Analysis (ENFA) was applied to determine the niches of both species, using seven contemporary environmental variables, i.e. salinity, water depth, current velocity, and sediment sand, gravel, silt and organic matter content. Secondly, ENFA-derived habitat-suitability (HS) maps were simultaneously treated, using geospatial techniques and following HS index-based criteria, to determine the potential distribution patterns. Both species models performed well according to the cross-validation evaluation method. The environmental variables that most determined the presence of both clams were depth, current velocity and salinity. ENFA factors showed that R. philippinarum habitat differs more from the mean environmental conditions over the estuary (i.e. higher marginality) and has less narrow requirements (i.e. lower specialization). R. philippinarum dominated areas, determined by relatively lower current velocities and percentages of sand, higher organic matter contents and slightly shallower depths, were very reduced (i.e. 2.0% of the bay surface) compared to coexistence (47%) and R. decussatus predominance areas (7.4%). These results suggest that HS may regulate the expansion of R. philippinarum. ENFA, together with geospatial analysis of HS index, seems to be a valuable approach to explore the expansion potential of estuarine invasive or introduced species and thus support conservation decisions regarding native species.

  1. Temporal occurrence of Cryptosporidium in the Manila clam Ruditapes philippinarum in northern Adriatic Italian lagoons.

    PubMed

    Molini, Umberto; Traversa, Donato; Ceschia, Giuseppe; Iorio, Raffaella; Boffo, Luciano; Zentilin, Aurelio; Capelli, Gioia; Giangaspero, Annunziata

    2007-02-01

    In order to evaluate the temporal occurrence of Cryptosporidium oocysts in Ruditapes philippinarum clams bred along the northeastern Italian Adriatic coast and molecularly characterize the isolates, 2,160 specimens (180 clams per month) were collected from three clam farms from January to December 2004. Two farms (sites A and B) were located in Venice (Chioggia, Veneto region) and one (site C) in the Marano Lagoons (Friuli Venezia Giulia region). Clams from 36 pools (i.e., one pool of 60 clams per month per site) were subjected to a high-sensitivity seminested PCR assay specific for a 360-bp diagnostic region internal to the Cryptosporidium spp. outer wall protein gene. Positive amplicons were sequenced and analyzed. Cryptosporidium DNA was found in clams from seven pools (sites A and B) during 1 month of sampling at site A and 6 months of sampling at site B, with Cryptosporidium hominis and Cryptosporidium parvum being detected. The expected infection rate of the clams was 0.36%. Site B showed a significantly higher expected infection rate (1.15%) than did the other sites (A = 0.14% and C = 0%). Given its high sensitivity and specificity, this seminested PCR assay can be considered a reliable tool for detecting and distinguishing species within the Cryptosporidium genus. The seasonal pattern of contamination and the related public health risks are of particular concern. PMID:17340889

  2. Recovery of intertidal hardshelled clams in Prince William Sound from Exxon Valdez oiling and shoreline treatments

    SciTech Connect

    Houghton, J.P.; Lees, D.C.; Driskell, W.B.

    1994-12-31

    Native little neck (Protothaca staminea) and butter clams (Saxidomus giganteus) were quantitatively surveyed from 1989 through 1993 to evaluate effects from the Exxon Valdez oil spill. Hydraulic washing of sand and gravel beaches altered beach morphology by transporting material down slope from upper elevations, often burying the lower beach in several centimeters of sediment having a relatively low content of fines and organic carbon. Hydraulically washed beaches showed significant reductions in clam densities in 1989 and 1990. Recruitment of clams was very limited on these beaches through 1993; as a result, clam densities on these hydraulically washed beaches remain very depressed compared to those on beaches that were unoiled or oiled but not washed. Littlenecks transplanted from a reference site to a heavily oiled but untreated site showed significant patterns of increased mortality, decreased growth, and increased bioaccumulation of PAH in response to a gradient in sediment PAH, This same heavily oiled site has consistently had among the highest rates of hardshelled clam recruitment of any of the sites sampled. Littlenecks also were transplanted to another heavily oiled beach that had been hydraulically washed and had little remaining hydrocarbons. These clams showed very high survival, yet this beach has had very little clam recruitment. It is hypothesized that recruitment at this site may be inhibited by the low level of finer sediments and low organic content remaining after washing.

  3. Early reproductive success of the hard clam (Mercenaria mercenaria) from Five Sites in Long Island Sound

    SciTech Connect

    Stiles, S.; Choromanski, J.; Nelson, D.; Miller, J.; Greig, R.; Sennefelder, G. )

    1991-09-01

    Early reproductive success of hard clams (Mercenaria mercenaria) in Long Island Sound was measured to determine whether pollution may have adverse effects on fragile recruitment to fisheries. Clams were collected at five sites in 1987 when ready to spawn naturally, along with water from within 39 cm of the bottom. Levels of polychlorinated biphenyls (PCBs), copper, and cadmium were measured in the mature gonad and were found to be generally low. Clams were spawned and the gametes were collected and cultured both in their respective site waters and in reference laboratory seawater. In both site and reference seawater, embryos of clams from the most highly industrialized area (Bridgeport) with higher contaminant levels exhibited more irregularity in chromosome numbers and greater larval abnormality, possible indicators of long-term sublethal effects. Fertilization and early meiotic success at 1 to 1 1/2 h were significantly lower for clams from Norwalk than for those from Greenwich. At 48 h, mortality was lowest for Greenwich larvae and highest for Norwalk larvae in their respective site waters, but the mortality for these two sites was significantly lower than for other sites in reference water. This suggests sporadically poor environmental quality. Milford larvae also had significant mortality. Population-level significance of pollution effects on clam reproduction will depend on how contaminated the environment is over the entire reproductive season of the clams in Long Island Sound, and over how large a portion of the spawning grounds.

  4. Microbiological responses to depuration and transport of native and exotic clams at optimal and stressful temperatures.

    PubMed

    Anacleto, Patrcia; Maulvault, Ana Lusa; Chaguri, Milena; Pedro, Snia; Nunes, Maria Leonor; Rosa, Rui; Marques, Antnio

    2013-12-01

    The microbiological responses of two bivalves species from Tagus estuary, Venerupis pullastra (native clam) and Ruditapes philippinarum (exotic clam) were investigated during 48 h of depuration and subsequent simulated transport in semi-dry conditions at two temperatures (4 and 22 C) until reaching 50% lethal time (LT50). Regardless of temperature and species, the maintenance of clams in water for 48 h (depuration period) did not affect LT50 during transport. R. philippinarum showed higher survival rates than V. pullastra, always reaching LT50 later, especially at 4 C. Significant differences between clams' species were found in almost all microbiological parameters. This can be related with clams' biological activity and habitat environmental conditions since both clams do not coexist in Tagus estuary. Depuration was efficient to reduce the bacterial load, particularly Escherichia coli, but not efficient to remove Vibrio spp. In both species, the growth of Vibrio spp. was inhibited at 4 C, whereas exponential growth occurred at 22 C. Total viable counts significantly increased in most treatments, while E. coli counts significantly decreased to undetected levels, except for non-depurated R. philippinarum simulated transported at 4 C. Thus, this study highlights the importance of clams depuration for at least 24 h in polluted estuarine areas, followed by transport at low temperatures (4 C). PMID:24010618

  5. Great Lakes clams find refuge from zebra mussels in restored, lake-connected marsh (Ohio)

    USGS Publications Warehouse

    Nichols, S. Jerrine; Wilcox, Douglas A.

    2004-01-01

    Since the early 1990s, more than 95 percent of the freshwater clams once found in Lake Erie have died due to the exotic zebara mussel (Dreissena polymorpha). Zebra mussels attach themselves to native clams in large numbers, impeding the ability of the clams to eat and burrow. However, in 1996, we discovered a population of native clams in Metzger Marsh in western Lake Erie (about 50 miles [80 km] east of Toledo) that were thriving despite the longtime presence of zebra mussel in surrounding waters. At that time, Metzger Marsh was undergoing extensive restoration, including construction of a dike to replace the eroded barrier beach and of a water-control structure to maintain hydrologic connections with the lake (Wilcox and Whillans 1999). The restoration plan called for a drawdown of water levels to promote plant growth from the seedbank -- a process that would also destroy most of the clam population. State and federal resource managers recommended removing as many clams as possible to a site that was isolated from zebra mussels, and then returning them to the marsh after it was restored. We removed about 7,000 native clams in 1996 and moved them back to Metzger Marsh in 1999.

  6. Effects of permethrin on biomarkers in Mediterranean clams (Ruditapes decussatus).

    PubMed

    Sellami, B; Khazri, A; Louati, H; Boufahja, F; Dellali, M; Sheehan, D; Aissa, P; Driss, M Ridha; Mahmoudi, E; Beyrem, H

    2014-05-01

    The present study was focused on the assessment of Catalase (CAT) and Acetylcholinesterase (AChE) activities in Mediterranean clams (Ruditapes decussatus) exposed to 50, 100 and 150 μg/L of Permethrin for 5, 10, 15, 20 and 25 days. In water, the measured concentrations of Permethrin in the treated aquariums were respectively 16.66, 38.24 and 55.61 μg/L. Results showed that CAT activity was increased after 5 days of exposure to high concentration reaching maximum value of 10.14 μmol/min/mg proteins after 25 days. However, no significant changes in AChE activity after 5 days of exposure were detected in all treated groups. AChE activity was significantly inhibited after 10 days with 100 and 150 μg/L and still depending on concentration and time. Maximum inhibition of AChE activity was reached after 25 days with the highest concentration of Permethrin. Our data indicated that exposure to Permethrin modifies biomarker profiles inducing oxidative stress and reducing AChE activity in Mediterranean clams. PMID:24519478

  7. An improved image matching algorithm based on SURF and Delaunay TIN

    NASA Astrophysics Data System (ADS)

    Cheng, Yuan-ming; Cheng, Peng-gen; Chen, Xiao-yong; Zheng, Shou-zhu

    2015-12-01

    Image matching is one of the key technologies in the image processing. In order to increase its efficiency and precision, a new method for image matching which based on the improved SURF and Delaunay-TIN is proposed in this paper. Based on the original SURF algorithm, three constraint conditions, color invariant model, Delaunay-TIN, triangle similarity function and photography invariant are added into the original SURF model. With the proposed algorithm, the image color information is effectively retained and the erroneous matching rate of features is largely reduced. The experimental results shows that this proposed method has the characteristics of higher matching speed, uniform distribution of feature points to be matched, and higher correct matching rate than the original algorithm does.

  8. Surfing in tortoises? Empirical signs of genetic structuring owing to range expansion

    PubMed Central

    Graci, Eva; Botella, Francisco; Anadn, Jos Daniel; Edelaar, Pim; Harris, D. James; Gimnez, Andrs

    2013-01-01

    Much of our current knowledge about the genetic dynamics in range expansions originates from models, simulations and microcosm experiments that need to be corroborated by field data. Here, we report a neutral genetic pattern that matches the predictions of the genetic surfing theory. Genetic surfing occurs when repeated founding events and genetic drift act on the wave of advance of an expanding population, promoting strong spatial structure. In the range expansion of the tortoise Testudo graeca from North Africa to southeastern Spain, we found several genetic signatures consistent with surfing: a decrease of genetic diversity with distance from the initial founder area, clinal patterns in allele frequencies, rare African alleles which have become common at distal sites in the Spanish range, and stronger spatial differentiation in the expanded range than in the original one. Our results provide support for the theory that genetic drift can be an important force in shaping the genetic structure of expanding populations. PMID:23554278

  9. Distribution and winter survival health of Asian clams, Corbicula fluminea, in the St. Clair River, Michigan

    USGS Publications Warehouse

    French, John R. P., III; Schloesser, Don W.

    1996-01-01

    We studied the distribution and winter survival of the Asian clam, Corbicula fluminea, in the St. Clair River from the fall of 1988 to the spring of 1990. Between fall of 1988 and spring of 1989, distribution of Corbicula was extended from 5.5 to 11.5 km downstream from an electric power plant. However, total abundance of clams decreased during the winter. By fall of 1989, Corbicula was found 14.5 km from the power plant, and the mean density of clams was 27 individuals/m2. Between fall of 1989 and spring of 1990, distribution was reduced to 7.5 km from the power plant and abundance decreased 97%. During the winter of 1988-1989, we collected clams monthly from one station 2.2 km from the power plant, and we observed that clams survived the harsh winter for two months after the water temperature dropped about 1.5°C below the reported lethal level for Corbicula in midwinter. During the winer of 1989-1990, we held clams at the sediment-water interface in enclosures, and we observed that condition indices (dry body weight; dry shell weight) of clams remained stable (mean = 0.05 ± 0.01) in December and January and then declined significantly (p < 0.05) to 0.04 ± 0.01 in February. All clams perished by late March. The deteriorating physiological state of clams, as indicated by declining condition index, seemingly is a factor in late winter mortalities of Corbicula in the St. Clair River. In contrast to the rapid geographic spread and population increases in the southern United States, Corbicula likely will not spread rapidly throughout the Great Lakes beyond shoreline thermal refugia of heated-water discharge plumes from power plants.

  10. Age, growth, and population structure of the smooth clam Callista chione in the eastern Adriatic Sea

    NASA Astrophysics Data System (ADS)

    Ezgeta-Bali?, Daria; Peharda, Melita; Richardson, Christopher A.; Kuzmani?, Marina; Vrgo?, Nedo; Isajlovi?, Igor

    2011-12-01

    The age, growth, and population structure of the smooth clam Callista chione were determined from samples collected by hydraulic dredge and SCUBA at four locations in the eastern Adriatic during 2007 and 2008. The age of 436 clam shells was determined from internal growth lines present in shell sections, and the timing of growth line formation was ascertained from monthly collections of clams to occur between August and September when sea water temperatures were maximal. In addition, age of 30 older individuals was verified with acetate peels of polished and etched shell sections. Differences were apparent in the age structure and growth rates of clams collected from the four locations studied. Von Bertalanffy growth (VBG) curves obtained for clams from these locations were L t = 72.4 (1-e-0.25(t - 2.68)) (Rab Island), L t = 74.5 (1-e-0.15(t + 0.57)) (Pag Bay), L t = 79.3 (1-e-0.34(t - 0.97)) (Cetina estuary), and L t = 82.5 (1-e-0.11(t + 2.88)) (Katela Bay). The age of the clams ranged between 3 and 44 years; median clam ages were similar at three of the four locations (14, 12, and 12 years, respectively), but was significantly lower in the Cetina estuary (4 years). The VBG growth constants recorded from clams were within the range of values obtained for this species by previous authors. The observed local differences in population structure indicate different levels of exploitation and illustrate the need to establish long-term strategies for a sustainable exploitation of smooth clams in the Croatian Adriatic.

  11. [THE CONTENT OF MERCURY IN SEDIMENTS AND THE CLAMS UNIO PICTORUM FROM THE URAL RIVER].

    PubMed

    Solovykh, G N; Osinkina, V V; Vereshchagin, N N; Belomestnova, V G; Vodyanitskaya, O V; Kamaukhova, I V

    2015-01-01

    There was investigated the mercury total content in bottom sediments and some bodies of clams from the area of the middle reach of the Ural river near the Orenburg city. In bottom sediments there was revealed an excess of the ecological standard for mercury. There was noted the uneven distribution of toxicant in bodies of clams: the maximal contents was detected in hepatopancreas, minimal--in "foot", that apparently is determined by the unequal metabolitic activity of these tissues. The highest concentration of mercury in the tissues of clams was noted at the station "Ural river above the camp" Dubki". PMID:26625617

  12. Non-linear control of the ''clam'' wave energy device. Final report

    SciTech Connect

    Not Available

    1983-09-01

    A promising wave energy device being currently investigated is the ''clam'' device. The clam extracts energy by pumping air through a specially designed (Wells) turbine. Although operation of the Wells turbine does not require a rectified air flow, some additional control will be necessary to optimize the phase of the clam motion for good efficiencies. An examination of the equation of motion in the time domain suggests the possibility of non-linear phase control by mechanical, power take-off, or pneumatic latching. Latching can be shown to increase the efficiency of the device in the longer wavelengths of the wave spectrum, i.e. those of high incident wave power.

  13. The asiatic clam, Corbicula fluminea (Mller), in the tidal Potomac River, Maryland

    USGS Publications Warehouse

    Dresler, Paul V.; Cory, Robert L.

    1980-01-01

    The Asiatic clam,Corbicula fluminea(Mller), has extended its range to include the tidal fresh-water portion of the Potomac River, Maryland. Though patchily distributed, the clams have attained densities of 665 m?2. Size-class distributions indicate that the clams first appeared in 1975. About 90% of the population belong to year-class I and were less than 12 mm in length. Elsewhere, this species has created severe water quality problems; it should be closely watched in the Potomac.

  14. Clams As recorders of ocean ridge volcanism and hydrothermal vent field activity

    PubMed

    Hart; Blusztajn

    1998-05-01

    The clam Calyptogena magnifica lives at abyssal depths in association with hydrothermal venting on midocean ridges. Analysis of strontium/calcium ratios in C. magnifica shells provides a temperature proxy with submonthly time resolution. A 21-year strontium/calcium record of two clams from 9 degrees50'N on the East Pacific Rise captures the known 1991 and 1992 eruptive events, documents several additional events between 1992 and 1996, and demonstrates the absence of major hydrothermal episodes during the period 1974 to 1991. These clam archives can increase our understanding of the thermal and chemical history of midocean ridge hydrothermal and volcanic activity on decadal time scales. PMID:9572728

  15. Registration of cardiac magnetic resonance images using SURF points and matching

    NASA Astrophysics Data System (ADS)

    Moreno, Braian; Atehorta, Anglica; Corredor, Germn.; Romero, Eduardo

    2015-01-01

    Reconstruction of the heartbeat is an useful tool to detect and diagnose some pathologies. However, this process represents a challenge because the heart is a moving organ inside a moving body, so that, either similar regions are hard to identify or some regions appear and disappear constantly. This article presents a reconstruction method of the right ventricle using SURF points in irregular regions. The SURF points, invariant to image scale and rotation, provide robust features of a right ventricle slice that can then be traced to the other slices. By using such points and then, using a nonrigid registration, it possible to perform a volumetrical reconstruction of these images.

  16. SURF: Taking Sustainable Remediation from Concept to Standard Operating Procedure (Invited)

    NASA Astrophysics Data System (ADS)

    Smith, L. M.; Wice, R. B.; Torrens, J.

    2013-12-01

    Over the last decade, many sectors of industrialized society have been rethinking behavior and re-engineering practices to reduce consumption of energy and natural resources. During this time, green and sustainable remediation (GSR) has evolved from conceptual discussions to standard operating procedure for many environmental remediation practitioners. Government agencies and private sector entities have incorporated GSR metrics into their performance criteria and contracting documents. One of the early think tanks for the development of GSR was the Sustainable Remediation Forum (SURF). SURF brings together representatives of government, industry, consultancy, and academia to parse the means and ends of incorporating societal and economic considerations into environmental cleanup projects. Faced with decades-old treatment programs with high energy outputs and no endpoints in sight, a small group of individuals published the institutional knowledge gathered in two years of ad hoc meetings into a 2009 White Paper on sustainable remediation drivers, practices, objectives, and case studies. Since then, SURF has expanded on those introductory topics, publishing its Framework for Integrating Sustainability into Remediation Projects, Guidance for Performing Footprint Analyses and Life-Cycle Assessments for the Remediation Industry, a compendium of metrics, and a call to improve the integration of land remediation and reuse. SURF's research and members have also been instrumental in the development of additional guidance through ASTM International and the Interstate Technology and Regulatory Council. SURF's current efforts focus on water reuse, the international perspective on GSR (continuing the conversations that were the basis of SURF's December 2012 meeting at the National Academy of Sciences in Washington, DC), and ways to capture and evaluate the societal benefits of site remediation. SURF also promotes and supports student chapters at universities across the US, encouraging the incorporation of sustainability concepts into environmental science and engineering in undergraduate curricula and graduate research, and student participation at professional conferences. This presentation will provide an overview of the evolution of GSR to-date and a history of SURF's technical and outreach work. Examples will be provided--using both qualitative and quantitative metrics--that document and support the benefits of GSR.

  17. The search for brown dwarfs

    NASA Technical Reports Server (NTRS)

    Stevenson, David J.

    1991-01-01

    The theory of brown dwarfs is summarized and observational findings regarding brown dwarfs are reviewed. The equation of state, the thermal properties, the interior transport properties, the boundary conditions, and the initial conditions are examined. Indirect observations, IR speckle interferometry, IR photometry, and field observations of brown dwarfs are discussed.

  18. Asteroseismology of White Dwarf Stars

    NASA Technical Reports Server (NTRS)

    Hansen, Carl J.

    1997-01-01

    The primary purpose of this investigation has been to study various aspects of multimode pulsations in variable white dwarfs. In particular, nonlinear interactions among pulsation modes in white dwarfs (and, to some extent, in other variable stars), analysis of recent observations where such interactions are important, and preliminary work on the effects of crystallization in cool white dwarfs are reported.

  19. Pressure Gradients in the Inner Surf and Outer Swash Zone

    NASA Astrophysics Data System (ADS)

    Kidwell, A.; Puleo, J. A.; Torres-Freyermuth, A.

    2010-12-01

    The swash zone is a highly dynamic region of the beach profile. Although there has been significant progression in understanding the complex hydrodynamics of the swash zone, an improvement in the understanding of the sediment transport mechanisms deserves further investigation. Prior studies have demonstrated that the existing formulations derived from the energetics-type formulation do not accurately and consistently predict sediment transport. Thus, measurements and numerical modeling can contribute in the improvement of the current predictive capability of sediment transport. A potential enhancement to nearshore sediment transport is the horizontal pressure gradient. However, measuring the dynamic pressure gradient in nearshore flows is a difficult task. For instance, standard pressure sensors are generally ill-suited for this type of measurement in shallow swash flows due to the obstructing size of the sensor and the potential for flow interference. With improved measurement apparati and techniques, it is possible to obtain measurements of the horizontal pressure gradient. Our current research includes laboratory and numerical model investigation of the horizontal pressure gradient in the inner surf and outer swash zone. An inexpensive differential pressure gauge is employed allowing for a pressure port on the order of 2 mm diameter. Four pressure sensor pairs are installed 1 cm above the bed with a cross-shore spacing of 8 cm. The sensors are deployed just outside of and at various locations within the outer swash zone to determine spatio-temporal pressure variations. The measurement of total pressure coupled with the corresponding free surface measurements from co-located capacitance wave gauges yields time series of the hydrostatic and dynamic pressure and pressure gradients. A VOF-type RANS model is employed in this investigation. Firstly, the numerical model is validated with swash measurements. Then, model simulations will be performed in order to complement the measured data. Initial investigations (lab and model) focus on the pressure gradients under solitary-wave-forced swash flows on a 1:12 sloping beach and will be extended to include the pressure gradient on a barred beach and for irregular waves.

  20. Fatty acid composition, sarcoplasmic reticular lipid oxidation, and immunity of hard clam (Meretrix lusoria) fed different dietary microalgae.

    PubMed

    Chen, Shu-Mei; Tseng, Kai-Yi; Huang, Chen-Huei

    2015-07-01

    Fatty acid profiles, activities of biomembrane lipid peroxidation, and immunity of a seawater clam (Meretrix lusoria) fed three species of dietary microalgae were investigated. Clams of a marketable size (25 g mean weight) were fed Tetraselmis chui, Chaetoceros muelleri, or Isochrysis galbana for 8 weeks. Fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in the polar lipid fractions of clams reflected those of the dietary algae species. Clams fed with T. chui and C. muelleri contained higher proportion of non-methylene interrupted (NMI) fatty acids than those fed I. galbana. Proportion of DHA in lipids of the clams fed with I. galbana was the highest among test groups. The NADH-dependent sarcoplasmic reticular lipid peroxidation activity of clams fed I. galbana was significantly greater (p < 0.05) than that of clams fed T. chui or C. muelleri. The hemocyte adhesion capacity of clams fed C. muelleri or I. galbana was significantly higher (p < 0.05) than that of clams fed T. chui. No significant differences (p ≥ 0.05) in total hemocyte count, phenoloxidase activity, clearance efficiency hemocyte and phagocytosis were detected among clams fed different microalgae. PMID:25707599

  1. White Dwarf Stars (With 37 figures)

    NASA Astrophysics Data System (ADS)

    Kawaler, Steven D.

    Introduction White Dwarfs as Useful Stars Origins: the Clue of White Dwarf Masses The Main Channel Why Such a Narrow Mass Distribution? Observed Properties of White Dwarfs Discovery of White Dwarfs Finding White Dwarfs White Dwarf Colors and the White Dwarf Luminosity Function White Dwarf Optical Spectra Distribution of Spectral Types with Effective Temperatures Magnetic White Dwarfs Pulsating White Dwarfs Physics of White Dwarf Interiors Equation of State Heat Transport in Degenerate Matter Nonideal Effects Specific Heat White Dwarf Formation and Early Cooling Thermal Pulses on the AGB Departure from the AGB The PNN Phase Nuclear Shutdown and Neutrino Cooling Chemical Evolution of White Dwarfs Diffusive Processes Accretion of "Fresh" ISM vs. Mass Loss Convection Chemical Evolution Scenarios White Dwarf Cooling and the White Dwarf Luminosity Function A Simplified Cooling Model Complications: Neutrinos and Crystallization Realistic Cooling Calculations Construction of Theoretical Luminosity Functions The Age of the Galactic Disk Nonradial Oscillations of White Dwarfs: Theory Review of Observations Hydrodynamic Equations Local Analysis and the Dispersion Relation g-mode Period Spacings Mode Trapping Rotational and Magnetic Splitting The Seismological Toolbox Pulsating White Dwarfs The Whole Earth Telescope PG 1159 Stars and Pulsating PNNs GD 358: A Pulsating DB White Dwarf The ZZ Ceti Stars Astrophysical Applications of White Dwarfs Stellar Evolution as a Spectator Sport The White Dwarf Luminosity Function and Our Galaxy White Dwarfs and Cluster Ages The Planetary Nebula Luminosity Function and Galaxy Distances Driving and Damping of Pulsations and Convective Efficiency in - White Dwarfs Ceti Stars Final Thoughts References

  2. Ultracool Companions to White Dwarfs

    NASA Astrophysics Data System (ADS)

    Steele, P. R.; Burleigh, M. R.; Barstow, M. A.; Jameson, R. F.; Dobbie, P. D.

    2010-11-01

    We present the latest results in a near-infrared photometric search for unresolved ultra-cool companions and debris disks to white dwarfs in UKIDSS. Twenty five DA white dwarfs were identified as having multiple excesses indicative of a low mass companion, with 8-10 of these having a predicted mass in the range associated with brown dwarfs. The results of this survey show that the unresolved (<2'') brown dwarf companion fraction to DA white dwarfs is 0.3<=fWD+BD<=1.3%.

  3. Origins, Evolution, and Fate of Brown Dwarfs

    NASA Technical Reports Server (NTRS)

    Martin, Eduardo

    2003-01-01

    Research related to the origins, evolution and fate of brown dwarfs is presented. The topics include: 1) Imaging surveys for brown dwarfs; 2) Companion detection techniques; 3) Measurements of fundamental properties of brown dwarfs; 4) Classification schemes for ultracool dwarfs; 5) Origins and evolution of brown dwarfs; 6) Ultracool atmospheres and interiors; 7) Time variable phenomena in brown dwarfs; 8) Comparisons between brown dwarfs and planets; 9) Substellar mass functions; and 10) Future facilities.

  4. Copper and silver accumulation in transplanted and resident clams (Macoma balthica) in South San Francisco Bay

    USGS Publications Warehouse

    Cain, D.J.; Luoma, S.N.

    1985-01-01

    Accumulation of Cu and Ag by soft tissues of the deposit-feeding clam Macoma balthica was less than half in clams transplanted to a contaminated area than in clams native to that area. During a period of tissue growth, the transplants retained 50% and 90%, respectively, of the net Cu and Ag accumulated, but loss of metals from soft tissue by the resident population equalled net accumulation. Copper accumulation in the transplants did not occur during some periods when increases in the metal body burden of the resident population indicated that environmental exposures were high. The difference in metal accumulation of the two groups of clams may be the result of past environmental exposures. The results illustrate some limitations of using transplants as indicators of pollution events or of pollutant impact upon resident populations.

  5. A theoretical individual-based model of Brown Ring Disease in Manila clams, Venerupis philippinarum

    NASA Astrophysics Data System (ADS)

    Paillard, Christine; Jean, Fred; Ford, Susan E.; Powell, Eric N.; Klinck, John M.; Hofmann, Eileen E.; Flye-Sainte-Marie, Jonathan

    2014-08-01

    An individual-based mathematical model was developed to investigate the biological and environmental interactions that influence the prevalence and intensity of Brown Ring Disease (BRD), a disease, caused by the bacterial pathogen, Vibrio tapetis, in the Manila clam (Venerupis (= Tapes, = Ruditapes) philippinarum). V. tapetis acts as an external microparasite, adhering at the surface of the mantle edge and its secretion, the periostracal lamina, causing the symptomatic brown deposit. Brown Ring Disease is atypical in that it leaves a shell scar that provides a unique tool for diagnosis of either live or dead clams. The model was formulated using laboratory and field measurements of BRD development in Manila clams, physiological responses of the clam to the pathogen, and the physiology of V. tapetis, as well as theoretical understanding of bacterial disease progression in marine shellfish. The simulation results obtained for an individual Manila clam were expanded to cohorts and populations using a probability distribution that prescribed a range of variability for parameters in a three dimensional framework; assimilation rate, clam hemocyte activity rate (the number of bacteria ingested per hemocyte per day), and clam calcification rate (a measure of the ability to recover by covering over the symptomatic brown ring deposit), which sensitivity studies indicated to be processes important in determining BRD prevalence and intensity. This approach allows concurrent simulation of individuals with a variety of different physiological capabilities (phenotypes) and hence by implication differing genotypic composition. Different combinations of the three variables provide robust estimates for the fate of individuals with particular characteristics in a population that consists of mixtures of all possible combinations. The BRD model was implemented using environmental observations from sites in Brittany, France, where Manila clams routinely exhibit BRD signs. The simulated annual cycle of BRD prevalence and intensity agrees with observed disease cycles in cultured clam populations from this region, with maximum disease prevalence and intensity occurring from December to April. Sensitivity analyses of modeled physiological processes showed that the level of hemocyte activity is the primary intrinsic determinant of recovery of infected clams. Simulations designed to investigate environmental effects on BRD suggested that the outcome of the host-parasite interaction is dependent on food supply (high values being favorable for the host) and temperature. Results of simulations illustrate the complex interaction of temperature effects on propagation and viability of the bacterium, on the phagocytic activity of the hemocytes, and on other physiological processes of the host clam. Simulations using 1 °C and 2 °C increases in temperature generally favored disease development, indicating that climate warming might favor the spread of BRD.

  6. Identification of leukemia cell surface proteins in clams

    SciTech Connect

    Reinisch, C.L.; Smolowitz, R.; Miosky, D. Marine Biological Lab., Woods Hole, MA )

    1988-09-01

    Soft-shell clams, Mya arenaria, develop leukemias which, in the advanced stages of disease, kill the host. The authors laboratory has developed an extensive panel of murine monoclonal antibodies to leukemia cells of Mya, and has used these powerful reagents to diagnose the disease with extreme accuracy. They have now ascertained that one membrane-associated protein of approximately 200kD is immunodominant. The function of this protein, regulation of its production and potential site of synthesis are being evaluated. Monoclonal antibodies have also permitted the exploration of the mechanism of leukemogensis. They have evaluated the specific staining pattern of one monoclonal antibody, and have concluded that at least one ontogenic source of leukemic cells may be connective tissue cells lining the sinusoids. Whether or not exposure to severely polluted sites such as New Bedford Harbor stimulates the export of immature hemocytes which then become transformed is at least one possibility amenable to testing using the monoclonal reagents.

  7. Reproducibility of the Most Probable Numbers Technique for Determining the Sanitary Quality of Clams1

    PubMed Central

    Lear, Donald W.

    1962-01-01

    The reproducibility of most probable numbers results in the bacteriological examination of clam meats, using the tentatively recommended procedure, is less than has been indicated in use with water analysis. Entrapped air bubbles in ground clam meats contribute to the variability of results by (i) lowering the density of the sample material, producing inaccurate aliquots for inocula, and (ii) interfering with the attainment of homogeneity in the brei. PMID:14463247

  8. Ozone depuration of Vibrio vulnificus from the southern quahog clam, Mercenaria campechiensis

    SciTech Connect

    Schneider, K.R.; Steslow, F.S.; Sierra, F.S.; Rodrick, G.E.; Noss, C.I. )

    1991-03-01

    Southern quahog clams, Mercenaria campechiensis, were dosed with Vibrio vulnificus and placed in a pilot-scale depuration system using ozonated recirculated artificial seawater. Twenty-four hours of treatment with ozone-treated recirculating artificial seawater reduced the numbers of V. vulnificus in the shellfish meats by an average of 2 log units when compared to natural die-off in control clams. The oxidant levels (up to 3 mg/liter) did not adversely affect shellfish pumping during the depuration process.

  9. Sediment-contact and survival of fingernail clams: Implications for conducting short-term laboratory tests

    USGS Publications Warehouse

    Naimo, T.J.; Cope, W.G.; Bartsch, M.R.

    2000-01-01

    Porewater toxicity tests have been used as indicators of whole sediment toxicity. However, many species commonly tested in porewater predominately reside in the water column and otherwise have little to no direct contact with sediment and associated porewater. We assessed the feasibility of porewater toxicity tests with fingernail clams Musculium transversum, a benthic macroinvertebrate that inhabits soft bottom sediments and feeds by filtering surface and porewater. Fingernail clams were exposed to water or sediment in a 96 h laboratory test with a 5 x 2 factorial experimental design. The five treatments included sediments from four sites in the Mississippi River and one sediment-free control (well water). In all treatments, clams were exposed to the sediments or water either directly (no enclosure) or indirectly (enclosure, suspended above the sediment surface). There were three replicates for each of the ten treatment combinations. Overall, survival of fingernail clams did not vary among the five treatments (p = 0.36). In treatments without enclosures, survival of clams in the sediment-free control was not significantly different (p = 0.34) from the sediment-containing treatments. Survival of clams in the sediment-free control averaged 85 - suggesting that direct sediment contact is not necessary for survival in short-term tests. In contrast, survival of clams in the sediment-containing treatments differed significantly (p = 0.03) between exposures with (mean, 77) and without (mean, 89) enclosures. Thus, fingernail clams may provide an alternative species for evaluating benthic macroinvertebrates in short-term laboratory porewater tests. However, more information on their physiological requirements and the development of sublethal endpoints is recommended before their use in tests of longer duration. (C) 2000 by John Wiley and Sons, Inc.

  10. Barley Yellow Dwarf

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Barley yellow dwarf is the most economically important virus disease affecting most cereal crops world wide. This manuscript summarizes the current knowledge of the disease etiology, epidemiology and management. This information is incorporated into the latest revision of the American Phytopathologi...

  11. Barley Yellow Dwarf Virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Barley yellow dwarf (BYD) is the most widespread and economically important virus disease of cereals. The viruses causing BYD were initially grouped based on common biological properties, including persistent and often strain-specific transmission by aphids and induction of yellowing symptoms. The...

  12. Dwarf Eye Disorder

    ERIC Educational Resources Information Center

    Science Teacher, 2005

    2005-01-01

    Johns Hopkins researchers at the Wilmer Eye Institute have discovered what appears to be the first human gene mutation that causes extreme farsightedness. The researchers report that nanophthalmos, Greek for "dwarf eye," is a rare, potentially blinding disorder caused by an alteration in a gene called MFRP that helps control eye growth and

  13. Sagittarius Dwarf Galaxy

    NASA Astrophysics Data System (ADS)

    Ibata, R.; Murdin, P.

    2000-11-01

    The Sagittarius DWARF GALAXY is the closest member of the Milky Way's entourage of satellite galaxies. Discovered by chance in 1994, its presence had previously been overlooked because it is largely hidden by the most crowded regions of our own Galaxy with which it is merging....

  14. Validation of accuracy and repeatability of UltraSurf metrology on common optical shapes

    NASA Astrophysics Data System (ADS)

    DeFisher, Scott; Matthews, Greg; Fess, Edward

    2015-10-01

    Advancements in optical manufacturing technology allow optical designers to implement steep aspheric or high departure surfaces into their systems. Accurate metrology during the grinding and polishing stages of asphere manufacturing will reduce time and cost. Measuring these surfaces with common interferometers or profilometers can be difficult due to large surface slopes or unpolished surface texture. OptiPro has developed UltraSurf to qualify the form, figure, and thickness of steep aspheric and freeform optics. UltraSurf is a computer controlled, non-contact coordinate measuring machine. It incorporates five air-bearing axes, linear motors, high-resolution feedback, and a non-contact probe. The measuring probe is scanned over the optical surface while maintaining perpendicularity and a constant focal offset. There are multiple probe technologies available on UltraSurf, and each probe has strengths and weaknesses relative to the material properties, surface finish, and figure error of an optical component. Validation of the system accuracy, repeatability, and methodology must be performed to trust the measurement data. Form and figure maps of a flat, a sphere, and an asphere using UltraSurf will be presented with comparisons to interferometry. In addition, accuracy, repeatability, and machine qualification will be discussed.

  15. "Making Waves" with Burke: Surf Nazi Culture and the Rhetoric of Localism.

    ERIC Educational Resources Information Center

    Scheibel, Dean

    1995-01-01

    Describes the historical, cultural, and mythic contexts that infuse the territorial exclusionary practices of surfers. Analyzes surfers' rhetorical responses in letters published in surfing magazines, describing how rhetors use economic and religious metaphors to position ideologies that both reproduce and mediate cultural myths of perfection

  16. Infragravity-wave modulation of short-wave celerity in the surf zone

    NASA Astrophysics Data System (ADS)

    Tissier, M.; Bonneton, P.; Michallet, H.; Ruessink, B. G.

    2015-10-01

    The cross-shore evolution of individual wave celerity is investigated using two high-resolution laboratory experiments on bichromatic waves. Individual waves are tracked during their onshore propagation and their characteristics, including celerity, are estimated. The intrawave variability in celerity is low in the shoaling zone but increases strongly after breaking. It is maximum when the infragravity-wave height to water depth ratio is the largest, that is to say close to the shoreline. There the observed range of individual wave celerity can be as large as the mean celerity value. This variability can be largely explained by the variations in water depth and velocity induced by the infragravity waves. The differences in celerity are such that they lead to the merging of the waves in the inner surf zone for most of the wave conditions considered. Again, the location at which the first waves start merging strongly correlates with the infragravity-wave height to water depth ratio. The consequences of these findings for celerity-based depth-inversion techniques are finally discussed. Surprisingly, accounting for the infragravity-wave modulation of the velocity field in the celerity estimate does not significantly improve depth estimation in the surf zone. However, it is shown that the occurrence of bore merging decreases significantly the coherence of the wavefield in the surf zone. This loss of coherence could hamper celerity estimation from pixel intensity time series and explain, at least partly, the relatively poor performance of depth-inversion techniques in the inner surf zone.

  17. Access Without Authentication: How and Why We Let Anyone Surf Our Wireless

    ERIC Educational Resources Information Center

    Watkins, Donna

    2006-01-01

    Wireless hotspots are popping up in local coffee shops everywhere. Anyone with a wireless-ready laptop or PDA can surf the Internet at one of these hotspots. The same is now true for all 32 branches of the Orange County Public Library (OCPL) in California. Though many public library systems are moving toward wireless access, most require patrons…

  18. Access Without Authentication: How and Why We Let Anyone Surf Our Wireless

    ERIC Educational Resources Information Center

    Watkins, Donna

    2006-01-01

    Wireless hotspots are popping up in local coffee shops everywhere. Anyone with a wireless-ready laptop or PDA can surf the Internet at one of these hotspots. The same is now true for all 32 branches of the Orange County Public Library (OCPL) in California. Though many public library systems are moving toward wireless access, most require patrons

  19. The Web Surfer: What (Literacy) Skills Does It Take to Surf Anyway?

    ERIC Educational Resources Information Center

    Blackburn, Jessie

    2010-01-01

    This article looks closely at some of the lingering stereotypes that Composition Studies holds toward Web surfing and queries the resulting literacy hierarchy against our students' reading and writing practices that take place online. This article claims that while good progress has been made in the way of revising twenty-first century definitions…

  20. The Ocean as a Unique Therapeutic Environment: Developing a Surfing Program

    ERIC Educational Resources Information Center

    Clapham, Emily D.; Armitano, Cortney N.; Lamont, Linda S.; Audette, Jennifer G.

    2014-01-01

    Educational aquatic programming offers necessary physical activity opportunities to children with disabilities and the benefits of aquatic activities are more pronounced for children with disabilities than for their able-bodied peers. Similar benefits could potentially be derived from surfing in the ocean. This article describes an adapted surfing…

  1. Lipid characteristics of a seep clam, Mesolinga soliditesta: Comparison with those of two coastal clams, Meretrix lamarckii and Ruditapes philippinarum

    NASA Astrophysics Data System (ADS)

    Saito, Hiroaki; Murata, Masakazu; Hashimoto, Jun

    2014-12-01

    The lipids and fatty acids of two coastal clams, Meretrix lamarckii and Ruditapes philippinarum, collected at 5 and 1 m of depth, and a seep clam, Mesolinga soliditesta, collected at 331 m of depth, were examined to assess their lipid physiology and trophic relationship with their diets. The major fatty acids of lipids in Mer. lamarckii and R. philippinarum were 14:0, 16:0, 18:0, 16:1n-7, 18:1n-9, 18:1n-7, 20:4n-6, 20:5n-3, and 22:6n-3, while those of Mes. soliditesta were 16:0, 18:0, 16:1n-7, 18:1n-7, 20:1n-7, 20:1n-13, 20:2n-7, 15 (Δ5,13-20:2), and 22:2n-7,15 (Δ7,15-22:2). The major polyunsaturated fatty acids (PUFAs) in the Mer. lamarckii and R. philippinarum lipids consisted of various n-3 and n-6 long-chain (LC) PUFAs, such as 20:4n-6, 22:4n-6, 20:5n-3, 22:5n-3, and 22:6n-3, while those in Mes. soliditesta muscle and viscera included various n-4 family PUFAs (18:3n-7, 18:4n-4, 20:2n-7, and 20:3n-7) with limited kinds of n-3 and n-6 PUFAs (20:4n-6 and 20:5n-3). These findings indicate that, like other common shallow-water clams, Mer. lamarckii and R. philippinarum ingest phytoplanktonic n-3 and n-6 LC-PUFAs, whereas Mes. soliditesta utilizes limited kinds of n-3 and n-6 LC-PUFAs. In contrast to the other two bivalves species, Mes. soliditesta yielded various n-4 and n-7 (n-4/n-7) PUFAs, which were assimilated from the chemosynthetic symbionts. The high diversity of PUFAs contained in the Mes. soliditesta lipids (n-3, n-4 family, and n-6 PUFAs) suggests that this species mixotrophically utilized both photosynthetic products and vent chemosynthetic nutrition derived from geothermal energy.

  2. Proto-brown dwarfs

    NASA Astrophysics Data System (ADS)

    Pound, Marc William

    1994-01-01

    We develop a new technique to find the progenitors of brown dwarfs, or 'proto-brown dwarfs,' in nearby molecular clouds. By using mm-wave telescopes, this method can achieve greater mass sensitivity than traditional approaches such as astrometry and infrared imaging. Our method can distinguish between various forms of the low-mass (less than 0.2 solar mass) stellar initial mass function (IMF), which currently is not well-constrained. We present results of a search for proto-brown dwarfs in two types of molecular cloud - those at high galactic latitudes, and those in the disk which are forming stars. The high latitude clouds (HLC's) have relatively low densities, and are apparently not forming stars. Our analysis of several HLC's gives little evidence for self-gravitating objects of any mass, although there are clumps with masses as low as 3 M(Jupiter). In molecular line and continuum searches in the Ophiuchus B and Barnard 18 star-forming regions, we find no clear-cut evidence of any proto-brown dwarfs. This lack of proto-brown dwarfs is surprising; even if the IMF slope were flat, we would expect to have found approx. 10 objects. We do find a few candidate objects near our detection limit (approx. 0.02 solar mass) which deserve further scrutiny. We find fewer low-mass clumps (approx. less than O.l solar mass) than expected from extrapolation of any reasonable mass function. If the IMF follows the clump mass spectrum below 0.08 solar mass, as it seems to at higher masses, our results imply that, unless some undetermined process causes the production of many more low-mass clumps, the IMF is falling at masses below 0.08 solar mass, even if all our candidate objects turn out to be true proto-brown dwarfs. We therefore predict that future searches for brown dwarfs will find very few, regardless of the depth of the searches. We present analyses of two HLC's, MBM 12 and MBM 41-44. The properties of 400 clumps - position, size, mass, line width, brightness temperature - are measured. We find the clump mass spectrum in MBM 12 deviates below 0.3 solar mass from the 'universal' GMC mass spectrum N(Mf) approx. M-0 5. This is the first molecular cloud known which has a mass spectrum which differs significantly and unambiguously from the GMC spectrum.

  3. White Dwarf Stars

    NASA Astrophysics Data System (ADS)

    Kepler, S. O.

    2014-10-01

    White dwarfs are the evolutionary endpoint for nearly 95% of all stars born in our Galaxy, the final stages of evolution of all low- and intermediate mass stars, i.e., main sequence stars with masses below (8.5± 1.5) M_{odot}, depending on metallicity of the progenitor, mass loss and core overshoot. Massive white dwarfs are intrinsically rare objects, tand produce a gap in the determination of the initial vs. final mass relation at the high mass end (e.g. Weidemann 2000 A&A, 363, 647; Kalirai et al. 2008, ApJ, 676, 594; Williams, Bolte & Koester 2009, ApJ, 693, 355). Main sequences stars with higher masses will explode as SNII (Smartt S. 2009 ARA&A, 47, 63), but the limit does depend on the metallicity of the progenitor. Massive white dwarfs are probably SNIa progenitors through accretion or merger. They are rare, being the final product of massive stars (less common) and have smaller radius (less luminous). Kepler et al. 2007 (MNRAS, 375, 1315), Kleinman et al. 2013 (ApJS, 204, 5) estimate only 1-2% white dwarfs have masses above 1 M_{odot}. The final stages of evolution after helium burning are a race between core growth and loss of the H-rich envelope in a stellar wind. When the burning shell is exposed, the star rapidly cools and burning ceases, leaving a white dwarf. As they cool down, the magnetic field freezes in, ranging from a few kilogauss to a gigagauss. Peculiar type Ia SN 2006gz, SN 2007if, SN 2009dc, SN 2003fg suggest progenitors in the range 2.4-2.8 M_{odot}, and Das U. & Mukhopadhyay B. (2012, Phys. Rev. D, 86, 042001) estimate that the Chandrasekhar limit increases to 2.3-2.6 M_{odot} for extremely high magnetic field stars, but differential rotation induced by accretion could also increase it, according to Hachisu I. et al. 2012 (ApJ, 744, 69). García-Berro et al. 2012, ApJ, 749, 25, for example, proposes double degenerate mergers are the progenitors of high-field magnetic white dwarfs. We propose magnetic fields enhance the line broadening in WDs, causing an overestimated surface gravity, and ultimately determine if these magnetic fields are likely developed through the star's own surface convection zone, or inherited from massive Ap/Bp progenitors. We discovered around 20 000 spectroscopic white dwarfs with the Sloan Digital Sky Survey (SDSS), with a corresponding increase in relatively rare varieties of white dwarfs, including the massive ones (Kleinman et al. 2013, ApJS, 204, 5, Kepler et al. 2013, MNRAS, 439, 2934). The mass distributions of the hydrogen-rich (DA) measured from fitting the spectra with model atmospheres calculated using unidimensinal mixing lenght-theory (MLT) shows the average mass (as measured by the surface gravity) increases apparently below 13 000K for DAs (e.g. Bergeron et al. 1991, ApJ, 367, 253; Tremblay et al. 2011, ApJ, 730, 128; Kleinman et al. 2013). Only with the tridimensional (3D) convection calculations of Tremblay et al. 2011 (A&A, 531, L19) and 2013 (A&A, 552, 13; A&A, 557, 7; arXiv 1309.0886) the problem has finally been solved, but the effects of magnetic fields are not included yet in the mass determinations. Pulsating white dwarf stars are used to measure their interior and envelope properties through seismology, and together with the luminosity function of white dwarf stars in clusters and around the Sun are valuable tools for the study of high density physics, and the history of stellar formation.

  4. Soft shell clams Mya arenaria with disseminated neoplasia demonstrate reverse transcriptase activity

    USGS Publications Warehouse

    House, M.L.; Kim, C.H.; Reno, P.W.

    1998-01-01

    Disseminated neoplasia (DN), a proliferative cell disorder of the circulatory system of bivalves, was first reported in oysters in 1969. Since that time, the disease has been determined to be transmissible through water-borne exposure, but the etiological agent has not been unequivocally identified. In order to determine if a viral agent, possibly a retrovirus, could be the causative agent of DN, transmission experiments were performed, using both a cell-free filtrate and a sucrose gradient-purified preparation of a cell-free filtrate of DN positive materials. Additionally, a PCR-enhanced reverse transcriptase assay was used to determine if reverse transcriptase was present in tissues or hemolymph from DN positive soft shell clams Mya arenaria. DN was transmitted to healthy clams by injection with whole DN cells, but not with cell-free flitrates prepared from either tissues from DN positive clams, or DN cells. The cell-free preparations from DN-positive tissues and hemolymph having high levels of DN cells in circulation exhibited positive reactions in the PCR-enhanced reverse transcriptase assay. Cell-free preparations of hemolymph from clams having low levels of DN (<0.1% of cells abnormal), hemocytes from normal soft shell clams, and normal soft shell clam tissues did not produce a positive reaction in the PCR enhanced reverse transcriptase assay.

  5. US Food and Drug Administration survey of cadmium, lead and other elements in clams and oysters.

    PubMed

    Capar, S G; Yess, N J

    1996-07-01

    In Fiscal Years 1985/1986, the US Food and Drug Administration conducted a survey of cadmium, lead and other elements in fresh clams and oysters collected from US coastal areas in use for shellfish production. Shellfish were analysed for cadmium and lead by using a dry ash-anodic stripping voltammetric method. Other elements (aluminium, arsenic, beryllium, calcium, chromium, cobalt, copper, iron, magnesium, manganese, molybdenum, nickel, phosphorus, potassium, selenium, sodium, strontium, vanadium and zinc) were determined by using inductively coupled plasma-atomic emission spectrometry, direct current plasma-atomic emission spectrometry or hydride generation atomic absorption spectrometry. A total of 75 hardshell clam, 59 softshell clam, 104 Eastern oyster and 40 Pacific oyster samples were analysed for cadmium and lead. Average levels found were 0.09, 0.05, 0.51 and 1.1 mg/kg wet weight for cadmium and 0.24, 0.30, 0.11 and 0.06 mg/kg wet weight for lead in hardshell clams, softshell clams, Eastern oysters and Pacific oysters, respectively. The other 19 elements were determined in 10-104 samples of the four types of shellfish. These data provide baseline values for elements in clams and oysters harvested from US coastal waters. PMID:8799717

  6. Occurrence of domoic acid in Washington state razor clams (Siliqua patula) during 1991-1993.

    PubMed

    Wekell, J C; Gauglitz, E J; Barnett, H J; Hatfield, C L; Simons, D; Ayres, D

    1994-01-01

    The presence of domoic acid in aquatic species was reported for the first time in the United States in the late summer of 1991 in Monterey Bay, California. By October of 1991, domoic acid was found in razor clams (Siliqua patula) and in the viscera of Dungeness crab (Cancer magister) along the coasts of Washington and Oregon. In response to this outbreak, the National Marine Fisheries Service, in cooperation with the Washington State Department of Fisheries began analysis of Washington State razor clams for the period from November 1991 to June 1993. This survey indicated that domoic acid levels in the edible portion of the razor clams peaked in December of 1991 (average of all Washington state coastal sites: 106 ppm) and followed a slow decline to the present day low levels (< 5 ppm). Sixteen months after the maximum level, domoic acid has not completely disappeared from the razor clams from the Washington State beaches. Unlike mussels (Mytilus edulis), where the toxin is found only in the viscera, domoic acid distributes itself throughout the various body parts of the razor clam. The highest concentration occurs in the foot or "digger" and the lowest in the siphon or "neck." The concentration of domoic acid in the razor clam foot reached a high of 230 ppm. PMID:7952944

  7. Evaluating sublethal indicators of stress in Asiatic clams (Corbicula fluminea) caged in an urban stream

    SciTech Connect

    Black, M.C.; Belin, J.I.

    1998-12-31

    Freshwater bivalves have been used extensively to monitor chemical accumulation in field exposures, although little information is available on the use of biomarker measurements in field exposures with bivalves. DNA strand breakage, growth rate, condition index and percentage tissue water were measured in freshwater Asiatic clams (Corbicula fluminea) exposed in-situ in a stream that receives urban and industrial stormwater runoff and in a non-impacted reference stream. After 4 weeks exposure, DNA strand lengths in foot tissue from Trail Creek-exposed clams were significantly shorter than DNA from reference clams. These results suggest a reduction in DNA integrity in Trail Creek-exposed clams, possibly indicating exposure to genotoxic chemicals. No significant differences were observed in the growth rates of clams. However, a significant inverse relationship was detected between condition index and % tissue water for all clams. Furthermore, site-specific differences in percentage tissue water and condition indices were observed after 2 and 10 weeks exposure. For this study DNA strand breakage, condition indices, and tissue hydration appear to be more sensitive indicators of sublethal toxicity than growth.

  8. Spatial distribution and bioaccumulation patterns in three clam populations from a low contaminated ecosystem

    NASA Astrophysics Data System (ADS)

    Velez, Cátia; Figueira, Etelvina; Soares, Amadeu; Freitas, Rosa

    2015-03-01

    When consuming bivalves, special concern should be taken to the total element burden. In order to assess this issue the present study aimed to measure the element levels in the sediments of different harvesting areas and relate them with clam accumulation; to assess the elements body burden, their availability for trophic transfer and relate it with total accumulation in clams, comparing the native (Ruditapes decussatus and Venerupis corrugata) and the invasive (Ruditapes philippinarum) species; to evaluate the human risk associated with the consumption of different clam species. The results showed that the element burden in clams does not reflect the sediment contamination and BAF values were higher in the less contaminated areas. Comparison of Maximum Levels (MLs) from international organizations with the concentration of elements in clams showed that As exceeded standard levels. The ingestion of less than 1 Kg per week of clams would result in exceeding the PTWI threshold for As. Furthermore, the results showed that, when comparing to other elements, As and Hg are more easily available to be transferred trophically.

  9. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (south Atlantic): Hard clam. [Mercenaria mercenaria

    SciTech Connect

    Eversole, A.G.

    1987-08-01

    The hard clam, Mercenaria mercenaria, supports an important commercial fishery in the South Atlantic, averaging about 1 million kg of meats annually from 1979 to 1983. It also is an important constituent of estuarine systems throughout the region. Spawning occurs in the spring and the fall at 16 to 30/sup 0/C. Planktonic eggs and larvae are carried by water currents, and larvae set sometime after 6 days of age. Mortality is highest in egg and larval stages, the most sensitive part of the life cycle. Spat display gregarious setting behavior and appear to select sand over finer substrates. Highest densities of clams occur in sandy bottoms with shell. Crab predation is an important factor influencing the density and distribution of clams. Blue crabs and mud crabs appear to be the most important predators. Hard clams are infested by few parasites. Adult clams feed by filtering suspended particulate matter from the water. Growth of clams decreases with size and age. Growth occurs year-round with peaks in spring and fall. Growth of adult hard clams occurs at 9 to 31/sup 0/C and at 4 to 35 ppt (optima near 20/sup 0/C and 24 to 28 ppt). Hard clams mature in 2 years and reach commercial size in 3 years in the South Atlantic. Tight-fitting shells permit hard clams to survive poor water quality for short periods.

  10. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic): Softshell clam. [Mya arenaria

    SciTech Connect

    Abraham, B.J.; Dillon, P.L.

    1986-08-01

    The softshell clam supports the third most valuable commercial clam fishery in the United States. Density is highest at depths of 3 to 4 m, temperatures less than 28/sup 0/C, and salinities greater than 3 ppt. Its near-shore habitat makes it easily threatened by pollution. Clam beds in some places have been closed because of contamination by bacteria. Softshell clams are more sensitive to oil pollution than are the other clams that share its habitat. The softshell clam spawns in spring (sometimes in early summer) and again in fall. In 36 to 48 h after fertilization, a pelagic veliger larva develops and persists for 2 to 6 weeks. Then it settles out of the plankton. It attaches to the substrate and can move and reattach itself. Eventually, it adopts the adult lifestyle and occupies a permanent burrow, usually in sandy bottom with less than 50% silt. Adult clams feed by filtering small particles from the water column. Predators of adult clams include crabs, fish, birds, and raccoons. The 24-h LC/sub 50/ values for summer-acclimated clams have been reported as 32.5 to 34.4/sup 0/C. Juveniles and adults can withstand long periods of anaerobiosis.

  11. Calibrating brown dwarf ages using white dwarfs in wide binaries

    NASA Astrophysics Data System (ADS)

    Cataln, S.

    Even though age is a critical parameter for all objects, it can also be one of the most difficult to measure, in particular for low-mass stars and brown dwarfs. Brown dwarf models suffer from degeneracy and are not useful to infer ages without well constrained atmospheric parameters \\citep{pin06}. However, there is a way to overcome this problem by studying brown dwarfs for which some external constraints are available, for example brown dwarfs in wide binary systems. Wide binary members share proper motion and are supposed to have been born simultaneously and with the same chemical composition. Since they are well separated (? 1000 AU) we can assume that no interaction has occurred between them in the past and they have evolved as isolated objects. If the companion of the brown dwarfs is a white dwarf, we can use it to calibrate the age of the system. White dwarf evolution can be described as a cooling process which is relatively well understood \\citep[e.g.][]{sal00}. Thus, they yield robust age constraints from the use of cooling sequences \\citep{gar11}. White dwarf cooling ages will uniformally give age lower limits (despite some uncertainty on progenitor life-time), and in some cases yield ages to better than 10% accuracy. Hence, wide binary systems containing a white dwarf can have system age constraints inferred from the white dwarf component. There are not many white dwarf-brown dwarf systems known so far, but with the combination of optical and IR surveys, SDSS+UKIDSS and Gaia + UKIDSS/VHS, new systems will be detected.

  12. Etiology, pathogenesis and epizootiology of hematopoietic neoplasia in the soft-shell clam, Mya arenaria

    SciTech Connect

    Paquette, G.E.

    1992-01-01

    Studies on the etiology of hematopoietic neoplasia (HN) in soft-shell clams, Mya arenaria, have been inconclusive. Petroleum-derived hydrocarbons, polychlorinated-biphenyls and a virus have all been implicated as causative agents. The isolation of 100 nm virus-like particles from neoplastic clams proved conclusively that the causative agent is a retrovirus. The virus can induce a neoplasia in non-neoplastic clams and similar virus particles can be re-isolated and induce neoplasia. The activities of the RT are temperature dependent, found at 6[degrees]C, but not at 25[degrees]C and 37[degrees]C. The incidence rate for neoplasia in Narragansett Bay, Rhode Island was 7.7% and for combined other locations, 3.7% (26/699). HN was present in clams throughout the year at varying levels. The highest incidence occurred in October (11.5%); the lowest incidence in April (1.2%) and June (2.5%). The outcome of the disease depends on the water temperature and degree of severity of neoplasia in the clams. Death rate was greatest when water temperature was at 15[degrees]C (100%). High severity clams had the highest death rate (100%). Chronicity of persistent neoplasia occurred more at 10[degrees]C (19%) than at 6[degrees]C (15%) or 15[degrees]C (0%). Remission occurred only in low severity juvenile clams at either 6[degrees]C or 10[degrees]C. Neoplasia causes metabolic alteration in clams. Remission occurred only in low severity juvenile clams at either 6[degrees]C or 10[degrees]C. The time to remission was longer at 6[degrees]C than 10[degrees]C. Neoplasia causes metabolic alteration in clams. This shown by a significant increase in uric acid, asparatate transminase and triglycerides and a decrease in urea in the hemolymph. The cell membrane of neoplastic hemocytes also shows differences in their binding pattern to lectin than the normal hemocytes, indicating a change in cell surface glycoprotein probably induced by the retrovirus.

  13. White dwarf heating and the ultraviolet flux in dwarf novae

    NASA Technical Reports Server (NTRS)

    Pringle, J. E.

    1988-01-01

    The heating of the outer layers of the white dwarf which is likely to occur during a dwarf nova outburst is investigated. It is shown that the decline in IUE flux, observed during quiescent intervals in the dwarf novae VW Hydri and WX Hydri, may be due to the outer layers cooling off once the heat source is removed. The calculations here assume uniformity of the heat source over the white dwarf surface. This is unlikely to be realized from disk accretion, and discussion is made of what further calculations are required.

  14. Recovery of Waterborne Cryptosporidium parvum Oocysts by Freshwater Benthic Clams (Corbicula fluminea)

    PubMed Central

    Graczyk, Thaddeus K.; Fayer, Ronald; Cranfield, Michael R.; Conn, David Bruce

    1998-01-01

    Asian freshwater clams, Corbicula fluminea, exposed for 24 h to 38 liters of water contaminated with infectious Cryptosporidium parvum oocysts (1.00 106 oocysts/liter; approximately 1.9 105 oocysts/clam) were examined (hemolymph, gills, gastrointestinal [GI] tract, and feces) on days 1, 2, 3, 7, and 14 postexposure (PE). No oocysts were detected in the water 24 h after the contamination event. The percentage of oocyst-containing clams varied from 20 to 100%, depending on the type of tissue examined and the technique usedacid-fast stain (AFS) or immunofluorescent antibody (IFA). The oocysts were found in clam tissues and feces on days 1 through 14 PE; the oocysts extracted from the tissues on day 7 PE were infectious for neonatal BALB/c mice. Overall, the highest number of positive samples was obtained when gills and GI tracts were processed with IFA (prevalence, 97.5%). A comparison of the relative oocyst numbers indicated that overall, 58.3% of the oocysts were found in clam tissues and 41.7% were found in feces when IFA was used; when AFS was used, the values were 51.9 and 48.1%, respectively. Clam-released oocysts were always surrounded by feces; no free oocysts or oocysts disassociated from fecal matter were observed. The results indicate that these benthic freshwater clams are capable of recovery and sedimentation of waterborne C. parvum oocysts. To optimize the detection of C. parvum oocysts in C. fluminea tissue, it is recommended that gill and GI tract samples be screened with IFA (such as that in the commercially available MERIFLUOR test kit). PMID:9464376

  15. Anaerobic methanotrophic community of a 5346-m-deep vesicomyid clam colony in the Japan Trench

    PubMed Central

    Felden, J; Ruff, S E; Ertefai, T; Inagaki, F; Hinrichs, K-U; Wenzhöfer, F

    2014-01-01

    Vesicomyidae clams harbor sulfide-oxidizing endosymbionts and are typical members of cold seep communities where active venting of fluids and gases takes place. We investigated the central biogeochemical processes that supported a vesicomyid clam colony as part of a locally restricted seep community in the Japan Trench at 5346 m water depth, one of the deepest seep settings studied to date. An integrated approach of biogeochemical and molecular ecological techniques was used combining in situ and ex situ measurements. In sediment of the clam colony, low sulfate reduction rates (maximum 128 nmol mL−1 day−1) were coupled to the anaerobic oxidation of methane. They were observed over a depth range of 15 cm, caused by active transport of sulfate due to bioturbation of the vesicomyid clams. A distinct separation between the seep and the surrounding seafloor was shown by steep horizontal geochemical gradients and pronounced microbial community shifts. The sediment below the clam colony was dominated by anaerobic methanotrophic archaea (ANME-2c) and sulfate-reducing Desulfobulbaceae (SEEP-SRB-3, SEEP-SRB-4). Aerobic methanotrophic bacteria were not detected in the sediment, and the oxidation of sulfide seemed to be carried out chemolithoautotrophically by Sulfurovum species. Thus, major redox processes were mediated by distinct subgroups of seep-related microorganisms that might have been selected by this specific abyssal seep environment. Fluid flow and microbial activity were low but sufficient to support the clam community over decades and to build up high biomasses. Hence, the clams and their microbial communities adapted successfully to a low-energy regime and may represent widespread chemosynthetic communities in the Japan Trench. In this regard, they contributed to the restricted deep-sea trench biodiversity as well as to the organic carbon availability, also for non-seep organisms, in such oligotrophic benthic environment of the dark deep ocean. PMID:24593671

  16. Structure of Manila Clam (Ruditapes philippinarum) Microbiota at the Organ Scale in Contrasting Sets of Individuals.

    PubMed

    Meisterhans, Guillaume; Raymond, Natalie; Girault, Emilie; Lambert, Christophe; Bourrasseau, Line; de Montaudouin, Xavier; Garabetian, Frédéric; Jude-Lemeilleur, Florence

    2016-01-01

    Marine invertebrate microbiota has a key function in host physiology and health. To date, knowledge about bivalve microbiota is poorly documented except public health concerns. This study used a molecular approach to characterize the microbiota associated with the bivalve Manila clam (Ruditapes philippinarum) by determining (1) the difference among organs either or not under the influence of host habitat, (2) small-scale variability of microbiota, and (3) the experimental response of the Manila clam microbiota submitted to different lateral transmissions. These questions were investigated by sampling two groups of individuals living in contrasting habitats and carrying out a transplant experiment. Manila clam microbiota (i.e., bacterial community structure) was determined at organ-scale (gills, gut, and a pool of remaining tissues) by capillary electrophoresis DNA fingerprinting (CE fingerprinting). The Manila clam microbiota structure differed among organs indicating a selection of Manila clam microbiota at organ scale. Habitat strongly influenced gill and gut microbiota. In contrast, microbiota associated with remaining tissues was similar between group individuals suggesting that these communities are mostly autochthonous, i.e., Manila clam specific. Transplant experiment showed that improving living condition did not induce any change in microbiota associated with remaining tissues. In contrast, the reduction in individual habitat quality led to individuals in declining health as strongly suggested by the increase in phagocytosis activity and decrease in condition index together with the change in internal organ microbiota. This study provides a first description of the Manila clam holobiont which can withstand disturbance and respond opportunistically to improved environmental conditions. PMID:26311127

  17. Anaerobic methanotrophic community of a 5346-m-deep vesicomyid clam colony in the Japan Trench.

    PubMed

    Felden, J; Ruff, S E; Ertefai, T; Inagaki, F; Hinrichs, K-U; Wenzhöfer, F

    2014-05-01

    Vesicomyidae clams harbor sulfide-oxidizing endosymbionts and are typical members of cold seep communities where active venting of fluids and gases takes place. We investigated the central biogeochemical processes that supported a vesicomyid clam colony as part of a locally restricted seep community in the Japan Trench at 5346 m water depth, one of the deepest seep settings studied to date. An integrated approach of biogeochemical and molecular ecological techniques was used combining in situ and ex situ measurements. In sediment of the clam colony, low sulfate reduction rates (maximum 128 nmol mL(-1) day(-1)) were coupled to the anaerobic oxidation of methane. They were observed over a depth range of 15 cm, caused by active transport of sulfate due to bioturbation of the vesicomyid clams. A distinct separation between the seep and the surrounding seafloor was shown by steep horizontal geochemical gradients and pronounced microbial community shifts. The sediment below the clam colony was dominated by anaerobic methanotrophic archaea (ANME-2c) and sulfate-reducing Desulfobulbaceae (SEEP-SRB-3, SEEP-SRB-4). Aerobic methanotrophic bacteria were not detected in the sediment, and the oxidation of sulfide seemed to be carried out chemolithoautotrophically by Sulfurovum species. Thus, major redox processes were mediated by distinct subgroups of seep-related microorganisms that might have been selected by this specific abyssal seep environment. Fluid flow and microbial activity were low but sufficient to support the clam community over decades and to build up high biomasses. Hence, the clams and their microbial communities adapted successfully to a low-energy regime and may represent widespread chemosynthetic communities in the Japan Trench. In this regard, they contributed to the restricted deep-sea trench biodiversity as well as to the organic carbon availability, also for non-seep organisms, in such oligotrophic benthic environment of the dark deep ocean. PMID:24593671

  18. Local Universe Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Carignan, Claude

    2015-08-01

    One of the outstanding problems in cosmology is addressing the "small-scale crisis" and understanding structure formation at the smallest scales. Standard Lambda Cold Dark Matter cosmological simulations of Milky Way-size DM halos predict many more DM sub-halos than the number of dwarf galaxies observed. This is the so-called Missing Satellites Problem. The most popular interpretation of the Missing Satellites Problem is that the smallest dark matter halos in the universe are extremely inefficient at forming stars. The virialized extent of the Milky Way's halo should contain ~500 satellites, while only 100 satellites and dwarfs are observed in the whole Local Group. Despite the large amount of theoretical work and new optical observations, the discrepancy, even if reduced, still persists between observations and hierarchical models, regardless of the model parameters. It may be possible to find those isolated ultra-faint missing dwarf galaxies via their neutral gas component, which is one of the goals we are pursuing with the SKA precursor KAT-7 in South Africa, and soon with the SKA pathfinder MeerKAT.

  19. Drones at the Beach - Surf Zone Monitoring Using Rotary Wing Unmanned Aerial Vehicles

    NASA Astrophysics Data System (ADS)

    Rynne, P.; Brouwer, R.; de Schipper, M. A.; Graham, F.; Reniers, A.; MacMahan, J. H.

    2014-12-01

    We investigate the potential of rotary wing Unmanned Aerial Vehicles (UAVs) to monitor the surf zone. In recent years, the arrival of lightweight, high-capacity batteries, low-power electronics and compact high-definition cameras has driven the development of commercially available UAVs for hobbyists. Moreover, the low operation costs have increased their potential for scientific research as these UAVs are extremely flexible surveying platforms. The UAVs can fly for ~12 min with a mean loiter radius of 1 - 3.5 m and a mean loiter error of 0.75 - 4.5 m, depending on the environmental conditions, flying style, battery type and vehicle type. Our experiments using multiple, alternating UAVs show that it is possible to have near continuous imagery data with similar Fields Of View. The images obtained from the UAVs (Fig. 1a), and in combination with surveyed Ground Control Points (GCPs) (Fig. 1b, red squares and white circles), can be geo-rectified (Fig. 1c) to pixel resolution between 0.01 - 1 m and a reprojection error, i.e. the difference between the surveyed GPS location of a GCP and the location of the GCP obtained from the geo-rectified image, of O(1 m). These geo-rectified images provide data on a variety of coastal aspects, such as beach width (Wb(x,t)), surf zone width (Wsf(x,t)), wave breaking location (rectangle B), beach usage (circle C) and location of dune vegegation (rectangle D), amongst others. Additionally, the possibility to have consecutive, high frequency (up to 2 Hz) rectified images makes the UAVs a great data instrument for spatially and temporally variable systems, such as the surf zone. Our first observations with the UAVs reveal the potential to quickly obtain surf zone and beach characteristics in response to storms or for day to day beach information, as well as the scientific pursuits of surf zone kinematics on different spatial and temporal scales, and dispersion and advection estimates of pollutants/dye. A selection of findings from several field experiments and using multiple optical instruments will be showed at the meeting, discussing the new possibilities rotary wing UAVs can offer for surf zone research.

  20. Distances to WISE Y dwarfs

    NASA Astrophysics Data System (ADS)

    Beichman; A., C.; Gelino; R., C.; Kirkpatrick, J. Davy

    The WISE satellite has detected some of the coldest, lowest mass objects in the solar neighborhood. These late T and early Y dwarfs have effective temperatures in the range 250-800 K and inferred masses in the range 5-25 MJup. A critical piece of information for determining the physical properties of a brown dwarf is its distance, which greatly improves the comparison with evolutionary models. We discuss the importance of Y dwarfs in the context of star and planet formation. We also update our recent paper on Y dwarf parallaxes with improved values for four objects based on recent observations.

  1. Hunting the Coolest Substellar Dwarfs

    NASA Astrophysics Data System (ADS)

    Zuckerman, Ben; Rodriguez, David; Melis, Carl; Song, Inseok; Vican, Laura

    2015-10-01

    Brown dwarfs with effective surface temperatures of 500 K or cooler have recently been identified as a new spectral class: Y-dwarfs. Some Y-dwarfs have now been discovered, most with the WISE all sky survey. Additional Y-dwarfs may be found by searching for widely separated companions to old stars given that the lowest mass substellar objects discovered in previous imaging surveys tend to have large semi?major axes, typically hundreds of AU. To expand the sample of the coolest brown dwarfs, we propose to re?observe some of our Spitzer Cycle 7 fields that targeted nearby old (ages >2 Gyr) white dwarfs. We have identified a number of 3.6-micron dropouts that could represent cold Y-dwarf companions. These second epoch observations are crucial to confirm these as co-moving substellar companions. As companions to white dwarfs, we will be able to determine the ages of any cool brown dwarfs we find and thus constrain their masses.

  2. The Habitability of White Dwarfs

    NASA Astrophysics Data System (ADS)

    Agol, E.

    2014-04-01

    There exists a region just outside the Roche limit of white dwarfs where a planet would receive an insolation between that of Venus and Mars for up to 8 billion years. If planets can migrate in or re-form after the red-giant phase, there may be a possible long-lived 'habitable zone' around white dwarfs. I will review some of the theoretical prospects, and pitfalls, for planets that might occupy the white dwarf habitable zone, as well as the observational prospects in the near term for finding close-in planets around white dwarfs.

  3. Influence of atmospheric parameters on vertical profiles and horizontal transport of aerosols generated in the surf zone

    NASA Astrophysics Data System (ADS)

    Kusmierczyk-Michulec, J.; Tedeschi, G.; Van Eijk, A. M. J.; Piazzola, J.

    2013-10-01

    The vertical and horizontal transport of aerosols generated over the surf zone is discussed. Experimental data were collected during the second campaign of the Surf Zone Aerosol Experiment that took place in Duck NC (USA) in November 2007. The Empirical Orthogonal Function (EOF) method was used to analyze the vertical concentration gradients, and allowed separating the surf aerosols from aerosols advected from elsewhere. The numerical Marine Aerosol Concentration Model (MACMod) supported the analysis by confirming that the concentration gradients are more pronounced under stable conditions and that aerosol plumes are then more confined to the surface. The model also confirmed the experimental observations made during two boat runs along the offshore wind vector that surf-generated aerosols are efficiently advected out to sea over several tens of kilometers.

  4. Effects of temperature on hard clam (Mercenaria mercenaria) immunity and QPX (Quahog Parasite Unknown) disease development: II. Defense parameters.

    PubMed

    Perrigault, Mickael; Dahl, Soren F; Espinosa, Emmanuelle Pales; Gambino, Laura; Allam, Bassem

    2011-02-01

    Quahog Parasite Unknown (QPX) is a protistan parasite affecting hard clams Mercenaria mercenaria along the Northeastern coast of the United States. The geographic distribution and occurrence of disease epizootics suggests a primary role of temperature in disease development. This study was designed to investigate the effect of temperature on constitutive and QPX-induced defense factors in M. mercenaria. Control and QPX-challenged (both experimentally and naturally) clams were maintained at 13, 21 and 27C for 4 months. Control and experimentally-infected clams originated from a southern broodstock (Florida, no prior reports of disease outbreak) while naturally-infected clams originated from a northern broodstock (Massachusetts, enzootic area). Standard and QPX-specific cellular and humoral defense parameters were assessed after 2 and 4 months. Measured parameters included total and differential hemocyte counts, reactive oxygen species production, phagocytic activity of hemocytes, lysozyme concentration in plasma, anti-QPX activity in plasma and resistance of hemocytes to cytotoxic QPX extracellular products. Results demonstrated a strong influence of temperature on constitutive clam defense factors with significant modulation of cellular and humoral parameters of control clams maintained at 13C compared to 21 and 27C. Similarly, clam response to QPX challenge was also affected by temperature. Challenged clams exhibited no difference from controls at 27C whereas different responses were observed at 21C and 13C compared to controls. Despite differences in infection mode (experimentally or naturally infected) and clam origin (northern and southern broodstocks), similarities were observed at 13C and 21C between QPX infected clams from Florida and Massachusetts. Clam response to temperature and to QPX exhibited interesting relationship with QPX disease development highlighting major influence of temperature on disease development. PMID:21115017

  5. Satellite dwarf galaxies in a hierarchical universe: the prevalence of dwarf-dwarf major mergers

    SciTech Connect

    Deason, Alis; Wetzel, Andrew; Garrison-Kimmel, Shea

    2014-10-20

    Mergers are a common phenomenon in hierarchical structure formation, especially for massive galaxies and clusters, but their importance for dwarf galaxies in the Local Group remains poorly understood. We investigate the frequency of major mergers between dwarf galaxies in the Local Group using the ELVIS suite of cosmological zoom-in dissipationless simulations of Milky Way- and M31-like host halos. We find that ∼10% of satellite dwarf galaxies with M {sub star} > 10{sup 6} M {sub ☉} that are within the host virial radius experienced a major merger of stellar mass ratio closer than 0.1 since z = 1, with a lower fraction for lower mass dwarf galaxies. Recent merger remnants are biased toward larger radial distance and more recent virial infall times, because most recent mergers occurred shortly before crossing within the virial radius of the host halo. Satellite-satellite mergers also occur within the host halo after virial infall, catalyzed by the large fraction of dwarf galaxies that fell in as part of a group. The merger fraction doubles for dwarf galaxies outside of the host virial radius, so the most distant dwarf galaxies in the Local Group are the most likely to have experienced a recent major merger. We discuss the implications of these results on observable dwarf merger remnants, their star formation histories, the gas content of mergers, and massive black holes in dwarf galaxies.

  6. Characterization of breeding habitats for black and surf scoters in the eastern boreal forest and subarctic regions of Canada

    USGS Publications Warehouse

    Perry, M.C.; Kidwell, D.M.; Wells, A.M.; Lohnes, E.J.R.; Osenton, P.C.; Altmann, S.H.

    2006-01-01

    We analyzed characteristics of wetland habitats used by breeding black scoters (Melanitta nigra) and surf scoters (M. perspicillata) in the eastern boreal forest and subarctic regions of Canada based on satellite telemetry data collected in the spring and summer. During 2002 and 2004, nine black scoters (four males, five females) were tracked to breeding areas in Quebec, Manitoba, and Northwest Territories. In addition, in 2001?04, seven surf scoters (three males, four females) were tracked to breeding areas in Labrador, Quebec, Northwest Territories, and Nunavut. Based on satellite telemetry data, locations of black and surf scoters in breeding areas were not significantly different in regard to latitude and longitude. Presumed breeding areas were manually plotted on topographic maps and percent cover type and water were estimated. Breeding habitat of black scoters was significantly different than that for surf scoters, with black scoters mainly using open (tundra) areas (44%) and surf scoters using mainly forest areas (66%). Surf scoters presumed breeding areas were at significantly higher elevations than areas used by black scoters. Some breeding areas were associated with islands, but the role of islands for breeding areas is equivocal. These results aid in the identification of potentially critical breeding areas and provide a baseline classification of breeding habitats used by these two species.

  7. The Evolution of Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Dunn, Jacqueline M.

    2016-01-01

    Dwarf galaxies are the most numerous galaxies in the Universe, yet the driving forces in their evolution remain elusive. The proposed evolutionary link between dwarf irregular and dwarf elliptical/spheroidal galaxies is investigated using broad-band UBVR photometry obtained for a sample of 29 dwarf galaxies. The galaxies span a range of absolute B-band magnitude from -13.67 to -19.86 mag. Broad-band colors and Sérsic surface brightness profile fits are compared for the two morphological types. All optical parameters are statistically different between the two subsamples, as evidenced by the significance level of the Kolmogorov-Smirnov statistic.Others have noted that dwarf ellipticals might have looked much like the currently observed dwarf irregulars in the past based on optical colors. An overlap between in the range of colors observed is noted for these targets, implying the possibility of an evolutionary link. A difference is noted between the two samples in the value of n (the power-law exponent determined from the Sérsic profile fitting), suggesting that the two main types of dwarf galaxy are structurally distinct. The differences in the structure of the stellar components would imply that dwarf irregulars do not evolve to become dwarf ellipticals in isolation, meaning that some sort of external interaction is required if the transformation is to occur. However, when the brightest dwarf elliptical targets are eliminated from the comparison, the two dwarf samples are much more similar in their values and range for the power-law exponent, which again suggests a possible evolutionary link. The environments of the galaxies are initially classified as either field or group/cluster, though no definitive environmental comparison is presented here.

  8. Infection by gymnophallid metacercariae enhances predation mortality of SW Atlantic stout razor clam Tagelus plebeius

    NASA Astrophysics Data System (ADS)

    Addino, Mariana; Lomovasky, Betina J.; Cremonte, Florencia; Iribarne, Oscar

    2010-02-01

    Parasite life cycles are frequently completed in different hosts, thus the parasites have its life cycle overlapped to natural trophic webs. The family Gymnophallidae (Class: Trematoda; Subclass: Digenea) includes digenetic parasites whose larval stages occur on bivalves and may affect bivalve predation by the final host of these parasites. In this work we evaluated: (a) if individuals of the razor clam Tagelus plebeius with higher parasite intensity suffer higher predation by the oystercatcher Haematopus palliatus and, (b) if there is any effect of parasite intensity on burrowing and escape behaviours of these razor clams which may enhance exposure to predators. Field experiments (oystercatcher exclusion vs. open access) showed that clams with higher parasite intensity support higher predation by oystercatchers, which suggests a higher consumption of more parasitized clams and thus, a more successful reproduction of parasites linked to the intensity of infection. However, clam burrowing and escape behaviours did not show differences related to different parasite intensity, suggesting that the commonly believed mechanisms are not responsible in this case.

  9. Sodium channel mutation leading to saxitoxin resistance in clams increases risk of PSP.

    PubMed

    Bricelj, V Monica; Connell, Laurie; Konoki, Keiichi; Macquarrie, Scott P; Scheuer, Todd; Catterall, William A; Trainer, Vera L

    2005-04-01

    Bivalve molluscs, the primary vectors of paralytic shellfish poisoning (PSP) in humans, show marked inter-species variation in their capacity to accumulate PSP toxins (PSTs) which has a neural basis. PSTs cause human fatalities by blocking sodium conductance in nerve fibres. Here we identify a molecular basis for inter-population variation in PSP resistance within a species, consistent with genetic adaptation to PSTs. Softshell clams (Mya arenaria) from areas exposed to 'red tides' are more resistant to PSTs, as demonstrated by whole-nerve assays, and accumulate toxins at greater rates than sensitive clams from unexposed areas. PSTs lead to selective mortality of sensitive clams. Resistance is caused by natural mutation of a single amino acid residue, which causes a 1,000-fold decrease in affinity at the saxitoxin-binding site in the sodium channel pore of resistant, but not sensitive, clams. Thus PSTs might act as potent natural selection agents, leading to greater toxin resistance in clam populations and increased risk of PSP in humans. Furthermore, global expansion of PSP to previously unaffected coastal areas might result in long-term changes to communities and ecosystems. PMID:15815630

  10. Impediment to Symbiosis Establishment between Giant Clams and Symbiodinium Algae Due to Sterilization of Seawater

    PubMed Central

    Kurihara, Takeo; Yamada, Hideaki; Inoue, Ken; Iwai, Kenji; Hatta, Masayuki

    2013-01-01

    To survive the juvenile stage, giant clam juveniles need to establish a symbiotic relationship with the microalgae Symbiodinium occurring in the environment. The percentage of giant clam juveniles succeeding in symbiosis establishment (symbiosis rate) is often low, which is problematic for seed producers. We investigated how and why symbiosis rates vary, depending on whether giant clam seeds are continuously reared in UV treated or non treated seawater. Results repeatedly demonstrated that symbiosis rates were lower for UV treated seawater than for non treated seawater. Symbiosis rates were also lower for autoclaved seawater and 0.2-m filtered seawater than for non treated seawater. The decreased symbiosis rates in various sterilized seawater suggest the possibility that some factors helping symbiosis establishment in natural seawater are weakened owing to sterilization. The possible factors include vitality of giant clam seeds, since additional experiments revealed that survival rates of seeds reared alone without Symbiodinium were lower in sterilized seawater than in non treated seawater. In conclusion, UV treatment of seawater was found to lead to decreased symbiosis rates, which is due possibly to some adverse effects common to the various sterilization techniques and relates to the vitality of the giant clam seeds. PMID:23613802

  11. Dynamics and control of the Asiatic clam in the New River, Virginia. Research report

    SciTech Connect

    Cherry, D.S.; Rodgers, J.H. Jr.; Graney, R.L.; Cairns, J. Jr.

    1980-01-01

    The Asiatic clam, Corbicula fluminea, has invaded the New River at the rate of 9 miles a year from the Kanawha River, which enters downstream from the Glen Lyn coal-powered generating plant in Virginia. During the period of investigation, October 1976-September 1978, clams were more numerous in the vicinity of the thermal discharge of the plant than they were in unheated waters, and their population fell sharply during the winter months, when the water temperature dropped to approximately 2C. The temperature (35C) of the heated discharge water in late summer did not adversely affect the clam. High mortality occurred at temperatures greater or equal to 36C in laboratory thermal tolerance studies. The clam proved to be highly resistant to the conventional biocidal practice of intermittent chlorination and to exposure to heavy metals in both static and artificial stream bioassays. Copper was more toxic than either zinc or a combination of zinc and copper. Potassium was not an effective biocidal agent at low concentrations (less than 100 mg/l). Measurements of 42 elements in water, sediment, clam shell, and visceral tissue revealed that Corbicula was an efficient accumulator of many elements.

  12. Effects of copper on adult and early life stages of the freshwater clam, Corbicula manilensis

    SciTech Connect

    Harrison, F.L.; Knezovich, J.P.; Rice, D.W. Jr.

    1981-09-01

    The copper sensitivity of adult and larval stages of the freshwater clam Corbicula manilensis was evaluated. In addition, copper concentrations in adult clams exposed for 4 to 10 wks to copper in a high-volume, flow-through bioassay are determined. The response of these clams to copper depended on life stage. Copper sensitivity of larvae decreased markedly in successive developmental stages. The LC50/sub 24/s of veliger and juvenile larve were 28 and 600 ..mu..g Cu/L, respectively. The mortality of trochophore larvae exposed to 10 ..mu..g Cu/L for 1 h was 91.5%. The sensitivity to copper decreased with the amount of larval shell deposition. Adult clams were resistant to copper; the LC50/sub 96/ was greater than 2600 ..mu..g Cu/L. By comparison the incipient concentration (ILC) was low - less than 10 ..mu..g Cu/L. Adult clams accumulated more copper as copper concentrations in the water increased. Evidence for copper loss near or at death was obtained.

  13. Identification of an E3 ubiquitin-protein ligase in the softshell clam (Mya arenaria).

    PubMed

    Kelley, M L; Van Beneden, R J

    2000-01-01

    Softshell clams (Mya arenaria) were exposed to dioxin in controlled laboratory experiments in order to study their molecular response to dioxin exposure. A complementary DNA (cDNA) fragment with sequence similarity to E3 ubiquitin-protein ligase appeared to be upregulated in dioxin-exposed clams compared to controls. E3 covalently ligates ubiquitin onto a protein, targeting it for degradation. Our findings suggest that the ubiquitin-mediated proteolytic pathway in the softshell clam may be activated by dioxin exposure. Because the clam E3-predicted amino acid sequence is most similar to a specific vertebrate E3 protein (E6-AP), we hypothesize that dioxin may stimulate ubiquitin-mediated degradation of cell-cycle regulatory proteins, such as the tumor suppressor p53, which promotes cell proliferation. This pathway has been observed in human cervical cancer. Partial cDNA sequence of the clam E3 has been identified using the differential display polymerase chain reaction (ddPCR) and RACE (Rapid Amplification of cDNA Ends) PCR; the full-length sequence is currently being determined. Discovering the molecular mechanism(s) stimulated by dioxin exposure in this invertebrate model may contribute to a better understanding of the effects of dioxin on marine organisms. PMID:11460706

  14. Depletion of Cryptosporidium parvum Oocysts from Contaminated Sewage by Using Freshwater Benthic Pearl Clams (Hyriopsis schlegeli)

    PubMed Central

    Yagita, Kenji; Izumiyama, Shinji; Endo, Takuro; Itoh, Yasoo

    2012-01-01

    The freshwater benthic pearl clam, Hyriopsis schlegeli, was experimentally exposed to Cryptosporidium parvum oocysts, and it was verified that the oocysts were eliminated predominantly via the fecal route, retaining their ability to infect cultured cells (HCT-8). The total fecal oocyst elimination rate was more than 90% within 5 days after exposure to the oocysts. H. schlegeli was able to survive in the final settling pond of a sewage plant for long periods, as confirmed by its pearl production. In the light of these findings, the clam was placed in the final settling pond in a trial to test its long-term efficacy in depleting oocysts contaminating the pond water. The number of clams placed was set to ensure a theoretical oocyst removal rate of around 50%, and the turbidity and the density of feed microbes in the overflow trough water of the pond were about 35% and 40 to 60% lower, respectively, than in the control water throughout the year. It was found that the clam feces containing oocysts were sufficiently heavy for them to settle to the bottom of the pond, despite the upward water flow. From these results, we concluded that efficient depletion of oocysts in the sewage water of small or midscale sewage treatment plants can be achieved by appropriate placement of H. schlegeli clams. PMID:22904053

  15. Hydrocarbon concentrations in sediments and clams (Rangia cuneata) in Laguna de Pom, Mexico

    SciTech Connect

    Alvarez-Legorreta, T.; Gold-Bouchot, G.; Zapata-Perez, O.

    1994-01-01

    Laguna de Pom is a coastal lagoon within the Laguna de Terminos system in southern Gulf of Mexico. It belongs to the Grijalva-Usumacinta basin, and is located between 18{degrees} 33{prime} and 18{degrees} 38{prime} north latitude and 92{degrees} 01{prime} and 92{degrees} 14{prime} west longitude, in the Coastal Plain physiographic Province of the Gulf. It is ellipsoidal and approximately 10 km long, with a surface area of 5,200 ha and a mean depth of 1.5 m. Water salinity and temperature ranges are 0 to 13 {per_thousand} and 25{degrees} to 31{degrees}C, respectively. Benthic macrofauna is dominated by bivalves such as the clams Rangia cuneata, R. flexuosa, and Polymesoda carolineana. These clams provide the basis of an artisanal fishery, which is the main economic activity in the region. The presence of several oil-processing facilities around the lagoon is very conspicuous, which together with decreasing yields has created social conflicts, with the fishermen blaming the mexican state oil company (PEMEX) for the decrease in the clam population. This work aims to determine if the concentration of hydrocarbons in the clams (R. cuneata) and sediments of Laguna de Pom are responsible for the declining clam fishery. 11 refs., 4 figs., 2 tabs.

  16. SurfKin: an ab initio kinetic code for modeling surface reactions.

    PubMed

    Le, Thong Nguyen-Minh; Liu, Bin; Huynh, Lam K

    2014-10-01

    In this article, we describe a C/C++ program called SurfKin (Surface Kinetics) to construct microkinetic mechanisms for modeling gas-surface reactions. Thermodynamic properties of reaction species are estimated based on density functional theory calculations and statistical mechanics. Rate constants for elementary steps (including adsorption, desorption, and chemical reactions on surfaces) are calculated using the classical collision theory and transition state theory. Methane decomposition and water-gas shift reaction on Ni(111) surface were chosen as test cases to validate the code implementations. The good agreement with literature data suggests this is a powerful tool to facilitate the analysis of complex reactions on surfaces, and thus it helps to effectively construct detailed microkinetic mechanisms for such surface reactions. SurfKin also opens a possibility for designing nanoscale model catalysts. PMID:25111729

  17. NBS-SURF calibrations: Use in NASA stratosphere and climate programs

    NASA Astrophysics Data System (ADS)

    Guenther, Bruce; Williams, Donald

    1980-05-01

    In 1976 a rocket measurement series was begun by NASA/GSFC to determine the variation of the solar ultraviolet spectrum between 140 and 350 nm. This is the spectral region which controls the oxygen photochemistry in the stratosphere and mesosphere. This wavelength region was identified in 1977 as an important spectral region to monitor at least once a year for climate studies by a World Meteorological Organization Panel of Experts for the Monitoring of Trace Gases in the Atmosphere. The measuring devices used for the rocket experiments are single Ebert grating monochromators which have been calibrated at the NBS/ SURF to achieve the best available calibration accuracies for this measurement program. Fair agreement is shown between the SURF absolute calibration and a Johns Hopkins University CTE relative calibration.

  18. Comparative genomics of vesicomyid clam (Bivalvia: Mollusca) chemosynthetic symbionts

    PubMed Central

    Newton, Irene LG; Girguis, Peter R; Cavanaugh, Colleen M

    2008-01-01

    Background The Vesicomyidae (Bivalvia: Mollusca) are a family of clams that form symbioses with chemosynthetic gamma-proteobacteria. They exist in environments such as hydrothermal vents and cold seeps and have a reduced gut and feeding groove, indicating a large dependence on their endosymbionts for nutrition. Recently, two vesicomyid symbiont genomes were sequenced, illuminating the possible nutritional contributions of the symbiont to the host and making genome-wide evolutionary analyses possible. Results To examine the genomic evolution of the vesicomyid symbionts, a comparative genomics framework, including the existing genomic data combined with heterologous microarray hybridization results, was used to analyze conserved gene content in four vesicomyid symbiont genomes. These four symbionts were chosen to include a broad phylogenetic sampling of the vesicomyid symbionts and represent distinct chemosynthetic environments: cold seeps and hydrothermal vents. Conclusion The results of this comparative genomics analysis emphasize the importance of the symbionts' chemoautotrophic metabolism within their hosts. The fact that these symbionts appear to be metabolically capable autotrophs underscores the extent to which the host depends on them for nutrition and reveals the key to invertebrate colonization of these challenging environments. PMID:19055818

  19. Tandem Repeat-Containing MITEs in the Clam Donax trunculus

    PubMed Central

    atovi?, Eva; Plohl, Miroslav

    2013-01-01

    Two distinct classes of repetitive sequences, interspersed mobile elements and satellite DNAs, shape eukaryotic genomes and drive their evolution. Short arrays of tandem repeats can also be present within nonautonomous miniature inverted repeat transposable elements (MITEs). In the clam Donax trunculus, we characterized a composite, high copy number MITE, named DTC84. It is composed of a central region built of up to five core repeats linked to a microsatellite segment at one array end and flanked by sequences holding short inverted repeats. The modular composition and the conserved putative target site duplication sequence AA at the element termini are equivalent to the composition of several elements found in the cupped oyster Crassostrea virginica and in some insects. A unique feature of D. trunculus element is ordered array of core repeat variants, distinctive by diagnostic changes. Position of variants in the array is fixed, regardless of alterations in the core repeat copy number. Each repeat harbors a palindrome near the junction with the following unit, being a potential hotspot responsible for array length variations. As a consequence, variations in number of tandem repeats and variations in flanking sequences make every sequenced element unique. Core repeats may be thus considered as individual units within the MITE, with flanking sequences representing a cassette for internal repeats. Our results demonstrate that onset and spread of tandem repeats can be more intimately linked to processes of transposition than previously thought and suggest that genomes are shaped by interplays within a complex network of repetitive sequences. PMID:24317975

  20. Tandem repeat-containing MITEs in the clam Donax trunculus.

    PubMed

    Satovic, Eva; Plohl, Miroslav

    2013-01-01

    Two distinct classes of repetitive sequences, interspersed mobile elements and satellite DNAs, shape eukaryotic genomes and drive their evolution. Short arrays of tandem repeats can also be present within nonautonomous miniature inverted repeat transposable elements (MITEs). In the clam Donax trunculus, we characterized a composite, high copy number MITE, named DTC84. It is composed of a central region built of up to five core repeats linked to a microsatellite segment at one array end and flanked by sequences holding short inverted repeats. The modular composition and the conserved putative target site duplication sequence AA at the element termini are equivalent to the composition of several elements found in the cupped oyster Crassostrea virginica and in some insects. A unique feature of D. trunculus element is ordered array of core repeat variants, distinctive by diagnostic changes. Position of variants in the array is fixed, regardless of alterations in the core repeat copy number. Each repeat harbors a palindrome near the junction with the following unit, being a potential hotspot responsible for array length variations. As a consequence, variations in number of tandem repeats and variations in flanking sequences make every sequenced element unique. Core repeats may be thus considered as individual units within the MITE, with flanking sequences representing a "cassette" for internal repeats. Our results demonstrate that onset and spread of tandem repeats can be more intimately linked to processes of transposition than previously thought and suggest that genomes are shaped by interplays within a complex network of repetitive sequences. PMID:24317975

  1. "Sub-Surf Rocks"! An A-Level Resource Developed through an Industry-Education Collaboration

    ERIC Educational Resources Information Center

    Mather, Hazel

    2012-01-01

    A free internet resource called "Sub-Surf Rocks"! was launched in 2010. Its aim is to use seismic data obtained by the oil industry for enhancing the teaching of structural and economic geology at A-level (ages 16-18) in the UK. Seismic data gives a unique insight into the sub-surface and the many high-quality images coupled with ready-made (but

  2. Immediate Surgical Skills Feedback in the Operating Room Using SurF Cards

    PubMed Central

    Connolly, AnnaMarie; Hansen, Darci; Schuler, Kevin; Galvin, Shelley L.; Wolfe, Honor

    2014-01-01

    Background Ensuring residents develop operative skills requires application of the principles of guided learning, deliberate practice, and directed feedback. Objective We sought to create and implement a tool to promote procedural key step review and immediate feedback on surgical skills, and examined faculty and resident satisfaction with surgical skills feedback. Methods We created surgical skills feedback (SurF) cards for 8 gynecologic procedures. Faculty/fellows and residents completed prestudy surveys querying frequency of preoperative key step review and satisfaction with surgical skill feedback, a SurF card each time 1 of 8 procedures was performed, and poststudy surveys to evaluate for changes. Results Prestudy surveys were completed by 31 faculty/fellows and 20 residents, with 55% (17 of 31) of the faculty/fellows and 5% (1 of 20) of the residents reporting key step review before surgery. All reported low satisfaction rates with feedback frequency, quality, and timeliness. After implementation of SurF cards, preoperative key step review occurred in 78% (82 of 105) of the procedures. Twenty-one faculty/fellows (68%) and 16 residents (80%) completed our poststudy survey. Faculty/fellows reported statistically similar key step review (n??=??15 [71%], P??=??.23), while residents reported that key step review had significantly improved (n??=??6 [38%], P??=??.01). Resident satisfaction with feedback frequency (5% to 50%, P??=??.002) and quality (15% to 50%, P??=??.02) increased significantly. Conclusions The SurF cards we developed facilitated procedural key step review, were associated with significantly improved resident satisfaction with surgical feedback, and could prove helpful with outcomes assessments, such as Accreditation Council for Graduate Medical Educationrequired documentation of Milestone attainment. PMID:25512804

  3. Accumulation of trace elements and organochlorines by surf scoters wintering in the Pacific northwest

    USGS Publications Warehouse

    Henny, C.J.; Blus, L.J.; Grove, R.A.; Thompson, S.P.

    1991-01-01

    Selenium, cadmium, mercury, copper, manganese, zinc, aluminum, lead, PCBs and DDE were accumulated by segments of the surf scoter (Melanitta perspicillata) population that winters in the Pacific Northwest, but whether the uptake occurred on breeding and/or wintering grounds was uncertain for some contaminants. Surf scoters collected in Puget Sound and San Francisco Bay (in another study) during the same period (January 1985) contained similar concentrations of cadmium, but Alsea Bay scoters contained more. Cadmium was inversely related to both liver and body weights of Northwest scoters in January; similar weight losses were reported in experimental laboratory studies. Northwest and north San Francisco Bay scoters contained similar mercury concentrations, but those in south San Francisco Bay contained higher concentrations. San Francisco Bay scoters contained higher arsenic and selenium concentrations than those in the Northwest; however, the 43.4 ppm (geometric mean, dry wt) selenium in livers at Commencement Bay in January was above levels associated with the reproductive problems in aquatic birds at Kesterson National Wildlife Refuge. Even higher concentrations of some elements may be found in surf scoters in March, because a later collection (March) at San Francisco Bay yielded higher concentrations than found there in January. Trace element concentrations in birds at a given wintering location are variable among species and may be influenced by diet, breeding grounds, and physiology (e.g., at Commencement Bay surf scoters with a sediment-associated diet contained 50X more cadmium in their kidneys than did fish-eating western grebes [Aechmophorus occidentalis]). The numerous wildlife species that live on estuaries require further attention.

  4. "Sub-Surf Rocks"! An A-Level Resource Developed through an Industry-Education Collaboration

    ERIC Educational Resources Information Center

    Mather, Hazel

    2012-01-01

    A free internet resource called "Sub-Surf Rocks"! was launched in 2010. Its aim is to use seismic data obtained by the oil industry for enhancing the teaching of structural and economic geology at A-level (ages 16-18) in the UK. Seismic data gives a unique insight into the sub-surface and the many high-quality images coupled with ready-made (but…

  5. Geographic Variations and Genetic Distance of Three Geographic Cyclina Clam (Cyclina sinensis Gmelin) Populations from the Yellow Sea

    PubMed Central

    Yoon, Jong-Man

    2012-01-01

    The gDNA isolated from Cyclina sinensis from Gochang (GOCHANG), Incheon (INCHEON) and a Chinese site (CHINESE), were amplified by PCR. Here, the seven oligonucleotide decamer primers (BION-66, BION-68, BION-72, BION-73, BION-74, BION-76, and BION-80) were used to generate the unique shared loci to each population and shared loci by the three cyclina clam populations. As regards multiple comparisons of average bandsharing value results, cyclina clam population from Chinese (0.763) exhibited higher bandsharing values than did clam from Incheon (0.681). In this study, the dendrogram obtained by the seven decamer primers indicates three genetic clusters: cluster 1 (GOCHANG 01~ GOCHANG 07), cluster 2 (INCHEON 08~INCHEON 14), cluster 3 (CHINESE 15~CHINESE 21). The shortest genetic distance that displayed significant molecular differences was between individuals 15 and 17 from the Chinese cyclina clam (0.049), while the longest genetic distance among the twenty-one cyclina clams that displayed significant molecular differences was between individuals GOCHANG no. 03 and INCHEON no. 12 (0.575). Individuals of Incheon cyclina clam population was somewhat closely related to that of Chinese cyclina clam population. In conclusion, our PCR analysis revealed a significant genetic distance among the three cyclina clam populations. PMID:25949106

  6. Quantitative Real-Time PCR Assay for QPX (Thraustochytriidae), a Parasite of the Hard Clam (Mercenaria mercenaria)?

    PubMed Central

    Liu, Qianqian; Allam, Bassem; Collier, Jackie L.

    2009-01-01

    We developed a real-time quantitative PCR (qPCR) assay targeting the rRNA internal transcribed spacer region of the hard clam pathogen QPX. The qPCR assay was more sensitive than was histology in detecting clams with light QPX infections. QPX was detected in 4 of 43 sediment samples but in none of 40 seawater samples. PMID:19465523

  7. Modulatory effects of hard clam (Mercenaria mercenaria) tissue extracts on the in vitro growth of its pathogen QPX.

    PubMed

    Perrigault, Mickael; Bugg, Deenie M; Hao, Chen Chuan; Allam, Bassem

    2009-01-01

    Quahog parasite unknown (QPX) is a fatal protistan parasite affecting cultured and wild hard clams Mercenaria mercenaria along the northeastern coasts of the USA and maritime Canada. Field investigations and laboratory transmission studies revealed some variations in the susceptibility of different hard clam stocks to QPX infection. In this study, we used in vitro QPX cultures to investigate the effect of plasma and tissue extracts from two different clam stocks on parasite survival and growth. Results demonstrated the presence of factors in clams that significantly modulate QPX growth. Extracts from gills and mantle tissues as well as plasma inhibited in vitro QPX growth, whereas foot and adductor muscle extracts enhanced parasite growth. Investigations of anti-QPX activities in plasma from two clam stocks displaying different susceptibility toward QPX disease in vivo demonstrated higher inhibition of QPX growth by plasma from New York (resistant) clams compared to Florida (susceptible) clams. Some clams appeared to be deficient in inhibitory factors, suggesting that such animals may become more easily infected by the parasite. PMID:18938174

  8. Observations of a Protistan Disease Similar to QPX in Mercenaria mercenaria (Hard Clams) from the Coast of Massachusetts

    PubMed

    Smolowitz; Leavitt; Perkins

    1998-01-01

    During the summer and fall of 1995, in clam aquaculture leases at two locations on the coast of Massachusetts, significant mortalities were observed to occur primarily in 1- to 2-year old hard clams (Mercenaria mercenaria, quahog) planted in the leases. Examination of hard clams from those leases suggested a parasite similar to QPX (Quahog Parasite Unknown), as described by Whyte, S. K., Cawthorn, R. J., and McGladdery, S. E. (1994, Can. Dis. Ag. Org. 19, 129-136), was responsible for the poor condition of affected clams and the resulting high mortality. In clam tissues, the QPX-like parasite formed thalli surrounded by a mucofilamentous net. Larger thalli underwent endosporulation producing sporangia that contained approximately 40 endospores. Rupture of the sporangium released the endospores into the surrounding tissue. Inflammatory response by the clam to infection was chronic, active, and granulomatous. The occurrence both of phagocytic multinucleated giant inflammatory cells and inflammatory encapsulation of parasites were commonly identified as part of the response. Moderately to severely infected clams showed significantly reduced growth and a poorer condition index as compared to uninfected or mildly infected clams. Copyright 1998 Academic Press. Copyright 1998 Academic Press PMID:9446733

  9. Quantitative real-time PCR assay for QPX (Thraustochytriidae), a parasite of the hard clam (Mercenaria mercenaria).

    PubMed

    Liu, Qianqian; Allam, Bassem; Collier, Jackie L

    2009-07-01

    We developed a real-time quantitative PCR (qPCR) assay targeting the rRNA internal transcribed spacer region of the hard clam pathogen QPX. The qPCR assay was more sensitive than was histology in detecting clams with light QPX infections. QPX was detected in 4 of 43 sediment samples but in none of 40 seawater samples. PMID:19465523

  10. Toxicological evaluation of two pedigrees of clam Ruditapes philippinarum as bioindicators of heavy metal contaminants using metabolomics.

    PubMed

    Ji, Chenglong; Cao, Lulu; Li, Fei

    2015-03-01

    Heavy metal pollution has been of great concern in the Bohai marine environment. Manila clam Ruditapes philippinarum has been used as a bioindicator in marine toxicology. In this study, NMR-based metabolomics was used to ascertain whether there were significant biological differences between two dominant pedigrees (White and Zebra) of clam and evaluate the suitability of two pedigrees for marine environmental toxicology, together with antioxidant enzymatic analysis. Our results indicated that there were significant biological differences between White and Zebra clams based on the metabolic profiles and antioxidant enzyme activities. In details, the metabolic profiles showed higher levels of amino acids and succinate in Zebra clam digestive glands and higher levels of ATP in White clam digestive glands, respectively. The superoxide dismutase activities in control White and Zebra clam samples were significantly different. Additionally, White clam was more sensitive to Cd based on the significant accumulation of Cd, antioxidant enzymatic alterations and sensitive metabolic changes. Overall, we concluded that White clam could be a preferable bioindicator for marine environmental toxicology. PMID:25681705

  11. EFFECTS OF RECREATIONAL CLAM HARVESTING ON EELGRASS (ZOSTERA MARINA) AND ASSOCIATED INFAUNAL INVERTEBRATES: IN SITU MANIPULATIVE EXPERIMENTS

    EPA Science Inventory

    The effect of recreational clam harvesting on eelgrass (Zostera marina) was experimentally tested by raking or digging for clams in experimental 1-m2 plots located in a Yaquina Bay (Newport, OR) eelgrass meadow. After three monthly treatments, eelgrass measures of biomass, prima...

  12. Clam Ruditapes philippinarum recovery from short-term exposure to the combined effect of salinity shifts and Arsenic contamination.

    PubMed

    Velez, Catia; Teixeira, Miguel; Wrona, Frederick J; Soares, Amadeu M V M; Figueira, Etelvina; Freitas, Rosa

    2016-04-01

    The current study assessed the biochemical alterations induced in the clam species Ruditapes philippinarum after exposure to salinity shifts (14, 28 and 42) and arsenic (As) contamination (0 and 2mg/L). The capacity of this species to recover (96h and 28 days) after exposure (96h) to both stressors, acting alone and in combination, was also evaluated. After exposure, regardless of the salinity tested, clams contaminated with As showed higher concentrations than non-contaminated specimens. After recovery, As concentration in clams decreased, with contaminated and non-contaminated specimens presenting similar values. The results obtained further demonstrated that exposure to As (2mg/L) at different salinities (salinities 14, 28 and 42) and salinity 42 (As 0mg/L) lead to an increase of lipid peroxidation and detoxification mechanisms in clams, compared with non-contaminated clams at salinities of 14 and 28. After recovery, at salinities 14 and 28, clams previously exposed to As were capable to decrease their oxidative stress to levels found in non-contaminated clams. Nevertheless, at salinity 42 both contaminated and non-contaminated clams did not survive. Overall results of measured energy-related parameters, indicators of oxidative stress, antioxidant and biotransformation enzymes indicated that As exposure and salinity shifts caused biochemical alterations in R. philippinarum, with stronger impacts when both stressors were acting in combination. PMID:26889773

  13. DIRECT MEASUREMENT TECHNIQUE FOR THE DETERMINING VENTILATION RATE IN THE DEPOSIT FEEDING CLAM, MACOMA NASUTA (BIVALVIA, TELLINACEAE)

    EPA Science Inventory

    An exposure chamber, the "clambox", was developed to measure ventilation rate, sediment processing rate, and efficiency of pollutant uptake byMacoma nasuta Conrad, a surface surface deposit-feeding clams. Clams, collected from Yaquina, Bay, Oregon, USA, were cemented into a hole ...

  14. Pedestrian detection in far-infrared daytime images using a hierarchical codebook of SURF.

    PubMed

    Besbes, Bassem; Rogozan, Alexandrina; Rus, Adela-Maria; Bensrhair, Abdelaziz; Broggi, Alberto

    2015-01-01

    One of the main challenges in intelligent vehicles concerns pedestrian detection for driving assistance. Recent experiments have showed that state-of-the-art descriptors provide better performances on the far-infrared (FIR) spectrum than on the visible one, even in daytime conditions, for pedestrian classification. In this paper, we propose a pedestrian detector with on-board FIR camera. Our main contribution is the exploitation of the specific characteristics of FIR images to design a fast, scale-invariant and robust pedestrian detector. Our system consists of three modules, each based on speeded-up robust feature (SURF) matching. The first module allows generating regions-of-interest (ROI), since in FIR images of the pedestrian shapes may vary in large scales, but heads appear usually as light regions. ROI are detected with a high recall rate with the hierarchical codebook of SURF features located in head regions. The second module consists of pedestrian full-body classification by using SVM. This module allows one to enhance the precision with low computational cost. In the third module, we combine the mean shift algorithm with inter-frame scale-invariant SURF feature tracking to enhance the robustness of our system. The experimental evaluation shows that our system outperforms, in the FIR domain, the state-of-the-art Haar-like Adaboost-cascade, histogram of oriented gradients (HOG)/linear SVM (linSVM) and MultiFtrpedestrian detectors, trained on the FIR images. PMID:25871724

  15. Human Action Poselets Estimation via Color G-Surf in Still Images

    NASA Astrophysics Data System (ADS)

    Favorskaya, M.; Novikov, D.; Savitskaya, Y.

    2015-05-01

    Human activity is a persistent subject of interest in the last decade. On the one hand, video sequences provide a huge volume of motion information in order to recognize the human active actions. On the other hand, the spatial information about static human poses is valuable for human action recognition. Poselets were introduced as latent variables representing a configuration for mutual locations of body parts and allowing different views of description. In current research, some modifications of Speeded-Up Robust Features (SURF) invariant to affine geometrical transforms and illumination changes were tested. First, a grid of rectangles is imposed on object of interest in a still image. Second, sparse descriptor based on Gauge-SURF (G-SURF) invariant to color/lighting changes is constructed for each rectangle separately. A common Spatial POselet Descriptor (SPOD) aggregates the SPODs of rectangles with following random forest classification in order to receive fast classification results. The proposed approach was tested on samples from PASCAL Visual Object Classes (VOC) Dataset and Challenge 2010 providing accuracy 61-68% for all possible 3D poses locations and 82-86% for front poses locations regarding to nine action categories.

  16. Rehabilitation and long-term course of nontraumatic myelopathy associated with surfing.

    PubMed

    Aoki, Masahiro; Moriizumi, Shigehiro; Toki, Megumi; Murakami, Takanori; Ishiai, Sumio

    2013-09-01

    A nontraumatic spinal cord injury related to surfing is called surfer's myelopathy. The case of a 26-yr-old man who became paraplegic after surfing without apparent traumatic events is described. Physical examination revealed a spinal cord injury at T12 according to the American Spinal Injury Association Impairment Scale A. The initial magnetic resonance image revealed a fusiform swelling of the spinal cord from T7-8 to the conus, which was hyperintense on T2-weighted images. After 6 mos of rehabilitation, the patient was followed for more than 1 yr after onset. He became able to walk with knee-ankle-foot-orthoses without assistance. A magnetic resonance image obtained 1 yr after the onset of paraplegia showed an atrophic spinal cord from T7-8 to the conus. The course of the neurologic findings and the imaging studies suggest that the pathogenesis of surfer's myelopathy may be ischemia of the anterior spinal artery territory induced by the abnormal trunk posture while surfing. PMID:22019977

  17. Surf-zone Chlorophyll aVariability at Cassino Beach, Southern Brazil

    NASA Astrophysics Data System (ADS)

    Odebrecht, C.; Segatto, A. Z.; Freitas, C. A.

    1995-07-01

    Chlorophyll a, water temperature, salinity, seston weight and dissolved inorganic nutrients (silicate, phosphate, nitrite+nitrate) were measured every other day between 30 April and 31 July 1987, in the surf-zone at a fixed point of the exposed sandy beach Cassino (3210'S, 5210'W). Chlorophyll avariability showed two phases: (1) from 30 April to mid-May chlorophyll aconcentration was variable but high, with concentrations up to 1647 ?g l -1, and brown coloured patches of the surf-zone diatom Asterionellopsis glacialiswere conspicuous with cell concentration up to 709 10 8cells l -1; (2) from mid-May to the end of July chlorophyll aconcentration was low and brown coloured patches were not observed. The results of this study indicate that the mesoscale variability of chlorophyll aand accumulation of patches is primarily controlled by exogenous meteorological factors such as wind direction and velocity, where southerly onshore winds act as the main factor accumulating cells in the surf-zone at Cassino Beach.

  18. Pedestrian Detection in Far-Infrared Daytime Images Using a Hierarchical Codebook of SURF

    PubMed Central

    Besbes, Bassem; Rogozan, Alexandrina; Rus, Adela-Maria; Bensrhair, Abdelaziz; Broggi, Alberto

    2015-01-01

    One of the main challenges in intelligent vehicles concerns pedestrian detection for driving assistance. Recent experiments have showed that state-of-the-art descriptors provide better performances on the far-infrared (FIR) spectrum than on the visible one, even in daytime conditions, for pedestrian classification. In this paper, we propose a pedestrian detector with on-board FIR camera. Our main contribution is the exploitation of the specific characteristics of FIR images to design a fast, scale-invariant and robust pedestrian detector. Our system consists of three modules, each based on speeded-up robust feature (SURF) matching. The first module allows generating regions-of-interest (ROI), since in FIR images of the pedestrian shapes may vary in large scales, but heads appear usually as light regions. ROI are detected with a high recall rate with the hierarchical codebook of SURF features located in head regions. The second module consists of pedestrian full-body classification by using SVM. This module allows one to enhance the precision with low computational cost. In the third module, we combine the mean shift algorithm with inter-frame scale-invariant SURF feature tracking to enhance the robustness of our system. The experimental evaluation shows that our system outperforms, in the FIR domain, the state-of-the-art Haar-like Adaboost-cascade, histogram of oriented gradients (HOG)/linear SVM (linSVM) and MultiFtrpedestrian detectors, trained on the FIR images. PMID:25871724

  19. Preventing Shoulder-Surfing Attack with the Concept of Concealing the Password Objects' Information

    PubMed Central

    Ho, Peng Foong; Kam, Yvonne Hwei-Syn; Wee, Mee Chin

    2014-01-01

    Traditionally, picture-based password systems employ password objects (pictures/icons/symbols) as input during an authentication session, thus making them vulnerable to shoulder-surfing attack because the visual interface by function is easily observed by others. Recent software-based approaches attempt to minimize this threat by requiring users to enter their passwords indirectly by performing certain mental tasks to derive the indirect password, thus concealing the user's actual password. However, weaknesses in the positioning of distracter and password objects introduce usability and security issues. In this paper, a new method, which conceals information about the password objects as much as possible, is proposed. Besides concealing the password objects and the number of password objects, the proposed method allows both password and distracter objects to be used as the challenge set's input. The correctly entered password appears to be random and can only be derived with the knowledge of the full set of password objects. Therefore, it would be difficult for a shoulder-surfing adversary to identify the user's actual password. Simulation results indicate that the correct input object and its location are random for each challenge set, thus preventing frequency of occurrence analysis attack. User study results show that the proposed method is able to prevent shoulder-surfing attack. PMID:24991649

  20. Estimating wave energy dissipation in the surf zone using thermal infrared imagery

    NASA Astrophysics Data System (ADS)

    Carini, Roxanne J.; Chickadel, C. Chris; Jessup, Andrew T.; Thomson, Jim

    2015-06-01

    Thermal infrared (IR) imagery is used to quantify the high spatial and temporal variability of dissipation due to wave breaking in the surf zone. The foam produced in an actively breaking crest, or wave roller, has a distinct signature in IR imagery. A retrieval algorithm is developed to detect breaking waves and extract wave roller length using measurements taken during the Surf Zone Optics 2010 experiment at Duck, NC. The remotely derived roller length and an in situ estimate of wave slope are used to estimate dissipation due to wave breaking by means of the wave-resolving model by Duncan (1981). The wave energy dissipation rate estimates show a pattern of increased breaking during low tide over a sand bar, consistent with in situ turbulent kinetic energy dissipation rate estimates from fixed and drifting instruments over the bar. When integrated over the surf zone width, these dissipation rate estimates account for 40-69% of the incoming wave energy flux. The Duncan (1981) estimates agree with those from a dissipation parameterization by Janssen and Battjes (2007), a wave energy dissipation model commonly applied within nearshore circulation models.

  1. Alongshore momentum in the outer surf zone under hurricane wind and wave forcing

    NASA Astrophysics Data System (ADS)

    Mulligan, R. P.; Hanson, J. L.

    2014-12-01

    Wave breaking is the dominant physical process acting along beaches and coasts exposed to surface waves during storms, causing large gradients in wave momentum that generate strong currents in the nearshore zone. At the outer edge of the wave breaking region, strong horizontal current shear between the alongshore currents and alongshelf flows can develop and drive strong shear and mixing between these regions. Wave and current observations from a cross-shore array of six acoustic sensors in water depths of 2-11 m at Duck, NC, are used to elucidate the balance of momentum under storm wave conditions with wide surf zones, corresponding to offshore hurricanes. Offshore hurricanes that are distal (calm local wind) and proximal (local wind up to 25 m/s) generate large wave heights (3-5 m) and very strong alongshore currents (up to 2 m/s). We find that horizontal shear contributes strongly to momentum at the seaward limit of the surf zone and that radiation stress gradients, bottom stress, wind stress, mixing and advection play important roles at different times and locations in the cross-shore integrated momentum balance. The results provide insight into the cross-shore distribution of the alongshore current and the connection between alongshore flows inside the surf zone and outside it during major storms.

  2. White Dwarf Population Statistical Analysis

    NASA Astrophysics Data System (ADS)

    Rybicka, M.; Krzeszowski, K.; Slowikowska, A.

    2013-01-01

    Villanova University White Dwarf Catalog (McCook & Sion 1999) contains almost 13 000 white dwarfs (WDs). Different WD types show different properties (e.g. Brightness, magnetic field). We present population wide statistical analysis of various WD properties. Analysis includes, but is not limited to e.g. distribution analysis and correlations.

  3. EXOSAT observations of M dwarfs

    NASA Astrophysics Data System (ADS)

    Schmitt, J. H. M. M.; Sztajno, M.

    1985-02-01

    The authors give a progress report of their EXOSAT observations of active M dwarfs. The possibilities of filter spectroscopy of coronal X-ray sources using the available CMA filters are discussed, and the authors confirm that M dwarfs are rather hot coronal sources with X-ray temperatures in excess of 107K, a result previously obtained with the Einstein Observatory.

  4. Kinematics of faint white dwarfs.

    PubMed

    Luyten, W J

    1978-10-01

    An analysis has been made for solar motion for 128 very faint white dwarfs of color class b or a. While about 40% of these stars may be high-velocity objects, it seems definitely indicated that the luminosity of all of them is considerably lower than that for the "normal" white dwarf of the same color. PMID:16592566

  5. Testing gravity using dwarf stars

    NASA Astrophysics Data System (ADS)

    Sakstein, Jeremy

    2015-12-01

    Generic scalar-tensor theories of gravity predict deviations from Newtonian physics inside astrophysical bodies. In this paper, we point out that low mass stellar objects, red and brown dwarf stars, are excellent probes of these theories. We calculate two important and potentially observable quantities: the radius of brown dwarfs and the minimum mass for hydrogen burning in red dwarfs. The brown dwarf radius can differ significantly from the general relativity prediction, and upcoming surveys that probe the mass-radius relation for stars with masses dwarf stars. This places a new and extremely stringent constraint on the parameters that appear in the effective field theory of dark energy and rules out several well-studied dark energy models.

  6. Brown dwarfs detections through microlensing

    NASA Astrophysics Data System (ADS)

    Ranc, C.; Cassan, A.

    2014-12-01

    Gravitational microlensing is known to be a powerful method to hunt for extrasolar planets and brown dwarfs. Recently, several brown dwarfs companions to stars have been detected through microlensing, as well as brown dwarfs binaries. We present the discovery of a new 40 M_{J} brown dwarf orbiting a K-dwarf at 4 AU, located at 4 kpc from the Earth. Besides using the standard photometric light curves gathered from different round-the-world observatories, its characterization involved high-resolution adaptative optics measurements from NaCo at VLT which allowed to break the degeneracies between the physical parameters and provide the exact mass and projected separation of the system.

  7. M Dwarf Flares: Exoplanet Implications

    NASA Astrophysics Data System (ADS)

    Wisniewski, John; Kowalski, Adam; Schmidt, Sarah; Hawley, Suzanne; Kundurthy, Praveen

    2009-08-01

    Low mass M dwarfs are attractive stars for exoplanet transit research as their low luminosities and small stellar radii could enable detection of super-Earths residing in their habitable zones using existing technology. Future IR facilities such as JWST will undoubtedly attempt to characterize these systems through detailed transit observations. M dwarfs can exhibit highly energetic flare events which cause <0.1 to 6.0 magnitude flux enhancements in the optical U-band, which is significantly higher than the predicted transit depths of super- Earths (~0.005 magnitude flux decrease). While Solar flares have been observed to cause IR continuum enhancements (Xu et al 2006); surprisingly, it is not known whether energetic flares associated with M dwarfs similarly induce IR variability. We propose to contemporaneously monitor the optical & IR flux of two M dwarfs known to regularly flare, to determine what effect flares could have on future IR characterization studies of M dwarf exoplanets.

  8. Barley yellow dwarf viruses.

    PubMed

    Miller, W A; Rasochová, L

    1997-01-01

    Barley yellow dwarf viruses represent one of the most economically important and ubiquitous groups of plant viruses. This review focuses primarily on four research areas in which progress has been most rapid. These include (a) evidence supporting reclassification of BYDVs into two genera; (b) elucidation of gene function and novel mechanisms controlling gene expression; (c) initial forays into understanding the complex interactions between BYDV virions and their aphid vectors; and (d) replication of a BYDV satellite RNA. Economic losses, symptomatology, and means of control of BYD are also discussed. PMID:15012520

  9. Dwarfs in Coma Cluster

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Click on image for larger poster version

    This false-color mosaic of the central region of the Coma cluster combines infrared and visible-light images to reveal thousands of faint objects (green). Follow-up observations showed that many of these objects, which appear here as faint green smudges, are dwarf galaxies belonging to the cluster. Two large elliptical galaxies, NGC 4889 and NGC 4874, dominate the cluster's center. The mosaic combines visible-light data from the Sloan Digital Sky Survey (color coded blue) with long- and short-wavelength infrared views (red and green, respectively) from NASA's Spitzer Space Telescope.

  10. Review on the Risk Assessment of Heavy Metals in Malaysian Clams

    PubMed Central

    Hamdan, Sinin; Rahman, Md. Rezaur

    2015-01-01

    The current review discusses the levels of six heavy metals in different clam species from 34 sites of Malaysian coasts. The concentrations (µg/g dry weight) of these heavy metals ranged around 0.18–8.51, 0.13–17.20, 2.17–7.80, 0.84–36.00, 24.13–368.00, and 177.82–1912.00 for Cd, Pb, Ni, Cu, Zn, and Fe, respectively. It was observed that the concentrations of metals slightly depend on different clam species but mostly depend on site locations. According to Malaysian Food Regulation (1985), about 30% and more than 50% sites are safe from Cd and Pb contamination, respectively, and also the clam species from the other populations studied were safe for consumption. PMID:26060840

  11. Influence of thermal aging on microstructure and mechanical properties of CLAM steel

    NASA Astrophysics Data System (ADS)

    Huang, Lixin; Hu, Xue; Yang, Chunguang; Yan, Wei; Xiao, Furen; Shan, Yiyin; Yang, Ke

    2013-11-01

    In order to investigate the influence of thermal aging on microstructure and mechanical properties of CLAM (China low activation martensitic) steel, a comparison study was made on the as-tempered and the aged steels. The tempered CLAM steels were subjected to aging treatment at 600 C for 1100 h and 3000 h, and at 650 C for 1100 h, respectively. The changes of microstructure were characterized by both transmission electron microscope (TEM) and scanning electron microscope (SEM). The mechanical properties were evaluated by Charpy impact, tensile and Vickers hardness tests. The upper shelf energy (USE) of the thermal aged CLAM steel decreased with the extension of aging time, while the yield strength changed slightly. After long-term thermal aging, the MX type precipitates remained stable. The coarsening of M23C6 and the formation of Laves phase were confirmed by scanning/transmission electron microscopes. The Laves phase was the main factor leading to the increase of DBTT.

  12. Effect of irradiation temperature on void swelling of China Low Activation Martensitic steel (CLAM)

    SciTech Connect

    Zhao Fei; Qiao Jiansheng; Huang Yina; Wan Farong Ohnuki, Soumei

    2008-03-15

    CLAM is one composition of a Reduced Activation Ferritic/Martensitic steel (RAFM), which is being studied in a number of institutes and universities in China. The effect of electron-beam irradiation temperature on irradiation swelling of CLAM was investigated by using a 1250 kV High Voltage Electron Microscope (HVEM). In-situ microstructural observations indicated that voids formed at each experimental temperature - 723 K, 773 K and 823 K. The size and number density of voids increased with increasing irradiation dose at each temperature. The results show that CLAM has good swelling resistance. The maximum void swelling was produced at 723 K; the swelling was about 0.3% when the irradiation damage was 13.8 dpa.

  13. Bioaccumulation and depuration of enteroviruses by the soft-shelled clam, Mya arenaria.

    PubMed Central

    Metcalf, T G; Mullin, B; Eckerson, D; Moulton, E; Larkin, E P

    1979-01-01

    Low levels of feces-associated natural virus, simulating virus numbers estimated to exist in moderately polluted shellfish-growing waters, were used to evaluate the effectiveness of depuration as a virus depletion procedure in soft-shell clams. Depuration effectiveness depended upon the numbers of virus bioaccumulated and whether virus was solids associated. Virus uptake was greatest when viruses were solids associated and pollution levels were equivalent or greater than those likely to be found in grossly polluted growing waters. Virtually all bioaccumulated feces-associated natural virus was deposited within either the hepatopancreas or siphon tissues. Viruses usually were eliminated within a 24- to 48-h depuration period. Dependence upon depuration of clams to elimate health hazards of virus etiology involved a risk factor not measureable in the study. The greatest reduction of health risks would come from the routine depuration of clams harvested from growing waters of good sanitary quality. PMID:229766

  14. Bioaccumulation and depuration of enteroviruses by the soft-shelled clam, Mya arenaria.

    PubMed

    Metcalf, T G; Mullin, B; Eckerson, D; Moulton, E; Larkin, E P

    1979-08-01

    Low levels of feces-associated natural virus, simulating virus numbers estimated to exist in moderately polluted shellfish-growing waters, were used to evaluate the effectiveness of depuration as a virus depletion procedure in soft-shell clams. Depuration effectiveness depended upon the numbers of virus bioaccumulated and whether virus was solids associated. Virus uptake was greatest when viruses were solids associated and pollution levels were equivalent or greater than those likely to be found in grossly polluted growing waters. Virtually all bioaccumulated feces-associated natural virus was deposited within either the hepatopancreas or siphon tissues. Viruses usually were eliminated within a 24- to 48-h depuration period. Dependence upon depuration of clams to elimate health hazards of virus etiology involved a risk factor not measureable in the study. The greatest reduction of health risks would come from the routine depuration of clams harvested from growing waters of good sanitary quality. PMID:229766

  15. Past daily light cycle recorded in the strontium/calcium ratios of giant clam shells.

    PubMed

    Sano, Yuji; Kobayashi, Sayumi; Shirai, Kotaro; Takahata, Naoto; Matsumoto, Katsumi; Watanabe, Tsuyoshi; Sowa, Kohki; Iwai, Kenji

    2012-01-01

    The historical record of daily light cycle in tropical and subtropical regions is short. Moreover, it remains difficult to extract this cycle in the past from natural archives such as biogenic marine carbonates. Here we describe the precise analysis of Sr/Ca, Mg/Ca, and Ba/Ca ratios in a cultivated giant clam shell, using a laterally high-resolution secondary ion mass spectrometer with 2??m resolution. The Sr/Ca ratio exhibits striking diurnal variations, reflecting the daily light cycle. A clear seasonal variation in Sr/Ca is also observed in another longer set of measurements with 50??m resolution. Light-enhanced calcification and elemental transportation processes, in giant clam and symbiotic algae, may explain these diurnal and annual variations. This opens the possibility to develop the Sr/Ca ratio from a giant clam shell as an effective proxy for parameters of the daily light cycle. PMID:22453834

  16. Responses of Manila clam growth and its food sources to global warming in a subarctic lagoon in Japan

    NASA Astrophysics Data System (ADS)

    Yoon, Seokjin; Abe, Hiroya; Kishi, Michio J.

    2013-12-01

    Akkeshi Lake is a subarctic shallow brackish lagoon located in Hokkaido, Japan. The Manila clam, Ruditapes philippinarum, is cultured in sandy sediments at the shallow, intertidal flat near the mouth of the lake. To quantitatively evaluate the effects of environmental factors such as water temperature and food availability on the growth of the Manila clam and to estimate the responses of Manila clam growth and food availability to global warming in Akkeshi Lake, we developed a numerical model by coupling a three-dimensional ecosystem model with a bioenergetics model for the growth of the Manila clam. We ran the model under two different conditions: the present condition and the global warming condition. For the global warming condition, water temperature was increased by 2 C at the open boundary for the entire computational period. The growth of the Manila clam was limited by water temperature and food availability. The Manila clam grew up to 1.33 g dry weight ind.-1 at the lake mouth (station A) for 5 years, whereas it grew up to 1.00 g dry weight ind.-1 at the lake center (station B). The difference in the biomass of the Manila clam between two stations was due to the difference in food availability. Under the global warming condition, the water temperature limitation for the Manila clam was relaxed with a water temperature increase. The Manila clam grew up to 1.55 g dry weight ind.-1 at station A and 1.10 g dry weight ind.-1 at station B. While the growth of the Manila clam was improved in the lake under the global warming condition, its food sources, especially phytoplankton, decreased because of ingestion increases of grazers.

  17. Evaluation of short-term exposure to heated water and chlorine for control of the Asiatic clam (Corbicula fluminea)

    SciTech Connect

    Mattice, J.S.; McLean, R.B.; Burch, M.B.

    1982-01-01

    Based on the need for development of efficient procedures for prevention or control of fouling by the Asiatic clam, Corbicula fluminea, the response of these clams to chlorine in combination with rapid increases in water temperature was examined. Small clams were acclimated to 10 and 25/sup 0/C, and large clams were acclimated to 25/sup 0/C. Experiments with each of these acclimation groups consisted of variables of total residual chlorine concentration (0, 5, 7.5, and 10 mg/L) and test temperature (ambient and 3 test temperatures ranging from 35 to 46/sup 0/C). The periods of exposure to increased temperature and chlorine were 40 and 30 min respectively. Clam mortalities were related to water temperature but not to chlorine exposure. At high temperatures at least 50% of the clams remained open through the entire chlorine exposure period. At higher temperatures all of the clams remained open. Even when clams remained open for the entire 30-min chlorine exposure period, all clams were not killed. However, virtually all clams exposed to 41 to 43/sup 0/C water temperatures were killed whether open or closed during the exposure period. Death due to temperature shock is the logical conclusion from these data. Combined application of heated water and chlorine at the concentrations used is not more effective in killing Corbicula than is heated water alone. Current regulations on the concentration of chlorine in power plant effluents indicate that further studies of control of Corbicula using chlorine offer little likelihood for success. (ERB)

  18. Direct contribution of clams (Ruditapes philippinarum) to benthic fluxes, nitrification, denitrification and nitrous oxide emission in a farmed sediment

    NASA Astrophysics Data System (ADS)

    Welsh, David T.; Nizzoli, Daniele; Fano, Elisa A.; Viaroli, Pierluigi

    2015-03-01

    The influence of the manila clam (Ruditapes philippinarum) on N-cycle processes, and oxygen and nutrient fluxes in a farmed sediment was investigated using a multiple core incubation approach and parallel incubations of individual clams. Clam population/biomass density varied ?8-fold between cores and all sediment-water column solute (O2. N2, N2O, NH4+, NOX and DIN) fluxes and benthic process (N-regeneration, nitrification and denitrification) rates were strongly and significantly correlated with clam density/biomass. Isolated clams exhibited high rates of respiration, N-excretion, nitrification and denitrification of 2050 70, 395 49, 201 42 and 235 40 nmol individual-1 h-1, respectively. The direct contribution of the clams and their associated microbiota to benthic processes was estimated by multiplying the per individual rates by the number of clams in each incubated core. The clams on average directly accounted for 64-133% of total rates of sediment oxygen demand, N-regeneration, nitrification and denitrification, indicating that they regulated processes primarily through their own metabolic activity and that of bacteria that colonise them. Clams and the farmed sediments were significant sources of the greenhouse gas N2O, but this was primarily due to their high nitrification and denitrification rates, rather than high specific N2O yields, as N2O emissions represented <1% of total N2O + N2 production. The clam-farmed sediments had a high denitrification efficiency of 67 10%, but this ecosystem service came at the environmental cost of increased N-regeneration and N2O emission rates. The measured N2O emissions indicate that bivalve aquaculture may be a significant source of N2O. It is therefore recommended that N2O emissions should be included in the impact assessments of current and future bivalve-farming projects.

  19. Transcriptional changes in Manila clam (Ruditapes philippinarum) inresponse to Brown Ring Disease.

    PubMed

    Allam, Bassem; Pales Espinosa, Emmanuelle; Tanguy, Arnaud; Jeffroy, Fanny; Le Bris, Cedric; Paillard, Christine

    2014-11-01

    Brown Ring Disease (BRD) is a bacterial infection affecting the economically-important clam Ruditapes philippinarum. The disease is caused by a bacterium, Vibrio tapetis, that colonizes the edge of the mantle, altering the biomineralization process and normal shell growth. Altered organic shell matrices accumulate on the inner face of the shell leading to the formation of the typical brown ring in the extrapallial space (between the mantle and the shell). Even though structural and functional changes have been described in solid (mantle) and fluid (hemolymph and extrapallial fluids) tissues from infected clams, the underlying molecular alterations and responses remain largely unknown. This study was designed to gather information on clam molecular responses to the disease and to compare focal responses at the site of the infection (mantle and extrapallial fluid) with systemic (hemolymph) responses. To do so, we designed and produced a Manila clam expression oligoarray (15K Agilent) using transcriptomic data available in public databases and used this platform to comparatively assess transcriptomic changes in mantle, hemolymph and extrapallial fluid of infected clams. Results showed significant regulation in diseased clams of molecules involved in pathogen recognition (e.g. lectins, C1q domain-containing proteins) and killing (defensin), apoptosis regulation (death-associated protein, bcl-2) and in biomineralization (shell matrix proteins, perlucin, galaxin, chitin- and calcium-binding proteins). While most changes in response to the disease were tissue-specific, systemic alterations included co-regulation in all 3 tested tissues of molecules involved in microbe recognition and killing (complement-related factors, defensin). These results provide a first glance at molecular alterations and responses caused by BRD and identify targets for future functional investigations. PMID:24882017

  20. Effects of salinity on hard clam (Mercenaria mercenaria) defense parameters and QPX disease dynamics.

    PubMed

    Perrigault, Mickael; Dahl, Soren F; Espinosa, Emmanuelle Pales; Allam, Bassem

    2012-05-01

    QPX (Quahog Parasite Unknown) is a protistan parasite affecting hard clams (Mercenaria mercenaria) along the Northeast coast of the United States. The fact that QPX disease epizootics are usually observed in field sites with high salinities led to the general assumption that salinity represents an important factor for disease distribution. This study was designed to investigate the effect of salinity on QPX disease development as well as constitutive and QPX-induced defense factors in M. mercenaria. Nave and QPX-infected (both experimentally and naturally) clams were submitted to 17 and 30 psu for 4 months. Standard and QPX-specific cellular and humoral defense parameters were assessed after 2 and 4 months. These included total and differential hemocyte counts, reactive oxygen species production, phagocytic activity of hemocytes, lysozyme concentration in plasma, anti-QPX activity in plasma and resistance of hemocytes to cytotoxic QPX extracellular products. Results demonstrated higher QPX-associated mortality in naturally infected clams maintained at high salinity compared to those held at 17 psu. Our findings also showed an increase in mortality following experimental challenge with QPX in clams submitted to 30 psu but not in those held at 17 psu. Constitutive clam defense factors and the response to QPX challenge were also affected by salinity. QPX challenge caused significant but transitory changes in hemolymph parameters that were obvious at 2 months but disappeared at 4 months. Overall, our results show that salinity modulates clam immunity and the progress of QPX disease although its impact appears secondary as compared to findings we reported earlier for temperature. PMID:22366664

  1. Microstructure and nanoindentation of the CLAM steel with nanocrystalline grains under Xe irradiation

    NASA Astrophysics Data System (ADS)

    Chang, Yongqin; Zhang, Jing; Li, Xiaolin; Guo, Qiang; Wan, Farong; Long, Yi

    2014-12-01

    This work presents an early look at irradiation effects on China low activation martensitic (CLAM) steel with nanocrystalline grains (NC-CLAM steels) under 500 keV Xe-ion bombardment at room temperature to doses up to 5.3 displacements per atom (dpa). The microstructure in the topmost region of the steel is composed of nanocrystalline grains with an average diameter of 13 nm. As the samples were implanted at low dose, the nanocrystalline grains had martensite lath structure, and many dislocations and high density bubbles were introduced into the NC-CLAM steels. As the irradiation dose up to 5.3 dpa, a tangled dislocation network exists in the lath region, and the size of the bubbles increases. X-ray diffraction results show that the crystal quality decreases after irradiation, although the nanocrystals obviously coarsen. Grain growth under irradiation may be ascribed to the direct impact of the thermal spike on grain boundaries in the NC-CLAM steels. In irradiated samples, a compressive stress exists in the surface layer because of grain growth and irradiation-introduced defects, while the irradiation introduced grain-size coarsening and defects gradients from the surface to matrix result in a tensile stress in the irradiated NC-CLAM steels. Nanoindentation was used to estimate changes in mechanical properties during irradiation, and the results show that the hardness of the NC-CLAM steels increases with increasing irradiation dose, which was ascribed to the competition between the grain boundaries and the irradiation-introduced defects.

  2. Infrared Colors of Dwarf-Dwarf Galaxy Interactions

    NASA Astrophysics Data System (ADS)

    Liss, Sandra; Stierwalt, Sabrina; Johnson, Kelsey; Patton, Dave; Kallivayalil, Nitya

    2015-10-01

    We request Spitzer Warm Mission IRAC Channel 1 & 2 imaging for a sample of 60 isolated dwarf galaxy pairs as a key component of a larger, multi-wavelength effort to understand the role low-mass mergers play in galaxy evolution. A systematic study of dwarf-dwarf mergers has never been done, and we wish to characterize the impact such interactions have on fueling star formation in the nearby universe. The Spitzer imaging proposed here will allow us to determine the extent to which the 3.6 and 4.5 mum bands are dominated by stellar light and investigate a) the extent to which interacting pairs show IR excess and b) whether the excess is related to the pair separation. Second, we will use this IR photometry to constrain the processes contributing to the observed color excess and scatter in each system. We will take advantage of the wealth of observations available in the Spitzer Heritage Archive for 'normal' non-interacting dwarfs by comparing the stellar populations of those dwarfs with the likely interacting dwarfs in our sample. Ultimately, we can combine the Spitzer imaging proposed here with our current, ongoing efforts to obtain groundbased optical photometry to model the star formation histories of these dwarfs and to help constrain the timescales and impact dwarf-dwarf mergers have on fueling star formation. The sensitivity and resolution offered by Spitzer are necessary to determine the dust properties of these interacting systems, and how these properties vary as a function of pair separation, mass ratio, and gas fraction.

  3. Synergistic Effect of Triple Ion Beams on Radiation Damage in CLAM Steel

    NASA Astrophysics Data System (ADS)

    Yuan, Da-Qing; Zheng, Yong-Nan; Zuo, Yi; Fan, Ping; Zhou, Dong-Mei; Zhang, Qiao-Li; Ma, Xiao-Qiang; Cui, Bao-Qun; Chen, Li-Hua; Jiang, Wei-Sheng; Wu, Yi-Can; Huang, Qun-Ying; Peng, Lei; Cao, Xing-Zhong; Wang, Bao-Yi; Wei, Long; Zhu, Sheng-Yun

    2014-04-01

    The synergistic effect of triple ion beams is investigated by simultaneous and sequential irradiations of gold, hydrogen and helium ions on the low activation martensitic steel (CLAM) developed in China. The depth profile measurements of the positron annihilation Doppler broadening S parameter are carried out as a function of slow-positron beam energy to examine the produced radiation damage. The synergistic effect of displacement damage and hydrogen and helium on the formation of radiation damage is clearly observed. In the preset case, this effect suppresses the radiation damage in the CLAM steel due to the helium and/or hydrogen filling of vacancy clusters.

  4. Accumulation and elimination of (9-/sup 14/C)phenanthrene in the calico clam (Macrocallista maculata)

    SciTech Connect

    Solbakken, J.E.; Jeffrey, F.M.H.; Knap, A.H.; Palmork, K.H.

    1982-05-01

    The accumulation and elimination of radoactivity is studied after exposure of (9-/sup 14/C) phenanthrene in various tissues in the calico clam (Macrocallista maculata). Results show that accumulation is highest in the lipid-rich hepatopancreas, and the elimination is very efficient compared to the horse mussel. The calico clam, which is a sand-dwelling organism, can easily come in contact with hydrocarbon contaminated sedments and might accumulate the hydrocarbons at different extents in various tissues. The efficient elimination, however, will prevent a lasting accumulation. (JMT)

  5. Observations of geese foraging for clam shells during spring on the Yukon-Kuskokwim Delta, Alaska

    USGS Publications Warehouse

    Flint, P.L.; Fowler, A.C.; Bottitta, G.E.; Schamber, J.

    1998-01-01

    We studied the behavior of geese on exposed river ice during spring on the Yukon-Kuskokwim Delta. The predominant behavior while on the ice for both sexes was foraging; however, females foraged more than males. Visual inspection of the ice revealed no potential plant or animal food items. However, numerous small (<20 man) clam shells (Macoma balthica) and pieces of shell were noted. It appeared that geese were foraging on empty clam shells. This potential source of calcium was available to breeding geese just prior to egg formation and geese likely stored this calcium in the form of medullary bone for use during egg formation.

  6. White Dwarf Stars

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Peering deep inside a cluster of several hundred thousand stars, NASA's Hubble Space Telescope has uncovered the oldest burned-out stars in our Milky Way Galaxy, giving astronomers a fresh reading on the age of the universe.

    Located in the globular cluster M4, these small, burned-out stars -- called white dwarfs -- are about 12 to 13 billion years old. By adding the one billion years it took the cluster to form after the Big Bang, astronomers found that the age of the white dwarfs agrees with previous estimates that the universe is 13 to 14 billion years old.

    The images, including some taken by Hubble's Wide Field and Planetary Camera 2, are available online at

    http://oposite.stsci.edu/pubinfo/pr/2002/10/ or

    http://www.jpl.nasa.gov/images/wfpc .

    The camera was designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif.

    In the top panel, a ground-based observatory snapped a panoramic view of the entire cluster, which contains several hundred thousand stars within a volume of 10 to 30 light-years across. The Kitt Peak National Observatory's .9-meter telescope took this picture in March 1995. The box at left indicates the region observed by the Hubble telescope.

    The Hubble telescope studied a small region of the cluster. A section of that region is seen in the picture at bottom left. A sampling of an even smaller region is shown at bottom right. This region is only about one light-year across. In this smaller region, Hubble pinpointed a number of faint white dwarfs. The blue circles indicate the dwarfs. It took nearly eight days of exposure time over a 67-day period to find these extremely faint stars.

    Globular clusters are among the oldest clusters of stars in the universe. The faintest and coolest white dwarfs within globular clusters can yield a globular cluster's age. Earlier Hubble observations showed that the first stars formed less than 1 billion years after the universe's birth in the big bang. So, finding the oldest stars puts astronomers within arm's reach of the universe's age.

    Hubble's Wide Field and Planetary Camera 2 made the observations from January through April 2001. These optical observations were combined to create the above images. Spectral data were also taken. M4 is 7,000 light-years away in the constellation Scorpius.

    The full press release on the latest findings is online at

    http://oposite.stsci.edu/pubinfo/pr/2002/10/pr.html .

    The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between the European Space Agency and NASA. The California Institute of Technology in Pasadena manages JPL for NASA.

  7. PROPERTIES OF THE COOLEST DWARFS

    SciTech Connect

    SAUMON, DIDIER; LEGGETT, SANDY K.; FREEDMAN, RICHARD S.; GEBALLE, THOMAS R.; GOLIMOWSKI, DAVID A.; LODIEU, NICOLAS; MARLEY, MARK S.; STEPHENS, DENISE; PINFIELD, DAVID J.; WARREN, STEPHEN J.

    2007-01-18

    Eleven years after the discovery of the first T dwarf, we have a population of ultracool L and T dwarfs that is large enough to show a range of atmospheric properties, as well as model atmospheres advanced enough to study these properties in detail. Since the last Cool Stars meeting, there have been observational developments which aid in these studies. they present recent mid-infrared photometry and spectroscopy from the Spitzer Space Telescope which confirms the prevalence of vertical mixing in the atmospheres of L and T dwarfs. Hence, the 700 K to 2200 K L and t dwarf photspheres require a large number of parameters for successful modeling: effective temperature, gravity, metallicity, grain sedimentation and vertical mixing efficiency. They also describe initial results of a search for ultracool dwarfs in the UKIRT Infrared Deep Sky Survey, and present the latest T dwarf found to date. They conclude with a discussion of the definition of the later-than-T spectral type, the Y dwarf.

  8. Behavior and Calibration of the Sr/Ca Temperature Proxy in Vesicomyid Clams

    NASA Astrophysics Data System (ADS)

    Hart, S. R.

    2009-12-01

    Clams of the Vesicomyidae family populate both hydrothermal vent areas and hydrocarbon cold seep areas. These habitats furnish reduced sulfides that support chemoautotrophic endosymbionts that nourish the clams. Clams of this family all grow aragonitic shells, and can have lifetimes that span many decades. The incorporation of Sr into aragonite in corals has a well-known temperature dependence and the same is true in clams, though the partitioning is reversed from that in corals. Thus the potential exists to use these clams to provide proxy temperatures for both hydrothermal and cold seep environments. Hart and Blusztajn (1998) used ion probe techniques for Sr/Ca analysis of several Calyptogena magnifica specimens from 10N on the East Pacific Rise. Sub-monthly resolution was obtained, and large Sr/Ca variations were observed that could be correlated with known eruptive and venting episodes. The preliminary temperature calibration we reported in 1998 was obtained from an Arctica icelandica (ocean quahog), recovered from a coastal site with a 6 year instrumental temperature record (1.3 - 17.7C). Because this species stops growing in the winter, the low temperature end of the calibration was uncertain. To refine this calibration, we report here Sr/Ca records from 3 cold seep localities (typically with 200+ analysis spots per clam): a Calyptogena ponderosa (Green Canyon, Gulf of Mexico, 720 m, ~ 6C); a C. phaseoliformis? (Aleutian trench, 4922 m, 1.5C); and paired C. pacifica and C. kilmeri (Monterey Canyon, 904 m, 4.2C). All of these samples exhibited significant Sr/Ca variations, suggesting that either the sites were not isothermal (as hoped), or that the clams were processing water with anomalous, pore-water-derived, Sr/Ca. Significant stretches of each record did have low and fairly constant Sr/Ca and, when coupled with the known ambient water temperatures for each locality, substantiated a calibration only ~ 1 higher than the 1998 calibration (new calibration: TC = 18160*(Sr/Ca) - 12.2). The C. kilmeri spent most of its early life at 9-12C, only dropping to ambient a year or so before collection in 1996. In contrast, the nearby C. pacifica spent most of its early life near ambient, with a rapidly increasing temperature over its last few years, reaching almost 20C just before collection in 1994. We also have determined detailed Sr/Ca records for 7 specimens of C. magnifica from a hydrothermal venting region at ~ 10N on the East Pacific Rise. These clams were collected in 1990, 1991, 1992, 1996, 1997, and 1999, and thus provide a time series with at least one known time for each clam. This was a period of active eruption and venting at this site, and the thermal episodes can be matched fairly well across the various clams. Sporadic low temperatures for these clams are in the 3-4C range, but large periods of their lives are spent in the 10-20C range, with short spikes to ~ 40C being common. We thank Colleen Cavanaugh, Lauren Mullineaux, Dan Fornari, Tim Shank, Rich Lutz, Jim Barry and Chuck Fisher for sharing their magnificent Vesicomyids.

  9. First Direct Evidence That Barium Dwarfs Have White Dwarf Companions

    NASA Astrophysics Data System (ADS)

    Gray, R. O.; McGahee, C. E.; Griffin, R. E. M.; Corbally, C. J.

    2011-05-01

    Barium II (Ba) stars are chemically peculiar F-, G-, and K-type objects that show enhanced abundances of s-process elements. Since s-process nucleosynthesis is unlikely to take place in stars prior to the advanced asymptotic giant branch (AGB) stage, the prevailing hypothesis is that each present Ba star was contaminated by an AGB companion which is now a white dwarf (WD). Unless the initial mass ratio of such a binary was fairly close to unity, the receiving star is thus at least as likely to be a dwarf as a giant. So although most known Ba stars appear to be giants, the hypothesis requires that Ba dwarfs be comparably plentiful and moreover that they should all have WD companions. However, despite dedicated searches with the IUE satellite, no WD companions have been directly detected to date among the classical Ba dwarfs, even though some 90% of those stars are spectroscopic binaries, so the contamination hypothesis is therefore presently in some jeopardy. In this paper, we analyze recent deep, near-UV and far-UV Galaxy Evolution Explorer (GALEX) exposures of four of the brightest of the class (HD 2454, 15360, 26367, and 221531), together with archived GALEX data for two newly recognized Ba dwarfs: HD 34654 and HD 114520 (which also prove to be spectroscopic binaries). The GALEX observations of the Ba dwarfs as a group show a significant far-UV excess compared to a control sample of normal F-type dwarfs. We suggest that this ensemble far-UV excess constitutes the first direct evidence that Ba dwarfs have WD companions.

  10. FIRST DIRECT EVIDENCE THAT BARIUM DWARFS HAVE WHITE DWARF COMPANIONS

    SciTech Connect

    Gray, R. O.; McGahee, C. E.; Griffin, R. E. M.; Corbally, C. J. E-mail: cmcgahe@g.clemson.edu E-mail: corbally@as.arizona.edu

    2011-05-15

    Barium II (Ba) stars are chemically peculiar F-, G-, and K-type objects that show enhanced abundances of s-process elements. Since s-process nucleosynthesis is unlikely to take place in stars prior to the advanced asymptotic giant branch (AGB) stage, the prevailing hypothesis is that each present Ba star was contaminated by an AGB companion which is now a white dwarf (WD). Unless the initial mass ratio of such a binary was fairly close to unity, the receiving star is thus at least as likely to be a dwarf as a giant. So although most known Ba stars appear to be giants, the hypothesis requires that Ba dwarfs be comparably plentiful and moreover that they should all have WD companions. However, despite dedicated searches with the IUE satellite, no WD companions have been directly detected to date among the classical Ba dwarfs, even though some 90% of those stars are spectroscopic binaries, so the contamination hypothesis is therefore presently in some jeopardy. In this paper, we analyze recent deep, near-UV and far-UV Galaxy Evolution Explorer (GALEX) exposures of four of the brightest of the class (HD 2454, 15360, 26367, and 221531), together with archived GALEX data for two newly recognized Ba dwarfs: HD 34654 and HD 114520 (which also prove to be spectroscopic binaries). The GALEX observations of the Ba dwarfs as a group show a significant far-UV excess compared to a control sample of normal F-type dwarfs. We suggest that this ensemble far-UV excess constitutes the first direct evidence that Ba dwarfs have WD companions.

  11. Metabolomic analysis revealed the differential responses in two pedigrees of clam Ruditapes philippinarum towards Vibrio harveyi challenge.

    PubMed

    Liu, Xiaoli; Zhao, Jianmin; Wu, Huifeng; Wang, Qing

    2013-12-01

    Manila clam Ruditapes philippinarum is an important marine aquaculture shellfish. This species has several pedigrees including White, Zebra, Liangdao Red and Marine Red distributing in the coastal areas in North China. In this work, we studied the metabolic differences induced by Vibrio harveyi in hepatopancreas from White and Zebra clams using NMR-based metabolomics. Metabolic responses (e.g., amino acids, glucose, glycogen, ATP and succinate) and altered mRNA expression levels of related genes (ATP synthase, heat shock protein 90, defensin and lysozyme) suggested that V. harveyi induced clear disruption in energy metabolism and immune stresses in both White and Zebra clam hepatopancreas. However, V. harveyi caused obvious osmotic stress in Zebra clam hepatopancreas, which was not observed in V. harveyi-challenged White clams samples. In addition, V. harveyi challenge induced more severe disruption in energy metabolism and immune stress in White clams than in Zebra clams. Overall, our results indicated that the biological differences between different pedigrees of R. philippinarum should be considered in immunity studies. PMID:24161758

  12. Species profiles: Life histories and environmental requirements of coastal fish and invertebrates (North Atlantic): Softshell clam. [Mya arenaria

    SciTech Connect

    Newell, C.R.; Hidu, H.

    1986-06-01

    The softshell clam, Mya arenaria, is a commercially and recreationally important invertebrate that inhabits the bottom sediments of subtidal and intertidal waters of moderate to high salinity. Its range is limited by water temperatures too low for reproduction in the north and by lethal warm temperatures in the south. Clams feed by siphoning seawater and removing food particles, especially phytoplankton, with their gills. Clams are therefore sensitive to factors affecting water quality, including suspended sediments, salinity, water temperature, oxygen, and waterborne pollutants. The clam life cycle consists of mass spawning and external fertilization, the development of pelagic larvae, settlement and metamorphosis into spat, and rapid juvenile growth to maturity. Clam recruitment and the migration of spat are dependent upon inshore currents. High morality of eggs, larvae, and spat is largely offset by high reproductive potential. As the clam grows, it finds refuge from most predators deep in the sediments, but it also loses its ability to burrow and is subject to suffocation by siltation. Sediment types, currents, and tidal heights all affect clam growth rates.

  13. Ichthyoplankton in a southern african surf zone: Nursery area for the postlarvae of estuarine associated fish species?

    NASA Astrophysics Data System (ADS)

    Whitfield, A. K.

    1989-12-01

    The surf zone ichthyoplankton of Swartvlei Bay was studied between February 1986 and June 1987, with particular emphasis on its potential role as a nursery area for estuarine associated marine fish species. Larvae and/or postlarvae of 16 families were identified from the surf zone, with the Gobiidae, Soleidae, Sparidae and Mugilidae comprising 85·7% of all teleosts sampled. The postlarvae of several taxa (including the six most common species), which utilize the Swartvlei estuary as a juvenile nursery area, were abundant in the surf zone. Conversely, species which are common in nearshore marine waters as juveniles and adults, but seldom enter estuaries, totalled less than 8% of the surf zone ichthyoplankton assemblage. Larval and postlarval densities peaked during summer when water temperatures exceeded 19°C and the estuary mouth was open. Concentrations of ichthyoplankton were highest at those sampling stations closest to the estuary mouth during the summer period. Diel changes in total catches revealed no significant difference between day and night densities; but of the four major taxa, the Mugilidae and Sparidae tended to be more abundant during the day, the Gobiidae at night and the Soleidae showed no distinct pattern. Results from a 24 h sampling session indicated that tidal phase may also be important in governing ichthyoplankton abundance in the surf zone.

  14. White Dwarf Pulsars

    NASA Technical Reports Server (NTRS)

    Patterson, Joseph

    1998-01-01

    Work on NAG5-3288 ("White Dwarf Pulsars") has been fully integrated with the identically titled project NAG5-4734. The final report below is the same, since the data analysis and interpretative work are integrated, as are the resulting (previous and in-pipeline) publications. The proposal was designed to study pulse and orbital modulations in candidate DQ Herculis stars. Data on 5 stars were obtained. The best results were obtained on YY Draconis, which exhibited a strongly pulsed hard X-ray flux, and even suggested a transition between one-pole and two-pole emission during the course of the observation. This result is being readied for inclusion in a comprehensive study of YY Draconis. A strong pulsation appeared to be present also in H0857-242, but with a period of - 50 minutes, confusion with the first harmonic of the satellite's orbital frequency is possible. So that result is uncertain and is "on ice". A negative result was obtained on 4UO608-49 (V347 Pup), suggesting either that the X-ray identification is incorrect, or that the source is very transient. Finally, data was obtained on V1432 Aql and WZ Sge, respectively the slowest and fastest of these stars. Combined with the ASCA data, the high-energy data demonstrates the latter to contain a white dwarf rotating with P = 27.87 s (Patterson et al. 1998, PASP, 110, 403). Optical photometry contemporaneous with the X-ray data was obtained of V1432 Aql, in order to study the variations in the eclipse waveform. As anticipated, the width and centroid of the eclipse appeared to vary with the 50-day "supercycle".

  15. AirMISR Red Band Browse Images from the CLAMS_2001 Field Campaign

    Atmospheric Science Data Center

    2013-04-04

    AirMISR Red Band Browse Images from the CLAMS_2001 Field Campaign July 12, 2001 July 12, 2001 Browse Images Run # BF (45.6 fore) camera only ... July 17, 2001 July 17, 2001 Browse Images Run # BF (45.6 fore) camera only ...

  16. The Quiet Clam Is Quite Calm: Transposed-Letter Neighborhood Effects on Eye Movements during Reading

    ERIC Educational Resources Information Center

    Johnson, Rebecca L.

    2009-01-01

    In responses time tasks, inhibitory neighborhood effects have been found for word pairs that differ in a transposition of two adjacent letters (e.g., "clam/calm"). Here, the author describes two eye-tracking experiments conducted to explore transposed-letter (TL) neighborhood effects within the context of normal silent reading. In Experiment 1,

  17. 50 CFR 17.45 - Special rules-snails and clams. [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 2 2011-10-01 2011-10-01 false Special rules-snails and clams. 17.45 Section 17.45 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR... WILDLIFE AND PLANTS (CONTINUED) ENDANGERED AND THREATENED WILDLIFE AND PLANTS Threatened Wildlife §...

  18. Cadmium sulfide quantum dots induce oxidative stress and behavioral impairments in the marine clam Scrobicularia plana.

    PubMed

    Buffet, Pierre-Emmanuel; Zalouk-Vergnoux, Aurore; Poirier, Laurence; Lopes, Christelle; Risso-de-Faverney, Christine; Guibbolini, Marielle; Gilliland, Douglas; Perrein-Ettajani, Hanane; Valsami-Jones, Eugenia; Mouneyrac, Catherine

    2015-07-01

    Cadmium sulfide (CdS) quantum dots have a number of current applications in electronics and solar cells and significant future potential in medicine. The aim of the present study was to examine the toxic effects of CdS quantum dots on the marine clam Scrobicularia plana exposed for 14 d to these nanomaterials (10 µg Cd L(-1) ) in natural seawater and to compare them with soluble Cd. Measurement of labile Cd released from CdS quantum dots showed that 52% of CdS quantum dots remained in the nanoparticulate form. Clams accumulated the same levels of Cd regardless of the form in which it was delivered (soluble Cd vs CdS quantum dots). However, significant changes in biochemical responses were observed in clams exposed to CdS quantum dots compared with soluble Cd. Increased activities of catalase and glutathione-S-transferase were significantly higher in clams exposed in seawater to Cd as the nanoparticulate versus the soluble form, suggesting a specific nano effect. The behavior of S. plana in sediment showed impairments of foot movements only in the case of exposure to CdS quantum dots. The results show that oxidative stress and behavior biomarkers are sensitive predictors of CdS quantum dots toxicity in S. plana. Such responses, appearing well before changes might occur at the population level, demonstrate the usefulness of this model species and type of biomarker in the assessment of nanoparticle contamination in estuarine ecosystems. PMID:25772261

  19. BENZO(A)PYRENE ACCUMULATION AND DEPURATION IN THE SOFT-SHELL CLAM ('MYA ARENARIA')

    EPA Science Inventory

    Three hundred clams were placed in sediment in a continuous flow seawater tank between March and June. The tank was dosed with 14C labeled benzo(a)pyrene in no. 2 fuel oil daily. Animals were removed weekly and assayed for accumulation of the radioactive material. On the sixth, t...

  20. TOXICITY EVALUATION OF A COMPLEX METAL MIXTURE TO THE SOFTSHELL CLAM 'MYA ARENARIA'

    EPA Science Inventory

    Adults of the softshell clam Mya arenaria were continuously subjected to a flowing raw seawater solution containing a mixture of salts of manganese, zinc, lead, nickel, copper, and cadmium. Final calculated concentrations, in micrograms per liter of the toxicant solution were 720...

  1. Uptake of trace metals by the clam Macoma inquinata from clean and oil-contaminated detritus

    SciTech Connect

    Crecelius, E.A.; Augenfeld, J.M.; Woodruff, D.L.; Anderson, J.W.

    1980-09-01

    In recent years there has been increasing concern about the entry of petroleum hydrocarbon (PHC) into the marine environment and the effects of such entry on the composition and functioning of the marine ecosystem. Few reports have been published on the possible effect of oil on the uptake of metals from water or sediments by animals. The possibility of such effects is indicated by the work of Fletcher et al. (1979), who showed that crude oil causes a reduction in blood plasma copper concentrations in fish, and Payne et al. (1978) who reported that petroleum affected chloride regulation in fish. Luoma and Jenne (1977) have shown that the availability of sediment-bound metals to a deposit-feeding clam depended on the metal-sediment associated and sediment-to-water desorption rate. We exposed a detritivorous clam, Macoma inquinata, to clean and oil-contaminated detritus to determine the effects of the oil on metal accumulation. To measure the uptake of metals, clams were exposed to neutron activated detritus and the uptake of several isotopes (/sup 51/Cr, /sup 60/Co, /sup 152/Eu, /sup 59/Fe, /sup 46/Sc, and /sup 65/Zn) measured in the clams.

  2. ACUTE TOXICITIES OF SELECTED HEAVY METALS TO THE SOFTSHELL CLAM, 'MYA ARENARIA'

    EPA Science Inventory

    Static acute toxicity bioassays with adult softshell clams and salts of copper, cadmium, zinc, lead, manganese, and nickel were conducted at 30 o/oo salinity and 22C. Concentrations fatal to 50% in 168 hours, in mg/l (ppm) metal added at start, were 0.035 for Cu, 0.150 for Cd, 1....

  3. DETERMINATION OF THE VENTILATION RATES OF INTERSTITIAL AND OVERLYING WATER BY THE CLAM MACOMA NASUTA

    EPA Science Inventory

    The ventilation rates of interstitial and overlying water for the deposit-feeding, tellinid clam Macoma nasuta (Conrad) were determined using two water-soluble dyes to differentiate between the two water sources. nique exposure chamber, the clambox, was used to separate the inhal...

  4. Epizootiology and distribution of transmissible sarcoma in Maryland softshell clams, Mya arenaria, 1984-1988.

    PubMed Central

    Farley, C A; Plutschak, D L; Scott, R F

    1991-01-01

    Seasonal and geographic studies of transmissible sarcoma in Maryland softshell clams, Mya arenaria, were carried out from 1984 to 1988. Three major epizootics occurred in our sampling location during this time, resulting in prevalences as high as 90%, with comparable mortalities in other high prevalence areas. The disease invaded populations of large adult clams first, later spreading to the small juvenile clam populations. An apparent 2-year cycle was noted with varying seasonal effects. Affected sites tended to be in the main stem of Chesapeake Bay north of Tangier Sound, primarily in the areas where the major harvesting occurs. Several sites, mostly in upstream locations, were consistently free of disease. The epizootiological study supports the interpretation that the disease is infectious exclusively to this species. Regression analysis between sarcoma prevalence and contaminant levels in clam tissues showed a significant correlation (p = 0.0001) between chlordane levels and this disease. No correlations were found with other contaminants that were analyzed. Images FIGURE 1. PMID:2050081

  5. Soft-shell clam, Mya arenaria, a convenient laboratory animal for screening pathogens of bivalve mollusks.

    PubMed

    Tubiash, H S

    1971-09-01

    Attempts to introduce infectious or foreign material into oysters and other bivalve mollusks usually involve force or trauma because of immediate, prolonged adduction of the tightly closing valves. The soft-shell clam, Mya arenaria, is unable to seal its valves completely and relaxes readily, exposing soft tissue and a large siphon. This species is free from fouling organisms and is readily available at all seasons in the New England and mid-Atlantic areas. Suspensions of five strains of Vibrio sp. that cause bacillary necrosis in larval and juvenile bivalve mollusks were injected into the heart, siphon tissue, and the incurrent and excurrent siphon lumina of soft-shell clams. All vibrio strains caused significant mortality, usually within 2 days. Heaviest losses resulted from heart and excurrent siphon injections. No mortality occurred in control clams injected with seawater, broth, Serratia sp., and Escherichia coli. The soft-shell clam appears to be a useful animal for testing the pathogenicity of marine microorganisms for bivalve mollusks. PMID:4940871

  6. Oxygen, sulphide and nutrient uptake of the mangrove mud clam Anodontia edentula (Family: Lucinidae).

    PubMed

    Lebata, M J

    2001-11-01

    Oxygen, sulphide and nutrient (ammonia, nitrite and phosphate) uptake of Anodontia edentula was measured. Oxygen and sulphide were measured from sealed containers provided with 1 l fresh mangrove mud (sulphide source) and seawater (oxygen source) with two treatments (with and without clam) at 16 replicates each. Oxygen, sulphide and other parameters were measured at days 1 (initial), 3 and 5 (final). Nutrients were measured from containers filled with 1.5 l wastewater from a milkfish broodstock tank with two treatments (with and without clam) at eight replicates each. Ammonia, NO2 and P04 were measured at days 0 (initial) 3, 6, 9 and 12 (final). Results showed significantly decreasing oxygen and sulphide concentrations in treatment with clams (ANOVA, p < 0.001). A significantly higher ammonia concentration (ANOVA, p < 0.05) was observed in treatment with clams while no significant difference was observed in nitrite and phosphate between the two treatments. A decreasing ammonia and an increasing nitrite trend was also observed in both treatments starting at day 3. PMID:11763226

  7. SUBLETHAL EFFECTS OF CHRONIC OIL EXPOSURE ON THE INTERTIDAL CLAM 'MACOMA BALTHICA'

    EPA Science Inventory

    When exposed to Prudhoe Bay crude oil in flowing seawater for 180 days, the small intertidal clam Macoma balthica showed behavioral, physical, physiological and biochemical changes. At a high concentration of oil in seawater (3.0 mg per l) burrowing rate decreased, respiration ra...

  8. White Dwarf Pulsations in LSST

    NASA Astrophysics Data System (ADS)

    Bell, Keaton J.; Claver, Chuck F.; Krughoff, K. Simon; Montgomery, M. H.; Mukadam, Anjum S.; Winget, D. E.

    2015-06-01

    The Large Synoptic Survey Telescope (LSST) is projected to begin full science operations in 2023. It will photometrically observe roughly 13 million white dwarfs in the southern sky to a single-visit depth of r = 24.5, obtaining parallax, proper motion, and 6-filter color measurements. Perhaps most excitingly, LSST will revisit every field 1000 times over its 10-year operation, holding massive potential for variable white dwarf science. We highlight the beginning steps in our work to test LSST's sensitivity to constrain various aspects of pulsations throughout the multi-parameter color-space of every white dwarf instability regime. We anticipate detecting variability in tens of thousands of white dwarf pulsators through the survey lifetime.

  9. The imbalanced surfing-life of humanity to survival in the global changes

    NASA Astrophysics Data System (ADS)

    Kontar, V. A.

    2013-12-01

    We have written many times about the imbalance of Nature as the cause of the global change. Here, we offer some method for the humanity survival in the face of global change of the imbalanced anisotropic real Nature. There are two logics of understanding the real Nature: the traditional balanced, and the new imbalanced. The balanced logic presupposes that Nature is balanced, isotropic, etc. The imbalanced logic presupposes opposite that Nature is imbalanced, anisotropic, etc. Respectively can be two styles of the people life: balanced and imbalanced. The image of the flat earth corresponds well with the balanced lifestyle of people. On the balanced life people spend activities to achieve the balance by reducing the change, stabilization, leveling any level changes, etc. If there is a mountain on the road, it must be align the track or make the tunnel. If there is a ravine on the road, then it need backfilled or to build a bridge. If someone is in restless, it must be calm, etc. As example of the happiness in the balanced life is the stability, balance, and therefore the global changes of Nature are perceived as a catastrophe. In the balanced lifestyle people can easily decide to use force, especially if there is not enough knowledge. But Nature has power which in billions times greater than the forces of humanity. Therefore, humanity will beaten in struggle with Nature and disappear. The imbalanced lifestyle is the fundamentally different. The imbalanced lifestyle complies with the surface of the ocean, which always changes, but sometimes can be and flat. But the flat calm ocean surface is inconvenient for the imbalanced life. You need to pull boat yourself because is no wind in the sails. The anisotropic imbalanced Nature has gradients in all parameters. At a certain level of knowledge and experience, people can use this multi-dimensional gradient essence of the real Nature for human's discretion. The imbalanced life is like a surfing. If properly understood Nature, you can find a route slip through the waves of Nature, which will bring closer the person to the desired goals. Of course, the changeable ocean is much more complicated than a flat surface. The imbalanced logic also is much more complex than the simplified balanced logic. As the calm ocean is like the flat surface, so same the balanced logic solutions are sometimes looks like as the truth, but only in the calm weather. At the normal ocean weather the balanced solutions are incorrect and mislead people. The river can be as image of the imbalanced surfing life. The river starts as small stream and running through all the obstacles to ocean. The water of river is flowing at the bottom of the potential trench of the Earth gravity and the Coriolis acceleration. For the imbalanced surfing life is most important not a steamroller of force, but the knowledge and perseverance in the search for the best path to the desirable goals. The example of happiness in the surfing imbalanced life can be joy from successfully usage the suitable trends of the anisotropic imbalanced real Nature. At the imbalanced surfing life should be the main guide: Nature doesn't have the bad weather. The global changes it is not catastrophe, but the normal state of the real anisotropic imbalanced Nature. Just everybody has to choose the weather which will be good for their personal surfing.

  10. Characterization of brevetoxin metabolism in Karenia brevis bloom-exposed clams (Mercenaria sp.) by LC-MS/MS.

    PubMed

    Abraham, Ann; Wang, Yuesong; El Said, Kathleen R; Plakas, Steven M

    2012-11-01

    Brevetoxin metabolites were identified and characterized in the hard clam (Mercenaria sp.) after natural exposure to Karenia brevis blooms by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Principal brevetoxins BTX-1 and BTX-2 produced by K. brevis were not detectable in clams. Metabolites of these brevetoxins found in clams included products of oxidation, reduction, hydrolysis and amino acid/fatty acid conjugation. Of highest abundance were cysteine and taurine conjugates. We also found glutathione, glycine-cysteine, and γ-glutamyl-cysteine conjugates. A series of fatty acid derivatives of cysteine-brevetoxin conjugates were also identified. PMID:22884629

  11. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Pacific Southwest): Common littleneck clam. [Protothaca staminea

    SciTech Connect

    Shaw, W.N.

    1986-04-01

    Common littleneck clam (Protothaca staminea) supports an important sport fishery in the Pacific Southwest Region, but has no commercial importance. The species is distributed from Alaska to Baja, California. The egg develops into the trochophore stage 12 h after fertilization, and the planktonic larval stage lasts about 3 weeks. Adults usually mature in the second or third year of life. Mortality is greatest early in life. Intraspecific competition among adults is more evident in mud than in sand. Most littleneck clams live in the lower intertidal zone. Littleneck clams concentrate heavy metals and are highly sensitive to copper.

  12. Prediction and assimilation of surf-zone processes using a Bayesian network: Part I: Forward models

    USGS Publications Warehouse

    Plant, Nathaniel G.; Holland, K. Todd

    2011-01-01

    Prediction of coastal processes, including waves, currents, and sediment transport, can be obtained from a variety of detailed geophysical-process models with many simulations showing significant skill. This capability supports a wide range of research and applied efforts that can benefit from accurate numerical predictions. However, the predictions are only as accurate as the data used to drive the models and, given the large temporal and spatial variability of the surf zone, inaccuracies in data are unavoidable such that useful predictions require corresponding estimates of uncertainty. We demonstrate how a Bayesian-network model can be used to provide accurate predictions of wave-height evolution in the surf zone given very sparse and/or inaccurate boundary-condition data. The approach is based on a formal treatment of a data-assimilation problem that takes advantage of significant reduction of the dimensionality of the model system. We demonstrate that predictions of a detailed geophysical model of the wave evolution are reproduced accurately using a Bayesian approach. In this surf-zone application, forward prediction skill was 83%, and uncertainties in the model inputs were accurately transferred to uncertainty in output variables. We also demonstrate that if modeling uncertainties were not conveyed to the Bayesian network (i.e., perfect data or model were assumed), then overly optimistic prediction uncertainties were computed. More consistent predictions and uncertainties were obtained by including model-parameter errors as a source of input uncertainty. Improved predictions (skill of 90%) were achieved because the Bayesian network simultaneously estimated optimal parameters while predicting wave heights.

  13. Fish Communities in the Surf Zone of a Protected Sandy Beach at Doigahama, Yamaguchi Prefecture, Japan

    NASA Astrophysics Data System (ADS)

    Suda, Y.; Inoue, T.; Uchida, H.

    2002-07-01

    Fish communities comprising postlarval to early adult stages were studied in the surf zone of a protected sandy beach, with runnels and a low tide terrace, at Doigahama, Yamaguchi Prefecture, western Japan. One elasmobranch and 100 teleost species, represented by a total of 17 608 individuals (1·85-785 mm in TL), were collected by fine and coarse meshed beach seines from May 1994 to April 1999. Species richness, abundance and biomass were greater during the evenings as well as in the warmer seasons (May to October). Larval and smaller juvenile ichthyofauna (collected mainly by fine-mesh seine) was relatively poor compared to larger juvenile ichthyofauna (coarse-mesh seine). Tidal effect was observed in the fine-mesh seine samples, whereas no tide-related trends were evident in the coarse-mesh seine samples. Effects of time of the day and tide on the species diversities were not so evident in both seines. Dominant species were classified according to the developmental stages occurring in the surf zone, as follows: Type-I: Postlarval (transformation) stage (Plecoglossus altivelis altivelis,Sardinops melanostictus , Enneapterygius etheostomus, Tripterygion bapturum, Luciogobius sp.). Type-II: Juvenile stage (Lateolabrax latus, Trachurus japonicus, Gerres oyena, Acanthopagrus schlegeli, Sparus sarba, Girella punctata, Mugil cephalus cephalus, Paralichthys olivaceus, Tarphops oligolepis, Heteromycteris japonica). Type-III: Postlarval and juvenile stages (Spratelloides gracilis, Engraulis japonicus, Gobiidae sp.1). Type-IV: Juvenile and early adult stages (Sillago japonica, Paraplagusia japonica). Type V: Postlarval to early adult stages (Takifugu niphobles). It is considered that the surf zone at Doigahama functions as a nursery area, particularly as a feeding place for larger juveniles than as a shelter for larvae and smaller juveniles.

  14. Modeling surf zone hydrodynamics and sediment transport - toward an integrated approach

    NASA Astrophysics Data System (ADS)

    Hsu, T.; Raubenheimer, B.; Trowbridge, J.; Cox, D.; Hanes, D.

    2006-12-01

    The pioneering work on surf zone processes conducted by E. B. Thornton and his collaborators in the early 80s has inspired numerous subsequent field, laboratory and modeling studies. In this paper, we evaluate wave- phase resolving models for surf zone hydrodynamics and sediment transport by comparing the predictions with field and prototype-scale wave flume data. In particular, a model based on the Reynolds-Averaged Navier-Stokes equations and the volume of fluid method for free-surface tracking (COBRAS, Lin and Liu 1998, J. Fluid Mech. 359, p239-264) is extended with a higher-order time-integration numerical scheme. The extended model is numerically stable, and simulates the surf zone wave heights, undertow, and mean water levels measured during the SwashX field experiment (conducted in fall 2000 near La Jolla, CA) reasonably well when driven with the measured offshore random wave time series. A two-phase model (Hsu et al. 2004, Proc. Royal Soc. Lond. A, 460, p2223-2250) for massive particles that has been extended to calculate sand transport is shown to simulate sand concentrations in both the concentrated and dilute regimes measured under non-breaking wave groups during the SISTEX99 prototype flume experiment (Dohmen- Janssen and Hanes 2005, Cont. Shelf Res., 25, 333-347). By driving the two-phase model with near-bed flow velocities and turbulent kinetic energies (due to surface-generated turbulence in breaking waves) measured during the CROSSTEX prototype flume experiment (conducted in summer 2005 at the O. H. Hinsdale laboratory, Oregon State University), it is shown that the bottom boundary layer sediment transport can be influenced significantly by breaking wave generated turbulence, consistent with measured data.

  15. On the importance of nearbed sediment flux measurements for estimating sediment transport in the surf zone

    NASA Astrophysics Data System (ADS)

    Ogston, Andrea S.; Sternberg, Richard W.

    1995-11-01

    Previous sediment studies in the surf zone typically have computed suspended sediment flux profiles by pairing a single current meter measurement at an elevation of 20 cm or more with measurements of suspended sediment concentration from sensor arrays located at 4-50 cm elevation. This note reports the results of a field experiment in which small impellor current meters were paired with OBS sensors at common elevations of 4, 9 and 19 cm from the bed and across the inner surf zone to obtain concurrent velocity and concentration profiles. The objectives of this experiment were to measure suspended sediment flux profiles within 20 cm of the seabed to determine the magnitude of flux very close to the seabed in comparison to measurements at higher elevation; and to evaluate the errors associated with estimating sediment flux using current meter measurements at only one elevation compared to flux estimates based on velocity profile measurements. Results show that the total sediment flux at z = 4 cm was greater than the flux higher in the water column ( z = 9 and 19 cm) by a factor of at least 2. The flux profiles computed using a single impellor current meter at z = 19 cm and OBS sensors at z = 4, 9 and 19 cm typically were between 0.5 and 2.0 times the flux profiles computed using paired instruments. In one case the estimate of flux direction from the single current meter data predicted transport in the wrong cross shore direction. These results highlight the importance of nearbed measurements of concentration and velocity in estimating sediment transport in the surf zone.

  16. Airborne Spectral Measurements of Ocean Anisotropy during CLAMS

    NASA Technical Reports Server (NTRS)

    Gatebe, C. K.; King, M. D.; Arnold, G. T.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    The Cloud Absorption Radiometer (CAR) aboard the University of Washington Convair CV-580 research aircraft obtained bidirectional reflectance-distribution function (BRDF) of Atlantic Ocean and Dismal Swamp between July 10 and August 2, 2001. The BRDF measurements (15 in total, 8 uncontaminated by clouds) obtained under a variety of sun angles and wind conditions, will be used to characterize ocean anisotropy in support of Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) science objectives principally to validate products from NASA's EOS satellites, and to parameterize and validate BRDF models of the ocean. In this paper we present results of BRDF of the Ocean under different sun angles and wind conditions. The CAR is capable of measuring scattered light in fourteen spectral bands. The scan mirror, rotating at 100 rpm, directs the light into a Dall-Kirkham telescope where the beam is split into nine paths. Eight light beams pass through beam splitters, dichroics, and lenses to individual detectors (0.34-1.27 micron), and finally are registered by eight data channels. They are sampled simultaneously and continuously. The ninth beam passes through a spinning filter wheel to an InSb detector cooled by a Stirling cycle cooler. Signals registered by the ninth data channel are selected from among six spectral channels (1.55-2.30 micron). The filter wheel can either cycle through all six spectral bands at a prescribed interval (usually changing filter every fifth scan line), or lock onto any one of the six spectral bands and sample it continuously. To measure the BRF of the surface-atmosphere system, the University of Washington CV-580 had to fly in a circle about 3 km in diameter above the surface for roughly two minutes. Replicated observations (multiple circular orbits) were acquired over selected surfaces so that average BRF smooth out small-scale surface and atmospheric inhomogeneities. At an altitude of 600 m above the targeted surface area and with a 1 degree IFOV, the pixel resolution is about 10 m at nadir and about 270 m at an 80 deg. viewing angle from the CAR.

  17. Chemical Signatures in Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Venn, Kim A.; Hill, Vanessa M.

    2008-12-01

    Chemical signatures in dwarf galaxies describe the examination of specific elemental abundance ratios to investigate the formation and evolution of dwarf galaxies, particularly when compared with the variety of stellar populations in the Galaxy. Abundance ratios can come from HII region emission lines, planetary nebulae, or supernova remnants, but mostly they come from stars. Since stars can live a very long time, for example, a 0.8 MSun star born at the time of the Big Bang would only now be ascending the red giant branch, and, if, for the most part, its quiescent main sequence lifetime had been uneventful, then it is possible that the surface chemistry of stars actually still resembles their natal chemistry. Detailed abundances of stars in dwarf galaxies can be used to reconstruct their chemical evolution, which we now find to be distinct from any other component of the Galaxy, questioning the assertion that dwarf galaxies like these built up the Galaxy. Potential solutions to reconciling dwarf galaxy abundances and Galaxy formation models include the timescale for significant merging and the possibility for uncovering different stellar populations in the new ultra-faint dwarfs.

  18. Gyrosolitons and helical surfing diffusion of impurity atoms in reactor fuel materials

    NASA Astrophysics Data System (ADS)

    Dubovsky, O. A.; Semenov, V. A.; Orlov, A. V.

    2015-08-01

    Fundamentally new gyrosolitons with helical trajectories of motion have been revealed in UO2 and PuO2 reactor fuel materials by the computer simulation of the microdynamics of high-amplitude atomic vibrations. The phonon spectra of nanostructures, as well as of gyrotropic materials, include quasioptical branches with different-sign linear dispersion. The corresponding branches of gyrosolitons have been revealed on the phase plane in the spectral density of vibrations. The main dynamic event of the kinetic process of helical surfing diffusion of impurity atoms on gyrosolitons has been observed.

  19. Internal waves and surf zone water quality at Huntington Beach, California

    NASA Astrophysics Data System (ADS)

    Wong, H.; Santoro, A.; Nidzieko, N. J.; Hench, J. L.; Boehm, A. B.

    2011-12-01

    This study characterized diurnal, semi-diurnal, and high-frequency internal wave field at Huntington Beach, California, USA and the connection between internal waves and surf zone water quality. An array of oceanographic moorings was deployed in the summer of 2005 and 2006 at 10-20 meter depths offshore of the beach to observe internal waves and cross-shore exchange. Concurrently, surf zone water quality was assessed twice daily at an adjacent station (Huntington State Beach) with measurements of phosphate, dissolved inorganic nitrogen, silicate, chlorophyll a, fecal indicator bacteria, and the human-specific fecal DNA marker in Bacteroidales. Spectral analysis of water temperature shows well-defined spectral peaks at diurnal and semi-diurnal frequencies. Complex Empirical Orthogonal Function analysis of observed currents reveals that the baroclinic component (summation of second to fifth principal components) accounted for 30% of the total variance in the currents in both years, indicating the importance of density-driven flow during the summer when the water column was stratified. The major axis of the first principal component was oriented alongshore, whereas that of the second and third principal components made an angle of 25 to 55 degree with the cross-shore direction. Arrival of cold subthermocline water in the very near shore (within 1 km of the surf zone) was characterized by strong onshore flow near the bottom of the water column. The near bottom, baroclinic, cross-shore current was significantly lag-correlated with the near bottom temperature data along a cross-shore transect towards shore, indicative of shoreward transport of cold subthermocline water. Wavelet analysis of temperature data showed that non-stationary temperature fluctuations were correlated with buoyancy frequency and the near bottom cross-shore baroclinic current. During periods of large temperature fluctuations, the majority of the variance was within the semi-diurnal band; however, the diurnal and high frequency bands also contained a substantial fraction of total variance. The bottom cross-shore baroclinic current served as a proxy for shoreward internal wave propagation and was positively correlated with phosphate concentration in both years, silicate in 2005, and fecal indicator bacteria measurements in 2006. The results suggest internal waves are an important transport mechanism of nutrient-rich sub-thermocline water to the very near shore in the Southern California Bight, and may facilitate the transport of FIB into the surf zone or enhance persistence of land-derived FIB.

  20. Germinomas and teratoid siphon anomalies in softshell clams, Mya arenaria, environmentally exposed to herbicides.

    PubMed Central

    Gardner, G R; Yevich, P P; Hurst, J; Thayer, P; Benyi, S; Harshbarger, J C; Pruell, R J

    1991-01-01

    Seminomas and dysgerminomas are epizootic in softshell clams, Mya arenaria, from three Maine estuaries contaminated with herbicides. The first epizootic was discovered in 22% of clams collected as Searsport near Long Cove Brook and three culverts that conveyed heating oil and jet fuel spilled from a tank farm in 1971. Data from subsequent epizootiological studies and a series of long-term experimental exposures of softshell clams to no. 2 fuel oil, JP-4, and JP-5 jet fuel at the U.S. EPA, Environmental Research Laboratory in Narragansett, Rhode Island, and in the field did not support an etiology by these petroleum products. In the two recent epizootics reported here, the germinomas have been observed in 3% of the softshell clams collected from Roque Bluffs near Machiasport and from 35% of softshell clams collected from Dennysville. Mya collected at Dennysville had pericardial mesotheliomas and teratoid siphon anomalies in addition to gonadal neoplasms. Estuaries at Dennysville had been contaminated by herbicides in a 1979 accidental spray overdrift during aerial application of Tordon 101 to adjacent forests. Further investigation determined widespread use of the herbicides Tordon 101, 2,4-D,2,4,5-T, and other agrochemicals in an extensive forestry and blueberry industry in both the Roque Bluffs and the Dennysville areas. Herbicide applications at Searsport were confirmed for railroad property bordering Long Cove estuary and for Long Cove Brook adjacent to the estuary where a highway department reportedly cleans its spray equipment. Herbicide contamination is the only common denominator identified at all three sites where Mya have been found with gonadal neoplasms.(ABSTRACT TRUNCATED AT 250 WORDS) Images FIGURE 5. FIGURE 6. PMID:2050082

  1. Transcriptome sequencing and microarray development for the Manila clam, Ruditapes philippinarum: genomic tools for environmental monitoring

    PubMed Central

    2011-01-01

    Background The Manila clam, Ruditapes philippinarum, is one of the major aquaculture species in the world and a potential sentinel organism for monitoring the status of marine ecosystems. However, genomic resources for R. philippinarum are still extremely limited. Global analysis of gene expression profiles is increasingly used to evaluate the biological effects of various environmental stressors on aquatic animals under either artificial conditions or in the wild. Here, we report on the development of a transcriptomic platform for global gene expression profiling in the Manila clam. Results A normalized cDNA library representing a mixture of adult tissues was sequenced using a ultra high-throughput sequencing technology (Roche 454). A database consisting of 32,606 unique transcripts was constructed, 9,747 (30%) of which could be annotated by similarity. An oligo-DNA microarray platform was designed and applied to profile gene expression of digestive gland and gills. Functional annotation of differentially expressed genes between different tissues was performed by enrichment analysis. Expression of Natural Antisense Transcripts (NAT) analysis was also performed and bi-directional transcription appears a common phenomenon in the R. philippinarum transcriptome. A preliminary study on clam samples collected in a highly polluted area of the Venice Lagoon demonstrated the applicability of genomic tools to environmental monitoring. Conclusions The transcriptomic platform developed for the Manila clam confirmed the high level of reproducibility of current microarray technology. Next-generation sequencing provided a good representation of the clam transcriptome. Despite the known limitations in transcript annotation and sequence coverage for non model species, sufficient information was obtained to identify a large set of genes potentially involved in cellular response to environmental stress. PMID:21569398

  2. Characterization of a domoic acid binding site from Pacific razor clam.

    PubMed

    Trainer, Vera L; Bill, Brian D

    2004-08-10

    The Pacific razor clam, Siliqua patula, is known to retain domoic acid, a water-soluble glutamate receptor agonist produced by diatoms of the genus Pseudo-nitzschia. The mechanism by which razor clams tolerate high levels of the toxin, domoic acid, in their tissues while still retaining normal nerve function is unknown. In our study, a domoic acid binding site was solubilized from razor clam siphon using a combination of Triton X-100 and digitonin. In a Scatchard analysis using [3H]kainic acid, the partially-purified membrane showed two distinct receptor sites, a high affinity, low capacity site with a KD (mean +/- S.E.) of 28 +/- 9.4 nM and a maximal binding capacity of 12 +/- 3.8 pmol/mg protein and a low affinity, high capacity site with a mM affinity for radiolabeled kainic acid, the latter site which was lost upon solubilization. Competition experiments showed that the rank order potency for competitive ligands in displacing [3H]kainate binding from the membrane-bound receptors was quisqualate > ibotenate > iodowillardiine = AMPA = fluorowillardiine > domoate > kainate > L-glutamate. At high micromolar concentrations, NBQX, NMDA and ATPA showed little or no ability to displace [3H]kainate. In contrast, Scatchard analysis using [3H]glutamate showed linearity, indicating the presence of a single binding site with a KD and Bmax of 500 +/- 50 nM and 14 +/- 0.8 pmol/mg protein, respectively. These results suggest that razor clam siphon contains both a high and low affinity receptor site for kainic acid and may contain more than one subtype of glutamate receptor, thereby allowing the clam to function normally in a marine environment that often contains high concentrations of domoic acid. PMID:15261449

  3. Germinomas and teratoid siphon anomalies in softshell clams, Mya arenaria, environmentally exposed to herbicides.

    PubMed

    Gardner, G R; Yevich, P P; Hurst, J; Thayer, P; Benyi, S; Harshbarger, J C; Pruell, R J

    1991-01-01

    Seminomas and dysgerminomas are epizootic in softshell clams, Mya arenaria, from three Maine estuaries contaminated with herbicides. The first epizootic was discovered in 22% of clams collected as Searsport near Long Cove Brook and three culverts that conveyed heating oil and jet fuel spilled from a tank farm in 1971. Data from subsequent epizootiological studies and a series of long-term experimental exposures of softshell clams to no. 2 fuel oil, JP-4, and JP-5 jet fuel at the U.S. EPA, Environmental Research Laboratory in Narragansett, Rhode Island, and in the field did not support an etiology by these petroleum products. In the two recent epizootics reported here, the germinomas have been observed in 3% of the softshell clams collected from Roque Bluffs near Machiasport and from 35% of softshell clams collected from Dennysville. Mya collected at Dennysville had pericardial mesotheliomas and teratoid siphon anomalies in addition to gonadal neoplasms. Estuaries at Dennysville had been contaminated by herbicides in a 1979 accidental spray overdrift during aerial application of Tordon 101 to adjacent forests. Further investigation determined widespread use of the herbicides Tordon 101, 2,4-D,2,4,5-T, and other agrochemicals in an extensive forestry and blueberry industry in both the Roque Bluffs and the Dennysville areas. Herbicide applications at Searsport were confirmed for railroad property bordering Long Cove estuary and for Long Cove Brook adjacent to the estuary where a highway department reportedly cleans its spray equipment. Herbicide contamination is the only common denominator identified at all three sites where Mya have been found with gonadal neoplasms.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2050082

  4. Exploring the effects of seasonality and chemical pollution on the hepatopancreas transcriptome of the Manila clam.

    PubMed

    Milan, Massimo; Ferraresso, Serena; Ciofi, Claudio; Chelazzi, Guido; Carrer, Claudio; Ferrari, Giorgio; Pavan, Lino; Patarnello, Tomaso; Bargelloni, Luca

    2013-04-01

    The assessment of marine environmental health is a complex but fundamental task both for ecosystem conservation and food safety related to the human consumption of marine products. Manila clams inhabiting the Venice Lagoon constitute an excellent case study for evaluating the effects of complex mixtures of industrial and urban effluents on aquatic organisms. Clams were collected in different seasons at four locations within the Venice Lagoon. The sampling sites were characterized by a range of pollutant concentrations and included Porto Marghera, a highly polluted industrial area where clam harvesting for human consumption is strictly forbidden. Pooled soft tissues were subjected to mass spectroscopy analysis to measure the concentrations of PCDDs/PCDFs/PCBs-DL, PCBs, PBDEs, HCB and PAHs, and pooled digestive gland samples were used for gene expression profiling. While seasonal variation was found to be responsible for the largest proportion of transcriptional changes, significance analysis of microarrays quantitative correlation analysis identified 162 transcripts that were correlated with at least one class of chemicals measured in the samples from the four different sampling sites. Prediction Analysis of Microarrays (PAM) identified a minimal set of seven genes that correctly assigned samples collected in the restricted polluted area (Porto Marghera), independent of the season in which they were collected. An integrated approach combining transcriptomics and chemical analyses of the Manila clam provided a global picture of how Manila clams respond to complex mixtures of xenobiotics and their interplay with other biotic and abiotic factors. We were also able to identify gene expression signatures for different classes of chemicals and a set of robust biomarkers of exposure to these chemicals. PMID:23480613

  5. Light and electron microscopy characteristics of the muscle of patients with SURF1 gene mutations associated with Leigh disease

    PubMed Central

    Pronicki, M; Matyja, E; Piekutowska-Abramczuk, D; Szyma?ska-D?bi?ska, T; Karkuci?ska-Wi?ckowska, A; Karczmarewicz, E; Grajkowska, W; Kmie?, T; Popowska, E; Sykut-Cegielska, J

    2008-01-01

    Aims: Leigh syndrome (LS) is characterised by almost identical brain changes despite considerable causal heterogeneity. SURF1 gene mutations are among the most frequent causes of LS. Although deficiency of cytochrome c oxidase (COX) is a typical feature of the muscle in SURF1-deficient LS, other abnormalities have been rarely described. The aim of the present work is to assess the skeletal muscle morphology coexisting with SURF1 mutations from our own research and in the literature. Methods: Muscle samples from 21 patients who fulfilled the criteria of LS and SURF1 mutations (14 homozygotes and 7 heterozygotes of c.841delCT) were examined by light and electron microscopy. Results: Diffuse decreased activity or total deficit of COX was revealed histochemically in all examined muscles. No ragged red fibres (RRFs) were seen. Lipid accumulation and fibre size variability were found in 14 and 9 specimens, respectively. Ultrastructural assessment showed several mitochondrial abnormalities, lipid deposits, myofibrillar disorganisation and other minor changes. In five cases no ultrastructural changes were found. Apart from slight correlation between lipid accumulation shown by histochemical and ultrastructural techniques, no other correlations were revealed between parameters investigated, especially between severity of morphological changes and the patients age at the biopsy. Conclusion: Histological and histochemical features of muscle of genetically homogenous SURF1-deficient LS were reproducible in detection of COX deficit. Minor muscle changes were not commonly present. Also, ultrastructural abnormalities were not a consistent feature. It should be emphasised that SURF1-deficient muscle assessed in the light and electron microscopy panel may be interpreted as normal if COX staining is not employed. PMID:17908801

  6. Carbon stars in the Carina dwarf galaxy

    NASA Astrophysics Data System (ADS)

    Cannon, R. D.

    Recently obtained data on carbon stars in the Carina dwarf spheroidal galaxy are discussed. The discovery of these carbon stars is reviewed, and their existence in the Carina dwarf is explained in terms of either the galaxy being much younger than the globular clusters or Carina undergoing a very major episode of star formation much more recently. The situation in the Carina dwarf is compared to that obtaining in other dwarf galaxies, and the use of the dwarf galaxies to understand the origin and evolutionary status of the carbon stars themselves is discussed. Finally, the use of the carbon dwarf spheroidals to determine the radial velocities of these distant systems is considered.

  7. Shell-armored wood cobbles as a potential criterion for detrital coal deposits

    SciTech Connect

    DiMarco, M.J.; Nummedal, D.

    1986-01-01

    Shell-armored wood cobbles occur on detrital-peat beaches along the seaward edge of the Mississippi Delta. Shell material consists exclusively of Mulinia lateralis, a dwarf surf clam. Soft, heavy, waterlogged wood fragments are abraded and become armored by hard shells in response to wave activity on the beach. Although their preservation potential is suspect, fossilized shell-armored wood clasts would probably be recognized as a type of coal ball and might indicate an allochthonous origin for the host coal.

  8. Habitats used by black and surf scoters in eastern North America as determined by satellite radio telemetry

    USGS Publications Warehouse

    Perry, M.C.; Kidwell, D.M.; Wells-Berlin, A. M.; Lohnes, E.J.R.; Olsen, G.H.; Osenton, P.C.

    2005-01-01

    Satellite radio telemetry was used to determine the movements and habitats of black scoters (Melanitta nigra) and surf scoters (Melanitta perspicillata) in eastern North America. A total of 21 surf scoters were instrumented during five years (2001-05) and 32 black scoters were instrumented during three years (2002-04) with implanted PTT 100 satellite transmitters (39 g) with external antenna. Nesting habitat of black scoters was more open than surf scoters (44% vs. 11%), whereas nesting habitat for surf scoters was located in more forested areas (66% vs. 20%). Locations of black scoters in breeding areas on average were at significantly higher latitude and lower elevations than sites used by surf scoters. Satellite telemetry determined that James Bay was the major molting area for male black and surf scoters, although some males molted along the coast of Labrador-Newfoundland. Black scoters instrumented on the Restigouche River, which is a major staging area, were widely distributed along the Atlantic Coast from Cape Cod to Georgia during winter. Major wintering areas for black scoters were Cape Cod (Martha's Vineyard and Nantucket Island), Long Island, and New Jersey. In these northern marine wintering areas, black scoters were located farther from shore (4.2 km) and in deeper water (8.3 m) than black scoters in more southern estuarine areas, where distance from shore was 3.1 km and water depth was 5.2 m. Surf scoters instrumented in Chesapeake Bay in late winter showed a strong tendency to return to the Bay the following winter after they had migrated to and from breeding areas. In Chesapeake Bay, black scoters and surf scoters were located mostly in mesohaline areas that had similar water depths (5.1 m vs. 7.5 m) and distances from shore (3.0 km vs. 2.9 km). Distance from shore and depth of water increased over time during the winter for both species. Updated information from the ARGOS Systems aboard the NOAA satellites on scoter movements was made accessible on the Patuxent Website.

  9. Cohort life tables for a population of the soft-shell clam, Mya arenaria L., in the White Sea

    NASA Astrophysics Data System (ADS)

    Gerasimova, Alexandra V.; Maximovich, Nikolay V.; Filippova, Nadezhda A.

    2015-06-01

    The Mya arenaria generation in the White Sea was observed for almost the whole life cycle (around 25 years). Using the data on this generation dynamics, the cohort life table was built. The main purpose of the research is analysis of age-specific mortality in this soft-shell clam population. The mortality rate was found to change more than tenfold throughout the study period. No regular changes in its value were observed. Periods of low mortality alternated with periods of much higher mortality. Several reasons for the increase in M. arenaria mortality rate during its life cycle are proposed: (a) living in the surface sediment layer at early stages of life cycle (unstable environment, high mortality of non-viable clams, predator impact); (b) intense intraspecific relationships in dense aggregations of young clams; (c) increased intraspecific competition during periods of the rapid individual growth; (d) ageing (clam mortality increases with older ageachievement of an average and a maximum lifespan).

  10. Intersex in the clam Scrobicularia plana (Da Costa): Widespread occurrence in English Channel estuaries and surrounding areas.

    PubMed

    Pope, N D; Childs, K; Dang, C; Davey, M S; O'Hara, S C M; Langston, K; Minier, C; Pascoe, P L; Shortridge, E; Langston, W J

    2015-06-30

    Estuarine clams Scrobicularia plana were sampled from 108 intertidal locations around the English Channel and adjacent areas. Although S. plana is believed to be a strict gonochorist, 58% of the populations sampled included intersexed individuals (described as male clams exhibiting ovotestis). Over the entire region, on average, 8.6% of male clams exhibited intersex, although proportions of affected males ranged from 0% to 53% depending on location. The severity of intersex was assessed using a simple classification scale, with the majority of individuals showing low levels of impact. Sex ratios were significantly skewed at some sites. There were no significant relationships between incidence or severity of intersex; or with size or parasitism of individual clams. Intersex in S. plana is a useful tool to assess endocrine disruptive effects in estuaries, although mechanisms of impact and causative agents remain uncertain. PMID:25837773

  11. A comparison of heavy metal concentrations and health assessment in Asian clams Corbicula fluminea from Florida and North Carolina.

    PubMed

    Lewbart, Gregory A; Christian, Larry S; Harms, Craig A; Van Wettere, Arnaud J

    2010-06-01

    The Asian clam Corbicula fluminea was introduced into the United States in 1938 and has since become established in much of the country. This invasive species can compete with native bivalves and compromise industrial water supply systems and power plants. Numerous studies have examined bivalves as bioindicators. The purpose of this study was to compare the heavy metal concentrations of the hard and soft tissues of specimens from Florida and North Carolina and to assess the clams' health by microscopic examination of their soft tissues. Although the sample size was small, this study suggests that the Asian clams from the watersheds examined are healthy and that they accumulate lower levels of heavy metals than have been reported for clams from other, more polluted aquatic environments. PMID:20848880

  12. Comparison of impact forces, accelerations and ankle range of motion in surfing-related landing tasks.

    PubMed

    Lundgren, Lina E; Tran, Tai T; Nimphius, Sophia; Raymond, Ellen; Secomb, Josh L; Farley, Oliver R L; Newton, Robert U; Sheppard, Jeremy M

    2016-06-01

    This study aimed to describe the impact forces, accelerations and ankle range of motion in five different landing tasks that are used in training and testing for competitive surfing athletes, to assist coaches in the prescription of landing task progression and monitoring training load. Eleven competitive surfing athletes aged 24 ± 7 years participated, and inertial motion sensors were fixed to the anterior aspect of the feet, mid-tibial shafts, sacrum and eighth thoracic vertebrae on these athletes. Three tasks were performed landing on force plates and two tasks in a modified gymnastics set-up used for land-based aerial training. Peak landing force, resultant peak acceleration and front and rear side ankle dorsiflexion ranges of motion during landing were determined. The peak acceleration was approximately 50% higher when performing aerial training using a mini-trampoline and landing on a soft-density foam board, compared to a similar landing off a 50 cm box. Furthermore, the ankle ranges of motion during the gymnastic type landings were significantly lower than the other landing types (P ≤ 0.05 and P ≤ 0.001), for front and rear sides, respectively. Conclusively, increased task complexity and specificity of the sport increased the tibial peak acceleration, indicating greater training load. PMID:26383823

  13. SURF imaging: in vivo demonstration of an ultrasound contrast agent detection technique.

    PubMed

    Masoy, S E; Standal, O; Nasholm, P; Johansen, T F; Angelsen, Bjorn; Hansen, Rune

    2008-05-01

    A dual-band method for ultrasound contrast agent detection is demonstrated in vivo in an animal experiment using pigs. The method is named Second -order UltRasound Field Imaging, abbreviated SURF Imaging. It relies on simultaneously transmitting two ultrasound pulses with a large separation in frequency. Here, a low-frequency pulse of 0.9 MHz is combined with a high-frequency pulse of 7.5 MHz. The low-frequency pulse is used to manipulate the properties of the contrast agent, and the high frequency pulse is used for high-resolution contrast detection and imaging. An annular array capable of transmitting the low- and high-frequency pulses simultaneously was constructed and fitted to a mechanically scanned probe used in a GE Vingmed System 5 ultrasound scanner. The scanner was modified and adapted for the dual-band transmit technique. In-house software was written for post-processing of recorded IQ-data. Contrast-processed B-mode images of pig kidneys after bolus injections of 1 mL of Sonovuer are presented. The images display contrast detection with contrast-to-tissue ratios ranging from 15-40 dB. The results demonstrate the potential of SURF Imaging as an ultrasound contrast detection technique for clinically high ultrasound frequencies. This may allow ultrasound contrast imaging to be available for a wide range of applications. PMID:18519219

  14. Longitudinal instability studies at the SURF II storage ring at NIST.

    SciTech Connect

    Harkay, K.C.; Sereno, N.S.

    1998-08-27

    Measurements of the longitudinal instability observed in the storage ring at the Synchrotrons Ultraviolet Radiation Facility (SURF II) at the National Institute of Standards and Technology (NET) were performed to understand the mechanism driving the instability. The instability, studied in depth by Ralcowsky and others, manifests itself in broad resonance features in the horizontal and vertical motion spectrum of the synchrotrons light from DC to a few kHz. Also observed are multiple synchrotrons harmonics that modulate the revolution harmonics; these are characteristic of longitudinal phase oscillations. These spectral features of the motion are found to be correlated with the periodic lengthening and shortening of the bunch length on time scales from {approximately}0.1 ms to 20 ms, depending on machine and radio-frequency (rf) system parameters. In this report, the growth rate of the instability is determined from measurements using an rf pickup electrode. The measured growth rates are compared to computed growth rates from an analytical model. Recommendations are made regarding options to control or mitigate the instability. In light of upgrade plans for SURF III, a few comments are presented about the beam lifetime.

  15. Overview of research at NBS using synchrotron radiation at SURF-II

    SciTech Connect

    Ederer, D. L.; Madden, R. P.; Parr, A. C.; Rakowsky, G.; Saloman, E. B.; Copper, J.; Stockbauer, Roger; Madey, T. E.; Dehmer, Joseph L.

    1982-11-01

    The National Bureau of Standards (NBS) Synchrotron Ultraviolet Radiation Facility (SURF-II) is used in conjunction with several high throughput monochromators to study the interaction of vacuum ultraviolet photons with solids and gases. Recent work has been concerned with the photon stimulated desorption of atomic and molecular ions from surfaces, with the effect of electric fields on molecular photoabsorption and with the study of molecular photoionization by angle resolved photoelectron spectroscopy. These research programs yield new information about molecular bonding at surfaces, molecular dynamics near ionization thresholds, and the coupling of the electronic and nuclear motion near resonances in molecules. In addition to these programs in basic research SURF-II is used for the calibration of transfer standard detectors over a photon energy range 20 to 250 eV. Calibration of monochromator systems is achieved over the photon energy range 5 to 250 eV by using the now calculable spectral intensity radiated by the electrons, which are confined in a nearly circular orbit.

  16. On the impact of an offshore bathymetric anomaly on surf zone rip channels

    NASA Astrophysics Data System (ADS)

    Castelle, B.; Marieu, V.; Coco, G.; Bonneton, P.; Bruneau, N.; Ruessink, B. G.

    2012-03-01

    We use a nonlinear morphodynamic model to demonstrate that the presence of a single persistent offshore bathymetric anomaly strongly affects the formation, nonlinear evolution and saturation of surf zone rip channels. In the case of an offshore bump or trough and waves with oblique incidence, a rip channel shoreward of the anomaly is enforced by the more seaward alongshore variability in depth. The degree of rip channel enforcement is controlled by the strength of the rotational nature of surf zone rip current circulations, which is, in turn, driven by differential broken wave energy dissipation induced by wave refraction across the offshore bathymetric anomaly. The alongshore location of this forced rip channel is more stable with increasing offshore anomaly amplitude, decreasing offshore wave obliquity and decreasing bathymetric anomaly distance to the shore. Simulations show that rip channel behavior downdrift and updrift of the offshore perturbation are different. In our numerical experiments, downdrift rip channels have systematically larger alongshore scales, smaller alongshore migration rates and more erosive megacusps than those updrift. Rip channels therefore self-organize into patterns of different alongshore scales and migration rates as a result of an alongshore perturbation in the wave forcing enforced by wave refraction across an offshore bathymetric anomaly. These simulations are qualitatively corroborated by video observations of sandbar behavior during a down-state sequence at a site with a persistent offshore trough.

  17. Modeling and analyzing observed transverse sand bars in the surf zone

    NASA Astrophysics Data System (ADS)

    Ribas, F.; de Swart, H. E.; Calvete, D.; Falqus, A.

    2012-06-01

    A morphodynamic model has been applied to explain the characteristics of transverse sandbars observed in the inner surf zone of open beaches. The model describes the feedback between waves, rollers, depth-averaged currents and bed evolution, so that self-organized processes can develop. The modeled bar characteristics, i.e. wavelength (30-70 m), crest orientation (up-current) and the e-folding growth time (about 12 hr) are in good agreement with those of observed transverse bars at Noordwijk beach, the Netherlands, but modeled migration speeds (tens of meters per day), turn out to be a factor 2 larger than those observed. The wavelength increases with the distance between the shoreline and the peak of the longshore current and the migration speed is correlated with the maximum longshore current. The model also explains why transverse bar formation at Noordwijk occurs for obliquely incident waves of intermediate heights. Realistic positive feedback leading to formation of up-current oriented bars like those observed is only obtained if a term related to the turbulence sediment resuspension created by the rollers is included in the transport formula. In that case, the depth-averaged sediment concentration decreases seaward across the inner surf zone, enhancing the convergence of sediment transport in the offshore directed flow perturbations that occur over the up-current bars. This offshore current deflection is mainly caused by frictional torques, but the roller radiation stresses also play an important role.

  18. The Web-Surf Task: A translational model of human decision-making.

    PubMed

    Abram, Samantha V; Breton, Yannick-Andr; Schmidt, Brandy; Redish, A David; MacDonald, Angus W

    2016-02-01

    Animal models of decision-making are some of the most highly regarded psychological process models; however, there remains a disconnection between how these models are used for pre-clinical applications and the resulting treatment outcomes. This may be due to untested assumptions that different species recruit the same neural or psychological mechanisms. We propose a novel human foraging paradigm (Web-Surf Task) that we translated from a rat foraging paradigm (Restaurant Row) to evaluate cross-species decision-making similarities. We examined behavioral parallels in human and non-human animals using the respective tasks. We also compared two variants of the human task, one using videos and the other using photos as rewards, by correlating revealed and stated preferences. We demonstrate similarities in choice behaviors and decision reaction times in human and rat subjects. Findings also indicate that videos yielded more reliable and valid results. The joint use of the Web-Surf Task and Restaurant Row is therefore a promising approach for functional translational research, aiming to bridge pre-clinical and clinical lines of research using analogous tasks. PMID:26377334

  19. MOD_FreeSurf2D: A MATLAB surface fluid flow model for rivers and streams

    NASA Astrophysics Data System (ADS)

    Martin, Nick; Gorelick, Steven M.

    2005-08-01

    MOD_FreeSurf2D is an open source MATLAB code that simulates fluid velocities and depths in rivers and streams. Although this model was designed for a specific purpose, MOD_FreeSurf2D can be employed in general scenarios when the depth-averaged, shallow water equations apply. The model approximates the depth-averaged, shallow water equations with a finite volume, semi-implicit, semi-Lagrangian representation. This numerical solution method provides accuracy and stability when using model time steps that exceed the Courant-Friedrichs-Lewy (CFL) restriction. An additional benefit of the numerical representation is the ability to simulate moving land/water boundaries. Model results were shown to be accurate when compared to published data from a dam-break experiment in a 21 m flume and from velocity and depth measurements along a 400 m river reach in Idaho. Results from the dam-break experiment simulations demonstrate the model's ability to simulate wetting and drying. Additionally, sensitivity analyses conducted on the two scenarios show model convergence and demonstrate that the model can employ time steps that exceed the CFL restriction.

  20. Robust and Effective Component-based Banknote Recognition by SURF Features

    PubMed Central

    Hasanuzzaman, Faiz M.; Yang, Xiaodong; Tian, YingLi

    2013-01-01

    Camera-based computer vision technology is able to assist visually impaired people to automatically recognize banknotes. A good banknote recognition algorithm for blind or visually impaired people should have the following features: 1) 100% accuracy, and 2) robustness to various conditions in different environments and occlusions. Most existing algorithms of banknote recognition are limited to work for restricted conditions. In this paper we propose a component-based framework for banknote recognition by using Speeded Up Robust Features (SURF). The component-based framework is effective in collecting more class-specific information and robust in dealing with partial occlusion and viewpoint changes. Furthermore, the evaluation of SURF demonstrates its effectiveness in handling background noise, image rotation, scale, and illumination changes. To authenticate the robustness and generalizability of the proposed approach, we have collected a large dataset of banknotes from a variety of conditions including occlusion, cluttered background, rotation, and changes of illumination, scaling, and viewpoints. The proposed algorithm achieves 100% recognition rate on our challenging dataset. PMID:25531008

  1. A model for the generation of two-dimensional surf beat

    USGS Publications Warehouse

    List, Jeffrey H.

    1992-01-01

    A finite difference model predicting group-forced long waves in the nearshore is constructed with two interacting parts: an incident wave model providing time-varying radiation stress gradients across the nearshore, and a long-wave model which solves the equations of motion for the forcing imposed by the incident waves. Both shallow water group-bound long waves and long waves generated by a time-varying breakpoint are simulated. Model-generated time series are used to calculate the cross correlation between wave groups and long waves through the surf zone. The cross-correlation signal first observed by Tucker (1950) is well predicted. For the first time, this signal is decomposed into the contributions from the two mechanisms of leaky mode forcing. Results show that the cross-correlation signal can be explained by bound long waves which are amplified, though strongly modified, through the surf zone before reflection from the shoreline. The breakpoint-forced long waves are added to the bound long waves at a phase of pi/2 and are a secondary contribution owing to their relatively small size.

  2. Annual variations of biogenic element contents of manila clam ( Ruditapes philippinarum) bottom-cultivated in Jiaozhou Bay, China

    NASA Astrophysics Data System (ADS)

    Zan, Xiaoxiao; Xu, Binduo; Zhang, Chongliang; Ren, Yiping

    2014-08-01

    Manila clam ( Ruditapes philippinarum) was monthly sampled from its benthic aquaculture area in Jiaozhou Bay from May 2009 to June 2010. The annual variations of major elemental composition, organic content, fatness and element ratio of Manila clam were examined. The element removal effect of clam farming in Jiaozhou Bay was analyzed based on natural mortality and clam harvest. The results indicated that the variation trend of carbon content in shell ( C shell) was similar to that in clam ( C clam). Such a variation was higher in summer and autumn than in other seasons, which ranged from 9.10 0.13 to 10.38 0.09 mmol g-1 and from 11.28 0.29 to 12.36 0.06 mmol g-1, respectively. Carbon content of flesh ( C flesh) showed an opposite variation trend to that of shell in most months, varying from 29.42 0.05 to 33.64 0.62 mmol g-1. Nitrogen content of shell ( N shell) and flesh ( N flesh) changed seasonally, which was relatively low in spring and summer. N shell and N flesh varied from 0.07 0.009 to 0.14 0.009 mmol g-1 and from 5.46 0.12 to 7.39 0.43 mmol g-1, respectively. Total nitrogen content of clam ranged from 0.50 0.003 to 0.76 0.10 mmol g-1 with a falling tend except for a high value in March 2010. Phosphorus content of clam ( N clam) fluctuated largely, while phosphorus content of shell ( P shell) was less varied than that of flesh ( P flesh). P shell varied from 0.006 0.001 to 0.016 0.001 mmol g-1; while P flesh fluctuated between 0.058 0.017 and 0.293 0.029 mmol g-1. P clam ranged from 0.015 0.002 to 0.041 0.006 mmol g-1. Carbon and nitrogen content were slightly affected by shell length, width or height. Elemental contents were closely related to the reproduction cycle. The removal amounts of carbon, nitrogen and phosphorus from clam harvest and natural death in Jiaozhou Bay were 2.92104t, 1420 t and 145 t, respectively. The nutrient removal may aid to reduce the concentrations of nitrogen and phosphorus, the main causes of eutrophication, and to maintain the ecosystem health of Jiaozhou Bay.

  3. Effect of cooling rates and temperatures on quality and safety of quahog clams (Mercenaria mercenaria).

    PubMed

    Granata, Linda Ankenman; Bourne, Dianne Wall; Flick, George J; Peirson, Michael; Riley, Tara; Croonenberghs, Robert E; Kensler, Jennifer

    2014-05-01

    The model ordinance in the National Shellfish Sanitation Program's Guide for the Control of Molluscan Shellfish was initially established for oysters; however, the clam industry also follows the protocol. Rapid cooling during periods when the growing waters exceed 80 F (26.7 C) results in cold shock, which causes unacceptable mortalities in clams. The clam industry was looking for a procedure to lower the clams to the standard temperature while minimizing shell shock mortalities during the warm summer months. Three tempering treatments were examined, and total aerobic plate counts (APCs) and most-probable-number (MPN) counts of Vibrio, V. parahaemolyticus, and fecal coliforms were enumerated. In treatment 1 (control), clams were harvested, held for 5 h at 90 F (32.2 C), and then moved to 45 F (7.2 C) for storage. In treatment 2, clams were harvested and held for 5 h at 90 F (32.2 C), followed by 12 h at 65 F (18.3 C) and 12 h at 55 F (12.8 C), and then were moved to 45 F (7.2 C) for long-term storage. In treatment 3, clams were harvested and held for 5 h at 90 F (32.2 C), followed by 24 h at 55 F (12.8 C) before being moved to 45 F (7.2 C) for long-term storage. Three replicate trials were performed with triplicate analyses during late June through early to mid-August. The current National Shellfish Sanitation Program standard is treatment 1; it contained statistically (P ? 0.05) higher total APCs than treatments 2 and 3 throughout the 21-day storage period. APCs ranged from 2.3 10(4) immediately after harvest to 2.7 10(6), 1.6 10(5), and 4.8 10(5) for treatments 1, 2, and 3, respectively, after 14 days of storage. A statistical analysis showed that treatments 2 and 3 had significantly lower total MPN per gram Vibrio than treatment 1 on day 7 but were equal to treatment 1 on days 1 and 14. MPN per gram for V. parahaemolyticus was statistically lower in treatments 2 and 3 than in treatment 1 on storage days 1 and 7. However, on day 14, treatment 3 was significantly lower than treatments 1 and 2. There was no statistical difference for fecal coliforms. The greatest mortality occurred in treatment 1 (87.4%), followed by treatment 2 (83.3%) and treatment 3 (66.0%). The outcome of this research clearly shows that treatments 2 and 3 can cool clams to a temperature of 45 F (7.2 C) without compromising quality or safety and can reduce the number of dead clams introduced into the marketplace. PMID:24780343

  4. Enzymatic and histopathologic biomarkers as indicators of contaminant exposure and effect in Asian clam (Potamocorbula amurensis)

    USGS Publications Warehouse

    Teh, S.J.; Clark, S.L.; Brown, C.L.; Luoma, S.N.; Hinton, D.E.

    1999-01-01

    Enzymatic and histopathologic alterations of the digestive gland, gill, gonad, and kidney were studied in Asian clam (Potamocorbula amurensis) in April, 1997 from each of four United States Geological Survey (USGS) stations in the San Francisco Estuary. Stations were selected based on differing body burdens of metallic contaminants in clams (Stn 4.1>6.1>8.1>12.5) observed over 7 years. Because no pristine sites are known within the estuary and because no laboratory-reared stocks of P. amurensis were available, clams from station 12.5 served as reference animals. Histopathologic analysis revealed no lesions in clams collected from station 12.5. Mild digestive gland atrophy and moderate distal kidney tubular vacuolation were seen in clams collected from station 8.1. Mild digestive gland atrophy, moderate kidney tubular atrophy, and moderate gill inflammation were seen in clams collected from station 6.1. Lesions found only in clams from station 4.1 were: (1) severe inflammation and moderate atrophy of primary ducts and diverticula, and decreased numbers of heterophagosomes and heterolysosomes in diverticula of the digestive gland; (2) severe gill inflammation; (3) severe kidney tubular atrophy; (4) severe ovarian and testicular inflammation and necrosis (5) decreased numbers of mature ova; and (6) decreased number of glycogen storage cells in the ovary and testis. Localization of specific enzymes including adenosine triphosphatase (ATP), acid phosphatase (ACP), alkaline phosphatase (ALKP), gamma-glutamyl transpeptidase (GGT), and glucose-6-phosphate dehydrogenase (G6PDH) was performed and correlated, in serial sections with glycogen (PAS) and haematoxylin and eosin stains. Enzymatic analysis revealed: (1) increased digestive diverticula ATP in stations 6.1 and 4.1; (2) decreased digestive diverticula ACP in stations 6.1 and 4.1 and proximal kidney tubular ACP deficiency in station 4.1; (3) no ALKP differences among stations; (4) increased distal kidney tubular GGT at station 12.5 and decreased distal kidney tubular GGT at station 4.1; (5) decreased digestive diverticula G6PDH G6PDH in all stations except 12.5 and decreased proximal kidney tubular G6PDH in stations 8.1 and 6.1. It is possible that other anthropogenic and natural stressors may have affected the results in this study. However, the prevalence and increased severity of lesions in clams with highest metal body burden suggests a contaminant- associated etiology. Enzymatic and histopathologic biomarker alterations identified in this study were positively correlated with the metal body burden. Clams with the higher prevalence of diseases and enzyme alterations also showed a lower condition index and glycogen content in the month when histopathological assessment was performed. Further study will seek to develop enzymatic and histopathologic biomarkers for use in controlled laboratory conditions to help validate the field study.

  5. Dwarf elliptical galaxies

    NASA Technical Reports Server (NTRS)

    Ferguson, Henry C.; Binggeli, Bruno

    1994-01-01

    Dwarf elliptical (dE) galaxies, with blue absolute magnitudes typically fainter than M(sub B) = -16, are the most numerous type of galaxy in the nearby universe. Tremendous advances have been made over the past several years in delineating the properties of both Local Group satellite dE's and the large dE populations of nearby clusters. We review some of these advances, with particular attention to how well currently availiable data can constrain (a) models for the formation of dE's, (b) the physical and evolutionary connections between different types of galaxies that overlap in the same portion of the mass-spectrum of galaxies, (c) the contribution of dE's to the galaxy luminosity functions in clusters and the field, (d) the star-forming histories of dE's and their possible contribution to faint galaxy counts, and (e) the clustering properties of dE's. In addressing these issues, we highlight the extent to which selection effects temper these constraints, and outline areas where new data would be particularly valuable.

  6. White Dwarf Pulsars

    NASA Technical Reports Server (NTRS)

    Patterson, Joseph

    1999-01-01

    This proposal was designed to study pulse and orbital modulations in candidate DQ Herculis stars. Data on 5 stars were obtained. The best results were obtained on YY Draconis, which exhibited a strongly pulsed hard X-ray flux, and even suggested a transition between one-pole and two-pole emission during the course of the observation. This result is being readied for inclusion in a comprehensive study of YY Draconis. A strong pulsation appeared to be present also in H0857-242, but with a period of about 50 minutes, confusion with the first harmonic of the satellite's orbital frequency is possible. So that result is uncertain. A negative result was obtained on 4UO608-49 (V347 Pup), suggesting either that the X-ray identification is incorrect, or that the source is very transient. Finally, data was obtained on V1432 Aql and WZ Sge, respectively the slowest and fastest of these stars. Combined with the Advanced Satellite for Cosmology and Astrophysics (ASCA) data, the high-energy data demonstrates the latter to contain a white dwarf rotating with P = 27.87 s. Optical photometry contemporaneous with the X-ray data was obtained of V1432 Aql, in order to study the variations in the eclipse waveform. As anticipated, the width and centroid of the eclipse appeared to vary with the 50-day "supercycle". A paper reporting this study is now in preparation.

  7. MOD_FreeSurf2D: a Surface Fluid Flow Simulation Model for Rivers, Streams, and Shallow Estuaries

    NASA Astrophysics Data System (ADS)

    Martin, N.; Gorelick, S. M.

    2003-12-01

    The MOD_FreeSurf2D, Modular Free Surface Flow in Two-Dimensions, computer model simulates free surface fluid flow in streams, rivers, and shallow estuaries under the assumptions of a well-mixed water column, a small water depth to width ratio, and a hydrostatic pressure distribution. The dependent variables in the model are free surface elevation, which provides total water depth, and fluid velocity. Primary advantages of MOD_FreeSurf2D relative to other two-dimensional models are a stable and computationally efficient numerical representation and a transparent representation of wetting and drying of the simulation domain. MOD_FreeSurf2D approximates the depth-averaged, shallow water equations with a finite volume, semi-implicit, semi-Lagrangian numerical representation similar to the TRIM method (Casulli, 1990; Casulli and Cheng, 1992; Casulli, 1999). The semi-implicit, semi-Lagrangian approach is computationally efficient because time steps can exceed the Courant-Friedrich-Lewy (CFL) stability criterion without significant accuracy degradation (Robert, 1982; Casulli, 1990). The rectangular, Arakawa C-grid, finite-volume layout allows flooding and drying in response to changing flow conditions without prior channel specification or closed boundary specification. Open boundary conditions available in MOD_FreeSurf2D are specified flux, specified total water depth, specified velocity, radiation free surface, and radiation velocity. MOD_FreeSurf2D requires initial topography, undisturbed water depth, and Manning's roughness coefficient. MOD_FreeSurf2D simulated results are shown to converge to the semi-empirical solution for a simple straight channel case. Two applications demonstrate the accuracy of MOD_FreeSurf2D. The first application is the evolution of water depth in the dambreak-style flume experiment of Bellos et al. (1992). In this case, MOD_FreeSurf2D accurately simulates the changing water depth in the flume during the experiment and models the wetting of the flume below the dam and the drying of the flume above the dam. The second application is simulation of a reach of the Kootenai River, ID studied by Lipscomb et al. (1998). Detailed 3D spatial measurements of water depth and velocity were numerically integrated and compared to the 2D values produced by MOD_FreeSurf2D. Results indicate that MOD_FreeSurf2D accurately simulates depth-averaged velocity and total water depth on the reach scale. Currently, MOD_FreeSurf2D is a fully vectorized set of custom Matlab functions. References: Bellos, C.V., Soulis, J.V., and Sakkas, J.G., 1992, Experimental Investigation of Two-dimensional Dam-break Induced Flows, Journal of Hydraulic Research, v. 20, p. 47-63. Casulli, V., 1999, A Semi-Implicit Finite Difference Method for Non-Hydrostatic, Free-Surface Flows, International Journal for Numerical Methods in Fluids, v. 30, p. 425-440. Casulli, V., 1990, Semi-implicit Finite Difference Methods for the Two-Dimensional Shallow Water Equations, Journal of Computational Physics, v. 86, p. 56-74. Casulli, V. and Cheng, R.T., 1992, Semi-implicit Finite Difference Methods for Three-Dimensional Shallow Water Flow, International Journal for Numerical Methods in Fluids, v. 15, p. 629-648. Lipscomb, S.W., Berenbrock, C., and Doyle, J.D., 1997, Spatial Distribution of Stream Velocities for the Kootenai River Near Bonners Ferry, ID, June 1997. U.S. Geological Survey Open File Report 97-830, 174 p. Robert, A., 1982, A Semi-Lagrangian and Semi-Implicit Numerical Integration Scheme for the Primitive Meteorological Equations, Journal of the Meteorological Society of Japan, v.60, n. 1. p. 319-325.

  8. Length-weight relationship of the freshwater clam, Galatea paradoxa (born 1778) from the Volta Estuary, Ghana.

    PubMed

    Obirikorang, K A; Adjei-Boateng, D; Madkour, H A; Amisah, S; Otchere, F A

    2013-02-15

    The length-weight relationship of the threatened freshwater clam, Galatea paradoxa (Born 1778) from the Volta Estuary, Ghana was studied over a two-year period, from March 2008 to February 2010, to aid in the development of stock assessment models for the sustainable management of the remaining clam stock. Data reported in this study were collected at monthly intervals and covered varying depths of the Estuary ranging from 0.5 to about 10 m. Overall, a total of 5276 clams with shell lengths ranging from 3.40 to 89.24 mm and total weight from 0.10 to 154.00 g were sampled during the study period. The length-weight relationships were highly significant (p < 0.0001) for all the months and the b-values ranged from 2.023 (January 2010) to 3.874 (June 2009). The calculated b-values indicated that clams exhibited different growth patterns at different periods but overall, the pooled samples of 5276 individuals exhibited an isometric growth pattern (b = 3.003). The observed monthly growth patterns exhibited by G. paradoxa appeared to be largely influenced by the reproductive cycle of the organism. During the periods leading to spawning, the clams generally exhibited positive allometric growth patterns (weight increasing faster than length) which appeared to be strongly linked to the build-up of proteins and carbohydrates in their tissues. Successive negative allometric growth patterns (length increasing faster relative to weight) were, however, observed from March to June 2008 and from December 2009 to February 2010, which are possibly indicative of the loss in tissue weight that occurs as a direct result of the spawning process. It will thus be suitable to institute a close season to coincide with the spawning period of the clams to avoid the harvesting of clams during the spawning period which will enhance future recruitment of the clam stock. PMID:24171267

  9. Differential immune response in the hard clam (mercenaria mercenaria) against bacteria and the protistan pathogen QPX (quahog parasite unknown).

    PubMed

    Perrigault, Mickael; Allam, Bassem

    2012-06-01

    The immune response of the hard clam (quahog) Mercenaria mercenaria following challenge with live bacteria (Vibrio alginolyticus) and the protist QPX (Quahog Parasite Unknown) was investigated. The study also compared immune responses following QPX challenge in two different hard clam broodstocks exhibiting different degrees of susceptibility toward this parasite. Different immune and stress-related cellular and humoral factors were assessed including general hemocyte parameters (total and differential hemocyte counts, percentage of dead cells, reactive oxygen production, phagocytosis), parameters geared toward QPX (anti-QPX activity in plasma and hemocyte resistance to the cytotoxicity of QPX extracellular products). Two genes (ferritin and metallothionein) previously shown to be modulated following QPX exposure were molecularly characterized by rapid amplification of cDNA ends (RACE) and their transcription levels were determined in resistant and susceptible clams in response to QPX and bacterial challenge. Results indicated that both V. alginolyticus and QPX challenge triggered significant immune responses in clams with similar trends for most measured parameters. However, specific responses were observed for anti-QPX activity in plasma and hemocyte resistance to QPX products as well as ferritin and metallothionein expression according to each inoculum. Similarly, different response patterns were detected following QPX challenge in susceptible and resistant clam stocks. Resistant clams were able to elicit effective response against the parasite leading to the elimination of QPX and the restoration of constitutive immune status whereas QPX-susceptible clams triggered a strong immune modulation characterized by an acute phase response and associated acute phase protein but appeared to be less active in eliminating the parasite. These results suggest that different signaling pathways are triggered during V. alginolyticus and QPX challenge. Moreover, differences in the immune response toward QPX might be linked to the susceptibility or resistance of different clam stocks to the infection by this parasite. PMID:22484278

  10. Archive and Analysis of Data Collected Aboard the University of Washington's Convair-580 Research Aircraft in CLAMS

    NASA Technical Reports Server (NTRS)

    Hobbs, Peter V.

    2004-01-01

    Work under this grant has been concerned with: (a) quality-assurance (QA) checking of the data collected on the University of Washington s (UW) Convair- 580 in the Chesapeake Lighthouse and Measurements for Satellites (CLAMS) field study in the Summer of 2001, (b) providing these data to the Langley DAAC, (c) providing specific data to users as requested, (d) analysis of portions of the data and publication of results, and (e) presentation of CLAMS results at workshop and conferences.

  11. Effect of fluctuating low-level chlorine concentrations on valve-movement behavior of the asiatic clam (corbicula fluminea)

    SciTech Connect

    Ham, K.D. . Graduate Program in Ecology); Peterson, M.J. )

    1994-03-01

    Asiatic clams (Corbicula fluminea) exposed to water from the upstream section of East Fork Popular Creek (Oak Ridge, TN), a stream receiving chlorine-containing industrial discharges, were monitored for changes in valve movement patterns. Individual clams were attached to an automated valve-movement monitoring apparatus and suspended in flow-through tanks located streamside. Valve-closure behavior of two clams exposed to untreated water was compared to that of two clams exposed to dechlorinated water for two 18-d periods. Chlorine concentrations in untreated water exhibited a pronounced diurnal cycle, fluctuating between a mean daily minimum of 0.02 mg/L total residual chlorine (TRC) during the day and a mean daily maximum of 0.07 mg/L TRC at night during the second monitoring period. In over 2,300 fifteen-minute intervals, clams closed for 0.70 of the intervals while exposed to untreated water, but closed for only 0.22 of the intervals while exposed to dechlorinated water. Treatment differences in valve closure were tested by repeated-measures ANOVA. A significant treatment effect on valve closure was found in the first monitoring period. Graphical analysis of valve-closure records revealed duel cycles that differed between treatments. Clams in untreated water usually opened only near midday, when TRC concentrations were lowest. Clams in dechlorinated water opened more often, for longer periods, and appeared to respond to dawn and dusk changes in light. The valve-closure behavior of clams in untreated water effectively minimized tissue exposure to waterborne TRC, presumably reducing toxic effects. Valve-closure monitoring in conjunction with other studies may help estimate the effect of tissue isolation on the toxicity or bioaccumulation of waterborne chemicals. Such estimates could improve prediction of toxicological or ecological consequences of stressful conditions on bivalves.

  12. Pathologic survey on the Manila clam Ruditapes philippinarum (Adams and Reeve 1850) from Haeju off the western coastal Yellow Sea

    NASA Astrophysics Data System (ADS)

    Yang, Hyun-Sung; Park, Kwang-Jae; Choi, Kwang-Sik

    2010-06-01

    Pathologic condition of Manila clam, Ruditapes philippinarum collected from Haeju off the west coast of North Korea in February and March 2007 was investigated in this study. The diagnostics included a protozoan parasite, Perkinsus olseni, the brown ring disease (BRD) caused by bacteria Vibrio tapetis and metazoan parasites Trematod and Cestod. P. olseni infection was examined using histology and Rays fluid thioglycollate medium (RFTM) assay along with Chois NaOH digestion technique. Trematode and cestode infection was also examined from the histology. A total of 140 clams with 35-45 mm in shell length (2-3 years old) were analyzed. Condition factor (CF), a ratio of the wet tissue weight to the shell dry weight, ranged from 0.4450.074 (February) to 0.5440.132 (March). Total body burden of P. olseni (i.e. infection intensity) ranged from 18,64437,755 (February) to 26,93380,611 cells/g wet tissue (March) with the prevalence of 76.7-43.3% (March) respectively. Prevalence of trematode and cestode infection in February and March varied 22.5-25.0 and 15.0-22.5% respectively. Infection intensity of V. tapetis ranged 1-2 and the prevalence was 1.4 (February) and 5.7% (March). Prevalence and infection intensity of P. olseni in clams from Haeju was comparatively lower than those of clams reported on the west coast of Korea. BRD and the other metazoan parasite infection were also relatively lower or similar to the condition of the clams reported previously. CF of Haeju clams was also relatively higher than the clams in Gyeonggi Bay and Taean, suggesting that Haeju clams had relatively better pathologic and health condition.

  13. Brown dwarfs as close companions to white dwarfs

    NASA Technical Reports Server (NTRS)

    Stringfellow, Guy S.; Bodenheimer, Peter; Black, David C.

    1990-01-01

    The influence of the radiation flux emitted by a white dwarf primary on the evolution of a closely orbiting brown dwarf (BD) companion is investigated. Full stellar evolutionary calculations are presented for both isolated and thermal bath cases, including effects of large variations in the atmospheric grain opacities. High grain opacities significantly increase the radii of the BDs, but the thermal bath does not. The major influence of the thermal bath is to increase substantially the surface temperature and luminosity of the BD at a given age. These results are compared with the observational properties of the possible BD companion of the white dwarf G29-38. Inclusion of both physical effects, high grain opacities and thermal bath, increases the mass range (0.034-0.063 solar masses) of viable models significantly, yet the final determination of whether the object is indeed a BD requires improvements in the observations of the system's properties.

  14. Faint dwarfs in nearby groups

    SciTech Connect

    Speller, Ryan; Taylor, James E. E-mail: taylor@uwaterloo.ca

    2014-06-20

    The number and distribution of dwarf satellite galaxies remain a critical test of cold dark matter-dominated structure formation on small scales. Until recently, observational information about galaxy formation on these scales has been limited mainly to the Local Group. We have searched for faint analogues of Local Group dwarfs around nearby bright galaxies, using a spatial clustering analysis of the photometric catalog of the Sloan Digital Sky Survey (SDSS) Data Release 8. Several other recent searches of SDSS have detected clustered satellite populations down to ?m{sub r} ? (m{sub r,} {sub sat} m{sub r,} {sub main}) ? 6-8, using photometric redshifts to reduce background contamination. SDSS photometric redshifts are relatively imprecise, however, for faint and nearby galaxies. Instead, we use angular size to select potential nearby dwarfs and consider only the nearest isolated bright galaxies as primaries. As a result, we are able to detect an excess clustering signal from companions down to ?m{sub r} = 12, 4 mag fainter than most recent studies. We detect an overdensity of objects at separations <400 kpc, corresponding to about 4.6 0.5 satellites per central galaxy, consistent with the satellite abundance expected from the Local Group, given our selection function. Although the sample of satellites detected is incomplete by construction, since it excludes the least and most compact dwarfs, this detection provides a lower bound on the average satellite luminosity function, down to luminosities corresponding to the faintest ''classical'' dwarfs of the Local Group.

  15. Identification and expression of differentially expressed genes in the hard clam, Mercenaria mercenaria, in response to quahog parasite unknown (QPX)

    PubMed Central

    Perrigault, Mickael; Tanguy, Arnaud; Allam, Bassem

    2009-01-01

    Background The hard clam, Mercenaria mercenaria, has been affected by severe mortality episodes associated with the protistan parasite QPX (Quahog Parasite Unknown) for several years. Despite the commercial importance of hard clams in the United States, molecular bases of defense mechanisms in M. mercenaria, especially during QPX infection, remain unknown. Results Our study used suppression subtractive hybridization (SSH), as well as the construction of cDNA libraries from hemocytes to identify genes related to the defense of the hard clam against its parasite. Hard clams were experimentally infected with QPX and SSH was performed on mRNA samples extracted from mantle and gill tissues at different times post-challenge. A total of 298 clones from SSH libraries and 1352 clones from cDNA libraries were sequenced. Among these sequences, homologies with genes involved in different physiological processes related to signal transduction, stress response, immunity and protein synthesis were identified. Quantitative PCR revealed significant changes in the expression of several of these genes in response to QPX challenge and demonstrated significant correlations in terms of levels of gene expression between intermediates of signalling pathways and humoral defense factors, such as big defensin and lysozyme. Conclusion Results of this study allowed the detection of modifications caused by QPX at the transcriptional level providing insight into clam immune response to the infection. These investigations permitted the identification of candidate genes and pathways for further analyses of biological bases of clam resistance to QPX allowing for a better understanding of bivalve immunity in general. PMID:19682366

  16. Immunological Profile of the Yellow Clam Mesodesma mactroides (Mesodesmatidae) from the Southern Coast of Rio Grande do Sul, Brazil.

    PubMed

    Silva Santos, Juan Jethro; Carvalho, Yuri Bovi; de Alcantara Lopes, Diogo Luiz; Romano, Luis Alberto

    2016-03-01

    The yellow clam Mesodesma mactroides (Mesodesmatidae) is a sandy beach bivalve that is distributed from Rio de Janeiro, Brazil, to the south of Buenos Aires province, Argentina. The yellow clam population has been declining in recent decades. To increase our understanding of this species, we evaluated the immunological status of yellow clams collected during different seasons from various areas in the state of Rio Grande do Sul, Brazil. We characterized the hemocytes, determined the differential hemocyte counts (DHCs), calculated the apoptotic index, and evaluated the incidence of parasites in yellow clams through histological analysis. We identified two types of hemocyte (hyaline and granular) that showed significant variation in DHCs among sampling areas during the summer and winter. The apoptotic index only exhibited significant variation during the summer. Histopathological analysis results did not significantly differ among sampling areas. This work demonstrated that environmental variation (e.g., temperature and salinity) associated with anthropogenic actions may be affecting the immune system of yellow clams. However, more studies are needed to determine the full influence of these factors on the yellow clam's immune system and thus contribute to future management and aquaculture of the species. Received May 10, 2015; accepted October 28, 2015. PMID:26913557

  17. De novo RNA-Seq Analysis of the Venus Clam, Cyclina sinensis, and the Identification of Immune-Related Genes

    PubMed Central

    Pan, Baoping; Ren, Yipeng; Gao, Jing; Gao, Hong

    2015-01-01

    The Venus clam, Cyclina sinensis, is one of the most important bivalves in China. In recent years, increasing expansive morbidity has occurred in breeding areas, imposing significant losses on the national economy. To understand the molecular mechanisms of immune-related genes, we analyzed and sequenced hemolymph samples that were injected with two pathogenic microorganisms using the Illumina Miseq system. After trimming, more than 12 M PE reads with an average length greater than 410 bp were assembled into 70,079 transcripts with a mean length of 980 bp. Using a homology analysis, 102 (135 transcripts) potentially immune-related genes were identified, and most of them exhibited a similar pattern in both samples. These data indicated that the response of the clam to both types of bacterial infection might follow a similar molecular mechanism. Using the TreeFam method, 9,904 gene families and 1,031 unique families of the clam were preliminarily classified in comparison to five related species. A significant number of SSRs were identified, which could facilitate the identification of polymorphisms in Venus clam populations. These datasets will improve our knowledge of the molecular mechanisms driving the immune response to bacterial infection in clam populations and will provide basic data about clam breeding and disease control. PMID:25853714

  18. Biochemical performance of native and introduced clam species living in sympatry: The role of elements accumulation and partitioning.

    PubMed

    Velez, Cátia; Leandro, Sérgio; Figueira, Etelvina; Soares, Amadeu M V M; Freitas, Rosa

    2015-08-01

    The present study reports metal and arsenic contamination in sediments, as well as element accumulation and partitioning in native (Ruditapes decussatus and Venerupis corrugata) and introduced (Ruditapes philippinarum) clam species living in sympatry at the Óbidos lagoon (Portugal). The biochemical performance and the human health risks derived from the consumption of these species are also discussed. The results obtained showed that R. decussatus was the most abundant species in all the sampling sites, revealing that the introduced clam has not yet supplanted the native species. The concentration of elements was higher in areas with higher Total Organic Matter (TOM) and fines content, being Chromium (Cr), Copper (Cu) and Lead (Pb) the most abundant metals. Clams from these areas showed the highest concentration of elements but the lowest bioaccumulation levels. Furthermore, except for As, higher concentration of elements was found in clams insoluble fraction, the less toxic fraction to the organisms. Due to the low contamination levels and because elements, except As, were mainly allocated to the insoluble fraction, clams presented similar biochemical parameters among distinct areas, with no significant oxidative stress induced. Furthermore, clams from the Óbidos lagoon represent a low health risk to human consumption since, except for As, their contamination levels were below the maximum permissible limits defined by international organizations. PMID:26112075

  19. Occurrence and Seasonal Variations of Lipophilic Marine Toxins in Commercial Clam Species along the Coast of Jiangsu, China.

    PubMed

    Wang, Xin-Zhi; Cheng, Ying; Li, Na; Wen, Hong-Mei; Liu, Rui; Shan, Chen-Xiao; Chai, Chuan; Wu, Hao

    2015-01-01

    Recent studies have examined lipophilic marine toxins (LMTs) in shellfish and toxic algae worldwide, but the occurrence and seasonal variations of LMTs in commercial clams (including Mactra veneriformis, Ruditapes philippinarum, Meretrix meretrix, and Cyclina sinensis) at their major culturing area in Jiangsu, China, remain largely unexplored. In this study, a new solid phase extraction (SPE) in combination with an ultra-fast liquid chromatography and triple-quadrupole linear ion trap mass spectrometry (UFLC-TQ-MS) method was developed to determine the presence of 10 typical LMTs (okadaic acid (OA), yessotoxins (YTXs), azaspiracids (AZA1-3), pectenotoxins (PTX2), gymnodimine (GYM), dinophysistoxins (DTX1&2), and spirolides (SPX1)) in the aforementioned four clam matrices. After confirmation of its sensitivity and precision, this method was used to evaluate the amounts of LMTs in clam samples harvested in five aquaculture zones of the Jiangsu coastal area. Monthly variations of GYM, PTX2, OA, and DTX1&2 in 400 clam samples from the sample areas were determined from January 2014 through August 2015. Peak values were observed during May and August. This is the first systematic report of LMTs detected in clam samples harvested in Jiangsu. Follow-up research and the implementation of protective measures are needed to ensure the safety of clams harvested in this area. PMID:26712791

  20. Occurrence and Seasonal Variations of Lipophilic Marine Toxins in Commercial Clam Species along the Coast of Jiangsu, China

    PubMed Central

    Wang, Xin-Zhi; Cheng, Ying; Li, Na; Wen, Hong-Mei; Liu, Rui; Shan, Chen-Xiao; Chai, Chuan; Wu, Hao

    2015-01-01

    Recent studies have examined lipophilic marine toxins (LMTs) in shellfish and toxic algae worldwide, but the occurrence and seasonal variations of LMTs in commercial clams (including Mactra veneriformis, Ruditapes philippinarum, Meretrix meretrix, and Cyclina sinensis) at their major culturing area in Jiangsu, China, remain largely unexplored. In this study, a new solid phase extraction (SPE) in combination with an ultra-fast liquid chromatography and triple-quadrupole linear ion trap mass spectrometry (UFLC-TQ-MS) method was developed to determine the presence of 10 typical LMTs (okadaic acid (OA), yessotoxins (YTXs), azaspiracids (AZA1-3), pectenotoxins (PTX2), gymnodimine (GYM), dinophysistoxins (DTX1&2), and spirolides (SPX1)) in the aforementioned four clam matrices. After confirmation of its sensitivity and precision, this method was used to evaluate the amounts of LMTs in clam samples harvested in five aquaculture zones of the Jiangsu coastal area. Monthly variations of GYM, PTX2, OA, and DTX1&2 in 400 clam samples from the sample areas were determined from January 2014 through August 2015. Peak values were observed during May and August. This is the first systematic report of LMTs detected in clam samples harvested in Jiangsu. Follow-up research and the implementation of protective measures are needed to ensure the safety of clams harvested in this area. PMID:26712791

  1. Size-related and seasonal diet of the manila clam (Ruditapes philippinarum), as determined using dual stable isotopes

    NASA Astrophysics Data System (ADS)

    Suh, Yeon Jee; Shin, Kyung-Hoon

    2013-12-01

    Stable isotope ratios of lab-cultured Manila clams (Ruditapes philippinarum) and those from natural tidal flats of Seonjae Island in Korea were investigated in terms of their dietary uptake patterns in relation to body size and season. The smallest size group of wild Manila clams revealed significantly depleted ?15N based on the results of a one-way ANOVA. There was significant seasonal change in the proportional contribution of food sources, especially in winter, from benthic particulate organic matter (BPOM) to pelagic particulate organic matter (POM). Laboratory-cultured Manila clams showed growth rates of 6.02-37.75 mm/yr, and smaller-sized clams did not fully utilise the microalgal diets that were provided constantly. Instead, they derived most of their energy from detritus or dead microalgae that had settled on the bottom. Bigger clams, however, exhibited well-balanced source contributions, converting the microalgal diets into biomass. This demonstrates intra-specific differences in the growth rates and preferred diet uptakes of Manila clams, even under similar environmental conditions.

  2. Differential toxicological effects induced by mercury in gills from three pedigrees of Manila clam Ruditapes philippinarum by NMR-based metabolomics.

    PubMed

    Liu, Xiaoli; Zhang, Linbao; You, Liping; Yu, Junbao; Zhao, Jianmin; Li, Lianzhen; Wang, Qing; Li, Fei; Li, Chenghua; Liu, Dongyan; Wu, Huifeng

    2011-01-01

    Mercury is a hazardous pollutant in the Bohai marine environments due to its high toxicity to the marine organisms and subsequent ecological risk. Manila clam Ruditapes philippinarum is one of important sentinel organisms in 'Mussel Watch Program' launched in China and therefore used as a bioindicator in marine and coastal ecotoxicology. There are dominantly distributed three pedigrees of clam (White, Liangdao Red and Zebra) in Yantai population endowed with different tolerances to environmental stressors. In this study, gill tissues were collected from both untreated and mercury exposed White, Liangdao Red and Zebra clams, and the extracts were analyzed by NMR-based metabolomics to compare the original metabolomes and the toxicological effects induced by mercury exposure in three pedigrees. The major abundant metabolites in White clam sample were branched-chain amino acids, lactate, alanine, arginine, acetoacetate, glutamate, succinate, citrate, malonate and taurine, while the metabolite profile of Liangdao Red clam sample comprises relative high levels of alanine, arginine, glutamate, succinate and glycogen. For Zebra clam sample, the metabolite profile exhibited relatively high amount of aspartate, acetylcholine and homarine. After 48 h exposure of 20 ?g l(-1) Hg(2+), the metabolic profiles from all the three pedigrees of clams commonly showed significant increases in alanine, arginine, glutamate, aspartate, ?-ketoglutarate, glycine and ATP/ADP, and decreases in citrate, taurine and homarine. The unique metabolic differences between the metabolomes of gill tissues from Hg(2+)-exposed White, Liangdao Red and Zebra clams were found, including elevated acetylcholine and branched-chain amino acids in White clams, and the declined succinate in both White and Liangdao Red samples as well as the declined betaine in Zebra and White clams. Overall, our findings showed the differential toxicological responses to mercury exposure and that White clams could be a preferable bioindicator for the metal pollution monitoring based on the metabolic changes from gill compared with other two (Liangdao Red and Zebra) pedigrees of clams. PMID:21080220

  3. Branes constrictions with White Dwarfs

    NASA Astrophysics Data System (ADS)

    García-Aspeitia, Miguel A.

    2015-11-01

    We consider here a robust study of stellar dynamics for white dwarf stars with polytropic matter in the weak-field approximation using the Lane-Emden equation from the brane-world scenario. We also derive an analytical solution to the nonlocal energy density and show the behavior and sensitivity of these stars to the presence of extra dimensions. Similarly, we analyze stability and compactness, in order to show whether it is possible to agree with the conventional wisdom of white dwarfs dynamics. Our results predict an average value of the brane tension of < λ rangle ≳ 84.818MeV^4, with a standard deviation σ ˜eq 82.021MeV^4, which comes from a sample of dwarf stars, being weaker than other astrophysical observations but remaining higher than cosmological results provided by nucleosynthesis among others.

  4. Magnetic Activity of Ultracool Dwarfs

    NASA Astrophysics Data System (ADS)

    McKay, Myles; Osten, Rachel A.; Stelzer, Beate

    2016-01-01

    Ultracool dwarfs are very low mass objects that have a temperature below about 2,800K; magnetic activity signatures probe magnetic field behavior in a mass regime intermediate between stars and planets. Very few ultracool dwarfs have detected levels of radio emission, so increasing the sample size is important for the understanding the variety of magnetic processes at work. Because of the dramatic variations in radio and X-ray properties, these probes are best done with simultaneous measurements. We report on a small sample of ultracool dwarfs that have been observed simultaneously with XMM Newton Observatory and the Jansky Very Large Array, for constraints on their coronal plasmas through X-ray and radio observations, respectively; we present the results of the radio reduction, calibration and imaging of our sample. We discuss the implications of upper limits and detections for increasing our understanding of magnetic field behavior in this regime.

  5. 76 FR 55566 - Safety Zones; Fireworks Displays and Surfing Events in Captain of the Port Long Island Sound Zone

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-08

    ... Captain of the Port Long Island Sound Zone AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY...) Long Island Sound Zone for a surfing event and fireworks displays. This action is necessary to provide... anchoring within this zone is prohibited unless authorized by the COTP Sector Long Island Sound. DATES:...

  6. Pluto: Dwarf planet 134340

    NASA Astrophysics Data System (ADS)

    Ksanfomality, L. V.

    2016-01-01

    In recent decades, investigations of Pluto with up-to-date astronomical instruments yielded results that have been generally confirmed by the New Horizons mission. In 2006, in Prague, the General Assembly of the International Astronomical Union (IAU) reclassified Pluto as a member of the dwarf planet category according to the criteria defined by the IAU for the term "planet". At the same time, interest in studies of Pluto was increasing, while the space investigations of Pluto were delayed. In 2006, the New Horizons Pluto spacecraft started its journey to Pluto. On July 14, 2015, the spacecraft, being in fly-by mode, made its closest approach to Pluto. The heterogeneities and properties of the surface and rarified atmosphere were investigated thoroughly. Due to the extreme remoteness of the spacecraft and the energy limitations, it will take 18 months to transmit the whole data volume. Along with the preliminary results of the New Horizons Pluto mission, this paper reviews the basics on Pluto and its moons acquired from the ground-based observations and with the Hubble Space Telescope (HST). There are only a few meteorite craters on the surfaces of Pluto and Charon, which distinctly marks them apart from such satellites of the giant planets as Ganymede and Callisto. The explanation is that the surface of Pluto is young: its age is estimated at less than 100 Myr. Ice glaciers of apparently a nitrogen nature were found. Nitrogen is also the main component of the atmosphere of Pluto. The planet demonstrates the signs of strong geologic activity, though the energy sources of these processes are unknown.

  7. How, Now, Brown Dwarfs?

    NASA Astrophysics Data System (ADS)

    Brecher, Kenneth

    2009-01-01

    The vocabulary of astronomy is riddled with colorful names for stars, from red giants to blue stragglers. Objects with masses between roughly .01 and .1 solar masses are called "brown dwarfs". Do they - could they - ever actually appear brown? Color is not a one-dimensional physical parameter like wavelength. It is a complex, psychophysical phenomenon involving not only three degrees of freedom - hue (often incorrectly equated with "color"), saturation and brightness - but also observational context. The perceptual nature of color has been known since Newton wrote in his "Opticks” in 1704: "For the Rays to speak properly are not coloured. In them there is nothing else than a certain Power and disposition to stir up a Sensation of this or that Colour.” To most observers, the 2000 or so naked eye stars observable from the northern hemisphere all appear white, with the half dozen exceptions which look reddish/orange like Betelgeuse, Arcturus and Antares. But what color would Betelgeuse (effective temperature 3600 K) appear at a distance of, say, 100 times the Earth-Sun separation? Not red. In fact, it has a temperature about 40% higher than that of an ordinary incandescent light bulb. It would appear white (or yellowish)! Can a very cool radiating (emissive) object ever appear brown? What is brown anyway? It is not a primary or even secondary color. In this presentation, we will explore the nature and meaning of "brown” by the use of several physical and computer demonstrations developed as part of "Project LITE- Light Inquiry Through Experiments", an educational materials development project. These demonstrations show that an isolated thermally radiating object will never appear brown. Hence the term "Brown Dwarf” is as nonsensical as the phrase "How, Now, Brown Cow?". Project LITE is supported by the NSF through DUE Grant # 0715975.

  8. In Brief: Dwarf planet named

    NASA Astrophysics Data System (ADS)

    Zielinski, Sarah

    2006-09-01

    The dwarf planet 2003 UB313, which had been nicknamed `Xena,' has been given the formal name of Eris, the International Astronomical Union announced on 13 September. Eris, which was discovered in January 2005, was named for the Greek goddess of discord. Its moon has been named Dysnomia, for the daughter of Eris, the demon goddess of lawlessness. Eris was assigned dwarf planet status in an IAU resolution approved in August (see Eos 87(35), 2006) along with Pluto and Ceres. Pluto's demotion prompted the Minor Planet Center, which operates under the auspices of the IAU, to assign Pluto an asteroid number, 134340, on 7 September.

  9. Tensile properties of CLAM steel irradiated up to 20.1dpa in STIP-V

    NASA Astrophysics Data System (ADS)

    Ge, Hongen; Peng, Lei; Dai, Yong; Huang, Qunying; Ye, Minyou

    2016-01-01

    Specimens of China low activation martensitic steel (CLAM) were irradiated in the fifth experiment of SINQ Target Irradiation Program (STIP-V) up to 20.1dpa/1499appm He/440C. Tensile tests were performed at room temperature (R.T) and irradiation temperatures (Tirr) in the range of 25-450C. The tensile results demonstrated strong effect of irradiation dose and irradiation temperature on hardening and embrittlement. With Tirr below ?314C, CLAM steel specimens tested at R.T and Tirr showed similar evolution trend with irradiation dose, compared to other reduced activation ferritic/martensitic (RAFM) steels in similar irradiation conditions. At higher Tirr above ?314C, it is interesting that the hardening effect decreases and the ductility seems to recover, probably due to a strong effect of high irradiation temperature.

  10. Creep deformation and rupture behavior of CLAM steel at 823 K and 873 K

    NASA Astrophysics Data System (ADS)

    Zhong, Boyu; Huang, Bo; Li, Chunjing; Liu, Shaojun; Xu, Gang; Zhao, Yanyun; Huang, Qunying

    2014-12-01

    China Low Activation Martensitic (CLAM) steel is selected as the candidate structural material in Fusion Design Study (FDS) series fusion reactor conceptual designs. The creep property of CLAM steel has been studied in this paper. Creep tests have been carried out at 823 K and 873 K over a stress range of 150-230 MPa. The creep curves showed three creep regimes, primary creep, steady-state creep and tertiary creep. The relationship between minimum creep rate (ε˙min) and the applied stress (σ) could be described by Norton power law, and the stress exponent n was decreased with the increase of the creep temperature. The creep mechanism was analyzed with the fractographes of the rupture specimens which were examined by scanning electron microscopy (SEM). The coarsening of precipitates observed with transmission electron microscope (TEM) indicated the microstructural degradation after creep test.

  11. Oxidative effects of the pharmaceutical drug paracetamol on the edible clam Ruditapes philippinarum under different salinities.

    PubMed

    Correia, Brbara; Freitas, Rosa; Figueira, Etelvina; Soares, Amadeu M V M; Nunes, Bruno

    2016-01-01

    Paracetamol, a drug with analgesic and antipyretic properties, is one of the most used substances in human therapeutics, being also frequently detected in aquatic environments. Recent studies report its toxicity towards aquatic species, but the overall amount of data concerning its effects is still scarce. Global changes, likely alterations in abiotic conditions, including salinity, can modulate the interactions of contaminants with biota, conditioning the toxicological responses elicited also by pharmaceuticals. The present article describes the oxidative toxic effects posed by paracetamol on the clam species Ruditapes philippinarum under different salinity conditions. The results demonstrated the establishment of an oxidative-based effect, with significant alteration of several parameters, such as superoxide dismutase (SOD) and the ratio of reduced/oxidized glutathione (GSH/GSSG). Water salinity influenced the response of clams exposed to different paracetamol concentrations, showing the importance of studying physiological traits under realistic test conditions, which are likely to vary in great extent as a result of climate change. PMID:26409706

  12. Horizontal transmission of clonal cancer cells causes leukemia in soft-shell clams.

    PubMed

    Metzger, Michael J; Reinisch, Carol; Sherry, James; Goff, Stephen P

    2015-04-01

    Outbreaks of fatal leukemia-like cancers of marine bivalves throughout the world have led to massive population loss. The cause of the disease is unknown. We recently identified a retrotransposon, Steamer, that is highly expressed and amplified to high copy number in neoplastic cells of soft-shell clams (Mya arenaria). Through analysis of Steamer integration sites, mitochondrial DNA single-nucleotide polymorphisms (SNPs), and polymorphic microsatellite alleles, we show that the genotypes of neoplastic cells do not match those of the host animal. Instead, neoplastic cells from dispersed locations in New York, Maine, and Prince Edward Island (PEI), Canada, all have nearly identical genotypes that differ from those of the host. These results indicate that the cancer is spreading between animals in the marine environment as a clonal transmissible cell derived from a single original clam. Our findings suggest that horizontal transmission of cancer cells is more widespread in nature than previously supposed. PMID:25860608

  13. Clam farming generates CO2: A study case in the Marinetta lagoon (Italy).

    PubMed

    Mistri, Michele; Munari, Cristina

    2012-10-01

    Respiration and calcium carbonate (CaCO(3)) production by the farmed short-neck clam Ruditapes philippinarum were calculated to assess their importance as carbon dioxide (CO(2)) sink/source in a lagoon of the Po Delta River (Italy). Biomass and calcimass were established by monthly harvests during a 1-year period (2009). The ratio of CO(2) released to CaCO(3) precipitated was calculated as a function of the near-bottom temperature. From our estimates, R. philippinarum sequestered [Formula: see text] for shell formation, but the CO(2) fluxes due to respiration and calcification resulted 22.7 and 5.56 [Formula: see text] , respectively. Clam farming seems therefore to be a significant additional source of CO(2) to seawater. PMID:22846887

  14. India ink induces apoptosis in the yellow clam Mesodesma mactroides (Deshayes, 1854). Optical and ultrastructural study.

    PubMed

    Carvalho, Yuri B M; Jethro, Juan; Poersch, Luis H; Romano, Luis A

    2015-12-01

    This paper reports on the acute inflammatory and cellular process in the yellow clam, Mesodesma mactroides, induced by injection of India ink into the muscular foot. Histological observations with optical and electronic microscopy were made at 24 and 48 h after injection. The induced cellular inflammatory response consisted of a general hemocyte infiltration without necrosis and apoptotic activity. Migration of ink-laden phagocytes across the intestinal epithelium was recorded. It appeared that the yellow clam "excreted" ink particles through the gill and kidney. The positive staining for apoptosis was observed in the digestive gland. Electronic microscopy revealed ultrastructural changes of endoplasmic reticulum stress and apoptotic bodies in the digestive gland. The mechanism by which the India ink particles induce apoptosis remains unknown, but might possibly be associated with the endoplasmic reticulum stress. This work has highlighted features that require further discussion in the restricted field the inflammatory responses of mollusks. PMID:26628034

  15. Illinois River fingernail clam toxicity study. Final report, 1 July 1990--31 December 1991

    SciTech Connect

    Sparks, R.E.; Dillon, F.S.

    1998-12-31

    A filtering performance bioassay was developed for the fingernail clam, Musculium transversum, a dominant bottom-dwelling organism in many waters of the midwestern United States, and a key in food chains leading from organic matter in water and sediment to fish and ducks valued by humans. The bioassay was used with a battery of standard bioassays to assess the toxicity of porewaters obtained from sediments of the Illinois River and its associated canal (known collectively as the Illinois Waterway), where fingernail clams and other benthic macroinvertebrates died out in 1955--1958 and have not recolonized, despite the availability of seed populations in tributaries and isolated refugia within the river. Inhibition of filtering performance was easily measured with relatively simple equipment available in most laboratories and proved be directly related to the concentration of a reference toxicant, sodium cyanide.

  16. Cooling water canal improvements to correct structural failures and control Asian clams

    SciTech Connect

    England, W.; Snow, R.E.; Palmer, E.C.

    1995-10-01

    Expansive soils destroyed the floor and impacted the roof support columns of a 600-foot-long concrete cooling water intake canal at the two unit, 700-MW Decker Creek Power Plant in Austin, Texas. These movements exposed clay and silt soils in the canal bottom and provided a habitat for a thriving Asian Clam community which caused operational problems in the plant including unplanned outages. Evaluations were performed to address the structural damages, characterize the clam habitat, and identify concepts to remediate the problem conditions. The various concepts evaluated to eliminate the difficulties are discussed in this paper as well as the basis for selection of the remedial concept. The selected remedial concept consisted of replacing the concrete canal structure with large diameter concrete pipes. The paper also discusses the construction sequence to accomplish the work within a limited outage period.

  17. He and H irradiation effects on the nanoindentation hardness of CLAM steel

    NASA Astrophysics Data System (ADS)

    Jiang, Siben; Peng, Lei; Ge, Hongen; Huang, Qunying; Xin, Jingping; Zhao, Ziqiang

    2014-12-01

    In this study, He and H ion irradiation induced hardening behavior of China Low Activation Martensitic (CLAM) steel was investigated, and the influence of Si on irradiation hardening was also examined. CLAM steel with different Si contents, Heat 0912 and Heat 0408D, were irradiated with single He (He concentration range from 0 to 2150 appm) ion beam and He/H dual ion beams. Then nanoindentation tests were applied to evaluate the ion irradiation induced hardening effect. The result of Heat 0912 showed hardening effect would be more serious with higher He concentration, and the trend saturated when He concentration reach 1000 appm. Comparing the result of Heat 0912 and Heat 0408D, higher Si content might improve the resistance to hardening.

  18. Influence of Methylmercury from Tributary Streams on Mercury Levels in Savannah River Asiatic Clams

    SciTech Connect

    Paller, M.H.

    2004-03-01

    Average methylmercury levels in five Savannah River tributary streams sampled 11 times over two years were nearly twice as high as in the Savannah River. Total mercury levels in the tributaries did not differ significantly from the river. All of the tributaries drained extensive wetlands that would be expected to support comparatively high rates of methylation. Mercury concentrations in Asiatic clams (Corbicula fluminea) collected from the discharge plumes of Savannah River tributaries were significantly higher than in Asiatic clams collected from the Savannah River upstream from the tributary mouths . These results indicate that streams draining wetlands into coastal plain rivers can create localized areas of elevated methylmercury with resulting increases in the mercury levels of river biota.

  19. Mixing and bottom friction: parametrization and application to the surf zone

    NASA Astrophysics Data System (ADS)

    Bennis, A.-C.; Dumas, F.; Ardhuin, F.; Blanke, B.; Lepesqueur, J.

    2012-04-01

    Wave breaking has been observed to impact the bottom boundary layer in surf zones, with potential impacts on bottom friction. Observations in the inner surf zone have also shown a tendency to an underestimation of the wave-induced set-up when using usual model parameterizations. The present study investigates the possible impact of wave breaking on bottom friction and set-up using a recently proposed parameterization of the wave-induced turbulent kinetic energy in the vertical mixing parameterization of the wave-averaged flow. This parametrization proposed by Mellor (2002) allows us to take account the oscillations of the bottom boundary layer with the wave phases thanks to some additional turbulent source terms. First, the behavior of this parameterization, is investigated by comparing phase-resolving and phase-averaged solutions. The hydrodynamical model MARS (Lazure et Dumas, 2008) is used for this, using a modified k-epsilon model to take account the Mellor (2002) parametrization. It is shown that the phase averaged solution strongly overestimates the turbulent kinetic energy, which is similar to the situation of the air flow over waves (Miles 1996). The waves inhibits the turbulence and the wave-averaged parametrization is not able to reproduce correctly this phenomenom. Cases with wave breaking at the surface are simulated in order to study the influence of surface wave breaking on the bottom boundary layer. This parametrization is applied in the surf zone for two differents cases, one for a planar beach and one other for a barred beach with rip currents. The coupled model MARS-WAVEWATCH III is used for this (Bennis et al, 2011) and for a realistic planar beach, the mixing parameterization has only a limited impact on the bottom friction and the wave set-up, unless the bottom roughness is greatly enhanced in very shallow water, or for a spatially varying roughness. The use of the mixing parametrization requires an adjustement of the bottom roughness to fit the observations probably due to the expression of the additional source of turbulent kinetic energy. For an idealized barred beach, the results given by the mixing parametrization are compared with others from parametrizations that take account the wave effects on the bottom friction via the wave orbital velocity, and no via the turbulent kinetic energy as in Mellor (2002). The vertical profile of the rip current is significantly modified by the bottom friction parametrization, while the feedback of the waves on the flow (ie. two-way mode) changes the pattern of the rip currents in comparison with the one-way mode.

  20. Estimating Energy Dissipation Due to Wave Breaking in the Surf Zone Using Infrared Imagery

    NASA Astrophysics Data System (ADS)

    Carini, Roxanne J.

    Wave breaking is the largest forcing mechanism in the surf zone. Therefore, quantifying energy dissipation due to wave breaking is important for improving models that seek to predict nearshore circulation, wave-current interactions, air-sea gas exchange, erosion and accretion of sediment, and storm surge. Wave energy dissipation is difficult to measure with in situ instruments, and even the most reliable estimates are limited to point measurements. Using remote sensing technologies, specifically infrared (IR) imagery, the high spatial and temporal variability of wave breaking may be sampled. Duncan (1981) proposed a model (D81) for dissipation on a wave-by-wave basis, based on wave slope and roller length, the crest-perpendicular length of the aerated region of a breaking wave. The wave roller is composed of active foam, which, in thermal IR images, appears brighter than the surrounding water and the residual foam, the foam left behind in the wake of a breaking wave. Using IR imagery taken during the Surf Zone Optics 2010 experiment at Duck, NC, and exploiting the distinct signature of active foam, a retrieval algorithm was developed to identify and extract breaking wave roller length. Roller length was then used to estimate dissipation rate via the D81 formulation. The D81 dissipation rate estimates compare reasonably to in situ dissipation estimates at a point. When the D81 estimates are compared to the bulk energy flux into the surf zone, it is found that wave breaking dissipates approximately 25-36% of the incoming wave energy. The D81 dissipation rate estimates also agree closely with those from a dissipation parameterization proposed by Janssen and Battjes (2007) (JB07) and commonly applied within larger nearshore circulation models. The JB07 formulation, however, requires additional physical parameters (wave height and water depth) that are often sparsely sampled and are difficult to attain from remote sensing alone. The power of the D81 formulation lies in its dependence on surface signatures alone, and with the methods developed here and those proposed for future work, wave energy dissipation rate maps could be produced for any imageable coastline.

  1. Impacts of stage-specific acute pesticide exposure on predicted population structure of the soft-shell clam, Mya arenaria.

    PubMed

    Lindsay, S; Chasse, J; Butler, R A; Morrill, W; Van Beneden, R J

    2010-07-01

    A combined laboratory and modeling approach was used to assess the impact of selected pesticides on early life stages of the soft-shell clam, Mya arenaria. Clams were exposed for 24h as veligers or pediveligers to the broad-spectrum herbicide hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1h,3h)-dione; Velpar], the phenoxyacetic acid herbicide, 2,4-D (2,4-dichlorophenoxyacetic acid; Agway Super BK 32), or phosmet (Imidan). In addition, juvenile clams were exposed for 24h to 2,4-D and their growth monitored for 21 months. Laboratory experiments indicated veligers were more sensitive to acute pesticide exposure than pediveligers, with 2,4-D exposed veligers exhibiting the lowest survival among all treatments. Relative to controls, juvenile clams exposed to 0.5 ppm 2,4-D had enhanced survival following the initial 3 months of grow out. Juveniles exposed to 0.5, 5 and 10 ppm 2,4-D showed an initial growth delay relative to control clams, but at 21 months post-exposure these clams were significantly larger than control clams. Data from the larval and juvenile exposures were used to generate a stage-specific matrix model to predict the effect of pesticide exposure on clam populations. Impacts on simulated clam populations varied with the pesticide and stage exposed. For example, 2,4-D exposure of veligers and pediveligers significantly reduced predicted recruitment as well as population growth rate compared to controls, but juvenile exposure to 2,4-D did not significantly reduce population growth rate. With the exception of veligers exposed to 10 ppm, hexazinone exposure at the both veliger and pediveliger stages significantly reduced predicted recruitment success compared to 0 ppm controls. Hexazinone exposure also reduced modeled population growth rates, but these reductions were only slight in the pediveliger exposure simulations. Veliger and pediveliger exposure to phosmet reduced modeled population growth rate in a dose-dependent fashion. Changes in modeled population stable stage distributions were also observed when veligers were exposed to any pesticide. These results suggest that both the stage of exposure and the specific toxicant are important in predicting effects of pesticide exposure on soft-shell clam populations, with earlier life stages showing greater sensitivity to the pesticides tested. PMID:20233632

  2. Impacts of stage-specific acute pesticide exposure on predicted population structure of the soft-shell clam, Mya arenaria

    PubMed Central

    Lindsay, S.; Chasse, J.; Butler, R.A.; Morrill, W.; Van Beneden, R.J.

    2010-01-01

    A combined laboratory and modeling approach was used to assess the impact of selected pesticides on early life stages of the soft-shell clam, Mya arenaria. Clams were exposed for 24 h as veligers or pediveligers to the broad-spectrum herbicide hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4 (1h,3h)-dione; (Velpar®)], the phenoxyacetic acid herbicide, 2,4-D (2,4- dichlorophenoxyacetic acid; Agway® Super BK 32), or phosmet (Imidan®). In addition, juvenile clams were exposed for 24 h to 2,4-D and their growth monitored for 21 months. Laboratory experiments indicated veligers were more sensitive to acute pesticide exposure than pediveligers, with 2,4-D exposed veligers exhibiting the lowest survival among all treatments. Relative to controls, juvenile clams exposed to 0.5 ppm 2,4-D had enhanced survival following the initial 3 months of grow out. Juveniles exposed to 0.5 ppm, 5 ppm and 10 ppm 2,4-D showed an initial growth delay relative to control clams, but at 21 months post exposure these clams were significantly larger than control clams. Data from the larval and juvenile exposures were used to generate a stage-specific matrix model to predict the effect of pesticide exposure on clam populations. Impacts on simulated clam populations varied with the pesticide and stage exposed. For example, 2,4-D exposure of veligers and pediveligers significantly reduced predicted recruitment as well as population growth rate compared to controls, but juvenile exposure to 2,4-D did not significantly reduce population growth rate. With the exception of veligers exposed to 10 ppm, hexazinone exposure at the both veliger and pediveliger stages significantly reduced predicted recruitment success compared to 0 ppm controls. Hexazinone exposure also reduced modeled population growth rates, but these reductions were only slight in the pediveliger exposure simulations. Veliger and pediveliger exposure to phosmet reduced modeled population growth rate in a dose-dependent fashion. Changes in modeled population stable stage distributions were also observed when veligers were exposed to any pesticide. These results suggest that both the stage of exposure and the specific toxicant are important in predicting effects of pesticide exposure on soft-shell clam populations, with earlier life stages showing greater sensitivity to the pesticides tested. PMID:20233632

  3. White Dwarf-M Dwarf Binaries in the Solar Neighborhood

    NASA Astrophysics Data System (ADS)

    Skinner, Julie N.; Morgan, Dylan P.; Thorstensen, John R.; Lepine, Sebastien

    2016-01-01

    As the most populous constituents of our galaxy, low-mass dwarfs are vital to understanding our galaxy's structure and kinematics. While wide White dwarf-M dwarf binaries (WD+dMs) can provide significant constraints on M dwarf age-activity relations, close WD+dMs can aid our understanding of the nature of common envelope evolution and its products (e.g. cataclysmic variables). We present the discovery and characterization of 186 new WD+dMs from the SUPERBLINK proper motion survey. These WD+dMs were discovered as a result of a search for post-common envelope binaries (PCEBs) and are part of an ongoing project to understand the space density and distribution of WD+dMs and PCEBs. In order to identify the sample of WD+dMs in SUPERBLINK, we utilized NUV-V and V-Ks colors. Here, we describe the discovery method and color selection, as well as present a detailed description of the properties of our sample based on two-component fits to our optical spectroscopy obtained at the MDM Observatory.

  4. Detection of a proteinaceous toxin in the brackishwater clam (Corbicula japonica).

    PubMed

    Shiomi, K; Arita, J; Nagashima, Y; Shinagawa, A

    1995-05-01

    Water extracts from the brackishwater clam (Corbicula japonica) were found to be lethal to mice upon i.v. injection. Muscular tissues (foot muscle, adductor muscle, mantle muscle, mantle and siphon) were all toxic while gill and viscera (mid-gut gland, testis and ovary) were nontoxic; the highest toxicity was observed with foot muscle. The toxin was judged to be a thermolabile, basic protein with a mol. wt. of about 13,000. PMID:7660374

  5. Water and sediment toxicity of freshwater mussels from population crashes of Asiatic clams

    SciTech Connect

    Scheller, J.L.; Cherry, D.S.; Yeager, M.M.; Lynde, S.R.; Shepard, N.D.

    1994-12-31

    The Clinch River watershed in Virginia contains one of the most diverse communities of freshwater bivalves or unionids in North America. These communities are becoming depleted over the past few decades due to various point (industrial, municipal) and nonpoint (roadside and agricultural runoff) discharges. By the latter 1980`s, the Asiatic clam (Corbicula fluminea) had invaded most reaches of this system and may be becoming a contributing factor to the demise of native mussels by the natural release of toxic ammonia from dense population crashes during late summer, low flow conditions. When densities surpassed 1,500 clams/m{sup 2}, crashes resulting in >99% mortality have been observed in various areas of the river. Total ammonia release from dying clams reached and sustained 70 mg/L for several days in laboratory artificial stream experiments. These ammonia levels resulted in acute toxicity and reproductive chronic impairment to Daphnia magna in 10-day sediment toxicity tests. Pediveliger larvae of Corbicula were acutely sensitive (48 hr LC{sub 50}) to 1.72 mg/L total ammonia (O.05 mg/L unionized), mortality was 100% to juvenile and adult clams in 9 to 13 days at 16.1 mg/L total (0.74 mg/L unionized ammonia). Mussel glochidia were sensitive to 24-hr ammonia exposures (LC{sub 50} = 3.29 and 0.11 mg/L as total and unionized ammonia, respectively). Juvenile and adult mussels are predicted to be less sensitive members of the unionid life cycle as observed from earlier studies involving copper toxicity in the Clinch River.

  6. Polycyclic aromatic hydrocarbons in clams, sediments, and seawater from the Great Barrier Reef region, Australia

    SciTech Connect

    Bagg, J.; Smith, J.D. )

    1988-09-01

    On the Great Barrier Reef actively growing organisms occur mainly in shallow water, between the low-water mark and about 5m depth. The effects of hydrocarbon pollution either from discharge into the sea or run-off from the shore might be expected to be most significantly at air/water or solid/water interfaces and so the earliest indications of contamination are likely to be found in species that live in this vulnerable zone. For this reason the clam Tridacna maxima which is found in the intertidal region was chosen to be analyzed for PAH content. This clam occurs in adequate numbers along the entire length of the Great Barrier Reef and yields enough tissue to permit detection of PAH at very low concentrations. In addition during collection their shells close so that the chance of significant contamination during transport is very small. Clams were taken from a number of sites including isolated reefs such as John Brewer Reef, the research stations, Heron and Lizard Islands, and a tourist resort, Green Island. At all these sites sediments were analyzed for PAH and at Green Island, in addition, seawater was analyzed.

  7. Effects of storage, processing and proteolytic digestion on microcystin-LR concentration in edible clams.

    PubMed

    Freitas, Marisa; Azevedo, Joana; Carvalho, Antnio Paulo; Campos, Alexandre; Vasconcelos, Vitor

    2014-04-01

    Accumulation of microcystin-LR (MC-LR) in edible aquatic organisms, particularly in bivalves, is widely documented. In this study, the effects of food storage and processing conditions on the free MC-LR concentration in clams (Corbicula fluminea) fed MC-LR-producing Microcystisaeruginosa (110(5) cell/mL) for four days, and the bioaccessibility of MC-LR after in vitro proteolytic digestion were investigated. The concentration of free MC-LR in clams decreased sequentially over the time with unrefrigerated and refrigerated storage and increased with freezing storage. Overall, cooking for short periods of time resulted in a significantly higher concentration (P<0.05) of free MC-LR in clams, specifically microwave (MW) radiation treatment for 0.5 (57.5%) and 1 min (59%) and boiling treatment for 5 (163.4%) and 15 min (213.4%). The bioaccessibility of MC-LR after proteolytic digestion was reduced to 83%, potentially because of MC-LR degradation by pancreatic enzymes. Our results suggest that risk assessment based on direct comparison between MC-LR concentrations determined in raw food products and the tolerable daily intake (TDI) value set for the MC-LR might not be representative of true human exposure. PMID:24491263

  8. Proteomic and metabolomic responses of clam Ruditapes philippinarum to arsenic exposure under different salinities.

    PubMed

    Wu, Huifeng; Liu, Xiaoli; Zhang, Xingyan; Ji, Chenglong; Zhao, Jianmin; Yu, Junbao

    2013-07-15

    Arsenic (As) contamination is a severe problem in the intertidal zones of the Bohai Sea (China) with wide salinity variation. In the present study, we combined proteomics and metabolomics to characterize the differential responses of arsenic in clam Ruditapes philippinarum under different salinities (31.1, 23.3 and 15.6 psu). Both proteomic and metabolomic responses indicated that varying salinities could significantly affect the toxicological responses of clams to As. Metabolic biomarkers revealed that the environmentally relevant arsenic (20 ?g L(-1)) exposure induced disturbance in energy metabolism and/or osmotic regulation under different salinities, whereas protein biomarkers indicated oxidative stress, cellular injury and apoptosis and disturbance in energy metabolism. In addition, the up-regulated proteins including ATP synthase, succinyl-CoA synthetase and nucleoside diphosphate kinase were validated by related metabolites, succinate and ATP, which confirmed the disturbance in energy metabolism in clam gills at low salinity (15.6 psu). These findings provide important insights into toxicological effects of environmental contaminant at molecular levels using combined proteomics and metabolomics. PMID:23660018

  9. Molecular diversity and evolution of defensins in the manila clam Ruditapes philippinarum.

    PubMed

    Wang, Qing; Zhang, Linbao; Yang, Dinglong; Yu, Qian; Li, Fei; Cong, Ming; Ji, Chenglong; Wu, Huifeng; Zhao, Jianmin

    2015-11-01

    Four types of defensins were identified in Manila clam and designated as Rpdef1, Rpdef2, Rpdef3 and Rpdef4, which encoded a polypeptide of 49, 46, 45 and 42 amino acids, respectively. Sequence alignments indicated that Rpdef1 shared 46.9% identity with Rpdef2, 40.8% with Rpdef3, and 34.7% with Rpdef4. Analysis of transcript polymorphism showed that Rpdef3 accounted for about 60% frequency of Rpdefs occurrence in clams from three geographic origins (Dalian, Qingdao and Hangzhou). By quantitative real-time RT-PCR (qRT-PCR) analysis, the transcripts of Rpdefs were mainly detected in hemocytes and they responded sensitively to bacterial challenge in hemocytes. Evolutionary analysis indicated that all Rpdefs were under positive selection with positively selected basic amino acid residues detected in the C-terminal regions, which perhaps have a functional relevance by modifying the charge distribution of Rpdefs. The results also showed some lineages with dN/dS > 1, suggesting positive selection pressures existed in some lineages of phylogeny tree constructed by mollusk defensins. Overall, our results suggest that Rpdefs perhaps played important roles in host defense and positive selection is the major driving force in generating high diversity of defensins in the Manila clam. PMID:26363232

  10. University of Washington Airborne Studies in Support of the CLAMS-2001 Field Study

    NASA Technical Reports Server (NTRS)

    Hobbs, Peter V.

    2003-01-01

    The main activity under this grant was participation in the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) field study from 10 July through 2 August 2001. The Cloud and Aerosol Research Group (CARG) from the University of Washington (UW) flew its Convair-580 research aircraft on thirteen occasions, for a total of 45 research flight hours, in support of CLAMS. Some of the main accomplishments of these flights were: 1) Aerosol and trace gas measurements and sunphotometer measurements of aerosol optical depth and column water vapor and ozone from close to Ocean surface to approx. 10,000 ft off Delmarva Peninsula on various occasions; 2) Measurements of aerosol properties on seven occasions beneath the Terra satellite, once beneath AVHRR, and five times beneath the ER-2 aircraft; 3) Measurements of aerosol properties in the vicinity of the (CERES instrumented) Chesapeake Bay lighthouse (COVE) on nine occasions; 4) Use of the NASA Goddard Cloud Absorption Radiometer (CAR) to obtain measurements of BRDF of the ocean surface on fifteen occasions and over Great Dismal Swamp on two occasions; 5) Measurements of aerosol properties over instrumented buoys 44014, 44004, and 41001. 6) On July 17 (a CLAMS 'Golden Day') six aircraft, including the Convair-580 and ER-2, were stacked above the Chesapeake Bay lighthouse under clear skies at the time of the Terra overpass.

  11. Microstructure of nano-structured ODS CLAM steel by mechanical alloying and hot isostatic pressing

    NASA Astrophysics Data System (ADS)

    Lu, Chen-yang; Lu, Zheng; Liu, Chun-ming

    2013-11-01

    Oxide dispersion strengthened (ODS) China Low Activation Martensitic (CLAM) steel was prepared by mechanical alloying (MA) and hot isostatic pressing. The morphology and microstructure of MA powders were studied by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and laser diffraction scattering to optimize the milling time. The microstructure of nano-structured ODS CLAM steel was characterized by electron backscatter diffraction, atom probe tomography, and transmission electron microscopy. The results showed that, during mechanical alloying, the morphology of MA powders changes from an initial fine spherical shape to a coarse laminar shape (at 0.5 h) back to a fine near-spherical shape (after 20 h), and the alloying elements and yttria (Y) gradually dissolve into the iron (Fe) matrix. With increased milling time, the mean grain size decreases rapidly (from 0 to 3 h), then gradually (from 3 to 8 h), then remains constant thereafter. The average grain size of as-received ODS CLAM steel that has undergone hot isotopic pressing is 368 nm. High-density Y-Ti-O-rich nano-clusters, a few Y2Ti2O7 precipitates, and some Cr-Mn-rich precipitates are formed. The size of Y2Ti2O7 and Cr-Mn-rich precipitates increases with increasing temperature. The nano-clusters show excellent temperature stability.

  12. Accumulation of organochlorines in the European clam (Ruditapes decussatus) and sediment of the Oualidia lagoon (Morocco).

    PubMed

    Jayed, Maria; Benbrahim, Samir; Bakkas, Salem; Ramdani, Mohamed; Flower, Roger

    2015-05-01

    This study focused on the analysis of organochlorine pesticides and PCBs in tissue samples of the clam, Ruditapes decussatus, in the Oualidia lagoon. Tissue assays were conducted during February to December 2005 and sediment (October 2005) was also tested. 13 organochlorine compounds and eight PCBs congeners were investigated, is HCB, γ-HCH, chlordane, cis-chlordane and trans-nonachlor, DDT and its metabolites DDD, DDE, heptachlor, its epoxide, mirex and PCBs (PCB28 + 50, PCB52, PCB101, PCB 118, PCB138, PCB153, PCB180). Analysis of these compounds was performed using a gas chromatography capillary column and an electron capture detector. Organochlorine contamination of clams and sediments in the lagoon did not exceed tolerable thresholds according to European standards. The levels of tPCB, tDDT and tOCP in clams are high at 49.4, 22.2, and 7.1 ng g(-1) dw respectively. Concentrations of trans nonachlor and mirex are low compared to other chlorinated pesticides. PCB28 + 50, PCB52 and PCB101 show typical values in sediment, at 18.5, 10.8 and 17.8 ng g(-1) dw respectively. PMID:25829056

  13. Assessment of the toxicity of organochlorine pesticide endosulfan in clams Ruditapes philippinarum.

    PubMed

    Tao, Yanxia; Pan, Luqing; Zhang, Hui; Tian, Shuangmei

    2013-07-01

    This study is aimed at evaluating the effects of endosulfan in clams (Ruditapes philippinarum). For this purpose, a study was performed on clams exposed to 0.005, 0.05 and 0.5μg/L endosulfan for 15 days. S ubsequently, the level of ethoxyresorufin-O-deethylase (EROD) activity, glutathione-S-transferase (GST) activity, glutathione (GSH) content, superoxide dismutase (SOD) activity, lipid peroxidation (LPO) and DNA strand break was determined in gills and digestive glands. Among the parameters, endosulfan caused significant changes in induction of EROD activity and oxidative stress in clams R. philippinarum. The exposure to endosulfan increased the concentration of EROD, GST, GSH, MDA and decreased the concentration of SOD. Moreover, according to the correlation analysis results, the EROD activity and GSH content in digestive gland as well as GST activity, LPO and DNA damage in both tissues had excellent correlation with endosulfan concentration. These results provided information on potential biomarkers that could be effectively applied to the biomonitoring of aquatic ecosystem in areas susceptible to persistent organochlorine compounds contamination, and also information on toxic effects. PMID:23642779

  14. FORMATION OF DWARF SPHEROIDAL GALAXIES VIA MERGERS OF DISKY DWARFS

    SciTech Connect

    Kazantzidis, Stelios; Lokas, Ewa L.; Klimentowski, Jaroslaw; Mayer, Lucio; Knebe, Alexander

    2011-10-10

    We perform collisionless N-body simulations to investigate whether binary mergers between rotationally supported dwarfs can lead to the formation of dwarf spheroidal galaxies (dSphs). Our simulation campaign is based on a hybrid approach combining cosmological simulations and controlled numerical experiments. We select merger events from a Constrained Local Universe simulation of the Local Group (LG) and record the properties of the interacting dwarf-sized halos. This information is subsequently used to seed controlled experiments of binary encounters between dwarf galaxies consisting of exponential stellar disks embedded in cosmologically motivated dark matter halos. These simulations are designed to reproduce eight cosmological merger events, with initial masses of the interacting systems in the range {approx}(5-60) x 10{sup 7} M{sub sun}, occurring quite early in the history of the LG, more than 10 Gyr ago. We compute the properties of the merger remnants as a distant observer would and demonstrate that at least three of the simulated encounters produce systems with kinematic and structural properties akin to those of the classic dSphs in the LG. Tracing the history of the remnants in the cosmological simulation to z = 0, we find that two dSph-like objects remain isolated at distances {approx}> 800 kpc from either the Milky Way or M31. These systems constitute plausible counterparts of the remote dSphs Cetus and Tucana which reside in the LG outskirts, far from the tidal influence of the primary galaxies. We conclude that merging of rotationally supported dwarfs represents a viable mechanism for the formation of dSphs in the LG and similar environments.

  15. Wave-Induced Sediment Motion Beyond the Surf Zone: Case Study of Lubiatowo (Poland)

    NASA Astrophysics Data System (ADS)

    Cerkowniak, Grzegorz R.; Ostrowski, Rafa?; Stella, Magdalena

    2015-06-01

    The paper presents results of field and theoretical investigations of a natural sandy shore located near the IBW PAN Coastal Research Station in Lubiatowo (Poland, the south Baltic Sea). The study site displays multi-bar cross-shore profiles that intensively dissipate wave energy, mostly by breaking. The main field data comprise offshore wave parameters and three cross-shore bathymetric profiles. Waveinduced nearbed velocities and bed shear stresses are theoretically modelled for weak, moderate, strong and extreme storm conditions to determine sediment motion regimes at various locations on the seaward boundary of the surf zone. The paper contains a discussion on the depth of closure concept, according to which the offshore range of sea bottom changes can be determined by the extreme seasonal deep-water wave parameters.

  16. Assessing mobility and redistribution patterns of sand and oil agglomerates in the surf zone.

    PubMed

    Dalyander, P Soupy; Long, Joseph W; Plant, Nathaniel G; Thompson, David M

    2014-03-15

    Heavier-than-water sand and oil agglomerates that formed in the surf zone following the Deepwater Horizon oil spill continued to cause beach re-oiling 3years after initial stranding. To understand this phenomena and inform operational response now and for future spills, a numerical method to assess the mobility and alongshore movement of these "surface residual balls" (SRBs) was developed and applied to the Alabama and western Florida coasts. Alongshore flow and SRB mobility and potential flux were used to identify likely patterns of transport and deposition. Results indicate that under typical calm conditions, cm-size SRBs are unlikely to move alongshore, whereas mobility and transport is likely during storms. The greater mobility of sand compared to SRBs makes burial and exhumation of SRBs likely, and inlets were identified as probable SRB traps. Analysis of field data supports these model results. PMID:24503377

  17. "Couch surfing" of Latino foster care alumni: reliance on peers as social capital.

    PubMed

    Perez, Beatrix F; Romo, Harriett D

    2011-04-01

    Youth exiting foster care often experience difficulties transitioning into adulthood. This paper focuses on Latino foster care youth in a major southwestern U.S. city and addresses the importance of peer networks as a crucial form of social capital as youth leave foster care. Case studies illustrate experiences of foster care alumni ranging in age from 18 to 26. Findings suggest that lack of housing forces youth into residential mobility or "couch surfing" and episodes of homelessness. Familial connections continue to be important to Latino youth. When Latino youth are unsuccessful in re-establishing family relationships, survival is dependent upon peer social capital as youth move between extended family and friends, eventually relying upon peers for support. Recommendations are included. PMID:20570341

  18. Surf zone bathymetry and circulation predictions via data assimilation of remote sensing observations

    NASA Astrophysics Data System (ADS)

    Wilson, G. W.; Özkan-Haller, H. T.; Holman, R. A.; Haller, M. C.; Honegger, D. A.; Chickadel, C. C.

    2014-03-01

    Bathymetry is a major factor in determining nearshore and surf zone wave transformation and currents, yet is often poorly known. This can lead to inaccuracy in numerical model predictions. Here bathymetry is estimated as an uncertain parameter in a data assimilation system, using the ensemble Kalman filter (EnKF). The system is tested by assimilating several remote sensing data products, which were collected in September 2010 as part of a field experiment at the U.S. Army Corps of Engineers Field Research Facility (FRF) in Duck, NC. The results show that by assimilating remote sensing data alone, nearshore bathymetry can be estimated with good accuracy, and nearshore forecasts (e.g., the prediction of a rip current) can be improved. This suggests an application where a nearshore forecasting model could be implemented using only remote sensing data, without the explicit need for in situ data collection.

  19. How much velocity information is necessary to predict sediment suspension in the surf zone?

    USGS Publications Warehouse

    Jaffe, Bruce E.; Rubin, David M.; Sallenger, Asbury, Jr.

    1995-01-01

    Instantaneous horizontal water velocity, or velocity to a power, does not contain enough information to predict suspension in the surf zone. Unlike steady uniform flow, more one than one velocity is necessary to parameterize pick-up and mixing of sediment into the water column. Using a velocity history improves predictions of suspension by more carefully specifying flow conditions (including accelerations and changes in accelerations) responsible for suspension. Suspension in the future is better predicted than suspension at the same instant as velocity measurements. Incorporating such a lag between velocity and concentration improved predictions, with optimum lag time increasing with elevation above the sea bed. These lags are largely due to the time for an observed flow event to effect the bed and mix sediment upward.

  20. 3D reconstruction of a human heart fascicle using SurfDriver

    NASA Astrophysics Data System (ADS)

    Rader, Robert J.; Phillips, Steven J.; LaFollette, Paul S., Jr.

    2000-06-01

    The Temple University Medical School has a sequence of over 400 serial sections of adult normal ventricular human heart tissue, cut at 25 micrometer thickness. We used a Zeiss Ultraphot with a 4x planapo objective and a Pixera digital camera to make a series of 45 sequential montages to use in the 3D reconstruction of a fascicle (muscle bundle). We wrote custom software to merge 4 smaller image fields from each section into one composite image. We used SurfDriver software, developed by Scott Lozanoff of the University of Hawaii and David Moody of the University of Alberta, for registration, object boundary identification, and 3D surface reconstruction. We used an Epson Stylus Color 900 printer to get photo-quality prints. We describe the challenge and our solution to the following problems: image acquisition and digitization, image merge, alignment and registration, boundary identification, 3D surface reconstruction, 3D visualization and orientation, snapshot, and photo-quality prints.

  1. General Multivariate Linear Modeling of Surface Shapes Using SurfStat

    PubMed Central

    Chung, Moo K.; Worsley, Keith J.; Nacewicz, Brendon, M.; Dalton, Kim M.; Davidson, Richard J.

    2010-01-01

    Although there are many imaging studies on traditional ROI-based amygdala volumetry, there are very few studies on modeling amygdala shape variations. This paper present a unified computational and statistical framework for modeling amygdala shape variations in a clinical population. The weighted spherical harmonic representation is used as to parameterize, to smooth out, and to normalize amygdala surfaces. The representation is subsequently used as an input for multivariate linear models accounting for nuisance covariates such as age and brain size difference using SurfStat package that completely avoids the complexity of specifying design matrices. The methodology has been applied for quantifying abnormal local amygdala shape variations in 22 high functioning autistic subjects. PMID:20620211

  2. A Comparison between XBeach and Terrestrial Laser Measurements of Surf-Zone Hydrodynamics and Beach Morphology

    NASA Astrophysics Data System (ADS)

    Brodie, K. L.; Long, J. W.; Slocum, R.

    2012-12-01

    Accurate predictions of beach evolution and coastal inundation during both storms and quiescent times require numerical models which correctly handle wave runup and inner surf-zone processes, the principle drivers of sediment exchange between the beach and surf-zone. Field validation of models is often restricted to analyzing elevation change between surveys conducted "pre" and "post" storm, but lack the hydrodynamic and morphologic data throughout the duration of the storm event needed to assess the modeled physical processes. Even fewer data sets exist that provide continuous observations during quiescent time periods (weeks-months) when much of the beach is re-built after storms. Using an automated terrestrial laser scanner mounted in the dune at the Field Research Facility (FRF) in Duck, NC, we collected hourly 20-minute measurements of the elevation of the beach and inner surf-zone free-surface profile. These data enable simultaneous analysis of foreshore morphologic evolution, wave runup, and inner-surf zone wave and water level characteristics. The laser data is collected along a narrow profile in line with the FRF's cross-shore array of wave gauges which provide observations in 2-23m of water depth. Roughly 700 hours of semi-continuous laser observations from 26 Aug through 29 Sep 2011 (including the landfall of Hurricane Irene and offshore swell from Hurricane Katia and Tropical Storm Maria), and from 26 Oct through 13 Nov 2011 (during the arrival of multiple Nor'Easters), are used to analyze wave runup statistics and beach morphology change and are compared to model predictions from XBeach. Initial analysis of observational data revealed a strong tidal signal in de-tided runup statistics, such that the 2% exceedence runup elevation and mean swash elevation is higher at high tide than at low tide for a given wave condition. This was similar to the significant incident band wave height (HsIN) at the base of the foreshore (defined as the 98% exceedence elevation), which also showed a strong tidal dependence. Our results suggest that particularly during quiescent time periods, mean swash elevation (setup) and incident band swash scale best with HsIN, though correlations are slightly improved when beach foreshore slope is included (r^2 = 0.74 vs 0.71). These data suggest that increased or decreased breaking over the sandbar at low and high tides respectively may filter the amount of energy left in the incident band to be transferred to runup at the shoreline. Observed incident and infragravity band swash and wave statistics from the laser and nearshore wave gauges will be compared to modeled hydrodynamics from XBeach. Assessments of the modeled physics are performed during quiescent and storm time periods and we focus on the role that under/overpredicting these hydrodynamic quantities has in making accurate predictions of profile change.

  3. Assessing mobility and redistribution patterns of sand and oil agglomerates in the surf zone

    USGS Publications Warehouse

    Dalyander, P. Soupy; Long, Joesph W.; Plant, Nathaniel G.; Thompson, David M.

    2014-01-01

    Heavier-than-water sand and oil agglomerates that formed in the surf zone following the Deepwater Horizon oil spill continued to cause beach re-oiling 3 years after initial stranding. To understand this phenomena and inform operational response now and for future spills, a numerical method to assess the mobility and alongshore movement of these “surface residual balls” (SRBs) was developed and applied to the Alabama and western Florida coasts. Alongshore flow and SRB mobility and potential flux were used to identify likely patterns of transport and deposition. Results indicate that under typical calm conditions, cm-size SRBs are unlikely to move alongshore, whereas mobility and transport is likely during storms. The greater mobility of sand compared to SRBs makes burial and exhumation of SRBs likely, and inlets were identified as probable SRB traps. Analysis of field data supports these model results.

  4. SURFING: A Program for Precise Determination of Sample Position in Stress Measurements Via Neutron Diffraction

    SciTech Connect

    Wang, D.-Q.

    2000-08-08

    Precise determination of the specimen position relative to the sampling volume for texture and stress measurements by neutron diffraction is difficult or sometimes impossible using only optical devices due to large or irregular sample dimensions and/or complicated shape of the sampling volume. The knowledge of the shape and size of the sampling volume allows development of a general mathematical model for the intensity variation with a parallelogram-shape sampling volume moving from outside to inside the specimen for both transmission and reflection geometric set-ups. Both fixed slits and radial collimators are options in defining the geometrical setup. The attenuation by the sample also has been taken into account in this model. Experimental results agree well with the model calculations. The program SURFING is based on the model calculation and was written in Labwindows/CVI{copyright}.

  5. Brown dwarfs as dark galactic halos

    NASA Technical Reports Server (NTRS)

    Adams, Fred C.; Walker, Terry P.

    1990-01-01

    The possibility that the dark matter in galactic halos can consist of brown dwarf stars is considered. The radiative signature for such halos consisting solely of brown dwarfs is calculated, and the allowed range of brown dwarf masses, the initial mass function (IMF), the stellar properties, and the density distribution of the galactic halo are discussed. The prediction emission from the halo is compared with existing observations. It is found that, for any IMF of brown dwarfs below the deuterium burning limit, brown dwarf halos are consistent with observations. Brown dwarf halos cannot, however, explain the recently observed near-IR background. It is shown that future satellite missions will either detect brown dwarf halos or place tight constraints on the allowed range of the IMF.

  6. White dwarfs - the once and future suns

    SciTech Connect

    Trimble, V.

    1986-10-01

    The history and properties of white dwarfs (Bessel's conclusion that Sirius and Procyon have invisible companions, Clark's discovery of Sirius B, Adams and Russell's study of white dwarf spectra, Chandrasekhar's explanation of white dwarf structure by equations incorporating quantum mechanics and relativity) are treated. Formation of white dwarfs, degeneracy, binary white dwarfs (and novae and supernovae) are explained. A mystery nearly 50 years old regarding the spectrum of the star Greenwich +70 degrees-8247 has been solved: it involves a stationary line phenomenon and a magnetic field of 300-500 million gauss. Processes being studied in white dwarfs and white dwarf models include gravitational settling, accretion, dredge-up, radiation pressure, and diffusive hydrogen burning.

  7. Chemolithotrophy in the continental deep subsurface: Sanford Underground Research Facility (SURF), USA

    PubMed Central

    Osburn, Magdalena R.; LaRowe, Douglas E.; Momper, Lily M.; Amend, Jan P.

    2014-01-01

    The deep subsurface is an enormous repository of microbial life. However, the metabolic capabilities of these microorganisms and the degree to which they are dependent on surface processes are largely unknown. Due to the logistical difficulty of sampling and inherent heterogeneity, the microbial populations of the terrestrial subsurface are poorly characterized. In an effort to better understand the biogeochemistry of deep terrestrial habitats, we evaluate the energetic yield of chemolithotrophic metabolisms and microbial diversity in the Sanford Underground Research Facility (SURF) in the former Homestake Gold Mine, SD, USA. Geochemical data, energetic modeling, and DNA sequencing were combined with principle component analysis to describe this deep (down to 8100 ft below surface), terrestrial environment. SURF provides access into an iron-rich Paleoproterozoic metasedimentary deposit that contains deeply circulating groundwater. Geochemical analyses of subsurface fluids reveal enormous geochemical diversity ranging widely in salinity, oxidation state (ORP 330 to −328 mV), and concentrations of redox sensitive species (e.g., Fe2+ from near 0 to 6.2 mg/L and Σ S2- from 7 to 2778μg/L). As a direct result of this compositional buffet, Gibbs energy calculations reveal an abundance of energy for microorganisms from the oxidation of sulfur, iron, nitrogen, methane, and manganese. Pyrotag DNA sequencing reveals diverse communities of chemolithoautotrophs, thermophiles, aerobic and anaerobic heterotrophs, and numerous uncultivated clades. Extrapolated across the mine footprint, these data suggest a complex spatial mosaic of subsurface primary productivity that is in good agreement with predicted energy yields. Notably, we report Gibbs energy normalized both per mole of reaction and per kg fluid (energy density) and find the later to be more consistent with observed physiologies and environmental conditions. Further application of this approach will significantly expand our understanding of the deep terrestrial biosphere. PMID:25429287

  8. Numerical modeling of surf zone dynamics under weakly plunging breakers with SPH method

    NASA Astrophysics Data System (ADS)

    Makris, Christos V.; Memos, Constantine D.; Krestenitis, Yannis N.

    2016-02-01

    The wave breaking of weak plungers over a relatively mild slope is investigated in this paper. Numerical modeling aspects are studied, concerning the propagation and breaking of shore-normal, nonlinear and regular waves. The two-dimensional (2-D) kinematics and dynamics (fluctuating flow features and large 2-D eddies) of the wave-induced flow on a vertical cross-section over the entire surf zone are simulated with the use of Smoothed Particle Hydrodynamics (SPH). The academic 'open source' code SPHysics v.2 is employed and the viscosity treatment is based on a Sub-Particle Scale (SPS) approach, similarly to the Large Eddy Simulations (LES) concept. Thorough analysis of the turbulent flow scales determines the necessary refinement of the spatial resolution. The initial particle discretization reaches down to the demarcation point between integral turbulence length scales and Taylor micro-scales. A convolution-type integration method is implemented for the transformation of scattered Lagrangian particle data to Eulerian values at fixed gauges. A heuristic technique of ensemble-averaging is used for the discrimination of the fluctuating flow components from coherent structures and ordered wave motion. Comparisons between numerical and experimental data give encouraging results for several wave features. The wave-induced mean flows are simulated plausibly, and even the 'streaming' effect near the bed is reproduced. The recurring vorticity patterns are derived, and coherent 2-D structures inside the surf zone are identified. Fourier spectral analysis of velocities reveals isotropy of 2-D fluctuating dynamics up to rather high frequencies in shear intensified regions. The simulated Reynolds stresses follow patterns that define the characteristic mechanism of wave breaking for weak plungers. Persisting discrepancies at the incipient breaking region confirm the need for fine, massively 'parallel' 3-D SPS-SPH simulations.

  9. Growth and Histological Effects to Protothaca staminea (Littleneck Clam) of Long-Term Exposure to Chlorinated Sea Water

    SciTech Connect

    Gibson, C. I.; Hillman, A. E.; Wilkinson, P.; Woodruff, D. L.

    1980-08-01

    There has been considerable concern about the potential for long-term effects to marine organisms from chlorinated sea water. As part of a larger study to investigate the effects of materials resulting from seawater chlorination on marine organisms, groups of littleneck clams, Protothaca staminea, were exposed to sea water that had been chlorinated. Two experiments were conducted. In one test, groups of littleneck clams were exposed to dilutions of chlorinated sea water that had average chlorine produced oxidant (CPO) concentrations of 16 {micro}g/l or less. In the second test, groups of clams were exposed to chlorinated seawater-unchlorinated seawater mixtures that had target CPO concentrations of 0, 6, 12, 25, 50 and 100 {micro}g/l. In the first experiment, length measurements were made on all clams at approximately one-month intervals for three months. In the second test, length, weight, depth, width and edge etching were used to measure growth, and subsamples were harvested and measured at one-month intervals. In addition, clams were preserved for histological examination. The clams in the first experiment all had negative growth. In the second test, growth was inhibited under all conditions through the first four months of exposure. During the last four months, there was positive signs of growth at the 0, 6 and 12 {micro}g/l CPO test conditions. Histological examination indicates that P. staminea does not adapt well to being held in aquaria. Most clams, tram all test and control conditions, showed evidence of necrosis at one month. This condition seemed to improve with longer exposure at lower CPO concentrations but persisted at CPO concentrations of 25 {micro}g/l and higher. Other histological effects were apparent at the higher exposure concentrations as the length of exposure increased.

  10. Giant Clams and Rising CO2: Light May Ameliorate Effects of Ocean Acidification on a Solar-Powered Animal

    PubMed Central

    Watson, Sue-Ann

    2015-01-01

    Global climate change and ocean acidification pose a serious threat to marine life. Marine invertebrates are particularly susceptible to ocean acidification, especially highly calcareous taxa such as molluscs, echinoderms and corals. The largest of all bivalve molluscs, giant clams, are already threatened by a variety of local pressures, including overharvesting, and are in decline worldwide. Several giant clam species are listed as ‘Vulnerable’ on the IUCN Red List of Threatened Species and now climate change and ocean acidification pose an additional threat to their conservation. Unlike most other molluscs, giant clams are ‘solar-powered’ animals containing photosynthetic algal symbionts suggesting that light could influence the effects of ocean acidification on these vulnerable animals. In this study, juvenile fluted giant clams Tridacna squamosa were exposed to three levels of carbon dioxide (CO2) (control ~400, mid ~650 and high ~950 μatm) and light (photosynthetically active radiation 35, 65 and 304 μmol photons m-2 s-1). Elevated CO2 projected for the end of this century (~650 and ~950 μatm) reduced giant clam survival and growth at mid-light levels. However, effects of CO2 on survival were absent at high-light, with 100% survival across all CO2 levels. Effects of CO2 on growth of surviving clams were lessened, but not removed, at high-light levels. Shell growth and total animal mass gain were still reduced at high-CO2. This study demonstrates the potential for light to alleviate effects of ocean acidification on survival and growth in a threatened calcareous marine invertebrate. Managing water quality (e.g. turbidity and sedimentation) in coastal areas to maintain water clarity may help ameliorate some negative effects of ocean acidification on giant clams and potentially other solar-powered calcifiers, such as hard corals. PMID:26083404

  11. Giant Clams and Rising CO2: Light May Ameliorate Effects of Ocean Acidification on a Solar-Powered Animal.

    PubMed

    Watson, Sue-Ann

    2015-01-01

    Global climate change and ocean acidification pose a serious threat to marine life. Marine invertebrates are particularly susceptible to ocean acidification, especially highly calcareous taxa such as molluscs, echinoderms and corals. The largest of all bivalve molluscs, giant clams, are already threatened by a variety of local pressures, including overharvesting, and are in decline worldwide. Several giant clam species are listed as 'Vulnerable' on the IUCN Red List of Threatened Species and now climate change and ocean acidification pose an additional threat to their conservation. Unlike most other molluscs, giant clams are 'solar-powered' animals containing photosynthetic algal symbionts suggesting that light could influence the effects of ocean acidification on these vulnerable animals. In this study, juvenile fluted giant clams Tridacna squamosa were exposed to three levels of carbon dioxide (CO2) (control ~400, mid ~650 and high ~950 μatm) and light (photosynthetically active radiation 35, 65 and 304 μmol photons m-2 s-1). Elevated CO2 projected for the end of this century (~650 and ~950 μatm) reduced giant clam survival and growth at mid-light levels. However, effects of CO2 on survival were absent at high-light, with 100% survival across all CO2 levels. Effects of CO2 on growth of surviving clams were lessened, but not removed, at high-light levels. Shell growth and total animal mass gain were still reduced at high-CO2. This study demonstrates the potential for light to alleviate effects of ocean acidification on survival and growth in a threatened calcareous marine invertebrate. Managing water quality (e.g. turbidity and sedimentation) in coastal areas to maintain water clarity may help ameliorate some negative effects of ocean acidification on giant clams and potentially other solar-powered calcifiers, such as hard corals. PMID:26083404

  12. Assimilation of cadmium, chromium, and zinc by the green mussel Perna viridis and the clam Ruditapes philippinarum

    SciTech Connect

    Chong, K.; Wang, W.X.

    2000-06-01

    The green mussel Perna viridis and the clam Ruditapes philippinarum have been frequently used as biomonitors of coastal contamination in subtropical and tropical waters, yet the physiological processes controlling metal uptake in these bivalves are unknown. Assimilation efficiency (AE) is an important physiological parameter quantifying metal bioavailability from ingested food. The authors determined the AEs of Cd, CR, and Zn in these bivalves feeding on five species of phytoplankton and one natural section. The influences of the cytoplasmic distribution of metals in the algal cells and the digestive physiology of bivalves on metal AEs were also examined. Among the three metals, Zn was generally assimilated at the highest efficiency, i.e., 21 to 36% in the mussels and 29 to 59% in the clams. Cr was the least assimilated metal, with AEs being 10 to 16% in the mussels and 11 to 24% in the clams. The AEs of Cd and Zn in the clams were 1.8 to 4.7 and 1.1 to 1.9 times higher, respectively, than the AEs in the mussels. Assimilation efficiencies of Cr were, however, comparable between the mussels and the clams. A positive significant relationship between the metal AE and the percent of metals in the algal cytoplasm was found only for Cd in the clams, suggesting that Cd fractionation in the algal cells influenced its assimilation. No significant relationship, however, was found for other metals in both bivalves. A significant relationship between Cr-assimilation efficiency and gut passage time (GPT) was documented in the mussels, indicating a higher assimilation when Cr was retained longer in the gut. There was also significant correlation of metal AEs among the three metals, which were probably subjected to the same digestive pathway in the bivalves. Their study demonstrated that both the green mussels and the clams were able to accumulate metals from ingested food source, and food quality appeared to have different effects on metal assimilation in different bivalve species.

  13. Pulsating Helium Atmosphere White Dwarfs

    NASA Astrophysics Data System (ADS)

    Provencal, Judith; Montgomery, Michael H.; Bischoff-Kim, Agnes; Shipman, Harry; Nitta, Atsuko; Whole Earth Telescope Collaboration

    2015-08-01

    The overwhelming majority of all stars currently on the main sequence as well as those from earlier generations will or have ended their stellar lives as white dwarf stars. White dwarfs are rich forensic laboratories linking the history and future evolution of our Galaxy. Their structure and atmospheric composition provide evidence of how the progenitors lived, how they evolved, and how they died. This information reveals details of processes governing the behavior of contemporary main sequence stars. Combined with their distribution in luminosity/temperature, white dwarfs strongly constrain models of galactic and cosmological evolution.GD358 is among the brightest (mv =13.7) and best studied of the pulsating white dwarfs. This helium atmoshere pulsator (DBV) has an extensive photometric database spanning 30 years, including nine multisite Whole Earth Telescope campaigns. GD358 exhibits a range of behaviors, from drastic changes in excited pulsation modes to variable multiplet splittings. We use GD358 as a template for an examination of the DBV class, combining photometric results with recent COS spectroscopy. The results present new questions concerning DB formation and evolution.

  14. The Physics of White Dwarfs.

    ERIC Educational Resources Information Center

    Van Horn, Hugh M.

    1979-01-01

    Describes the current understanding of the structure and evolution of the white dwarf stars that was gained as a result of the increasingly sensitive and detailed astronomical observations coupled with calculations of the properties of matter under extreme conditions. (Author/GA)

  15. THREE NEW ECLIPSING WHITE-DWARF-M-DWARF BINARIES DISCOVERED IN A SEARCH FOR TRANSITING PLANETS AROUND M-DWARFS

    SciTech Connect

    Law, Nicholas M.; Kraus, Adam L.; Street, Rachel; Fulton, Benjamin J.; Shporer, Avi; Lister, Tim; Hillenbrand, Lynne A.; Baranec, Christoph; Bui, Khanh; Davis, Jack T. C.; Dekany, Richard G.; Kulkarni, S. R.; Ofek, Eran O.; Bloom, Joshua S.; Cenko, S. Bradley; Filippenko, Alexei V.; Burse, Mahesh P.; Das, H. K.; Kasliwal, Mansi M.; Nugent, Peter; and others

    2012-10-01

    We present three new eclipsing white-dwarf/M-dwarf binary systems discovered during a search for transiting planets around M-dwarfs. Unlike most known eclipsing systems of this type, the optical and infrared emission is dominated by the M-dwarf components, and the systems have optical colors and discovery light curves consistent with being Jupiter-radius transiting planets around early M-dwarfs. We detail the PTF/M-dwarf transiting planet survey, part of the Palomar Transient Factory (PTF). We present a graphics processing unit (GPU)-based box-least-squares search for transits that runs approximately 8 Multiplication-Sign faster than similar algorithms implemented on general purpose systems. For the discovered systems, we decompose low-resolution spectra of the systems into white-dwarf and M-dwarf components, and use radial velocity measurements and cooling models to estimate masses and radii for the white dwarfs. The systems are compact, with periods between 0.35 and 0.45 days and semimajor axes of approximately 2 R{sub Sun} (0.01 AU). The M-dwarfs have masses of approximately 0.35 M{sub Sun }, and the white dwarfs have hydrogen-rich atmospheres with temperatures of around 8000 K and have masses of approximately 0.5 M{sub Sun }. We use the Robo-AO laser guide star adaptive optics system to tentatively identify one of the objects as a triple system. We also use high-cadence photometry to put an upper limit on the white-dwarf radius of 0.025 R{sub Sun} (95% confidence) in one of the systems. Accounting for our detection efficiency and geometric factors, we estimate that 0.08%{sub -0.05%}{sup +0.10%} (90% confidence) of M-dwarfs are in these short-period, post-common-envelope white-dwarf/M-dwarf binaries where the optical light is dominated by the M-dwarf. The lack of detections at shorter periods, despite near-100% detection efficiency for such systems, suggests that binaries including these relatively low-temperature white dwarfs are preferentially found at relatively large orbital radii. Similar eclipsing binary systems can have arbitrarily small eclipse depths in red bands and generate plausible small-planet-transit light curves. As such, these systems are a source of false positives for M-dwarf transiting planet searches. We present several ways to rapidly distinguish these binaries from transiting planet systems.

  16. Effects of temperature on hard clam (Mercenaria mercenaria) immunity and QPX (Quahog Parasite Unknown) disease development: I. Dynamics of QPX disease.

    PubMed

    Dahl, Soren F; Perrigault, Mickael; Liu, Qianqian; Collier, Jackie L; Barnes, Debra A; Allam, Bassem

    2011-02-01

    Quahog Parasite Unknown (QPX) causes disease and mortality in hard clams, Mercenaria mercenaria. Seasonality of QPX disease prevalence in the field and changes in QPX growth and survival in vitro suggest a role of temperature in the hard clam-QPX interaction and disease development. This study specifically examined the effect of temperature on QPX disease development and dynamics. Naturally and experimentally infected clams were separately maintained in the laboratory at 13C, 21C, or 27C for 4 months. Following this initial treatment, temperature was adjusted to 21C for 5 additional months to simulate seasonal changes of temperature in the field and to investigate the effect of temperature variations on QPX disease dynamics. Mortality was continuously monitored during the experiment and clams were sampled at 2, 4 and 9 months for the assessment of QPX disease prevalence and intensity using our standard histological and quantitative PCR techniques. Results demonstrated significantly higher QPX disease prevalence and intensity, as well as higher mortality, in naturally-infected clams maintained at 13C as compared to those held at 21C or 27C. Similarly, disease development was significantly higher in experimentally infected clams maintained at the colder temperature (70% prevalence after 4 months) as compared to those maintained under warmer conditions (<10%). Additionally, our results demonstrated an improvement in the condition of clams initially maintained at 13C for 4 months after transfer to 21C for 5 additional months, with a significant reduction of QPX prevalence (down to 19%). Interestingly, disease development or healing in clams maintained at different temperatures exhibited a strong relationship with clam defense status (jointly submitted paper) and highlighted the impact of temperature on clam activity and QPX disease dynamics. These findings should be taken into account for the timing of activities involving the monitoring, movement (e.g. relays, transplants) or grow out (e.g. commercial culture, municipal enhancement) of hard clams in enzootic areas. PMID:21112332

  17. Recorders of reef environment histories: stable isotopes in corals, giant clams, and calcareous algae

    NASA Astrophysics Data System (ADS)

    Aharon, Paul

    1991-06-01

    Time-series ?18O and ?13C records from cohabiting massive coral Porites australiensis and giant clam Tridacna gigas from the Great Barrier Reed of Australia, and from calcareous green algae in a core through modern Halimeda bioherm accreting in the eastern Java Sea, provide insights into the complex links between environmental factors and stable isotopes imprinted in these reef skeletal materials. The aragonitic coral and giant clam offer 20 years and 15 years of growth history, respectively. The giant clam yields mean ?18O and ?13C values of-0.50.5 and 2.20.2 ( n=67), which agree well with the predicted equilibrium values. The coral yields mean ?18O and ?13C values of-5.60.5 and-1.80.7 ( n=84), offering a striking example of kinetic and metabolic fractionation effects. Although both the coral and giant clam harbor symbionts and were exposed to a uniform ambient environment during their growth histories, their distinct isotopic compositions demonstrate dissimilar calcification pathways. The ?18O records contain periodicities corresponding to the alternating annual density bands revealed by X-radiography and optical transmitted light. Attenuation of the ?18O seasonal amplitudes occurring in the giant clam record 8 years after skeletal growth commenced is attributed to a changeover from fast to slow growth rates. Extreme seasonal ?18O amplitudes of up to 2.2 discerned in both the coral and giant clam records exceed the equivalent seasonal temperature contrast in the reef environment, and are caused by the combined effect of rainfall and evaporation during the monsoon and dry seasons, respectively. Thus in addition of being useful temperature recorders, reef skeletal material of sufficient longevity, such as Porites and Tridacna, may also indicate rainfall variations. Changing growth rates, determined from the annual growth bands, may exert a primary control on the coral ?13C record which shows a remarkable negative shift of 1.7 over its growth history, by comparison with only 0.15 negative shift in the contemporaneous giant clam record. Use of coral ?13C records as proxies of fossil fuel CO2 uptake by the ocean must be regarded with caution. The ?18O and ?13C records from Halimeda are remarkably uniform over 1000 years of bioherm accretion history (?18O=-1.70.2; ?13C=3.90.1, n=28), in spite of variable Mg-calcite cements present in the utricles. Most of the cement infilling is probably syndepositional, and both the Halimeda aragonite and the Mg-calcite cements containign 12.3 mole % MgCO3 are deposited in isotopic equilibrium. Therefore, in favorable circumstances these algal skeletal remains may act as the shallow water analogs of benthic foraminifera in deep sea sediments in recording ambient sea water isotopic composition and temperature.

  18. RESOLVED SPECTROSCOPY OF A BROWN DWARF BINARY AT THE T DWARF/Y DWARF TRANSITION

    SciTech Connect

    Burgasser, Adam J.; Gelino, Christopher R.; Kirkpatrick, J. Davy; Cushing, Michael C.

    2012-01-20

    We report resolved near-infrared imaging and spectroscopic observations of the T8.5 binary WISEP J045853.90+643452.6AB obtained with Keck/NIRC2, Keck/OSIRIS, and the Keck Laser Guide Star Adaptive Optics system. These data confirm common proper and radial motion for the two components, and we see the first indications of orbital motion (mostly radial) for this system. H-band spectroscopy identifies both components as very late type brown dwarfs with strong H{sub 2}O and CH{sub 4} absorption. The spectrum of WISE J0458+6434B also exhibits a compelling signature of NH{sub 3} absorption over 1.52-1.54 {mu}m when compared to the T9 dwarf UGPS J072227.51-054031.2. Comparison to T8-Y0 spectral standards and H-band spectral indices indicate classifications of T8.5 and T9.5 for these two components, approaching the boundary between the T dwarf and Y dwarf spectral classes.

  19. Purification and characterization of hemagglutinating proteins from Poker-chip Venus (Meretrix lusoria) and Corbicula clam (Corbicula fluminea).

    PubMed

    Cheng, Chin-Fu; Hung, Shao-Wen; Chang, Yung-Chung; Chen, Ming-Hui; Chang, Chen-Hsuan; Tsou, Li-Tse; Tu, Ching-Yu; Lin, Yu-Hsing; Liu, Pan-Chen; Lin, Shiun-Long; Wang, Way-Shyan

    2012-01-01

    Hemagglutinating proteins (HAPs) were purified from Poker-chip Venus (Meretrix lusoria) and Corbicula clam (Corbicula fluminea) using gel-filtration chromatography on a Sephacryl S-300 column. The molecular weights of the HAPs obtained from Poker-chip Venus and Corbicula clam were 358?kDa and 380?kDa, respectively. Purified HAP from Poker-chip Venus yielded two subunits with molecular weights of 26?kDa and 29?kDa. However, only one HAP subunit was purified from Corbicula clam, and its molecular weight was 32?kDa. The two Poker-chip Venus HAPs possessed hemagglutinating ability (HAA) for erythrocytes of some vertebrate animal species, especially tilapia. Moreover, HAA of the HAP purified from Poker-chip Venus was higher than that of the HAP of Corbicula clam. Furthermore, Poker-chip Venus HAPs possessed better HAA at a pH higher than 7.0. When the temperature was at 4C-10C or the salinity was less than 0.5, the two Poker-chip Venus HAPs possessed better HAA compared with that of Corbicula clam. PMID:22666167

  20. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Pacific Northwest): Pacific razor clam

    SciTech Connect

    Lassuy, D.R.; Simons, D.

    1989-01-01

    Species profiles are literature summaries of the taxonomy, morphology, distribution, life history, ecological role, fishery (when appropriate), and environmental requirements of coastal aquatic species. They are prepared to assist coastal managers, engineers, and biologists in the gathering of information pertinent to coastal development activities. The Pacific razor clam has a long history of human consumption on the West Coast. Turn-of-the-century commercial canning operations have given way to today's extensive recreational fishery. Razor clams spawn in late spring and early summer in the Pacific Northwest and recruit to flat, sandy beaches in late summer. Greatest densities of large clams occur in the lower intertidal zone. Razor clams grow and mature faster but attain a lower maximum size and age in the southern part of their range. They are noted for their unusual ability to dig very rapidly through the subsurface sand. Silt-generating activities should be avoided in the vicinity of razor clam beaches, as juveniles are susceptible to suffocation. 32 refs., 2 figs., 2 tabs.

  1. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (mid-Atlantic). Hard clam. [Mercenaria mercenaria

    SciTech Connect

    Stanley, J.G.

    1985-02-01

    This species profile is a literature summary on the taxonomy, morphology, range, life history, and environmental requirements of the hard clam (Mercenaria mercenaria). The species profiles are designed to assist in environmental impact assessments. The hard clam is the most extensively distributed commercial clam in the United States. They spawn offshore in summer when water temperatures are between 18/sup 0/ and 30/sup 0/C. The eggs and larvae are carried by currents into estuaries, where seed clams set on sand or pebbles. Seed clams that lack cover of shells or stone largely perish because of predation. Adults filter-feed on phytoplankton and particulate material. Adults survive temperatures of -6/sup 0/ to 30/sup 0/C and salinities of 10 to 35 ppt, and can withstand freshwater for several days by closing their shell. When the shell is closed, they must tolerate anoxic conditions, and they survive less than 1 mg/1 oxygen in the water for several days. Even the larvae tolerate 0.5 mg/1 of oxygen. 130 refs., 4 figs., 1 tab.

  2. Purification and Characterization of Hemagglutinating Proteins from Poker-Chip Venus (Meretrix lusoria) and Corbicula Clam (Corbicula fluminea)

    PubMed Central

    Cheng, Chin-Fu; Hung, Shao-Wen; Chang, Yung-Chung; Chen, Ming-Hui; Chang, Chen-Hsuan; Tsou, Li-Tse; Tu, Ching-Yu; Lin, Yu-Hsing; Liu, Pan-Chen; Lin, Shiun-Long; Wang, Way-Shyan

    2012-01-01

    Hemagglutinating proteins (HAPs) were purified from Poker-chip Venus (Meretrix lusoria) and Corbicula clam (Corbicula fluminea) using gel-filtration chromatography on a Sephacryl S-300 column. The molecular weights of the HAPs obtained from Poker-chip Venus and Corbicula clam were 358?kDa and 380?kDa, respectively. Purified HAP from Poker-chip Venus yielded two subunits with molecular weights of 26?kDa and 29?kDa. However, only one HAP subunit was purified from Corbicula clam, and its molecular weight was 32?kDa. The two Poker-chip Venus HAPs possessed hemagglutinating ability (HAA) for erythrocytes of some vertebrate animal species, especially tilapia. Moreover, HAA of the HAP purified from Poker-chip Venus was higher than that of the HAP of Corbicula clam. Furthermore, Poker-chip Venus HAPs possessed better HAA at a pH higher than 7.0. When the temperature was at 4C10C or the salinity was less than 0.5, the two Poker-chip Venus HAPs possessed better HAA compared with that of Corbicula clam. PMID:22666167

  3. NMR-based metabolomic investigations on the differential responses in adductor muscles from two pedigrees of Manila clam Ruditapes philippinarum to Cadmium and Zinc.

    PubMed

    Wu, Huifeng; Liu, Xiaoli; Zhao, Jianmin; Yu, Junbao

    2011-01-01

    Manila clam Ruditapes philippinarum is one of the most important economic species in shellfishery in China due to its wide geographic distribution and high tolerance to environmental changes (e.g., salinity, temperature). In addition, Manila clam is a good biomonitor/bioindicator in "Mussel Watch Programs" and marine environmental toxicology. However, there are several pedigrees of R. philippinarum distributed in the marine environment in China. No attention has been paid to the biological differences between various pedigrees of Manila clams, which may introduce undesirable biological variation in toxicology studies. In this study, we applied NMR-based metabolomics to detect the biological differences in two main pedigrees (White and Zebra) of R. philippinarum and their differential responses to heavy metal exposures (Cadmium and Zinc) using adductor muscle as a target tissue to define one sensitive pedigree of R. philippinarum as biomonitor for heavy metals. Our results indicated that there were significant metabolic differences in adductor muscle tissues between White and Zebra clams, including higher levels of alanine, glutamine, hypotaurine, phosphocholine and homarine in White clam muscles and higher levels of branched chain amino acids (valine, leucine and isoleucine), succinate and 4-aminobutyrate in Zebra clam muscles, respectively. Differential metabolic responses to heavy metals between White and Zebra clams were also found. Overall, we concluded that White pedigree of clam could be a preferable bioindicator/biomonitor in marine toxicology studies and for marine heavy metals based on the relatively high sensitivity to heavy metals. PMID:22131959

  4. A DESCRIPTIVE EVALUATION OF THE EFFECTS OF NUMBER 2 FUEL OIL ON THE TISSUES OF THE SOFT SHELL CLAM 'MYA ARENARIA L'

    EPA Science Inventory

    Soft shell clams were exposed over 28 days at 4C to single dose concentrations of 10, 50 and 100 ppm No. 2 fuel oil emulsion to simulate a potential winter oil spill. The hydrocarbon content of the water column was monitored on a weekly basis. Clams were removed and their histolo...

  5. COMPARISON OF AQUEOUS AND SOLID-PHASE UPTAKE FOR HEXACHLOROBENZENE IN THE TELLINID CLAM MACOMA NASUTA (CONRAD): A MASS BALANCE APPROACH

    EPA Science Inventory

    The uptake of sediment-associated hexachlorobenzene (HCB) by the deposit-feeding clam Macoma nasuta (Conrad) was determined using a clam ventilation chamber. lams were exposed to [14C]HCB-dosed sediment, and the 14C amounts were measured in inhalant and exhalant waters, fecal pel...

  6. Norovirus recognizes histo-blood group antigens on the gastrointestinal cells of clams, mussels and oysters: a possible mechanism of bio-accumulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study, a set of HBGA-specific monoclonal antibodies (MAbs) was used to detect the expression of HBGA in three oyster species consumed commonly (pacific, virginica, and kumamato), and manila clams, and blue mussels. rNVLPs were applied to plate coated with oyster, mussel or clam GI homogena...

  7. Shaping the Brown Dwarf Desert: Predicting the Primordial Brown Dwarf Binary Distributions from Turbulent Fragmentation

    NASA Astrophysics Data System (ADS)

    Jumper, Peter; Fisher, Robert

    2012-03-01

    Brown dwarfs are failed stars, with masses too low to undergo hydrogen nuclear burning. While the first incontrovertible brown dwarf was detected observationally in 1995, their formation mechanism and the origin of many of their physical properties remain open questions. The absence of brown dwarf companions in close orbits (less than several AU) to solar-type primary stars in binary systems poses a major problem. Astronomers have termed this sparsity of nearby brown dwarf companions in binary systems the brown dwarf desert. We demonstrate that direct fragmentation of the parent gaseous turbulent giant molecular cloud cores naturally gives rise to widely-separated stellar-brown dwarf binary systems. We also show that this fragmentation produces narrowly-separated brown dwarf - brown dwarf binary systems. Additionally, these results support the observation that the minimum binding energy of systems increases with decreasing system mass.

  8. Evaluation of Using Caged Clams to Monitor Contaminated Groundwater Exposure in the Near-Shore Environment of the Hanford Site 300 Area

    SciTech Connect

    Larson, Kyle B.; Poston, Ted M.; Tiller, Brett L.

    2008-01-31

    The Asiatic clam (Corbicula fluminea) has been identified as an indicator species for locating and monitoring contaminated groundwater in the Columbia River. Pacific Northwest National Laboratory conducted a field study to explore the use of caged Asiatic clams to monitor contaminated groundwater upwelling in the 300 Area near-shore environment and assess seasonal differences in uranium uptake in relation to seasonal flow regimes of the Columbia River. Additional objectives included examining the potential effects of uranium accumulation on growth, survival, and tissue condition of the clams. This report documents the field conditions and procedures, laboratory procedures, and statistical analyses used in collecting samples and processing the data. Detailed results are presented and illustrated, followed by a discussion comparing uranium concentrations in Asiatic clams collected at the 300 Area and describing the relationship between river discharge, groundwater indicators, and uranium in clams. Growth and survival, histology, and other sources of environmental variation also are discussed.

  9. Selenium and stable isotopes of carbon and nitrogen in the benthic clam Corbula amurensis from Northern San Francisco Bay, California: May 1995-February 2010

    USGS Publications Warehouse

    Kleckner, Amy E.; Stewart, A. Robin; Luoma, Samuel N.

    2010-01-01

    The clam-based food webs of San Francisco Bay, California efficiently bioaccumlate selenium and thus provide pathways for exposure to predators important to the estuary. This study documents changes in monthly selenium concentrations for the clam Corbula amurensis, a keystone species of the estuary, at five locations in northern San Francisco Bay from 1995 through 2010. Samples were collected from designated U.S. Geological Survey stations and prepared and analyzed by U.S. Geological Survey methods. Stable isotopes of carbon and nitrogen in soft tissues of clams also were measured as an indicator of sources of selenium for the clams. These monitoring data indicate that clam selenium concentrations ranged from a low of 2 to a high of 22 micrograms per gram dry weight with strong spatial and seasonal variation over the period of study.

  10. [The study of M dwarf spectral classification].

    PubMed

    Yi, Zhen-Ping; Pan, Jing-Chang; Luo, A-Li

    2013-08-01

    As the most common stars in the galaxy, M dwarfs can be used to trace the structure and evolution of the Milky Way. Besides, investigating M dwarfs is important for searching for habitability of extrasolar planets orbiting M dwarfs. Spectral classification of M dwarfs is a fundamental work. The authors used DR7 M dwarf sample of SLOAN to extract important features from the range of 600-900 nm by random forest method. Compared to the features used in Hammer Code, the authors added three new indices. Our test showed that the improved Hammer with new indices is more accurate. Our method has been applied to classify M dwarf spectra of LAMOST. PMID:24159887

  11. A Catalog of Nearby Ultracool Dwarfs

    NASA Astrophysics Data System (ADS)

    Tanner, Angelle M.; Ramos, Christopher; Gagne, Jonathan; Riedel, Adric R.; Henry, Todd J.; Recons

    2015-01-01

    This work consists of a compilation and analysis of nearby (d < 25 pc) ultracool dwarfs ( < M6V) with a focus on brown dwarfs. We have incorporated newly discovered (post 1991) cool companions to Gliese-Jahrei stars that had been previously been undetectable; with the advent of wide-field CCD cameras and all-sky surveys, numerous ultracool dwarfs have since been discovered with such missions as 2MASS, the Deep Near-Infrared Southern Sky Survey, the Wide-field Infrared Survey, and the Sloan Digital Sky Survey. We then expanded our efforts to include isolated ultracool dwarfs and other nearby multiple systems with at least one ultracool dwarf component. In this poster we will summarize the components of the catalog and describe physical trends we are able to extract from this large compilation of brown dwarf properties.

  12. Neutral hydrogen detection survey of dwarf galaxies. II. Faint Virgo dwarfs and a field sample

    SciTech Connect

    Hoffman, G.L.; Williams, H.L.; Salpeter, E.E.; Sandage, A.; Binggeli, B. Delaware Univ., Newark Cornell Univ., Ithaca, NY Mount Wilson and Las Campanas Observatories, Pasadena, CA Arcetri, Osservatorio Astrofisico, Florence )

    1989-12-01

    Neutral hydrogen spectra are presented for 53 faint dwarf galaxies in Virgo, completing the Arecibo survey of all late-type dwarfs in the Virgo Cluster Catalog, and for 42 dwarf galaxies from the field sample of Binggeli et al. (1989). For detected galaxies, heliocentric velocities, profile widths, and single-beam fluxes are tabulated. The field sample has been used to investigate the field luminosity function and the clustering of dwarf galaxies vis-a-vis bright galaxies. 31 refs.

  13. Metabolic responses in gills of Manila clam Ruditapes philippinarum exposed to copper using NMR-based metabolomics.

    PubMed

    Zhang, Linbao; Liu, Xiaoli; You, Liping; Zhou, Di; Wu, Huifeng; Li, Lianzhen; Zhao, Jianmin; Feng, Jianghua; Yu, Junbao

    2011-07-01

    Copper is an important heavy metal contaminant with high ecological risk in the Bohai Sea. In this study, the metabolic responses in the bioindicator, Manila clam (Ruditapes philippinarum), to the environmentally relevant copper exposures were characterized using NMR-based metabolomics. The significant metabolic changes corresponding to copper exposures were related to osmolytes, intermediates of the Krebs cycle and amino acids, such as the increase in homarine, branched chain amino acids and decrease in succinate, alanine and dimethylamine in the copper-exposed clam gills during 96 h exposure period. Overall, Cu may lead to the disturbances in osmotic regulation and energy metabolism in clams during 96 h experimental period. These results demonstrate that NMR-based metabolomics is applicable for the discovery of metabolic biomarkers which could be used to elucidate the toxicological mechanisms of marine heavy metal contaminants. PMID:21632102

  14. Verification of the effect of surface preparation on Hot Isostatic Pressing diffusion bonding joints of CLAM steel

    NASA Astrophysics Data System (ADS)

    Zhao, Yanyun; Li, Chunjing; Huang, Bo; Liu, Shaojun; Huang, Qunying

    2014-12-01

    Hot Isostatic Pressing (HIP) diffusion bonding with CLAM steel is the primary candidate fabrication technique for the first wall (FW) of DFLL-TBM. Surface state is one of the key factors for the joints quality. The effect of surface state prepared with grinder and miller on HIP diffusion bonding joints of CLAM steel was investigated. HIP diffusion bonding was performed at 140 MPa and 1373 K within 3 h. The mechanical properties of the joints were investigated with instrumented Charpy V-notch impact tests and the microstructures of the joints were analyzed with scanning electron microscopy (SEM). The results showed that the milled samples with fine surface roughness were more suitable for CLAM steel HIP diffusion bonding.

  15. Environmentally realistic concentrations of the antibiotic Trimethoprim affect haemocyte parameters but not antioxidant enzyme activities in the clam Ruditapes philippinarum.

    PubMed

    Matozzo, Valerio; De Notaris, Chiara; Finos, Livio; Filippini, Raffaella; Piovan, Anna

    2015-11-01

    Several biomarkers were measured to evaluate the effects of Trimethoprim (TMP; 300, 600 and 900ng/L) in the clam Ruditapes philippinarum after exposure for 1, 3 and 7 days. The actual TMP concentrations were also measured in the experimental tanks. The total haemocyte count significantly increased in 7 day-exposed clams, whereas alterations in haemocyte volume were observed after 1 and 3 days of exposure. Haemocyte proliferation was increased significantly in animals exposed for 1 and 7 days, whereas haemocyte lysate lysozyme activity decreased significantly after 1 and 3 days. In addition, TMP significantly increased haemolymph lactate dehydrogenase activity after 3 and 7 days. Regarding antioxidant enzymes, only a significant time-dependent effect on CAT activity was recorded. This study demonstrated that environmentally realistic concentrations of TMP affect haemocyte parameters in clams, suggesting that haemocytes are a useful cellular model for the assessment of the impact of TMP on bivalves. PMID:26301695

  16. Accumulation and tissue distribution of radioiodine ( sup 131 I) from algal phytoplankton by the freshwater clam Corbicula manilensis

    SciTech Connect

    Cuvin-Aralar, Ma.L.A. ); Umaly, R.C. )

    1991-12-01

    Radioactive wastes discharged from establishments involved in the use of radioisotopes such as nuclear-powered industries, tracer research and nuclear medicine are a potential public health hazard. Such wastes contain radionuclides, particularly Iodine-131 ({sup 131}I), produced in fission with a yield of about 3%. Radionuclides in waste waters are known to be taken up by molluscs such as mussels, oysters, and clams. This study aims to determine the uptake of {sup 131}I from algal phytoplankton (Chroococcus dispersus) fed to the freshwater clam Corbicula manilensis as well as the organ/tissue distribution. The results will be compared with a previous study on {sup 131}I uptake from water by the same clams.

  17. Diffusion Coefficients in White Dwarfs

    NASA Astrophysics Data System (ADS)

    Saumon, D.; Starrett, C. E.; Daligault, J.

    2015-06-01

    Models of diffusion in white dwarfs universally rely on the coefficients calculated by Paquette et al. (1986). We present new calculations of diffusion coefficients based on an advanced microscopic theory of dense plasmas and a numerical simulation approach that intrinsically accounts for multiple collisions. Our method is validated against a state-of-the-art method and we present results for the diffusion of carbon ions in a helium plasma.

  18. Formation of Ultra-compact Blue Dwarf Galaxies and Their Evolution into Nucleated Dwarfs

    NASA Astrophysics Data System (ADS)

    Bekki, Kenji

    2015-10-01

    We propose that there is an evolutionary link between ultra-compact blue dwarf galaxies (UCBDs) with active star formation and nucleated dwarfs based on the results of numerical simulations of dwarf-dwarf merging. We consider the observational fact that low-mass dwarfs can be very gas-rich, and thereby investigate the dynamical and chemical evolution of very gas-rich, dissipative dwarf-dwarf mergers. We find that the remnants of dwarf-dwarf mergers can be dominated by new stellar populations formed from the triggered starbursts and consequently can have blue colors and higher metallicities (Z [0.2-1]Z?). We also find that the remnants of these mergers can have rather high mass densities (104 M? pc-3) within the central 10 pc and small half-light radii (40-100 pc). The radial stellar structures of some merger remnants are similar to those of nucleated dwarfs. Star formation can continue in nuclear gas disks (R < 100 pc) surrounding stellar galactic nuclei (SGNs) so that the SGNs can finally have multiple stellar populations with different ages and metallicities. These very compact blue remnants can be identified as UCBDs soon after merging and as nucleated dwarfs after the young stars fade. We discuss these results in the context of the origins of metal-rich ultra-compact dwarfs and SGNs.

  19. Characterizing Accreting White Dwarf Pulsators

    NASA Astrophysics Data System (ADS)

    Szkody, Paula; Mukadam, Anjum

    2014-02-01

    Understanding the population, mass distribution, and evolution of accreting white dwarfs impacts the entire realm of binary interaction, including the creation of Type Ia supernovae. We are concentrating on accreting white dwarf pulsators, as the pulsation properties allow us a view of how the accretion affects the interior of the star. Our ground- based photometry on 11 accreting pulsators with corresponding temperatures from HST UV spectra suggest a broad instability strip in the range of 10500 to 16000K. Additionally, tracking a post-outburst heated white dwarf as it cools and crosses the blue edge and resumes pulsation provides an independent method to locate the empirical instability strip. Determining a post-outburst cooling curve yields an estimate of the amount of heating and the accreted mass during the outburst. We request additional photometry of 2 objects that present unique properties: GW Lib which has not yet returned to its pre-outburst pulsation spectrum after 6 yrs, and EQ Lyn which returned to its pre- outburst pulsation after 3 yrs but is now turning on and off without ongoing outbursts. Following the pulsation spectrum changes over stretches of several nights in a row will provide specific knowledge of the stability of the observed modes.

  20. Uncovering Blue Diffuse Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    James, Bethan; Koposov, Sergey; Stark, Daniel; Belokurov, Vasily; Pettini, Max; Olszewski, Edward W.

    2015-01-01

    Extremely metal-poor galaxies (XMPs) and the star-formation within their chemically pristine environments are fundamental to our understanding of the galaxy formation process at early times. However, traditional emission-line surveys detect only the brightest metal-poor galaxies where star-formation occurs in compact, starbursting environments, and thereby give us only a partial view of the dwarf galaxy population. To avoid such biases, we have developed a new search algorithm based on the morphological, rather then spectral, properties of XMPs and have applied to the Sloan Digital Sky Survey database of images. Using this novel approach, we have discovered ~100 previously undetected, faint blue galaxies, each with isolated HII regions embedded in a diffuse continuum. In this talk I will present the first results from follow-up optical spectroscopy of this sample, which reveals these blue diffuse dwarfs (BDDs) to be young, very metal-poor and actively forming stars despite their intrinsically low luminosities. I will present evidence showing that BDDs appear to bridge the gap between quiescent dwarf irregular (dIrr) galaxies and blue compact galaxies (BCDs) and as such offer an ideal opportunity to assess how star-formation occurs in more `normal' metal-poor systems.

  1. Frequency, Magnitude, and Possible Causes of Stranding and Mass-Mortality Events of the Beach Clam Tivela mactroides (Bivalvia: Veneridae)

    PubMed Central

    Turra, Alexander; Pombo, Maíra; Petracco, Marcelo; Siegle, Eduardo; Fonseca, Mariana; Denadai, Márcia R.

    2016-01-01

    Stranding combined with mass-mortality events of sandy-beach organisms is a frequent but little-understood phenomenon, which is generally studied based on discrete episodes. The frequency, magnitude, and possible causes of stranding and mass-mortality events of the trigonal clam Tivela mactroides were assessed based on censuses of stranded individuals, every four days from September 2007 through December 2008, in Caraguatatuba Bay, southeastern Brazil. Stranded clams were classified as dying (closed valves did not open when forced) or dead (closed valves were easily opened). Information on wave parameters and the living intertidal clam population was used to assess possible causes of stranding. This fine-scale monitoring showed that stranding occurred widely along the shore and year-round, with peaks interspersed with periods of low or no mortality. Dead clams showed higher mean density than dying individuals, but a lower mean shell length, attributed to a higher tolerance to desiccation of larger individuals. Wave height had a significant negative relationship to the density of dying individuals, presumed to be due to the accretive nature of low-energy waves: when digging out, clams would be more prone to be carried upward and unable to return; while larger waves, breaking farther from the beach and with a stronger backwash, would prevent stranding in the uppermost areas. This ecological finding highlights the need for refined temporal studies on mortality events, in order to understand them more clearly. Last, the similar size structure of stranded clams and the living population indicated that the stranded individuals are from the intertidal or shallow subtidal zone, and reinforces the ecological and behavioral components of this process, which have important ecological and socioeconomic implications for the management of this population. PMID:26745804

  2. The endocrine-disrupting effect and other physiological responses of municipal effluent on the clam Ruditapes decussatus.

    PubMed

    Mezghani-Chaari, Sawssan; Machreki-Ajmi, Monia; Tremolet, Gauthier; Kellner, Kristell; Geffard, Alain; Minier, Christophe; Hamza-Chaffai, Amel

    2015-12-01

    In order to document the potential endocrine disrupting and toxic effect of the municipal wastewater effluents discharged into the Sfax coastal area (South of Tunisia), specimens of clam R. decussatus were collected from a reference site and were in vivo exposed to treated sewage effluent for 30 days. To this end, estrogenic and androgenic activities were measured in the gills to assess potential accumulation and regulation of active compounds. After effluent exposure androgenic activity in organic extracts increased up to fivefold compared to controls and remained elevated, while estrogenic activity was not significantly affected by exposure. As a consequence, remarkable disruptions in the gametogenesis activity, glycogen content, and Vitellogenin-like protein levels in male clams were observed. A parallel analysis of heavy metals in clam tissues was determined. A significant uptake of Ni, Zn, and Pb in soft tissues of exposed clams was observed. The significant increase of malondialdehyde (MDA) concentrations as a function of exposure time implies that clams have been exposed to an oxidative stress probably due to the presence of high metal concentrations in sewage effluent. Correlation analysis has revealed a statistically significant and positive relationship between MDA levels and metal concentrations in clams' tissues. The acetylcholinesterase activity was not significantly affected by exposure. Altogether, these results showed that a short-term exposure to a mixture of chemical compounds released by the Sfax wastewater treatment plant induce adverse physiological and reproductive effects in R. decussatus. Further studies are underway in order to evaluate its long-term impacts on aquatic wildlife in the gulf of Gabes area. PMID:26278908

  3. Isolation of Vibrio alginolyticus and Vibrio splendidus from Aquacultured Carpet Shell Clam (Ruditapes decussatus) Larvae Associated with Mass Mortalities

    PubMed Central

    Gmez-Len, J.; Villamil, L.; Lemos, M. L.; Novoa, B.; Figueras, A.

    2005-01-01

    Two episodes of mortality of cultured carpet shell clams (Ruditapes decussatus) associated with bacterial infections were recorded during 2001 and 2002 in a commercial hatchery located in Spain. Vibrio alginolyticus was isolated as the primary organism from moribund clam larvae that were obtained during the two separate events. Vibrio splendidus biovar II, in addition to V. alginolyticus, was isolated as a result of a mixed Vibrio infection from moribund clam larvae obtained from the second mortality event. The larval mortality rates for these events were 62 and 73%, respectively. Mortality was also detected in spat. To our knowledge, this is the fist time that these bacterial species have been associated with larval and juvenile carpet shell clam mortality. The bacterial strains were identified by morphological and biochemical techniques and also by PCR and sequencing of a conserved region of the 16S rRNA gene. In both cases bacteria isolated in pure culture were inoculated into spat of carpet shell clams by intravalvar injection and by immersion. The mortality was attributed to the inoculated strains, since the bacteria were obtained in pure culture from the soft tissues of experimentally infected clams. V. alginolyticus TA15 and V. splendidus biovar II strain TA2 caused similar histological lesions that affected mainly the mantle, the velum, and the connective tissue of infected organisms. The general enzymatic activity of both live cells and extracellular products (ECPs), as evaluated by the API ZYM system, revealed that whole bacterial cells showed greater enzymatic activity than ECPs and that the activity of most enzymes ceased after heat treatment (100C for 10 min). Both strain TA15 and strain TA2 produced hydroxamate siderophores, although the activity was greater in strain TA15. ECPs from both bacterial species at high concentrations, as well as viable bacteria, caused significant reductions in hemocyte survival after 4 h of incubation, whereas no significant differences in viability were observed during incubation with heat-killed bacteria. PMID:15640176

  4. Frequency, Magnitude, and Possible Causes of Stranding and Mass-Mortality Events of the Beach Clam Tivela mactroides (Bivalvia: Veneridae).

    PubMed

    Turra, Alexander; Pombo, Maíra; Petracco, Marcelo; Siegle, Eduardo; Fonseca, Mariana; Denadai, Márcia R

    2016-01-01

    Stranding combined with mass-mortality events of sandy-beach organisms is a frequent but little-understood phenomenon, which is generally studied based on discrete episodes. The frequency, magnitude, and possible causes of stranding and mass-mortality events of the trigonal clam Tivela mactroides were assessed based on censuses of stranded individuals, every four days from September 2007 through December 2008, in Caraguatatuba Bay, southeastern Brazil. Stranded clams were classified as dying (closed valves did not open when forced) or dead (closed valves were easily opened). Information on wave parameters and the living intertidal clam population was used to assess possible causes of stranding. This fine-scale monitoring showed that stranding occurred widely along the shore and year-round, with peaks interspersed with periods of low or no mortality. Dead clams showed higher mean density than dying individuals, but a lower mean shell length, attributed to a higher tolerance to desiccation of larger individuals. Wave height had a significant negative relationship to the density of dying individuals, presumed to be due to the accretive nature of low-energy waves: when digging out, clams would be more prone to be carried upward and unable to return; while larger waves, breaking farther from the beach and with a stronger backwash, would prevent stranding in the uppermost areas. This ecological finding highlights the need for refined temporal studies on mortality events, in order to understand them more clearly. Last, the similar size structure of stranded clams and the living population indicated that the stranded individuals are from the intertidal or shallow subtidal zone, and reinforces the ecological and behavioral components of this process, which have important ecological and socioeconomic implications for the management of this population. PMID:26745804

  5. The galactic population of white dwarfs

    NASA Astrophysics Data System (ADS)

    Napiwotzki, Ralf

    2009-06-01

    The contribution of white dwarfs of the different Galactic populations to the stellar content of our Galaxy is only poorly known. Some authors claim a vast population of halo white dwarfs, which would be in accordance with some investigations of the early phases of Galaxy formation claiming a top-heavy initial- mass- function. Here, I present a model of the population of white dwarfs in the Milky Way based on observations of the local white dwarf sample and a standard model of Galactic structure. This model will be used to estimate the space densities of thin disc, thick disc and halo white dwarfs and their contribution to the baryonic mass budget of the Milky Way. One result of this investigation is that white dwarfs of the halo population contribute a large fraction of the Galactic white dwarf number count, but they are not responsible for the lion's share of stellar mass in the Milky Way. Another important result is the substantial contribution of the - often neglected - population of thick disc white dwarfs. Misclassification of thick disc white dwarfs is responsible for overestimates of the halo population in previous investigations.

  6. Auroral Phenomena in Brown Dwarf Atmospheres

    NASA Astrophysics Data System (ADS)

    Pineda, J. Sebastian; Hallinan, Gregg

    2016-01-01

    Since the unexpected discovery of radio emission from brown dwarfs some 15 years ago, investigations into the nature of this emission have revealed that, despite their cool and neutral atmospheres, brown dwarfs harbor strong kG magnetic fields, but unlike the warmer stellar objects, they generate highly circularly polarized auroral radio emission, like the giant planets of the Solar System. Our recent results from Keck LRIS monitoring of the brown dwarf LSR1835+32 definitively confirm this picture by connecting the auroral radio emission to spectroscopic variability at optical wavelengths as coherent manifestations of strong large-scale magnetospheric auroral current systems. I present some of the results of my dissertation work to understand the nature brown dwarf auroral phenomena. My efforts include a survey of Late L dwarfs and T dwarfs, looking for auroral Hα emission and a concurrent survey looking for the auroral emission of H3+ from brown dwarfs with radio pulse detections. I discuss the potential connection of this auroral activity to brown dwarf weather phenomena and how brown dwarf aurorae may differ from the analogous emission of the magnetized giant planets in the Solar System.

  7. Brown dwarfs in young stellar clusters

    NASA Technical Reports Server (NTRS)

    Stringfellow, Guy S.

    1991-01-01

    The present calculations of the early evolution of brown dwarfs and very low mass stars (LMSs) yield isochrones spanning 0.01-0.2 solar masses for ages in the 1 to 300 million year range. Since the brown dwarfs remain sharply segregated in T(eff) from LMSs for ages of less than 100 million years, it follows that for coeval populations of known age, a domain exists in the H-R diagram in which only brown dwarfs exist. These theoretical results are compared with recent observations of the Pleiades brown dwarf candidates, using two new sets of color-T(eff) transformations. Both sets yield consistent interpretations.

  8. Gaia and brown dwarfs from Spain

    NASA Astrophysics Data System (ADS)

    Caballero, J. A.

    Gaia will not observe 50 000 brown dwarfs, but about 100 times less. However, these ? 500 brown dwarfs will be benchmarks for many substellar topics. It is possible to identify them in advance and make the list public to all astronomers worldwide through a virtual observatory-compliant ``Gaia brown dwarf'' catalogue. This M-, L- and T-dwarf Archive of Interest for Astrophysics would tabulate precise Gaia astrometry, multiband photometry, high- and low-resolution spectroscopy and homogeneously derived astrophysical parameters. Spanish observatories may play a key role in the catalogue preparation.

  9. White Dwarfs in the ALHAMBRA Survey

    NASA Astrophysics Data System (ADS)

    Catalán, S.; Isern, J.; García-Berro, E.; Torres, S.; Alhambra Team

    2005-07-01

    A new high visual depth survey is presented. New cool white dwarfs will eventually be discovered, which will undoubtely increase the statistical significance of the white dwarf luminosity function. Moreover, by increasing the sample of known white dwarfs, we will be able to determine which ones are members of a binary system and which of those binary systems are detached and composed by a main sequence star and a white dwarf. Hence, comparison of their corresponding ages will provide tight constraints on the evolutionary models.

  10. Cross-shore and Vertical Distribution of Turbulence Kinetic Energy in the Surf Zone Generated by Plunging Breakers

    NASA Astrophysics Data System (ADS)

    Cheng, J.; Wang, P.

    2012-12-01

    Breaking waves, especially plunging breakers, generate intense turbulence and is crucial in dissipating incident wave energy, and suspending and transporting sediment in the surf zone. Therefore quantifying breaking-induced turbulence kinetic energy (TKE) is essential in understanding surf zone processes. Surf zone experiment data collected at the Large-scale Sediment Transport Facility (LSTF) at the U.S. Army Engineer Research and Development Center were used here. Two LSTF cases, one regular (3 s period) and one irregular (3 s peak period) waves over a movable bed, are examined here. Both cases resulted in dominantly plunging type of breakers. Waves and 3-D currents were measured simultaneously at 10 cross-shore locations and throughout the water column, with a sampling rate of 20 Hz. In order to separate orbital wave motion from turbulent motion, ensemble averaging and moving averaging were conducted for regular and irregular wave cases, respectively. A 5-point moving average, with 3-point averaging at the crest and trough, provided an optimal method to resolve turbulence, while approximately 95% of the incident wave energy being accounted for. The TKE was calculated after removing the averaged motion from the raw data. Large TKE was generated at the surface associated with wave breaking and dissipated rapidly downward. The TKE decreased nearly 2 orders of magnitude downward within 15 cm. The TKE researched a minimum value at approximately 50%-80% of the water depth, and increased thereafter toward the bottom due to the generation of bed-induced turbulence.

  11. Seasonal and diel variation in the standing crop of fishes and macroinvertebrates from a Gulf of Mexico surf zone

    NASA Astrophysics Data System (ADS)

    Ross, Stephen T.; McMichael, Robert H.; Ruple, David L.

    1987-10-01

    To determine the relative importance of surf zones as habitats for fishes and macroinvertebrates, compared to other inshore marine environments, seasonal and diel abundance patterns were studied for one year. Both study sites were located on the south shore of Horn Island, a barrier in the northern Gulf of Mexico. At each site a 300 m 2 area was sampled, using a 50-m seine set around steel poles. Capture efficiency of the seine, determined from escapement tests, averaged 82%. While 59 species were captured during the study, only six species, Harengula jaguana, Anchoa hepsetus, A. mitchilli, Callinectes sapidus, A. lyolepis and Menticirrhus littoralis, comprised 90% of the total catch by number. Summer macrofaunal standing crop (mean = 98 gm -2, wet weight) was significantly greater than other seasons. The lowest values for both density and standing crop were those obtained in the winter. Both standing crop and average weight of the fishes increased significantly in night samples; a similar pattern did not occur for blue carbs. This primarily reflects the movement of larger, but generally rarer, fish species into the shallow surf zone after dark. Principal components analysis indicated that the standing crop of fishes was lowest during periods of reduced water volume and wave activity. However, seasonal factors appear, overall, to be more important in influencing fish abundance. Compared to a wide range of inshore marine habitats, surf zones appear intermediate in standing crop. Thus, at least during the summer, such habitats are important contributors to inshore standing crops of fishes.

  12. Sequencing and Characterization of Striped Venus Transcriptome Expand Resources for Clam Fishery Genetics

    PubMed Central

    Coppe, Alessandro; Bortoluzzi, Stefania; Murari, Giulia; Marino, Ilaria Anna Maria; Zane, Lorenzo; Papetti, Chiara

    2012-01-01

    Background The striped venus Chamelea gallina clam fishery is among the oldest and the largest in the Mediterranean Sea, particularly in the inshore waters of northern Adriatic Sea. The high fishing pressure has lead to a strong stock abundance decline, enhanced by several irregular mortality events. The nearly complete lack of molecular characterization limits the available genetic resources for C. gallina. We achieved the first transcriptome of this species with the aim of identifying an informative set of expressed genes, potential markers to assess genetic structure of natural populations and molecular resources for pathogenic contamination detection. Methodology/Principal Findings The 454-pyrosequencing of a normalized cDNA library of a pool C. gallina adult individuals yielded 298,494 raw reads. Different steps of reads assembly and filtering produced 36,422 contigs of high quality, one half of which (18,196) were annotated by similarity. A total of 111 microsatellites and 20,377 putative SNPs were identified. A panel of 13 polymorphic transcript-linked microsatellites was developed and their variability assessed in 12 individuals. Remarkably, a scan to search for contamination sequences of infectious origin indicated the presence of several Vibrionales species reported to be among the most frequent clam pathogen's species. Results reported in this study were included in a dedicated database available at http://compgen.bio.unipd.it/chameleabase. Conclusions/Significance This study represents the first attempt to sequence and de novo annotate the transcriptome of the clam C. gallina. The availability of this transcriptome opens new perspectives in the study of biochemical and physiological role of gene products and their responses to large and small-scale environmental stress in C. gallina, with high throughput experiments such as custom microarray or targeted re-sequencing. Molecular markers, such as the already optimized EST-linked microsatellites and the discovered SNPs will be useful to estimate effects of demographic processes and to detect minute levels of population structuring. PMID:23028497

  13. Prevalence of Vibrio parahaemolyticus in oyster and clam culturing environments in Taiwan.

    PubMed

    Yu, Wei-Ting; Jong, Koa-Jen; Lin, Yu-Ren; Tsai, Shing-en; Tey, Yao Hsien; Wong, Hin-chung

    2013-01-01

    Vibrio parahaemolyticus is the most prevalent gastroenteritis pathogen in Taiwan and some other Asian countries, and it frequently occurs in oysters and other seafood. This study monitors changes in the density of V. parahaemolyticus and environmental parameters in oyster and hard clam aquacultural environments in Taiwan. Water, sediment and shellfish samples were collected from five sampling sites in 2008-2010, and analyzed for environmental physiochemical parameters, numbers of indicator bacteria (total aerobic counts, total coliforms and fecal coliforms), Vibrio and V. parahaemolyticus present. The results for open oyster farms and hard clam ponds did not differ significantly. V. parahaemolyticus was detected in 77.5, 77.5, 70.8 and 68.8% of the water, sediment, oyster and clam samples, respectively. The densities of V. parahaemolyticus were significantly higher in shellfish than in sediment or water samples, with mean values of 1.33, 1.04 and -0.02 Log CFU/g, respectively. Among these five sampling sites, Shengang and Fangyuan yielded significantly different data from those obtained at the other three sites. As determined by linear multiple regression, V. parahaemolyticus density in water samples depended significantly on the precipitation and Vibrio count, while the V. parahaemolyticus density in the sediment or shellfish samples depended significantly on the salinity of the seawater. Among 1076 isolates examined, a total of three putative pathogenic isolates were identified from 2.5% of the examined samples, and these isolates exhibited hemolytic or urease activities and the presence of gene markers for tdh, trh, type III secretion system (T3SS) 1 (vcrD1) or T3SS2? (vcrD2). The results herein may facilitate the assessment of risk associated with this pathogen in Taiwan and other geographically similar regions. PMID:23290223

  14. Chronic toxicity of the antiepileptic carbamazepine on the clam Ruditapes philippinarum.

    PubMed

    Almeida, ngela; Freitas, Rosa; Calisto, Vnia; Esteves, Valdemar I; Schneider, Rudolf J; Soares, Amadeu M V M; Figueira, Etelvina

    2015-01-01

    The impacts of carbamazepine (CBZ) on aquatic organisms are yet not well investigated. The present study aimed to better understand the chronic effects of environmentally relevant concentrations of CBZ. The experiment was performed by exposing the filter feeding clam Ruditapes philippinarum to 0.00, 0.03, 0.30, 3.00 and 9.00?g/L, during 28days. To assess the chronic toxicity of the drug a battery of biomarkers related with health status and oxidative stress was applied. In order to quantify CBZ in the clam's tissues and in water samples ELISA was used. The present study showed three types of responses on the clams after a chronic exposure to CBZ. For control condition and the lower concentrations (0.03 and 0.30?g/L) a "similar" metabolic state was observed and the most efficient antioxidant status leading to the elimination of reactive oxygen species formed during the metabolism of CBZ. The concentration of 3.00?g/L seemed to be a "threshold" concentration, beyond which the concentration levels of CBZ began to exert a toxic effect, compromising the activity of biotransformation and antioxidant enzymes, with notorious effects at the highest CBZ concentration (9.00?g/L). CBZ also seemed to alter the energy-related responses, especially the glycogen and electron system responses, revealing a slowdown in metabolism at the higher exposure concentrations (3.00 and 9.00?g/L). Overall, the present study demonstrated that the higher CBZ concentrations can lead to the impairment of antioxidant enzymes compromising the neutralization of reactive oxygen species, and thus the ability to cope with oxidative stress. PMID:25943297

  15. Comparison of selenium bioaccumulation in the clams Corbicula fluminea and Potamocorbula amurensis: A bioenergetic modeling approach

    USGS Publications Warehouse

    Lee, B.-G.; Lee, J.-S.; Luoma, S.N.

    2006-01-01

    Selenium uptake from food (assimilation efficiency) and dissolved phase (influx rate) as well as loss kinetics (efflux rate) were compared between two bivalves, Corbicula fluminea and Potamocorbula amurensis. The effects of salinity and temperature on these kinetic parameters for both clam species also were evaluated. The Asiatic clam, C. fluminea, more efficiently assimilated Se associated with algae (66-87%) than Se associated with oxic sediments (20-37%). However, no consistent difference was found between Se assimilation efficiencies from both food types (19-60%) for P. amurensis. The temperature and salinity had a minor influence on the Se assimilation from ingested food. However, the effects of temperature and salinity were more evident in the uptake from dissolved sources. The influx rate of Se(IV) increased by threefold with the increase of temperature from 5 to 21??C for C. fluminea. The increase of salinity from 4 to 20 psu decreased the uptake rate constant (ku) of Se in P. amurensis from 0.011 to 0.005 L/g/h, whereas salinity change (0-8 psu) had a negligible effect on the Se influx rate of C. fluminea. The Se influx rate of P. amurensis decreased by half with the 3.5-fold increase in tissue dry weight. The rate constant of loss was greater for P. amurensis (0.029/d at 8 psu) than for C. fluminea (0.014/d at 0 psu and 0.01/d at 8 psu). A bioenergetic model suggests that dietary uptake is the dominant pathway for Se bioaccumulation in the two clams in San Francisco Bay and that interspecies differences in Se bioaccumulation can be explained by differences in food ingestion rates. ?? 2006 SETAC.

  16. Larval and juvenile growth performance of Manila clam hybrids of two full-sib families

    NASA Astrophysics Data System (ADS)

    Huo, Zhongming; Yan, Xiwu; Zhao, Liqiang; Liang, Jian; Yang, Feng; Zhang, Guofan

    2015-06-01

    In order to determine whether growth performance could be improved by hybridizing full-sib families of Manila clam ( Ruditapes philippinarum), crosses between two full-sib families including self and reciprocal crosses were carried out. The effects of heterosis, combining ability and interaction on the growth of shell length were estimated. The results showed that the growth of hybrid larvae was intermediate between parents on days 6 and 9. Heterosis on shell length was observed, which varied at juvenile stage. The cross of ♂A × ♀B ( Hp varied between 10.41% and 68.27%) displayed larger heterosis than ♂B × ♀A ( Hp varied between 1.89% and 32.33%) did, suggesting that ♂A × ♀B was an ideal hatchery method of improving the growth performance of Manila clam. The variances of general combining ability (GCA), special combining ability (SCA) and interaction (I) were significant in shell length (P < 0.05), indicating that both additive and non-additive genetic factors were important contributors to the growth of larvae and juveniles. The GCA for shell length of ♂A × ♀B was higher than that of ♂B × ♀A at both larval and juvenile stages. This confirmed that the cross between ♂A and ♀B showed great growth in shell length. In summary, the growth of Manila clam seeds could be improved by hybridizing selected parents from large numbers of full-sib families.

  17. Environmental salinity modulates the effects of elevated CO2 levels on juvenile hard-shell clams, Mercenaria mercenaria.

    PubMed

    Dickinson, Gary H; Matoo, Omera B; Tourek, Robert T; Sokolova, Inna M; Beniash, Elia

    2013-07-15

    Ocean acidification due to increasing atmospheric CO2 concentrations results in a decrease in seawater pH and shifts in the carbonate chemistry that can negatively affect marine organisms. Marine bivalves such as the hard-shell clam, Mercenaria mercenaria, serve as ecosystem engineers in estuaries and coastal zones of the western Atlantic and, as for many marine calcifiers, are sensitive to the impacts of ocean acidification. In estuaries, the effects of ocean acidification can be exacerbated by low buffering capacity of brackish waters, acidic inputs from freshwaters and land, and/or the negative effects of salinity on the physiology of organisms. We determined the interactive effects of 21 weeks of exposure to different levels of CO2 (~395, 800 and 1500 ?atm corresponding to pH of 8.2, 8.1 and 7.7, respectively) and salinity (32 versus 16) on biomineralization, shell properties and energy metabolism of juvenile hard-shell clams. Low salinity had profound effects on survival, energy metabolism and biomineralization of hard-shell clams and modulated their responses to elevated PCO2. Negative effects of low salinity in juvenile clams were mostly due to the strongly elevated basal energy demand, indicating energy deficiency, that led to reduced growth, elevated mortality and impaired shell maintenance (evidenced by the extensive damage to the periostracum). The effects of elevated PCO2 on physiology and biomineralization of hard-shell clams were more complex. Elevated PCO2 (~800-1500 ?atm) had no significant effects on standard metabolic rates (indicative of the basal energy demand), but affected growth and shell mechanical properties in juvenile clams. Moderate hypercapnia (~800 ?atm PCO2) increased shell and tissue growth and reduced mortality of juvenile clams in high salinity exposures; however, these effects were abolished under the low salinity conditions or at high PCO2 (~1500 ?atm). Mechanical properties of the shell (measured as microhardness and fracture toughness of the shells) were negatively affected by elevated CO2 alone or in combination with low salinity, which may have important implications for protection against predators or environmental stressors. Our data indicate that environmental salinity can strongly modulate responses to ocean acidification in hard-shell clams and thus should be taken into account when predicting the effects of ocean acidification on estuarine bivalves. PMID:23531824

  18. Manila clams from Hg polluted sediments of Marano and Grado lagoons (Italy) harbor detoxifying Hg resistant bacteria in soft tissues

    SciTech Connect

    Baldi, Franco; Gallo, Michele; Marchetto, Davide; Faleri, Claudia; Maida, Isabel; Fani, Renato

    2013-08-15

    A mechanism of mercury detoxification has been suggested by a previous study on Hg bioaccumulation in Manila clams (Ruditapes philippinarum) in the polluted Marano and Grado lagoons and in this study we demonstrate that this event could be partly related to the detoxifying activities of Hg-resistant bacteria (MRB) harbored in clam soft tissues. Therefore, natural clams were collected in six stations during two different periods (winter and spring) from Marano and Grado Lagoons. Siphons, gills and hepatopancreas from acclimatized clams were sterile dissected to isolate MRB. These anatomical parts were glass homogenized or used for whole, and they were lying on a solid medium containing 5 mg l{sup −1} HgCl{sub 2} and incubated at 30 °C. A total of fourteen bacterial strains were isolated and were identified by 16S rDNA sequencing and analysis, revealing that strains were representative of eight bacterial genera, four of which were Gram-positive (Enterococcus, Bacillus, Jeotgalicoccus and Staphylococcus) and other four were Gram-negative (Stenotrophomonas, Vibrio, Raoultella and Enterobacter). Plasmids and merA genes were found and their sequences determined. Fluorescence in situ hybridization (FISH) technique shows the presence of Firmicutes, Actinobacteria and Gammaproteobacteria by using different molecular probes in siphon and gills. Bacterial clumps inside clam flesh were observed and even a Gram-negative endosymbiont was disclosed by transmission electronic microscope inside clam cells. Bacteria harbored in cavities of soft tissue have mercury detoxifying activity. This feature was confirmed by the determination of mercuric reductase in glass-homogenized siphons and gills. -- Highlights: ► We isolated Gram-positive and Gram-negative Hg resistant strains from soft tissues of Ruditapes philippinarum. ► We identify 14 mercury resistant strains by 16S rRNA gene sequences. ► Bacteria in siphon and gill tissues of clams were observed by TEM and identified with different FISH probes. ► Hg-reductase (MerA) activity in glass homogenized clam tissues was also determined.

  19. Effects of burial by the disposal of dredged materials from the Columbia River on Pacific razor clams (Siliqua patula)

    SciTech Connect

    Vavrinec, John; Kohn, Nancy P.; Hall, Kathleen D.; Romano, Brett A.

    2007-05-07

    Annual maintenance of the Columbia River navigation channel requires the U.S. Army Corps of Engineers (Corps) to dredge sediment from the river and dispose of the sediment in coastal areas at the mouth of the Columbia River. Some of these disposal areas can be as shallow as 12 m deep in waters off the coastal beaches, and dredged material disposal activities have therefore raised concerns of impacts to local razor clam (Siliqua patula) populations that are prevalent in the area. The Corps’ Portland District requested that the Marine Sciences Laboratory of the U.S. Department of Energy’s Pacific Northwest National Laboratory conduct laboratory experiments to evaluate the potential impacts of burial by dredged material to razor clams during disposal. Prior modeling of disposal events indicates three stresses that could have an impact on benthic invertebrates: convective descent and bottom encounter (compression forces due to bottom impact), dynamic collapse and spreading (surge as material washes over the bottom), and mounding (burial by material). Because the razor clam is infaunal, the effects of the first two components should be minimal, because the clams should be protected by substrate that is not eroded in the event and by the clams’ rapid digging capabilities. The mound resulting from the disposal, however, would bury any clams remaining in the footprint under as much as 12 cm of new sediment according to modeling, and the clams’ reaction to such an event and to burial is not known. Although the literature suggests that razor clams may be negatively affected by siltation and therefore perhaps by dredging and disposal activity, as well, impacts of this type have not been demonstrated. The primary purpose of this study was to evaluate the potential impacts of dredge material disposal on adult subtidal razor clam populations at the mouth of the Columbia River. Using the parameters defined in a previous model, a laboratory study was created in which a slurry was added to experimental chambers seeded with adult razor clams to produce burial mounds of various thicknesses. The laboratory results presented here have two implications for disposal operations.

  20. Paralytic shellfish poisoning toxins accumulation in purple clam Hiatula rostrata and toxic effect on milkfish Chanos chanos larval fish.

    PubMed

    Chen, C Y

    2001-11-01

    In an attempt to feed purple clams (Hiatula rostrata) with dinoglagellate Alexandrium minutum, the maximal accumulation toxicity of paralytic shellfish poisoning (PSP) toxins reached 40.6 MU/g on day 5 of feeding. Subsequently, the toxicity increased no further, although purple clams ingested more toxic algae. Furthermore, when milkfish (Chanos chanos) larvae were treated with toxic, nontoxic A. minutum or PSP toxin-containing extract in the water medium, it was found that the mortality of fish increased with the increasing concentrations of toxic algae. PSP toxin-containing extract did not show any toxic effect on milkfish larvae. PMID:11695819