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Sample records for lithic assemblage excavated

  1. The Lithic Assemblages of Xiaochangliang, Nihewan Basin: Implications for Early Pleistocene Hominin Behaviour in North China.

    PubMed

    Yang, Shi-Xia; Hou, Ya-Mei; Yue, Jian-Ping; Petraglia, Michael D; Deng, Cheng-Long; Zhu, Ri-Xiang

    2016-01-01

    Xiaochangliang (XCL), located in the Nihewan Basin of North China, is a key archaeological locality for understanding the behavioural evolution of early humans. XCL dates to ca. 1.36 Ma, making it one of the earliest sites in Northeast Asia. Although XCL represents the first excavation of an Early Pleistocene site in the Nihewan Basin, identified and excavated in the 1970's, the lithic assemblages have never been published in full detail. Here we describe the lithic assemblages from XCL, providing information on stone tool reduction techniques and the influence of raw materials on artefact manufacture. The XCL hominins used both bipolar and freehand reduction techniques to manufacture small flakes, some of which show retouch. Bipolar reduction methods at XCL were used more frequently than previously recognized. Comparison of XCL with other Early Pleistocene sites in the Nihewan Basin indicates the variable use of bipolar and freehand reduction methods, thereby indicating a flexible approach in the utilization of raw materials. The stone tools from XCL and the Nihewan sites are classifiable as Mode I lithic assemblages, readily distinguished from bifacial industries manufactured by hominins in Eastern Asia by ca. 800 ka. PMID:27205881

  2. The Lithic Assemblages of Xiaochangliang, Nihewan Basin: Implications for Early Pleistocene Hominin Behaviour in North China

    PubMed Central

    Yang, Shi-Xia; Hou, Ya-Mei; Yue, Jian-Ping; Petraglia, Michael D.; Deng, Cheng-Long; Zhu, Ri-Xiang

    2016-01-01

    Xiaochangliang (XCL), located in the Nihewan Basin of North China, is a key archaeological locality for understanding the behavioural evolution of early humans. XCL dates to ca. 1.36 Ma, making it one of the earliest sites in Northeast Asia. Although XCL represents the first excavation of an Early Pleistocene site in the Nihewan Basin, identified and excavated in the 1970’s, the lithic assemblages have never been published in full detail. Here we describe the lithic assemblages from XCL, providing information on stone tool reduction techniques and the influence of raw materials on artefact manufacture. The XCL hominins used both bipolar and freehand reduction techniques to manufacture small flakes, some of which show retouch. Bipolar reduction methods at XCL were used more frequently than previously recognized. Comparison of XCL with other Early Pleistocene sites in the Nihewan Basin indicates the variable use of bipolar and freehand reduction methods, thereby indicating a flexible approach in the utilization of raw materials. The stone tools from XCL and the Nihewan sites are classifiable as Mode I lithic assemblages, readily distinguished from bifacial industries manufactured by hominins in Eastern Asia by ca. 800 ka. PMID:27205881

  3. The behavioral and cultural stratigraphic contexts of the lithic assemblages from Schöningen.

    PubMed

    Serangeli, Jordi; Conard, Nicholas J

    2015-12-01

    Within the various archaeological horizons in Schöningen, the presence of hominins is repeatedly demonstrated by the recovery of stone artifacts, broken bones, and bones with cut marks. The Spear Horizon, 13 II-4, with its ca. 1500 stone artifacts and ca. 12,000 faunal remains, represents by far the richest archaeological layers in Schöningen. Systematic waterscreening over a period of 15 years has fostered the recovery of numerous small flakes that otherwise would have remained undetected. Based on the stone artifacts published by H. Thieme and the lithic artifacts recovered from the ongoing excavations of the University of Tübingen and the Archaeological Heritage Office of Lower Saxony since 2008, we present here the main aspects of these lithic assemblages. The main features of the lithic assemblages recovered from the different find horizons and concentrations provide a consistent signature, suggesting a robust and repetitive technological strategy. The assemblages, which are made of local, high quality flint, lack handaxes and are clearly not related to the Acheulean. Intensely retouched scrapers, as well as denticulates, notched pieces, and points on thick flakes, angular debris, and non-anthropogenic thermal spalls are the most numerous retouched forms. The assemblages also contain a smaller number of thinner forms. Reduction sequences are short and Levallois technology is absent. Although some of the retouched forms are reminiscent of the Middle Paleolithic, the relatively non-standardized short reduction sequences technically oriented toward the production of thick and broad flakes are consistent with a classification in the late Lower Paleolithic. PMID:26311252

  4. Subsurface geology, ancient hydrothermal systems and crater excavation processes beneath Lake Rotomahana: Evidence from lithic clasts of the 1886 AD Rotomahana Pyroclastics

    NASA Astrophysics Data System (ADS)

    Pittari, A.; Briggs, R. M.; Bowyer, D. A.

    2016-03-01

    The craters associated with the 1886 AD phreatomagmatic Rotomahana eruption, Okataina Volcanic Centre, New Zealand, and the near-vent geology are now hidden beneath Lake Rotomahana and its post-eruptive sediment fill. Lithic clasts from the near-vent lithic lapilli ash deposits of the Rotomahana Pyroclastics are used in this study to trace geological and geothermal conditions before the eruption, as well as vent excavation dynamics. Near-vent deposit characteristics were described in the field, representative lithic clasts were documented petrographically, and unaltered clasts were analysed for major and trace element compositions. The majority of the lithic clasts were rhyolites with subordinate ignimbrites and hydrothermally altered clasts, and trace siltstone and silicified clasts. The rhyolites were classified into four petrographic groups according to phenocryst content and assemblage and were more diverse with respect to geochemical compositions. Most of the rhyolite lithics in the Rotomahana Pyroclastics did not match the rhyolite domes exposed subaerially around the lake, but did have affinities with the pre-Matahina caldera Wairua Rhyolite, and potentially other older non-exposed domes. Ignimbrites most likely correlated either to the Matahina ignimbrite or older non-exposed units. Hydrothermally altered rhyolite and ignimbrite lithic clasts are common and suggest that there has been a long-lived hydrothermal system in this sector, possibly dating back to early activity of the Okataina Volcanic Centre. The diversity in lithic types indicate a spatial variation in country rock lithology and strength, which probably contributed to the vent position and morphology along the Rotomahana fissure.

  5. Characterizing the Late Pleistocene MSA Lithic Technology of Sibudu, KwaZulu-Natal, South Africa

    PubMed Central

    Will, Manuel; Bader, Gregor D.; Conard, Nicholas J.

    2014-01-01

    Studies of the African Middle Stone Age (MSA) have become central for defining the cultural adaptations that accompanied the evolution of modern humans. While much of recent research in South Africa has focused on the Still Bay and Howiesons Poort (HP), periods following these technocomplexes were often neglected. Here we examine lithic assemblages from Sibudu that post-date the HP to further the understanding of MSA cultural variability during the Late Pleistocene. Sibudu preserves an exceptionally thick, rich, and high-resolution archaeological sequence that dates to ∼58 ka, which has recently been proposed as type assemblage for the “Sibudan”. This study presents a detailed analysis of the six uppermost lithic assemblages from these deposits (BM-BSP) that we excavated from 2011–2013. We define the key elements of the lithic technology and compare our findings to other assemblages post-dating the HP. The six lithic assemblages provide a distinct and robust cultural signal, closely resembling each other in various technological, techno-functional, techno-economic, and typological characteristics. These results refute assertions that modern humans living after the HP possessed an unstructured and unsophisticated MSA lithic technology. While we observed several parallels with other contemporaneous MSA sites, particularly in the eastern part of southern Africa, the lithic assemblages at Sibudu demonstrate a distinct and so far unique combination of techno-typological traits. Our findings support the use of the Sibudan to help structuring this part of the southern African MSA and emphasize the need for further research to identify the spatial and temporal extent of this proposed cultural unit. PMID:24878544

  6. Middle and late Pleistocene Middle Stone Age lithic technology from Pinnacle Point 13B (Mossel Bay, Western Cape Province, South Africa).

    PubMed

    Thompson, Erin; Williams, Hope M; Minichillo, Tom

    2010-01-01

    Excavations at a complex of caves and open air sites at Pinnacle Point, Mossel Bay, Southern Africa have uncovered rich stratified assemblages of Middle Stone Age materials, including those from Pinnacle Point Cave 13B (PP13B) that comprises the first modernly excavated assemblage in southern Africa to be securely dated to the Middle Pleistocene. We report here on the complete excavated lithic artifact assemblage from PP13B. Both technological and typological analyses of the complete assemblage were performed. The assemblage-scale analysis allows for intrasite comparison as well as comparison of the PP13B assemblage with other sites from the region. No size-related pattern of change over time was observed within the PP13B assemblage, although there is significant evidence for varying strategies of lithic reduction between excavation areas within the cave. Comparison with other material from the Southern African MSA suggests that there is significant inter- and intra-site variability in the Southern African Middle Stone Age, even between portions of assemblages that are roughly contemporaneous. PMID:20934091

  7. Insights into early lithic technologies from ethnography.

    PubMed

    Hayden, Brian

    2015-11-19

    Oldowan lithic assemblages are often portrayed as a product of the need to obtain sharp flakes for cutting into animal carcases. However, ethnographic and experimental research indicates that the optimal way to produce flakes for such butchering purposes is via bipolar reduction of small cryptocrystalline pebbles rather than from larger crystalline cores resembling choppers. Ethnographic observations of stone tool-using hunter-gatherers in environments comparable with early hominins indicate that most stone tools (particularly chopper forms and flake tools) were used for making simple shaft tools including spears, digging sticks and throwing sticks. These tools bear strong resemblances to Oldowan stone tools. Bipolar reduction for butchering probably preceded chopper-like core reduction and provides a key link between primate nut-cracking technologies and the emergence of more sophisticated lithic technologies leading to the Oldowan. PMID:26483534

  8. Variation in Lithic Technological Strategies among the Neanderthals of Gibraltar

    PubMed Central

    Shipton, Ceri; Clarkson, Christopher; Bernal, Marco Antonio; Boivin, Nicole; Finlayson, Clive; Finlayson, Geraldine; Fa, Darren; Pacheco, Francisco Giles; Petraglia, Michael

    2013-01-01

    The evidence for Neanderthal lithic technology is reviewed and summarized for four caves on The Rock of Gibraltar: Vanguard, Beefsteak, Ibex and Gorham’s. Some of the observed patterns in technology are statistically tested including raw material selection, platform preparation, and the use of formal and expedient technological schemas. The main parameters of technological variation are examined through detailed analysis of the Gibraltar cores and comparison with samples from the classic Mousterian sites of Le Moustier and Tabun C. The Gibraltar Mousterian, including the youngest assemblage from Layer IV of Gorham’s Cave, spans the typical Middle Palaeolithic range of variation from radial Levallois to unidirectional and multi-platform flaking schemas, with characteristic emphasis on the former. A diachronic pattern of change in the Gorham’s Cave sequence is documented, with the younger assemblages utilising more localized raw material and less formal flaking procedures. We attribute this change to a reduction in residential mobility as the climate deteriorated during Marine Isotope Stage 3 and the Neanderthal population contracted into a refugium. PMID:23762312

  9. Lithic raw material variability in the Central Duck River Basin: Reflections of Middle and Late Archaic organizational strategies: Report of Investigations No. 46

    SciTech Connect

    Amick, D.S.

    1987-01-01

    The purpose was to develop a model for understanding prehistoric chipped-stone distribution in the central Duck River Basin region located in Middle Tennessee. The model design consists of theoretical and empirical observation which are integrated to form an interpretive framework. Seven lithic assemblages ranging from middle to late Archaic periods (ca. 7000 to 3000 years B.P.) in age were analyzed to assess the model. The first stage of model-building was the development of a theoretical foundation for approaching the problem. A cultural adaptation paradigm is the foundation cornerstone. Lithic technology is viewed as an integral part of prehistoric cultural adaptation and lithic remains are regarded as critical indicators of behavioral variability. Environmental variables are stressed in interpreting lithic debris patterning across the landscape. The second stage of model-building involved the construction of a set of observations on lithic resource types and their distributions in the study area. A regional lithic resource survey was implemented. Application of the model to archaeological data was the last stage of model-building. Seven Middle-Late Archaic assemblages are compared. Results of the interassemblage analysis suggest that Late Archaic settlement systems were more logisically organized and technological systems were less expediently organized than those of Middle Archaic groups. Differences between Middle and Late Archaic adaptations are viewed as response to regional environmental and demographic trends. These trends are documented and their implications for subsistence, settlement, and social organization are considered.

  10. Analysis of orientation patterns in Olduvai Bed I assemblages using GIS techniques: implications for site formation processes.

    PubMed

    Benito-Calvo, Alfonso; de la Torre, Ignacio

    2011-07-01

    Mary Leakey's excavations at Olduvai Beds I and II provided an unparalleled wealth of data on the archaeology of the early Pleistocene. We have been able to obtain axial orientations of the Bed I bone and stone tools by applying GIS methods to the site plans contained in the Olduvai Volume 3 monograph (Leakey, 1971). Our analysis indicates that the Bed I assemblages show preferred orientations, probably caused by natural agents such as water disturbance. These results, based on new GIS techniques applied to paleoanthropological studies, have important implications for the understanding of the formative agents of Olduvai sites and the behavioral meaning of the bone and lithic accumulations in Bed I. PMID:21470661

  11. Matuyama-age lithic tools from the Sima del Elefante site, Atapuerca (northern Spain).

    PubMed

    Parés, Josep M; Pérez-González, Alfredo; Rosas, Antonio; Benito, A; Bermúdez de Castro, J M; Carbonell, E; Huguet, R

    2006-02-01

    Paleomagnetic results obtained from the sedimentary fill at the Sima del Elefante site in Atapuerca, Spain, reveal a geomagnetic reversal, interpreted as the Matuyama-Brunhes boundary (0.78 Ma). The uppermost lithostratigraphic units (E17 through E19), which contain Mode II and III archaeological assemblages, display normal polarity magnetization, whereas the six lowermost units (E9 through E16) yield negative latitudinal virtual geomagnetic pole positions. Units E9 through E13, all of which display reverse magnetic polarity, contain Mode I (Oldowan) lithic tools, testifying to the presence of humans in the early Pleistocene (0.78-1.77 Ma). PMID:16249015

  12. Refining Our Understanding of Howiesons Poort Lithic Technology: The Evidence from Grey Rocky Layer in Sibudu Cave (KwaZulu-Natal, South Africa)

    PubMed Central

    de la Peña, Paloma

    2015-01-01

    The detailed technological analysis of the youngest Howiesons Poort occupation in Sibudu Cave, layer Grey Rocky, has shown the importance of blade production (with different knapping methods involved), but also of flaking methods in coarse grained rock types. Moreover, new strategies of bifacial production and microlithism were important. Grey Rocky lithic technology shows a really versatile example of reduction strategies that were highly influenced by the characteristics of the rock types. This lithic assemblage is another example of the technological variability linked to the Howiesons Poort technocomplex. The reasons for this variability are still difficult to elucidate. Discrepancies between sites might be for different reasons: diachronic variations, functional variations, organizational variations or maybe different regional variations within what has been recognized traditionally and typologically as Howiesons Poort. The technological comparison of the Grey Rocky assemblage with assemblages from other Howiesons Poort sites demonstrates that there are common technological trends during the late Pleistocene, but they still need to be properly circumscribed chronologically. On the one hand, Howiesons Poort characteristics such as the bifacial production in quartz are reminiscent of production in some Still Bay or pre-Still Bay industries and the flake production or the prismatic blade production described here could be a point in common with pre-Still Bay and post-Howiesons Poort industries. On the other hand, the detailed analysis of the Grey Rocky lithics reinforces the particular character of this Howiesons Poort technocomplex, yet it also shows clear technological links with other Middle Stone Age assemblages. PMID:26633008

  13. Refining Our Understanding of Howiesons Poort Lithic Technology: The Evidence from Grey Rocky Layer in Sibudu Cave (KwaZulu-Natal, South Africa).

    PubMed

    de la Peña, Paloma

    2015-01-01

    The detailed technological analysis of the youngest Howiesons Poort occupation in Sibudu Cave, layer Grey Rocky, has shown the importance of blade production (with different knapping methods involved), but also of flaking methods in coarse grained rock types. Moreover, new strategies of bifacial production and microlithism were important. Grey Rocky lithic technology shows a really versatile example of reduction strategies that were highly influenced by the characteristics of the rock types. This lithic assemblage is another example of the technological variability linked to the Howiesons Poort technocomplex. The reasons for this variability are still difficult to elucidate. Discrepancies between sites might be for different reasons: diachronic variations, functional variations, organizational variations or maybe different regional variations within what has been recognized traditionally and typologically as Howiesons Poort. The technological comparison of the Grey Rocky assemblage with assemblages from other Howiesons Poort sites demonstrates that there are common technological trends during the late Pleistocene, but they still need to be properly circumscribed chronologically. On the one hand, Howiesons Poort characteristics such as the bifacial production in quartz are reminiscent of production in some Still Bay or pre-Still Bay industries and the flake production or the prismatic blade production described here could be a point in common with pre-Still Bay and post-Howiesons Poort industries. On the other hand, the detailed analysis of the Grey Rocky lithics reinforces the particular character of this Howiesons Poort technocomplex, yet it also shows clear technological links with other Middle Stone Age assemblages. PMID:26633008

  14. Lithic fragments, glasses and chondrules from Luna 16 fines.

    NASA Technical Reports Server (NTRS)

    Keil, K.; Prinz, M.; Green, J. A.; Kurat, G.

    1972-01-01

    Electron probe determination of the bulk compositions of igneous and microbreccia lithic fragments, glasses and chondrules from Luna 16 fines and of the compositions of minerals in basaltic lithic fragments. It is found that the Luna 16 fines have a composition more similar to that of Apollo 11 than to those of Apollo 12 and 14 materials. The compositions of lithic fragments, glasses and chondrules from Luna 16 core tube layers A and D are similar. The glasses are compositional analogs of the lithic fragments and are produced largely from igneous rocks. The Luna 16 chondrules have an anorthositic-noritic-troctolitic composition. Evidence for the presence of ferric iron and water-bearing minerals in the Luna 16 material is not obtained. The occurrence of a great variety of igneous rocks in the material confirms an earlier conclusion that large-scale melting or partial melting to a considerable depth and an extensive igneous differentiation must have occurred on the moon.

  15. Crane and Excavator Operator.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    Developed as part of the Marine Corps Institute (MCI) correspondence training program, this course on crane and excavator operation is designed to enable the crane and excavator operator to perform his/her duties more proficiently. Introductory materials include specific information for MCI students, a course introduction, and a study guide…

  16. Thermomechanical milling of accessory lithics in volcanic conduits

    NASA Astrophysics Data System (ADS)

    Campbell, Michelle E.; Russell, James K.; Porritt, Lucy A.

    2013-09-01

    Accessory lithic clasts recovered from pyroclastic deposits commonly result from the failure of conduit wall rocks, and represent an underutilized resource for constraining conduit processes during explosive volcanic eruptions. The morphological features of lithic clasts provide distinctive 'textural fingerprints' of processes that have reshaped them during transport in the conduit. Here, we present the first study focused on accessory lithic clast morphology and show how the shapes and surfaces of these accessory pyroclasts can inform on conduit processes. We use two main types of accessory lithic clasts from pyroclastic fallout deposits of the 2360 B.P. subplinian eruption of Mount Meager, British Columbia, as a case study: (i) rough and subangular dacite clasts, and (ii) variably rounded and smoothed monzogranite clasts. The quantitative morphological data collected on these lithics include: mass, volume, density, 2-D image analysis of convexity (C), and 3-D laser scans for sphericity (Ψ) and smoothness (S). Shaping and comminution (i.e. milling) of clasts within the conduit are ascribed to three processes: (1) disruptive fragmentation due to high-energy impacts between clasts or between clasts and conduit walls, (2) ash-blasting of clasts suspended within the volcanic flux, and (3) thermal effects. We use a simplified conduit eruption model to predict ash-blasting velocities and lithic residence times as a function of clast size and source depth, thereby constraining the lithic milling processes. The extent of shape and surface modification (i.e. rounding and honing) is directly proportional to clast residence times within the conduit prior to evacuation. We postulate that the shallow-seated dacite clasts remain subangular and rough due to short (<2 min) residence times, whereas monzogranite clasts are much more rounded and smoothed due to deeper source depths and consequently longer residence times (up to ˜1 h). Larger monzogranite clasts are smoother than

  17. Hydromechanical Advanced Coal Excavator

    NASA Technical Reports Server (NTRS)

    Estus, Jay M.; Summers, David

    1990-01-01

    Water-jet cutting reduces coal dust and its hazards. Advanced mining system utilizes full-face, hydromechanical, continuous miner. Coal excavator uses high-pressure water-jet lances, one in each of cutting heads and one in movable lance, to make cuts across top, bottom and middle height, respectively, of coal face. Wedge-shaped cutting heads advance into lower and upper cuts in turn, thereby breaking coal toward middle cut. Thrust cylinders and walking pads advance excavator toward coal face.

  18. Techno-Cultural Characterization of the MIS 5 (c. 105 – 90 Ka) Lithic Industries at Blombos Cave, Southern Cape, South Africa

    PubMed Central

    Douze, Katja; Wurz, Sarah; Henshilwood, Christopher Stuart

    2015-01-01

    Blombos Cave is well known as an important site for understanding the evolution of symbolically mediated behaviours among Homo sapiens during the Middle Stone Age, and during the Still Bay in particular. The lower part of the archaeological sequence (M3 phase) contains 12 layers dating to MIS 5 with ages ranging from 105 to 90 ka ago (MIS 5c to 5b) that provide new perspectives on the technological behaviour of these early humans. The new data obtained from our extensive technological analysis of the lithic material enriches our currently limited knowledge of this time period in the Cape region. By comparing our results with previously described lithic assemblages from sites south of the Orange River, we draw new insights on the extent of the techno-cultural ties between these sites and the M3 phase at Blombos Cave and highlight the importance of this phase within the Middle Stone Age cultural stratigraphy. PMID:26580219

  19. Techno-Cultural Characterization of the MIS 5 (c. 105 - 90 Ka) Lithic Industries at Blombos Cave, Southern Cape, South Africa.

    PubMed

    Douze, Katja; Wurz, Sarah; Henshilwood, Christopher Stuart

    2015-01-01

    Blombos Cave is well known as an important site for understanding the evolution of symbolically mediated behaviours among Homo sapiens during the Middle Stone Age, and during the Still Bay in particular. The lower part of the archaeological sequence (M3 phase) contains 12 layers dating to MIS 5 with ages ranging from 105 to 90 ka ago (MIS 5c to 5b) that provide new perspectives on the technological behaviour of these early humans. The new data obtained from our extensive technological analysis of the lithic material enriches our currently limited knowledge of this time period in the Cape region. By comparing our results with previously described lithic assemblages from sites south of the Orange River, we draw new insights on the extent of the techno-cultural ties between these sites and the M3 phase at Blombos Cave and highlight the importance of this phase within the Middle Stone Age cultural stratigraphy. PMID:26580219

  20. Spatial and chronological patterns of the lithics of hearth 1 at the Gravettian site Krems-Wachtberg

    PubMed Central

    Thomas, Roswitha; Ziehaus, Johanna

    2014-01-01

    A spatial and micro-stratigraphic interpretation of the Gravettian open-air site Krems-Wachtberg in Lower Austria uses analysis of the lithic artefacts of an area of the excavations. The results are based on conclusive aspects of the artefact morphology and raw material attribution. Investigations focus on the acquisition of the spatial structure of living floor AH (archaeological horizon) 4.4 with a well-preserved hearth. Different utilization phases of hearth 1 with their relationships to the surrounding areas are discussed and a comparison of the in situ AH 4.4 and the post-occupational deposition of AH 4.11 presented. The examination of the artefact typology supports an attribution to the Early Gravettian of Central Europe (Pavlovian, 30–24 ka BP). PMID:25642117

  1. Lunar Regolith Excavation Competition

    NASA Technical Reports Server (NTRS)

    Liles, Cassandra

    2009-01-01

    The Lunar Regolith Excavation Competition is a new competition that needs graphics, logos, rules, as well as an arena. Although this is the first year of the competition, the competition is modeled after an existing competition, the Centennial Lunar Excavator Challenge. This competition however is aimed at college students. This makes the challenge identifying key aspects of the original competition and modeling them to fit into an easier task, and creating exciting advertisement that helps encourage participation. By using a youth focus group, young insight, as well as guiding advice from experts in the field, hopefully an arena can be designed and built, rules can be molded and created to fit, and alluring graphics can be printed to bring about a successful first year of the Lunar Regolith Excavation Competition.

  2. Mobile continuous lunar excavation

    NASA Technical Reports Server (NTRS)

    Paterson, John L.

    1992-01-01

    A novel approach to the concept of lunar mining and the use of in situ oxygen, metallics, and ceramics is presented. The EVA time required to set up, relocate, and maintain equipment, as well as the cost per pound of shipping the mining and processing equipment to the moon are considered. The proposed soil fracturing/loading mechanisms are all based loosely on using the Apollo Lunar Roving Vehicle (LRV) Frame. All use motor driven tracks for mobility in the forward/reverse and left/right direction. All mechanisms employ the concept of rototillers which are attached to a gantry which, through the use of motor-driven lead screws, provide the rototillers with an up/down capability. A self-reactant excavator, a local mass enhanced excavator, and a soil reactant excavator are illustrated.

  3. Analysis of Site Formation and Assemblage Integrity Does Not Support Attribution of the Uluzzian to Modern Humans at Grotta del Cavallo.

    PubMed

    Zilhão, João; Banks, William E; d'Errico, Francesco; Gioia, Patrizia

    2015-01-01

    Based on the morphology of two deciduous molars and radiocarbon ages from layers D and E of the Grotta del Cavallo (Lecce, Italy), assigned to the Uluzzian, it has been proposed that modern humans were the makers of this Early Upper Paleolithic culture and that this finding considerably weakens the case for an independent emergence of symbolism among western European Neandertals. Reappraisal of the new dating evidence, of the finds curated in the Taranto Antiquities depot, and of coeval publications detailing the site's 1963-66 excavations shows that (a) Protoaurignacian, Aurignacian and Early Epigravettian lithics exist in the assemblages from layers D and E, (b) even though it contains both inherited and intrusive items, the formation of layer D began during Protoaurignacian times, and (c) the composition of the extant Cavallo assemblages is influenced in a non-negligible manner by the post-hoc assignment of items to stratigraphic units distinct from that of original discovery. In addition, a major disturbance feature affected the 1960s excavation trench down to Mousterian layer F, this feature went unrecognized until 1964, the human remains assigned to the Uluzzian were discovered that year and/or the previous year, and there are contradictions between field reports and the primary anthropological description of the remains as to their morphology and level of provenience. Given these major contextual uncertainties, the Cavallo teeth cannot be used to establish the authorship of the Uluzzian. Since this technocomplex's start date is ca. 45,000 calendar years ago, a number of Neandertal fossils are dated to this period, and the oldest diagnostic European modern human fossil is the <41,400 year-old Oase 1 mandible, Neandertal authorship of the Uluzzian remains the parsimonious reading of the evidence. PMID:26154139

  4. Analysis of Site Formation and Assemblage Integrity Does Not Support Attribution of the Uluzzian to Modern Humans at Grotta del Cavallo

    PubMed Central

    Zilhão, João; Banks, William E.; d’Errico, Francesco; Gioia, Patrizia

    2015-01-01

    Based on the morphology of two deciduous molars and radiocarbon ages from layers D and E of the Grotta del Cavallo (Lecce, Italy), assigned to the Uluzzian, it has been proposed that modern humans were the makers of this Early Upper Paleolithic culture and that this finding considerably weakens the case for an independent emergence of symbolism among western European Neandertals. Reappraisal of the new dating evidence, of the finds curated in the Taranto Antiquities depot, and of coeval publications detailing the site’s 1963–66 excavations shows that (a) Protoaurignacian, Aurignacian and Early Epigravettian lithics exist in the assemblages from layers D and E, (b) even though it contains both inherited and intrusive items, the formation of layer D began during Protoaurignacian times, and (c) the composition of the extant Cavallo assemblages is influenced in a non-negligible manner by the post-hoc assignment of items to stratigraphic units distinct from that of original discovery. In addition, a major disturbance feature affected the 1960s excavation trench down to Mousterian layer F, this feature went unrecognized until 1964, the human remains assigned to the Uluzzian were discovered that year and/or the previous year, and there are contradictions between field reports and the primary anthropological description of the remains as to their morphology and level of provenience. Given these major contextual uncertainties, the Cavallo teeth cannot be used to establish the authorship of the Uluzzian. Since this technocomplex’s start date is ca. 45,000 calendar years ago, a number of Neandertal fossils are dated to this period, and the oldest diagnostic European modern human fossil is the <41,400 year-old Oase 1 mandible, Neandertal authorship of the Uluzzian remains the parsimonious reading of the evidence. PMID:26154139

  5. Overview and new results from large-scale excavations in Schöningen.

    PubMed

    Serangeli, Jordi; Böhner, Utz; Van Kolfschoten, Thijs; Conard, Nicholas J

    2015-12-01

    Archaeological finds including spears, other wooden artifacts, lithic artifacts, and bones with impact scars and cut marks document the repeated presence of hominins on the shoreline of an approximately 300,000 year old lake near Schöningen in Northern Germany. Continuing excavations have uncovered in the locality "Schöningen" at least 20 sites dating to the late Lower Paleolithic. Schöningen is therefore not only a singular archaeological site with remarkable finds; it is a vast locality that preserves a multifaceted archaeological landscape with numerous sites. Ongoing excavations have exposed several large surfaces with organic materials dating to MIS 9. In particular, recent excavations have uncovered new sections belonging to the original Spear Horizon from Schöningen 13 II-4 (the Horse Butchery Site). Current research in Schöningen places the exceptional artifacts within a spatial and environmental context, and provides a wealth of new information on the subsistence strategies and settlement dynamics of the inhabitants of these short-term lakeside occupations. Schöningen, with an overall excavated area of 9400 m(2), is one of the largest excavated archaeological localities from MIS 9. Here we present a summary of all the sites, as well as the most relevant excavated areas since 2008 (excavations Tübingen/NLD). PMID:26596727

  6. Petrology of some lithic fragments from Luna 20.

    NASA Technical Reports Server (NTRS)

    Roedder, E.; Weiblen, P. W.

    1973-01-01

    Microscopic and electron microprobe studies were made of polished thin sections of part of a 30-mg sample of 250- to 500-micron lunar soil returned by Luna 20 from a point between Mare Fecunditatis and Mare Crisium. Very fine-grained lithic (crystalline) rock fragments, composing about one-fifth of the total sample, have mineralogical compositions equivalent to various types of gabbro, anorthositic gabbro, gabbroic anorthosite, and troctolite, with minor basalt. The textures now observed in these fragments are in large part metamorphic. Twenty-seven electron microprobe analyses of minerals from these fragments are presented, including olivine, plagioclase, pyroxene, spinel, nickel-iron, and a Zr-Ti-REE mineral possibly similar to 'phase B' of Lovering and Wark (1971). Analyses of seven melt inclusions and 28 defocused beam analyses of lithic fragments are also given. Some of the fragments contain 'gas' inclusions which, along with the fine grain size, are believed to indicate final crystallization under low pressure near surface conditions.

  7. Excavator Design Validation

    NASA Technical Reports Server (NTRS)

    Pholsiri, Chalongrath; English, James; Seberino, Charles; Lim, Yi-Je

    2010-01-01

    The Excavator Design Validation tool verifies excavator designs by automatically generating control systems and modeling their performance in an accurate simulation of their expected environment. Part of this software design includes interfacing with human operations that can be included in simulation-based studies and validation. This is essential for assessing productivity, versatility, and reliability. This software combines automatic control system generation from CAD (computer-aided design) models, rapid validation of complex mechanism designs, and detailed models of the environment including soil, dust, temperature, remote supervision, and communication latency to create a system of high value. Unique algorithms have been created for controlling and simulating complex robotic mechanisms automatically from just a CAD description. These algorithms are implemented as a commercial cross-platform C++ software toolkit that is configurable using the Extensible Markup Language (XML). The algorithms work with virtually any mobile robotic mechanisms using module descriptions that adhere to the XML standard. In addition, high-fidelity, real-time physics-based simulation algorithms have also been developed that include models of internal forces and the forces produced when a mechanism interacts with the outside world. This capability is combined with an innovative organization for simulation algorithms, new regolith simulation methods, and a unique control and study architecture to make powerful tools with the potential to transform the way NASA verifies and compares excavator designs. Energid's Actin software has been leveraged for this design validation. The architecture includes parametric and Monte Carlo studies tailored for validation of excavator designs and their control by remote human operators. It also includes the ability to interface with third-party software and human-input devices. Two types of simulation models have been adapted: high-fidelity discrete

  8. Shoring pumping station excavation

    SciTech Connect

    Glover, J.B.; Reardon, D.J. )

    1991-11-01

    The city of San Mateo, Calif., operates three 12- to 50-year old wastewater pumping stations on a 24-m (80-ft) wide lot located in a residential area near San Francisco Bay. Because the aging stations have difficulty pumping peak 2.19-m{sup 3}/s (50-mgd) wet-weather flows and have structural and maintenance problems, a new 2.62-m{sup 3}/s (60-mgd) station was proposed - the Dale Avenue Pumping Station - to replace the existing ones. To prevent potential damage to adjacent homes, the new station was originally conceived as a circular caisson type; however, a geotechnical investigation recommended against this type of structure because the stiff soils could make sinking the structure difficult. This prompted an investigation of possible shoring methods for the proposed structure. Several shoring systems were investigated, including steel sheeting, soldier beams and lagging, tieback systems, open excavation, and others; however, each had disadvantages that prevented its use. Because these conventional techniques were unacceptable, attention was turned to using deep soil mixing (DSM) to create a diaphragm wall around the area to be excavated before constructing the pumping station. Although this method has been used extensively in Japan since 1983, the Dale Avenue Pumping Station would be the technology's first US application. The technology's anticipated advantages were its impermeability, its fast and efficient installation that did not require tiebacks under existing homes, its adaptability to subsurface conditions ranging from soft ground to stiff clay to gravels, and its lack of pile-driving requirements that would cause high vibration levels during installation.

  9. Electron Microprobe Analyses of Lithic Fragments and Their Minerals from Luna 20 Fines

    NASA Technical Reports Server (NTRS)

    Conrad, G. H.; Hlava, P. F.; Green, J. A.; Moore, R. B.; Moreland, G.; Dowty, E.; Prinz, M.; Keil, K.; Nehru, C. E.; Bunch, T. E.

    1973-01-01

    The bulk analyses (determined with the broad beam electron microprobe technique) of lithic fragments are given in weight percentages and are arranged according to the rock classification. Within each rock group the analyses are arranged in order of increasing FeO content. Thin section and lithic fragment numbers are given at the top of each column of analysis and correspond to the numbers recorded on photo mosaics on file in the Institute of Meteoritics. CIPW molecular norms are given for each analysis. Electron microprobe mineral analyses (given in oxide weight percentages), structural formulae and molecular end member values are presented for plagioclase, olivine, pyroxene and K-feldspar. The minerals are selected mostly from lithic fragments that were also analyzed for bulk composition. Within each mineral group the analyses are presented according to the section number and lithic fragment number. Within each lithic fragment the mineral analyses are arranged as follows: Plagioclase in order of increasing CaO; olivine and pyroexene in order of increasing FeO; and K-feldspar in order of increasing K2O. The mineral grains are identified at the top of each column of analysis by grain number and lithic fragment number.

  10. Percussive Excavation of Lunar Soil

    NASA Technical Reports Server (NTRS)

    Whittaker, Matthew P.

    2008-01-01

    It has been suggested using a percussive motion could improve the efficiency of excavation by up to 90%. If this is proven to be true it would be very beneficial to excavation projects on the Moon and Mars. The purpose of this study is to design, build and test a percussive tool which could dig a trench and then compare this data against that of a non-percussive tool of the same shape and size. The results of this test thus far have been inconclusive due to malfunctions in the testbed and percussive bucket; however, experimental results from small scale experiments confirm this higher efficiency and support further testing.

  11. Radiation history of lunar microbreccias and lithic chrondrules from Weston meteorite by track data

    SciTech Connect

    Kashkarov, L.L.; Genaeva, L.I.; Tarasov, L.S.; Baryshnikova, G.V.; Lavrukhina, A.K.

    1983-02-15

    Tracks generated in the lithic chondrules of the brecciated Weston meteorite as well as in the lunar microbreccias by iron group nuclei of solar cosmic rays are studied. The results for about 2000 olivine and pyroxene grains contained in 67 lithic chondrules indicate that a relict irradiation of the material occurred at an early stage in solar system formation, i.e., before these chondrules were assembled. The results for about 1000 olivine and pyroxene grains in 13 microbreccias strengthen our earlier conclusion that part of the chondrules from the Weston meteorite may have formed in processes analogous to brecciation. The newly obtained data confirm that the formation processes of the Weston lithic chondrules, containing solar flare irradiated crystals, were similar to the impact formation of microbreccias on the lunar regolith without heating compacted material up to temperatures of 600/sup 0/-700 /sup 0/C.

  12. Remote Excavation System test plan

    SciTech Connect

    Walker, S.; Hyde, R.A.

    1993-05-01

    The Office of Technology Development (OTD) established the Robotics Technology Development Program (RTDP) to integrate robotic development activities on a national basis; provide needs-oriented, timely, and economical robotics technology to support environmental and waste operations activities at Department of Energy (DOE) sites; and provide the focus and direction for the near term (less than five years) and guidance for the tong-term (five to twenty years) research and development efforts for site-specific problems. The RTDP consists of several programs including the Buried Waste Robotics Program (BWRP), which addresses remote buried waste applications. The Remote Excavation System (RES) was developed under the RTDP to provide a safer method of excavating hazardous materials for both the DOE and the Department of Defense (DOD). The excavator, initially developed by the DOD as a manually-operated small excavator, has been modified for teleoperation with joint funding from the BWRP and the DOD. The Buried Waste Integrated Demonstration (BWID) and the Uranium Soils Integrated Demonstration (USID) are funding the demonstration, testing, and evaluation of the RES covered in this test plan. This document covers testing both at Oak Ridge National Laboratory (ORNL) and the Idaho National Engineering Laboratory (INEL), as funded by BWID and USID. This document describes the tests planned for the RES demonstration for the BWRP. The purposes of the test plan are (1) to establish test parameters to ensure that the demonstration results are deemed useful and usable and (2) to demonstrate performance in a safe manner within all regulatory requirements.

  13. Lunar Excavator Preliminary Test Video

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This video shows a preliminary test of the boom and bucket wheel assembly of the lunar excavator prototype developed by the Center for Commercial Applications of Combustion at the Colorado School of Mines in Golden. According to Michael Duke, director for the center, the wheel on the end of the boom can dig up 45.36 kilograms (100 pounds) of dirt each hour which is several times the weight of the entire device.

  14. Reduce costs with vacuum excavation

    SciTech Connect

    Vitale, S.A.

    1983-09-01

    Although vacuum excavation equipment and methods are in their infancy, this developing technology offers tremendous promise for the future. The author explains Brooklyn Union Gas Co.'s experience with five vacuum trucks and the procedures that are used. In recent years, the higher cost of natural gas has increased the need for gas utilities to reduce their operating expenses. One way, which has been successful at Brooklyn Union Gas, is the use of vacuum excavation. Although vacuum excavation equipment and techniques are in their infancy, this developing technology offers substantial savings today and tremendous promise for the future. Brooklyn Union started its vacuum digging program by locating keyhole cutoffs--small surface openings ranging from 1 ft by 1 ft to 1 1/2 ft by 1 1/2 ft (0.3 m to 0.45 m square). It is no easy task to accurately locate a service that was installed 60 years ago. Reading the street indications, locating an existing curb valve or repair opening, gaining access to the building, making a physical lineup, and using an M-scope, plus any other tools available, have produced a high success rate.

  15. Hemodynamics of focal choroidal excavations.

    PubMed

    Soma, Ryoko; Moriyama, Muka; Ohno-Matsui, Kyoko

    2015-04-01

    The purpose of this study was to investigate the hemodynamics of focal choroidal excavations (FCEs). Four eyes of four patients with a FCE were studied. Indocyanine green angiography (ICGA), laser speckle flowgraphy (LSFG), optical coherence tomography (OCT), and multi-focal electroretinography (mfERG) were performed to investigate the choroidal hemodynamics and the morphological and functional changes. The mean depth of the FCE determined by OCT was 222.5 ± 49.5 μm with a range of 164-272 μm. In one case, subretinal fluid was observed in the excavation, and in three cases, subretinal fluid was not observed. ICGA showed hypofluorescence, and laser flowgraphy (LSFG) showed decreased choroidal blood flow at the excavation in all cases. Three cases were symptomatic, and the amplitudes of the mfERGs were reduced. FCEs cause a decrease of choroidal blood flow. In three of four cases, the mfERGs were depressed over the FCEs leading to symptoms. PMID:25626897

  16. Zero Horizontal Reaction Force Excavator

    NASA Technical Reports Server (NTRS)

    Mueller, Robert P. (Inventor); Nick, Andrew J. (Inventor); Schuler, Jason M. (Inventor); Smith, Jonathan D. (Inventor)

    2015-01-01

    An excavator includes a mobile chassis with a first bucket drum and a second bucket drum coupled thereto. The first bucket drum and second bucket drum are coupled to the chassis for positioning thereof on the surface at opposing ends of the chassis. Each first scoop on the first bucket drum is a mirror image of one second scoop on the second bucket drum when (i) the first bucket drum and second bucket drum are on the surface adjacent opposing ends of the chassis, and (ii) the first bucket drum is rotated in one direction and the second bucket drum is simultaneously rotated in an opposing direction.

  17. Metasomatism, titanian acmite, and alkali amphiboles in lithic- wacke inclusions within the Coyote Peak diatreme, Humboldt County, California.

    USGS Publications Warehouse

    Czamanske, S.A.; Atkin, G.K.

    1985-01-01

    Lithic-wacke inclusions within the alkali-ultramafic diatreme at Coyote Peak record a history of pronounced metasomatism and crystal growth. The dominant metasomatic changes were loss of Si from the inclusions and mass influx of K, due to an unusually high K activity in the ultramafic host. The reaction with K converted much of the clay, quartz and lithic fraction of the lithic wacke into microcline, and exchanged Na from abundant clastic albite. Probe analyses are tabulated for cores and rims of titanian acmites, augites and alkali amphiboles. -J.A.Z.

  18. Mechanical tunnel excavation in welded tuff

    SciTech Connect

    Sperry, P.E.

    1991-12-31

    The Technical Review Board for the US high-level radioactive waste facility at Yucca Mountain has recommended maximum use of {open_quotes}the most modern mechanical excavation techniques...in order to reduce disturbance to the rock walls and to achieve greater economy of time and cost.{close_quotes} Tunnels for the waste repository at Yucca Mountain can be economically constructed with mechanical excavation equipment. This paper presents the results of mechanical excavation of a tunnel in welded tuff, similar to the tuffs of Yucca Mountain. These results are projected to excavation of emplacement drifts in Yucca Mountain using a current state-of-the-art tunnel boring machine (TBM).

  19. Conduit evolution during the Avellinio Plinian eruption (Vesuvius): insights from fieldwork, lithic grain size distributions and modelling

    NASA Astrophysics Data System (ADS)

    Hanson, Jonathan; Rust, Alison; Phillips, Jeremy; Sulpizio, Roberto; Engwell, Samantha; Costa, Antonio

    2016-04-01

    Large-scale explosive eruptions are modulated by a combination of magmatic and conduit processes, including changes in the geometry of the conduit as host rocks are eroded from the conduit walls and vent region. This study of deposits 1-45 km from source of the main, quasi-steady Plinian phases of the 3949 ± 10 yBP Avellino eruption of Vesuvius (EU2 and EU3) demonstrates the potential for measurements of lithics and xenoliths to constrain subsurface eruption processes. The lithics comprise volcanic rocks derived from the upper ˜2700 m of the conduit, carbonates from the lower conduit and magma reservoir wall rocks. The lithics (free clasts) are thought to be incorporated into the erupting mixture by conduit wall implosion around and above the fragmentation depth as well as shallow vent spalling, whilst xenoliths are interpreted to result from viscous shear stresses applied to the conduit walls pre-fragmentation. The lithology of xenoliths indicates that they are sourced from relatively deep in the conduit, and their scarcity indicates that there is only minor conduit erosion below magma fragmentation during the Plinian eruptions. In contrast total lithic volumes calculated for EU2 and EU3 are 0.002 and 0.02 km3, respectively, which corresponds to 8 % and 18 % of the total erupted volume. Lava lithics dominate, making up 69 and 74 % of the total lithic volume for EU2 and EU3, respectively. The majority of conduit erosion occurred above the fragmentation depth, in the upper few kilometers of the conduit, and scales approximately with the increase in mass discharge rate between the two phases. Individual component (total lithic, carbonate, lava) Lithic Total Grain Size Distributions (L-TGSDs) provide insights into rock failure mechanisms. The fractal dimensions of the majority of the L-TGSDs are approximately 2 (grain size in φ against log2 no. of grains), inferred to be the result of conduit implosion modified by initial rock characteristics. The lava lithics from

  20. The surveillant assemblage.

    PubMed

    Haggerty, K D; Ericson, R V

    2000-12-01

    George Orwell's 'Big Brother' and Michel Foucault's 'panopticon' have dominated discussion of contemporary developments in surveillance. While such metaphors draw our attention to important attributes of surveillance, they also miss some recent dynamics in its operation. The work of Gilles Deleuze and Felix Guattari is used to analyse the convergence of once discrete surveillance systems. The resultant 'surveillant assemblage' operates by abstracting human bodies from their territorial settings, and separating them into a series of discrete flows. These flows are then reassembled in different locations as discrete and virtual 'data doubles'. The surveillant assemblage transforms the purposes of surveillance and the hierarchies of surveillance, as well as the institution of privacy. PMID:11140886

  1. Lithic breccia and ignimbrite erupted during the collapse of Crater Lake Caldera, Oregon

    USGS Publications Warehouse

    Druitt, T.H.; Bacon, C.R.

    1986-01-01

    The climactic eruption of Mount Mazama (6845 y.B.P.) vented a total of ???50 km3 of compositionally zoned rhyodacitic to basaltic magma from: (a) a single vent as a Plinian pumice fall deposit and the overlying Wineglass Welded Tuff, and (b) ring vents as ignimbrite and coignimbrite lithic breccia accompanying the collapse of Crater Lake caldera. New field and grain-size data for the ring-vent products are presented in this report. The coarse-grained, poorly bedded, clast-supported lithic breccia extends as far as 18 km from the caldera center. Like the associated ignimbrite, the breccia is compositionally zoned both radially and vertically, and silicic, mixed, and mafic types can be recognized, based on the proportion of rhyodacitic pumice. Matrix fractions in silicic breccias are depleted of fines and are lithic- and crystal-enriched relative to silicic ignimbrite due to vigorous gas sorting during emplacement. Ignimbrite occurs as a proximal veneer deposit overlying the breccia, a medial (??? 8 to ??? 25 km from the caldera center), compositionally zoned valley fill as much as > 110 m thick, and an unzoned distal ({slanted equal to or greater-than} 20 km) facies which extends as far as 55 km from the caldera. Breccia within ??? 9 km of the caldera center is interpreted as a coignimbrite lag breccia formed within the deflation zone of the collapsing ring-vent eruption columns. Expanded pyroclastic flows of the deflation zone were probably vertically graded in both size and concentration of blocks, as recently postulated for some turbidity currents. An inflection in the rate of falloff of lithic-clast size within the lithic breccia at ??? 9 km may mark the outer edge of the deflation zone or may be an artifact of incomplete exposure. The onset of ring-vent activity at Mt. Mazama was accompanied by a marked increase in eruptive discharge. Pyroclastic flows were emplaced as a semicontinuous stream, as few ignimbrite flow-unit boundaries are evident. As eruption from

  2. Toxic hazards of underground excavation

    SciTech Connect

    Smith, R.; Chitnis, V.; Damasian, M.; Lemm, M.; Popplesdorf, N.; Ryan, T.; Saban, C.; Cohen, J.; Smith, C.; Ciminesi, F.

    1982-09-01

    Inadvertent intrusion into natural or man-made toxic or hazardous material deposits as a consequence of activities such as mining, excavation or tunnelling has resulted in numerous deaths and injuries in this country. This study is a preliminary investigation to identify and document instances of such fatal or injurious intrusion. An objective is to provide useful insights and information related to potential hazards due to future intrusion into underground radioactive-waste-disposal facilities. The methodology used in this study includes literature review and correspondence with appropriate government agencies and organizations. Key categories of intrusion hazards are asphyxiation, methane, hydrogen sulfide, silica and asbestos, naturally occurring radionuclides, and various mine or waste dump related hazards.

  3. Archaeology Excavation Simulation: Correcting the Emphasis

    ERIC Educational Resources Information Center

    Thistle, Paul C.

    2012-01-01

    Museums offering archaeological programs often attempt to use the "sandbox approach" to simulate archaeological excavation work. However, in light of the definition of simulation, and given the realities of actual professional practice in archaeological excavation, the author argues that the activity of troweling for artifacts in loose sand places…

  4. Regolith Advanced Surface Systems Operations Robot Excavator

    NASA Technical Reports Server (NTRS)

    Mueller, Robert P.; Smith, Jonathan D.; Ebert, Thomas; Cox, Rachel; Rahmatian, Laila; Wood, James; Schuler, Jason; Nick, Andrew

    2013-01-01

    The Regolith Advanced Surface Systems Operations Robot (RASSOR) excavator robot is a teleoperated mobility platform with a space regolith excavation capability. This more compact, lightweight design (<50 kg) has counterrotating bucket drums, which results in a net-zero reaction horizontal force due to the self-cancellation of the symmetrical, equal but opposing, digging forces.

  5. Flow direction indicators in lithic-rich, basal ground layers in western exposures of the Miocene Peach Spring Tuff, California

    NASA Astrophysics Data System (ADS)

    Buesch, D.

    2012-12-01

    Lithic-rich, basal ground layer (BGL) deposits occur in three western exposures of the 18.7 Ma Peach Spring Tuff (PST), and structures indicate directions of transport in the pyroclastic flow. Locations include (1) Kane Wash (Newberry Mountains), (2) "West Gem" (Daggett Ridge), and (3) Alvord Mountain area. These locations are 190-225 km from the PST source in the Silver Creek Caldera, southwest Black Mountain, Arizona (Pearthree and others, 2009); however, ~50 km is from extension across the Lower Colorado River Extensional Corridor. In each location, many lithic clasts were locally derived. Lithic-rich horizons in Kane Wash exposures of the PST were described by Buesch (1991). Total thickness of valley-filling ignimbrite ranges from <1-30 m and was deposited on alluvial fan and axial stream sandstone. Thickness of 8 individual lithic-rich horizons (a type of BGL) range from 4-300 cm with lithic clasts 2-472 cm. Clast size-grading, imbrication, and elongation indicate directions of flow. Each horizon was attributed to (1) incorporation and concentration of local clasts into a boundary layer of the pyroclastic flow as it traversed topography, (2) decoupling of a lithic-rich layer from the over riding flow, (3) independent movement of a lithic-rich flow along local topography (180°±30°) with the ash-rich pyroclastic flow direction probably independent of local topography, but along the main paleovalley (245°±20°), and (4) introduction and westward deflection of lithic-rich flows into the main, valley-filling, pyroclastic flow. Multiple lithic-rich horizons indicate repeated, locally developed boundary layers from the body of the pyroclastic flow throughout the flow history. In the West Gem exposure, the PST is 5.3 m thick and was deposited on alluvial sandstone. The 60-cm thick, lithic-rich, BGL contains lithic clasts <25 cm. Poorly developed clast imbrication and elongation, and a rip-up flap from the BGL folded into the lower part of the ignimbrite, indicate

  6. Indirect pulp therapy and stepwise excavation.

    PubMed

    Bjørndal, Lars

    2008-01-01

    Various treatment concepts have been suggested to solve the deep carious lesion dilemma. Recent systematic reviews are presented. Their conclusions are based on very few studies, and the main message is that optimal randomized clinical studies are lacking. Observational studies on indirect pulp treatment and stepwise excavation demonstrate that these treatments avoid pulp exposures, but it cannot be said which approach is best. A less invasive modified stepwise excavation approach is described, focusing on changing on active lesion into on arrested lesion even without performing an excavation close to the pulp. In Denmark and Sweden a randomized clinical multi-center trial is currently taking place, the Caries and Pulp (CAP) trial. This trial is investigating the effects of stepwise excavation over 2 visits versus 1 complete excavation of deep caries in permanent teeth. Guidelines for treatment are presented. PMID:18615988

  7. Indirect pulp therapy and stepwise excavation.

    PubMed

    Bjørndal, Lars

    2008-07-01

    Various treatment concepts have been suggested to solve the deep carious lesion dilemma. Recent systematic reviews are presented. Their conclusions are based on very few studies, and the main message is that optimal randomized clinical studies are lacking. Observational studies on indirect pulp treatment and stepwise excavation demonstrate that these treatments avoid pulp exposures, but it cannot be said which approach is best. A less invasive modified stepwise excavation approach is described, focusing on changing an active lesion into an arrested lesion even without performing an excavation close to the pulp. In Denmark and Sweden a randomized clinical multi-center trial is currently taking place, the Caries and Pulp (CAP) trial. This trial is investigating the effects of stepwise excavation over 2 visits versus 1 complete excavation of deep caries in permanent teeth. Guidelines for treatment are presented. PMID:18565369

  8. Lithic Landscapes: Early Human Impact from Stone Tool Production on the Central Saharan Environment

    PubMed Central

    Foley, Robert A.; Lahr, Marta Mirazón

    2015-01-01

    Humans have had a major impact on the environment. This has been particularly intense in the last millennium but has been noticeable since the development of food production and the associated higher population densities in the last 10,000 years. The use of fire and over-exploitation of large mammals has also been recognized as having an effect on the world’s ecology, going back perhaps 100,000 years or more. Here we report on an earlier anthropogenic environmental change. The use of stone tools, which dates back over 2.5 million years, and the subsequent evolution of a technologically-dependent lineage required the exploitation of very large quantities of rock. However, measures of the impact of hominin stone exploitation are rare and inherently difficult. The Messak Settafet, a sandstone massif in the Central Sahara (Libya), is littered with Pleistocene stone tools on an unprecedented scale and is, in effect, a man-made landscape. Surveys showed that parts of the Messak Settafet have as much as 75 lithics per square metre and that this fractured debris is a dominant element of the environment. The type of stone tools—Acheulean and Middle Stone Age—indicates that extensive stone tool manufacture occurred over the last half million years or more. The lithic-strewn pavement created by this ancient stone tool manufacture possibly represents the earliest human environmental impact at a landscape scale and is an example of anthropogenic change. The nature of the lithics and inferred age may suggest that hominins other than modern humans were capable of unintentionally modifying their environment. The scale of debris also indicates the significance of stone as a critical resource for hominins and so provides insights into a novel evolutionary ecology. PMID:25760999

  9. Clamshell excavation of a permeable reactive barrier

    NASA Astrophysics Data System (ADS)

    Molfetta, Antonio Di; Sethi, Rajandrea

    2006-06-01

    Nowadays, permeable reactive barriers (PRB) are one of the most widespread techniques for the remediation of contaminated aquifers. Over the past 10 years, the use of iron-based PRBs has evolved from innovative to accepted standard practice for the treatment of a variety of groundwater contaminants (ITRC in: Permeable reactive barriers: lessons learned/new directions. The Interstate Technology and Regulatory Council, Permeable Reactive Barriers Team 2005). Although, a variety of excavation methods have been developed, backhoe excavators are often used for the construction of PRBs. The aim of this study is to describe the emplacement of a full-scale PRB and the benefits deriving from the use of a crawler crane equipped with a hydraulic grab (also known as clamshell excavator) in the excavation phases. The studied PRB was designed to remediate a chlorinated hydrocarbons plume at an old industrial landfill site, in Avigliana, near the city of Torino, in Italy. The continuous reactive barrier was designed to be 120 m long, 13 m deep, and 0.6 m thick. The installation of the barrier was accomplished using a clamshell for the excavation of the trench and a guar-gum slurry to support the walls. The performance of this technique was outstanding and allowed the installation of the PRB in 7 days. The degree of precision of the excavation was very high because of the intrinsic characteristics of this excavation tool and of the use of a concrete curb to guide the hydraulic grab. Moreover, the adopted technique permitted a saving of bioslurry thus minimizing the amount of biocide required.

  10. Petrology and geochemistry of lithic fragments separated from the Apollo 15 deep-drill core

    NASA Technical Reports Server (NTRS)

    Lindstrom, M. M.; Nielsen, R. L.; Drake, M. J.

    1977-01-01

    Petrological and geochemical analysis of lithic fragments separated from the Apollo 15 deep-drill core showed these fragments to fall into the essentially the same range of rock types as observed in surface soil samples and large rock samples. Three particles are singled out as being of special interest. One sample is a mare basalt containing extremely evolved phases. The particle may represent small-scale imperfect crystal/liquid separation in a lava flow. A green glass particle is not the ultramafic emerald green glass described from the Apollo 15 site, but rather an ANT-like light green color, and has a quite different chemical composition from the ultramafic variety. One mare basalt displays a positive Eu anomaly and is enriched in plagioclase relative to olivine plus pyroxene.

  11. Dolomite diagenesis and porosity preservation in lithic reservoirs: Carmopolis member, Sergipe-Alagoas Basin, northeastern Brazil

    SciTech Connect

    Souza, R.S. de; De Ros, L.F.; Morad, S.

    1995-05-01

    The lithic sandstones and conglomerates of the Carmopolis Member of the Muribeca Formation (Aptian) were deposited by fan deltas, alluvial fans, and braid deltas that prograded from low-grade metamorphic terrains into the Sergipe-Alagoas rift basin during the opening of the South Atlantic. Initial carbonates in the Carmopolis reservoirs (presently at depths of 180-2200 m) were marine (high-Mg calcite/aragonite) grain rims, allochems, stromatolitic laminites, and meteoric calcite. These carbonates were subsequently replaced by dolomite/ankerite ({delta}18O{sub PDB} = -7.3 to -4.1{per_thousand}; {delta}{sup 13}C{sub PDB} = -15 to +16.2{delta}) derived from ascending thermobaric fluids prior to oil emplacement. These fluids also caused the direct precipitation of dolomite/ankerite cements and the replacement of dolomite/ankerite cements and the replacement of nonferroan dolomite by ferroan dolomite/ankerite. Rocks lacking early cements were strongly compacted, losing their primary intergranular porosity and permeability, whereas massively cemented rocks show only minor compaction and further diagenetic modifications. Partial cementation has greatly limited the compaction and preserved intergranular porosity, allowing the partial dissolution of carbonates and framework grains and the precipitation of replacive ferroan dolomite/ankerite and pyrite. Offshore reservoirs show late porosity reduction by the precipitation of quartz, kaolinite/dickite, saddle dolomite, and ferroan calcite. Experimental analyses of porosity and permeability reduction under pressure confirmed the importance of early cementation in the preservation of porosity in lithic rocks with ductile framework.

  12. Mechanical excavator performance in Yucca Mountain tuffs

    SciTech Connect

    Ozdemir, L.; Hansen, F.D.

    1991-01-01

    A research effort of four phases is in progress at the Colorado School of Mines. The overall program will evaluate the cutability of welded tuff and other lithologies likely to be excavated at Yucca Mountain in the site characterization process. Several mechanical systems are considered with emphasis given to the tunnel boring machine. The research comprises laboratory testing, linear drag bit and disc cutter tests and potentially large-scale laboratory demonstrations to support potential use of a tunnel boring machine in welded tuff. Preliminary estimates of mechanical excavator performance in Yucca Mountain tuff are presented here. As phases of the research project are completed, well quantified estimates will be made of performance of mechanical excavators in the Yucca Mountain tuffs. 3 refs., 2 tabs.

  13. Mechanical excavator performance in Yucca Mountain tuffs

    SciTech Connect

    Ozdemir, L.; Hansen, F.D.

    1991-12-31

    A research effort of four phases is in progress at the Colorado School of Mines. The overall program will evaluate the cutability of welded tuff and other lithologies likely to be excavated at Yucca Mountain in the site characterization process. Several mechanical systems are considered with emphasis given to the tunnel boring machine. The research comprises laboratory testing, linear drag bit and disc cutter tests, and potentially large-scale lab. demonstrations to support potential use of a tunnel boring machine in welded tuff. Preliminary estimates of mechanical excavator performance in Yucca Mountain tuff are presented here. As phases of the research project are completed, well-quantified estimates will be made of performance of mechanical excavators in the Yucca Mountain tuffs.

  14. Origin and mode of emplacement of lithic-rich breccias at Aso Volcano, Japan: Geological, paleomagnetic, and petrological reconstruction

    NASA Astrophysics Data System (ADS)

    Furukawa, Kuniyuki; Uno, Koji; Shinmura, Taro; Miyoshi, Masaya; Kanamaru, Tatsuo; Inokuchi, Hiroo

    2014-04-01

    Takajosan breccia rocks are distributed around the southwestern caldera rim of the Aso Volcano in Japan. They are characterized by coarse lithic breccias with a pumiceous matrix. The proximal coarse lithic breccias are divided into the lower massive unit and the upper stratified unit. The lower massive lithic breccias tend to transform laterally into tuff breccias and pumiceous lapilli tuffs. Paleomagnetic results showed that all of the deposits were deposited at high temperatures of 175-560 °C. This was also supported by geological characteristics such as spatter clasts, clasts with a bread-crust texture, and weakly welded parts. These features clearly show that the deposits originated from pyroclastic density currents (PDCs). The dense lithic-rich lithofacies, low vesicularity of pumice, lack of plinian fall deposits, and radial distribution indicate that the deposits were derived from boil-over PDCs rather than plinian column-collapse PDCs. The SiO2 contents of the matrix glasses of the proximal lower massive breccia showed a progressive decrease from the bottom toward the upper part. We interpret that this chemical variation corresponds to chemical zonation of the magma chamber. This indicates that the massive deposits aggraded progressively from the base upwards (progressive aggradation), rather than through en masse freezing. The vertical lithofacies changes of the proximal breccias from the lower massive to the upper stratified units indicate that a sustained current in a quasi-steady state switched to an unsteady current with the progression of the volcanic activity.

  15. Experimental testing of the transport-durability of shale lithics and its implications for interpreting the rock record

    NASA Astrophysics Data System (ADS)

    Schieber, Juergen

    2016-01-01

    Detailed petrographic studies of shales show that they consist of a wide range of components, including a wide spectrum of composite particles that were contributed to the precursor muds in the form of high-water-content suspended floccules, bedload floccules, rip-up intraclasts, pedogenic aggregates, and fully lithified shale clasts. Experimental studies show that shale clasts of sand to silt size (shale lithics) can survive hundreds to thousands of kilometers of bedload transport. Observations of modern river and shelf muds reveal the common presence of shale lithics in these sediments, and suggest that a significant portion of ancient shale formations could potentially consist of reworked shale lithics and not, as commonly assumed, of primary composite particles such as clay floccules and organo-minerallic aggregates. Identification of shale lithics in the rock record presents challenges, but careful petrographic examination (using SEM and ion-milled samples) and case studies will help to develop robust criteria for recognition. The presented observations have manifold implications for the interpretation of many aspects of shales: mud transport and accumulation, sediment compaction and basin-fill modeling, and geochemical proxies. They emphasize the essential need for petrographic examination of shale samples before more advanced analyses are undertaken.

  16. Formation of composite pyroclasts by welding inside a lithic-rich mafic eruption column (Los Marteles Caldera, Canary Islands)

    NASA Astrophysics Data System (ADS)

    Sarrionandia, F.; Carracedo Sánchez, M.; Arostegui, J.; Gil Ibarguchi, J. I.

    2015-12-01

    The tuff ring of the Los Marteles phreatomagmatic maar (Gran Canaria, Canary Islands) includes a particular unit that comprises abundant composite spheroidal clasts. However, these clasts differ from cored clasts elsewhere that consist of erupted lithic pyroclasts with an adhering rim of coherent chilled magma. The composite clasts here studied range from lapilli to bombs, and are cored or concentrically banded. Among the welded components, several types of primary clasts are discerned that include: (i) juvenile clasts, resultant of the magma inertial fragmentation, and (ii) cognate or accessory lithic clasts. Juvenile clasts include glass spheres (nano- and microachneliths) and crystals. Lithic clasts include lava fragments, scoriae and olivine xenocrysts. Primary clasts are interpreted to have been produced by the explosion of a partially crystallized mafic (SiO2 ≈ 50-55%) magma that erupted into a maar, filled-up with scoriae plus lava fragments. The explosion would have originated as a dense and turbulent gas thrust into which the repeated collisions of melt droplets with solid clasts generated droplet-coated crystals, lithic clasts and single glass spheres. We interpret the cored and concentrically banded pyroclasts to be made of coalesced and/or agglutinated particles coated with a melt rim to the rest of the components. These composite clasts developed spheroidal shapes during transport within a violent Strombolian eruption column due to spin effect and, finally, landed in solid state.

  17. Pajarito Plateau archaeological surveys and excavations. II

    SciTech Connect

    Steen, C R

    1982-04-01

    Los Alamos National Laboratory continues its archaeological program of data gathering and salvage excavations. Sites recently added to the archaeological survey are described, as well as the results of five excavations. Among the more interesting and important discoveries are (1) the apparently well-established local use of anhydrous lime, and (2) a late pre-Columbian use of earlier house sites and middens for garden plots. Evidence indicated that the local puebloan population was the result of an expansion of upper Rio Grande peoples, not an influx of migrants.

  18. REDUCED ENERGY CONSUMPTION THROUGH PROJECTILE BASED EXCAVATION

    SciTech Connect

    Mark Machina

    2002-01-09

    The Projectile Based Excavation (ProjEX) program has as its goal, the reduction of energy required for production mining and secondary breakage through the use of a projectile based excavation system. It depends on the development of a low cost family of projectiles that will penetrate and break up different types of ore/rock and a low cost electric launch system. The electric launch system will eliminate the need for high cost propellant considered for similar concepts in the past. This document reports on the progress made in the program during the past quarter. It reports on projectile development experiments and the development of the electric launch system design.

  19. Efficacy of Carisolv-assisted caries excavation.

    PubMed

    Cederlund, A; Lindskog, S; Blomlöf, J

    1999-10-01

    As a possible alternative to conventional techniques for excavating caries chemomechanical methods have been developed. Caridex has so far been the dominating product. However, a new system, Carisolv, was recently introduced. The purpose of the present study was to evaluate the caries-dissolving efficacy of Carisolv in vitro. After excavation with Carisolv all dentin surfaces were caries free. However, 6 of the 10 cavities showed residual caries in the dentinoenamel junction. The dentin and enamel surfaces were covered by smear and debris. Since there may be a risk of leaving caries in the dentinoenamel junction proper case selection appears to be of importance to ensure a successful result. PMID:10709512

  20. REDUCED ENERGY CONSUMPTION THROUGH PROJECTILE BASED EXCAVATION

    SciTech Connect

    Mark Machina

    2002-10-12

    The Projectile Based Excavation (ProjEX) program has as its goal, the reduction of energy required for production mining and secondary breakage through the use of a projectile based excavation system. It depends on the development of a low cost family of projectiles that will penetrate and break up different types of ore/rock and a low cost electric launch system. The electric launch system will eliminate the need for high cost propellant investigated for similar concepts in the past. This document reports on the progress made in the program during the past quarter. It reports on projectile development and the development of the electric launch system design.

  1. 100 area excavation treatability test plan

    SciTech Connect

    Not Available

    1993-05-01

    This test plan documents the requirements for a treatability study on field radionuclide analysis and dust control techniques. These systems will be used during remedial actions involving excavation. The data from this treatability study will be used to support the feasibility study (FS) process. Development and screening of remedial alternatives for the 100 Area, using existing data, have been completed and are documented in the 100 Area Feasibility Study, Phases 1 and 2 (DOE-RL 1992a). Based on the results of the FS, the Treatability Study Program Plan (DOE-RL 1992b) identifies and prioritizes treatability studies for the 100 Area. The data from the treatability study program support future focused FS, interim remedial measures (IRM) selection, operable unit final remedy selection, remedial design, and remedial actions. Excavation is one of the high-priority, near-term, treatability study needs identified in the program plan (DOE-RL 1992b). Excavation of contaminated soils and buried solid wastes is included in several of the alternatives identified in the 100 Area FS. Although a common activity, excavation has only been used occasionally at the Hanford Site for waste removal applications.

  2. Compact Hydraulic Excavator and Support Unit

    NASA Technical Reports Server (NTRS)

    Lewis, E. V.

    1985-01-01

    Continuous-coal-mining machine maneuverable. Hydraulic coal excavator combined with chock, or roof-support structure, in self-contained unit that moves itself forward as it removes coal from seam. Unlike previous such units, new machine compact enough to be easily maneuverable; even makes small-radius right-angle turns.

  3. Excavated Documents Dealing with Chinese Astronomy

    NASA Astrophysics Data System (ADS)

    Guan, Yuzhen

    The materials ancient Chinese scholars used to write on changed from bamboo strips, wooden tablets, and silk in early China to paper in the later dynasties. This chapter will focus on excavated documents dealing with ancient Chinese astronomy and explore some of the ways that scholars have made use of these archaeological resources.

  4. Excavations in Hanford ponds, cribs, or ditches

    SciTech Connect

    Ryan, G.W., Westinghouse Hanford

    1996-07-30

    This document supports the development and presentation of the following accident scenario in the TWRS Final Safety Analysis Report: Unplanned Excavation/Drilling in Pond/Ditch/Crib. The calculations needed to quantify the risk associated with this accident scenario are included within.

  5. Clast assemblages of possible deep-seated /77517/ and immiscible-melt /77538/ origins in Apollo 17 breccias

    NASA Technical Reports Server (NTRS)

    Warner, R. D.; Taylor, G. J.; Mansker, W. L.; Keil, K.

    1978-01-01

    Breccia samples 77517 and 77538 are composed of abundant mineral and lithic clasts set in porous, poorly sintered matrices. Clast assemblages in the two rocks are of contrasting composition and origin. Breccia 77517 has Mg-rich olivine and pyroxene and calcic plagioclase clasts, indicating limited, almost exclusively ANT-suite parentage. A significant feature is the presence of an assemblage (aluminous enstatite, forsterite, anorthite, aluminous spinel) corresponding to spinel cataclasite, a rock type of deep-seated (about 60 km) crustal origin. Breccia 77538 contains Fe-rich pyroxene and rather sodic plagioclase clasts, indicative of predominantly KREEP and/or mare derivation. An important feature is the occurrence of high-K and high-Fe lithic clasts whose compositions resemble those of immiscible-melts produced during late-stage magmatic crystallization, and which probably originated via silicate liquid immiscibility in a KREEP or mare basalt magma. Both rocks contain numerous fine-grained breccia clasts which represent material that has been modified by impact processes at or very near the moon's surface.

  6. 4. VIEW SHOWING EXCAVATION IN ARIZONA CANAL, 8 MILES NORTHEAST ...

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

    4. VIEW SHOWING EXCAVATION IN ARIZONA CANAL, 8 MILES NORTHEAST OF PHOENIX. NOTE MEN DRILLING AND EXCAVATING IN OPERATION; CAMELBACK MOUNTAIN IN THE DISTANCE Photographer: Walter J. Lubken. No date - Arizona Canal, North of Salt River, Phoenix, Maricopa County, AZ

  7. 29 CFR 1926.651 - Specific excavation requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Specific excavation requirements. 1926.651 Section 1926.651 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Excavations § 1926.651 Specific excavation requirements. (a)...

  8. REDUCED ENERGY CONSUMPTION THROUGH PROJECTILE BASED EXCAVATION

    SciTech Connect

    Mark Machina

    2003-06-06

    The Projectile Based Excavation (ProjEX) program has as its goal, the reduction of energy required for production mining and secondary breakage through the use of a projectile based excavation system. It depends on the development of a low cost family of projectiles that will penetrate and break up different types of ore/rock and a low cost electric launch system. The electric launch system will eliminate the need for high cost propellant considered for similar concepts in the past. This document reports on the program findings through the first two phases. It presents projectile design and experiment data and the preliminary design for electric launch system. Advanced Power Technologies, Inc., now BAE SYSTEMS Advanced Technologies, Inc., was forced to withdraw from the program with the loss of one of our principal mining partners, however, the experiments conducted suggest that the approach is feasible and can be made cost effective.

  9. 118-B-1 excavation treatability test plan

    SciTech Connect

    Not Available

    1994-07-01

    The Hanford 118-B-1 Burial Ground Treatability Study has been required by milestone change request {number_sign}M-15-93-04, dated September 30, 1993. The change request requires that a treatability test be conducted at the 100-B Area to obtain additional engineering information for remedial design of burial grounds receiving waste from 100 Area removal actions. This treatability study has two purposes: (1) to support development of the Proposed Plan (PP) and Record of Decision (ROD), which will identify the approach to be used for burial ground remediation, and (2) to provide specific engineering information for receiving waste generated from the 100 Area removal actions. Data generated from this test also will provide critical performance and cost information necessary for remedy evaluation in the detailed analysis of alternatives during preparation of the focused feasibility study (FFS). This treatability testing supports the following 100 Area alternatives: (1) excavation and disposal, and (2) excavation, sorting, (treatment), and disposal.

  10. CLASSIFICATION OF THE MGR SUBSURFACE EXCAVATION SYSTEM

    SciTech Connect

    R. Garrett

    1999-08-31

    The purpose of this analysis is to document the Quality Assurance (QA) classification of the Monitored Geologic Repository (MGR) subsurface excavation system structures, systems and components (SSCs) performed by the MGR Safety Assurance Department. This analysis also provides the basis for revision of YMP/90-55Q, Q-List (YMP 1998). The Q-List identifies those MGR SSCs subject to the requirements of DOE/RW-0333P, ''Quality Assurance Requirements and Description'' (QARD) (DOE 1998).

  11. Lunar Regolith Excavation Student Competition Design

    NASA Technical Reports Server (NTRS)

    Nething, Julia

    2009-01-01

    The Surface Systems team is working to learn about lunar regolith and how we can use it as a source of air, water, and fuel for spacecrafts. However, excavation of this valuable regolith is difficult because the robot has to conform to many specifications (mass limit, efficiency level, etc.). NASA has therefore decided to include college students and companies in the search to create the best robot by making it into a competition.

  12. Telerobotic excavation system for unexploded ordnance retrieval

    SciTech Connect

    Burks, B.L.; Killough, S.M.; Thompson, D.H.; Rossi, R.A.

    1994-12-31

    The small emplacement excavator (SEE) is a ruggedized military vehicle with backhoe and front loader used by the US Army for unexploded ordnance (UXO) retrieval and general utility excavation activities. In order to evaluate the feasibility of removing personnel from the vehicle during high-risk excavation tasks a development and demonstration project was initiated to evaluate performance capabilities of the SEE under telerobotic control. A technology demonstration of the TSEE was conducted at McKinley Range, Redstone Arsenal, Huntsville, Alabama on 13--17 September, 1993. The primary objective of the demonstration was to evaluate and demonstrate the feasibility of remote UXO retrieval. During the demonstration, explosive ordnance disposal specialists were instructed on telerobotic operation of the TSEE, and then were asked to complete a simulated UXO retrieval task. Participants then submitted an evaluation of the system including human factors performance data. This presentation will describe the TSEE, retrieval demonstration, and summarize results of the performance evaluations. Some examples of the results are given below. Seventy percent of the demonstration participants found the tasks were as easy or easier to accomplish utilizing the remote system than with an unmodified system. Similarly, eighty percent of the participants found the TSEE hand controller was as easy or easier to use than the normal manual controls.

  13. National Advanced Drilling and Excavation Technologies Program

    SciTech Connect

    1993-06-15

    The second meeting of Federal agency representatives interested in the National Advanced Drilling and Excavation Technologies (NADET) Program took place on June 15, 1993. The Geothermal Division of the U.S. Department of Energy (DOE) hosted the meeting at the Washington, D.C., offices of DOE. Representatives from the National Science Foundation, U.S. Geological Survey, U.S. Bureau of Mines, National Institute of Standards and Technology, National Aeronautics and Space Administration, Environmental Protection Agency, and various offices within the Department of Energy attended. For a complete list of attendees see Attachment A. The purpose of the meeting was: (1) to cover the status of efforts to gain formal approval for NADET, (2) to brief participants on events since the last meeting, especially two recent workshops that explored research needs in drilling and excavation, (3) to review some recent technological advances, and (4) to solicit statements of the importance of improving drilling and excavation technologies to the missions of the various agencies. The meeting agenda is included as Attachment B.

  14. Discrete Element Modeling for Mobility and Excavation

    NASA Astrophysics Data System (ADS)

    Knuth, M. A.; Hopkins, M. A.

    2011-12-01

    The planning and completion of mobility and excavation efforts on the moon requires a thorough understanding of the planetary regolith. In this work, a discrete element method (DEM) model is created to replicate those activities in the laboratory and for planning mission activities in the future. The crux of this work is developing a particle bed that best replicates the regolith tool/wheel interaction seen in the laboratory. To do this, a DEM geotechnical triaxial strength cell was created allowing for comparison of laboratory JSC-1a triaxial tests to DEM simulated soils. This model relies on a triangular lattice membrane covered triaxial cell for determining the macroscopic properties of the modeled granular material as well as a fast and efficient contact detection algorithm for a variety of grain shapes. Multiple grain shapes with increasing complexity (ellipsoid, poly-ellipsoid and polyhedra) have been developed and tested. This comparison gives us a basis to begin scaling DEM grain size and shape to practical values for mobility and excavation modeling. Next steps include development of a DEM scoop for percussive excavation testing as well as continued analysis of rover wheel interactions using a wide assortment of grain shape and size distributions.

  15. Excavation of Regolith by Impinging Jets of Gas

    NASA Technical Reports Server (NTRS)

    Metzger, Philip T.; Immer, Christopher D.; Vu, Bruce T.; Donahue, Carly M.

    2006-01-01

    There are many situations in nature and technology where particulate matter is excavated by a fluid jet. Such a process is often used to excavate soil or to dig wells. Air jets are often used to transport particulate matter such as powders in various industrial processes. Similar situations occur in nature, as when waterfalls scour holes in sand. In other cases, the excavation is unwanted such as when a rocket lands on the sandy or dusty surface of a planet or moon. Recent research into regolith excavation by gas jets has obtained new insights into the physical processes of that excavation, and these may lead to new advances in technology for more efficient fluid-jet excavation processes and for better control of the unwanted excavation effects of landing rockets. This talk will explain the new insights and point to future work supporting lunar exploration.

  16. Field and paleomagnetic characterization of lithic and scoriaceous breccias at Pleistocene Broken Top volcano, Oregon Cascades

    NASA Astrophysics Data System (ADS)

    Grubensky, Michael J.; Smith, Gary A.; Geissman, John W.

    1998-07-01

    Cirque-wall exposures of cone-forming deposits of Pleistocene Broken Top volcano, Oregon Cascade Range, reveal that the volcano is composed of unconformity-bounded constructional units of coherent lava (lava-flow cores) and breccia. Coarse-grained autoclastic breccias are found above and below lava-flow cores and may extend downslope from coherent lava outcrops where they may or may not be associated with thin lava stringers. Mantle-bedded scoria-fall breccias are recognized by generally good sorting, mantle bedding, and presence of aerodynamically shaped bombs. These breccias vary considerably in thermal oxidation coloration (black, red, orange, purple). Many breccia layers are unsorted mixtures of scoria and lithic (nonvesicular) fragments that grade laterally to unambiguous autoclastic breccia or lava-flow cores. These layers are interpreted as hybrid pyroclastic-autoclastic deposits produced by incorporation of falling or fallen tephra into advancing lava-flow fronts. This latter breccia type is common at Broken Top and offers particular challenges for clast or deposit classification. Progressive thermal demagnetization results for selected examples of different breccia types show that most scoria-fall and autoclastic breccias are emplaced at elevated temperatures (averaging 100-300°C). Clasts within single deposits record different emplacement temperatures ranging, in some cases, from 100 to over 580°C indicating a lack of thermal equilibration within deposits. Magnetization directions for single breccia deposits are more dispersed than data typically reported for lava flows. Settling and rotation of clasts after cooling or incorporation of colder clasts that are not significantly reheated probably accounts for the relatively high dispersion and suggests that paleomagnetic studies demanding low within-site dispersion (e.g., for determining paleomagnetic poles or evaluating tectonic rotation) should avoid volcanic breccias.

  17. Selection of operating machinery parameters for a bucket excavator

    SciTech Connect

    Fabrichnyi, Y.F.; Baboshin, K.V.; Etinger, I.M.; Mekk, V.A.

    1985-05-01

    The mining industry uses extensively single-bucket excavators of the straight shovel type, like the EKG-4.6, as the most effective way of loading previously loosened hard and abrasive excavated rocks. Therefore, an increase in their working efficiency, mainly as regards increasing productivity, reducing load on the operating machinery, and reducing wear of the operating machinery elements, is of particular importance. Analysis shows that the possibilities for this lie in the correct selection of movement trajectory parameters for the excavator bucket, which for existing excavators are inadequate for loading excavated rock. The authors study here the effect of trajectory parameters on excavator bucket filling, and on their basis they select parameters for the operating machinery.

  18. Nature and velocity of pyroclastic density currents inferred from models of entrainment of substrate lithic clasts

    NASA Astrophysics Data System (ADS)

    Roche, Olivier

    2015-05-01

    Deposits of pyroclastic density currents (PDCs) often contain accidental lithic clasts of typical size of 0.1-1 m captured from an underlying substrate by the parent flows at distances up to several tens of kilometers from the eruptive vent. In order to gain insights into the nature of PDCs, this study investigates the conditions required for entrainment of particles from a granular substrate by a gas-particle density current, with special emphasis to ignimbrite-forming currents whose dynamics are controversial. The two types of physics of emplacement of PDCs proposed in literature are considered. The first model deals with a hydraulically rough, dilute turbulent PDC of bulk density of ∼1-10 kg/m3 and considers that entrainment through both traction and saltation is controlled by a Shield criterion at high (>104) particle Reynolds number. The second model considers entrainment by a PDC consisting of a dense basal flow of bulk density of the order of 103 kg /m3 and with high interstitial gas pore pressure. This model involves uplift of substrate particles, caused by an upward pressure gradient at the flow-substrate interface, and then transport and deposition on the aggrading basal deposit of the flow as demonstrated by recent laboratory experiments. Results show that a dilute PDC can entrain blocks of maximum size of ∼10-15 cm (for a block density of 2000-3000 kg/m3) if maximum current velocities up to ∼100 m/s are taken into account. This, in turn, suggests that larger (heavier) blocks found in deposits were captured by PDCs if these had a dense basal flow. The dense flow model predicts that PDCs have the potential to entrain metric blocks, whose maximum size (up to ∼2-5 m) decreases with decreasing atmospheric pressure (i.e. increasing altitude). Application of the model considering published data on the characteristics of accidental blocks in several well-studied ignimbrites indicates that the velocity of the parent dense PDCs was up to ∼25-30 m/s.

  19. Excavation and rock breaking system on the moon

    NASA Astrophysics Data System (ADS)

    Shimizu, Katsunori; Yoshida, Tetsuji; Kai, Yoshiro; Mano, Hideyuki; Takagi, Kenji; Matsumoto, Shinji

    The construction of lunar bases underground, in order to escape cosmic rays and small meteorites, entails lunar regolith soil-excavation equipment capable of both rock fracture and the subsequent processing of the mineral detritus from excavation sites. Consideration is given to excavation systems' power supplies, heat removal, mechanical bearings, vehicular platform, conveyor belts, and tool accessories. An evaluation is made of the enabling technologies required for such devices' implementation.

  20. 40Ar/39Ar and cosmic ray exposure ages of plagioclase-rich lithic fragments from Apollo 17 regolith, 78461

    NASA Astrophysics Data System (ADS)

    Das, J. P.; Baldwin, S. L.; Delano, J. W.

    2016-01-01

    Argon isotopic data is used to assess the potential of low-mass samples collected by sample return missions on planetary objects (e.g., Moon, Mars, asteroids), to reveal planetary surface processes. We report the first 40Ar/39Ar ages and 38Ar cosmic ray exposure (CRE) ages, determined for eleven submillimeter-sized (ranging from 0.06 to 1.2 mg) plagioclase-rich lithic fragments from Apollo 17 regolith sample 78461 collected at the base of the Sculptured Hills. Total fusion analysis was used to outgas argon from the lithic fragments. Three different approaches were used to determine 40Ar/39Ar ages and illustrate the sensitivity of age determination to the choice of trapped (40Ar/36Ar)t. 40Ar/39Ar ages range from ~4.0 to 4.4 Ga with one exception (Plag#10). Surface CRE ages, based on 38Ar, range from ~1 to 24 Ma. The relatively young CRE ages suggest recent re-working of the upper few centimeters of the regolith. The CRE ages may result from the effect of downslope movement of materials to the base of the Sculptured Hills from higher elevations. The apparent 40Ar/39Ar age for Plag#10 is >5 Ga and yielded the oldest CRE age (i.e., ~24 Ma). We interpret this data to indicate the presence of parentless 40Ar in Plag#10, originating in the lunar atmosphere and implanted in lunar regolith by solar wind. Based on a chemical mixing model, plagioclase compositions, and 40Ar/39Ar ages, we conclude that lithic fragments originated from Mg-suite of highland rocks, and none were derived from the mare region.

  1. Focal Choroidal Excavation in Best Vitelliform Macular Dystrophy: Case Report.

    PubMed

    Esfahani, Mohammad Riazi; Esfahani, Hamid Riazi; Mahmoudi, Alireza; Johari, Mohammad Karim; Hemati, Karim

    2015-05-01

    Focal choroidal excavation (FCE) was first reported as a choroidal posteriorly excavated zone without any scleral change. Choroidal excavation also divided into conforming and nonconforming type. Numerous reports demonstrated association between FCE and other disease such as choroidal neovascularization and central serous choroidoretinopathy. Here, we report a rare case of FCE in a patient with Best disease. The patient was diagnosed by spectoral domain optical coherence tomography (SD-OCT). To the best of our knowledge, our patient is the second report of choroidal excavation in Best vitelliform macular dystrophy. PMID:26155505

  2. Focal Choroidal Excavation in Best Vitelliform Macular Dystrophy: Case Report

    PubMed Central

    Esfahani, Mohammad Riazi; Esfahani, Hamid Riazi; Mahmoudi, Alireza; Johari, Mohammad Karim

    2015-01-01

    Focal choroidal excavation (FCE) was first reported as a choroidal posteriorly excavated zone without any scleral change. Choroidal excavation also divided into conforming and nonconforming type. Numerous reports demonstrated association between FCE and other disease such as choroidal neovascularization and central serous choroidoretinopathy. Here, we report a rare case of FCE in a patient with Best disease. The patient was diagnosed by spectoral domain optical coherence tomography (SD-OCT). To the best of our knowledge, our patient is the second report of choroidal excavation in Best vitelliform macular dystrophy. PMID:26155505

  3. Voluminous juvenile lithic fragments in the pumice-fall deposit of the 1108 eruption of Asama volcano: Evidence of repeated compaction and fragmentation in the shallow conduit

    NASA Astrophysics Data System (ADS)

    Nakamura, M.; Kichise, T.; Yasui, M.; Nagahashi, Y.; Yoshida, T.

    2010-12-01

    The pumice-fall deposit of the 1108 eruption of Asama volcano, central Japan, contains a large amount of lithic fragments (up to 40 wt%) that are angular, dense, and juvenile. The deposit consists of eight sublayers, comprising three thick layers of pumice (1.0-1.4 g/cm3) containing 5-40 wt% lithic fragments (1.4-2.7 g/cm3) interbedded with two thin pumiceous layers, two thin layers of lapilli-sized lithic fragments, and a volcanic ash layer. The average volume of each sublayer is ~0.01 km3. The large volume of lithic fragments and their occurrence throughout the deposit show that their source lava plugs formed and fragmented continuously during the eruption. The lithic fragments are not coated with vesicular matrix, indicating that the fragments were entrained into mist flows of the eruption columns; i.e., after the magma fragmentation that produced the pumice clasts. The plagioclase microlites in the lithic fragments have a range (55-75 mol%) and frequency distribution of anorthite content similar to those in the pumices, indicating that the lithic fragments and pumices have a similar history of decompression from the magma reservoir to the shallow conduit. The groundmass of the pumices has a porosity approximately ranging from 40% to 60% and positive correlation with groundmass crystallinity; this is consistent with an interpretation that magma with higher porosity is more decompressed and thus crystallized in the shallower conduit. The highest crystallinity of the pumice, of which the groundmass porosity is ca. 60%, coincides with the lowest crystallinity of the lithic fragments. In addition, the pore connectivity of the pumice increases (with increasing porosity) steeply at a groundmass porosity of ca. 60%. These petrographical observations strongly suggest that the lithic fragments are the collapsed and compacted products of magma foam (at a groundmass porosity of ca. 60%) just before it fragmented to become pumices. The lithic fragments often have mosaic

  4. Modelling bucket excavation by finite element

    NASA Astrophysics Data System (ADS)

    Pecingina, O. M.

    2015-11-01

    Changes in geological components of the layers from lignite pits have an impact on the sustainability of the cup path elements and under the action of excavation force appear efforts leading to deformation of the entire assembly. Application of finite element method in the optimization of components leads to economic growth, to increase the reliability and durability of the studied machine parts thus the machine. It is obvious usefulness of knowledge the state of mechanical tensions that the designed piece or the assembly not to break under the action of tensions that must cope during operation. In the course of excavation work on all bucket cutting force components, the first coming into contact with the material being excavated cutting edge. Therefore in the study with finite element analysis is retained only cutting edge. To study the field of stress and strain on the cutting edge will be created geometric patterns for each type of cup this will be subject to static analysis. The geometric design retains the cutting edge shape and on this on the tooth cassette location will apply an areal force on the abutment tooth. The cutting edge real pattern is subjected to finite element study for the worst case of rock cutting by symmetrical and asymmetrical cups whose profile is different. The purpose of this paper is to determine the displacement and tensions field for both profiles considering the maximum force applied on the cutting edge and the depth of the cutting is equal with the width of the cutting edge of the tooth. It will consider the worst case when on the structure will act both the tangential force and radial force on the bucket profile. For determination of stress and strain field on the form design of cutting edge profile will apply maximum force assuming uniform distribution and on the edge surface force will apply a radial force. After geometric patterns discretization on the cutting knives and determining stress field, can be seen that at the

  5. 118-B-1 excavation treatability test procedures

    SciTech Connect

    Frain, J.M.

    1994-08-01

    This treatability study has two purposes: to support development of the approach to be used for burial ground remediation, and to provide specific engineering information for the design of burial grounds receiving waste generated from the 100 Area removal actions. Data generated from this test will also provide performance and cost information necessary for detailed analysis of alternatives for burial ground remediation. Further details on the test requirements, milestones and data quality objectives are described in detail in the 118-B-1 Excavation Treatability Test Plan (DOE/RL-94-43). These working procedures are intended for use by field personnel to implement the requirements of the milestone. A copy of the detailed Test Plan will be kept on file at the on-site field support trailer, and will be available for review by field personnel.

  6. REDUCED ENERGY CONSUMPTION THROUGH PROJECTILE BASED EXCAVATION

    SciTech Connect

    Unknown

    2001-10-12

    The hypothesis to be tested is that the addition of steel or other synthetic fiber and/or high strength, low cost aggregate to strong grouts or concrete will result in a projectile of sufficient strength to produce cracking and spall enough to make its use cost effective for mining. Based on experiments conducted to date, no conclusions can yet be reached. Results of the experiments conducted suggest that reinforcement of a concrete projectile can yield performance that portends cost effective projectile based excavation. It is recognized that the projectile is but one component of the matrix. The electric launch system to be developed in the next phase of the program is the other factor that weighs heavily in the cost effectiveness equation. At this point, however, emerging low cost options for the projectile are very promising.

  7. Reconstructing Grazer Assemblages for Protected Area Restoration

    PubMed Central

    Venter, Jan A.; Prins, Herbert H. T.; Balfour, David A.; Slotow, Rob

    2014-01-01

    Protected area management agencies often struggle to reliably reconstruct grazer assemblages due to a lack of historical distribution data for their regions. Wrong predictions of grazing assemblages could potentially affect biodiversity negatively. The objective of the study was to determine how well grazing herbivores have become established since introduction to the Mkambati Nature Reserve, South Africa, how this was influenced by facilitation and competition, and how indigenous grazer assemblages can best be predicted for effective ecological restoration. Population trends of several grazing species were investigated in in order to determine how well they have become established since introduction. Five different conceivable grazing assemblages reflecting a range of approaches that are commonly encountered during conservation planning and management decision making were assessed. Species packing was used to predict whether facilitation, competition or co-existence were more likely to occur, and the species packing of the different assemblages were assessed using ANCOVA. Reconstructing a species assemblage using biogeographic and biological information provides the opportunity for a grazer assemblage that allows for facilitatory effects, which in turn leads to an ecosystem that is able to maintain its grazer assemblage structure. The strength of this approach lies in the ability to overcome the problem of depauperate grazer assemblages, resulting from a lack of historical data, by using biogeographical and biological processes, to assist in more effectively reconstructing grazer assemblages. Adaptive management of grazer assemblage restoration through reintroduction, using this approach would further mitigate management risks. PMID:24603663

  8. 29 CFR 1926.651 - Specific excavation requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... subparts D and E of this part (29 CFR 1926.50-1926.107) to prevent exposure to harmful levels of.... (f) Warning system for mobile equipment. When mobile equipment is operated adjacent to an excavation... have a clear and direct view of the edge of the excavation, a warning system shall be utilized such...

  9. Pre-excavation studies of prehistoric cave sites by magnetic prospecting

    NASA Astrophysics Data System (ADS)

    Itkis., Sonia; Matskevich, Zinovii; Meshveliani, Tengiz

    2014-05-01

    lithic material to Mesolithic and Early Neolithic periods. The upper layer is ca 50 cm thick, consists of fine grey silt with few pebbles and includes numerous bones and lithic implements. In this layer two circular dense concentrations of charcoal, possibly fireplaces were discovered. Conclusions 1. The results of magnetic survey obtained in prehistoric cave sites in Israel and Georgia show the high efficiency of the magnetic method for revealing and detailed characterization of caves. 2. The presence of organic materials, e.g. bones, charcoals and ceramics in caves enhances magnetic contrast between non-magnetic bedrock and the cave's fill, increasing the potential of the magnetic method. 3. Revealing enhanced magnetization of soil within studied caves allowed us to develop an approach to reliable interpretation of magnetic data in studied areas References Bar-Oz, G., Belfer-Cohen, A, Meshvelliani, T., Jakeli, N., Matskevich, Z. and Bar-Yosef, O. 2009. Bear in mind: bear hunting in the Mesolithic of the Southern Caucasus, the case of Kotias Klde rockshelter, western Georgia. Archaeology, Ethnology and Anthropology of Eurasia 37 (1): 15-24. Dalan, R. A. and Banerjee, S. K. 1998. Solving archaeological problems using techniques of soil magnetism. Geoarchaeology: An International Journal, Vol. 13, No.1, pp.1-36. Fassbinder, J.W. E. , Stanijek, H. and Vali, H. 1990. Occurence of magnetic bacteria in soil. Nature 343, 161-163. Itkis, S. 2003. Magnetic Susceptibility Measurements of Soil: A Diagnostic Tool for Location of Human Activity Areas (Ch. 14) In: Khalaily, H. and Marder, O. (editors). The Neolithic Site of Abu Ghosh: The 1995 Excavations. IAA Reports, No.19. Jerusalem. p. 129-131. Itkis, S. 2011..Magnetic survey at Ramat Bet Shemesh. In: Dagan Y. (editor). The Ramat Bet Shemesh Regional Project: Landscapes of Settlement from the Paleolithic to the Ottoman Period, IAA Reports, No. 47, Israel Antiquites Authority, Jerusalem 2011, pp. 95-104. Itkis S.E and Eppelbaum L

  10. Rational design and synthesis of excavated trioctahedral Au nanocrystals

    NASA Astrophysics Data System (ADS)

    Chen, Qiaoli; Jia, Yanyan; Shen, Wei; Xie, Shuifen; Yang, Yanan; Cao, Zhenming; Xie, Zhaoxiong; Zheng, Lansun

    2015-06-01

    Excavated polyhedral nanostructures, possessing the features of high surface area and well-defined surface structure with a specific crystal facet and avoidance of aggregation, could be one of the best choices for the purpose of reducing consumption and improving performance of noble metals in many application fields. However, the formation of the excavated structures is thermodynamically unfavourable and its rational synthesis is far beyond our knowledge. In this work, taking overgrowth of Pd onto trioctahedral Au nanocrystals as a model, we present a deep insight study for synthesizing an excavated structure relying on the protection role of surfactants under suitable crystal growth kinetics. Based on the abovementioned understanding, we designed a simple and effective strategy to synthesize Au nanocrystals with excavated trioctahedral structure in one step. Due to the novel feature of the excavated structure and exposed high energy {110} facets, excavated trioctahedral Au NCs exhibited optical extinction at the near-infrared region and showed high catalytic activity towards the reduction of p-nitrophenol. Moreover, the synthetic strategy can be extended to the synthesis of excavated Au-Pd alloys.Excavated polyhedral nanostructures, possessing the features of high surface area and well-defined surface structure with a specific crystal facet and avoidance of aggregation, could be one of the best choices for the purpose of reducing consumption and improving performance of noble metals in many application fields. However, the formation of the excavated structures is thermodynamically unfavourable and its rational synthesis is far beyond our knowledge. In this work, taking overgrowth of Pd onto trioctahedral Au nanocrystals as a model, we present a deep insight study for synthesizing an excavated structure relying on the protection role of surfactants under suitable crystal growth kinetics. Based on the abovementioned understanding, we designed a simple and effective

  11. Reducing extra-terrestrial excavation forces with percussion

    NASA Astrophysics Data System (ADS)

    Mueller, R.; Smith, J. D.; Lippitt, T.; Schuler, J.; Nick, A.

    High launch costs and mission requirements drive the need for low mass excavators with mobility platforms, which in turn have little traction and excavation reaction capacity in low gravity environments. This presents the need for precursor and long term future missions with low mass robotic mining technology to perform In-Situ Resource Utilization (ISRU) tasks. This paper discusses a series of experiments that investigate the effectiveness of a percussive digging device to reduce excavation loads and thereby the mass of the excavator itself. A percussive mechanism and 30" wide pivoting bucket were attached to a test stand simulating a basic backhoe with a percussion direction tangent to the direction of movement. Impact energies from 13.6J to 30.5J and frequencies from 0 to 700 beats per minute (BPM) were investigated. A reduction in excavation force of as much as 50% was achieved in this experimental investigation.

  12. Reducing Extra-Terrestrial Excavation Forces with Percussion

    NASA Technical Reports Server (NTRS)

    Mueller, Robert; Schuler, Jason M.; Smith, Jonathan Drew; Nick, Andrew J.; Lippitt, Thomas

    2012-01-01

    High launch costs and mission requirements drive the need for low mass excavators with mobility platforms, which in turn have little traction and excavation reaction capacity in low gravity environments. This presents the need for precursor and long term future missions with low mass robotic mining technology to perform In-Situ Resource Utilization (ISRU) tasks. This paper discusses a series of experiments that investigate the effectiveness of a percussive digging device to reduce excavation loads and thereby the mass of the excavator itself. A percussive mechanism and 30" wide pivoting bucket were attached at the end of the arm simulating a basic backhoe with a percussion direction tangent to the direction of movement. Impact energies from 13.6J to 30.5J and frequencies from 0 BPM to 700 BPM were investigated. A reduction in excavation force of as much as 50% was achieved in this experimental investigation.

  13. Development of Field Excavator with Embedded Force Measurement

    NASA Technical Reports Server (NTRS)

    Johnson, K.; Creager, C.; Izadnegahdar, A.; Bauman, S.; Gallo, C.; Abel, P.

    2012-01-01

    A semi-intelligent excavation mechanism was developed for use with the NASA-built Centaur 2 rover prototype. The excavator features a continuously rotatable large bucket supported between two parallel arms, both of which share a single pivot axis near the excavator base attached to the rover. The excavator is designed to simulate the collection of regolith, such as on the Moon, and to dump the collected soil into a hopper up to one meter tall for processing to extract oxygen. Because the vehicle can be autonomous and the terrain is generally unknown, there is risk of damaging equipment or using excessive power when attempting to extract soil from dense or rocky terrain. To minimize these risks, it is critical for the rover to sense the digging forces and adjust accordingly. It is also important to understand the digging capabilities and limitations of the excavator. This paper discusses the implementation of multiple strain gages as an embedded force measurement system in the excavator's arms. These strain gages can accurately measure and resolve multi-axial forces on the excavator. In order to validate these sensors and characterize the load capabilities, a series of controlled excavation tests were performed at Glenn Research Center with the excavator at various depths and cut angles while supported by a six axis load cell. The results of these tests are both compared to a force estimation model and used for calibration of the embedded strain gages. In addition, excavation forces generated using two different types of bucket edge (straight vs. with teeth) were compared.

  14. Trench Excavated By Viking 1 Surface Sampler

    NASA Technical Reports Server (NTRS)

    1976-01-01

    This image, received today, shows the trench excavated by Viking 1 surface sampler. The trench was dug by extending the surface sampler collection head in a direction from lower right toward the upper left and then withdrawing the surface sampler collector head. Lumpy piles of material at end of trench at lower right was pulled by plowing from trench by the backhoe which will be used to dig trenches later in the mission. Area around trench has ripple marks produced by Martian wind. The trench which was dug early on Sol 8, is about 3 inches wide, 2 inches deep and 6 inches long. Steep dark crater walls show the grains of the Martian surface material stick together (have adhesion). The doming of the surface at far end of the trench show the granular material is dense. The Martian surface material behaves somewhat like moist sand on Earth. Evidence from the trench indicate a sample was collected and delivered to the experiments after repeated tries. The biology experiment level full indicator indicates a sample was received for analysis. The X-Ray fluorescence experiment has no indication to show it received a sample. The GCMS experiment level full indicator suggests no sample was received but this matter is being investigated.

  15. COLLISIONAL EXCAVATION OF ASTEROID (596) SCHEILA

    SciTech Connect

    Bodewits, D.; Kelley, M. S.; Li, J.-Y.; Besse, S.; A'Hearn, M. F.; Landsman, W. B. E-mail: msk@astro.umd.edu E-mail: sbesse@astro.umd.edu E-mail: Wayne.B.Landsman@nasa.gov

    2011-05-20

    We observed asteroid (596) Scheila and its ejecta cloud using the Swift UV-optical telescope. We obtained photometry of the nucleus and the ejecta, and for the first time measured the asteroid's reflection spectrum between 290 and 500 nm. Our measurements indicate significant reddening at UV wavelengths (13% per 10{sup 3} A) and a possible broad, unidentified absorption feature around 380 nm. Our measurements indicate that the outburst has not permanently increased the asteroid's brightness. We did not detect any of the gases that are typically associated with either hypervolatile activity thought responsible for cometary outbursts (CO{sup +}, CO{sub 2} {sup +}), or for any volatiles excavated with the dust (OH, NH, CN, C{sub 2}, C{sub 3}). We estimate that 6 x 10{sup 8} kg of dust was released with a high ejection velocity of 57 m s{sup -1} (assuming 1 {mu}m sized particles). While the asteroid is red in color and the ejecta have the same color as the Sun, we suggest that the dust does not contain any ice. Based on our observations, we conclude that (596) Scheila was most likely impacted by another main belt asteroid less than 100 m in diameter.

  16. Excavation Damaged Zones In Rock Salt Formations

    SciTech Connect

    Jockwer, N.; Wieczorek, K.

    2008-07-01

    Salt formations have long been proposed as potential host rocks for nuclear waste disposal. After the operational phase of a repository the openings, e.g., boreholes, galleries, and chambers, have to be sealed in order to avoid the release of radionuclides into the biosphere. For optimising the sealing techniques knowledge about the excavation damaged zones (EDZ) around these openings is essential. In the frame of a project performed between 2004 and 2007, investigations of the EDZ evolution were performed in the Stassfurt halite of the Asse salt mine in northern Germany. Three test locations were prepared in the floor of an almost 20 year old gallery on the 800-m level of the Asse mine: (1) the drift floor as existing, (2) the new drift floor shortly after removing of a layer of about 1 m thickness of the floor with a continuous miner, (3) the new drift floor 2 years after cutting off the 1-m layer. Subject of investigation were the diffusive and advective gas transport and the advective brine transport very close to the opening. Spreading of the brine was tracked by geo-electric monitoring in order to gain information about permeability anisotropy. Results obtained showed that EDZ cut-off is a useful method to improve sealing effectiveness when constructing technical barriers. (authors)

  17. Pre-excavation studies of prehistoric cave sites by magnetic prospecting

    NASA Astrophysics Data System (ADS)

    Itkis., Sonia; Matskevich, Zinovii; Meshveliani, Tengiz

    2014-05-01

    Detailed magnetic survey was performed for caves study in Israel (1995-1996) within the framework of the Beit Shemesh Regional Project (Judean Shephelah). The experience accumulated in Israel we applied later (2010) in two Georgian prehistoric cave sites: Cherula and Kotias-Klde. The magnetic method is based on the contrast in magnetic properties between a target object (e.g., buried archaeological feature) and the host medium (i.e, the surrounding bedrock and soil). The feasibility of the magnetic method for cave revealing was evaluated by magnetic susceptibility (κ) measurements of surrounding soil and rocks, and archaeological features: stones making up the walls, ceramic fragments and cave fill. According to data obtained, the κ of soil within caves (cave fill) is higher than that of surrounding soil. The enhancement of cave fill κ occurs because processes associated with human habitation: repeated heating and accumulation of organic debris. Both these processes provide good conditions for the conversion of the iron oxide found within the soil to a strongly ferromagnetic form (Mullins, 1977; Maher, 1986; Dalan and Banerjee, 1998, Itkis and Eppelbaum, 1999; Itkis, 2003) The presence of highly magnetic ceramics in caves also enhances magnetic contrast between practically non-magnetic bed rock (chalk in Ramat Beit Shemesh Site (Israel) and limestone (Georgian sites) and the cave fill, increasing the potential of the magnetic method to reveal caves (Itkis, 2011). Based on magnetic survey results, an excavation revealed a cave with a large amount of well preserved pottery and finds typical of the Early Bronze Age. Both studied cave sites in Georgia were located in Chiatura region of Imeretia province. Cherula site is a karstic rockshelter with a single chamber, ca 100 sq. m. The site was briefly tested in 1970s'. The area excavated in 2010 went to the depth of 60 cm below the present day surface; the limestone bedrock was not reached. The excavation revealed

  18. Determination of near field excavation disturbance in crystalline rock

    SciTech Connect

    Koopmans, R.; Hughes, R.W.

    1986-01-01

    The computerized dilatometer system has rapidly and economically provided deformation moduli of low and high modulus rock, determined the extent of excavation disturbance surrounding an underground opening and located open fracture within a rock mass. Results from both test sites indicate that the moduli obtained were influenced by the in situ tangential stress field. It has been shown that the near field excavation disturbance is kept to a minimum through the use of careful excavation techniques such as the tunnel boring machine. In turn, the in situ tangential stress levels and deformation moduli are maximized while the corresponding permeability is minimized.

  19. Reducing Extra-Terrestrial Excavation Forces with Percussion

    NASA Technical Reports Server (NTRS)

    Schuler, Jason; Mueller, Robert; Smith, Drew; Nick, Andrew; Lippitt, Thomas

    2012-01-01

    High launch costs and mission requirements drive the need for low mass excavators with mobility platforms, which in turn have little traction and excavation reaction capacity in low gravity environments. This presents the need for precursor and long term future missions with low mass robotic mining technology to perform In-Situ Resource Utilization (ISRU) tasks. This paper discusses a series of experiments that investigate the effectiveness of a percussive digging device to reduce excavation loads and thereby the mass of the excavator itself. The goal of percussive excavation is to fluidize dry regolith in front of the leading edge of the tool by mechanically separating the microscopic interlocking grains resulting in a reduced force needed to shear the soil. There are several variables involved with this technique; this experiment varied: Impact energy, frequency, and excavation speed and held constant: impact direction, depth of cut, angle of tool, and soil bulk density. The test apparatus consisted of an aluminum truss bridge with a central pivoting arm. Attached to the arm was a winch with a load cell in line that recorded the tension in the cable and therefore the excavation load. The arm could be adjusted for excavation depth which was recorded along with the arm angle relative to the bridge. A percussive mechanism and 30" wide pivoting bucket were attached at the end of the arm simulating a basic backhoe with a percussion direction tangent to the direction of . movement. Internally the mechanism used a set of die springs and barrel cam to produce the percussive blow. By changing the springs and the speed of the motor the impact energy and frequency of percussion could be varied independently. Impact energies from 11.2J to 30.5J and frequencies from 0 BPM to 700 BPM were investigated. A reduction in excavation force of as much as 51% was achieved in this experimental investigation. Smaller percussive digging implements, tested by others, have achieved a

  20. Changes in rock salt permeability due to nearby excavation

    SciTech Connect

    Stormont, J C; Howard, C L

    1991-07-01

    Changes in brine and gas permeability of rock salt as a result of nearby excavation (mine-by) have been measured from the underground workings of the WIPP facility. Prior to the mine-by, the formation responds as a porous medium with a very low brine permeability, a significant pore (brine) pressure and no measurable gas permeability. The mine-by excavation creates a dilated, partially saturated zone in the immediate vicinity of the excavation with an increased permeability to brine and a measurable permeability to gas. The changes in hydrologic properties are discussed in the context of pore structure changes.

  1. Relative Importance of Modularity and Other Morphological Attributes on Different Types of Lithic Point Weapons: Assessing Functional Variations

    PubMed Central

    González-José, Rolando; Charlin, Judith

    2012-01-01

    The specific using of different prehistoric weapons is mainly determined by its physical properties, which provide a relative advantage or disadvantage to perform a given, particular function. Since these physical properties are integrated to accomplish that function, examining design variables and their pattern of integration or modularity is of interest to estimate the past function of a point. Here we analyze a composite sample of lithic points from southern Patagonia likely formed by arrows, thrown spears and hand-held points to test if they can be viewed as a two-module system formed by the blade and the stem, and to evaluate the degree in which shape, size, asymmetry, blade: stem length ratio, and tip angle explain the observed variance and differentiation among points supposedly aimed to accomplish different functions. To do so we performed a geometric morphometric analysis on 118 lithic points, departing from 24 two-dimensional landmark and semi landmarks placed on the point's contour. Klingenberg's covariational modularity tests were used to evaluate different modularity hypotheses, and a composite PCA including shape, size, asymmetry, blade: stem length ratio, and tip angle was used to estimate the importance of each attribute to explaining variation patterns. Results show that the blade and the stem can be seen as “near decomposable units” in the points integrating the studied sample. However, this modular pattern changes after removing the effects of reduction. Indeed, a resharpened point tends to show a tip/rest of the point modular pattern. The composite PCA analyses evidenced three different patterns of morphometric attributes compatible with arrows, thrown spears, and hand-held tools. Interestingly, when analyzed independently, these groups show differences in their modular organization. Our results indicate that stone tools can be approached as flexible designs, characterized by a composite set of interacting morphometric attributes, and

  2. Blasting and excavating on precarious rock slopes

    SciTech Connect

    Oriard, L.L.

    1996-12-01

    There is an intuitive tendency to equate rock strength with rock stability, yet the two must be evaluated separately. A slope in strong hard rock is not necessarily stable, nor is a slope in weathered weak rock necessarily unstable. In some cases the reverse is true, depending on the geometry of joints and weak planes. The time element is a matter of special concern, that is how suddenly the failure begins and how rapidly it progresses. An important element in avoiding catastrophes is to study the site geology for dangerous conditions, implement the types of blasting procedures that minimize failures, and evaluate the potential use of reinforcement or other mechanical stabilizing procedures. It may be possible to reinforce the perimeters of structural excavations, but that is not usually possible for quarry or surface mine operations. However, it is often possible to change a dangerous operation into a safe one merely by changing the orientation, sequence or dimensions of the work without changing other details of the blasting designs. Several important principles are illustrated in this paper, using case histories. One case is that of a catastrophic slope failure in Mexico, and the remedial procedures used to get the work back into operation. That case is compared to large-scale work which was done safely on a similar site in Spain, even with an 850 ft high slope and up to 200 ft between safety benches. Also illustrated are some of the procedures used for delicate work on sensitive slopes at a site in Colombia, South America, and those used to preserve a delicate narrow rib of rock in a deep river canyon on the Snake River in Idaho. Brief reference is made also to slope damage on a Canadian project.

  3. 4. VIEW OF AREA EXCAVATED FOR ACCESS TO MERCURY RETORT. ...

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

    4. VIEW OF AREA EXCAVATED FOR ACCESS TO MERCURY RETORT. VIEW SOUTH FROM RETORT. (OCTOBER, 1995) - McCormick Group Mine, Mercury Retort, East slope of Buckskin Mountain, Paradise Valley, Humboldt County, NV

  4. CONSTRUCTION PROGRESS PHOTO SHOWING EXCAVATION PIT FOR MAIN PROCESSING BUILDING ...

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

    CONSTRUCTION PROGRESS PHOTO SHOWING EXCAVATION PIT FOR MAIN PROCESSING BUILDING (CPP-601) LOOKING SOUTH. INL PHOTO NUMBER NRTS-50-693. Unknown Photographer, 1950 - Idaho National Engineering Laboratory, Idaho Chemical Processing Plant, Fuel Reprocessing Complex, Scoville, Butte County, ID

  5. EXCAVATION OF EAST (FRONT) BASEMENT WELL AND DRAINAGE SYSTEM, WITH ...

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

    EXCAVATION OF EAST (FRONT) BASEMENT WELL AND DRAINAGE SYSTEM, WITH ARCHED ENTRY INTO BASEMENT UNDER FRONT ENTRY IN BACKGROUND, LOOKING NORTH (NOTE GALLETING IN BRICK FOUNDATION) - Belair, Tulip Grove Drive, Belair-at-Bowie, Bowie, Prince George's County, MD

  6. General view of the archaeological site showing excavation and revealing ...

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

    General view of the archaeological site showing excavation and revealing the steps leading down into the eighteenth-century burial vault - Harry Buck House, North of Main Street (14800 Governor Oden Bowie Drive), Upper Marlboro, Prince George's County, MD

  7. 48. EXCAVATING AND DRIVING PILES FOR SHOOFLY BRIDGE, YOLO COUNTY ...

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

    48. EXCAVATING AND DRIVING PILES FOR SHOOFLY BRIDGE, YOLO COUNTY SIDE OF RIVER, November 7, 1934 - Sacramento River Bridge, Spanning Sacramento River at California State Highway 275, Sacramento, Sacramento County, CA

  8. 13. AERIAL VIEW SHOWING IN THE FOREGROUND, EXCAVATION FOR THE ...

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

    13. AERIAL VIEW SHOWING IN THE FOREGROUND, EXCAVATION FOR THE SPILLWAY APRON.... Volume XVII, No. 12, December 26, 1939. - Prado Dam, Spillway, Santa Ana River near junction of State Highways 71 & 91, Corona, Riverside County, CA

  9. 14. FLOODED POWER HOUSE FOUNDATION EXCAVATION BEING PUMPED OUT. NOTE ...

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

    14. FLOODED POWER HOUSE FOUNDATION EXCAVATION BEING PUMPED OUT. NOTE KEYS IN FOREBAY ABUTMENT TO INTERLOCK WITH POWER HOUSE FOUNDATION, March 1918. - Dam No. 5 Hydroelectric Plant, On Potomac River, Hedgesville, Berkeley County, WV

  10. 9. View looking S at archeological excavations at base of ...

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

    9. View looking S at archeological excavations at base of wall adjacent to Jamaican Train. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  11. 1. AERIAL VIEW SHOWING ARCHEOLOGICAL EXCAVATIONS OF LOCOMOTIVE PITS IN ...

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

    1. AERIAL VIEW SHOWING ARCHEOLOGICAL EXCAVATIONS OF LOCOMOTIVE PITS IN FORMER ERECTING SHOP. MACHINE SHOP IS BUILDING AT RIGHT. - Grant Locomotive Works, Market & Spruce Streets, Paterson, Passaic County, NJ

  12. 2. CLOSE IN AERIAL VIEW OF ARCHEOLOGICAL EXCAVATIONS OF LOCOMOTIVE ...

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

    2. CLOSE IN AERIAL VIEW OF ARCHEOLOGICAL EXCAVATIONS OF LOCOMOTIVE PITS IN FORMER ERECTING SHOP. MACHINE SHOP IS BUILDING AT RIGHT. - Grant Locomotive Works, Market & Spruce Streets, Paterson, Passaic County, NJ

  13. 8. General view looking S at archeological excavations along base ...

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

    8. General view looking S at archeological excavations along base of west wall of purging house. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  14. 18. View of archeological excavations along base of mill wall ...

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

    18. View of archeological excavations along base of mill wall showing unidentified pits. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  15. 9. Excavation work at Pleasant Dam (now called Waddell Dam). ...

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

    9. Excavation work at Pleasant Dam (now called Waddell Dam). Photographer unknown, July, 22, 1926. Source: Maricopa County Municipal Water Conservation District Number One (MWD). - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  16. 27. photographer unknown undated DREDGING OVERBURDEN FROM CRIB EXCAVATION AREAS ...

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

    27. photographer unknown undated DREDGING OVERBURDEN FROM CRIB EXCAVATION AREAS IN MAIN CHANNEL FOR FIRST STEP COFFERDAM. BRADFORD ISLAND IN BACKGROUND. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  17. 42. View of emergency spillway excavation looking downstream from spillway. ...

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

    42. View of emergency spillway excavation looking downstream from spillway. Photographer unknown, 1929. Source: ADWR. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  18. 41. Upstream end of emergency spillway excavation. Photographer unknown, 1929. ...

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

    41. Upstream end of emergency spillway excavation. Photographer unknown, 1929. Source: Arizona Department of Water Resources (ADWR). - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  19. 16. TAILRACE ARCH FROM 1814 MILL BROKEN THROUGH DURING EXCAVATION ...

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

    16. TAILRACE ARCH FROM 1814 MILL BROKEN THROUGH DURING EXCAVATION FOR A SURFACE WATER RUNOFF POLLUTION TRAP, SUBSEQUENTLY FILLED. - Boston Manufacturing Company, 144-190 Moody Street, Waltham, Middlesex County, MA

  20. Telerobotic Excavator Designed to Compete in NASA's Lunabotics Mining Competition

    NASA Technical Reports Server (NTRS)

    Nash, Rodney; Santin, Cara; Yousef, Ahmed; Nguyen, Thien; Helferty, John; Pillapakkam, Shriram

    2011-01-01

    The second annual NASA Lunabotics Mining competition is to be held in May 23-28, 2011. The goal of the competition is for teams of university level students to design, build, test and compete with a fully integrated lunar excavator on a simulated lunar surface. Our team, named Lunar Solutions I, will be representing Temple University's College of Engineering in the competition. The team's main goal was to build a robot which is able to compete with other teams, and ultimately win the competition. The main challenge of the competition was to build a wireless robot that can excavate and collect a minimum of 10 kilograms of the regolith material within 15 minutes. The robot must also be designed to operate in conditions similar to those found on the lunar surface. The design of the lunar excavator is constrained by a set of requirements determined by NASA and detailed in the competition's rulebook. The excavator must have the ability to communicate with the "main base" wirelessly, and over a Wi-Fi network. Human operators are located at a remote site approximately 60 meters away from the simulated lunar surface upon which the robot must excavate the lunar regolith surface. During the competition, the robot will operate in a separate area from the control room in an area referred to as the "Lunarena." From the control room, the operators will have to control the robot using visual feedback from cameras placed both within the arena and on the robot. Using this visual feedback the human operators control the robots movement using both keyboard and joystick commands. In order to place in the competition, a minimum of 10 kg of regolith material has to be excavated, collected, and dumped into a specific location. For that reason, the robot must be provided with an effective and powerful excavation system. Our excavator uses tracks for the drive system. After performing extensive research and trade studies, we concluded that tracks would be the most effective method for

  1. Impact-Actuated Digging Tool for Lunar Excavation

    NASA Technical Reports Server (NTRS)

    Wilson, Jak; Chu, Philip; Craft, Jack; Zacny, Kris; Santoro, Chris

    2013-01-01

    NASA s plans for a lunar outpost require extensive excavation. The Lunar Surface Systems Project Office projects that thousands of tons of lunar soil will need to be moved. Conventional excavators dig through soil by brute force, and depend upon their substantial weight to react to the forces generated. This approach will not be feasible on the Moon for two reasons: (1) gravity is 1/6th that on Earth, which means that a kg on the Moon will supply 1/6 the down force that it does on Earth, and (2) transportation costs (at the time of this reporting) of $50K to $100K per kg make massive excavators economically unattractive. A percussive excavation system was developed for use in vacuum or nearvacuum environments. It reduces the down force needed for excavation by an order of magnitude by using percussion to assist in soil penetration and digging. The novelty of this excavator is that it incorporates a percussive mechanism suited to sustained operation in a vacuum environment. A percussive digger breadboard was designed, built, and successfully tested under both ambient and vacuum conditions. The breadboard was run in vacuum to more than 2..times the lifetime of the Apollo Lunar Surface Drill, throughout which the mechanism performed and held up well. The percussive digger was demonstrated to reduce the force necessary for digging in lunar soil simulant by an order of magnitude, providing reductions as high as 45:1. This is an enabling technology for lunar site preparation and ISRU (In Situ Resource Utilization) mining activities. At transportation costs of $50K to $100K per kg, reducing digging forces by an order of magnitude translates into billions of dollars saved by not launching heavier systems to accomplish excavation tasks necessary to the establishment of a lunar outpost. Applications on the lunar surface include excavation for habitats, construction of roads, landing pads, berms, foundations, habitat shielding, and ISRU.

  2. NOVEL EXCAVATION TECHNOLOGIES FOR EFFICIENT AND ECONOMIC SURFACE MINING

    SciTech Connect

    Vladislav Kecojevic; Samuel Frimpong

    2005-05-01

    Ground excavation constitutes a significant component of production costs in any surface mining operation. The excavation process entails material digging and removal in which the equipment motion is constrained by the workspace geometry. A major excavation problem is the variability of material properties, resulting in varying mechanical energy input and stress loading of shovel dipper-and-tooth assembly across the working bench. This variability has a huge impact on the shovel dipper and tooth assembly in hard formations. With this in mind, the primary objectives of the project were to (i) provide the theoretical basis to develop the Intelligent Shovel Excavation (ISE) technology to solve the problems associated with excavation in material formations; (ii) advance knowledge and frontiers in shovel excavation through intelligent navigation; and (iii) submit proposal for the design, development and implementation of the ISE technology for shovel excavation at experimental surface mining sites. The mathematical methods were used to (i) develop shovel's kinematics and dynamics, and (ii) establish the relationship between shovel parameters and the resistive forces from the material formation during excavation process. The ADAMS simulation environment was used to develop the hydraulic and cable shovel virtual prototypes. Two numerical examples are included to test the theoretical hypotheses and the obtained results are discussed. The area of sensor technology was studied. Application of specific wrist-mounted sensors to characterize the material, bucket and frame assembly was determined. Data acquisition, display and control system for shovel loading technology was adopted. The concept of data acquisition and control system was designed and a shovel boom stresses were simulated. A multi-partner collaboration between research organizations, shovel manufacturer, hardware and sensor technology companies, and surface mining companies is proposed to test design features

  3. SIMULATING FISH ASSEMBLAGE DYNAMICS IN RIVER NETWORKS

    EPA Science Inventory

    My recently retired colleague, Joan Baker, and I have developed a prototype computer simulation model for studying the effects of human and non-human alterations of habitats and species availability on fish assemblage populations. The fish assemblage model, written in R, is a sp...

  4. Intelligent excavator control system for lunar mining system

    NASA Astrophysics Data System (ADS)

    Lever, Paul J. A.; Wang, Fei-Yue

    1995-01-01

    A major benefit of utilizing local planetary resources is that it reduces the need and cost of lifting materials from the Earth's surface into Earth orbit. The location of the moon makes it an ideal site for harvesting the materials needed to assist space activities. Here, lunar excavation will take place in the dynamic unstructured lunar environment, in which conditions are highly variable and unpredictable. Autonomous mining (excavation) machines are necessary to remove human operators from this hazardous environment. This machine must use a control system structure that can identify, plan, sense, and control real-time dynamic machine movements in the lunar environment. The solution is a vision-based hierarchical control structure. However, excavation tasks require force/torque sensor feedback to control the excavation tool after it has penetrated the surface. A fuzzy logic controller (FLC) is used to interpret the forces and torques gathered from a bucket mounted force/torque sensor during excavation. Experimental results from several excavation tests using the FLC are presented here. These results represent the first step toward an integrated sensing and control system for a lunar mining system.

  5. Cratos: A Simple Low Power Excavation and Hauling System for Lunar Oxygen Production and General Excavation Tasks

    NASA Technical Reports Server (NTRS)

    Caruso, John J.; Greer, Lawrence C.; John, Wentworth T.; Spina, Dan C.; Krasowski, Mike J.; Abel, Phillip B.; Prokop, Norman F.; Flatico, Joseph M.; Sacksteder, Kurt R.

    2007-01-01

    The development of a robust excavating and hauling system for lunar and planetary excavation is critical to the NASA mission to the Moon and Mars. Cratos was developed as a low center of gravity, small (.75m x .75m x 0.3m), low power tracked test vehicle. The vehicle was modified to excavate and haul because it demonstrated good performance capabilities in a laboratory and field testing. Tested on loose sand in the SLOPE facility, the vehicle was able to pick up, carry, and dump sand, allowing it to accomplish the standard requirements delivery of material to a lunar oxygen production site. Cratos can pick up and deliver raw material to a production plant, as well as deliver spent tailings to a disposal site. The vehicle can complete many other In-Situ Resource Utilization (ISRU) excavation chores and in conjunction with another vehicle or with additional attachments may be able to accomplish all needed ISRU tasks.

  6. Identification of New Lithic Clasts in Lunar Breccia 14305 by Micro-CT and Micro-XRF Analysis

    NASA Technical Reports Server (NTRS)

    Zeigler, Ryan A.; Carpenter, Paul K.; Jolliff, Bradley L.

    2014-01-01

    From 1969 to 1972, Apollo astronauts collected 382 kg of rocks, soils, and core samples from six locations on the surface of the Moon. The samples were initially characterized, largely by binocular examination, in a custom-built facility at Johnson Space Center (JSC), and the samples have been curated at JSC ever since. Despite over 40 years of study, demand for samples remains high (500 subsamples per year are allocated to scientists around the world), particularly for plutonic (e.g., anorthosites, norites, etc.) and evolved (e.g., granites, KREEP basalts) lithologies. The reason for the prolonged interest is that as new scientists and new techniques examine the samples, our understanding of how the Moon, Earth, and other inner Solar System bodies formed and evolved continues to grow. Scientists continually clamor for new samples to test their emerging hypotheses. Although all of the large Apollo samples that are igneous rocks have been classified, many Apollo samples are complex polymict breccias that have previously yielded large (cm-sized) igneous clasts. In this work we present the initial efforts to use the non-destructive techniques of micro-computed tomography (micro-CT) and micro x-ray fluorescence (micro-XRF) to identify large lithic clasts in Apollo 14 polymict breccia sample 14305. The sample in this study is 14305,483, a 150 g slab of regolith breccia 14305 measuring 10x6x2 cm (Figure 1a). The sample was scanned at the University of Texas High-Resolution X-ray CT Facility on an Xradia MicroXCT scanner. Two adjacent overlapping volumes were acquired at 49.2 micrometer resolution and stitched together, resulting in 1766 slices. Each volume was acquired at 100 kV accelerating voltage and 98 mA beam current with a 1 mm CaF2 filter, with 2161 views gathered over 360deg at 3 seconds acquisition time per view. Micro-XRF analyses were done at Washington University in St. Louis, Missouri on an EDAX Orbis PC micro-XRF instrument. Multiple scans were made at 40 k

  7. Excavations at Schöningen and paradigm shifts in human evolution.

    PubMed

    Conard, Nicholas J; Serangeli, Jordi; Böhner, Utz; Starkovich, Britt M; Miller, Christopher E; Urban, Brigitte; Van Kolfschoten, Thijs

    2015-12-01

    The exceptional preservation at Schöningen together with a mixture of perseverance, hard work, and sheer luck led to the recovery of unique finds in an exceptional context. The 1995 discovery of numerous wooden artifacts, most notably at least 10 carefully made spears together with the skeletons of at least 20 to 25 butchered horses, brought the debate about hunting versus scavenging among late archaic hominins and analogous arguments about the purportedly primitive behavior of Homo heidelbergensis and Neanderthals to an end. Work under H. Thieme's lead from 1992 to 2008 and results from the current team since 2008 demonstrate that late H. heidelbergensis or early Neanderthals used sophisticated artifacts made from floral and faunal materials, in addition to lithic artifacts more typically recovered at Lower Paleolithic sites. The finds from the famous Horse Butchery Site and two dozen other archaeological horizons from the edges of the open-cast mine at Schöningen provide many new insights into the technology and behavioral patterns of hominins about 300 ka BP during MIS 9 on the Northern European Plain. An analysis of the finds from Schöningen and their contexts shows that the inhabitants of the site were skilled hunters at the top of the food chain and exhibited a high level of planning depth. These hominins had command of effective means of communication about the here and now, and the past and the future, that allowed them to repeatedly execute well-coordinated and successful group activities that likely culminated in a division of labor and social and economic patterns radically different from those of all non-human primates. The unique preservation and high quality excavations have led to a major paradigm shift or "Schöningen Effect" that changed our views of human evolution during the late Lower Paleolithic. In this respect, we can view the behaviors documented at Schöningen as a plausible baseline for the behavioral sophistication of archaic hominins

  8. Collective workload organization in confined excavation of granular media

    NASA Astrophysics Data System (ADS)

    Monaenkova, Daria; Linevich, Vadim; Goodisman, Michael A.; Goldman, Daniel I.

    2015-03-01

    Many social insects collectively construct large nests in complex substrates; such structures are often composed of narrow tunnels. The benefits of collective construction, including reduced construction costs per worker come with challenges of navigation in crowded, confined spaces. Here we study the workforce organization of groups of S. invicta fire ants creating tunnels in wet granular media. We monitor the activity levels of marked (painted) workers-defined as a number of tunnel visits over 12 hours- during initiation of tunnels. The activity levels are described by a Lorenz curve with a Gini coefficient of ~ 0 . 7 indicating that a majority of the excavation is performed by a minority of workers. We hypothesize that this workload distribution is beneficial for excavation in crowded conditions, and use a 2D cellular automata (CA) model to reproduce behaviors of the excavating ants. CA simulations reveal that tunnel construction rates decrease in groups of equally active animals compared to groups with the natural workload distribution. We use predictions of the CA model to organize collective excavation of granular material by teams of digging robots, and use the robots to test hypotheses of crowded excavation in the physical world. We acknowledge support of National Science Foundation, Physics of Living Systems division.

  9. Archean geotherms and supracrustal assemblages

    NASA Astrophysics Data System (ADS)

    Condie, Kent C.

    1984-06-01

    Metamorphic mineral assemblages suggest the existence of variable geotherms and lithospheric thicknesses beneath late Archean continental crust. Archean granite-greenstone terranes reflect steep geotherms (50-70°C/km) while high-grade terranes reflect moderate geotherms similar to present continental crust with high heat flow (25-40°C/km). Corresponding lithosphere thicknesses for each terrane during the late Archean are 35-50 km and 50-75 km, respectively. Early Archean (⩾ 3.0 b.y.) greenstones differ from late Archean (˜ 2.7 b.y.) greenstones by the rarity or absence of andesite and graywacke and the relative abundance of pelite, quartzite, and komatiite. Mature clastic sediments in early greenstones reflect shallow-water, stable-basin deposition. Such rocks, together with granite-bearing conglomerate and felsic volcanics imply the existence of still older granitic source terranes. The absence or rarity of andesite in early greenstones reflects the absence of tectonic conditions in which basaltic and tonalitic magmas are modified to produce andesite. A model is presented in which early Archean greenstones form at the interface between tonalite islands and oceanic lithosphere, over convective downcurrents; high-grade supracrustals form on stable continental edges or interiors; and late Archean greenstones form in intracontinental rifts over mantle plumes.

  10. [Morphology of a lithic lesion of the bone treated with cement filling with the addition of methotrexate].

    PubMed

    Król, R; Waloszczyk, P; Uciński, R; Pankowski, J

    2000-01-01

    The results of histopathologic examination of a lithic bony lesion and of the surrounding soft tissues obtained from a metastatic site from 2 patients are presented. Both patients had been previously treated surgically with a 40 g bone cement filling with 2 g of methotrexate. Revision surgical intervention was necessary because of loss of stability at the fracture site in a 68 year old female after with a metastasis from breast cancer after 8 weeks and in a 72 year old male with metastasis from cancer of the prostate after 10 weeks. During revision surgery the metal plates and the cement were removed. Tissues samples from the fracture site were taken for histopathologic examination. Fibrosis of connective tissue and haemosiderin accumulation were noted in the soft tissues surrounding the fractures site. Where there was direct contact between the bone cement and bone, necrosis of bone trabeculae and granuloma like bodies were noted. Revision surgery 10 weeks after the first procedure revealed more advanced bony necrosis. No cancerous tissue was observed in any of the cases. PMID:10838774

  11. Quantifying lithic microwear with load variation on experimental basalt flakes using LSCM and area-scale fractal complexity (Asfc)

    NASA Astrophysics Data System (ADS)

    Stemp, W. James; Morozov, Mikhail; Key, Alastair J. M.

    2015-09-01

    Working load is one factor that affects wear on stone tools. Despite the recognition of the importance of the relationship between working load and the development of microwear on stone tools, there have been few attempts to quantify differences in wear due to changes in load. In a controlled experiment, we used 30 basalt flakes knapped from raw material collected in Olduvai Gorge, Tanzania, Africa, to cut oak branches for the same number of strokes. For each flake, a different loading level was applied starting at 150 g and increasing by increments of 150 g to a maximum load of 4.5 kg. A laser scanning confocal microscope was used to mathematically document the surface texture of the flakes. The worn surface data were compared using area-scale fractal complexity (Asfc), calculated from relative areas, to determine the degree to which variation in loading significantly affected the amount of wear on the flake surfaces. Our results indicate that working load does play a role in the development of lithic microwear on these flakes and that discrimination of two worn flake surfaces, using mean square ratios of Asfc, based on variable load is consistently possible with load differences between ∼100 g and 4.5 kg. However, discrimination of microwear on flake surfaces was not consistent for all load level differences and discrimination became less consistent when working load differences were below ∼100 g.

  12. Cyanobacteria are confined to dewless habitats within a dew desert: Implications for past and future climate change for lithic microorganisms

    NASA Astrophysics Data System (ADS)

    Kidron, Giora J.; Starinsky, Abraham; Yaalon, Dan H.

    2014-11-01

    Although covering almost all rock outcrops around the world, little is known regarding the factors that govern the spatial distribution of lithic cyanobacteria and lichens. This is also the case in the Negev Desert, where cyanobacteria predominate on the rock outcrops of the south-facing slopes and lichens on the rock outcrops of the north-facing slopes. Hypothesizing that abiotic conditions determine their distribution, radiation, temperature, rain, dew and fog were monitored over a two-year period (2008-2010) at cyanobacteria- and lichen-dwelling habitats within a first-order drainage basin in the Negev Highlands. While non-significant differences characterized the rain amounts, substantial differences in substrate temperatures were recorded which resulted in turn in fundamental differences in the non-rainfall water regime. While dew condensed at the rock outcrops of the lichen habitat, no condensation took place at the cyanobacteria habitat. Contrary to the common belief, cyanobacteria were found to inhabit dewless habitats. As a result, cyanobacteria solely rely on rain precipitation for growth and can therefore serve as bioindicators for dewless habitats within the dewy Negev Desert. The findings may have important implications regarding Earth colonization, soil forming processes and geochemical processes following climate warming. They may explain lichen expansion and subsequent O2 increase during the mid Neoproterozoic providing indirect support for substantial photosynthetic activity and high weathering rates during this era.

  13. Taphonomic analysis of the early Pleistocene (2.4 Ma) faunal assemblage from A.L. 894 (Hadar, Ethiopia).

    PubMed

    Domínguez-Rodrigo, Manuel; Martínez-Navarro, Bienvenido

    2012-03-01

    The A.L. 894 site (Hadar, Ethiopia) is, together with OGS 7 (Gona, Ethiopia), one of the oldest archaeological sites documenting a spatial association of stone tools and bones retrieved from an in situ excavation. In contrast with OGS 7, the better preservation of the bone assemblage at A.L. 894 allows the identification of taphonomic processes of bone breakage, thanks to abundant green bone fractures. The presence of tooth marks and the lack of hominin-produced bone modifications together argue against hominins as the responsible agents for bone accumulation and modification. This taphonomic study of A.L. 894 shows lack of evidence for functional associations between stone tools and bones, a pattern documented in several other early Pleistocene sites. Such a pattern underscores the complex phenomena involved in site formation processes, especially in the earliest archaeological assemblages. PMID:20207393

  14. Giardia duodenalis genetic assemblages and hosts

    PubMed Central

    Heyworth, Martin F.

    2016-01-01

    Techniques for sub-classifying morphologically identical Giardia duodenalis trophozoites have included comparisons of the electrophoretic mobility of enzymes and of chromosomes, and sequencing of genes encoding β-giardin, triose phosphate isomerase, the small subunit of ribosomal RNA and glutamate dehydrogenase. To date, G. duodenalis organisms have been sub-classified into eight genetic assemblages (designated A–H). Genotyping of G. duodenalis organisms isolated from various hosts has shown that assemblages A and B infect the largest range of host species, and appear to be the main (or possibly only) G. duodenalis assemblages that undeniably infect human subjects. In at least some cases of assemblage A or B infection in wild mammals, there is suggestive evidence that the infection had resulted from environmental contamination by G. duodenalis cysts of human origin. PMID:26984116

  15. A Novel Energy Recovery System for Parallel Hybrid Hydraulic Excavator

    PubMed Central

    Li, Wei; Cao, Baoyu; Zhu, Zhencai; Chen, Guoan

    2014-01-01

    Hydraulic excavator energy saving is important to relieve source shortage and protect environment. This paper mainly discusses the energy saving for the hybrid hydraulic excavator. By analyzing the excess energy of three hydraulic cylinders in the conventional hydraulic excavator, a new boom potential energy recovery system is proposed. The mathematical models of the main components including boom cylinder, hydraulic motor, and hydraulic accumulator are built. The natural frequency of the proposed energy recovery system is calculated based on the mathematical models. Meanwhile, the simulation models of the proposed system and a conventional energy recovery system are built by AMESim software. The results show that the proposed system is more effective than the conventional energy saving system. At last, the main components of the proposed energy recovery system including accumulator and hydraulic motor are analyzed for improving the energy recovery efficiency. The measures to improve the energy recovery efficiency of the proposed system are presented. PMID:25405215

  16. Remotely operated excavator needs assessment/site visit summary

    SciTech Connect

    Straub, J.; Haller, S.; Worsley, R.; King, M.

    1992-12-02

    The Uranium in Soils Integrated Demonstration requested an assessment of soil excavation needs relative to soil remediation. The following list identifies the DOE sites assessed: Mound Laboratory, Paducah Gaseous Diffusion Plant, Portsmouth Gaseous Diffusion Plant, Nevada Test Site, Lawrence Livermore National Laboratory, Rocky Flats Plant, Los Alamos National Laboratory, Sandia National Laboratory, Idaho National Engineering Laboratory, Hanford Site, and Fernald Site. The reviewed sites fall into one or more of the following three categories: production, EPA National Priorities List, or CERCLA (superfund) designation. Only three of the sites appear to have the need for a remotely operated excavator rope. Hanford and Idaho Falls have areas of high-level radioactive contamination either buried or in/under buildings. The Fernald site has a need for remote operated equipment of different types. It is their feeling that remote equipment can be used to remove the health dangers to humans by removing them from the area. Most interviewees stated that characterization technologies needs are more immediate concern over excavation. In addition, the sites do not have similar geographic conditions which would aid in the development of a generic precision excavator. The sites visited were not ready to utilize or provide the required design information necessary to draft a performance specification. This creates a strong case against the development of one type of ROPE for use at these sites. Assuming soil characterization technology/methodology is improved sufficiently to allow accurate and real time field characterization then development of a precision excavator might be pursued based on FEMP needs, since the FEMP`s sole scope of work is remediation. The excavator could then be used/tested and then later modified for other sites as warranted.

  17. Asteroid Icy Regolith Excavation and Volatile Capture Project

    NASA Technical Reports Server (NTRS)

    Zeitlin, Nancy; Mantovani, James; Swanger, Adam; Townsend, Ivan

    2015-01-01

    Icy regolith simulants will be produced in a relevant vacuum environment using various minerals, including hydrated minerals, that are found in C-type meteorites and in other types of planetary regolith. This will allow us to characterize the mechanical strength of the icy regolith as a function of ice content using penetration, excavation, and sample capture devices. The results of this study will benefit engineers in designing efficient regolith excavators and ISRU processing systems for future exploration missions to asteroids and other planetary bodies.

  18. Remote Excavation System technology evaluation report: Buried Waste Robotics Program

    SciTech Connect

    Not Available

    1993-09-01

    This document describes the results from the Remote Excavation System demonstration and testing conducted at the Idaho National Engineering Laboratory during June and July 1993. The purpose of the demonstration was to ascertain the feasibility of the system for skimming soil and removing various types of buried waste in a safe manner and within all regulatory requirements, and to compare the performances of manual and remote operation of a backhoe. The procedures and goals of the demonstration were previously defined in The Remote Excavation System Test Plan, which served as a guideline for evaluating the various components of the system and discussed the procedures used to conduct the tests.

  19. Calculation of Excavation Force for ISRU on Lunar Surface

    NASA Technical Reports Server (NTRS)

    Zeng, Xiangwu (David); Burnoski, Louis; Agui, Juan H.; Wilkinson, Allen

    2007-01-01

    Accurately predicting the excavation force that will be encountered by digging tools on the lunar surface is a crucial element of in-situ resource utilization (ISRU). Based on principles of soil mechanics, this paper develops an analytical model that is relatively simple to apply and uses soil parameters that can be determined by traditional soil strength tests. The influence of important parameters on the excavation force is investigated. The results are compared with that predicted by other available theories. Results of preliminary soil tests on lunar stimulant are also reported.

  20. Geotechnical characterization and construction methods for SSC tunnel excavation

    SciTech Connect

    Nelson, P.P.; Lundin, T.K. Superconducting Super Collider Lab., Dallas, TX )

    1990-06-01

    The site for the Superconducting Super Collider (SSC) facility was selected in 1988 after a nationwide proposal competition. The selected site is located in Ellis County, Texas, surrounding the town of Waxahachie which is about 30 miles (48 km) south of the City of Dallas central business district. This paper will describe the geotechnical conditions anticipated for excavation at the SSC site. A general geologic and geomechanical description of the rock present will be followed by a summary of the site-specific conceptual design for the tunneled components of the SSC machine. The Supercollider project will include about 70 miles (113) km of tunnel excavation.

  1. The nature of organic records in impact excavated rocks on Mars

    NASA Astrophysics Data System (ADS)

    Montgomery, W.; Bromiley, G. D.; Sephton, M. A.

    2016-08-01

    Impact ejected rocks are targets for life detection missions to Mars. The Martian subsurface is more favourable to organic preservation than the surface owing to an attenuation of radiation and physical separation from oxidising materials with increasing depth. Impact events bring materials to the surface where they may be accessed without complicated drilling procedures. On Earth, different assemblages of organic matter types are derived from varying depositional environments. Here we assess whether these different types of organic materials can survive impact events without corruption. We subjected four terrestrial organic matter types to elevated pressures and temperatures in piston-cylinder experiments followed by chemical characterisation using whole-rock pyrolysis-gas chromatography-mass spectrometry. Our data reveal that long chain hydrocarbon-dominated organic matter (types I and II; mainly microbial or algal) are unresistant to pressure whereas aromatic hydrocarbon-dominated organic matter types (types III and IV; mainly land plant, metamorphosed or degraded, displaying some superficial chemical similarities to abiotic meteoritic organic matter) are relatively resistant. This suggests that the impact excavated record of potential biology on Mars will be unavoidably biased, with microbial organic matter underrepresented while metamorphosed, degraded or abiotic meteoritic organic matter types will be selectively preserved.

  2. The nature of organic records in impact excavated rocks on Mars

    PubMed Central

    Montgomery, W.; Bromiley, G. D.; Sephton, M. A.

    2016-01-01

    Impact ejected rocks are targets for life detection missions to Mars. The Martian subsurface is more favourable to organic preservation than the surface owing to an attenuation of radiation and physical separation from oxidising materials with increasing depth. Impact events bring materials to the surface where they may be accessed without complicated drilling procedures. On Earth, different assemblages of organic matter types are derived from varying depositional environments. Here we assess whether these different types of organic materials can survive impact events without corruption. We subjected four terrestrial organic matter types to elevated pressures and temperatures in piston-cylinder experiments followed by chemical characterisation using whole-rock pyrolysis-gas chromatography-mass spectrometry. Our data reveal that long chain hydrocarbon-dominated organic matter (types I and II; mainly microbial or algal) are unresistant to pressure whereas aromatic hydrocarbon-dominated organic matter types (types III and IV; mainly land plant, metamorphosed or degraded, displaying some superficial chemical similarities to abiotic meteoritic organic matter) are relatively resistant. This suggests that the impact excavated record of potential biology on Mars will be unavoidably biased, with microbial organic matter underrepresented while metamorphosed, degraded or abiotic meteoritic organic matter types will be selectively preserved. PMID:27492071

  3. The nature of organic records in impact excavated rocks on Mars.

    PubMed

    Montgomery, W; Bromiley, G D; Sephton, M A

    2016-01-01

    Impact ejected rocks are targets for life detection missions to Mars. The Martian subsurface is more favourable to organic preservation than the surface owing to an attenuation of radiation and physical separation from oxidising materials with increasing depth. Impact events bring materials to the surface where they may be accessed without complicated drilling procedures. On Earth, different assemblages of organic matter types are derived from varying depositional environments. Here we assess whether these different types of organic materials can survive impact events without corruption. We subjected four terrestrial organic matter types to elevated pressures and temperatures in piston-cylinder experiments followed by chemical characterisation using whole-rock pyrolysis-gas chromatography-mass spectrometry. Our data reveal that long chain hydrocarbon-dominated organic matter (types I and II; mainly microbial or algal) are unresistant to pressure whereas aromatic hydrocarbon-dominated organic matter types (types III and IV; mainly land plant, metamorphosed or degraded, displaying some superficial chemical similarities to abiotic meteoritic organic matter) are relatively resistant. This suggests that the impact excavated record of potential biology on Mars will be unavoidably biased, with microbial organic matter underrepresented while metamorphosed, degraded or abiotic meteoritic organic matter types will be selectively preserved. PMID:27492071

  4. Phytoplankton Assemblage Characteristics in Recurrently Fluctuating Environments

    PubMed Central

    Roelke, Daniel L.; Spatharis, Sofie

    2015-01-01

    Annual variations in biogeochemical and physical processes can lead to nutrient variability and seasonal patterns in phytoplankton productivity and assemblage structure. In many coastal systems river inflow and water exchange with the ocean varies seasonally, and alternating periods can arise where the nutrient most limiting to phytoplankton growth switches. Transitions between these alternating periods can be sudden or gradual and this depends on human activities, such as reservoir construction and interbasin water transfers. How such activities might influence phytoplankton assemblages is largely unknown. Here, we employed a multispecies, multi-nutrient model to explore how nutrient loading switching mode might affect characteristics of phytoplankton assemblages. The model is based on the Monod-relationship, predicting an instantaneous growth rate from ambient inorganic nutrient concentrations whereas the limiting nutrient at any given time was determined by Liebig’s Law of the Minimum. Our simulated phytoplankton assemblages self-organized from species rich pools over a 15-year period, and only the surviving species were considered as assemblage members. Using the model, we explored the interactive effects of complementarity level in trait trade-offs within phytoplankton assemblages and the amount of noise in the resource supply concentrations. We found that the effect of shift from a sudden resource supply transition to a gradual one, as observed in systems impacted by watershed development, was dependent on the level of complementarity. In the extremes, phytoplankton species richness and relative overyielding increased when complementarity was lowest, and phytoplankton biomass increased greatly when complementarity was highest. For low-complementarity simulations, the persistence of poorer-performing phytoplankton species of intermediate R*s led to higher richness and relative overyielding. For high-complementarity simulations, the formation of phytoplankton

  5. Discontinuous behavior near excavations in a bedded salt formation

    SciTech Connect

    Stormont, J.C.

    1990-10-01

    Discontinuous behavior is being observed and measured in the vicinity of excavations constructed in a bedded salt formation 650 m below ground surface for the Waste Isolation Pilot Plant (WIPP) Facility. The 2 m thick salt layer in the immediate roof acts as a beam, shearing along a thin overlying anhydrite/clay seam. The floor of the excavations is comprised of a 1 m thick salt layer underlain by a 1 m thick predominately anhydrite layer (referred to as MB139). In the ribs, there is limited fracturing within the first meter of most larger excavations. Vertical fractures develop in pillars at most intersections. The discontinuous behavior is qualitatively consistent with analyses of the formation behaving as a layered medium (elastic beam analysis) and limited tensile and compressive failure of the rock salt. The significance of the discontinuous behavior is that can dominate the effective fluid transport properties of the formation near the excavation, and therefore requires considerations in the design of repository seals. Furthermore, the discontinuous behavior must be monitored and is a very important consideration in the maintenance program designed to assume a safe underground environment. 22 refs., 17 figs.

  6. 56. Historic photo of excavation work at Building 202, shows ...

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

    56. Historic photo of excavation work at Building 202, shows facility with exhaust scrubber in foreground, February 24, 1969. On file at NASA Plumbrook Research Center, Sandusky, Ohio. NASA photo number C-69-712. - Rocket Engine Testing Facility, GRC Building No. 202, NASA Glenn Research Center, Cleveland, Cuyahoga County, OH

  7. 55. Historic photo of excavation work at Building 202, shows ...

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

    55. Historic photo of excavation work at Building 202, shows facility with detention tank in foreground, February 24, 1969. On file at NASA Plumbrook Research Center, Sandusky, Ohio. NASA photo number C-69-711. - Rocket Engine Testing Facility, GRC Building No. 202, NASA Glenn Research Center, Cleveland, Cuyahoga County, OH

  8. CONSTRUCTION PROGRESS PHOTO SHOWING EXCAVATION PIT FOR MAIN PROCESSING BUILDING ...

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

    CONSTRUCTION PROGRESS PHOTO SHOWING EXCAVATION PIT FOR MAIN PROCESSING BUILDING (CPP-601) LOOKING NORTHWEST. INL PHOTO NUMBER NRTS-50-885. Unknown Photographer, 10/30/1950 - Idaho National Engineering Laboratory, Idaho Chemical Processing Plant, Fuel Reprocessing Complex, Scoville, Butte County, ID

  9. An Analysis of Excavation Support Safety Based on Experimental Studies

    NASA Astrophysics Data System (ADS)

    Gorska, Karolina; Wyjadłowski, Marek

    2015-09-01

    The article presents the results of inclinometric measurements and numerical analyses of soldier-pile wall displacements. The excavation under investigation was made in cohesive soils. The measurements were conducted at points located at the edge of the cantilever excavation support system. The displacements of the excavation support observed over the period of three years demonstrated the pattern of steady growth over the first two months, followed by a gradual levelling out to a final plateau. The numerical analyses were conducted based on 3D FEM models. The numerical analysis of the problem comprise calculations of the global structural safety factor depending on the displacement of the chosen points in the lagging and conducted by means of the φ/c reduction procedure. The adopted graphical method of safety estimation is very conservative in the sense that it recognizes stability loss quite early, when one could further load the medium or weaken it by further strength reduction. The values of the Msf factor are relatively high. This is caused by the fact that the structure was designed for excavation twice as deep. Nevertheless, the structure is treated as a temporary one.

  10. Granular Flow and Dynamics of Lunar Simulants in Excavating Implements

    NASA Technical Reports Server (NTRS)

    Agui, Juan H.; Wilkinson, R. Allen

    2010-01-01

    The exploration of the lunar surface will rely on properly designed excavation equipment for surface preparations and for collection of lunar regolith in In-Situ Resource Utilization (ISRU) processes. Performance efficiency, i.e minimizing loading forces while maximizing material collection, and mass and volume reductions are major design goals. The NASA Glenn Research Center has embarked on an experimental program to determine the flow characteristics and dynamic forces produced by excavation operations using various excavator bucket designs. A new large scale soil bin facility, 2.27 m x 5.94 m x 0.76 m (nominally 8 ft. x 20 ft. x 27 in.) in size, capable of accommodating moderately large test implements was used for the simulations of lunar operations. The soil bin is filled with GRC-3simulant (a mixture of industrial sands and silt with a particle size distribution and the bulk mechanical (shear) strength representative of an average of lunar regolith from different regions) and uses motorized horizontal rails and a vertical actuator to drive the implement through the lunar simulant soil. A six-axis load cell and encoders provide well resolved measurements of the three dimensional forces and torques and motion of the bucket. In addition, simultaneous video allows for the analysis of the flow behavior and structure formation of the regolith during excavation. The data may be useful in anchoring soil mechanic models and to provide engineering data for design consideration.

  11. 43 CFR 10.3 - Intentional archaeological excavations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... for obtaining such permits, see 25 CFR part 262 or contact the Deputy Commissioner of Indian Affairs... PROTECTION AND REPATRIATION REGULATIONS Human Remains, Funerary Objects, Sacred Objects, or Objects of... objects, sacred objects, or objects of cultural patrimony that are excavated intentionally from Federal...

  12. 43 CFR 10.3 - Intentional archaeological excavations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... for obtaining such permits, see 25 CFR part 262 or contact the Deputy Commissioner of Indian Affairs... PROTECTION AND REPATRIATION REGULATIONS Human Remains, Funerary Objects, Sacred Objects, or Objects of... objects, sacred objects, or objects of cultural patrimony that are excavated intentionally from Federal...

  13. Telemanipulation and supervisory control of a backhoe excavator

    NASA Astrophysics Data System (ADS)

    Luengo, Oscar; Barrientos, Antonio

    1998-12-01

    The excavation tasks present one of the more challenging area in robotic research. The environment is highly unstructured, the forces that appear are very large it is very important the detection of underground obstacles to avoid any damage, and the modeling of the hydraulic actuators is highly nonlinear. In recent years, the remote control of the excavation has found applications in very dangerous environments for human beings, like nuclear power plants, nuclear and chemical waste facilities and terrestrial and extra-terrestrial mining. Some kind of intelligence is required due to the presence of unexpected situations. The first approach to deal with the problem is to put a human being in the loop, that is: teleoperation. The next step towards the total automation of the excavation is the supervisory control of the task. In this scheme, the operator acts like a supervisor, providing high level commands, and checking the development and accomplishment of the task. The solutions that DISAM has developed are presented in this paper, as well as future work that will be very useful in the search for the total automation of excavation tasks.

  14. 6. VIEW WEST, INTERIOR CANAL WALL, FLOOR FULLY EXCAVATED (Original ...

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

    6. VIEW WEST, INTERIOR CANAL WALL, FLOOR FULLY EXCAVATED (Original Fabric) - Bald Eagle Cross-Cut Canal Lock, North of Water Street along West Branch of Susquehanna River South bank, 500 feet East of Jay Street Bridge, Lock Haven, Clinton County, PA

  15. 8. DETAIL OF WEST WALL, FLOOR FULLY EXCAVATED, CROSS MEMBER ...

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

    8. DETAIL OF WEST WALL, FLOOR FULLY EXCAVATED, CROSS MEMBER (Original Fabric) - Bald Eagle Cross-Cut Canal Lock, North of Water Street along West Branch of Susquehanna River South bank, 500 feet East of Jay Street Bridge, Lock Haven, Clinton County, PA

  16. 7. DETAIL OF WEST WALL, FLOOR FULLY EXCAVATED, FIRST AND ...

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

    7. DETAIL OF WEST WALL, FLOOR FULLY EXCAVATED, FIRST AND SECOND LAYER OF PLANKS (Original Fabric) - Bald Eagle Cross-Cut Canal Lock, North of Water Street along West Branch of Susquehanna River South bank, 500 feet East of Jay Street Bridge, Lock Haven, Clinton County, PA

  17. 9. VIEW NORTH, EXCAVATED LOCK FROM WATER STREET (Numbers painted ...

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

    9. VIEW NORTH, EXCAVATED LOCK FROM WATER STREET (Numbers painted on stones for reconstruction purposes) - Bald Eagle Cross-Cut Canal Lock, North of Water Street along West Branch of Susquehanna River South bank, 500 feet East of Jay Street Bridge, Lock Haven, Clinton County, PA

  18. 40. Photocopied August 1978. EXCAVATION IN THE FOREBAY, VIEW LOOKING ...

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

    40. Photocopied August 1978. EXCAVATION IN THE FOREBAY, VIEW LOOKING WEST, MARCH 31, 1899. THE EQUIPMENT USED IN THIS AREA WAS MAINLY MAN-OR HORSE-POWERED SINCE SOIL CONDITIONS HERE (NEAR THE RIVER) WERE TOO SOFT TO PERMIT HEAVY EQUIPMENT. (28) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  19. CUTS FOR MTR EXCAVATION ILLUSTRATE SEDIMENTARY MANTLE OF SOIL AND ...

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

    CUTS FOR MTR EXCAVATION ILLUSTRATE SEDIMENTARY MANTLE OF SOIL AND GRAVEL OVERLAYING LAVA ROCK FIFTY FEET BELOW. SAGEBRUSH HAS BEEN SCOURED FROM REST OF SITE. CAMERA PROBABLY FACES SOUTHWEST. INL NEGATIVE NO. 67. Unknown Photographer, 6/4/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  20. 30. DETAILED FRONTAL VIEW WEST OF EXCAVATION AT SUSPECTED MICA ...

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

    30. DETAILED FRONTAL VIEW WEST OF EXCAVATION AT SUSPECTED MICA PIT, SHOWING SOIL MIXED WITH MICA FLAKES AT REAR, AND DEEPER HOLE OF VIRGIN SOIL AT FRONT. - Vulcan Crucible Steel Company, Building No. 3, 100 First Street, Aliquippa, Beaver County, PA

  1. OEM unveil new ideas for shovels and excavators

    SciTech Connect

    Fiscor, S.

    2006-08-15

    From upgrades to new loading arrangements, vendors are looking at new ways to optimize the production process. The paper describes P & M equipment's new C series electric shovels equipped with the centurion system, Hitachi's super-sized excavator to Canadian oil sands, and Bucyrus and Siemens' engineer shovels. 3 figs., 1 photo.

  2. 10. View looking northwest at excavation into serpentine rock. Formwork ...

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

    10. View looking northwest at excavation into serpentine rock. Formwork at left is for pump room. Partially completed caisson is in foreground. Portion of Point Avisadero visible at right (12/17/42). Photographer unknown. - Hunters Point Naval Shipyard, Drydock No. 4, East terminus of Palou Avenue, San Francisco, San Francisco County, CA

  3. VIEW OF SOUTH GUN EMPLACEMENT. NOTE THE EXCAVATED EDGE OF ...

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

    VIEW OF SOUTH GUN EMPLACEMENT. NOTE THE EXCAVATED EDGE OF THE GUN BLOCK IN THE FOREGROUND. VIEW FACING NORTH - U.S. Naval Base, Pearl Harbor, Ford Island 5-Inch Antiaircraft Battery, South Gun Emplacement, Ford Island, Pearl City, Honolulu County, HI

  4. 17. Photocopy of photograph showing excavation of South Bank Substation ...

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

    17. Photocopy of photograph showing excavation of South Bank Substation site, 15 May 1939 (from the BPA Photo Archives, Portland, Oregon, Negative No. 345), LOOKING WEST - Bonneville Power Administration South Bank Substation, I-84, South of Bonneville Dam Powerhouse, Bonneville, Multnomah County, OR

  5. Development and demonstration of a telerobotic excavation system

    NASA Technical Reports Server (NTRS)

    Burks, Barry L.; Thompson, David H.; Killough, Stephen M.; Dinkins, Marion A.

    1994-01-01

    Oak Ridge National Laboratory is developing remote excavation technologies for the Department of Energy's Office (DOE) of Technology Development, Robotics Technology Development Program, and also for the Department of Defense (DOD) Project Manager for Ammunition Logistics. This work is being done to meet the need for remote excavation and removal of radioactive and contaminated buried waste at several DOE sites and unexploded ordnance at DOD sites. System requirements are based on the need to uncover and remove waste from burial sites in a way that does not cause unnecessary personnel exposure or additional environmental contamination. Goals for the current project are to demonstrate dexterous control of a backhoe with force feedback and to implement robotic operations that will improve productivity. The Telerobotic Small Emplacement Excavator is a prototype system that incorporates the needed robotic and telerobotic capabilities on a commercially available platform. The ability to add remote dexterous teleoperation and robotic operating modes is intended to be adaptable to other commercially available excavator systems.

  6. The statistical upper mantle assemblage

    NASA Astrophysics Data System (ADS)

    Meibom, Anders; Anderson, Don L.

    2004-01-01

    A fundamental challenge in modern mantle geochemistry is to link geochemical data with geological and geophysical observations. Most of the early geochemical models involved a layered mantle and the concept of geochemical reservoirs. Indeed, the two layer mantle model has been implicit in almost all geochemical literature and the provenance of oceanic island basalt (OIB) and mid-ocean ridge basalt (MORB) [van Keken et al., Annu. Rev. Earth Planet. Sci. 30 (2002) 493-525]. Large-scale regions in the mantle, such as the 'convective' (i.e. well-stirred, homogeneous) upper mantle, sub-continental lithosphere, and the lower mantle were treated as distinct and accessible geochemical reservoirs. Here we discuss evidence for a ubiquitous distribution of small- to moderate-scale (i.e. 10 2-10 5 m) heterogeneity in the upper mantle, which we refer to as the statistical upper mantle assemblage (SUMA). This heterogeneity forms as the result of long-term plate tectonic recycling of sedimentary and crustal components. The SUMA model does not require a convectively homogenized MORB mantle reservoir, which has become a frequently used concept in geochemistry. Recently, Kellogg et al. [Earth Planet. Sci. Lett. 204 (2002) 183-202] modeled MORB and OIB Sr and Nd isotopic compositions as local mantle averages of random distributions of depleted residues and recycled continental crustal material. In this model, homogenization of the MORB source region is achieved by convective stirring and mixing. In contrast, in the SUMA model, the isotopic compositions of MORB and OIB are the outcome of homogenization during sampling, by partial melting and magma mixing (e.g. [Helffrich and Wood, Nature 412 (2001) 501-507]), of a distribution of small- to moderate-scale upper mantle heterogeneity, as predicted by the central limit theorem. Thus, the 'SUMA' acronym also captures what we consider the primary homogenization process: sampling upon melting and averaging. SUMA does not require the

  7. Radiopaque Tagging Masks Caries Lesions following Incomplete Excavation in vitro.

    PubMed

    Schwendicke, F; Meyer-Lueckel, H; Schulz, M; Dörfer, C E; Paris, S

    2014-06-01

    One-step incomplete excavation seals caries-affected dentin under a restoration and appears to be advantageous in the treatment of deep lesions. However, it is impossible to discriminate radiographically between intentionally left, arrested lesions and overlooked or active lesions. This diagnostic uncertainty decreases the acceptance of minimally invasive excavation and might lead to unnecessary re-treatment of incompletely excavated teeth. Radiopaque tagging of sealed lesions might mask arrested lesions and assist in discrimination from progressing lesions. Therefore, we microradiographically screened 4 substances (SnCl2, AgNO3, CsF, CsCH3COO) for their effect on artificial lesions. Since water-dissolved tin chloride (SnCl2×Aq) was found to stably mask artificial lesions, we then investigated its radiographic effects on progressing lesions. Natural lesions were incompletely excavated and radiopaque tagging performed. Grey-value differences (△GV) between sound and carious dentin were determined and radiographs assessed by 20 dentists. While radiographic effects of SnCl2×Aq were stable for non-progressing lesions, they significantly decreased during a second demineralization (p < .001, t test). For natural lesions, tagging with SnCl2×Aq significantly reduced △GV (p < .001, Wilcoxon). Tagged lesions were detected significantly less often than untagged lesions (p < .001). SnCl2×Aq was suitable to mask caries-affected dentin and discriminate between arrested and progressing lesions in vitro. Radiopaque tagging could resolve diagnostic uncertainties associated with incomplete excavation. PMID:24718110

  8. Scrapheap Challenge: A novel bulk-bone metabarcoding method to investigate ancient DNA in faunal assemblages

    PubMed Central

    Murray, Dáithí C.; Haile, James; Dortch, Joe; White, Nicole E.; Haouchar, Dalal; Bellgard, Matthew I.; Allcock, Richard J.; Prideaux, Gavin J.; Bunce, Michael

    2013-01-01

    Highly fragmented and morphologically indistinct fossil bone is common in archaeological and paleontological deposits but unfortunately it is of little use in compiling faunal assemblages. The development of a cost-effective methodology to taxonomically identify bulk bone is therefore a key challenge. Here, an ancient DNA methodology using high-throughput sequencing is developed to survey and analyse thousands of archaeological bones from southwest Australia. Fossils were collectively ground together depending on which of fifteen stratigraphical layers they were excavated from. By generating fifteen synthetic blends of bulk bone powder, each corresponding to a chronologically distinct layer, samples could be collectively analysed in an efficient manner. A diverse range of taxa, including endemic, extirpated and hitherto unrecorded taxa, dating back to c.46,000 years BP was characterized. The method is a novel, cost-effective use for unidentifiable bone fragments and a powerful molecular tool for surveying fossils that otherwise end up on the taxonomic “scrapheap”. PMID:24288018

  9. Multidimensional chemical optimization of protein assemblages

    NASA Astrophysics Data System (ADS)

    Dick, J. M.; Shock, E.

    2010-12-01

    The formation of biomolecular assemblages, at all levels of organization from ecosystems to cellular protein complexes, is a crucial biological phenomenon that has complex physical and chemical requirements. Observations on the makeup and dynamics of gene and protein assemblages in natural environments are advancing at an astounding pace, but theoretical models are needed to interpret the chemical requirements of their formation and place them into a geochemical context. A chemical equilibrium model, while requiring relative few input variables, nevertheless gives a plethora of predictions for the relative abundances of proteins. We have implemented a computer algorithm for optimizing predictions of metastable assemblages of proteins by varying combinations of chemical activities of basis species, temperature and/or pressure. The target predictions include species richness, coefficient of variation, and correlation with a (log)normal distribution. Results of simulations for ribosomal protein assemblages from model organisms provide a foundation for interpreting metagenomic sequences from a hot spring environment. The optimization method was used at different temperatures to compute the chemical potentials of basis species that contain hydrogen, oxygen and other major elements in proteins. The results show that different protein assemblages can be distiguished on the basis of their chemical potential requirements as a function of temperature. Unlike many cluster analysis methods commonly used in bioinformatics, the variables in the equilibrium model are explicitly chemical variables that allow comparisons with geochemical measurements. These comparisons aid in interpretations of metagenomic data including documenting the emergence of scatter around the central trends of the chemical variables.

  10. 29 CFR 1926.913 - Blasting in excavation work under compressed air.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... rock face is approaching mixed face, and when tunnel excavation is in mixed face, blasting shall be... tunnel excavation in rock face approaches mixed face, to determine the general nature and extent of...

  11. 29 CFR 1926.913 - Blasting in excavation work under compressed air.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... rock face is approaching mixed face, and when tunnel excavation is in mixed face, blasting shall be... tunnel excavation in rock face approaches mixed face, to determine the general nature and extent of...

  12. Giardia duodenalis assemblages in Egyptian children with diarrhea.

    PubMed

    Fahmy, H M; El-Serougi, A O; El Deeb, H K; Hussein, H M; Abou-Seri, H M; Klotz, C; Aebischer, T; El Sayed Khalifa Mohamed, K

    2015-08-01

    Giardia duodenalis is considered the most common cause of parasitic diarrhea worldwide. Genetic studies revealed that at least eight assemblages (A-H) exist. Of these assemblages, A and B are found primarily in human beings and occasionally in animals. The association between clinical symptoms and G. duodenalis assemblages is controversial. The aim of the present study was to determine the assemblages of G. duodenalis prevalent among Egyptian children with diarrhea. Therefore, 96 positive stool samples for Giardia by light microscopy were subjected to multilocus genotyping targeting the triose phosphate isomerase (tpi), β-giardin (bg), and glutamate dehydrogenase (gdh) genes. Amplified polymerase chain reaction (PCR) products were then purified, sequenced, and aligned with reference strains to determine the assemblages of the Giardia isolates. Out of the 96 microscopically positive stool samples for Giardia, 77 (80 %) were successfully amplified and sequenced at least at one locus. Of these, 21 (27.3 %) were shown to be assemblage A, 54 (70.1 %) assemblage B, while discordant sequence typing results were observed in 2 (2.6 %) samples. AII was the predominant subassemblage of assemblage A, while it was generally difficult to further classify assemblage B. It was concluded that infection with assemblage B was more common than that with assemblage A. No associations between epidemiological information and assemblage were detected, except with age. Although infections with assemblage B were more frequently associated with abdominal pain and acute diarrhea than with assemblage A, the difference was not statistically significant. PMID:25939803

  13. Chemical divides and evaporite assemblages on Mars

    NASA Astrophysics Data System (ADS)

    Tosca, Nicholas J.; McLennan, Scott M.

    2006-01-01

    Assemblages of evaporite minerals record detailed physical and chemical characteristics of ancient surficial environments. Accordingly, newly discovered regions of saline minerals on Mars are high priority targets for exploration. The chemical divide concept of evaporite mineral formation is used successfully to predict evaporite mineralogy and brine evolution on Earth. However, basaltic weathering largely controls fluid compositions on Mars and the robust predictive capabilities of terrestrial chemical divides cannot be used to interpret Martian evaporites. Here we present a new chemical divide system that predicts evaporite assemblages identified in SNC-type meteorites, ancient evaporites discovered on Meridiani Planum by the Opportunity rover, and Mars Express OMEGA data. We suggest that a common fluid type that has been buffered to different pH levels by basaltic weathering controls the variability among Martian evaporite assemblages and that evaporite mineralogy and brine evolution is essentially established by the initial composition of the dilute evaporating fluid.

  14. Rapid biotic homogenization of marine fish assemblages.

    PubMed

    Magurran, Anne E; Dornelas, Maria; Moyes, Faye; Gotelli, Nicholas J; McGill, Brian

    2015-01-01

    The role human activities play in reshaping biodiversity is increasingly apparent in terrestrial ecosystems. However, the responses of entire marine assemblages are not well-understood, in part, because few monitoring programs incorporate both spatial and temporal replication. Here, we analyse an exceptionally comprehensive 29-year time series of North Atlantic groundfish assemblages monitored over 5° latitude to the west of Scotland. These fish assemblages show no systematic change in species richness through time, but steady change in species composition, leading to an increase in spatial homogenization: the species identity of colder northern localities increasingly resembles that of warmer southern localities. This biotic homogenization mirrors the spatial pattern of unevenly rising ocean temperatures over the same time period suggesting that climate change is primarily responsible for the spatial homogenization we observe. In this and other ecosystems, apparent constancy in species richness may mask major changes in species composition driven by anthropogenic change. PMID:26400102

  15. The function of prehistoric lithic tools: a combined study of use-wear analysis and FTIR microspectroscopy.

    PubMed

    Nunziante Cesaro, Stella; Lemorini, Cristina

    2012-02-01

    The application of combined use-wear analysis and FTIR micro spectroscopy for the investigation of the flint and obsidian tools from the archaeological sites of Masseria Candelaro (Foggia, Italy) and Sant'Anna di Oria (Brindisi, Italy) aiming to clarify their functional use is described. The tools excavated in the former site showed in a very high percentage spectroscopically detectable residues on their working edges. The identification of micro deposits is based on comparison with a great number of replicas studied in the same experimental conditions. FTIR data confirmed in almost all cases the use-wear analysis suggestions and added details about the material processed and about the working procedures. PMID:22074884

  16. A Review of Lunar Regolith Excavation Robotic Device Prototypes

    NASA Technical Reports Server (NTRS)

    Mueller, Robert P.; Van Susante, Paul J.

    2011-01-01

    The excavation of lunar regolith is desirable for use as a feedstock for oxygen production processes as well as civil engineering purposes and for the fabrication of parts and structures. This is known as In-Situ Resource Utilization (ISRU). More recently, there has been mounting evidence that water ice exists at the poles of the Moon, buried in the regolith where thermally stable conditions exist. This means that regolith excavation will be required to mine the water ice which is believed to be. mixed in with the regolith, or bonded to it. The mined water ice can then be electrolyzed to produce hydrogen and oxygen propellants which could form the basis of a cis-lunar transportation system using in-situ derived propellants. In 2007, the National Aeronautics & Space Administration (NASA) sponsored a Lunar Regolith Excavation Competition as part of its Centennial Challenges program, The competition was not won and it was held again in 2008 and 2009, when it was won by a university team. A $500,000 prize was awarded to the winning team by NASA. In 2010, NASA continued the competition as a spinoff of the Centennial Challenges, which is restricted to university participation only. This competition is known as the "Lunabotics Mining Competition" and is hosted by NASA at Kennedy Space Center. Twenty three American university teams competed in the 2010 Lunabotics Mining Competition. The competition was held again in May 2011 with over 60 teams registered, including international participation. The competition will be held again in May 2012 at Kennedy Space Center in Florida. . This paper contains a thorough review of the various regolith eX,cavation robotic device prototypes that competed in these NASA competitions, and will. classify the machines and their methods of excavation to document the variety of ideas that were spawned and built to compete at these events. It is hoped that documentation of these robots will serve to help future robotic excavation designers and

  17. 43 CFR 15.3 - Dredging, filling, excavating and building activities.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 1 2014-10-01 2014-10-01 false Dredging, filling, excavating and building activities. 15.3 Section 15.3 Public Lands: Interior Office of the Secretary of the Interior KEY LARGO CORAL REEF PRESERVE § 15.3 Dredging, filling, excavating and building activities. No dredging, excavating,...

  18. 43 CFR 15.3 - Dredging, filling, excavating and building activities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Dredging, filling, excavating and building activities. 15.3 Section 15.3 Public Lands: Interior Office of the Secretary of the Interior KEY LARGO CORAL REEF PRESERVE § 15.3 Dredging, filling, excavating and building activities. No dredging, excavating, or filling operations of any kind...

  19. 43 CFR 15.3 - Dredging, filling, excavating and building activities.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 1 2013-10-01 2013-10-01 false Dredging, filling, excavating and building activities. 15.3 Section 15.3 Public Lands: Interior Office of the Secretary of the Interior KEY LARGO CORAL REEF PRESERVE § 15.3 Dredging, filling, excavating and building activities. No dredging, excavating,...

  20. 43 CFR 15.3 - Dredging, filling, excavating and building activities.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Dredging, filling, excavating and building activities. 15.3 Section 15.3 Public Lands: Interior Office of the Secretary of the Interior KEY LARGO CORAL REEF PRESERVE § 15.3 Dredging, filling, excavating and building activities. No dredging, excavating,...

  1. 43 CFR 15.3 - Dredging, filling, excavating and building activities.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 1 2012-10-01 2011-10-01 true Dredging, filling, excavating and building activities. 15.3 Section 15.3 Public Lands: Interior Office of the Secretary of the Interior KEY LARGO CORAL REEF PRESERVE § 15.3 Dredging, filling, excavating and building activities. No dredging, excavating,...

  2. The Châtelperronian conundrum: Blade and bladelet lithic technologies from Quinçay, France.

    PubMed

    Roussel, M; Soressi, M; Hublin, J-J

    2016-06-01

    The discovery of an almost complete Neanderthal skeleton in a Châtelperronian context at Saint-Césaire 35 years ago changed our perspective on the beginning of the Upper Paleolithic in western Europe. Since then, the Châtelperronian has generally been considered a "transitional" industry rather than an Upper or a Middle Paleolithic industry because of its chronological position, and the association of Neanderthal remains with blades, bone tools and personal ornaments. Several competing hypotheses have been proposed to explain the association between Neanderthals and these types of artefacts including post-depositional mixing, acculturation from anatomically modern human populations, or an independent technological evolution by local Neanderthal populations. Quinçay Cave is the only Châtelperronian site where personal ornaments have been found that does not contain an overlying Upper Paleolithic layer. This means that the post-depositional mixing of later elements into the Châtelperronian may not be used as an explanation for the presence of these materials. We report here on a detailed technological analysis of lithic artefacts from the three Châtelperronian layers at Quinçay Cave. We compare our results with the technology of Mousterian blade industries dating to OIS (oxygen isotope stage) 5, the Mousterian of Acheulian Tradition type B, and the Proto-Aurignacian. We show that the Châtelperronian is sufficiently divergent from the Middle Paleolithic to be classified as a fully Upper Paleolithic industry, with a focus on blade and bladelet production. We also show that the Quinçay Châtelperronian includes retouched bladelets that resemble those found in the Proto-Aurignacian, but were produced in a different manner. We argue that a technological convergence cannot account for these behaviors, since the specific type of retouched bladelet associated with the Châtelperronian was also regularly used by Proto-Aurignacian of neighboring regions. We suggest

  3. Recycling of quartz-poor/lithic-rich foreland-basin sediments in arid climate (Euphrates-Tigris-Karun river system)

    NASA Astrophysics Data System (ADS)

    Garzanti, Eduardo; Juboury, Ali Ismail Al; Zoleikhaei, Yousef; Vermeesch, Pieter; Hamzah Abdulhussein Jotheri, Jaafar; Akkoca, Dicle Bal; Allen, Mark; Andò, Sergio; Limonta, Mara; Padoan, Marta; Resentini, Alberto; Vezzoli, Giovanni

    2016-04-01

    In this detailed petrological analysis of a large source-to-sink sediment-routing system (catchment area > 1 million km2) we document its several peculiarities, and illustrate a rich petrographic and heavy-mineral dataset integrated by bulk-sediment geochemistry and detrital-zircon U-Pb geochronological data that widens the spectrum of compositions generally assumed as paradigmatic for orogenic settings. We test traditional versus upgraded sedimentary-petrology models in the endeavor to derive a more refined conceptual model of reference, in order to enhance the power of provenance analysis but also to define its limitations and understand which secret of nature is likely to remain beyond reach in our efforts to reconstruct orogenic landscapes of the past. Sands derived from the Zagros-Southeast Anatolian fold-thrust belt contain an abundance of lithic grains derived not only first-cycle from carbonates, cherts, mudrocks, arc volcanics, and obducted mantle serpentinites representing the exposed shallow structural level of the orogen, but also recycled from Neogene molassic strata exposed in the foothills. Quartz, K-feldspar and mica are equally scarce in first-cycle and recycled sediments. This quartz-poor petrographic signature, characterizing the broad undissected tectonic domain of the Anatolia-Iranian plateau, is markedly distinct from that of sands shed by highly elevated and dissected collision orogens of the same mountain system such as the Himalaya or the Alps. Arid climate in the region allows full preservation of chemically unstable grains including carbonate and mafic/ultramafic rock fragments even through more than a single sedimentary cycle. Also, it reduces transport capacity of fluvial systems, which dump most of their load in Mesopotamian marshlands upstream of the Arabian/Persian Gulf allochemical carbonate factory. Quartz-poor orogenic sediments from the Zagros-Southeast Anatolian range mix with quartz-rich recycled sands ultimately derived from

  4. Detection of tunnel excavation using fiber optic reflectometry: experimental validation

    NASA Astrophysics Data System (ADS)

    Linker, Raphael; Klar, Assaf

    2013-06-01

    Cross-border smuggling tunnels enable unmonitored movement of people and goods, and pose a severe threat to homeland security. In recent years, we have been working on the development of a system based on fiber- optic Brillouin time domain reflectometry (BOTDR) for detecting tunnel excavation. In two previous SPIE publications we have reported the initial development of the system as well as its validation using small-scale experiments. This paper reports, for the first time, results of full-scale experiments and discusses the system performance. The results confirm that distributed measurement of strain profiles in fiber cables buried at shallow depth enable detection of tunnel excavation, and by proper data processing, these measurements enable precise localization of the tunnel, as well as reasonable estimation of its depth.

  5. Bilateral choroidal excavation in best vitelliform macular dystrophy.

    PubMed

    Parodi, Maurizio Battaglia; Zucchiatti, Ilaria; Fasce, Francesco; Bandello, Francesco

    2014-01-01

    Focal choroidal excavation (FCE) has recently been described as one or more localized areas of choroidal excavation on spectral-domain optical coherence tomography (SD-OCT). The authors describe a case of bilateral FCE in Best vitelliform macular dystrophy (VMD). SD-OCT revealed FCE in both eyes characterized by interruption of the internal segment-outer segment junction and the presence of subretinal hyporeflective space. This is the first report describing bilateral FCE in a distinct macular disorder and specifically with VMD. Future investigations are warranted to ascertain the involvement of other macular dystrophies with atrophic evolution and the impact of FCE on the clinical course. [Ophthalmic Surg Lasers Imaging Retina. 2014;45:e8-e10.]. PMID:24512759

  6. End effectors and attachments for buried waste excavation equipment

    SciTech Connect

    King, R.H.

    1993-09-01

    The Buried Waste Integrated Demonstration (BWID) supports the applied research, development, demonstration, and evaluation of a suite of advanced technologies that form a comprehensive remediation system for the effective and efficient remediation of buried waste. Their efforts are identified and coordinated in support of the U.S. Department of Energy (DOE), Environmental Restoration and Waste Management (ER&WM) Department`s needs and objectives. The present focus of BWID is to support retrieval and ex-situ treatment configuration options. Future activities will explore and support containment, and stabilization efforts in addition to the retrieval/ex situ treatment options. This report presents a literature search on the state-of-the-art in end effectors and attachments in support of excavator of buried transuranic waste. Included in the report are excavator platforms and a discussion of the various attachments. Also included is it list of vendors and specifications.

  7. The Montana ALE (Autonomous Lunar Excavator) Systems Engineering Report

    NASA Technical Reports Server (NTRS)

    Hull, Bethanne J.

    2012-01-01

    On May 2 1-26, 20 12, the third annual NASA Lunabotics Mining Competition will be held at the Kennedy Space Center in Florida. This event brings together student teams from universities around the world to compete in an engineering challenge. Each team must design, build and operate a robotic excavator that can collect artificial lunar soil and deposit it at a target location. Montana State University, Bozeman, is one of the institutions selected to field a team this year. This paper will summarize the goals of MSU's lunar excavator project, known as the Autonomous Lunar Explorer (ALE), along with the engineering process that the MSU team is using to fulfill these goals, according to NASA's systems engineering guidelines.

  8. 3. "TEST STAND NO. 13, EXCAVATION PLAN & SECTIONS." Specifications ...

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

    3. "TEST STAND NO. 1-3, EXCAVATION PLAN & SECTIONS." Specifications No. ENG 04-353-50-10; Drawing No. 60-0906; no sheet number within title block; D.O. SERIES 1109/10. Stamped: AS BUILT. No revisions or revision dates. Last work date on this drawing "Checked by EAG, 1/31/49." Though this drawing is specific to Test Stand 1-3, it also illustrates the general methods used for excavation design and retaining wall construction at Test Stand 1-5. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-3, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  9. EAST FACE OF REACTOR BASE. COMING TOWARD CAMERA IS EXCAVATION ...

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

    EAST FACE OF REACTOR BASE. COMING TOWARD CAMERA IS EXCAVATION FOR MTR CANAL. CAISSONS FLANK EACH SIDE. COUNTERFORT (SUPPORT PERPENDICULAR TO WHAT WILL BE THE LONG WALL OF THE CANAL) RESTS ATOP LEFT CAISSON. IN LOWER PART OF VIEW, DRILLERS PREPARE TRENCHES FOR SUPPORT BEAMS THAT WILL LIE BENEATH CANAL FLOOR. INL NEGATIVE NO. 739. Unknown Photographer, 10/6/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  10. Behavioral and mechanical determinants of collective subsurface nest excavation.

    PubMed

    Monaenkova, Daria; Gravish, Nick; Rodriguez, Greggory; Kutner, Rachel; Goodisman, Michael A D; Goldman, Daniel I

    2015-05-01

    Collective construction of topologically complex structures is one of the triumphs of social behavior. For example, many ant species construct underground nests composed of networks of tunnels and chambers. Excavation by these 'superorganisms' depends on the biomechanics of substrate manipulation, the interaction of individuals, and media stability and cohesiveness. To discover principles of robust social excavation, we used X-ray computed tomography to monitor the growth in three dimensions of nests built by groups of fire ants (Solenopsis invicta) in laboratory substrates composed of silica particles, manipulating two substrate properties: particle size and gravimetric moisture content. Ants were capable of nest construction in all substrates tested other than completely dry or fully saturated; for a given particle size, nest volume was relatively insensitive to moisture content. Tunnels were deepest at intermediate moisture content and the maximum tunnel depth correlated with measured yield force on small rod-shaped intruders (a proxy for cohesive strength). This implies that increased cohesive strength allowed creation of tunnels that were resistant to perturbation but did not decrease individual excavation ability. Ants used two distinct behaviors to create pellets composed of wetted particles, depending on substrate composition. However, despite the ability to create larger stable pellets in more cohesive substrates, pellet sizes were similar across all conditions. We posit that this pellet size balances the individual's load-carrying ability with the need to carry this pellet through confined crowded tunnels. We conclude that effective excavation of similarly shaped nests can occur in a diversity of substrates through sophisticated digging behaviors by individuals which accommodate both differing substrate properties and the need to work within the collective. PMID:25954041

  11. EXCAVATION OF EAST (FRONT) BASEMENT WELL AND DRAINAGE SYSTEM, WITH ...

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

    EXCAVATION OF EAST (FRONT) BASEMENT WELL AND DRAINAGE SYSTEM, WITH ARCHED ENTRY INTO BASEMENT UNDER FRONT ENTRY IN BACKGROUND, LOOKING NORTH (NOTE GALLETING IN BRICK FOUNDATION) BUT CLOSER RANGE SHOWING BRICK STRUCTURE WHICH CARRIED WATER FROM THE GUTTER DRAIN PIPE INTO THE BRICK DRAIN ALONG THE GROUND AND AWAY FROM THE FOUNDATION OF THE HOUSE - Belair, Tulip Grove Drive, Belair-at-Bowie, Bowie, Prince George's County, MD

  12. Driftwood dropstones in mid-Miocene shallow marine strata (Calvert Cliffs, Maryland Coastal Plain): An erratic lithic pebble des not necessarily a cold paleoclimate make

    NASA Astrophysics Data System (ADS)

    Vogt, P. R.; Parrish, M.

    2009-12-01

    Erratic lithic pebbles recovered from marine sediments are routinely identified as Ice-Rafted Debris (IRD), transported by icebergs, sea ice, or river ice discharged into the sea. We suggest this is not always the transport mechanism--especially when other paleoclimatologic proxies indicate relatively warm climates and extensive forests in the pebble provenance regions. Rivers could transport significant amounts of pebbbles as driftwood dropstones, trapped in the roots of trees and later uprooted in floods and carried out to sea. To illustrate a likely example of Tree-Rafted Detritus (TRD), we analyzed a collection of lithic erratics collected from three beds in eroding (5-10 cm/a) mid-Miocene (Serravalian)shallow marine deposits (upper Calvert Formation,Chesapeake Bay, southern Maryland), which predate the ca. 13.9 Ma global cooling and expansion of the East Antarctic Ice Sheet. The ca. 220 specimens (1-10 cm in diameter) are extremely variable in lithology and degree of roundness. The great majority are evidently of Piedmont provenance and were probably rafted ca. 120 km to the collection site from the paleo-mouth of the Susquehanna River, floated out to sea and carried south by the Miocene Coastal Current. River ice can probably be ruled out as the transport mechanism, given the prevailing warm temperate to subtropical climates. Common carbonized wood fragments (typically 2 x 10 cm in outcrop dimensions) in the same strata containing the erratics support driftwood transport. The lithic erratics may serve as independent tracers for terrestrial vertebrate fossils, transported into the Calvert Sea (Atlantic Ocean) by the 'float and bloat' mechanism.(Allowance has to be made for ca. 20 m/Ma post-middle Miocene source region denudation). However,only 3% of the clasts (mostly quartz diorite gneiss)could be readily related to a specific outcrop--the Port Deposit Gneiss near the modern mouth of the Susquehanna River. We suggest that driftwood transport be considered as

  13. Machinic Assemblages: Women, Art Education and Space

    ERIC Educational Resources Information Center

    Tamboukou, Maria

    2008-01-01

    In this paper I explore connections between women, art education and spatial relations drawing on the Deleuzo-Guattarian concept of "machinic assemblage" as a useful analytical tool for making sense of the heterogeneity and meshwork of life narratives and their social milieus. In focusing on Mary Bradish Titcomb, a fin-de-siecle Bostonian woman…

  14. Obesity Assemblages and Surveillance in Schools

    ERIC Educational Resources Information Center

    Rich, Emma

    2010-01-01

    In this paper, I draw on the growing body of work in surveillance studies, to examine the increasing propensity in recent years towards the monitoring and collection of information about children's weight and health within school contexts. Applying Haggerty and Ericson's concept of the surveillant assemblage within school contexts, the paper…

  15. Simulating fish assemblages in riverine networks

    EPA Science Inventory

    We describe a modeling approach for simulating assemblages of fish in riverine landscapes. The approach allows a user to determine the grain and extent of river networks within which fish populations reproduce, move, and survive in response to both environmental drivers and assem...

  16. EXCAVATOR: detecting copy number variants from whole-exome sequencing data.

    PubMed

    Magi, Alberto; Tattini, Lorenzo; Cifola, Ingrid; D'Aurizio, Romina; Benelli, Matteo; Mangano, Eleonora; Battaglia, Cristina; Bonora, Elena; Kurg, Ants; Seri, Marco; Magini, Pamela; Giusti, Betti; Romeo, Giovanni; Pippucci, Tommaso; De Bellis, Gianluca; Abbate, Rosanna; Gensini, Gian Franco

    2013-01-01

    We developed a novel software tool, EXCAVATOR, for the detection of copy number variants (CNVs) from whole-exome sequencing data. EXCAVATOR combines a three-step normalization procedure with a novel heterogeneous hidden Markov model algorithm and a calling method that classifies genomic regions into five copy number states. We validate EXCAVATOR on three datasets and compare the results with three other methods. These analyses show that EXCAVATOR outperforms the other methods and is therefore a valuable tool for the investigation of CNVs in largescale projects, as well as in clinical research and diagnostics. EXCAVATOR is freely available at http://sourceforge.net/projects/excavatortool/. PMID:24172663

  17. Lunar Excavation Experiments in Simulant Soil Test Beds-Revisiting the Surveyor Geotechnical Data

    NASA Technical Reports Server (NTRS)

    Agui, Juan H.; Wilkinson, R. Allen

    2012-01-01

    (1) Establishing ISRU technologies on planetary bodies is an important long-term goal of NASA; (2) Excavation is a key component of these ISRU processes; (3) Lack of flight data relevant to lunar excavation; (4) Existing models of the excavation-cutting phenomenon give varying results; (5) The lack of predictive models of the dynamic behavior of soils in excavation implements is a major driver for these studies; and (6) Objective: Need to develop robust models of excavation cutting phenomena that generate predictive capabilities to aid the designer and engineer.

  18. Mangrove macrobenthos: Assemblages, services, and linkages

    NASA Astrophysics Data System (ADS)

    Lee, S. Y.

    2008-02-01

    Macrobenthic assemblages are relatively poorly known compared to other components of the mangrove ecosystem. Tropical mangroves support macrobenthic biodiversity resources yet to be properly documented and interpreted. Some methodological challenges, such as the generally high spatial heterogeneity and complexity of the habitat, evidently reduce sampling efficiency and accuracy, while also leaving some microhabitats under-sampled. Macrobenthic assemblage structure seems to be influenced by local environmental conditions, such as hydroperiod, organic matter availability and sediment characteristics. Brachyurans, gastropods and oligochaetes dominate in the sediment, with the former two groups also common on hard surfaces provided by tree trunks, while insects and arachnids inhabit the canopy. Traditionally, studies of mangrove macrobenthos have focused on assemblage structure or the biology of individual species, but more complex inter-specific interactions and the inter-relationship between habitat and the biota are recently being addressed. Brachyuran crabs are the best-studied macrobenthos group, but many issues about their role in mangrove ecosystem dynamics are still controversial. Despite many species of mangrove macrobenthos being referred to as 'trophic dead ends', most serve as important links between recalcitrant mangrove organic matter and estuarine secondary production, through feeding excursion by mobile nekton during the high tide, and macrobenthos-mediated processing and exportation of organic matter. A significant difference in the standing crop biomass of forests between the Indo-west-Pacific (IWP)' and Atlantic-east-Pacific (AEP) mangroves may be related to the difference in species richness of mangrove as well as macrobenthos diversity in the two bioregions. Such differences in assemblage structure may also result in different ecosystem functioning, but the nature of the links is, however, yet to be explored. There is also a strong need for

  19. Silica exposure to excavation workers during the excavation of a low level radiological waste pit and tritium disposal shafts

    SciTech Connect

    Wilson, K.M.

    1995-01-01

    This study evaluated the task-length average (TLA) respirable dust and respirable silica airborne concentrations to which construction workers excavating volcanic tuff at Los Alamos National Laboratory (LANL) were exposed. These workers were excavating a low level radiological waste disposal pit of final dimensions 720 feet long, 132 feet wide and 60 feet deep. The objectives of this study were as follows: (1) evaluate exposures; (2) determine if the type of machinery used affects the respirable dust concentration in the breathing zone of the worker; (3) evaluate the efficacy of wetting the pit to reduce the respirable dust exposure; and (4) determine if exposure increases with increasing depth of pit due to the walls of the pit blocking the cross wind ventilation.

  20. Patterns of Assemblage Structure Indicate a Broader Conservation Potential of Focal Amphibians for Pond Management.

    PubMed

    Soomets, Elin; Rannap, Riinu; Lõhmus, Asko

    2016-01-01

    Small freshwater ponds host diverse and vulnerable biotic assemblages but relatively few conspicuous, specially protected taxa. In Europe, the amphibians Triturus cristatus and Pelobates fuscus are among a few species whose populations have been successfully restored using pond restoration and management activities at the landscape scale. In this study, we explored whether the ponds constructed for those two target species have wider conservation significance, particularly for other species of conservation concern. We recorded the occurrence of amphibians and selected aquatic macro-invertebrates (dragonflies; damselflies; diving beetles; water scavenger beetles) in 66 ponds specially constructed for amphibians (up to 8 years post construction) and, for comparison, in 100 man-made ponds (created by local people for cattle or garden watering, peat excavation, etc.) and 65 natural ponds in Estonia. We analysed nestedness of the species assemblages and its dependence on the environment, and described the co-occurrence patterns between the target amphibians and other aquatic species. The assemblages in all ponds were significantly nested, but the environmental determinants of nestedness and co-occurrence of particular species differed among pond types. Constructed ponds were most species-rich irrespective of the presence of the target species; however, T. cristatus was frequent in those ponds and rare elsewhere, and it showed nested patterns in every type of pond. We thus conclude that pond construction for the protected amphibians can serve broader habitat conservation aims in the short term. However, the heterogeneity and inconsistent presence of species of conservation concern observed in other types of ponds implies that long-term perspectives on pond management require more explicit consideration of different habitat and biodiversity values. We also highlight nestedness analysis as a tool that can be used for the practical task of selecting focal species for

  1. Patterns of Assemblage Structure Indicate a Broader Conservation Potential of Focal Amphibians for Pond Management

    PubMed Central

    Soomets, Elin; Rannap, Riinu; Lõhmus, Asko

    2016-01-01

    Small freshwater ponds host diverse and vulnerable biotic assemblages but relatively few conspicuous, specially protected taxa. In Europe, the amphibians Triturus cristatus and Pelobates fuscus are among a few species whose populations have been successfully restored using pond restoration and management activities at the landscape scale. In this study, we explored whether the ponds constructed for those two target species have wider conservation significance, particularly for other species of conservation concern. We recorded the occurrence of amphibians and selected aquatic macro-invertebrates (dragonflies; damselflies; diving beetles; water scavenger beetles) in 66 ponds specially constructed for amphibians (up to 8 years post construction) and, for comparison, in 100 man-made ponds (created by local people for cattle or garden watering, peat excavation, etc.) and 65 natural ponds in Estonia. We analysed nestedness of the species assemblages and its dependence on the environment, and described the co-occurrence patterns between the target amphibians and other aquatic species. The assemblages in all ponds were significantly nested, but the environmental determinants of nestedness and co-occurrence of particular species differed among pond types. Constructed ponds were most species-rich irrespective of the presence of the target species; however, T. cristatus was frequent in those ponds and rare elsewhere, and it showed nested patterns in every type of pond. We thus conclude that pond construction for the protected amphibians can serve broader habitat conservation aims in the short term. However, the heterogeneity and inconsistent presence of species of conservation concern observed in other types of ponds implies that long-term perspectives on pond management require more explicit consideration of different habitat and biodiversity values. We also highlight nestedness analysis as a tool that can be used for the practical task of selecting focal species for

  2. Chemistry and petrology of Luna 24 lithic fragments and less than 250-micron soils - Constraints on the origin of VLT mare basalts

    NASA Technical Reports Server (NTRS)

    Ma, M.-S.; Schmitt, R. A.; Taylor, G. J.; Warner, R. D.; Lange, D. E.; Keil, K.

    1978-01-01

    Results are reported on a combined INAA-petrologic study of 17 small (0.2-1.5 mg) Luna 24 lithic and mineral fragments and INAA study of 5 bulk soils and mineral separates from gabbro 24170. Lithic and mineral fragments are classified into VLT mare basalts (ferrobasalt and metabasalts), low-Ti, variolitic mare basalt, gabbros, melt rock and soil breccia. Data indicate 5 possible magma types, represented by: (1) VLT ferrobasalt and gabbro fragments, with low-TiO2 (about 1%), slightly bow-shaped REE pattern, and low REE concentrations (5-10X chondritic); (2) a ferrobasalt (Laul et al., 1978) and metabasalt fragments with major and trace element contents similar to (1), but positive Eu anomalies; (3) one gabbro fragment with distinctive pyroxene compositional trend (increasing Ti with nearly constant Fe/Fe + Mg) and highest REE contents of any Luna 24 mare basaltic sample, (4) a gabbro fragment with considerably less V and Cr2O3 than ferrobasalt and metabasalt fragments; and (5) variolitic basalt fragment with higher Ti2(2.3%) than other Luna 24 basalts and pyroxene that has increasing then decreasing Ti with increasing Fe/Fe + Mg. Trace element data place constraints on the nature of the source region and possible parent magmas for the Luna 24 VLT ferrobasalt.

  3. New age estimates for the Palaeolithic assemblages and Pleistocene succession of Casablanca, Morocco

    NASA Astrophysics Data System (ADS)

    Rhodes, E. J.; Singarayer, J. S.; Raynal, J.-P.; Westaway, K. E.; Sbihi-Alaoui, F. Z.

    2006-10-01

    Marine and aeolian Quaternary sediments from Casablanca, Morocco were dated using the optically stimulated luminescence (OSL) signal of quartz grains. These sediments form part of an extensive succession spanning the Pleistocene, and contain a rich faunal and archaeological record, including an Acheulian lithic assemblage from before the Brunhes-Matayama boundary, and a Homo erectus jaw from younger cave deposits. Sediment samples from the sites of Reddad Ben Ali, Oulad J'mel, Sidi Abderhamane and Thomas Quarries have been dated, in order to assess the upper limits of OSL. The revision of previously measured mammalian tooth enamel electron spin resonance (ESR) dates from the Grotte des Rhinocéros, Oulad Hamida Quarry 1, incorporating updated environmental dose rate measurements and attenuation calculations, also provide chronological constraint for the archaeological material preserved at Thomas Quarries. Several OSL age estimates extend back to around 500,000 years, with a single sample providing an OSL age close to 1 Ma in magnetically reversed sediments. These luminescence dates are some of the oldest determined, and their reliability is assessed using both internal criteria based on stratigraphic consistency, and external lithostratigraphic, morphostratigraphic and independent chronological constraints. For most samples, good internal agreement is observed using single aliquot regenerative-dose OSL measurements, while multiple aliquot additive-dose measurements generally have poorer resolution and consistency. Novel slow-component and component-resolved OSL approaches applied to four samples provide significantly enhanced dating precision, and an examination of the degree of signal zeroing at deposition. A comparison of the OSL age estimates with the updated ESR dates and one U-series date demonstrate that this method has great potential for providing reliable age estimates for sediments of this antiquity. We consider the cause of some slight age inversion

  4. The taphonomy of a Middle Devensian (MIS 3) vertebrate assemblage from Lynford, Norfolk, UK, and its implications for Middle Palaeolithic subsistence strategies

    NASA Astrophysics Data System (ADS)

    Schreve, Danielle C.

    2006-07-01

    The association of a rich lithic assemblage with a Middle Devensian mammalian assemblage at Lynford was initially thought indicative of a mammoth butchery locality, a rare occurrence for a European Middle Palaeolithic open site. However, taphonomic analyses suggest that the specimens have very different depositional histories and were incorporated into a palaeochannel in several stages. Most specimens are extremely fragmentary, probably the result of extensive trampling, and signs of weathering and root-damage provide further indications of exposure before burial. Carnivore damage is minimal but establishing the degree of interaction between the mammal fauna and alternative predators, such as Neanderthals, is problematic. Direct evidence of butchery is not present and the best indication of any form of mammoth exploitation lies in more circumstantial evidence such as the virtual absence of long bones from the main channel deposit and the mammoth age profiles. Instances of pathologies are also unusually common in the mammoths, implying that their greater vulnerability may have led to an accelerated demise either naturally or at the hands of a predator. The best evidence for direct faunal exploitation at the site is from green bone fractures and broken teeth that suggest marrow extraction in horse, reindeer and woolly rhinoceros. Copyright

  5. The beginning of the Upper Paleolithic in the Iranian Zagros. A taphonomic approach and techno-economic comparison of Early Baradostian assemblages from Warwasi and Yafteh (Iran).

    PubMed

    Tsanova, Tsenka

    2013-07-01

    Southwest Asia is a key region in current debates surrounding the appearance of the first cultures attributed to anatomically modern humans, particularly the Aurignacian and preceding cultural units of the Iranian Zagros, Levant, and the Balkans (Baradostian, Ahmarien, Kozarnikien, etc.). The Zagros mountain range encompasses an immense territory that remains understudied with regard to the Upper Paleolithic as well as the first bladelet industries traditionally presumed to be the work of anatomically modern humans. Concerning the emergence of the Aurignacian, the sites of Warwasi rockshelter and Yafteh cave in the central Zagros are considered to show evidence of in situ evolution of the Upper Paleolithic from the local Mousterian. This hypothesis is tested by way of a taphonomic, techno-typological and economic approach applied to the Upper Paleolithic levels of Warwasi (spits LL-AA) and Yafteh (the series from the lower part of the sequence). A comparison of the techno-economic features of both assemblages demonstrates a conceptual bond with contemporaneous techno-complexes from Levant and Europe (Ahmarian, Protoaurignacian, etc.). The techno-typological Middle Paleolithic character of the Warwasi lithic assemblage permits a discussion of a possible in situ dependence/continuum from the Mousterian or perhaps particular activities linked to the type of the occupation of the site. However, bladelet technology cannot be considered as rooted in the Zagros Mousterian. Consequently the origin of the Aurignacian sensu stricto has to be reconsidered. PMID:23742933

  6. Wrinkle ridge assemblages on the terrestrial planets

    NASA Technical Reports Server (NTRS)

    Watters, Thomas R.

    1988-01-01

    The morphological and dimensional similarities of the structures within the wrinkle ridge assemblages observed on terrestrial planets are investigated, including structures that occur in mare basalts on the moon and in smooth plains on Mars and Mercury. These structures can be classified as either arches or ridges on the basis of morphology, and ridges can be subdivided onto first-, second-, and third-order ridges on the basis of dimensions. Using ridge structures on the Columbia Plateau (U.S.) as analogs, a basis for a structural interpretation of the wrinkle ridge assemblages on the terrestrial planets is established. It is shown that the anticlinal ridges of the Columbia Plateau are appropriate analogs to the first-order ridges, supporting tectonic interpretations for the ridges.

  7. A low cost, high performance remotely controlled backhoe/excavator

    SciTech Connect

    Rizzo, J.

    1995-12-31

    This paper addresses a state of the art, low cost, remotely controlled backhoe/excavator system for remediation use at hazardous waste sites. The all weather, all terrain, Remote Dig-It is based on a simple, proven construction platform and incorporates state of the art sensors, control, telemetry and other subsystems derived from advanced underwater remotely operated vehicle systems. The system can be towed to a site without the use of a trailer, manually operated by an on board operator or operated via a fiber optic or optional RF communications link by a remotely positioned operator. A proportional control system is piggy backed onto the standard manual control system. The control system improves manual operation, allows rapid manual/remote mode selection and provides fine manual or remote control of all functions. The system incorporates up to 4 separate video links, acoustic obstacle proximity sensors, and stereo audio pickups and an optional differential GPS navigation. Video system options include electronic panning and tilting within a distortion-corrected wide angle field of view. The backhoe/excavator subsystem has a quick disconnect interface feature which allows its use as a manipulator with a wide variety of end effectors and tools. The Remote Dig-It was developed to respond to the need for a low-cost, effective remediation system for use at sites containing hazardous materials. The prototype system was independently evaluated for this purpose by the Army at the Jefferson Proving Ground where it surpassed all performance goals. At the time of this writing, the Remote Dig-It system is currently the only backhoe/excavator which met the Army`s goals for remediation systems for use at hazardous waste sites and it costs a fraction of any known competing offerings.

  8. A new bee species that excavates sandstone nests.

    PubMed

    Orr, Michael C; Griswold, Terry; Pitts, James P; Parker, Frank D

    2016-09-12

    Humanity has long been fascinated by animals with apparently unfavorable lifestyles [1]. Nesting habits are especially important because they can limit where organisms live, thereby driving population, community, and even ecosystem dynamics [2]. The question arises, then, why bees nest in active termite mounds [3] or on the rim of degassing volcanoes, seemingly preferring such hardship [4]. Here, we present a new bee species that excavates sandstone nests, Anthophora (Anthophoroides) pueblo Orr (described in Supplemental Information, published with this article online), despite the challenges already inherent to desert life. Ultimately, the benefits of nesting in sandstone appear to outweigh the associated costs in this system. PMID:27623257

  9. Native American lithic procurement along the international border in the boot heel region of southwestern New Mexico

    NASA Astrophysics Data System (ADS)

    Zeigler, K. E.; Hughes, C.; Kurota, A.; Hogan, P.

    2010-12-01

    Multidisciplinary field projects can be very useful to a more fundamental understanding of the world around us, though these projects are not as common as they should be. In particular, the combination of archeology and geology combines our understanding of human behavior and human use of the landscape with an intimate knowledge of geologic processes and the materials available for human use in order to gain a broader understanding of human-Earth interaction. Here we present data from a cross-disciplinary project that uses a common dataset, archeological artifacts, to explore the anthropological and geologic implications of useage patterns. Archeological excavations and surveys conducted by the Office of Contract Archeology in 2007 along the route of the proposed international border fence reveal patterns of use of geologic materials by Archaic, Formative and Protohistoric Native Americans in the Boot Heel of southwestern New Mexico. Thousands of artifacts were recorded in multiple sites from Guadalupe Pass in the southern Peloncillo Mountains to the Carrizalillo Hills west of Columbus. We identified the lithologies of artifacts, ranging from projectile points to groundstones, and then constructed material movement maps based on either known procurement sites ("quarries") or outcrops identified as the closest source to a given site for each lithology. Not unexpectedly, the majority of the rock types utilized by native peoples are local siliceous volcanic materials. However, several artifacts constructed from obsidian were transported into the region from northern Mexico and eastern Arizona, indicating long-distance travel and/or trade routes. We also examine useage pattern difference between Archaic, Formative and Protohistoric sites. Additionally, a dramatic change in distribution of sources for geologic materials occurs between one pre-Spanish site and one post-Spanish site that are adjacent to one another.

  10. Native American lithic procurement along the international border in the boot heel region of southwestern New Mexico

    NASA Astrophysics Data System (ADS)

    Zeigler, K. E.; Hogan, P.; Hughes, C.; Kurota, A.

    2011-06-01

    Multidisciplinary field projects can be very useful to a more fundamental understanding of the world around us, though these projects are not as common as they should be. In particular, the combination of archeology and geology combines our understanding of human behavior and human use of the landscape with an intimate knowledge of geologic processes and the materials available for human use in order to gain a broader understanding of human-Earth interaction. Here we present data from a cross-disciplinary project that uses a common dataset, archeological artifacts, to explore the anthropological and geologic implications of useage patterns. Archeological excavations and surveys conducted by the Office of Contract Archeology in 2007 along the route of the proposed international border fence reveal patterns of use of geologic materials by Archaic, Formative and Protohistoric Native Americans in the Boot Heel of southwestern New Mexico. Thousands of artifacts were recorded in multiple sites from Guadalupe Pass in the southern Peloncillo Mountains to the Carrizalillo Hills west of Columbus. We identified the lithologies of artifacts, ranging from projectile points to groundstones, and then constructed material movement maps based on either known procurement sites ("quarries") or outcrops identified as the closest source to a given site for each lithology. Not unexpectedly, the majority of the rock types utilized by native peoples are local siliceous volcanic materials. However, several artifacts constructed from obsidian were transported into the region from northern Mexico and eastern Arizona, indicating long-distance travel and/or trade routes. We also examine useage pattern difference between Archaic, Formative and Protohistoric sites. Additionally, a dramatic change in distribution of sources for geologic materials occurs between one pre-Spanish site and one post-Spanish site that are adjacent to one another.

  11. Analysis of Mineral Assemblages Containing Unstable Hydrous Phases

    NASA Astrophysics Data System (ADS)

    Vaniman, D. T.; Wilson, S. A.; Bish, D. L.; Chipera, S.

    2011-12-01

    Minerals in many environments can be treated as durable phases that preserve a record of their formation. However many minerals, especially those with hydrogen-bonded H2O molecules as part of their structure, are ephemeral and are unlikely to survive disturbance let alone removal from their environment of formation. Minerals with exceptionally limited stability such as meridianiite (Mg-sulfate 11 hydrate), ikaite (Ca-carbonate 6 hydrate), and mirabilite (Na-sulfate 10 hydrate) are very susceptible to destabilization during analysis, and even modest changes in temperature or relative humidity can lead to change in hydration state or deliquescence. The result may be not only loss of the salt hydrate but dissolution of other salts present, precipitation of new phases, and ion exchange between the concentrated solution and otherwise unaffected phases. Exchange of H2O molecules can also occur in solid-vapor systems without any liquid involvement; moreover, recent work has shown that cation exchange between smectite and sulfate hydrates can occur without any liquid phase present other than a presumed thin film at the salt-silicate interface. Among hydrous silicates, clay minerals are susceptible to cation exchange and similar alteration can be expected for zeolites, palagonite, and possibly other hydrous silicate alteration products. Environmentally sensitive phases on Mars, such as meridianiite, may occur at higher latitudes or in the subsurface where permafrost may be present. Accurate determination of the presence and paragenesis of such minerals will be important for understanding the near-surface hydrogeology of Mars, and in situ analysis may be the only way to obtain this information. Access to the subsurface may be required, yet the act of exposure by excavation or drilling can itself lead to rapid degradation as the sample is exposed or brought to the surface for analysis. Mars is not the only body with which to be concerned, for similar concerns can be raised

  12. DARPA background clutter data collection experiment: excavation results

    NASA Astrophysics Data System (ADS)

    George, Vivian; Altshuler, Thomas W.; Rosen, Erik M.

    1998-09-01

    Most technologies in use or proposed for use to detect landmines and unexploded ordnance (UXO) suffer from unacceptably high false-alarm rates, even at modest probabilities of detection. High false-alarm rates are a consequence of the inability to discriminate real UXO and landmines from man-made and naturally occurring clutter. The goal of the Defense Advanced Research Project Agency (DARPA)- sponsored Background Clutter Data Collection Experiment is to provide data which will support the development of techniques that are more adept at discriminating UXO from benign, man- made objects. During the fall of 1996, high areal density site surveys were completed using the following sensor types: magnetometer, infrared, electromagnetic induction, and ground- penetrating radar. Preliminary analysis of the data confirmed that a large number of anomalies in the sensor data are visually indistinguishable from anomalies that are a result of emplaced inert UXO or landmines. The Firing Point 20 site at Fort A. P. Hill exhibits the largest number of these ordnance- like anomalies. To determine the source of a subset of these sensor response anomalies, a 1-week excavation effort was conducted. This paper presents an analysis of the data to determine the candidate locations for, the procedures used during, and the results of the excavation.

  13. Target and Projectile: Material Effects on Crater Excavation and Growth

    NASA Technical Reports Server (NTRS)

    Anderson, J. L. B.; Burleson, T.; Cintala, Mark J.

    2010-01-01

    Scaling relationships allow the initial conditions of an impact to be related to the excavation flow and final crater size and have proven useful in understanding the various processes that lead to the formation of a planetary-scale crater. In addition, they can be examined and tested through laboratory experiments in which the initial conditions of the impact are known and ejecta kinematics and final crater morphometry are measured directly. Current scaling relationships are based on a point-source assumption and treat the target material as a continuous medium; however, in planetary-scale impacts, this may not always be the case. Fragments buried in a megaregolith, for instance, could easily approach or exceed the dimensions of the impactor; rubble-pile asteroids could present similar, if not greater, structural complexity. Experiments allow exploration into the effects of target material properties and projectile deformation style on crater excavation and dimensions. This contribution examines two of these properties: (1) the deformation style of the projectile, ductile (aluminum) or brittle (soda-lime glass) and (2) the grain size of the target material, 0.5-1 mm vs. 1-3 mm sand.

  14. A study experiment of auto idle application in the excavator engine performance

    NASA Astrophysics Data System (ADS)

    Purwanto, Wawan; Maksum, Hasan; Putra, Dwi Sudarno; Azmi, Meri; Wahyudi, Retno

    2016-03-01

    The purpose of this study was to analyze the effect of applying auto idle to excavator engine performance, such as machine unitization and fuel consumption in Excavator. Steps to be done are to modify the system JA 44 and 67 in Vehicle Electronic Control Unit (V-ECU). The modifications will be obtained from the pattern of the engine speed. If the excavator attachment is not operated, the engine speed will return to the idle speed automatically. From the experiment results the auto idle reduces fuel consumption in excavator engine.

  15. Fish Assemblages of Mediterranean Marine Caves

    PubMed Central

    Bussotti, Simona; Di Franco, Antonio; Francour, Patrice; Guidetti, Paolo

    2015-01-01

    Fish assemblages associated with 14 marine caves and adjacent external rocky reefs were investigated at four Marine Protected Areas (MPAs) along the coasts of Italy. Within the caves sampling was carried out in different sub-habitats: walls, ceilings, bottoms and ends of caves. On the whole, 38 species were recorded inside the 14 caves investigated. Eighteen species were exclusively found inside the caves: they were mainly represented by speleophilic (i.e. species preferentially or exclusively inhabiting caves) gobids (e.g. Didogobius splechtnai) and nocturnal species (e.g. Conger conger). Forty-one species were censused outside, 20 of which were shared with cave habitats. Apogon imberbis was the most common fish found in all 14 caves investigated, followed by Thorogobius ephippiatus (recorded in 13 caves), and Diplodus vulgaris and Scorpaena notata (both censused in 12 caves). Distinct fish assemblages were found between external rocky reefs and the different cave sub-habitats. New data on the distribution of some speleophilic gobids were collected, showing the existence of a pool of species shared by marine caves on a large scale (i.e. hundreds of km). Considering the uniqueness of cave fishes (18 exclusive species and different assemblage structures), the inclusion of marine caves among the habitats routinely investigated for fish biodiversity monitoring could facilitate the achievement of more comprehensive inventories. Due to their contribution to local species diversity and the shelter they provide to species valuable for conservation, marine caves should be prioritized for their inclusion not only within future MPAs through the Mediterranean Sea, but also into larger management spatial planning. PMID:25875504

  16. Geophysical prospection, archaeological excavation, and dating in two Hellenic pyramids

    NASA Astrophysics Data System (ADS)

    Theocaris, P. S.; Liritzis, I.; Lagios, E.; Sampson, A.

    1996-09-01

    Geophysical prospection employing magnetometry and electromagnetic measurements has been applied in and around two small sized pyramids of Hellenikon and Ligourio in Argolid, Greece. The magnetic anomalies appropriately assessed were interpreted as possible archaeological targets. Subsequent test excavations revealed the presence of room foundations and parts of walls, as well as a plethora of ceramic ware. Typological study of the ceramics classified them to as early as the proto-Helladic period and to as late as the first centuries A.D. The earlier periods have been also confirmed by a novel application of thermoluminescence (TL) dating of ceramics and the megalithic stones themselves. The present results question earlier attempts classifying these pyramids at the Classical period and favour much earlier periods.

  17. Fish Assemblages on Estuarine Artificial Reefs: Natural Rocky-Reef Mimics or Discrete Assemblages?

    PubMed Central

    Folpp, Heath; Lowry, Michael; Gregson, Marcus; Suthers, Iain M.

    2013-01-01

    If the primary goal of artificial reef construction is the creation of additional reef habitat that is comparable to adjacent natural rocky-reef, then performance should be evaluated using simultaneous comparisons with adjacent natural habitats. Using baited remote underwater video (BRUV) fish assemblages on purpose-built estuarine artificial reefs and adjacent natural rocky-reef and sand-flat were assessed 18 months post-deployment in three south-east Australian estuaries. Fish abundance, species richness and diversity were found to be greater on the artificial reefs than on either naturally occurring reef or sand-flat in all estuaries. Comparisons within each estuary identified significant differences in the species composition between the artificial and natural rocky-reefs. The artificial reef assemblage was dominated by sparid species including Acanthopagrus australis and Rhabdosargus sarba. The preference for a range of habitats by theses sparid species is evident by their detection on sand-flat, natural rocky reef and artificial reef habitats. The fish assemblage identified on the artificial reefs remained distinct from the adjacent rocky-reef, comprising a range of species drawn from naturally occurring rocky-reef and sand-flat. In addition, some mid-water schooling species including Trachurus novaezelandiae and Pseudocaranx georgianus were only identified on the artificial reef community; presumably as result of the reef's isolated location in open-water. We concluded that estuarine artificial reef assemblages are likely to differ significantly from adjacent rocky-reef, potentially as a result of physical factors such as reef isolation, coupled with species specific behavioural traits such as the ability of some species to traverse large sand flats in order to locate reef structure, and feeding preferences. Artificial reefs should not be viewed as direct surrogates for natural reef. The assemblages are likely to remain distinct from naturally occurring

  18. Fish assemblages on estuarine artificial reefs: natural rocky-reef mimics or discrete assemblages?

    PubMed

    Folpp, Heath; Lowry, Michael; Gregson, Marcus; Suthers, Iain M

    2014-01-01

    If the primary goal of artificial reef construction is the creation of additional reef habitat that is comparable to adjacent natural rocky-reef, then performance should be evaluated using simultaneous comparisons with adjacent natural habitats. Using baited remote underwater video (BRUV) fish assemblages on purpose-built estuarine artificial reefs and adjacent natural rocky-reef and sand-flat were assessed 18 months post-deployment in three south-east Australian estuaries. Fish abundance, species richness and diversity were found to be greater on the artificial reefs than on either naturally occurring reef or sand-flat in all estuaries. Comparisons within each estuary identified significant differences in the species composition between the artificial and natural rocky-reefs. The artificial reef assemblage was dominated by sparid species including Acanthopagrus australis and Rhabdosargus sarba. The preference for a range of habitats by theses sparid species is evident by their detection on sand-flat, natural rocky reef and artificial reef habitats. The fish assemblage identified on the artificial reefs remained distinct from the adjacent rocky-reef, comprising a range of species drawn from naturally occurring rocky-reef and sand-flat. In addition, some mid-water schooling species including Trachurus novaezelandiae and Pseudocaranx georgianus were only identified on the artificial reef community; presumably as result of the reef's isolated location in open-water. We concluded that estuarine artificial reef assemblages are likely to differ significantly from adjacent rocky-reef, potentially as a result of physical factors such as reef isolation, coupled with species specific behavioural traits such as the ability of some species to traverse large sand flats in order to locate reef structure, and feeding preferences. Artificial reefs should not be viewed as direct surrogates for natural reef. The assemblages are likely to remain distinct from naturally occurring

  19. Reservoir floodplains support distinct fish assemblages

    USGS Publications Warehouse

    Miranda, Leandro E.; Wigen, S. L.; Dagel, Jonah D.

    2014-01-01

    Reservoirs constructed on floodplain rivers are unique because the upper reaches of the impoundment may include extensive floodplain environments. Moreover, reservoirs that experience large periodic water level fluctuations as part of their operational objectives seasonally inundate and dewater floodplains in their upper reaches, partly mimicking natural inundations of river floodplains. In four flood control reservoirs in Mississippi, USA, we explored the dynamics of connectivity between reservoirs and adjacent floodplains and the characteristics of fish assemblages that develop in reservoir floodplains relative to those that develop in reservoir bays. Although fish species richness in floodplains and bays were similar, species composition differed. Floodplains emphasized fish species largely associated with backwater shallow environments, often resistant to harsh environmental conditions. Conversely, dominant species in bays represented mainly generalists that benefit from the continuous connectivity between the bay and the main reservoir. Floodplains in the study reservoirs provided desirable vegetated habitats at lower water level elevations, earlier in the year, and more frequently than in bays. Inundating dense vegetation in bays requires raising reservoir water levels above the levels required to reach floodplains. Therefore, aside from promoting distinct fish assemblages within reservoirs and helping promote diversity in regulated rivers, reservoir floodplains are valued because they can provide suitable vegetated habitats for fish species at elevations below the normal pool, precluding the need to annually flood upland vegetation that would inevitably be impaired by regular flooding. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  20. 29 CFR 570.68 - Occupations in excavation operations (Order 17).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false Occupations in excavation operations (Order 17). 570.68... REGULATIONS CHILD LABOR REGULATIONS, ORDERS AND STATEMENTS OF INTERPRETATION Occupations Particularly...-Being § 570.68 Occupations in excavation operations (Order 17). (a) Finding and declaration of fact....

  1. 29 CFR 570.68 - Occupations in excavation operations (Order 17).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Occupations in excavation operations (Order 17). 570.68... REGULATIONS CHILD LABOR REGULATIONS, ORDERS AND STATEMENTS OF INTERPRETATION Occupations Particularly...-Being § 570.68 Occupations in excavation operations (Order 17). (a) Finding and declaration of fact....

  2. Analytical Solutions for Tunnels of Elliptical Cross-Section in Rheological Rock Accounting for Sequential Excavation

    NASA Astrophysics Data System (ADS)

    Wang, H. N.; Utili, S.; Jiang, M. J.; He, P.

    2015-09-01

    Time dependency in tunnel excavation is mainly due to the rheological properties of rock and sequential excavation. In this paper, analytical solutions for deeply buried tunnels with elliptical cross-section excavated in linear viscoelastic media are derived accounting for the process of sequential excavation. For this purpose, an extension of the principle of correspondence to solid media with time varying boundaries is formulated for the first time. An initial anisotropic stress field is assumed. To simulate realistically the process of tunnel excavation, solutions are developed for a time-dependent excavation process with the major and minor axes of the elliptical tunnel changing from zero until a final value according to time-dependent functions specified by the designers. In the paper, analytical expressions in integral form are obtained assuming the incompressible generalized Kelvin viscoelastic model for the rheology of the rock mass, with Maxwell and Kelvin models solved as particular cases. An extensive parametric analysis is then performed to investigate the effects of various excavation methods and excavation rates. Also the distribution of displacements and stresses in space at different times is illustrated. Several dimensionless charts for ease of use of practitioners are provided.

  3. Investigation of Hexavalent Chromium Flux to Groundwater at the 100-C-7:1 Excavation Site

    SciTech Connect

    Truex, Michael J.; Vermeul, Vincent R.; Fritz, Brad G.; Mackley, Rob D.; Horner, Jacob A.; Johnson, Christian D.; Newcomer, Darrell R.

    2012-11-16

    Deep excavation of soil has been conducted at the 100-C-7 and 100-C-7:1 waste sites within the 100-BC Operable Unit at the Department of Energy (DOE) Hanford Site to remove hexavalent chromium (Cr(VI)) contamination with the excavations reaching to near the water table. Soil sampling showed that Cr(VI) contamination was still present at the bottom of the 100-C-7:1 excavation. In addition, Cr(VI) concentrations in a downgradient monitoring well have shown a transient spike of increased Cr(VI) concentration following initiation of excavation. Potentially, the increased Cr(VI) concentrations in the downgradient monitoring well are due to Cr(VI) from the excavation site. However, data were needed to evaluate this possibility and to quantify the overall impact of the 100-C-7:1 excavation site on groundwater. Data collected from a network of aquifer tubes installed across the floor of the 100-C-7:1 excavation and from temporary wells installed at the bottom of the entrance ramp to the excavation were used to evaluate Cr(VI) releases into the aquifer and to estimate local-scale hydraulic properties and groundwater flow velocity.

  4. 18 CFR 1304.207 - Channel excavation on TVA-owned residential access shoreland.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... reservoir drawdown periods. (g) Channel excavations must be accomplished during the reservoir drawdown when the reservoir bottom is exposed and dry. (h) Spoil material from channel excavations must be placed in... Risk Profile elevation. For those reservoirs that have no flood control storage, dredge spoil must...

  5. 18 CFR 1304.207 - Channel excavation on TVA-owned residential access shoreland.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... reservoir drawdown periods. (g) Channel excavations must be accomplished during the reservoir drawdown when the reservoir bottom is exposed and dry. (h) Spoil material from channel excavations must be placed in... Risk Profile elevation. For those reservoirs that have no flood control storage, dredge spoil must...

  6. 18 CFR 1304.207 - Channel excavation on TVA-owned residential access shoreland.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... reservoir drawdown periods. (g) Channel excavations must be accomplished during the reservoir drawdown when the reservoir bottom is exposed and dry. (h) Spoil material from channel excavations must be placed in... Risk Profile elevation. For those reservoirs that have no flood control storage, dredge spoil must...

  7. Trade Study of Excavation Tools and Equipment for Lunar Outpost Development and ISRU

    NASA Astrophysics Data System (ADS)

    Mueller, R. P.; King, R. H.

    2008-01-01

    The NASA Lunar Architecture Team (LAT) has developed a candidate architecture to establish a lunar outpost that includes in-situ resource utilization (ISRU). Outpost development requires excavation for landing and launch sites, roads, trenches, foundations, radiation and thermal shielding, etc. Furthermore, ISRU requires excavation as feed stock for water processing and oxygen production plants. The design environment for lunar excavation tools and equipment including low gravity, cost of launching massive equipment, limited power, limited size, high reliability, and extreme temperatures is significantly different from terrestrial excavation equipment design environment. Consequently, the lunar application requires new approaches to developing excavation tools and equipment in the context of a systems engineering approach to building a Lunar Outpost. Several authors have proposed interesting and innovative general excavation approaches in the literature, and the authors of this paper will propose adaptations and/or new excavation concepts specific to the Lunar Outpost. The requirements for excavation from the LAT architecture will be examined and quantified with corresponding figures of merit and evaluation criteria. This paper will evaluate the proposed approaches using traditional decision making with uncertainty techniques.

  8. ZOOBENTHOS ASSEMBLAGES AS INDICATORS OF LAKE SUPERIOR COASTAL WETLAND CONDITIONS

    EPA Science Inventory

    Little is known about the diversity or structure of zoobenthos assemblages in Great Lakes coastal wetlands. As part of a comparative study in western Lake Superior we wanted to investigate whether these assemblages might be useful as indicators of wetland condition. We also wante...

  9. Genetic exchange within and between assemblages of Giardia duodenalis.

    PubMed

    Lasek-Nesselquist, Erica; Welch, David Mark; Thompson, Richard Christopher Andrew; Steuart, Robert F; Sogin, Mitchell L

    2009-01-01

    Meiotic sex evolved early in the history of eukaryotes. Giardia duodenalis (syn. Giardia lamblia, Giardia intestinalis), a parasitic protist belonging to an early diverging lineage of eukaryotes, shows no cytological or physiological evidence of meiotic or sexual processes. Recent molecular analyses challenge the idea that G. duodenalis is a strictly clonal organism by providing evidence of recombination between homologous chromosomes within one subgroup (Assemblage A) of this species as well as genetic transfer from one subgroup to another (Assemblage A-B). Because recombination is not well documented and because it is not known whether the observed inter-assemblage transfer represents true reciprocal genetic exchange or a non-sexual process, we analyzed genic sequences from all major subgroups (Assemblages A-G) of this species. For all assemblages, we detected molecular signatures consistent with meiotic sex or genetic exchange, including low levels of heterozygosity, as indicated by allelic sequence divergence within isolates, and intra- and inter-assemblage recombination. The identification of recombination between assemblages suggests a shared gene pool and calls into question whether it is appropriate to divide the genetically distinct assemblages of G. duodenalis into a species complex. PMID:19883439

  10. Here Comes the Sun ... and I Say, "It' an Assemblage"

    ERIC Educational Resources Information Center

    Skophammer, Karen

    2011-01-01

    In this article, the author discusses how she combines science lesson with a hands-on art project. She used the wonderfully creative suns shown on the Sunday edition of "The CBS Morning Show" to give the students fodder for thought. She describes how to create an assemblage. An assemblage is like a collage, but it moves past the two-dimensional…

  11. Percolation and permeability of fracture networks in Excavated Damaged Zones

    NASA Astrophysics Data System (ADS)

    Mourzenko, V.; Thovert, J.; Adler, P. M.

    2012-12-01

    Generally, the excavation process of a gallery generates fractures in its immediate vicinity. The corresponding zone which is called the Excavated Damaged Zone (EDZ), has a larger permeability than the intact surrounding medium. The properties of the EDZ are attracting more and more attention because of their potential importance in repositories of nuclear wastes. The EDZ which is induced by the excavation process may create along the galleries of the repositories a high permeability zone which could directly connect the storage area with the ground surface. Therefore, the studies of its properties are of crucial importance for applications such as the storage of nuclear wastes. Field observations (such as the ones which have been systematically performed at Mont Terri by [1, 2]) suggest that the fracture density is an exponentially decreasing function of the distance to the wall with a characteristic length of about 0.5 m and that the fracture orientation is anisotropic (most fractures are subparallel to the tunnel walls) and well approximated by a Fisher law whose pole is orthogonal to the wall. Numerical samples are generated according to these prescriptions. Their percolation status and hydraulic transmissivity can be calculated by the numerical codes which are detailed in [3]. Percolation is determined by a pseudo diffusion algorithm. Flow determination necessitates the meshing of the fracture networks and the discretisation of the Darcy equation by a finite volume technique; the resulting linear system is solved by a conjugate gradient algorithm. Only the flow properties of the EDZ along the directions which are parallel to the wall are of interest when a pressure gradient parallel to the wall is applied. The transmissivity T which relates the total flow rate per unit width Q along the wall through the whole EDZ to the pressure gradient grad p, is defined by Q = - T grad p/mu where mu is the fluid viscosity. The percolation status and hydraulic transmissivity

  12. Rock mass characterisation and stability analyses of excavated slopes

    NASA Astrophysics Data System (ADS)

    Zangerl, Christian; Lechner, Heidrun

    2016-04-01

    Excavated slopes in fractured rock masses are frequently designed for open pit mining, quarries, buildings, highways, railway lines, and canals. These slopes can reach heights of several hundreds of metres and in cases concerning open pit mines slopes larger than 1000 m are not uncommon. Given that deep-seated slope failures can cause large damage or even loss of life, the slope design needs to incorporate sufficient stability. Thus, slope design methods based on comprehensive approaches need to be applied. Excavation changes slope angle, groundwater flow, and blasting increases the degree of rock mass fracturing as well as rock mass disturbance. As such, excavation leads to considerable stress changes in the slopes. Generally, slope design rely on the concept of factor of safety (FOS), often a requirement by international or national standards. A limitation of the factor of safety is that time dependent failure processes, stress-strain relationships, and the impact of rock mass strain and displacement are not considered. Usually, there is a difficulty to estimate the strength of the rock mass, which in turn is controlled by an interaction of intact rock and discontinuity strength. In addition, knowledge about in-situ stresses for the failure criterion is essential. Thus, the estimation of the state of stress of the slope and the strength parameters of the rock mass is still challenging. Given that, large-scale in-situ testing is difficult and costly, back-calculations of case studies in similar rock types or rock mass classification systems are usually the methods of choice. Concerning back-calculations, often a detailed and standardised documentation is missing, and a direct applicability to new projects is not always given. Concerning rock mass classification systems, it is difficult to consider rock mass anisotropy and thus the empirical estimation of the strength properties possesses high uncertainty. In the framework of this study an approach based on

  13. RNA assemblages orchestrate complex cellular processes.

    PubMed

    Nielsen, Finn Cilius; Hansen, Heidi Theil; Christiansen, Jan

    2016-07-01

    Eukaryotic mRNAs are monocistronic, and therefore mechanisms exist that coordinate the synthesis of multiprotein complexes in order to obtain proper stoichiometry at the appropriate intracellular locations. RNA-binding proteins containing low-complexity sequences are prone to generate liquid droplets via liquid-liquid phase separation, and in this way create cytoplasmic assemblages of functionally related mRNAs. In a recent iCLIP study, we showed that the Drosophila RNA-binding protein Imp, which exhibits a C-terminal low-complexity sequence, increases the formation of F-actin by binding to 3' untranslated regions of mRNAs encoding components participating in F-actin biogenesis. We hypothesize that phase transition is a mechanism the cell employs to increase the local mRNA concentration considerably, and in this way synchronize protein production in cytoplasmic territories, as discussed in the present review. PMID:27172226

  14. Phylogenetic and functional diversity in large carnivore assemblages.

    PubMed

    Dalerum, F

    2013-06-01

    Large terrestrial carnivores are important ecological components and prominent flagship species, but are often extinction prone owing to a combination of biological traits and high levels of human persecution. This study combines phylogenetic and functional diversity evaluations of global and continental large carnivore assemblages to provide a framework for conservation prioritization both between and within assemblages. Species-rich assemblages of large carnivores simultaneously had high phylogenetic and functional diversity, but species contributions to phylogenetic and functional diversity components were not positively correlated. The results further provide ecological justification for the largest carnivore species as a focus for conservation action, and suggests that range contraction is a likely cause of diminishing carnivore ecosystem function. This study highlights that preserving species-rich carnivore assemblages will capture both high phylogenetic and functional diversity, but that prioritizing species within assemblages will involve trade-offs between optimizing contemporary ecosystem function versus the evolutionary potential for future ecosystem performance. PMID:23576787

  15. Meiofaunal assemblages associated with native and non-indigenous macroalgae

    NASA Astrophysics Data System (ADS)

    Veiga, Puri; Sousa-Pinto, Isabel; Rubal, Marcos

    2016-07-01

    Meiofauna is a useful tool to detect effects of different disturbances; however, its relevance in the frame of biological invasions has been almost fully neglected. Meiofaunal assemblages associated with the invasive macroalga Sargassum muticum were studied and compared with those associated with two native macroalgae (Bifurcaria bifurcata and Chondrus crispus). We used a linear mixed model to determine the influence of habitat size (i.e. macroalgal biomass) in shaping meiofaunal assemblages. Results showed that habitat size (i.e. macroalgal biomass) shaped meiofaunal assemblages influencing its abundance, richness and structure. However, the identity of macroalga (i.e. species) appears also to play a significant role, particularly the differences of complexity among the studied species may shape their meiofaunal assemblages. Finally, the invasive macroalga appears to influence positively species richness. Our results highlight the need of including different faunal components to achieve a comprehensive knowledge on effects of invasive macroalgae and that meiofaunal assemblages may be a valuable tool to examine them.

  16. Molluscan subfossil assemblages reveal the long-term deterioration of coral reef environments in Caribbean Panama.

    PubMed

    Cramer, Katie L; Leonard-Pingel, Jill S; Rodríguez, Félix; Jackson, Jeremy B C

    2015-07-15

    Caribbean reef corals have declined sharply since the 1980s, but the lack of prior baseline data has hindered identification of drivers of change. To assess anthropogenic change in reef environments over the past century, we tracked the composition of subfossil assemblages of bivalve and gastropod mollusks excavated from pits below lagoonal and offshore reefs in Bocas del Toro, Panama. The higher prevalence of (a) infaunal suspension-feeding bivalves and herbivorous and omnivorous gastropods in lagoons and (b) epifaunal and suspension-feeding bivalves and carnivorous and suspension-feeding gastropods offshore reflected the greater influence of land-based nutrients/sediments within lagoons. Temporal changes indicated deteriorating environmental conditions pre-1960 in lagoons and post-1960 offshore, with offshore communities becoming more similar to lagoonal ones since 1960. Relative abundances of dominant bivalve species tracked those of their coral hosts, revealing broader ecosystem effects of coral community change. The nature and timing of changes implicate land-based runoff in reef deterioration. PMID:26031382

  17. Short-term effects of small dam removal on freshwater mussel assemblage

    USGS Publications Warehouse

    Heise, Ryan J.; Cope, W. Gregory; Kwak, Thomas J.; Eads, Chris B.

    2013-01-01

    Dam removal is increasingly used to restore lotic habitat and biota, but its effects on freshwater mussels (family Unionidae) are not well known. We conducted a four-year study to assess short-term effects on mussels after removal of a small hydropower dam on the Deep River (Cape Fear River drainage), North Carolina, USA, in 2006. We conducted annual pre- and post-removal monitoring of mussel density, richness, and survival (post removal only) with transect surveys and quadrat excavation, and assessed changes in substrate composition at two impact sites (tailrace and impoundment) and two reference sites. Before-after-control-impact (BACI) analyses of variance did not detect a significant change in mussel density (total or individually for the three most abundant species), species richness, Eastern Elliptio (Elliptio complanata) mean length, or substrate composition in the tailrace or drained impoundment following dam removal. Apparent annual survival estimates of Eastern Elliptio at the tailrace site did not differ among sampling periods and were similar to control sites. We observed minimal mussel mortality from stranding in the dewatered reservoir. These results demonstrate that adverse short-term impacts of dam removal on downstream mussel assemblages can be minimized with appropriate planning, timing, and removal techniques, but additional monitoring is warranted to determine long-term effects on mussels within the restored river reach.

  18. SLOPE STABILITY EVALUATION AND EQUIPMENT SETBACK DISTANCES FOR BURIAL GROUND EXCAVATIONS

    SciTech Connect

    MCSHANE DS

    2010-03-25

    After 1970 Transuranic (TRU) and suspect TRU waste was buried in the ground with the intention that at some later date the waste would be retrieved and processed into a configuration for long term storage. To retrieve this waste the soil must be removed (excavated). Sloping the bank of the excavation is the method used to keep the excavation from collapsing and to provide protection for workers retrieving the waste. The purpose of this paper is to document the minimum distance (setback) that equipment must stay from the edge of the excavation to maintain a stable slope. This evaluation examines the equipment setback distance by dividing the equipment into two categories, (1) equipment used for excavation and (2) equipment used for retrieval. The section on excavation equipment will also discuss techniques used for excavation including the process of benching. Calculations 122633-C-004, 'Slope Stability Analysis' (Attachment A), and 300013-C-001, 'Crane Stability Analysis' (Attachment B), have been prepared to support this evaluation. As shown in the calculations the soil has the following properties: Unit weight 110 pounds per cubic foot; and Friction Angle (natural angle of repose) 38{sup o} or 1.28 horizontal to 1 vertical. Setback distances are measured from the top edge of the slope to the wheels/tracks of the vehicles and heavy equipment being utilized. The computer program utilized in the calculation uses the center of the wheel or track load for the analysis and this difference is accounted for in this evaluation.

  19. Focal choroidal excavation in patients with central serous chorioretinopathy

    PubMed Central

    Luk, F O J; Fok, A C T; Lee, A; Liu, A T W; Lai, T Y Y

    2015-01-01

    Purpose To evaluate the prevalence and clinical features of focal choroidal excavation (FCE) in patients presenting with central serous chorioretinopathy (CSC). Methods This is a retrospective consecutive case series of consecutive patients with CSC who were referred for spectral domain optical coherence tomography (SD-OCT) between January 2010 and December 2011. Medical records were reviewed and clinical features including presence of FCE in SD-OCT, fluorescence angiography (FA), and indocyanine green angiography (ICGA) were studied. Results Among the 116 CSC patients assessed, FCE was found in 11 eyes of 7 (6.0%) patients. FCE was associated with subretinal fluid in six eyes of six patients and serous pigment epithelial detachment in three eyes of two patients. The mean central subfield retinal thickness of CSC eyes with FCE was 283.7 μm, compared with 377.5 μm for CSC eyes without FCE (Mann–Whitney U-test, P=0.020). Five FCE eyes of five patients had focal leakage on FA. Choroidal hyperpermeability on ICGA was found in seven CSC eyes with FCE, with four eyes showing hypofluorescent spot corresponding to the FCE. After a mean follow-up of 16 months, visual acuity of all 11 eyes with FCE remained stable or improved at the last follow-up. Conclusion FCE is not an uncommon feature in patients with CSC and might be associated with choroidal hemodynamic disturbances. PMID:25853402

  20. Oxymonads are closely related to the excavate taxon Trimastix.

    PubMed

    Dacks, J B; Silberman, J D; Simpson, A G; Moriya, S; Kudo, T; Ohkuma, M; Redfield, R J

    2001-06-01

    Despite intensive study in recent years, large-scale eukaryote phylogeny remains poorly resolved. This is particularly problematic among the groups considered to be potential early branches. In many recent systematic schemes for early eukaryotic evolution, the amitochondriate protists oxymonads and Trimastix have figured prominently, having been suggested as members of many of the putative deep-branching higher taxa. However, they have never before been proposed as close relatives of each other. We amplified, cloned, and sequenced small-subunit ribosomal RNA genes from the oxymonad Pyrsonympha and from several Trimastix isolates. Rigorous phylogenetic analyses indicate that these two protist groups are sister taxa and are not clearly related to any currently established eukaryotic lineages. This surprising result has important implications for our understanding of cellular evolution and high-level eukaryotic phylogeny. Given that Trimastix contains small, electron-dense bodies strongly suspected to be derived mitochondria, this study constitutes the best evidence to date that oxymonads are not primitively amitochondriate. Instead, Trimastix and oxymonads may be useful organisms for investigations into the evolution of the secondary amitochondriate condition. All higher taxa involving either oxymonads or Trimastix may require modification or abandonment. Affected groups include four contemporary taxa given the rank of phylum (Metamonada, Loukozoa, Trichozoa, Percolozoa), and the informal excavate taxa. A new "phylum-level" taxon may be warranted for oxymonads and Trimastix. PMID:11371592

  1. Heavily-hydrated lithic clasts in CH chondrites and the related, metal-rich chondrites Queen Alexandra Range 94411 and Hammadah al Hamra 237

    NASA Astrophysics Data System (ADS)

    Greshake, A.; Krot, A. N.; Meibom, A.; Weisberg, M. K.; Zolensky, M. E.; Keil, K.

    2002-02-01

    Fine-grained, heavily-hydrated lithic clasts in the metal-rich (CB) chondrites Queen Alexandra Range (QUE) 94411 and Hammadah al Hamra 237 and CH chondrites, such as Patuxent Range (PAT) 91546 and Allan Hills (ALH) 85085, are mineralogically similar suggesting genetic relationship between these meteorites. These clasts contain no anhydrous silicates and consist of framboidal and platelet magnetite, prismatic sulfides (pentlandite and pyrrhotite), and Fe-Mn-Mg-bearing Ca-carbonates set in a phyllosilicate-rich matrix. Two types of phyllosilicates were identified: serpentine, with basal spacing of ?0.73 nm, and saponite, with basal spacings of about 1.1-1.2 nm. Chondrules and FeNi-metal grains in CB and CH chondrites are believed to have formed at high temperature (>1300 K) by condensation in a solar nebula region that experienced complete vaporization. The absence of aqueous alteration of chondrules and metal grains in CB and CH chondrites indicates that the clasts experienced hydration in an asteroidal setting prior to incorporation into the CH and CB parent bodies. The hydrated clasts were either incorporated during regolith gardening or accreted together with chondrules and FeNi-metal grains after these high-temperature components had been transported from their hot formation region to a much colder region of the solar nebula.

  2. Past equable climates, mixed assemblages, and the regression fallacy

    SciTech Connect

    Cole, K.L. )

    1994-06-01

    Equable climates are often invoked to account for Pleistocene mixed (disharmonious) assemblages of plants or animals. However, mixed assemblages are defined by comparison with only modern distributions. Many modern assemblages, such as the western ponderosa pine and the northern hardwoods forests, are mixed assemblages when compared to Pleistocene distributions. Thus, explaining past assemblages with no modern analog by invoking a past equable climate ignores the fact that many modern assemblages have no past analog, yet the modern climate is not considered equable. This logical error is analogous to the regression fallacy in statistics. A change in the variability within assemblages through time cannot be detected if only the presence (and not the absence) of extreme species are considered. Because species also respond to historical and other non-climatic variables, interpretations will inevitably be biased toward equable paleoclimates. A more direct approach is to count those species that presently reside in equable climatic zones. If the species typical of modern equable zones are absent, then the proposed equable paleoclimate becomes tenuous.

  3. A Fish Assemblage from the Middle Eocene from Libya (Dur At-Talah) and the Earliest Record of Modern African Fish Genera.

    PubMed

    Otero, Olga; Pinton, Aurélie; Cappetta, Henri; Adnet, Sylvain; Valentin, Xavier; Salem, Mustapha; Jaeger, Jean-Jacques

    2015-01-01

    In the early nineteen sixties, Arambourg and Magnier found some freshwater fish (i.e., Polypterus sp., Siluriformes indet. and Lates sp.) mixed with marine members in an Eocene vertebrate assemblage at Gebel Coquin, in the southern Libyan Desert. This locality, aged ca 37-39Ma and now known under the name of Dur At-Talah, has been recently excavated. A new fish assemblage, mostly composed of teeth, was collected by the Mission Paléontologique Franco-Libyenne. In this paper, we describe freshwater fish members including a dipnoan (Protopterus sp.), and several actinopterygians: bichir (Polypterus sp.), aba fish (Gymnarchus sp.), several catfishes (Chrysichthys sp. and a mochokid indet.), several characiforms (including the tiger fish Hydrocynus sp., and one or two alestin-like fish), and perciforms (including the snake-head fish Parachanna sp. and at least one cichlid). Together with the fossiliferous outcrops at Birket Qarun in Egypt, the Libyan site at Dur At-Talah reduces a 10-Ma chronological gap in the fossil record of African freshwater fish. Their fish assemblages overlap in their composition and thus constitute a rather homogenous, original and significant amount of new elements regarding the Paleogene African ichthyofauna. This supports the establishment of the modern African freshwater fish fauna during this time period because these sites mostly contain the earliest members known in modern genera. PMID:26674637

  4. A Fish Assemblage from the Middle Eocene from Libya (Dur At-Talah) and the Earliest Record of Modern African Fish Genera

    PubMed Central

    Otero, Olga; Pinton, Aurélie; Cappetta, Henri; Adnet, Sylvain; Valentin, Xavier; Salem, Mustapha; Jaeger, Jean-Jacques

    2015-01-01

    In the early nineteen sixties, Arambourg and Magnier found some freshwater fish (i.e., Polypterus sp., Siluriformes indet. and Lates sp.) mixed with marine members in an Eocene vertebrate assemblage at Gebel Coquin, in the southern Libyan Desert. This locality, aged ca 37–39Ma and now known under the name of Dur At-Talah, has been recently excavated. A new fish assemblage, mostly composed of teeth, was collected by the Mission Paléontologique Franco-Libyenne. In this paper, we describe freshwater fish members including a dipnoan (Protopterus sp.), and several actinopterygians: bichir (Polypterus sp.), aba fish (Gymnarchus sp.), several catfishes (Chrysichthys sp. and a mochokid indet.), several characiforms (including the tiger fish Hydrocynus sp., and one or two alestin-like fish), and perciforms (including the snake-head fish Parachanna sp. and at least one cichlid). Together with the fossiliferous outcrops at Birket Qarun in Egypt, the Libyan site at Dur At-Talah reduces a 10-Ma chronological gap in the fossil record of African freshwater fish. Their fish assemblages overlap in their composition and thus constitute a rather homogenous, original and significant amount of new elements regarding the Paleogene African ichthyofauna. This supports the establishment of the modern African freshwater fish fauna during this time period because these sites mostly contain the earliest members known in modern genera. PMID:26674637

  5. 'Domestic' origin of opaque assemblages in refractory inclusions in meteorites

    NASA Technical Reports Server (NTRS)

    Blum, Joel D.; Wasserburg, G. J.; Hutcheon, Ian D.; Beckett, John R.; Stolper, Edward M.

    1988-01-01

    Experimental studies indicate that opaque assemblages rich in refractory siderophile elements were formed within host calcium- and aluminum-rich inclusions (CAIs) by exsolution, oxidation and sulphidization of homogeneous alloys, rather than by aggregation of materials in the solar nebula before the formation of CAIs. These opaque assemblages are thus not the oldest known solid materials, as was once thought, and they do not constrain processes in the early solar nebula before CAI formation. Instead, the assemblages record the changing oxygen fugacity experienced by CAIs during slow cooling in nebular and/or planetary environments.

  6. 'Domestic' origin of opaque assemblages in refractory inclusions in meteorites

    NASA Astrophysics Data System (ADS)

    Blum, J. D.; Wasserburg, G. J.; Hutcheon, I. D.; Beckett, J. R.; Stolper, E. M.

    1988-02-01

    Experimental studies indicate that opaque assemblages rich in refractory siderophile elements were formed within host calcium- and aluminium-rich inclusions (CAIs) by exsolution, oxidation and sulphidization of homogeneous alloys, rather than by aggregation of materials in the solar nebula before the formation of CAIs. These opaque assemblages are thus not the oldest known solid materials, as was once thought, and they do not constrain processes in the early solar nebula before CAI formation. Instead, the assemblages record the changing oxygen fugacity experienced by CAIs during slow cooling in nebular and/or planetary environments.

  7. Assemblages: Functional units formed by cellular phase separation

    PubMed Central

    Wright, Peter E.

    2014-01-01

    The partitioning of intracellular space beyond membrane-bound organelles can be achieved with collections of proteins that are multivalent or contain low-complexity, intrinsically disordered regions. These proteins can undergo a physical phase change to form functional granules or other entities within the cytoplasm or nucleoplasm that collectively we term “assemblage.” Intrinsically disordered proteins (IDPs) play an important role in forming a subset of cellular assemblages by promoting phase separation. Recent work points to an involvement of assemblages in disease states, indicating that intrinsic disorder and phase transitions should be considered in the development of therapeutics. PMID:25179628

  8. ISRU System Model Tool: From Excavation to Oxygen Production

    NASA Technical Reports Server (NTRS)

    Santiago-Maldonado, Edgardo; Linne, Diane L.

    2007-01-01

    In the late 80's, conceptual designs for an in situ oxygen production plant were documented in a study by Eagle Engineering [1]. In the "Summary of Findings" of this study, it is clearly pointed out that: "reported process mass and power estimates lack a consistent basis to allow comparison." The study goes on to say: "A study to produce a set of process mass, power, and volume requirements on a consistent basis is recommended." Today, approximately twenty years later, as humans plan to return to the moon and venture beyond, the need for flexible up-to-date models of the oxygen extraction production process has become even more clear. Multiple processes for the production of oxygen from lunar regolith are being investigated by NASA, academia, and industry. Three processes that have shown technical merit are molten regolith electrolysis, hydrogen reduction, and carbothermal reduction. These processes have been selected by NASA as the basis for the development of the ISRU System Model Tool (ISMT). In working to develop up-to-date system models for these processes NASA hopes to accomplish the following: (1) help in the evaluation process to select the most cost-effective and efficient process for further prototype development, (2) identify key parameters, (3) optimize the excavation and oxygen production processes, and (4) provide estimates on energy and power requirements, mass and volume of the system, oxygen production rate, mass of regolith required, mass of consumables, and other important parameters. Also, as confidence and high fidelity is achieved with each component's model, new techniques and processes can be introduced and analyzed at a fraction of the cost of traditional hardware development and test approaches. A first generation ISRU System Model Tool has been used to provide inputs to the Lunar Architecture Team studies.

  9. PERSPECTIVE VIEW OF EAST (FRONT) ELEVATION DURING EXCAVATION OF 18TH ...

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

    PERSPECTIVE VIEW OF EAST (FRONT) ELEVATION DURING EXCAVATION OF 18TH CENTURY BASEMENT ENTRY WELL AND DRAINAGE SYSTEM, LOOKING NORTHWEST - Belair, Tulip Grove Drive, Belair-at-Bowie, Bowie, Prince George's County, MD

  10. Initial energy partitioning and some excavation stage phenomenology in laboratory-scale cratering calculations in clay

    NASA Technical Reports Server (NTRS)

    Austin, M. G.; Thomsen, J. M.; Ruhl, S. F.

    1982-01-01

    One impact and two explosive cratering calculations have been analyzed with emphasis on the early excavation stage. The early excavation stage is here defined as that part of the excavation stage that occurs after energy partitioning is 90% complete, but before the cratering flow field can be well described by Z-type flow fields with values of Z uniformly greater than two. Impact generated flow fields seem to have a much longer early excavation stage than explosion generated flow fields, due possibly to the slower momentum transfer versus energy transfer rate between projectile and target. During this time when the projectile retains a significant portion of its original momentum, Z values less than two are observed in the impact generated flow field. Z values less than two are not observed at any time in the explosion generated flow fields.

  11. Performance predictions for mechanical excavators in Yucca Mountain tuffs; Yucca Mountain Site Characterization Project

    SciTech Connect

    Ozdemir, L.; Gertsch, L.; Neil, D.; Friant, J.

    1992-09-01

    The performances of several mechanical excavators are predicted for use in the tuffs at Yucca Mountain: Tunnel boring machines, the Mobile Miner, a roadheader, a blind shaft borer, a vertical wheel shaft boring machine, raise drills, and V-Moles. Work summarized is comprised of three parts: Initial prediction using existing rock physical property information; Measurement of additional rock physical properties; and Revision of the initial predictions using the enhanced database. The performance predictions are based on theoretical and empirical relationships between rock properties and the forces-experienced by rock cutters and bits during excavation. Machine backup systems and excavation design aspects, such as curves and grades, are considered in determining excavator utilization factors. Instanteous penetration rate, advance rate, and cutter costs are the fundamental performance indicators.

  12. Energy-Saving Analysis of Hydraulic Hybrid Excavator Based on Common Pressure Rail

    PubMed Central

    Jiang, Jihai; Su, Xiaoyu

    2013-01-01

    Energy-saving research of excavators is becoming one hot topic due to the increasing energy crisis and environmental deterioration recently. Hydraulic hybrid excavator based on common pressure rail (HHEC) provides an alternative with electric hybrid excavator because it has high power density and environment friendly and easy to modify based on the existing manufacture process. This paper is focused on the fuel consumption of HHEC and the actuator dynamic response to assure that the new system can save energy without sacrificing performance. Firstly, we introduce the basic principle of HHEC; then, the sizing process is presented; furthermore, the modeling period which combined mathematical analysis and experiment identification is listed. Finally, simulation results show that HHEC has a fast dynamic response which can be accepted in engineering and the fuel consumption can be reduced 21% to compare the original LS excavator and even 32% after adopting another smaller engine. PMID:24194683

  13. SIDE ELEVATION, CATERPILLAR 245B SERIES II HYDRAULIC EXCAVATOR ('OR BACKHOE') ...

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

    SIDE ELEVATION, CATERPILLAR 245B SERIES II HYDRAULIC EXCAVATOR ('OR BACKHOE') USED FOR LOADING AND MOVING EXTRACTED STONE. - Wade Sand & Gravel Company, North Quarry, State Highway 78, Thomas, Jefferson County, AL

  14. Excavated Cubic Platinum-Tin Alloy Nanocrystals Constructed from Ultrathin Nanosheets with Enhanced Electrocatalytic Activity.

    PubMed

    Chen, Qiaoli; Yang, Yanan; Cao, Zhenming; Kuang, Qin; Du, Guifen; Jiang, Yaqi; Xie, Zhaoxiong; Zheng, Lansun

    2016-07-25

    Excavated polyhedral noble-metal materials that were built by the orderly assembly of ultrathin nanosheets have both large surface areas and well-defined facets, and therefore could be promising candidates for diverse important applications. In this work, excavated cubic Pt-Sn alloy nanocrystals (NCs) with {110} facets were constructed from twelve nanosheets by a simple co-reduction method with the assistance of the surface regulator polyvinylpyrrolidone. The specific surface area of the excavated cubic Pt-Sn NCs is comparable to that of commercial Pt black despite their larger particle size. The excavated cubic Pt-Sn NCs exhibited superior electrocatalytic activity in terms of both the specific area current density and the mass current density towards methanol oxidation. PMID:27325395

  15. Lymphatic endothelial lineage assemblage during corneal lymphangiogenesis.

    PubMed

    Connor, Alicia L; Kelley, Philip M; Tempero, Richard M

    2016-03-01

    Postnatal inflammatory lymphangiogenesis presumably requires precise regulatory processes to properly assemble proliferating lymphatic endothelial cells (LECs). The specific mechanisms that regulate the assembly of LECs during new lymphatic vessel synthesis are unclear. Dynamic endothelial shuffling and rearrangement has been proposed as a mechanism of blood vessel growth. We developed genetic lineage-tracing strategies using an inductive transgenic technology to track the fate of entire tandem dimer tomato-positive (tdT) lymphatic vessels or small, in some cases clonal, populations of LECs. We coupled this platform with a suture-induced mouse model of corneal lymphangiogenesis and used different analytic microscopy techniques including serial live imaging to study the spatial properties of proliferating tdT(+) LEC progenies. LEC precursors and their progeny expanded from the corneal limbal lymphatic vessel and were assembled contiguously to comprise a subunit within a new lymphatic vessel. VE-cadherin blockade induced morphologic abnormalities in newly synthesized lymphatic vessels, but did not disrupt the tdT(+) lymphatic endothelial lineage assembly. Analysis of this static and dynamic data based largely on direct in vivo observations supports a model of lymphatic endothelial lineage assemblage during corneal inflammatory lymphangiogenesis. PMID:26658452

  16. Faceless sex: glory holes and sexual assemblages.

    PubMed

    Holmes, Dave; O'Byrne, Patrick; Murray, Stuart J

    2010-10-01

    According to our previous research, the use of glory holes in public venues such as saunas and bathhouses is very popular. The popularity of glory holes is due in part to the anonymous sex that these architectural elements allow. This post-structuralist theoretical reflection seeks to understand the specific nature of anonymous public sex among bathhouse patrons, focusing on the links between desire-architecture-place-sexual practices. Drawing on interviews with glory hole users gathered during an ethnographic research project in bathhouses, this essay goes beyond traditional public health discourse to offer an original perspective on anonymous public sex. Utilizing the philosophy of Deleuze and Guattari's concepts of assemblages and machines, we re-theorize glory hole sex--what we call 'faceless sex'--and rethink the ways that desire is imbricated with our understanding of architecture, place, and public. Finally, we reflect upon the particular ethical challenges that are posed by these particular sexual practices, and ask whether a post-structuralist ethic might be possible. PMID:20840136

  17. Geographical assemblages of European raptors and owls

    NASA Astrophysics Data System (ADS)

    López-López, Pascual; Benavent-Corai, José; García-Ripollés, Clara

    2008-09-01

    In this work we look for geographical structure patterns in European raptors (Order: Falconiformes) and owls (Order: Strigiformes). For this purpose we have conducted our research using freely available tools such as statistical software and databases. To perform the study, presence-absence data for the European raptors and owl species (Class Aves) were downloaded from the BirdLife International website. Using the freely available "pvclust" R-package, we applied similarity Jaccard index and cluster analysis in order to delineate biogeographical relationships for European countries. According to the cluster of similarity, we found that Europe is structured into two main geographical assemblages. The larger length branch separated two main groups: one containing Iceland, Greenland and the countries of central, northern and northwestern Europe, and the other group including the countries of eastern, southern and southwestern Europe. Both groups are divided into two main subgroups. According to our results, the European raptors and owls could be considered structured into four meta-communities well delimited by suture zones defined by Remington (1968) [Remington, C.L., 1968. Suture-zones of hybrid interaction between recently joined biotas. Evol. Biol. 2, 321-428]. Climatic oscillations during the Quaternary Ice Ages could explain at least in part the modern geographical distribution of the group.

  18. Lymphatic endothelial lineage assemblage during corneal lymphangiogenesis

    PubMed Central

    Connor, Alicia L.; Kelley, Philip M.; Tempero, Richard M.

    2015-01-01

    Post natal inflammatory lymphangiogenesis presumably requires precise regulatory processes to properly assemble proliferating lymphatic endothelial cells (LECs). The specific mechanisms that regulate the assembly of LECs during new lymphatic vessel synthesis are unclear. Dynamic endothelial shuffling and rearrangement has been proposed as a mechanism of blood vessel growth. We developed genetic lineage tracing strategies using an inductive transgenic technology to track the fate of entire tandem dimer tomato positive (tdT) lymphatic vessels or small, in some cases clonal, populations of LECs. We coupled this platform with a suture induced mouse model of corneal lymphangiogenesis and used different analytic microscopy techniques including serial live imaging to study the spatial properties of proliferating tdT+ LEC progenies. LEC precursors and their progeny expanded from the corneal limbal lymphatic vessel and were assembled contiguously to comprise a subunit within a new lymphatic vessel. VE-cadherin blockade induced morphologic abnormalities in newly synthesized lymphatic vessels, but did not disrupt the tdT+ lymphatic endothelial lineage assembly. Analysis of this static and dynamic data based largely on direct in vivo observations supports a model of lymphatic endothelial lineage assemblage during corneal inflammatory lymphangiogenesis. PMID:26658452

  19. Bacterial Plasmids in Antarctic Natural Microbial Assemblages

    PubMed Central

    Kobori, Hiromi; Sullivan, Cornelius W.; Shizuya, Hiroaki

    1984-01-01

    Samples of psychrophilic and psychrotrophic bacteria were collected from sea ice, seawater, sediments, and benthic or ice-associated animals in McMurdo Sound, Antarctica. A total of 155 strains were isolated and tested for the presence of plasmids by DNA agarose gel electrophoresis. Thirty-one percent of the isolates carried at least one kind of plasmid. Bacterial isolates taken from sediments showed the highest plasmid incidence (42%), and isolates from seawater showed the lowest plasmid incidence (20%). Plasmids were significantly more frequent in the strains which had been first isolated from low-nutrient media (46%) than in the strains which had been isolated from high-nutrient media (25%). Multiple forms of plasmids were observed in two-thirds of the plasmid-carrying strains. A majority of the plasmids detected were estimated to have a mass of 10 megadaltons or less. Among 48 plasmid-carrying strains, 7 showed antibiotic resistance. It is concluded that bacterial plasmids are ubiquitous in natural microbial assemblages of the pristine marine ecosystem of Antarctica. Images PMID:16346621

  20. Controlled drill & blast excavation at AECL`s Underground Research Laboratory

    SciTech Connect

    Kuzyk, G.W.; Onagi, D.P.; Thompson, P.M.

    1996-12-01

    A controlled drill and blast method has been developed and used to excavate the Underground Research Laboratory, a geotechnical facility constructed by Atomic Energy of Canada Limited (AECL) in crystalline rock. It has been demonstrated that the method can effectively reduce the excavation disturbed zone (EDZ) and is suitable for the construction of a used fuel disposal vault in the plutonic rock of the Canadian Shield.

  1. A Study on the Vibration Frequency of Blasting Excavation in Highly Stressed Rock Masses

    NASA Astrophysics Data System (ADS)

    Yang, Jianhua; Lu, Wenbo; Jiang, Qinghui; Yao, Chi; Jiang, Shuihua; Tian, Lin

    2016-07-01

    During blasting excavation in deep-buried tunnels and mines characterized by high in situ stress, the rock vibration is attributed not only to blast loading, but also to dynamic unloading caused by transient release of the in situ stress on excavation faces in the process of rock fragmentation by blasting. Understanding the vibration frequency characteristics under these two excitation sources is of important signification to determine appropriate vibration threshold limits for structure damage in deep-buried opening excavations. With a theoretical model developed for a deep-buried circular tunnel excavation by the millisecond delay blasting sequence, frequency characteristics and their influence factors are investigated and discussed for the vibrations induced by the blast loading, the dynamic unloading and the combined effects, respectively. The results show that the rising time of blast loading, the duration of dynamic unloading and the dimension of excavation boundaries are the main factors that affect the vibration frequency of blasting excavation in highly stressed rock masses. It is found that, the blast loading with a much shorter rising time accentuates higher vibration frequency than the dynamic unloading with a long duration, and it causes the blast loading vibration to be more readily attenuated as the propagation distance increases. Thus, the unloading vibration may become the main vibration component at far distances where its low-frequency vibration may exceed the vibration limits. The vibration induced by the combined effects has two distinctly dominant frequency bands corresponding to the two vibration excitation sources. The frequency analyses of the vibration records from two underground projects excavated by blasting are presented to demonstrate this finding. The findings of this study also clearly reveal that, reducing the dimension of excavation boundaries is one of the most effective means to prevent the vibrational damage to structures as it

  2. Conceptual design of equipment to excavate and transport regolith from the lunar maria

    NASA Technical Reports Server (NTRS)

    Detwiler, Mark; Foong, Chee Seng; Stocklin, Catherine

    1990-01-01

    NASA hopes to have a manned lunar outpost completed by 2005. In order to establish the base, regolith must be excavated from the lunar surface. Regolith will be used as a source for life-supporting elements and as radiation shielding for the lunar outpost. The design team from the University of Texas at Austin designed excavation and transportation equipment for initial operations of the lunar base. The design team also characterized the elements to be found in the regolith and determined the power required to excavate regolith. The characterization of the soil was based on a literature review of lunar geography. Power requirements for excavation were developed by adapting terrestrial equations for excavation power requirements and adapting them to lunar soil conditions. The design of the excavation and transportation equipment was broken into three functions: loosing, collecting, and transporting. A scarifier was selected to loosen, a bucket was selected to collect, and a load-haul system was selected to transport. The functions are powered by a modular fuel cell powered vehicle that provides power for motion of the equipment.

  3. Monitoring the excavation damaged zone by three-dimensional reconstruction of electrical resistivity

    NASA Astrophysics Data System (ADS)

    Lesparre, Nolwenn; Gibert, Dominique; Nicollin, Florence; Nussbaum, Christophe; Adler, Andy

    2013-11-01

    A damaged zone is formed during the excavation of underground galleries, altering the rock properties. From a perspective of nuclear waste storage in deep geological sites, there is a clear interest to monitor the rock properties in such zones. We constructed electrical resistivity tomograms as a function of time to monitor the damaged area in gallery 04 of the Mont Terri underground rock laboratory (Switzerland). Measurements were performed using electrode rings surrounding the gallery. The experience showed a heterogeneous distribution of damages around the gallery and their fast formation after the excavation. Two main areas were concerned by damage formation, located in regions where the bedding was tangential to the excavated gallery. Such regions represented an extension of about 2 m along the gallery walls and reached a depth of 1.5 m. Main damages were created during the next months following the excavation process. Slight variations were still observed 3 yr after the excavation that may be related to the gallery environmental condition fluctuation. The method applied here demonstrates the interest to monitor the whole region surrounding excavated galleries dedicated to host nuclear wastes.

  4. Recovery of Missing Persons in Cyprus: Heavy Equipment Methods and Techniques for Complex Well Excavations.

    PubMed

    Ceker, Deren; Stevens, William D

    2015-11-01

    This technical note presents the methods and techniques developed by the Bi-communal Forensic Team (BCFT) of the Committee on Missing Persons in Cyprus (CMP) used to excavate and exhume the remains of missing persons, many of whom were buried in deep wells at sites across the island of Cyprus during the conflict period of the 1960s and 1970s. A total of 493 Turkish Cypriots and 1508 Greek Cypriots were officially reported missing by the two communities as a result of the conflict. Since the team's formation, in 2005, the BCFT has excavated 114 wells, resulting in the recovery of 195 missing individuals from 35 of these well excavations. The standard excavation approach used by the BCFT, especially for deep well recovery, consists of "ramp," "pocket," and "pool" components. These excavation features enable CMP archaeologists to excavate deep wells safely and efficiently while simultaneously permitting time for thorough documentation and unimpeded recovery of human remains. The team uses three variants of this approach to cope with the variety of geological, physical, and hydrological contexts faced in Cyprus' wells, including hard and soft landforms, the presence or absence of water, and limitations imposed by surrounding infrastructure. The "terracing", "double-ramp", and "single-ramp" variations are detailed with respect to the environmental contexts which prescribe their use. The BCFT's general procedures for human remains recovery and standard well safety protocols conclude the article. PMID:26250595

  5. Clinical, histological and microbiological study of hand-excavated carious dentine in extracted permanent teeth.

    PubMed

    Bönecker, M; Grossman, E; Cleaton-Jones, P E; Parak, R

    2003-08-01

    Changes in cultivable flora in dentine samples collected before and after hand excavation were examined in association with clinical status of the cavity surface, light microscopy and scanning electron microscopy (SEM). Thirty-five extracted permanent molar teeth with an occlusal caries lesion were excavated with hand instruments according to the atraumatic restorative treatment (ART) approach. Excavation pressure, dentine colour and consistency were recorded at the dentine-enamel junction (DEJ) prior to carious dentine removal and at the cavity floor after the final excavation; a microbiological sample of dentine was taken at both stages. Twelve restored teeth; six with positive and six with negative bacterial growth on the second sample, were selected for light microscopy and SEM. The hand-excavation removed tooth structure was soft, irreversibly damaged, dark and highly infected. Hand excavation reached dentine of increased hardness with a more normal colour to provide a sound structural base for restoration. Light and SEM examination of the cavity floor showed infected dentinal tubules in all 12 teeth examined. Linear logistic analysis showed a statistical association between light-yellow dentine on the cavity floor and an absence of bacterial growth (P = 0.006). This short-term in vitro study showed that caries-producing bacteria remained in dentine close to the cavity floor in 26/35 teeth despite clinical observations that indicated a suitably prepared cavity floor. PMID:14649040

  6. [Experimental research of the influences on the development of the hip joints with excavated acetabula].

    PubMed

    Sun, D; Chen, X; Tang, C

    1996-12-01

    There are still arguments about the operation excavated acetabula treatments for the congenital dislocation of the hip. To inquire into the influences on the development of the hip joints with excavated acetabula size, we divided 60 two-month-old chickens into three groups which were given incised dislocation and then reduction partly excavated the cartilages of the acetabula and excavated them totally to the left hips respectively. Contrasting observation of all the experimental chickens was taken on the right ones of their own. The second group achieved a fair function of the joint movement. Limited and slight adhesion was not affecting the development of the joints seriously. The third group had, on the contrary, poor functions because of the comprehensive adhesion in the acetabula. The surfaces of the acetabula were replaced by fabric tissue. The remaining or regenerating cartilage cells vary obviously under the light scope and the electronic scope. The heads of the femurs had changed similarly. It is suggested that in dealing with the congenital dislocation of the hip, excavating the acetabola cartilage is not advisable. Partly excavating is permitted when a limited bony process existing in the bottom of the acetabula. PMID:9590781

  7. FISH ASSEMBLAGES AS INDICATORS OF LAKE SUPERIOR COASTAL WETLAND CONDITION

    EPA Science Inventory

    Fish assemblages associated with coastal wetlands in Lake Superior are poorly described. Understanding the environmental factors structuring the biota in these habitats is essential to developing robust indicators of their condition. To identify key environmental influences struc...

  8. Response of a seagrass fish assemblage to improved wastewater treatment.

    PubMed

    Ourgaud, M; Ruitton, S; Bell, J D; Letourneur, Y; Harmelin, J G; Harmelin-Vivien, M L

    2015-01-15

    We compared the structure of a seagrass fish assemblage near a sewage outlet before and after improvements to wastewater treatment. To determine whether responses by the fish assemblage were due to changes in water quality or to other factors, comparisons were made with the structure of a fish assemblage from a nearby site unaffected by sewage effluent. Total species richness, density and biomass of fish, decreased at both sites over the 30-year period. An increase in mean trophic level near the sewage outlet following improvements in water quality indicated that wastewater treatment had another important effect. This result is consistent with the reductions in food webs supporting pelagic and benthic fishes that typically accompany decreases in nutrient inputs. Although improvements to wastewater treatment explained much of the variation in the structure of the fish assemblage at PC, our results also suggest that fishing and climate change, at both sites. PMID:25499183

  9. ANALYSIS OF LOTIC MACROINVERTEBRATE ASSEMBLAGES IN CALIFORNIA'S CENTRAL VALLEY

    EPA Science Inventory

    Using multivariate and cluster analyses, we examined the relaitonships between chemical and physical characteristics and macroinvertebrate assemblages at sites sampled by R-EMAP in California's Central Valley. By contrasting results where community structure was summarized as met...

  10. Light-dependant biostabilisation of sediments by stromatolite assemblages.

    PubMed

    Paterson, David M; Aspden, Rebecca J; Visscher, Pieter T; Consalvey, Mireille; Andres, Miriam S; Decho, Alan W; Stolz, John; Reid, R Pamela

    2008-01-01

    For the first time we have investigated the natural ecosystem engineering capacity of stromatolitic microbial assemblages. Stromatolites are laminated sedimentary structures formed by microbial activity and are considered to have dominated the shallows of the Precambrian oceans. Their fossilised remains are the most ancient unambiguous record of early life on earth. Stromatolites can therefore be considered as the first recognisable ecosystems on the planet. However, while many discussions have taken place over their structure and form, we have very little information on their functional ecology and how such assemblages persisted despite strong eternal forcing from wind and waves. The capture and binding of sediment is clearly a critical feature for the formation and persistence of stromatolite assemblages. Here, we investigated the ecosystem engineering capacity of stromatolitic microbial assemblages with respect to their ability to stabilise sediment using material from one of the few remaining living stromatolite systems (Highborne Cay, Bahamas). It was shown that the most effective assemblages could produce a rapid (12-24 h) and significant increase in sediment stability that continued in a linear fashion over the period of the experimentation (228 h). Importantly, it was also found that light was required for the assemblages to produce this stabilisation effect and that removal of assemblage into darkness could lead to a partial reversal of the stabilisation. This was attributed to the breakdown of extracellular polymeric substances under anaerobic conditions. These data were supported by microelectrode profiling of oxygen and calcium. The structure of the assemblages as they formed was visualised by low-temperature scanning electron microscopy and confocal laser microscopy. These results have implications for the understanding of early stromatolite development and highlight the potential importance of the evolution of photosynthesis in the mat forming process

  11. Habitat characteristics affecting fish assemblages on a Hawaiian coral reef

    USGS Publications Warehouse

    Friedlander, A.M.; Parrish, J.D.

    1998-01-01

    Habitat characteristics of a reef were examined as potential influences on fish assemblage structure, using underwater visual census to estimate numbers and biomass of all fishes visible on 42 benthic transects and making quantitative measurements of 13 variables of the corresponding physical habitat and sessile biota. Fish assemblages in the diverse set of benthic habitats were grouped by detrended correspondence analysis, and associated with six major habitat types. Statistical differences were shown between a number of these habitat types for various ensemble variables of the fish assemblages. Overall, both for complete assemblages and for component major trophic and mobility guilds, these variables tended to have higher values where reef substratum was more structurally or topographically complex, and closer to reef edges. When study sites were separately divided into five depth strata, the deeper strata tended to have statistically higher values of ensemble variables for the fish assemblages. Patterns with depth varied among the various trophic and mobility guilds. Multiple linear regression models indicated that for the complete assemblages and for most trophic and mobility guilds, a large part of the variability for most ensemble variables was explained by measures of holes in the substratum, with important contributions from measured substratum rugosity and depth. A strong linear relationship found by regression of mean fish length on mean volume of holes in the reef surface emphasized the importance of shelter for fish assemblages. Results of this study may have practical applications in designing reserve areas as well as theoretical value in helping to explain the organization of reef fish assemblages.

  12. Light-Dependant Biostabilisation of Sediments by Stromatolite Assemblages

    PubMed Central

    Paterson, David M.; Aspden, Rebecca J.; Visscher, Pieter T.; Consalvey, Mireille; Andres, Miriam S.; Decho, Alan W.; Stolz, John; Reid, R. Pamela

    2008-01-01

    For the first time we have investigated the natural ecosystem engineering capacity of stromatolitic microbial assemblages. Stromatolites are laminated sedimentary structures formed by microbial activity and are considered to have dominated the shallows of the Precambrian oceans. Their fossilised remains are the most ancient unambiguous record of early life on earth. Stromatolites can therefore be considered as the first recognisable ecosystems on the planet. However, while many discussions have taken place over their structure and form, we have very little information on their functional ecology and how such assemblages persisted despite strong eternal forcing from wind and waves. The capture and binding of sediment is clearly a critical feature for the formation and persistence of stromatolite assemblages. Here, we investigated the ecosystem engineering capacity of stromatolitic microbial assemblages with respect to their ability to stabilise sediment using material from one of the few remaining living stromatolite systems (Highborne Cay, Bahamas). It was shown that the most effective assemblages could produce a rapid (12–24 h) and significant increase in sediment stability that continued in a linear fashion over the period of the experimentation (228 h). Importantly, it was also found that light was required for the assemblages to produce this stabilisation effect and that removal of assemblage into darkness could lead to a partial reversal of the stabilisation. This was attributed to the breakdown of extracellular polymeric substances under anaerobic conditions. These data were supported by microelectrode profiling of oxygen and calcium. The structure of the assemblages as they formed was visualised by low-temperature scanning electron microscopy and confocal laser microscopy. These results have implications for the understanding of early stromatolite development and highlight the potential importance of the evolution of photosynthesis in the mat forming

  13. Determinants of fish assemblage structure in Northwestern Great Plains streams

    USGS Publications Warehouse

    Mullen, J.A.; Bramblett, R.G.; Guy, C.S.; Zale, A.V.; Roberts, D.W.

    2011-01-01

    Prairie streams are known for their harsh and stochastic physical conditions, and the fish assemblages therein have been shown to be temporally variable. We assessed the spatial and temporal variation in fish assemblage structure in five intermittent, adventitious northwestern Great Plains streams representing a gradient of watershed areas. Fish assemblages and abiotic conditions varied more spatially than temporally. The most important variables explaining fish assemblage structure were longitudinal position and the proportion of fine substrates. The proportion of fine substrates increased proceeding upstream, approaching 100% in all five streams, and species richness declined upstream with increasing fine substrates. High levels of fine substrate in the upper reaches appeared to limit the distribution of obligate lithophilic fish species to reaches further downstream. Species richness and substrates were similar among all five streams at the lowermost and uppermost sites. However, in the middle reaches, species richness increased, the amount of fine substrate decreased, and connectivity increased as watershed area increased. Season and some dimensions of habitat (including thalweg depth, absolute distance to the main-stem river, and watershed size) were not essential in explaining the variation in fish assemblages. Fish species richness varied more temporally than overall fish assemblage structure did because common species were consistently abundant across seasons, whereas rare species were sometimes absent or perhaps not detected by sampling. The similarity in our results among five streams varying in watershed size and those from other studies supports the generalization that spatial variation exceeds temporal variation in the fish assemblages of prairie and warmwater streams. Furthermore, given longitudinal position, substrate, and stream size, general predictions regarding fish assemblage structure and function in prairie streams are possible. ?? American

  14. The Use of Ground Penetrating Radar to extend the Results of Archaeological Excavation

    NASA Astrophysics Data System (ADS)

    Utsi, E.

    2009-04-01

    The condition of the Romano-British archaeological site in Wortley, Gloucestershire, UK is typical of sites of the period in that it has been heavily robbed out since it first fell into disuse. Building materials taken from the site have been re-used over the centuries to construct other local buildings. This makes both preservation of the extant remains and interpretation of the excavation problematic. Following the accidental discovery of the site in the 1980s, a programme of excavation was set in place. This excavation was run as a practical archaeological training school and, as a result, a wide range of archaeological and geophysical techniques were applied to the site. This included the introduction of Ground Penetrating Radar (GPR). The preliminary results of the first GPR used on site were not entirely satisfactory which led to the development of a new radar in the early 1990s, specifically developed for use on archaeological sites. The excavation and GPR results were published in a series of excavation reports [1] [2]. It was not possible to excavate fully for two reasons. Firstly the site crossed present day ownership boundaries and secondly the ownership of the excavation area changed. At this point the excavation was summarily terminated. In 2007, permission was given by the owner of an adjacent property to carry out a GPR survey over their land in order to derive additional information, if possible. An area survey was carried out in May 2007 with reduced transect spacing [3]. The radar data showed similar patterning to that of the original investigation i.e. substantial remains which had been subject to a high degree of post-occupational attrition. Time slices from the radar survey were matched to the principal excavation plans. It proved possible to deduce the full extent of certain partially excavated features, notably the courtyard and bath house. It was also possible to demonstrate that one part of the adjacent property did not contain similar

  15. Habitat influence in the morphological diversity of coastal fish assemblages

    NASA Astrophysics Data System (ADS)

    Farré, Marc; Lombarte, Antoni; Recasens, Laura; Maynou, Francesc; Tuset, Victor M.

    2015-05-01

    Ecological diversity based on quantitative data is widely used to characterize biological communities, but recently morphological and functional traits have also been used to analyse the structure of fish assemblages. This diversity and structure is usually linked to variables such as habitat complexity and composition, depth, and spatial and temporal variations. In this study, several fish assemblages off the Catalan coast (NW Mediterranean) were ecologically and morphologically analysed and compared. The morphological analysis was performed from body shape of fish species using geometric morphology. Moreover, a canonical correspondence analysis (CCA) was used to analyse the effect of local environmental variables such as habitat, locality and depth on the composition and abundance of assemblages. The results revealed greater differences among assemblages in the clustering performed from morphological data, which is linked to habitat complexity, than those shown by the ecological analysis. Moreover, the CCA analysis indicated that type of substratum and the location significantly influenced the composition and structure of the fish assemblages. These results evidenced that morphology provides different and complementary information than ecological analysis because it allows to predict the ecological and functional habits of species within the community, helping to improve the understanding of the fish assemblages structure.

  16. DETECTION AND COMPARISON OF GIARDIAVIRUS (GLV) FROM DIFFERENT ASSEMBLAGES OF GIARDIA DUODENALIS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Five assemblages of Giardia were identified from cysts in cattle, dog, cat, sheep, and reindeer feces using ribosomal DNA (rDNA) sequencing. Assemblage A was present in cattle and reindeer feces, Assemblages C and D were present in dog feces, Assemblage E was present in cattle and sheep feces, and ...

  17. Shock-induced growth and metastability of stishovite and coesite in lithic clasts from suevite of the Ries impact crater (Germany)

    NASA Astrophysics Data System (ADS)

    Stähle, Volker; Altherr, Rainer; Koch, Mario; Nasdala, Lutz

    2008-04-01

    The microtextures of stishovite and coesite in shocked non-porous lithic clasts from suevite of the Ries impact structure were studied in transmitted light and under the scanning electron microscope. Both high-pressure silica phases were identified in situ by laser-Raman spectroscopy. They formed from silica melt as well as by solid-state transformation. In weakly shocked rocks (stage I), fine-grained stishovite (≤1.8 μm) occurs in thin pseudotachylite veins of quartz-rich rocks, where it obviously nucleated from high-pressure frictional melts. Generally no stishovite was found in planar deformation features (PDFs) within grains of rock-forming quartz. The single exception is a highly shocked quartz grain, trapped between a pseudotachylite vein and a large ilmenite grain, in which stishovite occurs within two sets of lamellae. It is assumed that in this case the small stishovite grains formed by the interplay of conductive heating and shock reverberation. In strongly shocked rocks (stages Ib-III, above ˜30 GPa), grains of former quartz typically contain abundant and variably sized stishovite (<6 μm) embedded within a dense amorphous silica phase in the interstices between PDFs. The formation of transparent diaplectic glass in adjacent domains results from the breakdown of stishovite and the transformation of the dense amorphous phase and PDFs to diaplectic glass in the solid state. Coesite formed during unloading occurs in two textural varieties. Granular micrometre-sized coesite occurs embedded in silica melt glass along former fractures and grain boundaries. These former high-pressure melt pockets are surrounded by diaplectic glass or by domains consisting of microcrystalline coesite and earlier formed stishovite. The latter is mostly replaced by amorphous silica.

  18. Factors influencing riverine fish assemblages in Massachusetts

    USGS Publications Warehouse

    Armstrong, David S.; Richards, Todd A.; Levin, Sara B.

    2011-01-01

    The U.S. Geological Survey, in cooperation with the Massachusetts Department of Conservation and Recreation, Massachusetts Department of Environmental Protection, and the Massachusetts Department of Fish and Game, conducted an investigation of fish assemblages in small- to medium-sized Massachusetts streams. The objective of this study was to determine relations between fish-assemblage characteristics and anthropogenic factors, including impervious cover and estimated flow alteration, relative to the effects of environmental factors, including physical-basin characteristics and land use. The results of this investigation supersede those of a preliminary analysis published in 2010. Fish data were obtained for 669 fish-sampling sites from the Massachusetts Division of Fisheries and Wildlife fish-community database. A review of the literature was used to select fish metrics - species richness, abundance of individual species, and abundances of species grouped on life history traits - responsive to flow alteration. The contributing areas to the fish-sampling sites were delineated and used with a geographic information system to determine a set of environmental and anthropogenic factors that were tested for use as explanatory variables in regression models. Reported and estimated withdrawals and return flows were used together with simulated unaltered streamflows to estimate altered streamflows and indicators of flow alteration for each fish-sampling site. Altered streamflows and indicators of flow alteration were calculated on the basis of methods developed in a previous U.S. Geological Survey study in which unaltered daily streamflows were simulated for a 44-year period (water years 1961-2004), and streamflow alterations were estimated by use of water-withdrawal and wastewater-return data previously reported to the State for the 2000-04 period and estimated domestic-well withdrawals and septic-system discharges. A variable selection process, conducted using principal

  19. Application of dig-face monitoring during excavation of a radioactive plume

    SciTech Connect

    Josten, N.E.; Gehrke, R.; Stanley, R.; MacMahan, K.

    1996-11-01

    Dig-face characterization is a concept for improving the safety and efficiency of hazardous waste retrieval. A dig-face characterization system consists of onsite hardware for collecting detailed information on the changing chemical, radiological, and physical conditions in the subsurface during the entire course of a hazardous site excavation. The dig-face characterization concept originated at the Idaho National Engineering Laboratory and has been under development there since 1992. During August 1995, a prototype dig-face system was taken to Mound Laboratory, Ohio, for a first attempt at monitoring a hazardous excavation. Mound Area 7 was the site of historical disposals of {sup 232}Th, {sup 227}Ac, and assorted debris. The dig-face characterization system was used to monitor a 20-ft x 20-ft x 5-ft-deep excavation aimed at removing {sup 227}Ac contaminated soils. Radiological, geophysical, and topographic sensors were scanned across the excavation dig-face at four successive depths as soil was removed in 1-ft to 2-ft lifts. The geophysical and topographic sensors located metallic debris and mapped the dig-face topography in great detail as the excavation advanced. The radiation sensors produced high-fidelity images showing the location of radioactive contaminants and clearly identified and delineated separate {sup 232}Th and {sup 227}Ac plumes. By combining the radiation data from all four levels, a three-dimensional image of the contamination plumes was developed. The radiation sensor data indicated that only a small portion of the excavated soil volume was contaminated. The spatial information produced by the dig-face system was used to direct the excavation activities into the area containing the {sup 227}Ac and to evaluate options for handling the separate {sup 232}Th plume.

  20. Dig-face monitoring during excavation of a radioactive plume at Mound Laboratory, Ohio

    SciTech Connect

    Josten, N.E.; Gehrke, R.J.; Carpenter, M.V.

    1995-12-01

    A dig-face monitoring system consists of onsite hardware for collecting information on changing chemical, radiological, and physical conditions in the subsurface soil during the hazardous site excavation. A prototype dig-face system was take to Mount Laboratory for a first trial. Mound Area 7 was the site of historical disposals of {sup 232}Th, {sup 227}Ac, and assorted debris. The system was used to monitor a deep excavation aimed at removing {sup 227}Ac-contaminated soils. Radiological, geophysical, and topographic sensors were used to scan across the excavation dig-face at four successive depths as soil was removed. A 3-D image of the contamination plumes was developed; the radiation sensor data indicated that only a small portion of the excavated soil volume was contaminated. The spatial information produced by the dig-face system was used to direct the excavation activities into the area containing the {sup 227}Ac and to evaluate options for handling the separate {sup 232}Th plume.

  1. Physical soil properties and slope treatments effects on hydraulic excavator productivity for forest road construction.

    PubMed

    Parsakho, Aidin; Hosseini, Seyed Ataollah; Jalilvand, Hamid; Lotfalian, Majid

    2008-06-01

    Effects of moisture, porosity and soil bulk density properties, grubbing time and terrain side slopes on pc 220 komatsu hydraulic excavator productivity were investigated in Miana forests road construction project which located in the northern forest of Iran. Soil moisture and porosity determined by samples were taken from undisturbed soil. The elements of daily works were measured with a digital stop watch and video camera in 14 observations (days). The road length and cross section profiles after each 20 m were selected to estimate earthworks volume. Results showed that the mean production rates for the pc 220 komatsu excavators were 60.13 m3 h(-1) and earthwork 14.76 m h(-1) when the mean depth of excavation or cutting was 4.27 m3 m(-1), respectively. There was no significant effects (p = 0.5288) from the slope classes' treatments on productivity, whereas grubbing time, soil moisture, bulk density and porosity had significantly affected on excavator earthworks volume (p < 0.0001). Clear difference was showed between the earthwork length by slope classes (p = 0.0060). Grubbing time (p = 0.2180), soil moisture (p = 0.1622), bulk density (p = 0.2490) and porosity (p = 0.2159) had no significant effect on the excavator earthworks length. PMID:18817241

  2. Cost-effectiveness of one- and two-step incomplete and complete excavations.

    PubMed

    Schwendicke, F; Stolpe, M; Meyer-Lueckel, H; Paris, S; Dörfer, C E

    2013-10-01

    The treatment of deep caries lesions carries significant risks for the integrity of the pulp and often initiates a cascade of re-interventions. Incomplete caries removal may reduce these risks and avoid or delay re-treatment. The present study analyzed the cost-effectiveness of one- and two-step incomplete as well as complete excavations. We used Markov models to simulate treatment of a molar tooth with a deep caries lesion in a 15-year-old patient. Retention of the tooth and its vitality as effectiveness measures as well as accruing costs were analyzed over the patient's lifetime. The model adopted a public-private-payer perspective within German health care. Transition probabilities were calculated based on literature reviews. Monte-Carlo microsimulations were performed with 6-month cycles. One-step incomplete excavation resulted in lower long-term costs and in longer-retained teeth and their vitality (means: 53.5 and 41.0 yrs) compared with two-step incomplete (52.5 and 37.5 yrs) and complete excavations (49.5 and 31.0 yrs), and dominated the other strategies in 70% to 100% of simulations. Regardless of the assumed willingness-to-pay ceiling value, one-step incomplete excavation had the highest probability of being cost-effective. Despite limited evidence levels of input data, we expect one-step incomplete excavation to reduce costs while retaining deeply carious teeth and their vitality for longer. PMID:23945975

  3. Virtual taphonomy: A new method integrating excavation and postprocessing in an archaeological context.

    PubMed

    Wilhelmson, Helene; Dell'Unto, Nicoló

    2015-06-01

    The objective of this paper was to integrate excavation and post-processing of archaeological and osteological contexts and material to enhance the interpretation of these with specific focus on the taphonomical aspects. A method was designed, Virtual Taphonomy, based on the use and integration of image-based 3D modeling techniques into a 3D GIS platform, and tested on a case study. Merging the 3D models and a database directly in the same virtual environment allowed the authors to fully integrate excavation and post-processing in a complex spatial analysis reconnecting contexts excavated on different occasions in the field process. The case study further demonstrated that the method enabled a deeper understanding of the taphonomic agents at work and allowed the construction of a more detailed interpretation of the skeletal remains than possible with more traditional methods. The method also proved to add transparency to the entire research process from field to post-processing and interpretation. Other benefits were the timesaving aspects in documentation, not only in the excavation process but also in post-processing without creating additional costs in material, as the equipment used is available in most archaeological excavations. The authors conclude that this methodology could be employed on a variety of investigations from archaeological to forensic contexts and add significant value in many different respects (for example, detail, objectivity, complexity, time-efficiency) compared to methods currently used. PMID:25720527

  4. Quantifying Assemblage Turnover and Species Contributions at Ecologic Boundaries

    PubMed Central

    Hayek, Lee-Ann C.; Wilson, Brent

    2013-01-01

    Not all boundaries, whether stratigraphical or geographical, are marked by species-level changes in community composition. For example, paleodata for some sites do not show readily discernible glacial-interglacial contrasts. Rather, the proportional abundances of species can vary subtly between glacials and interglacials. This paper presents a simple quantitative measure of assemblage turnover (assemblage turnover index, ATI) that uses changes in species' proportional abundances to identify intervals of community change. A second, functionally-related index (conditioned-on-boundary index, CoBI) identifies species contributions to the total assemblage turnover. With these measures we examine benthonic foraminiferal assemblages to assess glacial/interglacial contrasts at abyssal depths. Our results indicate that these measures, ATI and CoBI, have potential as sequence stratigraphic tools in abyssal depth deposits. Many peaks in the set of values of ATI coincide with terminations at the end of glaciations and delineate peak-bounded ATI intervals (PATIs) separated by boundaries that approximate to glacial terminations and to transgressions at neritic depths. These measures, however, can be used to evaluate the assemblage turnover and composition at any defined ecological or paleoecological boundary. The section used is from Ocean Drilling Program (OPD) Hole 994C, drilled on the Blake Ridge, offshore SE USA. PMID:24130679

  5. Fish assemblage structure following Impoundment of a Great Plains river

    USGS Publications Warehouse

    Quist, M.C.; Hubert, W.A.; Rahel, F.J.

    2005-01-01

    Understanding the upstream and downstream effect of impoundments on stream fish assemblages is important in managing fish populations and predicting the effects of future human activities on stream ecosystems. We used information collected over a 41-year period (1960-2001) to assess changes in fish assemblage structure resulting from impoundment of the Laramie River by Grayrocks Reservoir. Prior to impoundment (i.e., 1960-1979), fish assemblages were dominated by native catostomids and cyprinids. After impoundment several exotic species (e.g., smallmouth bass [Micropterus dolomieu], walleye [Sander vitreus; formerly Stizostedion vitreum], yellow perch [Perca flavescens], brown trout [Salmo trutta]) were sampled from reaches upstream and downstream of the reservoir. Suckermouth minnows (Phenacobius mirabilis) were apparently extirpated, and hornyhead chubs (Nocomis biguttatus) and common shiners (Luxilus cornutus) became rare upstream of Grayrocks Reservoir. The lower Laramie River downstream from Grayrocks Reservoir near its mouth retains habitat characteristics similar to those prior to impoundment (e.g., shallow, braided channel morphology) and is the only downstream area where several sensitive species persist, including sucker-mouth minnows, hornyhead chubs, and bigmouth shiners (Notropis dorsalis). Grayrocks Reservoir serves as a source of exotic piscivores to both upstream and downstream reaches and has altered downstream habitat characteristics. These impacts have had a substantial influence on native fish assemblages. Our results suggest that upstream and downstream effects of impoundment on fish assemblage structure are similar and that downstream reaches which retain habitat characteristics similar to pre-impoundment conditions may serve as areas of refuge for native species.

  6. Tropical Mosquito Assemblages Demonstrate ‘Textbook’ Annual Cycles

    PubMed Central

    Franklin, Donald C.; Whelan, Peter I.

    2009-01-01

    Background Annual biological rhythms are often depicted as predictably cyclic, but quantitative evaluations are few and rarely both cyclic and constant among years. In the monsoon tropics, the intense seasonality of rainfall frequently drives fluctuations in the populations of short-lived aquatic organisms. However, it is unclear how predictably assemblage composition will fluctuate because the intensity, onset and cessation of the wet season varies greatly among years. Methodology/Principal Findings Adult mosquitoes were sampled using EVS suction traps baited with carbon dioxide around swamplands adjacent to the city of Darwin in northern Australia. Eleven sites were sampled weekly for five years, and one site weekly for 24 years, the sample of c. 1.4 million mosquitoes yielding 63 species. Mosquito abundance, species richness and diversity fluctuated seasonally, species richness being highly predictable. Ordination of assemblage composition demonstrated striking annual cycles that varied little from year to year. The mosquito assemblage was temporally structured by a succession of species peaks in abundance. Conclusion/Significance Ordination provided strong visual representation of annual rhythms in assemblage composition and the means to evaluate variability among years. Because most mosquitoes breed in shallow freshwater which fluctuates with rainfall, we did not anticipate such repeatability; we conclude that mosquito assemblage composition appears adapted to predictable elements of the rainfall. PMID:20011531

  7. Interaction between ultrapotassic magmas and carbonate rocks: Evidence from geochemical and isotopic (Sr, Nd, O) compositions of granular lithic clasts from the Alban Hills Volcano, Central Italy

    NASA Astrophysics Data System (ADS)

    Peccerillo, Angelo; Federico, Marcella; Barbieri, Mario; Brilli, Mauro; Wu, Tsai-Wan

    2010-05-01

    Magma-carbonate rock interaction is investigated through a geochemical and Sr-Nd-O isotope study of granular lithic clasts ( ejecta) from the Alban Hills ultrapotassic volcano, Central Italy. Some samples (Group-1) basically represent intrusive equivalents of Alban Hills magmas. A few samples (Group-2) are ultramafic, have high MgO (˜30 to 40 wt%) and δ 18O‰, and originated by accumulation of mafic phases that crystallised from ultrapotassic melts during assimilation of dolomitic rocks. Group-3 ejecta consist of dominant K-feldspar, and show major element compositions similar to phonolites, which, however, are absent among the Alban Hills volcanics. Finally, another group (Group-4) contains corroded K-feldspars, surrounded by a microgranular to porphyritic matrix, made of igneous minerals (K-feldspar, foids, clinopyroxene, phlogopite) plus wollastonite, garnet, and some cuspidine. Group-4 ejecta are depleted in SiO 2 and enriched in CaO with respect to Group-3. The analysed ejecta have similar 143Nd/ 144Nd (0.51204-0.51217) as the Alban Hills lavas, whereas 87Sr/ 86Sr (0.70900-0.71067) is similar to lower. Whole rocks δ 18O‰ ranges from +7.0 to +13.2, reaching maximum values in ultramafic samples. A positive correlation with CaO is observed in single rock groups. Large Ion Lithophile Element (LILE) abundances and REE fractionation are generally high, and extreme values of Th, U and LREE are found in some Group-3 and Group-4 rocks. Mineralogical, petrological and geochemical data reveal extensive interaction between magma and carbonate wall rocks, involving both dolostones and limestones. These processes had dramatic effects on magma compositions, especially on phonolites, which were transformed to foidites. Evidence of such a process is found in Group-4 samples, in which K-feldspar is observed to react with a matrix that represents strongly undersaturated melts formed by interaction between silicate magma and carbonates. Trace element data also testify to a

  8. A Comparison Between The NORCAT Rover Test Results and the ISRU Excavation System Model Predictions Results

    NASA Technical Reports Server (NTRS)

    Gallo, Christopher A.; Agui, Juan H.; Creager, Colin M.; Oravec, Heather A.

    2012-01-01

    An Excavation System Model has been written to simulate the collection and transportation of regolith on the moon. The calculations in this model include an estimation of the forces on the digging tool as a result of excavation into the regolith. Verification testing has been performed and the forces recorded from this testing were compared to the calculated theoretical data. The Northern Centre for Advanced Technology Inc. rovers were tested at the NASA Glenn Research Center Simulated Lunar Operations facility. This testing was in support of the In-Situ Resource Utilization program Innovative Partnership Program. Testing occurred in soils developed at the Glenn Research Center which are a mixture of different types of sands and whose soil properties have been well characterized. This testing is part of an ongoing correlation of actual field test data to the blade forces calculated by the Excavation System Model. The results from this series of tests compared reasonably with the predicted values from the code.

  9. Using three dimensional structural simulations to study the interactions of multiple excavations in salt

    SciTech Connect

    Hoffman, E.L.; Ehgartner, B.L.

    1998-02-01

    Three-dimensional quasistatic finite element codes are being used at Sandia National Laboratories to simulate the interactions of multiple large room and pillar mines in rock salt. The calculations presented in this paper are of a salt dome which contains multiple closely-spaced room and pillar mines. One of the mines was used as an oil storage facility, supported by the US DOE under the auspices of the Strategic Petroleum Reserve (SPR) program. The facility has recently been decommissioned due to the discovery of geotechnical instabilities. The model, validated by field observations, has resulted in a better understanding of the mechanisms which can threaten the stability of an underground excavation, as well as the structural interactions of multiple excavations. Although these calculations were performed in the specific interest of the SPR, the results should be of interest to mine designers concerned with the interactions of multiple mines excavated in a common formation.

  10. Comparison of ISRU Excavation System Model Blade Force Methodology and Experimental Results

    NASA Technical Reports Server (NTRS)

    Gallo, Christopher A.; Wilkinson, R. Allen; Mueller, Robert P.; Schuler, Jason M.; Nick, Andrew J.

    2010-01-01

    An Excavation System Model has been written to simulate the collection and transportation of regolith on the Moon. The calculations in this model include an estimation of the forces on the digging tool as a result of excavation into the regolith. Verification testing has been performed and the forces recorded from this testing were compared to the calculated theoretical data. A prototype lunar vehicle built at the NASA Johnson Space Center (JSC) was tested with a bulldozer type blade developed at the NASA Kennedy Space Center (KSC) attached to the front. This is the initial correlation of actual field test data to the blade forces calculated by the Excavation System Model and the test data followed similar trends with the predicted values. This testing occurred in soils developed at the NASA Glenn Research Center (GRC) which are a mixture of different types of sands and whose soil properties have been well characterized. Three separate analytical models are compared to the test data.

  11. Multi-filter analysis of infrared images from the excavation experiment in horizontally stratified rocks

    NASA Astrophysics Data System (ADS)

    Gong, W. L.; Gong, Y. X.; Long, A. F.

    2013-01-01

    This paper presents a morphological study of the low-resolution and noisy thermogram obtained in the laboratory excavation experiment on the large-scale geological model of man-made horizontally stratified rocks. The developed new image processing algorithm consists of image subtraction, median filter, low-pass alternating-morphological filter, and multi-scale morphological enhancement filter. These filters were used sequentially to process the detected infrared images. In comparison with the old algorithm for thermogram process, the excavation border with changed stress and changed brightness can be distinguished more clearly in the new thermogram sequences. The new algorithm is possible to be applied in processing other low-resolution and noisy thermogram, and the analysis results in this paper are helpful for understanding the pure elastic, the stationary frictional effect and the dynamic frictional effect at the excavation processes.

  12. Bronze and Iron Age Finds from Romuald's Cave, Istria: 2014 Excavation Season.

    PubMed

    Janković, Ivor; Ahern, James C M; Mihelić, Sanjin; Premuzić, Zrinka

    2015-12-01

    Archaeological excavations in Romuald's Cave (Lim Channel, Istria, Croatia) have yielded evidence of human activity stretching back to the Middle Palaeolithic. This paper reports on recent Bronze Age/Early Iron Age discoveries uncovered during excavations as part of the Croatian National Science Foundation funded project: "Archaeological Investigations into the Late Pleistocene and Early Holocene of the Lim Channel, Istria". Fragmentary skeletal remains from at least two individuals were excavated, and a direct radiocarbon date from one of the remains is commensurate with a Bronze Age attribution. The recovered ceramics confirm this age attribution, although they range from the Middle Bronze Age to incipient Iron Age in character. Furthermore, the ceramics indicate that the human activities in Romuald's Cave were associated with the nearby settlements of Gradina and St. Martin. PMID:26987164

  13. Alternative cytoskeletal landscapes: cytoskeletal novelty and evolution in basal excavate protists

    PubMed Central

    Dawson, Scott C.; Paredez, Alexander R.

    2016-01-01

    Microbial eukaryotes encompass the majority of eukaryotic evolutionary and cytoskeletal diversity. The cytoskeletal complexity observed in multicellular organisms appears to be an expansion of components present in genomes of diverse microbial eukaryotes such as the basal lineage of flagellates, the Excavata. Excavate protists have complex and diverse cytoskeletal architectures and life cycles – essentially alternative cytoskeletal “landscapes” – yet still possess conserved microtubule- and actin-associated proteins. Comparative genomic analyses have revealed that a subset of excavates, however, lack many canonical actin-binding proteins central to actin cytoskeleton function in other eukaryotes. Overall, excavates possess numerous uncharacterized and “hypothetical” genes, and may represent an undiscovered reservoir of novel cytoskeletal genes and cytoskeletal mechanisms. The continued development of molecular genetic tools in these complex microbial eukaryotes will undoubtedly contribute to our overall understanding of cytoskeletal diversity and evolution. PMID:23312067

  14. A common tendency for phylogenetic overdispersion in mammalian assemblages

    PubMed Central

    Cooper, Natalie; Rodríguez, Jesús; Purvis, Andy

    2008-01-01

    Competition has long been proposed as an important force in structuring mammalian communities. Although early work recognized that competition has a phylogenetic dimension, only with recent increases in the availability of phylogenies have true phylogenetic investigations of mammalian community structure become possible. We test whether the phylogenetic structure of 142 assemblages from three mammalian clades (New World monkeys, North American ground squirrels and Australasian possums) shows the imprint of competition. The full set of assemblages display a highly significant tendency for members to be more distantly related than expected by chance (phylogenetic overdispersion). The overdispersion is also significant within two of the clades (monkeys and squirrels) separately. This is the first demonstration of widespread overdispersion in mammal assemblages and implies an important role for either competition between close relatives where traits are conserved, habitat filtering where distant relatives share convergent traits, or both. PMID:18508747

  15. Shaping up: a geometric morphometric approach to assemblage ecomorphology.

    PubMed

    Bower, L M; Piller, K R

    2015-09-01

    This study adopts an ecomorphological approach to test the utility of body shape as a predictor of niche relationships among a stream fish assemblage of the Tickfaw River (Lake Pontchartrain Basin) in southeastern Louisiana, U.S.A. To examine the potential influence of evolutionary constraints, analyses were performed with and without the influence of phylogeny. Fish assemblages were sampled throughout the year, and ecological data (habitat and tropic guild) and body shape (geometric morphometric) data were collected for each fish specimen. Multivariate analyses were performed to examine relationships and differences between body shape and ecological data. Results indicate that a relationship exists between body shape and trophic guild as well as flow regime, but no significant correlation between body shape and substratum was found. Body shape was a reliable indicator of position within assemblage niche space. PMID:26268468

  16. A radioactive waste excavation at Mound Area 7 using INEL dig-face monitoring technology

    SciTech Connect

    Carpenter, M.V.; Josten, N.E.

    1996-12-31

    Dig-face characterization is a method to improve the safety and efficiency during hazardous waste retrieval. A dig-face characterization system consists of on-site hardware for collecting detailed information on the changing chemical, radiological, and physical conditions in the subsurface throughout a hazardous site excavation. The dig-face characterization concept originated at the Idaho National Engineering Laboratory where it has been under development since 1992. In August 1995, a prototype dig-face system was taken to Mound Laboratory, Ohio, to monitor a hazardous waste site excavation. Mound Area 7 was the site of previous disposal of {sup 232}Th, {sup 227}Ac, and other waste. The dig-face characterization system was used to monitor a 20-ft x 20-ft x 5-ft-deep excavation intended to remove the {sup 227}Ac contaminated soils. Radiological, geophysical, and topographical sensors were scanned across each of four successive excavated soil levels, each 1-ft to 2-ft thick. The radiation sensors produced highly detailed images showing the location of the contaminants {sup 232}Th and {sup 227}Ac, and the clear delineation between them. When combined into a single data set, the four levels of collected data produced a three dimensional image of the contamination. The radiation sensor data indicated that only a small portion of the excavated soil was actually contaminated. The information produced by the dig-face system was used to direct precise excavation activities in the area containing the {sup 227}Ac and to plan subsequent removal of the separate {sup 232}Th plume.

  17. Faunal assemblage composition and paleoenvironment of Plovers Lake, a Middle Stone Age locality in Gauteng Province, South Africa.

    PubMed

    de Ruiter, Darryl J; Brophy, Juliet K; Lewis, Patrick J; Churchill, Steven E; Berger, Lee R

    2008-12-01

    Plovers Lake is a dolomitic cave infill located approximately 45km northwest of Johannesburg in the Bloubank Valley, Gauteng Province, South Africa. Excavations between 2002-2004 revealed a rich and diverse fauna, a moderate-sized stone tool assemblage of Middle Stone Age (MSA) character, and human skeletal remains. Two principal depositional units are recognized: 1) a disturbed ex situ component that was likely displaced from 2) an otherwise relatively undisturbed in situ component from which the human skeletal material was recovered. The in situ depositional unit is bracketed by 2 flowstone layers, with U-series dates of 62.9 (+/-1.3)ka for the capping flowstone and 88.7 (+/-1.6)ka for the underlying flowstone. A single isochron ESR date of 75.6 (+/-5.6)ka corroborates the U-series dates. This paper presents an analysis of the mammalian, bird, and reptile faunas recovered from these two units. The two faunal assemblages show close correspondence in taphonomic, taxonomic, and ecological composition, supporting a common origin for both the ex situ and in situ components. Although human skeletal material, cut-marked bone, and stone tools have been recovered, these indications are too rare to consider Plovers Lake a human occupation site. Instead, a high abundance of carnivores, coprolites, and carnivore damaged bones point to brown hyenas as the principal, though not exclusive, bone accumulating agent. In the absence of a significant taphonomic bias relating to accumulating agent, Plovers Lake allows us to document an environment occupied by MSA humans, even if the humans were not resident in the cave itself. We reconstruct the paleoenvironment of Plovers Lake as predominantly grassland, though it was colder, moister, and more wooded than at present. Paleoclimatic conditions appear to have been as different from historic norms as those seen in several fossil localities in the Western Cape, pointing to greater environmental heterogeneity than has previously been

  18. Alteration assemblages in the nakhlites: Variation with depth on Mars

    NASA Astrophysics Data System (ADS)

    Changela, H. G.; Bridges, J. C.

    2010-12-01

    Secondary mineral assemblages in the nakhlite meteorites, Lafayette, Governador Valadares (GV), Nakhla, Yamato (Y)-000593/Y-000749 have been studied using scanning electron microscopy, transmission electron microscopy, and electron probe micro analysis. The different nakhlites have distinctive secondary assemblages in their olivine grains and mesostases, showing compositional fractionation correlated with their relative depths below the Martian surface. Fracture-filled veins in Lafayette at the bottom of the pile consist of a siderite-phyllosilicate-Fe oxide-hydrated silicate gel assemblage. Corresponding veins in Nakhla and GV further up the pile are predominantly a siderite-gel assemblage, with additional evaporites including gypsum. Y-000593/Y-000749 veins are dominated by gel. The gel’s Mg/(Mg + Fe) ratio decreases from Lafayette (0.37) to GV (0.32), Nakhla (0.24), and Y-000593 (0.15). We suggest that hydrothermal fluid flowed up this depth profile, initiated by melting of buried H2O-CO2 ice. Our results show a complex mix of Fe-rich phyllosilicate within the veins and mesostasis of Lafayette with d-spacings of 0.7-1.1 nm suggesting a mixture of smectite and serpentine. The phyllosilicate formed at close to neutral pH, ≤150 °C. We also suggest that water rock ratios (W/R) of 1-10 occurred in Lafayette with smaller values for the other nakhlites. This is reflected in the volume of alteration minerals: 10% of olivine in Lafayette to 3% in Nakhla. Textural evidence of rapid cooling, together with the W/R and likely fluid velocities, suggest that the secondary assemblages formed quickly, e.g., within months. A model is proposed in which the secondary assemblages formed in an impact-induced hydrothermal system terminated by precipitation of the gel and evaporation of soluble salts.

  19. Habitat Specialization in Tropical Continental Shelf Demersal Fish Assemblages

    PubMed Central

    Fitzpatrick, Ben M.; Harvey, Euan S.; Heyward, Andrew J.; Twiggs, Emily J.; Colquhoun, Jamie

    2012-01-01

    The implications of shallow water impacts such as fishing and climate change on fish assemblages are generally considered in isolation from the distribution and abundance of these fish assemblages in adjacent deeper waters. We investigate the abundance and length of demersal fish assemblages across a section of tropical continental shelf at Ningaloo Reef, Western Australia, to identify fish and fish habitat relationships across steep gradients in depth and in different benthic habitat types. The assemblage composition of demersal fish were assessed from baited remote underwater stereo-video samples (n = 304) collected from 16 depth and habitat combinations. Samples were collected across a depth range poorly represented in the literature from the fringing reef lagoon (1–10 m depth), down the fore reef slope to the reef base (10–30 m depth) then across the adjacent continental shelf (30–110 m depth). Multivariate analyses showed that there were distinctive fish assemblages and different sized fish were associated with each habitat/depth category. Species richness, MaxN and diversity declined with depth, while average length and trophic level increased. The assemblage structure, diversity, size and trophic structure of demersal fishes changes from shallow inshore habitats to deeper water habitats. More habitat specialists (unique species per habitat/depth category) were associated with the reef slope and reef base than other habitats, but offshore sponge-dominated habitats and inshore coral-dominated reef also supported unique species. This suggests that marine protected areas in shallow coral-dominated reef habitats may not adequately protect those species whose depth distribution extends beyond shallow habitats, or other significant elements of demersal fish biodiversity. The ontogenetic habitat partitioning which is characteristic of many species, suggests that to maintain entire species life histories it is necessary to protect corridors of connected

  20. Phytoplankton Assemblage Patterns in the Southern Mid-Atlantic Bight

    NASA Technical Reports Server (NTRS)

    Makinen, Carla; Moisan, Tiffany A. (Editor)

    2012-01-01

    As part of the Wallops Coastal Oceans Observing Laboratory (Wa-COOL) Project, we sampled a time-series transect in the southern Mid-Atlantic Bight (MAB) biweekly. Our 2-year time-series data included physical parameters, nutrient concentrations, and chlorophyll a concentrations. A detailed phytoplankton assemblage structure was examined in the second year. During the 2-year study, chlorophyll a concentration (and ocean color satellite imagery) indicated that phytoplankton blooms occurred in January/February during mixing conditions and in early autumn under stratified conditions. The chlorophyll a concentrations ranged from 0.25 microgram 1(exp -1) to 15.49 microgram 1(exp -1) during the 2-year period. We were able to discriminate approximately 116 different species under phase contrast microscopy. Dominant phytoplankton included Skeletonema costatum, Rhizosolenia spp., and Pseudo-nitzschia pungens. In an attempt to determine phytoplankton species competition/succession within the assemblage, we calculated a Shannon Weaver diversity index for our diatom microscopy data. Diatom diversity was greatest during the winter and minimal during the spring. Diatom diversity was also greater at nearshore stations than at offshore stations. Individual genera appeared patchy, with surface and subsurface patches appearing abruptly and persisting for only 1-2 months at a time. The distribution of individual species differed significantly from bulk variables of the assemblage (chlorophyll a ) and total phytoplankton assemblage (cells), which indicates that phytoplankton species may be limited in growth in ways that differ from those of the total assemblage. Our study demonstrated a highly diverse phytoplankton assemblage throughout the year, with opportunistic species dominating during spring and fall in response to seasonal changes in temperature and nutrients in the southern MAB.

  1. Riparian influences on stream fish assemblage structure in urbanizing streams

    USGS Publications Warehouse

    Roy, A.H.; Freeman, B.J.; Freeman, Mary C.

    2007-01-01

    We assessed the influence of land cover at multiple spatial extents on fish assemblage integrity, and the degree to which riparian forests can mitigate the negative effects of catchment urbanization on stream fish assemblages. Riparian cover (urban, forest, and agriculture) was determined within 30 m buffers at longitudinal distances of 200 m, 1 km, and the entire network upstream of 59 non-nested fish sampling locations. Catchment and riparian land cover within the upstream network were highly correlated, so we were unable to distinguish between those variables. Most fish assemblage variables were related to % forest and % urban land cover, with the strongest relations at the largest spatial extent of land cover (catchment), followed by riparian land cover in the 1-km and 200-m reach, respectively. For fish variables related to urban land cover in the catchment, we asked whether the influence of riparian land cover on fish assemblages was dependent on the amount of urban development in the catchment. Several fish assemblage metrics (endemic richness, endemic:cosmopolitan abundance, insectivorous cyprinid richness and abundance, and fluvial specialist richness) were all best predicted by single variable models with % urban land cover. However, endemic:cosmopolitan richness, cosmopolitan abundance, and lentic tolerant abundance were related to % forest cover in the 1-km stream reach, but only in streams that had <15% catchment urban land cover. In these cases, catchment urbanization overwhelmed the potential mitigating effects of riparian forests on stream fishes. Together, these results suggest that catchment land cover is an important driver of fish assemblages in urbanizing catchments, and riparian forests are important but not sufficient for protecting stream ecosystems from the impacts of high levels of urbanization.

  2. Methane Seep Carbonates Host Distinct, Diverse, and Dynamic Microbial Assemblages

    PubMed Central

    Pasulka, Alexis L.; Marlow, Jeffrey J.; Grupe, Benjamin M.; Levin, Lisa A.

    2015-01-01

    ABSTRACT Marine methane seeps are globally distributed geologic features in which reduced fluids, including methane, are advected upward from the subsurface. As a result of alkalinity generation during sulfate-coupled methane oxidation, authigenic carbonates form slabs, nodules, and extensive pavements. These carbonates shape the landscape within methane seeps, persist long after methane flux is diminished, and in some cases are incorporated into the geologic record. In this study, microbial assemblages from 134 native and experimental samples across 5,500 km, representing a range of habitat substrates (carbonate nodules and slabs, sediment, bottom water, and wood) and seepage conditions (active and low activity), were analyzed to address two fundamental questions of seep microbial ecology: (i) whether carbonates host distinct microbial assemblages and (ii) how sensitive microbial assemblages are to habitat substrate type and temporal shifts in methane seepage flux. Through massively parallel 16S rRNA gene sequencing and statistical analysis, native carbonates are shown to be reservoirs of distinct and highly diverse seep microbial assemblages. Unique coupled transplantation and colonization experiments on the seafloor demonstrated that carbonate-associated microbial assemblages are resilient to seep quiescence and reactive to seep activation over 13 months. Various rates of response to simulated seep quiescence and activation are observed among similar phylogenies (e.g., Chloroflexi operational taxonomic units) and similar metabolisms (e.g., putative S oxidizers), demonstrating the wide range of microbial sensitivity to changes in seepage flux. These results imply that carbonates do not passively record a time-integrated history of seep microorganisms but rather host distinct, diverse, and dynamic microbial assemblages. PMID:26695630

  3. Stepwise Excavation Allows Apexogenesis in Permanent Molars with Deep Carious Lesions and Incomplete Root Formation.

    PubMed

    Hernandéz-Gatón, Patrícia; Serrano, César Ruiz; Nelson Filho, Paulo; De Castañeda, Esther Ruiz; Lucisano, Marília P; Silva, Raquel A B da; Silva, Léa A B da

    2015-01-01

    This study evaluated the stepwise excavation technique in 138 permanent molars with deep carious lesions and incomplete root formation within a 24-month clinical and radiographic follow-up period. In 96.7% of the cases, success was observed (no pain, integrity of restoration margins, absence of radiographic alterations and apexogenesis). The cases of failure (3.3%) were due to the loss of the temporary restoration. In conclusion, the stepwise excavation is a promising technique for permanent teeth with deep carious lesions and incomplete root formation as a minimally invasive approach because it allows the preservation of pulp vitality and occurrence of apexogenesis. PMID:26655853

  4. National Advanced Drilling and Excavation Technologies Institute. Status report, March 1997

    SciTech Connect

    Peterson, C.

    1997-12-31

    The National Advanced Drilling and Excavation Technologies (NADET) program is intended to pool support, talent, and technologies of the industries dependent upon drilling and excavation technologies to initiate, coordinate, and sustain programs capable of developing substantial technological advances. The NADET Institute has been funded by the DOE Office of Geothermal Technologies and is now supporting seven projects aimed at advanced geothermal drilling technologies. The Institute seeks to broaden its base of funding and technological support from both government and industry sources. Encouraging progress has been made with the support of dues-paying industrial members and industrial sponsorship of a substantial drilling research study.

  5. Nest enlargement in leaf-cutting ants: relocated brood and fungus trigger the excavation of new chambers.

    PubMed

    Römer, Daniela; Roces, Flavio

    2014-01-01

    During colony growth, leaf-cutting ants enlarge their nests by excavating tunnels and chambers housing their fungus gardens and brood. Workers are expected to excavate new nest chambers at locations across the soil profile that offer suitable environmental conditions for brood and fungus rearing. It is an open question whether new chambers are excavated in advance, or will emerge around brood or fungus initially relocated to a suitable site in a previously-excavated tunnel. In the laboratory, we investigated the mechanisms underlying the excavation of new nest chambers in the leaf-cutting ant Acromyrmex lundi. Specifically, we asked whether workers relocate brood and fungus to suitable nest locations, and to what extent the relocated items trigger the excavation of a nest chamber and influence its shape. When brood and fungus were exposed to unfavorable environmental conditions, either low temperatures or low humidity, both were relocated, but ants clearly preferred to relocate the brood first. Workers relocated fungus to places containing brood, demonstrating that subsequent fungus relocation spatially follows the brood deposition. In addition, more ants aggregated at sites containing brood. When presented with a choice between two otherwise identical digging sites, but one containing brood, ants' excavation activity was higher at this site, and the shape of the excavated cavity was more rounded and chamber-like. The presence of fungus also led to the excavation of rounder shapes, with higher excavation activity at the site that also contained brood. We argue that during colony growth, workers preferentially relocate brood to suitable locations along a tunnel, and that relocated brood spatially guides fungus relocation and leads to increased digging activity around them. We suggest that nest chambers are not excavated in advance, but emerge through a self-organized process resulting from the aggregation of workers and their density-dependent digging behavior

  6. Hydrothermal Alteration Constrained by Mineral Assemblages on Mars: Evidence from Craters Near Syrtis Major

    NASA Astrophysics Data System (ADS)

    Mustard, J. F.; Ehlmann, B. L.; Murchie, S. L.

    2009-12-01

    Observational evidence for hydrothermal alteration associated with impact craters in the Southern Highlands of Mars is growing [Ehlmann, et al 2008; 2009; Marzo 2008]. Hydrothermal systems are predicted for impacts into volatile-rich targets where fluid flow is typically concentrated along fractures in the walls, central peaks, and beneath the crater floor [e.g. Abramov and Kring, 2005]. The impact process may also excavate pre-existing alteration minerals that were buried at depth, leading to their exposure in rock units comprising the crater central peak, walls, and ejecta [Mustard et al., 2008]. Here we report on the hydrated silicate mineralogy of three impact craters on Syrtis Major that define possible hydrothermal assemblages: Toro Crater (17°N, 71.8°E, 40 km diameter), Schroeter Crater (3°N, 58°E, 64 km diameter), and an unnamed crater (15.5°N, 72.4°E, 50 km diameter). Crater morphology and superposition of ejecta on the Hesperian-aged Syrtis Major lavas shows Toro and Schroeter post-date the emplacement of the lava, while the floor of the unnamed crater is filled by volcanics and thus clearly predates the lavas. Detailed analysis of the overtone and combination tone bands near 1.4 and between 1.9 and 2.5 µm in CRISM near-infrared reflectance spectra leads to identification of a number of hydrated silicate minerals [Ehlmann et al., 2009]. Fe/Mg smectite clay as well as chlorite and prehnite are present in each of the craters, which also exhibit additional mineralogic diversity. Toro crater shows clear evidence for hydrated silica while the unnamed crater and Schroeter show the presence of kaolinite. The central peaks of Toro and Schroeter are exposed and show the most diverse mineralogy, including spectra that are mixtures of numerous alteration minerals. In addition, HiRISE images resolve large breccia blocks and fractures relative to the impact events in these central peaks. Toro shows fractures that are filled with a dark material that also

  7. 76 FR 19129 - Excavations (Design of Cave-in Protection Systems); Extension of the Office of Management and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-06

    ... 1995 (44 U.S.C. 3506 et seq.) and Secretary of Labor's Order No. 4-2010 (75 FR 55355). ] Signed at... Occupational Safety and Health Administration Excavations (Design of Cave-in Protection Systems); Extension of... information collection requirements contained in the Standard on Excavations (Design of Cave-in...

  8. Climate mediates the effects of disturbance on ant assemblage structure.

    PubMed

    Gibb, Heloise; Sanders, Nathan J; Dunn, Robert R; Watson, Simon; Photakis, Manoli; Abril, Silvia; Andersen, Alan N; Angulo, Elena; Armbrecht, Inge; Arnan, Xavier; Baccaro, Fabricio B; Bishop, Tom R; Boulay, Raphael; Castracani, Cristina; Del Toro, Israel; Delsinne, Thibaut; Diaz, Mireia; Donoso, David A; Enríquez, Martha L; Fayle, Tom M; Feener, Donald H; Fitzpatrick, Matthew C; Gómez, Crisanto; Grasso, Donato A; Groc, Sarah; Heterick, Brian; Hoffmann, Benjamin D; Lach, Lori; Lattke, John; Leponce, Maurice; Lessard, Jean-Philippe; Longino, John; Lucky, Andrea; Majer, Jonathan; Menke, Sean B; Mezger, Dirk; Mori, Alessandra; Munyai, Thinandavha C; Paknia, Omid; Pearce-Duvet, Jessica; Pfeiffer, Martin; Philpott, Stacy M; de Souza, Jorge L P; Tista, Melanie; Vasconcelos, Heraldo L; Vonshak, Merav; Parr, Catherine L

    2015-06-01

    Many studies have focused on the impacts of climate change on biological assemblages, yet little is known about how climate interacts with other major anthropogenic influences on biodiversity, such as habitat disturbance. Using a unique global database of 1128 local ant assemblages, we examined whether climate mediates the effects of habitat disturbance on assemblage structure at a global scale. Species richness and evenness were associated positively with temperature, and negatively with disturbance. However, the interaction among temperature, precipitation and disturbance shaped species richness and evenness. The effect was manifested through a failure of species richness to increase substantially with temperature in transformed habitats at low precipitation. At low precipitation levels, evenness increased with temperature in undisturbed sites, peaked at medium temperatures in disturbed sites and remained low in transformed sites. In warmer climates with lower rainfall, the effects of increasing disturbance on species richness and evenness were akin to decreases in temperature of up to 9°C. Anthropogenic disturbance and ongoing climate change may interact in complicated ways to shape the structure of assemblages, with hot, arid environments likely to be at greatest risk. PMID:25994675

  9. Temporal variability in epifaunal assemblages associated with temperate gorgonian gardens.

    PubMed

    Dias, I M; Cúrdia, J; Cunha, M R; Santos, M N; Carvalho, S

    2015-12-01

    The present study is one of the few that investigate the temporal variability of epifaunal assemblages associated with coral species, particularly the octocorals Eunicella gazella and Leptogorgia lusitanica in south Portugal. The results suggest time rather than colony size as a primary driver of the ecological patterns of these assemblages, which were dominated by amphipods, molluscs and polychaetes. Temporal variability was linked to changes in environmental parameters, namely temperature, chlorophyll a and particulate organic carbon. Hence, temporal variability must be taken into account for the design of future biodiversity assessment studies, as different patterns may be observed depending on the sampling time. Associated epifaunal assemblages were consistently dominated by resident species (i.e. species present in all sampling periods) and a peak of rare species was observed in the transition from spring to summer following the increase in seawater temperature. Turnover was particularly high in the transition between the spring and summer periods. In both hosts, turnover was higher in the small sized colonies, which harboured less diverse and less abundant assemblages that also differed from those inhabiting larger size colonies. The high levels of diversity associated with gorgonian colonies highlight the need for the conservation of this priority habitat. PMID:26525873

  10. AN INDEX OF COMPOSITIONAL DISSIMILARITY BETWEEN OBSERVED AND EXPECTED ASSEMBLAGES

    EPA Science Inventory

    The reference-condition approach to bioassessment often uses the observed/expected (O/E) ratio to indicate anthropogenic alteration of aquatic macroinvertebrates, fish, or periphyton assemblages. Given a list of taxa found at 1 or more minimally disturbed reference sites, E is t...

  11. Sewage pollution impact on Mediterranean rocky-reef fish assemblages.

    PubMed

    Azzurro, Ernesto; Matiddi, Marco; Fanelli, Emanuela; Guidetti, Paolo; La Mesa, Gabriele; Scarpato, Alfonso; Axiak, Victor

    2010-06-01

    The effects of sewage outfalls on subtidal fish assemblages were studied along the NW coasts of Malta (Sicily channel, Mediterranean Sea) by means of underwater visual census. The presence of two spatially distinct outfalls discharging untreated wastewaters allowed to use a balanced symmetrical after control/impact (ACI) design that consisted of two putatively impacted locations and two controls, with four sites nested in each location. Surveys were performed in 2006 at two random dates. The study highlighted significant changes at both assemblage and individual species levels. Fish assemblages structures were different between controls and sewages, where total abundance of fish were higher. The responses of individual species to sewage pollution were mostly related to an anomalous increase of two small opportunistic species i.e. Gobius bucchichii and Parablennius rouxi and to a decrease of species of the genus Symphodus, particularly S. roissali and S. ocellatus. Moreover in correspondence of the outfalls, significant changes of the fish size distribution were detected for several species. These results support the use of fish assemblages as biological indicators for marine coastal waters and demonstrated the possibility to obtain sharp signals of environmental impact from some individual fish species. PMID:20193961

  12. Watershed Alteration Impacts to Benthic Diatom Assemblages in Streams

    EPA Science Inventory

    To examine the use of diatoms as indicators of urban impacts to streams, we identified relationships of diatom assemblages with water chemistry and land use for 160 sites in New England. The first axis of a nonmetric multidimensional scaling ordination showed significant relation...

  13. UV EXPOSURE OF CORAL ASSEMBLAGES IN THE FLORIDA KEYS

    EPA Science Inventory

    Recent studies have indicated that solar radiation can be a significant stressor of coral assemblages in tropical and subtropical marine environments. Here we review the scientific literature related to the interactions of solar radiation with coral reefs, with emphasis on harm...

  14. Experimental formation of brittle structural assemblages in oblique divergence

    NASA Astrophysics Data System (ADS)

    Smith, J. V.; Durney, D. W.

    1992-12-01

    A series of experiments is reported in which brittle minor structures are initiated in narrow deformation zones in clay under conditions of kinematically controlled oblique divergent displacement. Nineteen settings of boundary displacement angle were used from pure wrench to pure divergence under conditions favouring either faults (dry experiments) or extension fractures (wet experiments). Pure wrench produced the well known assemblage of Riedel strike-slip faults whereas experiments in pure divergence produced conjugate arrays of normal faults and extension fractures with a dihedral angle of 30° bisected by the direction of the zone, as has been described in rift zones. Experiments with boundary displacements at intermediate settings show a continuum of structural orientations and dihedral angles between these two extremes. A boundary between assemblages dominated by strike-slip faults and extensional faults was found at a displacement angle of 45° from the deformation zone. These results are interpreted kinematically in terms of: (1) principal axes of infinitesimal incremental strain; (2) material dilatancy control on shear structure dihedral angles; and (3) whether the vertical strain in divergent wrench settings is a thickening (strike-slip assemblage) or a thinning (normal fault assemblage).

  15. Early cretaceous radiolarian assemblages from the East Sakhalin Mountains

    NASA Astrophysics Data System (ADS)

    Kurilov, D. V.; Vishnevskaya, V. S.

    2011-02-01

    Three-dimensional radiolarian skeletons isolated from rock matrix in HF solution and then studied under scanning electron microscope substantiate the Early Cretaceous age of volcanogenic-cherty deposits sampled from fragmentary rock successions of the East Sakhalin Mountains. Accordingly the Berriasian age is established for jasper packets formerly attributed to the Upper Paleozoic-Mesozoic Daldagan Group; the Valanginian radiolarians are identified in cherty rock intercalations in the Upper Paleozoic (?) Ivashkino Formation; the Berriasian-Barremian assemblage is macerated from cherty tuffites of the Jurassic-Cretaceous Ostraya Formation; and the Aptian-early Albian radiolarians are characteristic of tuffaceous cherty rocks sampled from the Cretaceous Khoe Formation of the Nabil Group. Photographic documentation of radiolarian skeletons specifies taxonomic composition and age of the Berriasian, Valanginian, Berriasian-Valanginian, Barremian, and Aptian-Albian radiolarian assemblages from the East Sakhalin Mountains, and their evolution as related to abiotic events is considered. Coexistence of Tethyan and Pacific species in the same rock samples evidence origin of radiolarian assemblages in an ecotone. Consequently, the assemblages are applicable for intra- and interregional correlations and paleogeographic reconstructions.

  16. Climate mediates the effects of disturbance on ant assemblage structure

    PubMed Central

    Gibb, Heloise; Sanders, Nathan J.; Dunn, Robert R.; Watson, Simon; Photakis, Manoli; Abril, Silvia; Andersen, Alan N.; Angulo, Elena; Armbrecht, Inge; Arnan, Xavier; Baccaro, Fabricio B.; Bishop, Tom R.; Boulay, Raphael; Castracani, Cristina; Del Toro, Israel; Delsinne, Thibaut; Diaz, Mireia; Donoso, David A.; Enríquez, Martha L.; Fayle, Tom M.; Feener, Donald H.; Fitzpatrick, Matthew C.; Gómez, Crisanto; Grasso, Donato A.; Groc, Sarah; Heterick, Brian; Hoffmann, Benjamin D.; Lach, Lori; Lattke, John; Leponce, Maurice; Lessard, Jean-Philippe; Longino, John; Lucky, Andrea; Majer, Jonathan; Menke, Sean B.; Mezger, Dirk; Mori, Alessandra; Munyai, Thinandavha C.; Paknia, Omid; Pearce-Duvet, Jessica; Pfeiffer, Martin; Philpott, Stacy M.; de Souza, Jorge L. P.; Tista, Melanie; Vasconcelos, Heraldo L.; Vonshak, Merav; Parr, Catherine L.

    2015-01-01

    Many studies have focused on the impacts of climate change on biological assemblages, yet little is known about how climate interacts with other major anthropogenic influences on biodiversity, such as habitat disturbance. Using a unique global database of 1128 local ant assemblages, we examined whether climate mediates the effects of habitat disturbance on assemblage structure at a global scale. Species richness and evenness were associated positively with temperature, and negatively with disturbance. However, the interaction among temperature, precipitation and disturbance shaped species richness and evenness. The effect was manifested through a failure of species richness to increase substantially with temperature in transformed habitats at low precipitation. At low precipitation levels, evenness increased with temperature in undisturbed sites, peaked at medium temperatures in disturbed sites and remained low in transformed sites. In warmer climates with lower rainfall, the effects of increasing disturbance on species richness and evenness were akin to decreases in temperature of up to 9°C. Anthropogenic disturbance and ongoing climate change may interact in complicated ways to shape the structure of assemblages, with hot, arid environments likely to be at greatest risk. PMID:25994675

  17. EXAMINING ASSOCIATIONS BETWEEN FISH ASSEMBLAGES AND PHYSICAL HABITAT

    EPA Science Inventory

    Assessing lotic fish-habitat interactions from regional survey data requires that we consider a comprehensive representation, at the appropriate scale, of the likely controls on fish assemblages. At the scale of stream and river reaches, the important dimensions of physical habi...

  18. Freshwater Fish Assemblage Patterns in Rhode Island Streams and Rivers

    EPA Science Inventory

    Patterns in fish assemblages in streams and rivers can inform watershed and water management, yet these patterns are not well characterized for the U.S. state of Rhode Island. Here we relate freshwater fish data collected by the Rhode Island Department of Environmental Managemen...

  19. Simulating fish assemblages in riverine networks - September 2013

    EPA Science Inventory

    We describe a modeling approach for simulating assemblages of fish in riverine landscapes. The approach allows a user to determine the grain and extent of river networks within which fish populations reproduce, move, and survive in response to both environmental drivers and assem...

  20. Elk herbivory alters small mammal assemblages in high elevation drainages

    USGS Publications Warehouse

    Parsons, Elliott W.R.; Maron, John L.; Martin, Thomas E.

    2012-01-01

    Together, our results show that relaxation of heavy herbivore pressure by a widespread native ungulate can lead to rapid changes in small mammal assemblages. Moreover, exclusion of large herbivores can yield rapid responses by vegetation that may enhance or maintain habitat quality for small mammal populations.

  1. Lightweight Bulldozer Attachment for Construction and Excavation on the Lunar Surface

    NASA Technical Reports Server (NTRS)

    Mueller, Robert; Wilkinson, R. Allen; Gallo, Christopher A.; Nick, Andrew J.; Schuler, Jason M.; King, Robert H.

    2009-01-01

    A lightweight bulldozer blade prototype has been designed and built to be used as an excavation implement in conjunction with the NASA Chariot lunar mobility platform prototype. The combined system was then used in a variety of field tests in order to characterize structural loads, excavation performance and learn about the operational behavior of lunar excavation in geotechnical lunar simulants. The purpose of this effort was to evaluate the feasibility of lunar excavation for site preparation at a planned NASA lunar outpost. Once the feasibility has been determined then the technology will become available as a candidate element in the NASA Lunar Surface Systems Architecture. In addition to NASA experimental testing of the LANCE blade, NASA engineers completed analytical work on the expected draft forces using classical soil mechanics methods. The Colorado School of Mines (CSM) team utilized finite element analysis (FEA) to study the interaction between the cutting edge of the LANCE blade and the surface of soil. FEA was also used to examine various load cases and their effect on the lightweight structure of the LANCE blade. Overall it has been determined that a lunar bulldozer blade is a viable technology for lunar outpost site preparation, but further work is required to characterize the behavior in 1/6th G and actual lunar regolith in a vacuum lunar environment.

  2. Radiation measurements of excavated items at a radioactive-waste burial site

    NASA Astrophysics Data System (ADS)

    Stromswold, D. C.; Alvarez, J. L.; Ludowise, J. D.

    1995-12-01

    Radiation measurements on items excavated from a radioactive-waste burial ground were part of a field test of excavation techniques for the cleanup of subsurface sites. The waste resulted from plutonium production for nuclear weapons at Hanford, WA. The radiation measurements investigated techniques for classifying bulk waste for placement into a permanent disposal facility. Hand-held γ-ray survey instruments measured exposure rates (mR/h) from contaminated dirt and radioactive objects as they were removed by heavy excavation equipment. Gamma-ray detectors mounted on the excavation equipment provided additional data that were transmitted by radio. Exposure rates from identifiable objects (e.g. specific reactor components) were compared with expected exposure rates calculated from site-disposal records and computer modeling. Selected objects were subjected to additional on-site measurements using a high-purity germanium detector. Detected nuclides included 60Co, 137Cs, 152,154Eu, and 108mAg. A large-volume neutron detector checked for possible transuranic nuclides. Alpha and β spectrometry also were tested. but their utility for this application was limited due to the short range of the particles and the difficulty of maintaining a repeatable measurement geometry in the field.

  3. Subsurface Tiltmeter Observations of Solid Earth Tides and Rock Excavation in Northeastern Illinois

    NASA Astrophysics Data System (ADS)

    Lancelle, C.; Volk, J.; Fratta, D.; Wang, H. F.

    2013-12-01

    Tiltmeter arrays in the Main Injector Neutrino Oscillation Search (MINOS) Near Detector Hall at Fermilab and the Lafarge - Conco Mine record solid earth tides and mechanical unloading due to excavation. The arrays are located approximately 100 meters underground in the Galena-Platteville dolomite in Northeastern Illinois. Just off of the MINOS Near Detector Hall a new cavern was excavated to house the Off-axis Neutrino Appearance Experiment (NOvA) program near detector. The recorded excavation response in the MINOS Near Detector Hall due to the NOvA cavern excavation is approximately thirteen times a point-load estimated response calculated using laboratory-determined properties. This discrepancy is likely due to variations in Young's Modulus in the rock in a field versus laboratory scale, although seasonal effects causing long term trends in the data could be part of this response. Amplitudes of measured solid earth tides differ from the amplitudes of theoretical solid earth tides by up to 40 percent for both arrays. This is likely due to a local heterogeneity or discontinuity.

  4. [Excavation in middle Iraq. Anthropologic results of findings from the thousand years before Christ].

    PubMed

    Burger-Heinrich, E

    1991-03-01

    In the years from 1970 to 1985 the "Belgian Archaeological Expedition to Iraq" excavated the remains of the ancient cultural and commercial centers Sippar and Sippar Amnanum. In connexion with this work it was possible to remove twelve human skeletons from the Persian and Hellenistic Period which are described here. PMID:1859195

  5. The Freeze-Drying of Wet and Waterlogged Materials from Archaeological Excavations

    ERIC Educational Resources Information Center

    Watson, Jacqui

    2004-01-01

    Large quantities of wood and leather have been found in the waterlogged layers on archaeological excavations. Centuries of burial, however, have left these materials in a very degraded and vulnerable state such that if they dry out they will fall apart. This paper discusses the physics behind the freeze-drying techniques that allow the…

  6. Characteristics of H2S emission from aged refuse after excavation exposure.

    PubMed

    Shen, Dong-Sheng; Du, Yao; Fang, Yuan; Hu, Li-Fang; Fang, Cheng-Ran; Long, Yu-Yang

    2015-05-01

    Hydrogen sulfide (H2S(g)) emission from landfills is a widespread problem, especially when aged refuse is excavated. H2S(g) emission from aged refuse exposed to air was investigated and the results showed that large amounts of H2S(g) can be released, especially in the first few hours after excavation, when H2S(g) concentrations in air near refuse could reach 2.00 mg m(-3). Initial exposure to air did not inhibit the emission of H2S(g), as is generally assumed, but actually promoted it. The amounts of H2S(g) emitted in the first 2 d after excavation can be very dangerous, and the risks associated with the emission of H2S(g) could decrease significantly with time. Unlike a large number of sulfide existed under anaerobic conditions, the sulfide in aged municipal solid waste can be oxidized chemically to elemental sulfur (but not sulfate) under aerobic conditions, and its conversion rate was higher than 80%. Only microorganisms can oxidize the reduced sulfur species to sulfate, and the conversion rate could reach about 50%. Using appropriate techniques to enhance these chemical and biological transformations could allow the potential health risks caused by H2S(g) after refuse excavation to be largely avoided. PMID:25725388

  7. Requirements Allocation Analysis for Test Alcoves Excavation and Layout CII: BABEAF000

    SciTech Connect

    E.F. Fitch

    1995-02-02

    The purpose and objective of this analysis are to allocate all Exploratory Studies Facility Design Requirements (ESFDR) (Reference 8.1) applicable to Configuration Item (CI) Test Alcoves Excavation and Layout, Configuration Item Identifier (CII) BABEAF000, for Exploratory Studies Facility (ESF) Design Package 2C.

  8. The Li(f)e of the Self: Missing Persons and Auto/Archeological Excavations

    ERIC Educational Resources Information Center

    Burdick, Jake

    2014-01-01

    This article describes and enacts a process of autobiographical inquiry, auto/archeology, which seeks to address problematic confluences of memory and identity in reconstructing one's historical narrative. Drawing on curriculum theory and Lacanian psychoanalysis, the author describes a process of excavation in which understandings of a prior…

  9. APPLICATION ANALYSIS REPORT - DEMONSTRATION OF A TRIAL EXCAVATION AT THE MCCOLL SUPERFUND SITE

    EPA Science Inventory

    In June 1990, the U.S. Environmental Protection Agency’s Region IX Superfund Program, in cooperation with EPA’s Air and Energy Engineering Research Laboratory (AEERL), and EPA’s Superfund Innovative Technology Evaluation (SITE) Program performed a trial excavation of approximatel...

  10. Creative spoil: Design concepts, construction techniques, and disposal of excavated materials

    NASA Astrophysics Data System (ADS)

    McLindon, Gerald J.

    1985-03-01

    The author discusses some of the construction methods used in building the Tennessee-Tombigbee Waterway, the disposal of surplus excavated materials, and the reclamation of disposal areas along the waterway Emphasis is placed on the steps taken to assure protection of natural resources and to promote overall environmental quality.

  11. Content Literacy for the 21st Century: Excavation, Elevation, and Relational Cosmopolitanism in the Classroom

    ERIC Educational Resources Information Center

    Damico, James S.; Baildon, Mark

    2011-01-01

    This article makes the a case for conceptualizing content literacy, especially in social studies, as inquiry-based social practices for understanding and addressing complex, multifaceted problems. Two core practices especially needed for a Web-dominated 21st century are then described--excavation and elevation. Next, these two practices are…

  12. Supplement analysis for paleontological excavation at the National Ignition Facility at Lawrence Livermore National Laboratory

    SciTech Connect

    1997-12-19

    On December 15, 1997, contractor workers supporting the National Ignition Facility (NIF) construction uncovered bones suspected to be of paleontological importance. The NIF workers were excavating a utility trench near the southwest corner of the NIF footprint area, located at the northeast corner of the Lawrence Livermore National Laboratory (LLNL) Livermore Site, and were excavating at a depth of approximately 30 feet. Upon the discovery of bone fragments, the excavation in the immediate vicinity was halted and the LLNL archaeologist was notified. The archaeologist determined that there was no indication of cultural resources. Mark Goodwin, Senior Curator for the University of California Museum of Paleontology at the University of California, Berkeley, was then contacted. Mr. Goodwin visited the site on December 16th and confirmed that the bones consisted of a section of the skull, a portion of the mandible, several teeth, upper palate, and possibly the vertebrae of a mammoth, genus Mammuthus columbi. This supplement analysis evaluates the potential for adverse impacts of excavating skeletal remains, an activity that was only generally assessed by the NIF Project-Specific Analysis in the Final Programmatic Environmental impact Statement for Stockpile Stewardship and Management (SS and M PEIS) published in September 1996 (DOE/EIS-0236) and its Record of Decision published on December 19, 1996. This supplement analysis has been prepared pursuant to the DOE regulations implementing the National Environmental Policy Act (10 CFR 1021.314).

  13. National advanced drilling and excavation technologies program: Summary of third meeting of interested Federal agencies

    SciTech Connect

    1993-12-07

    The purpose of the meeting was: (1) to discuss a proposal by the Massachusetts Institute of Technology (MIT) outlining a National Advanced Drilling and Excavation Technologies Program, (2) to brief participants on events since the last meeting, and (3) to hear about drilling research activities funded by the Department of Energy. The meeting agenda is included as Attachment B.

  14. Modeling the effect of executive device of a bucket-wheel excavator on the coal face

    SciTech Connect

    Zaitseva, A.A.; Cheskidov, V.I.; Zaitsev, G.D.

    2005-11-15

    An algorithm is proposed and substantiated to calculate the optimum trajectory of scooping for the dynamic bucket-wheel and stationary bucket excavators. The applicability of the developed program in determining mineral losses and impoverishment during selective and bulk-selective mining in bedded deposits is demonstrated.

  15. Blast-free mining of coal seams by excavators equipped with rotary dynamic buckets

    SciTech Connect

    Labutin, V.N.; Mattis, A.R.; Zaitseva, A.A.

    2005-04-01

    The necessity to equip cable excavators with rotary buckets is substantiated. The results of graphic-analytical analysis of the rotary bucket operation are presented, and its main advantages are determined in comparison with conventional buckets in mining coal seams of complex structure.

  16. Excavating, Trenching, and Shoring Safety. Module SH-38. Safety and Health.

    ERIC Educational Resources Information Center

    Center for Occupational Research and Development, Inc., Waco, TX.

    This student module on excavating, trenching, and shoring safety is one of 50 modules concerned with job safety and health. This module outlines the hazards of trenching and shoring and the procedures and equipment that should be employed to prevent cave-ins and other trenching and shoring accidents. Following the introduction, 10 objectives (each…

  17. 29 CFR 570.68 - Occupations in excavation operations (Order 17).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false Occupations in excavation operations (Order 17). 570.68 Section 570.68 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS CHILD LABOR REGULATIONS, ORDERS AND STATEMENTS OF INTERPRETATION Occupations Particularly Hazardous for the Employment of...

  18. Offsite radiological consequence analysis for the bounding unplanned excavation/drilling of 200 area soils

    SciTech Connect

    STEPHENS, L.S.

    2003-03-21

    This analysis calculates the offsite radiological consequence of the bounding unplanned excavation/drilling of 200 Area soils accident. The US. Department of Energy (DOE) standard DOE-STD-3009-94, ''Preparation Guide for U.S. Department of Energy Nonreactor Nuclear Facility Documented Safety Analyses'', requires the formal quantification of a limited subset of accidents representing a complete set of bounding conditions. The results of these analyses are then evaluated to determine if they challenge the DOE-STD-3009-94 Appendix A, ''Evaluation Guideline,'' of 25 rem total effective dose equivalent to identify and evaluate safety-class structures, systems, and components. This document supports the development of the unplanned excavation/drilling of 200 Area soils accident in the tank farm documented safety analysis. Consequently, it: (1) Provides a comprehensive review of potential unplanned excavation scenarios (i.e., backhoe, buried pressurized line ruptures, drilling, Guzzler vacuum) to determine the representative activity that would bound unmitigated, unplanned, or inadvertent excavations of 200 Area soils. (2) Evaluates radiological isotope inventories of all current Tank Farm Contractor (TFC) liquid waste disposal sites [i.e., cribs, ditches, and ponds (including French drains)], and isotope inventories of unplanned release sites (UPR) and plume columns. (3) Establishes the radiological consequences to the maximum offsite individual (MOI) from an unplanned/inadvertent 200 Area soil disturbance based on bounding site development and representative accident determination.

  19. Spatiotemporal patterns of fish assemblage structure in a river impounded by low-head dams

    USGS Publications Warehouse

    Gillette, David P.; Tiemann, Jeremy S.; Edds, David R.; Wildhaber, Mark L.

    2005-01-01

    We studied spatiotemporal patterns of fish assemblage structure in the Neosho River, Kansas, a system impounded by low-head dams. Spatial variation in the fish assemblage was related to the location of dams that created alternating lotic and lentic stream reaches with differing fish assemblages. At upstream sites close to dams, assemblages were characterized by species associated with deeper, slower-flowing habitat. Assemblages at sites immediately downstream from dams had higher abundance of species common to shallow, swift-flowing habitat. Temporal variation in assemblage structure was stronger than spatial variation, and was associated with fish life history events such as spawning and recruitment, as well as seasonal changes in environmental conditions. Our results suggest that low-head dams can influence spatial patterns of fish assemblage structure in systems such as the Neosho River and that such assemblages also vary seasonally.

  20. Benthic Macroinvertebrate Assemblages in the Near Coastal Zone of Lake Erie

    EPA Science Inventory

    Benthic macroinvertebrate assemblages have been used as indicators of ecological condition because their responses integrate localized environmental conditions of the sediments and overlying water. Assemblages of benthic invertebrates in the near coastal region are of particular...

  1. ECOREGIONS AND BENTHIC DIATOM ASSEMBLAGES IN MID-ATLANTIC HIGHLANDS STREAMS

    EPA Science Inventory

    Ecoregional differences in geology and hydrology may affect physical and chemical conditions in streams and, consequently, the species composition of algal assemblages. Stresses resulting from human disturbance, however, may constrain species membership in algal assemblages and ...

  2. Magnesite-bearing inclusion assemblage in natural diamond

    NASA Astrophysics Data System (ADS)

    Wang, Alian; Pasteris, Jill D.; Meyer, Henry O. A.; Dele-Duboi, Marie L.

    1996-06-01

    A significant mineral assemblage has been found as an inclusion in a natural diamond from the Finsch kimberlite pipe of South Africa: a euhedral rhombohedron-shaped magnesite (MgCO 3) crystal (d ˜ 30 μm) co-exists with several idiomorphic olivine [(Mg 1.86Fe 0.14)SiO 4] grains (d ˜ 80 μm). Many tiny anatase (TiO 2) particles (d ˜ 2-5 μm) and microcrystallites (d < 1 μm) of diamond and disordered graphite are attached to the surface of the magnesite grain. Structural and compositional characterization of the inclusion phases was achieved by micro-Raman spectroscopy and electron microprobe analysis. The occurrence of this syngenetic multiphase inclusion assemblage in a natural diamond provides unambiguous evidence for the existence in the Earth's mantle of magnesite, which has been proposed as a major carbon reservoir in most of the mantle. Both the formation and preservation aspects of the assemblage have been investigated. The mineralogy of the assemblage indicates that carbonated peridotite formed the surrounding petrologic environment. The inclusion assemblage suggests two reactions involving the decomposition of carbonates in mantle peridotite during decompression, which, in part, may explain the paucity of magnesite that has been found in other mantle rocks. The chemical inertness and low compressibility of the host diamond must have been critical to the preservation of this magnesite-bearing assemblage. The incorporation of a pure TiO 2 phase in a peridotitic diamond inclusion and its occurrence in the anatase structural form further emphasize the unusual conditions that allowed both the formation and preservation of this multiphase inclusion. The P-T-fO 2 conditions defined by the inclusion assemblage are represented by the intersection of the graphite-diamond transition curve and the enstatite-magnesite-olivine-diamond buffer. The oxygen fugacity range represented by the inclusion assemblage is below that of the quartz-fayalite-magnetite and C

  3. Ground Stabilization for foundation and excavation construction in Florida karst topography

    NASA Astrophysics Data System (ADS)

    Almaleh, L. J.; Grob, J. D.; Gorny, R. H.

    1993-12-01

    The construction of additional facilities at the Florida Power Corporation's Crystal River Energy Complex required an extensive stabilization program to construct foundations for approximately one half mile of cooling towers. This paper presents an overview of the techniques and methods used in the construction of additional facilities at the Crystal River Generating Station. Excavations for intake and discharge structures were to be more than 20 ft below the water table. Cooling tower foundations were constructed on extensively solutioned Florida limerock located on the central Gulf Coast of Florida. Hybrid ground modification techniques were used to stabilize soft or loose soils and solution features in the underlying limerock, allowing mat and spread footing foundations to be used for most of the facility. The ground modification techniques were used to detect, collapse, densify, and fill solution features below the structure foundations. The bearing capacity after ground modification was verified by field load tests. Subsurface investigations indicated that sheet pile excavations with grouted seals were the optimal technique for cofferdam excavations in the limerock formation. Existing collapsed caverns were encountered during construction of the cofferdam for the intake structure and the adjacent discharge structure, requiring a fast-track design change, considerable field coordination, and daily modifications to accommodate the varied conditions encountered. Tied-back soldier pile cofferdam construction was combined with grouting, underwater excavation, and a massive, unreinforced, concrete tremie slab with grouted anchors, and installed off a barge to provide a dewatered excavation. This project involved the use of hybrid soil-rock anchors to anchor one of the largest continuous placement tremie seals installed in Florida. Other excavations used sheeting and grouting of the underlying limerock formation to provide a dewatered excavation. Ground modification

  4. THE INFLUENCE OF SUBMERGED MACROPHYTES ON SEDIMENTARY DIATOM ASSEMBLAGES(1).

    PubMed

    Vermaire, Jesse C; Prairie, Yves T; Gregory-Eaves, Irene

    2011-12-01

    Submerged macrophytes are a central component of lake ecosystems; however, little is known regarding their long-term response to environmental change. We have examined the potential of diatoms as indicators of past macrophyte biomass. We first sampled periphyton to determine whether habitat was a predictor of diatom assemblage. We then sampled 41 lakes in Quebec, Canada, to evaluate whether whole-lake submerged macrophyte biomass (BiomEpiV) influenced surface sediment diatom assemblages. A multivariate regression tree (MRT) was used to construct a semiquantitative model to reconstruct past macrophyte biomass. We determined that periphytic diatom assemblages on macrophytes were significantly different from those on wood and rocks (ANOSIM R = 0.63, P < 0.01). A redundancy analysis (RDA) of the 41-lake data set identified BiomEpiV as a significant (P < 0.05) variable in structuring sedimentary diatom assemblages. The MRT analysis classified the lakes into three groups. These groups were (A) high-macrophyte, nutrient-limited lakes (BiomEpiV ≥525 μg · L(-1) ; total phosphorus [TP] <35 μg · L(-1) ; 23 lakes); (B) low-macrophyte, nutrient-limited lakes (BiomEpiV <525 μg · L(-1) ; TP <35 μg · L(-1) ; 12 lakes); and (C) eutrophic lakes (TP ≥35 μg · L(-1) ; six lakes). A semiquantitative model correctly predicted the MRT group of the lake 71% of the time (P < 0.001). These results suggest that submerged macrophytes have a significant influence on diatom community structure and that sedimentary diatom assemblages can be used to infer past macrophyte abundance. PMID:27020346

  5. Depth as an organizer of fish assemblages in floodplain lakes

    USGS Publications Warehouse

    Miranda, L.E.

    2011-01-01

    Depth reduction is a natural process in floodplain lakes, but in many basins has been accelerated by anthropogenic disturbances. A diverse set of 42 floodplain lakes in the Yazoo River Basin (Mississippi, USA) was examined to test the hypothesis of whether depth reduction was a key determinant of water quality and fish assemblage structure. Single and multiple variable analyses were applied to 10 commonly monitored water variables and 54 fish species. Results showed strong associations between depth and water characteristics, and between depth and fish assemblages. Deep lakes provided less variable environments, clearer water, and a wider range of microhabitats than shallow lakes. The greater environmental stability was reflected by the dominant species in the assemblages, which included a broader representation of large-body species, species less tolerant of extreme water quality, and more predators. Stability in deep lakes was further reflected by reduced among-lake variability in taxa representation. Fish assemblages in shallow lakes were more variable than deep lakes, and commonly dominated by opportunistic species that have early maturity, extended breeding seasons, small adult size, and short lifespan. Depth is a causal factor that drives many physical and chemical variables that contribute to organizing fish assemblages in floodplain lakes. Thus, correlations between fish and water transparency, temperature, oxygen, trophic state, habitat structure, and other environmental descriptors may ultimately be totally or partly regulated by depth. In basins undergoing rapid anthropogenic modifications, local changes forced by depth reductions may be expected to eliminate species available from the regional pool and could have considerable ecological implications. ?? 2010 Springer Basel AG (outside the USA).

  6. Scaled experimental study on excavation of lunar regolith with rakes/rippers and flat blade

    NASA Astrophysics Data System (ADS)

    Iai, Masafumi

    As humanity's activities expand to the Moon, Mars, and other extra-terrestrial bodies, it will be necessary to use local resources rather than bringing everything from the Earth. This concept is called In-Situ Resource Utilization (ISRU), which starts with excavation and earthmoving. The present study focuses on loosening and moving of the lunar regolith by a ripper (or rake) and a wide blade with consideration of gravel content. After characterizing the lunar regolith and two of its simulants (JSC-1A and FJS-1), the relationship between the excavation energy and different conditions, namely gravel content, relative density, and tine spacing on a rake, is investigated with scaled experiments. Geotechnical properties of JSC-1A were determined, in addition to the simulants' stress-strain relationships over a wide range of relative density (13% to near 100%). Gravel content of the lunar regolith, often overlooked in previous studies, is estimated based on the data of 11 Apollo cores, which reveals the maximum local gravel content is about 30% by weight. Also the grain size distribution of the lunar regolith up to 1 m grains is created by combining the data from Apollo and Surveyor missions. In the experiments, gravel (2 mm--10 mm) is added to JSC-1A In addition, a math model of the ripping force is developed as a function of material density, which could be the basis of an instrumented-ripper technique for detailed mapping of construction. Prior ripping decreases total excavation energy by up to 20% if the relative density is ≥ 60% and the gravel content is ≤ 10%. The optimal tine spacing for JSC-1A at a penetration depth of 30 mm is 30 mm. Even a gravel content of 5% increases the reaction force on excavation tools, which underlines the necessity of consideration of gravel content for lunar excavation planning.

  7. Identification of a novel Assemblage B subgenotype and a zoonotic Assemblage C in human isolates of Giardia intestinalis in Egypt.

    PubMed

    Soliman, R H; Fuentes, I; Rubio, J M

    2011-12-01

    Giardia intestinalis (G. intestinalis) is a flagellate parasite which has been considered the most common protozoan infecting human. Molecular techniques are of great value in studying the taxonomy, the zoonotic potential of animal isolates and the correlation between the genetic variability of the parasite and the range of clinical symptoms observed in humans. The present work aims at genotyping G. intestinalis isolates from Egypt using molecular techniques. PCR targeting the β-giardin locus, RFLP and sequencing were applied to 12 microscopically positive and 3 microscopically negative samples (which were positive by real time PCR targeting SSUr DNA). Two other loci, triose phosphate isomerase (TPI) gene and glutamate dehydrogenase (GDH) gene PCR and RFLP were also applied to all study isolates. The most frequent genotype was Assemblage B (13 out of 15), while Assemblage A and C were present in one sample each. This is the first report on zoonotic transmission of Assemblage C (dog genotype) to human in Egypt. Sequencing of the Assemblage B isolates revealed new subgenotypes with consistent mutations at specific positions, some of which were not characterized previously. The results shed light on the possibility that G. intestinalis can infect humans through a zoonotic route and open the door to wider investigations using different genetic loci to genotype Giardia isolates. PMID:21989040

  8. Protocol for Monitoring Fish Assemblages in Pacific Northwest National Parks

    USGS Publications Warehouse

    Brenkman, Samuel J.; Connolly, Patrick J.

    2008-01-01

    Rivers and streams that drain from Olympic, Mount Rainier, and North Cascades National Parks are among the most protected corridors in the lower 48 States, and represent some of the largest tracts of contiguous, undisturbed habitat throughout the range of several key fish species of the Pacific Northwest. These watersheds are of high regional importance as freshwater habitat sanctuaries for native fish, where habitat conditions are characterized as having little to no disturbance from development, channelization, impervious surfaces, roads, diversions, or hydroelectric projects. Fishery resources are of high ecological and cultural importance in Pacific Northwest National Parks, and significantly contribute to economically important recreational, commercial, and tribal fisheries. This protocol describes procedures to monitor trends in fish assemblages, fish abundance, and water temperature in eight rivers and five wadeable streams in Olympic National Park during summer months, and is based on 4 years of field testing. Fish assemblages link freshwater, marine, and terrestrial ecosystems. They also serve as focal resources of national parks and are excellent indicators of ecological conditions of rivers and streams. Despite the vital importance of native anadromous and resident fish populations, there is no existing monitoring program for fish assemblages in the North Coast and Cascades Network. Specific monitoring objectives of this protocol are to determine seasonal and annual trends in: (1) fish species composition, (2) timing of migration of adult fish, (3) relative abundance, (4) age and size structure, (5) extent of non-native and hatchery fish, and (6) water temperature. To detect seasonal and annual trends in fish assemblages in reference sites, we rely on repeated and consistent annual sampling at each monitoring site. The general rationale for the repeated sampling of reference sites is to ensure that we account for the high interannual variability in fish

  9. Acoustic emission and ultrasonic-velocity methods used to characterise the excavation disturbance associated with deep tunnels in hard rock

    NASA Astrophysics Data System (ADS)

    Falls, Stephen D.; Young, R. Paul

    1998-04-01

    Acoustic emission (AE) and ultrasonic-velocity monitoring studies have been undertaken at both the Atomic Energy of Canada Limited (AECL) Underground Research Laboratory (URL) and at the Swedish Nuclear Fuel Waste Management Company (SKB) Hard Rock Laboratory (HRL). At both locations the excavations were tunnels in granitic material at approximately 420 m depth. However, the stress regime was more severe at the URL Mine-by tunnel site than the HRL ZEDEX tunnel. Different parts of the ZEDEX tunnel were created using different excavation techniques. Using AE and ultrasonic techniques to study these tunnels we have been able to examine the nature of the excavation-disturbed zone around the tunnel, as well as examining the effects of different stress regimes and excavation techniques. Studies were undertaken both during and after the Mine-by tunnel excavation and during excavation in the ZEDEX tunnel. AE monitoring in the wall of the Mine-by tunnel during excavation showed that some activity occurred in the sidewall regions, but the spatial density of AE hypocentres increased toward the regions in the floor and roof of the tunnel where breakout notches formed. This sidewall activity was clustered primarily within 0.5 m of the tunnel wall. AE monitoring in the floor of the tunnel showed that small numbers of AE continued to occur in the notch region in the floor of the tunnel over 2 years after excavation was completed. This activity became more acute as the rock was heated, imposing thermally induced stresses on the volume. Ultrasonic-velocity studies both in the floor and the wall of the tunnel showed that the velocity is strongly anisotropic with the direction of slowest velocity orthogonal to the tunnel surface. The velocity increased with distance into the rock from the tunnel surface. In the floor, this effect was seen up to 2 m from the tunnel surface. Most of the change occurred within the first 0.5 m from the tunnel perimeter. At the lower-stress HRL, most of

  10. Archaeological Excavation Report for Proposed Well 199-K-131 in Support of the 100-KR-4 Pump-and-Treat Project

    SciTech Connect

    Woody, Dave M.; Prendergast-Kennedy, Ellen L.

    2004-06-22

    An archaeological excavation was conducted at the site of proposed groundwater monitoring well 199-K-131 in support of the 100-KR-4 Pump-and-Treat Project between June 2 and 3, 2004. Excavations confirmed that there were no intact cultural deposits at the proposed well location. This report was prepared to document the findings of the test excavation.

  11. A Top Pilot Tunnel Preconditioning Method for the Prevention of Extremely Intense Rockbursts in Deep Tunnels Excavated by TBMs

    NASA Astrophysics Data System (ADS)

    Zhang, Chuanqing; Feng, Xiating; Zhou, Hui; Qiu, Shili; Wu, Wenping

    2012-05-01

    The headrace tunnels at the Jinping II Hydropower Station cross the Jinping Mountain with a maximum overburden depth of 2,525 m, where 80% of the strata along the tunnels consist of marble. A number of extremely intense rockbursts occurred during the excavation of the auxiliary tunnels and the drainage tunnel. In particular, a tunnel boring machine (TBM) was destroyed by an extremely intense rockburst in a 7.2-m-diameter drainage tunnel. Two of the four subsequent 12.4-m-diameter headrace tunnels will be excavated with larger size TBMs, where a high risk of extremely intense rockbursts exists. Herein, a top pilot tunnel preconditioning method is proposed to minimize this risk, in which a drilling and blasting method is first recommended for the top pilot tunnel excavation and support, and then the TBM excavation of the main tunnel is conducted. In order to evaluate the mechanical effectiveness of this method, numerical simulation analyses using the failure approaching index, energy release rate, and excess shear stress indices are carried out. Its construction feasibility is discussed as well. Moreover, a microseismic monitoring technique is used in the experimental tunnel section for the real-time monitoring of the microseismic activities of the rock mass in TBM excavation and for assessing the effect of the top pilot tunnel excavation in reducing the risk of rockbursts. This method is applied to two tunnel sections prone to extremely intense rockbursts and leads to a reduction in the risk of rockbursts in TBM excavation.

  12. Assemblage time series reveal biodiversity change but not systematic loss.

    PubMed

    Dornelas, Maria; Gotelli, Nicholas J; McGill, Brian; Shimadzu, Hideyasu; Moyes, Faye; Sievers, Caya; Magurran, Anne E

    2014-04-18

    The extent to which biodiversity change in local assemblages contributes to global biodiversity loss is poorly understood. We analyzed 100 time series from biomes across Earth to ask how diversity within assemblages is changing through time. We quantified patterns of temporal α diversity, measured as change in local diversity, and temporal β diversity, measured as change in community composition. Contrary to our expectations, we did not detect systematic loss of α diversity. However, community composition changed systematically through time, in excess of predictions from null models. Heterogeneous rates of environmental change, species range shifts associated with climate change, and biotic homogenization may explain the different patterns of temporal α and β diversity. Monitoring and understanding change in species composition should be a conservation priority. PMID:24744374

  13. A new Lower Triassic ichthyopterygian assemblage from Fossil Hill, Nevada

    PubMed Central

    Motani, Ryosuke; Embree, Patrick; Orchard, Michael J.

    2016-01-01

    We report a new ichthyopterygian assemblage from Lower Triassic horizons of the Prida Formation at Fossil Hill in central Nevada. Although fragmentary, the specimens collected so far document a diverse fauna. One partial jaw exhibits isodont dentition with blunt tipped, mesiodistally compressed crowns and striated enamel. These features are shared with the Early Triassic genus Utatsusaurus known from coeval deposits in Japan and British Columbia. An additional specimen exhibits a different dentition characterized by relatively small, rounded posterior teeth resembling other Early Triassic ichthyopterygians, particularly Grippia. This Nevada assemblage marks a southward latitudinal extension for Early Triassic ichthyopterygians along the eastern margin of Panthalassa and indicates repeated trans-hemispheric dispersal events in Early Triassic ichthyopterygians. PMID:26855868

  14. Power is sweet: sugarcane in the global ethanol assemblage.

    PubMed

    Hollander, Gail

    2010-01-01

    New alliances between Brazil and the US for ethanol production, transport, and trade are revitalising and expanding the centuries -old sugarcane plantation system in the Americas. In this paper I adopt the concept of global assemblages, building on the work of Aihwa Ong, Stephen Collier, and Saskia Sassen, to draw the contours of an "ethanol assemblage," which includes states, corporations, growers, technologies, urban consumers, and rural communities and landscapes. Though important to conceptualise agrofuels as a global phenomenon, it is also necessary to recognise the distinct regional patterns that cohere around various aspects of this polymorphous industry. Therefore, I focus on alliances around sugarcane ethanol, paying particular attention to the role of Miami as a global city serving as a gateway to information, investment, and commodities for the public/private and national/transnational entities that are engaged in the hemispheric project of ethanol promotion, production and distribution. PMID:20873028

  15. Niche conservatism constrains Australian honeyeater assemblages in stressful environments.

    PubMed

    Miller, E T; Zanne, A E; Ricklefs, R E

    2013-09-01

    The hypothesis of phylogenetic niche conservatism proposes that most extant members of a clade remain in ancestral environments because expansion into new ecological space imposes a selectional load on a population. A prediction that follows is that local assemblages contain increasingly phylogenetically clustered subsets of species with increasing difference from the ancestral environment of a clade. We test this in Australian Meliphagidae, a continental radiation of birds that originated in wet, subtropical environments, but subsequently spread to drier environments as Australia became more arid during the late Cenozoic. We find local assemblages are increasingly phylogenetically clustered along a gradient of decreasing precipitation. The pattern is less clear along a temperature gradient. We develop a novel phyloclimatespace to visualise the expansion of some lineages into drier habitats. Although few species extend into arid regions, those that do occupy larger ranges and thus local species richness does not decline predictably with precipitation. PMID:23848846

  16. A new Lower Triassic ichthyopterygian assemblage from Fossil Hill, Nevada.

    PubMed

    Kelley, Neil P; Motani, Ryosuke; Embree, Patrick; Orchard, Michael J

    2016-01-01

    We report a new ichthyopterygian assemblage from Lower Triassic horizons of the Prida Formation at Fossil Hill in central Nevada. Although fragmentary, the specimens collected so far document a diverse fauna. One partial jaw exhibits isodont dentition with blunt tipped, mesiodistally compressed crowns and striated enamel. These features are shared with the Early Triassic genus Utatsusaurus known from coeval deposits in Japan and British Columbia. An additional specimen exhibits a different dentition characterized by relatively small, rounded posterior teeth resembling other Early Triassic ichthyopterygians, particularly Grippia. This Nevada assemblage marks a southward latitudinal extension for Early Triassic ichthyopterygians along the eastern margin of Panthalassa and indicates repeated trans-hemispheric dispersal events in Early Triassic ichthyopterygians. PMID:26855868

  17. Barrier backbeach shell assemblages from the central Texas Gulf Coast

    SciTech Connect

    Albertzart, L.S.; Wilkinson, B.H. )

    1990-08-01

    Lateral variation in the abundance, taxonomic composition and amount of abrasion of approximately 14,000 mollusc shells, from 135 km of backbeach along Matagorda Island and Matagorda Peninsula of the central Texas coast, primarily reflect long-term patterns of shoreline progradation and recession. Disarticulated shell is concentrated as a gravel lag during landward transport of barrier island/peninsula sediment from storm washover and during lateral transport by fairweather longshore currents. Taxonomic dominance within any backbeach area directly relates to long-term Holocene patterns of shoreline migration. Shell along progradational Matagorda Island is largely derived from gulfward shoreface communities and valves of normal marine species are predominant. Shell along recessive beaches of Matagorda Peninsula, on the other hand, is primarily derived from the erosion of older bay-estuarine facies now exposed to shoreface currents, and values of brackish lagoonal species are predominant. Degree of valve abrasion reflects both the residence time of shell in shoreface settings and occurrence of shell with coarse, poorly sorted sediment. Central Texas coast backbeach molluscan death assemblages largely reflect a time-averaged census of both living communities and older shell assemblages that are sampled over an along-shore length of several kilometers and over a shore-to-basin distance of several hundred meters. These assemblages, accumulated over a time span of several thousand years, reflect the spatial and the temporal proximity of specific sedimentary environments to sites of sediment accumulation. Backbeach shell assemblages record both the ecologic preference of individual taxonomic groups to specific environmental parameters as well as the dominant processes of sediment transport in littoral depositional systems.

  18. Characterizing lentic freshwater fish assemblages using multiple sampling methods

    USGS Publications Warehouse

    Fischer, Jesse R.; Quist, Michael

    2014-01-01

    Characterizing fish assemblages in lentic ecosystems is difficult, and multiple sampling methods are almost always necessary to gain reliable estimates of indices such as species richness. However, most research focused on lentic fish sampling methodology has targeted recreationally important species, and little to no information is available regarding the influence of multiple methods and timing (i.e., temporal variation) on characterizing entire fish assemblages. Therefore, six lakes and impoundments (48–1,557 ha surface area) were sampled seasonally with seven gear types to evaluate the combined influence of sampling methods and timing on the number of species and individuals sampled. Probabilities of detection for species indicated strong selectivities and seasonal trends that provide guidance on optimal seasons to use gears when targeting multiple species. The evaluation of species richness and number of individuals sampled using multiple gear combinations demonstrated that appreciable benefits over relatively few gears (e.g., to four) used in optimal seasons were not present. Specifically, over 90 % of the species encountered with all gear types and season combinations (N = 19) from six lakes and reservoirs were sampled with nighttime boat electrofishing in the fall and benthic trawling, modified-fyke, and mini-fyke netting during the summer. Our results indicated that the characterization of lentic fish assemblages was highly influenced by the selection of sampling gears and seasons, but did not appear to be influenced by waterbody type (i.e., natural lake, impoundment). The standardization of data collected with multiple methods and seasons to account for bias is imperative to monitoring of lentic ecosystems and will provide researchers with increased reliability in their interpretations and decisions made using information on lentic fish assemblages.

  19. Bacterial assemblages in rivers and billabongs of Southeastern Australia.

    PubMed

    Boon, P I

    1991-12-01

    Billabongs, lentic waterbodies common to the floodplain of Australian rivers, differ considerably from the lotic riverine environment in terms of hydrology, physiochemical characteristics, and biological assemblages present. As little is known regarding the bacterial ecology of billabong habitats, a comparison was made of the bacterial assemblages in the water column of seven paired river/billabong sites in the Murray-Darling Basin of southeastern Australia. Billabongs supported larger populations of bacteria (1-157×10(9) cells liter(-1); 11-10,270 μg C liter(-1)) than did rivers (1-10×10(9) cells liter(-1); 6-143 μg C liter(-1)). Phospholipid analyses confirmed that billabongs (14-111 μg phospholipid fatty acid liter(-1)) had larger bacterial populations than rivers (<12 μg liter(-1)). Bacterial production, measured with(3)H-leucine, was also greater in billabongs (0.28-3.05 μg C liter(-1) hour(-1)) than rivers (0.05-0.62 μg C liter(-1) hour(-1)). Production calculated from the frequency of dividing cells confirmed this conclusion, and suggested bacterial production in some billabongs could exceed 100 μg C liter(-1) hour(-1). An INT-formazan method indicated that usually <25% of bacterial cells were active in either habitat, but this was probably an underestimate of the bona fide value. Turnover times of glucose were usually shorter in billabongs, and the cell-specific activity greater for billabong than river assemblages. The factors most likely to be responsible for the differences between the bacterial assemblages in rivers and billabongs relate to hydrological regime and the availability of organic carbon substrates. PMID:24194324

  20. Nestedness in centipede (Chilopoda) assemblages on continental islands (Aegean, Greece)

    NASA Astrophysics Data System (ADS)

    Simaiakis, Stylianos Michail; Martínez-Morales, Miguel Angel

    2010-05-01

    In natural ecosystems, species assemblages among isolated ecological communities such as continental islands often show a nested pattern in which biotas of sites with low species richness are non-random subsets of biotas of richer sites. The distribution of centipede (Chilopoda) species in the central and south Aegean archipelago was tested for nestedness. To achieve this aim we used distribution data for 53 species collected on 24 continental Aegean islands (Kyklades and Dodekanisa). Based on the first-order jackknife estimator, most of islands were comprehensively surveyed. In order to quantify nestedness, we used the nestedness temperature calculator (NTC) as well as the nestedness metric based on overlap and decreasing Fill (NODF). NTC indicated that data exhibited a high degree of nestedness in the central and south Aegean island complexes. As far as the Kyklades and Dodekanisa are concerned, NTC showed less nested centipede structures than the 24 islands. Likewise, NODF revealed a significant degree of nestedness in central and south Aegean islands. It also showed that biotas matrices without singletons were more nested than the complete ones (Aegean, Kyklades and Dodekanisa). The two commonest centipede taxa (lithobiomorphs and geophilomorphs) contributed differently to centipede assemblages. In the Kyklades and Dodekanisa, geophilomorphs did not show a reliable nested arrangement unlike lithobiomorphs. In relation to the entire data set, nestedness was positively associated with the degree of isolation. In the Kyklades altitudinal range best explained nestedness patterns, while in Dodekanisa habitat heterogeneity proved to be more important for the centipede communities. Island area does not seem to be a significant explanatory variable. Some of our results from the Kyklades were critically compared with those for terrestrial isopod and land snail nested assemblages from the same geographical area. The complex geological and palaeogeographical history of

  1. Macromolecular Assemblage in the Design of a Synthetic AIDS Vaccine

    NASA Astrophysics Data System (ADS)

    Defoort, Jean-Philippe; Nardelli, Bernardetta; Huang, Wolin; Ho, David D.; Tam, James P.

    1992-05-01

    We describe a peptide vaccine model based on the mimicry of surface coat protein of a pathogen. This model used a macromolecular assemblage approach to amplify peptide antigens in liposomes or micelles. The key components of the model consisted of an oligomeric lysine scaffolding to amplify peptide antigens covalently 4-fold and a lipophilic membrane-anchoring group to further amplify noncovalently the antigens many-fold in liposomal or micellar form. A peptide antigen derived from the third variable domain of glycoprotein gp120 of human immunodeficiency virus type 1 (HIV-1), consisting of neutralizing, T-helper, and T-cytotoxic epitopes, was used in a macromolecular assemblage model (HIV-1 linear peptide amino acid sequence 308-331 in a tetravalent multiple antigen peptide system linked to tripalmitoyl-S-glycerylcysteine). The latter complex, in liposome or micelle, was used to immunize mice and guinea pigs without any adjuvant and found to induce gp120-specific antibodies that neutralize virus infectivity in vitro, elicit cytokine production, and prime CD8^+ cytotoxic T lymphocytes in vivo. Our results show that the macromolecular assemblage approach bears immunological mimicry of the gp120 of HIV virus and may lead to useful vaccines against HIV infection.

  2. Temporal changes of a macrobenthic assemblage in harsh lagoon sediments

    NASA Astrophysics Data System (ADS)

    Como, Serena; Magni, Paolo

    2009-08-01

    An opportunistic macrobenthic assemblage was studied from 2001 to 2003 in a central area of the Cabras lagoon (western Sardinia, Italy), known to be affected by environmental disturbances (i.e. organic over-enrichment of sediments, and episodic events of hypoxia/anoxia and sulphide development). We identified recurrent seasonal changes in this macrobenthic assemblage, with a general impoverishment in summer and a recovery in winter/spring. The nereids Neanthes succinea and Hediste diversicolor were found to replace the spionid Polydora ciliata as the most dominant species in the summer for 3 consecutive years. Occasional, unsynchronized appearances of small-sized deposit feeders, such as Tubificidae, Capitella cf. capitata, chironomid larvae and Hydrobia spp., were observed in winter/spring. We suggest that these changes are driven by the interplay of environmental conditions (worse in summer) with numerous biotic factors. This includes different tolerance levels of taxa to low oxygen concentrations and sulphides, variability in larval supply and post-larval transport, as well as competition for space and food between and within different functional groups, and facilitation through animal bioturbation and sediment reoxidation. A conceptual model is proposed to demonstrate how environmental conditions and biotic interactions may control the benthic assemblage in such a harsh lagoon environment.

  3. Unlocking the bacterial and fungal communities assemblages of sugarcane microbiome

    PubMed Central

    de Souza, Rafael Soares Correa; Okura, Vagner Katsumi; Armanhi, Jaderson Silveira Leite; Jorrín, Beatriz; Lozano, Núria; da Silva, Márcio José; González-Guerrero, Manuel; de Araújo, Laura Migliorini; Verza, Natália Cristina; Bagheri, Homayoun Chaichian; Imperial, Juan; Arruda, Paulo

    2016-01-01

    Plant microbiome and its manipulation herald a new era for plant biotechnology with the potential to benefit sustainable crop production. However, studies evaluating the diversity, structure and impact of the microbiota in economic important crops are still rare. Here we describe a comprehensive inventory of the structure and assemblage of the bacterial and fungal communities associated with sugarcane. Our analysis identified 23,811 bacterial OTUs and an unexpected 11,727 fungal OTUs inhabiting the endophytic and exophytic compartments of roots, shoots, and leaves. These communities originate primarily from native soil around plants and colonize plant organs in distinct patterns. The sample type is the primary driver of fungal community assemblage, and the organ compartment plays a major role in bacterial community assemblage. We identified core bacterial and fungal communities composed of less than 20% of the total microbial richness but accounting for over 90% of the total microbial relative abundance. The roots showed 89 core bacterial families, 19 of which accounted for 44% of the total relative abundance. Stalks are dominated by groups of yeasts that represent over 12% of total relative abundance. The core microbiome described here comprise groups whose biological role underlies important traits in plant growth and fermentative processes. PMID:27358031

  4. Unlocking the bacterial and fungal communities assemblages of sugarcane microbiome.

    PubMed

    de Souza, Rafael Soares Correa; Okura, Vagner Katsumi; Armanhi, Jaderson Silveira Leite; Jorrín, Beatriz; Lozano, Núria; da Silva, Márcio José; González-Guerrero, Manuel; de Araújo, Laura Migliorini; Verza, Natália Cristina; Bagheri, Homayoun Chaichian; Imperial, Juan; Arruda, Paulo

    2016-01-01

    Plant microbiome and its manipulation herald a new era for plant biotechnology with the potential to benefit sustainable crop production. However, studies evaluating the diversity, structure and impact of the microbiota in economic important crops are still rare. Here we describe a comprehensive inventory of the structure and assemblage of the bacterial and fungal communities associated with sugarcane. Our analysis identified 23,811 bacterial OTUs and an unexpected 11,727 fungal OTUs inhabiting the endophytic and exophytic compartments of roots, shoots, and leaves. These communities originate primarily from native soil around plants and colonize plant organs in distinct patterns. The sample type is the primary driver of fungal community assemblage, and the organ compartment plays a major role in bacterial community assemblage. We identified core bacterial and fungal communities composed of less than 20% of the total microbial richness but accounting for over 90% of the total microbial relative abundance. The roots showed 89 core bacterial families, 19 of which accounted for 44% of the total relative abundance. Stalks are dominated by groups of yeasts that represent over 12% of total relative abundance. The core microbiome described here comprise groups whose biological role underlies important traits in plant growth and fermentative processes. PMID:27358031

  5. Brood size modifications affect plumage bacterial assemblages of European starlings.

    PubMed

    Lucas, Françoise S; Moureau, Benoit; Jourdie, Violaine; Heeb, Philipp

    2005-02-01

    During reproduction, birds face trade-offs between time and energy devoted to parental effort and traits associated with self-maintenance. We manipulated brood sizes to investigate the effects of such trade-offs on feather bacterial densities and the structure of bacterial assemblages on feathers in adult European starlings, Sturnus vulgaris, and in vitro feather degradation. As predicted by a trade-off between parental effort and self-maintenance, we found that birds with enlarged broods had more free-living bacteria on their feathers than birds with reduced broods. Furthermore, we found a significant interaction between brood manipulation and original brood size on free-living bacterial densities suggesting that the trade-off is mediated by the adults' initial reproductive investment. In contrast, brood size manipulations had no significant effect on densities of attached bacteria. Using ribosomal intergenic spacer analysis (RISA), we demonstrated that brood manipulations significantly modified the structure (band pattern) of feather-degrading bacterial assemblages, but had no significant effect on their richness (number of bands) or the in vitro feather degradation. In vitro feather degradation varied in relation to the premanipulation brood size and positively with the richness of the feather degrading bacterial community. Besides brood manipulation effect, we found that ecological factors and individual traits, such as the age, the nest location or the capture date, shaped bacterial assemblages and feather degradation capacities. PMID:15660952

  6. Historic changes in fish assemblage structure in midwestern nonwadeable rivers

    USGS Publications Warehouse

    Parks, Timothy P.; Quist, Michael C.; Pierce, Clay L.

    2014-01-01

    Historical change in fish assemblage structure was evaluated in the mainstems of the Des Moines, Iowa, Cedar, Wapsipinicon, and Maquoketa rivers, in Iowa. Fish occurrence data were compared in each river between historical and recent time periods to characterize temporal changes among 126 species distributions and assess spatiotemporal patterns in faunal similarity. A resampling procedure was used to estimate species occurrences in rivers during each assessment period and changes in species occurrence were summarized. Spatiotemporal shifts in species composition were analyzed at the river and river section scale using cluster analysis, pairwise Jaccard's dissimilarities, and analysis of multivariate beta dispersion. The majority of species exhibited either increases or declines in distribution in all rivers with the exception of several “unknown” or inconclusive trends exhibited by species in the Maquoketa River. Cluster analysis identified temporal patterns of similarity among fish assemblages in the Des Moines, Cedar, and Iowa rivers within the historical and recent assessment period indicating a significant change in species composition. Prominent declines of backwater species with phytophilic spawning strategies contributed to assemblage changes occurring across river systems.

  7. Effects of chemical disturbances on intertidal benthic assemblages.

    PubMed

    Mayer-Pinto, Mariana; Ignacio, Barbara Lage

    2015-02-15

    Contamination is a particular harmful type of chemical disturbance and predicting their effects on natural systems is very complex. Effects of disturbances vary in space and time and depend, among other things, on the type and age of organisms, the habitat being studied and the complex interactions occurring in the systems. Most impact analyses of contaminants are however still done with limited number of selected organisms under laboratory conditions. Manipulative experiments done in situ are important to measure ecologically relevant responses of contaminant effects on marine systems. Ecological approaches on contamination studies, accounting for interactions among species and the environment are essential to understand how such disturbances affect systems. We evaluated the effects of bleach and permethrin, two common and pervasive contaminants, on intertidal benthic assemblages in two different successional stages, mature and young. There were no impacts on the overall structure of assemblages, regardless of their age. The lack of effects on the structure of assemblages might be due to the intrinsic characteristic of the habitat studied, which provide few sinks for contaminants, as well as the inherent features of the organisms themselves. Bleach did cause, however, a decrease in the abundance of limpets, which can have further consequences to these systems. This study shows the importance of studies on chemical disturbances done under relevant natural scenarios and that efficient management policies of natural systems will only achieve successful responses with properly designed experiments under natural conditions. PMID:25460934

  8. PCBs in the fish assemblage of a southern European estuary

    NASA Astrophysics Data System (ADS)

    Baptista, Joana; Pato, Pedro; Pereira, Eduarda; Duarte, Armando C.; Pardal, Miguel A.

    2013-02-01

    The Mondego estuary fish assemblage was studied for the accumulation of PCBs. Three sampling stations were visited along an estuarine salinity gradient, and, in total, 15 species were collected. Analysis of PCBs revealed no significant differences among the sampling stations, although differences were observed among the fish assemblages. Fish assemblages could be divided into three groups. The first group comprised those with higher concentration (more than 10 ng g- 1, dw), included the species Gobius niger, Sardina pilchardus, Anguilla anguilla, Pomatoschistus microps, Chelidonichthys lucerna and Liza ramada; the second group with medium concentration (5-10 ng g- 1, dw), included the species Pomatoschistus minutus, Dicentrarchus labrax, Atherina presbyter, Chelon labrosus, Diplodus vulgaris, Platichthys flesus and Cilata mustela; and a third group with low concentration (less than 5 ng g- 1, dw), included the species Solea solea and Callionymus lyra. A positive correlation was found between lipid content and PCB concentrations. To evaluate the influence of the residence time of species on the accumulation of PCBs, species were divided into two groups: species that spend more than 3 years in the estuary, and species that spend less than 3 years in the estuary. Species that spend more than 3 years in the estuary presented higher concentrations than species that spend less than 3 years in the estuary. CBs 138 and 153 had higher concentration, and tended to increase with time spent in the estuary.

  9. Minimizing soil remediation volume through specification of excavation and materials handling procedures

    SciTech Connect

    Oresik, W.L.S.; Otten, M.T.; Nelson, M.D.

    1994-12-31

    The technologies currently available for treating soils contaminated with the explosives 2,4,6-trinitroluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazene (RDX) are both limited and expensive. Therefore, an important consideration in soils remediation is the preparation of construction specifications and contract drawings which limit the volume of soil that will be required to undergo treatment. Construction specifications and contract drawings were developed for the Contaminated Soil Remediation of the Explosives Washout Lagoons at Umatilla Depot Activity (UMDA) with the following primary objectives: (1) limit the volume of soil excavated from the Explosives Washout Lagoons and Explosives Washout Plant Areas, (2) minimize materials handling, and (3) reduce the excavated volume of soil which will undergo treatment.

  10. Excavating silences and tensions of agency|passivity in science education reform

    NASA Astrophysics Data System (ADS)

    Rivera Maulucci, Maria S.

    2010-12-01

    I reflect on studies by Rodriguez and Carlone, Haun-Frank, and Kimmel to emphasize the ways in which they excavate silences in the science education literature related to linguistic and cultural diversity and situating the problem of reform in teachers rather than contextual factors, such as traditional schooling discourses and forces that serve to marginalize science. I propose that the current push for top-down reform and accountability diminishes opportunities for receptivity, learning with and from students in order to transform teachers' practices and promote equity in science education. I discuss tensions of agency and passivity in science education reform and argue that attention to authentic caring constitutes another silence in the science education literature. I conclude that the current policy context positions teachers and science education researchers as tempered radicals struggling against opp(reg)ressive reforms and that there is a need for more studies to excavate these and other silences.

  11. Application of full-face round by the sequential blasting machine in tunnel excavation

    SciTech Connect

    Cho, Y.D.; Park, B.K.; Lee, S.E.; Lim, H.U.

    1995-12-31

    Many methods and techniques have been developed to reduce ground vibrations. Some of them are an adoption of electric millisecond detonators with a sequential blasting machine and an improvement of initiating system with an adequate number of delay intervals. To reduce the level of ground vibration in tunnel excavation, the sequential blasting machine (S.B.M.) with decisecond detonators was adopted. A total of 134 blasts was recorded at various sites and the results were analyzed. The distances blast-to-structures were ranged from 20.3 to 42.0 meter, where charge weights were varied from 0.25 to 0.75kg per delay. It is proved that the sequential blasting in tunnel excavation is very effective to control ground vibration.

  12. Presence of a radioactive gas in archaeological excavations, determination and mitigation.

    PubMed

    Balcázar, M; Gómez, S; Peña, P; Zavala Arredondo, J; Gazzola, J; Villamares, A

    2014-01-01

    During recent archaeological discovery and excavation of a tunnel build approximately 2000 years ago by the Teotihuacans under the feathered serpent temple, in Mexico, abnormal radon concentrations up to 700 Bq m(-3) were measured at several excavation stages. The tunnel is at 15m below the earth surface with a vertical rectangular entrance of 4×4 m(2), a semi cylindrical shape of 3m in diameter, with a probable length of 100 m. This study supports the assumption that at the opening of the tunnel radon concentration was around 5500 Bq m(-3); however, although natural convection in the tunnel atmosphere naturally pups radon out, it build up to a maximum concentration of 2000 Bq m(-3). This paper presents the identification of the radon problem in this archaeological site, dose determination, and the mitigation actions that reduced the radon concentration down to 40 Bq m(-3) that ensure a negligible radon risk for archaeologist. PMID:23938077

  13. Regolith Advanced Surface Systems Operations Robot (RASSOR) Phase 2 and Smart Autonomous Sand-Swimming Excavator

    NASA Technical Reports Server (NTRS)

    Sandy, Michael

    2015-01-01

    The Regolith Advanced Surface Systems Operations Robot (RASSOR) Phase 2 is an excavation robot for mining regolith on a planet like Mars. The robot is programmed using the Robotic Operating System (ROS) and it also uses a physical simulation program called Gazebo. This internship focused on various functions of the program in order to make it a more professional and efficient robot. During the internship another project called the Smart Autonomous Sand-Swimming Excavator was worked on. This is a robot that is designed to dig through sand and extract sample material. The intern worked on programming the Sand-Swimming robot, and designing the electrical system to power and control the robot.

  14. Black liquor and the hangover effect: fish assemblage recovery dynamics following a pulse disturbance.

    PubMed

    Piller, Kyle R; Geheber, Aaron D

    2015-06-01

    Anthropogenic perturbations impact aquatic systems causing wide-ranging responses, from assemblage restructuring to assemblage recovery. Previous studies indicate the duration and intensity of disturbances play a role in the dynamics of assemblage recovery. In August 2011, the Pearl River, United States, was subjected to a weak black liquor spill from a paper mill which resulted in substantial loss of fish in a large stretch of the main channel. We quantified resilience and recovery of fish assemblage structure in the impacted area following the event. We compared downstream (impacted) assemblages to upstream (unimpacted) assemblages to determine initial impacts on structure. Additionally, we incorporated historic fish collections (1988-2011) to examine impacts on assemblage structure across broad temporal scales. Based on NMDS, upstream and downstream sites generally showed similar assemblage structure across sample periods with the exception of the 2 months postdischarge, where upstream and downstream sites visually differed. Multivariate analysis of variance (PERMANOVA) indicated significant seasonal variation among samples, but found no significant interaction between impacted and unimpacted assemblages following the discharge event. However, multivariate dispersion (MVDISP) showed greater variance among assemblage structure following the discharge event. These results suggest that 2 months following the disturbance represent a time period of stochasticity in regard to assemblage structure dynamics, and this was followed by rapid recovery. We term this dynamic the "hangover effect" as it represents the time frame from the cessation of the perturbation to the assemblage's return to predisturbance conditions. The availability and proximity of tributaries and upstream refugia, which were not affected by the disturbance, as well as the rapid recovery of abiotic parameters likely played a substantial role in assemblage recovery. This study not only demonstrates

  15. Black liquor and the hangover effect: fish assemblage recovery dynamics following a pulse disturbance

    PubMed Central

    Piller, Kyle R; Geheber, Aaron D

    2015-01-01

    Anthropogenic perturbations impact aquatic systems causing wide-ranging responses, from assemblage restructuring to assemblage recovery. Previous studies indicate the duration and intensity of disturbances play a role in the dynamics of assemblage recovery. In August 2011, the Pearl River, United States, was subjected to a weak black liquor spill from a paper mill which resulted in substantial loss of fish in a large stretch of the main channel. We quantified resilience and recovery of fish assemblage structure in the impacted area following the event. We compared downstream (impacted) assemblages to upstream (unimpacted) assemblages to determine initial impacts on structure. Additionally, we incorporated historic fish collections (1988–2011) to examine impacts on assemblage structure across broad temporal scales. Based on NMDS, upstream and downstream sites generally showed similar assemblage structure across sample periods with the exception of the 2 months postdischarge, where upstream and downstream sites visually differed. Multivariate analysis of variance (PERMANOVA) indicated significant seasonal variation among samples, but found no significant interaction between impacted and unimpacted assemblages following the discharge event. However, multivariate dispersion (MVDISP) showed greater variance among assemblage structure following the discharge event. These results suggest that 2 months following the disturbance represent a time period of stochasticity in regard to assemblage structure dynamics, and this was followed by rapid recovery. We term this dynamic the “hangover effect” as it represents the time frame from the cessation of the perturbation to the assemblage's return to predisturbance conditions. The availability and proximity of tributaries and upstream refugia, which were not affected by the disturbance, as well as the rapid recovery of abiotic parameters likely played a substantial role in assemblage recovery. This study not only

  16. Extreme cellular adaptations and cell differentiation required by a cyanobacterium for carbonate excavation

    PubMed Central

    Guida, Brandon Scott; Garcia-Pichel, Ferran

    2016-01-01

    Some cyanobacteria, known as euendoliths, excavate and grow into calcium carbonates, with their activity leading to significant marine and terrestrial carbonate erosion and to deleterious effects on coral reef and bivalve ecology. Despite their environmental relevance, the mechanisms by which they can bore have remained elusive and paradoxical, in that, as oxygenic phototrophs, cyanobacteria tend to alkalinize their surroundings, which will encourage carbonate precipitation, not dissolution. Therefore, cyanobacteria must rely on unique adaptations to bore. Studies with the filamentous euendolith, Mastigocoleus testarum, indicated that excavation requires both cellular energy and transcellular calcium transport, mediated by P-type ATPases, but the cellular basis for this phenomenon remains obscure. We present evidence that excavation in M. testarum involves two unique cellular adaptations. Long-range calcium transport is based on active pumping at multiple cells along boring filaments, orchestrated by the preferential localization of calcium ATPases at one cell pole, in a ring pattern, facing the cross-walls, and by repeating this placement and polarity, a pattern that breaks at branching and apical cells. In addition, M. testarum differentiates specialized cells we call calcicytes, that which accumulate calcium at concentrations more than 500-fold those found in other cyanobacteria, concomitantly and drastically lowering photosynthetic pigments and enduring severe cytoplasmatic alkalinization. Calcicytes occur commonly, but not exclusively, in apical parts of the filaments distal to the excavation front. We suggest that calcicytes allow for fast calcium flow at low, nontoxic concentrations through undifferentiated cells by providing buffering storage for excess calcium before final excretion to the outside medium. PMID:27140633

  17. Contributions of In-Situ Stress Transient Redistribution to Blasting Excavation Damage Zone of Deep Tunnels

    NASA Astrophysics Data System (ADS)

    Yan, Peng; Lu, Wen-bo; Chen, Ming; Hu, Ying-guo; Zhou, Chuang-bing; Wu, Xin-xia

    2015-03-01

    With the background of construction of the headrace tunnels with the deepest buried depth in China at present, by means of carefully acoustic velocity detection and analysis of Excavation Damage Zone (EDZ), the contributions to damage zones made by the effect of in situ stress transient redistribution are studied and compared with the extent of damage caused by the explosive load. Also, the numerical simulation was adopted to verify detecting the results. It turned out that the in situ stress transient redistribution during blasting has great influence on the development of EDZ of deep tunnels. The blasting excavation-induced damage zone of deep tunnels can be divided into the inner damage zone and the outer damage zone from the excavation surface into surrounding rocks. Although this damage zone dividing method is similar to the work of Martino and Chandler (2004), the consideration of developing a mechanism of the inner damage zone, especially the contribution of in situ stress transient redistribution, is totally different. The inner damage zone, which accounts for 29-57 % of the total damage zone, is mainly caused by explosive load and in situ stress transient adjustment, while the outer damage zone can be mostly attributed to the static redistribution of in situ stress. Field tests and numerical simulation indicate that the in situ stress transient redistribution effect during blasting contributes about 16-51 % to the inner damage zone in the 2# headrace tunnel of Jinping II Hydropower Station. For general cases, it can be concluded that the in situ stress transient redistribution is one of the main contributors of an excavation damage zone, and damage caused by in situ stress transient redistribution effect may exceed the damage caused by explosion load and become the main inducing factor for damage with the rise of in situ stress levels.

  18. Extreme cellular adaptations and cell differentiation required by a cyanobacterium for carbonate excavation.

    PubMed

    Guida, Brandon Scott; Garcia-Pichel, Ferran

    2016-05-17

    Some cyanobacteria, known as euendoliths, excavate and grow into calcium carbonates, with their activity leading to significant marine and terrestrial carbonate erosion and to deleterious effects on coral reef and bivalve ecology. Despite their environmental relevance, the mechanisms by which they can bore have remained elusive and paradoxical, in that, as oxygenic phototrophs, cyanobacteria tend to alkalinize their surroundings, which will encourage carbonate precipitation, not dissolution. Therefore, cyanobacteria must rely on unique adaptations to bore. Studies with the filamentous euendolith, Mastigocoleus testarum, indicated that excavation requires both cellular energy and transcellular calcium transport, mediated by P-type ATPases, but the cellular basis for this phenomenon remains obscure. We present evidence that excavation in M. testarum involves two unique cellular adaptations. Long-range calcium transport is based on active pumping at multiple cells along boring filaments, orchestrated by the preferential localization of calcium ATPases at one cell pole, in a ring pattern, facing the cross-walls, and by repeating this placement and polarity, a pattern that breaks at branching and apical cells. In addition, M. testarum differentiates specialized cells we call calcicytes, that which accumulate calcium at concentrations more than 500-fold those found in other cyanobacteria, concomitantly and drastically lowering photosynthetic pigments and enduring severe cytoplasmatic alkalinization. Calcicytes occur commonly, but not exclusively, in apical parts of the filaments distal to the excavation front. We suggest that calcicytes allow for fast calcium flow at low, nontoxic concentrations through undifferentiated cells by providing buffering storage for excess calcium before final excretion to the outside medium. PMID:27140633

  19. Fish assemblages of the upper Little Sioux River basin, Iowa, USA: Relationships with stream size and comparison with historical assemblages

    USGS Publications Warehouse

    Palic, D.; Helland, L.; Pedersen, B.R.; Pribil, J.R.; Grajeda, R.M.; Loan-Wilsey, Anna; Pierce, C.L.

    2007-01-01

    We characterized the fish assemblages in second to fifth order streams of the upper Little Sioux River basin in northwest Iowa, USA and compared our results with historical surveys. The fish assemblage consisted of over twenty species, was dominated numerically by creek chub, sand shiner, central stoneroller and other cyprinids, and was dominated in biomass by common carp. Most of the species and the great majority of all individuals present were at least moderately tolerant to environmental degradation, and biotic integrity at most sites was characterized as fair. Biotic integrity declined with increasing stream size, and degraded habitat in larger streams is a possible cause. No significant changes in species richness or the relative distribution of species' tolerance appear to have occurred since the 1930s.

  20. Hydrology and plant survival in excavated depressions near an earthen dam in north-central Texas

    NASA Astrophysics Data System (ADS)

    Williams, Lynde L.; Hudak, Paul F.

    2005-09-01

    This investigation examined plant survival and water sources for small depressions excavated to build an earthen dam and nature trail in north-central Texas, USA. These “inadvertent wetlands” occupy part of an outdoor education facility, overlying alluvial deposits of the Trinity River. A large lake behind the earthen dam strongly influences surface water and groundwater levels in the area. Excavated depressions receive direct precipitation, runoff, and groundwater inputs, losing water by seepage and evapotranspiration. Hydroperiods varied with location and water input: excavations receiving groundwater held water year round; others periodically desiccated. Groundwater-fed depressions had higher salinity; however, the highest average value (1,304 μS/cm) was within the freshwater range. A total of 66 to 75% of emergent and floating wetland species planted in three depressions survived after 2 years. The developing wetlands appear viable under hydrologic conditions typical of the study period. Ultimately, variable hydroperiods among wetlands, and water level fluctuations within individual wetlands, may foster diverse plant-species compositions. Depressed lake levels following long-term drought or increased water demands pose the greatest threat to the developing wetlands.

  1. Three-dimensional laser scanning for geometry documentation and construction management of highway tunnels during excavation.

    PubMed

    Gikas, Vassilis

    2012-01-01

    Driven by progress in sensor technology, computer software and data processing capabilities, terrestrial laser scanning has recently proved a revolutionary technique for high accuracy, 3D mapping and documentation of physical scenarios and man-made structures. Particularly, this is of great importance in the underground space and tunnel construction environment as surveying engineering operations have a great impact on both technical and economic aspects of a project. This paper discusses the use and explores the potential of laser scanning technology to accurately track excavation and construction activities of highway tunnels. It provides a detailed overview of the static laser scanning method, its principles of operation and applications for tunnel construction operations. Also, it discusses the planning, execution, data processing and analysis phases of laser scanning activities, with emphasis given on geo-referencing, mesh model generation and cross-section extraction. Specific case studies are considered based on two construction sites in Greece. Particularly, the potential of the method is examined for checking the tunnel profile, producing volume computations and validating the smoothness/thickness of shotcrete layers at an excavation stage and during the completion of excavation support and primary lining. An additional example of the use of the method in the geometric documentation of the concrete lining formwork is examined and comparisons against dimensional tolerances are examined. Experimental comparisons and analyses of the laser scanning method against conventional surveying techniques are also considered. PMID:23112655

  2. The Effect of Projectile Density and Disruption on the Crater Excavation Flow-Field

    NASA Technical Reports Server (NTRS)

    Anderson, Jennifer L. B.; Schultz, P. H.

    2005-01-01

    The ejection parameters of material excavated by a growing crater directly relate to the subsurface excavation flow-field. The ejection angles and speeds define the end of subsurface material streamlines at the target surface. Differences in the subsurface flow-fields can be inferred by comparing observed ejection parameters of various impacts obtained using three-dimensional particle image velocimetry (3D PIV). The work presented here investigates the observed ejection speeds and angles of material ejected during vertical (90 impact angle) experimental impacts for a range of different projectile types. The subsurface flow-fields produced during vertical impacts are simple when compared with that of oblique impacts, affected primarily by the depth of the energy and momentum deposition of the projectile. This depth is highly controlled by the projectile/target density ratio and the disruption of the projectile (brittle vs. ductile deformation). Previous studies indicated that cratering efficiency and the crater diameter/depth ratio were affected by projectile disruption, velocity, and the projectile/target density ratio. The effect of these projectile properties on the excavation flow-field are examined by comparing different projectile materials.

  3. Multirobot Lunar Excavation and ISRU Using Artificial-Neural-Tissue Controllers

    SciTech Connect

    Thangavelautham, Jekanthan; Smith, Alexander; Abu El Samid, Nader; Ho, Alexander; D'Eleuterio, Gabriele M. T.; Boucher, Dale; Richard, Jim

    2008-01-21

    Automation of site preparation and resource utilization on the Moon with teams of autonomous robots holds considerable promise for establishing a lunar base. Such multirobot autonomous systems would require limited human support infrastructure, complement necessary manned operations and reduce overall mission risk. We present an Artificial Neural Tissue (ANT) architecture as a control system for autonomous multirobot excavation tasks. An ANT approach requires much less human supervision and pre-programmed human expertise than previous techniques. Only a single global fitness function and a set of allowable basis behaviors need be specified. An evolutionary (Darwinian) selection process is used to 'breed' controllers for the task at hand in simulation and the fittest controllers are transferred onto hardware for further validation and testing. ANT facilitates 'machine creativity', with the emergence of novel functionality through a process of self-organized task decomposition of mission goals. ANT based controllers are shown to exhibit self-organization, employ stigmergy (communication mediated through the environment) and make use of templates (unlabeled environmental cues). With lunar in-situ resource utilization (ISRU) efforts in mind, ANT controllers have been tested on a multirobot excavation task in which teams of robots with no explicit supervision can successfully avoid obstacles, interpret excavation blueprints, perform layered digging, avoid burying or trapping other robots and clear/maintain digging routes.

  4. Explosive ordinance disposal technology demonstration using the telerobotic small emplacement excavator

    SciTech Connect

    Burks, B.L.; Killough, S.M.; Thompson, D.H.; Dinkins, M.A.

    1994-06-01

    The small emplacement excavator (SEE) is a ruggedized military vehicle with backhoe and front loader used by the US Army for explosive ordinance disposal (EOD), combat engineer, and general utility excavation activities. In order to evaluate the feasibility of removing personnel from the vehicle during the high risk EOD excavation tasks a development and demonstration project was initiated to evaluate performance capabilities of the SEE under telerobotic control. This feasibility study was performed at the request of the Ordinance Missile and Munitions Center and School (OMMCS) at the Redstone Arsenal to help define requirements for further joint service development activities. Development of a telerobotic SEE (TSEE) was performed by the Oak Ridge National Laboratory (ORNL) in a project funded jointly by the US Army Project Manager for Ammunition Logistics (PM-AMMOLOG) and the Department of Energy (DOE) Office of Technology Development (OTD) Robotics Technology Development Program (RTDP). A technology demonstration of the TSEE was conducted at McKinley Range, Redstone Arsenal, Huntsville, Alabama, on September 13--17, 1993. The primary objective of the demonstration was to evaluate and demonstrate the feasibility of remote EOD. During the demonstration, approximately 40 EOD specialists were instructed on telerobotic operation of the TSEE and then were asked to complete a series of simulated EOD tasks. Upon completion of the tasks, participants completed an evaluation of the system including human factors performance data.

  5. Hollow Cylinder Tests on Boom Clay: Modelling of Strain Localization in the Anisotropic Excavation Damaged Zone

    NASA Astrophysics Data System (ADS)

    François, Bertrand; Labiouse, Vincent; Dizier, Arnaud; Marinelli, Ferdinando; Charlier, Robert; Collin, Frédéric

    2014-01-01

    Boom Clay is extensively studied as a potential candidate to host underground nuclear waste disposal in Belgium. To guarantee the safety of such a disposal, the mechanical behaviour of the clay during gallery excavation must be properly predicted. In that purpose, a hollow cylinder experiment on Boom Clay has been designed to reproduce, in a small-scale test, the Excavation Damaged Zone (EDZ) as experienced during the excavation of a disposal gallery in the underground. In this article, the focus is made on the hydro-mechanical constitutive interpretation of the displacement (experimentally obtained by medium resolution X-ray tomography scanning). The coupled hydro-mechanical response of Boom Clay in this experiment is addressed through finite element computations with a constitutive model including strain hardening/softening, elastic and plastic cross-anisotropy and a regularization method for the modelling of strain localization processes. The obtained results evidence the directional dependency of the mechanical response of the clay. The softening behaviour induces transient strain localization processes, addressed through a hydro-mechanical second grade model. The shape of the obtained damaged zone is clearly affected by the anisotropy of the materials, evidencing an eye-shaped EDZ. The modelling results agree with experiments not only qualitatively (in terms of the shape of the induced damaged zone), but also quantitatively (for the obtained displacement in three particular radial directions).

  6. Three-Dimensional Laser Scanning for Geometry Documentation and Construction Management of Highway Tunnels during Excavation

    PubMed Central

    Gikas, Vassilis

    2012-01-01

    Driven by progress in sensor technology, computer software and data processing capabilities, terrestrial laser scanning has recently proved a revolutionary technique for high accuracy, 3D mapping and documentation of physical scenarios and man-made structures. Particularly, this is of great importance in the underground space and tunnel construction environment as surveying engineering operations have a great impact on both technical and economic aspects of a project. This paper discusses the use and explores the potential of laser scanning technology to accurately track excavation and construction activities of highway tunnels. It provides a detailed overview of the static laser scanning method, its principles of operation and applications for tunnel construction operations. Also, it discusses the planning, execution, data processing and analysis phases of laser scanning activities, with emphasis given on geo-referencing, mesh model generation and cross-section extraction. Specific case studies are considered based on two construction sites in Greece. Particularly, the potential of the method is examined for checking the tunnel profile, producing volume computations and validating the smoothness/thickness of shotcrete layers at an excavation stage and during the completion of excavation support and primary lining. An additional example of the use of the method in the geometric documentation of the concrete lining formwork is examined and comparisons against dimensional tolerances are examined. Experimental comparisons and analyses of the laser scanning method against conventional surveying techniques are also considered. PMID:23112655

  7. Multimodal Imaging Evaluations of Focal Choroidal Excavations in Eyes with Central Serous Chorioretinopathy

    PubMed Central

    Chen, Zhi-Qing; Wang, Wei

    2016-01-01

    Purpose. To investigate the prevalence and characteristics of focal choroidal excavation (FCE) concurrent with central serous chorioretinopathy (CSC) using multimodal imaging. Methods. This was a retrospective single-institution study. Clinical features and multimodal imaging findings were analyzed in eyes with CSC and FCEs, using imaging methods including optical coherence tomography (OCT), OCT angiography (OCTA), fluorescein angiography (FA), indocyanine green angiography (ICGA), fundus autofluorescence (FAF), and multispectral imaging. Results. Seventeen patients (4.8%) with 21 FCEs (19 eyes) were found among 351 consecutive Chinese patients with CSC. Chronic CSC represented 47.1% of those cases. Window defects in 12 lesions identified through FA and hypoautofluorescence in 13 lesions identified through FAF revealed retinal pigment epithelial attenuation. Choroidal hemodynamic disturbances characterized by localized filling defects at the excavation and circumferential hyperperfusion were validated by both ICGA and OCTA, which were similar to the angiographic features of normal chronic CSC. The hyperreflective tissue beneath FCE, observed on B-scan OCT, presented as intensive choroidal flow signals on OCTA. Conclusions. FCE is not uncommon in patients with CSC. Multimodal imaging suggested that the aberrant choroidal circulation might be a contribution factor for leakage from the dysfunctional retinal pigment epithelium at the area of excavation. PMID:27437148

  8. A Completely 3D Model for the Simulation of Mechanized Tunnel Excavation

    NASA Astrophysics Data System (ADS)

    Zhao, Kai; Janutolo, Michele; Barla, Giovanni

    2012-07-01

    For long deep tunnels as currently under construction through the Alps, mechanized excavation using tunnel boring machines (TBMs) contributes significantly to savings in construction time and costs. Questions are, however, posed due to the severe ground conditions which are in cases anticipated or encountered along the main tunnel alignment. A major geological hazard is the squeezing of weak rocks, but also brittle failure can represent a significant problem. For the design of mechanized tunnelling in such conditions, the complex interaction between the rock mass, the tunnel machine, its system components, and the tunnel support need to be analysed in detail and this can be carried out by three-dimensional (3D) models including all these components. However, the state-of-the-art shows that very few fully 3D models for mechanical deep tunnel excavation in rock have been developed so far. A completely three-dimensional simulator of mechanised tunnel excavation is presented in this paper. The TBM of reference is a technologically advanced double shield TBM designed to cope with both conditions. Design analyses with reference to spalling hazard along the Brenner and squeezing along the Lyon-Turin Base Tunnel are discussed.

  9. Reliable Support Design for Excavations in Brittle Rock Using a Global Response Surface Method

    NASA Astrophysics Data System (ADS)

    Langford, J. Connor; Diederichs, Mark S.

    2015-03-01

    Spalling damage can pose significant risks during the construction of underground excavations in brittle rock. While deterministic analyses have traditionally been used in the design of these structures, reliability-based design (RBD) methods provide a more rational approach to quantify spalling risk by directly incorporating input uncertainty into the design process and quantifying variable ground response. This paper presents a new RBD approach to evaluate the excavation response and support performance for a tunnel in brittle ground. Guidance for the selection of appropriate parameters for variable brittle materials is provided using a combination of the damage initiation and spalling limit method and theories of microcrack initiation. System performance is then evaluated using a proposed global response surface method (GRSM) coupled with the first-order reliability method, random sampling and finite element analysis. The proposed GRSM provides a computationally efficient way to evaluate the probability of failure for various limit states, allowing for the selection of appropriate design parameters such as minimum bolt length and required bolt capacity during early stages of design. To demonstrate the usefulness of this approach, a preliminary design option for a proposed deep geologic repository located in Canada was assessed. Numerical analyses were completed using finite element modeling to determine the depth of spalling around the excavation and support loads over the range of possible rock mass and in situ stress conditions. The results of these analyses were then used to assess support performance and make support recommendations.

  10. Multirobot Lunar Excavation and ISRU Using Artificial-Neural-Tissue Controllers

    NASA Astrophysics Data System (ADS)

    Thangavelautham, Jekanthan; Smith, Alexander; Abu El Samid, Nader; Ho, Alexander; Boucher, Dale; Richard, Jim; D'Eleuterio, Gabriele M. T.

    2008-01-01

    Automation of site preparation and resource utilization on the Moon with teams of autonomous robots holds considerable promise for establishing a lunar base. Such multirobot autonomous systems would require limited human support infrastructure, complement necessary manned operations and reduce overall mission risk. We present an Artificial Neural Tissue (ANT) architecture as a control system for autonomous multirobot excavation tasks. An ANT approach requires much less human supervision and pre-programmed human expertise than previous techniques. Only a single global fitness function and a set of allowable basis behaviors need be specified. An evolutionary (Darwinian) selection process is used to `breed' controllers for the task at hand in simulation and the fittest controllers are transferred onto hardware for further validation and testing. ANT facilitates `machine creativity', with the emergence of novel functionality through a process of self-organized task decomposition of mission goals. ANT based controllers are shown to exhibit self-organization, employ stigmergy (communication mediated through the environment) and make use of templates (unlabeled environmental cues). With lunar in-situ resource utilization (ISRU) efforts in mind, ANT controllers have been tested on a multirobot excavation task in which teams of robots with no explicit supervision can successfully avoid obstacles, interpret excavation blueprints, perform layered digging, avoid burying or trapping other robots and clear/maintain digging routes.

  11. Archaeological Geophysics, Excavation, and Ethnographic Approaches Toward a Deeper Understanding of an Eighteenth Century Wichita Site

    NASA Astrophysics Data System (ADS)

    Carlock, Michael Don

    This research exemplifies a multidirectional approach to an archaeological interpretation of an eighteenth century Wichita village and fortification located on the Red River bordering Oklahoma and Texas. A battle that is believed to have occurred at the Longest site (34JF1) in 1759 between Spanish colonials and a confederation of Native Americans led to several Spanish primary documents describing the people that lived there, the fortification and surrounding village, and of course the battle itself. Investigation of the Longest site (34JF1) in Oklahoma presents a remarkable opportunity to combine extensive historical research, archaeological prospecting using geophysics, and traditional excavation techniques in order to gain a more complete understanding of this important archaeological site. The fortification at the Longest site, as well as possible associated structures and cultural features, were relocated using magnetometry, ground-penetrating radar, and electrical resistivity methods. Then, previously translated historical documents provided valuable insights in the interpretation of the geophysical data. Finally, archaeological excavation permitted validation of the interpretations and identification of features described in the historical accounts. As interpreted in the geophysical data and excavations, the construction of the fortification and associated interior subterranean rooms suggests that it is indeed the fortification involved in the altercation between the Taovayas and the Spanish in 1759.

  12. Excavation and melting of the Hadean continental crust by Late Heavy Bombardment

    NASA Astrophysics Data System (ADS)

    Shibaike, Yuhito; Sasaki, Takanori; Ida, Shigeru

    2016-03-01

    No Hadean rocks have ever been found on Earth's surface except for zircons-evidence of continental crust, suggesting that Hadean continental crust existed but later disappeared. One hypothesis for the disappearance of the continental crust is excavation/melting by the Late Heavy Bombardment (LHB), a concentration of impacts in the last phase of the Hadean eon. In this paper, we calculate the effects of LHB on Hadean continental crust in order to investigate this hypothesis. Approximating the size-frequency distribution of the impacts by a power-law scaling with an exponent α as a parameter, we have derived semi-analytical expressions for the effects of LHB impacts. We calculated the total excavation/melting volume and area affected by the LHB from two constraints of LHB on the Moon, the size of the largest basin during LHB, and the density of craters larger than 20 km. We also investigated the effects of the value of α. Our results show that LHB does not excavate/melt all of Hadean continental crust directly, but over 70% of the Earth's surface area can be covered by subsequent melts in a broad range of α. If there have been no overturns of the continental crust until today, LHB could be responsible for the absence of Hadean rocks because most of Hadean continental crust is not be exposed on the Earth's surface in this case.

  13. The adoption of mechanized excavation techniques for the Superconducting Super Collider

    SciTech Connect

    Laughton, C.; Nelson, P.; Lundin, T.

    1991-01-01

    The Superconducting Super Collider (SSC) is the latest and largest in a line of high-energy physics accelerator projects. The five increasingly energetic accelerators which make up the physics laboratory complex are to be housed almost entirely in subsurface structures, which will include over 100 km of small-diameter tunnel. Among other reasons, the Texas SSC site was chosen from a set of state proposals because of the suitability of the host rock materials for the performance of rapid and efficient excavation work. This site bedrock units are relatively soft and homogeneous and should allow for a maximum use of mechanical excavation plant for the various underground openings. This paper will review the site conditions and describe the developed understanding of geologic material behavior. With completion of planned large-scale in-situ studies of the ground behavior to provide acquisition of early site-specific excavation data, final design and construction detail of critical structures can be undertaken with the necessary degree of confidence to satisfy the stringent performance requirements. 5 refs., 4 figs., 6 tabs.

  14. Endoscopic en bloc resection of an exophytic gastrointestinal stromal tumor with suction excavation technique.

    PubMed

    Choi, Hyuk Soon; Chun, Hoon Jai; Kim, Kyoung-Oh; Kim, Eun Sun; Keum, Bora; Jeen, Yoon-Tae; Lee, Hong Sik; Kim, Chang Duck

    2016-06-21

    Here, we report the first successful endoscopic resection of an exophytic gastrointestinal stromal tumor (GIST) using a novel perforation-free suction excavation technique. A 49-year-old woman presented for further management of a gastric subepithelial tumor on the lesser curvature of the lower body, originally detected via routine upper gastrointestinal endoscopy. Abdominal computed tomography and endoscopic ultrasound showed a 4-cm extraluminally protruding mass originating from the muscularis propria layer. The patient firmly refused surgical resection owing to potential cardiac problems, and informed consent was obtained for endoscopic removal. Careful dissection and suction of the tumor was repeated until successful extraction was achieved without serosal injury. We named this procedure the suction excavation technique. The tumor's dimensions were 3.5 cm × 2.8 cm × 2.5 cm. The tumor was positive for C-KIT and CD34 by immunohistochemical staining. The mitotic count was 6/50 high-power fields. The patient was followed for 5 years without tumor recurrence. This case demonstrated the use of endoscopic resection of an exophytic GIST using the suction excavation technique as a potential therapy without surgical resection. PMID:27340363

  15. Endoscopic en bloc resection of an exophytic gastrointestinal stromal tumor with suction excavation technique

    PubMed Central

    Choi, Hyuk Soon; Chun, Hoon Jai; Kim, Kyoung-Oh; Kim, Eun Sun; Keum, Bora; Jeen, Yoon-Tae; Lee, Hong Sik; Kim, Chang Duck

    2016-01-01

    Here, we report the first successful endoscopic resection of an exophytic gastrointestinal stromal tumor (GIST) using a novel perforation-free suction excavation technique. A 49-year-old woman presented for further management of a gastric subepithelial tumor on the lesser curvature of the lower body, originally detected via routine upper gastrointestinal endoscopy. Abdominal computed tomography and endoscopic ultrasound showed a 4-cm extraluminally protruding mass originating from the muscularis propria layer. The patient firmly refused surgical resection owing to potential cardiac problems, and informed consent was obtained for endoscopic removal. Careful dissection and suction of the tumor was repeated until successful extraction was achieved without serosal injury. We named this procedure the suction excavation technique. The tumor’s dimensions were 3.5 cm × 2.8 cm × 2.5 cm. The tumor was positive for C-KIT and CD34 by immunohistochemical staining. The mitotic count was 6/50 high-power fields. The patient was followed for 5 years without tumor recurrence. This case demonstrated the use of endoscopic resection of an exophytic GIST using the suction excavation technique as a potential therapy without surgical resection. PMID:27340363

  16. An investigation on possible stability problems of rock masses during Elmadag tunnel excavation, Turkey

    NASA Astrophysics Data System (ADS)

    Özge Dinç, Şaziye; Tunusluoǧlu, Celal

    2014-05-01

    Our research project presents possible stability problems of rock masses of Elmadag- Ankara tunnel as one of the sections along the high speed railway system between Ankara and Sivas. The length and diameter of the tunnel will be 2975 m and 12.5 m, respectively. The studies of the tunnel excavation area at predesign stage were carried out both in the field and laboratory. The results of engineering mapping, core drilling and mineralogical-petrographic analysis indicated two rock formations, called Elmadag (metasiltstones, Triassic age) and Artova (serpantinites, Cretaceous age). Data from laboratory tests (permability, point load strength index, unit weight, uniaxial compressive strength tests, elasticity modules) and boring logs (TCR, RQD, weathering degree, fracture frequency, ground water depth) were used to identify rock mass quaility in excavation area. These data are combined to calculate the strengths of rock masses by empirical approaches in literature. However, the strength values were predicted less than 0.1 MPa that needs more investigations to determine excavation material as highly jointed rock or soil. Additionaly, preliminary results of numerical anaysis showed that the radius of plastic zone (approximately 26.11 m- 27.01 m ) is more than allowed value (rplastik≤ 2r) that causes inevitable stability problems needed to estimate before tunnel construction.

  17. Foraminiferal, lithic, and isotopic changes across four major unconformities at Deep Sea Drilling Project Site 548, Goban Spur: Chapter 14 in Initial reports of the Deep Sea Drilling Project

    USGS Publications Warehouse

    Poag, C. Wylie; Reynolds, Leslie A.; Mazzullo, James M.; Keigwin, Loyd D.

    1985-01-01

    Sediment samples taken at close intervals across four major unconformities (middle Miocene/upper Miocene, lower Oligocene/upper Oligocene, lower Eocene/upper Eocene, lower Paleocene/upper Paleocene) at DSDP-IPOD Site 548, Goban Spur, reveal that coeval biostratigraphic gaps, sediment discontinuities, and seismic unconformities coincide with postulated low stands of sea level. Foraminiferal, lithic, and isotopic analyses demonstrate that environments began to shift prior to periods of marine erosion, and that sedimentation resumed in the form of turbidites derived from nearby upper-slope sources. The unconformities appear to have developed where a water-mass boundary intersected the continental slope, rhythmically crossing the drill site in concert with sea-level rise and fall.

  18. Composition of the Primary Crust of Mars: Observations of Deeply Excavated Crater Central Peaks

    NASA Astrophysics Data System (ADS)

    Skok, J. R.; Mustard, J. F.; Tornabene, L. L.; Murchie, S. L.

    2011-12-01

    It is predicted that the primary crust of Mars crystallized from a magma ocean and would be well preserved at depth on a single plate planet but poorly exposed as impacts, volcanism and alteration has reworked the upper crust. In a few select locations, extensive excavation by impact or erosion has exposed unaltered mafic minerals of the Martian crust. The majority of these exposures occur within the uplifted central peaks and peak rings of Southern Highland craters. We examine the mafic compositions of these deeply excavated crustal rocks in an attempt to constrain the composition of the Martian crust and test models of planetary formation. The search for deeply excavated bedrock from HiRISE images is ongoing and has so far resulted in nearly 200 potential locations. Over half of these currently have CRISM spectroscopic observations with ~50 locations having good exposures of crustal rocks showing little to no alteration. It is this combination of deeply excavated minerals that has potential to tap the preserved primary crust of Mars. We focus our analysis on olivine and pyroxene as crustal formation models predict that these two minerals would dominate the modal mineralogy of the crystallizing crust with a garnet layer potentially stable at depth. The high-resolution visible and near-infrared spectroscopic data provided by the CRISM instrument is ideally suited for examining these compositional characteristics. Initial in-depth analysis of the central peak of Alga Crater shows excellent exposures of lithologies characterized by both olivine and pyroxene. The olivine-bearing unit here has a fayalitic composition and a dunite lithology. This ancient Fe-rich olivine is in stark contrast to the Mg-enriched olivine of the primitive mantle of Earth. The primary pyroxene-bearing unit was determined to be a low-calcium, high-Fe enstatite orthopyroxenite, consistent with the mineralogy of the ancient Mars meteorite ALH84001. These observations suggest that the crust

  19. Ichthyoplankton assemblage structure of springs in the Yangtze Estuary revealed by biological and environmental visions

    PubMed Central

    Zhang, Hui; Liu, Shude

    2015-01-01

    The ichthyoplankton assemblage structure in the Yangtze Estuary was analyzed based on four springs in 1999, 2001, 2004 and 2007 in order to provide detailed characterizations of the ichthyoplankton assemblage in springs, examine the long-term dynamics of spring ichthyoplankton assemblages, and evaluate the influence of environmental factors on the spatial distribution and inter-annual variations of ichthyoplankton assemblages associated with the Yangtze Estuary. Forty-two ichthyoplankton species belonging to 23 families were collected. Engraulidae was the most abundant family, including six species and comprising 67.91% of the total catch. Only four species (Coilia mystus, Engraulis japonicus, Trachidermis fasciatus and Allanetta bleekeri) could be considered dominant, accounting for 88.70% of total abundance. The structure of the ichthyoplankton spring assemblage persisted on an annual basis, with the dominant species reappearing consistently even though their abundance fluctuated from year to year. This inter-annual variation probably reflects variable environmental conditions influenced by jellyfish blooms, declining river flow, and overfishing. Canonical correspondence analysis indicated aspatial structure of the ichthyoplankton assemblage in three areas: (1) an inner assemblage dominated by C. mystus; (2) a central assemblage dominated by A. bleekeri and T. fasciatus; and (3) a shelf assemblage featuring E. japonicus. The observed ichthyoplankton assemblage structure appears to be strongly influenced by depth, salinity and suspended particulate matter gradients. PMID:26312180

  20. Ichthyoplankton assemblage structure of springs in the Yangtze Estuary revealed by biological and environmental visions.

    PubMed

    Zhang, Hui; Xian, Weiwei; Liu, Shude

    2015-01-01

    The ichthyoplankton assemblage structure in the Yangtze Estuary was analyzed based on four springs in 1999, 2001, 2004 and 2007 in order to provide detailed characterizations of the ichthyoplankton assemblage in springs, examine the long-term dynamics of spring ichthyoplankton assemblages, and evaluate the influence of environmental factors on the spatial distribution and inter-annual variations of ichthyoplankton assemblages associated with the Yangtze Estuary. Forty-two ichthyoplankton species belonging to 23 families were collected. Engraulidae was the most abundant family, including six species and comprising 67.91% of the total catch. Only four species (Coilia mystus, Engraulis japonicus, Trachidermis fasciatus and Allanetta bleekeri) could be considered dominant, accounting for 88.70% of total abundance. The structure of the ichthyoplankton spring assemblage persisted on an annual basis, with the dominant species reappearing consistently even though their abundance fluctuated from year to year. This inter-annual variation probably reflects variable environmental conditions influenced by jellyfish blooms, declining river flow, and overfishing. Canonical correspondence analysis indicated aspatial structure of the ichthyoplankton assemblage in three areas: (1) an inner assemblage dominated by C. mystus; (2) a central assemblage dominated by A. bleekeri and T. fasciatus; and (3) a shelf assemblage featuring E. japonicus. The observed ichthyoplankton assemblage structure appears to be strongly influenced by depth, salinity and suspended particulate matter gradients. PMID:26312180

  1. Use of chemical explosives for emergency solar flare shelter construction and other excavations on the Martian surface

    SciTech Connect

    Dick, R.D.; Blacic, J.D.; Pettitt, D.R.

    1985-01-01

    The necessity to shelter people on the Martian surface from solar flare particles at short notice and the need for long-term habitats with thick cosmic ray shielding suggests that explosives could be used effectively for excavation of such structures. Modern insensitive high explosives are safe, efficient, and reliable for rock breakage and excavation. Extensive Earth-bound experience leads us to propose several strategies for explosively-constructed shelters based on tunneling, cratering, and rock casting techniques.

  2. Applying the seismic interferometry method to vertical seismic profile data using tunnel excavation noise as source

    NASA Astrophysics Data System (ADS)

    Jurado, Maria Jose; Teixido, Teresa; Martin, Elena; Segarra, Miguel; Segura, Carlos

    2013-04-01

    In the frame of the research conducted to develop efficient strategies for investigation of rock properties and fluids ahead of tunnel excavations the seismic interferometry method was applied to analyze the data acquired in boreholes instrumented with geophone strings. The results obtained confirmed that seismic interferometry provided an improved resolution of petrophysical properties to identify heterogeneities and geological structures ahead of the excavation. These features are beyond the resolution of other conventional geophysical methods but can be the cause severe problems in the excavation of tunnels. Geophone strings were used to record different types of seismic noise generated at the tunnel head during excavation with a tunnelling machine and also during the placement of the rings covering the tunnel excavation. In this study we show how tunnel construction activities have been characterized as source of seismic signal and used in our research as the seismic source signal for generating a 3D reflection seismic survey. The data was recorded in vertical water filled borehole with a borehole seismic string at a distance of 60 m from the tunnel trace. A reference pilot signal was obtained from seismograms acquired close the tunnel face excavation in order to obtain best signal-to-noise ratio to be used in the interferometry processing (Poletto et al., 2010). The seismic interferometry method (Claerbout 1968) was successfully applied to image the subsurface geological structure using the seismic wave field generated by tunneling (tunnelling machine and construction activities) recorded with geophone strings. This technique was applied simulating virtual shot records related to the number of receivers in the borehole with the seismic transmitted events, and processing the data as a reflection seismic survey. The pseudo reflective wave field was obtained by cross-correlation of the transmitted wave data. We applied the relationship between the transmission

  3. The Excavation and Remediation of the Sandia National Laboratories Chemical Waste Landfill

    SciTech Connect

    KWIECINSKI,DANIEL ALBERT; METHVIN,RHONDA KAY; SCHOFIELD,DONALD P.; YOUNG,SHARISSA G.

    1999-11-23

    The Chemical Waste Landfill (CWL) at Sandia National Laboratories/New Mexico (SNL/NM) is a 1.9-acre disposal site that was used for the disposal of chemical wastes generated by many of SNL/NM research laboratories from 1962 until 1985. These laboratories were primarily involved in the design, research and development of non-nuclear components of nuclear weapons and the waste generated by these labs included small quantities of a wide assortment of chemical products. A Resource Conservation and Recovery Act (RCRA) Closure Plan for the Chemical Waste Landfill was approved by the New Mexico Environment Department (NMED) in 1992. Subsequent site characterization activities identified the presence of significant amounts of chromium in the soil as far as 80 feet below ground surface (fbgs) and the delineation of a solvent plume in the vadose zone that extends to groundwater approximately 500 fbgs. Trichloroethylene (TCE) was detected in some groundwater samples at concentrations slightly above the drinking water limit of 5 parts per billion. In 1997 an active vapor extraction system reduced the size of the TCE vapor plume and for the last six quarterly sampling events groundwater samples have not detected TCE above the drinking water standard. A source term removal, being conducted as a Voluntary Corrective Measure (VCM), began in September 1998 and is expected to take up to two years. Four distinct disposal areas were identified from historical data and the contents of disposal pits and trenches in these areas, in addition to much of the highly contaminated soil surrounding the disposal cells, are currently being excavated. Buried waste and debris are expected to extend to a depth of 12 to 15 fbgs. Excavation will focus on the removal of buried debris and contaminated soil in a sequential, area by area manner and will proceed to whatever depth is required in order to remove all pit contents. Up to 50,000 cubic yards of soil and debris will be removed and managed during

  4. Performance prediction of mechanical excavators from linear cutter tests on Yucca Mountain welded tuffs; Yucca Mountain Site Characterization Project

    SciTech Connect

    Gertsch, R.; Ozdemir, L.

    1992-09-01

    The performances of mechanical excavators are predicted for excavations in welded tuff. Emphasis is given to tunnel boring machine evaluations based on linear cutting machine test data obtained on samples of Topopah Spring welded tuff. The tests involve measurement of forces as cutters are applied to the rock surface at certain spacing and penetrations. Two disc and two point-attack cutters representing currently available technology are thus evaluated. The performance predictions based on these direct experimental measurements are believed to be more accurate than any previous values for mechanical excavation of welded tuff. The calculations of performance are predicated on minimizing the amount of energy required to excavate the welded tuff. Specific energy decreases with increasing spacing and penetration, and reaches its lowest at the widest spacing and deepest penetration used in this test program. Using the force, spacing, and penetration data from this experimental program, the thrust, torque, power, and rate of penetration are calculated for several types of mechanical excavators. The results of this study show that the candidate excavators will require higher torque and power than heretofore estimated.

  5. Temporal Assemblage Turnovers of Foraminiferal Communities from the Caribbean, United Kingdom and Mediterranean regions

    NASA Astrophysics Data System (ADS)

    Costelloe, Ashleigh; Wilson, Brent

    2016-04-01

    Temporal assemblage turnovers of intertidal foraminiferal communities were quantitatively determined using the assemblage turnover index (ATI), and contributing species were identified using the conditioned on-boundary index (CoBI). The live foraminiferal communities were examined as metacommunities (all stations) and assemblages (groups of stations defined by cluster analysis) over one and two year periods at Caroni Swamp, Claxton Bay (E Trinidad), Cowpen Marsh (NE England) and Bay of Cádiz (SW Spain). Major assemblage turnovers (when ATI > x + σ) of the Caroni Swamp metacommunity and assemblages coincided with seasonal changes from dry to wet conditions in 2011 and 2012. The abundant species (Ammonia tepida, Ammotium salsum, Arenoparella mexicana, Trochammina advena, Trochammina laevigata and Trochammina inflata) contributed the most to assemblage turnovers but showed no preference to either dry or wet conditions. At Claxton Bay major assemblage turnovers of the metacommunity and mid assemblage coincided with seasonal change and calcareous species (A. tepida and Triloculina oblonga) increased during wet conditions and decreased during dry conditions, while agglutinated species (T. advena and A. salsum) fluctuated oppositely. At Cowpen Marsh major assemblage turnovers of the metacommunity coincided with the start of summer and winter. Assemblages at higher elevations (mainly Jadammina macrescens and Haplophragmoides spp.) were responsible for the summer turnover, while the winter turnover was led by the assemblage at lower elevations (mainly Haynesina germanica, Elphidium earlandi, Elphidium williamsoni, Elphidium excavatum and Quinqueloculina spp.). At Bay of Cádiz, the foraminiferal assemblage at a tidal height of 1.5 to 1.7 m above the hydrographic zero was examined within three separate plots, and the seasonal occurrence of assemblage turnovers differed between plots. Thus, replicate samples and multiple plots may be necessary to overcome spatial

  6. Variation in Symbiodinium ITS2 sequence assemblages among coral colonies.

    PubMed

    Stat, Michael; Bird, Christopher E; Pochon, Xavier; Chasqui, Luis; Chauka, Leonard J; Concepcion, Gregory T; Logan, Dan; Takabayashi, Misaki; Toonen, Robert J; Gates, Ruth D

    2011-01-01

    Endosymbiotic dinoflagellates in the genus Symbiodinium are fundamentally important to the biology of scleractinian corals, as well as to a variety of other marine organisms. The genus Symbiodinium is genetically and functionally diverse and the taxonomic nature of the union between Symbiodinium and corals is implicated as a key trait determining the environmental tolerance of the symbiosis. Surprisingly, the question of how Symbiodinium diversity partitions within a species across spatial scales of meters to kilometers has received little attention, but is important to understanding the intrinsic biological scope of a given coral population and adaptations to the local environment. Here we address this gap by describing the Symbiodinium ITS2 sequence assemblages recovered from colonies of the reef building coral Montipora capitata sampled across Kāne'ohe Bay, Hawai'i. A total of 52 corals were sampled in a nested design of Coral Colony(Site(Region)) reflecting spatial scales of meters to kilometers. A diversity of Symbiodinium ITS2 sequences was recovered with the majority of variance partitioning at the level of the Coral Colony. To confirm this result, the Symbiodinium ITS2 sequence diversity in six M. capitata colonies were analyzed in much greater depth with 35 to 55 clones per colony. The ITS2 sequences and quantitative composition recovered from these colonies varied significantly, indicating that each coral hosted a different assemblage of Symbiodinium. The diversity of Symbiodinium ITS2 sequence assemblages retrieved from individual colonies of M. capitata here highlights the problems inherent in interpreting multi-copy and intra-genomically variable molecular markers, and serves as a context for discussing the utility and biological relevance of assigning species names based on Symbiodinium ITS2 genotyping. PMID:21246044

  7. Quantity and quality components of effectiveness in insular pollinator assemblages.

    PubMed

    Rodríguez-Rodríguez, María C; Jordano, Pedro; Valido, Alfredo

    2013-09-01

    Ecologically isolated habitats (e.g., oceanic islands) favor the appearance of small assemblages of pollinators, generally characterized by highly contrasted life modes (e.g., birds, lizards), and opportunistic nectar-feeding behavior. Different life modes should promote a low functional equivalence among pollinators, while opportunistic nectar feeding would lead to reduced and unpredictable pollination effectiveness (PE) compared to more specialized nectarivores. Dissecting the quantity (QNC) and quality (QLC) components of PE, we studied the opportunistic bird-lizard pollinator assemblage of Isoplexis canariensis from the Canary Islands to experimentally evaluate these potential characteristics. Birds and lizards showed different positions in the PE landscape, highlighting their low functional equivalence. Birds were more efficient than lizards due to higher visitation frequency (QNC). Adult lizards differed from juveniles in effecting a higher production of viable seeds (QLC). The disparate life modes of birds and lizards resulted in ample intra- and inter-specific PE variance. The main sources of PE variance were visitation frequency (both lizards and birds), number of flowers probed (lizards) and proportion of viable seeds resulting from a single visit (birds). The non-coincident locations of birds and lizards on the PE landscape indicate potential constraints for effectiveness. Variations in pollinator abundance can result in major effectiveness shifts only if QLC is relatively high, while changes in QLC would increase PE substantially only at high QNC. The low functional equivalence of impoverished, highly contrasted pollinator assemblages may be an early diagnostic signal for pollinator extinction potentially driving the collapse of mutualistic services. PMID:23404070

  8. Variation in Symbiodinium ITS2 Sequence Assemblages among Coral Colonies

    PubMed Central

    Stat, Michael; Bird, Christopher E.; Pochon, Xavier; Chasqui, Luis; Chauka, Leonard J.; Concepcion, Gregory T.; Logan, Dan; Takabayashi, Misaki; Toonen, Robert J.; Gates, Ruth D.

    2011-01-01

    Endosymbiotic dinoflagellates in the genus Symbiodinium are fundamentally important to the biology of scleractinian corals, as well as to a variety of other marine organisms. The genus Symbiodinium is genetically and functionally diverse and the taxonomic nature of the union between Symbiodinium and corals is implicated as a key trait determining the environmental tolerance of the symbiosis. Surprisingly, the question of how Symbiodinium diversity partitions within a species across spatial scales of meters to kilometers has received little attention, but is important to understanding the intrinsic biological scope of a given coral population and adaptations to the local environment. Here we address this gap by describing the Symbiodinium ITS2 sequence assemblages recovered from colonies of the reef building coral Montipora capitata sampled across Kāne'ohe Bay, Hawai'i. A total of 52 corals were sampled in a nested design of Coral Colony(Site(Region)) reflecting spatial scales of meters to kilometers. A diversity of Symbiodinium ITS2 sequences was recovered with the majority of variance partitioning at the level of the Coral Colony. To confirm this result, the Symbiodinium ITS2 sequence diversity in six M. capitata colonies were analyzed in much greater depth with 35 to 55 clones per colony. The ITS2 sequences and quantitative composition recovered from these colonies varied significantly, indicating that each coral hosted a different assemblage of Symbiodinium. The diversity of Symbiodinium ITS2 sequence assemblages retrieved from individual colonies of M. capitata here highlights the problems inherent in interpreting multi-copy and intra-genomically variable molecular markers, and serves as a context for discussing the utility and biological relevance of assigning species names based on Symbiodinium ITS2 genotyping. PMID:21246044

  9. Clearcut stand size and scrub-successional bird assemblages

    USGS Publications Warehouse

    Krementz, D.G.; Christie, J.S.

    2000-01-01

    We investigated the effects of clearcut stand size on species richness, reproductive effort, and relative abundance of scrub-successional birds and the entire bird assemblage at the Savannah River Site in South Carolina. We used standardized mist-net grids to mark and recapture birds in clearcuts replanted with longleaf pine (Pinus palustris) in stands of 2 to 57 ha that were two to six years old. Species richness for the entire bird assemblage was not explained by stand size (P = 0.67), stand age (P = 0.95), or the interaction of these two variables (P = 0.90). Similarly, species richness of scrub-successional birds was not explained by stand size (P = 0.63), stand age (P = 0.55), or the interaction of stand size and stand age (P = 0.35). Regressing species richness on clearcut stand size, we found a significant negative relationship between these variables for the entire bird assemblage (P = 0.01) and for scrub-successional birds (P = 0.02). The ratio of juveniles to adults in mist-net samples varied by year (P = 0.04), but neither clearcut size (P = 0.23) nor the interaction of clearcut size and year (P = 0.25) was related to the ratio of juveniles to adults in the sample. We found no relationship between the frequency of capture of any category of birds and stand size (scrub-successional, P = 0.52; woodland, P = 0.77; combined sample, P = 0.55). Neither bird-species richness, reproductive effort, nor relative abundance differed across clearcut stand sizes. Clearcut stand size does not appear to be an important management variable if variation in species richness, reproductive effort, or relative abundance are objectives. We suggest that even-aged forestry is a useful tool for managing birds in the southeastern United States.

  10. Distinguishing primary and secondary inclusion assemblages in Jack Hills zircons

    NASA Astrophysics Data System (ADS)

    Bell, Elizabeth A.; Boehnke, Patrick; Hopkins-Wielicki, Michelle D.; Harrison, T. Mark

    2015-10-01

    Detrital igneous zircons from Jack Hills, Western Australia, range in age from ~ 3.0 to nearly 4.4 Ga and contain an inclusion assemblage dominated by quartz and muscovite, cited as evidence of their derivation from peraluminous granitoids. However, some phosphate inclusions in these zircons are known to be secondary from their post-depositional U-Pb ages and manifest mineralization along cracks. We undertook a survey of mineral inclusions in 4.3-3.0 Ga Jack Hills zircons with particular emphasis on their relationship to possible alteration features (e.g., cracks, disturbed internal zonation, and visual turbidity). Mineral inclusions revealed at polished surfaces show variations in modal mineralogy, mostly corresponding to their relationship with cracks. Muscovite is common both on and away from cracks, although the chemistry of muscovite inclusions shows little relationship with other potential alteration features. Inclusions filling cracks (secondary) and inclusions isolated from cracks differ in their modal mineralogy, although both suites are rich in muscovite and quartz. The higher incidence of crack-intersecting inclusions among younger zircons may reflect effects of the (generally larger) inclusion size among younger zircons. Mismatches between the isolated and crack-intersecting populations indicate selective loss of certain phases (e.g., feldspar, apatite) and over-representation of quartz and muscovite along cracks likely due to the effects of larger inclusion size and varying degrees of overpressure following zircon cooling and decompression. Inclusions not associated with cracks in magmatically zoned versus regions with disturbed zoning have similar phase proportions. This indicates only minor inclusion replacement away from cracks (i.e., the isolated assemblage is likely primary). This holds true also for inclusions within visually turbid versus clear volumes of zircon. Phase proportions within the inclusion assemblages differ with age indicating a

  11. Post-defaunation recovery of fish assemblages in southeastern blackwater streams

    SciTech Connect

    Meffe, G.K. ); Sheldon, A.L. )

    1990-04-01

    The authors analyzed fish assemblage structure at 37 sites in South Carolina streams before and nearly one year after experimental defaunation to test assemblage resiliency. Decreases in stream depth and width in the second year reflected an intervening drought, but habitat structure remained highly correlated between years. Fish assemblages recovered well over four scales of analysis. Total fishes sampled, collective assemblage properties (species richness, density, biomass, and mean mass of fish), local assemblage structure, and single-species attributes generally did not significantly differ after defaunation, as determined by species- and individual-abundance correlations, detrended correspondence analysis, and a proportional similarity index. These assemblages were not randomly structured units, but were largely deterministic systems highly predictable from local habitat structure.

  12. Habitat relationships with fish assemblages in minimally disturbed Great Plains regions

    USGS Publications Warehouse

    Fischer, John R.; Paukert, C.P.

    2008-01-01

    Effects of local environmental influences on the structure of fish assemblages were evaluated from 159 sites in two regions of the Great Plains with limited anthropogenic disturbance. These regions offered an opportunity to evaluate the structure and variation of streams and fish assemblages within the Great Plains. We used canonical correspondence analyses to determine the influence of environmental conditions on species abundances, species occurrences and assemblage characteristics. Analysis of regions separately indicated that similar environmental factors structured streams and fish assemblages, despite differences in environmental conditions and species composition between regions. Variance in fish abundance and assemblage characteristics from both regions was best explained by metrics of stream size and associated metrics (width, depth, conductivity and instream cover). Our results provide a framework and reference for conditions and assemblage structure in North American prairie streams.

  13. Influential environmental gradients and spatiotemporal patterns of fish assemblages in the unimpounded Upper Mississippi River

    USGS Publications Warehouse

    Barko, V.A.; Palmer, M.W.; Herzog, D.P.; Ickes, B.S.

    2004-01-01

    We investigated variation of fish assemblages in response to environmental factors using Long Term Resource Monitoring Program data. Data were collected from 1993 to 2000 from five physical habitats in the unimpounded upper Mississippi River. We captured 89 species composing 18 families. Of these, 26% were fluvial specialists, 25% were fluvial dependent and 49% were generalists. The numerically dominant component of the adult fish assemblage (species accounting for >10% of total catch) accounted for 50% of the assemblage and was comprised of only three species: gizzard shad (Dorosoma cepedianum; 25%), common carp (Cyprinus carpio, 15%) and channel catfish (Ictalurus punctatus, 10%). The dominant component of the YOY fish assemblage was comprised of only two species, which accounted for 76% of the total catch: freshwater drum (Aplodinotus grunniens; 39%) and gizzard shad (37%). We used a cross-validation multivariate approach to explore how adult and young-of-the-year (YOY) assemblages varied with respect. to physical habitat and environmental gradients. Furthermore, we were interested how the fish assemblages changed over time. Partial canonical correspondence analyses (pCCA) demonstrated significant effects of physical habitats. Such effects differed between young-of-the-year and adult fishes. The four main environmental gradients influencing overall assemblage structure for both age groups were river elevation, water velocity, conductivity, and depth of gear deployment. Morisita's index revealed similar adult assemblage structure over time. However, the YOY assemblage present in 1995 was dissimilar from assemblages present during the other years. We speculate this is a lag effect from the backwater spawning episodes (floodpulse) that occurred with the 500-y flood in 1993. Shannon-Weiner diversity and Camargo's evenness indices were low, but stable across years for the adult assemblage, but varied across years for the YOY assemblage.

  14. Giardia Assemblages A and B in Diarrheic Patients: A Comparative Study in Egyptian Children and Adults.

    PubMed

    El Basha, Noussa R; Zaki, Mayssa M; Hassanin, Omayma M; Rehan, Mohamed K; Omran, Dalia

    2016-02-01

    Giardia duodenalis is considered the most common intestinal parasite in humans worldwide. Children are especially affected, with more severe consequences than adults. The present study was designed to determine the distribution of assemblages A and B Giardia infection in children and adults, with the use of light microscopy and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) as diagnostic procedures, and to investigate its associations with clinical and epidemiological data collected from children and adult groups. This cross-sectional study was conducted from October 2012 to October 2013 by collecting fecal samples from 200 children and 200 adults complaining of diarrhea. Samples were subjected to parasitological examination by direct wet smear and formol-ether methods. Genotyping of G. doudenalis samples was conducted by PCR-RFLP analysis. Giardia duodenalis infection caused by assemblages A and B was identified in 60 samples, 34 from children and 26 from adults. Assemblage B was detected in 38 patients (63.34%), and assemblage A was detected in 22 patients (36.66%). Assemblage A was significantly more frequent in children with age range 2-8 yr, and assemblage B was higher in children with age range 6-16 yr old. Diarrhea frequency/day and recurrences per month affected patients infected with assemblage A (P value < 0.001) more frequently. Children infected with assemblage A presented significantly more severe diarrhea and dehydration than those infected with assemblage B (P value < 0.001). Although both Giardia assemblages A and B were identified in children and adults, assemblage A infected younger children more frequently and was more closely related to severe clinical manifestations than assemblage B. PMID:26509291

  15. Temporal changes in taxonomic and functional diversity of fish assemblages downstream from mountaintop mining

    USGS Publications Warehouse

    Hitt, Nathaniel P.; Chambers, Douglas B.

    2014-01-01

    Mountaintop mining (MTM) affects chemical, physical, and hydrological properties of receiving streams, but the long-term consequences for fish-assemblage structure and function are poorly understood. We sampled stream fish assemblages using electrofishing techniques in MTM exposure sites and reference sites within the Guyandotte River basin, USA, during 2010–2011. We calculated indices of taxonomic diversity (species richness, abundance, Shannon diversity) and functional diversity (functional richness, functional evenness, functional divergence) to compare exposure and reference assemblages between seasons (spring and autumn) and across years (1999–2011). We based temporal comparisons on 2 sites that were sampled during 1999–2001 by Stauffer and Ferreri (2002). Exposure assemblages had lower taxonomic and functional diversity than reference assemblages or simulated assemblages that accounted for random variation. Differences in taxonomic composition between reference and exposure assemblages were associated with conductivity and aqueous Se concentrations. Exposure assemblages had fewer species, lower abundances, and less biomass than reference assemblages across years and seasons. Green Sunfish (Lepomis cyanellus) and Creek Chub (Semotilus atromaculatus) became numerically dominant in exposure assemblages over time because of their persistence and losses of other taxa. In contrast, species richness increased over time in reference assemblages, a result that may indicate recovery from drought. Mean individual biomass increased as fish density decreased and most obligate invertivores were apparently extirpated at MTM exposure sites. Effects of MTM were not related to physical-habitat conditions but were associated with water-quality variables, which may limit quality and availability of benthic macroinvertebrate prey. Simulations revealed effects of MTM that could not be attributed to random variation in fish assemblage structure.

  16. CASTLE3D - A Computer Aided System for Labelling Archaeological Excavations in 3D

    NASA Astrophysics Data System (ADS)

    Houshiar, H.; Borrmann, D.; Elseberg, J.; Nüchter, A.; Näth, F.; Winkler, S.

    2015-08-01

    Documentation of archaeological excavation sites with conventional methods and tools such as hand drawings, measuring tape and archaeological notes is time consuming. This process is prone to human errors and the quality of the documentation depends on the qualification of the archaeologist on site. Use of modern technology and methods in 3D surveying and 3D robotics facilitate and improve this process. Computer-aided systems and databases improve the documentation quality and increase the speed of data acquisition. 3D laser scanning is the state of the art in modelling archaeological excavation sites, historical sites and even entire cities or landscapes. Modern laser scanners are capable of data acquisition of up to 1 million points per second. This provides a very detailed 3D point cloud of the environment. 3D point clouds and 3D models of an excavation site provide a better representation of the environment for the archaeologist and for documentation. The point cloud can be used both for further studies on the excavation and for the presentation of results. This paper introduces a Computer aided system for labelling archaeological excavations in 3D (CASTLE3D). Consisting of a set of tools for recording and georeferencing the 3D data from an excavation site, CASTLE3D is a novel documentation approach in industrial archaeology. It provides a 2D and 3D visualisation of the data and an easy-to-use interface that enables the archaeologist to select regions of interest and to interact with the data in both representations. The 2D visualisation and a 3D orthogonal view of the data provide cuts of the environment that resemble the traditional hand drawings. The 3D perspective view gives a realistic view of the environment. CASTLE3D is designed as an easy-to-use on-site semantic mapping tool for archaeologists. Each project contains a predefined set of semantic information that can be used to label findings in the data. Multiple regions of interest can be joined under

  17. Middle Ordovician organic matter assemblages and their effect on Ordovician-derived oils

    SciTech Connect

    Jacobson, S.R.; Hatch, J.R.; Teerman, S.C.; Askin, R.A.

    1988-09-01

    Two distinct Middle Ordovician oil-prone organic-matter assemblages occur in thermally immature to marginally mature petroleum source rocks from Iowa. The substantially more oil-prone Assemblage A generates the unique Ordovician Oil fingerprint, which has been associated with the organic-walled microfossil Gloeocapsamorpha prisca. The second, Assemblage B, generates a more ordinary signature. The two assemblages, which are mixed or interbedded in many Ordovician sediments of North America, explain the variations in oils derived from Ordovician source rocks. These mixtures also aid in interpretation of the chemistry of G. prisca. 7 figures, 2 tables.

  18. Effects of hydrologic connectivity on aquatic macroinvertebrate assemblages in different marsh types

    USGS Publications Warehouse

    Kang, Sung-Ryong; King, Sammy L.

    2013-01-01

    Hydrologic connectivity can be an important driver of aquatic macroinvertebrate assemblages. Its effects on aquatic macroinvertebrate assemblages in coastal marshes, however, are relatively poorly studied. We evaluated the effects of lateral hydrologic connectivity (permanently connected ponds: PCPs; temporary connected ponds: TCPs), and other environmental variables on aquatic macroinvertebrate assemblages and functional feeding groups (FFGs) in freshwater, brackish, and saline marshes in Louisiana, USA. We hypothesized that (1) aquatic macroinvertebrate assemblages in PCPs would have higher assemblage metric values (density, biomass, Shannon-Wiener diversity) than TCPs and (2) the density and proportional abundance of certain FFGs (i.e. scrapers, shredders, and collectors) would be greater in freshwater marsh than brackish and saline marshes. The data in our study only partially supported our first hypothesis: while freshwater marsh PCPs had higher density and biomass than TCPs, assemblage metric values in saline TCPs were greater than saline PCPs. In freshwater TCPs, long duration of isolation limited access of macroinvertebrates from adjacent water bodies, which may have reduced assemblage metric values. However, the relatively short duration of isolation in saline TCPs provided more stable or similar habitat conditions, facilitating higher assemblage metric values. As predicted by our second hypothesis, freshwater PCPs and TCPs supported a greater density of scrapers, shredders, and collectors than brackish and saline ponds. Aquatic macroinvertebrate assemblages seem to be structured by individual taxa responses to salinity as well as pond habitat attributes.

  19. Biological structure and dynamics of littoral fish assemblages in the eastern Finger Lakes

    USGS Publications Warehouse

    McKenna, James E., Jr.

    2001-01-01

    Fish assemblages from three of the New York Finger Lakes were examined for structure within and between lakes and over time. Species-area relationships indicated that local fish assemblages are the result of recent, lake-specific events that altered the regional species pool. Fish assemblages varied among seasons and those occupying eutrophic waters had different characteristics from those in oligotrophic waters. Bluntnose minnows (Pimephales notatus) were a persistent and important component of most assemblages, but abundance of bluegill (Lepomis macrochirus) was the most distinguishing feature. Species associations indicated that interactions among the fishes had little influence on assemblage structure. Correlations between community structure and abiotic factors were identified. Ten abiotic variables were strongly associated with the species assemblages, but could not fully explain differences between assemblages. Results indicate that the abundance and diversity of water column feeders was related to productivity of lake habitat. In general, fish populations were smaller in oligotrophic waters and water column feeders were poorly represented in those assemblages. Productivity at various trophic levels was implicated as a major factor determining lake fish assemblage structure.

  20. Land use structures fish assemblages in reservoirs of the Tennessee River

    USGS Publications Warehouse

    Miranda, Leandro E.; Bies, J. M.; Hann, D. A.

    2015-01-01

    Inputs of nutrients, sediments and detritus from catchments can promote selected components of reservoir fish assemblages, while hindering others. However, investigations linking these catchment subsidies to fish assemblages have generally focussed on one or a handful of species. Considering this paucity of community-level awareness, we sought to explore the association between land use and fish assemblage composition in reservoirs. To this end, we compared fish assemblages in reservoirs of two sub-basins of the Tennessee River representing differing intensities of agricultural development, and hypothesised that fish assemblage structure indicated by species percentage composition would differ among reservoirs in the two sub-basins. Using multivariate statistical analysis, we documented inter-basin differences in land use, reservoir productivity and fish assemblages, but no differences in reservoir morphometry or water regime. Basins were separated along a gradient of forested and non-forested catchment land cover, which was directly related to total nitrogen, total phosphorous and chlorophyll-a concentrations. Considering the extensive body of knowledge linking land use to aquatic systems, it is reasonable to postulate a hierarchical model in which productivity has direct links to terrestrial inputs, and fish assemblages have direct links to both land use and productivity. We observed a shift from an invertivore-based fish assemblage in forested catchments to a detritivore-based fish assemblage in agricultural catchments that may be a widespread pattern among reservoirs and other aquatic ecosystems.

  1. Patterns in species richness and assemblage structure of native mussels in the Upper Mississippi River

    USGS Publications Warehouse

    Zigler, Steven J.; Newton, Teresa J.; Davis, Mike; Rogala, James T.

    2012-01-01

    1. To evaluate patterns in mussel assemblages in the Upper Mississippi River (UMR), data from systematic surveys of mussels conducted in three large reaches (Navigation Pools 5, 6, and 18) from 2005–2007 were analysed. 2. Nonmetric multi-dimensional scaling analyses and permutation tests indicated that assemblages differed among reaches. The mussel assemblage in Pool 18 was substantially different from the assemblage in Pool 5 and moderately different from the assemblage in Pool 6, whereas assemblages in Pools 5 and 6 were similar. Assemblages in broadly defined, flowing aquatic habitats did not substantially differ. 3. The dissimilarity of Pool 18 was primarily the result of Pool 18 having higher abundances of three Quadrula species (Q. quadrula, Q. pustulosa, and Q. nodulata), and lower abundances of Amblema plicata and Fusconaia flava. 4. Rarefaction analyses showed that species richness and species density were higher in Pool 18 compared with the other two pools. 5. Large-scale patterns in mussel assemblages may be related to other longitudinal trends in the system including geomorphology, water quality, and abundances of fish species that serve as hosts for glochidial larvae. 6. The results suggest that management goals and actions in the UMR may need to account for important differences in mussel assemblages that occur among reaches.

  2. Effects of Reef Proximity on the Structure of Fish Assemblages of Unconsolidated Substrata

    PubMed Central

    Schultz, Arthur L.; Malcolm, Hamish A.; Bucher, Daniel J.; Smith, Stephen D. A.

    2012-01-01

    Fish assemblages of unconsolidated sedimentary habitats on continental shelves are poorly described when compared to those of hard substrata. This lack of data restricts the objective management of these extensive benthic habitats. In the context of protecting representative areas of all community types, one important question is the nature of the transition from reefal to sedimentary fish assemblages. We addressed this question using Baited Remote Underwater Videos (BRUVs) to assess fish assemblages of sedimentary habitats at six distances from rocky reefs (0, 25, 50, 100, 200, and 400 m) at four sites in subtropical eastern Australia. Distance from reef was important in determining fish assemblage structure, and there was no overlap between reef sites and sedimentary sites 400 m from reef. While there was a gradient in assemblage structure at intermediate distances, this was not consistent across sites. All sites, however, supported a mixed ‘halo’ assemblage comprising both reef and sediment species at sampling stations close to reef. BRUVs used in conjunction with high-resolution bathymetric and backscatter spatial data can resolve differences in assemblage structure at small spatial scales (10s to 100s of metres), and has further application in unconsolidated habitats. Unless a ‘reef halo’ assemblage is being examined, a minimum of 200 m but preferably 400 m distance from any hard substrate is recommended when designing broader-scale assessments of fish assemblages of sedimentary habitats. PMID:23189145

  3. Macroalgal assemblages of disturbed coastal detritic bottoms subject to invasive species

    NASA Astrophysics Data System (ADS)

    Klein, Judith C.; Verlaque, Marc

    2009-04-01

    Characteristic flora and fauna that are highly sensitive to disturbances colonize coastal detritic bottoms in the Mediterranean Sea. In the present study, a comparison of the assemblage composition and colonization by invasive macroalgae was made between two coastal detritic macrophyte assemblages, one dominated by rhodoliths (free-living non-geniculate Corallinales) and the other dominated by fleshy algae, in an area that has been exposed to important levels of anthropogenic disturbance, mainly pollution (including changed sedimentation regimes) in the recent past (bay of Marseilles, France). In comparison with less strongly impacted Mediterranean regions, the macrophyte assemblages in the bay of Marseilles were characteristic in terms of species identity and richness of coastal detritic macrophyte assemblages. However, extremely low species abundance (cover) was observed. As far as invasive species were concerned, Caulerpa racemosa var. cylindracea was only abundant in the rhodolith assemblage whereas the two invasive Rhodophyta Asparagopsis armata and Womersleyella setacea were mainly found in the fleshy algae assemblage. The seasonality observed in the Rhodolith assemblage seemed to be related to the development of C. racemosa var. cylindracea and did not follow the typical pattern of other Mediterranean assemblages. This study represents the first study of coastal detritic assemblages invaded by C. racemosa var. cylindracea.

  4. Autumn ichthyoplankton assemblage in the Yangtze Estuary shaped by environmental factors

    PubMed Central

    Liu, Shude

    2016-01-01

    This study investigated the response of the ichthyoplankton community to environmental changes in the Yangtze Estuary using canonical correspondence analysis. Ichthyoplankton community and environmental data were recorded during the autumns of 1998, 2000, 2002, 2003, 2004, 2007 and 2009. Among the ichthyoplankton, the dominant larval and juvenile families were the Engraulidae, Gobiidae and Salangidae, and the most common eggs were from Trichiurus lepturus. The ichthyoplankton was identified via canonical correspondence analysis to three assemblages: an estuary assemblage dominated by Chaeturichthys stigmatias, a coastal assemblage dominated by Engraulis japonicus and Stolephorus commersonii, and an offshore assemblage dominated by Trichiurus lepturus. Regarding environmental factors in the Yangtze Estuary, suspended matter and surface seawater salinity were the main factors influencing the distributions of the different assemblages, while sediment from the Yangtze River during the rainy season and chlorophyll a were the principle drivers of the annual variances in the distribution of ichthyoplankton assemblages. Our aims in this study were to provide detailed characterizations of the ichthyoplankton assemblage in the autumns of seven years, examine the long-term dynamics of autumn ichthyoplankton assemblages, and evaluate the influence of environmental factors on the spatial distribution and inter-annual variations of ichthyoplankton assemblages associated with the Yangtze Estuary. PMID:27114877

  5. Excavation of Tunnel Valleys and Inner Gorges by Subglacial Meltwater Erosion

    NASA Astrophysics Data System (ADS)

    Beaud, F.; Flowers, G. E.; Venditti, J. G.; Koppes, M. N.

    2015-12-01

    Subglacial meltwater erosion (SME) is thought to contribute to the excavation of tunnel valleys and inner gorges, yet the underpinnings of the formation of these landforms remain obscure. Tunnel valleys are large channel-like features (100s of metres to few kilometres wide and up to 10s of kilometres in length) commonly found in the vicinity of former continental ice-sheet margins. The main question concerning their formation is: does SME excavate them gradually or by large subglacial floods? Inner gorges are V-shaped incisions in an otherwise glacially overprinted landscape. The initial assertion of their fluvial origin has recently been disputed, as they have been shown to persist through multiple glaciations and SME has been invoked to explain some inner gorges in Scandinavia and the Alps. The question is therefore: can SME explain the excavation of an inner gorge? In order to test these hypotheses related to the genesis of tunnel valleys and inner gorges, we use a 1-D model of subglacial hydrology to drive a model of bedrock erosion by total sediment load based on the tools and cover effect. Calculated values of subglacial transport stage in response to ordinary seasonal processes are comparable to those during large floods in rivers. Subglacial floods therefore limit bedrock erosion by transporting sediment farther from the bed, thus inhibiting impacts. Consequently, we find that gradual SME is likely to produce more incision over a glacial cycle. When we simulate the total SME that occurs through a glacial cycle under a synthetic ice-sheet margin, we are able to produce tunnel valleys or inner gorges over the timespan of a glaciation. Based on these results, we propose that (1) tunnel valleys and inner gorges can both be the result of SME, (2) tunnel valleys in bedrock can be formed through gradual processes rather than floods, and (3) SME enhances inner gorge relief.

  6. In situ measurements of rock salt permeability changes due to nearby excavation

    SciTech Connect

    Stormont, J.C. ); Howard, C.L. ); Daemen, J.J.K. . Mackay School of Mines)

    1991-07-01

    The Small-Scale Mine-By was an in situ experiment to measure changes in brine and gas permeability of rock salt as a result of nearby excavation. A series of small-volume pressurized brine- and gas-filled test intervals were established 8 m beneath the floor of Room L1 in the WIPP underground. The test intervals were isolated in the bottom of the 4.8-cm diameter monitoring boreholes with inflatable rubber packers, and are initially pressurized to about 2 MPa. Both brine- and gas-filled test intervals were located 1.25, 1.5, 2, 3, and 4 r from the center of a planned large-diameter hole, where r is the radius of the large-diameter hole. Prior to the drilling of the large-diameter borehole, the responses of both the brine- and gas-filled test intervals were consistent with the formation modeled as a very low permeability, low porosity porous medium with a significant pore (brine) pressure and no measurable gas permeability. The drilling of the mine-by borehole created a zone of dilated, partially saturated rock out to about 1.5 r. The formation pressure increases from near zero at 1.5 r to the pre-excavation value at 4 r. Injection tests reveal a gradient of brine permeabilities from 5 {times} 10{sup {minus}18} m{sup 2} at 1.25 r to about the pre-excavation value (10{sup {minus}21} m{sup 2}) by 3 r. Gas-injection tests reveal measurable gas permeability is limited to within 1.5 r. 17 refs., 24 figs., 6 tabs.

  7. Natural diet of coral-excavating sponges consists mainly of dissolved organic carbon (DOC).

    PubMed

    Mueller, Benjamin; de Goeij, Jasper M; Vermeij, Mark J A; Mulders, Yannick; van der Ent, Esther; Ribes, Marta; van Duyl, Fleur C

    2014-01-01

    Coral-excavating sponges are the most important bioeroders on Caribbean reefs and increase in abundance throughout the region. This increase is commonly attributed to a concomitant increase in food availability due to eutrophication and pollution. We therefore investigated the uptake of organic matter by the two coral-excavating sponges Siphonodictyon sp. and Cliona delitrix and tested whether they are capable of consuming dissolved organic carbon (DOC) as part of their diet. A device for simultaneous sampling of water inhaled and exhaled by the sponges was used to directly measure the removal of DOC and bacteria in situ. During a single passage through their filtration system 14% and 13% respectively of the total organic carbon (TOC) in the inhaled water was removed by the sponges. 82% (Siphonodictyon sp.; mean ± SD; 13 ± 17 μmol L(-1)) and 76% (C. delitrix; 10 ± 12 μmol L(-1)) of the carbon removed was taken up in form of DOC, whereas the remainder was taken up in the form of particulate organic carbon (POC; bacteria and phytoplankton) despite high bacteria retention efficiency (72 ± 15% and 87 ± 10%). Siphonodictyon sp. and C. delitrix removed DOC at a rate of 461 ± 773 and 354 ± 562 μmol C h(-1) respectively. Bacteria removal was 1.8 ± 0.9 × 10(10) and 1.7 ± 0.6 × 10(10) cells h(-1), which equals a carbon uptake of 46.0 ± 21.2 and 42.5 ± 14.0 μmol C h(-1) respectively. Therefore, DOC represents 83 and 81% of the TOC taken up by Siphonodictyon sp. and C. delitrix per hour. These findings suggest that similar to various reef sponges coral-excavating sponges also mainly rely on DOC to meet their carbon demand. We hypothesize that excavating sponges may also benefit from an increasing production of more labile algal-derived DOC (as compared to coral-derived DOC) on reefs as a result of the ongoing coral-algal phase shift. PMID:24587253

  8. The initiatives of the Los Alamos Scientific Laboratory in the transfer of a new excavation technology

    NASA Technical Reports Server (NTRS)

    Hanold, R. J.; Bankston, C. A.; Rowley, J. C.; Long, W. W.

    1974-01-01

    A system for making vertical or horizontal holes in rock or soil by progressive local melting is described. In one operation the three major tasks of excavation are performed with the Subterrene concept: (1) rock fracturing; (2) debris removal; and (3) wall stabilization. Potential applications of the Subterrene system are indicated, with emphasis on extraction of geothermal energy and development of superconduction transmission lines for electrical power. A program in technology dissemination implemented by the staff members is described. It is indicated that a large scale commercial utilization of the technology is required to complete the transfer of technology.

  9. Towards a web-based archaeological excavation platform for smartphones: review and potentials.

    PubMed

    Styliaras, Georgios

    2015-01-01

    The paper conducts a review questioning the usability of a web-based platform supporting archaeological excavations and related fields, which will execute on smartphones. Based on the thorough review and comparison of related work, the basic features of such a platform are outlined. The platform should support documenting content on an underlying XML database through a content management system, producing and exchanging notes, map interaction, use of a shared whiteboard, collaboration among archaeologists etc. The architecture of the platform is presented along with two case studies supporting usual practices on an archaeological field, some primary evaluation results and future work. PMID:26155450

  10. Mobile system for extracting spilled hazardous materials from excavated soils. Final report Dec 76-Apr 82

    SciTech Connect

    Scholz, R.; Milanowski, J.

    1983-10-01

    Laboratory tests were conducted with three separate pollutants (phenol, arsenic trioxide, and polychlorinated biphenyls (PCB's) and two soils of widely different characteristics (sand/gravel/silt/clay and organic loam) to evaluate techniques for cleansing soil contaminated with released or spilled hazardous materials. The tests show that scrubbing of excavated soil on site is an efficient approach for freeing soils of certain contaminants but that the effectiveness depends on the washing fluid (water + additives) and on the soil composition and particle size distribution. Based on the test results, a full-scale, field-use system was designed, engineered, fabricated, assembled, and briefly tested; the unit is now ready for field demonstrations.

  11. The evaluation of support performance for tunnels with different diameters excavated in weak graphitic shists

    NASA Astrophysics Data System (ADS)

    Posluk, Evren; Oğul, Kenan

    2015-04-01

    2. stage (İnönü-Köseköy) of Ankara-İstanbul High-Speed Train Project (YHT) is 150 km-long and includes 25 tunnels with total length of nearly 58 km. The 7765 m-long part of these tunnels between Bozüyük and Bilecik was excavated in the metamorphic units of Pazarcık Structural Complex which have different thicknesses and form horizontal and vertical transitions to each other. The folded weak graphitic schists with thin schistosity planes affect the tunnel support performance negatively. In this study, the tunnels with 13.5, 8.2 and 4 m-diameters excavated in the weak-very weak graphitic schists by the conventional methods and the reasons of the problems (overbreak, deformation higher than estimated, wreckage etc.) are examined. The most common problems in the tunnel construction are overbreak and deformations higher than estimated before. Upsizing the fore-polling diameters, injection with pressure and carving the tunnel face were the first applied methods for decreasing the overbreak in the wide tunnels. Although these methods decreased the overbreak, the deformations in the tunnel couldn't be prevented. In this context, the data derived from the rod and tape extensometers was examined, the elastic and plastic zones were determined, the creep behaviour was locally observed on the support elements during 65 days. Also the mass parameters (GSI, weight per unit of volume, uniaxial compression, modulus of elasticity, modulus of deformation etc.) of the weak-very weak rocks were evaluated again. By the help of the compiled data it was determined that when the tunnel diameter increases, the deformation and overbreak increase. For example, while there are approximately two overbreaks at each 100 m in a 4 m-diameter tunnel, it is three in a 8.2 m-diameter tunnel and six in a 13.5 m-diameter tunnel. The deformations were estimated as 8 cm in a 4 m-diameter tunnel, 15 cm in a 8.2 m-diameter tunnel, 20 cm in a 13.5 m-diameter tunnel. However they are respectively 7

  12. Technical note: Efficient removal of a PCR inhibitory agent (vivianite) found on excavated bones.

    PubMed

    Votrubova-Dubska, Jitka; Vanek, Daniel; Zikmund, Jaroslav; Mestek, Oto; Urbanova, Vladislava; Brzobohata, Hana; Brestovansky, Petr

    2016-04-01

    During a rescue excavation in October 2011, archaeologists discovered a mass grave with 10 individuals. The skeletons should belong to victims of the battle of Reichenberg between the Austrian and Prussian armies on April 21, 1757. Several bones of the skeletons were covered with a blue colored encrustation. Initial DNA analysis failed due to strong inhibition. Chemical analysis of the bluish encrustation indicated the presence of the iron phosphate mineral vivianite (Fe3(PO4)2·(H2O)8). This technical note describes a novel procedure for the removal of this inhibitory substance. PMID:26874049

  13. Geotechnical issues and guidelines for storage of compressed air in excavated hard rock caverns

    SciTech Connect

    Allen, R.D.; Doherty, T.J.; Fossum, A.F.

    1982-04-01

    The results of a literature survey on the stability of excavated hard rock caverns are presented. The objective of the study was to develop geotechnical criteria for the design of compressed air energy storage (CAES) caverns in hard rock formations. These criteria involve geologic, hydrological, geochemical, geothermal, and in situ stress state characteristics of generic rock masses. Their relevance to CAES caverns, and the identification of required research areas, are identified throughout the text. This literature survey and analysis strongly suggests that the chief geotechnical issues for the development and operation of CAES caverns in hard rock are impermeability for containment, stability for sound openings, and hydrostatic balance.

  14. Application of the Bang and Ramm age at death estimation method to two known-age archaeological assemblages.

    PubMed

    Tang, Nancy; Antoine, Daniel; Hillson, Simon

    2014-11-01

    The Bang and Ramm method uses root dentine translucency (RDT) length in sectioned or unsectioned teeth as a sole indicator of chronological age at death in adult human remains. The formulae have been tested on modern remains of known age and on modern and archaeological remains of unknown age. This is the first published study of the method on known-age archaeological specimens and tests whether RDT is a good indicator of chronological age in buried human remains. We applied the Bang and Ramm equations to two 18th and 19th century assemblages excavated from the crypt of Christ Church, Spitalfields, and the cemetery of All Hallows by the Tower. Translucency was defined by shining a light through the external unsectioned root surface and was measured from digital images of 583 and 83 nonmolar roots from 126 Spitalfields and 12 All Hallows individuals, respectively, aged 21-81 years. Average absolute difference between real age and estimated age was 10.7 years and 8.4 years for Spitalfields and All Hallows individuals, respectively, with 58% and 75% estimated within 10 years of known age, and 29% and 33% estimated within five years of known age. These estimations are comparable to results from other ageing methods applied to the Spitalfields collection. Ages from both populations were estimated largely to the middle ranges, with younger individuals overestimated and older individuals underestimated. This is a common occurrence when using inverse calibration, where age is treated as the dependent variable and the ageing feature as the independent variable. PMID:25043454

  15. Coastal Upwelling Drives Intertidal Assemblage Structure and Trophic Ecology

    PubMed Central

    Reddin, Carl J.; Docmac, Felipe; O’Connor, Nessa E.; Bothwell, John H.; Harrod, Chris

    2015-01-01

    Similar environmental driving forces can produce similarity among geographically distant ecosystems. Coastal oceanic upwelling, for example, has been associated with elevated biomass and abundance patterns of certain functional groups, e.g., corticated macroalgae. In the upwelling system of Northern Chile, we examined measures of intertidal macrobenthic composition, structure and trophic ecology across eighteen shores varying in their proximity to two coastal upwelling centres, in a hierarchical sampling design (spatial scales of >1 and >10 km). The influence of coastal upwelling on intertidal communities was confirmed by the stable isotope values (δ13C and δ15N) of consumers, including a dominant suspension feeder, grazers, and their putative resources of POM, epilithic biofilm, and macroalgae. We highlight the utility of muscle δ15N from the suspension feeding mussel, Perumytilus purpuratus, as a proxy for upwelling, supported by satellite data and previous studies. Where possible, we used corrections for broader-scale trends, spatial autocorrelation, ontogenetic dietary shifts and spatial baseline isotopic variation prior to analysis. Our results showed macroalgal assemblage composition, and benthic consumer assemblage structure, varied significantly with the intertidal influence of coastal upwelling, especially contrasting bays and coastal headlands. Coastal topography also separated differences in consumer resource use. This suggested that coastal upwelling, itself driven by coastline topography, influences intertidal communities by advecting nearshore phytoplankton populations offshore and cooling coastal water temperatures. We recommend the isotopic values of benthic organisms, specifically long-lived suspension feeders, as in situ alternatives to offshore measurements of upwelling influence. PMID:26214806

  16. Pollen assemblages as paleoenvironmental proxies in the Florida Everglades

    USGS Publications Warehouse

    Willard, D.A.; Weimer, L.M.; Riegel, W.L.

    2001-01-01

    Analysis of 170 pollen assemblages from surface samples in eight vegetation types in the Florida Everglades indicates that these wetland sub-environments are distinguishable from the pollen record and that they are useful proxies for hydrologic and edaphic parameters. Vegetation types sampled include sawgrass marshes, cattail marshes, sloughs with floating aquatics, wet prairies, brackish marshes, tree islands, cypress swamps, and mangrove forests. The distribution of these vegetation types is controlled by specific environmental parameters, such as hydrologic regime, nutrient availability, disturbance level, substrate type, and salinity; ecotones between vegetation types may be sharp. Using R-mode cluster analysis of pollen data, we identified diagnostic species groupings; Q-mode cluster analysis was used to differentiate pollen signatures of each vegetation type. Cluster analysis and the modern analog technique were applied to interpret vegetational and environmental trends over the last two millennia at a site in Water Conservation Area 3A. The results show that close modern analogs exist for assemblages in the core and indicate past hydrologic changes at the site, correlated with both climatic and land-use changes. The ability to differentiate marshes with different hydrologic and edaphic requirements using the pollen record facilitates assessment of relative impacts of climatic and anthropogenic changes on this wetland ecosystem on smaller spatial and temporal scales than previously were possible. ?? 2001 Elsevier Science B.V.

  17. Niche partitioning and species coexistence in a Neotropical felid assemblage

    NASA Astrophysics Data System (ADS)

    Di Bitetti, Mario S.; De Angelo, Carlos D.; Di Blanco, Yamil E.; Paviolo, Agustín

    2010-07-01

    Carnivores have been used as a model to understand the effects of competition in community structure. Behavioral mechanisms that facilitate species coexistence have been poorly explored and may explain the lack of community-wide morphological character displacement in some carnivore assemblages. We use the results of large-scale and intensive camera-trap surveys conducted in the Atlantic Forest of NE Argentina between 2003 and 2008 to describe the spatial patterns of detection and the daily pattern of records of the six wild cat species present in the region (jaguar Panthera onca, puma Puma concolor, ocelot Leopardus pardalis, jaguarundi Puma yagouaroundi, margay Leopardus wiedii, and oncilla Leopardus tigrinus). We use these patterns to generate hypotheses about behavioral differences that may facilitate species coexistence. The larger species were more frequently recorded in the better-protected areas, probably as a result of anthropogenic effects (poaching of cats and their prey). Competitive release from ocelots and jaguarundis may explain why the oncilla and the margay showed the opposite pattern. Morphologically similar species had the most contrasting activity patterns: the margay was exclusively nocturnal and the jaguarundi diurnal. The other species were cathemeral, but alternated their peaks of activity in relation to the relative order of their body weights. The contrasting temporal patterns observed and the ability of pumas and oncillas to adjust their activity patterns to local conditions may facilitate the coexistence of these cat species and explain the lack of character displacement in this assemblage.

  18. Limnic sediments and the taphonomy of Lateglacial pollen assemblages

    NASA Astrophysics Data System (ADS)

    Pennington, Winifred; Tutin, T. G.

    Pollen taphonomy, defined by R.G. West in 1973 as "the processes which govern the production of fossil (pollen) assemblages from living vegetation", introduces an additional variable into the pollen/vegetation relationship. Changes in taphonomic factors, of the kind to be expected within cold-stage Quaternary environments, may influence the composition of pollen assemblages, producing variations between them in space and time which are not directly related to variation in vegetation. Comparisons between sites — 35 Lateglacial (Late Devensian) lake sediment profiles within a 40 × 40 km region of high relief — are used to identify situations where anomalies in pollen values can be attributed to taphonomic factors. Processes involved include: redeposition of older pollen from soils (recycling) during episodes of increased instability of the land surface; spatial differentiation in deposition of sediment and pollen within the larger lakes, associated with a within-lake water circulation very different from today's; selective recruitment of pollen taxa by glacial meltwater; a) of Salix by outlet streams from small glaciers associated with favourable habitats for willows, and b) of Pinus from grains trapped by extensive mountain snowfields and larger glaciers.

  19. Rhizosphere microbiome assemblage is affected by plant development

    PubMed Central

    Chaparro, Jacqueline M; Badri, Dayakar V; Vivanco, Jorge M

    2014-01-01

    There is a concerted understanding of the ability of root exudates to influence the structure of rhizosphere microbial communities. However, our knowledge of the connection between plant development, root exudation and microbiome assemblage is limited. Here, we analyzed the structure of the rhizospheric bacterial community associated with Arabidopsis at four time points corresponding to distinct stages of plant development: seedling, vegetative, bolting and flowering. Overall, there were no significant differences in bacterial community structure, but we observed that the microbial community at the seedling stage was distinct from the other developmental time points. At a closer level, phylum such as Acidobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria and specific genera within those phyla followed distinct patterns associated with plant development and root exudation. These results suggested that the plant can select a subset of microbes at different stages of development, presumably for specific functions. Accordingly, metatranscriptomics analysis of the rhizosphere microbiome revealed that 81 unique transcripts were significantly (P<0.05) expressed at different stages of plant development. For instance, genes involved in streptomycin synthesis were significantly induced at bolting and flowering stages, presumably for disease suppression. We surmise that plants secrete blends of compounds and specific phytochemicals in the root exudates that are differentially produced at distinct stages of development to help orchestrate rhizosphere microbiome assemblage. PMID:24196324

  20. Primate assemblage structure in Amazonian flooded and unflooded forests.

    PubMed

    Haugaasen, Torbjørn; Peres, Carlos A

    2005-10-01

    There is considerable variation in primate species richness across neotropical forest sites, and the richest assemblages are found in western Amazonia. Forest type is an important determinant of the patterns of platyrrhine primate diversity, abundance, and biomass. Here we present data on the assemblage structure of primates in adjacent unflooded (terra firme) and seasonally inundated (várzea and igapó) forests in the lower Purús region of central-western Brazilian Amazonia. A line-transect census of 2,026 km in terra firme, 2,309 km in várzea, and 277 km in igapó was conducted. Twelve primate species were recorded from 2,059 primate group sightings. Although terra firme was found to be consistently more species-rich than várzea, the aggregate primate density in terra firme forest was considerably lower than that in the species-poor várzea. Consequently, the total biomass estimate was much higher in várzea compared to either terra firme or igapó forest. Brown capuchin monkeys (Cebus apella) were the most abundant species in terra firme, but were outnumbered by squirrel monkeys (Saimiri cf. ustus) in the várzea. The results suggest that floodplain forest is a crucial complement to terra firme in terms of primate conservation in Amazonian forests. PMID:16229024

  1. Influence of tuna penning activities on soft bottom macrobenthic assemblages.

    PubMed

    Mangion, Marija; Borg, Joseph A; Thompson, Richard; Schembri, Patrick J

    2014-02-15

    The influence of tuna penning on soft bottom habitat present in the vicinity of tuna pens and at distances 200 m and 1.5 km away, was assessed by comparing attributes of macroinvertebrate assemblages and sediment quality before (November 2000, March 2001) and after (November 2001, April 2002) initiation of the activity. Results from November 2001 indicated a significant increase in sediment organic carbon and organic nitrogen, and a non-significant increase in the abundance of Capitellidae in the vicinity of the cages. Similar results were obtained 200 m from the cages but not 1.5 km away, where the only change was a significant increase in organic nitrogen in sediment. Results from April 2002 indicated no significant change in sediment organic carbon and organic nitrogen, however, mean sediment grain size decreased significantly in the immediate vicinity of the cages. Changes in attributes of the benthic assemblages and sediment resulted from accumulation of uneaten feed-fish on the seabed. PMID:24447635

  2. "Controlling ourselves, by ourselves": risk assemblages on Malaysia's assembly lines.

    PubMed

    Root, Robin

    2008-01-01

    Since the early 1990s, the Malaysian government has identified factories as high risk for HIV and AIDS. Signaling epidemiological concerns over the rising rates of HIV among factory workers, a significant proportion of whom are women, the label also appeared to reconstitute stereotypes of factory women as dangerously sexual and of factories as immoral spaces. Drawing on ethnographic research in the export processing zones of Penang, Malaysia in the mid-1990s, I examine the meanings and experiences of HIV risk among factory women themselves. Data were analyzed using discourse and grounded theory methods, the former to identify women's multiple modes of rationalizing HIV risks, and the latter to theorize the sources and significance of women's HIV risk assemblages. The heuristic of assemblages as localized knowledge spaces helped to show that biomedical and socioreligious risk lexica operated not as fixed epistemological categories but as situational resources in women's risk scripts. Overall, women desired multiple risk knowledges to help them "control themselves by themselves," a project of reflexive self-shaping mediated by the diverse and discordant discourses of gender, ethnicity, and modernity in Malaysia that shaped how HIV risks were engendered and experienced. PMID:18958787

  3. Influence of landscape structure on reef fish assemblages

    USGS Publications Warehouse

    Grober-Dunsmore, R.; Frazer, T.K.; Beets, J.P.; Lindberg, W.J.; Zwick, P.; Funicelli, N.A.

    2008-01-01

    Management of tropical marine environments calls for interdisciplinary studies and innovative methodologies that consider processes occurring over broad spatial scales. We investigated relationships between landscape structure and reef fish assemblage structure in the US Virgin Islands. Measures of landscape structure were transformed into a reduced set of composite indices using principal component analyses (PCA) to synthesize data on the spatial patterning of the landscape structure of the study reefs. However, composite indices (e.g., habitat diversity) were not particularly informative for predicting reef fish assemblage structure. Rather, relationships were interpreted more easily when functional groups of fishes were related to individual habitat features. In particular, multiple reef fish parameters were strongly associated with reef context. Fishes responded to benthic habitat structure at multiple spatial scales, with various groups of fishes each correlated to a unique suite of variables. Accordingly, future experiments should be designed to test functional relationships based on the ecology of the organisms of interest. Our study demonstrates that landscape-scale habitat features influence reef fish communities, illustrating promise in applying a landscape ecology approach to better understand factors that structure coral reef ecosystems. Furthermore, our findings may prove useful in design of spatially-based conservation approaches such as marine protected areas (MPAs), because landscape-scale metrics may serve as proxies for areas with high species diversity and abundance within the coral reef landscape. ?? 2007 Springer Science+Business Media B.V.

  4. The 'Goldilocks' effect: preservation bias in vertebrate track assemblages.

    PubMed

    Falkingham, P L; Bates, K T; Margetts, L; Manning, P L

    2011-08-01

    Finite-element analysis was used to investigate the extent of bias in the ichnological fossil record attributable to body mass. Virtual tracks were simulated for four dinosaur taxa of different sizes (Struthiomimus, Tyrannosaurus, Brachiosaurus and Edmontosaurus), in a range of substrate conditions. Outlines of autopodia were generated based upon osteology and published soft-tissue reconstructions. Loads were applied vertically to the feet equivalent to the weight of the animal, and distributed accordingly to fore- and hindlimbs where relevant. Ideal, semi-infinite elastic-plastic substrates displayed a 'Goldilocks' quality where only a narrow range of loads could produce tracks, given that small animals failed to indent the substrate, and larger animals would be unable to traverse the area without becoming mired. If a firm subsurface layer is assumed, a more complete assemblage is possible, though there is a strong bias towards larger, heavier animals. The depths of fossil tracks within an assemblage may indicate thicknesses of mechanically distinct substrate layers at the time of track formation, even when the lithified strata appear compositionally homogeneous. This work increases the effectiveness of using vertebrate tracks as palaeoenvironmental indicators in terms of inferring substrate conditions at the time of track formation. Additionally, simulated undertracks are examined, and it is shown that complex deformation beneath the foot may not be indicative of limb kinematics as has been previously interpreted, but instead ridges and undulations at the base of a track may be a function of sediment displacement vectors and pedal morphology. PMID:21233145

  5. Coastal Upwelling Drives Intertidal Assemblage Structure and Trophic Ecology.

    PubMed

    Reddin, Carl J; Docmac, Felipe; O'Connor, Nessa E; Bothwell, John H; Harrod, Chris

    2015-01-01

    Similar environmental driving forces can produce similarity among geographically distant ecosystems. Coastal oceanic upwelling, for example, has been associated with elevated biomass and abundance patterns of certain functional groups, e.g., corticated macroalgae. In the upwelling system of Northern Chile, we examined measures of intertidal macrobenthic composition, structure and trophic ecology across eighteen shores varying in their proximity to two coastal upwelling centres, in a hierarchical sampling design (spatial scales of >1 and >10 km). The influence of coastal upwelling on intertidal communities was confirmed by the stable isotope values (δ13C and δ15N) of consumers, including a dominant suspension feeder, grazers, and their putative resources of POM, epilithic biofilm, and macroalgae. We highlight the utility of muscle δ15N from the suspension feeding mussel, Perumytilus purpuratus, as a proxy for upwelling, supported by satellite data and previous studies. Where possible, we used corrections for broader-scale trends, spatial autocorrelation, ontogenetic dietary shifts and spatial baseline isotopic variation prior to analysis. Our results showed macroalgal assemblage composition, and benthic consumer assemblage structure, varied significantly with the intertidal influence of coastal upwelling, especially contrasting bays and coastal headlands. Coastal topography also separated differences in consumer resource use. This suggested that coastal upwelling, itself driven by coastline topography, influences intertidal communities by advecting nearshore phytoplankton populations offshore and cooling coastal water temperatures. We recommend the isotopic values of benthic organisms, specifically long-lived suspension feeders, as in situ alternatives to offshore measurements of upwelling influence. PMID:26214806

  6. Avian assemblages in the lower Missouri river floodplain

    USGS Publications Warehouse

    Thogmartin, W.E.; Gallagher, M.; Young, N.; Rohweder, J.J.; Durbian, F.; Knutson, M.G.

    2009-01-01

    Floodplain habitat provides important migration and breeding habitat for birds in the midwestern United States. However, few studies have examined how the avian assemblage changes with different stages of floodplain forest succession in the midwestern United States. In spring and summer from 2002 to 2004, we conducted 839 point counts in wet prairie/forbs fields, 547 point counts in early successional forests, and 434 point counts in mature forests to describe the migrating and breeding bird assemblage in the lower Missouri River floodplain. We recorded 131, 121, and 141 species in the three respective habitats, a number higher than most locations in the midwestern United States and comprising > 15% of all avian species in North America. Avian species diversity generally increased from west to east along the river, differed among land cover classes, but overlapped between seasons (migration and breeding) and years. Wet prairies were particularly important for conservation as there were 20 species of high conservation concern observed, including Dickcissels (Spiza americana). Important species for monitoring biotic integrity included the Northern Harrier (Circus cyaneus) and Bobolink (Dolichonyx oryzivorus) in wet prairie, Bell's Vireo (Vireo bellii) in early successional forest, and Northern Parula (Parula americana) and Prothonotary Warbler (Protonotaria citrea) in mature forest. ?? 2009, The Society of Wetland Scientists.

  7. Sampling effort affects multivariate comparisons of stream assemblages

    USGS Publications Warehouse

    Cao, Y.; Larsen, D.P.; Hughes, R.M.; Angermeier, P.L.; Patton, T.M.

    2002-01-01

    Multivariate analyses are used widely for determining patterns of assemblage structure, inferring species-environment relationships and assessing human impacts on ecosystems. The estimation of ecological patterns often depends on sampling effort, so the degree to which sampling effort affects the outcome of multivariate analyses is a concern. We examined the effect of sampling effort on site and group separation, which was measured using a mean similarity method. Two similarity measures, the Jaccard Coefficient and Bray-Curtis Index were investigated with 1 benthic macroinvertebrate and 2 fish data sets. Site separation was significantly improved with increased sampling effort because the similarity between replicate samples of a site increased more rapidly than between sites. Similarly, the faster increase in similarity between sites of the same group than between sites of different groups caused clearer separation between groups. The strength of site and group separation completely stabilized only when the mean similarity between replicates reached 1. These results are applicable to commonly used multivariate techniques such as cluster analysis and ordination because these multivariate techniques start with a similarity matrix. Completely stable outcomes of multivariate analyses are not feasible. Instead, we suggest 2 criteria for estimating the stability of multivariate analyses of assemblage data: 1) mean within-site similarity across all sites compared, indicating sample representativeness, and 2) the SD of within-site similarity across sites, measuring sample comparability.

  8. Assemblages of saproxylic beetles on large downed trunks of oak.

    PubMed

    Milberg, Per; Bergman, Karl-Olof; Sancak, Kerem; Jansson, Nicklas

    2016-03-01

    Old living oaks (Quercus robur) are known as a very species-rich habitat for saproxylic beetles, but it is less clear to what extent such veteran trees differ from an even rarer feature: downed trunks of large oaks. In this study, we set out to sample this habitat, using window traps, with two aims: (1) to describe the variation of assemblages among downed trunks of different type and (2) to compare beetles on downed oaks with data from veteran standing trees. The results showed that trunk volume and sun exposure better explained assemblages as well as species numbers on downed trunks than did decay stage. Furthermore, species classified as facultative saproxylic species showed weak or no differentiation among downed trunks. Species with different feeding habits showed no apparent differentiation among downed trunks. Furthermore, species composition on dead, downed oak trunks differed sharply from that of living, veteran oaks. Wood or bark feeders were more common on veterans than downed trunks, but there was no difference for those species feeding on fungi or those feeding on insects and their remains. In conclusion, for a successful conservation of the saproxylic beetle fauna it is important to keep downed oak trunks, and particularly large ones, in forest and pastures as they constitute a saproxylic habitat that differs from that of living trees. PMID:26904184

  9. Benthic foraminiferal assemblages in Osaka Bay, southwestern Japan: Faunal changes over the last 50 years

    USGS Publications Warehouse

    Tsujimoto, Akira; Nomura, Ritsuo; Yasuhara, Moriaki; Yoshikawa, Shusaku

    2006-01-01

    Live benthic foraminiferal assemblages from surface sediment in Osaka Bay collected in 1999 were analyzed to characterize the distribution of the modern foraminiferal assemblages. Foraminiferal assemblages were compared with those of previous studies to document environmental changes in Osaka Bay over the past 50 years. Sixty-one species of foraminifera belonging to 37 genera were recognized from the 1999 surface sediment samples. An agglutinated assemblage containing Trochammina hadai and Eggerella advena is dominant in the inner part of the bay and is related to eutrophication. The foraminiferal assemblage in areas deeper than about 20 m is composed of Eggerella advena, Ammonia beccarii forma A, and Pseudorotalia gaimardii. This assemblage may be influenced by the large clockwise Okinose Circulation Current which extends throughout the western bay. Foraminiferal assemblages in Osaka Bay have changed dramatically during the last 50 years. The Trochammina hadai-Eggerella advena assemblage became established in the inner part of the bay, reflecting eutrophication that progressed from the 1960s through the 1970s. This assemblage became dominant in 1983, and typically dominated the inner part of the bay. From 1983 to 1999, however, the abundance of taxa belonging to this assemblage decreased greatly following implementation of 1973 Osaka City bylaws that restricted wastewater discharge. Changes in benthic assemblages such as the decrease of Ammonia beccarii forma A and increase of Eggerella advena have occurred in response to decreased incidence of red tides, and floral change in the species that cause these tides. The results of this study demonstrate that the abundance and distribution of benthic foraminifers in Osaka Bay are intimately related to environmental changes related to the urbanization of coastal areas. ?? by the Palaeontological Society of Japan.

  10. Selective excavation of human carious dentin using the nanosecond pulsed laser in 5.8-μm wavelength range

    NASA Astrophysics Data System (ADS)

    Kita, Tetsuya; Ishii, Katsunori; Yoshikawa, Kazushi; Yasuo, Kenzo; Yamamoto, Kazuyo; Awazu, Kunio

    Less-invasive treatment of caries has been needed in laser dentistry. Based on the absorption property of dentin substrates, 6 μm wavelength range shows specific absorptions and promising characteristics for the excavation. In our previous study, 5.8 μm wavelength range was found to be effective for selective excavation of carious dentin and restoration treatment using composite resin from the irradiation experiment with bovine sound and demineralized dentin. In this study, the availability of 5.8 μm wavelength range for selective excavation of human carious dentin was investigated for clinical application. A mid-infrared tunable nanosecond pulsed laser by difference-frequency generation was used for revealing the ablation property of human carious dentin. Irradiation experiments indicated that the wavelength of 5.85 μm and the average power density of 30 W/cm2 realized the selective excavation of human carious dentin, but ablation property was different with respect to each sample because of the different caries progression. In conclusion, 5.8 μm wavelength range was found to be effective for selective excavation of human carious dentin.

  11. Anisotropy of electrical conductivity of the excavation damaged zone in the Mont Terri Underground Rock Laboratory

    NASA Astrophysics Data System (ADS)

    Nicollin, Florence; Gibert, Dominique; Lesparre, Nolwenn; Nussbaum, Christophe

    2010-04-01

    Electrical resistivity measurements were performed to characterize the anisotropy of electrical resistivity of the excavation damaged zone (EDZ) at the end-face of a gallery in the Opalinus clay of the Mont Terri Underground Rock Laboratory (URL). The data were acquired with a combination of square arrays in 18 zones on the gallery's face and in two series of four boreholes perpendicular to the face. Each data set is independently inverted using simulated annealing to recover the resistivity tensor. Both the stability and the non-uniqueness of the inverse problem are discussed with synthetic examples. The inversion of the data shows that the face is split in two domains separated by a tectonic fracture, with different resistivity values but with a common orientation. The direction of the maximum resistivity is found perpendicular to the bedding plane, and the direction of minimum resistivity is contained in the face's plane. These results show that the geo-electrical structure of the EDZ is controlled by a combination of effects due to tectonics, stratigraphy, and recent fracturing produced by the excavation of the gallery.

  12. Comparative clinical evaluation of the efficacy of a new method for caries diagnosis and excavation

    PubMed Central

    Peskersoy, Cem; Turkun, Murat; Onal, Banu

    2015-01-01

    Aim: The purpose of this study is to compare the efficiency of fluorescence-aided caries excavation (FACE) to remove carious dentin primary teeth with that of conventional methods. Methods and Materials: After caries excavation was carried out, dentin surfaces were conventionally inspected using visual tactile criteria and 415 cavities which were classified as caries-free, re-inspected with Face-Light and caries detector dye (CDD) methods. Orange-red fluorescing areas classified as carious dentin, as well as stained carious dentin. All the data were recorded according to localization of the caries and determination efficiency of the methods. X2 test was used to compare the mean values of both Face-Light and dye applications, while Wilcoxon test performed to evaluate the effectiveness for each diagnostic method. Results: A total of 273 patients with 415 Class II (OM/OD) cavities (1.65 ± 0.52 teeth per patient) with carious lesions in molar and premolar teeth, were examined. Out of 415 teeth, in 149 teeth (35.9%) no caries findings had been illustrated. While FACE detected remaining carious or partially removed areas in 237 teeth (57.2%), CDD stained only 29 teeth by itself (P < 0.05). Conclusion: In conclusion, FACE has a higher detectability compared to visual inspection and caries detector dye in diagnosis and removal of carious dentin. PMID:26430298

  13. The Tissint Martian meteorite as evidence for the largest impact excavation.

    PubMed

    Baziotis, Ioannis P; Liu, Yang; DeCarli, Paul S; Melosh, H Jay; McSween, Harry Y; Bodnar, Robert J; Taylor, Lawrence A

    2013-01-01

    High-pressure minerals in meteorites provide clues for the impact processes that excavated, launched and delivered these samples to Earth. Most Martian meteorites are suggested to have been excavated from 3 to 7 km diameter impact craters. Here we show that the Tissint meteorite, a 2011 meteorite fall, contains virtually all the high-pressure phases (seven minerals and two mineral glasses) that have been reported in isolated occurrences in other Martian meteorites. Particularly, one ringwoodite (75 × 140 μm(2)) represents the largest grain observed in all Martian samples. Collectively, the ubiquitous high-pressure minerals of unusually large sizes in Tissint indicate that shock metamorphism was widely dispersed in this sample (~25 GPa and ~2,000 °C). Using the size and growth kinetics of the ringwoodite grains, we infer an initial impact crater with ~90 km diameter, with a factor of 2 uncertainty. These energetic conditions imply alteration of any possible low-T minerals in Tissint. PMID:23360995

  14. Effect of tunnel excavation on source and mixing of groundwater in a coastal granitoidic fracture network.

    PubMed

    Mathurin, Frédéric A; Åström, Mats E; Laaksoharju, Marcus; Kalinowski, Birgitta E; Tullborg, Eva-Lena

    2012-12-01

    The aim of this study was to assess how the excavation of the Äspö Hard Rock Laboratory tunnel has impacted on sources and mixing of groundwater in fractured crystalline (granitoidic) bedrock. The tunnel is 3600 m long and extends to a depth of 460 m at a coastal site in Boreal Europe. The study builds on a unique data set consisting of 1117 observations on chloride and δ(18)O of groundwater collected from a total of 356 packed-off fractures between 1987 and 2011. On the basis of the values of these two variables in selected source waters, a classification system was developed to relate the groundwater observations to source and postinfiltration mixing phenomena. The results show that the groundwater has multiple sources and a complex history of transport and mixing, and is composed of at least glacial water, marine water, recent meteoric water, and an old saline water. The tunnel excavation has had a large impact on flow, sources, and mixing of the groundwater. Important phenomena include upflow of deep-lying saline water, extensive intrusion of current Baltic Sea water, and substantial temporal variability of chloride and δ(18)O in many fractures. PMID:23088667

  15. Brittle Rock Modeling Approach and its Validation Using Excavation-Induced Micro-Seismicity

    NASA Astrophysics Data System (ADS)

    Ma, Chun-Chi; Li, Tian-Bin; Xing, Hui-Lin; Zhang, Hang; Wang, Min-Jie; Liu, Tian-Yi; Chen, Guo-Qing; Chen, Zi-Quan

    2016-08-01

    With improvements to the bonded-particle model, a custom indicator of crack intensity is introduced to grade rock fractures accurately. Brittle fracturing of rock mass is studied using the bonded-particle model; here, "brittle" refers to the process where more energy is released towards making particles collide and disperse, and hence results in the quick emergence of "chain cracks". Certain principles concerning how to construct brittle rock are then proposed. Furthermore, a modeling approach for brittle rocks based on the adaptive continuum/discontinuum (AC/DC) method is proposed to aid the construction of large-scale models of tunnel excavations. To connect with actual tunneling conditions, fundamental mechanical properties, the mechanism for brittle fracturing, the joint distribution, and the initial stress field are considered in the modeling approach. Results from micro-seismic monitoring of a tunnel excavation confirmed the suitability of this modeling approach to simulate crack behavior, and results show that simulated cracking exhibit similar trends (evolution, location, and intensity) with micro-seismic cracking.

  16. Results of Hazardous and Mixed Waste Excavation from the Chemical Waste Landfill

    SciTech Connect

    Young, S. G.; Schofield, D. P.; Kwiecinski, D.; Edgmon, C. L.; Methvin, R.

    2002-02-27

    This paper describes the results of the excavation of a 1.9-acre hazardous and mixed waste landfill operated for 23 years at Sandia National Laboratories, Albuquerque, New Mexico. Excavation of the landfill was completed in 2 1/2 years without a single serious accident or injury. Approximately 50,000 cubic yards of soil contaminated with volatile and semi-volatile organics, metals, polychlorinated biphenyl compounds, and radioactive constituents was removed. In addition, over 400 cubic yards of buried debris was removed, including bulk debris, unknown chemicals, compressed gas cylinders, thermal and chemical batteries, explosive and ordnance debris, pyrophoric materials and biohazardous waste. Removal of these wastes included negotiation of multiple regulations and guidances encompassed in the Resource Conservation and Recovery Act (RCRA), the Toxic Substances Control Act (TSCA), and risk assessment methodology. RCRA concepts that were addressed include the area of contamination, permit modification, emergency treatment provision, and listed waste designation. These regulatory decisions enabled the project to overcome logistical and programmatic needs such as increased operational area, the ability to implement process improvements while maintaining a record of decisions and approvals.

  17. Reactive-power compensation of coal mining excavators by using a new-generation STATCOM

    SciTech Connect

    Bilgin, H.F.; Ermis, M.; Kose, K.N.; Cadirci, I.; Acik, A.; Demirci, T.; Terciyanli, A.; Kocak, C.; Yorukoglu, M.

    2007-01-15

    This paper deals with the development and implementation of a current-source-converter-based static synchronous compensator (CSC-STATCOM) applied to the volt-ampere-reactive (VAR) compensation problem of coal mining excavators. It is composed of a +/- 750-kVAR full-bridge CSC with selective harmonic elimination, a low-pass input filter tuned to 200 Hz, and a Delta/Y-connected coupling transformer for connection to medium-voltage load bus. Each power semiconductor switch is composed of an asymmetrical integrated gate commutated thyristor (IGCT) connected in series with a reverse-blocking diode and switched at 500 Hz to eliminate 5th, 7th, 11th, and 13th current harmonics produced by the CSC. Operating principles, power stage, design of dc link, and input filter are also described in this paper. It has been verified by field tests that the developed STATCOM follows rapid fluctuations in nearly symmetrical lagging and leading VAR consumption of electric excavators, resulting in nearly unity power factor on monthly basis, and the harmonic current spectra in the lines of CSC-STATCOM at the point of common coupling comply with the IEEE Standard 519-1992.

  18. Mechanical behavior and shape optimization of lining structure for subsea tunnel excavated in weathered slot

    NASA Astrophysics Data System (ADS)

    Li, Peng-fei; Zhou, Xiao-jun

    2015-12-01

    Subsea tunnel lining structures should be designed to sustain the loads transmitted from surrounding ground and groundwater during excavation. Extremely high pore-water pressure reduces the effective strength of the country rock that surrounds a tunnel, thereby lowering the arching effect and stratum stability of the structure. In this paper, the mechanical behavior and shape optimization of the lining structure for the Xiang'an tunnel excavated in weathered slots are examined. Eight cross sections with different geometric parameters are adopted to study the mechanical behavior and shape optimization of the lining structure. The hyperstatic reaction method is used through finite element analysis software ANSYS. The mechanical behavior of the lining structure is evidently affected by the geometric parameters of crosssectional shape. The minimum safety factor of the lining structure elements is set to be the objective function. The efficient tunnel shape to maximize the minimum safety factor is identified. The minimum safety factor increases significantly after optimization. The optimized cross section significantly improves the mechanical characteristics of the lining structure and effectively reduces its deformation. Force analyses of optimization process and program are conducted parametrically so that the method can be applied to the optimization design of other similar structures. The results obtained from this study enhance our understanding of the mechanical behavior of the lining structure for subsea tunnels. These results are also beneficial to the optimal design of lining structures in general.

  19. Excavation on the Moon: Regolith Collection for Oxygen Production and Outpost Site Preparation

    NASA Technical Reports Server (NTRS)

    Caruso, John J.; Spina, Dan C.; Greer, Lawrence C.; John, Wentworth T.; Michele, Clem; Krasowski, Mike J.; Prokop, Norman F.

    2008-01-01

    The development of a robust regolith moving system for lunar and planetary processing and construction is critical to the NASA mission to the Moon and Mars. Oxygen production may require up to 200 metric tons of regolith collection per year; outpost site development may require several times this amount. This paper describes progress in the small vehicle implement development and small excavation system development. Cratos was developed as a platform for the ISRU project to evaluate the performance characteristics of a low center of gravity, small (0.75m x 0.75m x 0.3m), low-power, tracked vehicle performing excavation, load, haul, and dump operations required for lunar ISRU. It was tested on loose sand in a facility capable of producing level and inclined surfaces, and demonstrated the capability to pick up, carry, and dump sand, allowing it to accomplish the delivery of material to a site. Cratos has demonstrated the capability to pick up and deliver simulant to a bury an inflatable habitat, to supply an oxygen production plant, and to build a ramp.

  20. A Basic Robotic Excavator (the Glenn Digger): Description, Design, and Initial Operation

    NASA Technical Reports Server (NTRS)

    Bauman, Steve; Newman, Paul; Izadnegahdar, Alain; Johnson, Kyle; Abel, Phillip

    2016-01-01

    This paper describes the design, commercial part selections, fabrication, assembly, installation, and initial operation of a two degree of freedom robotic excavator. Colloquially referred to as "the NASA Glenn Digger," it was designed specifically to be mounted onto, and to operate with, the then newly developed Centaur 2 robotic mobility base. The excavator, when mounted to Centaur 2, is designed to scoop loose regolith from the terrain, raise its loaded bucket up and dump the load into a hopper of at least a 1-m-height. The hopper represents the input to a machine that would process the raw material, such as to produce oxygen from lunar regolith as would be required for long-term lunar habitation. This equipment debuted at the annual Research and Technology Studies ("Desert RATS", Ref. 1) event held north of Flagstaff, Arizona, in September of 2010, when the Digger was successfully joined to Centaur 2 and the shoveling articulation was demonstrated. During 2011, the hardware was modified for added strength, strain gauges were added to measure loads, and the controls were improved in preparation for the 2011 Desert RATS event, where additional "field operations" experience was gained.

  1. Middle Pleistocene ostracod assemblages from Lake Trasimeno, Perugia (Italy)

    NASA Astrophysics Data System (ADS)

    Marchegiano, Marta; Gliozzi, Elsa; Buratti, Nicoletta; Ariztegui, Daniel; Cirilli, Simonetta

    2014-05-01

    Lake Trasimeno is a meso-eutrophic, shallow (<6 m deep) and large lake (~120km2) located in central Italy, at 259 m above sea level. A preliminary age model based on pollen data for a core retrieved along the present southern shore of the lake (north of the Panicarola town) suggests that the record may be as old as Middle Pleistocene. An ongoing multidisciplinary study of a 175 m long sedimentary core includes magnetic properties, sedimentary microfacies, paleontology, palynology and bulk elemental geochemistry. This contribution focus on the paleoenvironmental reconstruction of the topmost 30 m of the core using ostracods. A total of 245 samples have been taken at a 13 cm sampling interval. On the whole, 13 species referable to 10 genera were collected (Ilyocypris gibba, Candona neglecta, Candona angulata, Cypridopsis vidua, Heterocypris salina, Limnocythere sp.1, Limnocythere stationis, Darwinula stevensoni, Cyprideis sp., Leptocythere spp., Fabaeformiscandona fabaeformis, Cyclocypris ovum). Abrupt changes in the abundance of the assemblages were found along the studied core alternating sections with very abundant ostracod remains with others with scant (or even null) individuals. Moreover, the changes observed in the composition of the ostracod assemblages are interpreted as recording environmental variations. In particular, two intervals are significant for the paleoenvironmental reconstruction of this sedimentary succession: 1) the section from 25.60 m to 23.50 m is characterized by a rich ostracod fauna (dominated by Cyprideis sp., Candona angulata and Leptocythere spp.). These assemblages possibly indicate an increase in salinity or alkalinity of the water body; 2) the interval from 21.05 m to 17.60 m contains Ilyocypris gibba, Candona neglecta, Cypridopsis vidua, Heterocypris salina, Limnocythere sp. 1, Limnocythere stationis and Darwinula stevensoni. Limnocythere stationis is a central European species, until now in Italy only described in the Holocene of

  2. Isotopic characteristics of canopies in simulated leaf assemblages

    NASA Astrophysics Data System (ADS)

    Graham, Heather V.; Patzkowsky, Mark E.; Wing, Scott L.; Parker, Geoffrey G.; Fogel, Marilyn L.; Freeman, Katherine H.

    2014-11-01

    The geologic history of closed-canopy forests is of great interest to paleoecologists and paleoclimatologists alike. Closed canopies have pronounced effects on local, continental and global rainfall and temperature patterns. Although evidence for canopy closure is difficult to reconstruct from the fossil record, the characteristic isotope gradients of the "canopy effect" could be preserved in leaves and proxy biomarkers. To assess this, we employed new carbon isotopic data for leaves collected in diverse light environments within a deciduous, temperate forest (Maryland, USA) and for leaves from a perennially closed canopy, moist tropical forest (Bosque Protector San Lorenzo, Panamá). In the tropical forest, leaf carbon isotope values range 10‰, with higher δ13Cleaf values occurring both in upper reaches of the canopy, and with higher light exposure and lower humidity. Leaf fractionation (Δleaf) varied negatively with height and light and positively with humidity. Vertical 13C enrichment in leaves largely reflects changes in Δleaf, and does not trend with δ13C of CO2 within the canopy. At the site in Maryland, leaves express a more modest δ13C range (∼6‰), with a clear trend that follows both light and leaf height. Using a model we simulate leaf assemblage isotope patterns from canopy data binned by elevation. The re-sampling (bootstrap) model determined both the mean and range of carbon isotope values for simulated leaf assemblages ranging in size from 10 to over 1000 leaves. For the tropical forest data, the canopy's isotope range is captured with 50 or more randomly sampled leaves. Thus, with a sufficient number of fossil leaves it is possible to distinguish isotopic gradients in an ancient closed canopy forest from those in an open forest. For very large leaf assemblages, mean isotopic values approximate the δ13C of carbon contributed by leaves to soil and are similar to observed δ13Clitter values at forested sites within Panamá, including the

  3. High phylogenetic diversity is preserved in species-poor high-elevation temperate moth assemblages

    PubMed Central

    Zou, Yi; Sang, Weiguo; Hausmann, Axel; Axmacher, Jan Christoph

    2016-01-01

    Understanding the diversity and composition of species assemblages and identifying underlying biotic and abiotic determinants represent great ecological challenges. Addressing some of these issues, we investigated the α-diversity and phylogenetic composition of species-rich geometrid moth (Lepidoptera: Geometridae) assemblages in the mature temperate forest on Changbai Mountain. A total of 9285 geometrid moths representing 131 species were collected, with many species displaying wide elevational distribution ranges. Moth α-diversity decreased monotonously, while the standardized effect size of mean pairwise phylogenetic distances (MPD) and phylogenetic diversity (PD) increased significantly with increasing elevation. At high elevations, the insect assemblages consisted largely of habitat generalists that were individually more phylogenetically distinct from co-occurring species than species in assemblages at lower altitudes. This could hint at higher speciation rates in more favourable low-elevation environments generating a species-rich geometrid assemblage, while exclusion of phylogenetically closely related species becomes increasingly important in shaping moth assemblages at higher elevations. Overall, it appears likely that high-elevation temperate moth assemblages are strongly resilient to environmental change, and that they contain a much larger proportion of the genetic diversity encountered at low-elevation assemblages in comparison to tropical geometrid communities. PMID:26979402

  4. Lunch Time at the Child Care Centre: Neoliberal Assemblages in Early Childhood Education

    ERIC Educational Resources Information Center

    Nxumalo, Fikile; Pacini-Ketchabaw, Veronica; Rowan, Mary Caroline

    2011-01-01

    In this article we interrogate neoliberal assemblages within the context of eating and feeding practices in early childhood education. We consider how neoliberal assemblages are enacted and created through multiple linkages between micro and macro regulations and policies, and everyday food routines. We attend to the embodied intensities, desires…

  5. Social Equity and the Assemblage of Values in Australian Higher Education

    ERIC Educational Resources Information Center

    Rizvi, Fazal; Lingard, Bob

    2011-01-01

    The paper argues that the policy concept of social equity cannot be adequately understood in a generalised abstract manner, but is better viewed as an assemblage that brings together a number of contrasting, and sometimes competing, values. Our use of assemblage is somewhat eclectic and is designed to underscore the performative character of…

  6. Surface water connectivity drives richness and composition of Arctic lake fish assemblages

    USGS Publications Warehouse

    Laske, Sarah M.; Haynes, Trevor B.; Rosenberger, Amanda E.; Koch, Joshua C.; Wipfli, Mark S.; Whitman, Matthew; Zimmerman, Christian E.

    2016-01-01

    This work provides useful baseline information on the processes that drive the relations between patch connectivity and fish species richness and assemblage composition. The environmental processes that organise fish assemblages in Arctic lakes are likely to change in a warming climate.

  7. Lions as Bone Accumulators? Paleontological and Ecological Implications of a Modern Bone Assemblage from Olduvai Gorge.

    PubMed

    Arriaza, Mari Carmen; Domínguez-Rodrigo, Manuel; Yravedra, José; Baquedano, Enrique

    2016-01-01

    Analytic models have been developed to reconstruct early hominin behaviour, especially their subsistence patterns, revealed mainly through taphonomic analyses of archaeofaunal assemblages. Taphonomic research is used to discern which agents (carnivores, humans or both) generate the bone assemblages recovered at archaeological sites. Taphonomic frameworks developed during the last decades show that the only large-sized carnivores in African biomes able to create bone assemblages are leopards and hyenas. A carnivore-made bone assemblage located in the short-grassland ecological unit of the Serengeti (within Olduvai Gorge) was studied. Taphonomic analyses of this assemblage including skeletal part representation, bone density, breakage patterns and anatomical distribution of tooth marks, along with an ecological approach to the prey selection made by large carnivores of the Serengeti, were carried out. The results show that this bone assemblage may be the first lion-accumulated assemblage documented, although other carnivores (namely spotted hyenas) may have also intervened through postdepositional ravaging. This first faunal assemblage potentially created by lions constitutes a new framework for neotaphonomic studies. Since lions may accumulate carcasses under exceptional circumstances, such as those documented at the site reported here, this finding may have important consequences for interpretations of early archaeological and paleontological sites, which provide key information about human evolution. PMID:27144649

  8. High phylogenetic diversity is preserved in species-poor high-elevation temperate moth assemblages.

    PubMed

    Zou, Yi; Sang, Weiguo; Hausmann, Axel; Axmacher, Jan Christoph

    2016-01-01

    Understanding the diversity and composition of species assemblages and identifying underlying biotic and abiotic determinants represent great ecological challenges. Addressing some of these issues, we investigated the α-diversity and phylogenetic composition of species-rich geometrid moth (Lepidoptera: Geometridae) assemblages in the mature temperate forest on Changbai Mountain. A total of 9285 geometrid moths representing 131 species were collected, with many species displaying wide elevational distribution ranges. Moth α-diversity decreased monotonously, while the standardized effect size of mean pairwise phylogenetic distances (MPD) and phylogenetic diversity (PD) increased significantly with increasing elevation. At high elevations, the insect assemblages consisted largely of habitat generalists that were individually more phylogenetically distinct from co-occurring species than species in assemblages at lower altitudes. This could hint at higher speciation rates in more favourable low-elevation environments generating a species-rich geometrid assemblage, while exclusion of phylogenetically closely related species becomes increasingly important in shaping moth assemblages at higher elevations. Overall, it appears likely that high-elevation temperate moth assemblages are strongly resilient to environmental change, and that they contain a much larger proportion of the genetic diversity encountered at low-elevation assemblages in comparison to tropical geometrid communities. PMID:26979402

  9. BIRD SPECIES ASSEMBLAGES AS INDICATORS OF BIOLOGICAL INTEGRITY IN GREAT BASIN RANGELAND

    EPA Science Inventory

    The study evaluates the potential for bird species assemblages to serve as indicators of biological integrity of rangelands in the Great Basin in much the same way that fish and invertebrate assemblages have been used as indicators in aquatic environments. Our approach was to ide...

  10. Lions as Bone Accumulators? Paleontological and Ecological Implications of a Modern Bone Assemblage from Olduvai Gorge

    PubMed Central

    Arriaza, Mari Carmen; Domínguez-Rodrigo, Manuel; Yravedra, José; Baquedano, Enrique

    2016-01-01

    Analytic models have been developed to reconstruct early hominin behaviour, especially their subsistence patterns, revealed mainly through taphonomic analyses of archaeofaunal assemblages. Taphonomic research is used to discern which agents (carnivores, humans or both) generate the bone assemblages recovered at archaeological sites. Taphonomic frameworks developed during the last decades show that the only large-sized carnivores in African biomes able to create bone assemblages are leopards and hyenas. A carnivore-made bone assemblage located in the short-grassland ecological unit of the Serengeti (within Olduvai Gorge) was studied. Taphonomic analyses of this assemblage including skeletal part representation, bone density, breakage patterns and anatomical distribution of tooth marks, along with an ecological approach to the prey selection made by large carnivores of the Serengeti, were carried out. The results show that this bone assemblage may be the first lion-accumulated assemblage documented, although other carnivores (namely spotted hyenas) may have also intervened through postdepositional ravaging. This first faunal assemblage potentially created by lions constitutes a new framework for neotaphonomic studies. Since lions may accumulate carcasses under exceptional circumstances, such as those documented at the site reported here, this finding may have important consequences for interpretations of early archaeological and paleontological sites, which provide key information about human evolution. PMID:27144649

  11. Treatment of deep caries lesions in adults: randomized clinical trials comparing stepwise vs. direct complete excavation, and direct pulp capping vs. partial pulpotomy.

    PubMed

    Bjørndal, Lars; Reit, Claes; Bruun, Gitte; Markvart, Merete; Kjaeldgaard, Marianne; Näsman, Peggy; Thordrup, Marianne; Dige, Irene; Nyvad, Bente; Fransson, Helena; Lager, Anders; Ericson, Dan; Petersson, Kerstin; Olsson, Jadranka; Santimano, Eva M; Wennström, Anette; Winkel, Per; Gluud, Christian

    2010-06-01

    Less invasive excavation methods have been suggested for deep caries lesions. We tested the effects of stepwise vs. direct complete excavation, 1 yr after the procedure had been carried out, in 314 adults (from six centres) who had received treatment of a tooth with deep caries. The teeth had caries lesions involving 75% or more of the dentin and were centrally randomized to stepwise or direct complete excavation. Stepwise excavation resulted in fewer pulp exposures compared with direct complete excavation [difference: 11.4%, 95% confidence interval (CI) (1.2; 21.3)]. At 1 yr of follow-up, there was a statistically significantly higher success rate with stepwise excavation, with success being defined as an unexposed pulp with sustained pulp vitality without apical radiolucency [difference: 11.7%, 95% CI (0.5; 22.5)]. In a subsequent nested trial, 58 patients with exposed pulps were randomized to direct capping or partial pulpotomy. We found no significant difference in pulp vitality without apical radiolucency between the two capping procedures after more than 1 yr [31.8% and 34.5%; difference: 2.7%, 95% CI (-22.7; 26.6)]. In conclusion, stepwise excavation decreases the risk of pulp exposure compared with direct complete excavation. In view of the poor prognosis of vital pulp treatment, a stepwise excavation approach for managing deep caries lesions is recommended. PMID:20572864

  12. New and extraordinary Early Cambrian sponge spicule assemblage from China

    NASA Astrophysics Data System (ADS)

    Zhang, Xi-Guang; Pratt, Brian R.

    1994-01-01

    The fossil record of siliceous sponges, compared with that of other skeleton- secreting Metazoa, is poorly known, based as it is on disarticulated spicules and sporadically preserved body fossils. Abundant spicules recovered from Lower Cambrian strata in Shaanxi, China, essentially double the known morphological diversity of siliceous sponges for that interval of geologic time. These fossils, along with a comparable coeval fauna from South Australia, have a remarkably modern aspect, thereby demonstrating that the principal siliceous sponge groups and styles of body architecture were established quickly in the earliest Phanerozoic as part of the Cambrian "explosion" and that they inhabited a variety of low-energy, relatively deep water settings. The similarity of spicule shape and variation to that of younger assemblages reflects a conservative architecture for the siliceous sponges.

  13. Impacts of multiple stressors during the establishment of fouling assemblages.

    PubMed

    Saloni, Silvia; Crowe, Tasman P

    2015-02-15

    Limited knowledge of the mechanisms through which multiple stressors affect communities and ecosystems limits capacity to predict their effects. Less clear is how stressors impact early colonization of newly available habitats due to scarcity of studies. The present study tested whether copper and freshwater input affect colonization of hard substrata independently or interactively and assessed differences in community respiration and total biomass among early stage assemblages which developed under different regimes of copper and freshwater input. While copper influenced effectively the colonization of individual species, freshwater effect was weak or null. Apart from a significant effect on total community composition, the interactive effect between stressors was weak and mainly driven by antagonistic interactions between copper and water flow. Total biomass and respiration of the community studied were not affected by stressors. These findings contradict the expectation that changes in community structure are likely to cause changes in functioning. PMID:25563931

  14. Sequence of mineral assemblages in differentiated granitic pegmatites.

    USGS Publications Warehouse

    Norton, J.J.

    1983-01-01

    The sequence of mineral assemblages in internally zoned granitic pegmatites recognized by Cameron et al. (1949) is modified here to account for an observed vertical component, especially in feldspar compositions, in addition to the recognized outer contact-to-inner core differentiation process, and the importance of primary lithium minerals other than spodumene, such as petalite. The zonal patterns of 11 well-known granitic pegmatites are consistent with this revised sequence, with additional explanations for the repeated monomineralic zones of quartz or pollucite, etc. The crystallization history of zoned pegmatites is described in general terms, beginning with the magmatic crystallization which produces the outer zones. Aqueous fluid is exsolved continuously from the magma as relatively anhydrous phases precipitate, and plays an important role in the formation of the inner zones; its evolution is thought to be a major cause of pegmatite differentiation.-J.E.S.

  15. Long-term functional changes in an estuarine fish assemblage.

    PubMed

    Baptista, J; Martinho, F; Nyitrai, D; Pardal, M A; Dolbeth, M

    2015-08-15

    The functional diversity of the fish assemblages of the Mondego estuary was studied for a discontinuous 30-year period (1988-2012). During this time, hydrological changes occurred due to man-induced alterations and weather extremes. These changes led to alterations in the structure and function of the fish community. Species richness and functional richness decreased over time and the fish community started to explore new micro-habitats and food resources. Before severe hydrological changes, the community was dominated by pelagic, detritivorous and species with wider salinity ranges. After, the community became dominated by demersal, benthic, piscivorous and marine species. During a drought, omnivorous became increasingly important, reflecting greater possibilities of using available feeding resources. We have also found an increase in sub-tropical species throughout the years, which might be related to gradual temperature increases at a global scale. This study also confirmed estuaries as extremely important for restocking several commercial species. PMID:26093816

  16. Description of viral assemblages associated with the Gorgonia ventalina holobiont

    NASA Astrophysics Data System (ADS)

    Hewson, I.; Brown, J. M.; Burge, C. A.; Couch, C. S.; LaBarre, B. A.; Mouchka, M. E.; Naito, M.; Harvell, C. D.

    2012-06-01

    The diversity and function of viruses in coral holobionts has only recently received attention. The non-reef building gorgonian octocoral, Gorgonia ventalina, is a major constituent of Caribbean reefs. We investigated viral communities associated with G. ventalina tissues to understand their role in gorgonian ecology. Pyrosequencing was used to prepare a total of 514,632 sequence reads of DNA- and RNA-based mixed-community viral genomes (metaviromes). RNA viral assemblages were comprised of primarily unidentifiable reads, with most matching host transcripts and other RNA metaviromes. DNA metaviromes were similar between healthy and diseased tissues and comprised of contiguous sequences (contigs) that matched primarily metazoan and bacterial proteins. Only ~5% of contigs matched viral proteins that were primarily cyanophage and viruses of Chlorella and Ostreococcus. Our results confirm that DNA and RNA viruses comprise a component of the gorgonian holobiont, suggesting that they may play a role in the ecology of G. ventalina.

  17. Historical photogrammetry: Bird's Paluxy River dinosaur chase sequence digitally reconstructed as it was prior to excavation 70 years ago.

    PubMed

    Falkingham, Peter L; Bates, Karl T; Farlow, James O

    2014-01-01

    It is inevitable that some important specimens will become lost or damaged over time, conservation is therefore of vital importance. The Paluxy River dinosaur tracksite is among the most famous in the world. In 1940, Roland T. Bird described and excavated a portion of the site containing associated theropod and sauropod trackways. This excavated trackway was split up and housed in different institutions, and during the process a portion was lost or destroyed. We applied photogrammetric techniques to photographs taken by Bird over 70 years ago, before the trackway was removed, to digitally reconstruct the site as it was prior to excavation. The 3D digital model offers the opportunity to corroborate maps drawn by R.T. Bird when the tracksite was first described. More broadly, this work demonstrates the exciting potential for digitally recreating palaeontological, geological, or archaeological specimens that have been lost to science, but for which photographic documentation exists. PMID:24695537

  18. Historical Photogrammetry: Bird's Paluxy River Dinosaur Chase Sequence Digitally Reconstructed as It Was prior to Excavation 70 Years Ago

    PubMed Central

    Falkingham, Peter L.; Bates, Karl T.; Farlow, James O.

    2014-01-01

    It is inevitable that some important specimens will become lost or damaged over time, conservation is therefore of vital importance. The Paluxy River dinosaur tracksite is among the most famous in the world. In 1940, Roland T. Bird described and excavated a portion of the site containing associated theropod and sauropod trackways. This excavated trackway was split up and housed in different institutions, and during the process a portion was lost or destroyed. We applied photogrammetric techniques to photographs taken by Bird over 70 years ago, before the trackway was removed, to digitally reconstruct the site as it was prior to excavation. The 3D digital model offers the opportunity to corroborate maps drawn by R.T. Bird when the tracksite was first described. More broadly, this work demonstrates the exciting potential for digitally recreating palaeontological, geological, or archaeological specimens that have been lost to science, but for which photographic documentation exists. PMID:24695537

  19. Seafloor massive sulfide deposits support unique megafaunal assemblages: Implications for seabed mining and conservation.

    PubMed

    Boschen, Rachel E; Rowden, Ashley A; Clark, Malcolm R; Pallentin, Arne; Gardner, Jonathan P A

    2016-04-01

    Mining of seafloor massive sulfides (SMS) is imminent, but the ecology of assemblages at SMS deposits is poorly known. Proposed conservation strategies include protected areas to preserve biodiversity at risk from mining impacts. Determining site suitability requires biological characterisation of the mine site and protected area(s). Video survey of a proposed mine site and protected area off New Zealand revealed unique megafaunal assemblages at the mine site. Significant relationships were identified between assemblage structure and environmental conditions, including hydrothermal features. Unique assemblages occurred at both active and inactive chimneys and are particularly at risk from mining-related impacts. The occurrence of unique assemblages at the mine site suggests that the proposed protected area is insufficient alone and should instead form part of a network. These results provide support for including hydrothermally active and inactive features within networks of protected areas and emphasise the need for quantitative survey data of proposed sites. PMID:26897590

  20. The role of depth in regulating water quality and fish assemblages in oxbow lakes

    USGS Publications Warehouse

    Goetz, Daniel B.; Miranda, Leandro E.; Kroger, Robert; Andrews, Caroline S.

    2015-01-01

    We evaluated water quality and fish assemblages in deep (> 3.0 m; N = 7) and shallow (< 1.5 m; N = 6) floodplain lakes in the intensively cultivated Yazoo River Basin (Mississippi, USA) using indirect gradient multivariate procedures. Shallow lakes displayed wide diel oxygen fluctuations, some reaching hypoxic/anoxic conditions for extended periods of time, high suspended solids, and extreme water temperatures. Conversely, deeper lakes were represented by higher visibility, stable oxygen levels, and cooler water temperatures. Fish assemblages in shallow lakes were dominated by tolerant, small-bodied fishes and those able to breathe atmospheric oxygen. Deeper lakes had a greater representation of predators and other large-bodied fishes. Our evaluation suggests fish assemblages are reflective of oxbow lakes water quality, which is shaped by depth. Understanding the interactions between depth, water quality, and fish assemblages may facilitate development of effective management plans for improving conditions necessary to sustain diverse fish assemblages in agriculturally dominated basins.

  1. Spatial segregation in eastern North Pacific skate assemblages.

    PubMed

    Bizzarro, Joseph J; Broms, Kristin M; Logsdon, Miles G; Ebert, David A; Yoklavich, Mary M; Kuhnz, Linda A; Summers, Adam P

    2014-01-01

    Skates (Rajiformes: Rajoidei) are common mesopredators in marine benthic communities. The spatial associations of individual species and the structure of assemblages are of considerable importance for effective monitoring and management of exploited skate populations. This study investigated the spatial associations of eastern North Pacific (ENP) skates in continental shelf and upper continental slope waters of two regions: central California and the western Gulf of Alaska. Long-term survey data were analyzed using GIS/spatial analysis techniques and regression models to determine distribution (by depth, temperature, and latitude/longitude) and relative abundance of the dominant species in each region. Submersible video data were incorporated for California to facilitate habitat association analysis. We addressed three main questions: 1) Are there regions of differential importance to skates?, 2) Are ENP skate assemblages spatially segregated?, and 3) When skates co-occur, do they differ in size? Skate populations were highly clustered in both regions, on scales of 10s of kilometers; however, high-density regions (i.e., hot spots) were segregated among species. Skate densities and frequencies of occurrence were substantially lower in Alaska as compared to California. Although skates are generally found on soft sediment habitats, Raja rhina exhibited the strongest association with mixed substrates, and R. stellulata catches were greatest on rocky reefs. Size segregation was evident in regions where species overlapped substantially in geographic and depth distribution (e.g., R. rhina and Bathyraja kincaidii off California; B. aleutica and B. interrupta in the Gulf of Alaska). Spatial niche differentiation in skates appears to be more pronounced than previously reported. PMID:25329312

  2. Spatial Segregation in Eastern North Pacific Skate Assemblages

    PubMed Central

    Bizzarro, Joseph J.; Broms, Kristin M.; Logsdon, Miles G.; Ebert, David A.; Yoklavich, Mary M.; Kuhnz, Linda A.; Summers, Adam P.

    2014-01-01

    Skates (Rajiformes: Rajoidei) are common mesopredators in marine benthic communities. The spatial associations of individual species and the structure of assemblages are of considerable importance for effective monitoring and management of exploited skate populations. This study investigated the spatial associations of eastern North Pacific (ENP) skates in continental shelf and upper continental slope waters of two regions: central California and the western Gulf of Alaska. Long-term survey data were analyzed using GIS/spatial analysis techniques and regression models to determine distribution (by depth, temperature, and latitude/longitude) and relative abundance of the dominant species in each region. Submersible video data were incorporated for California to facilitate habitat association analysis. We addressed three main questions: 1) Are there regions of differential importance to skates?, 2) Are ENP skate assemblages spatially segregated?, and 3) When skates co-occur, do they differ in size? Skate populations were highly clustered in both regions, on scales of 10s of kilometers; however, high-density regions (i.e., hot spots) were segregated among species. Skate densities and frequencies of occurrence were substantially lower in Alaska as compared to California. Although skates are generally found on soft sediment habitats, Raja rhina exhibited the strongest association with mixed substrates, and R. stellulata catches were greatest on rocky reefs. Size segregation was evident in regions where species overlapped substantially in geographic and depth distribution (e.g., R. rhina and Bathyraja kincaidii off California; B. aleutica and B. interrupta in the Gulf of Alaska). Spatial niche differentiation in skates appears to be more pronounced than previously reported. PMID:25329312

  3. Geohydromechanical Processes in the Excavation Damaged Zone in Crystalline Rock, Rock Salt, and Indurated and Plastic Clays

    SciTech Connect

    Tsang, Chin-Fu; Bernier, Frederic; Davies, Christophe

    2004-06-20

    The creation of an excavation disturbed zone or excavation damaged zone is expected around all man-made openings in geologic formations. Macro- and micro-fracturing, and in general a redistribution of in situ stresses and rearrangement of rock structures, will occur in this zone, resulting in drastic changes of permeability to flow, mainly through the fractures and cracks induced by excavation. Such an EDZ may have significant implications for the operation and long-term performance of an underground nuclear waste repository. Various issues of concern need to be evaluated, such as processes creating fractures in the excavation damaged zone, the degree of permeability increase, and the potential for sealing or healing (with permeability reduction) in the zone. In recent years, efforts along these lines have been made for a potential repository in four rock types-crystalline rock, salt, indurated clay, and plastic clay-and these efforts have involved field, laboratory, and theoretical studies. The present work involves a synthesis of the ideas and issues that emerged from presentations and discussions on EDZ in these four rock types at a CLUSTER Conference and Workshop held in Luxembourg in November, 2003. First, definitions of excavation disturbed and excavation damaged zones are proposed. Then, an approach is suggested for the synthesis and intercomparison of geohydromechanical processes in the EDZ for the four rock types (crystalline rock, salt, indurated clay, and plastic clay). Comparison tables of relevant processes, associated factors, and modeling and testing techniques are developed. A discussion of the general state-of-the-art and outstanding issues are also presented. A substantial bibliography of relevant papers on the subject is supplied at the end of the paper.

  4. Sequential Subterranean Transport of Excavated Sand and Foraged Seeds in Nests of the Harvester Ant, Pogonomyrmex badius

    PubMed Central

    Tschinkel, Walter R.; Rink, William J.; Kwapich, Christina L.

    2015-01-01

    During their approximately annual nest relocations, Florida harvester ants (Pogonomyrmex badius) excavate large and architecturally-distinct subterranean nests. Aspects of this process were studied by planting a harvester ant colony in the field in a soil column composed of layers of 12 different colors of sand. Quantifying the colors of excavated sand dumped on the surface by the ants revealed the progress of nest deepening to 2 m and enlargement to 8 L in volume. Most of the excavation was completed within about 2 weeks, but the nest was doubled in volume after a winter lull. After 7 months, we excavated the nest and mapped its structure, revealing colored sand deposited in non-host colored layers, especially in the upper 30 to 40 cm of the nest. In all, about 2.5% of the excavated sediment was deposited below ground, a fact of importance to sediment dating by optically-stimulated luminescence (OSL). Upward transport of excavated sand is carried out in stages, probably by different groups of ants, through deposition, re-transport, incorporation into the nest walls and floors and remobilization from these. This results in considerable mixing of sand from different depths, as indicated in the multiple sand colors even within single sand pellets brought to the surface. Just as sand is transported upward by stages, incoming seeds are transported downward to seed chambers. Foragers collect seeds and deposit them only in the topmost nest chambers from which a separate group of workers rapidly transports them downward in increments detectable as a "wave" of seeds that eventually ends in the seed chambers, 20 to 80 cm below the surface. The upward and downward transport is an example of task-partitioning in a series-parallel organization of work carried out by a highly redundant work force in which each worker usually completes only part of a multi-step process. PMID:26509900

  5. Numerical Simulation of Rock Mass Damage Evolution During Deep-Buried Tunnel Excavation by Drill and Blast

    NASA Astrophysics Data System (ADS)

    Yang, Jianhua; Lu, Wenbo; Hu, Yingguo; Chen, Ming; Yan, Peng

    2015-09-01

    Presence of an excavation damage zone (EDZ) around a tunnel perimeter is of significant concern with regard to safety, stability, costs and overall performance of the tunnel. For deep-buried tunnel excavation by drill and blast, it is generally accepted that a combination of effects of stress redistribution and blasting is mainly responsible for development of the EDZ. However, few open literatures can be found to use numerical methods to investigate the behavior of rock damage induced by the combined effects, and it is still far from full understanding how, when and to what degree the blasting affects the behavior of the EDZ during excavation. By implementing a statistical damage evolution law based on stress criterion into the commercial software LS-DYNA through its user-subroutines, this paper presents a 3D numerical simulation of the rock damage evolution of a deep-buried tunnel excavation, with a special emphasis on the combined effects of the stress redistribution of surrounding rock masses and the blasting-induced damage. Influence of repeated blast loadings on the damage extension for practical millisecond delay blasting is investigated in the present analysis. Accompanying explosive detonation and secession of rock fragments from their initial locations, in situ stress in the immediate vicinity of the excavation face is suddenly released. The transient characteristics of the in situ stress release and induced dynamic responses in the surrounding rock masses are also highlighted. From the simulation results, some instructive conclusions are drawn with respect to the rock damage mechanism and evolution during deep-buried tunnel excavation by drill and blast.

  6. Benthic macroinvertebrate assemblages in the US nearshore zone of Lake Erie, 2009: Status and linkages to landscape-derived stressors

    EPA Science Inventory

    Benthic macroinvertebrate assemblages have been used as indicators of ecological condition because their responses integrate localized environmental conditions of the sediments and overlying water. Assemblages of benthic invertebrates in the near coastal region are of particular...

  7. A MULTI-ASSEMBLAGE INDEX OF STREAM INTEGRITY: WHAT ARE THE FISH, BUGS, AND ALGAE TELLING US?

    EPA Science Inventory

    Three different taxonomic assemblages have been proposed for use in the biological monitoring and assessment of water quality and stream biological integrity: fishm macroinvertebrates, and periphyton. All three assemblages can be eficiently collected with established methods, ar...

  8. Archaeogeophysical Studies in the Ruins of Kars-Ani (Turkey) in the 2009 Excavation Season

    NASA Astrophysics Data System (ADS)

    Hoskan, Nihan; Ahmet Yuksel, Fethi; Gorucu, Ziya; Coruhlu, Yasar

    2010-05-01

    The Ani ancient city, which is at 48 km distance to Kars (Turkey), is founded at the banks of the Arpacay River flowing in the vicinity of Turkey - Armenia border and is in the borders of Mevcut Ocakli Village. Recent studies show that the first settlement in Ani ancient city could be in the 5th millenium B.C.(Chalcolithic Period) and moreover, there were some buildings built in the Iron and Bronze Period. In the early 9th century, Ashot Msaker, who was Bagratuni dynasty (806-827), declared their first capital city at Bagaran, some 40 km south of Ani, and then transferred it to Kars in the year 929. In 961, King Ashot III (953-977) transferred the capital city from Kars to Ani. Ani expanded during the reign of King Smbat II (977-989). Recent research shows that by the early 11th century the population of Ani was over 100,000. After capture of Ashot, Ani surrendered to Byzantine controlled in 1045. A Greek governor was installed in the city. In 1064 a Seljuk Turkish army, headed by Sultan Alparslan, attacked and captured Ani. Then the Georgians captured Ani in 1124, 1161 and 1174. By the 14th century Ani was ruled by the Turkish dynasties, namely Jalayrids and the Kara Koyunlu. After the Persian Safavids ruled Ani, it became part of the Turkish Ottoman Empire in 1579. A small town remained within its walls until 1650 A.C. and it was completely abandoned by the middle of the 18th century. Examples of Sasani, Arabic, Armenian, and Seljuk architecture can be found among the Ani ruins. Ani is home to the first Turkish mosque built in Anatolia, namely Ebul Menucehr. The mosque was erected by the members of the Seljuk Dynasty in 1072. The first archaeological excavations were conducted at Ani in 1892. Since then, several archaeological excavations have been done in Ani. In the 2009 excavation season, magnetic methods were applied in Ani ruins to find the exact locations of the ruins. Magnetic Gradient Measurements were taken in front of Ebul Menucehr Mosque. After

  9. Spectroscopic characterization of recently excavated archaeological potsherds from Tamilnadu, India with multi-analytical approach.

    PubMed

    Raja Annamalai, G; Ravisankar, R; Rajalakshmi, A; Chandrasekaran, A; Rajan, K

    2014-12-10

    A combined analytical study of potsherds excavated from different archaeological sites of Tamilnadu (Kavalapatti, Nattapuraki and Thamaraikulam villages), India are analyzed by spectroscopic techniques such as FTIR, X-ray diffraction, thermogravimetric analysis (TGA) and Scanning Electron Microscope (SEM) coupled with Energy Dispersive Spectrometer (EDS). FTIR and XRD techniques have been attempted to characterize the mineralogical composition, firing temperature and firing conditions of the archaeological potsherds. Thermogravimetric analysis (TGA) is the complementary study to estimate the firing temperature from characteristic thermal reactions in potsherds under controlled firing in inert gas atmosphere. Further, Scanning Electron Microscopy (SEM) equipped and coupled with an Energy Dispersive Spectrometer (EDS) to analyze internal morphology and chemical composition of the potsherds was used. From the results of the above techniques, the firing temperatures of potsherds were found to be greater than 650°C. PMID:24929323

  10. Estimation of firing temperature of some archaeological pottery shreds excavated recently in Tamilnadu, India

    NASA Astrophysics Data System (ADS)

    Velraj, G.; Janaki, K.; Musthafa, A. Mohamed; Palanivel, R.

    2009-05-01

    An attempt has been made in the present work to estimate the firing temperature of the archaeological pottery shreds excavated from the three archaeological sites namely Maligaimedu, Thiruverkadu and Palur in the state of Tamilnadu in INDIA. The lower limit of firing temperature of the Archaeological pottery shreds were estimated by refiring the samples to different temperatures and recording the corresponding FT-IR spectrum. The firing methods and conditions of firing were inferred from the characteristic absorption positions and the bands observed due to the presence of magnetite and hematite in the samples. In addition, the Scanning Electron Microscopic analysis were carried out to study the internal morphology, vitrification factor and the upper limit of the firing temperature of the potteries fired at the time of manufacture.

  11. A Probabilistic Risk Assessment of Groundwater-Related Risks at Excavation Sites

    NASA Astrophysics Data System (ADS)

    Jurado, A.; de Gaspari, F.; Vilarrasa, V.; Sanchez-Vila, X.; Fernandez-Garcia, D.; Tartakovsky, D. M.; Bolster, D.

    2010-12-01

    Excavation sites such as those associated with the construction of subway lines, railways and highway tunnels are hazardous places, posing risks to workers, machinery and surrounding buildings. Many of these risks can be groundwater related. In this work we develop a general framework based on a probabilistic risk assessment (PRA) to quantify such risks. This approach is compatible with standard PRA practices and it employs many well-developed risk analysis tools, such as fault trees. The novelty and computational challenges of the proposed approach stem from the reliance on stochastic differential equations, rather than reliability databases, to compute the probabilities of basic events. The general framework is applied to a specific case study in Spain. It is used to estimate and minimize risks for a potential construction site of an underground station for the new subway line in the Barcelona metropolitan area.

  12. Estimation of firing temperature of some archaeological pottery shreds excavated recently in Tamilnadu, India.

    PubMed

    Velraj, G; Janaki, K; Musthafa, A Mohamed; Palanivel, R

    2009-05-01

    An attempt has been made in the present work to estimate the firing temperature of the archaeological pottery shreds excavated from the three archaeological sites namely Maligaimedu, Thiruverkadu and Palur in the state of Tamilnadu in INDIA. The lower limit of firing temperature of the Archaeological pottery shreds were estimated by refiring the samples to different temperatures and recording the corresponding FT-IR spectrum. The firing methods and conditions of firing were inferred from the characteristic absorption positions and the bands observed due to the presence of magnetite and hematite in the samples. In addition, the Scanning Electron Microscopic analysis were carried out to study the internal morphology, vitrification factor and the upper limit of the firing temperature of the potteries fired at the time of manufacture. PMID:19117795

  13. Abundance and reproductive patterns of the excavating sponge Cliona vermifera: a threat to Pacific coral reefs?

    NASA Astrophysics Data System (ADS)

    Bautista-Guerrero, Eric; Carballo, José Luis; Maldonado, Manuel

    2014-03-01

    Cliona vermifera is a common excavating sponge in coral reefs from the East Pacific. Abundance and reproductive patterns of the sponge in a Mexican Pacific coral reef over a 4-year period are herein described. Sponge abundance was estimated along three transects 50 m long which were randomly placed on the reef, and along each one, a piece of coral rubble and a branch of a live coral from the Pocillopora spp. coral colony closest to the transect were collected at random, approximately every 2 m, yielding 25 pieces of each category per transect (and 75 pieces total of each category). A 2-way ANOVA revealed that invasion was significantly higher in living coral colonies (34.8 %) than in rubble (13.7 %). It also indicated that the abundance in both coralline substrates showed a temporal variation without a clear pattern of increase over the years. It was estimated that 60-85 % of sponges in the population reproduced sexually every year. The sponge proved gonochoristic, with a sex ratio strongly departing from parity (1 male: 3 females). Over the 4-year study period, at least two cohorts of oocytes with densities of up to 3.5 oocytes per mm2 tissue were observed. Spermatogenesis lasted about a month, but often producing more than a pulse from July to November, coupled with peaks of oocyte maturation. Fertilization occurred internally to produce encapsulated zygotes that were released in one or more spawning events from July to November. In the following months (December to February), which were the periods of lowest temperature (~18.5-20 °C), no gametic activity occurred in the sponges. Because anomalous temperature rises that are detrimental to corals do not appear to negatively affect the reproduction and abundance of C. vermifera, it is likely that the excavating activity of this sponge may be compromising the health of those coral reefs that are recurrently affected by episodes of thermal stress.

  14. Nest relocation and excavation in the Florida harvester ant, Pogonomyrmex badius.

    PubMed

    Tschinkel, Walter R

    2014-01-01

    The Florida harvester ant (Pogonomyrmex badius) excavates deep nests in the sandy soils of the Gulf and Atlantic coastal plains. Nest relocations of over 400 colonies in a north Florida coastal plains pine forest were tracked and mapped from 2010 to 2013. Individual colonies varied from one move in two years to four times a year, averaging about one per year. Almost all moves occurred between May and November peaking in July when more than 1% of the colonies moved per day. Move directions were random, and averaged 4 m, with few moves exceeding 10 m. Distance moved was not related to colony size. Over multiple moves, paths were random walks around the original nest location. Relocation is probably intrinsic to the life history of this species, and the causes of relocation remain obscure--the architecture of old and new nests was very similar, and neither the forest canopy nor the density or size of neighbors was correlated with relocation. Monitoring entire relocations (n = 20) showed that they were usually completed in 4 to 6 days. Moves were diurnal, peaking in the mornings and afternoons dipping during mid-day, and ceasing before sundown. Workers excavated the new nest continuously during the daytime throughout the move and beyond. A minority of workers carried seeds, charcoal and brood, with seeds being by far the most common burden. The proportion of burdened workers increased throughout the move. Measured from year to year, small colonies gained size and large ones lost it. Colonies moving more than once in two years lost more size than those moving less often, suggesting that moving may bear a fitness cost. Colony relocation is a dramatic and consistent feature of the life history of the Florida harvester ant, inviting inquiry into its proximal and ultimate causes. PMID:25409332

  15. Monitoring DNA Contamination in Handled vs. Directly Excavated Ancient Human Skeletal Remains

    PubMed Central

    Pilli, Elena; Modi, Alessandra; Serpico, Ciro; Achilli, Alessandro; Lancioni, Hovirag; Lippi, Barbara; Bertoldi, Francesca; Gelichi, Sauro; Lari, Martina; Caramelli, David

    2013-01-01

    Bones, teeth and hair are often the only physical evidence of human or animal presence at an archaeological site; they are also the most widely used sources of samples for ancient DNA (aDNA) analysis. Unfortunately, the DNA extracted from ancient samples, already scarce and highly degraded, is widely susceptible to exogenous contaminations that can affect the reliability of aDNA studies. We evaluated the molecular effects of sample handling on five human skeletons freshly excavated from a cemetery dated between the 11 to the 14th century. We collected specimens from several skeletal areas (teeth, ribs, femurs and ulnas) from each individual burial. We then divided the samples into two different sets: one labeled as “virgin samples” (i.e. samples that were taken by archaeologists under contamination-controlled conditions and then immediately sent to the laboratory for genetic analyses), and the second called “lab samples”(i.e. samples that were handled without any particular precautions and subject to normal washing, handling and measuring procedures in the osteological lab). Our results show that genetic profiles from “lab samples” are incomplete or ambiguous in the different skeletal areas while a different outcome is observed in the “virgin samples” set. Generally, all specimens from different skeletal areas in the exception of teeth present incongruent results between “lab” and “virgin” samples. Therefore teeth are less prone to contamination than the other skeletal areas we analyzed and may be considered a material of choice for classical aDNA studies. In addition, we showed that bones can also be a good candidate for human aDNA analysis if they come directly from the excavation site and are accompanied by a clear taphonomic history. PMID:23372650

  16. Excavation and drilling at a spent-fuel test facility in granitic rock

    SciTech Connect

    Patrick, W.C.; Mayr, M.C.

    1981-10-01

    Funding for a project to test the feasibility of safe and reliable storage and retrieval of spent fuel from a commercial nuclear reactor was approved by the Department of Energy on June 2, 1978. By May 28, 1980, 11 spent-fuel assemblies had been emplaced 420 m below the surface in the Climax granitic stock at the Nevada Test Site. Design and construction of the Spent Fuel Test-Climax, including fuel emplacement, had taken less than two years, at a total cost of $18.4 million. Construction activities were preceded by geologic exploration using four cored holes and existing underground workings. The sinking of a 0.76-m-diam shaft to the 420-m level initiated construction at the site. Effective rates of sinking varied from 0.16 m/h with a rotary tricone drill to 0.5 m/h with a hammer drill. Underground excavation included a central canister-storage drift 4.6 x 6.1 x 64 m long, two parallel 3.4 x 3.4-m heater drifts, and a tail drift. About 6700 m{sup 3} were excavated at an average rate of 2 m{sup 3}/h, and 178 cored holes, with diameters from 38 to 152 mm, were drilled. A total length of nearly 1100 m was drilled at rates ranging from 0.4 m/h to 1 m/h, depending on hole size and drilling equipment. Eighteen 610-mm-diam canister emplacement holes were hammer-drilled at an average rate of 1.4 m/h. The use of the critical path method, integrated contractors, and close cooperation between project participants facilitated completion of the project on schedule.

  17. Particle Size Distributions Measured in B757 Engine Plume During EXCAVATE

    NASA Technical Reports Server (NTRS)

    Sanders, Terry; Penko, Paul; Culler, Steve; Rivera, Monica

    2005-01-01

    A ground-based test, the Experiment to Characterize Aircraft Volatile Aerosols and Trace Species Emissions (EXCAVATE), was conducted at NASA Langley Research Center, January 26 - 27, 2002, with a Boeing 757 aircraft. The aircraft was anchored on a tarmac and two probes were positioned downstream of the right-side engine, a Rolls Royce RB211-585. One probe was designed and fabricated by Arnold Engineering Development Center (AEDC) and had a 45.6 mm (1.794 in.) ID. A second probe, constructed of 6.4 mm (0.25 in.) stainless-steel tubing at NASA Langley Research Center, had a 6 mm (0.22 in.) ID. The engine was run on JP-5 with three different sulfur concentrations, 810 ppm, 1050 ppm, 1820 ppm; and was operated over a range of power settings from idle to near-full power. Particulate size-distributions and concentrations were measured at four downstream axial locations: 1 m and 10 m with the AEDC particulate probe, and 25 m and 35 m with the Langley probe. Fuel with various sulfur contents was tested to address the long-standing question of the role of sulfur in the formation of volatile species. Several experimental and modeling studies have shown a correlation between fuel sulfur-content and particulate-emissions. The object of EXCAVATE was to further study the effect of sulfur content on particulate number concentration and size-distribution as a function of location in the engine plume and engine operating conditions.

  18. The Role of Cell Compartmentalization and Cell Differentiation in Cyanobacterial Excavation of Miineral Carbonates

    NASA Astrophysics Data System (ADS)

    Garcia-Pichel, F.; Guida, B. S.; Couradeau, E.

    2015-12-01

    The bioerosion of coastal limestones and biogenic carbonates by boring filamentous or pseudo-filamentous cyanobacteria is not only a geomicrobial phenomenon of global proportions, but also plays an important role in the demise of coral reefs, and affects significantly human enterprises like bivalve fisheries. In spite of its importance, the mechanism by which cyanobacteria excavate carbonates constitutes an apparent paradox, in that their metabolism will tend to precipitate carbonates, not dissolved them. We have previously advanced, and obtained evidence for, a mechanism of excavation that relies on the uptake of Ca2+ by cells at the boring front, its trans-cellular transport along the filaments, and its eventual active excretion at the solid/liquid interface. It was postulated that the mechanism involved the strategically organized deployment of Ca2+ transport enzymes like P-type Ca2+ ATPases and Ca2+ channels. Here we present evidence that confirms this basic mechanism, but also reveals that it is based on an unexpected level of cellular complexity. The model organism Mastigocoleus testarum BC008, transports Ca2+ from the mineral to the external medium using a repetitive, polar arrangement of Ca2+ ATPases, localized preferentially on one cellular pole, in a ring conformation on the cell membrane adjacent to the trans-cellular septum, pumping Ca2+ locally towards the periplasmic space, from which it passively enters the next cell. This strain also develops specialized groups of cells, which we named calcicytes, often but not exclusively located at the ends of filaments, that accumulate large concentrations of Ca2+, some 40-fold higher than typical in microbes, and seem to act as sinks or capacitors in the trans-cellular Ca2+ transport. Calcicytes are also characterized by a lack of photosynthetic pigments, and a very high intracellular pH. These cellular adaptations can also be found in evolutionary distant euendoliths such as the pseudofilamentous Hyella sp.

  19. Hydraulic accumulator-motor-generator energy regeneration system for a hybrid hydraulic excavator

    NASA Astrophysics Data System (ADS)

    Lin, Tianliang; Wang, Qingfeng

    2012-11-01

    Though the traditional energy regeneration system(ERS) which used a hydraulic motor and a generator in hybrid excavators can regenerate part of the energy, the power of the motor and the generator should be larger and the time for regenerating energy is so short. At first, the structure of new ERS that combines the advantages of an electric and hydraulic accumulator is analyzed. The energy can be converted into both the electric energy and the hydraulic energy at the lowering of the boom and the generator can still works when the boom stops going down. Then, a method how to set the working pressure of the hydraulic accumulator is proposed. To avoid the excess loss, extra noise and shock pressure, a two-level pressure threshold method that the generator starts to work at the rising edge of the high pressure threshold and stops working at the falling edge of the low pressure threshold is presented to characterize the working mode of the generator. The control strategies on how to control the boom velocity at the lowering of the boom and how to improve the recovery efficiency when the boom stops going down are presented. The test bench of hybrid excavator with ERS is constructed, with which the studies on the influences of ERS on energy conversion efficiency and control performance are carried out. Experimental results show that the proposed ERS features better speed control performance of the boom than traditional ERS. It is also observed that an estimated 45% of the total potential energy could be regenerated at the lowering of the boom in the proposed ERS, and the power level of the generator and the hydraulic motor could be reduced by 60%. Hence, the proposed ERS has obvious advantages over the traditional ERS on the improvement of energy regeneration time, energy efficiency, control performance and economy.

  20. Nest Relocation and Excavation in the Florida Harvester Ant, Pogonomyrmex badius

    PubMed Central

    Tschinkel, Walter R.

    2014-01-01

    The Florida harvester ant (Pogonomyrmex badius) excavates deep nests in the sandy soils of the Gulf and Atlantic coastal plains. Nest relocations of over 400 colonies in a north Florida coastal plains pine forest were tracked and mapped from 2010 to 2013. Individual colonies varied from one move in two years to four times a year, averaging about one per year. Almost all moves occurred between May and November peaking in July when more than 1% of the colonies moved per day. Move directions were random, and averaged 4 m, with few moves exceeding 10 m. Distance moved was not related to colony size. Over multiple moves, paths were random walks around the original nest location. Relocation is probably intrinsic to the life history of this species, and the causes of relocation remain obscure— the architecture of old and new nests was very similar, and neither the forest canopy nor the density or size of neighbors was correlated with relocation. Monitoring entire relocations (n = 20) showed that they were usually completed in 4 to 6 days. Moves were diurnal, peaking in the mornings and afternoons dipping during mid-day, and ceasing before sundown. Workers excavated the new nest continuously during the daytime throughout the move and beyond. A minority of workers carried seeds, charcoal and brood, with seeds being by far the most common burden. The proportion of burdened workers increased throughout the move. Measured from year to year, small colonies gained size and large ones lost it. Colonies moving more than once in two years lost more size than those moving less often, suggesting that moving may bear a fitness cost. Colony relocation is a dramatic and consistent feature of the life history of the Florida harvester ant, inviting inquiry into its proximal and ultimate causes. PMID:25409332