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Sample records for fissure type vents

  1. Phimosis with Preputial Fissures as a Predictor of Undiagnosed Type 2 Diabetes in Adults.

    PubMed

    Huang, Yun-Ching; Huang, Yao-Kuang; Chen, Chih-Shou; Shindel, Alan W; Wu, Ching-Fang; Lin, Jian-Hui; Chiu, Kuo-Hsiung; Yang, Tzu-Hsin; Shi, Chung-Sheng

    2016-03-01

    Diabetes is usually asymptomatic in its early stage. Early diagnosis may improve outcomes by enabling initiation of treatment before end organ damage has progressed. The aim of this study was to determine whether the clinical sign of phimosis with preputial fissures is predictive of type 2 diabetes in patients not previously diagnosed with diabetes. Twenty-eight patients with acquired phimosis and preputial fissures were collected prospectively. Twenty-eight controls with acquired phimosis without preputial fissures were selected. Statistically significant differences were found in body mass index, random plasma glucose, glucosuria and glycosylated haemoglobin levels, but not in age, family history of diabetes, hypertension and classical hyperglycaemic symptoms. Diabetes was confirmed in all 28 patients in the preputial fissures group, but only 2 (7.1%) patients in the non-preputial fissures group (p < 0.0001). In conclusion, phimosis with preputial fissures may be a specific sign of undiagnosed diabetes mellitus. PMID:26349852

  2. Relationships between lava types, seafloor morphology, and the occurrence of hydrothermal venting in the ASHES vent field of Axial Volcano. [Axial Seamount Hydrothermal Emission Study

    SciTech Connect

    Hammond, S.R. )

    1990-08-10

    Deep-towed and submersible photographic surveys within the caldera of Axial Volcano have been integrated with high-resolution bathmetry to produce a geological map of the most active vent field in the caldera. Locations for over 2,000 photographs in and near the vent field were determined using a seafloor transponder network. Then each photograph was described utilizing a classification system which provides detailed information concerning lava type, hydrothermal activity, sediment cover, geological structure, and biology. Resulting data were entered into a digital data base, and computer-generated maps were created that portray spatial relationships between selected geological variables. In general, the entire ASHES field is characterized by pervasive low-temperature venting. The most vigorous venting is concentrated in an approximately 80 m {times} 80 m area where there are several high-temperature vents including some which are producing high-temperature vapor-phase fluids derived from a boiling hydrothermal system. Lava types within the ASHES vent field are grouped into three distinct morphologies: (1) smooth (flat-surfaced, ropy, and whorled) sheet flows, (2) lobate flows, and (3) jumbled-sheet flows. The most intense hydrothermal venting is concentrated in the smooth sheet flows and the lobate flows. The location of the ASHES field is mainly attributable to faulting which defines the southwest caldera wall, but the concentration of intense venting appears to be related also to the spatial distribution of lava types in the vent field and their contrasting permeabilities. Other structural trends of faults and fissures within the field also influence the location of individual events.

  3. Submarine fissure eruptions and hydrothermal vents on the southern Juan de Fuca Ridge: preliminary observations from the submersible Alvin.

    USGS Publications Warehouse

    Normark, W.R.

    1986-01-01

    The submersible Alvin was used to investigate 3 active hydrothermal discharge sites along the S Juan de Fuca Ridge in September 1984. The hydrothermal zones occur within a 10-30m-deep, 30-50m-wide cleft marking the center of the axial valley. This cleft is the eruptive locus for the axial valley. The hydrothermal vents coincide with the main eruptive vents along the cleft. Each hydrothermal zone has multiple discharge sites extending as much as 500m along the cleft. Sulfide deposits occur as clusters (15-100m2 area) of small chimneys (= or <2m high) and as individual and clustered fields of large, branched chimneys (= or <10m high). Recovered sulfide samples are predominantly the tops of chimneys and spires and typically contain more than 80% sphalerite and wurtzite with minor pyrrhotite, pyrite, marcasite, isocubanite, chalcopyrite, anhydrite, anhydrite, and amorphous silica. The associated hydrothermal fluids have the highest chlorinity of any reported to date.-Authors

  4. Anal fissure.

    PubMed

    Metcalf, Amanda M

    2002-12-01

    Anal fissure is a common condition with a characteristic presentation. Despite increased pharmaceutical options in the medical management of anal fissures, surgical therapy is not in danger of becoming obsolete. Lateral internal sphincterotomy remains an attractive option for many patients suffering from this painful condition. PMID:12516855

  5. Anal fissure

    PubMed Central

    Schlichtemeier, Steven; Engel, Alexander

    2016-01-01

    SUMMARY An anal fissure is a common, mostly benign, condition that can be acute or chronic. The diagnosis is usually made on history and physical examination, but further investigations are sometimes necessary. Primary fissures are usually benign and located in the posterior or anterior position. Secondary fissures are lateral or multiple and often indicate a more serious underlying pathology. The management of primary anal fissures is generally non-operative and includes increased dietary fibre, sitz baths, topical ointments and botulinum toxin injections. If these treatments are ineffective the patient will need a surgical referral. Secondary anal fissures require further investigation. Multidisciplinary management is preferable and is essential in the case of malignancy. PMID:27041801

  6. Chabazite in spodumene-bearing Alpine-type fissure veins from Hiddenite, North Carolina, USA

    NASA Astrophysics Data System (ADS)

    Wise, Michael A.

    2009-07-01

    Alpine-type fissure vein mineralization in the Hiddenite area of western North Carolina, USA consists mostly of quartz, but locally contains Cr-bearing beryl (emerald) or Cr-bearing spodumene (hiddenite). These gem minerals occur in mineral-lined cavities and may be accompanied by euhedral crystals of quartz, calcite, muscovite, rutile, albite, pyrite, siderite and dolomite. Chabazite-Ca occurs as a late stage phase in spodumene-bearing veins, but is absent in emerald-bearing veins. Chabazite-Ca occurs as simple penetrating twins of pseudocubic rhombohedra and as the lens-shaped variety, phacolite. Chabazite-Ca from Hiddenite contains minor amounts of Na, Mg, Fe and K. Phacolitic chabazite-Ca shows Fe-enriched but Mg-depleted cores relative to the rims. Chemical zoning is absent in rhombohedral chabazite. The Hiddenite chabazite apparently precipitated under low temperature (< 250°C) and low pressure (< 2 kbar) conditions during the waning stages of crystallization of an alkaline hydrothermal fluid.

  7. Shallow Subsurface Structures of Volcanic Fissures

    NASA Astrophysics Data System (ADS)

    Parcheta, C. E.; Nash, J.; Mitchell, K. L.; Parness, A.

    2015-12-01

    Volcanic fissure vents are a difficult geologic feature to quantify. They are often too thin to document in detail with seismology or remote geophysical methods. Additionally, lava flows, lava drain back, or collapsed rampart blocks typically conceal a fissure's surface expression. For exposed fissures, quantifying the surface (let along sub0surface) geometric expression can become an overwhelming and time-consuming task given the non-uniform distribution of wall irregularities, drain back textures, and the larger scale sinuosity of the whole fissure system. We developed (and previously presented) VolcanoBot to acquire robust characteristic data of fissure geometries by going inside accessible fissures after an eruption ends and the fissure cools off to <50 C. Data from VolcanoBot documents the fissure conduit geometry with a near-IR structured light sensor, and reproduces the 3d structures to cm-scale accuracy. Here we present a comparison of shallow subsurface structures (<30 m depth) within the Mauna Ulu fissure system and their counterpart features at the vent-to-ground-surface interface. While we have not mapped enough length of the fissure to document sinuosity at depth, we see a self-similar pattern of irregularities on the fissure walls throughout the entire shallow subsurface, implying a fracture mechanical origin similar to faults. These irregularities are, on average, 1 m across and protrude 30 cm into the drained fissure. This is significantly larger than the 10% wall roughness addressed in the engineering literature on fluid dynamics, and implies that magma fluid dynamics during fissure eruptions are probably not as passive nor as simple as previously thought. In some locations, it is possible to match piercing points across the fissure walls, where the dike broke the wall rock in order to propagate upwards, yet in other locations there are erosional cavities, again, implying complex fluid dynamics in the shallow sub-surface during fissure eruptions.

  8. Anal fissure

    MedlinePlus

    ... pain interferes with normal bowel movements Petroleum jelly Zinc oxide, 1% hydrocortisone cream, Preparation H, and other ... anal muscle Prescription creams such as nitrates or calcium channel blockers, applied over the fissure to help ...

  9. Radar Observations of Fissure-fed Basaltic Lava Flows, Craters of the Moon, Idaho

    NASA Technical Reports Server (NTRS)

    Martel, L.; Greeley, R.

    1985-01-01

    Changes in surface roughness of lava flows, estimated from dual polarization, synthetic aperture, X and L band side-looking airborne radar images, were tested as a means of locating fissure vent areas. If lava textures proess from smooth, near-vent shelly pahoehoe to hummocky pahoehoe to aa with distance from fissure vents, then radr images of the lava flows would show a progression from dark to brighter tones due to the flows' increasing radar back-scatter.

  10. Radar observations of fissure-fed basaltic lava flows, Craters of the Moon, Idaho

    NASA Astrophysics Data System (ADS)

    Martel, L.; Greeley, R.

    1985-04-01

    Changes in surface roughness of lava flows, estimated from dual polarization, synthetic aperture, X and L band side-looking airborne radar images, were tested as a means of locating fissure vent areas. If lava textures proess from smooth, near-vent shelly pahoehoe to hummocky pahoehoe to aa with distance from fissure vents, then radr images of the lava flows would show a progression from dark to brighter tones due to the flows' increasing radar back-scatter.

  11. The architecture and shallow conduits of Laki-type pyroclastic cones: insights into a basaltic fissure eruption

    NASA Astrophysics Data System (ADS)

    Reynolds, P.; Brown, R. J.; Thordarson, T.; Llewellin, E. W.

    2016-05-01

    Pyroclastic cones built along basaltic fissures provide important volcanological information, but it is often difficult to examine the early-erupted products due to burial by later products. Furthermore, it is rare to see the link between the feeder dyke and overlying cone fully exposed. In this study, we detail the architecture of a hybrid spatter cone, scoria half-cone and feeder dyke that has been dissected to below the pre-eruption surface by glacial floods. The cones were constructed during the 6-8 ka Rauðuborgir-Kvensöðul fissure eruption in North Iceland during Hawaiian- and Strombolian-style activities. Widening of their feeder dyke in the shallow sub-surface to produce an upward flaring morphology was accommodated by country rock removal and elastic host rock deformation. Ballistic calculations and stratigraphic relationships indicate that the scoria half-cone was constructed early in the eruption from the deposits of a lava fountain ~100 m high. A decline in fountain height and the generation of abundant welded deposits resulted in the formation of a nested spatter cone within the scoria half-cone. The cones are similar in structure and size to the hybrid scoria and spatter cones produced during the 15-km3 1783 Laki eruption and serve as a valuable window into the construction of pyroclastic edifices during basaltic fissure eruptions.

  12. SURFACE FISSURE FORMATION ABOVE UNDERGROUND COALSEAM FIRES: DIMENSIONLESS RELATIONSHIPS BETWEEN SURFACE FISSURES AND SUBSURFACE SUBSIDENCE

    NASA Astrophysics Data System (ADS)

    Ide, T. S.; Pollard, D. D.; Orr, F. M.

    2009-12-01

    Coalbed fires are uncontrolled subsurface fires that occur around the world. These fires are believed to be significant contributors to annual CO2 emissions. Although many of these fires have been burning for decades, researchers have only recently begun to investigate physical mechanisms that control fire behavior. One aspect that is poorly characterized is the relationship between subsurface combustion and surface fissures. At the surface above many fires, long, wide fissures are observed. At a coalbed fire near Durango, Colorado, these fissures form systematic orthogonal patterns that align with regional joints in the Upper Cretaceous Fruitland Formation. Understanding the mechanisms that form and widen these fissures is important, as the fissures are believed to play vital roles in sustaining the combustion in the subsurface by acting as chimneys for the escaping gases and conduits for incoming oxygen. In some of the coalbed fire simulation models available today, these fissures are treated as fixed boundary conditions, but we argue, using field observations and simulation results, that there exists a relationship between the location and magnitude of subsidence caused by the fire and the opening of fissures. Four distinct types of fissures are observed over the coalbed fire near Durango, CO. These fissures are termed ‘molehill’, ‘plateau’, ‘gaping’, and ‘narrow’ based on their surface appearances. Molehill fissures are marked by surface depressions on either side, causing the strata around the opening to form an apex towards the center of the fissure. Plateau fissures show a steep vertical offset on only one side with minimal horizontal displacement. Gaping fissures and narrow fissures are predominantly opening with little evidence for vertical displacements. Gaping fissures are defined as fissures with wide apertures (0.3 ~ 1.5m), while narrow fissures have apertures on the order of centimeters. A boundary element method code was used to show

  13. Engineering a robotic approach to mapping exposed volcanic fissures

    NASA Astrophysics Data System (ADS)

    Parcheta, C. E.; Parness, A.; Mitchell, K. L.

    2014-12-01

    Field geology provides a framework for advanced computer models and theoretical calculations of volcanic systems. Some field terrains, though, are poorly preserved or accessible, making documentation, quantification, and investigation impossible. Over 200 volcanologists at the 2012 Kona Chapman Conference on volcanology agreed that and important step forward in the field over the next 100 years should address the realistic size and shape of volcanic conduits. The 1969 Mauna Ulu eruption of Kīlauea provides a unique opportunity to document volcanic fissure conduits, thus, we have an ideal location to begin addressing this topic and provide data on these geometries. Exposed fissures can be mapped with robotics using machine vision. In order to test the hypothesis that fissures have irregularities with depth that will influence their fluid dynamical behavior, we must first map the fissure vents and shallow conduit to deci- or centimeter scale. We have designed, constructed, and field-tested the first version of a robotic device that will image an exposed volcanic fissure in three dimensions. The design phase included three steps: 1) create the payload harness and protective shell to prevent damage to the electronics and robot, 2) construct a circuit board to have the electronics communicate with a surface-based computer, and 3) prototype wheel shapes that can handle a variety of volcanic rock textures. The robot's mechanical parts were built using 3d printing, milling, casting and laser cutting techniques, and the electronics were assembled from off the shelf components. The testing phase took place at Mauna Ulu, Kīlauea, Hawai'i, from May 5 - 9, 2014. Many valuable design lessons were learned during the week, and the first ever 3D map from inside a volcanic fissure were successfully collected. Three vents had between 25% and 95% of their internal surfaces imaged. A fourth location, a non-eruptive crack (possibly a fault line) had two transects imaging the textures

  14. Anal fissure - slideshow

    MedlinePlus

    ... this page: //medlineplus.gov/ency/presentations/100154.htm Anal fissure - series—Normal anatomy To use the sharing ... rectum through which passes stool during defecation. The anal sphincter is a critical mechanism for control of ...

  15. Anal fissure - series (image)

    MedlinePlus

    ... rectum through which passes stool during defecation. The anal sphincter is a critical mechanism for control of ... Anal fissures are tears in the skin overlying the anal sphincter, usually due to increased tone of ...

  16. A Geophysical Study of Fissures in Pahrump, Nevada

    NASA Astrophysics Data System (ADS)

    Hirsch, A. C.; McEwan, M. J.; Howley, R. A.; Mehling, J. B.; Snelson, C. M.; Drohan, P.

    2004-12-01

    Earth fissures are surface expressions of deep fracturing subsidence systems caused by groundwater withdrawl greater than aquifer recharge. This type of subsidence is most common in arid environments of the south western U.S. such as, Las Vegas, NV, Phoenix, AZ, and areas in New Mexico. In addition, fissures have recently been identified in the Pahrump Valley in southwestern Nevada just west of Las Vegas. The city of Pahrump has experienced an increase in population and economic growth. This growth has lead to a higher demand in the use of the areas natural resources. One major concern is groundwater pumping and over-watering of the land surface. Pahrump has experienced significant differential subsidence within the valley causing significant structural damage to infrastructure. This differential subsidence is most readily identified by its surface expression as fissures. Earth fissures are not only shallow surface features but can be 10's of meters deep and 100's of meters long. These ground failures can be exacerbated by faults at depth, shallow bedrock, and/or differential compaction. However, the most significant cause is from groundwater withdrawl. Several geophysical methods were performed on the fissures to better understand their subsurface expression, trend, and ultimately their affect on the city of Pahrump. Seismic refraction, reflection, ground penetrating radar (GPR), and gravity measurements were performed on the fissures and surrounding area including local faults. Our initial studies show the fissures propagating for long distances, in a variety of shapes, and trending in a north-south direction. Initial GPR studies show high fissure reflections at approximately 1 and 1.5 meters along with general slumping features below these reflections. Fissures are an unmitigatable problem. Our results will help identify fissures in the area that do not have a surface expression as well as mapping the current fissures and their extent. These results can be used

  17. High-Temperature Hydrothermal Vent Field of Kolumbo Submarine Volcano, Aegean Sea: Site of Active Kuroko-Type Mineralization

    NASA Astrophysics Data System (ADS)

    Sigurdsson, H.; Carey, S.; Alexandri, M.; Vougioukalakis, G.; Croff, K.; Roman, C.; Sakellariou, D.; Anagnostou, C.; Rousakis, G.; Ioakim, C.; Gogou, A.; Ballas, D.; Misaridis, T.; Nomikou, P.

    2006-12-01

    Kolumbo submarine volcano is located 7 km north-east of the island of Santorini in the Hellenic arc (Greece), and comprises one of about twenty submarine cones in a NE-trending rift zone. Kolumbo erupted explosively in 1649-50AD, causing 70 fatalities on Santorini. Kolumbo's crater is 1700 m in diameter, with a crater rim at 10 m below sea level and crater floor at depth of 505 m. Recent marine geological investigations, using ROVs, reveal a very active high-temperature hydrothermal vent field in the northeastern part of the Kolumbo crater floor, about 25,000 m2. Vent chimneys up to 4 m high are vigorously emitting colorless gas plumes up to 10 m high in the water column. Temperatures up to 220oC are recorded in vent fluids. Some vents are in crater- like depressions, containing debris from collapsed extinct chimneys. The entire crater floor of Kolumbo is mantled by a reddish-orange bacterial mat, and bacterial filaments of a variety of colors cling to chimneys in dense clusters. Glassy tunicates and anemones are common in lower-temperature environments on the crater floor. Most chimneys show a high porosity, with a central conduit surrounded by an open and very permeable framework of sulfides and sulfates, aiding fluid flow through the chimney walls. In the sulfate-rich samples, blades of euhedral barite and anhydrite crystals coat the outside of the chimney wall, and layers of barite alternate with sulfide in the interior. The dominant sulfides are pyrite, sphalerite, wurtzite, marcasite and galena. Crusts on extinct and lower-temperature chimneys are composed of amorphous silica, goethite and halite. Sulfur isotope composition of sulfates is virtually at sea water values, whereas the sulfides are more depleted. Elevated levels of copper, gold and silver are observed in bulk composition of chimney samples. Both the structural setting, character of the vent field and sulfide/sulfate mineralogy and geochemistry indicate on-going Kuroko-type mineralization in the

  18. Vents to events: determining an eruption event record from volcanic vent structures for the Harrat Rahat, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Runge, Melody G.; Bebbington, Mark S.; Cronin, Shane J.; Lindsay, Jan M.; Kenedi, Catherine L.; Moufti, Mohammed Rashad H.

    2014-03-01

    Distributed "monogenetic" volcanic eruptions commonly occur in continental settings without obvious structural alignments or rifting/extensional structures. Nevertheless, these may develop as fissures, representing the surface expression of dykes with a range of orientations, especially when stress regimes vary over time and/or older crustal features and faults are exploited by rising magmas. Dykes reaching the surface as fissures can last hours to months and produce groups of closely aligned vents, hiding the true extent of the source fissure. Grouped or aligned vents in a distributed volcanic environment add complexity to hazard modelling where the majority of eruptions are single-vent, point-source features, represented by cones, craters or domes; i.e. vent groups may represent fissure events, or single eruptions coincidently located but erupted hundreds to tens of thousands of years apart. It is common practice in hazard estimation for intraplate monogenetic volcanism to assume that a single eruption cone or crater represents an individual eruptive event, but this could lead to a significant overestimate of temporal recurrence rates if multiple-site and fissure eruptions were common. For accurate recurrence rate estimates and hazard-event scenarios, a fissure eruption, with its multiple cones, must be considered as a single multi-dimensional eruptive event alongside the single-vent eruptions. We present a statistical method to objectively determine eruptive events from visible vents, and illustrate this using the 968 vents of the 10 Ma to 0.6 ka volcanic field of Harrat Rahat, Saudi Arabia. A further method is presented to estimate the number of hidden vents in a thick volcanic pile. By combining these two methods for Harrat Rahat, we determined an updated spatial recurrence rate estimate, and an average temporal recurrence rate of 7.5 × 10-5 events/year. This new analysis highlights more concentrated regions of higher temporal hazard in parts of Harrat Rahat

  19. Video monitoring analysis of the dynamics at fissure eruptions

    NASA Astrophysics Data System (ADS)

    Witt, Tanja; Walter, Thomas R.

    2016-04-01

    At basaltic eruption often lava fountains occur. The fountains mainly develop at erupting fissures, underlain by a magma-filled dike transporting the magma horizontally and vertically. Understanding of the dynamics of the deep dike and fracture mechanisms are mainly based on geophysical data as well as observations from seismic or geodetic networks. At the surface, however, new methods are needed to allow detailed interpretation on the eruption velocities, interactions between vents and complexities in the magma paths. With video cameras we collected imaging data from different erupting fissures. We find that lava fountaining is often correlated at distinct vents. From the frames of the videos we calculated the height and velocities of fountains as a function of time. Lava fountains often show a pulsating regime, that may change over time. Comparing the fountain height as a function of time of different vents by an time-dependent cross-correlation, we find a time lag between the pulses at adjacent vents. From this we derive an apparent velocity of temporal separation between vents, associated with the fountaining activity based on the calculated time lag and the vent distances. Although the correlation system can change episodically and sporadically, both the frequency of the fountains and eruption and the rest time between single fountains remain remarkably similar for adjacent lava fountains imply a controlling process in the magma feeder system itself. We present and compare our method for the Kamoamoa eruption 2011 (Hawaii) and the Holuhraun eruption 2014/2015 (Iceland). Both sites show a significant time shift between the single pulses of adjacent vents. We compare our velocities determined by this time shift to the assumed magma flow velocity in the dike as determined by independent models. Therefore we conjecture that the time shift of venting activity may allow to estimate the dynamics of magma and fluid migration at depth, as well as to identify the

  20. New volcanogenic-eruptive genetic type of diamond occurrence (based on studying the 2012-2013 Fissure Tolbachik Eruption in Kamchatka)

    NASA Astrophysics Data System (ADS)

    Karpov, Gennady; Anikin, Leonid; Filatov, Stanislav; Silaev, Valery; Petrovsky, Vitaly; Zolotarev, Andrey; Dunin-Barkovsky, Romuald; Volynets, Anna

    2014-05-01

    During the 2012-2013 Fissure Tolbachik eruption, diamonds were found both in fresh pyroclastics and in the effusive lava pores. Lavas are aphyric and subaphyric porous aluminous basaltic trachyandesites with rare megacrysts and subphenocrysts of plagioclase, olivine and pyroxene. Groundmass is hyalopilitic, pilotaxitic, occasionally hyaline, with abundant plagioclase microlites. So far, over 750 diamond grains have been found sized mostly 100-500 mkm. Generally, grains are well formed isometric, plane-faced and sharp-edged monocrystals of cubic-octahedral habit and green color, rarer colorless. Faces of rhombic-dodecahedron, tetragonal-trisoctahedron and trigonal-trisoctahedron also occur. Crystal cubic faces host pits of diffusive depletion, and pits with induction surfaces formed after the breakoff of syngenetic inclusions. Octahedral faces often show pyramidal etching pits formed at the dislocation outcrops. Pits contain coatings whose composition includes Fe, Mg, Ca, Si, and Cu-Sn (Zn) alloy films. Diamond X-ray diffraction data (Bruker APEX DUO, STOE IPDS II, MoKα-radiation, 788 reflections) show space group Fd-3m, cubic unit cell parameter a = 3.574(3) A and major reflections (111), (220), (311) etc. at Gandolfi pattern. Raman spectra with red beam reveal only one strong line at 1332 cm-1 typical for diamonds. Spectra excited by the 785 nm beam reveal a wide line with the peak at 1370 cm-1, whose intensity oscillates from 1% to 70% of the diamond line intensity at 1332 cm-1. Infrared absorption spectra reflect two lines with peaks at 1345 and 1130 cm-1, corresponding to structural C-defects (isolated N atoms). Partially, these defects occur in the positive charge state - N+. Structural nitrogen concentration in the form of C-defects varies from 150 to 500 ppm, while that in the form of N+ - from 10 to 30 ppm. Lines of infrared absorption on A and B1 nitrogen defects, as well as those on hydrogen defects typical for most natural diamonds, are not detected for

  1. Growing Hemorrhagic Choroidal Fissure Cyst

    PubMed Central

    Gelal, Fazıl; Gurkan, Gokhan; Feran, Hamit

    2016-01-01

    Choroidal fissure cysts are often incidentally discovered. They are usually asymptomatic. The authors report a case of growing and hemorrhagic choroidal fissure cyst which was treated surgically. A 22-year-old female presented with headache. Cranial MRI showed a left-sided choroidal fissure cyst. Follow-up MRI showed that the size of the cyst had increased gradually. Twenty months later, the patient was admitted to our emergency department with severe headache. MRI and CT showed an intracystic hematoma. Although such cysts usually have a benign course without symptoms and progression, they may rarely present with intracystic hemorrhage, enlargement of the cyst and increasing symptomatology. PMID:26962426

  2. Vented transmission

    SciTech Connect

    Nguyen, T.H.

    1990-01-29

    This patent describes a vented transmission. It comprises: a housing; a rotary input to the housing; a rotary output from the housing; transmission means within the housing interconnecting the input and the output and including a hollow, rotary shaft journaled within the housing; a vent tube having a first end extending into one end of the hollow shaft and a second end in fluid communication with the exterior of the housing; a shoulder within the hollow shaft and intermediate the ends of the vent tube and defining of relatively smaller diameter section near the first end of the vent tube that is within the hollow shaft and a relatively large diameter section nearer the second end of the vent tube; at least one aperture extending through the hollow shaft from the large diameter section immediately adjacent the shoulder; and a labyrinth seal at the interface of the vent tube and the large diameter section at a location between the aperture (s) and the second end of the vent tube.

  3. Influence of Geologic Setting on the Morphology, Mineralogy, and Geochemistry of Vent Deposits Along the Eastern Lau Spreading Center and Valu Fa Ridge

    NASA Astrophysics Data System (ADS)

    Tivey, M. K.; Evans, G. N.; Ferrini, V. L.

    2014-12-01

    Establishment of links between lithology, vent fluid chemistry, and vent deposit characteristics along the Eastern Lau Spreading Center (ELSC) and Valu Fa Ridge (VFR) was made possible using deep submergence vehicles and technology. ROV Jason was used to collect ultrahigh-resolution (submeter) bathymetric data sufficient to quantify characteristics of volcanic, tectonic and hydrothermal features; differences within vent fields from north to south include a change from low-relief volcanic domes cut by faults and fissures to higher aspect ratio volcanic domes dominated by aa-type lava morphologies (Ferrini et al., G-cubed, 2008). Highest temperature fluids are associated with crosscutting faults at all but Mariner vent field where faults are not observed. The detailed maps were used to target areas within vent fields for observations and sampling. Vent deposit morphologies are similar at the northernmost vent fields (Kilo Moana, TowCam, Tahi Moana), with black smokers and diffusers present on branched edifices. Vent deposits at the more southerly ABE, Tui Malila and Mariner vent fields vary in morphology, despite similar substrate lithology. Examples include abundant flanges at ABE and Tui Malila and ~20m-tall spires and squat barite-rich edifices at Mariner. Geochemical analyses and petrographic observations document the influence of lithology, fluid temperature, pH, and extents of seawater mixing on deposit formation. Concentrations of As, which increase from north to south, reflect lithologic control. Sb, Pb, and Ba concentrations also reflect lithologic control, but are affected as well by low pH and/or extents of seawater mixing. The significant differences in Mariner deposits reflect formation from very high temperature, low pH (<3 vs >4) fluids that keep Zn in solution, combined with local subsurface mixing. Overall, results document the influence of the Tonga Subduction Zone on vent deposits through its affects on lithology and vent fluid composition.

  4. Direct Monte Carlo Simulations of Gas Flow from Enceladus’ Nozzle-like Vents

    NASA Astrophysics Data System (ADS)

    Tucker, Orenthal; Combi, M. R.; Tenishev, V.

    2013-10-01

    Collective observations by the Cassini spacecraft indicate that the gas plumes emanating from Enceladus’ south pole contain micrometer sized ice grains that travel at speeds 50-80% lower than the bulk gas speed (Kempf et al., 2008, Hedman et al., 2009, Teolis et al., 2010). Previous studies indicate the difference in velocity originates below the surface, and the gas flow to the surface occurs supersonically suggestive of nozzle like vents (Schmidt et al., 2008, Hansen et al., 2011). Here we use a 2D Direct Monte Carlo Simulation (DSMC) technique (Bird, 1994) to model gas flow and grain acceleration in nozzle like fissures for Enceladus’ vent geometries. First, we use the DSMC technique to model the transition of the gas flow from inside the highly collisional vent to a couple of meters above the surface where the gas flow becomes essentially collisionless. Then the DSMC results for gas density, temperature and velocity are used with an equation of motion for the drag force on a grain entrenched in a gas. The flow is tracked in both the vertical direction from the vent opening, and the radial direction from the vent axis. It is impossible to consider every type of vent geometry, but using Cassini data for grain sizes and velocities within the plumes we consider a few vent geometries of different width, length, and opening angle with respect to the surface. The Enceladus vents are not likely to be axially symmetric, but the simulations provide insight into possible vent geometries, and the effect of the vent wall geometry on gas flow and grain acceleration for suggested plume water production rates (0.5 - 1×1028 s-1) inferred using Cassini data (Tenishev et al., 2010). We obtain density and velocity distributions at the vent exit for the gas and grains that can serve as parameters for plume models and be used as comparisons for interpretation of various Cassini measurements. Kempf, S., et al., 2008, Icarus 193, 2. Hedman, M.M., et al., 2009, AJ 693. Teolis, B

  5. Vented Capacitor

    DOEpatents

    Brubaker, Michael Allen; Hosking, Terry Alan

    2006-04-11

    A technique of increasing the corona inception voltage (CIV), and thereby increasing the operating voltage, of film/foil capacitors is described. Intentional venting of the capacitor encapsulation improves the corona inception voltage by allowing internal voids to equilibrate with the ambient environment.

  6. Construction and Evolution of an Ice-Confined Basaltic Eruptive Fissure Complex: Sveifluhals, SW Iceland

    NASA Astrophysics Data System (ADS)

    Mercurio, E. C.; Skilling, I. P.; Cameron, B.

    2009-05-01

    Ice-confined fissure-fed basaltic eruptions were common in Iceland during the Pleistocene. Most of these generated complexes consisting of closely spaced, sub-parallel, multi-vent ridges. Individual ridges are constructed mostly of numerous linked steep-sided mounds (point-source vents) and short ridges (fissure vents) of subaqueous lavas, most of which are draped by phreatomagmatic tephra. There are more than 1000 such ridges in Iceland and they represent an important, largely untapped, database on North Atlantic terrestrial ice conditions. Some of these complexes were of comparable length to the famous Laki fissure eruptions of 1783-1785. Sveifluhals is a 21.5-km long formerly ice-confined fissure complex of unknown age, but similar nearby centers have been dated at about 47ka. Ice-thickness estimates, based on volatile analysis of pillow rind glass vary from 70-400m. This is the first detailed study of such a complex, which focuses on how it was constructed in space and time, how it differs from published studies of simple single short fissure ice-confined centers, and how it interacted with the overlying ice. Initial results have identified vents with an average spacing of 0.7km on at least nine sub-parallel fissures, which are spaced about 0.1-0.5km apart. The vents are dominated by inward and outward-dipping rotated (oversteepened) blocks of bedded tephra, which overlies mostly slumped massive tephra. The tephra drapes subaqueous lava mounds that display marginal steep- ridges of subaqueous lavas, that may have been emplaced in short sub-ice tunnels. We have also identified several now dry lakes that formed in some inter-ridge areas, but whose age relationship to ridge construction is as yet uncertain. We present here our preliminary data on vent locations and estimates of product volumes, volumes of ice melted, and location of possible meltwater pathways. We discuss the most important differences of the processes and products of such ridge complexes compared

  7. Research of features related to land subsidence and ground fissure disasters in the Beijing Plain

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Luo, Y.; Liu, M.; Wang, R.; Wang, H.

    2015-11-01

    This study overviews the development history, current situation, impact, and hazards of land subsidence and ground fissure disasters in the Beijing Plain (BP) and focuses on the disaster distribution and features of disaster-causing mechanisms. Currently, the BP is still in a rapid developmental stage of land subsidence. The development and distribution of land subsidence are affected by various factors including the thickness of Quaternary compressible clay, groundwater overexploitation, and the rapid development of urban construction. The causes of ground fissures in the BP are complex and diverse, with evidence of structure fissures, non-structure fissures, and mixed genesis fissures. Investigations of the Gaoliying ground fissure have shown that this fissure has evidence of fracture activity, with vertical deformation that is more significant than horizontal deformation. Furthermore, this ground fissure has characteristics of inter-annual periodicity and annual jumping. The land subsidence and ground fissures are all under structural control and impact each other, and more severe hazards may be induced under the superimposition of these two types of disasters. Effective measures and suggestions for disaster prevention and control are recommended on the basis of this study.

  8. An opening magmatic fissure: structural pattern of its termination

    NASA Astrophysics Data System (ADS)

    Zelenin, Egor A.; Kozhurin, Andrey I.; Pinegina, Tatiana K.; Mikhaylyukova, Polina G.

    2014-05-01

    Volcanic zones of Kamchatka bear two types of active faults and fractures. Faults of the first type are tectonic, so they are long-living with net offset growing with time by repeating movement. Faults of the second type could be termed volcano-tectonic as they couple with or are caused by eruptions and thus move just once. Authors have explored and described a NE-SW-striking fissure on the SW side of Gorely plateau in the South Kamchatka volcanic zone, which conducted magma 200 years ago (Selyangin, Ponomareva, 1999). The fissure depression is filled with basaltic-andesite lava. The 900 meters long southern terminus of the fissure is situated on the hill slope and therefore not overlapped with lava. The fissure ending is an asymmetric graben, deeper at its west side, up to 300 m wide and bounded by two nearly parallel normal faults. The graben floor is gradually deepening to the north, away from the terminus, down to 9-10 m. Bounding faults are perfectly expressed in topography, thus providing a rare opportunity for determination of fissure parameters. Both faults dip at 80-85°, that gives approximately up to 3 m of perpendicular extension and the same thickness of the dyke beneath. Vertical movements on the western and eastern bounding faults were accompanied by horizontal components, left-lateral and right-lateral, respectively. There are also several transverse north-facing scarps breaking the graben floor and not extending beyond its limits. The observed deformations altogether suggests simultaneous sinking of the graben floor and northward compensating movement of masses into the graben. Tectonic landforms we studied illustrate how strain could be compensated at the end of an opening fissure and provide some insight into similar settings at a regional and even global scale.

  9. Microbial isotopic signatures in calcareous tufa from Punta Mita coastal vents, Mexico

    NASA Astrophysics Data System (ADS)

    Canet, C.; Prol-Ledesma, R. M.; Melgarejo, J. C.; Reyes, A.

    2002-12-01

    Numerous small calcareous mounds accompanied by Ba, Hg and Tl mineralization occur in shallow submarine hydrothermal manifestations on the sea bottom, at 10 m depth, in Punta Mita (Western coast of Mexico). The formation of calcite mounds in these coastal vents provides an uncommon example of calcareous tufa deposits in a submarine hydrothermal environment. The hydrothermal activity consists in water and gas (essentially nitrogen and methane) venting at 85°C, through a 100 m fissure hosted in basaltic rocks and partially covered by unconsolidated sediments. The mounds consist of travertine-like metre-sized calcite aggregates that develop around the main submarine hot springs. Barite, sulphides (mostly pyrite and cinnabar) and phosphates (carbonate-hydroxylapatite) are also present in these mounds. Two main calcite types are texturally distinguished: firstly an earlier radial-fibrous generation, and a later fine-grained calcite generation that cements the detrital grains and fills the pore spaces. Stable isotope analyses were performed in calcite from these mounds. The δ13C measured values show a strong depletion in 13C, with values as low as -39.2 per mil (PDB). These values agree with a microbially mediated calcite mineralization process, by means of bacterial oxidation of vent derived methane. In contrast to most known cases of microbial methane oxidation, in Punta Mita this process took place under hydrothermal conditions.

  10. Fluoride release from fissure sealants.

    PubMed

    Garcia-Godoy, F; Abarzua, I; De Goes, M F; Chan, D C

    1997-01-01

    This 30-day study, compared the amounts and patterns of fluoride release from 5 commercially available fluoride-containing pit and fissure sealants: FluroShield, Helioseal-F, Ultraseal XT, Baritone L3, and Teethmate-F; Delton without fluoride, was used as control. Disc-shaped samples of each sealant were immersed in distilled water and the fluoride release was measured periodically until day 30. All the fluoridated sealants tested released measurable fluoride throughout the test period in a similar pattern: the greatest amount of fluoride was released in the first 24 hours after mixing, fell sharply on the second day and decreased slowly for the last days. On day one, Baritone L3 released significantly more fluoride than all other materials. Teethmate-F released the highest amount of fluoride during all the other time intervals from day 2, until day 30. PMID:9643204

  11. Anorectal conditions: anal fissure and anorectal fistula.

    PubMed

    Fox, Audralan; Tietze, Pamela H; Ramakrishnan, Kalyanakrishnan

    2014-04-01

    Anal fissures are linear splits in the anal mucosa. Acute fissures typically resolve within a few weeks; chronic fissures persist longer than 8 to 12 weeks. Most fissures are posterior and midline and are related to constipation or anal trauma. Painful defecation and rectal bleeding are common symptoms. The diagnosis typically is clinical. High-fiber diet, stool softeners, and medicated ointments relieve symptoms and speed healing of acute fissures but offer limited benefit in chronic fissures. Lateral internal sphincterotomy is the surgical management of choice for chronic and refractory acute fissures. Anorectal fistula is an abnormal tract connecting the anorectal mucosa to the exterior skin. Fistulas typically develop after rupture or drainage of a perianal abscess. Fistulas are classified as simple or complex; low or high; and intersphincteric, transsphincteric, suprasphincteric, or extrasphincteric. Inspection of the perianal area identifies the skin opening, and anoscopy visualizes internal openings. The goal of management is to obliterate the tract and openings with negligible sphincter disruption to minimize incontinence. Fistulotomy is effective for simple fistulas; patients with complex fistulas may require fistulectomy. Other procedures that are used include injection of fibrin glue or insertion of a bioprosthetic plug into the fistula opening. PMID:24742084

  12. Gas venting system

    SciTech Connect

    Khan, Amjad; Dreier, Ken Wayne; Moulthrop, Lawrence Clinton; White, Erik James

    2010-06-29

    A system to vent a moist gas stream is disclosed. The system includes an enclosure and an electrochemical cell disposed within the enclosure, the electrochemical cell productive of the moist gas stream. A first vent is in fluid communication with the electrochemical cell for venting the moist gas stream to an exterior of the enclosure, and a second vent is in fluid communication with an interior of the enclosure and in thermal communication with the first vent for discharging heated air to the exterior of the enclosure. At least a portion of the discharging heated air is for preventing freezing of the moist gas stream within the first vent.

  13. A robotic approach to mapping post-eruptive volcanic fissure conduits

    NASA Astrophysics Data System (ADS)

    Parcheta, Carolyn E.; Pavlov, Catherine A.; Wiltsie, Nicholas; Carpenter, Kalind C.; Nash, Jeremy; Parness, Aaron; Mitchell, Karl L.

    2016-06-01

    VolcanoBot was developed to map volcanic vents and their underlying conduit systems, which are rarely preserved and generally inaccessible to human exploration. It uses a PrimeSense Carmine 1.09 sensor for mapping and carries an IR temperature sensor, analog distance sensor, and an inertial measurement unit (IMU) inside a protective shell. The first field test succeeded in collecting valuable scientific data but revealed several needed improvements, including more rugged cable connections and mechanical couplers, increased ground clearance, and higher-torque motors for uphill mobility. The second field test significantly improved on all of these aspects but it traded electrical ruggedness for reduced data collection speed. Data collected by the VolcanoBots, while intermittent, yield the first insights into the cm-scale geometry of volcanic fissures at depths of up to 25 m. VolcanoBot was deployed at the 1969 Mauna Ulu fissure system on Kīlauea volcano in Hawai'i. It collected first-of-its-kind data from inside the fissure system. We hypothesized that 1) fissure sinuosity should decrease with depth, 2) irregularity should be persistent with depth, 3) any blockages in the conduit should occur at the narrowest points, and 4) the fissure should narrow with depth until it is too narrow for VolcanoBot to pass or is plugged with solidified lava. Our field campaigns did not span enough lateral or vertical area to test sinuosity. The preliminary data indicate that 1) there were many irregularities along fissures at depth, 2) blockages occurred, but not at obviously narrow locations, and 3) the conduit width remained a consistent 0.4-0.5 m for most of the upper 10 m that we analyzed.

  14. Complete genome sequence of the aerobic, heterotroph Marinithermus hydrothermalis type strain (T1T) from a deep-sea hydrothermal vent chimney

    SciTech Connect

    Copeland, A; Gu, Wei; Yasawong, Montri; Lapidus, Alla L.; Lucas, Susan; Deshpande, Shweta; Pagani, Ioanna; Tapia, Roxanne; Cheng, Jan-Fang; Goodwin, Lynne A.; Pitluck, Sam; Liolios, Konstantinos; Ivanova, N; Mavromatis, K; Mikhailova, Natalia; Pati, Amrita; Chen, Amy; Palaniappan, Krishna; Land, Miriam L; Pan, Chongle; Brambilla, Evelyne-Marie; Rohde, Manfred; Tindall, Brian; Sikorski, Johannes; Goker, Markus; Detter, J. Chris; Bristow, James; Eisen, Jonathan; Markowitz, Victor; Hugenholtz, Philip; Kyrpides, Nikos C; Klenk, Hans-Peter; Woyke, Tanja

    2012-01-01

    Marinithermus hydrothermalis Sako et al. 2003 is the type species of the monotypic genus Marinithermus. M. hydrothermalis T1 T was the first isolate within the phylum ThermusDeinococcus to exhibit optimal growth under a salinity equivalent to that of sea water and to have an absolute requirement for NaCl for growth. M. hydrothermalis T1 T is of interest because it may provide a new insight into the ecological significance of the aerobic, thermophilic decomposers in the circulation of organic compounds in deep-sea hydrothermal vent ecosystems. This is the first completed genome sequence of a member of the genus Marinithermus and the seventh sequence from the family Thermaceae. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 2,269,167 bp long genome with its 2,251 protein-coding and 59 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

  15. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) Materials—(1) Pipe. Vent piping shall be standard weight steel, wrought iron, brass, copper tube DWV, listed... fittings shall conform to the type of piping used. (i) Fittings for screw pipe shall be cast iron, malleable iron, plastic, or brass, with standard pipe threads. (ii) Fittings for copper tubing shall be...

  16. Narrow Vertical Caves: Mapping Volcanic Fissure Geometries

    NASA Astrophysics Data System (ADS)

    Parcheta, C.; Nash, J.; Parness, A.; Mitchell, K. L.; Pavlov, C. A.

    2015-10-01

    Volcanic conduits are difficult to quantify, but their geometry fundamentally influences how eruptions occur. We robotically map old fissure conduits - elongated narrow cracks in the ground that transported magma to the surface during an eruption.

  17. Hemoglobins from deep-sea hydrothermal vent scaleworms of the genus Branchipolynoe: a new type of quaternary structure.

    PubMed

    Hourdez, S; Lallier, F H; Green, B N; Toulmond, A

    1999-03-01

    Branchipolynoe symmytilida and B. seepensis are two scaleworms (Polychaeta; Polynoidae) living commensally in the mantle cavity of deep-sea hydrothermal vent and cold-seep mussels. In contrast with littoral members of this family, the two species exhibit a large amount of extracellular hemoglobin (Hb) in their coelomic fluid. Gel filtration revealed the existence of four different Hbs: one minor, high molecular mass (3x10(6) Da) Hb, V1-Hb, reminiscent of a vascular hexagonal bilayer annelid Hb; two major coelomic Hbs, C1-Hb, and C2-Hb, with unusual masses for extracellular annelid Hbs of 153 and 124 kDa respectively; and a minor probably coelomic Hb of 23 kDa (C3-Hb). Using electrospray ionization mass spectrometry, SDS-PAGE after subtilisin treatment, and tandem mass spectrometry, we showed that C1-Hb is a trimer of a 57,996 Da chain and C2-Hb is a dimer of a 57,648 Da chain, each chain being a four-domain/four-heme polypeptide. This multimeric, multidomain arrangement is unique among annelid Hbs and appears different from that of other known multidomain Hbs. PMID:10081955

  18. Overview of the precursors and dynamics of the 2012-13 basaltic fissure eruption of Tolbachik Volcano, Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Belousov, Alexander; Belousova, Marina; Edwards, Benjamin; Volynets, Anna; Melnikov, Dmitry

    2015-12-01

    We present a broad overview of the 2012-13 flank fissure eruption of Plosky Tolbachik Volcano in the central Kamchatka Peninsula. The eruption lasted more than nine months and produced approximately 0.55 km3 DRE (volume recalculated to a density of 2.8 g/cm3) of basaltic trachyandesite magma. The 2012-13 eruption of Tolbachik is one of the most voluminous historical eruptions of mafic magma at subduction related volcanoes globally, and it is the second largest at Kamchatka. The eruption was preceded by five months of elevated seismicity and ground inflation, both of which peaked a day before the eruption commenced on 27 November 2012. The batch of high-Al magma ascended from depths of 5-10 km; its apical part contained 54-55 wt.% SiO2, and the main body 52-53 wt.% SiO2. The eruption started by the opening of a 6 km-long radial fissure on the southwestern slope of the volcano that fed multi-vent phreatomagmatic and magmatic explosive activity, as well as intensive effusion of lava with an initial discharge of > 440 m3/s. After 10 days the eruption continued only at the lower part of the fissure, where explosive and effusive activity of Hawaiian-Strombolian type occurred from a lava pond in the crater of the main growing scoria cone. The discharge rate for the nine month long, effusion-dominated eruption gradually declined from 140 to 18 m3/s and formed a compound lava field with a total area of ~ 36 km2; the effusive activity evolved from high-discharge channel-fed 'a'a lavas to dominantly low-discharge tube-fed pahoehoe lavas. On 23 August, the effusion of lava ceased and the intra-crater lava pond drained. Weak Strombolian-type explosions continued for several more days on the crater bottom until the end of the eruption around 5 September 2013. Based on a broad array of new data collected during this eruption, we develop a model for the magma storage and transport system of Plosky Tolbachik that links the storage zones of the two main genetically related magma

  19. Short communication: sclerosing meningioma in the deep sylvian fissure.

    PubMed

    Fukushima, Shintaro; Narita, Yoshitaka; Yonezawa, Motoki; Ohno, Makoto; Arita, Hideyuki; Miyakita, Yasuji; Ichimura, Koichi; Yoshida, Akihiko; Shibui, Soichiro

    2014-10-01

    Sclerosing meningioma is a rare type of meningeal tumor with extensive collagen depositions. Deep sylvian meningioma, a tumor that is unattached to the dura mater, is also unusual. The biological activity of both is controversial, as are therapeutic strategies. A heterogeneous contrast-enhanced mass in the right sylvian fissure of a 10-year-old boy with a 3-year history of epilepsy was identified via magnetic resonance imaging. The patient underwent partial surgical resection because the tumor was hard and contained numerous perforators arising from the right middle cerebral artery. The tumor was histologically diagnosed as sclerosing meningioma. Twelve months after surgery, the patient was asymptomatic and did not require any additional therapies. This case is the first report of a sclerosing meningioma arising in the deep sylvian fissure. We discuss the therapeutic dilemma of this case with respect to the current literature. PMID:24141724

  20. Modeling plaque fissuring and dissection during balloon angioplasty intervention.

    PubMed

    Gasser, T Christian; Holzapfel, Gerhard A

    2007-05-01

    Balloon angioplasty intervention is traumatic to arterial tissue. Fracture mechanisms such as plaque fissuring and/or dissection occur and constitute major contributions to the lumen enlargement. However, these types of mechanically-based traumatization of arterial tissue are also contributing factors to both acute procedural complications and chronic restenosis of the treatment site. We propose physical and finite element models, which are generally useable to trace fissuring and/or dissection in atherosclerotic plaques during balloon angioplasty interventions. The arterial wall is described as an anisotropic, heterogeneous, highly deformable, nearly incompressible body, whereas tissue failure is captured by a strong discontinuity kinematics and a novel cohesive zone model. The numerical implementation is based on the partition of unity finite element method and the interface element method. The later is used to link together meshes of the different tissue components. The balloon angioplasty-based failure mechanisms are numerically studied in 3D by means of an atherosclerotic-prone human external iliac artery, with a type V lesion. Image-based 3D geometry is generated and tissue-specific material properties are considered. Numerical results show that in a primary phase the plaque fissures at both shoulders of the fibrous cap and stops at the lamina elastica interna. In a secondary phase, local dissections between the intima and the media develop at the fibrous cap location with the smallest thickness. The predicted results indicate that plaque fissuring and dissection cause localized mechanical trauma, but prevent the main portion of the stenosis from high stress, and hence from continuous tissue damage. PMID:17385047

  1. Testing Geyser Models using Down-vent Data

    NASA Astrophysics Data System (ADS)

    Wang, C.; Munoz, C.; Ingebritsen, S.; King, E.

    2013-12-01

    Geysers are often studied as an analogue to magmatic volcanoes because both involve the transfer of mass and energy that leads to eruption. Several conceptual models have been proposed to explain geyser eruption, but no definitive test has been performed largely due to scarcity of down-vent data. In this study we compare simulated time histories of pressure and temperature against published data for the Old Faithful geyser in the Yellowstone National Park and new down-vent measurements from geysers in the El Tatio geyser field of northern Chile. We test two major types of geyser models by comparing simulated and field results. In the chamber model, the geyser system is approximated as a fissure-like conduit connected to a subsurface chamber of water and steam. Heat supplied to the chamber causes water to boil and drives geyser eruptions. Here the Navier-Stokes equation is used to simulate the flow of water and steam. In the fracture-zone model, the geyser system is approximated as a saturated fracture zone of high permeability and compressibility, surrounded by rock matrix of relatively low permeability and compressibility. Heat supply from below causes pore water to boil and drives geyser eruption. Here a two-phase form of Darcy's law is assumed to describe the flow of water and steam (Ingebritsen and Rojstaczer, 1993). Both models can produce P-T time histories qualitatively similar to field results, but the simulations are sensitive to assumed parameters. Results from the chamber model are sensitive to the heat supplied to the system and to the width of the conduit, while results from the fracture-zone model are most sensitive to the permeability of the fracture zone and the adjacent wall rocks. Detailed comparison between field and simulated results, such as the phase lag between changes of pressure and temperature, may help to resolve which model might be more realistic.

  2. Fissure distribution at Mauna Loa (Hawaii) as an example to understand shallow magma transfer at volcanoes

    NASA Astrophysics Data System (ADS)

    La Marra, Daniele; Acocella, Valerio; Trusdell, Frank

    2016-04-01

    Mauna Loa (Hawaii) is the largest active shield volcano on the Island of Hawai'i, covering more than half of it and rising to 4,169 meters above sea level. The volcano hosts the Moku'aweoweo summit caldera, from which two elongated rift zones depart: the Northeast Rift Zone (NERZ) and the Southwest Rift Zone (SWRZ). Most of Mauna Loa's eruptions begin with lava fountains from a series of fissure vents in the summit region and then often migrate to vents down either rift zone. Mauna Loa volcano shows a distinctive feature, being characterized by minor radial eruptive fissures (not related to the two main rifts) on the NW flank only. This study tries to explain such a selective distribution of vents, and thus of shallow magma transfer. To this aim, we run numerical models with different amount of opening of the two rift zones of Mauna Loa, as well as different amount of slip on its SE flank. Our results suggest that the selective occurrence of the radial fissures may be explained by the competition between two processes: a) rift intrusion (especially along the NERZ), promoting the development of radial dikes along the NW flank; b) flank slip, inhibiting the development of the radial dikes on the SE flank. The opening of the two non-parallel main rift zones of Mauna Loa promotes the local extension necessary to develop the radial dikes on the NW flank. A general model for the development of a third branch of radial rift, which may be also applied to Mt. Etna and some volcanoes on the Canary Islands, is proposed.

  3. Hydrothermal vents of Yellowstone Lake, Yellowstone National Park, Wyoming

    SciTech Connect

    Kaplinski, M.A.; Morgan, P. . Geology Dept.)

    1993-04-01

    Hydrothermal vent systems within Yellowstone Lake are located within the Yellowstone caldera in the northeastern and West Thumb sections of the lake. The vent systems lie within areas of extremely high geothermal gradients (< 1,000 C/km) in the lake sediments and occur as clusters of individual vents that expel both hydrothermal fluids and gas. Regions surrounding the vents are colonized by unique, chemotropic biologic communities and suggest that hydrothermal input plays an important role in the nutrient dynamics of the lake's ecosystem. The main concentration of hydrothermal activity occurs in the northeast region of the main lake body in a number of locations including: (1) along the shoreline from the southern edge of Sedge Bay to the inlet of Pelican Creek; (2) the central portion of the partially submerged Mary Bay phreatic explosion crater, within deep (30--50 m) fissures; (3) along the top of a 3 km long, steep-sided ridge that extends from the southern border of Mary Bay, south-southeast into the main lake basin; and (4) east of Stevenson Island along the lower portion of the slope (50--107 m) into the lake basin, within an anastomosing series of north to northwest trending, narrow troughs or fissures. Hydrothermal vents were also located within, and surrounding the West Thumb of Yellowstone Lake, with the main concentration occurring the offshore of the West Thumb and Potts Geyser Basin. Hydrothermal vents in Yellowstone Lake occur along fractures that have penetrated the lake sediments or along the tops of ridges and near shore areas. Underneath the lake, rising hydrothermal fluids encounter a semi-permeable cap of lake sediments. Upwardly convecting hydrothermal fluid flow may be diverted by the impermeable lake sediments along the buried, pre-existing topography. These fluids may continue to rise along topography until fractures are encountered, or the lake sediment cover is thinned sufficiently to allow egress of the fluids.

  4. Robust pulmonary lobe segmentation against incomplete fissures

    NASA Astrophysics Data System (ADS)

    Gu, Suicheng; Zheng, Qingfeng; Siegfried, Jill; Pu, Jiantao

    2012-03-01

    As important anatomical landmarks of the human lung, accurate lobe segmentation may be useful for characterizing specific lung diseases (e.g., inflammatory, granulomatous, and neoplastic diseases). A number of investigations showed that pulmonary fissures were often incomplete in image depiction, thereby leading to the computerized identification of individual lobes a challenging task. Our purpose is to develop a fully automated algorithm for accurate identification of individual lobes regardless of the integrity of pulmonary fissures. The underlying idea of the developed lobe segmentation scheme is to use piecewise planes to approximate the detected fissures. After a rotation and a global smoothing, a number of small planes were fitted using local fissures points. The local surfaces are finally combined for lobe segmentation using a quadratic B-spline weighting strategy to assure that the segmentation is smooth. The performance of the developed scheme was assessed by comparing with a manually created reference standard on a dataset of 30 lung CT examinations. These examinations covered a number of lung diseases and were selected from a large chronic obstructive pulmonary disease (COPD) dataset. The results indicate that our scheme of lobe segmentation is efficient and accurate against incomplete fissures.

  5. Outpatient treatment of fissure-in-ano.

    PubMed

    Badejo, O A

    1984-12-01

    A review of 86 cases of fissure-in-ano as seen in Ife is presented. The method of management is described and compared with other conservative methods of treatment. The results show a complete healing of the condition within two weeks as compared with four to six weeks recorded in other series. Healing was confirmed by a complete resolution of symptoms together with re-epithelisation of the fissure on inspection at proctoscopy. It is suggested that the described surgical management is simple, fast, cost reducing and time saving in the treatment of fissure-in-ano. It is further envisaged that this procedure may also serve as a means of relief to our already congested hospitals. PMID:6528355

  6. Effect of surface fissure on apparent resistivity measurements

    NASA Astrophysics Data System (ADS)

    Sailhac, P.; Gance, J.; Malet, J.

    2013-12-01

    Fissures are features of interest, prone to create preferential flow path, modifying locally the soil hydrogeological behavior. Electrical Resistivity Tomography (ERT) is a suitable tool to monitor such preferential flow path. However, this technique is not efficient in the presence of surface fissure, due to a bad resistivity recovering around the fissure vicinity during the inversion process. Therefore, we propose a description of fissure effect on raw apparent resistivity on three resistivity arrays. The purposes of the study are multiple. First, we aim at making ERT users aware of surface fissure effect, and propose a first help to interpret basically resistivity pseudo sections. Second, we propose to ERT users to automatically conduct a surface fissure survey on the studied profile, in order to consider each fissure in a forward DC model and to suppress their effect. Finally, this study is only a first step toward 2D fissure shape inversion, and time-lapse monitoring of fissure drying and filling. In this study, we create a fissure model based on different geomorphological descriptors. After describing the FEM-DC forward modeling strategy, we investigate the fissure effect on pseudo section of apparent resistivity for a Wenner-Schlumberger (WS), a dipole-dipole (DD) and a gradient (GRAD) array. We determine a fissure detectability threshold for each array and perform a sensitivity analysis on the different fissure parameters (position, width, depth, dip angles...). The crack filling or drying effect is also investigated. The possibility to remove fissure effect and to propose a first interpretation of time-lapse data is illustrated on real data. This study show again the higher sensitivity of the DD array compared to the GRAD and WS arrays. Not only the maximal amplitude in the pseudo section is higher for the DD array, but also the anomaly pattern created by the fissure is much larger for this acquisition geometry. The minimal depth detectable for the DD

  7. Thoracoscopic sympathetic clamping in a patient with an azygos fissure.

    PubMed

    Moon, Seok Whan; Yoon, Jeong Sub; Jo, Keon Hyeon; Wang, Young Pil; Park, Hyeon Jin

    2005-04-01

    We believe that an azygos fissure may predispose to bleeding during thoracoscopic surgery. An azygos fissure causes important morphologic changes in the superior mediastinum and thereby poses a risk of massive bleeding during thoracoscopic procedures. We report on a successful thoracoscopic procedure conducted in a patient with palmar hyperhidrosis and an azygos fissure and emphasize that the course of the thoracic sympathetic chain runs laterally along the base of the azygos fissure. PMID:15821627

  8. Geochemistry of the 2012-2013 Tolbachik Fissure eruption (Kamchatka, Russia)

    NASA Astrophysics Data System (ADS)

    Volynets, Anna; Melnikov, Dmitry; Belousov, Alexander; Belousova, Marina; Yakushev, Anton

    2014-05-01

    From November 27th, 2012, until the beginning of September 2013, a fissure eruption at the southern slope of Ploskiy Tolbachik volcano, Kamchatka, produced more than 0.52 km3 of lava (Dvigalo et al., 2014) and covered the area about 36 km2. The eruption was named as "The Institute of Volcanology and Seismology 50th Anniversary Fissure Tolbachik Eruption" (FTE-50). This is a manifestation of the ongoing high activity in Tolbachinskiy Dol (monogenetic zone around Ploskiy Tolbachik stratovolcano), which already produced in Holocene a lava field, covering more than 900 km2. FTE-50 lasted 9 months and exhibited some peculiar features, allowing us to distinguish it as a unique for Tolbachinskiy Dol: seismic activity only in the low energy class during 5 month prior to eruption (Kugaenko et al., 2013), the unusually high discharge rate at the beginning of the eruption (about 400 m3/sec), specific geochemical composition of the erupted lava. The eruption started from two vents, named after eminent Russian volcanologists as Menyailov (upper) and Naboko (lower) vents, and after three days all activity concentrated in the lower (Naboko) vent. All products of FTE-50 are richer in alkalis and TiO2 than previously studied lavas of Tolbachinskiy Dol. After the drastic change in composition at the beginning of the eruption, associated with the shift of the eruption center from the Menyailov to Naboko vent, when silica content dropped up to 2 wt.%, the composition remained practically constant until at least May 2013. Lavas of the Menyailov Vent are more acid than any of the earlier erupted rocks of the monogenetic zone (SiO2 up to 55.35 wt.%). Lavas of the Naboko Vent, at silica content close to the Southern Vent of the Great Fissure Tolbachik Eruption (1975-76) and other alumina-rich basaltic andesites of the Dol (52.5 wt.% in average in Naboko vent lavas vs. 51.8 wt.% in high-Al lavas from Tolb.Dol), have lowered concentrations of Al2O3 (16.3 wt.% vs. 17.1 wt/%), CaO (7.5 wt

  9. Battery venting system and method

    DOEpatents

    Casale, Thomas J.; Ching, Larry K. W.; Baer, Jose T.; Swan, David H.

    1999-01-05

    Disclosed herein is a venting mechanism for a battery. The venting mechanism includes a battery vent structure which is located on the battery cover and may be integrally formed therewith. The venting mechanism includes an opening extending through the battery cover such that the opening communicates with a plurality of battery cells located within the battery case. The venting mechanism also includes a vent manifold which attaches to the battery vent structure. The vent manifold includes a first opening which communicates with the battery vent structure opening and second and third openings which allow the vent manifold to be connected to two separate conduits. In this manner, a plurality of batteries may be interconnected for venting purposes, thus eliminating the need to provide separate vent lines for each battery. The vent manifold may be attached to the battery vent structure by a spin-welding technique. To facilitate this technique, the vent manifold may be provided with a flange portion which fits into a corresponding groove portion on the battery vent structure. The vent manifold includes an internal chamber which is large enough to completely house a conventional battery flame arrester and overpressure safety valve. In this manner, the vent manifold, when installed, lessens the likelihood of tampering with the flame arrester and safety valve.

  10. Battery venting system and method

    DOEpatents

    Casale, T.J.; Ching, L.K.W.; Baer, J.T.; Swan, D.H.

    1999-01-05

    Disclosed herein is a venting mechanism for a battery. The venting mechanism includes a battery vent structure which is located on the battery cover and may be integrally formed therewith. The venting mechanism includes an opening extending through the battery cover such that the opening communicates with a plurality of battery cells located within the battery case. The venting mechanism also includes a vent manifold which attaches to the battery vent structure. The vent manifold includes a first opening which communicates with the battery vent structure opening and second and third openings which allow the vent manifold to be connected to two separate conduits. In this manner, a plurality of batteries may be interconnected for venting purposes, thus eliminating the need to provide separate vent lines for each battery. The vent manifold may be attached to the battery vent structure by a spin-welding technique. To facilitate this technique, the vent manifold may be provided with a flange portion which fits into a corresponding groove portion on the battery vent structure. The vent manifold includes an internal chamber which is large enough to completely house a conventional battery flame arrester and overpressure safety valve. In this manner, the vent manifold, when installed, lessens the likelihood of tampering with the flame arrester and safety valve. 8 figs.

  11. Battery Vent Mechanism And Method

    DOEpatents

    Ching, Larry K. W.

    2000-02-15

    Disclosed herein is a venting mechanism for a battery. The venting mechanism includes a battery vent structure which is located on the battery cover and may be integrally formed therewith. The venting mechanism includes an opening extending through the battery cover such that the opening communicates with a plurality of battery cells located within the battery case. The venting mechanism also includes a vent manifold which attaches to the battery vent structure. The vent manifold includes a first opening which communicates with the battery vent structure opening and second and third openings which allow the vent manifold to be connected to two separate conduits. In this manner, a plurality of batteries may be interconnected for venting purposes, thus eliminating the need to provide separate vent lines for each battery. The vent manifold may be attached to the battery vent structure by a spin-welding technique. To facilitate this technique, the vent manifold may be provided with a flange portion which fits into a corresponding groove portion on the battery vent structure. The vent manifold includes an internal chamber which is large enough to completely house a conventional battery flame arrester and overpressure safety valve. In this manner, the vent manifold, when installed, lessens the likelihood of tampering with the flame arrester and safety valve.

  12. Payload bay atmospheric vent airflow testing at the Vibration and Acoustic Test Facility

    NASA Technical Reports Server (NTRS)

    Johnston, James D., Jr.

    1988-01-01

    Several concerns related to venting the Space Shuttle Orbiter payload bay during launch led to laboratory experiments with a flight-type vent box installed in the wall of a subsonic wind tunnel. This report describes the test setups and procedures used to acquire data for characterization of airflow through the vent box and acoustic tones radiated from the vent-box cavity. A flexible boundary-layer spoiler which reduced the vent-tone amplitude is described.

  13. Multiple I-Type Lysozymes in the Hydrothermal Vent Mussel Bathymodiolus azoricus and Their Role in Symbiotic Plasticity.

    PubMed

    Detree, Camille; Chabenat, Apolline; Lallier, François H; Satoh, Nori; Shoguchi, Eiichi; Tanguy, Arnaud; Mary, Jean

    2016-01-01

    The aim of this study was first to identify lysozymes paralogs in the deep sea mussel Bathymodiolus azoricus then to measure their relative expression or activity in different tissue or conditions. B. azoricus is a bivalve that lives close to hydrothermal chimney in the Mid-Atlantic Ridge (MAR). They harbour in specialized gill cells two types of endosymbiont (gram-bacteria): sulphide oxidizing bacteria (SOX) and methanotrophic bacteria (MOX). This association is thought to be ruled by specific mechanism or actors of regulation to deal with the presence of symbiont but these mechanisms are still poorly understood. Here, we focused on the implication of lysozyme, a bactericidal enzyme, in this endosymbiosis. The relative expression of Ba-lysozymes paralogs and the global anti-microbial activity, were measured in natural population (Lucky Strike--1700 m, Mid-Atlantic Ridge), and in in situ experimental conditions. B. azoricus individuals were moved away from the hydrothermal fluid to induce a loss of symbiont. Then after 6 days some mussels were brought back to the mussel bed to induce a re-acquisition of symbiotic bacteria. Results show the presence of 6 paralogs in B. azoricus. In absence of symbionts, 3 paralogs are up-regulated while others are not differentially expressed. Moreover the global activity of lysozyme is increasing with the loss of symbiont. All together these results suggest that lysozyme may play a crucial role in symbiont regulation. PMID:26882089

  14. Multiple I-Type Lysozymes in the Hydrothermal Vent Mussel Bathymodiolus azoricus and Their Role in Symbiotic Plasticity

    PubMed Central

    Detree, Camille; Chabenat, Apolline; Lallier, François H.; Satoh, Nori; Shoguchi, Eiichi; Tanguy, Arnaud; Mary, Jean

    2016-01-01

    The aim of this study was first to identify lysozymes paralogs in the deep sea mussel Bathymodiolus azoricus then to measure their relative expression or activity in different tissue or conditions. B. azoricus is a bivalve that lives close to hydrothermal chimney in the Mid-Atlantic Ridge (MAR). They harbour in specialized gill cells two types of endosymbiont (gram—bacteria): sulphide oxidizing bacteria (SOX) and methanotrophic bacteria (MOX). This association is thought to be ruled by specific mechanism or actors of regulation to deal with the presence of symbiont but these mechanisms are still poorly understood. Here, we focused on the implication of lysozyme, a bactericidal enzyme, in this endosymbiosis. The relative expression of Ba-lysozymes paralogs and the global anti-microbial activity, were measured in natural population (Lucky Strike -1700m, Mid-Atlantic Ridge), and in in situ experimental conditions. B. azoricus individuals were moved away from the hydrothermal fluid to induce a loss of symbiont. Then after 6 days some mussels were brought back to the mussel bed to induce a re-acquisition of symbiotic bacteria. Results show the presence of 6 paralogs in B. azoricus. In absence of symbionts, 3 paralogs are up-regulated while others are not differentially expressed. Moreover the global activity of lysozyme is increasing with the loss of symbiont. All together these results suggest that lysozyme may play a crucial role in symbiont regulation. PMID:26882089

  15. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... vent pipe or equivalent directly connected to the toilet drain within the distance allowed in § 3280... any other vent pipe. Vents for horizontal drains shall connect above the centerline of the drain... this section and as otherwise required by this standard. (b) Materials—(1) Pipe. Vent piping shall...

  16. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... for all changes in direction or size and where pipes are joined. The material and design of vent...) Size of vent piping—(1) Main vent. The drain piping for each toilet shall be vented by a 11/2 inch... toilet drain within the distance allowed in § 3280.611(c)(5), for 3-inch trap arms undiminished in...

  17. Dynamics of the 2014 Holuhraun fissure eruption analysed by video monitoring system

    NASA Astrophysics Data System (ADS)

    Witt, Tanja; Walter, Thomas R.

    2015-04-01

    Events on the volcanic system within the axial volcanic zones are linked to plate movements. The spreading and subsequent rifting of the crust take place at the plate boundary and occurs in distinct rifting episodes. These rifting episodes are characterized by earthquakes and volcanic eruptions within the central volcano or along fissures. For the subsurface structure of a volcanic system and the behavior of the magma plumbing system during major rifting episodes two contrasting models exists, (i) vertical feeding by a deep magma source or (ii) lateral feeding through a shallow magma chamber under the central volcano. The ongoing 2014 Holuhraun eruption is providing a unique opportunity to rigorously test the feeding paths of an active fissure eruption. Here we employ video images to analyse the height and velocity variation of the lava fountains at the Holuhraun eruption fissure. On the first day of the eruption we could set up in total five high resolution video cameras. With algorithms of photogrammetry and correlation analysis we interpret the behavior of the lava fountains. Results suggest a significal lateral propagation path of the dynamics of the active vents, and a lateral migration of the peaks and lows of distinct lava fountains. Although the correlation system can change episodically and sporadically, both the frequency of the lava fountains and the eruption and rest time between single fountains remain similar for adjacent lava fountains imply a controlling process in the magma feeder system itself. We interpret the results by a lateral magma and gas flow underlying and feeding the eruption fissure. Systematic recording and analysis of video data hence help to decide which magma plumbing system is more reliable. Additionally, the dataset allows us to compare the eruption behavior to seismic datasets.

  18. From fissure to fault: A model of fault growth in the Krafla Fissure System, NE Iceland

    NASA Astrophysics Data System (ADS)

    Bramham, Emma; Paton, Douglas; Wright, Tim

    2015-04-01

    Current models of fault growth examine the relationship of fault length (L) to vertical displacement (D) where the faults exhibit the classic fault shape of gradually increasing vertical displacement from zero at the fault tips to a maximum displacement (Dmax) at the middle of the fault. These models cannot adequately explain displacement-length observations at the Krafla fissure swarm, in Iceland's northern volcanic zone, where we observe that many of the faults with significant vertical displacements still retain fissure-like features, with no vertical displacement, along portions of their lengths. We have created a high resolution digital elevation model (DEM) of the Krafla region using airborne LiDAR and measured the displacement/length profiles of 775 faults, with lengths ranging from 10s to 1000s of metres. We have categorised the faults based on the proportion of the profile that was still fissure-like. Fully-developed faults (no fissure-like regions) were further grouped into those with profiles that had a flat-top geometry (i.e. significant proportion of fault length with constant throw), those with a bell-shaped throw profile and those that show regions of fault linkage. We suggest that a fault can most easily accommodate stress by displacing regions that are still fissure-like, and that a fault would be more likely to accommodate stress by linkage once it has reached the maximum displacement for its fault length. Our results demonstrate that there is a pattern of growth from fissure to fault in the Dmax/L ratio of the categorised faults and propose a model for this growth. These data better constrain our understanding of how fissures develop into faults but also provide insights into the discrepancy in D/L profiles from a typical bell-shaped distribution.

  19. Fissural volcanism, polygenetic volcanic fields, and crustal thickness in the Payen Volcanic Complex on the central Andes foreland (Mendoza, Argentina)

    NASA Astrophysics Data System (ADS)

    Mazzarini, F.; Fornaciai, A.; Bistacchi, A.; Pasquarè, F. A.

    2008-09-01

    Shield volcanoes, caldera-bearing stratovolcanoes, and monogenetic cones compose the large fissural Payen Volcanic Complex, located in the Andes foreland between latitude 35°S and 38°S. The late Pliocene-Pleistocene and recent volcanic activity along E-W trending eruptive fissures produced basaltic lavas showing a within-plate geochemical signature. The spatial distribution of fractures and monogenetic vents is characterized by self-similar clustering with well defined power law distributions. Vents have average spacing of 1.27 km and fractal exponent D = 1.33 defined in the range 0.7-49.3 km. The fractal exponent of fractures is 1.62 in the range 1.5-48.1 km. The upper cutoffs of fractures and vent fractal distributions (about 48-49 km) scale to the crustal thickness in the area, as derived from geophysical data. This analysis determines fractured media (crust) thickness associated with basaltic retroarc eruptions. We propose that the Payen Volcanic Complex was and is still active under an E-W crustal shortening regime.

  20. Anatomy and approaches along the cerebellar-brainstem fissures.

    PubMed

    Matsushima, Ken; Yagmurlu, Kaan; Kohno, Michihiro; Rhoton, Albert L

    2016-01-01

    OBJECT Fissure dissection is routinely used in the supratentorial region to access deeply situated pathology while minimizing division of neural tissue. Use of fissure dissection is also practical in the posterior fossa. In this study, the microsurgical anatomy of the 3 cerebellar-brainstem fissures (cerebellomesencephalic, cerebellopontine, and cerebellomedullary) and the various procedures exposing these fissures in brainstem surgery were examined. METHODS Seven cadaveric heads were examined with a microsurgical technique and 3 with fiber dissection to clarify the anatomy of the cerebellar-brainstem and adjacent cerebellar fissures, in which the major vessels and neural structures are located. Several approaches directed along the cerebellar surfaces and fissures, including the supracerebellar infratentorial, occipital transtentorial, retrosigmoid, and midline suboccipital approaches, were examined. The 3 heads examined using fiber dissection defined the anatomy of the cerebellar peduncles coursing in the depths of these fissures. RESULTS Dissections directed along the cerebellar-brainstem and cerebellar fissures provided access to the posterior and posterolateral midbrain and upper pons, lateral pons, floor and lateral wall of the fourth ventricle, and dorsal and lateral medulla. CONCLUSIONS Opening the cerebellar-brainstem and adjacent cerebellar fissures provided access to the brainstem surface hidden by the cerebellum, while minimizing division of neural tissue. Most of the major cerebellar arteries, veins, and vital neural structures are located in or near these fissures and can be accessed through them. PMID:26274986

  1. Visualization of three dimensional earth fissures in geological structure

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Yu, J.; Liu, Y.; Gong, H.; Chen, Y.; Chen, B.

    2015-11-01

    This paper proposes a new method for visualizing the earth fissures of geological structure in three dimensional (3-D) domains on the basis of the seismic data and features information of earth fissures. The seismic data were interpreted for obtaining the stratagraphic data with various lithological information and the depth of the earth fissures. The spatial distribution of the ground fissures including the dip, strike and width were digitalized on an ArcGIS platform. Firstly, the 3-D geological structure was rebuilt using the Generalized Tri-Prism (GTP) method which is a real solid method for displaying geological structures. The GTP method can reflect the inner material of the strata and can simulate complicated geological structures such as faults and stratagraphic pinch outs. The upper and lower surfaces of each stratum consist of Triangle Irregular Networks (TIN). The inner solid between the two surfaces are a series of triangular prisms. Secondly, since the width of the ground fissure gradually decreases with depth, multiple edge lines of the earth fissures on the bottom stratum surface are deduced on the basis of the fissure characteristics. Then, the model of the earth fissures consisting of a series of triangular pyramids can be constructed using these points and the edge lines. A cutting operation was carried out on the 3-D geological structure using this ground fissures model. If the surfaces of the ground fissures model intersects with the GTPs in the geological structure model, new GTPs were generated within the local regions. During this process, the topological relations between TIN, triangular prism and lines were reconstructed so that the visualization of ground fissures in the geological structure model is realized. This method can facilitate the mechanism for studying fissures and avoid the gaps between the fissure solid and the geological structure to accurately reflect their 3-D characteristics.

  2. Subsurface Gas Flow and Ice Grain Acceleration within Enceladus and Europa Fissures: 2D DSMC Models

    NASA Astrophysics Data System (ADS)

    Tucker, O. J.; Combi, M. R.; Tenishev, V.

    2014-12-01

    The ejection of material from geysers is a ubiquitous occurrence on outer solar system bodies. Water vapor plumes have been observed emanating from the southern hemispheres of Enceladus and Europa (Hansen et al. 2011, Roth et al. 2014), and N2plumes carrying ice and ark particles on Triton (Soderblom et al. 2009). The gas and ice grain distributions in the Enceladus plume depend on the subsurface gas properties and the geometry of the fissures e.g., (Schmidt et al. 2008, Ingersoll et al. 2010). Of course the fissures can have complex geometries due to tidal stresses, melting, freezing etc., but directly sampled and inferred gas and grain properties for the plume (source rate, bulk velocity, terminal grain velocity) can be used to provide a basis to constrain characteristic dimensions of vent width and depth. We used a 2-dimensional Direct Simulation Monte Carlo (DSMC) technique to model venting from both axi-symmetric canyons with widths ~2 km and narrow jets with widths ~15-40 m. For all of our vent geometries, considered the water vapor source rates (1027­ - 1028 s-1) and bulk gas velocities (~330 - 670 m/s) obtained at the surface were consistent with inferred values obtained by fits of the data for the plume densities (1026 - 1028 s-1, 250 - 1000 m/s) respectively. However, when using the resulting DSMC gas distribution for the canyon geometries to integrate the trajectories of ice grains we found it insufficient to accelerate submicron ice grains to Enceladus' escape speed. On the other hand, the gas distributions in the jet like vents accelerated grains > 10 μm significantly above Enceladus' escape speed. It has been suggested that micron-sized grains are ejected from the vents with speeds comparable to the Enceladus escape speed. Here we report on these results including comparisons to results obtained from 1D models as well as discuss the implications of our plume model results. We also show preliminary results for similar considerations applied to Europa

  3. Time-dependent chamber and vent conditions during explosive caldera-forming eruptions

    NASA Astrophysics Data System (ADS)

    Folch, A.; Martí, J.

    2009-04-01

    We use a modified version of the CPIUC model [Macedonio, G., Neri, A., Martí, J., Folch, A., 2005. Temporal evolution of flow conditions in sustained explosive eruptions, Journal of Volcanology and Geothermal Research, 143, 153-172] to simulate chamber and vent conditions during the different phases of a piston-like caldera-forming eruption. Our idealized caldera-forming scenario assumes an initial central-vent conduit that, after critical chamber decompression, migrates to a fissure-vent peripheral conduit(s). Further decompression leads to final piston-like subsidence which stops only after the virtual destruction of the magmatic reservoir. The simulations find that the pressure at the conduit entrance drops during the decompression phases at a rate depending on the conduit geometry, chamber volatile zonation and fragmentation threshold. The higher the volume contrast between the initial central-vent and the final peripheral fissure-vent conduits, the higher the pressure drop and the jump in the mass eruption rate. Pressure increases back to lithostatic during piston subsidence while some compressible magma remains within the chamber. Finally, during the later phase, pressure experiments a gentle increase or decrease depending on the balance between deposition of intra-caldera material and decrease in the contents of volatiles as deeper chamber levels are tapped.

  4. First hydrothermal active vent discovered on the Galapagos Microplate

    NASA Astrophysics Data System (ADS)

    Tao, C.; Li, H.; Wu, G.; Su, X.; Zhang, G.; Chinese DY115-21 Leg 3 Scientific Party

    2011-12-01

    The Galapagos Microplate (GM) lies on the western Gaplapagos Spreading Center (GSC), representing one of the classic Ridge-Ridge-Ridge (R-R-R) plate boundaries of the Nazca, Cocos, and Pacific plates. The presence of the 'black smoke' and hydrothermal vent community were firstly confirmed on the GSC. Lots of hydrothermal fields were discovered on the center and eastern GSC, while the western GSC has not been well investigated. During 17th Oct. to 9th Nov. 2009, the 3rd leg of Chinese DY115-21 cruise with R/V Dayangyihao has been launched along 2°N-5°S near equatorial East Pacific Rise (EPR). Two new hydrothermal fields were confirmed. One is named 'Precious Stone Mountain', which is the first hydrothermal field on the GM. The other is found at 101.47°W, 0.84°S EPR. The 'Precious Stone Mountain' hydrothermal field (at 101.49°W, 1.22°N) is located at an off-axial seamount on the southern GM boundary, with a depth from 1,450 to 1,700m. Hydrothermal fluids emitting from the fissures and hydrothermal fauna were captured by deep-tow video. Few mineral clasts of pyrite and chalcopyrite were separated from one sediment sample, but no sulfide chimney was found yet. Hydrothermal fauna such as alive mussels, crabs, shrimps, tubeworms, giant clams, as well as rock samples were collected by TV-Grab. The study of the seafloor classification with Simrad EM120 multi-beam echosounder has been conducted on the 'Precious Stone Mountain' hydrothermal field. The result indicates that seafloor materials around the hydrothermal field can be characterized into three types, such as the fresh lava, hydrothermal sediment, and altered rock.

  5. Parachute having improved vent line stacking

    NASA Technical Reports Server (NTRS)

    Hengel, John E.

    1994-01-01

    A parachute having an improved vent line stacking wherein the parachute is provided with a canopy having a central vent opening and a vent band secured to the canopy around the periphery of the vent opening, with a plurality of vent lines each lying on a diameter of the vent opening and having its ends secured to the vent band on opposite sides of the vent opening is described. The vent lines are sewed to the vent band in an order such that the end of a first vent line is sewed to the vent band at a starting point with the end of a second vent band then being sewed to the vent band adjacent to and counterclockwise from the first band. A third vent band is sewed to the vent band adjacent to and clockwise from the first band, with a fourth vent band being sewed to the vent band adjacent to and counterclockwise from the second vent band. It can be seen that, if the vent lines are numbered in the order of being sewed to the vent band, the odd numbered vent lines will run consecutively in a clockwise direction and the even numbered lines will run consecutively in a counterclockwise direction from the starting point. With this order of assembly, each and every vent line will be separated from adjacent vent lines by no more than one vent line in the center of the vent opening where the vent lines cross.

  6. [Fissures in biliary calculi. Personal contribution (author's transl)].

    PubMed

    Nano, M; Potenzoni, F; Camandona, M; Casalegno, P A

    1979-04-01

    In a series of 70 patients suffering from biliary lithiasis, the roentgenologic findings of fissures in the calculi was observed in 5 cases examined by means of cholecystography and in 7 cases who underwent cholangiocholecystography. Fissures were demonstrated 11 times in calculi after surgery. The "Mercedes-Benz" sign was never observed at the abdominal examination without contrast medium. The presence of fissures may be an additional sign in the radiologic diagnosis of biliary calculi, but its value is not determinant. PMID:550199

  7. [Sylvius (1614-1672) and his fissure].

    PubMed

    van Gijn, Jan; Gijselhart, Joost P

    2010-01-01

    Franciscus dele Boë, or Sylvius, was born into a family of French Huguenots who had moved to the province of Hessen. He studied medicine in Sedan, Leiden and Basle. He was a private teacher in anatomy in Leiden for some years, and while teaching he drew the attention of his students to the long fissure on either side of the cerebral surface. He practised successfully as a physician in Amsterdam from 1641 onwards, until he was recalled to the chair of medicine in Leiden in 1658. He emphasized the role of chemical processes in the human body (iatrochemistry). PMID:20699035

  8. Corrections of surface fissure effect on apparent resistivity measurements

    NASA Astrophysics Data System (ADS)

    Gance, J.; Sailhac, P.; Malet, J.-P.

    2015-02-01

    Electrical resistivity tomography (ERT) is a useful tool to detect and track water flow paths in the subsoil. However, measurements are strongly affected by subsurface heterogeneities such as fissures of different sizes and genesis (shrinking-swelling, macropores and deformation). In this work, we focus on surface fissures characterized by dimensions lower than the interelectrode spacing and correct their effect on apparent resistivity pseudo-sections by incorporating fissure geometry in the topography. We show that fissures with depths greater than 0.10 times the interelectrode spacing for a dipole-dipole array and equal to 0.16 for the gradient array and the Wenner-Schlumberger arrays create significant anomalies (greater than 5 per cent) in the pseudo-section. Surface fissure widths and dip angles have little effect with respect to the fissure depths which can increase the apparent resistivity up to 200 per cent. The clogging of the fissures with water or soil material decreases the anomaly effect linearly with the percentage of filling. The correction of apparent resistivity values is possible for relatively simple fissure geometries and only requires a manual survey of the surface fissures. It allows to improve the quality of the inverted resistivity section by mitigating the inversion artefacts and therefore a better interpretation.

  9. Organogenesis of mild ocular coloboma in FLS mice: failure of basement membrane disintegration at optic fissure margins.

    PubMed

    Tsuji, Naho; Kita, Katsutoshi; Ozaki, Kiyokazu; Narama, Isao; Matsuura, Tetsuro

    2012-01-01

    Fatty Liver Shionogi (FLS) mice have been shown to develop a hereditary disorder characterized by localized retinochoroidal defects of the ventral fundus very similar to human typical ocular coloboma without microphthalmia. The objective of this study was to determine when and how the failure of the optic fissure closure occurs, and to clarify the disturbed mechanism of basement membrane disintegration during embryonal stage in FLS mice. Fetuses at day 11.5-15.5 of gestation were obtained from dams of FLS and BALB/c strain of mice. Coronal serial sections through the eye were examined by light and electron microscopy. The sections were followed by observation of the basement membrane using reaction with periodic acid-Schiff (PAS) reagent and immunohistochemical staining with anti-Laminin and anti-Type IV collagen antibodies. Both optic fissure margins closely approached each other up to GD 11.5 in all FLS and BALB/c embryos. The inner and outer layers of the optic cup did not normally fuse at midlenticular levels of the optic fissure in almost 70% of FLS fetuses by GD 15.5, whereas both margins were completely fused in all BALB/c fetuses of the same gestational day. In the FLS fetuses at GD 12.5, rolling on one side of fissure margins and consequent asymmetry were observed at the ventral optic fissure. The basement membrane persisted after the close contact of both sides of the fissure margins during GD 11.5 and 15.5. Ultrastructurally, the basal lamina was not disintegrated and mesenchymal cells intervened between the two neuroepithelial layers, resulting in complete separation of both fissure margins at GD 13.0. It is highly probable that the disturbed basement membrane disintegration right before optic fissure closure causes mild ocular coloboma without microphthalmia in FLS mice. PMID:22182670

  10. Distributed Computing for Seismic Data Retrieval using FISSURES DHI Client FMI Implimented from MatSeis 1.9

    NASA Astrophysics Data System (ADS)

    Hart, D. M.; Li, Q.; Creager, K. C.; Ning, R.; Crotwell, H. P.; Zuzlewski, S.; Hellman, S. B.; Schoch, K. S.; Laughbon, C. J.; Stromme, S. R.

    2004-12-01

    Three software development efforts have recently combined to allow a seamless method for obtaining data from the IRIS DMC over the Internet and analyzing it in MATLAB. During the past few years IRIS has constructed the initial framework and definitions for FISSURES servers and Data Handling Interface (DHI) clients. FISSURES uses the distributed computing language Common Object Request Broker Architecture (CORBA), which allows software systems to work across the Internet in a platform independent and computer-language neutral manner. Starting from the FISSURES object model three seismic services have been defined: event, network and seismogram. From these three object types a DHI client is used to access information through FISSURES services. Using the University of Washington developed FISSURES-Matlab-Interface (FMI) DHI client, all three FISSURES objects can be accessed via the Internet and downloaded into local MATLAB objects, allowing access to earthquake event catalogs, seismograms, network and instrument information. The DHI client FMI can be implemented from MatSeis. MatSeis, developed at Sandia National Laboratory, is a MATLAB based, Graphical User Interface (GUI) controlled software package with seismic data visualization, signal processing, and database importing and exporting capabilities, to list just a few. In this poster, we will discuss the seismic data retrieval currently prototyped for the IRIS DMC, as well as the planned connections to the Northern California Earthquake Data Center (NCEDC), Southern California Earthquake Data Center (SCEDC), and South Carolina Earth Physics Project (SCEPP) data center.

  11. Coil spring venting arrangement

    DOEpatents

    McCugh, R.M.

    1975-10-21

    A simple venting device for trapped gas pockets in hydraulic systems is inserted through a small access passages, operated remotely, and removed completely. The device comprises a small diameter, closely wound coil spring which is pushed through a guide temporarily inserted in the access passage. The guide has a central passageway which directs the coil spring radially upward into the pocket, so that, with the guide properly positioned for depth and properly oriented, the coil spring can be pushed up into the top of the pocket to vent it. By positioning a seal around the free end of the guide, the spring and guide are removed and the passage is sealed.

  12. Integral valve provides automatic relief and remote venting

    NASA Technical Reports Server (NTRS)

    Gilmore, R. F.

    1969-01-01

    In-line, pilot-operated, differential area, poppet type valve provides both automatic relief of a tank at a precise over-pressure and remote control of tank venting. Relief and vent operations are separate functions incorporated in an integral valve package.

  13. Overview of the 2012-13 basaltic fissure eruption of Tolbachik, Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Belousov, Alexander; Belousova, Marina; Edwards, Benjamin; Volynetz, Anna; Melnikov, Dmitry; Senyukov, Sergey

    2014-05-01

    On 27 November 2012 a short-lived swarm of shallow (<10 km) earthquakes marked the onset of a new eruption from the Tolbachik volcanic complex, in east-central Kamchatka, Russia. The 3.5-km-long radial eruptive fissure opened on the south flank between 1500-2000 m a.s.l. Lava fountaining from multiple small vents ceased after several days and the eruption continued from vents at the southern end of the fissure. Almost continuous lava fountains up to 200 m high issued from a small lava lake located inside the broad, open crater of the largest cinder cone. While explosive activity was rather mild, initial discharge of lava was very high (up to 400 m3/s) and by the end of December 'a'a lava flows had travelled up to 17 km from the vent. SiO2 concentrations for the plagioclase-phyric lava were 54 wt.%, but then decreased to 52 wt.%. In January 2013 lava was transported through a system of lava tubes 1 km long and up to 5 m wide. From tube exit points it propagated in the form of channelized lava streams (velocities 1-3 m/s; discharge rates 30-50 m3/s); on lower slopes of the volcano it propagated mostly as 'a'a flows. Lava channels were frequently dammed by floating clinker and accretionary lava balls, which caused flooding of proximal areas by ropy/shelly/slabby pahoehoe lavas. Locally small volumes of lava were extruded through the upper surfaces and lateral levees of 'a'a lava to form very slowly inflating entrail pahoehoe lava lobes. Starting in mid-February the average intensity of the eruption gradually declined, with sporadic bursts in February and April. By May discharge rates of lava had decreased to approximately 15 m3/s and most of lava started to flow as entrail pahoehoe. By the beginning of June the volume of erupted products (dominantly lavas) reached 0.52km3. The effusion of lava continued until the end of August, when the lava lake in the crater of the active cinder cone became inactive. Weak strombolian outbursts from 1-3 small vents on the bottom of

  14. Vent Relief Valve Test

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Shown is the disassembly, examination, refurbishment and testing of the LH2 ( liquid hydrogen) and LOX (liquid oxygen) vent and relief valves for the S-IVB-211 engine stage in support of the Constellation/Ares project. This image is extracted from high definition video and is the highest resolution available.

  15. Reconstructing recent basaltic fissure eruptions in the Afar Depression, Ethiopia, using satellite imagery

    NASA Astrophysics Data System (ADS)

    Barnie, T. D.; Ferguson, D. J.; Oppenheimer, C.

    2009-12-01

    Since 2005, there have been numerous dike intrusions in the Manda-Hararo rift segment in central Afar, Ethiopia, as part of an on-going rifting event similar to that which occurred at Krafla, Iceland between 1975 and 1984. Two of the dikes have been associated with basaltic fissure eruptions, in August 2007 and in June 2009. A large fissure eruption also occurred in the Erta ‘Ale volcanic range in northern Afar in November 2008, which may be related to the activity further south. These eruptions took place in remote areas and lasted only a few days, making field observation almost impossible. We must therefore rely on the geomorphology and geochemistry of the erupted deposits, and syn-eruption satellite observations of thermally emitted radiance and gas emissions to reconstruct the evolution of these eruptions. Reconstruction of the eruptions is important for i) understanding the relationship between dike intrusion and fissure eruption dynamics ii) understanding the relationship between eruption dynamics and the resulting deposits, iii) interpreting the deposits of pre-historic eruptions from previous rifting events, and iv) estimating the hazard posed to the local population by further activity. In this study we use pre- and post-eruption high resolution ASTER and ALI images to map the morphology of the erupted material, and SEVIRI and MODIS time series of the eruptions to track evolution of the vent dynamics and lava flows. These datasets are augmented by oblique aerial and ground based photographic and FLIR surveys of the cooling lava flows and tephra. ASTER and ALI images are also used to map older erupted materials, which allow us to compare this rifting event with previous events to anticipate future activity.

  16. Remote sensing and petrological observations on the 2012-2013 fissure eruption at Tolbachik volcano, Kamchatka: Implications for reconstruction of the eruption chronology

    NASA Astrophysics Data System (ADS)

    Melnikov, Dmitry; Volynets, Anna O.

    2015-12-01

    We present a reconstruction of the chronological sequence of events that took place during the first days of the 2012-2013 Tolbachik fissure eruption using petrological data and remote sensing methods. We were forced to use this approach because bad weather conditions did not allow direct observations during the first two days of the eruption. We interpreted infrared images from the scanning radiometer VIIRS Suomi NPP and correlated the output with the results of the geochemical study, including comparison of the ash, deposited at the period from 27 to 29 November, with the samples of lava and bombs erupted from the Menyailov and Naboko vents. We argue that the compositional change observed in the eruption products (the decrease of SiO2 concentration and K2O/MgO ratio, increase of MgO concentration and Mg#) started approximately 24 h after the eruption began. At this time the center of activity moved to the southern part of the fissure, where the Naboko group of vents was formed; therefore, this timeframe also characterizes the timing of the Naboko vent opening. The Naboko group of vents remained active until the end of eruption in September 2013.

  17. Monitoring an eruption fissure in 3D: video recording, particle image velocimetry and dynamics

    NASA Astrophysics Data System (ADS)

    Witt, Tanja; Walter, Thomas R.

    2015-04-01

    The processes during an eruption are very complex. To get a better understanding several parameters are measured. One of the measured parameters is the velocity of particles and patterns, as ash and emitted magma, and of the volcano itself. The resulting velocity field provides insights into the dynamics of a vent. Here we test our algorithm for 3 dimensional velocity fields on videos of the second fissure eruption of Bárdarbunga 2014. There we acquired videos from lava fountains of the main fissure with 2 high speed cameras with small angles between the cameras. Additionally we test the algorithm on videos from the geyser Strokkur, where we had 3 cameras and larger angles between the cameras. The velocity is calculated by a correlation in the Fourier space of contiguous images. Considering that we only have the velocity field of the surface smaller angles result in a better resolution of the existing velocity field in the near field. For general movements also larger angles can be useful, e.g. to get the direction, height and velocity of eruption clouds. In summary, it can be stated that 3D velocimetry can be used for several application and with different setup due to the application.

  18. Fine Mapping and Introgressing a Fissure Resistance Locus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice (Oryza sativa L.) kernel fissuring is a major concern of both rice producers and millers. Fissures are small cracks in rice kernels that increase breakage among kernels when transported or milled, which decrease the value of processed rice. This study employed molecular gene tagging methods to ...

  19. On Small Disturbance Ascent Vent Behavior

    NASA Technical Reports Server (NTRS)

    Woronowicz, Michael

    2015-01-01

    As a spacecraft undergoes ascent in a launch vehicle, its ambient pressure environment transitions from one atmosphere to high vacuum in a matter of a few minutes. Venting of internal cavities is necessary to prevent the buildup of pressure differentials across cavity walls. These pressure differentials are often restricted to low levels to prevent violation of container integrity. Such vents usually consist of fixed orifices, ducts, or combinations of both. Duct conductance behavior is fundamentally different from that for orifices in pressure driven flows governing the launch vehicle ascent depressurization environment. Duct conductance is governed by the average pressure across its length, while orifice conductance is dictated by a pressure ratio. Hence, one cannot define a valid equivalent orifice for a given duct across a range of pressure levels. This presentation discusses development of expressions for these two types of vent elements in the limit of small pressure differentials, explores conditions for their validity, and compares their features regarding ascent depressurization performance.

  20. Instrumentation and measurement of airflow and temperature in attics fitted with ridge and soffit vents

    SciTech Connect

    Romero, M.I.; Brenner, R.J.

    1998-12-31

    This study established a research facility where airflow velocities, temperature, and differential pressures could be measured at the ridge of an attic. Following the construction of a test building, sensors were constructed, calibrated, and installed inside the attic. Paired tests were performed for three different ridge vent treatments; two were rolled type vents and one was a baffled vent. When both attics were fitted with the same ridge vent, the airspeed and differential pressure profiles at the ridge were very similar for both attics, indicating that any observed differences in airspeed and differential pressure were caused by the ridge vent treatment used. The baffled vent and rolled vents were then installed on the ridge of the west and east attics, respectively. The data demonstrated that the baffled ridge vent provided a minimum of twice the ridge airspeed of the rolled vents, when all wind conditions were considered. On the day selected to study the direction of the airflows at the ridge, the baffled vent had airflow speeds at the ridge similar to the rolled vent without fabric backing. The baffled vent allowed air to come out of the attic through both sides of the ridge (negative differential pressures on both sides), while the rolled vent without fabric backing caused air to enter through the south side of the ridge and exit through the north side (positive differential pressure on the south side and negative differential pressure on the north), in effect short-circuiting the vent. The fabric-backed rolled vent allowed attic air to come out of the attic through both sides of the ridge, as did the baffled vent, but the airspeed was slower. The baffled vent was the one with the highest airspeed at the ridge and also had both sides of the vent under negative differential pressure, providing the most effective ventilation.

  1. Numerical simulation of earth fissures due to groundwater withdrawal

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Zhang, Y.; Wu, J.; Yu, J.; Gong, X.

    2015-11-01

    Excessive groundwater withdrawal can cause land subsidence and earth fissures. The initiation and propagation of earth fissures are related to tensile failure and crack propagation in soils. Based on fracture mechanics, the crack band model (CBM), one of the smear crack models which is relatively easy to construct and convenient to be integrated into standard finite element codes is used in this paper. The calculated results of CBM are less dependent on the sizes of finite elements. The model was applied to simulate the formation and propagation of earth fissures in the hydrostratigraphic units with a bedrock ridge. The simulated positions and patterns of earth fissures coincide with field observations, suggesting that the modeling approach is adept to simulate the initiation and propagation of earth fissures due to groundwater withdrawal.

  2. Pearl in interhemispheric fissure: A rare phenomenon.

    PubMed

    Agarwal, Vivek; Vijayan, Abhishek; Velho, Vernon; Mally, Rahul

    2012-10-01

    Epidermoid cysts (Keratin pearls) are benign congenital lesions, found commonly in cerebello-pontine angle, suprasellar cistern, sylvian cistern, pineal region, but they are very rare in interhemispheric fissure. Approaching these lesions are challenging to neurosurgeons because of narrow and deep fissure with surrounding vital structures. The present study constitutes an analysis of interhemispheric epidermoid managed at our hospital in last 10 years (Jan 2001-Dec 2010). Total 187 cases of intracranial epidermoid operated in our institute; eight of them were interhemispheric epidermoid making about 4.27% of all epidermoids. The patients were presented with seizures (50%), headache (37%), and weakness (25%). On examination, the common findings were decreased Mini mental score (MMSE) in 50%, motor deficit in 25%, and decreased visual acuity in 25% of cases. All patients underwent craniotomy across the midline as per the location of the lesions. In seven patients, tumors were resected by interhemispheric approach but in one by transcortical. Lesion were excised with microscope and endoscopic assistance with measures to prevent spillage of epidermoid tissue while excision. Post excision tumor bed was irrigated with hydrocortisone diluted saline. All patients except one improved after surgery and non-developed chemical meningitis. One patient of parietal interhemispheric epidermoid with transcortical approach developed weakness in immediate post-operative period. Patients were followed for average 6.8 year without any recurrence. Interhemispheric epidermoids are rare tumors. Achieving safe complete excision without spillage is surgical goal to prevent chemical meningitis and recurrence. Endoscope assists in achieving complete excision so decrease incidence of chemical meningitis and recurrence. PMID:23559996

  3. Methods for monitoring land subsidence and earth fissures in the Western USA

    NASA Astrophysics Data System (ADS)

    Fergason, K. C.; Rucker, M. L.; Panda, B. B.

    2015-11-01

    Depletion of groundwater resources in many deep alluvial basin aquifers in the Western USA is causing land subsidence, as it does in many regions worldwide. Land subsidence can severely and adversely impact infrastructure by changing the ground elevation, ground slope (grade) and through the development of ground cracks known as earth fissures that can erode into large gullies. Earth fissures have the potential to compromise the foundations of dams, levees, and other infrastructure and cause failure. Subsequent to an evaluation of the overall subsidence experienced in the vicinity of subsidence-impacted infrastructure, a detailed investigation to search for earth fissures, and design and/or mitigation of potentially effected infrastructure, a focused monitoring system should be designed and implemented. Its purpose is to provide data, and ultimately knowledge, to reduce the potential adverse impacts of land subsidence and earth fissure development to the pertinent infrastructure. This risk reduction is realized by quantifying the rate and distribution of ground deformation, and to detect ground rupture if it occurs, in the vicinity of the infrastructure. The authors have successfully designed and implemented monitoring systems capable of quantifying rates and distributions of ground subsidence and detection of ground rupture at multiple locations throughout the Western USA for several types of infrastructure including dams, levees, channels, basins, roadways, and mining facilities. Effective subsidence and earth fissure monitoring requires understanding and quantification of historic subsidence, estimation of potential future subsidence, delineation of the risk for earth fissures that could impact infrastructure, and motivation and resources to continue monitoring through time. A successful monitoring system provides the means to measure ground deformation, grade changes, displacement, and anticipate and assess the potential for earth fissuring. Employing multiple

  4. D0 Vent Stacks

    SciTech Connect

    Fuerst, J.D.; /Fermilab

    1988-01-22

    There are two nitrogen/argon exhaust headers in the D0 cryogenic piping system, one for the liquid argon dewar and another for the three argon calorimeters. These headers serve two functions, venting both nitrogen exhaust from the cooling loops and cold argon gas should any argon vessel blow a relief. These headers are vacuum jacketed until they exit the building. At that point, uninsulated exhaust stacks direct the flow into the atmosphere. This note deals with the these stacks.

  5. Spacecraft Compartment Venting

    NASA Technical Reports Server (NTRS)

    Scialdone, John J.

    1998-01-01

    At various time concerns have been expressed that rapid decompressions of compartments of gas pockets and thermal blankets during spacecraft launches may have caused pressure differentials across their walls sufficient to cause minor structural failures, separations of adhesively-joined parts, ballooning, and flapping of blankets. This paper presents a close form equation expressing the expected pressure differentials across the walls of a compartment as a function of the external to the volume pressure drops, the pressure at which the rates occur and the vent capability of the compartment. The pressure profiles measured inside the shrouds of several spacecraft propelled by several vehicles and some profiles obtained from ground vacuum systems have been included. The equation can be used to design the appropriate vent, which will preclude excessive pressure differentials. Precautions and needed approaches for the evaluations of the expected pressures have been indicated. Methods to make a rapid assessment of the response of the compartment to rapid external pressure drops have been discussed. These are based on the evaluation of the compartment vent flow conductance, the volume and the length of time during which the rapid pressure drop occurs.

  6. Staged venting of fuel cell system during rapid shutdown

    DOEpatents

    Clingerman, Bruce J.; Doan, Tien M.; Keskula, Donald H.

    2002-01-01

    A venting methodology and system for rapid shutdown of a fuel cell apparatus of the type used in a vehicle propulsion system. H.sub.2 and air flows to the fuel cell stack are slowly bypassed to the combustor upon receipt of a rapid shutdown command. The bypass occurs over a period of time (for example one to five seconds) using conveniently-sized bypass valves. Upon receipt of the rapid shutdown command, the anode inlet of the fuel cell stack is instantaneously vented to a remote vent to remove all H.sub.2 from the stack. Airflow to the cathode inlet of the fuel cell stack gradually diminishes over the bypass period, and when the airflow bypass is complete the cathode inlet is also instantaneously vented to a remote vent to eliminate pressure differentials across the stack.

  7. Staged venting of fuel cell system during rapid shutdown

    DOEpatents

    Keskula, Donald H.; Doan, Tien M.; Clingerman, Bruce J.

    2004-09-14

    A venting methodology and system for rapid shutdown of a fuel cell apparatus of the type used in a vehicle propulsion system. H.sub.2 and air flows to the fuel cell stack are slowly bypassed to the combustor upon receipt of a rapid shutdown command. The bypass occurs over a period of time (for example one to five seconds) using conveniently-sized bypass valves. Upon receipt of the rapid shutdown command, the anode inlet of the fuel cell stack is instantaneously vented to a remote vent to remove all H.sub.2 from the stack. Airflow to the cathode inlet of the fuel cell stack gradually diminishes over the bypass period, and when the airflow bypass is complete the cathode inlet is also instantaneously vented to a remote vent to eliminate pressure differentials across the stack.

  8. Study of the deformation mechanism of the Gaoliying ground fissure

    NASA Astrophysics Data System (ADS)

    Cheng, G.; Wang, H.; Luo, Y.; Guo, H.

    2015-11-01

    The Gaoliying ground fissure in Beijing has caused building cracking and road damage, and has seriously influenced city construction. Based on investigations and trenching, the influences of the fault and the variation of groundwater levels on the formation mechanism of the Gaoliying ground fissure were investigated by using FLAC3D. The results indicated that (1) the surface location of Gaoliying fissure is controlled by the underlying normal fault activity, and over pumping further exacerbates development of the ground fissure; (2) when the groundwater level declines, obvious differential settlement occurs at both sides of the ground fissure, in which greater settlement occurs in the vicinity of the hanging wall, the greater the distance from the hanging wall, the smaller the ground subsidence, however smaller ground subsidence occurs in the vicinity of the footwall, the greater the distance from the footwall, the greater the ground subsidence; (3) the vertical velocity of the ground fissure triggered by the fault activity and groundwater decline ranges from 15.5 to 18.3 mm a-1, which is basically in line with the monitoring data. The fault activity contributes about 28-39 %, and the groundwater contributes about 61-72 % to the deformation of the ground fissure, respectively.

  9. Airbag vent valve and system

    NASA Technical Reports Server (NTRS)

    Peterson, Leslie D. (Inventor); Zimmermann, Richard E. (Inventor)

    2001-01-01

    An energy absorbing airbag system includes one or more vent valve assemblies for controlling the release of airbag inflation gases to maintain inflation gas pressure within an airbag at a substantially constant pressure during a ride-down of an energy absorbing event. Each vent valve assembly includes a cantilever spring that is flat in an unstressed condition and that has a free end portion. The cantilever spring is secured to an exterior surface of the airbag housing and flexed to cause the second free end portion of the cantilever spring to be pressed, with a preset force, against a vent port or a closure covering the vent port to seal the vent port until inflation gas pressure within the airbag reaches a preselected value determined by the preset force whereupon the free end portion of the cantilever spring is lifted from the vent port by the inflation gases within the airbag to vent the inflation gases from within the airbag. The resilience of the cantilever spring maintains a substantially constant pressure within the airbag during a ride-down portion of an energy absorbing event by causing the cantilever spring to vent gases through the vent port whenever the pressure of the inflation gases reaches the preselected value and by causing the cantilever spring to close the vent port whenever the pressure of the inflation gases falls below the preselected value.

  10. Visual Observations and Geologic Settings of the Newly-Discovered Black Smoker Vent Sites Across the Galapagos Ridge-Hotspot Intersection

    NASA Astrophysics Data System (ADS)

    Anderson, P.; Haymon, R.; MacDonald, K.; White, S.

    2006-12-01

    Nearly one-fifth of the global mid-ocean ridge is hotspot-affected, yet very little is known about how hotspots affect quantity and distribution of high-temperature hydrothermal vents along the ridge. During the 2005-06 GalAPAGoS expedition, acoustic and plume sensor surveys were conducted across the Galapagos ridge- hotspot intersection, lon. 94.5ºW- lon. 89.5ºW, to map fine scale geologic features and locate hydrothermal plumes emanating from the ridge crest. Where significant plumes were detected, the Medea fiber-optic camera sled was used successfully to find and image high-temperature vents on the seafloor. With Medea we discovered and imaged the first active and recently extinct black smokers known along the entire Galapagos Spreading Center (GSC), and documented the geologic setting of these vents. The Medea survey imaged numerous inactive vents as well as 3 active high-temperature vent fields along the ridge at 94º 04.5'W (Navidad Site), 91º56.2'W (Iguanas Site) and 91º54.3'W (Pinguinos Site). Two recently extinct vent fields also were identified at 91º23.4'-23.7'W and 91º13.8'W. All of the high-temperature vent sites that we identified along the GSC are found above relatively shallow AMC reflectors and are located in the middle 20% of ridge segments. Without exception the vent sites are located along fissures atop constructional axial volcanic ridges (AVR's) composed of relatively young pillow basalts. In some cases, the vents were associated with collapses adjacent to the fissures. The fissures appear to be eruptive sources of the pillow lavas comprising the AVR's. Video images of the chimneys show mature, cylindrical structures, up to 14m high; little diffuse flow; few animals; and some worm casts and dead clam shells, suggesting prior habitation. We conclude that distribution of the vents is controlled by magmatic processes, (i.e., by locations of shallow AMC magma reservoirs and eruptive fissures above dike intrusions), and that there is

  11. Tapped-Hole Vent Path

    NASA Technical Reports Server (NTRS)

    Chandler, J. A.

    1983-01-01

    Long helical vent path cools and releases hot pyrotechnical gas that exits along its spiraling threads. Current design uses 1/4-28 threads with outer diameter of stud reduced by 0.025 in. (0.62 mm). To open or close gassampler bottle, pyrotechnic charges on either one side or other of valve cylinder are actuated. Gases vented slowly over long path are cool enough to present no ignition hazard. Vent used to meter flow in refrigeration, pneumaticcontrol, and fluid-control systems by appropriately adjusting size and length of vent path.

  12. Calcified gallstone fissures: the reversed Mercedes Benz sign.

    PubMed

    Strijk, S P

    1987-01-01

    This article describes the occurrence of an unusual radiating pattern of calcification in the center of large radiolucent gallstones. The radiographic findings are attributed to calcium deposition within the fissures of biliary calculi. PMID:3556975

  13. Two Vent Fields Discovered at the Ultraslow Spreading Arctic Ridge System

    NASA Astrophysics Data System (ADS)

    Pedersen, R. B.; Thorseth, I. H.; Hellevang, B.; Schultz, A.; Taylor, P.; Knudsen, H. P.; Steinsbu, B. O.

    2005-12-01

    Two high-temperature vent fields were discovered at the Mohns Ridge during an expedition with the Norwegian research vessel "G.O. Sars" in July 2005. Both vent fields are located within the southernmost segment of the Mohns Ridge approximately 50 km north of the West Jan Mayen Fracture Zone. Water depths along this segment range from 3800 meters close to the fracture zone to ~500 meters at the segment centre where the vent fields are located. The largest field - named "Gallionella Garden" - is situated within a rift graben where high- and low-temperature venting occurs along ridge-parallel normal faults and fissures. Presently we have documented high- and low-temperature venting along more then 2 km of the fault and fissure system in the area. The high-temperature venting takes place at around 550 mbsl at the base of a 100 meter high fault wall and was traced ~500 meters along strike. The field consists of at least 10 major vent sites, each composed of multiple chimneys that are up to 5-10 meters tall. There are also large areas of diffuse flow. The temperature of the vent fluids was measured to be above 260°C at a chimney orifice. This is at the boiling point of seawater at these water depths, and gas bubbling was observed at several of the vent sites. A sample of the top of a chimney consists of anhydrite, barite, sphalerite and pyrite. Outside the high-temperature vent area mounds of ferric iron are abundant. Such deposits have presently been traced along ~2 km of the faults and fissure system in the area. The deposits are predominantly made up of branching and twisted stalks comparable to those formed by the iron oxidizing bacteria Gallionella ferruginea showing that the precipitation is mediated by microbial activity. The temperatures below the upper crust of a mound were measured to be one degree above the ambient water temperature. The Fe-oxyhydroxides show Nd-isotope compositions similar to the basaltic crust and Sr-isotope compositions close to that of

  14. Safe venting of hydrogen

    SciTech Connect

    Stewart, W.F.; Dewart, J.M.; Edeskuty, F.J.

    1990-01-01

    The disposal of hydrogen is often required in the operation of an experimental facility that contains hydrogen. Whether the vented hydrogen can be discharged to the atmosphere safely depends upon a number of factors such as the flow rate and atmospheric conditions. Calculations have been made that predict the distance a combustible mixture can extend from the point of release under some specified atmospheric conditions. Also the quantity of hydrogen in the combustible cloud is estimated. These results can be helpful in deciding of the hydrogen can be released directly to the atmosphere, or if it must be intentionally ignited. 15 refs., 5 figs., 2 tabs.

  15. Tornado protection by venting

    SciTech Connect

    Cavanagh, C.A.

    1987-01-01

    The purpose of this paper is to demonstrate the ability to protect a modern nuclear power plant from the effects of a tornado by the use of a system of venting in all safety-related structures outside of the containment. The paper demonstrates this by presenting a method of analysis and of equipment selection that fully complies with the intent and the letter of applicable federal regulatory guides. A report of an actual tornado in the City of Kalamazoo, Michigan, suggests that the concept of sealing a plant during a tornado may not always be applicable.

  16. Differential compaction mechanism for earth fissures near Casa Grande, Arizona.

    USGS Publications Warehouse

    Jachens, R.C.; Holzer, T.L.

    1982-01-01

    Precise gravity measurements indicate that earth fissures or tension cracks caused by ground-water withdrawal within a 10km2 area SE of Casa Grande are associated with relief on the buried interface between the alluvial aquifer and underlying bedrock. These relations suggest that the fissures are forming in response to localized differential compaction caused by localized variations of aquifer-system thickness. -from Authors

  17. Vented gaseous deflagrations modelling of hinged inertial vent covers.

    PubMed

    Molkov, V V; Grigorash, A V; Eber, R M; Makarov, D V

    2004-12-10

    The model of explosion pressure build up in enclosures with inertial vent covers and the CINDY code implementing the model are validated against experiments by Hochst and Leuckel (1998) in a 50 m3 vessel with a pair of ceiling-mounted upwards-opening hinged doors in a 'butterfly' configuration with surface densities of 73 and 124 kg/m2 under conditions of initially quiescent and turbulent mixtures. The model and the code are further validated against an experiment by Zalosh (1978) in a 33.5 m3 room-like enclosure with a pair of wall-mounted rectangular doors, in a parallel configuration, each hinged at its bottom edge with a surface density of 23.1 kg/m2 and initially quiescent mixture. A formula for the torque acting upon a rotating venting door is derived under conditions of vent cover jet formation. The vent cover jet effect decreases the torque three times compared to an elementary approach valid at the start of vent cover movement. It is demonstrated that, similar to translating vent covers, the vent cover jet effect is crucial for prediction of interdependent vent cover displacement in time and pressure transients. PMID:15561358

  18. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Vents and venting. 3280.611 Section 3280.611 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued) OFFICE OF ASSISTANT SECRETARY FOR HOUSING-FEDERAL HOUSING COMMISSIONER, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT MANUFACTURED...

  19. Implications of ground-deformation measurements across earth fissures in subsidence areas in the southwestern USA

    USGS Publications Warehouse

    Holzer, Thomas L.

    2010-01-01

    Ground deformation was monitored at earth fissures in areas of land subsidence induced by groundwater extraction in the southwestern United States. The ground deformation is consistent with the mechanism that fissures are caused by horizontal strains generated by bending of overburden in response to localized differential compaction. Subsidence profiles indicated that localized differential subsidence occurred across the fissures and that maximum convex-upward curvature was at the fissure. The overall shape of the profile stayed similar with time, and maximum curvature remained stationary at the fissure. Horizontal displacements were largest near the fissure, and generally were small to negligible away from the fissure. Maximum tensile horizontal strains were at the fissure and coincided with maximum curvature in the subsidence profiles. Horizontal tensile strain continued to accumulate at fissures after they formed with rates of opening ranging from 30 to 120 microstrain/year at fissures in Arizona.

  20. Predominant cultivable microflora of human dental fissure plaque.

    PubMed Central

    Theilade, E; Fejerskov, O; Karring, T; Theilade, J

    1982-01-01

    Plaque developed in 10 occlusal fissures from unerupted third molars during implantation for 200 to 270 days in lower molars of dental students was studied. To characterize the predominant cultivable flora, 592 isolates (51 to 67 from each fissure) were subcultured from anaerobic roll tubes. Twenty-eight of the isolates were lost. Streptococci constituted 8 to 86% (median, 45%) of the isolates, Streptococcus mutans constituted 0 to 86% (median, 25%) and S. sanguis constituted 0 to 15% (median, 1%). A few isolates of "S. mitior" and "S. milleri" were found, but no S. salivarius. Staphylococci made up 0 to 23% (median, 9%). Gram-positive rods constituted 6 to 59% (median, 35%). Of these, 0 to 46% (median, 18%) were Actinomyces naeslundii and A. viscosus, but no anaerobic actinomyces were isolated. Arachnia and propionibacteria made up small proportions, lactobacilli were isolated from two fissures, constituting 10 and 29%, and eubacteria were isolated from one fissure (27%). Gram-negative cocci made up 0 to 46% (media, 4%). Only two isolates of gram-negative rods were found, both facultative anaerobes. Although 8 of the 10 fissures had large proportions of S. mutans, lactobacilli, or both, no caries was found even with microradiography. The large individual variation probably reflects differences in initial colonization from saliva and in growth conditions in each fissure. PMID:7095858

  1. Battery vent valve

    SciTech Connect

    McCartney, C.P. Jr.; Montgomery, C.C.; Meadows, C.A.; Cole, B.A.

    1988-10-25

    This patent describes an electric storage battery comprising (1) a container defining a compartment containing gas-generating electro-chemical means for producing an electric current, and (2) check/relief valve means operatively associated with the container upon closing to isolate the electrochemical means from the ambient atmosphere and upon opening to vent the compartment when the internal pressure of the gas generated in the compartment exceeds a predetermined superatmospheric pressure the improvement wherein the valve comprises: a housing defining a vent chamber and including a valve seat projecting into the chamber, the seat having a sloping exterior sealing surface; an inlet in one end of the housing for admitting gas into the chamber from the compartment; means for exhausting the gas from the chamber to the environment; and a sealing member in the chamber circumscribing the inlet for controlling the internal pressures at which the opening and closing occurs and as necessary, for dumping relatively large volumes of the gas without excessive build-up of the internal pressure in the container. The sealing member comprising an annular elastomeric skirt secured at one end and having a tubular portion extending from the one end above the inlet so as to provide an internal annular surface exposed to the internal gas pressure and a sealing edge on the interior of the other end of the tubular portion circumferentially sealing engaging the sloping exterior sealing surface when the valve is closed

  2. EVALUATION OF SOIL VENTING APPLICATION

    EPA Science Inventory

    The ability of soil venting to inexpensively remove large amounts of volatile organic compounds (VOCs) from contaminated soils is well established. However, the time required using venting to remediate soils to low contaminant levels often required by state and federal regulators...

  3. Pulmonary Fissure Integrity and Collateral Ventilation in COPD Patients

    PubMed Central

    Pu, Jiantao; Wang, Zhimin; Gu, Suicheng; Fuhrman, Carl; Leader, Joseph K.; Meng, Xin; Tedrow, John; Sciurba, Frank C.

    2014-01-01

    Purpose To investigate whether the integrity (completeness) of pulmonary fissures affects pulmonary function in patients with chronic obstructive pulmonary disease (COPD). Materials and Methods A dataset consisting of 573 CT exams acquired on different subjects was collected from a COPD study. According to the global initiative for chronic obstructive lung disease (GOLD) criteria, these subjects (examinations) were classified into five different subgroups, namely non-COPD (222 subjects), GOLD-I (83 subjects), GOLD-II (141 subjects), GOLD-III (63 subjects), and GOLD-IV (64 subjects), in terms of disease severity. An available computer tool was used to aid in an objective and efficient quantification of fissure integrity. The correlations between fissure integrity, and pulmonary functions (e.g., FEV1, and FEV1/FVC) and COPD severity were assessed using Pearson and Spearman's correlation coefficients, respectively. Results For the five sub-groups ranging from non-COPD to GOLD-IV, the average integrities of the right oblique fissure (ROF) were 81.8%, 82.4%, 81.8%, 82.8%, and 80.2%, respectively; the average integrities of the right horizontal fissure (RHF) were 62.6%, 61.8%, 62.1%, 62.2%, and 62.3%, respectively; the average integrities of the left oblique fissure (LOF) were 82.0%, 83.2%, 81.7%, 82.0%, and 78.4%, respectively; and the average integrities of all fissures in the entire lung were 78.0%, 78.6%, 78.1%, 78.5%, and 76.4%, respectively. Their Pearson correlation coefficients with FEV1 and FE1/FVC range from 0.027 to 0.248 with p values larger than 0.05. Their Spearman correlation coefficients with COPD severity except GOLD-IV range from −0.013 to −0.073 with p values larger than 0.08. Conclusion There is no significant difference in fissure integrity for patients with different levels of disease severity, suggesting that the development of COPD does not change the completeness of pulmonary fissures and incomplete fissures alone may not contribute to the

  4. Ice-Confined Basaltic Eruptive Fissure Complexes in Iceland: Accessible Analogs for Understanding Shallow Submarine Ridge Construction

    NASA Astrophysics Data System (ADS)

    Skilling, I. P.; Mercurio, E.; Cameron, B. I.

    2009-12-01

    In southwest Iceland, the onshore Mid-Atlantic Ridge (Reykjanes Ridge) forms a series of fissure and central vent (“shield”) volcanic complexes, known as the Western Volcanic Zone (WVZ). Sveifluháls is one of the longest fissure-fed complexes in the WVZ, and was erupted in an ice-confined environment during the Last Glacial Maximum. There are more than 1000 similar such glaciovolcanic ridges in Iceland, but there are few detailed studies of their construction. The complexes are both an important record of North Atlantic terrestrial ice presence and thicknesses in the Pleistocene, and are accessible analogs for submarine basaltic ridge volcanism in water less than a few hundred metres deep. This study focuses on the volcanic and sedimentary processes, products and depositional environments at Sveifluháls. Sveifluháls is a complex of closely spaced, sub-parallel, and multiple vent ridges. Ridges are constructed of numerous, regularly-spaced to overlapping and steep-sided topographic highs (point-source vents or tuff cones) and short, lower, intervening ridge segments (fissure vents or “tuff ridges”). Both tuff cones and tuff ridges consist dominantly of basal subaqueous lavas draped by phreatomagmatic tephra. Point-source vents have an average spacing of 0.7 km. Up to nine sub-parallel fissures/ridges occur, spaced 0.03-0.5 km apart. Ridges range from a few hundred metres to 21.5km in length. The majority of the phreatomagmatic has been rotated, slumped or slid. An upper sequence of inward and outward-dipping, over-steepened (rotated) “soft-margined” domains and angular blocks of bedded, subaqueously-deposited “Surtseyan” lapilli tuff, overlies more widespread aprons of very similar, but mostly slumped massive tephra. Important results to date include the observation that 1-2m wide dikes, emplaced into formerly wet unconsolidated tephra, form a volumetrically important part of the complex. The host tephra commonly shows evidence of deformation and

  5. Identification of possible recent water/lava source vents in the Cerberus plains: Stratigraphic andcrater count age constraints

    NASA Astrophysics Data System (ADS)

    Thomas, Rebecca J.

    2013-04-01

    In order to investigate sources of lava and water to the Cerberus plains of Mars, geomorphological mapping on High Resolution Imaging Science Experiment (HiRISE) images was carried out to reveal the history of activity of fissures and pits which lie upstream of channels and deposits associated with a wrinkle ridge near Cerberus Fossae. The fissures and pits are superbly exposed and imaged, and flows and channels emanate directly from them, interpreted as clear evidence that these are vents. The mapping establishes stratigraphic relationships between the plains and the channels and deposits originating from the vents, establishing the vent history. For example, to the south of the wrinkle ridge, both incised channels and leveed flows extend onto the southern plain and are clearly the final phase of plains-forming activity. Conversely, to the north, vent-sourced channels only incise the plain close to the ridge—beyond that, they are overlain by large-scale regional flows that appear to have originated from the direction of Athabasca Valles. In the southeast, there is evidence of contemporaneity between vent-sourced activity and large-scale plains-forming flow that was not sourced from the vents, indicating that activity here was part of a broader process of Cerberus plains formation from multiple sources. Crater counts show all the activity to be Late Amazonian, with the latest activity tentatively dating to circa 11 Ma. Thus, this study implies that very recent outflows from these vents contributed to the formation of the Cerberus plains and constrains the timing and local flow direction of plains-forming deposits from other sources.

  6. Arteries and Veins of the Sylvian Fissure and Insula: Microsurgical Anatomy.

    PubMed

    Delion, Matthieu; Mercier, Philippe; Brassier, Gilles

    2016-01-01

    We present a vascular anatomical study of the arteries and veins of the sylvian fissure and insula.A good knowledge of the sylvian fissure, the insula, and their vascular relationship would seem mandatory before performing surgery in this area, whatever the type of surgery (aneurysms, arteriovenous malformations, insular tumors).We start with the sylvian fissure and insula morphology, followed by the MCA description and its perforators, with special attention paid to the insular perforators. We demonstrate that the long insular perforators penetrating in the superior part of the posterior short gyrus and long gyri vascularize, respectively, the corticonuclear and corticospinal fasciculi. We particularly insist too on three anatomical constants regarding the vascularization of the insula, already described in the literature: The superior periinsular sulcus is the only sulcus on the lateral surface of the brain without an artery along its axis; the superior branch of the MCA supplies the anterior insular pole and both the anterior and middle short gyri in 100 % of cases; in at least 90 % of cases, the artery that supplied the central insular sulcus continued on to become the central artery.We end with the anatomical study of the veins and cisterns. PMID:26508410

  7. Resin infiltration of fissure caries with various techniques of pretreatment in vitro.

    PubMed

    Lausch, Julian; Paris, Sebastian; Selje, Timo; Dörfer, Christof E; Meyer-Lueckel, Hendrik

    2015-01-01

    The resin infiltration technique might be used for occlusal caries lesions in order to arrest their progression. This in vitro study evaluated the influence of various modifications of the infiltration technique on the penetration abilities of the infiltrant into occlusal lesions. Extracted human molars and premolars (n = 140) with non-cavitated white spot lesions were randomly allocated to 7 groups. As control, specimens were etched with 15% hydrochloric acid (HCl) gel for 120 s and resin infiltrated for 180 s (Icon; DMG). As modification HCl gel reduced in surface tension and viscosity with and without abrasives was applied using 3 different types of brushes either to oscillate or rub the HCl gel onto the enamel surface. The median maximum lesion depth was 1,232 µm (interquartile range 882-1,513). Compared with the control procedure [23% (16/50)] a higher percentage penetration was observed if the HCl gel was mixed with a small amount of abrasives were rubbed into the fissures using a modified brush with stiff bristles that were adjusted to the fissure relief for either 120 s [100% (64/100)] or 30 s [98% (61/100); p < 0.05; Mann-Whitney test]. All other experimental treatments resulted in penetration results in-between. It can be concluded that the use of an abrasive HCl gel in conjunction with a modified brush mostly enhances resin infiltration into fissure caries lesions. PMID:25427531

  8. Vesicle size analysis of magmatic and phreatomagmatic phases of the 934-40 AD Eldgjá fissure eruption, southern Iceland

    NASA Astrophysics Data System (ADS)

    Thordarson, T.; Moreland, W.; Houghton, B. F.

    2014-12-01

    Eldgjá is a ~75 km volcanic fissure which erupted in the middle of the 10th century. It belongs to the Katla volcanic system and is of the mixed-cone row type. The eruption lasted several years and produced two large lava fields (18.3 km3) and a widespread basaltic tephra deposit (4.5 km3 or 1.3 km3 DRE). Proximal tephra deposits are up to 5 m thick and contain as many as 10 sub-units which vary in thickness parallel to the fissure, indicating multiple points of origin. Many of the lowest units were produced by phreatomagmatic activity and dispersion of these units indicate an origin below the Mýrdalsjökull glacier. Two sections were chosen to represent magmatic and phreatomagmatic activity. A 3.7 m section at Skælingar, 0.5 km south-east of Eldgjá, represents the magmatic products. The phreatomagmatic products are represented by a 2.7 m thick section at Stóragil, located 10-15 km south and east of the vent system. The sampled phreatomagmatic part of the section is 1.12 m thick. These sections were logged and then each sub-unit was sampled for density analysis which involves picking 100 clasts in the 8 to 32 mm size range from horizons less than 5 cm thick. Thin-sections were then made from representative clasts of each sub-unit. Nested images of these thin-sections were analysed for vesicle size and shape. The magmatic clasts have unimodal, normal to moderately log-normal density distributions with a mean density of 7900-7500 kg.m-3 (60-70% vesicularity) and a range of around 8600 kg.m-3 (40% vesicularity). The log-normal distribution of some samples may be explained by the inclusion of previously degassed magma in the eruption. The section at Stóragil contains both phreatomagmatic and magmatic products. The phreatomagmatic samples have characteristic plateau-like distributions with a mean density of 7200-7500 kg.m-3 (70-80% vesicularity) and a range of around 8420 kg.m-3 (45% vesicularity). One layer shows a change from phreatomagmatic to magmatic

  9. Open Fissure Folds record coseismic loading and postseismic stress relaxation

    NASA Astrophysics Data System (ADS)

    Nüchter, Jens-Alexander

    2015-03-01

    Open Fissure Folds hosted by high pressure/low temperature metamorphic rocks of south Evia (Greece) are introduced, their structural and microstructural record is analysed, and a mechanical model is proposed. Open Fissure Folds are preserved as at least two parallel folded quartz-feldspar veins separated by narrow buckled rock columns. The veins originated as tensile cracks that propagated in the middle crust driven by high differential stress. Features diagnostic for Open Fissure Folds indicate that the rock columns represented the layers of high viscosity, and not the veins as consistently reported in many previous studies on folded veins. This record is taken to indicate that buckling of the rock columns initiated after arrest of the fractures and terminated prior to complete vein sealing. Accordingly, mechanical decoupling by open fissures allowed for buckling of the rock columns in response to episodic creep of the host rocks according to stress relaxation, as expected for postseismic deformation in the earthquake cycle. I propose that the parental fractures propagated in response to quasi-instantaneous coseismic loading of the middle crust. Buckling was attributed to transient postseismic creep and stress relaxation. Complete sealing of the veins occurred when stresses were largely relaxed. Each Open Fissure Fold records the stress and strain history of a single earthquake.

  10. Provisions for containment venting in Germany

    SciTech Connect

    Wilhelm, J.G.

    1997-08-01

    In this short paper an overlook is given of the systems developed in Germany for filtered containment venting and their implementation in nuclear power plants. More information on the development can be found in the Proceedings of the DOE/NRC Aircleaning Conferences. In Germany, 28.8 % of the electric energy is produced by 19 nuclear power reactors. No new power reactor is expected to be built at least within the next ten years, but France and Germany cooperate in the development of a future European Power Reactor (ERP). This reactor type will be fitted with a core catcher and passive cooling in order to avoid serious consequences of a hypothetical core meltdown accident so that provisions for containment venting are not required. 3 refs., 6 figs., 1 tab.

  11. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) Materials—(1) Pipe. Vent piping shall be standard weight steel, wrought iron, brass, copper tube DWV, listed... fixture unit loading. (4) The device shall be installed in a location that permits a free flow of air...

  12. Research on positioning of Xi'an ground fissures with InSAR quality map

    NASA Astrophysics Data System (ADS)

    Xu, Li; Zhao, Chao-ying

    2011-02-01

    Xi'an ground fissure is a typical geo-hazard with nearly half a century history, which have been caused serious damages to roads, building and other civil facilities. Based on the theory of deformation de-correlation of the active ground fissures, this manuscript mainly investigated the positioning method of active ground fissures by analyzing the pseudo-coherence map of adaptively filtered differential interferogram. We took two ERS1 SAR data during 1992-1993 as an example to investigate the active fissures position during this period. Consequently, high consistency between newly detected fissures and the ground fissure map from engineering geological investigation can be achieved.

  13. Cost considerations in the treatment of anal fissures.

    PubMed

    Brisinda, Giuseppe; Bianco, Giuseppe; Silvestrini, Nicola; Maria, Giorgio

    2014-08-01

    Anal fissure is a split in the lining of the distal anal canal. Lateral internal sphincterotomy remains the gold standard for treatment of anal fissure. Although technique is simple and effective, a drawback of this surgical procedure is its potential to cause minor but some times permanent alteration in rectal continence. Conservative approaches (such as topical application of ointment or botulinum toxin injections) have been proposed in order to treat this condition without any risk of permanent injury of the internal anal sphincter. These treatments are effective in a large number of patients. Furthermore, with the ready availability of medical therapies to induce healing of anal fissure, the risk of a first-line surgical approach is difficult to justify. The conservative treatments have a lower cost than surgery. Moreover, evaluation of the actual costs of each therapeutic option is important especially in times of economic crisis and downsizing of health spending. PMID:24867398

  14. Perioperative Identification of an Accessory Fissure of the Right Lung

    PubMed Central

    Taverne, Yannick; Kleinrensink, Gert-Jan; de Rooij, Peter

    2015-01-01

    Anatomical variations of lungs are common in clinical practice; however, they are sometimes overlooked in routine imaging. Surgical anatomy of the lung is complex and many variations are known to occur. A defective pulmonary development gives rise to variations in lobes and fissures. Morphological presentation is of clinical importance and profound knowledge of the organogenesis and functional anatomy is imperative for the interpretation and evaluation of lung pathophysiology and subsequent surgical intervention. However, appreciating them on radiographs and CT scans is difficult and they are therefore often either not identified or completely misinterpreted. As presented in this case report, an accessory fissure separating the superior segment of the right lower lobe from its native lobe was seen perioperatively and could only retrospectively be defined on X-rays and CT scan. It is imperative to keep in mind that accessory fissures can be missed on imaging studies and thus can make the surgical procedure more challenging. PMID:26185701

  15. Marginal Microleakage of Conventional Fissure Sealants and Self-Adhering Flowable Composite as Fissure Sealant in Permanent Teeth

    PubMed Central

    Rahimian-Imam, Sara; Fayazi, Mohammad Reza

    2015-01-01

    Objectives: Application of sealants is a safe and effective way to prevent occlusal caries in the posterior teeth. A successful sealant therapy depends on good isolation. Decreased steps of adhesive application may enable proper isolation and use of self-adhering flowable composites for sealant therapy. This study sought to compare the marginal microleakage of fissure sealants and self-adhering flowable composites in permanent teeth. Materials and Methods: This in vitro, experimental study was conducted on 60 extracted human premolar teeth. The teeth were divided randomly into two groups of 30. In the first group, fissure sealant (Clinpro, 3M ESPE, USA) was placed on the teeth. In the second group, self-adhering flowable composite (Vertise Flow, Kerr, USA) was applied as the sealant. Then, both groups were immersed in 0.5% fuchsin dye solution for 24 hours. Sectioned samples were observed with a stereomicroscope for the extent of dye penetration. Data were analyzed using SPSS 21 and the Mann-Whitney test (P<0.05). Results: Microleakage in the fissure sealant group was significantly higher than that in the self-adhering flowable composite group (P<0.001). Conclusion: Microleakage was less using self-adhering flowable composite compared to conventional fissure sealant; therefore, self-adhering flowable composite can be used as a suitable fissure sealant in permanent teeth. PMID:26884777

  16. Pit and fissure sealant: review of the literature.

    PubMed

    Simonsen, Richard J

    2002-01-01

    For this literature review of pit and fissure sealant, 1,465 references were selected by a search for "sealants" on PubMed. References were limited to dental journals and papers in the English language. The search comprised papers from 1971 to October 2001. Additional papers of historical significance prior to 1971 were added from memory and from reference lists published in early papers. This paper reviewed the literature on pit and fissure sealants under the following subheadings: (1) laboratory studies, (2) clinical technique and tooth preparation, (3) etching time, (4) auxiliary application of pit and fissure sealant, (5) retention and caries prevention, (6) fluoride used with sealants and fluoride-containing sealant, (7) glass ionomer materials as sealants, (8) options in sealant: filled vs unfilled; colored vs clear; autocure vs light-initiated, (9) sealant placed over caries in a therapeutic manner, (10) cost effectiveness of sealant application, (11) underuse of pit and fissure sealant, (12) the estrogenicity issue, (13) use of an intermediate bonding layer to improve retention, (14) new developments and projections, and (15) summary and conclusions. From a careful and thorough review of peer-reviewed publications on pit and fissure sealant, it is clear that sealants are safe, effective and underused (at least underused in the United States). Pit and fissure sealant is best applied to high-risk populations by trained auxiliaries using sealant that incorporates the benefit of an intermediate bonding layer, applied under the rubber dam or with some alternative short-term, but effective, isolation technique, onto an enamel surface that has been cleaned with an air polishing technique and etched with 35% phosphoric acid for 15 seconds. The dental profession awaits with enthusiasm, and some impatience, the incorporation of dentin-bonding technology into the development of a modern, more durable, resin-based sealant. PMID:12412954

  17. Potential biomass in deep-sea hydrothermal vent ecosystem

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Takai, K.

    2012-12-01

    Since the first discovery of black smoker vents hosting chemosynthetic macrofaunal communities (Spiess et al., 1980), submarine hydrothermal systems and associated biota have attracted interest of many researchers (e.g., Humphris et al., 1995; Van Dover, 2000; Wilcock et al., 2004). In the past couple of decades, particular attention has been paid to chemolithoautotrophic microorganisms that sustain the hydrothermal vent-endemic animal communities as the primary producer. This type of microorganisms obtains energy from inorganic substances (e.g., sulfur, hydrogen, and methane) derived from hydrothermal vent fluids, and is often considered as an important modern analogue to the early ecosystems of the Earth as well as the extraterrestrial life in other planets and moons (e.g., Jannasch and Mottl, 1985; Nealson et al., 2005; Takai et al., 2006). Even today, however, the size of this type of chemosynthetic deep-sea hydrothermal vent ecosystem is largely unknown. Here, we present geophysical and geochemical constraints on potential biomass in the deep-sea hydrothermal vent ecosystem. The estimation of the potential biomass in the deep-sea hydrothermal vent ecosystem is based on hydrothermal fluid flux calculated from heat flux (Elderfield and Schltz, 1996), maximum chemical energy available from metabolic reactions during mixing between hydrothermal vent fluids and seawater (McCollom, 2007), and maintenance energy requirements of the chemolithoautotrophic microorganisms (Hoehler, 2004). The result shows that the most of metabolic energy sustaining the deep-sea hydrothermal vent ecosystem is produced by oxidation reaction of reduced sulfur, although some parts of the energy are derived from hydrogenotrophic and methanotrophic reactions. The overall total of the potential biomass in deep-sea hydrothermal vent ecosystem is calculated to be much smaller than that in terrestrial ecosystems including terrestrial plants. The big difference in biomass between the

  18. Cement penetration after patella venting.

    PubMed

    Jones, Christopher W; Lam, Li-On; Butler, Adam; Wood, David J; Walsh, William R

    2009-01-01

    There is a high rate of patellofemoral complications following total knee arthroplasty. Optimization of the cement-bone interface by venting and suction of the tibial plateau has been shown to improve cement penetration. Our study was designed to investigate if venting the patella prior to cementing improved cement penetration. Ten paired cadaver patellae were allocated prior to resurfacing to be vented or non-vented. Bone mineral density (BMD) was measured by DEXA scanning. In vented specimens, a 1.6 mm Kirschner wire was used to breach the anterior cortex at the center. Specimens were resurfaced with standard Profix instrumentation and Versabond bone cement (Smith and Nephew PLC, UK). Cement penetration was assessed from Faxitron and sectioned images by a digital image software package (ImageJ V1.38, NIH, USA). Wilcoxon rank sum test was used to assess the difference in cement penetration between groups. The relationship between BMD and cement penetration was analyzed by Pearson correlation coefficient. There was a strong negative correlation between peak BMD and cement penetration when analyzed independent of experimental grouping (r(2)=-0.812, p=0.004). Wilcoxon rank sum testing demonstrated no significant difference (rank sum statistic W=27, p=0.579) in cement penetration between vented (10.53%+/-4.66; mean+/-std dev) and non-vented patellae (11.51%+/-6.23; mean+/-std dev). Venting the patella using a Kirschner wire does not have a significant effect on the amount of cement penetration achieved in vitro using Profix instrumentation and Versabond cement. PMID:19010682

  19. On small disturbance ascent vent behavior

    NASA Astrophysics Data System (ADS)

    Woronowicz, M. S.

    2012-10-01

    As a spacecraft undergoes ascent in a launch vehicle, its ambient pressure environment transitions from one atmosphere to high vacuum in a matter of a few minutes. Venting of internal cavities is necessary to prevent the buildup of pressure differentials across cavity walls. These pressure differentials are often restricted to low levels to prevent violation of container integrity. Such vents usually consist of fixed orifices, ducts, or combinations of both. Duct conductance behavior is fundamentally different from that for orifices in pressure driven flows governing the launch vehicle ascent depressurization environment. Duct conductance is governed by the average pressure across its length, while orifice conductance is dictated by a pressure ratio. Hence, one cannot define a valid "equivalent orifice" for a given duct across a range of pressure levels. The purpose of this paper is to develop expressions for these two types of vent elements in the limit of small pressure differentials, explore conditions for their validity, and to compare features regarding ascent depressurization performance.

  20. 2D models of gas flow and ice grain acceleration in Enceladus' vents using DSMC methods

    NASA Astrophysics Data System (ADS)

    Tucker, Orenthal J.; Combi, Michael R.; Tenishev, Valeriy M.

    2015-09-01

    The gas distribution of the Enceladus water vapor plume and the terminal speeds of ejected ice grains are physically linked to its subsurface fissures and vents. It is estimated that the gas exits the fissures with speeds of ∼300-1000 m/s, while the micron-sized grains are ejected with speeds comparable to the escape speed (Schmidt, J. et al. [2008]. Nature 451, 685-688). We investigated the effects of isolated axisymmetric vent geometries on subsurface gas distributions, and in turn, the effects of gas drag on grain acceleration. Subsurface gas flows were modeled using a collision-limiter Direct Simulation Monte Carlo (DSMC) technique in order to consider a broad range of flow regimes (Bird, G. [1994]. Molecular Gas Dynamics and the Direct Simulation of Gas Flows. Oxford University Press, Oxford; Titov, E.V. et al. [2008]. J. Propul. Power 24(2), 311-321). The resulting DSMC gas distributions were used to determine the drag force for the integration of ice grain trajectories in a test particle model. Simulations were performed for diffuse flows in wide channels (Reynolds number ∼10-250) and dense flows in narrow tubular channels (Reynolds number ∼106). We compared gas properties like bulk speed and temperature, and the terminal grain speeds obtained at the vent exit with inferred values for the plume from Cassini data. In the simulations of wide fissures with dimensions similar to that of the Tiger Stripes the resulting subsurface gas densities of ∼1014-1020 m-3 were not sufficient to accelerate even micron-sized ice grains to the Enceladus escape speed. In the simulations of narrow tubular vents with radii of ∼10 m, the much denser flows with number densities of 1021-1023 m-3 accelerated micron-sized grains to bulk gas speed of ∼600 m/s. Further investigations are required to understand the complex relationship between the vent geometry, gas source rate and the sizes and speeds of ejected grains.

  1. Dental Pit and Fissure Sealants: Implications for School Health Personnel.

    ERIC Educational Resources Information Center

    McCormack-Brown, K. R.; And Others

    1989-01-01

    To promote good personal hygiene practices in students, school health personnel must be informed about dental pit and fissure sealants and related programs. Adoption and maintenance of such programs may depend on the success of school health personnel in educating administrators and policymakers. (SM)

  2. Hemorrhoids and anal fissures in inflammatory bowel disease.

    PubMed

    D'Ugo, S; Stasi, E; Gaspari, A L; Sileri, P

    2015-12-01

    Perianal disease is a common complication of inflammatory bowel disease (IBD). It includes different conditions from more severe and potentially disabling ones, such as abscesses and fistulas, to more benign conditions such as hemorrhoids, skin tags and fissures. Most literature has been focused on anal sepsis and fistulae, as they carry the majority of disease burden and often alter the natural course of the disease. Hemorrhoids and anal fissures in patients with IBD have been overlooked, although they can represent a challenging problem. The management of hemorrhoids and fissures in IBD patients may be difficult and may significantly differ compared to the non-affected population. Historically surgery was firmly obstructed, and hemorrhoidectomy or sphincterotomy in patients with associated diagnosis of IBD was considered harmful, although literature data is scant and based on small series. Various authors reported an incidence of postoperative complications higher in IBD than in the general populations, with potential severe events. Considering that a spontaneous healing is possible, the first line management should be a medical therapy. In patients non-responding to conservative measures it is possible a judicious choice of surgical options on a highly selective basis; this can lead to acceptable results, but the risk of possible complications needs to be considered. In this review it is analyzed the current literature on the incidence, symptoms and treatment options of hemorrhoids and anal fissures in patients with Crohn's disease and ulcerative colitis. PMID:26446683

  3. New method opens opportunity to proactively select for fissure resistance in early breeding generations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    WANTED: New rice varieties improved for resistance to kernel fissuring. Rice kernel fissuring is one of the leading causes of reduced milling yield. Any reduction in fissuring can result in direct increases in yield and profit for both producers and millers. While most U.S. rice varieties yield a...

  4. Numerical modeling of the evolution of two-phase zone under fissured caprock

    SciTech Connect

    Yano, Y.; Ishido, T.

    1993-01-28

    A vapor-dominated two-phase zone would be formed in a geothermal reservoir under fissured caprock, if the permeability of the fissure is much smaller than a critical permeability which is estimated by an energy balance. If the permeability of the fissure is large, then the rule of minimum mass input would be applied.

  5. Selection for fissure resistance now made possible in early breeding generations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice kernel fissuring is one of the leading causes of milling yield losses. Any reduction in fissuring can result in direct increases in yield and profit for both producers and millers. While most U.S. rice varieties yield around 55% head rice, the fissure-resistant varieties ‘Cypress’, ‘Saber’ an...

  6. High-Resolution Micro-Bathymetry Mapping in the Lau Basin: Examples From the Tui Malila and Mariner Vent Sites

    NASA Astrophysics Data System (ADS)

    Ferrini, V.; Sterling, A.; Martinez, F.; Tivey, M. K.; Mottl, M.; Kim, S.

    2005-12-01

    High-resolution SM2000 (200 kHz) multibeam sonar data were collected at six vent areas on the Lau Basin spreading center in April 2005. Data were acquired during near-bottom surveys conducted with the ROV Jason II at altitudes ranging from 5 to 20 m. High altitude (20 m) bathymetric surveys were complemented by near-bottom visual surveys, which provided ground-truth observations of the seafloor. Combined with Doppler and Long Baseline (LBL) Navigation, these bathymetry data provide sub-meter resolution of seafloor features, and reveal individual vent structures, faults and fissures. We present bathymetry data from two sites located 22 km apart, which are geologically and biologically distinct and exhibit contrasts in venting styles and biota. The Mariner vent field contains massive vent structures, many of which are taller than 25 m, with active venting from their bases and sides. Fluids exit as vigorous, high-temperature (< 363°C) black smoker fluids through chalcopyrite-lined conduits, and as less focused flow from porous beehive structures. Inactive structures are friable and are composed of iron- and copper-oxides. There was little evidence of faulting or fracture at the vent field, but we note the presence of collapsed volcanic dome structures. The vent fauna at Mariner is very limited; only Bythograeid and Galatheid crabs, and one Brisingid Seastar, were found. Tui Malila, by contrast, is characterized by shorter and wider branched vent structures with coalesced spires, the tops of which were actively venting. There is extensive faulting and fracture at this site, as well as a number of large flanges and areas of diffuse flow. At Tui Malila fluids exit tall structures through chalcopyrite- and zinc-lined conduits (at temperatures < 312°C), from beneath flanges, and directly from andesite. Hydrothermal breccias are also present. Tui Malila hosts a more typical vent community, with greater abundances of both Bythograeid and Galatheid crabs, mostly within 4 m

  7. Complete genome sequence of the thermophilic sulfur-reducer Desulfurobacterium thermolithotrophum type strain (BSAT) from a deep-sea hydrothermal vent

    SciTech Connect

    Goker, Markus; Daligault, Hajnalka E.; Mwirichia, Romano; Lapidus, Alla L.; Deshpande, Shweta; Pagani, Ioanna; Tapia, Roxanne; Cheng, Jan-Fang; Goodwin, Lynne A.; Pitluck, Sam; Liolios, Konstantinos; Ivanova, N; Mavromatis, K; Mikhailova, Natalia; Pati, Amrita; Chen, Amy; Palaniappan, Krishna; Han, Cliff; Land, Miriam L; Hauser, Loren John; Pan, Chongle; Brambilla, Evelyne-Marie; Rohde, Manfred; Spring, Stefan; Sikorski, Johannes; Wirth, Reinhard; Detter, J. Chris; Woyke, Tanja; Bristow, James; Eisen, Jonathan; Markowitz, Victor; Hugenholtz, Philip; Kyrpides, Nikos C; Klenk, Hans-Peter

    2011-01-01

    Desulfurobacterium thermolithotrophum L'Haridon et al. 1998 is the type species of the ge- nus Desulfurobacterium which belongs to the family Desulfurobacteriaceae. The species is of interest because it represents the first thermophilic bacterium that can act as a primary pro- ducer in the temperature range of 45-75 C (optimum 70 C) and is incapable of growing un- der microaerophilic conditions. Strain BSAT preferentially synthesizes high-melting-point fatty acids (C18 and C20) which is hypothesized to be a strategy to ensure the functionality of the membrane at high growth temperatures. This is the second completed genome sequence of a member of the family Desulfurobacteriaceae and the first sequence from the genus Desulfu- robacterium. The 1,541,968 bp long genome harbors 1,543 protein-coding and 51 RNA genes and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

  8. Reactor pressure vessel vented head

    DOEpatents

    Sawabe, James K.

    1994-01-11

    A head for closing a nuclear reactor pressure vessel shell includes an arcuate dome having an integral head flange which includes a mating surface for sealingly mating with the shell upon assembly therewith. The head flange includes an internal passage extending therethrough with a first port being disposed on the head mating surface. A vent line includes a proximal end disposed in flow communication with the head internal passage, and a distal end disposed in flow communication with the inside of the dome for channeling a fluid therethrough. The vent line is fixedly joined to the dome and is carried therewith when the head is assembled to and disassembled from the shell.

  9. Modeling of zero gravity venting

    NASA Technical Reports Server (NTRS)

    Merte, H., Jr.

    1984-01-01

    The venting of cylindrical containers partially filled with initially saturated liquids was conducted under zero gravity conditions and compared with an analytical model which determined the effect of interfacial mass transfer on the ullage pressure response during venting. A model is proposed to improve the estimation of the interfacial mass transfer. Duhammel's superposition integral is incorporated in this analysis to approximate the transient temperature response of the interface, treating the liquid as a semiinfinite solid with conduction heat transfer. This approach to estimating interfacial mass transfer gives improved response when compared to previous models. The model still predicts a pressure decrease greater than those in the experiments reported.

  10. Double-Porosity Models for a Fissured Groundwater Reservoir With Fracture Skin

    NASA Astrophysics Data System (ADS)

    Moench, Allen F.

    1984-07-01

    Theories of flow to a well in a double-porosity groundwater reservoir are modified to incorporate effects of a thin layer of low-permeability material or fracture skin that may be present at fracture-block interfaces as a result of mineral deposition or alteration. The commonly used theory for flow in double- porosity formations that is based upon the assumption of pseudo-steady state block-to-fissure flow is shown to be a special case of the theory presented in this paper. The latter is based on the assumption of transient block-to-fissure flow with fracture skin. Under conditions where fracture skin has a hydraulic conductivity that is less than that of the matrix rock, it may be assumed to impede the interchange of fluid between the fissures and blocks. Resistance to flow at fracture-block interfaces tends to reduce spatial variation of hydraulic head gradients within the blocks. This provides theoretical justification for neglecting the divergence of flow in the blocks as required by the pseudo-steady state flow model. Coupled boundary value problems for flow to a well discharging at a constant rate were solved in the Laplace domain. Both slab-shaped and sphere-shaped blocks were considered, as were effects of well bore storage and well bore skin. Results obtained by numerical inversion were used to construct dimensionless-type curves that were applied to well test data, for a pumped well and for an observation well, from the fractured volcanic rock terrane of the Nevada Test Site.

  11. 14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fuel tank vents and carburetor vapor vents. 29.975 Section 29.975 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System § 29.975 Fuel tank vents and carburetor vapor vents....

  12. 14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fuel tank vents and carburetor vapor vents. 25.975 Section 25.975 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.975 Fuel tank vents and carburetor vapor vents....

  13. Monitoring of the volcanic rock compositions during the 2012-2013 fissure eruption at Tolbachik volcano, Kamchatka

    NASA Astrophysics Data System (ADS)

    Volynets, Anna O.; Edwards, Benjamin R.; Melnikov, Dmitry; Yakushev, Anton; Griboedova, Irina

    2015-12-01

    Here we present the results from monitoring of the composition of rocks produced during the 2012-2013 fissure eruption at Tolbachik volcano (FTE). Major and trace element concentrations in 75 samples are reported. Products of this eruption are represented by high alumina basaltic trachyandesites with higher alkalis and titanium contents than in all previously studied rocks of the Tolbachik monogenetic volcanic field. Rocks erupted during the first three days (27-30 November) from the northern (also called Menyailov) group of vents are the most silica- and alkali-rich (SiO2 concentrations up to 55.35 wt.% and K2O up to 2.67 wt.%). From December onwards, when the eruptive activity switched from the Menyailov vents to the southern (Naboko) group of vents, silica content dropped by 2 wt.%, concentrations of MgO, FeO, TiO2 and Mg# increased, and K2O and Na2O concentrations and K2O/MgO ratio decreased. For the rest of the eruption the compositions of rocks remained constant and homogeneous; no systematic compositional differences between lava, bombs and scoria samples are evident. Trace element distributions in the rocks of the Menyailov and Naboko vent lavas are relatively uniform; Menyailov lavas have slightly higher Th, Nb, Hf, Y, and HREE concentrations than the Naboko vent lavas at more or less constant element ratios. We explain the initial change in geochemistry by tapping of a slightly cooler and fractionated (~ 3% Mt and 8% Cpx) upper part of the magma storage zone before the main storage area began to feed the eruption. Thermodynamic constraints show that apparent liquidus temperatures varied from 1142 °C to 1151 °C, and thermodynamic modeling shows that variations in compositions are consistent with a high degree of low pressure (100-300 MPa), nominally anhydrous fractionation of a parent melt compositionally similar to the 1975 Northern Breakthrough high-Mg basalt. Geochemistry, petrological observations and modeling are in agreement with the newly erupted

  14. A Computational Geometry Approach to Automated Pulmonary Fissure Segmentation in CT Examinations

    PubMed Central

    Pu, Jiantao; Leader, Joseph K; Zheng, Bin; Knollmann, Friedrich; Fuhrman, Carl; Sciurba, Frank C; Gur, David

    2010-01-01

    Identification of pulmonary fissures, which form the boundaries between the lobes in the lungs, may be useful during clinical interpretation of CT examinations to assess the early presence and characterization of manifestation of several lung diseases. Motivated by the unique nature of the surface shape of pulmonary fissures in three-dimensional space, we developed a new automated scheme using computational geometry methods to detect and segment fissures depicted on CT images. After a geometric modeling of the lung volume using the Marching Cube Algorithm, Laplacian smoothing is applied iteratively to enhance pulmonary fissures by depressing non-fissure structures while smoothing the surfaces of lung fissures. Next, an Extended Gaussian Image based procedure is used to locate the fissures in a statistical manner that approximates the fissures using a set of plane “patches.” This approach has several advantages such as independence of anatomic knowledge of the lung structure except the surface shape of fissures, limited sensitivity to other lung structures, and ease of implementation. The scheme performance was evaluated by two experienced thoracic radiologists using a set of 100 images (slices) randomly selected from 10 screening CT examinations. In this preliminary evaluation 98.7% and 94.9% of scheme segmented fissure voxels are within 2 mm of the fissures marked independently by two radiologists in the testing image dataset. Using the scheme detected fissures as reference, 89.4% and 90.1% of manually marked fissure points have distance ≤ 2 mm to the reference suggesting a possible under-segmentation of the scheme. The case-based RMS (root-mean-square) distances (“errors”) between our scheme and the radiologist ranged from 1.48±0.92 to 2.04±3.88 mm. The discrepancy of fissure detection results between the automated scheme and either radiologist is smaller in this dataset than the inter-reader variability. PMID:19272987

  15. The effect of vegetation on infiltration in shallow soils underlain by fissured bedrock

    NASA Astrophysics Data System (ADS)

    Stothoff, S. A.; Or, D.; Groeneveld, D. P.; Jones, S. B.

    1999-05-01

    Mean annual infiltration above the high-level waste repository proposed to be sited at Yucca Mountain, Nevada, has a large impact on assessments of repository performance. Ongoing investigations of infiltration processes have identified the relatively horizontal caprock environment above portions of the repository as a potentially large source of infiltrating waters, due to shallow, permeable soils above a moderately welded tuff with large soil-filled fissures. The combination of shallow soils and fissured bedrock allows rapid penetration of wetting pulses to below the rooting zone. Plant uptake can strongly reduce net infiltration in arid environments with high water storage capacity, and, despite the low water storage capacity, there is a relatively high vegetation density in this environment. The apparent discrepancy between high vegetation density and low water storage motivates the study of plant-hydrologic interactions in this semiarid environment. Field observations were coupled with plant- and landscape-scale models to provide insight into plant-hydrologic interactions. Several lines of evidence, including: (i) linear plant growth features observed on aerial photographs; (ii) comparisons of plant cover within the fissured environment and comparable environments lacking fissures; and (iii) direct excavations, all suggest that the widely spaced soil-filled fissures are conducive to plant growth even when fissures are buried at soil depths exceeding 30 cm. Results from a mechanistic simulation model for root growth into fissures suggest that the additional (sheltered) plant-available soil water within fissures provides a competitive advantage for plant establishment. Therefore, plants that germinate above a fissure are more likely to survive, in turn developing linear features above fissures. Having established that plants preferentially root within soil-filled fissures in the caprock environment, a set of simulations were performed to examine the hydrologic

  16. [Aortic intramural hematoma fissuration: atypical presentation in an aircraft pilot].

    PubMed

    Fozzato, Francesca; Prioli, Maria Antonia; Santini, Francesco; Menini, Fabio; Pavan, Michela; Guarise, Paola; Vassanelli, Corrado

    2010-02-01

    Aortic intramural hematoma is a life-threatening thoracic aortic pathology. In this report we describe a case of fissuration of an aortic intramural hematoma with atypical clinical presentation, which occurred in an aircraft pilot. The patient was admitted to our emergency room with transient chest pain developed during a flight landing, followed only by persistent abdominal pain. The ECG and cardiac enzymes were normal. A portable two-dimensional transthoracic echocardiogram showed aortic root dilation and pericardial effusion. Transesophageal echocardiography showed aortic intramural hematoma with fissuration into the pericardial space. The angio-computed tomography confirmed the diagnosis. Two hours after admission the patient, with signs of cardiac tamponade, underwent Bentall surgical intervention without complications. PMID:20408481

  17. Delayed Superior Orbital Fissure Syndrome After Reconstruction of Blowout Fracture.

    PubMed

    Kim, Young Joon; Choi, Woong Kyu

    2016-01-01

    The superior orbital fissure syndrome (SOFS) has been known to be a condition caused by impairment of the nerves that cross the superior orbital fissure. Traumatic SOFS is an uncommon complication which occurs usually within 48 hours after a facial injury. A 25-year-old male sustained facial trauma following an altercation. Clinical findings on presentation included swelling, ecchymosis, hyphema, subretinal hemorrhage, and mild extraocular movement limitation upon lateral gaze on his right eyelids. Facial computed tomography scan confirmed fractures of the medial walls of the right orbit and herniation of orbital soft tissue without the incarceration of medial rectus muscle. Ten days after the trauma, the operation was performed. On postoperative day 16, the patient showed ptosis of the right upper eyelid with a fixed pupil, and there was a hypoesthesia over the distribution of the right supraorbital and supratrochlear nerves. The authors diagnosed as a delayed SOFS and prescribed 4 mg of methylprednisolone q.i.d. for 30 days. After steroid therapy, extraocular movement limitations improved progressively. After 8 months, movement was completely restored. The authors experienced delayed SOFS on posttrauma day 27, and it was treated by steroid therapy. Surgical intervention is required when there is an evident etiology such as underlying hematoma or plate migration. If the reason is not clear like our case, steroid therapy can be considered as one of the options. Particularly, the authors should give special attention to the patient who has congenitally narrow superior orbital fissure, like Fujiwara et al suggested. PMID:26674904

  18. Effect of Different Vent Configurations on the Interruption Performance of Arc Chamber

    NASA Astrophysics Data System (ADS)

    Chen, Degui; Li, Xingwen; Dai, Ruicheng

    Gas flow in arc quenching chamber has an important effect on the interruption capability of low voltage circuit breakers. In this paper, based on a simplified model of arc chamber with a single break, which can be opened by the electro-dynamics repulsion force automatically, the effect of different vent configurations including middle vent and side vent on the interruption performance is investigated. First, the experiments are carried out to compare the different performance in the interruption process between middle vent type and side vent type. In addition, according to the experimental model, a 3-D magneto-hydrodynamic model was developed by adapting and modified the commercial computational fluid dynamics software FLUENT. The simulation results show the same trend in arc motion as explained in the experimental conclusions in theory.

  19. EXPOSED BEAM AND VINYL VENTED SOFFIT MATERIAL IN THE CARPORT ...

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

    EXPOSED BEAM AND VINYL VENTED SOFFIT MATERIAL IN THE CARPORT ON THE SOUTHEAST SIDE OF THE UNIT - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, U-Shaped Two-Bedroom Single-Family Type 6, Birch Circle, Elm Drive, Elm Circle, and Date Drive, Pearl City, Honolulu County, HI

  20. Location of seismic events and eruptive fissures on the Piton de la Fournaise volcano using seismic amplitudes

    USGS Publications Warehouse

    Battaglia, J.; Aki, K.

    2003-01-01

    We present a method for locating the source of seismic events on Piton de la Fournaise. The method is based on seismic amplitudes corrected for station site effects using coda site amplification factors. Once corrected, the spatial distribution of amplitudes shows smooth and simple contours for many types of events, including rockfalls, long-period events and eruption tremor. On the basis of the simplicity of these distributions we develop inversion methods for locating their origins. To achieve this, the decrease of the amplitude as a function of the distance to the source is approximated by the decay either of surface or body waves in a homogeneous medium. The method is effective for locating rockfalls, long-period events, and eruption tremor sources. The sources of eruption tremor are usually found to be located at shallow depth and close to the eruptive fissures. Because of this, our method is a useful tool for locating fissures at the beginning of eruptions.

  1. Electrochemical cell having a safety vent closure

    SciTech Connect

    Zupancic, R.L.

    1982-05-11

    A safety blow-out vent closure for galvanic cells, such as nonaqueous oxyhalide cells, which comprises the employment of a conductive tubular member secured to the cell's housing and surrounding a vent orifice in the cell's housing and wherein a deformable member is force-fitted in said vent orifice and adapted to at least partially be ejected from the vent orifice upon the build up of a predetermined internal gas pressure within the cell. The invention is also directed to a method for assembling an electrochemical cell with the above-described safety vent closure.

  2. The fissure: interlobar collateral ventilation and implications for endoscopic therapy in emphysema

    PubMed Central

    Koster, Theodoor David; Slebos, Dirk-Jan

    2016-01-01

    In patients with severe emphysema, bronchoscopic lung volume reduction using one-way valves is a promising therapeutic option to improve lung function and quality of life. The goal of this treatment is to achieve a complete lobar atelectasis. In a significant proportion of patients, this atelectasis cannot be achieved due to interlobar collateral ventilation. This collateral ventilation is generated through incomplete lobar fissures. Therefore, only patients with complete fissures and no collateral ventilation can be selected for endobronchial therapy with one-way valves. Incomplete fissures are very common and exhibit a great variation in anatomy. The reported prevalence is 17%–85% for the right major fissure, 19%–74% for the left major fissure, and 20%–90% for the minor fissure. There are several methods of measuring or predicting the presence of collateral ventilation, with computed tomography (CT)-fissure analysis and the Chartis measurement being the most important. CT-fissure analysis is an indirect method to measure the completeness of fissures as a surrogate for collateral ventilation. The Chartis system is an endobronchial method to directly measure the presence of collateral ventilation. Both methods have unique value, and the combination of both can accurately predict the treatment response to the bronchoscopic placement of endobronchial valves. This review provides an in-depth view of lung fissure and collateral ventilation to help understand its importance in selecting the appropriate patients for new emphysema treatments and thus avoid useless treatment in unsuitable patients. PMID:27110109

  3. Giant desiccation fissures filled with calcareous eolian sand, Hermosa Formation (Pennsylvanian), southeastern Utah

    NASA Astrophysics Data System (ADS)

    Loope, David B.; Haverland, Zsolt E.

    1988-04-01

    At two stratigraphic intervals within the upper member of the Upper Pennsylvanian Hermosa Formation, calcareous eolian sand fills downward-tapering fissures that are as much as 18 cm wide and 5.7 m deep. Fissure fillings define orthogonal polygons 10 m or more in diameter. One of the host beds is primarily composed of subtidally deposited limestone, the other is a thinly laminated, nonmarine red siltstone. Both systems of fissure fillings are directly overlain and underlain by large-scale cross-stratified, calcareous eolianites. The limestone host bed contains chert pseudomorphs after gypsum. Compaction of host rocks contorted fissure fillings and caused doming of eolian strata over each fissure. Platy mineral grains in fissure fillings are aligned subparallel to bedding in the host rocks, supporting the view that the fissures were passively filled rather than forcefully injected. These ancient fissure systems are similar in scale and pattern to those that define giant desiccation polygons in numerous Great Basin playas. The Pennsylvanian fissures, like their Holocene counterparts, probably formed when groundwater tables dropped from shallow levels within fine-grained, impermeable deposits into underlying aquifers, greatly decreasing the extent of the capillary fringe. Our study of the fissures and host rocks supports the hypothesis that carbonate grains within the eolianites were deflated from uncemented marine sediments that were broadly exposed during regressive intervals.

  4. A Review of Cyanoacrylate Liquid Skin Protectant and Its Efficacy on Pedal Fissures

    PubMed Central

    Vlahovic, Tracey C.; Hinton, Elizabeth A.; Chakravarthy, Debashish; Fleck, Cynthia Ann

    2011-01-01

    Introduction Skin fissures are a common dermatologic condition caused by excessive dry skin, numerous systemic diseases, and backless shoe gear. They are defects in skin that fall into the category of damaged, partial-thickness skin wounds, as opposed to full-thickness wounds. Patients with heel fissures are at an increased risk for developing infection, which could cause more severe issues, especially in patients with diabetes and peripheral vascular disease. Methods Five patients from Temple Foot and Ankle Institute, Philadelphia, PA, with a total of 8 heel fissures and 2 hallux fissures, were studied. Patients were dispensed 9 vials of a cyanoacrylate liquid skin protectant (Marathon™, Medline Industries, Inc, Mundelein, IL) to be applied to the fissure every 3 days. Patients returned every 2 weeks for follow-up in clinic. Results The hallux fissures and 4 of the heel fissures went to complete closure after 2 weeks. There was an average decrease of 1.16 cm in length of the heel fissure dimensions after 2 weeks and an average decrease of 1.1 cm in length of the hallux fissures. Conclusion This novel skin protectant proved to be a comfortable, easy, and effective tool in aiding the resolution of pedal skin fissures. PMID:24527155

  5. Wear of two pit and fissure sealants in contact with primary teeth

    PubMed Central

    Galo, Rodrigo; Contente, Marta Maria Martins Giamatei; Borsatto, Maria Cristina

    2014-01-01

    Objectives: Wear simulations may provide an indication of the clinical performance of pit-and-fissure sealants when associated with primary teeth as counterbody, restricting the involved variables. The aim of this study was to evaluate wear of dental materials used as pit-and-fissure sealants in contact with primary teeth. Materials and Methods: A resinous sealant (Fluroshield®) and a resin-modified glass ionomer cement (Vitremer®) were selected in a post-plate design, using as counterbody primary tooth pins (4 × 4 × 2 mm) at 3 and 10 N vertical load, 1 Hz frequency, 900 wear cycles in artificial saliva (n = 15). Attrition coefficient values were obtained and the material and primary tooth volumes were analyzed. Data were analyzed statistically by ANOVA and Duncan's test (P < 0.05). Results: Fluroshield® presented the highest attrition coefficient values for the 3 N but these values decreased significantly for the 10 N load. The means for volume loss (3 mm) of the different samples after the wear test were not statistically different for the materials. The volume loss values for the primary teeth were statistically different and there was an increase in volume loss with the increase of the load applied in the wear tests. Conclusions: Differences were also observed with regard to the surface deformation characteristics. The wear rates of primary tooth enamel vary according to the type of material and the load applied during mastication. PMID:24966777

  6. Reactor pressure vessel vented head

    DOEpatents

    Sawabe, J.K.

    1994-01-11

    A head for closing a nuclear reactor pressure vessel shell includes an arcuate dome having an integral head flange which includes a mating surface for sealingly mating with the shell upon assembly therewith. The head flange includes an internal passage extending therethrough with a first port being disposed on the head mating surface. A vent line includes a proximal end disposed in flow communication with the head internal passage, and a distal end disposed in flow communication with the inside of the dome for channeling a fluid therethrough. The vent line is fixedly joined to the dome and is carried therewith when the head is assembled to and disassembled from the shell. 6 figures.

  7. Differences in recovery between deep-sea hydrothermal vent and vent-proximate communities after a volcanic eruption

    NASA Astrophysics Data System (ADS)

    Gollner, Sabine; Govenar, Breea; Arbizu, Pedro Martinez; Mills, Susan; Le Bris, Nadine; Weinbauer, Markus; Shank, Timothy M.; Bright, Monika

    2015-12-01

    Deep-sea hydrothermal vents and the surrounding basalt seafloor are subject to major natural disturbance events such as volcanic eruptions. In the near future, anthropogenic disturbance in the form of deep-sea mining could also significantly affect the faunal communities of hydrothermal vents. In this study, we monitor and compare the recovery of insular, highly productive vent communities and vent-proximate basalt communities following a volcanic eruption that destroyed almost all existing communities at the East Pacific Rise, 9°50‧N in 2006. To study the recovery patterns of the benthic communities, we placed settlement substrates at vent sites and their proximate basalt areas and measured the prokaryotic abundance and compared the meio- and macrofaunal species richness and composition at one, two and four years after the eruption. In addition, we collected samples from the overlying water column with a pelagic pump, at one and two years after the volcanic eruption, to determine the abundance of potential meiofauna colonisers. One year after eruption, mean meio- and macrofaunal abundances were not significantly different from pre-eruption values in vent habitats (meio: 8-1838 ind. 64 cm-2 in 2006; 3-6246 ind. 64 cm-2 in 2001/02; macro: 95-1600 ind. 64 cm-2 in 2006; 205-4577 ind. 64 cm-2 in 2001/02) and on non-vent basalt habitats (meio: 10-1922 ind. 64 cm-2 in 2006; 8-328 ind. 64 cm-2 in 2003/04; macro: 14-3351 ind. 64 cm-2 in 2006; 2-63 ind. 64 cm-2 in 2003/04), but species recovery patterns differed between the two habitat types. In the vent habitat, the initial community recovery was relatively quick but incomplete four years after eruption, which may be due to the good dispersal capabilities of vent endemic macrofauna and vent endemic dirivultid copepods. At vents, 42% of the pre-eruption meio- and 39% of macrofaunal species had returned. In addition, some new species not evident prior to the eruption were found. At the tubeworm site Tica, a total of 26

  8. Assessing the atmospheric and climatic effects of basaltic fissure eruptions. A case study Nornahraun, North Iceland, 2014-2015.

    NASA Astrophysics Data System (ADS)

    Gallagher, Catherine; Burton, Kevin; Thordarson, Thorvaldur; Vye-Brown, Charlotte; Brown, Richard

    2015-04-01

    A volcanic eruption's ability to release sulphur gases into the atmosphere is one of the critical factors in assessing their climatic and environmental effects, because it is directly linked to the potential H2SO4 aerosol burden produced [1]. Basaltic fissure eruptions loft large amounts of sulphur into the atmosphere because of the efficient degassing of volatiles and halogens from the magma at the vent [2-4] coupled with the high sulphur yield of basaltic magma. The common nature of this style of eruption and its products, regardless of magnitude, means that our understanding of the exact processes which influence atmospheric chemistry and environmental impact is very important. The Nornahraun fissure eruption in North Iceland that began on the 31st August 2014, has quickly become one of the best documented eruptions of its kind, through systematic monitoring and sampling by the Institute of Earth Sciences eruption team and The Icelandic Meteorological Office. As a result it is an excellent modern analogue for historic or ancient basaltic fissure eruptions, for which the amount of degassing can only be estimated through petrological and geochemical methods. It also serves as a timely testing platform for novel geochemical proxies. This study uses the exceptional sensitivity of the 187Os-187Re radiogenic system to the presence of crustal material [5], and highly siderophile stable isotopes Cu, Zn and S to indicate the chemistry and degassing of the melt carrying S to the surface. The geochemical isotopic proxies will be tested using established petrological methods and gas emission data. This study concentrates on determining the following key parameters: (1) The source of volatiles in the magma indicated though the pressure dependence of S solubility. (2) The mechanism of aerosol and gas release into the atmosphere is dictated both by the chemistry of the melt that controls the S species (H2S, SO2 or FeS2) present [6], and by the mechanism of transfer. (3) The

  9. Enamel fusion using a carbon dioxide laser: A technique for sealing pits and fissures

    SciTech Connect

    Walsh, L.J.; Perham, S.J. )

    1991-05-01

    The well-established enhanced resistance of lased enamel to demineralization is the basis for clinical application of the carbon dioxide laser to caries prevention. This in vitro study examined the effect of focused infrared laser radiation on sound enamel and early pit and fissure caries. Low power levels (2-5 W) induced localized melting and resolidification of enamel with little surface destruction. For sound fissures, fusion of enamel from the lateral walls of the fissure eliminated the fissure space, providing a sealant effect; while in carious fissures, carious enamel was vaporized and adjacent sound enamel fused to partially eliminate the defect. The technique for enamel fusion using CO2 lasers has potential application for sealing pits and fissures and producing physicochemical alterations in enamel which may have preventive benefits.

  10. Tectonic and magmatic controls on the location of post-subduction monogenetic volcanoes in Baja California, Mexico, revealed through spatial analysis of eruptive vents

    NASA Astrophysics Data System (ADS)

    Germa, Aurélie; Connor, Laura J.; Cañon-Tapia, Edgardo; Le Corvec, Nicolas

    2013-12-01

    Post-subduction (12.5 Ma to less than 1 Ma) monogenetic volcanism on the Baja California peninsula, Mexico, formed one of the densest intra-continental areas of eruptive vents on Earth. It includes about 900 vents within an area ˜700 km long (N-S) and 70 to 150 km wide (W-E). This study shows that post-subduction volcanic activity was distributed along this arc and that modes exist in the volcano distribution, indicating that productivity of the magma source region was not uniform along the length of the arc. Vent clustering, vent alignments, and cone elongations were measured within eight monogenetic volcanic fields located along the peninsula. Results indicate that on a regional scale, vent clustering varies from north to south with denser spatial clustering in the north on the order of 1.9 × 10-1 vents/km2 to less dense clustering in the south on the order of 7.8 × 10-2 vents/km2. San Quintin, San Carlos, Jaraguay, and Santa Clara are spatially distinct volcanic fields with higher eruptive vent densities suggesting the existence of individual melt columns that may have persisted over time. In contrast, the San Borja, Vizcaino, San Ignacio, and La Purisima vent fields show lower degrees of vent clustering and no obvious spatial gaps between fields, thus indicating an area of more distributed volcanism. Insight into the lithospheric stress field can be gained from vent alignments and vent elongation measurements. Within the fields located along the extinct, subduction-related volcanic arc, elongation patterns of cinder cones and fissure-fed spatter cones, vent clusters, and vent alignments trend NW-SE and N-S. Within the Santa Clara field, located more to the west within the forearc, elongation patterns of the same volcanic features trend NE-SW. These patterns suggest that magmatism was more focused in the forearc and in the northern part of Baja California than in its southern region. Within the extinct arc, magma ascent created volcano alignments and elongate

  11. Endemic hydrothermal vent species identified in the open ocean seed bank.

    PubMed

    Gonnella, Giorgio; Böhnke, Stefanie; Indenbirken, Daniela; Garbe-Schönberg, Dieter; Seifert, Richard; Mertens, Christian; Kurtz, Stefan; Perner, Mirjam

    2016-01-01

    Hydrothermal vent systems host microbial communities among which several microorganisms have been considered endemic to this type of habitat. It is still unclear how these organisms colonize geographically distant hydrothermal environments. Based on 16S rRNA gene sequences, we compare the bacterial communities of sixteen Atlantic hydrothermal vent samples with our own and publicly available global open ocean samples. Analysing sequences obtained from 63 million 16S rRNA genes, the genera we could identify in the open ocean waters contained 99.9% of the vent reads. This suggests that previously observed vent exclusiveness is, in most cases, probably an artefact of lower sequencing depth. These findings are a further step towards elucidating the role of the open ocean as a seed bank. They can explain the predicament of how species expected to be endemic to vent systems are able to colonize geographically distant hydrothermal habitats and contribute to our understanding of whether 'everything is really everywhere'. PMID:27573109

  12. Evidence for a Chemoautotrophically Based Food Web at Inactive Hydrothermal Vents (Manus Basin)

    NASA Astrophysics Data System (ADS)

    van Dover, C. L.; Erickson, K.; Macko, S.

    2008-12-01

    Hydrothermal vents are ephemeral systems. When venting shuts down, sulfide-dependent taxa die off, and non-vent taxa can colonize the hard substrata. In Manus Basin (Papua New Guinea), where active and inactive sulfide mounds are interspersed, hydroids, cladorhizid sponges, barnacles, and bamboo sponges, and other invertebrate types may occupy inactive sulfide mounds. Carbon and nitrogen isotopic compositions of animals occupying inactive sulfide mounds are consistent with nutritional dependence on either chemoautotrophically or photosynthetically produced organic material, but sulfur isotopic compositions of these animals point to a chemoautotrophic source of sulfur from dissolved sulfide in vent fluids rather than sulfur derived from seawater sulfate through photosynthesis. Given that suspension-feeding and micro- carnivorous invertebrates are the biomass dominants at inactive sulfide mounds, the primary source of chemoautotrophic nutrition is likely suspended particulates and organisms delivered from nearby active vents.

  13. Evidence for a chemoautotrophically based food web at inactive hydrothermal vents (Manus Basin)

    NASA Astrophysics Data System (ADS)

    Erickson, K. L.; Macko, S. A.; Van Dover, C. L.

    2009-09-01

    Hydrothermal vents are ephemeral systems. When venting shuts down, sulfide-dependent taxa die off, and non-vent taxa can colonize the hard substrata. In Manus Basin (Papua New Guinea), where hydrothermally active and inactive sites are interspersed, hydroids, cladorhizid sponges, barnacles, bamboo corals, and other invertebrate types may occupy inactive sites. Carbon and nitrogen isotopic compositions of animals occupying inactive sites are consistent with nutritional dependence on either chemoautotrophically or photosynthetically produced organic material, but sulfur isotopic compositions of these animals point to a chemoautotrophic source of sulfur from dissolved sulfide in vent fluids rather than sulfur derived from seawater sulfate through photosynthesis. Given that suspension-feeding and micro-carnivorous invertebrates are the biomass dominants at inactive sites, the primary source of chemoautotrophic nutrition is likely suspended particulates and organisms delivered from nearby active vents.

  14. Joints, fissures, and voids in rhyolite welded ash-flow tuff at Teton damsite, Idaho

    USGS Publications Warehouse

    Prostka, Harold J.

    1977-01-01

    Several kinds of joints, fissures, and voids are present in densely welded rhyolite ash-flow tuff at Teton damsite. Older fissures and voids probably were formed in the ash-flow sheet during secondary flowage, which probably was caused by differential compaction or settling over irregular topography. The younger, more abundant fissures are mostly steep cooling joints that probably have been opened farther by horizontal tectonic extension and gravitational creep, perhaps aided by lateral stress relief.

  15. Temporal change in megafauna at the Rose Garden hydrothermal vent (Galapagos Rift; eastern tropical Pacific)

    NASA Astrophysics Data System (ADS)

    Hessler, Robert R.; Smithey, William M.; Boudrias, Michel A.; Keller, Clifford H.; Lutz, Richard A.; Childress, James J.

    1988-10-01

    Hydrothermal vent communities must undergo substantial temporal change because of their dynamic physical milieu. This was verified in March 1985, when the Rose Garden hydrothermal vent on the Galapagos Rift was revisited after 5 1/4 years' absence. Comparison of photographs from the two visits revealed considerable faunal change. Among the hosts to chemoautotrophic bacteria, vestimentiferans were reduced from dominance to very low numbers. The mytilid was now extremely abundant and dominated vent openings. Vesicomyids also were more abundant. In general, vent-field suspension feeders had declined; anemones were distinctly less abundant, and siphonophores and enteropneusts were virtually absent. The decline of serpulids was likely, but less obvious. Of the mobile scavengers and carnivores, both galatheids and whelks were distincly more common. These community changes appear to result from both continuing recruitment and changes in the physical milieu. While the growth of some populations could have resulted from expanding opportunities, the population of at least one, the vesicomyid, had not achieved carrying capacity in 1979, and this could have pertained to others as well. The decrease of vestimentiferans may have been caused by declining vent-water flux, a process that would favor mytilids, or more complete vent-water filtration by the mytilids themselves. The same factors also could explain the reduction of vent-field filter feeders. These observations suggest that early stages in the cycle of Galapagos-type vent communities are likely to be dominated by vestimentiferans, but that bivalves will replace them with time.

  16. Comparative study of vent and seep macrofaunal communities in the Guaymas Basin

    NASA Astrophysics Data System (ADS)

    Portail, M.; Olu, K.; Escobar-Briones, E.; Caprais, J. C.; Menot, L.; Waeles, M.; Cruaud, P.; Sarradin, P. M.; Godfroy, A.; Sarrazin, J.

    2015-09-01

    Understanding the ecological processes and connectivity of chemosynthetic deep-sea ecosystems requires comparative studies. In the Guaymas Basin (Gulf of California, Mexico), the presence of seeps and vents in the absence of a biogeographic barrier, and comparable sedimentary settings and depths offers a unique opportunity to assess the role of ecosystem-specific environmental conditions on macrofaunal communities. Six seep and four vent assemblages were studied, three of which were characterised by common major foundation taxa: vesicomyid bivalves, siboglinid tubeworms and microbial mats. Macrofaunal community structure at the family level showed that density, diversity and composition patterns were primarily shaped by seep- and vent-common abiotic factors including methane and hydrogen sulfide concentrations, whereas vent environmental specificities (higher temperature, higher metal concentrations and lower pH) were not significant. The type of substratum and the heterogeneity provided by foundation species were identified as additional structuring factors and their roles were found to vary according to fluid regimes. At the family level, seep and vent similarity reached at least 58 %. All vent families were found at seeps and each seep-specific family displayed low relative abundances (< 5 %). Moreover, 85 % of the identified species among dominant families were shared between seep and vent ecosystems. This study provides further support to the hypothesis of continuity among deep-sea seep and vent ecosystems.

  17. Caries-preventive effect of fissure sealants: a systematic review.

    PubMed

    Mejàre, Ingegerd; Lingström, Peter; Petersson, Lars G; Holm, Anna-Karin; Twetman, Svante; Källestål, Carina; Nordenram, Gunilla; Lagerlöf, Folke; Söder, Birgitta; Norlund, Anders; Axelsson, Susanna; Dahlgren, Helena

    2003-12-01

    The objectives of this study were to evaluate systematically the evidence of the caries-preventive effect of fissure sealing of occlusal tooth surfaces and to examine factors potentially modifying the effect. The search strategies included electronic databases, reference lists of articles, and selected textbooks. Inclusion criteria were randomized or quasi-randomized clinical trials or controlled clinical trials comparing fissure sealing with no treatment or another preventive treatment in children up to 14 years of age at the start; the outcome measure was caries increment; the diagnostic criteria had been described; and the follow-up time was at least 2 years. Inclusion decisions were taken and grading of the studies was done independently by two of the authors. The main measure of effect was relative risk reduction. Thirteen studies using resin-based or glass ionomer sealant materials were included in the final analysis. The results showed that most studies were performed during the 1970s and a single application had been utilized. The relative caries risk reduction pooled estimate of resin-based sealants on permanent 1st molars was 33% (relative risk = 0.67; CI = 0.55-0.83). The effect depended on retention of the sealant. In conclusion, the review suggests limited evidence that fissure sealing of 1st permanent molars with resin-based materials has a caries-preventive effect. The evidence is incomplete for permanent 2nd molars, premolars and primary molars and for glass ionomer cements. Overall, there remains a need for further trials of high quality, particularly in child populations with a low and a high caries risk, respectively. PMID:14960003

  18. Bonding Agents in Pit and Fissure Sealants: A Review

    PubMed Central

    Das, Usha Mohan; G, Suma

    2009-01-01

    Dental adhesive systems used for bonding dental resins to enamel and dentin have evolved through several "generations," with changes in chemistry, mechanism, number of bottles, application technique, and clinical effectiveness. The trend in the latest generation of dental bonding systems is to reduce the number of components and clinical placement steps. The introduction of i bond, a single-bottle dental adhesive system, is the latest of the new generation materials, and combines etchant, adhesive, and desensitizer in one component. This paper describes different dentin bonding agents, its evolution, mechanism of action and different commercially available dentin bonding agents and their role in the retention of pit and fissure sealant. PMID:25206115

  19. Sylvian fissure epidermoid cyst presenting with intention tremor

    PubMed Central

    Shah, Abhidha; Makkiyah, Feda; Goel, Atul

    2016-01-01

    Epidermoid tumors are benign tumors which contain keratin, cellular debris, and cholesterol, and are lined with stratified squamous epithelium. They grow in discreet silence sustained over a multitude of years. The tumors most commonly present with headache and seizures. We report the case of a 24-year-old male with a large sylvian fissure epidermoid tumor who presented with intention tremor. The patient was operated, and a near-total excision of the tumor was performed with a resolution of the tremor. PMID:27057232

  20. Fluoride release and uptake abilities of different fissure sealants

    PubMed Central

    Andenna, Gianluigi; Ceci, Matteo; Beltrami, Riccardo; Colombo, Marco; Cucca, Lucia

    2016-01-01

    Background The long-term capability of resin sealants and glass ionomer cements to release fluoride is associated to a reduction in pit and fissure caries. The regular use of fluoride varnishes/toothpastes can result in the absorption of fluoride into the sealant. The objective of the present study was to assess the fluoride release/uptake capacities of different fissure sealants. Material and Methods Three different fissure sealants (Fuji Triage/GC, Fissurit FX/Voco and Grandio Seal/Voco) were examined. Ten discs of each material were prepared. Each disc was incubated with distilled water and then the solution analyzed for diluted for fluoride concentration, using a combination of fluoride electrode (OrionGP 1 S/N 13824, Orion Research Inc, Boston, MA, USA) connected to an expandable ion analyzer (Orion 720A, Orion Research Inc, Boston, MA, USA). Standard curves between 1 and 100 ppm F- were used to calibrate the electrode. Cumulative fluoride release was measured on days 1, 2, 3, 5, 7, 21, 35 and 49, then two different fluoride varnishes/pastes (Profluorid Varnish/Voco, MI Paste Plus/GC), were applied to the sealants tested, and fluoride release (after reuptake) was measured on days 56, 70 and 84. Results Kruskal Wallis test confirmed significant differences in fluoride release between Fuji Triage/GC and Fissurit FX/Voco and Grandio Seal/Voco from day 1 (P < 0.001). The application of fluoride varnish Profluorid Varnish enhanced the fluoride release for all sealants (P < 0.05). MI Paste Plus enhanced the fluoride release for all sealants except for Fuji Triage/GC (P > 0.05). Conclusions The GIC-based sealant (Fuji Triage/GC) released significantly more fluoride than the resin sealants tested. The exposure to the fluoridated varnish (Profluorid Varnish) significantly recharged the sealants tested more than the CPP-ACPF toothpaste (MI Paste Plus). Key words:Fissure sealants, fluoride release, fluoride uptake, glass ionomer cements. PMID:27398179

  1. Fissure sealants: Knowledge and practice of Yemeni dental practitioners

    PubMed Central

    Al-Maweri, Sadeq Ali; Al-Jamaei, Aisha Ahmed; Halboub, Esam Saleh; Al-Soneidar, Walid Ahmed; Tarakji, Bassel; Alsalhani, Anas

    2016-01-01

    Objectives This study was conducted to evaluate Yemeni dental practitioners' knowledge and practices concerning fissure sealants. Materials and Methods: A modified questionnaire consisted of 25-items was distributed to 500 dentists working in Sana'a City. Descriptive statistics and Chi-square/Fisher's exact tests were used for statistical analyses. Results: The response rate was 74%. Most of the respondents were male (61.3%), general practitioners (84.2%), and had <5 years of clinical experience (48.3%). The respondents showed a reasonable level of knowledge about sealants, with the majority (88%) believed that there is strong scientific evidence about fissure sealants effectiveness and around 90% showed a good understanding of sealant placement instructions. On the other hand, respondents showed insufficient knowledge about sealants clinical practice. Conclusion: Although a high proportion of dental practitioners showed adequate knowledge about dental sealant, following guidelines and standardized procedures in clinical practice is lacking. These emphasize the need for regular continuing education courses for dental professional. PMID:27095903

  2. 40 CFR 65.62 - Process vent group determination.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., or Group 2B) for each process vent. Group 1 process vents require control, and Group 2A and 2B... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Process vent group determination. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Process Vents § 65.62 Process vent group determination. (a)...

  3. 40 CFR 65.62 - Process vent group determination.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., or Group 2B) for each process vent. Group 1 process vents require control, and Group 2A and 2B... 40 Protection of Environment 16 2012-07-01 2012-07-01 false Process vent group determination. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Process Vents § 65.62 Process vent group determination. (a)...

  4. 40 CFR 65.62 - Process vent group determination.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., or Group 2B) for each process vent. Group 1 process vents require control, and Group 2A and 2B... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Process vent group determination. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Process Vents § 65.62 Process vent group determination. (a)...

  5. 40 CFR 65.62 - Process vent group determination.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., or Group 2B) for each process vent. Group 1 process vents require control, and Group 2A and 2B... 40 Protection of Environment 16 2013-07-01 2013-07-01 false Process vent group determination. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Process Vents § 65.62 Process vent group determination. (a)...

  6. Mapping radiating graben-fissure systems and pit crater chains on Venus

    NASA Astrophysics Data System (ADS)

    Davey, Sarah

    This study has mapped two types of extensional tectono-magmatic structures including radiating graben-fissure systems (RGFS) in the Idunn Mons and Mielikki Mons study areas, and pit crater chains in Idunn Mons, Themis Regio, Ulfrun Regio, and Ganiki Planitia on Venus. The areas selected to map RGFS host high emissivity anomalies focused on a single volcano and are proposed to reflect younger lava flows which might have occurred as recently as 250 ka. A relative chronology of RGFS is determined using cross-cutting relationships between interacting systems and surface geology. The Idunn Mons high emissivity anomaly is host to the youngest magmatic and volcanic activity, while the Mielikki Mons high emissivity anomaly is not the youngest. Hierarchical clusters of pit crater chains are predominantly focused on RGFS and coronae. It is hypothesized that hierarchical clustering is due to a lithology related variable as lithology may dictate how tensile stress is expressed.

  7. Mineralization of Alvinella polychaete tubes at hydrothermal vents.

    PubMed

    Georgieva, M N; Little, C T S; Ball, A D; Glover, A G

    2015-03-01

    Alvinellid polychaete worms form multilayered organic tubes in the hottest and most rapidly growing areas of deep-sea hydrothermal vent chimneys. Over short periods of time, these tubes can become entirely mineralized within this environment. Documenting the nature of this process in terms of the stages of mineralization, as well as the mineral textures and end products that result, is essential for our understanding of the fossilization of polychaetes at hydrothermal vents. Here, we report in detail the full mineralization of Alvinella spp. tubes collected from the East Pacific Rise, determined through the use of a wide range of imaging and analytical techniques. We propose a new model for tube mineralization, whereby mineralization begins as templating of tube layer and sublayer surfaces and results in fully mineralized tubes comprised of multiple concentric, colloform, pyrite bands. Silica appeared to preserve organic tube layers in some samples. Fine-scale features such as protein fibres, extracellular polymeric substances and two types of filamentous microbial colonies were also found to be well preserved within a subset of the tubes. The fully mineralized Alvinella spp. tubes do not closely resemble known ancient hydrothermal vent tube fossils, corroborating molecular evidence suggesting that the alvinellids are a relatively recent polychaete lineage. We also compare pyrite and silica preservation of organic tissues within hydrothermal vents to soft tissue preservation in sediments and hot springs. PMID:25556400

  8. Mineralization of Alvinella polychaete tubes at hydrothermal vents

    PubMed Central

    Georgieva, M N; Little, C T S; Ball, A D; Glover, A G

    2015-01-01

    Alvinellid polychaete worms form multilayered organic tubes in the hottest and most rapidly growing areas of deep-sea hydrothermal vent chimneys. Over short periods of time, these tubes can become entirely mineralized within this environment. Documenting the nature of this process in terms of the stages of mineralization, as well as the mineral textures and end products that result, is essential for our understanding of the fossilization of polychaetes at hydrothermal vents. Here, we report in detail the full mineralization of Alvinella spp. tubes collected from the East Pacific Rise, determined through the use of a wide range of imaging and analytical techniques. We propose a new model for tube mineralization, whereby mineralization begins as templating of tube layer and sublayer surfaces and results in fully mineralized tubes comprised of multiple concentric, colloform, pyrite bands. Silica appeared to preserve organic tube layers in some samples. Fine-scale features such as protein fibres, extracellular polymeric substances and two types of filamentous microbial colonies were also found to be well preserved within a subset of the tubes. The fully mineralized Alvinella spp. tubes do not closely resemble known ancient hydrothermal vent tube fossils, corroborating molecular evidence suggesting that the alvinellids are a relatively recent polychaete lineage. We also compare pyrite and silica preservation of organic tissues within hydrothermal vents to soft tissue preservation in sediments and hot springs. PMID:25556400

  9. Explosive Volcanic Eruptions from Linear Vents on Earth, Venus and Mars: Comparisons with Circular Vent Eruptions

    NASA Technical Reports Server (NTRS)

    Glaze, Lori S.; Baloga, Stephen M.; Wimert, Jesse

    2010-01-01

    Conditions required to support buoyant convective plumes are investigated for explosive volcanic eruptions from circular and linear vents on Earth, Venus, and Mars. Vent geometry (linear versus circular) plays a significant role in the ability of an explosive eruption to sustain a buoyant plume. On Earth, linear and circular vent eruptions are both capable of driving buoyant plumes to equivalent maximum rise heights, however, linear vent plumes are more sensitive to vent size. For analogous mass eruption rates, linear vent plumes surpass circular vent plumes in entrainment efficiency approximately when L(sub o) > 3r(sub o) owing to the larger entrainment area relative to the control volume. Relative to circular vents, linear vents on Venus favor column collapse and the formation of pyroclastic flows because the range of conditions required to establish and sustain buoyancy is narrow. When buoyancy can be sustained, however, maximum plume heights exceed those from circular vents. For current atmospheric conditions on Mars, linear vent eruptions are capable of injecting volcanic material slightly higher than analogous circular vent eruptions. However, both geometries are more likely to produce pyroclastic fountains, as opposed to convective plumes, owing to the low density atmosphere. Due to the atmospheric density profile and water content on Earth, explosive eruptions enjoy favorable conditions for producing sustained buoyant columns, while pyroclastic flows would be relatively more prevalent on Venus and Mars. These results have implications for the injection and dispersal of particulates into the planetary atmosphere and the ability to interpret the geologic record of planetary volcanism.

  10. Fracture mechanical behavior of red sandstone containing a single fissure and two parallel fissures after exposure to different high temperature treatments

    NASA Astrophysics Data System (ADS)

    Yang, Sheng-Qi; Jing, Hong-Wen; Huang, Yan-Hua; Ranjith, P. G.; Jiao, Yu-Yong

    2014-12-01

    A detailed understanding of the brittle deformation behavior of sandstone containing pre-existing flaws at elevated temperatures is a key concern in underground engineering. In this research, uniaxial compression tests were performed to evaluate the effect of high temperature treatments (300, 600 or 900 °C) on the strength, deformability and fracture coalescence behavior of a sandstone containing either a single fissure or two parallel fissures. All experiments focused on rectangular prismatic (80 × 160 × 30 mm) specimens of red sandstone. Constant strain rate experiments were performed on either: (1) specimens that contained a single 2 mm-wide fissure or (2) specimens that contained two 2 mm-wide parallel fissures. The specimens containing either one or two fissures were either left at room temperature (i.e., no heat treatment), or heat treated to 300, 600 or 900 °C prior to experimentation. The results demonstrated that, in all cases, the strength and stiffness of red sandstone was increased at 300 °C, before decreasing up to our maximum temperature of 900 °C. However, the peak strain at failure always showed an increase when the temperature was increased. The crack initiation, propagation and coalescence process were monitored during the deformation using both photographic monitoring and acoustic emission (AE) monitoring techniques. The monitoring results showed that the cracking process depended on both the fissure geometry and the heat treatment temperature. The potential mechanisms causing the differences in the mechanical behavior observed with increasing temperature are discussed, as is the influence of the single fissure and the two parallel fissures on the crack evolution process. These results are important and valuable to understand the fracture mechanism of rock engineering in deep underground mining excavations and nuclear waste depositories.

  11. 21 CFR 872.3765 - Pit and fissure sealant and conditioner.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Pit and fissure sealant and conditioner. 872.3765 Section 872.3765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3765 Pit and fissure sealant...

  12. 21 CFR 872.3765 - Pit and fissure sealant and conditioner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pit and fissure sealant and conditioner. 872.3765 Section 872.3765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3765 Pit and fissure sealant...

  13. 21 CFR 872.3765 - Pit and fissure sealant and conditioner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pit and fissure sealant and conditioner. 872.3765 Section 872.3765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3765 Pit and fissure sealant...

  14. 21 CFR 872.3765 - Pit and fissure sealant and conditioner.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pit and fissure sealant and conditioner. 872.3765 Section 872.3765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3765 Pit and fissure sealant...

  15. Response to early generation selection for resistance to rice kernel fissuring

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The value of milled rice (Oryza sativa L.) depends on the percent whole versus broken kernels after milling. Kernel fissures caused by pre- or post-harvest stresses are the leading cause of breakage upon milling. ‘Cypress’ is known to be more fissure resistant (FR) than most cultivars, but breeding ...

  16. Early screening of recombinant inbred lines for fissure resistance in non-semidwarf rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice (Oryza sativa L.) kernel fissuring poses a major problem for both rice farmers and millers. It results in the decreased value of milled rice because of the increase in the percentage of broken kernels associated with fissuring. This study employs the use of fine mapping to increase the genetic ...

  17. Holocene intracontinental deformation of the northern North China Plain: Evidence of tectonic ground fissures

    NASA Astrophysics Data System (ADS)

    Xu, Liqing; Li, Sanzhong; Cao, Xianzhi; Somerville, I. D.; Suo, Yanhui; Liu, Xin; Dai, Liming; Zhao, Shujuan; Guo, Lingli; Wang, Pengcheng; Cao, Huahua

    2016-04-01

    Following the collecting and analyzing of field data on the geometry and kinematics characteristics of ground fissures in the northern North China Plain (NNCP), this paper shows that en échelon ground fissures or tectonic ground fissures with a length of several meters to tens of kilometers extending along active faults are possibly controlled by underlying active faults. There are two groups of tectonic ground fissures developed in the NNCP. One group consists of ENE-trending "right-stepping" ground fissures, some of which have a component of sinistral motion. The other group is NNE-trending "left-stepping" ground fissures with dextral motion. A large amount of data from trenches, boreholes and seismic exploration reflect that they are active-faulting-related. The NNW-trending regional extensional stress field and the reactivation of pre-existing faults are the major factors controlling ground fissures. Data from the Quaternary sedimentary records, deep incised valleys, the distribution of earthquakes and ground fissures, and our field work show that the Holocene intracontinental deformation of the NNCP is characterized by intense faulting and northwestward tilting, which may be related to a NNW-SSE-oriented tensional stress field in the shallow crust and asthenospheric upwelling in the mantle.

  18. Preserving rice quality: fine mapping and introgressing a fissure resistance locus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice (Oryza sativa L.) kernel fissuring is a major concern of both rice producers and millers. Fissures are small cracks in the rice kernels that increase the percentage of breakage among the kernels when they are transported and milled, which decreases the value of processed rice. This study employ...

  19. First Active Hydrothermal Vent Fields Discovered at the Equatorial Southern East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Tao, C.; Lin, J.; Wu, G.; German, C. R.; Yoerger, D. R.; Chen, Y. J.; Guo, S.; Zeng, Z.; Han, X.; Zhou, N.; Li, J.; Xia, S.; Wang, H.; Ding, T.; Gao, S.; Qian, X.; Cui, R.; Zhou, J.; Ye, D.; Zhang8, Y.; Zhang, D.; Li, L.; Zhang, X.; Li, Y.; Wu, X.; Li, S.; He, Y.; Huang, W.; Wang, Y.; Wang, T.; Li, X.; Wang, K.; Gai, Y.; Science Party, D.; Baker, E. T.; Nakamura14, K.

    2008-12-01

    The third leg of the 2008 Chinese DY115-20 expedition on board R/V Dayangyihao has successfully discovered, for the first time, active hydrothermal vent fields on the fast-spreading Southern East Pacific Rise (SEPR) near the equator. This expedition follows the work of a 2005 expedition by R/V Dayangyihao, during which water column turbidity anomalies were measured in the region. The newly discovered vent fields are located along a 22-km-long ridge segment of the SEPR at 102.655°W/2.22°S, 102.646°W/2.152°S, 102.619°W/2.078°S, and 102.62°W/2.02°S, respectively, as well as on an off-axial volcano near 102.456°W/1.369°S. A significant portion of the activity appears to be concentrated along the edges of a seafloor fissure system. Furthermore, water column turbidity anomalies were observed over off-axis volcanoes near 102.827°W/2.084°S and 102.58°W/2.019°S. Video footage of the vent fields and water column turbidity, temperature, and methane anomalies were recorded by a deep-towed integrated system consisting of video, still camera, CTD, and ADCP, and MAPR and METS sensors. Two active hydrothermal fields at 2.217°S and 2.023°S were then extensively photographed and surveyed using the autonomous underwater vehicle ABE of the Woods Hole Oceanographic Institution (WHOI). Four samples of hydrothermal chimneys were successfully obtained by a TV-guided grab in three locations, showing evidence of high-temperature hydrothermal venting.

  20. 46 CFR 151.15-5 - Venting.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Pressure-vacuum venting. A normally closed venting system fitted with a device to automatically limit the pressure or vacuum in the tank to design limits. Pressure-vacuum relief valves shall comply with the... devices in accordance with the requirements of § 54.15-13 of this chapter. (2) When a...

  1. A bestiary of ordinary vent activities at Stromboli (and what it tells us about vent conditions)

    NASA Astrophysics Data System (ADS)

    Gaudin, Damien; Taddeucci, Jacopo; Scarlato, Piergiorgio

    2015-04-01

    Normal active degassing at Stromboli (Aeolian Islands, Italy) is traditionally divided in two classes. Puffing correspond to the frequent (~1 Hz) release of small gas pockets (0.5 - 1 m of diameter) at low exit velocities (5 - 15 m/s). Whereas, Strombolian explosions occur at a frequency of 1 - 10 per hour, and are characterized the ejection of bombs and/or ash at high velocities (50 - 400 m/s). In order to get a broader overview of two types of degassing, we used a thermal high speed FLIR SC655 camera to monitor the temperature anomalies generated by the expelled gas, ash, and/or bombs. The enhanced time and spatial resolutions of the camera (200 frames per second, 15 cm wide pixels) enables to use numerical algorithms to distinguish and characterize individual ejection events. In particular, for each explosion and puff, we compute the temperature, the volume, the exit point and the rise velocities of the expelled material. These values, as well as the frequency of the release events, are used to portray a total of 12 vent activities, observed during three field campaigns in 2012, 2013 and 2014. Sustained puffing was visible on 7 cases, with an intensity ranging on at least two orders of magnitude. Although the released gas volume is sometimes highly variable, on some cases, constant sized puffs allows to define a typical discharge frequency ranging between 0.4 and 1.5 Hz. Regular Strombolian explosions, with various duration, intensity and ash contents, are reported in 6 cases, 2 of them simultaneously presenting a puffing activity. In some cases, we noticed modifications of the vent activity just before the explosions. These precursors, usually lasting about 1 second but occasionally reaching 10 seconds, can be sorted into 1) increase of the puffing activity ; 2) emission of gas plumes ; 3) inflation of the visible vent surface. Finally, one vent activity was hybrid between puffing and Strombolian explosions, with frequent explosions (1 Hz) ejecting numerous

  2. Groundwater-Mining-Induced Subsidence and Earth Fissures in Cedar Valley, Southwestern Utah

    NASA Astrophysics Data System (ADS)

    Knudsen, T. R.; Inkenbrandt, P.; Lund, W. R.; Lowe, M.; Bowman, S. D.

    2014-12-01

    Groundwater pumping in excess of recharge (groundwater mining) has lowered the potentiometric surface in Cedar Valley, southwestern Utah, by as much as 114 feet since 1939. Lowering the potentiometric surface (head decline) has caused permanent compaction of fine-grained sediments of the Cedar Valley aquifer. Recently acquired interferometric synthetic aperture radar (InSAR) imagery shows that land subsidence is occurring over an ~100 square-mile area, including two pronounced subsidence bowls in the northeastern (Enoch graben) and southwestern (Quichapa Lake area) parts of the valley. A lack of accurate historical benchmark elevation data over much of the valley prevents detailed long-term quantification of subsidence. In response to the land subsidence, earth fissures have formed along the margins of the Enoch graben and north and west of Quichapa Lake. Our initial inventory of Cedar Valley fissures, which relied on aerial-photography analysis, identified 3.9 miles of fissures in 2009. With newly acquired light detection and ranging (LiDAR) coverage in 2011, we more than doubled the total length of mapped fissures to 8.3 miles. Fissures on the west side of the Enoch graben exhibit ongoing vertical surface displacement with rates as high as 1.7 inches/year. The largest Enoch-graben-west fissure has displaced street surfaces, curb and gutter, and sidewalks, and has reversed the flow direction of a sewer line in a partially developed subdivision. Several Cedar Valley fissures are closely associated with, and in some places coincident with, mapped Quaternary faults. While the majority of Cedar Valley fissures are mapped in agricultural areas, continued groundwater mining and resultant subsidence will likely cause existing fissures to lengthen and new fissures to form that may eventually impact other developed areas of the valley.

  3. Turbulent atmospheric plumes above line sources with an application to volcanic fissure eruptions on the terrestrial planets

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.

    1989-01-01

    The theory of turbulent plumes maintained above steady line sources of buoyancy is worked out in detail within the limitations of Taylor's entrainment assumption. It is applied to the structure of a pure plume injected into a stably stratified atmosphere. Volcanic basalt eruptions that develop from long, narrow vents create line source plumes, which rise well above the magmatic fire fountains playing near the ground level. The eruption of Laki in 1783 may provide an example of this style of eruption. Flood basalts are more ancient examples. Evidence of enormous fissure eruptions that occurred in the past on Mars and Venus also exists. Owing to the different properties of the atmospheres on these two planets from those on the earth, heights of line source plumes are expected to vary in the ratios 1:6:0.6 (earth:Mars:Venus). It is very unlikely that the observed increase of sulfur dioxide above the Venusian cloud deck in 1978 could have been due to a line source volcanic eruption, even if it had been a flood basalt eruption.

  4. Exploring rock fissures: does a specialized root morphology explain endemism on granite outcrops?

    PubMed Central

    Poot, Pieter; Hopper, Stephen D.; van Diggelen, Josepha M.H.

    2012-01-01

    Background and Aims Worldwide, many plant species are confined to open, shallow-soil, rocky habitats. Although several hypotheses have been proposed to explain this habitat specificity, none has been convincing. We suggest that the high level of endemism on shallow soils is related to the edaphic specialization needed to survive in these often extremely drought-prone habitats. Previous research has shown that species endemic to ironstone communities in SW Australia have a specialized root morphology that enhances their chance to access fissures in the underlying rock. Here we test the generality of these findings for species that are confined to a shallow-soil habitat that is of much greater global significance: granite outcrops. Methods We compared temporal and spatial root growth and allocation of three endemic woody perennials of SW Australian granite outcrop communities with those of congeners occurring on nearby deeper soils. Seedlings of all species were grown in 1·2 m long custom-made containers with a transparent bottom that allowed monitoring of root growth over time. Key Results The granite outcrop endemics mostly differed in a predictable way from their congeners from deeper soils. They generally invested a larger portion of their biomass in roots, distributed their roots faster and more evenly over the container and had a lower specific root length. In different species pairs the outcrop endemics achieved their apparent advantage by a different combination of the aforementioned traits. Conclusions Our results are consistent with earlier work, indicating that species restricted to different types of drought-prone shallow-soil communities have undergone similar selection pressures. Although adaptive in their own habitat in terms of obtaining access to fissures in the underlying rock, these root system traits are likely to be maladaptive in deeper soil habitats. Therefore, our results may provide an explanation for the narrow endemism of many shallow

  5. Filtered venting considerations in the United States

    SciTech Connect

    Dallman, R.J.; Hulman, L.G.; Kudrick, J.

    1988-01-01

    The capability to vent with or without attenuation of fission products exists at some US facilities. In addition, two utilities have proposed enhanced capabilities, and generic enhancements are being considered under a regulatory evaluation of severe accident vulnerabilities at all US commercial reactors. The paper 1) summarizes the history of filtered venting in the US including significant past and proposed related research; 2) summarizes an assessment of the positive and negative safety aspects of venting for a class of 24 US reactors (BWR Mark I), and 3) discusses the regulatory assessments being made of filtered venting as a severe accident management strategy, including potential attributes of both accident prevention and mitigation associated with venting. Lastly, based on a review of available literature on European initiatives, questions are raised; answers to which would significantly help US evaluations. 10 refs., 2 tabs.

  6. Low Gravity venting of Refrigerant 11

    NASA Technical Reports Server (NTRS)

    Labus, T. L.; Aydelott, J. C.; Lacovic, R. F.

    1972-01-01

    An experimental investigation was conducted in a five-second zero gravity facility to examine the effects of venting initially saturated Refrigerant 11 from a cylindrical container (15-cm diameter) under reduced gravitational conditions. The system Bond numbers studied were 0 (weightlessness), 9 and 63; the liquid exhibited a nearly zero-degree contact angle on the container surface. During the venting process, both liquid-vapor interface and liquid bulk vaporization occurred. The temperature of the liquid in the immediate vicinity of the liquid-vapor interface was found to decrease during venting, while the liquid bulk temperature remained constant. Qualitative observations of the effects of system acceleration, vent rate, and vapor volume presented. Quantitative information concerning the ullage pressure decay during low gravity venting is also included.

  7. Evidence not practised: the underutilisation of preventive fissure sealants.

    PubMed

    Bonetti, D L

    2014-04-01

    International and UK professional organisations, Cochrane systematic reviews, and international and UK guidance documents all support the application of preventive fissure sealants (PFSs) as an effective treatment for reducing caries. However, PFSs are well known to be underutilised in primary care. This paper collates data from PFS-relevant studies in Scotland, which has a large population of children at caries risk, to identify the beliefs and factors dentists perceive as influencing their decision not to provide this treatment. This information provides a platform to suggest how to increase the application of PFSs in this region (a standardised audit incorporating evidence-based behaviour change techniques, supplemental guidance on how to implement gold-standard recommendations in practice, training). This may also be relevant outside of Scotland, as well as to the implementation of other evidence-based behaviours in practice. PMID:24722094

  8. Pleistocene microvertebrates from fissure-fillings in Thailand

    NASA Astrophysics Data System (ADS)

    Chaimanee, Yaowalak; Jaeger, Jean-Jacques; Suteethorn, Varavudh

    Microvertebrates (and among them specially, rodents) have contributed to the elaboration of precise biochronological time scales and to the reconstitution of Pleistocene paleoenvironments in several parts of the world (North America, Africa, Europe and Japan). They have been demonstrated to be highly sensitive to climatic changes since they are very sensitive to vegetation changes. Up to now, no data is available for Southeast Asia and very few information is available concerning the nature of climatic changes which affected that part of the tropical world during the Pleistocene. In the past few years, we have discovered several fissure fillings in Thailand yielding numerous remains of microvertebrates which have been extracted by dissolution in acetic acid solution. These deposits are the result of the feeding activity of predators, like owls or diurnal raptors, whose pellets are accumulated in caves or fissures. Eleven localities, located in Central (2), Eastern (1), Western (2) and Peninsular Thailand (6) have been investigated so far. Several rodent species, belonging to 9 genera of Murinae (rats and mice) and 9 genera of Sciuridae (squirrels) have been identified in these localities. The most important differences with the extant representatives often concern the size of the teeth of these fossil species. The meaning of these size differences is not yet clearly understood since they can be attributed either to significant time differences between localities (microevolution) or as the result of size variations related to climatic changes (clinical variations). More data will have to be collected to calibrate the temporal frame. Already, important modification of the geographic distribution of some species have been discovered which testify that during the Pleistocene, significative climatic changes have affected Southeast Asia. For example, Exilisciurus, a squirrel which is presently restricted to Borneo has been recognized in Peninsular Thailand. Also, Iomys

  9. Oil heat venting technology residential heating systems

    SciTech Connect

    Krajewski, R.F.; Celebi, Y.; Strasser, J.

    1991-05-01

    Tests were conducted on two oil-fired space heating appliances (a boiler and a furnace). Instead of using a chimney these appliances were configured to exhaust the combustion products through the side wall of the building (sidewall vent). The products of combustion were extracted mechanically (power-vent) from each of the appliances by using a fan (induced-draft fan) in the vent system. Measurements were made of the time required to clear the appliances of combustion products by running the vent fan after burner shutdown (postpurge). These measurements indicated that one minute of postpurge was sufficient to clear the combustion products. The required postpurge duration was longer when based upon controlling nozzle temperature rise after burner shutdown. This is due to heat soakback from the combustion chamber. In order to hold nozzle temperatures down, the required postpurge period was estimated to be about 3 minutes for the furnace and about 7 minutes for the boiler. Measurements were also made of the off-cycle energy losses due to postpurge duration. Furnaces are more severely impacted by postpurge losses than are boilers. In addition, tests were conducted on two boilers to determine the off-cycle losses due to an actual chimney system. A comparison of these results to those of the side-wall vent tests revealed the need for short postpurge durations to minimize losses. Calculations were made using the DOE test procedure and compared to the results of tests. Experimental results show that direct-vent systems perform as well as chimney-vent systems in terms of off-cycle losses. There is potential for an efficiency advantage for direct-vent over chimney-vent systems if postpurge requirements can be reduced. Initial efforts in developing a computer program for venting design and analysis are described. 7 refs., 39 figs., 4 tabs.

  10. Neotectonic activity at the Giant Gjallar Vent (Norwegian Sea) indicates a future phase of active fluid venting

    NASA Astrophysics Data System (ADS)

    Dumke, Ines; Berndt, Christian; Crutchley, Gareth; Couillard, Mélanie; Gay, Aurélien

    2013-04-01

    The Giant Gjallar Vent (GGV) is a hydrothermal vent complex that formed during the opening of the North Atlantic at about 55 Ma. Sill intrusions into Cretaceous organic-rich sediments led to the production and subsequent vigorous seafloor venting of methane. A later phase of fluid escape occurred in mid-Oligocene times. The GGV is characterised by two pipes of 440 m and 480 m in diameter that reach up to the Base Late Pliocene Unconformity (BLPU) between the Kai and Naust formations. The unconformity is strongly deformed over an area of c. 18,000 km² across the vent, with a positive relief of up to 38 m above the surrounding paleo-seafloor. The overlying sediments of the Naust Formation conformally drape this deformation, smoothing its relief to a maximum of 15 m at the modern seafloor. The sediment drape indicates present inactivity of the vent system, as does the absence of indicators of active fluid escape in the water column during RV METEOR cruise M87-2 in 2012. However, high-resolution 2D seismic and Parasound data from the same cruise, and exploration-type 3D seismic data acquired by Norsk Hydro, show several indications for recent to ongoing activity at the GGV. Beneath the BLPU, strong frequency attenuation and chaotic reflections indicate the presence of free gas. At the edges of the extent of chaotic reflections, subvertical faults cut the unconformity as well as horizons of the lower and middle Naust Formation, suggesting tectonic activity after deposition of these horizons. Neotectonic activity is further indicated by the extensive occurrence of shallow faults apparent in Parasound records in the immediate vicinity of the vent and up to 16 km away. Some of these faults reach the seafloor. The observed deformation and faults may be the result of fluids accumulating beneath the BLPU due to increased loading of the oozy Kai Formation by denser glacigenic Naust sediments. Because of the lower permeability of the Naust Formation, the unconformity acts as a

  11. Discrete element modeling on the crack evolution behavior of brittle sandstone containing three fissures under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Yang, Sheng-Qi; Huang, Yan-Hua; Ranjith, P. G.; Jiao, Yu-Yong; Ji, Jian

    2015-12-01

    Based on experimental results of brittle, intact sandstone under uniaxial compression, the micro-parameters were firstly confirmed by adopting particle flow code (PFC^{2D}). Then, the validation of the simulated models were cross checked with the experimental results of brittle sandstone containing three parallel fissures under uniaxial compression. The simulated results agreed very well with the experimental results, including the peak strength, peak axial strain, and ultimate failure mode. Using the same micro-parameters, the numerical models containing a new geometry of three fissures are constructed to investigate the fissure angle on the fracture mechanical behavior of brittle sandstone under uniaxial compression. The strength and deformation parameters of brittle sandstone containing new three fissures are dependent to the fissure angle. With the increase of the fissure angle, the elastic modulus, the crack damage threshold, and the peak strength of brittle sandstone containing three fissures firstly increase and secondly decrease. But the peak axial strain is nonlinearly related to the fissure angle. In the entire process of deformation, the crack initiation and propagation behavior of brittle sandstone containing three fissures under uniaxial compression are investigated with respect to the fissure angle. Six different crack coalescence modes are identified for brittle sandstone containing three fissures under uniaxial compression. The influence of the fissure angle on the length of crack propagation and crack coalescence stress is evaluated. These investigated conclusions are very important for ensuring the stability and safety of rock engineering with intermittent structures.

  12. Infrasound from the 2007 fissure eruptions of Kīlauea Volcano, Hawai'i

    USGS Publications Warehouse

    Fee, D.; Garces, M.; Orr, T.; Poland, M.

    2011-01-01

    Varied acoustic signals were recorded at Kīlauea Volcano in mid-2007, coincident with dramatic changes in the volcano's activity. Prior to this time period, Pu'u 'Ō'ō crater produced near-continuous infrasonic tremor and was the primary source of degassing and lava effusion at Kīlauea. Collapse and draining of Pu'u 'Ō'ō crater in mid-June produced impulsive infrasonic signals and fluctuations in infrasonic tremor. Fissure eruptions on 19 June and 21 July were clearly located spatially and temporally using infrasound arrays. The 19 June eruption from a fissure approximately mid-way between Kīlauea's summit and Pu'u 'O'o produced infrasound for ~30 minutes-the only observed geophysical signal associated with the fissure opening. The infrasound signal from the 21 July eruption just east of Pu'u 'Ō'ō shows a clear azimuthal progression over time, indicative of fissure propagation over 12.9 hours. The total fissure propagation rate is relatively slow at 164 m/hr, although the fissure system ruptured discontinuously. Individual fissure rupture times are estimated using the acoustic data combined with visual observations.

  13. Modeling of earth fissures caused by land subsidence due to groundwater withdrawal

    NASA Astrophysics Data System (ADS)

    Panda, B. B.; Rucker, M. L.; Fergason, K. C.

    2015-11-01

    Land subsidence and earth fissures are phenomena related to groundwater withdrawal in a sedimentary basin. If the rock basement or basin lithology is irregular, both vertical and horizontal displacements can be induced due to differential settlement and tensile stresses appearing in the soil mass. If the differential settlement is of sufficient magnitude, earth fissuring can occur within tensile zones. The magnitudes of compaction and fissure geometry are closely related to the thickness and skeletal compressibility of fine-grained sediments within the aquifer system. Land subsidence and earth fissuring were modeled by employing a two-dimensional (2-D) coupled seepage and stress-strain finite element analysis. The basin bedrock geometry, lithological variation, measurements of surface displacements, and changes in hydraulic head were the critical input parameter for the subsidence modeling. Simulation results indicate that strain had exceeded the approximate threshold for fissure formation of 0.02 to 0.06 % in the area of the identified fissures. The numerical model was used to predict future subsidence and potential earth fissures for flood control structures within the metro Phoenix area.

  14. Preferential flow in fissured sediments in desert soils related to radioactive waste disposal

    SciTech Connect

    Scanlon, B.R.; Raney, J.A. . Bureau of Economic Geology)

    1992-01-01

    Unsaturated flow in fissured sediments in the Chihuahuan Desert of Texas was examined to determine if these features act as preferred pathways for water and solute transport. Fissures are surface features, or gulleys, that are underlain by fractures filled with sediment derived from surrounding areas. Hydraulic and chemical approaches were used to investigate unsaturated flow processes beneath and adjacent to fissures, and the results were compared with data from surrounding geomorphic systems such as arroyos, ephemeral streams, and interstreams. Typically, high water potentials in surficial sediments result from infiltration of recent precipitation. Below this surficial zone of high water potentials lies a zone of low water potentials that is much thinner beneath the fissure than in adjacent sediments or in sediments beneath ephemeral streams and interstreams. Maximum chloride concentrations in profiles in the near-surface fissured sediments were much lower than those measured in all other geomorphic systems. The corresponding moisture velocities in the fissured sediments ranged from 10 to 70 mm/yr. A tracer experiment demonstrated higher downward water and solute transport in the fracture fill beneath the fissure relative to adjacent sediments. Numerical simulations of the tracer experiment with the computer code TRACR3D reproduced the overall shape of the tracer plume. Sensitivity analyses demonstrated that the tracer plume is most sensitive to spatial variability in soil texture and the corresponding hydraulic parameters. The results from this study suggest that sediments in the fissured area act as preferred pathways in the shallow subsurface because surface runoff is concentrated in the fissures and because underlying fractures and cavities provide avenues for moisture and solute transport.

  15. VOC transport in vented drums containing simulated waste sludge

    SciTech Connect

    Liekhus, K.J.; Gresham, G.L.; Rae, C.; Connolly, M.J.

    1994-02-01

    A model is developed to estimate the volatile organic compound (VOC) concentration in the headspace of the innermost layer of confinement in a lab-scale vented waste drum containing simulated waste sludge. The VOC transport model estimates the concentration using the measured VOC concentration beneath the drum lid and model parameters defined or estimated from process knowledge of drum contents and waste drum configuration. Model parameters include the VOC diffusion characteristic across the filter vent, VOC diffusivity in air, size of opening in the drum liner lid, the type and number of layers of polymer bags surrounding the waste, VOC permeability across the polymer, and the permeable surface area of the polymer bags. Comparison of model and experimental results indicates that the model can accurately estimate VOC concentration in the headspace of the innermost layer of confinement. The model may be useful in estimating the VOC concentration in actual waste drums.

  16. Monitoring arrangement for vented nuclear fuel elements

    DOEpatents

    Campana, Robert J.

    1981-01-01

    In a nuclear fuel reactor core, fuel elements are arranged in a closely packed hexagonal configuration, each fuel element having diametrically opposed vents permitting 180.degree. rotation of the fuel elements to counteract bowing. A grid plate engages the fuel elements and forms passages for communicating sets of three, four or six individual vents with respective monitor lines in order to communicate vented radioactive gases from the fuel elements to suitable monitor means in a manner readily permitting detection of leakage in individual fuel elements.

  17. Hydrogen venting characteristics of commercial carbon-composite filters and applications to TRU waste

    SciTech Connect

    Callis, E.L.; Marshall, R.S.; Cappis, J.H.

    1997-04-01

    The generation of hydrogen (by radiolysis) and of other potentially flammable gases in radioactive wastes which are in contact with hydrogenous materials is a source of concern, both from transportation and on-site storage considerations. Because very little experimental data on the generation and accumulation of hydrogen was available in actual waste materials, work was initiated to experimentally determine factors affecting the concentration of hydrogen in the waste containers, such as the hydrogen generation rate, (G-values) and the rate of loss of hydrogen through packaging and commercial filter-vents, including a new design suitable for plastic bags. This report deals only with the venting aspect of the problem. Hydrogen venting characteristics of two types of commercial carbon-composite filter-vents, and two types of PVC bag closures (heat-sealed and twist-and-tape) were measured. Techniques and equipment were developed to permit measurement of the hydrogen concentration in various layers of actual transuranic (TRU) waste packages, both with and without filter-vents. A test barrel was assembled containing known configuration and amounts of TRU wastes. Measurements of the hydrogen in the headspace verified a hydrogen release model developed by Benchmark Environmental Corporation. These data were used to calculate revised wattage Emits for TRU waste packages incorporating the new bag filter-vent.

  18. Diverse styles of submarine venting on the ultraslow spreading Mid-Cayman Rise

    PubMed Central

    German, C. R.; Bowen, A.; Coleman, M. L.; Honig, D. L.; Huber, J. A.; Jakuba, M. V.; Kinsey, J. C.; Kurz, M. D.; Leroy, S.; McDermott, J. M.; de Lépinay, B. Mercier; Nakamura, K.; Seewald, J. S.; Smith, J. L.; Sylva, S. P.; Van Dover, C. L.; Whitcomb, L. L.; Yoerger, D. R.

    2010-01-01

    Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global mid-ocean ridge remains unexplored for hydrothermal activity. Of particular interest are the world’s ultraslow spreading ridges that were the last to be demonstrated to host high-temperature venting but may host systems particularly relevant to prebiotic chemistry and the origins of life. Here we report evidence for previously unknown, diverse, and very deep hydrothermal vents along the ∼110 km long, ultraslow spreading Mid-Cayman Rise (MCR). Our data indicate that the MCR hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultramafic systems and, at ∼5,000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent types identified here and their relative geographic isolation make the MCR unique in the oceans. These new sites offer prospects for an expanded range of vent-fluid compositions, varieties of abiotic organic chemical synthesis and extremophile microorganisms, and unparalleled faunal biodiversity—all in close proximity. PMID:20660317

  19. Diverse styles of submarine venting on the ultra-slow spreading Mid-Cayman Rise (Invited)

    NASA Astrophysics Data System (ADS)

    German, C. R.; Bowen, A.; Coleman, M. L.; Honig, D. L.; Huber, J. A.; Jakuba, M.; Kinsey, J. C.; Kurz, M. D.; Leroy, S.; McDermott, J.; Mercier de Lepinay, B. F.; Nakamura, K.; Seewald, J.; Smith, J.; Sylva, S.; van Dover, C. L.; Whitcomb, L. L.; Yoerger, D. R.

    2010-12-01

    Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global Mid Ocean Ridge remains unexplored for hydrothermal activity. Of particular interest are the world’s ultra-slow spreading ridges which were the last to be demonstrated to host high-temperature venting, but may host systems particularly relevant to pre-biotic chemistry and the origins of life. Here we report first evidence for diverse and very deep hydrothermal vents along the ~110 km long, ultra-slow spreading Mid-Cayman Rise collected using a combination of CTD-rosette operations and dives of the Hybrid Remotely Operated Vehicle (HROV) Nereus in 2009 followed by shore based work-up of samples for geochemical and microbiological analyses. Our data indicate that the Mid-Cayman Rise hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultra-mafic systems and, at ~5000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent-types identified here and their relative geographic isolation make the Mid-Cayman Rise unique in the oceans. These new sites offer prospects for: an expanded range of vent-fluid compositions; varieties of abiotic organic chemical synthesis and extremophile microorganisms; and unparalleled faunal biodiversity - all in close proximity.

  20. 24 CFR 3280.710 - Venting, ventilation and combustion air.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air...

  1. 24 CFR 3280.710 - Venting, ventilation and combustion air.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air...

  2. 46 CFR 153.362 - Venting system drain.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Venting system drain. 153.362 Section 153.362 Shipping... Systems § 153.362 Venting system drain. Unless a cargo vent system at every point is level or slopes back... system must have a drain valve at each low point (trap) in the vent line....

  3. 14 CFR 125.159 - Vent and drain lines.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Vent and drain lines. 125.159 Section 125... Requirements § 125.159 Vent and drain lines. All vent and drain lines, and their fittings, that are located in... Administrator finds that the rupture or breakage of any vent or drain line may result in a fire hazard....

  4. 40 CFR 65.143 - Closed vent systems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Closed vent systems. 65.143 Section 65...) CONSOLIDATED FEDERAL AIR RULE Closed Vent Systems, Control Devices, and Routing to a Fuel Gas System or a Process § 65.143 Closed vent systems. (a) Closed vent system equipment and operating requirements....

  5. BIOREMEDIATED SOIL VENTING OF LIGHT HYDROCARBONS

    EPA Science Inventory

    The effectiveness and feasibility of bioremediated soil venting of light hydrocarbons in the unsaturated zone was investigated. Degradation mechanics were considered as a one dimensional balance of storage, linear sorption, vertical advection, and Michaelis-Menton kinetics. he re...

  6. Efficient Vent Unloading of Air Compressors

    NASA Technical Reports Server (NTRS)

    Muhonen, Alvin J.

    1987-01-01

    Method for unloading one-and two-stage reciprocating air compressors increases energy efficiency and inhibits deterioration of components. In new unloader configuration, compressor vented to atmosphere on downstream side. Method implemented expeditiously as modification of existing systems.

  7. External Tank GH2 Vent Arm

    NASA Technical Reports Server (NTRS)

    Reichle, G. E.; Glassburn, C. W.

    1985-01-01

    Because the venting of free hydrogen gas to the atmosphere presents an extremely hazardous situation, it was necessary to devise a means for safe, controlled venting of the shuttle external tank gaseous hydrogen during and after liquid hydrogen tank loading. Several design concepts that were considered initially were discarded as unfeasible because of vehicle weight restrictions, high cost, and because the proposed structure was itself deemed a hazard due to the vehicle's nonvertical launch trajectory. These design concepts are discussed. A design employing a support structure/access arm attached to the fixed service structure was finally selected. The various design problems resolved included vent arm disconnect/drop interference, minimizing refurbishment due to launch damage, disconnect reliability, vehicle movement tracking, minimizing vent line pressure drop, and the presence of other vehicle services at the same centralized supply area. Six launches have proven the system to be reliable, efficient, and of nearly zero refurbishment cost.

  8. VentDB: A Global Online Synthesis Database of Seafloor Hydrothermal Spring Geochemistry

    NASA Astrophysics Data System (ADS)

    Mottl, M. J.; Lehnert, K. A.; Johansson, A. K.; Hsu, L.

    2011-12-01

    Chemical data for seafloor hydrothermal springs are fundamental to the study of mid-ocean ridge and seafloor processes, ocean water chemistry, and global geochemical cycles, as well as vent ecosystems and the sub-seafloor biosphere. So far, these data have been accessible only in the scientific literature or in online data catalogs where they are widely dispersed in individual data tables, and are often insufficiently documented for re-use. We have developed VentDB as an online data system for geochemical data for hydrothermal springs that will facilitate access and analysis of these data. VentDB uses the concept and architecture of the popular PetDB database for seafloor igneous and metamorphic rock geochemistry (www.petdb.org) to provide easy and fast access to a global synthesis of seafloor hydrothermal spring geochemical data. The VentDB database contains concentrations of major and trace species, dissolved gases, and radiogenic and isotopic ratios for hydrothermal vents on the seafloor. Further chemical or physical properties of hydrothermal springs can be included in the future if desired. The database comprises both the calculated hydrothermal end-member solution compositions as estimated by extrapolation of the concentrations of individual chemical species to a Mg concentration of zero, and the raw data for hydrothermal solution samples as collected, where available. Data quality is documented by including information for the raw analytical data about the analytical method, precision, and reference material measurements, and quality control parameters for end-member compositions including the lowest Mg measured in any sample, the number of samples and correlation coefficient of the linear regression, and the charge balance for the extrapolated zero-Mg composition. The database also includes information about the sampled locations (geospatial coordinates, vent or vent field names, names of other physiographic features), temperature, flow and vent type

  9. Zero-gravity venting of three refrigerants

    NASA Technical Reports Server (NTRS)

    Labus, T. L.; Aydelott, J. C.; Amling, G. E.

    1974-01-01

    An experimental investigation of venting cylindrical containers partially filled with initially saturated liquids under zero-gravity conditions was conducted in the NASA Lewis Research Center 5-second zero-gravity facility. The effect of interfacial mass transfer on the ullage pressure response during venting was analytically determined, based on a conduction analysis applied to an infinitely planer (flat) liquid-vapor interface. This pressure response was compared with both the experimental results and an adiabatic decompression computation.

  10. Safe venting of ``red oil`` runaway reactions

    SciTech Connect

    Paddleford, D.F.; Fauske, H.K.

    1994-12-21

    Calorimetry testing of Tri-n-butyl phosphate (TBP) saturated with strong nitric acid was performed to determine the relationship between vent size and pressure buildup in the event of a runaway reaction. These experiments show that runaway can occur in an open system, but that even when runaway is induced in the TBP/HN0{sub 3} system, dangerous pressure buildup will be prevented with practical vent size.

  11. Vented coke oven door apparatus

    SciTech Connect

    Brown, H. B.; Gerding, C. C.

    1980-08-12

    A vented coke oven door includes a door frame having a vertical face surface carrying a plug assembly having a central vertical internal opening to conduct coke oven gas generated at the bottom of a coal charge in a coke oven chamber. The plug assembly includes a plurality of u-shaped refractory plug segments arranged in an end-to-end aligned relation with leg sections of each u-shaped segment extending horizontally into an abutting relation with the face surface of the door frame. Each leg section carries either an embedded hooked end or a t-shaped head of a threaded fastener which is supported by the door frame so that the leg sections are unrestrained against movement toward and away from each other in response to a thermal gradient across the wall thickness of the refractory plug segment. A backing plug plate is fitted into a recess in the leg sections of each plug segment to provide a closure wall to the u-shaped configuration of the segments and forms the vertical passageway for conducting coke oven gas. The backing plug plate has an exposed layer of cast refractory overlying a layer of insulation used to protect the door frame. A seal strip extends about the outer periphery of the door frame to prevent emission of coke oven gas from the coking chamber.

  12. Mechanical benefits of conservative restoration for dental fissure caries.

    PubMed

    Zhang, Zhongpu; Zheng, Keke; Li, Eric; Li, Wei; Li, Qing; Swain, Michael V

    2016-01-01

    The principle of minimal intervention dentistry (MID) is to limit removal of carious tooth tissue while maximizing its repair and survival potential. The objective of this study is to explore the fracture resistance of a permanent molar tooth with a fissure carious lesion along with three clinical restoration procedures, namely one traditional and two conservative approaches, based upon MID. The traditional restoration employs extensive surgical removal of enamel and dentine about the cavity to eliminate potential risk of further caries development, while conservative method #1 removes significantly less enamel and infected dentine, and conservative method #2 only restores the overhanging enamel above the cavity and leaves the infected and affected dentine as it was. An extended finite element method (XFEM) is adopted here to analyze the fracture behaviors of both two-dimensional (2D) and three-dimensional (3D) modeling of these four different scenarios. It was found that the two conservative methods exhibited better fracture resistance than the traditional restorative method. Although conservative method #2 has less fracture resistance than method #1, it had significantly superior fracture resistance compared to other restorations. More important, after cavity sealing it may potentially enhance the opportunity for remineralization and improved loading bearing capacity and fracture resistance. PMID:26298801

  13. 21 CFR 872.3765 - Pit and fissure sealant and conditioner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3765 Pit and fissure sealant and... depressions (faults in the enamel) in the biting surfaces of teeth to prevent cavities. (b)...

  14. Use of CO2 laser in pit and fissure caries prevention: clinical evaluation

    NASA Astrophysics Data System (ADS)

    Brugnera, Aldo, Jr.; Rosso, Naomi; Duarte, Danilo; Guedes Pinto, Antonio C.; Genovese, Walter J.

    1997-05-01

    In this four-year follow up in vivo controlled study, 112 human permanent first molars, from children between the ages of 6 and 11 years old were used to investigate the viability of the CO2 laser in promoting carie-free occlusal surfaces in permanent molars, as an isolated form of treatment or associated with conventional fissure sealants. The findings suggest that occlusal caries prevention only by means of CO2 laser irradiation is not effective; that the utilization of photo-activated sealants, as well as its association with CO2 laser, applied over the occlusal fissures, are effective means of preventing occlusal caries and that the application of CO2 laser over occlusal fissures, prior to the application of a photo-activated fissure sealant, improves the retention of the sealant.

  15. Painless Ulcers and Fissures of Toes: Hereditary Sensory Neuropathy, Not Leprosy

    PubMed Central

    Rao, Angoori Gnaneshwar

    2016-01-01

    Hereditary sensory neuropathies (HSN) are rare genetically determined neuropathies. They often manifest as painless injuries in children. We present HSN in a 5-year-old boy who presented with recurrent fissuring and ulceration involving both great toes. PMID:26955138

  16. Land subsidence and earth fissures due to groundwater withdrawal in the Southern Yangtse Delta, China

    NASA Astrophysics Data System (ADS)

    Zhang, Yun; Xue, Yu-Qun; Wu, Ji-Chun; Yu, Jun; Wei, Zi-Xin; Li, Qin-Fen

    2008-08-01

    Excessive extraction of groundwater has caused severe land subsidence and earth fissures in the Southern Yangtse Delta, China. Based on field data, the temporal and spatial distribution of land subsidence is investigated and the causes for earth fissures are analyzed. The areal distribution of the land subsidence is closely related to the cones of depression in the main exploited aquifers. The compaction of a hydrostratigraphic unit depends on its mechanical behavior, thickness, compressibility, and the piezometric level changing. The primary subsidence layers in Shanghai have been the first aquitard before 1990 and the third confined aquifer since then. But the second aquitard unit was the primary subsidence layer in Changzhou. Earth fissures, trending in several directions, occurred in the Husu tectonic zone. They were mainly caused by differential subsidence and horizontal displacement that resulted from tensile stress and shear stress in units. The majority of fissures in the study area are tensile.

  17. Putative fissure-resistance QTLs mapped to chromosomes 1 and 8 based on allelic frequency differences observed between fissure-resistant and fissure-susceptible progeny from two segregating populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole rice kernels have two to three times more market value than broken, which means that any reduction in milling yield results in financial losses for both rice producers and millers. One of the primary causes of rice breakage during milling is fissuring of the rice before it even enters the mil...

  18. The vent microbiome: patterns and drivers

    NASA Astrophysics Data System (ADS)

    Pachiadaki, M.

    2015-12-01

    Microbial processes within deep-sea hydrothermal vents affect the global biogeochemical cycles. Still, there are significant gaps in our understanding of the microbiology and the biogeochemistry of deep-sea hydrothermal systems. Vents differ in temperature, host rock composition and fluid chemistry; factors that are hypothesized to shape the distribution of the microbial communities, their metabolic capabilities and their activities. Using large-scale single cell genomics, we obtained insights into the genomic content of several linkages of a diffuse flow vent. The genomes show high metabolic versatility. Sulfur oxidation appears to be predominant but there is the potential of using a variety of e- donors and acceptors to obtain energy. To further assess the ecological importance of the vent auto- and heterotrophs, the global biogeography of the analyzed lineages will be investigated by fragment recruitment of metagenomes produced from the same site as well as other hydrothermal systems. Metatranscriptomic and metaproteomic data will be integrated to examine the expression of the predominant metabolic pathways and thus the main energy sources driving chemoautotrophic production. The comparative analysis of the key players and associated pathways among various vent sites that differ in physicochemical characteristics is anticipated to decipher the patterns and drivers of the global dispersion and the local diversification of the vent microbiome.

  19. Geologic form and setting of a hydrothermal vent field at latitude 10/sup 0/56'N, East Pacific Rise: a detailed study using Angus and Alvin

    SciTech Connect

    McConachy, T.F.; Ballard, R.D.; Mottl, M.J.; Von Herzen, R.P.

    1986-04-01

    A hydrothermal vent field, here called the Feather Duster site, occurs on the eastern marginal high near the edge of a narrow (95-m) and shallow (15-20-m) axial graben, within an area dominated by sheet flows and collapse features. The sheet flows are intermediate in relative age between younger fluid-flow lavas on the floor of the axial graben and older pillow (constructional) lavas on the marginal highs. Hydrothermal activity occurs in two zones within a 65 by 45 m area. The main zone is located where a fissure system and sulfide-sulfate chimneys vent warm (9-47/sup 0/C) and hot (347/sup 0/C) hydrothermal fluids. Here, two mounds of massive sulfide totaling about 200 t are forming. One occurs at the base of a 3-m-high scarp which is the wall of a drained lava lake; the other is perched on top of the scarp. 19 references, 4 figures.

  20. Explosion testing for the container venting system

    SciTech Connect

    Cashdollar, K.L.; Green, G.M.; Thomas, R.A.; Demiter, J.A.

    1993-09-30

    As part of the study of the hazards of inspecting nuclear waste stored at the Hanford Site, the US Department of Energy and Westinghouse Hanford Company have developed a container venting system to sample the gases that may be present in various metal drums and other containers. In support of this work, the US Bureau of Mines has studied the probability of ignition while drilling into drums and other containers that may contain flammable gas mixtures. The Westinghouse Hanford Company drilling procedure was simulated by tests conducted in the Bureau`s 8-liter chamber, using the same type of pneumatic drill that will be used at the Hanford Site. There were no ignitions of near-stoichiometric hydrogen-air or methane-air mixtures during the drilling tests. The temperatures of the drill bits and lids were measured by an infrared video camera during the drilling tests. These measured temperatures are significantly lower than the {approximately}500{degree}C autoignition temperature of uniformly heated hydrogen-air or the {approximately}600{degree}C autoignition temperature of uniformly heated methane-air. The temperatures are substantially lower than the 750{degree}C ignition temperature of hydrogen-air and 1,220{degree}C temperature of methane-air when heated by a 1-m-diameter wire.

  1. Fluorine mapping in sound and carious fissures of human teeth using PIGE

    NASA Astrophysics Data System (ADS)

    Yamamoto, H.; Nomachi, M.; Yasuda, K.; Iwami, Y.; Ebisu, S.; Sakai, T.; Fukuda, M.

    2005-04-01

    By using the PIGE technique at JAERI Takasaki, we measured fluorine (F) distribution in a micro area of occlusal fissures in the enamel of human teeth. The fissures were classified into three groups: Group I, no caries; Group II, incipient caries; Group III, advanced caries. The extracted teeth were embedded in epoxy resin and cut along the longitudinal axis through the fissures. The F concentration in the fissure at the cut surface was measured. A 1.7 MeV proton beam accelerated by the TIARA single-ended accelerator was delivered to a micro-beam apparatus. The beam spot size was about 1 μm with a beam current of about 100 pA. A nuclear reaction, 19F (p,αγ)16O, was used to measure the F concentration and gamma-rays from this reaction were detected with a 4″ NaI(Tl) detector. X-rays induced by proton were detected with a Ge detector to measure calcium concentration and the beam intensity was monitored with the X-ray yield from a copper foil for quantitative analysis. The obtained results were shown as two-dimensional mapping. In all specimens, an F concentration was observed around the fissure. The F concentration varied depending on the location of the fissure and decreased towards the inner part of the tooth. The maximum F concentration values in the measured area ranged from 3500-11700 ppm (mean = 6000 ppm) in Group I, 2400-10700 ppm (mean = 6300 ppm) in Group II, and 5200-16900 ppm (mean = 9300 ppm) in Group III. Although high F concentrations tended to be measured in the carious fissures, high values were also recognized in the sound fissures. More studies are necessary to clarify the relationship between F and carious lesions.

  2. Adaptive Management of Land Subsidence and Ground Fissuring in the Chino Groundwater Basin, California

    NASA Astrophysics Data System (ADS)

    Malone, A.; Rolfe, T.; Wildermuth, M.; Kavounas, P.

    2014-12-01

    The Chino Basin, located in southern California, is a large alluvial groundwater basin with storage in excess of five million acre-feet. The basin has a long history of groundwater development for various uses dating back to the early 1900s. As a result, piezometric heads declined basin-wide during the past century - in some areas by more than 200 feet. Declines of this magnitude typically cause irreversible aquifer-system compaction, which in turn results in subsidence at the ground surface. In portions of Chino Basin, land subsidence has been differential and accompanied by ground fissuring, which damaged existing infrastructure and poses concerns for new and existing development.Chino Basin Watermaster, the agency responsible for groundwater basin management, has recognized that land subsidence and ground fissuring should be minimized to the extent possible. At the same time, Watermaster is implementing aggressive groundwater-supply programs that include controlled overdraft and the possibility of causing head declines in areas prone to subsidence and fissuring. The groundwater-supply programs must also address the subsidence and fissuring phenomena.From 2001 to 2005, Watermaster conducted a technical investigation to characterize the extent, rate, and mechanisms of subsidence and fissuring. The investigation employed InSAR and ground-level surveying of benchmarks to monitor ground-surface deformation, and borehole extensometers and piezometric monitoring to establish the relationships between groundwater production, piezometric levels, and aquifer-system deformation. Based on the results of the investigation, Watermaster developed: (i) subsidence-management criteria for the areas experiencing acute subsidence and fissuring, and (ii) an adaptive management program to minimize the potential for future subsidence and fissuring across the entire Chino Basin. The science-based program includes ongoing monitoring, which now includes sophisticated fissure

  3. Comparative study of vent and seep macrofaunal communities in the Guaymas Basin

    NASA Astrophysics Data System (ADS)

    Portail, M.; Olu, K.; Escobar-Briones, E.; Caprais, J. C.; Menot, L.; Waeles, M.; Cruaud, P.; Sarradin, P. M.; Godfroy, A.; Sarrazin, J.

    2015-06-01

    Understanding the ecological processes and connectivity of chemosynthetic deep-sea ecosystems requires comparative studies. In the Guaymas Basin (Gulf of California, Mexico), the presence of seeps and vents in the absence of biogeographic barrier, comparable sedimentary settings and depths offers a unique opportunity to assess the role of ecosystem specific environmental conditions on macrofaunal communities. Six seep and four vent assemblages were studied, three of which were characterised by common major foundation taxa: vesicomyid bivalves, siboglinid tubeworms and microbial mats. Macrofaunal community structure at the family level showed that density, diversity and composition patterns were primarily shaped by seep and vent common abiotic factors including methane and hydrogen sulphide concentrations. The type of substratum and the heterogeneity provided by foundation species were identified as additional structuring factors and their roles were found to vary according to fluid regimes. Surprisingly, the presence of vent environmental specificities, with higher temperature, higher metal concentrations and lower pH was not significant in explaining community patterns. Moreover, Guaymas seep and vent shared an important number of common species suggesting frequent connections between the two ecosystems. Finally, this study provides further support for the hypothesis of continuity among deep-sea seep and vent ecosystems.

  4. Monitoring on Xi'an ground fissures deformation with TerraSAR-X data

    USGS Publications Warehouse

    Zhao, C.; Zhang, Q.; Zhu, W.; Lu, Zhiming

    2012-01-01

    Owing to the fine resolution of TerraSAR-X data provided since 2007, this paper applied 6 TerraSAR data (strip mode) during 3rd Dec. 2009 to 23rd Mar. 2010 to detect and monitor the active fissures over Xi'an region. Three themes have been designed for high precision detection and monitoring of Xi'an-Chang'an fissures, as small baseline subsets (SBAS) to test the atmospheric effects of differential interferograms pair stepwise, 2-pass differential interferogram with very short baseline perpendicular to generate the whole deformation map with 44 days interval, and finally, corner reflector (CR) technique was used to closely monitor the relative deformation time series between two CRs settled crossing two ground fissures. Results showed that TerraSAR data are a good choice for small-scale ground fissures detection and monitoring, while special considerations should be taken for their great temporal and baseline decorrelation. Secondly, ground fissures in Xi'an were mostly detected at the joint section of stable and deformable regions. Lastly, CR-InSAR had potential ability to monitor relative deformation crossing fissures with millimeter precision.

  5. Energy metabolism and cellular homeostasis trade-offs provide the basis for a new type of sensitivity to ocean acidification in a marine polychaete at a high-CO2 vent: adenylate and phosphagen energy pools versus carbonic anhydrase.

    PubMed

    Turner, Lucy M; Ricevuto, Elena; Massa-Gallucci, Alexia; Gambi, Maria-Cristina; Calosi, Piero

    2015-07-01

    Species distributions and ecology can often be explained by their physiological sensitivity to environmental conditions. Whilst we have a relatively good understanding of how these are shaped by temperature, for other emerging drivers, such as PCO2  we know relatively little. The marine polychaete Sabella spallanzanii increases its metabolic rate when exposed to high PCO2  conditions and remains absent from the CO2 vent of Ischia. To understand new possible pathways of sensitivity to CO2 in marine ectotherms, we examined the metabolic plasticity of S. spallanzanii exposed in situ to elevated PCO2  by measuring fundamental metabolite and carbonic anhydrase concentrations. We show that whilst this species can survive elevated PCO2  conditions in the short term, and exhibits an increase in energy metabolism, this is accompanied by a significant decrease in carbonic anhydrase concentration. These homeostatic changes are unlikely to be sustainable in the longer term, indicating S. spallanzanii may struggle with future high PCO2  conditions. PMID:25987731

  6. Fracturing and earthquake activity within the Prestahnúkur fissure swarm in the Western Volcanic Rift Zone of Iceland

    NASA Astrophysics Data System (ADS)

    Hjartardóttir, Ásta Rut; Hjaltadóttir, Sigurlaug; Einarsson, Páll; Vogfjörd, Kristín.; Muñoz-Cobo Belart, Joaquín.

    2015-12-01

    The Prestahnúkur fissure swarm is located within the ultraslowly spreading Western Volcanic Zone in Iceland. The fissure swarm is characterized by normal faults, open fractures, and evidence of subglacial fissure eruptions (tindars). In this study, fractures and faults within the Prestahnúkur fissure swarm were mapped in detail from aerial photographs to determine the extent and activity of the fissure swarm. Earthquakes during the last ~23 years were relocated to map the subsurface fault planes that they delineate. The Prestahnúkur fissure swarm is 40-80 km long and up to ~20 km wide. Most of the areas of the fissure swarm have been glacially eroded, although a part of it is covered by postglacial lava flows. The fissure swarm includes numerous faults with tens of meters vertical offset within the older glacially eroded part, whereas open fractures are found within postglacial lava flows. Comparison of relocated earthquakes and surface fractures indicates that some of the surface fractures have been activated at depth during the last ~23 years, although no dike intrusions have been ongoing. The existence of tindars nevertheless indicates that dike intrusions and rifting events do occur within the Prestahnúkur fissure swarm. The low-fracture density within postglacial lava flows and low density of postglacial eruptive fissures indicate that rifting episodes occur less often than in the faster spreading Northern Volcanic Zone.

  7. 14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... top part of the expansion space so that venting is effective under normal flight conditions. In..., during— (i) Normal flight operation; (ii) Maximum rate of ascent and descent; and (iii) Refueling and... attitude or the level flight attitude, unless drainage is provided; (6) No vent or drainage provision...

  8. 14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... top part of the expansion space so that venting is effective under normal flight conditions. In..., during— (i) Normal flight operation; (ii) Maximum rate of ascent and descent; and (iii) Refueling and... attitude or the level flight attitude, unless drainage is provided; (6) No vent or drainage provision...

  9. 14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... top part of the expansion space so that venting is effective under any normal flight condition. In..., during— (i) Normal flight operation; (ii) Maximum rate of ascent and descent; and (iii) Refueling and... attitude or the level flight attitude, unless drainage is provided; and (6) No vent or drainage...

  10. 14 CFR 23.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fuel tank vents and carburetor vapor vents. 23.975 Section 23.975 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Fuel System § 23.975 Fuel tank...

  11. 14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... top part of the expansion space so that venting is effective under normal flight conditions. In..., during— (i) Normal flight operation; (ii) Maximum rate of ascent and descent; and (iii) Refueling and... attitude or the level flight attitude, unless drainage is provided; (6) No vent or drainage provision...

  12. 14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... top part of the expansion space so that venting is effective under normal flight conditions. In..., during— (i) Normal flight operation; (ii) Maximum rate of ascent and descent; and (iii) Refueling and... attitude or the level flight attitude, unless drainage is provided; (6) No vent or drainage provision...

  13. 14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... top part of the expansion space so that venting is effective under any normal flight condition. In..., during— (i) Normal flight operation; (ii) Maximum rate of ascent and descent; and (iii) Refueling and... attitude or the level flight attitude, unless drainage is provided; and (6) No vent or drainage...

  14. 14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... top part of the expansion space so that venting is effective under any normal flight condition. In..., during— (i) Normal flight operation; (ii) Maximum rate of ascent and descent; and (iii) Refueling and... attitude or the level flight attitude, unless drainage is provided; and (6) No vent or drainage...

  15. 14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... top part of the expansion space so that venting is effective under any normal flight condition. In..., during— (i) Normal flight operation; (ii) Maximum rate of ascent and descent; and (iii) Refueling and... attitude or the level flight attitude, unless drainage is provided; and (6) No vent or drainage...

  16. ANALYSIS OF VENTING OF A RESIN SLURRY

    SciTech Connect

    Laurinat, J.; Hensel, S.

    2012-03-27

    A resin slurry venting analysis was conducted to address safety issues associated with overpressurization of ion exchange columns used in the Purex process at the Savannah River Site (SRS). If flow to these columns were inadvertently interrupted, an exothermic runaway reaction could occur between the ion exchange resin and the nitric acid used in the feed stream. The nitric acid-resin reaction generates significant quantities of noncondensable gases, which would pressurize the column. To prevent the column from rupturing during such events, rupture disks are installed on the column vent lines. The venting analysis models accelerating rate calorimeter (ARC) tests and data from tests that were performed in a vented test vessel with a rupture disk. The tests showed that the pressure inside the test vessel continued to increase after the rupture disk opened, though at a slower rate than prior to the rupture. Calculated maximum discharge rates for the resin venting tests exceeded the measured rates of gas generation, so the vent size was sufficient to relieve the pressure in the test vessel if the vent flow rate was constant. The increase in the vessel pressure is modeled as a transient phenomenon associated with expansion of the resin slurry/gas mixture upon rupture of the disk. It is postulated that the maximum pressure at the end of this expansion is limited by energy minimization to approximately 1.5 times the rupture disk burst pressure. The magnitude of this pressure increase is consistent with the measured pressure transients. The results of this analysis demonstrate the need to allow for a margin between the design pressure and the rupture disk burst pressure in similar applications.

  17. Identification of possible recent water/lava source fissures in the Cerberus Plains: stratigraphic and crater count age constraints

    NASA Astrophysics Data System (ADS)

    Thomas, Rebecca J.

    2013-04-01

    The Cerberus plains are one of the youngest surfaces on Mars. They are thought to have been formed by lava and/or water flows, but there is considerable debate regarding the source of this material. Much of the material forming the western plains, including the Athabasca Valles outflow channels, appears to have flowed from the region of the Cerberus Fossae graben system [1,2,3] and limited areas forming the eastern plains may have been erupted by low shield volcanoes [4,5]. However, flow of material from west to east is obstructed by a ridge centred on 157°E, 7°N and, prior to this study, vents which might be the source of fluid of a low enough viscosity to form the majority of the flat eastern plains had not been identified. We studied new HiRISE (25cm/px, High Resolution Science Imaging Experiment) images of the ridge between the east and west plains and observed possible source vents for this material: the ridge is cut by a series of pits and fissures which lie at the heads of flows and channels extending towards the surrounding plains. In order to establish the stratigraphic relationships between the vents and plains, this study produced large scale geomorphological maps based on the HiRISE images. The mapping showed that both incised channels and leveed flows extend onto the plain to the south of the ridge and that these were the final phase of plains-forming activity in that region. Conversely, to the north, ridge-sourced deposits only form the plains surface close to the ridge - beyond that, they are overlain by large-scale regional flows that appear to have originated from the direction of Athabasca Valles. In the southeast, a large-scale flow which does not emanate from this ridge forms the plains surface, but there is evidence that the youngest outflow activity from the ridge was contemporaneous with emplacement of this unit. We also performed crater counts to age-date the surfaces and these indicate that plains-forming and ridge-sourced units are of a

  18. Examination of frit vent from Sixty-Watt Heat Source simulant fueled clad vent set

    SciTech Connect

    Ulrich, G.B.

    1995-11-01

    The flow rate and the metallurgical condition of a frit vent from a simulant-fueled clad vent set (CVS) that had been hot isostatically pressed (HIP) for the Sixty-Watt Heat Source program were evaluated. The flow rate form the defueled vent cup subassembly was reduced approximately 25% from the original flow rate. No obstructions were found to account for the reduced flow rate. Measurements indicate that the frit vent powder thickness was reduced about 30%. Most likely, the powder was compressed during the HIP operation, which increased the density of the powder layer and thus reduced the flow rate of the assembly. All other observed manufacturing attributes appeared to be normal, but the vent hole activation technique needs further refinement before it is used in applications requiring maximum CVS integrity.

  19. Automatic venting valve for gas storage tank

    SciTech Connect

    Johnson, H.

    1986-12-02

    A control valve is described for blocking atmospheric venting of gas fumes contained within a gasoline storage tank during tanker refill operations. The gasoline tank includes a venting tube coupled to open space within the top of the tank to provide air intake for pressure equalization as gasoline is gradually removed from the tank, the control valve comprising: a. a rigid, tubular valve casing having a top opening, a bottom opening and a flow channel therebetween; b. means for attaching the bottom end of the casing to an upper end of the venting tube such that the valve flow channel forms a continuation venting path for the venting tube; c. first and second valve seats and an intermediate seating member coupled to the casing and at least partially contained within the flow channel. The seating member is configured in shape and size to form restricted air space between the seating member and a surrounding wall of the flow channel to be reversibly displaceable in response to fume exhaust expelled during refill operations.

  20. Comparison of Various Concentrations of Tricalcium Phosphate Nanoparticles on Mechanical Properties and Remineralization of Fissure Sealants

    PubMed Central

    Tavassoli-Hojjati, Sara; Atai, Mohammad; Haghgoo, Roza; Rahimian-Imam, Sara; Kameli, Somayeh; Ahmaian-Babaki, Fatemeh; Hamzeh, Faezeh; Ahmadyar, Maryam

    2014-01-01

    Objective: The aim of this study was to investigate the mechanical properties (flexural strength, micro-shear bond strength) and remineralizing potential of fissure sealants by adding various concentrations of β-tricalcium phosphate nanoparticles. Materials and Methods: This in-vitro study consisted of five experimental groups containing prepared nano-fisssure sealants (1–5 wt.% β-TCP nanoparticles) and two control groups containing a prepared and a commercial fissure sealant. Flexural/micro-shear bond strength values were measured using Zwick test machine. Cavities on sixty healthy premolar teeth were filled with the fissure sealants containing 0–5 wt.% of nano β-TCP. The samples were assessed for remineralization under scanning electron microscopy (SEM) and EDAX. Kolmogorov-Smirnov test, One-way ANOVA and Tukey’s Post Hoc analysis/HSD were used to analyze the data. Results: There was no significant difference between the flexural strengths/elastic modulus of the 0–5 wt.% nano β-TCP groups (p>0.05). The average flexural strength/elastic modulus of the prepared fissure sealant group (0%) was significantly higher than the commercial fissure sealant group (Clinpro) (p<0.05). There was no significant difference between micro-shear bond strengths of the experimental groups (1–5 wt.%), and between the commercial and the prepared (0%) fissure sealant groups (p>0.05). Examining the samples under SEM showed a significant increase in thickness of the intermediate layer with increasing concentrations of β-TCP nanoparticles (p<0.05). Conclusion: Addition of 1–5 wt.% β-TCP nanoparticles to the fissure sealants significantly increased the remineralization potential without affecting the mechanical properties. PMID:25584048

  1. Retention of resin-based filled and unfilled pit and fissure sealants: A comparative clinical study

    PubMed Central

    Reddy, V. Rajashekar; Chowdhary, Nagalakshmi; Mukunda, K. S.; Kiran, N. K.; Kavyarani, B. S.; Pradeep, M. C.

    2015-01-01

    Background and Objectives: The most caries-susceptible period of a permanent first molar tooth is the eruption phase, during which the enamel is not fully matured and it is usually difficult for the child to clean the erupting tooth surfaces. Sealing occlusal pits and fissures with resin-based pit and fissure sealants is a proven method to prevent occlusal caries. The difference in the viscosity of the sealants differs in the penetration into pit and fissures and abrasive wear resistance property due to the addition of filler particles. The present study was conducted to evaluate and compare the retention of the resin-based filled (Helioseal F, Ivoclar Vivadent) and unfilled (Clinpro, 3M ESPE) pit and fissure sealants, which is important for their effectiveness. Materials and Methods: Fifty-six children between the age group of 6 and 9 years, with all four newly erupted permanent first molars were selected. Sealants were applied randomly using split mouth design technique on permanent first molars. Evaluation of sealant retention was performed at regular intervals over 12 months, using Simonsen's criteria at 2nd, 4th, 6th, 8th, 10th and 12th month. The results were subjected to statistical analysis. Results: At the end of our study period (12th month), 53.57% showed complete retention, 37.50% showed partial retention, and 8.83% showed complete missing of resin-based filled (Helioseal F) pit and fissure sealant. And, 64.29% showed complete retention, 32.14% showed partial retention, and 3.57% showed complete missing of resin-based unfilled (Clinpro) pit and fissure sealant. This difference in retention rates between filled and unfilled pit and fissure sealants was not statistically significant. Conclusion: The difference in retention rates between Helioseal F and Clinpro was not statistically significant, but Clinpro (unfilled) sealant showed slightly higher retention rates and clinically better performance than Helioseal F (filled). PMID:25821368

  2. Medium Fidelity Simulation of Oxygen Tank Venting

    NASA Technical Reports Server (NTRS)

    Sweet, Adam; Kurien, James; Lau, Sonie (Technical Monitor)

    2001-01-01

    The item to he cleared is a medium-fidelity software simulation model of a vented cryogenic tank. Such tanks are commonly used to transport cryogenic liquids such as liquid oxygen via truck, and have appeared on liquid-fueled rockets for decades. This simulation model works with the HCC simulation system that was developed by Xerox PARC and NASA Ames Research Center. HCC has been previously cleared for distribution. When used with the HCC software, the model generates simulated readings for the tank pressure and temperature as the simulated cryogenic liquid boils off and is vented. Failures (such as a broken vent valve) can be injected into the simulation to produce readings corresponding to the failure. Release of this simulation will allow researchers to test their software diagnosis systems by attempting to diagnose the simulated failure from the simulated readings. This model does not contain any encryption software nor can it perform any control tasks that might be export controlled.

  3. Investigations Into Tank Venting for Propellant Resupply

    NASA Technical Reports Server (NTRS)

    Hearn, H. C.; Harrison, Robert A. (Technical Monitor)

    2002-01-01

    Models and simulations have been developed and applied to the evaluation of propellant tank ullage venting, which is integral to one approach for propellant resupply. The analytical effort was instrumental in identifying issues associated with resupply objectives, and it was used to help develop an operational procedure to accomplish the desired propellant transfer for a particular storable bipropellant system. Work on the project was not completed, and several topics have been identified as requiring further study; these include the potential for liquid entrainment during the low-g and thermal/freezing effects in the vent line and orifice. Verification of the feasibility of this propellant venting and resupply approach still requires additional analyses as well as testing to investigate the fluid and thermodynamic phenomena involved.

  4. Why does a mature volcano need new vents? The case of the New Southeast Crater at Etna

    NASA Astrophysics Data System (ADS)

    Acocella, Valerio; Neri, Marco; Behncke, Boris; Bonforte, Alessandro; Del Negro, Ciro; Ganci, Gaetana

    2016-06-01

    Mature volcanoes usually erupt from a persistent summit crater. Permanent shifts in vent location are expected to occur after significant structural variations and are seldom documented. Here we provide such an example that recently occurred at Etna. Eruptive activity at Mount Etna during 2007 focused at the Southeast Crater (SEC), the youngest (formed in 1971) and most active of the four summit craters, and consisted of six paroxysmal episodes. The related erupted volumes, determined by field-based measurements and radiant heat flux curves measured by satellite, totalled 8.67 x 106 m3. The first four episodes occurred, between late-March and early-May, from the summit of the SEC and short fissures on its flanks. The last two episodes occurred, in September and November, from a new vent ("pit crater" or "proto-NSEC") at the SE base of the SEC cone; this marked the definitive demise of the old SEC and the shift to the new vent. The latter, fed by NW-SE striking dikes propagating from the SEC conduit, formed since early 2011 an independent cone (the New Southeast Crater, or "NSEC") at the base of the SEC. Detailed geodetic reconstruction and structural field observations allow defining the surface deformation pattern of Mount Etna in the last decade. These suggest that the NSEC developed under the NE-SW trending tensile stresses on the volcano summit promoted by accelerated instability of the NE flank of the volcano during inflation periods. The development of the NSEC is not only important from a structural point of view, as its formation may also lead to an increase in volcanic hazard. The case of the NSEC at Etna here reported shows how flank instability may control the distribution and impact of volcanism, including the prolonged shift of the summit vent activity in a mature volcano.

  5. Spatial Compilation of Holocene Volcanic Vents in the Western Conterminous United States

    NASA Astrophysics Data System (ADS)

    Ramsey, D. W.; Siebert, L.

    2015-12-01

    A spatial compilation of all known Holocene volcanic vents in the western conterminous United States has been assembled. This compilation records volcanic vent location (latitude/longitude coordinates), vent type (cinder cone, dome, etc.), geologic map unit description, rock type, age, numeric age and reference (if dated), geographic feature name, mapping source, and, where available, spatial database source. Primary data sources include: USGS geologic maps, USGS Data Series, the Smithsonian Global Volcanism Program (GVP) catalog, and published journal articles. A total of 726 volcanic vents have been identified from 45 volcanoes or volcanic fields spanning ten states. These vents are found along the length of the Cascade arc in the Pacific Northwest, widely around the Basin and Range province, and at the southern margin of the Colorado Plateau into New Mexico. The U.S. Geological Survey (USGS) National Volcano Early Warning System (NVEWS) identifies 28 volcanoes and volcanic centers in the western conterminous U.S. that pose moderate, high, or very high threats to surrounding communities based on their recent eruptive histories and their proximity to vulnerable people, property, and infrastructure. This compilation enhances the understanding of volcano hazards that could threaten people and property by providing the context of where Holocene eruptions have occurred and where future eruptions may occur. Locations in this compilation can be spatially compared to located earthquakes, used as generation points for numerical hazard models or hazard zonation buffering, and analyzed for recent trends in regional volcanism and localized eruptive activity.

  6. Vented Cavity Radiant Barrier Assembly And Method

    DOEpatents

    Dinwoodie, Thomas L.; Jackaway, Adam D.

    2000-05-16

    A vented cavity radiant barrier assembly (2) includes a barrier (12), typically a PV module, having inner and outer surfaces (18, 22). A support assembly (14) is secured to the barrier and extends inwardly from the inner surface of the barrier to a building surface (14) creating a vented cavity (24) between the building surface and the barrier inner surface. A low emissivity element (20) is mounted at or between the building surface and the barrier inner surface. At least part of the cavity exit (30) is higher than the cavity entrance (28) to promote cooling air flow through the cavity.

  7. Composition of gases vented from a condenser

    SciTech Connect

    Lyon, R.N.

    1980-08-01

    Designers of systems that involve condensers often need to predict the amount of process vapor that accompanies the noncondensable gases that are vented from the condensers. An approximation is given that appears to provide, in many cases, reasonably accurate values for the mole ratio of process vapor to noncondensable gases in the vented mixture. The approximation is particularly applicable to flash and direct-contact power systems for geothermal brines and ocean thermal energy conversion (OTEC). More regorous relationships are available for exceptional cases.

  8. Geological and geochemical controls on the distribution of Alviniconcha vent snail symbioses: Have we finally linked mantle to microbe? (Invited)

    NASA Astrophysics Data System (ADS)

    Girguis, P. R.; Beinart, R.; Sanders, J.; Seewald, J.

    2010-12-01

    Gastropods of the genus Alviniconcha are found at hydrothermal vent fields in the Western Pacific, and have been reported to associate with either γ- or ɛ-Proteobacterial endosymbionts. These symbionts harness energy from the oxidation of chemicals in vent fluid to fix inorganic carbon and are the primary source of nutrition for the holobiont. An extensive sampling effort during a recent expedition to the Eastern Lau Spreading Center (ELSC) has revealed that Alviniconcha host both previously observed symbiont types, as well as an additional γ- proteobacterial symbiont. Specifically, we collected 266 Alviniconcha individuals from four vent fields along the spreading center (30-140km apart) which span the north-south transition from fast spreading, basalt-hosted to slower spreading, andesite-hosted fields. Vent fluids from each field were also analyzed for the abundances of aqueous volatile and non-volatile species. The symbionts of all collected Alviniconcha were genotyped using restriction fragment length polymorphism analysis as well as quantitative PCR. Individuals were found to primarily host one of the three symbiont genotypes (two γ- and one ɛ-Proteobacteria). Notably, we found that the two northern-most sites (basalt-hosted vents) were greatly dominated by individuals with the ɛ-Proteobacterial symbiont, while the two southern sites (andesite-hosted vents) were dominated by individuals hosting one of the two γ-Proteobacterial symbionts. This pattern corresponds to differences in the aqueous chemistry of the vent fluids along the spreading center. In particular, we have measured higher concentrations of hydrogen and hydrogen sulfide in the vent fluids at the northern sites than in the fluids of the southern sites. We posit that vent chemistry -which is influenced by subsurface water-rock interactions- may be influencing the dominance of each symbiont type along the ELSC. The putative implications for the role that geology and geochemistry plays in

  9. Automatic recognition of lung lobes and fissures from multislice CT images

    NASA Astrophysics Data System (ADS)

    Zhou, Xiangrong; Hayashi, Tatsuro; Hara, Takeshi; Fujita, Hiroshi; Yokoyama, Ryujiro; Kiryu, Takuji; Hoshi, Hiroaki

    2004-05-01

    Computer-aided diagnosis (CAD) has been expected to help radiologists to improve the accuracy of abnormality detection and reduce the burden during CT image interpretations. In order to realize such functions, automated segmentations of the target organ regions are always required by CAD systems. This paper describes a fully automatic processing procedure, which is designed to identify inter-lobe fissures and divide lung into five lobe regions. The lung fissures are disappeared very fuzzy and indefinite in CT images, so that it is very difficult to extract fissures directly based on its CT values. We propose a method to solve this problem using the anatomy knowledge of human lung. We extract lung region firstly and then recognize the structures of lung vessels and bronchus. Based on anatomy knowledge, we classify the vessels and bronchus on a lobe-by-lobe basis and estimate the boundary of each lobe region as the initial fissure locations. Within those locations, we extract lung fissures precisely based on an edge detection method and divide lung regions into five lung lobes lastly. The performance of the proposed method was evaluated using 9 patient cases of high-resolution multi-slice chest CT images; the improvement has been confirmed with the reliable recognition results.

  10. In Vitro Comparison of Microleakage of Two Materials Used as Pit and Fissure Sealants

    PubMed Central

    Bahrololoomi, Zahra; Soleymani, Aliasghar; Heydari, Zahra

    2011-01-01

    Background and aims Marginal seal of the material is extremely important in fissure sealant therapy. The aim of this study was to investigate microleakage of flowable composite resins and conventional fissure sealants with or without dentin bonding agent. Materials and methods The occlusal surface of 60 intact extracted human premolars, divided into four groups, were cleaned with pumice/slurry, etched with 37% phosphoric acid for 15 seconds, rinsed and dried. Groups were treated differ-ently: Excite bonding agent followed by Helioseal F fissure sealant in group1; Helioseal F alone in group 2; Excite bonding agent followed by Tetric Flow in group 3; and Tetric Flow alone in group 4. Light-curing was done after each application. After thermocycling, the whole surface of each specimen was coated with nail varnish except for one millimeter around the fissure sealant. The teeth were immersed in 2% basic fuchsin for 24 hours and then sectioned buccolingually. The sections were analyzed for leakage under a stereomicroscope. Data was analyzed by Kruskal-Wallis and Mann-Whitney tests at asignificance level of P < 0.05. Results There were no statistically significant differencesbetween the study groups in terms of the mean microleakage scores (P > 0.05), except for groups 2 and 4 (P = 0.002) and groups 3 and 4 (P = 0.033). Conclusion Use of a flowable composite with bonding agent is a good alternative for sealing pits and fissures; however, further in vitro and in vivo studies are necessary. PMID:22991611