DYNAMICS OF NASCENT AND ACTIVE ZONE ULTRASTRUCTURE AS SYNAPSES ENLARGE DURING LTP IN MATURE HIPPOCAMPUS

PubMed Central

Bell, Maria Elizabeth; Bourne, Jennifer N.; Chirillo, Michael A.; Mendenhall, John M.; Kuwajima, Masaaki; Harris, Kristen M.

2014-01-01

Nascent zones and active zones are adjacent synaptic regions that share a postsynaptic density, but nascent zones lack the presynaptic vesicles found at active zones. Here dendritic spine synapses were reconstructed through serial section electron microscopy (3DEM) and EM tomography to investigate nascent zone dynamics during long-term potentiation (LTP) in mature rat hippocampus. LTP was induced with theta-burst stimulation and comparisons were made to control stimulation in the same hippocampal slices at 5 minutes, 30 minutes, and 2 hours post-induction and to perfusion-fixed hippocampus in vivo. Nascent zones were present at the edges of ~35% of synapses in perfusion-fixed hippocampus and as many as ~50% of synapses in some hippocampal slice conditions. By 5 minutes, small dense core vesicles known to transport active zone proteins moved into more presynaptic boutons. By 30 minutes, nascent zone area decreased without significant change in synapse area, suggesting that presynaptic vesicles were recruited to pre-existing nascent zones. By 2 hours, both nascent and active zones were enlarged. Immunogold labeling revealed that glutamate receptors can be found in nascent zones; however, average distances from nascent zones to docked presynaptic vesicles ranged from 170±5 nm in perfusion-fixed hippocampus to 251±4 nm at enlarged synapses by 2 hours during LTP. Prior stochastic modeling suggests that falloff in glutamate concentration reduces the probability of glutamate receptor activation from 0.4 at the center of release to 0.1 just 200 nm away. Thus, conversion of nascent zones to functional active zones likely requires the recruitment of presynaptic vesicles during LTP. PMID:25043676

Butterfly Density and Behaviour in Uncut Hay Meadow Strips: Behavioural Ecological Consequences of an Agri-Environmental Scheme.

PubMed

Lebeau, Julie; Wesselingh, Renate A; Van Dyck, Hans

2015-01-01

Sparing zones from mowing has been proposed, and applied, to improve local conditions for survival and reproduction of insects in hay meadows. However, little is known about the efficiency of refuge zones and the consequences for local populations. We studied population densities of butterflies before and after mowing in the refuge zone of 15 meadows in 2009 and 2011. We also studied the behaviour of the meadow brown (Maniola jurtina) comparing nectar use, interactions and flights in the refuge zone before and after mowing. Densities of grassland butterflies in this zone doubled on average after mowing. The density of females of M. jurtina increased on average fourfold, while males showed a more modest increase. In line with the idea of increased scramble competition in the refuge zone after mowing, M. jurtina increased the time spent on nectar feeding, the preferred nectar source was visited more frequently, and females made more use of non-preferred nectar sources. Maniola jurtina did not interact more with conspecifics after mowing, but interactions lasted longer. Flight tracks did not change in linearity, but were faster and shorter after mowing. After mowing, only a part of the local grassland butterflies moved to the uncut refuge zone. The resulting concentration effect alters the time allocated to different activities, nectar use and movements. These aspects have been largely ignored for agri-environmental schemes and grassland management in nature reserves and raise questions about optimal quantities and quality of uncut refuge sites for efficient conservation of grassland arthropods in agricultural landscapes.

Butterfly Density and Behaviour in Uncut Hay Meadow Strips: Behavioural Ecological Consequences of an Agri-Environmental Scheme

PubMed Central

Lebeau, Julie; Wesselingh, Renate A.; Van Dyck, Hans

2015-01-01

Sparing zones from mowing has been proposed, and applied, to improve local conditions for survival and reproduction of insects in hay meadows. However, little is known about the efficiency of refuge zones and the consequences for local populations. We studied population densities of butterflies before and after mowing in the refuge zone of 15 meadows in 2009 and 2011. We also studied the behaviour of the meadow brown (Maniola jurtina) comparing nectar use, interactions and flights in the refuge zone before and after mowing. Densities of grassland butterflies in this zone doubled on average after mowing. The density of females of M. jurtina increased on average fourfold, while males showed a more modest increase. In line with the idea of increased scramble competition in the refuge zone after mowing, M. jurtina increased the time spent on nectar feeding, the preferred nectar source was visited more frequently, and females made more use of non-preferred nectar sources. Maniola jurtina did not interact more with conspecifics after mowing, but interactions lasted longer. Flight tracks did not change in linearity, but were faster and shorter after mowing. After mowing, only a part of the local grassland butterflies moved to the uncut refuge zone. The resulting concentration effect alters the time allocated to different activities, nectar use and movements. These aspects have been largely ignored for agri-environmental schemes and grassland management in nature reserves and raise questions about optimal quantities and quality of uncut refuge sites for efficient conservation of grassland arthropods in agricultural landscapes. PMID:26284618

47 CFR 69.123 - Density pricing zones for special access and switched transport.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 3 2010-10-01 2010-10-01 false Density pricing zones for special access and...) COMMON CARRIER SERVICES (CONTINUED) ACCESS CHARGES Computation of Charges § 69.123 Density pricing zones... price cap regulation may establish any number of density zones within a study area that is used for...

The Cascadia Subduction Zone: two contrasting models of lithospheric structure

USGS Publications Warehouse

Romanyuk, T.V.; Blakely, R.; Mooney, W.D.

1998-01-01

The Pacific margin of North America is one of the most complicated regions in the world in terms of its structure and present day geodynamic regime. The aim of this work is to develop a better understanding of lithospheric structure of the Pacific Northwest, in particular the Cascadia subduction zone of Southwest Canada and Northwest USA. The goal is to compare and contrast the lithospheric density structure along two profiles across the subduction zone and to interpet the differences in terms of active processes. The subduction of the Juan de Fuca plate beneath North America changes markedly along the length of the subduction zone, notably in the angle of subduction, distribution of earthquakes and volcanism, goelogic and seismic structure of the upper plate, and regional horizontal stress. To investigate these characteristics, we conducted detailed density modeling of the crust and mantle along two transects across the Cascadia subduction zone. One crosses Vancouver Island and the Canadian margin, the other crosses the margin of central Oregon.

The ambient acoustic environment in Laguna San Ignacio, Baja California Sur, Mexico.

PubMed

Seger, Kerri D; Thode, Aaron M; Swartz, Steven L; Urbán, Jorge R

2015-11-01

Each winter gray whales (Eschrichtius robustus) breed and calve in Laguna San Ignacio, Mexico, where a robust, yet regulated, whale-watching industry exists. Baseline acoustic environments in LSI's three zones were monitored between 2008 and 2013, in anticipation of a new road being paved that will potentially increase tourist activity to this relatively isolated location. These zones differ in levels of both gray whale usage and tourist activity. Ambient sound level distributions were computed in terms of percentiles of power spectral densities. While these distributions are consistent across years within each zone, inter-zone differences are substantial. The acoustic environment in the upper zone is dominated by snapping shrimp that display a crepuscular cycle. Snapping shrimp also affect the middle zone, but tourist boat transits contribute to noise distributions during daylight hours. The lower zone has three source contributors to its acoustic environment: snapping shrimp, boats, and croaker fish. As suggested from earlier studies, a 300 Hz noise minimum exists in both the middle and lower zones of the lagoon, but not in the upper zone.

Gravity anomaly and density structure of the San Andreas fault zone

NASA Astrophysics Data System (ADS)

Wang, Chi-Yuen; Rui, Feng; Zhengsheng, Yao; Xingjue, Shi

1986-01-01

A densely spaced gravity survey across the San andreas fault zone was conducted near Bear Valley, about 180 km south of San Francisco, along a cross-section where a detailed seismic reflection profile was previously made by McEvilly (1981). With Feng and McEvilly's velocity structure (1983) of the fault zone at this cross-section as a constraint, the density structure of the fault zone is obtained through inversion of the gravity data by a method used by Parker (1973) and Oldenburg (1974). Although the resulting density picture cannot be unique, it is better constrained and contains more detailed information about the structure of the fault than was previously possible. The most striking feature of the resulting density structure is a deeply seated tongue of low-density material within the fault zone, probably representing a wedge of fault gouge between the two moving plates, which projects from the surface to the base of the seismogenic zone. From reasonable assumptions concerning the density of the solid grains and the state of saturation of the fault zone the average porosity of this low-density fault gouge is estimated as about 12%. Stress-induced cracks are not expected to create so much porosity under the pressures in the deep fault zone. Large-scaled removal of fault-zone material by hydrothermal alteration, dissolution, and subsequent fluid transport may have occurred to produce this pronounced density deficiency. In addition, a broad, funnel-shaped belt of low density appears about the upper part of the fault zone, which probably represents a belt of extensively shattered wall rocks.

Mass motions in the solar chromosphere and transition zone

NASA Technical Reports Server (NTRS)

Mein, P.; Simon, G.; Vial, J. C.; Shine, R. A.

1982-01-01

A comparison is made between H-alpha and C IV observations of Active Region 2717 on October 9, 1980. On the basis of this comparison, it is found that upward velocities are present above sunspots in the chromosphere-corona transition zone (20 km/s). The downward velocities are found to be well correlated in both lines. Doppler-shift ratios between C IV and H-alpha levels (approximately 10) are seen to be much smaller than expected from density ratio estimates. The comparison is seen as suggesting that flow lines are probably far from vertical in the transition zone. It is pointed out, however, that this depends on model densities that may not be correct. A simple method for comparing matter flows is presented. The best fit between H-alpha and C IV levels is obtained when C IV Doppler shifts are multiplied by the line intensity to the power 0.5 (approximately) in order to make allowance for density fluctuations.

Prostate specific antigen and acinar density: a new dimension, the "Prostatocrit".

PubMed

Robinson, Simon; Laniado, Marc; Montgomery, Bruce

2017-01-01

Prostate-specific antigen densities have limited success in diagnosing prostate cancer. We emphasise the importance of the peripheral zone when considered with its cellular constituents, the "prostatocrit". Using zonal volumes and asymmetry of glandular acini, we generate a peripheral zone acinar volume and density. With the ratio to the whole gland, we can better predict high grade and all grade cancer. We can model the gland into its acinar and stromal elements. This new "prostatocrit" model could offer more accurate nomograms for biopsy. 674 patients underwent TRUS and biopsy. Whole gland and zonal volumes were recorded. We compared ratio and acinar volumes when added to a "clinic" model using traditional PSA density. Univariate logistic regression was used to find significant predictors for all and high grade cancer. Backwards multiple logistic regression was used to generate ROC curves comparing the new model to conventional density and PSA alone. Prediction of all grades of prostate cancer: significant variables revealed four significant "prostatocrit" parameters: log peripheral zone acinar density; peripheral zone acinar volume/whole gland acinar volume; peripheral zone acinar density/whole gland volume; peripheral zone acinar density. Acinar model (AUC 0.774), clinic model (AUC 0.745) (P=0.0105). Prediction of high grade prostate cancer: peripheral zone acinar density ("prostatocrit") was the only significant density predictor. Acinar model (AUC 0.811), clinic model (AUC 0.769) (P=0.0005). There is renewed use for ratio and "prostatocrit" density of the peripheral zone in predicting cancer. This outperforms all traditional density measurements. Copyright® by the International Brazilian Journal of Urology.

Theoretical and experimental investigation into high current hollow cathode arc attachment

NASA Astrophysics Data System (ADS)

Downey, Ryan T.

This research addresses several concerns of the mechanisms controlling performance and lifetime of high-current single-channel-hollow-cathodes, the central electrode and primary life-limiting component in Magnetoplasmadynamic thrusters. Specifically covered are the trends, and the theorized governing mechanisms, seen in the discharge efficiency and power, the size of the plasma attachment to the cathode (the active zone), cathode exit plume plasma density and energy, along with plasma property distributions of the internal plasma column (the IPC) of a single-channel-hollow-cathode. Both experiment and computational modeling were employed in the analysis of the cathodes. Employing Tantalum and Tungsten cathodes (of 2, 6 and 10 mm inner diameter), experiments were conducted to measure the temperature profile of operating cathodes, the width of the active zone, the discharge voltage, power, plasma arc resistance and efficiency, with mass flow rates of 50 to 300 sccm of Argon, and discharge currents of 15 to 50 Amps. Langmuir probing was used to obtain measurements for the electron temperature, plasma density and plasma potential at the cathode exit plane (down stream tip). A computational model was developed to predict the distribution of plasma inside the cathode, based upon experimentally determined boundary conditions. It was determined that the peak cathode temperature is a function of both interior cathode density and discharge current, though the location of the peak temperature is controlled gas density but not discharge current. The active zone width was found to be an increasing function of the discharge current, but a decreasing function of the mass flow rate. The width of the active zone was found to not be controlled by the magnitude of the peak cathode wall temperature. The discharge power consumed per unit of mass throughput is seen as a decreasing function of the mass flow rate, showing the increasing efficiency of the cathode. Finally, this new understanding of the mechanisms of the plasma attachment phenomena of a single-channel-hollow-cathode were extrapolated to the multi-channel-hollow-cathode environment, to explain performance characteristics of these devices seen in previous research.

Asymmetric battery having a semi-solid cathode and high energy density anode

DOEpatents

Tan, Taison; Chiang, Yet-Ming; Ota, Naoki; Wilder, Throop; Duduta, Mihai

2017-11-28

Embodiments described herein relate generally to devices, systems and methods of producing high energy density batteries having a semi-solid cathode that is thicker than the anode. An electrochemical cell can include a positive electrode current collector, a negative electrode current collector and an ion-permeable membrane disposed between the positive electrode current collector and the negative electrode current collector. The ion-permeable membrane is spaced a first distance from the positive electrode current collector and at least partially defines a positive electroactive zone. The ion-permeable membrane is spaced a second distance from the negative electrode current collector and at least partially defines a negative electroactive zone. The second distance is less than the first distance. A semi-solid cathode that includes a suspension of an active material and a conductive material in a non-aqueous liquid electrolyte is disposed in the positive electroactive zone, and an anode is disposed in the negative electroactive zone.

Asymmetric battery having a semi-solid cathode and high energy density anode

DOEpatents

Tan, Taison; Chiang, Yet-Ming; Ota, Naoki; Wilder, Throop; Duduta, Mihai

2016-09-06

Embodiments described herein relate generally to devices, systems and methods of producing high energy density batteries having a semi-solid cathode that is thicker than the anode. An electrochemical cell can include a positive electrode current collector, a negative electrode current collector and an ion-permeable membrane disposed between the positive electrode current collector and the negative electrode current collector. The ion-permeable membrane is spaced a first distance from the positive electrode current collector and at least partially defines a positive electroactive zone. The ion-permeable membrane is spaced a second distance from the negative electrode current collector and at least partially defines a negative electroactive zone. The second distance is less than the first distance. A semi-solid cathode that includes a suspension of an active material and a conductive material in a non-aqueous liquid electrolyte is disposed in the positive electroactive zone, and an anode is disposed in the negative electroactive zone.

Communities on the Move: Pedestrian-Oriented Zoning as a Facilitator of Adult Active Travel to Work in the United States.

PubMed

Chriqui, Jamie F; Leider, Julien; Thrun, Emily; Nicholson, Lisa M; Slater, Sandy

2016-01-01

Communities across the United States have been reforming their zoning codes to create pedestrian-friendly neighborhoods with increased street connectivity, mixed use and higher density, open space, transportation infrastructure, and a traditional neighborhood structure. Zoning code reforms include new urbanist zoning such as the SmartCode, form-based codes, transects, transportation and pedestrian-oriented developments, and traditional neighborhood developments. To examine the relationship of zoning code reforms and more active living--oriented zoning provisions with adult active travel to work via walking, biking, or by using public transit. Zoning codes effective as of 2010 were compiled for 3,914 municipal-level jurisdictions located in 471 counties and 2 consolidated cities in 48 states and the District of Columbia, and that collectively covered 72.9% of the U.S. population. Zoning codes were evaluated for the presence of code reform zoning and nine pedestrian-oriented zoning provisions (1 = yes): sidewalks, crosswalks, bike-pedestrian connectivity, street connectivity, bike lanes, bike parking, bike-pedestrian trails/paths, mixed-use development, and other walkability/pedestrian orientation. A zoning scale reflected the number of provisions addressed (out of 10). Five continuous outcome measures were constructed using 2010-2014 American Community Survey municipal-level 5-year estimates to assess the percentage of workers: walking, biking, walking or biking, or taking public transit to work OR engaged in any active travel to work. Regression models controlled for municipal-level socioeconomic characteristics and a GIS-constructed walkability scale and were clustered on county with robust standard errors. Adjusted models indicated that several pedestrian-oriented zoning provisions were statistically associated (p < 0.05 or lower) with increased rates of walking, biking, or engaging in any active travel (walking, biking, or any active travel) to work: code reform zoning, bike parking (street furniture), bike lanes, bike-pedestrian trails/paths, other walkability, mixed-use zoning, and a higher score on the zoning scale. Public transit use was associated with code reform zoning and a number of zoning measures in Southern jurisdictions but not in non-Southern jurisdictions. As jurisdictions revisit their zoning and land use policies, they may want to evaluate the pedestrian-orientation of their zoning codes so that they can plan for pedestrian improvements that will help to encourage active travel to work.

Seed viability detection using computerized false-color radiographic image enhancement

NASA Technical Reports Server (NTRS)

Vozzo, J. A.; Marko, Michael

1994-01-01

Seed radiographs are divided into density zones which are related to seed germination. The seeds which germinate have densities relating to false-color red. In turn, a seed sorter may be designed which rejects those seeds not having sufficient red to activate a gate along a moving belt containing the seed source. This results in separating only seeds with the preselected densities representing biological viability lending to germination. These selected seeds demand a higher market value. Actual false-coloring isn't required for a computer to distinguish the significant gray-zone range. This range can be predetermined and screened without the necessity of red imaging. Applying false-color enhancement is a means of emphasizing differences in densities of gray within any subject from photographic, radiographic, or video imaging. Within the 0-255 range of gray levels, colors can be assigned to any single level or group of gray levels. Densitometric values then become easily recognized colors which relate to the image density. Choosing a color to identify any given density allows separation by morphology or composition (form or function). Additionally, relative areas of each color are readily available for determining distribution of that density by comparison with other densities within the image.

Neighbourhood walkability, leisure-time and transport-related physical activity in a mixed urban-rural area.

PubMed

de Sa, Eric; Ardern, Chris I

2014-01-01

Objectives. To develop a walkability index specific to mixed rural/suburban areas, and to explore the relationship between walkability scores and leisure time physical activity. Methods. Respondents were geocoded with 500 m and 1,000 m buffer zones around each address. A walkability index was derived from intersections, residential density, and land-use mix according to built environment measures. Multivariable logistic regression models were used to quantify the association between the index and physical activity levels. Analyses used cross-sectional data from the 2007-2008 Canadian Community Health Survey (n = 1158; ≥18 y). Results. Respondents living in highly walkable 500 m buffer zones (upper quartiles of the walkability index) were more likely to walk or cycle for leisure than those living in low-walkable buffer zones (quartile 1). When a 1,000 m buffer zone was applied, respondents in more walkable neighbourhoods were more likely to walk or cycle for both leisure-time and transport-related purposes. Conclusion. Developing a walkability index can assist in exploring the associations between measures of the built environment and physical activity to prioritize neighborhood change.

Finding Faults: Tohoku and other Active Megathrusts/Megasplays

NASA Astrophysics Data System (ADS)

Moore, J. C.; Conin, M.; Cook, B. J.; Kirkpatrick, J. D.; Remitti, F.; Chester, F.; Nakamura, Y.; Lin, W.; Saito, S.; Scientific Team, E.

2012-12-01

Current subduction-fault drilling procedure is to drill a logging hole, identify target faults, then core and instrument them. Seismic data may constrain faults but the additional resolution of borehole logs is necessary for efficient coring and instrumentation under difficult conditions and tight schedules. Thus, refining the methodology of identifying faults in logging data has become important, and thus comparison of log signatures of faults in different locations is worthwhile. At the C0019 (JFAST) drill site, the Tohoku megathrust was principally identified as a decollement where steep cylindrically-folded bedding abruptly flattens below the basal detachment. A similar structural contrast occurs across a megasplay fault in the NanTroSEIZE transect (Site C0004). At the Tohoku decollement, a high gamma-ray value from a pelagic clay layer, predicted as a likely decollement sediment type, strengthens the megathrust interpretation. The original identification of the pelagic clay as a decollement candidate was based on results of previous coring of an oceanic reference site. Negative density anomalies, often seen as low resistivity zones, identified a subsidiary fault in the deformed prism overlying the Tohoku megathrust. Elsewhere, at Barbados, Nankai (Moroto), and Costa Rica, negative density anomalies are associated with the decollement and other faults in hanging walls. Log-based density anomalies in fault zones provide a basis for recognizing in-situ fault zone dilation. At the Tohoku Site C0019, breakouts are present above but not below the megathrust. Changes in breakout orientation and width (stress magnitude) occur across megasplay faults at Sites C0004 and C0010 in the NantroSEIZE transect. Annular pressure anomalies are not apparent at the Tohoku megathrust, but are variably associated with faults and fracture zones drilled along the NanTroSEIZE transect. Overall, images of changes in structural features, negative density anomalies, and changes in breakout occurrence and orientation provide the most common log criteria for recognizing major thrust zones in ocean drilling holes at convergent margins. In the case of JFAST, identification of faults by logging was confirmed during subsequent coring activities, and logging data was critical for successful placement of the observatory down hole.

Continuous theory of active matter systems with metric-free interactions.

PubMed

Peshkov, Anton; Ngo, Sandrine; Bertin, Eric; Chaté, Hugues; Ginelli, Francesco

2012-08-31

We derive a hydrodynamic description of metric-free active matter: starting from self-propelled particles aligning with neighbors defined by "topological" rules, not metric zones-a situation advocated recently to be relevant for bird flocks, fish schools, and crowds-we use a kinetic approach to obtain well-controlled nonlinear field equations. We show that the density-independent collision rate per particle characteristic of topological interactions suppresses the linear instability of the homogeneous ordered phase and the nonlinear density segregation generically present near threshold in metric models, in agreement with microscopic simulations.

Characterizing the dynamics of hydrothermal systems with muon tomography: the case of La Soufrière de Guadeloupe

NASA Astrophysics Data System (ADS)

Rosas-Carbajal, M.; Marteau, J.; Tramontini, M.; de Bremond d Ars, J.; Le Gonidec, Y.; Carlus, B.; Ianigro, J. C.; Deroussi, S.; Komorowski, J. C.; Gibert, D.

2017-12-01

Muon imaging has recently emerged as a powerful method to complement standard geophysical tools in the study of the Earth's subsurface. Muon measurements yield a radiography of the average density along the muon path, allowing to image large volumes of a geological body from a single observation point. Long-term measurements allow to infer density changes by tracking the associated variations in the muon flux. In the context of volcanic hydrothermal systems, this approach helps to characterize zones of steam formation, condensation, water infiltration and storage. We present results of imaging the La Soufrière de Guadeloupe dome and shallow active hydrothermal system with a network of muon telescopes viewing the dome from different positions around its base. First, we jointly invert the muon radiographies of the different telescopes with gravity data to obtain a three-dimensional density model of the lava dome. The model reveals an extended low density region where the hydrothermal system is most active. We then analyze the dynamics of the hydrothermal system from long-term measurements (more than 2 years of almost non-interrupted acquisition) with 5 simultaneous muon telescopes. We identify a periodicity of 1-2 months in the density increase/decrease in the most active zones below fumaroles and acid boiling ponds. Our simultaneous-muon telescope strategy provides constraints on the three-dimensional location of the density changes and an improved quantification of the associated mass flux changes. We compare the temporal trends acquired by the different muon telescopes to time-series of rainfall on the summit recharge area as well as to ground temperature profiles in the vicinity of thermal anomalies and high-discharge summit fumaroles.

Direct current plasma jet at atmospheric pressure operating in nitrogen and air

NASA Astrophysics Data System (ADS)

Deng, X. L.; Nikiforov, A. Yu.; Vanraes, P.; Leys, Ch.

2013-01-01

An atmospheric pressure direct current (DC) plasma jet is investigated in N2 and dry air in terms of plasma properties and generation of active species in the active zone and the afterglow. The influence of working gases and the discharge current on plasma parameters and afterglow properties are studied. The electrical diagnostics show that discharge can be sustained in two different operating modes, depending on the current range: a self-pulsing regime at low current and a glow regime at high current. The gas temperature and the N2 vibrational temperature in the active zone of the jet and in the afterglow are determined by means of emission spectroscopy, based on fitting spectra of N2 second positive system (C3Π-B3Π) and the Boltzmann plot method, respectively. The spectra and temperature differences between the N2 and the air plasma jet are presented and analyzed. Space-resolved ozone and nitric oxide density measurements are carried out in the afterglow of the jet. The density of ozone, which is formed in the afterglow of nitrogen plasma jet, is quantitatively detected by an ozone monitor. The density of nitric oxide, which is generated only in the air plasma jet, is determined by means of mass-spectroscopy techniques.

Reference models for thermospheric NO

NASA Technical Reports Server (NTRS)

Barth, C. A.

1989-01-01

Nitric oxide has been measured with an ultraviolet spectrometer on the polar-orbiting satellite Solar Mesosphere Explorer (SME) for the period January 1982 to August 1986. The nitric oxide database contains densities at all latitudes sorted into 5 degree bins and at altitudes between 100 and 140 km sorted into 3.3 km-bins. The largest densities occur at latitudes in the auroral zones where the density varies as a function of geomagnetic activity. Variations of a factor of 10 occur between times of intense activity and quiet times. At low latitudes, the nitric oxide density at 110 km varies from a mean value of 3 times 10(exp 7) molecules per cubic cm in January 1982 to a mean value of 4 times 10(exp 6) molecules per cubic cm during solar minimum conditions in 1986. In addition, the low-latitude nitric oxide density varies plus or minus 50 percent with a period of 27 days during times of high solar activity.

Habitat shifts and spatial distribution of the intertidal crab Neohelice ( Chasmagnathus ) granulata Dana

NASA Astrophysics Data System (ADS)

Casariego, Agustina Mendez; Alberti, Juan; Luppi, Tomás; Daleo, Pedro; Iribarne, Oscar

2011-08-01

Intertidal zones of estuaries and embayments of the SW Atlantic are dominated by the semiterrestrial burrowing grapsid crab, Neohelice ( Chasmagnathus) granulata, and characterized by extensive mud flats surrounded by salt marshes. In this work we examined spatial patterns of distribution of N. granulata during two years to explain their movement patterns. The results of the population sampling showed segregation by sex and size throughout the intertidal, with seasonal variations in densities and different condition indices for adults and juveniles at the different zones. The comparison of seasonal activity (ambulatory activity outside burrows) between marshes and mudflats shows that short term (e.g. daily) variations in activity were controlled by tides. Crabs were active at high tides but increased their activity on days with higher tidal amplitude. Seasonal activity showed that at both areas, females remain with low activity except for a peak in winter, while males showed the highest activity during summer in the mudflat zone, but not so in the marsh. This pattern can be the response to differences in stress tolerance, suggesting that high temperatures are limiting the performance of adult crabs during summer, especially at the marsh where physical conditions can be more critical. The spatial size segregation can be explained by differential mortality in each zone (estimated with tethered crabs), and by the juvenile movement between these zones (estimated with movement traps). Juvenile mortality is higher at the mudflat, while adult mortality is higher in the marsh. Smaller juveniles moved to the marsh, where the mortality is lower, and the larger juveniles moved towards the mudflat. This mortality is due almost exclusively to cannibalism, so our results suggest that this movement of different size classes between zones is controlled, at least in part, by intraspecific predation.

Density Zoning and Class Segregation in U.S. Metropolitan Areas

PubMed Central

Rothwell, Jonathan T.; Massey, Douglas S.

2013-01-01

Objectives Socioeconomic segregation rose substantially in U.S. cities during the final decades of the 20th century and we argue zoning regulations are an important cause for this increase. Methods We measure neighborhood economic segregation using the Gini Coefficient for neighborhood income inequality and the poor-affluent exposure index. These outcomes are regressed on an index of density zoning developed from the work of Pendall for 50 U.S. metropolitan areas, while controlling for other metropolitan characteristics likely to affect urban housing markets and class segregation. Results For both 2000 and changes from 1990 to 2000, OLS estimates reveal a strong relationship between density zoning and income segregation, and replication using 2SLS suggests that the relationship is causal. We also show that zoning is associated with higher inter-jurisdictional inequality. Conclusions Metropolitan areas with suburbs that restrict the density of residential construction are more segregated on the basis of income than those with more permissive density zoning regimes. This arrangement perpetuates and exacerbates racial and class inequality in the United States. PMID:21117332

Geological and geomorphological controls on groundwater occurrence in a hard rock region

NASA Astrophysics Data System (ADS)

Rajaveni, S. P.; Brindha, K.; Elango, L.

2017-06-01

Remote sensing and GIS tools have broadly helped hydrogeologists to delineate the groundwater prospective zones for watershed development and management. The origin, movement and existence of groundwater depends on several factors such as slope, drainage density, land use, geology, lineament density and geomorphology. Based on these, the mapping and identification of groundwater potential zones were carried out in a part of Nalgonda district, Telangana, India. The regions were categorised as high, moderate and low groundwater potential, and they were validated with the groundwater levels and yield of wells located in the corresponding zones. Extensive possibility for watershed development is possible in 41 % of the total 724 km2 and 46 % of the area offers moderate options. Any groundwater management project implemented in these favourable areas will bring maximum benefit. Similar studies should be considered necessary before designing a water resource development activity as it will reduce the cost on detailed field visits which are time-consuming.

A torque-measuring micromotor provides operator independent measurements marking four different density areas in maxillae.

PubMed

Di Stefano, Danilo Alessio; Arosio, Paolo; Piattelli, Adriano; Perrotti, Vittoria; Iezzi, Giovanna

2015-02-01

Bone density at implant placement site is a key factor to obtain the primary stability of the fixture, which, in turn, is a prognostic factor for osseointegration and long-term success of an implant supported rehabilitation. Recently, an implant motor with a bone density measurement probe has been introduced. The aim of the present study was to test the objectiveness of the bone densities registered by the implant motor regardless of the operator performing them. A total of 3704 bone density measurements, performed by means of the implant motor, were registered by 39 operators at different implant sites during routine activity. Bone density measurements were grouped according to their distribution across the jaws. Specifically, four different areas were distinguished: a pre-antral (between teeth from first right maxillary premolar to first left maxillary premolar) and a sub-antral (more distally) zone in the maxilla, and an interforaminal (between and including teeth from first left mandibular premolar to first right mandibular premolar) and a retroforaminal (more distally) zone in the lower one. A statistical comparison was performed to check the inter-operators variability of the collected data. The device produced consistent and operator-independent bone density values at each tooth position, showing a reliable bone-density measurement. The implant motor demonstrated to be a helpful tool to properly plan implant placement and loading irrespective of the operator using it.

The relationship between Anopheles gambiae density and rice cultivation in the savannah zone and forest zone of Côte d'Ivoire.

PubMed

Briët, Olivier J T; Dossou-Yovo, Joel; Akodo, Elena; van de Giesen, Nick; Teuscher, Thomas M

2003-05-01

In 13 villages in the savannah zone and 21 villages in the forest zone of Côte d'Ivoire, the biting density of the principal malaria vector, Anopheles gambiae, was studied as a function of rice cultivation in the inland valleys in a 2-km radius around each village. In the savannah villages, during the main season cropping period, surface water on rice-cultivated and to a lesser extent on uncultivated inland valleys seems to contribute strongly to the A. gambiae population density. For the off-season cropping period (which starts after the first light rains in the savannah zone), correlations were weaker. Breeding sites other than in inland valleys may play an important role in the savannah zone. In the forest zone, however, the A. gambiae population density was strongly correlated with the surface water availability (SWA) in the rice-cultivated inland valleys, whereas the correlation with the SWA in other (uncultivated) inland valleys was weak. The requirement of sunlit breeding sites for A. gambiae might explain this difference between zones. In the forest zone, only inland valleys cleared for rice cultivation meet this requirement, whereas all other inland valleys are covered with dense vegetation. In the savannah zone, however, most undergrowth is burnt during the dry season, which permits sunlight to reach puddles resulting from the first rains.

Slab dehydration in Cascadia and its relationship to volcanism, seismicity, and non-volcanic tremor

NASA Astrophysics Data System (ADS)

Delph, J. R.; Levander, A.; Niu, F.

2017-12-01

The characteristics of subduction beneath the Pacific Northwest (Cascadia) are variable along strike, leading to the segmentation of Cascadia into 3 general zones: Klamath, Siletzia, and Wrangelia. These zones show marked differences in tremor density, earthquake density, seismicity rates, and the locus and amount of volcanism in the subduction-related volcanic arc. To better understand what controls these variations, we have constructed a 3D shear-wave velocity model of the upper 80 km along the Cascadia margin from the joint inversion of CCP-derived receiver functions and ambient noise surface wave data using 900 temporary and permanent broadband seismic stations. With this model, we can investigate variations in the seismic structure of the downgoing oceanic lithosphere and overlying mantle wedge, the character of the crust-mantle transition beneath the volcanic arc, and local to regional variations in crustal structure. From these results, we infer the presence and distribution of fluids released from the subducting slab and how they affect the seismic structure of the overriding lithosphere. In the Klamath and Wrangelia zones, high seismicity rates in the subducting plate and high tremor density correlate with low shear velocities in the overriding plate's forearc and relatively little arc volcanism. While the cause of tremor is debated, intermediate depth earthquakes are generally thought to be due to metamorphic dehydration reactions resulting from the dewatering of the downgoing slab. Thus, the seismic characteristics of these zones combined with rather sparse arc volcanism may indicate that the slab has largely dewatered by the time it reaches sub-arc depths. Some of the water released during earthquakes (and possibly tremor) may percolate into the overriding plate, leading to slow seismic velocities in the forearc. In contrast, Siletzia shows relatively low seismicity rates and tremor density, with relatively higher shear velocities in the forearc. Siletzia also contains most of the young arc volcanoes in the Cascades, indicating that water is retained in the slab to depths where it can feed arc volcanism. Thus, the along strike variations in volcanic activity and seismic activity in Cascadia appear to be related to variations in depth of dewatering of the downgoing oceanic lithosphere.

Indicators of red squirrel (Tamiasciurus hudonicus) abundance in the whitebark pine zone

USGS Publications Warehouse

Mattson, D.J.; Reinhart, Daniel P.

1996-01-01

We investigated occupied squirrel middens and squirrel sightings and vocalizations as indicators of red squirrel (Tamiasciurus hudsonicus) abundance in the high-elevation whitebark pine (Pinus albicaulis) zone. Data were collected 1984-1989 from line transects located on 2 study sites in the Yellowstone ecosystem. We evaluated the performance of each measure on the basis of precision and biological considerations. We concluded that, of the 3 measures, active middens were the best indicator of red squirrel abundance. We also observed that the density of active middens dropped by 48%-66% between 1987 and 1989, following a severe drought and extensive wildfires that burned one of the study sites during 1988.

Basement structure based on gravity anomaly in the northern Noto peninsula, Central Japan

NASA Astrophysics Data System (ADS)

Mizubayashi, T.; Sawada, A.; Hamada, M.; Hiramatsu, Y.; Honda, R.

2012-12-01

Upper crustal block structures are usually defined by using surface information, such as geological and morphological data. The northern Noto Peninsula, central Japan, is divided into four geological block structures from tectonic geomorphologic perspectives (Ota and Hirakawa, 1979). This division is based on the surface crustal movement. To image the geological blocks three-dimensionally, it is necessary to construct a subsurface structure model. Gravity survey can clarify the detailed subsurface structure with dense gravity measurement. From the detailed Bouguer anomalies in the northwestern Noto Peninsula, Honda et al. (2008) suggested that the rupture size of the 2007 Noto Hanto earthquake was constrained by the geological block structures. Hiramatsu et al. (2008) also suggested the active faults on the seafloor, such as the source fault of the 2007 Noto Hanto earthquake plays a major role for the formation of the geological block structures. In this study, we analyze subsurface density structure based on the Bouguer anomaly and estimate the distribution of basement depth in the northern Noto Peninsula. We focus the relationship among the basement depth, the block structures and the active faults on the seafloor and discuss the block movement in the northern Noto Peninsula. We compiled the data measured and published previously (Gravity Database of Southwest Japan, 2001; Geological survey of Japan, 2004; Geographical survey institute of Japan, 2006; The Gravity Research Group in Southwest Japan, 2001; Komazawa and Okuma, 2010; Hokuriku electric power Co. Ltd., undisclosed) and calculated Bouguer anomaly in the northern Noto Peninsula. Based on this Bouguer anomaly, we analyzed subsurface density structures along 13 northeastern-southwestern profiles and 35 northwestern-southeastern profiles with the interval of 2 km using the two dimensional Talwani's method (Talwani et al., 1959). In the analysis, we assumed a density structure with four layers: basement (density is 2670kg/m3), Neocene volcanic rock (density is 2400kg/m3, or 2550kg/m3), Neocene sedimentary rock (density is 2200kg/m3), and Quaternary sedimentary rock (density is 1800kg/m3, or 1500kg/m3) (Honda et al., 2008). To compare our basement model to the geological block structures, we focus on a transition zone of the basement depth. We recognize that two of three geological block boundaries correspond to the transition zones. These boundaries also correspond to the boundary of active fault segments on the seafloor. Therefore, based on the relationship between the source fault of the 2007 Noto Hanto earthquake and the geological block, we suggest that the movement of those geological blocks is possibly controlled by the corresponding active fault segments. However, we find that the other block boundary doesn't correspond to the transition zone.

Universal time dependence of nighttime F region densities at high latitudes

NASA Technical Reports Server (NTRS)

De La Beaujardiere, O.; Wickwar, V. B.; Caudal, G.; Holt, J. M.; Craven, J. D.; Frank, L. A.; Brace, L. H.

1985-01-01

Coincident auroral-zone experiments using three incoherent-scatter radars at widely spaced longitudes are reported. The observational results demonstrate that, during the night, the F layer electron density is strongly dependent on the longitude of the observing site. Ionization patches were observed in the nighttime F region from the Chatanika and EISCAT radars, while densities observed from the Millstone radar were substantially smaller. The electron density within these maxima is larger at EISCAT than at Chatanika. When observed in the midnight sector auroral zone, these densities had a peak density at a high altitude of 360-475 km. The density was maximum when EISCAT was in the midnight sector and minimum when Millstone was in the midnight sector. A minimum in insolation in the auroral zone occurs at the UT when Millstone is in the midnight sector.

Optimization of Methods for Articular Cartilage Surface Tissue Engineering: Cell Density and Transforming Growth Factor Beta Are Critical for Self-Assembly and Lubricin Secretion.

PubMed

Iwasa, Kenjiro; Reddi, A Hari

2017-07-01

Lubricin/superficial zone protein (SZP)/proteoglycan4 (PRG4) plays an important role in boundary lubrication in articular cartilage. Lubricin is secreted by superficial zone chondrocytes and synoviocytes of the synovium. The specific objective of this investigation is to optimize the methods for tissue engineering of articular cartilage surface. The aim of this study is to investigate the effect of cell density on the self-assembly of superficial zone chondrocytes and lubricin secretion as a functional assessment. Superficial zone chondrocytes were cultivated as a monolayer at low, medium, and high densities. Chondrocytes at the three different densities were treated with transforming growth factor beta (TGF-β)1 twice a week or daily, and the accumulated lubricin in the culture medium was analyzed by immunoblots and quantitated by enzyme-linked immunosorbent assay (ELISA). Cell numbers in low and medium densities were increased by TGF-β1; whereas cell numbers in high-density cell cultures were decreased by twice-a-week treatment of TGF-β1. On the other hand, the cell numbers were maintained by daily TGF-β treatment. Immunoblots and quantitation of lubricin by ELISA analysis indicated that TGF-β1 stimulated lubricin secretion by superficial zone chondrocytes at all densities with twice-a-week TGF-β treatment. It is noteworthy that the daily treatment of TGF-β1 increased lubricin much higher compared with twice-a-week treatment. These data demonstrate that daily treatment is optimal for the TGF-β1 response in a higher density of monolayer cultures. These findings have implications for self-assembly of surface zone chondrocytes of articular cartilage for application in tissue engineering of articular cartilage surface.

Exhalation of (222)Rn from phosphogypsum piles located at the Southwest of Spain.

PubMed

Dueñas, C; Liger, E; Cañete, S; Pérez, M; Bolívar, J P

2007-01-01

Phosphogypsum (PG) is a waste product of the phosphoric acid production process and contains, generally, high activity concentrations of uranium series radionuclides. It is stored in piles formed over the last 40 years close to the town of Huelva (Southwest of Spain). The very broad expanse of the PG piles (about 1200 ha) produces a local, but unambiguous, radioactive impact to their surroundings. In 1992, the regional government of Andalusia restored an area of 400 ha by covering it with a 25-cm thick layer of natural soil and, currently, there is an additional zone of 400 ha in course of restoration (unrestored) and the same area of active PG stacks. Due to the high activity concentration of (226)Ra in active PG stacks (average 647 Bq kg(-1)), a significant exhalation of (222)Rn could be produced from the surface of the piles. Measurements have been made of (222)Rn exhalation from active PG stacks and from restored and unrestored zones. The (222)Rn exhalation from unrestored zones is half of that of the active PG stacks. Following restoration, the (222)Rn exhalation is approximately eight times lower than the active PG stacks. The activity concentrations of natural radionuclides ((226)Ra, (40)K, (232)Th) in the mentioned zones have been determined. This study was also conducted to determine the effect of (226)Ra activity concentration on the (222)Rn exhalation, and a good correlation was obtained between the (222)Rn exhalation and (226)Ra activity, porosity and density of soil.

Wetland use and feeding by lesser scaup during spring migration across the upper Midwest, USA

USGS Publications Warehouse

Anteau, M.J.; Afton, A.D.

2009-01-01

Low food availability and forage quality and concomitant decreased lipid reserves of lesser scaup (Aythya affinis; hereafter scaup) during spring migration in the upper Midwest may partially explain reductions in the continental population of scaup. In springs 20042005, we examined wetland use and feeding activity of scaup on 356 randomly-selected wetlands within 6 regions in Iowa, Minnesota, and North Dakota. We examined wetland characteristics that favor high scaup use in 286 of these wetlands. We found that probabilities of wetland use and feeding by scaup increased with turbidity up to 45 and 30 NTU, respectively, but then declined at higher turbidity levels. Wetland use was positively correlated with size of open-water zone and amphipod densities, but was not correlated with chironomid densities. Feeding increased with amphipod density up to 26 m-3 and then declined at higher amphipod densities; scaup seemingly forage most efficiently at amphipod densities above 26 m -3. Wetland use was higher in North Dakota than in southern Minnesota and Iowa. Our results indicate that effective wetland restoration efforts to benefit scaup require maintaining abundant populations of amphipods (generally near 26 m-3 landscape geometric mean) in wetlands with large (> 500 m diameter) open-water zones throughout the upper Midwest, but especially within Iowa and southern Minnesota.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roy, D.W.; Schmitt, L.; Woussen, G.

Airborne SAR images provided essential clues to the tectonic setting of (1) the MbLg 6.5 Saguenay earthquake of 25 November 1988, (2) the Charlevoix-Kamouraska seismic source zone, and (3) some of the low *eve* seismic activity in the Eastern seismic background zone of Canada. The event occurred in the southeastern part of the Canadian Shield in an area where the boundary between the Saguenay graben and the Jacques Cartier horst is not well defined. These two tectonic blocks are both associated with the Iapetan St-Lawrence rift. These blocks exhibit several important structural breaks and distinct domains defined by the lineamentmore » orientations, densities, and habits. Outcrop observations confirm that several lineament sets correspond to Precambrian ductile shear zones reactivated as brittle faults during the Phanerozoic. In addition, the northeast and southwest limits of recent seismic activity in the Charlevoix-Kamouraska zone correspond to major elements of the fracture pattern identified on the SAR images. These fractures appear to be related to the interaction of the Charlevoix astrobleme with the tectonic features of the area. 20 refs.« less

Sinking mafic body in a reactivated lower crust: A mechanism for stress concentration at the New Madrid seismic zone

USGS Publications Warehouse

Pollitz, F.F.; Kellogg, L.; Burgmann, R.

2001-01-01

We propose a geodynamic model for stress concentration in the New Madrid seismic zone (NMSZ). The model postulates that a high-density (mafic) body situated in the deep crust directly beneath the most seismically active part of the NMSZ began sinking several thousands of years ago when the lower crust was suddenly weakened. Based on the fact that deformation rates in the NMSZ have accelerated over the past 9 k.y., we envision the source of this perturbation to be related to the last North American deglaciation. Excess mass of the mafic body exerts a downward pull on the elastic upper crust, leading to a cycle of primary thrust faulting with secondary strike-slip faulting, after which continued sinking of the mafic body reloads the upper crust and renews the process. This model is consistent with the youth of activity, the generation of a sequence of earthquakes, and the velocity evolution during interseismic periods, which depend upon the density contrast of the mafic body with respect to the surrounding crust, its volume, and the viscosity of the lower crust.

Effect of friction on anodic polarization properties of metallic biomaterials.

PubMed

Okazaki, Yoshimitsu

2002-05-01

The effect of friction on the anodic polarization properties of metallic biomaterials in a physiological saline solution was investigated. The current density during friction becomes higher than during the static condition. The fluctuation range of the current density caused by the destruction and formation of passive film was observed. For SUS316L stainless steel and Co-Cr-Mo casting alloy, the fluctuation range was observed in the passivity zone. Otherwise, for Ti alloys, the fluctuation range was observed in both the activity and passivity zones. The decrease of the corrosion potential for Ti alloys due to friction was much larger than that of SUS316L stainless steel and Co-Cr-Mo casting alloy. From this result, it was considered that in a the frictional environment, the stressing zone turned anodic and its periphery cathodic, and corrosion tended to progress more than in the static environment. The effect of wear on the anodic polarization curves also changed depending on the frictional load, potential zone and the pH of the solution. A rapid increase in current density due to corrosion starting from the frictional area was found in the Ti-6Al-4V and Ti-15Mo-5Zr-3Al alloys containing Al. However, for the new Ti-15Zr-4Nb-4Ta alloy, this rapid increase was not seen in the high-potential region. The effect of the lateral reciprocal speed was also negligible for the new Ti alloy. It was found that the new Ti-15Zr-4Nb-4Ta alloy exhibited excellent corrosion resistance under friction.

Self-organization and self-limitation in high power impulse magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anders, Andre

The plasma over the racetrack in high power impulse magnetron sputtering develops in traveling ionization zones. Power densities can locally reach 10{sup 9} W/m{sup 2}, which is much higher than usually reported. Ionization zones move because ions are 'evacuated' by the electric field, exposing neutrals to magnetically confined, drifting electrons. Drifting secondary electrons amplify ionization of the same ionization zone where the primary ions came from, while sputtered and outgassing atoms are supplied to the following zone(s). Strong density gradients parallel to the target disrupt electron confinement: a negative feedback mechanism that stabilizes ionization runaway.

Fault Damage Zone Permeability in Crystalline Rocks from Combined Field and Laboratory Measurements

NASA Astrophysics Data System (ADS)

Mitchell, T.; Faulkner, D.

2008-12-01

In nature, permeability is enhanced in the damage zone of faults, where fracturing occurs on a wide range of scales. Here we analyze the contribution of microfracture damage on the permeability of faults that cut through low porosity, crystalline rocks by combining field and laboratory measurements. Microfracture densities surrounding strike-slip faults with well-constrained displacements ranging over 3 orders of magnitude (~0.12 m - 5000 m) have been analyzed. The faults studied are excellently exposed within the Atacama Fault Zone, where exhumation from 6-10 km has occurred. Microfractures in the form of fluid inclusion planes (FIPs) show a log-linear decrease in fracture density with perpendicular distance from the fault core. Damage zone widths defined by the density of FIPs scale with fault displacement, and an empirical relationship for microfracture density distribution throughout the damage zone with displacement is derived. Damage zone rocks will have experienced differential stresses that were less than, but some proportion of, the failure stress. As such, permeability data from progressively loaded, initially intact laboratory samples, in the pre-failure region provide useful insights into fluid flow properties of various parts of the damage zone. The permeability evolution of initially intact crystalline rocks under increasing differential load leading to macroscopic failure was determined at water pore pressures of 50 MPa and effective pressure of 10 MPa. Permeability is seen to increase by up to, and over, two orders of magnitude prior to macroscopic failure. Further experiments were stopped at various points in the loading history in order to correlate microfracture density within the samples with permeability. By combining empirical relationships determined from both quantitative fieldwork and experiments we present a model that allows microfracture permeability distribution throughout the damage zone to be determined as function of increasing fault displacement.

State-of-stress in magmatic rift zones: Predicting the role of surface and subsurface topography

NASA Astrophysics Data System (ADS)

Oliva, S. J. C.; Ebinger, C.; Rivalta, E.; Williams, C. A.

2017-12-01

Continental rift zones are segmented along their length by large fault systems that form in response to extensional stresses. Volcanoes and crustal magma chambers cause fundamental changes to the density structure, load the plates, and alter the state-of-stress within the crust, which then dictates fracture orientation. In this study, we develop geodynamic models scaled to a < 7 My rift sector in the Eastern rift, East Africa where geophysical imaging provides tight constraints on subsurface structure, petrologic and thermodynamic studies constrain material densities, and seismicity and structural analyses constrain active and time-averaged kinematics. This area is an ideal test area because a 60º stress rotation is observed in time-averaged fault and magma intrusion, and in local seismicity, and because this was the site of a large volume dike intrusion and seismic sequence in 2007. We use physics-based 2D and 3D models (analytical and finite elements) constrained by data from active rift zones to quantify the effects of loading on state-of-stress. By modeling varying geometric arrangements, and density contrasts of topographic and subsurface loads, and with reasonable regional extensional forces, the resulting state-of-stress reveals the favored orientation for new intrusions. Although our models are generalized, they allow us to evaluate whether a magmatic system (surface and subsurface) can explain the observed stress rotation, and enable new intrusions, new faults, or fault reactivation with orientations oblique to the main border faults. Our results will improve our understanding of the different factors at play in these extensional regimes, as well as contribute to a better assessment of the hazards in the area.

Heterogeneous distribution of exocytotic microdomains in adrenal chromaffin cells resolved by high-density diamond ultra-microelectrode arrays.

PubMed

Gosso, Sara; Turturici, Marco; Franchino, Claudio; Colombo, Elisabetta; Pasquarelli, Alberto; Carbone, Emilio; Carabelli, Valentina

2014-08-01

Here we describe the ability of a high-density diamond microelectrode array targeted to resolve multi-site detection of fast exocytotic events from single cells. The array consists of nine boron-doped nanocrystalline diamond ultra-microelectrodes (9-Ch NCD-UMEA) radially distributed within a circular area of the dimensions of a single cell. The device can be operated in voltammetric or chronoamperometric configuration. Sensitivity to catecholamines, tested by dose-response calibrations, set the lowest detectable concentration of adrenaline to ∼5 μm. Catecholamine release from bovine or mouse chromaffin cells could be triggered by electrical stimulation or external KCl-enriched solutions. Spikes detected from the cell apex using carbon fibre microelectrodes showed an excellent correspondence with events measured at the bottom of the cell by the 9-Ch NCD-UMEA, confirming the ability of the array to resolve single quantal secretory events. Subcellular localization of exocytosis was provided by assigning each quantal event to one of the nine channels based on its location. The resulting mapping highlights the heterogeneous distribution of secretory activity in cell microdomains of 12-27 μm2. In bovine chromaffin cells, secretion was highly heterogeneous with zones of high and medium activity in 54% of the cell surface and zones of low or no activity in the remainder. The 'non-active' ('silent') zones covered 24% of the total and persisted for 6-8 min, indicating stable location. The 9-Ch NCD-UMEA therefore appears suitable for investigating the microdomain organization of neurosecretion with high spatial resolution. © 2014 The Authors. The Journal of Physiology © 2014 The Physiological Society.

Age-related changes in the articular cartilage of the stifle joint in non-working and working German Shepherd dogs.

PubMed

Francuski, J V; Radovanović, A; Andrić, N; Krstić, V; Bogdanović, D; Hadzić, V; Todorović, V; Lazarević Macanović, M; Sourice Petit, S; Beck-Cormier, S; Guicheux, J; Gauthier, O; Kovacević Filipović, M

2014-11-01

The aims of this study were to define age-related histological changes in the articular cartilage of the stifle joint in non-chondrodystrophic dogs and to determine whether physical activity has a positive impact on preservation of cartilage structure during ageing. Twenty-eight German shepherd dogs were included in the study. These dogs had no evidence of joint inflammation as defined by clinical assessment, radiology and synovial fluid analysis (specifically absence of synovial fluid serum amyloid A). The dogs were grouped as young working (n ¼ 4), young non-working (n ¼ 5), aged working (n ¼ 13) and aged non-working (n ¼ 6) animals. Gross changes in the stifle joints were recorded and biopsy samples of femoral and tibial articular cartilage were evaluated for thickness; chondrocyte number, density, surface area and morphology; isogenous group morphology; tidemark integrity; subchondral bone structure; presence of proteoglycans/ glycosaminoglycans; and expression of type I, II and X collagens. The major age-related changes, not related to type of physical activity, included elevated chondrocyte density and thinning of tibial cartilage and increased chondrocyte surface area in the superficial and intermediate zone of the femoral cartilage. There was also expression of type X collagen in the femoral and tibial calcified and non-calcified cartilage; however, type X collagen was not detected in the superficial zone of old working dogs. Therefore, ageing, with or without physical activity, leads to slight cartilage degeneration, while physical activity modulates the synthesis of type X collagen in the superficial cartilage zone, partially preserving the structure of hyaline cartilage. 2014 Elsevier Ltd. All rights reserved.

CO2 concentration and occupancy density in the critical zones served by the VAV system

NASA Astrophysics Data System (ADS)

Etoua Evina, Ghislaine; Kajl, Stanislaw; Lamarche, Louis; Beltran-Galindo, Javier

2017-11-01

This article presents the results obtained from monitoring a VAV system with highly diversified zone occupancy density are presented in the article. The investigated VAV system meets the load for 72 zones (68 perimeters and 4 interiors) consisting of classrooms, offices, conference rooms, etc. with highly diversified occupancy densities from 1.875 to 2.5 m2/person for the classrooms and from 10 to 15 m2/person for the offices. The monitoring shows that the CO2 concentration can exceed the set point in the critical rooms. Simulation results are also presented in the article to show that it is often impossible to adjust the operation of such VAV systems because the adjusted System Outdoor Air Fractions, % OA, can reach 100% even where the zone CO2 concentration is not respected. The presented monitoring and simulation results were obtained in the winter, with the VAV system operating at partial load and with the minimum outdoor air flowrate required by the economizer system. As shown in the article, to respect the zone set point CO2 concentration in such period, the VAV system must operate mostly at a %OA equal to 100% instead of its minimum value. To circumvent this, the supply zone air flow rate may have to be designed taking into account the CO2 concentration resulting from the critical zones occupancy density.

A comparison of food pattern, macro- and some micronutrients density of the diet across different socio-economic zones of Tehran

PubMed Central

Abdollahi, Morteza; Salehi, Forouzan; Kalantari, Naser; Asadilari, Mohsen; Khoshfetrat, Mohammad Reza; Ajami, Marjan

2016-01-01

Background: The consumption of low quality foods is common in low socioeconomic areas; and according to epidemiological studies, the density of nutrients often proves the quality of diet. This study aimed to compare the density of macronutrients and micronutrients in various parts of Tehran. Methods: This was a cross-sectional study performed from September to December 2007 in all the 22 districts of the municipality of Tehran including 1,807 households. Experienced interviewers completed a 24-hour recall questionnaire. To estimate the nutrient densities, nutrient intake (grams or milligrams) was calculated per 1,000 kcal energy intake. To calculate the density of energy intake, energy intake (kcal) was divided by 100 g of foodstuff. The 22 districts of Tehran were divided into five zones of north, center, east, west and south. ANOVA and Tukey tests were used. Results: The highest density of protein and fat intake was observed in the north of Tehran, while carbohydrate density was highest in the west, east and south zones, and energy density was highest in the south zone (p<0.05). Calcium and vitamin C had the highest density in the north of Tehran, and vitamin A and riboflavin had the highest density in the north and center of Tehran, and the lowest level in the south of Tehran (p<0.05). Conclusion: Despite the high density of energy in the south of Tehran, a deficiency of micronutrient intake was obvious, reflecting the importance of the impact of socioeconomic factors. PMID:27390710

First measurements of the temporal evolution of the plasma density in HiPIMS discharges using THz time domain spectroscopy

NASA Astrophysics Data System (ADS)

Meier, Steffen M.; Hecimovic, Ante; Tsankov, Tsanko V.; Luggenhölscher, Dirk; Czarnetzki, Uwe

2018-03-01

In this paper, the novel technique of THz time domain spectroscopy has been applied to obtain time-resolved measurements of the plasma density in the active zone of a HiPIMS discharge with a titanium target. The obtained peak values are in the range of 1012-1013 cm-3 for discharge current densities of 1-4 A cm-2 at 0.5 and 2 Pa argon pressure. The measured densities show good correlation with the discharge current and voltage and the intensity of various atomic and ionic lines. The well known phases of the discharge have been identified and related to the variation of the electron density. The measurement results show that the plasma density remains nearly constant during the runaway/self-sputtering phase. Based on that, it is conjectured that singly charged titanium ions are the dominant ion species during this phase.

Differential intensity-dependent effects of magnetic stimulation on the longest neurites and shorter dendrites in neuroscreen-1 cells

NASA Astrophysics Data System (ADS)

Lin, Ching-Yi; Huang, Whitney J.; Li, Kevin; Swanson, Roy; Cheung, Brian; Lin, Vernon W.; Lee, Yu-Shang

2015-04-01

Objective. Magnetic stimulation (MS) is a potential treatment for neuropsychiatric disorders. This study investigates whether MS-regulated neuronal activity can translate to specific changes in neuronal arborization and thus regulate synaptic activity and function. Approach. To test our hypotheses, we examined the effects of MS on neurite growth of neuroscreen-1 (NS-1) cells over the pulse frequencies of 1, 5 and 10 Hz at field intensities controlled via machine output (MO). Cells were treated with either 30% or 40% MO. Due to the nature of circular MS coils, the center region of the gridded coverslip (zone 1) received minimal (∼5%) electromagnetic current density while the remaining area (zone 2) received maximal (∼95%) current density. Plated NS-1 cells were exposed to MS twice per day for three days and then evaluated for length and number of neurites and expression of brain-derived neurotrophic factor (BDNF). Main results. We show that MS dramatically affects the growth of the longest neurites (axon-like) but does not significantly affect the growth of shorter neurites (dendrite-like). Also, MS-induced changes in the longest neurite growth were most evident in zone 1, but not in zone 2. MS effects were intensity-dependent and were most evident in bolstering longest neurite outgrowth, best seen in the 10 Hz MS group. Furthermore, we found that MS-increased BDNF expression and secretion was also frequency-dependent. Taken together, our results show that MS exerts distinct effects when different frequencies and intensities are applied to the neuritic compartments (longest neurite versus shorter dendrite(s)) of NS-1 cells. Significance. These findings support the concept that MS increases BDNF expression and signaling, which sculpts longest neurite arborization and connectivity by which neuronal activity is regulated. Understanding the mechanisms underlying MS is crucial for efficiently incorporating its use into potential therapeutic strategies.

The effect of potassium on exocytosis of transmitter at the frog neuromuscular junction.

PubMed Central

Ceccarelli, B; Fesce, R; Grohovaz, F; Haimann, C

1988-01-01

1. Electrophysiology and morphology have been combined to investigate the time course of the exocytosis of quanta of neurotransmitter induced by elevated concentrations of K+ at the frog neuromuscular junction. 2. Replicas of freeze-fractured resting nerve terminals fixed in the presence of 20 mM-K+ showed images of fusion of synaptic vesicles with the presynaptic axolemma which were closely associated with the active zones. After 1 min in 20 nM-K+ fusions appeared also outside the active zones, and by 5 min they became uniformly distributed over the presynaptic membrane. 3. The average total density of fusions was not significantly different at the various times examined since it decreased at the active zones while it increased over the rest of the membrane. 4. Resting terminals fixed in 20 mM-K+ released 33,000-45,000 quanta after the addition of fixative; terminals stimulated by 20 mM-K+ for 1-5 min released 50,000-100,000 quanta during fixation. The fixative potentiated K+-induced transmitter release. 5. Fusions were uniformly distributed in terminals pre-incubated for 5 min in 20 mM-K+ without added Ca2+, stimulated by adding Ca2+ for 30 s, and then fixed. Conversely, after 5 min stimulation in hypertonic Ringer solution fusions remained predominantly located near the active zones. A similar distribution was observed after 15 min stimulation by a lower concentration of K+ (15 mM). 6. At all concentrations of K+ tested (10, 15, 20, 25 mM) miniature end-plate potential (MEPP) rate attained a steady-state value within 10-15 min. Values from a single junction were generally lower at higher concentrations of K+, which indicates partial inactivation of the secretion-recycling process. 7. The data indicate that K+ initially activates exocytosis at the active zones. Subsequently, ectopic exocytosis is activated while sites at the active zones appear to undergo partial inactivation. These phenomena are not related to the intensity or to the amount of previous secretion. Images Fig. 1 Fig. 2 Fig. 3 Fig. 8 Fig. 10 PMID:2902217

Summer distributions of forage fish in the eastern Bering Sea

NASA Astrophysics Data System (ADS)

Parker-Stetter, Sandra L.; Horne, John K.; Farley, Edward V.; Barbee, David H.; Andrews, Alexander G.; Eisner, Lisa B.; Nomura, Jennifer M.

2013-10-01

Juvenile and small adult fish, typically called forage fish, are an important but poorly studied part of the eastern Bering Sea (EBS) ecosystem. Acoustic and trawl data from a non-target survey were used to evaluate distributions of capelin (Mallotus villosus), age-0 Pacific cod (Gadus macrocephalus), and age-0 walleye pollock (Theragra chalcogramma, herein pollock) in 2006-2010. Within the surface zone (15 m to ~35 m, evaluated 2006-2010), capelin occurred throughout the EBS but primarily in the middle shelf. Capelin were also present in the midwater zone (~35 m to 0.5 m off-bottom) in both 2009 and 2010 (evaluated 2009-2010), and resulted in water column zone (15 m to 0.5 m off-bottom) distributions that differed from surface zone characterizations. Age-0 Pacific cod occurred primarily in the surface zone of the middle and outer shelf regions in all years. As midwater and surface zone age-0 Pacific cod were often coincident, water column zone distributions in 2009-2010 were similar to surface zone distributions. Age-0 pollock were found in the EBS surface zone in all years, primarily in the middle and outer shelf regions. High densities of age-0 pollock occurred in the midwater zone in 2006-2007 and 2009-2010. Water column zone distributions of age-0 pollock were similar to surface zone distributions in 2006-2007, but differed in 2009-2010 due to low numbers of age-0 pollock in the surface zone and presence of high densities in the midwater zone of the outer shelf region. While general patterns in capelin distribution in the surface zone were similar between the present and the previous studies, the acoustic-trawl characterization suggested that capelin densities were high in the middle shelf region. As expected, surface zone distributions of age-0 Pacific cod and age-0 pollock were similar to previous characterizations. Observed high densities of midwater age-0 pollock have not been described by previous studies. Annual abundance indices based on bottom or surface trawl data alone will not be sufficient in all years. Data and conclusions from non-target surveys may be constrained compared to dedicated survey efforts, but can provide baseline distributions, potential abundance indices, and insight for planning future research.

Landslide susceptibility mapping for a part of North Anatolian Fault Zone (Northeast Turkey) using logistic regression model

NASA Astrophysics Data System (ADS)

Demir, Gökhan; aytekin, mustafa; banu ikizler, sabriye; angın, zekai

2013-04-01

The North Anatolian Fault is know as one of the most active and destructive fault zone which produced many earthquakes with high magnitudes. Along this fault zone, the morphology and the lithological features are prone to landsliding. However, many earthquake induced landslides were recorded by several studies along this fault zone, and these landslides caused both injuiries and live losts. Therefore, a detailed landslide susceptibility assessment for this area is indispancable. In this context, a landslide susceptibility assessment for the 1445 km2 area in the Kelkit River valley a part of North Anatolian Fault zone (Eastern Black Sea region of Turkey) was intended with this study, and the results of this study are summarized here. For this purpose, geographical information system (GIS) and a bivariate statistical model were used. Initially, Landslide inventory maps are prepared by using landslide data determined by field surveys and landslide data taken from General Directorate of Mineral Research and Exploration. The landslide conditioning factors are considered to be lithology, slope gradient, slope aspect, topographical elevation, distance to streams, distance to roads and distance to faults, drainage density and fault density. ArcGIS package was used to manipulate and analyze all the collected data Logistic regression method was applied to create a landslide susceptibility map. Landslide susceptibility maps were divided into five susceptibility regions such as very low, low, moderate, high and very high. The result of the analysis was verified using the inventoried landslide locations and compared with the produced probability model. For this purpose, Area Under Curvature (AUC) approach was applied, and a AUC value was obtained. Based on this AUC value, the obtained landslide susceptibility map was concluded as satisfactory. Keywords: North Anatolian Fault Zone, Landslide susceptibility map, Geographical Information Systems, Logistic Regression Analysis.

Evidence of a temperature transition for denuded zone formation in nanocrystalline Fe under He irradiation

DOE PAGES

El-Atwani, Osman; Nathaniel II, James E.; Leff, Asher C.; ...

2016-10-18

Nanocrystalline materials are radiation-tolerant materials’ candidates due to their high defect sink density. Here, nanocrystalline iron films were irradiated with 10 keV helium ions in situ in a transmission electron microscope at elevated temperatures. Grain-size-dependent bubble density changes and denuded zone occurrence were observed at 700 K, but not at 573 K. This transition, attributed to increased helium–vacancy migration at elevated temperatures, suggests that nanocrystalline microstructures are more resistant to swelling at 700 K due to decreased bubble density. Finally, denuded zone formation had no correlation with grain size and misorientation angle under the conditions studied.

An analysis of OH excited state absorption lines in DR 21 and K3-50

NASA Astrophysics Data System (ADS)

Jones, K. N.; Doel, R. C.; Field, D.; Gray, M. D.; Walker, R. N. F.

1992-10-01

We present an analysis of the OH absorption line zones observed toward the compact H II regions DR 21 and K3-50. Using as parameters the kinetic and dust temperatures, the H2 number density and the ratio of OH-H2 number densities to the velocity gradient, the model quantitatively reproduces the absorption line data for the six main line transitions in 2 Pi3/2 J = 5/2, 7/2, and 9/2. Observed upper limits for the absorption or emission in the satellite lines of 2 Pi3/2 J = 5/2 are crucial in constraining the range of derived parameters. Physical conditions derived for DR 21 show that the kinetic temperature centers around 140 K, the H2 number density around 10 exp 7/cu cm, and that the OH column density in the excited state absorption zone lies between 1 x 10 exp 15/sq cm and 2 x 10 exp 15/sq cm. Including contributions from a J = 3/2 absorption zone, the total OH column density is more than a factor of 2 lower than estimates based upon LTE (Walmsley et al., 1986). The OH absorption zone in K3-50 tends toward higher density and displays a larger column density, while the kinetic temperature is similar. For both sources, the dust temperature is found to be significantly lower than the kinetic temperature.

Can dead zones create structures like a transition disk?

NASA Astrophysics Data System (ADS)

Pinilla, Paola; Flock, Mario; Ovelar, Maria de Juan; Birnstiel, Til

2016-12-01

Context. Regions of low ionisation where the activity of the magneto-rotational instability is suppressed, the so-called dead zones, have been suggested to explain gaps and asymmetries of transition disks. Dead zones are therefore a potential cause for the observational signatures of transition disks without requiring the presence of embedded planets. Aims: We investigate the gas and dust evolution simultaneously assuming simplified prescriptions for a dead zone and a magnetohydrodynamic (MHD) wind acting on the disk. We explore whether the resulting gas and dust distribution can create signatures similar to those observed in transition disks. Methods: We imposed a dead zone and/or an MHD wind in the radial evolution of gas and dust in protoplanetary disks. For the dust evolution, we included the transport, growth, and fragmentation of dust particles. To compare with observations, we produced synthetic images in scattered optical light and in thermal emission at mm wavelengths. Results: In all models with a dead zone, a bump in the gas surface density is produced that is able to efficiently trap large particles (≳ 1 mm) at the outer edge of the dead zone. The gas bump reaches an amplitude of a factor of 5, which can be enhanced by the presence of an MHD wind that removes mass from the inner disk. While our 1D simulations suggest that such a structure can be present only for 1 Myr, the structure may be maintained for a longer time when more realistic 2D/3D simulations are performed. In the synthetic images, gap-like low-emission regions are seen at scattered light and in thermal emission at mm wavelengths, as previously predicted in the case of planet-disk interaction. Conclusions: Main signatures of transition disks can be reproduced by assuming a dead zone in the disk, such as gap-like structure in scattered light and millimetre continuum emission, and a lower gas surface density within the dead zone. Previous studies showed that the Rossby wave instability can also develop at the edge of such dead zones, forming vortices and also creating asymmetries.

Structural control of monogenetic volcanism in the Garrotxa volcanic field (Northeastern Spain) from gravity and self-potential measurements

NASA Astrophysics Data System (ADS)

Barde-Cabusson, S.; Gottsmann, J.; Martí, J.; Bolós, X.; Camacho, A. G.; Geyer, A.; Planagumà, Ll.; Ronchin, E.; Sánchez, A.

2014-01-01

We report new geophysical observations on the distribution of subsurface structures associated with monogenetic volcanism in the Garrotxa volcanic field (Northern Spain). As part of the Catalan Volcanic Zone, this Quaternary volcanic field is associated with the European rifts system. It contains the most recent and best preserved volcanic edifices of the Catalan Volcanic Zone with 38 monogenetic volcanoes identified in the Garrotxa Natural Park. We conducted new gravimetric and self-potential surveys to enhance our understanding of the relationship between the local geology and the spatial distribution of the monogenetic volcanoes. The main finding of this study is that the central part of the volcanic field is dominated by a broad negative Bouguer anomaly of around -0.5 mGal, within which a series of gravity minima are found with amplitudes of up to -2.3 mGal. Inverse modelling of the Bouguer data suggests that surficial low-density material dominates the volcanic field, most likely associated with effusive and explosive surface deposits. In contrast, an arcuate cluster of gravity minima to the NW of the Croscat volcano, the youngest volcano of this zone, is modelled by vertically extended low-density bodies, which we interpret as a complex ensemble of fault damage zones and the roots of young scoria cones. A ground-water infiltration zone identified by a self-potential anomaly is associated with a steep horizontal Bouguer gravity gradient and interpreted as a fault zone and/or magmatic fissure, which fed the most recent volcanic activity in the Garrotxa. Gravimetric and self-potential data are well correlated and indicate a control on the locations of scoria cones by NNE-SSW and NNW-SSE striking tectonic features, which intersect the main structural boundaries of the study area to the north and south. Our interpretation of the data is that faults facilitated magma ascent to the surface. Our findings have major implications for understanding the relationship between subsurface structures and potential future volcanic activity in the Garrotxa volcanic field.

Spatial organization of seismicity and fracture pattern at the boundary between Alps and Dinarides

NASA Astrophysics Data System (ADS)

Bressan, Gianni; Ponton, Maurizio; Rossi, Giuliana; Urban, Sandro

2016-04-01

The paper affords the study of the spatial organization of seismicity in the easternmost region of the Alps (Friuli, in NE Italy and W Slovenia), dominated by the interference between the Alpine and the Dinaric tectonic systems. Two non-conventional methods of spatial analysis are used: fractal analysis and principal component analysis (PCA). The fractal analysis helps to discriminate the cases in which hypocentres clearly define a plane, from the ones in which hypocenter distribution tends to the planarity, without reaching it. The PCA analysis is used to infer the orientation of planes fitting through earthquake foci, or the direction of propagation of the hypocentres. Furthermore, we study the spatial seismicity pattern at the shallow depths in the context of a general damage model, through the crack density distribution. The results of the three methods concur to a complex and composite model of fracturing in the region. The hypocentre pattern fills only partially a plane, i.e. has a fractal dimension close to 2. The three exceptions regard planes with Dinaric trend, without interference with Alpine lineaments. The shallowest depth range (0-10 km depth) is characterized by the activation of planes with variable orientations, reflecting the interference between the Dinaric and the Alpine tectonic structures, and closely bound to the variation of the mechanical properties of the crust. The seismicity occurs mostly in areas characterized by a variation from low to moderate crack density, indicating the sharp transition from zones of low damage to zones of moderate damage. Low crack density indicates the presence of more competent rocks capable of sustaining high strain energy while high crack density areas pertain to highly fractured rocks that cannot store high strain energy. Brittle failure, i.e. seismic activity, is favoured within the sharp transitions from low to moderate crack density zones. The orientation of the planes depicting the seismic activity, indeed, coincides with the orientation of the faults generated along the flanks of past carbonate platforms both in Friuli and western Slovenia. In the deepest depth range (10-20-km depth), on the contrary, the study evidences the dominance of the tectonic Dinaric system to the NW of the External Dinarides, in depth. This depth interval is characterized by a more organized pattern of seismicity. Seismic events mainly locate on the Dinaric lineaments in the northern and eastern parts of the region considered, while on Alpine thrusts in the western and southern parts.

Comparative Evaluation of Antibacterial Effect of Dental Luting Cements on Streptococcus mutans and Lactobacillus acidophilus: An In vitro Study.

PubMed

Feroz, Sma; Bhoyar, A; Khan, S

2016-12-01

This study aimed at evaluating and comparing the antibacterial activity of six types of dental luting cements on Streptococcus mutans and Lactobacillus acidophilus using the agar diffusion test (ADT) and the direct-contact test (DCT). The antibacterial activity in ADT was measured based on the diameter of the zone of inhibition formed, whereas in DCT the density of the bacterial suspension was measured. The lower the density of the suspension, the more antibacterial activity the cement possesses. Agar diffusion test was carried out on the bacteria. After an incubation period of 24 hours, the plates were checked for the presence of zone of inhibition. In DCT the cement was mixed and applied. Once the cement was set, bacterial suspension and brain-heart infusion medium was poured and incubated for 24 hours. After 24 hours, the plate was placed in the enzyme-linked immunosorbent assay plate reader, which measured the optical density of the fluid. The first set of data was recorded approximately 1 hour after incubation. Overall, three sets of data were recorded. Additional experiments were performed on set test materials that were allowed to age for 24 hours, 1 week, 1, 3, and 6 months. When using ADT only two cements zinc oxide eugenol (ZOE) and zinc polycarboxylate (ZPC) cement showed antibacterial activity against the test organisms. When using DCT, all cements showed some amount of antibacterial activity. Zinc oxide eugenol and ZPC cement showed highest amount of antibacterial activity against S. mutans and L. acidophilus respectively. Within the limitations of study, ZOE cement and ZPC cement were most effective against the tested microorganisms followed by the newer resin cement. The glass ionomer cement was the weakest of all. Patients with high caries index can be treated more effectively using the abovementioned cements.

Is Urografin density gradient centrifugation suitable to separate nonculturable cells from Escherichia coli populations?

PubMed

Arana, Inés; Orruño, Maite; Seco, Carolina; Muela, Alicia; Barcina, Isabel

2008-03-01

The ability of Urografin or Percoll density gradient centrifugations to separate nonculturable subpopulations from heterogeneous Escherichia coli populations was analysed. Bacterial counts (total, active and culturable cells) and flow cytometric analyses were carried out in all recovered bands. After Urografin centrifugation, and despite the different origin of E. coli populations, a common pattern was obtained. High-density bands were formed mainly by nonculturable cells. However, the increase in cell density would not be common to all nonculturable cells, since part of this subpopulations banded in low-density zones, mixed with culturable cells. Bands obtained after Percoll centrifugation were heterogeneous and culturable and nonculturable cells were recovered along the gradient. Thus, fractionation in Urografin cannot be only attributed to changes in buoyant densities during the transition from culturable to nonculturable state. Urografin density gradients allow us to obtain enriched fractions in nonculturable subpopulations from a heterogeneous population, but working conditions should be carefully chosen to avoid Urografin toxicity.

Fault Damage Zone Permeability in Crystalline Rocks from Combined Field and Laboratory Measurements: Can we Predict Damage Zone Permeability?

NASA Astrophysics Data System (ADS)

Mitchell, T. M.; Faulkner, D. R.

2009-04-01

Models predicting crustal fluid flow are important for a variety of reasons; for example earthquake models invoking fluid triggering, predicting crustal strength modelling flow surrounding deep waste repositories or the recovery of natural resources. Crustal fluid flow is controlled by both the bulk transport properties of rocks as well as heterogeneities such as faults. In nature, permeability is enhanced in the damage zone of faults, where fracturing occurs on a wide range of scales. Here we analyze the contribution of microfracture damage on the permeability of faults that cut through low porosity, crystalline rocks by combining field and laboratory measurements. Microfracture densities surrounding strike-slip faults with well-constrained displacements ranging over 3 orders of magnitude (~0.12 m - 5000 m) have been analyzed. The faults studied are excellently exposed within the Atacama Fault Zone, where exhumation from 6-10 km has occurred. Microfractures in the form of fluid inclusion planes (FIPs) show a log-linear decrease in fracture density with perpendicular distance from the fault core. Damage zone widths defined by the density of FIPs scale with fault displacement, and an empirical relationship for microfracture density distribution throughout the damage zone with displacement is derived. Damage zone rocks will have experienced differential stresses that were less than, but some proportion of, the failure stress. As such, permeability data from progressively loaded, initially intact laboratory samples, in the pre-failure region provide useful insights into fluid flow properties of various parts of the damage zone. The permeability evolution of initially intact crystalline rocks under increasing differential load leading to macroscopic failure was determined at water pore pressures of 50 MPa and effective pressure of 10 MPa. Permeability is seen to increase by up to, and over, two orders of magnitude prior to macroscopic failure. Further experiments were stopped at various points in the loading history in order to correlate microfracture density within the samples with permeability. By combining empirical relationships determined from both quantitative fieldwork and experiments we present a new model that allows microfracture permeability distribution throughout the damage zone to be determined as function of increasing fault displacement.

Surface Melt and Firn Density Evolution in the Western Greenland Percolation Zone Over the Past 50 Years

NASA Astrophysics Data System (ADS)

Graeter, K.; Osterberg, E. C.; Hawley, R. L.; Thundercloud, Z. R.; Marshall, H. P.; Ferris, D. G.; Lewis, G.

2016-12-01

Predictions of the Greenland Ice Sheet's (GIS) contribution to sea-level rise in a warming climate depend on our ability to model the surface mass balance (SMB) processes occurring across the ice sheet. These processes are poorly constrained in the percolation zone, the region of the ice sheet where surface melt refreezes in the firn, thus preventing that melt from directly contributing to GIS mass loss. In this way, the percolation zone serves as a buffer to higher temperatures increasing mass loss. However, it is unknown how the percolation zone is evolving in a changing climate and to what extent the region will continue to serve as a buffer to future runoff. We collected seven shallow ( 22-30 m) firn cores from the Western Greenland percolation zone in May-June 2016 as part of the Greenland Traverse for Accumulation and Climate Studies (GreenTrACS) project. Here we present data on melt layer stratigraphy, density, and annual accumulation for each core to determine: (1) the temporal and spatial accumulation and melt refreeze patterns in the percolation zone of W. Greenland over the past 40 - 55 years, and (2) the impacts of changing melt and refreeze patterns on the near-surface density profile of the percolation zone. Three of the GreenTrACS firn cores re-occupy firn core sites collected in the 1970's-1990's, allowing us to more accurately quantify the evolution of the percolation zone surface melt and firn density during the most recent decades of summertime warming. This work is the basis for broader investigations into how changes in W. Greenland summertime climate are impacting the SMB of the Greenland Ice Sheet.

Anatomy of a Plate Boundary at Shallow Crustal Levels: a Composite Section from the Alpine Fault, New Zealand

NASA Astrophysics Data System (ADS)

Barth, N. C.; Toy, V. G.; Boulton, C. J.; Carpenter, B. M.

2010-12-01

New Zealand's Alpine Fault is mostly a moderately SE-dipping dextral reverse plate boundary structure, but at its southern end, strike-slip-normal motion is indicated by offset of recent surfaces, juxtaposition of sediments, and both brittle and ductile shear sense indicators. At the location of uplift polarity reversal fault rocks exhumed from both the hangingwall Pacific and footwall Australian Plates are juxtaposed, offering a remarkably complete cross section of the plate boundary at shallow crustal levels. We describe Alpine Fault damage zone and fault core structures overprinted on Pacific and Australian plate mylonites of a variety of compositions, in a fault-strike perpendicular composite section spanning the reversal in dip-slip polarity. The damage zone is asymmetric; on the Australian Plate 160m of quartzose paragneiss-derived mylonites are overprinted by brittle faults and fractures that increase in density towards the principal slip surface (PSS). This damage zone fabric consists of 1-10m-spaced, moderately to steeply-dipping, 1-20cm-thick gouge-filled faults, overprinted on and sub-parallel to a mylonitic foliation sub-parallel to the PSS. On the Pacific Plate, only 40m of the 330m section of volcaniclastic-derived mylonites have brittle damage in the form of unhealed fractures and faults, as well as a pervasive greenschist facies hydrothermal alteration absent in the footwall. These damage-related structures comprise a network of small-offset faults and fractures with increasing density and intensity towards the PSS. The active Pacific Plate fault core is composed of ~1m of cataclasite grading into folded protocataclasite that is less folded and fractured with increasing distance from the PSS. The active Australian Plate fault core is <1.5m wide and consists of 3 distinct foliated clay gouges, as well as a 4cm thick brittle ultracataclasite immediately adjacent to the active PSS. The Australian Plate foliated clay gouge contains stringers of quartz that become less continuous and more sigmoidal toward the PSS, indicating a strain gradient across the gouge zone. Gouge textures are consistent with deformation by pressure solution. Intact wafers from one of the gouges, experimentally -sheared in a biaxial configuration under true-triaxial loading at σn’= 31MPa and Pf = 10MPa, yielded a friction coefficient, μss = 0.32 and displayed velocity strengthening behavior. No significant re-strengthening was observed during hold periods of slide-hold tests. Well-cemented glacial till (~8000 years old), which caps many outcrops, is a marker that shows that the damage zone is not active in the near-surface, but most of the fault core is. The active near-surface damage zone here is <40m wide and the active fault core is <2.5m wide. Both overprint a much wider, inactive damage zone. The combination of rheologically-weak Australian Plate fault rocks with surface rupture traces indicates distinctly different coseismic and interseismic behaviors along the southern strike-slip-normal segment of the Alpine Fault.

Consolidation patterns during initiation and evolution of a plate-boundary decollement zone: Northern Barbados accretionary prism

USGS Publications Warehouse

Moore, J.C.; Klaus, A.; Bangs, N.L.; Bekins, B.; Bucker, C.J.; Bruckmann, W.; Erickson, S.N.; Hansen, O.; Horton, T.; Ireland, P.; Major, C.O.; Moore, Gregory F.; Peacock, S.; Saito, S.; Screaton, E.J.; Shimeld, J.W.; Stauffer, P.H.; Taymaz, T.; Teas, P.A.; Tokunaga, T.

1998-01-01

Borehole logs from the northern Barbados accretionary prism show that the plate-boundary decollement initiates in a low-density radiolarian claystone. With continued thrusting, the decollement zone consolidates, but in a patchy manner. The logs calibrate a three-dimensional seismic reflection image of the decollement zone and indicate which portions are of low density and enriched in fluid, and which portions have consolidated. The seismic image demonstrates that an underconsolidated patch of the decollement zone connects to a fluid-rich conduit extending down the decollement surface. Fluid migration up this conduit probably supports the open pore structure in the underconsolidated patch.

The effects of intragrain defects on the local photoresponse of polycrystalline silicon solar cells

NASA Astrophysics Data System (ADS)

Inoue, N.; Wilmsen, C. W.; Jones, K. A.

1981-02-01

Intragrain defects in Wacker cast and Monsanto zone-refined polycrystalline silicon materials were investigated using the electron-beam-induced current (EBIC) technique. The EBIC response maps were compared with etch pit, local diffusion length and local photoresponse measurements. It was determined that the Wacker polycrystalline silicon has a much lower density of defects than does the Monsanto polycrystalline silicon and that most of the defects in the Wacker material are not active recombination sites. A correlation was found between the recombination site density, as determined by EBIC, and the local diffusion length. It is shown that a large density of intragrain recombination sites greatly reduces the minority carrier diffusion length and thus can significantly reduce the photoresponse of solar cells.

Propulsive force of Paramecium as revealed by the video centrifuge microscope.

PubMed

Kuroda, K; Kamiya, N

1989-09-01

Using the video centrifuge microscope we constructed, we observed the behavior of Paramecium cells in a solution of graded densities under centrifugal acceleration. Beyond 300g, they not only gather in the zone where the density is closest to theirs, but also orient themselves with their longitudinal axis parallel to the direction of centrifugation turning their anterior ends toward either centripetal or centrifugal direction. Since all of them retain still active swimming capacity, it is possible to calculate their propulsive force from the difference in density between theirs (1.04 g cm-3) and that of the upper or lower layer which they can reach. The propulsive force of single Paramecium cells thus obtained was calculated to be about 7 x 10(-4) dyn.

Crustal structure in high deformation zones: Insights from gravimetric and magnetometric studies in the Guacha Corral shear zone (Eastern Sierras Pampeanas, Argentina)

NASA Astrophysics Data System (ADS)

Radice, Stefania; Lince Klinger, Federico; Maffini, M. Natalia; Pinotti, Lucio P.; Demartis, Manuel; D´Eramo, Fernando J.; Giménez, Mario; Coniglio, Jorge E.

2018-03-01

The Guacha Corral shear zone (GCSZ) is represented by mylonites that were developed under amphibolites facies conditions from migmatitic protoliths. In this contribution, geophysical, petrological and structural data were combined to determine the 3D geometry of the GCSZ. New gravimetric, magnetometric and structural studies, along an E-W profile, were integrated with existing magnetotelluric and seismological data from a representative regional database of the Eastern Sierras Pampeanas. The zonation of different fabrics across the GCSZ suggests that the pre-existing heterogeneities of the protoliths played a key role in governing the degree of metamorphism of different regions. The low gravity anomalies observed in the GCSZ suggest a transitional boundary zone between the migmatitic and mylonitic domains, where highly deformed shear bands are interspersed with undeformed rocks, presenting gradual contacts. The mylonites in this shear zone show a considerably reduced density when compared to the migmatite protoliths. The density of the rocks gradually increases with depth until it reaches that of the protolith. These changes in the gravity values in response to density changes allowed us to infer a listric geometry at depth of the GCSZ. Low gravity anomalies in the profiles, in regions where high density rocks (migmatites) outcrop at the surface, modeled as buried granitic plutons.

Seasonal variability of rocky reef fish assemblages: Detecting functional and structural changes due to fishing effects

NASA Astrophysics Data System (ADS)

Henriques, Sofia; Pais, Miguel Pessanha; Costa, Maria José; Cabral, Henrique Nogueira

2013-05-01

The present study analyzed the effects of seasonal variation on the stability of fish-based metrics and their capability to detect changes in fish assemblages, which is yet poorly understood despite the general idea that guilds are more resilient to natural variability than species abundances. Three zones subject to different levels of fishing pressure inside the Arrábida Marine Protected Area (MPA) were sampled seasonally. The results showed differences between warm (summer and autumn) and cold (winter and spring) seasons, with the autumn clearly standing out. In general, the values of the metrics density of juveniles, density of invertebrate feeders and density of omnivores increased in warm seasons, which can be attributed to differences in recruitment patterns, spawning migrations and feeding activity among seasons. The density of generalist/opportunistic individuals was sensitive to the effect of fishing, with higher values at zones with the lowest level of protection, while the density of individuals with high commercial value only responded to fishing in the autumn, due to a cumulative result of both juveniles and adults abundances during this season. Overall, this study showed that seasonal variability affects structural and functional features of the fish assemblage and that might influence the detection of changes as a result of anthropogenic pressures. The choice of a specific season, during warm sea conditions after the spawning period (July-October), seems to be more adequate to assess changes on rocky-reef fish assemblages.

Tectonic Divisions Based on Gravity Data and Earthquake Distribution Characteristics in the North South Seismic Belt, China

NASA Astrophysics Data System (ADS)

Tian, T.; Zhang, J.; Jiang, W.

2017-12-01

The North South Seismic Belt is located in the middle of China, and this seismic belt can be divided into 12 tectonic zones, including the South West Yunnan (I), the Sichuan Yunnan (II), the Qiang Tang (III), the Bayan Har (IV), the East Kunlun Qaidam (V), the Qi Lian Mountain (VI), the Tarim(VII), the East Alashan (VIII), the East Sichuan (IX), the Ordos(X), the Middle Yangtze River (XI) and the Edge of Qinghai Tibet Block (XII) zone. Based on the Bouguer Gravity data calculated from the EGM2008 model, the Euler deconvolution was used to obtain the edge of tectonic zone to amend the traditional tectonic divisions. In every tectonic zone and the whole research area, the logarithm of the total energy of seismic was calculated. The Time Series Analysis (TSA) for all tectonic zones and the whole area were progressed in R, and 12 equal divisions were made (A1-3, B1-3, C1-3, D1-3) by latitude and longitude as a control group. A simple linear trend fitting of time was used, and the QQ figure was used to show the residual distribution features. Among the zones according to Gravity anomalies, I, II and XII show similar statistical characteristic, with no earthquake free year (on which year there was no earthquake in the zone), and it shows that the more seismic activity area is more similar in statistical characteristic as the large area, no matter how large the zone is or how many earthquakes are in the zone. Zone IV, V, IX, III, VII and VIII show one or several seismic free year during 1970s (IV, V and IX) and 1980s (III, VII and VIII), which may implicate the earthquake activity were low decades ago or the earthquake catalogue were not complete in these zones, or both. Zone VI, X and XI show many earthquake free years even in this decade, which means in these zones the earthquake activity were very low even if the catalogue were not complete. In the control group, the earthquake free year zone appeared random and independent of the seismic density, and in all equal divided zones with seismic free years, the seismic free years all appeared in 1970s, which only related to the incompleteness of the earthquake catalogue in the west area of China. In conclusion, the tectonic divisions based on Gravity anomalies can provide a more efficient way to add space factor in the time series analysis with specific tectonic implications.

The effect of adipose derived stromal vascular fraction on stasis zone in an experimental burn model.

PubMed

Eyuboglu, Atilla Adnan; Uysal, Cagri A; Ozgun, Gonca; Coskun, Erhan; Markal Ertas, Nilgun; Haberal, Mehmet

2018-03-01

Stasis zone is the surrounding area of the coagulation zone which is an important part determining the extent of the necrosis in burn patients. In our study we aim to salvage the stasis zone by injecting adipose derived stromal vascular fraction (ADSVF). Thermal injury was applied on dorsum of Sprague-Dawley rats (n=20) by the "comb burn" model as described previously. When the burn injury was established on Sprague-Dawley rats (30min); rat dorsum was separated into 2 equal parts consisting of 4 burn zones (3 stasis zone) on each pair. ADSVF cells harvested from inguinal fat pads of Sprague-Dawley rats (n=5) were injected on the right side while same amount of phosphate buffered saline (PBS) injected on the left side of the same animal. One week later, average vital tissue on the statis zone was determined by macroscopy, angiography and microscopy. Vascular density, inflammatory cell density, gradient of fibrosis and epithelial thickness were determined via immunohistochemical assay. Macroscopic stasis zone tissue viability (32±3.28%, 57±4.28%) (p<0.01), average number of vessels (10.28±1.28, 19.43±1.72) (p<0.01), capillary count (15.67±1.97, 25.35±2.15) (p<0.01) vascular density (1.55±0.38, 2.14±0.45) (p<0.01) epithelial thickness (0.014±0.009mm, 0.024±0.0011mm) were higher on ADSVF side. Fibrosis gradient (1.87±0.51, 1.50±0.43) (p<0.01) and inflammatory cell density (1.33±0.40, 1.20±0.32) (p<0.01) were higher on the PBS side. Macroscopic and microscopic findings determined that ADSVF has a statistically significant benefit for salvaging stasis zone on acute burn injuries. Copyright © 2017 Elsevier Ltd and ISBI. All rights reserved.

Large-scale magmatic layering in the Main Zone of the Bushveld Complex and episodic downward magma infiltration

NASA Astrophysics Data System (ADS)

Hayes, Ben; Ashwal, Lewis D.; Webb, Susan J.; Bybee, Grant M.

2017-03-01

The Bellevue drillcore intersects 3 km of Main and Upper Zone cumulates in the Northern Limb of the Bushveld Complex. Main Zone cumulates are predominately gabbronorites, with localized layers of pyroxenite and anorthosite. Some previous workers, using bulk rock major, trace and isotopic compositions, have suggested that the Main Zone crystallized predominantly from a single pulse of magma. However, density measurements throughout the Bellevue drillcore reveal intervals that show up-section increases in bulk rock density, which are difficult to explain by crystallization from a single batch of magma. Wavelet analysis of the density data suggests that these intervals occur on length-scales of 40 to 170 m, thus defining a scale of layering not previously described in the Bushveld Complex. Upward increases in density in the Main Zone correspond to upward increases in modal pyroxene, producing intervals that grade from a basal anorthosite (with 5% pyroxene) to gabbronorite (with 30-40% pyroxene). We examined the textures and mineral compositions of a 40 m thick interval showing upwardly increasing density to establish how this type of layering formed. Plagioclase generally forms euhedral laths, while orthopyroxene is interstitial in texture and commonly envelops finer-grained and embayed plagioclase grains. Minor interstitial clinopyroxene was the final phase to crystallize from the magma. Plagioclase compositions show negligible change up-section (average An62), with local reverse zoning at the rims of cumulus laths (average increase of 2 mol%). In contrast, interstitial orthopyroxene compositions become more primitive up-section, from Mg# 57 to Mg# 63. Clinopyroxene similarly shows an up-section increase in Mg#. Pyroxene compositions record the primary magmatic signature of the melt at the time of crystallization and are not an artefact of the trapped liquid shift effect. Combined, the textures and decoupled mineral compositions indicate that the upward density increase is produced by the downward infiltration of noritic magma into a previously emplaced plagioclase-rich crystal mush. Fresh noritic magma soaked down into the crystallizing anorthositic mush, partially dissolving plagioclase laths and assimilating Fe-enriched pore melt. The presence of multiple cycles showing upward increases in density in the Bellevue drillcore suggests that downward magma infiltration occurred episodically during crystallization of the Main Zone.

Macroinvertebrate assemblage recovery following a catastrophic flood and debris flows in an Appalachian mountain stream

USGS Publications Warehouse

Snyder, C.D.; Johnson, Z.B.

2006-01-01

In June 1995, heavy rains caused severe flooding and massive debris flows on the Staunton River, a 3rd-order stream in the Blue Ridge Mountains (Virginia, USA). Scouring caused the loss of the riparian zone and repositioned the stream channel of the lower 2.1 km of the stream. Between 1998 and 2001, we conducted seasonal macroinvertebrate surveys at sites on the Staunton River and on White Oak Canyon Run, a reference stream of similar size and geology that was relatively unaffected by the flood. Our study was designed to determine the extent to which flood-induced changes to the stream channel and riparian habitats caused long-term changes to macroinvertebrate community structure and composition. Sites within the impacted zone of the Staunton River supported diverse stable benthic macroinvertebrate assemblages 3 y after the flood despite dramatic and persistent changes in environmental factors known to be important controls on stream ecosystem function. However, significant differences in total macroinvertebrate density and trophic structure could be attributed to the flood. In autumn, densities of most feeding guilds, including shredders, were higher at impacted-zone sites than at all other sites, suggesting higher overall productivity in the impacted zone. Higher shredder density in the impacted zone was surprising in light of expected decreases in leaf-litter inputs because of removal of riparian forests. In contrast, in spring, we observed density differences in only one feeding guild, scrapers, which showed higher densities at impacted-zone sites than at all other sites. This result conformed to a priori expectations that reduced shading in the impacted zone would lead to increased light and higher instream primary production. We attribute the seasonal differences in trophic structure to the effects of increased temperatures on food quality and to the relationship between the timing of our sampling and the emergence patterns of important taxa. ?? 2006 by The North American Benthological Society.

Mechanical interaction between volcanic systems in Libya

NASA Astrophysics Data System (ADS)

Elshaafi, Abdelsalam; Gudmundsson, Agust

2018-01-01

The spatial distributions of monogenetic volcanoes, primarily volcanic craters, within the four principal volcanic provinces of Libya are examined and presented on a volcano-density map. Six main volcanic clusters have been identified, referred to as volcanic systems. Remarkably, the Al Haruj (AHVP) and Nuqay (NVP) volcanic provinces have double-peak volcano-density distributions, while the Gharyan (GVP) and As Sawda (SVP) volcanic provinces have single-peak volcano-density distributions. We interpret each volcano-density peak as corresponding to a separate volcanic system, so that there is a total of six systems in these four provinces. There was an overlap in volcanic activity in these provinces with at least three simultaneously active. We propose that each of the 6 volcanic systems was/is supplied with magma from a large sill-like reservoir - similar in lateral dimensions to the systems/clusters themselves. Numerical results show zones of high tensile and shear stresses between the reservoirs that coincide roughly with the main swarms of extension (dykes and volcanic fissures) and shear (faults) fractures in the areas. The most recent volcanic eruptions in Libya fall within the modelled high-stress concentration zones, primarily eruptions in the volcano Waw an Namus and the Holocene Al Mashaqaq lava flow. There are no known eruptions in Libya in historical time, but some or all the volcanic systems may have had one or more arrested historical dyke injections. In particular, part of the recurrent seismic events in the Hun Graben in the northwest Libya may be related to dyke propagation and arrest. If some of the inferred magma reservoirs are still fluid, as is likely, they pose earthquake and volcanic hazards to parts of Libya, particularly to the city of Gharyan and Zallah town, as well as to many oil-field operations.

Photosynthate partitioning in basal zones of tall fescue leaf blades. [Festuca arundinacea Schreb

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allard, G.; Nelson, C.J.

Elongating grass leaves have successive zones of cell division, cell elongation, and cell maturation in the basal portion of the blade and are a strong sink for photosynthate. Our objective was to determine dry matter (DM) deposition and partitioning in basal zones of elongating tall fescue (Festuca arundinacea Schreb.) leaf blades. Vegetative tall fescue plants were grown in continuous light (350 micromoles per square meter per second photosynthetic photon flux density) to obtain a constant spatial distribution of elongation growth with time. Content and net deposition rates of water-soluble carbohydrates (WSC) and DM along elongating leaf blades were determined. Thesemore » data were compared with accumulation of {sup 14}C in the basal zones following leaf-labeling with {sup 14}CO{sub 2}. Net deposition of DM was highest in the active cell elongation zone, due mainly to deposition of WSC. The maturation zone, just distal to the elongation zone, accounted for 22% of total net deposition of DM in elongating leaves. However, the spatial profile of {sup 14}C accumulation suggested that the elongation zone and the maturation zone were sinks of equal strength. WSC-free DM accounted for 55% of the total net DM deposition in elongating leaf blades, but only 10% of incoming {sup 14}C-photosynthate accumulated in the water-insoluble fraction (WIF {approximately} WSC-free DM) after 2 hours. In the maturation zone, more WSC was used for synthesis of WSC-free DM than was imported as recent photosynthate.« less

Response of Chondrocytes to Local Mechanical Injury in an Ex Vivo Model

PubMed Central

Lyman, Jeffrey R.; Chappell, Jonathan D.; Kelley, Scott S.; Lee, Greta M.

2012-01-01

Background: Our goal was to set up an ex vivo culture system to assess whether cartilage wounding (partial-thickness defects) can induce morphological changes in neighboring chondrocytes and whether these cells can translocate to the surface of the defect. Methods: Two-millimeter partial-depth defects were created in human osteochondral explants followed by culture for up to 4 weeks. Frozen sections of defects and defect-free regions were labeled using immunofluorescence for a plasma membrane protein, CD44, and actin with TRITC-phalloidin. Viable nuclei were detected with Hoechst 33342. Differential interference contrast (DIC), confocal, and transmission electron microscopy (TEM) were used to examine process extension. Results: Significant changes in cell morphology occurred in response to wounding in the superficial and deep cartilage zones. These included cell flattening, polarization of the actin cytoskeleton, extension of pseudopods projecting towards the edge of the defect, and interactions of these filopodia with collagen fibers. Cell density decreased progressively in the 300-µm zone adjacent to the defect to an average of approximately 25% to 35% after 3 weeks. Concomitant increases in cell density in the defect margin were observed. By contrast, minimal changes were seen in the middle cartilage zone. Conclusions: These novel observations strongly suggest active cartilage cell responses and movements in response to wounding. It is proposed that cartilage cells use contact guidance on fibrillated collagen to move into and populate defect areas in the superficial and deep zones. PMID:26069619

Species composition of Bromeliaceae and their distribution at the Massambaba restinga in Arraial do Cabo, Rio de Janeiro, Brazil.

PubMed

Rocha-Pessôa, T C; Nunes-Freitas, A F; Cogliatti-Carvalho, L; Rocha, C F D

2008-05-01

We studied some ecological parameters such as richness, abundance, density, biomass and variation in species composition in four vegetation zones and in a zone with anthropic disturbance in the Massambaba Restinga in Arraial do Cabo, Rio de Janeiro State. We sampled 100 plots of 100 m(2) (10 x 10 m) recording the bromeliad species and their abundance. We found a total of seven bromeliad species, with Vriesea neoglutinosa (5647 ramets) and Tillandsia stricta (1277 ramets) being the most abundant. The vegetation zone called Clusia shrubs had the highest richness (S = 5) and density (6360 ramets.ha(-1)) of bromeliads. The differences found in abundance and variation in species composition among vegetation zones seems to be related to the vegetation structure of each zone.

Fracture zone drilling through Atotsugawa fault in central Japan - geological and geophysical structure -

NASA Astrophysics Data System (ADS)

Omura, K.; Yamashita, F.; Yamada, R.; Matsuda, T.; Fukuyama, E.; Kubo, A.; Takai, K.; Ikeda, R.; Mizuochi, Y.

2004-12-01

Drilling is an effective method to investigate the structure and physical state in and around the active fault zone, such as, stress and strength distribution, geological structure and materials properties. In particular, the structure in the fault zone is important to understand where and how the stress accumulates during the earthquake cycle. In previous studies, we did integrate investigation on active faults in central Japan by drilling and geophysical prospecting. Those faults are estimated to be at different stage in the earthquake cycle, i.e., Nojima fault which appeared on the surface by the 1995 Great Kobe earthquake (M=7.2), the Neodani fault which appeared by the 1891 Nobi earth-quake (M=8.0), the Atera fault, of which some parts have seemed to be dislocated by the 1586 Tensyo earthquake (M=7.9), and Gofukuji Fault that is considered to have activated about 1200 years ago. Each faults showed characteristic features of fracture zone structure according to their geological and geophysical situations. In a present study, we did core recovery and down hole measurements at the Atotsugawa fault, central Japan, that is considered to have activated at 1858 Hida earthquake (M=7.0). The Atotsugawa fault is characterized by active seismicity along the fault. But, at the same time, the shallow region in the central segment of the fault seems to have low seismicity. The high seismicity segment and low seismicity segments may have different mechanical, physical and material properties. A 350m depth borehole was drilled vertically beside the surface trace of the fault in the low seismicity segment. Recovered cores were overall heavily fractured and altered rocks. In the cores, we observed many shear planes holding fault gouge. Logging data showed that the apparent resistance was about 100 - 600 ohm-m, density was about 2.0 - 2.5g/cm3, P wave velocity was approximately 3.0 - 4.0 km/sec, neutron porosity was 20 - 40 %. Results of physical logging show features of fault fracture zone that were the same as the fault fracture zones of other active faults that we have drilled previously. By the BHTV logging, we detected many fractures of which the strikes are not only parallel to the fault trace bur also oblique to the fault trace. The observations of cores and logging data indicate that the borehole passed in the fracture zone down to the bottom, and that the fracture zone has complicate internal structure including foliation not parallel to the fault trace. The core samples are significant for further investigation on material properties in the fracture zone. And we need data of geophysical prospecting to infer the deeper structure of the fracture zone.

Compression and release dynamics of an active matter system of Euglena gracilis

NASA Astrophysics Data System (ADS)

Lam, Amy; Tsang, Alan C. H.; Ouellette, Nicholas; Riedel-Kruse, Ingmar

Active matter, defined as ensembles of self-propelled particles, encompasses a large variety of systems at all scales, from nanoparticles to bird flocks. Though various models and simulations have been created to describe the dynamics of these systems, experimental verification has been difficult to obtain. This is frequently due to the complex interaction rules which govern the particle behavior, in turn making systematic varying of parameters impossible. Here, we propose a model for predicting the system evolution of compression and release of an active system based on experiments and simulations. In particular, we consider ensembles of the unicellular, photo-responsive algae, Euglena gracilis, under light stimulation. By varying the spatiotemporal light patterns, we are able to finely adjust cell densities and achieve arbitrary non-homogeneous distributions, including compression into high-density aggregates of varying geometries. We observe the formation of depletion zones after the release of the confining stimulus and investigate the effects of the density distribution and particle rotational noise on the depletion. These results provide implications for defining state parameters which determine system evolution.

Quantitative analysis of the impacts of terrestrial environmental factors on precipitation variation over the Beibu Gulf Economic Zone in Coastal Southwest China.

PubMed

Zhao, Yinjun; Deng, Qiyu; Lin, Qing; Cai, Chunting

2017-03-15

Taking the Guangxi Beibu Gulf Economic Zone as the study area, this paper utilizes the geographical detector model to quantify the feedback effects from the terrestrial environment on precipitation variation from 1985 to 2010 with a comprehensive consideration of natural factors (forest coverage rate, vegetation type, terrain, terrestrial ecosystem types, land use and land cover change) and social factors (population density, farmland rate, GDP and urbanization rate). First, we found that the precipitation trend rate in the Beibu Gulf Economic Zone is between -47 and 96 mm/10a. Second, forest coverage rate change (FCRC), urbanization rate change (URC), GDP change (GDPC) and population density change (PDC) have a larger contribution to precipitation change through land-surface feedback, which makes them the leading factors. Third, the human element is found to primarily account for the precipitation changes in this region, as humans are the active media linking and enhancing these impact factors. Finally, it can be concluded that the interaction of impact factor pairs has a significant effect compared to the corresponding single factor on precipitation changes. The geographical detector model offers an analytical framework to reveal the terrestrial factors affecting the precipitation change, which gives direction for future work on regional climate modeling and analyses.

Quantitative analysis of the impacts of terrestrial environmental factors on precipitation variation over the Beibu Gulf Economic Zone in Coastal Southwest China

NASA Astrophysics Data System (ADS)

Zhao, Yinjun; Deng, Qiyu; Lin, Qing; Cai, Chunting

2017-03-01

Taking the Guangxi Beibu Gulf Economic Zone as the study area, this paper utilizes the geographical detector model to quantify the feedback effects from the terrestrial environment on precipitation variation from 1985 to 2010 with a comprehensive consideration of natural factors (forest coverage rate, vegetation type, terrain, terrestrial ecosystem types, land use and land cover change) and social factors (population density, farmland rate, GDP and urbanization rate). First, we found that the precipitation trend rate in the Beibu Gulf Economic Zone is between -47 and 96 mm/10a. Second, forest coverage rate change (FCRC), urbanization rate change (URC), GDP change (GDPC) and population density change (PDC) have a larger contribution to precipitation change through land-surface feedback, which makes them the leading factors. Third, the human element is found to primarily account for the precipitation changes in this region, as humans are the active media linking and enhancing these impact factors. Finally, it can be concluded that the interaction of impact factor pairs has a significant effect compared to the corresponding single factor on precipitation changes. The geographical detector model offers an analytical framework to reveal the terrestrial factors affecting the precipitation change, which gives direction for future work on regional climate modeling and analyses.

Analysis of the Corrosion Behavior of an A-TIG Welded SS 409 Weld Fusion Zone

NASA Astrophysics Data System (ADS)

Vidyarthy, R. S.; Dwivedi, D. K.

2017-11-01

AISI 409 (SS 409) ferritic stainless steel is generally used as the thick gauge section in freight train wagons, in ocean containers, and in sugar refinery equipment. Activating the flux tungsten inert gas (A-TIG) welding process can reduce the welding cost during fabrication of thick sections. However, corrosion behavior of the A-TIG weld fusion zone is a prime concern for this type of steel. In the present work, the effect of the A-TIG welding process parameters on the corrosion behavior of a weld fusion zone made of 8-mm-thick AISI 409 ferritic stainless-steel plate has been analyzed. Potentiodynamic polarization tests were performed to evaluate the corrosion behavior. The maximum corrosion potential ( E corr) was shown by the weld made using a welding current of 215 A, a welding speed of 95 mm/min, and a flux coating density of 0.81 mg/cm2. The minimum E corr was observed in the weld made using a welding current of 190 A, a welding speed of 120 mm/min, and a flux coating density of 1.40 mg/cm2. The current study also presents the inclusive microstructure-corrosion property relationships using the collective techniques of scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray diffraction.

Subsurface structures of the active reverse fault zones in Japan inferred from gravity anomalies.

NASA Astrophysics Data System (ADS)

Matsumoto, N.; Sawada, A.; Hiramatsu, Y.; Okada, S.; Tanaka, T.; Honda, R.

2016-12-01

The object of our study is to examine subsurface features such as continuity, segmentation and faulting type, of the active reverse fault zones. We use the gravity data published by the Gravity Research Group in Southwest Japan (2001), the Geographical Survey Institute (2006), Yamamoto et al. (2011), Honda et al. (2012), and the Geological Survey of Japan, AIST (2013) in this study. We obtained the Bouguer anomalies through terrain corrections with 10 m DEM (Sawada et al. 2015) under the assumed density of 2670 kg/m3, a band-pass filtering, and removal of linear trend. Several derivatives and structural parameters calculated from a gravity gradient tensor are applied to highlight the features, such as a first horizontal derivatives (HD), a first vertical derivatives (VD), a normalized total horizontal derivative (TDX), a dip angle (β), and a dimensionality index (Di). We analyzed 43 reverse fault zones in northeast Japan and the northern part of southwest Japan among major active fault zones selected by Headquarters for Earthquake Research Promotion. As the results, the subsurface structural boundaries clearly appear along the faults at 21 faults zones. The weak correlations appear at 13 fault zones, and no correlations are recognized at 9 fault zones. For example, in the Itoigawa-Shizuoka tectonic line, the subsurface structure boundary seems to extend further north than the surface trace. Also, a left stepping structure of the fault around Hakuba is more clearly observed with HD. The subsurface structures, which detected as the higher values of HD, are distributed on the east side of the surface rupture in the north segments and on the west side in the south segments, indicating a change of the dip direction, the east dipping to the west dipping, from north to south. In the Yokote basin fault zone, the subsurface structural boundary are clearly detected with HD, VD and TDX along the fault zone in the north segment, but less clearly in the south segment. Also, Di implies the existence of 3D-like structure with E-W trend around the segment boundary. The distribution of dip angle β along the fault zone implies a reverse faulting, corresponding to the faulting type of this fault zone reported by previous studies.

Changes in Spatial Patterns of Caragana stenophylla along a Climatic Drought Gradient on the Inner Mongolian Plateau

PubMed Central

Xie, Li-Na; Guo, Hong-Yu; Gabler, Christopher A.; Li, Qing-Fang; Ma, Cheng-Cang

2015-01-01

Few studies have investigated the influence of water availability on plant population spatial patterns. We studied changes in the spatial patterns of Caragana stenophylla along a climatic drought gradient within the Inner Mongolian Plateau, China. We examined spatial patterns, seed density, “nurse effects” of shrubs on seedlings, transpiration rates and water use efficiency (WUE) of C. stenophylla across semi-arid, arid, and intensively arid zones. Our results showed that patches of C. stenophylla populations shifted from a random to a clumped spatial pattern towards drier environments. Seed density and seedling survival rate of C. stenophylla decreased from the semi-arid zone to the intensively arid zone. Across the three zones, there were more C. stenophylla seeds and seedlings underneath shrub canopies than outside shrub canopies; and in the intensively arid zone, there were almost no seeds or seedlings outside shrub canopies. Transpiration rates of outer-canopy leaves and WUE of both outer-canopy and inner-canopy leaves increased from the semi-arid zone to the intensively arid zone. In the intensively arid zone, transpiration rates and WUE of inner-canopy leaves were significantly lower and higher, respectively, than those of outer-canopy leaves. We conclude that, as drought stress increased, seed density decreased, seed proportions inside shrubs increased, and “nurse effects” of shrubs on seedlings became more important. These factors, combined with water-saving characteristics associated with clumped spatial patterns, are likely driving the changes in C. stenophylla spatial patterns. PMID:25785848

Density of basalt core from Hilo drill hole, Hawaii

USGS Publications Warehouse

Moore, J.G.

2001-01-01

Density measurements of 1600 samples of core from 889 to 3097 m depth below sea level in the Hawaii Scientific Drilling Program hole near Hilo, Hawaii show marked differences between the basaltic rock types and help define stratigraphy in the hole. Water-saturated densities of subaerial lava flows (occurring above 1079 m depth) have the broadest range because of the large density variation within a single lava flow. Water-saturated densities commonly range from 2.0 to 3.0 with an average of 2.55 ?? 0.24 g/cc. Dikes and sills range from 2.8 to 3.1 g/cc). Densities of hyaloclastite commonly range from 2.3 to 2.7, with an overall average of about 2.5 g/cc. The low-density of most hyaloclastite is due primarily to palagonitization of abundant glass and presence of secondary minerals in the interstices between fragments. Four principal zones of pillow lava, separated by hyaloclastite, occur in the drill core. The shallowest (1983-2136 m) is paradoxically the densest, averaging 3.01 ?? 0.10 g/cc. The second (2234-2470 m) is decidedly the lightest, averaging 2.67 ?? 0.13 g/cc. The third (2640-2790 m) and fourth (2918-bottom at 3097 m) are high, averaging 2.89 ?? 0.17 and 2.97 ?? 0.08 g/cc, respectively. The first pillow zone includes degassed pillows i.e. lava erupted on land that flowed into the sea. These pillows are poor in vesicles, because the subaerial, one-atmosphere vesicles were compressed when the flow descended to deeper water and higher pressure. The second (low-density, non-degassed) pillow zone is the most vesicle-rich, apparently because it was erupted subaqueously at a shallow depth. The higher densities of the third and fourth zones result from a low vesicularity of only a few percent and an olivine content averaging more than 5% for the third zone and about 10% for the fourth zone. The uppermost hyaloclastite extending about 400 m below the bottom of the subaerial basalt is poorly cemented and absorbs up to 6 wt% of water when immersed. Progressing downward the hyaloclastite absorbs less water and becomes better cemented. This change is apparently due to palagonitization of glass and addition of secondary minerals in the deeper older hyaloclastite, a process favored by the increase of temperature with depth. The cementation is largely complete at 1800 m depth where the temperature attains about 20??C. The zone of freshest, uncemented hyaloclastite represents the weakest rock in the drill hole and is a likely level for tectonic or landslide disruption. ?? 2001 Published by Elsevier Science B.V.

Carbon isotopic data from test hole USW UZ-1, Yucca Mountain, Nevada

USGS Publications Warehouse

Yang, In C.; Peters, C.A.; Thorstenson, D.C.

1993-01-01

Rock-CO2-gas analyses in test hole USW UZ-1 at Yucca Mountain indicate that gas movement in the unsaturated zone is likely through a dry-fracture system with little porewater or caliche-calcite interaction. This is because near-surface ??13C values are of biogenic origin and have changed little throughout the total depth. Post-bomb 14C activity is observed to the depth of about 12 m. An abrupt change in plotted 14C/depth slope is seen at 61 m. The less steep upper segment corresponds to the zone with greater porosity and moisture content, and consequently more tortuosity, with an estimated traveltime of 1.27 cm/yr; the steeper sloped zone corresponding to the lower segment has smaller porosity and moisture content but larger fracture density for gas transport, with an estimated traveltime of 3.26 cm/yr.

3-D density modeling of Mt. Paekdu (N Korea/China) stratovolcano and its evolution by a combination of EGM2008/terrestrial gravity field

NASA Astrophysics Data System (ADS)

Götze, Hans-Jürgen; Choi, Sungchan

2015-04-01

We combined the global gravity dataset EGM2008 and a local terrestrial gravity data survey to conduct constrained 3-D crustal density modeling of a strato-volcanic complex and the surrounding area located close to the border of North Korea and China. The independent geophysical (seismic, seismology, geochemistry) and petrological constraints will be presented together with the preprocessing of data base by curvature analysis and Euler deconvolution. The multiple data base is used to assist a general interpretation of the investigated area, and the 3D density model (modelled by the in-house IGMAS+ software). Mt. Paekdu is characterized by a low of Bouguer anomaly of some -110 × 10-5 m/s2, which is caused by the combined gravity effects of (1) Moho depth of about 40 km, (2) a zone with both lower P-wave velocity and density than the surrounding, (3) low density volcanic rocks at the surface, and (4) the presence of a magma chamber that has not previously been identified. The terrestrial gravity field measured along the seismic profile shows a remarkable anomaly descending from the southern- to the northern flank of the Mt. Paekdu volcano, which should be a typical anomaly pattern generally observed over the active volcanic area in the world (e.g. the Yellow Stone volcano). The trend is interpreted to be caused by a prominent density difference between a serious of high density mid crustal sill beneath the southern flank and a predicted partial melted zone locating in the northern flank. With the help of several geoscientific observations (seismic, electromagnetic, gravity and geochemistry) and the 3D density model we conclude that a high density sill was formed in Pliocene and early Pleistocene after pre-shield plateau-forming eruption. Since the Pliocene, volcanic activity in the Mt. Paekdu region might be migrated from the southeastern of North Korea to the northwest, following the path of NW-SE-trending faults. Recently observed seismic tremors can be explained by the vertical movement of the partial melted magma chamber beneath the northern part of the Mt. Baekdu volcanic area, which is confirmed by vertical stress change calculation.

3-D Density Modeling of the Combined EGM2008/Terrestrial Gravity Field over the Mt. Paekdu (N Korea/China) Stratovolcano and Its Evolution

NASA Astrophysics Data System (ADS)

Goetze, H. J.; Choi, S.

2014-12-01

In the presentation we get use of the global gravity dataset EGM2008 and a local terrestrial gravity data survey for a constrained 3-D crustal density modeling of a stratovolcano and its surrounding area located close to the border of North Korea and China. The independent geophysical (seismic, seismology, geochemistry) and petrological constraints will be presented together with the preprocessing of data base by curvature analysis and Euler deconvolution. The multiple data base is used to assist a general interpretation of the investigated area in time, and the 3D density model (modelled by the inhouse IGMAS+ software). Mt. Paekdu is characterized by a low of Bouguer anomaly of some -110 ´ 10-5 m/s2, which is caused by the combined gravity effects of (1) Moho depth of about 40 km, (2) a zone with both lower P-wave velocity and density than the surrounding, (3) low density volcanic rocks at the surface, and (4) the presence of a magma chamber that has not previously been identified. The terrestrial gravity field measured along the seismic profile shows a remarkable anomaly descending from the southern- to the northern flank of the Mt. Paekdu volcano, which should be a typical anomaly pattern generally obsered over the active volcanic area in the world (e.g. the Yellow Stone volcano). The trend is interpreted to be caused by a prominent density difference between a serious of high density mid crustal sill beneath the southern flank and a predicted partial melted zone locating in the northern flank. With the help of several geoscientific observations (seismic, electromagnetic, gravity and geochemistry) and the 3D density model we conclude that a high density sill was formed in Pliocene and early Pleistocene after pre-shield plateau-forming eruption. Since the Pliocene, volcanic activity in the Mt. Paekdu region might be migrated from the southeastern of North Korea to the northwest, following the path of NW-SE-trending faults. Recently observed seismic tremors can be explained by the vertical movement of the partial melted magma chamber beneath the northern part of the Mt. Baekdu volcanic area, which is confirmed by vertical stress calculation.

On-chip very low junction temperature GaN-based light emitting diodes by selective ion implantation

NASA Astrophysics Data System (ADS)

Cheng, Yun-Wei; Chen, Hung-Hsien; Ke, Min-Yung; Chen, Cheng-Pin; Huang, JianJang

2008-08-01

We propose an on-wafer heat relaxation technology by selectively ion-implanted in part of the p-type GaN to decrease the junction temperature in the LED structure. The Si dopant implantation energy and concentration are characterized to exhibit peak carrier density 1×1018 cm-3 at the depth of 137.6 nm after activation in nitrogen ambient at 750 °C for 30 minutes. The implantation schedule is designed to neutralize the selected region or to create a reverse p-n diode in the p-GaN layer, which acts as the cold zone for heat dissipation. The cold zone with lower effective carrier concentration and thus higher resistance is able to divert the current path. Therefore, the electrical power consumption through the cold zone was reduced, resulting in less optical power emission from the quantum well under the cold zone. Using the diode forward voltage method to extract junction temperature, when the injection current increases from 10 to 60 mA, the junction temperature of the ion-implanted LED increases from 34.3 °C to 42.3 °C, while that of the conventional one rises from 30.3 °C to 63.6 °C. At 100 mA, the output power of the ion-implanted device is 6.09 % higher than that of the conventional device. The slight increase of optical power is due to the increase of current density outside the cold zone region of the implanted device and reduced junction temperature. The result indicates that our approach improves thermal dissipation and meanwhile maintains the linearity of L-I curves.

Quantitative determination of the mineral distribution in different collagen zones of calcifying tendon using high voltage electron microscopic tomography

NASA Technical Reports Server (NTRS)

McEwen, B. F.; Song, M. J.; Landis, W. J.

1991-01-01

High voltage electron microscopic tomography was used to make the first quantitative determination of the distribution of mineral between different regions of collagen fibrils undergoing early calcification in normal leg tendons of the domestic turkey, Meleagris gallopavo. The tomographic 3-D reconstruction was computed from a tilt series of 61 different views spanning an angular range of +/- 60 degrees in 2 degrees intervals. Successive applications of an interactive computer operation were used to mask the collagen banding pattern of either hole or overlap zones into separate versions of the reconstruction. In such 3-D volumes, regions specified by the mask retained their original image density while the remaining volume was set to background levels. This approach was also applied to the mineral crystals present in the same volumes to yield versions of the 3-D reconstructions that were masked for both the crystal mass and the respective collagen zones. Density profiles from these volumes contained a distinct peak corresponding only to the crystal mass. A comparison of the integrated density of this peak from each profile established that 64% of the crystals observed were located in the collagen hole zones and 36% were found in the overlap zones. If no changes in crystal stability occur once crystals are formed, this result suggests the possibilities that nucleation of mineral is preferentially and initially associated with the hole zones, nucleation occurs more frequently in the hole zones, the rate of crystal growth is more rapid in the hole zones, or a combination of these alternatives. All lead to the conclusion that the overall accumulation of mineral mass is predominant in the collagen hole zones compared to overlap zones during early collagen fibril calcification.

Coccolithophore ecology at the HOT station ALOHA, Hawaii

NASA Astrophysics Data System (ADS)

Cortés, Mara Y.; Bollmann, Jörg; Thierstein, Hans R.

Cell densities of total coccolithophores and dominant taxa were determined in 183 samples from the upper 200 m of the water column at about monthly intervals between January 1994 and August 1996 at the HOT station ALOHA, Hawaii. High cell densities were observed twice a year, in March (up to 41×10 3 cells l -1) and in September/October (up to 52×10 3 cells l -1). In the intervening months, cell densities were extremely low (0-20×10 3 cells l -1), reflecting a strong seasonality. The main production of coccolithophores took place in the middle photic zone between 50 and 100 m water depth. In total 125 coccolithophore species were identified but only five constituted on average more than 30% of the community: Emiliania huxleyi, Umbellosphaera irregularis, U. tenuis, Florisphaera profunda and Gephyrocapsa ericsonii. The generally low, but seasonally dynamic coccolithophore cell density variability is compared with in situ measurements of environmental parameters. Correlation analyses between cell density variability of the dominant taxa and potentially controlling environmental parameters show significant correlation coefficients when the data set was separated into upper and lower photic zone. Cell densities of all dominant taxa are most highly correlated with temperature variability. U. irregularis is positively correlated in the upper photic zone, whereas E. huxleyi and G. ericsonii are negatively correlated. In the lower photic zone, F. profunda cell densities are positively correlated with light, which corresponds to the maximum bottom-up control (i.e. by physical forcing) of any species encountered. The surprisingly low correlations of cell densities with nitrate and phosphate may be caused by insufficient sampling resolution, nutrient levels close to detection limits, or both.

Noise Configuration and fault zone anisotropy investigation from Taiwan Chelungpu-fault Deep Borehole Array

NASA Astrophysics Data System (ADS)

Hung, R. J.; Ma, K. F.; Song, T. R. A.; Nishida, K.; Lin, Y. Y.

2016-12-01

The Taiwan Chelungpu-fault Drilling Project was operated to understand the fault zone characteristics associated with the 1999 Chichi earthquake. Seven Borehole Seismometers (TCDPBHS) were installed through the identified fault zone to monitor the micro-seismic activities, as well as the fault-zone seismic structure properties. To understand the fault zone anisotropy and its possible temporal variations after the Chichi earthquake, we calculated cross-correlations of the noise at different stations to obtain cross correlation functions (CCFs) of the ambient noise field between every pair of the stations. The result shows that TCDP well site suffers from complex wavefield, and phase traveltime from CCF can't provide explicit result to determine the dominated wavefield. We first analyze the power density spectra and probability density functions of this array. We observe that the spectra show diurnal variation in the frequency band 1-25 Hz, suggesting human-generated sources are dominated in this frequency band. Then, we focus on the particle motion analysis at each CCF. We assume one component at a station plays as a visual source and compute the CCF tensor in other station components. The particle motion traces show high linearity which indicate that the dominated wavefield in our study area is body wave signals with the azimuth approximate to 60° from north. We also analyze the Fourier spectral amplitudes by rotating every 5 degrees in time domain to search for the maximum background energy distribution. The result shows that the spectral amplitudes are stronger at NE-SW direction, with shallow incident angles which are comparable with the CCF particle motion measurement. In order to obtain higher resolution about the dominated wavefield in our study area, we also used beamforming from surface station array to validate our results from CCF analysis. In addition to the CCF analysis to provide the noise configuration at the TCDPBHS site for further analysis on fault zone anisotropy using ambient noise, we also analyze fault zone anisotropy using the events data recorded by TCDPBHS. The identified event clusters through the borehole data enhance the consistency in results to give hints on fault zone anisotropy.

Vectorial structures of linear-polarized Butterfly-Gauss vortex beams in the far zone

NASA Astrophysics Data System (ADS)

Cheng, Ke; Zhou, Yan; Lu, Gang; Yao, Na; Zhong, Xianqiong

2018-05-01

By introducing the Butterfly catastrophe to optics, the far-zone vectorial structures of Butterfly-Gauss beam with vortex and non-vortex are studied using the angular spectrum representation and stationary phase method. The influence of topological charge, linear-polarized angle, off-axis distance and scaling length on the far-zone vectorial structures, especially in the Poynting vector and angular momentum density of the corresponding beam is emphasized. The results show that the embedded optical vortex at source plane lead to special dark zones in the far zone, where the number of dark zone equals the absolute value of topological charge of optical vortex. Furthermore, the symmetry and direction of the special dark zones can be controlled by off-axis distance and scaling length, respectively. The linear-polarized angle adjusts only the Poynting vectors of TE and TM terms, but it does not affect those of whole beam. Finally, the vectorial expressions also indicate that the total angular momentum density is certainly zero owing to the far-zone stable structures rather than rotation behaviors.

Nocturnal and daytime stomatal conductance respond to root-zone temperature in ‘Shiraz’ grapevines

PubMed Central

Rogiers, Suzy Y.; Clarke, Simon J.

2013-01-01

Background and Aims Daytime root-zone temperature may be a significant factor regulating water flux through plants. Water flux can also occur during the night but nocturnal stomatal response to environmental drivers such as root-zone temperature remains largely unknown. Methods Here nocturnal and daytime leaf gas exchange was quantified in ‘Shiraz’ grapevines (Vitis vinifera) exposed to three root-zone temperatures from budburst to fruit-set, for a total of 8 weeks in spring. Key Results Despite lower stomatal density, night-time stomatal conductance and transpiration rates were greater for plants grown in warm root-zones. Elevated root-zone temperature resulted in higher daytime stomatal conductance, transpiration and net assimilation rates across a range of leaf-to-air vapour pressure deficits, air temperatures and light levels. Intrinsic water-use efficiency was, however, lowest in those plants with warm root-zones. CO2 response curves of foliar gas exchange indicated that the maximum rate of electron transport and the maximum rate of Rubisco activity did not differ between the root-zone treatments, and therefore it was likely that the lower photosynthesis in cool root-zones was predominantly the result of a stomatal limitation. One week after discontinuation of the temperature treatments, gas exchange was similar between the plants, indicating a reversible physiological response to soil temperature. Conclusions In this anisohydric grapevine variety both night-time and daytime stomatal conductance were responsive to root-zone temperature. Because nocturnal transpiration has implications for overall plant water status, predictive climate change models using stomatal conductance will need to factor in this root-zone variable. PMID:23293018

Nocturnal and daytime stomatal conductance respond to root-zone temperature in 'Shiraz' grapevines.

PubMed

Rogiers, Suzy Y; Clarke, Simon J

2013-03-01

Daytime root-zone temperature may be a significant factor regulating water flux through plants. Water flux can also occur during the night but nocturnal stomatal response to environmental drivers such as root-zone temperature remains largely unknown. Here nocturnal and daytime leaf gas exchange was quantified in 'Shiraz' grapevines (Vitis vinifera) exposed to three root-zone temperatures from budburst to fruit-set, for a total of 8 weeks in spring. Despite lower stomatal density, night-time stomatal conductance and transpiration rates were greater for plants grown in warm root-zones. Elevated root-zone temperature resulted in higher daytime stomatal conductance, transpiration and net assimilation rates across a range of leaf-to-air vapour pressure deficits, air temperatures and light levels. Intrinsic water-use efficiency was, however, lowest in those plants with warm root-zones. CO(2) response curves of foliar gas exchange indicated that the maximum rate of electron transport and the maximum rate of Rubisco activity did not differ between the root-zone treatments, and therefore it was likely that the lower photosynthesis in cool root-zones was predominantly the result of a stomatal limitation. One week after discontinuation of the temperature treatments, gas exchange was similar between the plants, indicating a reversible physiological response to soil temperature. In this anisohydric grapevine variety both night-time and daytime stomatal conductance were responsive to root-zone temperature. Because nocturnal transpiration has implications for overall plant water status, predictive climate change models using stomatal conductance will need to factor in this root-zone variable.

Metrics of Cellular and Vascular Infiltration of Human Acellular Dermal Matrix in Ventral Hernia Repairs

PubMed Central

Campbell, Kristin Turza; Burns, Nadja K.; Ensor, Joe; Butler, Charles E.

2012-01-01

Background Human acellular dermal matrix (HADM) is used for ventral hernia repair, as it resists infection and remodels via surrounding tissue. However, the tissue source and impact of basement membrane (BM) on cell and vessel infiltration have not been determined. We hypothesized that musculofascia would be the primary tissue source of cells and vessels infiltrating into HADM and the BM would inhibit infiltration. Methods Fifty-six guinea pigs underwent inlay HADM ventral hernia repair with the BM oriented toward or away from the peritoneum. At postoperative weeks 1, 2, or 4, repair sites were completely excised. Histologic and immunohistochemical analyses were performed to quantify cell and vessel density within repair-site zones, including interface (lateral, beneath musculofascia) and center (beneath subcutaneous fat) zones. Cell and vessel quantities were compared as functions of zone, BM orientation, and time. Results Cellular and vascular infiltration increased over time universally. The interface demonstrated greater mean cell density than the center (weeks 1 and 2, p=0.01, p<0.0001). Cell density was greater with the BM oriented toward the peritoneum at week 4 (p=0.02). The interface zone had greater mean vessel density than the center zone at week 4 (p<0.0001). Orienting the BM toward the peritoneum increased vessel density at week 4 (p=0.0004). Conclusion Cellular and vascular infiltration into HADM for ventral hernia repairs was greater from musculofascia than subcutaneous and the BM inhibited cellular and vascular. HADM should be placed adjacent to the best vascularizing tissue to improve fibrovascular incorporation. PMID:22456361

Zooplankton variability and larval striped bass foraging: Evaluating potential match/mismatch regulation

USGS Publications Warehouse

Chick, J.H.; Van Den Avyle, M.J.

1999-01-01

We quantified temporal and spatial variability of zooplankton in three potential nursery sites (river, transition zone, lake) for larval striped bass (Morone saxatilis) in Lake Marion, South Carolina, during April and May 1993-1995. In two of three years, microzooplankton (rotifers and copepod nauplii) density was significantly greater in the lake site than in the river or transition zone. Macrozooplankton (>200 ??m) composition varied among the three sites in all years with adult copepods and cladocerans dominant at the lake, and juvenile Corbicula fluminea dominant at the river and transition zone. Laboratory feeding experiments, simulating both among-site (site treatments) and within-site (density treatments) variability, were conducted in 1995 to quantify the effects of the observed zooplankton variability on foraging success of larval striped bass. A greater proportion of larvae fed in the lake than in the river or transition-zone treatments across all density treatments: mean (x), 10x and 100x. Larvae also ingested significantly more dry mass of prey in the lake treatment in both the mean and 10x density treatments. Field zooplankton and laboratory feeding data suggest that both spatial and temporal variability of zooplankton influence larval striped bass foraging. Prey density levels that supported successful foraging in our feeding experiments occurred in the lake during late April and May in 1994 and 1995 but were never observed in the river or transition zone. Because the rivers flowing into Lake Marion are regulated, it may be possible to devise flow management schemes that facilitate larval transport to the lake and thereby increase the proportion of larvae matched to suitable prey resources.

Estimation of Existence Geothermal Manifestation Using Very Low Frequency (VLF) Method in the PagerkandangVulcanic, Dieng, Central Java

NASA Astrophysics Data System (ADS)

Wulandari, Asri; Asti Anggari, Ega; Dwiasih, Novi; Suyanto, Imam

2018-03-01

Very Low Frequency (VLF) measurement has been done at Pagerkandang Volcanic, Dieng Volcanic Complex (DVC) to examine the possible existence of conductive zones that related with geothermal manifestation. VLF – EM survey used tilt mode with T-VLF BRGM Iris Instrument operated with two frequencies, they are 22200 Hz from Japan (JJI) and 19800 Hz from Australia (NWC). There are five lines with distance between lines is 50 m, and distance between measure points is 20 m. The parameters measured from VLF method are tilt angle (%) and elliptisity (%). Data processed by tilt angle value with fraser and Karous – Hjelt filter used WinVLF program. Karous – Hjelt filter resulted current density contour to estimate lateral location from conductive and resistive zones. The conductive zone is interpreted as the area which have high current density value. This area located at eastern dan western of Pagerkandang Volcanic. The conductive zone related to geothermal manifestation as like as fumarol that appeared because presenced of normal fault. Whereas the resistive zone is interpreted as the area which have low current density value. This area spread almost in the middle of the Pagerkandang Volcanic. The resistive zone was caused by the high weathering in claystone.

Zone-dependent changes in human vertebral trabecular bone: clinical implications.

PubMed

Thomsen, Jesper Skovhus; Ebbesen, E N; Mosekilde, Li

2002-05-01

We have previously shown that there are pronounced age-related changes in human vertebral cancellous bone density and microarchitecture. However, the magnitude of these changes seemed to be dependent on zone location in the vertebral body-the central third vs. the areas adjacent to the endplates. The aim of the present study was, therefore, to investigate whether such zone-specific differences could be identified by static histomorphometric measures. The material comprised 48 individuals (24 women aged 19-97 years, and 24 men aged 23-95 years). Three of the women had a known fracture of the L-2. From each L-2, thick frontal sections of half of the vertebra were embedded undecalcified in methylmethacrylate, cut into 10-microm-thick sections, and stained with aniline blue. The sections were scanned into a computer, and classic static histomorphometry was performed on the images. The histomorphometry was performed on both the whole section and on the separate zones (central and sub-endplate zone). The results showed that trabecular bone volume, trabecular number, and connectivity density decreased significantly faster with age, whereas marrow space star volume increased significantly faster with age in the zones adjacent to the endplates than in the central zone. The other histomorphometric measures showed no zone specificity in relation to aging. However, trabecular thickness and trabecular separation were both higher at all ages in the central zone than in the sub-endplate zone, although this was significant only for trabecular separation. The described differences might have significant clinical implications concerning quantitative computed tomography (QCT) scanning, X-ray analyses, and assessment of fracture liability in the human spine, but the underlying pathogenesis is still not known. This study shows that the human vertebral body can be described as two distinct zones with very specific age-related changes in density and microstructure. This zone-specificity is important for the correct interpretation of clinical data.

Evaluation of potential site for mineral processing plant

NASA Astrophysics Data System (ADS)

Izwan Ishak, Muhamad Noor; Sipaun, Susan Maria; Mustapha, Ismail; Fahmi Engku Chik, Engku Mohd; Abdullah, Nurliyana; Affandi Mahmood, Airwan

2018-01-01

Nuclear moisture-density gauge is a type of instrument for measuring density and moisture of the material in a relatively thin zone beneath a surface of the material by using low activity of neutron and gamma radiation source. Density and moisture content data of the compacted layers are needed to determine the degree of compaction of soils, aggregate, concrete, asphalt or other materials used in civil engineering works. A gamma radiation source is mounted inside gauge housing with the source rod vertically extended to various depth positions. Direct transmission gamma radiation technique is used to obtain the count reading for the number of photons emitted before it is converted into density reading by microprocessor. This paper presents the inspection technique and results for the measurement of soil moisture and density carried out at potential site for mineral processing plant, Malaysian Nuclear Agency. Primarily, the experiment was conducted to ensure the compaction of ground is suitable for the plant construction. From the calculation, the percentages of soil wet density compaction (%WD Compact) are within acceptable limits with respect to the standard compacted wet soil density measured in the laboratory.

Astrophysical radiation environments of habitable worlds

NASA Astrophysics Data System (ADS)

Smith, David Samuel

Numerous astrophysical sources of radiation affect the environment of planets orbiting within the liquid-water habitable zone of main-sequence stars. This dissertation reaches a number of conclusions about the ionizing radiation environment of the habitable zone with respect to X-rays and gamma-rays from stellar flares and background Galactic cosmic rays. Gamma-rays and X-rays incident on terrestrial-like exoplanet atmospheres can be efficiently reprocessed into diffuse UV emission that, depending on the presence of atmospheric UV absorbers, can reach the surface. Extreme solar X-ray flares over the last 4.6 Gyr could have delivered large enough radiation doses to the Martian surface to sterilize any unprotected organisms, depending on the largest energy releases possible. These flares also pose a significant hazard to manned space missions, since a large flare can occur with little or no warning during an extravehicular activity. A flare as large as the largest observed could deliver radiation doses exceeding safety limits to an astronaut protected by only a spacesuit. With respect to particle radiation, the nature of Galactic cosmic-ray modulation by astrospheres means that habitable-zone cosmic-ray fluxes change by much larger magnitudes when passing through low- densities regions of the interstellar medium. In contrast to the popular idea that passages through dense molecular clouds are required to significantly enhance Galactic cosmic-ray fluxes and affect planets' electrical circuits, background mutation rates, and climates, we find that densities of only 0.1-10 cm -3 , the densities of most interstellar clouds, are sufficient to bring fluxes close to the full, interstellar level. Finally, passages through dense molecular clouds are necessary to shrink astrospheres to within the habitable zone, but such events produce even higher interstellar hydrogen and dust accretion rates than have been estimated because of the combination of enhanced charge-exchange rates between stellar-wind ions and interstellar neutrals and the growing importance of the central star's gravity on particle trajectories as the astrosphere shrinks.

Does human pressure affect the community structure of surf zone fish in sandy beaches?

NASA Astrophysics Data System (ADS)

Costa, Leonardo Lopes; Landmann, Júlia G.; Gaelzer, Luiz R.; Zalmon, Ilana R.

2017-01-01

Intense tourism and human activities have resulted in habitat destruction in sandy beach ecosystems with negative impacts on the associated communities. To investigate whether urbanized beaches affect surf zone fish communities, fish and their benthic macrofaunal prey were collected during periods of low and high human pressure at two beaches on the Southeastern Brazilian coast. A BACI experimental design (Before-After-Control-Impact) was adapted for comparisons of tourism impact on fish community composition and structure in urbanized, intermediate and non-urbanized sectors of each beach. At the end of the summer season, we observed a significant reduction in fish richness, abundance, and diversity in the high tourist pressure areas. The negative association between visitors' abundance and the macrofaunal density suggests that urbanized beaches are avoided by surf zone fish due to higher human pressure and the reduction of food availability. Our results indicate that surf zone fish should be included in environmental impact studies in sandy beaches, including commercial species, e.g., the bluefish Pomatomus saltatrix. The comparative results from the less urbanized areas suggest that environmental zoning and visitation limits should be used as effective management and preservation strategies on beaches with high conservation potential.

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Atwani, Osman; Nathaniel II, James E.; Leff, Asher C.

Nanocrystalline materials are radiation-tolerant materials’ candidates due to their high defect sink density. Here, nanocrystalline iron films were irradiated with 10 keV helium ions in situ in a transmission electron microscope at elevated temperatures. Grain-size-dependent bubble density changes and denuded zone occurrence were observed at 700 K, but not at 573 K. This transition, attributed to increased helium–vacancy migration at elevated temperatures, suggests that nanocrystalline microstructures are more resistant to swelling at 700 K due to decreased bubble density. Finally, denuded zone formation had no correlation with grain size and misorientation angle under the conditions studied.

ABSORPTION MEASURE DISTRIBUTION IN Mrk 509

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adhikari, T. P.; Różańska, A.; Sobolewska, M.

2015-12-20

In this paper we model the observed absorption measure distribution (AMD) in Mrk 509, which spans three orders of magnitude in ionization level with a single-zone absorber in pressure equilibrium. AMD is usually constructed from observations of narrow absorption lines in radio-quiet active galaxies with warm absorbers. We study the properties of the warm absorber in Mrk 509 using recently published broadband spectral energy distribution observed with different instruments. This spectrum is an input in radiative transfer computations with full photoionization treatment using the titan code. We show that the simplest way to fully reproduce the shape of AMD is tomore » assume that the warm absorber is a single zone under constant total pressure. With this assumption, we found theoretical AMD that matches the observed AMD determined on the basis of the 600 ks reflection grating spectrometer XMM-Newton spectrum of Mrk 509. The softness of the source spectrum and the important role of the free–free emission breaks the usual degeneracy in the ionization state calculations, and the explicit dependence of the depths of AMD dips on density open a new path to the density diagnostic for the warm absorber. In Mrk 509, the implied density is of the order of 10{sup 8} cm{sup −3}.« less

Physical Properties of 3D Interconnected Graphite Networks - Aerographite

DTIC Science & Technology

2015-10-30

Figure 1.2: Influence of toluene injection rate per time on Aerographite density...................... 6 Figure 1.3: Influence of toluene injection ...densities ........................... 20 Figure 3.15: Capacitance as a function of carbon precursor injection rate .............................. 20...At a constant temperature profile of 200° C in the injection zone and 760° C in main zone, a carbon precursor (toluene) is injected with a

SU-E-T-791: Validation of a Determinant Based Photon Transport Solver in Dose Perturbed By Diverse Media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuo, H; Tome, W; Yaparpalvi, R

Purpose: To validate a determinant based photon transport solver in dose imparted within different transition zone between different medium. Methods: Thickness (.2cm,.5cm, 1cm, 3cm) from various materials (Air - density=0.0012g/cm3, Cork-0.19g/cm3, Lung-0.26g/cm3, Bone-1.85g/cm3, Aluminum (Al)-2.7g/cm3, Titanium (Ti)-4.42g/cm3, Iron (Fe)-8g/cm3) were sandwiched by 10cm solid water. 6MV were used to study the calculation difference between a superposition photon beam model (AAA) and the determinant based Boltzmann photon transport solver (XB) at the upstream (I) and downstream boarder (II) of the medium, within the medium (III), and at far distance downstream away from medium (IV). Calculation was validated with available thickness ofmore » Air, Cork, Lung, Al, Ti and Fe. Results are presented as the ratio of the dose at the point with medium perturbation to the same point dose without perturbation. Results: Zone I showed different backscatter enhancement from high-density materials within the 5mm of the upstream border. AAA showed no backscatter at all, XB showed good agreement beyond 1mm upstream (1.18 vs 1.14, 1.09 vs 1.10, and 1.04 vs 1.05 for Fe, Ti, and Fe, respectively). Zone II showed a re-buildup after exiting high-density medium and Air but no build up for density close to water in both of the measurement and XB. AAA yielded the opposite results in Zone II. XB and AAA showed in Zone III very different absorption in high density medium and the Air. XB and measurement had high concordance regarding photon attenuation in Zone IV. AAA showed less agreement especially when the medium was Air or Fe. Conclusion: XB compared well with measurement in regions 1mm away from the interface. Planning using XB should be beneficial for External Beam Planning in situations with large air cavity, very low lung density, compact bone, and any kind of metal implant.« less

Protostellar Disk Evolution over Million-year Timescales with a Prescription for Magnetized Turbulence

NASA Astrophysics Data System (ADS)

Landry, Russell; Dodson-Robinson, Sarah E.; Turner, Neal J.; Abram, Greg

2013-07-01

Magnetorotational instability (MRI) is the most promising mechanism behind accretion in low-mass protostellar disks. Here we present the first analysis of the global structure and evolution of non-ideal MRI-driven T-Tauri disks on million-year timescales. We accomplish this in a 1+1D simulation by calculating magnetic diffusivities and utilizing turbulence activity criteria to determine thermal structure and accretion rate without resorting to a three-dimensional magnetohydrodynamical (MHD) simulation. Our major findings are as follows. First, even for modest surface densities of just a few times the minimum-mass solar nebula, the dead zone encompasses the giant planet-forming region, preserving any compositional gradients. Second, the surface density of the active layer is nearly constant in time at roughly 10 g cm-2, which we use to derive a simple prescription for viscous heating in MRI-active disks for those who wish to avoid detailed MHD computations. Furthermore, unlike a standard disk with constant-α viscosity, the disk midplane does not cool off over time, though the surface cools as the star evolves along the Hayashi track. Instead, the MRI may pile material in the dead zone, causing it to heat up over time. The ice line is firmly in the terrestrial planet-forming region throughout disk evolution and can move either inward or outward with time, depending on whether pileups form near the star. Finally, steady-state mass transport is an extremely poor description of flow through an MRI-active disk, as we see both the turnaround in the accretion flow required by conservation of angular momentum and peaks in \\dot{M}(R) bracketing each side of the dead zone. We caution that MRI activity is sensitive to many parameters, including stellar X-ray flux, grain size, gas/small grain mass ratio and magnetic field strength, and we have not performed an exhaustive parameter study here. Our 1+1D model also does not include azimuthal information, which prevents us from modeling the effects of Rossby waves.

PROTOSTELLAR DISK EVOLUTION OVER MILLION-YEAR TIMESCALES WITH A PRESCRIPTION FOR MAGNETIZED TURBULENCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landry, Russell; Dodson-Robinson, Sarah E.; Turner, Neal J.

2013-07-10

Magnetorotational instability (MRI) is the most promising mechanism behind accretion in low-mass protostellar disks. Here we present the first analysis of the global structure and evolution of non-ideal MRI-driven T-Tauri disks on million-year timescales. We accomplish this in a 1+1D simulation by calculating magnetic diffusivities and utilizing turbulence activity criteria to determine thermal structure and accretion rate without resorting to a three-dimensional magnetohydrodynamical (MHD) simulation. Our major findings are as follows. First, even for modest surface densities of just a few times the minimum-mass solar nebula, the dead zone encompasses the giant planet-forming region, preserving any compositional gradients. Second, themore » surface density of the active layer is nearly constant in time at roughly 10 g cm{sup -2}, which we use to derive a simple prescription for viscous heating in MRI-active disks for those who wish to avoid detailed MHD computations. Furthermore, unlike a standard disk with constant-{alpha} viscosity, the disk midplane does not cool off over time, though the surface cools as the star evolves along the Hayashi track. Instead, the MRI may pile material in the dead zone, causing it to heat up over time. The ice line is firmly in the terrestrial planet-forming region throughout disk evolution and can move either inward or outward with time, depending on whether pileups form near the star. Finally, steady-state mass transport is an extremely poor description of flow through an MRI-active disk, as we see both the turnaround in the accretion flow required by conservation of angular momentum and peaks in M-dot (R) bracketing each side of the dead zone. We caution that MRI activity is sensitive to many parameters, including stellar X-ray flux, grain size, gas/small grain mass ratio and magnetic field strength, and we have not performed an exhaustive parameter study here. Our 1+1D model also does not include azimuthal information, which prevents us from modeling the effects of Rossby waves.« less

On the electron density localization in elemental cubic ceramic and FCC transition metals by means of a localized electrons detector.

PubMed

Aray, Yosslen; Paredes, Ricardo; Álvarez, Luis Javier; Martiz, Alejandro

2017-06-14

The electron density localization in insulator and semiconductor elemental cubic materials with diamond structure, carbon, silicon, germanium, and tin, and good metallic conductors with face centered cubic structure such as α-Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au, was studied using a localized electrons detector defined in the local moment representation. Our results clearly show an opposite pattern of the electron density localization for the cubic ceramic and transition metal materials. It was found that, for the elemental ceramic materials, the zone of low electron localization is very small and is mainly localized on the atomic basin edges. On the contrary, for the transition metals, there are low-valued localized electrons detector isocontours defining a zone of highly delocalized electrons that extends throughout the material. We have found that the best conductors are those in which the electron density at this low-value zone is the lowest.

Impact of Camping on Soil Properties at Strawberry Lake, North Dakota, USA

NASA Astrophysics Data System (ADS)

Brevik, Eric C.; Tibor, Matthew A.

2014-05-01

Recreational activity at campsites can cause compaction and metal contamination of soils. This study compared the bulk densities, penetration resistance values, organic matter contents, and Zn, Mn, and Cu contents of soils sampled from zones of varying recreational activity within the campsites at Strawberry Lake, North Dakota, USA. The results of this study showed that there were statistically significant increases in the soil bulk densities and soil penetration resistance values compared to the controls. However, the low recreational intensity has not compacted the surface soils beyond an average of 1.36 g cm-3, which is not dense enough to hinder the root growth of the surrounding vegetation. There were no statistically significant differences between the soil organic matter content of the different activity zones at the 95% confidence interval. Zinc values were four orders of magnitude and Cu values three to four orders of magnitude below US EPA guideline limits. The EPA does not have guidelines for Mn, but Mn levels were lower than reported typical natural values for a nearby area. Therefore, metal contents were not high enough to be of concern. Taken together, these results were interpreted to indicate that the low-intensity camping activities that occur at Strawberry Lake campground have not had a significant negative impact on the soils found there. Additional information on this study can be found in Tibor and Brevik (2013). Reference Tibor, M.A., and E.C. Brevik. 2013. Anthropogenic Impacts on Campsite Soils at Strawberry Lake, North Dakota. Soil Horizons 54: doi:10.2136/sh13-06-0016.

Metrics of cellular and vascular infiltration of human acellular dermal matrix in ventral hernia repairs.

PubMed

Campbell, Kristin Turza; Burns, Nadja K; Ensor, Joe; Butler, Charles E

2012-04-01

Human acellular dermal matrix is used for ventral hernia repair, as it resists infection and remodels by means of surrounding tissue. However, the tissue source and impact of basement membrane on cell and vessel infiltration have not been determined. The authors hypothesized that musculofascia would be the primary tissue source of cells and vessels infiltrating into human acellular dermal matrix and that the basement membrane would inhibit infiltration. Fifty-six guinea pigs underwent inlay human acellular dermal matrix ventral hernia repair with the basement membrane oriented toward or away from the peritoneum. At postoperative weeks 1, 2, or 4, repair sites were completely excised. Histologic and immunohistochemical analyses were performed to quantify cell and vessel density within repair-site zones, including interface (lateral, beneath musculofascia) and center (beneath subcutaneous fat) zones. Cell and vessel quantities were compared as functions of zone, basement membrane orientation, and time. Cellular and vascular infiltration increased over time universally. The interface demonstrated greater mean cell density than the center (weeks 1 and 2, p = 0.01 and p < 0.0001, respectively). Cell density was greater with the basement membrane oriented toward the peritoneum at week 4 (p = 0.02). The interface zone had greater mean vessel density than the center zone at week 4 (p < 0.0001). Orienting the basement membrane toward the peritoneum increased vessel density at week 4 (p = 0.0004). Cellular and vascular infiltration into human acellular dermal matrix for ventral hernia repairs was greater from musculofascia than from subcutaneous fat, and the basement membrane inhibited cellular and vascular infiltration. Human acellular dermal matrix should be placed adjacent to the best vascularizing tissue to improve fibrovascular incorporation.

Density effect on great tit (Parus major) clutch size intensifies in a polluted environment.

PubMed

Eeva, Tapio; Lehikoinen, Esa

2013-12-01

Long-term data on a great tit (Parus major) population breeding in a metal-polluted zone around a copper-nickel smelter indicate that, against expectations, the clutch size of this species is decreasing even though metal emissions in the area have decreased considerably over the past two decades. Here, we document long-term population-level changes in the clutch size of P. major and explore if changes in population density, population numbers of competing species, timing of breeding, breeding habitat, or female age distribution can explain decreasing clutch sizes. Clutch size of P. major decreased by one egg in the polluted zone during the past 21 years, while there was no significant change in clutch size in the unpolluted reference zone over this time period. Density of P. major nests was similar in both environments but increased threefold during the study period in both areas (from 0.8 to 2.4 nest/ha). In the polluted zone, clutch size has decreased as a response to a considerable increase in population density, while a corresponding density change in the unpolluted zone did not have such an effect. The other factors studied did not explain the clutch size trend. Fledgling numbers in the polluted environment have been relatively low since the beginning of the study period, and they do not show a corresponding decrease to that noted for the clutch size over the same time period. Our study shows that responses of commonly measured life-history parameters to anthropogenic pollution depend on the structure of the breeding population. Interactions between pollution and intrinsic population characters should therefore be taken into account in environmental studies.

Spatial and temporal variability in estuary habitat use by American alligators

USGS Publications Warehouse

Fujisaki, Ikuko; Hart, Kristen M.; Cherkiss, Michael S.; Mazzotti, Frank J.; Beauchamp, Jeffrey S.; Jeffery, Brian M.; Brandt, Laura A.

2016-01-01

Estuarine habitat occupied by Alligator mississippiensis, a primarily freshwater species, is spatially and temporally heterogeneous largely due to a salinity gradient that fluctuates. Using long-term night light survey data, we examined seasonal patterns in alligators’ habitat use by size classes in midstream and downstream estuary zones of Shark River, Everglades National Park, in southern Florida. We observed predominantly large-sized alligators (total length ≥ 1.75 m); observations of alligators in the small size classes (0.5 m ≤ total length < 1.25 m) were rare especially in the higher-salinity downstream zone. The density of alligators in the downstream zone was lower than that of the midstream zone during the dry season when salinity increases due to reduced precipitation. Conversely, the density of the large size alligators was higher in the downstream zone than in the midstream zone during the wet season, likely because of reduced salinity. We also found a significant declining trend over time in the number of alligators in the dry season, which coincides with the reported decline in alligator relative density in southern Florida freshwater wetlands. Our results indicated high adaptability of alligators to the fluctuating habitat conditions. Use of estuaries by alligators is likely driven in part by physiology and possibly by reproductive cycle, and our results supported their opportunistic use of estuary habitat and ontogenetic niche shifts.

Developmental morphology of cover crop species exhibit contrasting behaviour to changes in soil bulk density, revealed by X-ray computed tomography

PubMed Central

Burr-Hersey, Jasmine E.; Mooney, Sacha J.; Bengough, A. Glyn; Mairhofer, Stefan

2017-01-01

Plant roots growing through soil typically encounter considerable structural heterogeneity, and local variations in soil dry bulk density. The way the in situ architecture of root systems of different species respond to such heterogeneity is poorly understood due to challenges in visualising roots growing in soil. The objective of this study was to visualise and quantify the impact of abrupt changes in soil bulk density on the roots of three cover crop species with contrasting inherent root morphologies, viz. tillage radish (Raphanus sativus), vetch (Vicia sativa) and black oat (Avena strigosa). The species were grown in soil columns containing a two-layer compaction treatment featuring a 1.2 g cm-3 (uncompacted) zone overlaying a 1.4 g cm-3 (compacted) zone. Three-dimensional visualisations of the root architecture were generated via X-ray computed tomography, and an automated root-segmentation imaging algorithm. Three classes of behaviour were manifest as a result of roots encountering the compacted interface, directly related to the species. For radish, there was switch from a single tap-root to multiple perpendicular roots which penetrated the compacted zone, whilst for vetch primary roots were diverted more horizontally with limited lateral growth at less acute angles. Black oat roots penetrated the compacted zone with no apparent deviation. Smaller root volume, surface area and lateral growth were consistently observed in the compacted zone in comparison to the uncompacted zone across all species. The rapid transition in soil bulk density had a large effect on root morphology that differed greatly between species, with major implications for how these cover crops will modify and interact with soil structure. PMID:28753645

Developmental morphology of cover crop species exhibit contrasting behaviour to changes in soil bulk density, revealed by X-ray computed tomography.

PubMed

Burr-Hersey, Jasmine E; Mooney, Sacha J; Bengough, A Glyn; Mairhofer, Stefan; Ritz, Karl

2017-01-01

Plant roots growing through soil typically encounter considerable structural heterogeneity, and local variations in soil dry bulk density. The way the in situ architecture of root systems of different species respond to such heterogeneity is poorly understood due to challenges in visualising roots growing in soil. The objective of this study was to visualise and quantify the impact of abrupt changes in soil bulk density on the roots of three cover crop species with contrasting inherent root morphologies, viz. tillage radish (Raphanus sativus), vetch (Vicia sativa) and black oat (Avena strigosa). The species were grown in soil columns containing a two-layer compaction treatment featuring a 1.2 g cm-3 (uncompacted) zone overlaying a 1.4 g cm-3 (compacted) zone. Three-dimensional visualisations of the root architecture were generated via X-ray computed tomography, and an automated root-segmentation imaging algorithm. Three classes of behaviour were manifest as a result of roots encountering the compacted interface, directly related to the species. For radish, there was switch from a single tap-root to multiple perpendicular roots which penetrated the compacted zone, whilst for vetch primary roots were diverted more horizontally with limited lateral growth at less acute angles. Black oat roots penetrated the compacted zone with no apparent deviation. Smaller root volume, surface area and lateral growth were consistently observed in the compacted zone in comparison to the uncompacted zone across all species. The rapid transition in soil bulk density had a large effect on root morphology that differed greatly between species, with major implications for how these cover crops will modify and interact with soil structure.

Radon measurements in an area of tectonic zone: A case study in Central Slovakia.

PubMed

Mojzeš, Andrej; Marko, František; Porubčanová, Barbara; Bartošová, Andrea

2017-01-01

General overviews of the spatial distribution of radon and other natural radionuclides in the geological basement as commonly presented on regional or country maps tend to offer a low density of information, insufficient for gaining relevant knowledge of the environmental impact, especially in the areas of tectonic zones often assumed to be radon prone and therefore dangerous for the human population. An additional survey, employing radon measurements in soil and indoor air, was carried out seeking to provide a more detailed characterization of the expressive fault zone of the Malá Magura in the Horná Nitra region of Central Slovakia. Eventually, the results of soil 222 Rn volume activity measurements along two short profiles crossing the assumed fault line did not reveal any indication of active nature of local tectonics, but merely pointed to an existence of a zone of contact between different types of rocks. The results of indoor radon measurements in dwellings of two villages lying on the studied fault showed values that were lower than those commonly observed on the Slovak territory, ruling out any negative health impact on population. Nevertheless, in order to add new findings to an already well established study of geological structure of the region, the indoor radon data collected through a previous survey require a further analysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

The seismogenic Gole Larghe Fault Zone (Italian Southern Alps): quantitative 3D characterization of the fault/fracture network, mapping of evidences of fluid-rock interaction, and modelling of the hydraulic structure through the seismic cycle

NASA Astrophysics Data System (ADS)

Bistacchi, A.; Mittempergher, S.; Di Toro, G.; Smith, S. A. F.; Garofalo, P. S.

2016-12-01

The Gole Larghe Fault Zone (GLFZ) was exhumed from 8 km depth, where it was characterized by seismic activity (pseudotachylytes) and hydrous fluid flow (alteration halos and precipitation of hydrothermal minerals in veins and cataclasites). Thanks to glacier-polished outcrops exposing the 400 m-thick fault zone over a continuous area > 1.5 km2, the fault zone architecture has been quantitatively described with an unprecedented detail, providing a rich dataset to generate 3D Discrete Fracture Network (DFN) models and simulate the fault zone hydraulic properties. The fault and fracture network has been characterized combining > 2 km of scanlines and semi-automatic mapping of faults and fractures on several photogrammetric 3D Digital Outcrop Models (3D DOMs). This allowed obtaining robust probability density functions for parameters of fault and fracture sets: orientation, fracture intensity and density, spacing, persistency, length, thickness/aperture, termination. The spatial distribution of fractures (random, clustered, anticlustered…) has been characterized with geostatistics. Evidences of fluid/rock interaction (alteration halos, hydrothermal veins, etc.) have been mapped on the same outcrops, revealing sectors of the fault zone strongly impacted, vs. completely unaffected, by fluid/rock interaction, separated by convolute infiltration fronts. Field and microstructural evidence revealed that higher permeability was obtained in the syn- to early post-seismic period, when fractures were (re)opened by off-fault deformation. We have developed a parametric hydraulic model of the GLFZ and calibrated it, varying the fraction of faults/fractures that were open in the post-seismic, with the goal of obtaining realistic fluid flow and permeability values, and a flow pattern consistent with the observed alteration/mineralization pattern. The fraction of open fractures is very close to the percolation threshold of the DFN, and the permeability tensor is strongly anisotropic, resulting in a marked channelling of fluid flow in the inner part of the fault zone. Amongst possible seismological applications of our study, we will discuss the possibility to evaluate the coseismic fracture intensity due to off-fault damage, a fundamental mechanical parameter in the energy balance of earthquakes.

Convergence of semantics and emotional expression within the IFG pars orbitalis.

PubMed

Belyk, Michel; Brown, Steven; Lim, Jessica; Kotz, Sonja A

2017-08-01

Humans communicate through a combination of linguistic and emotional channels, including propositional speech, writing, sign language, music, but also prosodic, facial, and gestural expression. These channels can be interpreted separately or they can be integrated to multimodally convey complex meanings. Neural models of the perception of semantics and emotion include nodes for both functions in the inferior frontal gyrus pars orbitalis (IFGorb). However, it is not known whether this convergence involves a common functional zone or instead specialized subregions that process semantics and emotion separately. To address this, we performed Kernel Density Estimation meta-analyses of published neuroimaging studies of the perception of semantics or emotion that reported activation in the IFGorb. The results demonstrated that the IFGorb contains two zones with distinct functional profiles. A lateral zone, situated immediately ventral to Broca's area, was implicated in both semantics and emotion. Another zone, deep within the ventral frontal operculum, was engaged almost exclusively by studies of emotion. Follow-up analysis using Meta-Analytic Connectivity Modeling demonstrated that both zones were frequently co-activated with a common network of sensory, motor, and limbic structures, although the lateral zone had a greater association with prefrontal cortical areas involved in executive function. The status of the lateral IFGorb as a point of convergence between the networks for processing semantic and emotional content across modalities of communication is intriguing since this structure is preserved across primates with limited semantic abilities. Hence, the IFGorb may have initially evolved to support the comprehension of emotional signals, being later co-opted to support semantic communication in humans by forming new connections with brain regions that formed the human semantic network. Copyright © 2017 Elsevier Inc. All rights reserved.

Ratios of molecular hydrogen line intensities in shocked gas - Evidence for cooling zones

NASA Technical Reports Server (NTRS)

Brand, P. W. J. L.; Moorhouse, A.; Bird, M.; Burton, M. G.; Geballe, T. R.

1988-01-01

Column densities of molecular hydrogen have been calculated from 19 infrared vibration-rotation and pure rotational line intensities measured at peak 1 of the Orion molecular outflow. The run of column density with energy level is similar to a simple coolng zone model of the line-emitting region, but is not well fitted by predictions of C-shock models current in the literature.

Quantitative analysis of the impacts of terrestrial environmental factors on precipitation variation over the Beibu Gulf Economic Zone in Coastal Southwest China

PubMed Central

Zhao, Yinjun; Deng, Qiyu; Lin, Qing; Cai, Chunting

2017-01-01

Taking the Guangxi Beibu Gulf Economic Zone as the study area, this paper utilizes the geographical detector model to quantify the feedback effects from the terrestrial environment on precipitation variation from 1985 to 2010 with a comprehensive consideration of natural factors (forest coverage rate, vegetation type, terrain, terrestrial ecosystem types, land use and land cover change) and social factors (population density, farmland rate, GDP and urbanization rate). First, we found that the precipitation trend rate in the Beibu Gulf Economic Zone is between −47 and 96 mm/10a. Second, forest coverage rate change (FCRC), urbanization rate change (URC), GDP change (GDPC) and population density change (PDC) have a larger contribution to precipitation change through land-surface feedback, which makes them the leading factors. Third, the human element is found to primarily account for the precipitation changes in this region, as humans are the active media linking and enhancing these impact factors. Finally, it can be concluded that the interaction of impact factor pairs has a significant effect compared to the corresponding single factor on precipitation changes. The geographical detector model offers an analytical framework to reveal the terrestrial factors affecting the precipitation change, which gives direction for future work on regional climate modeling and analyses. PMID:28294123

Stabilization of a salamander moving hybrid zone.

PubMed

Visser, Michaël; de Leeuw, Maarten; Zuiderwijk, Annie; Arntzen, Jan W

2017-01-01

When related species meet upon postglacial range expansion, hybrid zones are frequently formed. Theory predicts that such zones may move over the landscape until equilibrium conditions are reached. One hybrid zone observed to be moving in historical times (1950-1979) is that of the pond-breeding salamanders Triturus cristatus and Triturus marmoratus in western France. We identified the ecological correlates of the species hybrid zone as elevation, forestation, and hedgerows favoring the more terrestrial T. marmoratus and pond density favoring the more aquatic T. cristatus . The past movement of the zone of ca. 30 km over three decades has probably been driven by the drastic postwar reduction of the "bocage" hedgerow landscape, favoring T. cristatus over T. marmoratus . No further hybrid zone movement was observed from 1979 to the present. To explain the changing dynamics of the hybrid zone, we propose that it stalled, either because an equilibrium was found at an altitude of ca. 140 m a.s.l. or due to pond loss and decreased population densities. While we cannot rule out the former explanation, we found support for the latter. Under agricultural intensification, ponds in the study area are lost at an unprecedented rate of 5.5% per year, so that remaining Triturus populations are increasingly isolated, hampering dispersal and further hybrid zone movement.

Evaluation of soil manipulation to prepare engineered earthen waste covers for revegetation

DOE PAGES

Waugh, W. Joseph; Benson, Craig H.; Albright, William H.; ...

2015-10-21

Seven ripping treatments designed to improve soil physical conditions for revegetation were compared on a test pad simulating an earthen cover for a waste disposal cell. The field test was part of study of methods to convert compacted-soil waste covers into evapotranspiration covers. The test pad consisted of a compacted layer of fine-textured soil simulating a barrier protection layer overlain by a gravelly sand bedding layer and a cobble armor layer. Treatments included combinations of soil-ripping implements (conventional shank [CS], wing-tipped shank [WTS], and parabolic oscillating shank with wings [POS]), ripping depths, and number of passes. Dimensions, dry density, moisturemore » content, and particle size distribution of disturbance zones were determined in two trenches excavated across rip rows. The goal was to create a root-zone dry density between 1.2 and 1.6 Mg m-3 and a seedbed soil texture ranging from clay loam to sandy loam with low rock content. All treatments created V-shaped disturbance zones as measured on trench faces. Disturbance zone size was most influenced by ripping depth. Winged implements created larger disturbance zones. All treatments lifted fines into the bedding layer, moved gravel and cobble down into the fine-textured protection layer, and thereby disrupted the capillary barrier at the interface. Changes in dry density within disturbance zones were comparable for the CS and WTS treatments but were highly variable among POS treatments. Water content increased in the bedding layer and decreased in the protection layer after ripping. The POS at 1.2-m depth and two passes created the largest zone with a low dry density (1.24 Mg m-3) and the most favorable seedbed soil texture (gravely silt loam). Furthermore, ripping also created large soil aggregates and voids in the protection layer that may produce preferential flow paths and reduce water storage capacity.« less

An experimental investigation of gas fuel injection with X-ray radiography

DOE PAGES

Swantek, Andrew B.; Duke, D. J.; Kastengren, A. L.; ...

2017-04-21

In this paper, an outward-opening compressed natural gas, direct injection fuel injector has been studied with single-shot x-ray radiography. Three dimensional simulations have also been performed to compliment the x-ray data. Argon was used as a surrogate gas for experimental and safety reasons. This technique allows the acquisition of a quantitative mapping of the ensemble-average and standard deviation of the projected density throughout the injection event. Two dimensional, ensemble average and standard deviation data are presented to investigate the quasi-steady-state behavior of the jet. Upstream of the stagnation zone, minimal shot-to-shot variation is observed. Downstream of the stagnation zone, bulkmore » mixing is observed as the jet transitions to a subsonic turbulent jet. From the time averaged data, individual slices at all downstream locations are extracted and an Abel inversion was performed to compute the radial density distribution, which was interpolated to create three dimensional visualizations. The Abel reconstructions reveal that upstream of the stagnation zone, the gas forms an annulus with high argon density and large density gradients. Inside this annulus, a recirculation region with low argon density exists. Downstream, the jet transitions to a fully turbulent jet with Gaussian argon density distributions. This experimental data is intended to serve as a quantitative benchmark for simulations.« less

An experimental investigation of gas fuel injection with X-ray radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swantek, Andrew B.; Duke, D. J.; Kastengren, A. L.

In this paper, an outward-opening compressed natural gas, direct injection fuel injector has been studied with single-shot x-ray radiography. Three dimensional simulations have also been performed to compliment the x-ray data. Argon was used as a surrogate gas for experimental and safety reasons. This technique allows the acquisition of a quantitative mapping of the ensemble-average and standard deviation of the projected density throughout the injection event. Two dimensional, ensemble average and standard deviation data are presented to investigate the quasi-steady-state behavior of the jet. Upstream of the stagnation zone, minimal shot-to-shot variation is observed. Downstream of the stagnation zone, bulkmore » mixing is observed as the jet transitions to a subsonic turbulent jet. From the time averaged data, individual slices at all downstream locations are extracted and an Abel inversion was performed to compute the radial density distribution, which was interpolated to create three dimensional visualizations. The Abel reconstructions reveal that upstream of the stagnation zone, the gas forms an annulus with high argon density and large density gradients. Inside this annulus, a recirculation region with low argon density exists. Downstream, the jet transitions to a fully turbulent jet with Gaussian argon density distributions. This experimental data is intended to serve as a quantitative benchmark for simulations.« less

Current-driven orbital order-disorder transition in LaMnO3

NASA Astrophysics Data System (ADS)

Mondal, Parthasarathi; Bhattacharya, Dipten; Mandal, P.

2011-08-01

We report a significant influence of electric current on the orbital order-disorder transition in LaMnO3. The transition temperature TOO, thermal hysteresis in the resistivity ρ versus temperature T plot around TOO, and latent heat L associated with the transition decrease with an increase in current density. Eventually, at a critical current density, L reaches zero. The transition zone, on the other hand, broadens with an increase in current density. The states at ordered, disordered, and transition zones are all found to be stable within the time window from ˜10-3 to ˜104 s.

Density, distribution, and activity of the ocelot Leopardus pardalis (Carnivora: Felidae) in Southeast Mexican rainforests.

PubMed

Pérez-Irineo, Gabriela; Santos-Moreno, Antonio

2014-12-01

The ocelot Leopardus pardalis is of particular significance in terrestrial communities due to its ecological role within the group of small-sized felids and as a mesopredator. However, despite the reduction of ocelot habitat in Southeast Mexico, there are still very few ecological studies. This research aimed to contribute with some ecological aspects of the species in this region. For this, 29 camera trap stations were established in a rain forest in Los Chimalapas (an area of 22 km2) during a two years period (March 2011-June, 2013), in Oaxaca state, Southeast Mexico. Data allowed the estimation of the population density, activity pattern, sex ratio, residence time, and spatial distribution. Population density was calculated using Capture-Recapture Models for demographically open populations; besides, circular techniques were used to determine if nocturnal and diurnal activity varied significantly over the seasons, and Multiple Discriminant Analysis was used to determine which of the selected environmental variables best explained ocelot abundance in the region. A total of 103 ocelot records were obtained, with a total sampling effort of 8,529 trap-days. Density of 22-38 individuals/100 km2 was estimated. Ocelot population had a high proportion of transient individuals in the zone (55%), and the sex ratio was statistically equal to 1:1. Ocelot activity was more frequent at night (1:00-6:00h), but it also exhibited diurnal activity throughout the study period. Ocelot spatial distribution was positively affected by the proximity to the village as well as by the amount of prey. The ocelot population here appears to be stable, with a density similar to other regions in Central and South America, which could be attributed to the diversity of prey species and a low degree of disturbance in Los Chimalapas.

Spatial Distributions of Potassium, Solutes, and Their Deposition Rates in the Growth Zone of the Primary Corn Root 1

PubMed Central

Silk, Wendy Kuhn; Hsiao, Theodore C.; Diedenhofen, Ulrike; Matson, Christina

1986-01-01

Densities of osmoticum and potassium were measured as a function of distance from the tip of the primary root of Zea mays L. (cv WF9 × mo17). Millimeter segments were excised and analyzed for osmotic potential by a miniaturized freezing point depression technique, and for potassium by flame spectrophotometry. Local deposition rates were estimated from the continuity equation with values for density and growth velocity. Osmotic potential was uniform, −0.73 ± 0.05 megapascals, throughout the growth zone of well-watered roots. Osmoticum deposition rate was 260 μosmoles per gram fresh weight per hour. Potassium density fell from 117 micromoles per gram in the first mm region to 48 micromoles per gram at the base of the growth zone. Potassium deposition rates had a maximum of 29 micromoles per gram per hour at 3.5 millimeters from the tip and were positive (i.e. potassium was being added to the tissue) until 8 millimeters from the tip. The results are discussed in terms of ion relations of the growing zone and growth physics. PMID:16665121

Density and Ultrasonic Characterization of Oil Palm Trunk Infected by Ganoderma Boninense Disease

NASA Astrophysics Data System (ADS)

Najmie, M. M. K.; Khalid, K.; Sidek, A. A.; Jusoh, M. A.

2011-01-01

Oil palm trunks infected by Ganoderma boninense disease have been studied using density and ultrasonic characterizations. The ultrasonic characterizations have been performed using a commercial ultrasonic instrument at the frequency of 54 kHz. The measurements have been done in 3 zones: inner zone, central zone and peripheral zone. It was found that the stem density of the oil palm infected by Ganoderma boninense disease was reduced by 50% in comparison to the original healthy trunk. From this effect the velocity of the ultrasonic wave propagated through the Longitudinal, Radial, and Tangential directions is lower for the trunk infected by Ganoderma boninense disease compared to a healthy trunk. For the 10 cm thickness of samples, the ultrasonic velocity for all transit directions was in range of 260 - 750 ms-1 for the infected sample, whereas for healthy samples was in the range of 460 - 900 ms-1. These results are very useful for the detection of the area which has been affected by the disease.

Geophysical characterization of an active hydrothermal shear zone in granitic rocks

NASA Astrophysics Data System (ADS)

Zahner, Tobias; Baron, Ludovic; Holliger, Klaus; Egli, Daniel

2016-04-01

Hydrothermally active faults and shear zones in the crystalline massifs of the central Alps are currently of particular interest because of their potential similarities and analogies with planned deep petrothermal reservoirs in the Alpine foreland. In order to better understand such hydrothermal systems, a near-vertical, hydrothermally active shear zone embedded in low-permeability granitic rocks has been drilled. This borehole is located on the Grimsel Pass in the central Swiss Alps, has an inclination of 24 degrees with regard to the vertical, and crosses the targeted shear zone between about 82 and 86 meters depth. The borehole has been fully cored and a comprehensive suite of geophysical logging data has been acquired. The latter comprises multi-frequency sonic, ground-penetrating radar, resistivity, self-potential, gamma-gamma, neutron-neutron, optical televiewer, and caliper log data. In addition to this, we have also performed a surface-to-borehole vertical seismic profiling experiment. The televiewer data and the retrieved core samples show a marked increase of the fracture density in the target region, which also finds its expression in rather pronounced and distinct signatures in all other log data. Preliminary results point towards a close correspondence between the ground-penetrating radar and the neutron-neutron log data, which opens the perspective of constraining the effective fracture porosity at vastly differing scales. There is also remarkably good agreement between the sonic log and the vertical seismic profiling data, which may allow for assessing the permeability of the probed fracture network by interpreting these data in a poroelastic context.

Soil organic carbon in Apolobamba (Bolivia): Quantity and quality of the reservoir

NASA Astrophysics Data System (ADS)

Muñoz, M. Á.; Faz, A.

2009-04-01

Global carbon cycle mainly depends on the soil organic matter (SOM). Some reducction of climatic impact techiques are related to the increase of the soil organic carbon (SOC) contents in order to elevate atmospherical carbon inputs. Kinetic mechanisms of the SOC are differents due to the complex interation between biological, physical and chemical processes in the soil. For a full understanding of the SOM contribution to the carbon cycle in the soil, the SOC contents should be addressed. The vicuna (Vicugna vicugna) is an endangered species which belongs to camelid family. Its natural habitat is located in highland grasses in the Andes Montain Range, above 4,000 m.a.s.l. In Bolivia the vicuna is distributed around some andean regions such as Apolobamba. It is a protected area located in the Northwest of Bolivia where native inhabitants carry out a sustainable management of the vicuna. This activity is considered within a programme to improve economical conditions in the area. The vicuna lives in the same habitat than other cattle camelid like alpaca (Lama pacos). The soil is an essential natural resource in the vicuna development and the biodiversity conservation due to its role to support the native vegetation in Apolobamba. The objectives of this research were: (i) the quantification of SOC contents, (ii) the study of the SOC quality and (iii) the determination of the soil degradation degree in some zones in Apolobamba. Eight zones or census places, separated areas with geographic accidents, with different vicuna and alpaca densities were selected: Ulla-Ulla and Killu (low density), Ucha-Ucha and Wakampata (medium density), Sucondori and Caballchiñuni (high density) and Puyo-Puyo and Japu (very high density). One soil profile was taken and three sampling plots were determined in each zone. Three sampling points were selected in each plot and surface (0-5 cm) and subsurface samples (5-15 cm) were collected. Total carbon, total organic carbon (TOC) and water soluble organic carbon (WSOC) were messure. In addition, 13C MNR technique was used in surface samples in each plot in order to determine the main carbonide groups: alkyl, O-alkyl, aromatic and carboxilic. Results were discussing through statistical analyses. Soil profile datas exhibited very low TOC in Ulla-Ulla zone including the surface horizon. Sampling plot results showed maximum TOC contents in Wakampata and Puyo-Puyo surface samples; on the other hand, Sucondori, Caballchiñuni and Ulla-Ulla presented minimum contents. Generally speaking, low and medium WSOC inputs were determined in surface and subsurface samples, respectively, in studied areas. Moreover, Wakampata and Japu zones presented high O-alkyl percentages; it could be related to highest polysacharide concentrations and the easiest SOM degradation, taking into account alkyl/O-alkyl ratios. On the contrary, Ulla-Ulla and Caballchiñuni exhibited highest carboxilic percentages pointing out a SOM oxidation increase. In conclusion, Apolobamba soils presented different SOC conditions. There were some zones which could be characterized as excellent carbon reservoirs due to high SOM quantity and quality; however, in other census places could be identify a certain soil exhaustion degree, as a consequence to the soil overexploitation due to the cattle camelid concentrations both the natural wind erosion in these zones. It should be carried out conservation actions in order to improve the carbon sink and to preserve the soil and the biodiversity in Apolobamba.

Exploring the Ecological Association Between Crime and Medical Marijuana Dispensaries

PubMed Central

Kepple, Nancy J.; Freisthler, Bridget

2012-01-01

Objective: Routine activities theory purports that crime occurs in places with a suitable target, motivated offender, and lack of guardianship. Medical marijuana dispensaries may be places that satisfy these conditions, but this has not yet been studied. The current study examined whether the density of medical marijuana dispensaries is associated with crime. Method: An ecological, cross-sectional design was used to explore the spatial relationship between density of medical marijuana dispensaries and two types of crime rates (violent crime and property crime) in 95 census tracts in Sacramento, CA, during 2009. Spatial error regression methods were used to determine associations between crime rates and density of medical marijuana dispensaries, controlling for neighborhood characteristics associated with routine activities. Results: Violent and property crime rates were positively associated with percentage of commercially zoned areas, percentage of one-person households, and unemployment rate. Higher violent crime rates were associated with concentrated disadvantage. Property crime rates were positively associated with the percentage of population 15–24 years of age. Density of medical marijuana dispensaries was not associated with violent or property crime rates. Conclusions: Consistent with previous work, variables measuring routine activities at the ecological level were related to crime. There were no observed cross-sectional associations between the density of medical marijuana dispensaries and either violent or property crime rates in this study. These results suggest that the density of medical marijuana dispensaries may not be associated with crime rates or that other factors, such as measures dispensaries take to reduce crime (i.e., doormen, video cameras), may increase guardianship such that it deters possible motivated offenders. PMID:22630790

Exploring the ecological association between crime and medical marijuana dispensaries.

PubMed

Kepple, Nancy J; Freisthler, Bridget

2012-07-01

Routine activities theory purports that crime occurs in places with a suitable target, motivated offender, and lack of guardianship. Medical marijuana dispensaries may be places that satisfy these conditions, but this has not yet been studied. The current study examined whether the density of medical marijuana dispensaries is associated with crime. An ecological, cross-sectional design was used to explore the spatial relationship between density of medical marijuana dispensaries and two types of crime rates (violent crime and property crime) in 95 census tracts in Sacramento, CA, during 2009. Spatial error regression methods were used to determine associations between crime rates and density of medical marijuana dispensaries, controlling for neighborhood characteristics associated with routine activities. Violent and property crime rates were positively associated with percentage of commercially zoned areas, percentage of one-person households, and unemployment rate. Higher violent crime rates were associated with concentrated disadvantage. Property crime rates were positively associated with the percentage of population 15-24 years of age. Density of medical marijuana dispensaries was not associated with violent or property crime rates. Consistent with previous work, variables measuring routine activities at the ecological level were related to crime. There were no observed cross-sectional associations between the density of medical marijuana dispensaries and either violent or property crime rates in this study. These results suggest that the density of medical marijuana dispensaries may not be associated with crime rates or that other factors, such as measures dispensaries take to reduce crime (i.e., doormen, video cameras), may increase guardianship such that it deters possible motivated offenders.

Water-induced convection in the Earth's mantle transition zone

NASA Astrophysics Data System (ADS)

Richard, Guillaume C.; Bercovici, David

2009-01-01

Water enters the Earth's mantle by subduction of oceanic lithosphere. Most of this water immediately returns to the atmosphere through arc volcanism, but a part of it is expected as deep as the mantle transition zone (410-660 km depth). There, slabs can be deflected and linger before sinking into the lower mantle. Because it lowers the density and viscosity of the transition zone minerals (i.e., wadsleyite and ringwoodite), water is likely to affect the dynamics of the transition zone mantle overlying stagnant slabs. The consequences of water exchange between a floating slab and the transition zone are investigated. In particular, we focus on the possible onset of small-scale convection despite the adverse thermal gradient (i.e., mantle is cooled from below by the slab). The competition between thermal and hydrous effects on the density and thus on the convective stability of the top layer of the slab is examined numerically, including water-dependent density and viscosity and temperature-dependent water solubility. For plausible initial water content in a slab (≥0.5 wt %), an episode of convection is likely to occur after a relatively short time delay (5-20 Ma) after the slab enters the transition zone. However, water induced rheological weakening is seen to be a controlling parameter for the onset time of convection. Moreover, small-scale convection above a stagnant slab greatly enhances the rate of slab dehydration. Small-scale convection also facilitates heating of the slab, which in itself may prolong the residence time of the slab in the transition zone.

Subsurface Constraints on Late Cenozoic Basin Geometry in Northern Fish Lake Valley and Displacement Transfer Along the Northern Fish Lake Valley Fault Zone, Western Nevada

NASA Astrophysics Data System (ADS)

Mueller, N.; Kerstetter, S. R.; Katopody, D. T.; Oldow, J. S.

2016-12-01

The NW-striking, right-oblique Fish Lake Valley fault zone (FLVFZ) forms the northern segment of the longest active structure in the western Great Basin; the Death Valley - Furnace Creek - Fish Lake Valley fault system. Since the mid-Miocene, 50 km of right-lateral displacement is documented on the southern FLVFZ and much of that displacement was and is transferred east and north on active WNW left-lateral faults. Prior to the Pliocene, displacement was transferred east and north on a low-angle detachment. Displacement on the northern part of the FLVFZ continues and is transferred to a fanned array of splays striking (west to east) WNW, NNW, ENE and NNE. To determine the displacement budget on these structures, we conducted a gravity survey to determine subsurface basin morphology and its relation to active faults. Over 2450 stations were collected and combined with existing PACES and proprietary data for a total of 3388 stations. The data were terrain corrected and reduced to a 2.67 g/cm3 density to produce a residual complete Bouguer anomaly. The eastern part of northern Fish Lake Valley is underlain by several prominent gravity lows forming several sub-basins with maximum RCBA values ranging from -24 to -28 mGals. The RCBA was inverted for depth using Geosoft Oasis Montaj GM-SYS 3D modeling software. Density values for the inversion were constrained by lithologic and density logs from wells that penetrate the entire Cenozoic section into the Paleozoic basement. Best fitting gravity measurements taken at the wellheads yielded an effective density of 2.4 g/cm3 for the basin fill. Modeled basement depths range between 2.1 to 3 km. The sub-basins form an arc opening to the NW and are bounded by ENE and NNE faults in the south and NS to NNW in the north. At the northern end of the valley, the faults merge with ENE left-lateral strike slip faults of the Mina deflection, which carries displacement to NW dextral strike-slip faults of the central Walker Lane.

Influence of seep emission on the non-symbiont-bearing fauna and vagrant species at an active giant pockmark in the Gulf of Guinea (Congo-Angola margin)

NASA Astrophysics Data System (ADS)

Olu, K.; Caprais, J. C.; Galéron, J.; Causse, R.; von Cosel, R.; Budzinski, H.; Ménach, K. Le; Roux, C. Le; Levaché, D.; Khripounoff, A.; Sibuet, M.

2009-12-01

Detailed surveying with an ROV found that a dense and diverse cold-seep community colonises a giant pockmark located at 3200 m depth, 8 km north from the deep Congo channel. Several types of assemblages, either dominated by Mytilidae and Vesicomyidae bivalves or Siboglinidae polychaetes, are distributed on the 800-m diameter active area. The site is characterised by a most active central zone in a depression with abundant carbonate concretions and high methane fluxes where high-density clusters of mussels and siboglinids dominate. In contrast, the peripheral zones display large fields of dead and live vesicomyids on soft sediment, with a lower mean density and lower methane concentration in seawater. The associated megafauna includes Alvinocarididae shrimps, echinoids, holothurians of the family Synaptidae, several species of gastropods, two species of galatheids, and Zoarcidae and Ophidiidae fishes. Multivariate analyses of video transect data show that the distribution of these major megafauna species at the pockmark scale is influenced by the habitat heterogeneity due to fluid or gas emission, occurrence of hydrates, substratum variability and by the presence of large symbiont-bearing species. Several assemblages dominated either by mytilids, vesicomyids, or siboglinids have been sampled for megafauna densities and biomass estimations and stable isotope measurements ( δ13C and δ15N) of dominant species and food sources. The highest estimates of megafauna densities have been obtained in mytilid beds. According to their stable isotopes values, non-symbiont-bearing species mainly rely on chemosynthesis-originated carbon, either as primary consumers of chemoautotrophic microorganisms, or at higher trophic level recycling organic matter, or relying on bivalve and tubeworm production. Most of them likely feed on different sources like shrimps, but differences according to habitat have been evidenced. Carbon and nitrogen isotope ratios of galatheids and benthic or benthopelagic fishes captured by trawls at increasing distances from the pockmark provide evidence of the high variability in the proportion of chemosynthesis-originated carbon in their diet, from 15% to 38%, according to the species captured as far as 4 km to the site.

Geospatial Approach on Landslide Hazard Zonation Mapping Using Multicriteria Decision Analysis: A Study on Coonoor and Ooty, Part of Kallar Watershed, The Nilgiris, Tamil Nadu

NASA Astrophysics Data System (ADS)

Rahamana, S. Abdul; Aruchamy, S.; Jegankumar, R.

2014-12-01

Landslides are one of the critical natural phenomena that frequently lead to serious problems in hilly area, resulting to loss of human life and property, as well as causing severe damage to natural resources. The local geology with high degree of slope coupled with high intensity of rainfall along with unplanned human activities of the study area causes many landslides in this region. The present study area is more attracted by tourist throughout the year, so this area must be considered for preventive measures. Geospatial based Multicriteria decision analysis (MCDA) technique is increasingly used for landslide vulnerability and hazard zonation mapping. It enables the integration of different data layers with different levels of uncertainty. In this present study, it is used analytic hierarchy process (AHP) method to prepare landslide hazard zones of the Coonoor and Ooty, part of Kallar watershed, The Nilgiris, Tamil Nadu. The study was carried out using remote sensing data, field surveys and geographic information system (GIS) tools. The ten factors that influence landslide occurrence, such as elevation, slope aspect, slope angle, drainage density, lineament density, soil, precipitation, land use/land cover (LULC), distance from road and NDVI were considered. These factors layers were extracted from the various related spatial data's. These factors were evaluated, and then, the individual factor weight and class weight were assigned to each of the related factors. The Landslide Hazard Zone Index (LHZI) was calculated using Multicriteria decision analysis (MCDA) the technique based on the assigned weight and the rating is given by the Analytical Hierarchy Process (AHP) method. The final cumulative map of the study area was categorized into four hazard zones and classified as zone I to IV. There are 3.56% of the area comes under the hazard zone IV fallowed by 48.19% of the area comes under zone III, 43.63 % of the area in zone II and 4.61% of the area comes hazard zone I. Further resulted hazard zone map and landuse/landcover map are overlaid to check the hazard status, and existing inventory of known landslides within the present study area was compared with the resulting vulnerable and hazard zone maps. The landslide hazard zonation map is useful for landslide hazard prevention, mitigation, and improvement to society, and proper planning for land use and construction in the future.

Atomistic Simulations of Detonation Instabilities in Condensed Phase Systems

NASA Astrophysics Data System (ADS)

Kober, Edward; Heim, Andrew; Germann, Timothy; Jensen, Niels

2007-06-01

We report the results of simulations of condensed phase detonation phenomena using a model diatomic system: 2AB -> A2 + B2. The initial set of parameters for this system corresponded to the Model 0 set of C. White et al, which exhibits a steady, Chapman-Jouget (CJ) detonation structure with a reaction zone length of 30-100 å. This has a highly compressed CJ state (V/V0˜0.5) that does not consist of discrete molecular species. The potential form was modified so that a more molecular CJ state resulted, consistent with the models for conventional organic explosives. The new system has a less dense CJ state (V/V0˜0.8), and the reaction zone was substantially extended. The reaction rate fits Arrhenius-type kinetics with an activation energy of ˜2 eV, with a minor density dependence. In contrast, the original Model 0 system had a lower activation energy (˜1 eV) with a stronger density dependence. The new system exhibits quite marked two dimensional instability structures with well-defined wavelengths similar to what has been observed for gas-phase detonations and for nitromethane. Depending on the exothermicity and the width of the periodic simulations, these instabilities can result in either detonation failure or quasi-steady propagation. The observed propagation velocities are several per cent higher than CJ values derived from thermodynamic analyses.

Starch-based Antimicrobial Films Incorporated with Lauric Acid and Chitosan

NASA Astrophysics Data System (ADS)

Salleh, E.; Muhamad, I. I.

2010-03-01

Antimicrobial (AM) packaging is one of the most promising active packaging systems. Starch-based film is considered an economical material for antimicrobial packaging. This study aimed at the development of food packaging based on wheat starch incorporated with lauric acid and chitosan as antimicrobial agents. The purpose is to restrain or inhibit the growth of spoilage and/or pathogenic microorganisms that are contaminating foods. The antimicrobial effect was tested on B. substilis and E. coli. Inhibition of bacterial growth was examined using two methods, i.e. zone of inhibition test on solid media and liquid culture test (optical density measurements). The control and AM films (incorporated with chitosan and lauric acid) were produced by casting method. From the observations, AM films exhibited inhibitory zones. Interestingly, a wide clear zone on solid media was observed for B. substilis growth inhibition whereas inhibition for E. coli was not as effective as B. substilis. From the liquid culture test, the AM films clearly demonstrated a better inhibition against B. substilis than E. coli.

Timescales and conditions of crystallization in the Pokai and Chimpanzee Ignimbrites, Taupo Volcanic Zone, New Zealand

NASA Astrophysics Data System (ADS)

Connor, M.; Gualda, G. A.; Gravley, D. M.

2013-12-01

Silicic magmas give rise to explosive eruptions that are both of scientific and societal interest. The central Taupo Volcanic Zone in New Zealand has been volcanically active for 2 Ma and represents the most active volcanic area in the world today. Particularly intense volcanic activity took place as part of a flare-up event that occurred from ~340 to ~240 ka, when 7 large ignimbrite eruptions took place, as well as many smaller eruptions, which erupted a total of at least 3000 km3 of magma. This project seeks to identify the conditions and timescales over which magma bodies that gave rise to these ignimbrite eruptions evolved. We aim to understand how much of the tens of thousands of years between successive eruptions were characterized by the presence of large bodies of silicic magma within the crust, as well the magma distribution within the crust during those times. We focus on the Chimpanzee and Pokai ignimbrites, which together erupted ~150 km3 of magma. The Pokai ignimbrite erupted at ~275 ka, while the Chimpanzee ignimbrite (undated) erupted between ~320 and 275 ka. Pumice clasts from the Chimpanzee and Pokai ignimbrite were collected in the field. Pumice bulk densities were measured using a submersion technique. Quartz and plagioclase crystals were extracted through a crushing, sieving, and winnowing procedure. Whole crystals were hand-picked under a conventional microscope, mounted on epoxy, and polished to expose grain interiors. Grain mounts were analyzed under an SEM using back-scattered electron, cathodoluminescence (CL), and energy-dispersive x-ray (EDX) imaging. Bulk-densities vary from 0.42 to 0.81 g/cm3 for Pokai and between 0.52 and 0.64 g/cm3 for Chimpanzee pumice clasts. Plagioclase is the dominant crystal phase in both units. Several plagioclase crystals have inclusions of orthopyroxene, ilmenite, magnetite, and zircon, which in some cases form clusters. Quartz is rare but is present in pumice from both deposits. Both plagioclase and quartz have glass inclusions. Quantitative EDX analyses under the SEM reveal high-silica rhyolite compositions (~78 wt. % SiO2), consistent with crystallization at shallow crustal levels (~100 MPa). Rhyolite-MELTS barometry confirms this suggestion, with estimated crystallization pressures of 70-110 MPa. Such crystallization depths are characteristic of magma bodies that give rise to ignimbrites in the Taupo Volcanic Zone. CL images of a small number of quartz crystals reveal zoning that is variable in character, from unzoned to distinctly zoned. Zoned crystals have several discrete zones, each one with its own characteristic homogeneous brightness; bright CL rims are observed in these crystals. Contacts between zones can be used to calculate crystallization times using diffusional relaxation assuming that CL intensity variations are due to Ti zonation. We estimate that quartz crystallization took place over decades to a few centuries, with rims crystallizing over months to years at most. These short timescales suggest that magma bodies with eruptible magma are very short-lived, much shorter-lived than the 10s of ka repose periods between eruptions that make up the flare-up event.

Assessing Urban Streets Network Vulnerability against Earthquake Using GIS - Case Study: 6TH Zone of Tehran

NASA Astrophysics Data System (ADS)

Rastegar, A.

2017-09-01

Great earthquakes cause huge damages to human life. Street networks vulnerability makes the rescue operation to encounter serious difficulties especially at the first 72 hours after the incident. Today, physical expansion and high density of great cities, due to narrow access roads, large distance from medical care centers and location at areas with high seismic risk, will lead to a perilous and unpredictable situation in case of the earthquake. Zone # 6 of Tehran, with 229,980 population (3.6% of city population) and 20 km2 area (3.2% of city area), is one of the main municipal zones of Tehran (Iran center of statistics, 2006). Major land-uses, like ministries, embassies, universities, general hospitals and medical centers, big financial firms and so on, manifest the high importance of this region on local and national scale. In this paper, by employing indexes such as access to medical centers, street inclusion, building and population density, land-use, PGA and building quality, vulnerability degree of street networks in zone #6 against the earthquake is calculated through overlaying maps and data in combination with IHWP method and GIS. This article concludes that buildings alongside the streets with high population and building density, low building quality, far to rescue centers and high level of inclusion represent high rate of vulnerability, compared with other buildings. Also, by moving on from north to south of the zone, the vulnerability increases. Likewise, highways and streets with substantial width and low building and population density hold little values of vulnerability.

Mapping of groundwater potential zones in Salem Chalk Hills, Tamil Nadu, India, using remote sensing and GIS techniques.

PubMed

Thilagavathi, N; Subramani, T; Suresh, M; Karunanidhi, D

2015-04-01

This study proposes to introduce the remote sensing and geographic information system (GIS) techniques in mapping the groundwater potential zones. Remote sensing and GIS techniques have been used to map the groundwater potential zones in Salem Chalk Hills, Tamil Nadu, India. Charnockites and fissile hornblende biotite gneiss are the major rock types in this region. Dunites and peridodites are the ultramafic rocks which cut across the foliation planes of the gneisses and are highly weathered. It comprises magnesite and chromite deposits which are excavated by five mining companies by adopting bench mining. The thickness of weathered and fracture zone varies from 2.2 to 50 m in gneissic formation and 5.8 to 55 m in charnockite. At the contacts of gneiss and charnockite, the thickness ranges from 9.0 to 90.8 m favoring good groundwater potential. The mine lease area is underlined by fractured and sheared hornblende biotite gneiss where groundwater potential is good. Water catchment tanks in this area of 5 km radius are small to moderate in size and are only seasonal. They remain dry during summer seasons. As perennial water resources are remote, the domestic and agricultural activities in this region depend mainly upon the groundwater resources. The mines are located in gently slope area, and accumulation of water is not observed except in mine pits even during the monsoon period. Therefore, it is essential to map the groundwater potential zones for proper management of the aquifer system. Satellite imageries were also used to extract lineaments, hydrogeomorphic landforms, drainage patterns, and land use, which are the major controlling factors for the occurrence of groundwater. Various thematic layers pertaining to groundwater existence such as geology, geomorphology, land use/land cover, lineament, lineament density, drainage, drainage density, slope, and soil were generated using GIS tools. By integrating all the above thematic layers based on the ranks and weightages, eventually groundwater potential zones were demarcated. The study indicates that groundwater potential is good to high in 22 villages and moderate in 13 villages. The good to high potential zone occupies an area of 128 km2 and moderate potential zone occupies an area of 77 km2. Groundwater occurrence is poor in five villages which need artificial recharge to augment groundwater.

Forcing of the Coupled Ionosphere-Thermosphere (IT) System During Magnetic Storms

NASA Technical Reports Server (NTRS)

Huang, Cheryl; Huang, Yanshi; Su, Yi-Jiun; Sutton, Eric; Hairston, Marc; Coley, W. Robin; Doornbos, Eelco; Zhang, Yongliang

2014-01-01

Poynting flux shows peaks around auroral zone AND inside polar cap. Energy enters IT system at all local times in polar cap. Track-integrated flux at DMSP often peaks at polar latitudes- probably due to increased area of polar cap during storm main phases. center dot lon temperatures at DMSP show large increases in polar region at all local times; cusp and auroral zones do not show distinctively high Ti. center dot I on temperatures in the polar cap are higher than in the auroral zones during quiet times. center dot Neutral densities at GRACE and GOCE show maxima at polar latitudes without clear auroral signatures. Response is fast, minutes from onset to density peaks. center dot GUVI observations of O/N2 ratio during storms show similar response as direct measurements of ion and neutral densities, i.e. high temperatures in polar cap during prestorm quiet period, heating proceeding from polar cap to lower latitudes during storm main phase. center dot Discrepancy between maps of Poynting flux and of ion temperatures/neutral densities suggests that connection between Poynting flux and Joule heating is not simple.

Application of active quenching of second generation wire for current limiting

DOE PAGES

Solovyov, Vyacheslav F.; Li, Qiang

2015-10-19

Superconducting fault current limiters (SFCL's) are increasingly implemented in the power grid as a protection of substation equipment from fault currents. Resistive SFCL's are compact and light, however they are passively triggered and thus may not be sufficiently sensitive to respond to faults in the distribution grid. Here, we explore the prospect of adding an active management feature to a traditional resistive SFCL. A flexible radio-frequency coil, which is an integral part of the switching structure, acts as a triggering device. We show that the application of a short, 10 ms, burst of ac magnetic field during the fault triggersmore » a uniform quench of the wire and significantly reduces the reaction time of the wire at low currents. The ac field burst generates a high density of normal zones, which merge into a continuous resistive region at a rate much faster than that of sparse normal zones created by the transport current alone.« less

Turbulence and wave particle interactions in solar-terrestrial plasmas

NASA Technical Reports Server (NTRS)

Dulk, G. A.; Goldman, M. V.; Toomre, J.

1985-01-01

Activities in the following study areas are reported: (1) particle and wave processes in solar flares; (2) solar convection zone turbulence; and (3) solar radiation emission. To investigate the amplification of cyclotron maser radiation in solar flares, a radio frequency. (RF) heating model was developed for the corona surrounding the energy release site. Then nonlinear simulations of compressible convection display prominent penetration by plumes into regions of stable stratification at the base of the solar convection zone, leading to the excitation of internal gravity waves there. Lastly, linear saturation of electron-beam-driven Langmuir waves by ambient density fluctuations, nonlinear saturation by strong turbulence processes, and radiation emission mechanisms are examined. An additional section discusses solar magnetic fields and hydromagnetic waves in inhomogeneous media, and the effect of magnetic fields on stellar oscillation.

Petroleum hydrocarbon pollution of urban topsoil in Ibadan city, Nigeria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Onianwa, P.C.

The distribution of total petroleum hydrocarbon in topsoils from various parts of Ibadan city, Nigeria, was studied. Samples were selected from around the following zones: (a) railway tracks, (b) petrol stations, (c) refuse dumps, (d) residential areas, (e) high traffic density areas, (f) mechanical workshops, and (g) control zones. Contamination of the topsoil with hydrocarbons was significant only around petrol stations and mechanical workshops where the factors of accumulation were 10.1 and 4.72, respectively. The general trend in hydrocarbon levels was petrol station > mechanical workshop > refuse dumps > high traffic areas {ge} rail tracks > control residential areas.more » The results highlight the need to monitor urban environments that are remote from petroleum exploration activities for petroleum hydrocarbon contamination. 19 refs., 3 tabs.« less

Morphology, spatial pattern and sediment of Nitraria tangutorum nebkhas in barchans interdune areas at the southeast margin of the Badain Jaran Desert, China

NASA Astrophysics Data System (ADS)

Yang, YanYan; Liu, LianYou; Shi, PeiJun; Zhang, GuoMing; Qu, ZhiQiang; Tang, Yan; Lei, Jie; Wen, HaiMing; Xiong, YiYing; Wang, JingPu; Shen, LingLing

2015-03-01

To understand the characteristics of the nebkhas in barchan interdune areas, isolated barchan dunes at the southeast margin of the Badain Jaran Desert in China and Nitraria tangutorun nebkhas in the interdune areas were selected, and the morphometric parameters, spatial patterns, and granulometric characteristics of the nebkhas in various interdune zones were compared. According to the locations relative to barchan dunes, the interdune areas were divided into three zones: the windward interdune zone (Zw), the leeward interdune zone (Zl), and the horn interdune zone (Zh). The zone that is proximal to barchan dunes and has never been disturbed by barchan dunes was also selected (Zi). The morphometric parameters were measured through a satellite image and field investigation. The population density and spatial patterns were analyzed using the satellite image, and surface sediment samples of the nebkhas and barchan dunes were collected for grain size analysis. The morphometric parameters of Nitraria tangutorun nebkhas in the interdune zones differ significantly. The nebkhas in Zh are larger than those observed in the other zones, and the nebkhas are the smallest in Zl. In all of the zones, the long-axis orientation of the nebkhas is perpendicular to the prevailing wind direction. The population density of the nebkhas in Zw is relatively higher, whereas the density in Zh and Zl becomes obviously lower. The spatial distribution of nebkhas in all of the zones can be categorized as a dispersed pattern. The sediments of the nebkhas are coarsest in Zh and finest in Zl. In addition, the sediments of the nebkhas in all of the zones are finer than those of barchan dunes. The amount of sand captured by the nebkhas in the interdune areas is approximately 20% of the volume of barchan dunes. The variations of the nebkhas' sizes, spatial pattern and sediment are subjected to migration, flow field and sand transport of barchan dunes and sand accumulation with plant growth in the interdune areas, which suggest complex mutual interactions between barchan dunes and the nebkhas in the interdune areas.

Presynaptic active zones of mammalian neuromuscular junctions: Nanoarchitecture and selective impairments in aging.

PubMed

Badawi, Yomna; Nishimune, Hiroshi

2018-02-01

Neurotransmitter release occurs at active zones, which are specialized regions of the presynaptic membrane. A dense collection of proteins at the active zone provides a platform for molecular interactions that promote recruitment, docking, and priming of synaptic vesicles. At mammalian neuromuscular junctions (NMJs), muscle-derived laminin β2 interacts with presynaptic voltage-gated calcium channels to organize active zones. The molecular architecture of presynaptic active zones has been revealed using super-resolution microscopy techniques that combine nanoscale resolution and multiple molecular identification. Interestingly, the active zones of adult NMJs are not stable structures and thus become impaired during aging due to the selective degeneration of specific active zone proteins. This review will discuss recent progress in the understanding of active zone nanoarchitecture and the mechanisms underlying active zone organization in mammalian NMJs. Furthermore, we will summarize the age-related degeneration of active zones at NMJs, and the role of exercise in maintaining active zones. Copyright © 2017 Elsevier Ireland Ltd and Japan Neuroscience Society. All rights reserved.

Gravity anomaly and crustal structure characteristics in North-South Seismic Belt of China

NASA Astrophysics Data System (ADS)

Shen, Chongyang; Xuan, Songtbai; Yang, Guangliang; Wu, Guiju

2017-04-01

The North-South Seismic Belt (NSSB) is the binary system boundary what is formed by the western Indian plate subduction pushing and the eastern west Pacific asthenosphere rising, and it is one of the three major seismic belts (Tianshan, Taiwan and NSSB) and mainly located between E102°and E107°. And it is mainly composed of topographic gradient zones, faults, cenozoic basins and strong earthquake zones, which form two distinct parts of tectonic and physical features in the west and east. The research results of geophysical and deep tectonic setting in the NSSB show that it is not only a gravity anomaly gradient zone, it is but also a belt of crustal thickness increasing sharply westward of abrupt change. Seismic tomography results show that the anomaly zone is deeper than hundreds of kilometers in the NSSB, and the composition and structure of the crust are more complex. We deployed multiple Gravity and GNSS synchronous detection profiles in the NSSB, and these profiles crossed the mainly faults structure and got thousands of points data. In the research, source analysis, density structure inversion, residual gravity related imaging and normalized full gradient methods were used, and analyzed gravity field, density and their structure features in different positions, finally obtained the crustal density structure section characteristics and depth structure differences. The research results showed that the gravity Bouguer anomaly is similar to the existing large scale result. The Bouguer anomaly is rising significantly from west to east, its trend variation coincides well with the trend change of Moho depth, which is agreeing with the material flows to the peripheral situation of the Tibetan plateau. The obvious difference changes of the residual anomaly is relative to the boundary of structure or main tectonics, it's also connected with the stop degree of the eurasian plate when the material migrates around. The density structure of the gravity profiles mainly reflects basic frame work of the regional crust structure. The earth's crust basically present three layer structure, nearly horizontally distributes, undulation of Moho is obvious, which is consistent with the results of seismic sounding and seismic array detection; in the local area, there are lower density layer zonal distribution in the earth's crust what accelerates the lateral movement in up and middle crust; when the substance of the Tibetan plateau spreads around, the integrity in up and middle crust is well, and it is basically a coupling movement together; in the lower crust, the thickness of the Tibetan plateau is outward gradually thinning, there is decoupling phenomenon in crust-mantle; The results of the gravity and the crustal density structure show that the research area can be divided into several part such as Qinghai-Tibet Plateau, Sichuan-Yunnan block, Ordos block and Alxa block, the transitional zones of the Qinghai-Tibet Plateau and Sichuan basin, and Alxa and Ordos are complex, and Moho slope is bigger, where is the part of strong tectonic activity and strong earthquakes occur easily. The research is of great significance for study the crustal deep structure, geodynamic evolution process and environment of earthquake gestation of the NSSB region.

Phytoplankton variation and its relation to nutrients and allochthonous organic matter in a coastal lagoon on the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Aké-Castillo, José A.; Vázquez, Gabriela

2008-07-01

In tropical and subtropical zones, coastal lagoons are surrounded by mangrove communities which are a source of high quantity organic matter that enters the aquatic system through litter fall. This organic matter decomposes, becoming a source of nutrients and other substances such as tannins, fulvic acids and humic acids that may affect the composition and productivity of phytoplankton communities. Sontecomapan is a coastal lagoon located in the southern Gulf of Mexico, which receives abundant litter fall from mangrove. To study the phytoplankton composition and its variation in this lagoon from October 2002 to October 2003, we evaluated the concentrations of dissolved folin phenol active substances (FPAS) as a measure of plant organic matter, salinity, temperature, pH, O 2, N-NH 4+, N-NO 3-, P-PO 43-, Si-SiO 2, and phytoplanktonic cell density in different mangrove influence zones including the three main rivers that feed the lagoon. Nutrients concentrations depended on freshwater from rivers, however these varied seasonally. Concentrations of P-PO 43-, N-NH 4+ and FPAS were the highest in the dry season, when maximum mangrove litter fall is reported. Variation of these nutrients seemed to depend on the internal biogeochemical processes of the lagoon. Blooms of diatoms ( Skeletonema spp., Cyclotella spp. and Chaetoceros holsaticus) and dinoflagellates ( Peridinium aff. quinquecorne, Prorocentrum cordatum) occurred seasonally and in the different mangrove influence zones. The high cell densities in these zones and the occurrence of certain species and its ordination along gradient of FPAS in a canonical correspondence analysis, suggest that plant organic matter (i.e. mangrove influence) may contribute to phytoplankton dynamics in Sontecomapan lagoon.

Late summer metalimnetic oxygen minimum zone in the northern Baltic Sea

NASA Astrophysics Data System (ADS)

Raateoja, M.; Kuosa, H.; Flinkman, J.; Pääkkönen, J.-P.; Perttilä, M.

2010-02-01

The frequently observed, but commonly ignored hydrographic characteristic of the Baltic Sea, the oxygen minimum zone (OMiZ) above and within the summertime thermocline, was studied during the 6-yr monitoring programme encompassing the Gulfs of Bothnia and Finland in the northern Baltic Sea. A temperature-anomaly-driven density gradient was found to be a prerequisite for the existence of the OMiZ. We determined the magnitude of the apparently utilized O 2 in the OMiZ by combining graphical analysis and empirical modelling. A sound criterion for distinguishing the cases in which the OMiZ had a biological origin, and not only a hydrodynamic one, was the accompanying ammonium maximum zone (AMaZ). Of a total of 46 stations visited, a density gradient was found at every station, an accompanying OMiZ at 37 stations, and an accompanying AMaZ at 20 stations. This suggests that biological activity is an essential factor in forming the OMiZ. We investigated to what extent the OMiZ was a manifestation of microbial decomposition of autochthonous organic matter, as zooplankton respiration was also a factor. As a study average, ~ 80% of the apparently utilized O 2 was consumed by the microbial decomposition process and ~ 20% of it by mesozooplankton respiration. According to the O 2 quota consumed in the process, the microbial community in the OMiZ of the Gulf of Finland decomposed, on average, 14% of all the organic matter settling from the euphotic zone in the time frame of mid-June to early August. A pronounced allochthonous organic carbon pool in the Gulf of Bothnia hinders a prompt estimation of a corresponding share for that basin.

Seismic refraction studies of volcanic crust in Costa Rica and of critical zones in the southern Sierra Nevada, California and Laramie Range, Wyoming

NASA Astrophysics Data System (ADS)

Hayes, Jorden L.

This work demonstrates the utility of seismic refraction surveys to understanding geologic processes at a range of scales. Each chapter presents subsurface maps of seismic p-wave velocities, which vary due to contrasts in elastic material properties. In the following chapters we examine seismic p-wave velocity variations that result from volcanic and tectonic processes within Earth's crust and chemical and physical weathering processes within Earth's near-surface environment. Chapter one presents results from an across-arc wide-angle seismic refraction survey of the Costa Rican volcanic front. These results support the hypothesis that juvenile continental crust may form along volcanic island arcs if built upon relatively thick substrates (i.e., large igneous provinces). Comparisons of velocity-depth functions show that velocities within the active arc of Costa Rica are lower than other modern island arcs (i.e., volcanic arcs built upon oceanic crust) and within the high-velocity extreme of bulk continental crust. Chapter two shows that physical processes can dominate over chemical processes in generating porosity in the deep critical zone and outlines a new framework for interpreting subsurface chemical and physical weathering at the landscape scale. Direct measurements of saprolite from boreholes at the Southern Sierra Nevada Critical Zone Observatory show that, contrary to convention, saprolite may experience high levels of volumetric strain (>35%) and uniform mass loss in the upper 11 m. By combining observations from boreholes and seismic refraction surveys we create a map of volumetric strain across the landscape. Variations in inferred volumetric strain are consistent with opening-mode fracture patterns predicted by topographic and tectonic stress models. Chapter three is a characterization of fracture distribution in the deep critical zone from geophysical and borehole observations in the Laramie Mountains, Wyoming. Data from core and down-hole acoustic televiewer images show that fracture density not only decreases with depth but also varies with topography. Comparisons of seismic p-wave velocities and fracture density show that increases in seismic velocity at our site (i.e., from 1-4 km/s) correspond to decreasing fracture density. Observations of a seismological boundary layer coupled with weathering interpreted in borehole images suggest a significant change in chemical weathering with depth. These results emphasize the complex interplay of chemical and physical processes in the deep critical zone.

Marine Litter Distribution and Density in European Seas, from the Shelves to Deep Basins

PubMed Central

Pham, Christopher K.; Ramirez-Llodra, Eva; Alt, Claudia H. S.; Amaro, Teresa; Bergmann, Melanie; Canals, Miquel; Company, Joan B.; Davies, Jaime; Duineveld, Gerard; Galgani, François; Howell, Kerry L.; Huvenne, Veerle A. I.; Isidro, Eduardo; Jones, Daniel O. B.; Lastras, Galderic; Morato, Telmo; Gomes-Pereira, José Nuno; Purser, Autun; Stewart, Heather; Tojeira, Inês; Tubau, Xavier; Van Rooij, David; Tyler, Paul A.

2014-01-01

Anthropogenic litter is present in all marine habitats, from beaches to the most remote points in the oceans. On the seafloor, marine litter, particularly plastic, can accumulate in high densities with deleterious consequences for its inhabitants. Yet, because of the high cost involved with sampling the seafloor, no large-scale assessment of distribution patterns was available to date. Here, we present data on litter distribution and density collected during 588 video and trawl surveys across 32 sites in European waters. We found litter to be present in the deepest areas and at locations as remote from land as the Charlie-Gibbs Fracture Zone across the Mid-Atlantic Ridge. The highest litter density occurs in submarine canyons, whilst the lowest density can be found on continental shelves and on ocean ridges. Plastic was the most prevalent litter item found on the seafloor. Litter from fishing activities (derelict fishing lines and nets) was particularly common on seamounts, banks, mounds and ocean ridges. Our results highlight the extent of the problem and the need for action to prevent increasing accumulation of litter in marine environments. PMID:24788771

Investigation of physical processes limiting plasma density in H-mode on DIII-D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maingi, R.; Mahdavi, M.A.; Jernigan, T.C.

1996-12-01

A series of experiments was conducted on the DIII-D tokamak to investigate the physical processes which limit density in high confinement mode (H-mode) discharges. The typical H-mode to low confinement mode (L-mode) transition limit at high density near the empirical Greenwald density limit was avoided by divertor pumping, which reduced divertor neutral pressure and prevented formation of a high density, intense radiation zone (MARFE) near the X-point. It was determined that the density decay time after pellet injection was independent of density relative to the Greenwald limit and increased non-linearly with the plasma current. Magnetohydrodynamic (MHD) activity in pellet-fueled plasmasmore » was observed at all power levels, and often caused unacceptable confinement degradation, except when the neutral beam injected (NBI) power was {le} 3 MW. Formation of MARFEs on closed field lines was avoided with low safety factor (q) operation but was observed at high q, qualitatively consistent with theory. By using pellet fueling and optimizing discharge parameters to avoid each of these limits, an operational space was accessed in which density {approximately} 1.5 {times} Greenwald limit was achieved for 600 ms, and good H-mode confinement was maintained for 300 ms of the density flattop. More significantly, the density was successfully increased to the limit where a central radiative collapse was observed, the most fundamental density limit in tokamaks.« less

Meiofauna as descriptor of tourism-induced changes at sandy beaches.

PubMed

Gheskiere, Tom; Vincx, Magda; Weslawski, Jan Marcin; Scapini, Felicita; Degraer, Steven

2005-08-01

Tourism has long been considered as a 'clean industry' with almost no negative effects on the environment. This study demonstrated, in two different coastal systems (Mediterranean and Baltic), that tourism related activities are particularly affecting the sandy beach meio- and nematofauna in the upper beach zone, the specific ecotone in which many meiofauna species from both the marine and the terrestrial environment congregate. Tourist upper beaches are characterized by a lower % total organic matter (%TOM), lower densities, lower diversities (absence of Insecta, Harpacticoida, Oligochaeta, terrestrial nematodes and marine Ironidae nematodes) and higher community stress compared to nearby non-tourist locations. The %TOM was found to be the single most important factor for the observed differences in meiofauna assemblage structure at tourist versus non-tourist beaches in both the Mediterranean and the Baltic region. The free-living nematode assemblages from tourist upper zones depart significantly from expectations based on random selections from the regional nematode species pool. Furthermore upper zone assemblages are characterised by a low species diversity consisting of taxonomically closely related nematode species with r-strategist features. Generally, faunal differences between tourist and non-tourist beaches are decreasing towards the lower beach zones.

The seasonal succession of zooplankton in the Southern Ocean south of Australia, part II: The Sub-Antarctic to Polar Frontal Zones

NASA Astrophysics Data System (ADS)

Hunt, Brian P. V.; Hosie, Graham W.

2006-07-01

Between October 2001 and March 2002 six transects were completed at monthly intervals in the Sub-Antarctic Zone (SAZ) and Inter-Sub-Antarctic Front Zone (ISAFZ)/Polar Frontal Zone (PFZ) in the Southern Ocean south of Australia. Zooplankton were collected with a Continuous Plankton Recorder and NORPAC net and multivariate analysis was used to analyse the seasonal succession of communities. Despite strong, seasonally consistent, biogeographic differences between the SAZ and ISAFZ/PFZ, community structure in all zones was dominated by a suite of common taxa. These included the ubiquitous Oithona similis, foraminiferans and appendicularians (Core taxa), occurring in >97% of samples and contributing an average of 75% to total sample abundance, and Calanus simillimus, Rhincalanus gigas, Ctenocalanus citer, Clausocalanus brevipes, Clausocalanus laticeps, Oithona frigida, Limacina spp. and chaetognaths (Summer taxa), present in >57% of samples and occurring at seasonally high densities. Because of the dominance of the Core and Summer taxa, the seasonal succession was most clearly evident as a change in zooplankton densities. In October densities averaged <15 ind m -3, rising to 52 ind m -3 (max=92 ind m -3) in November, and subsequently increasing slowly through to January (ave=115 ind m -3; max=255 ind m -3). Densities peaked abruptly in February (ave=634 ind m -3; max=1593 ind m -3), and remained relatively high in March (ave=193 ind m -3; max=789 ind m -3). A latitudinal lag in seasonal development was observed with peak densities occurring first in the SAZ (February) and then in the ISAFZ/PFZ (March). The seasonal community succession was strongly influenced by species population cycles. The role of zooplankton in biogeochemical cycling in the SAZ and ISAFZ/PFZ was discussed in the light of past sediment trap data collected from the study area.

THE RELATIONSHIP BETWEEN FOVEAL AVASCULAR ZONE AREA, VESSEL DENSITY, AND CYSTOID CHANGES IN DIABETIC RETINOPATHY, AN OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY STUDY.

PubMed

Tarassoly, Kia; Miraftabi, Arezoo; Soltan Sanjari, Mostafa; Parvaresh, Mohammad Mehdi

2017-06-29

To measure the foveal avascular zone (FAZ) areas and vessel densities of patients with diabetic retinopathy and to study their relationship with diabetic cystoid changes and retinal thickness. Prospective case series of 51 eyes of 31 patients with diabetic retinopathy. The eyes were grouped based on the presence or absence of cystoid edema and evaluated using optical coherence tomography angiography. The FAZ areas and vessel density were compared. The FAZ area at the superficial capillary plexus level was equal between the eyes with and without cystoid edema. Vessel density did not differ as well. There was no correlation with retinal thickness. In eyes with cystoid changes, FAZ area changes at the deep capillary plexus level were difficult to interpret. The FAZ area and vessel density at the superficial capillary plexus level are reproducible and independent of the presence of cystoid edema.

Imprint of Southern Red Sea Major Tectonic Zone In A New Bouguer Anomaly Map of Southern Yemen Margin

NASA Astrophysics Data System (ADS)

Blecha, V.

A new Bouguer anomaly map of western part of southern Yemen margin has been compiled. Densities of rock samples from main geological units (Precambrian base- ment, Mesozoic sediments, Tertiary volcanites) have been measured and used for grav- ity modeling. Regional gravity map indicates decrease of thickness of continental crust from volcanites of the Yemen Trap Series towards the coast of the Gulf of Aden. Most remarkable feature in the map of residual anomalies is a positive anomaly over the Dhala graben. The Dhala graben is a prominent geological structure in the area of study trending parallel to the Red Sea axis. Gravity modeling on a profile across the Dhala graben presumes intrusive plutonic rocks beneath the graben. There are two other areas in the southwestern tip of Arabia, which have essentially the same struc- tural position as the Dhala graben: the Jabal Tirf volcanic rift zone in the southern Saudi Arabia and Jabal Hufash extensional zone in northern Yemen. All three areas extend along the line trending parallel to the Red Sea axis with length of about 500 km. The line coincides with the axis of Afar (Danakil) depression after Arabia is shifted and rotated back to Africa. These facts imply conclusion that the Oligocene - Early Miocene magmatic activity on the Jabal Tirf - Dhala lineament is related to the same original deep tectonic zone, forming present-day Afar depression and still active.

Structural analysis characterization of permeability pathways across reservoir-seal interface - South-Eastern Utah; Results from integrated sedimentological, structural, and geochemical studies.

NASA Astrophysics Data System (ADS)

Petrie, E. S.; Evans, J. P.; Richey, D.; Flores, S.; Barton, C.; Mozley, P.

2015-12-01

Sedimentary rocks in the San Rafael Swell, Utah, were deformed by Laramide compression and subsequent Neogene extension. We evaluate the effect of fault damage zone morphology as a function of structural position, and changes in mechanical stratigraphy on the distribution of secondary minerals across the reservoir-seal pair of the Navajo Sandstone and overlying Carmel Formation. We decipher paleo-fluid migration and examine the effect faults and fractures have on reservoir permeability and efficacy of top seal for a range of geo-engineering applications. Map-scale faults have an increased probability of allowing upward migration of fluids along the fault plane and within the damage zone, potentially bypassing the top seal. Field mapping, mesoscopic structural analyses, petrography, and geochemical observations demonstrate that fault zone thickness increases at structural intersections, fault relay zones, fault-related folds, and fault tips. Higher densities of faults with meters of slip and dense fracture populations are present in relay zones relative to single, discrete faults. Curvature analysis of the San Rafael monocline and fracture density data show that fracture density is highest where curvature is highest in the syncline hinge and near faults. Fractures cross the reservoir-seal interface where fracture density is highest and structural diagensis includes mineralization events and bleaching and calcite and gypsum mineralization. The link between fracture distributions and structural setting implys that transmissive fractures have predictable orientations and density distributions. At the m- to cm- scale, deformation-band faults and joints in the Navajo Sandstone penetrate the reservoir-seal interface and transition into open-mode fractures in the caprock seal. Scanline analysis and petrography of veins provide evidence for subsurface mineralization and fracture reactivation, suggesting that the fractures act as loci for fluid flow through time. Heterolithic caprock seals with variable fracture distributions and morphology highlight the strong link between the variation in material properties and the response to changing stress conditions. The variable connectivity of fractures and the changes in fracture density plays a critical role in subsurface fluid flow.

Importance of atomic oxygen in preheating zone in plasma-assisted combustion of a steady-state premixed burner flame

NASA Astrophysics Data System (ADS)

Zaima, K.; Akashi, H.; Sasaki, K.

2015-09-01

It is widely believed that electron impact processes play essential roles in plasma-assisted combustion. However, the concrete roles of high-energy electrons have not been fully understood yet. In this work, we examined the density of atomic oxygen in a premixed burner flame with the superposition of dielectric barrier discharge (DBD). The density of atomic oxygen in the reaction zone was not affected by the superposition of DBD, indicating that the amount of atomic oxygen produced by combustion reactions was much larger than that produced by electron impact processes. On the other hand, in the preheating zone, we observed high-frequency oscillation of the density of atomic oxygen at the timings of the pulsed current of DBD. The oscillation suggests the rapid consumption of additional atomic oxygen by combustion reactions. A numerical simulation using Chemkin indicates the shortened ignition delay time when adding additional atomic oxygen in the period of low-temperature oxidation. The present results reveals the importance of atomic oxygen, which is produced by the effect of high-energy electrons, in the preheating zone in plasma-assisted combustion of the steady-state premixed burner flame.

Diet, dietary selectivity and density of South American grey fox, Lycalopex griseus, in Central Chile.

PubMed

Muñoz-Pedreros, Andrés; Yáñez, José; Norambuena, Heraldo V; Zúñiga, Alfredo

2018-01-01

The South American grey fox Lycalopex griseus is a canid widely distributed in southern South America; however, some aspects of its biology are still poorly known. We studied the diet and density of L. griseus in the Lago Peñuelas Biosphere Reserve, in Central Chile. The trophic niche breadth was B = 6.16 (B sta = 0.47) and prey diversity was H' = 2.46 (H max ' = 3.17, J' = 0.78). The highest proportions of prey consumed in the diet were Oryctolagus cuniculus (52.21%) and other mammals (32.78%). We compared these results with a latitudinal gradient of diet results for this species in Chile. L. griseus eats mostly mammals (>90% of total prey), consuming the rodent Phyllotis darwini and reptiles in the northern zone; Oryctolagus cuniculus, Octodon degus and Abrocoma bennetti in the central zone; Abrothrix spp. and lagomorphs in the southern zone; and Lepus capensis and Ovis aries in the austral zone. The estimated density of L. griseus in Lago Peñuelas NR was 1.3 foxes/km 2 . © 2017 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

A combined magnetometry and gravity study across Zagros orogeny in Iran

NASA Astrophysics Data System (ADS)

Abedi, Maysam; Oskooi, Behrooz

2015-11-01

In this work, the structural geology and the tectonic conditions of the Zagros orogeny along the route of Qom to Kermanshah cities were investigated using the combined geophysical methods of the airborne magnetometry and the ground-based gravity data. Airborne magnetometry data of Iran with a line space of survey, 7.5 km, were used to model the magnetic susceptibility property along the route. At first, the airborne magnetic data were stably 500-m downward continued to the ground surface in order to enhance minor changes of the Earth's magnetic field over the studied region. Afterward, 3D inverse modeling of the magnetic data was implemented to the downward continued data, and subsequently the section of magnetic susceptibility variation along the desired route was extracted and imaged at depth. The acquired model could appropriately predict the observed magnetic data, showing low misfit values between the observation and the predicted data. The analytic signal filter was applied to the reduced-to-pole (RTP) magnetic data leading to the determination of the active and probable hidden faults in the structural zones of the Zagros, such as Sanandaj-Sirjan, Central Domain (CD) and Urumieh-Dokhtar based upon the generated peaks along the profile of analytic signal filter. In addition, the density variations of the subsurface geological layers were determined by 3D inverting of the ground-based gravity data over the whole study area, and extracting this property along the route. The joint models of magnetic susceptibility and density variation could appropriately localize the traces of faults along with the geologically and tectonically structural boundaries in the region. The locations of faults correspond well to the variation of geophysical parameters on the inverted sections. Probable direction, slope and extension at depth of these faults were also determined on the sections, indicating a high tectonized zone of the Sanandaj-Sirjan Zone (SSZ) parallel to the zone of the Urumieh-Dokhtar Magmatic Assemblage (UDMA). The UDMA zone increases the magnetic and the Bouguer anomalies by intruding into the CD zone as well.

Irradiation stratigraphy and depositional history of the Apollo 16 double drive tube 60009/10

NASA Technical Reports Server (NTRS)

Blanford, G. E.; Blanford, J.; Hawkins, J. A.

1979-01-01

We report track density frequency distributions, the fraction of high density grains and minimum track densities for 63, 1 mm wide locations in the Apollo 16 double drive tube 60009/10. From these data we conclude that there are seven irradiation strata in the core. Only one buried reworking zone extending from 50-52 cm was found and it was exposed near the surface from 4.5-9 times 10 to the 6th y with a most probable exposure period of 6 times 10 to the 6th y. There is lack of conclusive data that this zone represents a reworking zone in which case the material below 52 cm most probably was exposed in situ for 4.5 times 10 to the 6th y and developed a reworking zone approximately less than 0.5 cm. The present surface of the core has a reworking zone of 12-13 cm which was exposed from 1.3 times 10 to the 7th to 2.5 times 10 to the 8th y. The best estimate for this exposure period remains the value of approximately less than 1.25 times 10 to the 8th y determined by Bogard and Hirsch (1976). The other strata in the core appear to contain mixtures of various soil types and are not related to in situ depositional events.

Impacts of blending on dilution of negatively buoyant brine discharge in a shallow tidal sea.

PubMed

Kämpf, Jochen

2009-07-01

A fine-resolution three-dimensional hydrodynamic model is applied to study the dilution of desalination brine discharged into a tidal sea. Based on given inflow rate and salinity excess of discharge brine, this study explores variations in mid-field dilutions when other low-salinity wastewater is added to the discharge. Findings reveal that this blending leads to a decrease in dilution in the mixing zone and therefore to higher levels of pollutants in this zone, while, on the other hand, the mixing zone occupies a smaller area. The reason is that the discharge of brine creates a density-driven flow that operates to partially remove effluent from the discharge location. This removal is less efficient for the decrease in density excess of the discharge. Hence, in an ambient sea of moderate mixing, blending can be expected to increase the risk of marine pollution in the mixing zone.

Brittle fracture damage around the Alpine Fault, New Zealand

NASA Astrophysics Data System (ADS)

Williams, J. N.; Toy, V.; Smith, S. A. F.; Boulton, C. J.; Massiot, C.; Mcnamara, D. D.

2017-12-01

We use field and drill-core samples to characterize macro- to micro-scale brittle fracture networks within the hanging-wall of New Zealand's Alpine Fault, an active plate-boundary fault that is approaching the end of its seismic cycle. Fracture density in the hanging-wall is roughly constant for distances of up to 500 m from the principal slip zone gouges (PSZs). Fractures >160 m from the PSZs are typically open and parallel to the regional mylonitic foliation or host rock schistosity, and likely formed as unloading joints during rapid exhumation of the hanging-wall at shallow depths. Fractures within c. 160 m of the PSZs are broadly oriented shear-fractures filled with gouge or cataclasite, and are interpreted to constitute the hanging-wall damage zone of the Alpine Fault. This is comparable to the 60-200 m wide "geophysical damage zone" estimated from low seismic wave velocities surrounding the Alpine Fault. Veins are pervasive within the c. 20 m-thick hanging-wall cataclasites and are most commonly filled by calcite, chlorite, muscovite and K-feldspar. Notably, there is a set of intragranular clast-hosted veins, as well as a younger set of veins that cross-cut both clasts and cataclasite matrix. The intragranular veins formed prior to cataclasis or during synchronous cataclasis and calcite-silicate mineralisation. Broad estimates for the depth of vein formation indicate that the cataclasites formed a c. 20 m wide actively deforming zone at depths of c. 4-8 km. Conversely, the cross-cutting veins are interpreted to represent off-fault damage within relatively indurated cataclasites following slip localization onto the <10 cm wide smectite-bearing PSZ gouges at depths of <4 km. Our observations therefore highlight a strong depth-dependence of the width of the actively deforming zone within the brittle seismogenic crust around the Alpine Fault.

Co-Occurrence and Habitat Use of Fin Whales, Striped Dolphins and Atlantic Bluefin Tuna in the Northwestern Mediterranean Sea

PubMed Central

Bauer, Robert Klaus; Demarcq, Hervé; Brisset, Blandine

2015-01-01

Different dolphin and tuna species have frequently been reported to aggregate in areas of high frontal activity, sometimes developing close multi-species associations to increase feeding success. Aerial surveys are a common tool to monitor the density and abundance of marine mammals, and have recently become a focus in the search for methods to provide fisheries-independent abundance indicators for tuna stock assessment. In this study, we present first density estimates corrected for availability bias of fin whales (Balaenoptera physalus) and striped dolphins (Stenella coeruleoalba) from the Golf of Lions (GoL), compared with uncorrected estimates of Atlantic bluefin tuna (ABFT; Thunnus thynnus) densities from 8 years of line transect aerial surveys. The raw sighting data were further used to analyze patterns of spatial co-occurrence and density of these three top marine predators in this important feeding ground in the Northwestern Mediterranean Sea. These patterns were investigated regarding known species-specific feeding preferences and environmental characteristics (i. e. mesoscale activity) of the survey zone. ABFT was by far the most abundant species during the surveys in terms of schools and individuals, followed by striped dolphins and fin whales. However, when accounted for availability bias, schools of dolphins and fin whales were of equal density. Direct interactions of the species appeared to be the exception, but results indicate that densities, presence and core sighting locations of striped dolphins and ABFT were correlated. Core sighting areas of these species were located close to an area of high mesoscale activity (oceanic fronts and eddies). Fin whales did not show such a correlation. The results further highlight the feasibility to coordinate research efforts to explore the behaviour and abundance of the investigated species, as demanded by the Marine Strategy Framework Directive (MSFD). PMID:26458254

Co-Occurrence and Habitat Use of Fin Whales, Striped Dolphins and Atlantic Bluefin Tuna in the Northwestern Mediterranean Sea.

PubMed

Bauer, Robert Klaus; Fromentin, Jean-Marc; Demarcq, Hervé; Brisset, Blandine; Bonhommeau, Sylvain

2015-01-01

Different dolphin and tuna species have frequently been reported to aggregate in areas of high frontal activity, sometimes developing close multi-species associations to increase feeding success. Aerial surveys are a common tool to monitor the density and abundance of marine mammals, and have recently become a focus in the search for methods to provide fisheries-independent abundance indicators for tuna stock assessment. In this study, we present first density estimates corrected for availability bias of fin whales (Balaenoptera physalus) and striped dolphins (Stenella coeruleoalba) from the Golf of Lions (GoL), compared with uncorrected estimates of Atlantic bluefin tuna (ABFT; Thunnus thynnus) densities from 8 years of line transect aerial surveys. The raw sighting data were further used to analyze patterns of spatial co-occurrence and density of these three top marine predators in this important feeding ground in the Northwestern Mediterranean Sea. These patterns were investigated regarding known species-specific feeding preferences and environmental characteristics (i. e. mesoscale activity) of the survey zone. ABFT was by far the most abundant species during the surveys in terms of schools and individuals, followed by striped dolphins and fin whales. However, when accounted for availability bias, schools of dolphins and fin whales were of equal density. Direct interactions of the species appeared to be the exception, but results indicate that densities, presence and core sighting locations of striped dolphins and ABFT were correlated. Core sighting areas of these species were located close to an area of high mesoscale activity (oceanic fronts and eddies). Fin whales did not show such a correlation. The results further highlight the feasibility to coordinate research efforts to explore the behaviour and abundance of the investigated species, as demanded by the Marine Strategy Framework Directive (MSFD).

Phase-locked laser array

NASA Technical Reports Server (NTRS)

Botez, Dan (Inventor)

1987-01-01

A phase-locked laser array comprises a body of semiconductor material having means for defining a plurality of substantially parallel lasing zones which are spaced an effective distance apart so that the modes of the adjacent lasing zones are phase-locked to one another. One of the array electrodes comprises a plurality of electrical contacts to the body between the lasing zones. These contacts provide an enhanced current density profile and thus an increase in the gain in the regions between the lasing zones so that zero degree phase-shift operation between adjacent lasing zones is achievable.

Vanishing Act: Experiments on Fission Track Annealing in Monazite

NASA Astrophysics Data System (ADS)

Shipley, N. K.; Fayon, A. K.

2006-12-01

To determine the viability of monazite as a low temperature thermochronometer, we conducted fission track annealing experiments under isothermal conditions. These experiments evaluated the effects of uranium concentration and zoning on annealing rates. Fission track annealing rates in monazite were also compared to those in Durango apatite. Preliminary results indicate that monazite grains with higher initial track densities anneal at faster rates than those with low initial densities and that fission tracks in monazite anneal at a faster rate than those in apatite. Monazite sand grains were selected from a placer sand deposit, mounted in teflon, and polished. Grains were imaged with electron backscattering to characterize zoning patterns and variations in uranium concentration. Monazite grain mounts were etched in boiling 37% HCl for 50 minutes and fission track densities were determined using standard fission track counting techniques. Durango apatite was etched in 5N HNO3 at room temperature for 20 seconds. After the initial track densities were determined, mounts in one group were annealed at 150 ° C for 1to 6 h. The mounts in a second group were annealed at 200 ° C for 2 hour periods along with mounts of Durango apatite grains. All grains were re-polished prior to each anneal. Upon completion of the experiment, backscatter images were taken of grains from which fission track counts were obtained to verify continuance of concentric zoning. Results of these experiments indicate that annealing rates of fission tracks in monazite vary as a function of uranium concentration. Uranium concentration was constrained on the basis of zoning patterns obtained from electron backscatter images. Fission track densities in grains with initial track densities of approximately 2.4 × 106 tracks/cm2 were reduced at average rate of 16% every two hours. In contrast, track densities in grains with initial track densities of approximately 1.6 × 106 tracks/cm2 average 4.6% density reduction every two hours. In both cases, track density reduction in monazite was faster than the rate of 0.1 % every two hours obtained for apatite. This would indicate that fission track annealing occurs at a lower temperature in monazite than in apatite. Thus monazite would be useful as a low temperature chronometer for determining cooling histories in recently exhumed rocks.

Precipitation of silicon from splat-cooled Al-Si alloys

NASA Technical Reports Server (NTRS)

Matyja, H.; Russell, K. C.; Grant, N. J.; Giessen, B. C.

1975-01-01

Splat cooled Al-Si solid solutions with 1 to 11 at.% Si were prepared and their precipitation kinetics were studied by transmission electron microscopy. The time required for appearance of particles visible at a magnification of 35,000 times was determined at temperatures between 248 K and 573 K. The resulting Arrhenius plots yielded activation energies ranging from 55 to 40 plus or minus 2kJ/mol over the composition range. Precipitate densities were higher and denuded zones of 100 to 150 nm were narrower than in comparable solid quenched samples. The activation energies are explained in terms of excess point defect concentrations.

36 CFR 910.12 - Development density.

Code of Federal Regulations, 2011 CFR

2011-07-01

... GUIDELINES AND UNIFORM STANDARDS FOR URBAN PLANNING AND DESIGN OF DEVELOPMENT WITHIN THE PENNSYLVANIA AVENUE DEVELOPMENT AREA Urban Planning and Design Concerns § 910.12 Development density. (a) Land would be developed... urban design elements. (c) Development density is limited by the Zoning Regulations of the District of...

Gravimetric surveys for assessing rock mass condition around a mine shaft

NASA Astrophysics Data System (ADS)

Madej, Janusz

2017-06-01

The fundamentals of use of vertical gravimetric surveying method in mine shafts are presented in the paper. The methods of gravimetric measurements and calculation of interval and complex density are discussed in detail. The density calculations are based on an original method accounting for the gravity influence of the mine shaft thus guaranteeing closeness of calculated and real values of density of rocks beyond the shaft lining. The results of many gravimetric surveys performed in shafts are presented and interpreted. As a result, information about the location of heterogeneous zones of work beyond the shaft lining is obtained. In many cases, these zones used to threaten the safe operation of machines and utilities in the shaft.

Opposing effects of fire severity on climate feedbacks in Siberian larch forests

NASA Astrophysics Data System (ADS)

Loranty, M. M.; Alexander, H. D.; Natali, S.; Kropp, H.; Mack, M. C.; Bunn, A. G.; Davydov, S. P.; Erb, A.; Kholodov, A. L.; Schaaf, C.; Wang, Z.; Zimov, N.; Zimov, S. A.

2017-12-01

Boreal larch forests in northeastern Siberia comprise nearly 25% of the continuous permafrost zone. Structural and functional changes in these ecosystems will have important climate feedbacks at regional and global scales. Like boreal ecosystems in North America, fire is an important determinant of landscape scale forest distribution, and fire regimes are intensifying as climate warms. In Siberian larch forests are dominated by a single tree species, and there is evidence that fire severity influences post-fire forest density via impacts on seedling establishment. The extent to which these effects occur, or persist, and the associated climate feedbacks are not well quantified. In this study we use forest stand inventories, in situ observations, and satellite remote sensing to examine: 1) variation in forest density within and between fire scars, and 2) changes in land surface albedo and active layer dynamics associated with forest density variation. At the landscape scale we observed declines in Landsat derived albedo as forests recovered in the first several decades after fire, though canopy cover varied widely within and between individual fire scars. Within an individual mid-successional fire scar ( 75 years) we observed canopy cover ranging from 15-90% with correspondingly large ranges of albedo during periods of snow cover, and relatively small differences in albedo during the growing season. We found an inverse relationship between canopy density and soil temperature within this fire scar; high-density low-albedo stands had cooler soils and shallower active layers, while low-density stands had warmer soils and deeper active layers. Intensive energy balance measurements at a high- and low- density site show that canopy cover alters the magnitude and timing of ground heat fluxes that affect active layer properties. Our results show that fire impacts on stand structure in Siberian larch forests affect land surface albedo and active layer dynamics in ways that may lead to opposing climate feedbacks. At effectively large scales these changes constitute positive and negative climate feedbacks, respectively. Accurate predictive understanding of terrestrial Arctic climate feedbacks requires improved knowledge regarding the ecological consequences of changing fire regimes in Siberian boreal forests.

Phonon spectra and the one-phonon and two-phonon densities of states of UO2 and PuO2

NASA Astrophysics Data System (ADS)

Poplavnoi, A. S.; Fedorova, T. P.; Fedorov, I. A.

2017-04-01

The vibrational spectra of uranium dioxide UO2 and plutonium dioxide PuO2, as well as the one-phonon densities of states and thermal occupation number weighted two-phonon densities of states, have been calculated within the framework of the phenomenological rigid ion model. It has been shown that the acoustic and optical branches of the spectra are predominantly determined by vibrations of the metal and oxygen atoms, respectively, because the atomic masses of the metal and oxygen differ from each other by an order of magnitude. On this basis, the vibrational spectra can be represented in two Brillouin zones, i.e., in the Brillouin zone of the crystal and the Brillouin zone of the oxygen sublattice. In this case, the number of optical branches decreases by a factor of two. The two-phonon densities of states consist of two broad structured peaks. The temperature dependences of the upper peak exhibit a thermal broadening of the phonon lines L01 and L02 in the upper part of the optical branches. The lower peak is responsible for the thermal broadening of the lowest two optical (T02, T01) and acoustic (LA, TA) branches.

Plume-driven plumbing and crustal formation in Iceland

USGS Publications Warehouse

Allen, R.M.; Nolet, G.; Morgan, W.J.; Vogfjord, K.; Nettles, M.; Ekstrom, G.; Bergsson, B.H.; Erlendsson, P.; Foulger, G.R.; Jakobsdottir, S.; Julian, B.R.; Pritchard, M.; Ragnarsson, S.; Stefansson, R.

2002-01-01

Through combination of surface wave and body wave constraints we derive a three-dimensional (3-D) crustal S velocity model and Moho map for Iceland. It reveals a vast plumbing system feeding mantle plume melt into upper crustal magma chambers where crustal formation takes place. The method is based on the partitioned waveform inversion to which we add additional observations. Love waves from six local events recorded on the HOTSPOT-SIL networks are fitted, Sn travel times from the same events measured, previous observations of crustal thickness are added, and all three sets of constraints simultaneously inverted for our 3-D model. In the upper crust (0-15 km) an elongated low-velocity region extends along the length of the Northern, Eastern and Western Neovolcanic Zones. The lowest velocities (-7%) are found at 5-10 km below the two most active volcanic complexes: Hekla and Bardarbunga-Grimsvotn. In the lower crust (>15 km) the low-velocity region can be represented as a vertical cylinder beneath central Iceland. The low-velocity structure is interpreted as the thermal halo of pipe work which connects the region of melt generation in the uppermost mantle beneath central Iceland to active volcanoes along the neovolcanic zones. Crustal thickness in Iceland varies from 15-20 km beneath the Reykjanes Peninsula, Krafla and the extinct Snfellsnes rift zone, to 46 km beneath central Iceland. The average crustal thickness is 29 km. The variations in thickness can be explained in terms of the temporal variation in plume productivity over the last ~20 Myr, the Snfellsnes rift zone being active during a minimum in plume productivity. Variations in crustal thickness do not depart significantly from an isostatically predicted crustal thickness. The best fit linear isostatic relation implies an average density jump of 4% across the Moho. Rare earth element inversions of basalt compositions on Iceland suggest a melt thickness (i.e., crustal thickness) of 15-20 km, given passive upwelling. The observed crustal thickness of up to 46 km implies active fluxing of source material through the melt zone by the mantle plume at up to 3 times the passive rate.

Assessment of fish communities in a Mediterranean MPA: Can a seasonal no-take zone provide effective protection?

NASA Astrophysics Data System (ADS)

Dimitriadis, Charalampos; Sini, Maria; Trygonis, Vasilis; Gerovasileiou, Vasilis; Sourbès, Laurent; Koutsoubas, Drosos

2018-07-01

The efficacy of a Mediterranean Marine Protected Area (National Marine Park of Zakynthos - NMPZ, Ionian Sea, Greece) that implements a seasonal no-take zone as part of its management scheme was assessed using fish data collected in situ with underwater visual census. Sampling was conducted at two habitat types (Posidonia oceanica meadows and rocky reefs) that occur at sites of different protection level with respect to fisheries (high protection: seasonal no-take zone within the MPA; intermediate: zones within the MPA where small-scale fishing is allowed; none: areas outside the MPA, where all types of fishing are allowed, including trawlers, purse seiners, and recreational fishing). The data were used to examine the effects of protection level and habitat type on community parameters, trophic structure and functional diversity of fish populations that occupy the upper sublittoral zone. Overall, habitat type had a more pronounced effect than protection level on all investigated parameters. Biomass, density and number of fish species with low commercial value were higher in sites of intermediate protection, but no substantial fisheries-related ecological benefits were detected for targeted fish in the seasonal no-take zone. Conducted 8 years after the initial implementation of the seasonal no-take management scheme, our study suggests that existing fishing regulations in the NMPZ provide some measurable effects, but fall short of maintaining sufficient protection for the recovery of apex predators or other commercially important fish species. A revision of the existing zoning system to include permanent no-take zones, alongside the regulation of professional fishing and all extractive activities in the rest of the MPA, are strongly encouraged in order to enhance the effectiveness of fisheries management.

Auroral zone effects on hydrogen geocorona structure and variability

NASA Technical Reports Server (NTRS)

Moore, T. E.; Biddle, A. P.; Waite, J. H., Jr.; Killeen, T. L.

1985-01-01

The effect of diurnal and magnetospheric modulations on the structure of the hydrogen geocorona is analyzed on the basis of recent observations. Particular attention is given to the enhancement of neutral escape by plasma effects, including the recently observed phenomenon of low-altitude ion acceleration. It is found that, while significant fluxes of neutral H should be produced by transverse ion acceleration in the auroral zone, the process is probably insufficient to account for the observed polar depletion of hydrogen atoms. Analysis of recent exospheric temperature measurements from the Dynamics Explorer-2 satellite suggest that neutral heating in and near the high latitude cusp may be the major contributor to depleted atomic hydrogen densities at high latitudes. Altitude profiles of the production rates for escaping neutral hydrogen atoms during periods of maximum, minimum, and typical solar activity are provided.

Meltwater storage in low-density near-surface bare ice in the Greenland ice sheet ablation zone

NASA Astrophysics Data System (ADS)

Cooper, Matthew G.; Smith, Laurence C.; Rennermalm, Asa K.; Miège, Clément; Pitcher, Lincoln H.; Ryan, Jonathan C.; Yang, Kang; Cooley, Sarah W.

2018-03-01

We document the density and hydrologic properties of bare, ablating ice in a mid-elevation (1215 m a.s.l.) supraglacial internally drained catchment in the Kangerlussuaq sector of the western Greenland ice sheet. We find low-density (0.43-0.91 g cm-3, μ = 0.69 g cm-3) ice to at least 1.1 m depth below the ice sheet surface. This near-surface, low-density ice consists of alternating layers of water-saturated, porous ice and clear solid ice lenses, overlain by a thin (< 0.5 m), even lower density (0.33-0.56 g cm-3, μ = 0.45 g cm-3) unsaturated weathering crust. Ice density data from 10 shallow (0.9-1.1 m) ice cores along an 800 m transect suggest an average 14-18 cm of specific meltwater storage within this low-density ice. Water saturation of this ice is confirmed through measurable water levels (1-29 cm above hole bottoms, μ = 10 cm) in 84 % of cryoconite holes and rapid refilling of 83 % of 1 m drilled holes sampled along the transect. These findings are consistent with descriptions of shallow, depth-limited aquifers on the weathered surface of glaciers worldwide and confirm the potential for substantial transient meltwater storage within porous low-density ice on the Greenland ice sheet ablation zone surface. A conservative estimate for the ˜ 63 km2 supraglacial catchment yields 0.009-0.012 km3 of liquid meltwater storage in near-surface, porous ice. Further work is required to determine if these findings are representative of broader areas of the Greenland ice sheet ablation zone, and to assess the implications for sub-seasonal mass balance processes, surface lowering observations from airborne and satellite altimetry, and supraglacial runoff processes.

DEAD ZONE IN THE POLAR-CAP ACCELERATOR OF PULSARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Alexander Y.; Beloborodov, Andrei M.

We study plasma flows above pulsar polar caps using time-dependent simulations of plasma particles in the self-consistent electric field. The flow behavior is controlled by the dimensionless parameter {alpha} = j/c{rho}{sub GJ}, where j is the electric current density and {rho}{sub GJ} is the Goldreich-Julian charge density. The region of the polar cap where 0 < {alpha} < 1 is a {sup d}ead zone{sup -}in this zone, particle acceleration is inefficient and pair creation is not expected even for young, rapidly rotating pulsars. Pulsars with polar caps near the rotation axis are predicted to have a hollow-cone structure of radiomore » emission, as the dead zone occupies the central part of the polar cap. Our results apply to charge-separated flows of electrons (j < 0) or ions (j > 0). In the latter case, we consider the possibility of a mixed flow consisting of different ion species, and observe the development of two-stream instability. The dead zone at the polar cap is essential for the development of an outer gap near the null surface {rho}{sub GJ} = 0.« less

Strain distribution across magmatic margins during the breakup stage: Seismicity patterns in the Afar rift zone

NASA Astrophysics Data System (ADS)

Brown, C.; Ebinger, C. J.; Belachew, M.; Gregg, T.; Keir, D.; Ayele, A.; Aronovitz, A.; Campbell, E.

2008-12-01

Fault patterns record the strain history along passive continental margins, but geochronological constraints are, in general, too sparse to evaluate these patterns in 3D. The Afar depression in Ethiopia provides a unique setting to evaluate the time and space relations between faulting and magmatism across an incipient passive margin that formed above a mantle plume. The margin comprises a high elevation flood basalt province with thick, underplated continental crust, a narrow fault-line escarpment underlain by stretched and intruded crust, and a broad zone of highly intruded, mafic crust lying near sealevel. We analyze fault and seismicity patterns across and along the length of the Afar rift zone to determine the spatial distribution of strain during the final stages of continental breakup, and its relation to active magmatism and dike intrusions. Seismicity data include historic data and 2005-2007 data from the collaborative US-UK-Ethiopia Afar Geodynamics Project that includes the 2005-present Dabbahu rift episode. Earthquake epicenters cluster within discrete, 50 km-long magmatic segments that lack any fault linkage. Swarms also cluster along the fault-line scarp between the unstretched and highly stretched Afar rift zone; these earthquakes may signal release of stresses generated by large lateral density contrasts. We compare Coulomb static stress models with focal mechanisms and fault kinematics to discriminate between segmented magma intrusion and crank- arm models for the central Afar rift zone.

The importance of Radio Quiet Zone (RQZ) for radio astronomy

NASA Astrophysics Data System (ADS)

Umar, Roslan; Abidin, Zamri Zainal; Ibrahim, Zainol Abidin

2013-05-01

Most of radio observatories are located in isolated areas. Since radio sources from the universe is very weak, astronomer need to avoid radio frequency interference (RFI) from active spectrum users and radio noise produced by human made (telecommunication, mobile phone, microwave user and many more. There are many observatories around the world are surrounded by a Radio Quiet Zone (RQZ), which is it was set up using public or state laws. A Radio Quiet Zone normally consists of two areas: an exclusive area in which totally radio emissions are forbidden, with restrictions for residents and business developments, and a larger (radius up to 100 km above) coordination area where the power of radio transmission limits to threshold levels. Geographical Information System (GIS) can be used as a powerful tool in mapping large areas with varying RQZ profiles. In this paper, we report the initial testing of the usage of this system in order to identify the areas were suitable for Radio Quiet Zone. Among the important parameters used to develop the database for our GIS are population density, information on TV and telecommunication (mobile phones) transmitters, road networks (highway), and contour shielding. We will also use other information gathered from on-site RFI level measurements on selected 'best' areas generated by the GIS. The intention is to find the best site for the purpose of establishing first radio quiet zones for radio telescope in Malaysia.

Determining Source Attenuation History to Support Closure by Natural Attenuation

DTIC Science & Technology

2013-09-01

SUBTITLE 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 6. AUTHOR(S...Tortuosity Factor Exponent Bulk Density of Low-k Zone DistriDutlon Coemctent or FractiOn Organic Carbon In Low-k Zone o rgaric CarDon Pa-tnioning...Organic Carbon In Low-k Zone orgaric CarDon Pa-tnioning coemctent Constrtuent Half-Life in Low-k Zone 3. GEN ERA L Year Core sample Collected fran

Nonlinear density waves in planetary rings

NASA Technical Reports Server (NTRS)

Borderies, Nicole; Goldreich, Peter; Tremaine, Scott

1986-01-01

The steady-state structure of planetary rings in the presence of density waves at the Lindblad resonances of a satellite is indicated. The study is based on the dispersion relation and damping rate for nonlinear density waves, derived by Shu et al. (1985) and by Borderies, Goldreich, and Tremaine (1985). It is shown that strong density waves lead to an enhancement of the background surface density in the wave zone.

Modelling population distribution using remote sensing imagery and location-based data

NASA Astrophysics Data System (ADS)

Song, J.; Prishchepov, A. V.

2017-12-01

Detailed spatial distribution of population density is essential for city studies such as urban planning, environmental pollution and city emergency, even estimate pressure on the environment and human exposure and risks to health. However, most of the researches used census data as the detailed dynamic population distribution are difficult to acquire, especially in microscale research. This research describes a method using remote sensing imagery and location-based data to model population distribution at the function zone level. Firstly, urban functional zones within a city were mapped by high-resolution remote sensing images and POIs. The workflow of functional zones extraction includes five parts: (1) Urban land use classification. (2) Segmenting images in built-up area. (3) Identification of functional segments by POIs. (4) Identification of functional blocks by functional segmentation and weight coefficients. (5) Assessing accuracy by validation points. The result showed as Fig.1. Secondly, we applied ordinary least square and geographically weighted regression to assess spatial nonstationary relationship between light digital number (DN) and population density of sampling points. The two methods were employed to predict the population distribution over the research area. The R²of GWR model were in the order of 0.7 and typically showed significant variations over the region than traditional OLS model. The result showed as Fig.2.Validation with sampling points of population density demonstrated that the result predicted by the GWR model correlated well with light value. The result showed as Fig.3. Results showed: (1) Population density is not linear correlated with light brightness using global model. (2) VIIRS night-time light data could estimate population density integrating functional zones at city level. (3) GWR is a robust model to map population distribution, the adjusted R2 of corresponding GWR models were higher than the optimal OLS models, confirming that GWR models demonstrate better prediction accuracy. So this method provide detailed population density information for microscale citizen studies.

A High Explanatory Power Model of Foot and Mouth Disease Spread in Central California

DTIC Science & Technology

2013-03-01

22  1.  The Farm File...map of farms in Zone 3. The density index increases with lighter to darker shades of green. This map highlights that certain locations in Zone 3...have larger concentrations of farms highlighted in darker shades of green. .....22  Figure 9.  Histogram of types of farms in Zone 3. We observe that

The influence of four macrozoobenthic species on the abundance of the amphipod Corophium volutator on tidal flats of the Wadden Sea

NASA Astrophysics Data System (ADS)

Flach, E. C.

On the tidal flats of the Wadden Sea, a zonation pattern can be found with Corophium volutator and Nereis diversicolor as the dominating species of the upper intertidal zone and Arenicola marina and Cerastoderma edule as the dominating species of the lower zone. As C. volutator can live under a great variety of physical conditions, its restriction to higher areas might result from biotic interactions. This was investigated by field experiments on a tidal flat in the westernmost part of the Wadden Sea. Within large depopulated areas, small plots were recolonized with different densities of N. diversicolor, A. marina, C. edule and Macoma balthica and the subsequent settlement and dynamics of C. volutator were studied. In addition, A. marina and/or C. edule were added to or removed from small plots within a natural benthic community. Neither the presence of M. balthica not that of N. diversicolor significantly affected the abundance of C. volutator. A strongly negative effect was found of C. edule when present in high densities, whereas A. marina negatively affected C. volutator abundance already at relatively low densities. Local removals of A. marina and C. edule from their own zone resulted in increases of Corophium numbers at these locations and local additions of these species within the Corophium zone resulted in decreases of Corophium numbers at these locations. It is suggested that the major species to restrict C. volutator effectively to the upper tidal zone is A. marina.

Binational school-based monitoring of traffic-related air pollutants in El Paso, Texas (USA) and Ciudad Juárez, Chihuahua (México).

PubMed

Raysoni, Amit U; Sarnat, Jeremy A; Sarnat, Stefanie Ebelt; Garcia, Jośe Humberto; Holguin, Fernando; Luèvano, Silvia Flores; Li, Wen-Whai

2011-10-01

Paired indoor and outdoor concentrations of fine and coarse particulate matter (PM), PM2.5 reflectance [black carbon(BC)], and nitrogen dioxide (NO(2)) were determined for sixteen weeks in 2008 at four elementary schools (two in high and two in low traffic density zones) in a U.S.-Mexico border community to aid a binational health effects study. Strong spatial heterogeneity was observed for all outdoor pollutant concentrations. Concentrations of all pollutants, except coarse PM, were higher in high traffic zones than in the respective low traffic zones. Black carbon and NO(2) appear to be better traffic indicators than fine PM. Indoor air pollution was found to be well associated with outdoor air pollution, although differences existed due to uncontrollable factors involving student activities and building/ventilation configurations. Results of this study indicate substantial spatial variability of pollutants in the region, suggesting that children's exposures to these pollutants vary based on the location of their school. Copyright © 2011 Elsevier Ltd. All rights reserved.

[Characteristics of soil organic carbon and enzyme activities in soil aggregates under different vegetation zones on the Loess Plateau].

PubMed

Li, Xin; Ma, Rui-ping; An, Shao-shan; Zeng, Quan-chao; Li, Ya-yun

2015-08-01

In order to explore the distribution characteristics of organic carbon of different forms and the active enzymes in soil aggregates with different particle sizes, soil samples were chosen from forest zone, forest-grass zone and grass zone in the Yanhe watershed of Loess Plateau to study the content of organic carbon, easily oxidized carbon, and humus carbon, and the activities of cellulase, β-D-glucosidase, sucrose, urease and peroxidase, as well as the relations between the soil aggregates carbon and its components with the active soil enzymes were also analyzed. It was showed that the content of organic carbon and its components were in order of forest zone > grass zone > forest-grass zone, and the contents of three forms of organic carbon were the highest in the diameter group of 0.25-2 mm. The content of organic carbon and its components, as well as the activities of soil enzymes were higher in the soil layer of 0-10 cm than those in the 10-20 cm soil layer of different vegetation zones. The activities of cellulase, β-D-glucosidase, sucrose and urease were in order of forest zone > grass zone > forest-grass zone. The peroxidase activity was in order of forest zone > forest-grass zone > grass zone. The activities of various soil enzymes increased with the decreasing soil particle diameter in the three vegetation zones. The activities of cellulose, peroxidase, sucrose and urease had significant positive correlations with the contents of various forms of organic carbon in the soil aggregates.

A geophysical potential field study to image the Makran subduction zone in SE of Iran

NASA Astrophysics Data System (ADS)

Abedi, Maysam; Bahroudi, Abbas

2016-10-01

The Makran subduction wedge as one of the largest subduction complexes has been forming due to the Arabian oceanic lithosphere subducting beneath the Lut and the Afghan rigid block microplates. To better visualize the subducting oceanic crust in this region, a geophysical model of magnetic susceptibility from an airborne magnetic survey (line spacing about 7.5 km) over the Makran zone located at southeast of Iran is created to image various structural units in Iran plate. The constructed geophysical model from the 3D inverse modeling of the airborne magnetic data indicates a thin subducting slab to the north of the Makran structural zone. It is demonstrated that the thickness of sedimentary units varies approximately at an interval of 7.5-11 km from north to south of this zone in the Iranian plate, meanwhile the curie depth is also estimated approximately < 26 km. It is also shown the Jazmurian depression zone adjacent to the north of the Makran indicates high intensity magnetic anomalies due to being underlain by an ophiolite oceanic basement, while such intensity reduces over the Makran. The directional derivatives of the magnetic field data have subtle changes in the Makran, but strongly increase in the Jazmurian by enhancing and separating different structural boundaries in this region. In addition, the density variations of the subsurface geological layers were determined by 3D inversion of the ground-based gravity data over the whole study area, where the constructed density model was in good agreement with the magnetic one. According to the outputs of the magnetic susceptibility and the density contrast, the Arabian plate subducts to the north under the Eurasia with a very low dip angle in the Makran structural zone.

Factors controlling bacteria and protists in selected Mazurian eutrophic lakes (North-Eastern Poland) during spring

PubMed Central

2013-01-01

Background The bottom-up (food resources) and top-down (grazing pressure) controls, with other environmental parameters (water temperature, pH) are the main factors regulating the abundance and structure of microbial communities in aquatic ecosystems. It is still not definitively decided which of the two control mechanisms is more important. The significance of bottom-up versus top-down controls may alter with lake productivity and season. In oligo- and/or mesotrophic environments, the bottom-up control is mostly important in regulating bacterial abundances, while in eutrophic systems, the top-down control may be more significant. Results The abundance of bacteria, heterotrophic (HNF) and autotrophic (ANF) nanoflagellates and ciliates, as well as bacterial production (BP) and metabolically active cells of bacteria (CTC, NuCC, EST) were studied in eutrophic lakes (Mazurian Lake District, Poland) during spring. The studied lakes were characterized by high nanoflagellate (mean 17.36 ± 8.57 × 103 cells ml-1) and ciliate abundances (mean 59.9 ± 22.4 ind. ml-1) that were higher in the euphotic zone than in the bottom waters, with relatively low bacterial densities (4.76 ± 2.08 × 106 cells ml-1) that were lower in the euphotic zone compared to the profundal zone. Oligotrichida (Rimostrombidium spp.), Prostomatida (Urotricha spp.) and Scuticociliatida (Histiobalantium bodamicum) dominated in the euphotic zone, whereas oligotrichs Tintinnidium sp. and prostomatids Urotricha spp. were most numerous in the bottom waters. Among the staining methods used to examine bacterial cellular metabolic activity, the lowest percentage of active cells was recorded with the CTC (1.5–15.4%) and EST (2.7–14.2%) assay in contrast to the NuCC (28.8–97.3%) method. Conclusions In the euphotic zone, the bottom-up factors (TP and DOC concentrations) played a more important role than top-down control (grazing by protists) in regulating bacterial numbers and activity. None of the single analyzed factors controlled bacterial abundance in the bottom waters. The results of this study suggest that both control mechanisms, bottom-up and top-down, simultaneously regulated bacterial community and their activity in the profundal zone of the studied lakes during spring. In both lake water layers, food availability (algae, nanoflagellates) was probably the major factor determining ciliate abundance and their composition. In the bottom waters, both groups of protists appeared to be also influenced by oxygen, temperature, and total phosphorus. PMID:23566491

Changed Synaptic Plasticity in Neural Circuits of Depressive-Like and Escitalopram-Treated Rats

PubMed Central

Li, Xiao-Li; Yuan, Yong-Gui; Xu, Hua; Wu, Di; Gong, Wei-Gang; Geng, Lei-Yu; Wu, Fang-Fang; Tang, Hao; Xu, Lin

2015-01-01

Background: Although progress has been made in the detection and characterization of neural plasticity in depression, it has not been fully understood in individual synaptic changes in the neural circuits under chronic stress and antidepressant treatment. Methods: Using electron microscopy and Western-blot analyses, the present study quantitatively examined the changes in the Gray’s Type I synaptic ultrastructures and the expression of synapse-associated proteins in the key brain regions of rats’ depressive-related neural circuit after chronic unpredicted mild stress and/or escitalopram administration. Meanwhile, their depressive behaviors were also determined by several tests. Results: The Type I synapses underwent considerable remodeling after chronic unpredicted mild stress, which resulted in the changed width of the synaptic cleft, length of the active zone, postsynaptic density thickness, and/or synaptic curvature in the subregions of medial prefrontal cortex and hippocampus, as well as the basolateral amygdaloid nucleus of the amygdala, accompanied by changed expression of several synapse-associated proteins. Chronic escitalopram administration significantly changed the above alternations in the chronic unpredicted mild stress rats but had little effect on normal controls. Also, there was a positive correlation between the locomotor activity and the maximal synaptic postsynaptic density thickness in the stratum radiatum of the Cornu Ammonis 1 region and a negative correlation between the sucrose preference and the length of the active zone in the basolateral amygdaloid nucleus region in chronic unpredicted mild stress rats. Conclusion: These findings strongly indicate that chronic stress and escitalopram can alter synaptic plasticity in the neural circuits, and the remodeled synaptic ultrastructure was correlated with the rats’ depressive behaviors, suggesting a therapeutic target for further exploration. PMID:25899067

The density, compressibility and seismic velocity of hydrous melts at crustal and upper mantle conditions

NASA Astrophysics Data System (ADS)

Ueki, K.; Iwamori, H.

2015-12-01

Various processes of subduction zone magmatism, such as upward migration of partial melts and fractional crystallization depend on the density of the hydrous silicate melt. The density and the compressibility of the hydrous melt are key factors for the thermodynamic calculation of phase relation of the hydrous melt, and the geophysical inversion to predict physicochemical conditions of the melting region based on the seismic velocity. This study presents a new model for the calculations of the density of the hydrous silicate melts as a function of T, P, H2O content and melt composition. The Birch-Murnaghan equation is used for the equation of state. We compile the experimentally determined densities of various hydrous melts, and optimize the partial molar volume, compressibility, thermal expansibility and its pressure derivative, and K' of the H2O component in the silicate melt. P-T ranges of the calibration database are 0.48-4.29 GPa and 1033-2073 K. As such, this model covers the P-T ranges of the entire melting region of the subduction zone. Parameter set provided by Lange and Carmichael [1990] is used for the partial molar volume and KT value of the anhydrous silicate melt. K' of anhydrous melt is newly parameterized as a function of SiO2 content. The new model accurately reproduces the experimentally determined density variations of various hydrous melts from basalt to rhyolite. Our result shows that the hydrous melt is more compressive and less dense than the anhydrous melt; with the 5 wt% of H2O in melt, density and KT decrease by ~10% and ~30% from those of the anhydrous melt, respectively. For the application of the model, we calculated the P-wave velocity of the hydrous melt. With the 5 wt% of H2O, P-wave velocity of the silicate melt decreases by >10%. Based on the melt P-wave velocity, we demonstrate the effect of the melt H2O content on the seismic velocity of the partially molten zone of the subduction zone.

Instrumented roll technology for the design space development of roller compaction process.

PubMed

Nesarikar, Vishwas V; Vatsaraj, Nipa; Patel, Chandrakant; Early, William; Pandey, Preetanshu; Sprockel, Omar; Gao, Zhihui; Jerzewski, Robert; Miller, Ronald; Levin, Michael

2012-04-15

Instrumented roll technology on Alexanderwerk WP120 roller compactor was developed and utilized successfully for the measurement of normal stress on ribbon during the process. The effects of process parameters such as roll speed (4-12 rpm), feed screw speed (19-53 rpm), and hydraulic roll pressure (40-70 bar) on normal stress and ribbon density were studied using placebo and active pre-blends. The placebo blend consisted of 1:1 ratio of microcrystalline cellulose PH102 and anhydrous lactose with sodium croscarmellose, colloidal silicon dioxide, and magnesium stearate. The active pre-blends were prepared using various combinations of one active ingredient (3-17%, w/w) and lubricant (0.1-0.9%, w/w) levels with remaining excipients same as placebo. Three force transducers (load cells) were installed linearly along the width of the roll, equidistant from each other with one transducer located in the center. Normal stress values recorded by side sensors and were lower than normal stress values recorded by middle sensor and showed greater variability than middle sensor. Normal stress was found to be directly proportional to hydraulic pressure and inversely to screw to roll speed ratio. For active pre-blends, normal stress was also a function of compressibility. For placebo pre-blends, ribbon density increased as normal stress increased. For active pre-blends, in addition to normal stress, ribbon density was also a function of gap. Models developed using placebo were found to predict ribbon densities of active blends with good accuracy and the prediction error decreased as the drug concentration of active blend decreased. Effective angle of internal friction and compressibility properties of active pre blend may be used as key indicators for predicting ribbon densities of active blend using placebo ribbon density model. Feasibility of on-line prediction of ribbon density during roller compaction was demonstrated using porosity-pressure data of pre-blend and normal stress measurements. Effect of vacuum to de-aerate pre blend prior to entering the nip zone was studied. Varying levels of vacuum for de-aeration of placebo pre blend did not affect the normal stress values. However, turning off vacuum completely caused an increase in normal stress with subsequent decrease in gap. Use of instrumented roll demonstrated potential to reduce the number of DOE runs by enhancing fundamental understanding of relationship between normal stress on ribbon and process parameters. Copyright © 2012 Elsevier B.V. All rights reserved.

Modeling the Plasmasphere

NASA Technical Reports Server (NTRS)

Gallagher, Dennis L

1998-01-01

The plasmasphere has often been considered one of the more boring regions in the magnetosphere. Its low energy plasma doesn't begin to compete against the free sources of energy available in the ring current, auroral zone, or plasma sheet. Its best known feature is its relatively highly density, archived as a result of prolonged accumulation of ionospheric outflow onto corotating flux tubes. On second look, however, the plasmasphere can be found to exhibit a remarkable influence on its more energetic cousins and display convection behavior indicative of physical processes acting throughout the magnetosphere for which we have no explanation. Plasmaspheric plasma densities and composition of heavy ions are particularly sensitive to heating by processes active in the ionosphere and all along field lines. Wave propagation and instabilities, collisional losses in the ring current, and heat transport from superthermal electrons are all equally sensitive to dense, heavy plasmaspheric densities and density gradients. It is in this context that we seek to characterize plasmaspheric populations using event based, empirical, and physical modeling methods. The modeling approaches, the challenges, and some of the results of these efforts will be presented.

Strain-dependent Damage Evolution and Velocity Reduction in Fault Zones Induced by Earthquake Rupture

NASA Astrophysics Data System (ADS)

Zhong, J.; Duan, B.

2009-12-01

Low-velocity fault zones (LVFZs) with reduced seismic velocities relative to the surrounding wall rocks are widely observed around active faults. The presence of such a zone will affect rupture propagation, near-field ground motion, and off-fault damage in subsequent earth-quakes. In this study, we quantify the reduction of seismic velocities caused by dynamic rup-ture on a 2D planar fault surrounded by a low-velocity fault zone. First, we implement the damage rheology (Lyakhovsky et al. 1997) in EQdyna (Duan and Oglesby 2006), an explicit dynamic finite element code. We further extend this damage rheology model to include the dependence of strains on crack density. Then, we quantify off-fault continuum damage distribution and velocity reduction induced by earthquake rupture with the presence of a preexisting LVFZ. We find that the presence of a LVFZ affects the tempo-spatial distribu-tions of off-fault damage. Because lack of constraint in some damage parameters, we further investigate the relationship between velocity reduction and these damage prameters by a large suite of numerical simulations. Slip velocity, slip, and near-field ground motions computed from damage rheology are also compared with those from off-fault elastic or elastoplastic responses. We find that the reduction in elastic moduli during dynamic rupture has profound impact on these quantities.

The CARMENES Search for Exoplanets around M Dwarfs: A Low-mass Planet in the Temperate Zone of the Nearby K2-18

NASA Astrophysics Data System (ADS)

Sarkis, Paula; Henning, Thomas; Kürster, Martin; Trifonov, Trifon; Zechmeister, Mathias; Tal-Or, Lev; Anglada-Escudé, Guillem; Hatzes, Artie P.; Lafarga, Marina; Dreizler, Stefan; Ribas, Ignasi; Caballero, José A.; Reiners, Ansgar; Mallonn, Matthias; Morales, Juan C.; Kaminski, Adrian; Aceituno, Jesús; Amado, Pedro J.; Béjar, Victor J. S.; Hagen, Hans-Jürgen; Jeffers, Sandra; Quirrenbach, Andreas; Launhardt, Ralf; Marvin, Christopher; Montes, David

2018-06-01

K2-18 is a nearby M2.5 dwarf, located at 34 pc and hosting a transiting planet that was first discovered by the K2 mission and later confirmed with Spitzer Space Telescope observations. With a radius of ∼2 R ⊕ and an orbital period of ∼33 days, the planet lies in the temperate zone of its host star and receives stellar irradiation similar to that of Earth. Here we perform radial velocity follow-up observations with the visual channel of CARMENES with the goal of determining the mass and density of the planet. We measure a planetary semi-amplitude of K b ∼ 3.5 {{m}} {{{s}}}-1 and a mass of M b ∼ 9 M ⊕, yielding a bulk density around {ρ }b∼ 4 {{g}} {cm}}-3. This indicates a low-mass planet with a composition consistent with a solid core and a volatile-rich envelope. A signal at 9 days was recently reported using radial velocity measurements taken with the HARPS spectrograph. This was interpreted as being due to a second planet. We see a weaker, time- and wavelength-dependent signal in the CARMENES data set and thus favor stellar activity for its origin. K2-18 b joins the growing group of low-mass planets detected in the temperate zone of M dwarfs. The brightness of the host star in the near-infrared makes the system a good target for detailed atmospheric studies with the James Webb Space Telescope.

Pn Tomography of the Central and Eastern United States

NASA Astrophysics Data System (ADS)

Zhang, Q.; Sandvol, E. A.; Liu, M.

2005-12-01

Approximately 44,000 Pn phase readings from the ISC and NEIC catalogs and 750 hand picked arrivals were inverted to map the velocity structure of mantle lithosphere in the Central and Eastern United States (CEUS). Overall we have a high density of ray paths within the active seismic zones in the eastern and southern parts of the CEUS, while ray coverage is relatively poor to the west of Great Lakes as well as along the eastern and southern coastlines of the U.S. The average Pn velocity in the CEUS is approximately 8.03 km/s. High Pn velocities (~8.18 km/s) within the northeastern part of the North American shield are reliable, while the resolution of the velocity image of the American shield around the mid-continent rift (MCR) is relatively low due to the poor ray coverage. Under the East Continent Rift (EC), the northern part of the Reelfoot Rift Zone (RRZ), and the South Oklahoma Aulacogen (SO), we also observe high velocity lithospheric mantle (~8.13-8.18 km/s). Typical Pn velocities (~7.98 km/s) are found between those three high velocity blocks. Low velocities are shown in the northern and southern Appalachians (~7.88-7.98 km/s) as well as the Rio Grande Rift (~7.88 km/s). In the portion of our model with the highest ray density, the Pn azimuthal anisotropy seems to be robust. These fast directions appear to mirror the boundaries of the low Pn velocity zone and parallel the Appalachians down to the southwest.

Trophic State Evolution and Nutrient Trapping Capacity in a Transboundary Subtropical Reservoir: A 25-Year Study

NASA Astrophysics Data System (ADS)

Cunha, Davi Gasparini Fernandes; Benassi, Simone Frederigi; de Falco, Patrícia Bortoletto; do Carmo Calijuri, Maria

2016-03-01

Artificial reservoirs have been used for drinking water supply, other human activities, flood control and pollution abatement worldwide, providing overall benefits to downstream water quality. Most reservoirs in Brazil were built during the 1970s, but their long-term patterns of trophic status, water chemistry, and nutrient removal are still not very well characterized. We aimed to evaluate water quality time series (1985-2010) data from the riverine and lacustrine zones of the transboundary Itaipu Reservoir (Brazil/Paraguay). We examined total phosphorus and nitrogen, chlorophyll a concentrations, water transparency, and phytoplankton density to look for spatial and temporal trends and correlations with trophic state evolution and nutrient retention. There was significant temporal and spatial water quality variation ( P < 0.01, ANCOVA). The results indicated that the water quality and structure of the reservoir were mainly affected by one internal force (hydrodynamics) and one external force (upstream cascading reservoirs). Nutrient and chlorophyll a concentrations tended to be lower in the lacustrine zone and decreased over the 25-year timeframe. Reservoir operational features seemed to be limiting primary production and phytoplankton development, which exhibited a maximum density of 6050 org/mL. The relatively small nutrient concentrations in the riverine zone were probably related to the effect of the cascade reservoirs upstream of Itaipu and led to relatively low removal percentages. Our study suggested that water quality problems may be more pronounced immediately after the filling phase of the artificial reservoirs, associated with the initial decomposition of drowned vegetation at the very beginning of reservoir operation.

Trophic State Evolution and Nutrient Trapping Capacity in a Transboundary Subtropical Reservoir: A 25-Year Study.

PubMed

Cunha, Davi Gasparini Fernandes; Benassi, Simone Frederigi; de Falco, Patrícia Bortoletto; Calijuri, Maria do Carmo

2016-03-01

Artificial reservoirs have been used for drinking water supply, other human activities, flood control and pollution abatement worldwide, providing overall benefits to downstream water quality. Most reservoirs in Brazil were built during the 1970s, but their long-term patterns of trophic status, water chemistry, and nutrient removal are still not very well characterized. We aimed to evaluate water quality time series (1985-2010) data from the riverine and lacustrine zones of the transboundary Itaipu Reservoir (Brazil/Paraguay). We examined total phosphorus and nitrogen, chlorophyll a concentrations, water transparency, and phytoplankton density to look for spatial and temporal trends and correlations with trophic state evolution and nutrient retention. There was significant temporal and spatial water quality variation (P < 0.01, ANCOVA). The results indicated that the water quality and structure of the reservoir were mainly affected by one internal force (hydrodynamics) and one external force (upstream cascading reservoirs). Nutrient and chlorophyll a concentrations tended to be lower in the lacustrine zone and decreased over the 25-year timeframe. Reservoir operational features seemed to be limiting primary production and phytoplankton development, which exhibited a maximum density of 6050  org/mL. The relatively small nutrient concentrations in the riverine zone were probably related to the effect of the cascade reservoirs upstream of Itaipu and led to relatively low removal percentages. Our study suggested that water quality problems may be more pronounced immediately after the filling phase of the artificial reservoirs, associated with the initial decomposition of drowned vegetation at the very beginning of reservoir operation.

[Spatial pattern of forest biomass and its influencing factors in the Great Xing'an Mountains, Heilongjiang Province, China].

PubMed

Wang, Xiao-Li; Chang, Yu; Chen, Hong-Wei; Hu, Yuan-Man; Jiao, Lin-Lin; Feng, Yu-Ting; Wu, Wen; Wu, Hai-Feng

2014-04-01

Based on field inventory data and vegetation index EVI (enhanced vegetation index), the spatial pattern of the forest biomass in the Great Xing'an Mountains, Heilongjiang Province was quantitatively analyzed. Using the spatial analysis and statistics tools in ArcGIS software, the impacts of climatic zone, elevation, slope, aspect and vegetation type on the spatial pattern of forest biomass were explored. The results showed that the forest biomass in the Great Xing'an Mountains was 350 Tg and spatially aggregated with great increasing potentials. Forest biomass density in the cold temperate humid zone (64.02 t x hm(-2)) was higher than that in the temperate humid zone (60.26 t x hm(-2)). The biomass density of each vegetation type was in the order of mixed coniferous forest (65.13 t x hm(-2)) > spruce-fir forest (63.92 t x hm(-2)) > Pinus pumila-Larix gmelinii forest (63.79 t x hm(-2)) > Pinus sylvestris var. mongolica forest (61.97 t x hm(-2)) > Larix gmelinii forest (61.40 t x hm(-2)) > deciduous broadleaf forest (58.96 t x hm(-2)). With the increasing elevation and slope, the forest biomass density first decreased and then increased. The forest biomass density in the shady slopes was greater than that in the sunny slopes. The spatial pattern of forest biomass in the Great Xing' an Mountains exhibited a heterogeneous pattern due to the variation of climatic zone, vegetation type and topographical factor. This spatial heterogeneity needs to be accounted when evaluating forest biomass at regional scales.

Assessing Photoreceptor Structure in Retinitis Pigmentosa and Usher Syndrome.

PubMed

Sun, Lynn W; Johnson, Ryan D; Langlo, Christopher S; Cooper, Robert F; Razeen, Moataz M; Russillo, Madia C; Dubra, Alfredo; Connor, Thomas B; Han, Dennis P; Pennesi, Mark E; Kay, Christine N; Weinberg, David V; Stepien, Kimberly E; Carroll, Joseph

2016-05-01

The purpose of this study was to examine cone photoreceptor structure in retinitis pigmentosa (RP) and Usher syndrome using confocal and nonconfocal split-detector adaptive optics scanning light ophthalmoscopy (AOSLO). Nineteen subjects (11 RP, 8 Usher syndrome) underwent ophthalmic and genetic testing, spectral-domain optical coherence tomography (SD-OCT), and AOSLO imaging. Split-detector images obtained in 11 subjects (7 RP, 4 Usher syndrome) were used to assess remnant cone structure in areas of altered cone reflectivity on confocal AOSLO. Despite normal interdigitation zone and ellipsoid zone appearance on OCT, foveal and parafoveal cone densities derived from confocal AOSLO images were significantly lower in Usher syndrome compared with RP. This was due in large part to an increased prevalence of non-waveguiding cones in the Usher syndrome retina. Although significantly correlated to best-corrected visual acuity and foveal sensitivity, cone density can decrease by nearly 38% before visual acuity becomes abnormal. Aberrantly waveguiding cones were noted within the transition zone of all eyes and corresponded to intact inner segment structures. These remnant cones decreased in density and increased in diameter across the transition zone and disappeared with external limiting membrane collapse. Foveal cone density can be decreased in RP and Usher syndrome before visible changes on OCT or a decline in visual function. Thus, AOSLO imaging may allow more sensitive monitoring of disease than current methods. However, confocal AOSLO is limited by dependence on cone waveguiding, whereas split-detector AOSLO offers unambiguous and quantifiable visualization of remnant cone inner segment structure. Confocal and split-detector thus offer complementary insights into retinal pathology.

Assessing Photoreceptor Structure in Retinitis Pigmentosa and Usher Syndrome

PubMed Central

Sun, Lynn W.; Johnson, Ryan D.; Langlo, Christopher S.; Cooper, Robert F.; Razeen, Moataz M.; Russillo, Madia C.; Dubra, Alfredo; Connor, Thomas B.; Han, Dennis P.; Pennesi, Mark E.; Kay, Christine N.; Weinberg, David V.; Stepien, Kimberly E.; Carroll, Joseph

2016-01-01

Purpose The purpose of this study was to examine cone photoreceptor structure in retinitis pigmentosa (RP) and Usher syndrome using confocal and nonconfocal split-detector adaptive optics scanning light ophthalmoscopy (AOSLO). Methods Nineteen subjects (11 RP, 8 Usher syndrome) underwent ophthalmic and genetic testing, spectral-domain optical coherence tomography (SD-OCT), and AOSLO imaging. Split-detector images obtained in 11 subjects (7 RP, 4 Usher syndrome) were used to assess remnant cone structure in areas of altered cone reflectivity on confocal AOSLO. Results Despite normal interdigitation zone and ellipsoid zone appearance on OCT, foveal and parafoveal cone densities derived from confocal AOSLO images were significantly lower in Usher syndrome compared with RP. This was due in large part to an increased prevalence of non-waveguiding cones in the Usher syndrome retina. Although significantly correlated to best-corrected visual acuity and foveal sensitivity, cone density can decrease by nearly 38% before visual acuity becomes abnormal. Aberrantly waveguiding cones were noted within the transition zone of all eyes and corresponded to intact inner segment structures. These remnant cones decreased in density and increased in diameter across the transition zone and disappeared with external limiting membrane collapse. Conclusions Foveal cone density can be decreased in RP and Usher syndrome before visible changes on OCT or a decline in visual function. Thus, AOSLO imaging may allow more sensitive monitoring of disease than current methods. However, confocal AOSLO is limited by dependence on cone waveguiding, whereas split-detector AOSLO offers unambiguous and quantifiable visualization of remnant cone inner segment structure. Confocal and split-detector thus offer complementary insights into retinal pathology. PMID:27145477

Dual-color STED microscopy reveals a sandwich structure of Bassoon and Piccolo in active zones of adult and aged mice.

PubMed

Nishimune, Hiroshi; Badawi, Yomna; Mori, Shuuichi; Shigemoto, Kazuhiro

2016-06-20

Presynaptic active zones play a pivotal role as synaptic vesicle release sites for synaptic transmission, but the molecular architecture of active zones in mammalian neuromuscular junctions (NMJs) at sub-diffraction limited resolution remains unknown. Bassoon and Piccolo are active zone specific cytosolic proteins essential for active zone assembly in NMJs, ribbon synapses, and brain synapses. These proteins are thought to colocalize and share some functions at active zones. Here, we report an unexpected finding of non-overlapping localization of these two proteins in mouse NMJs revealed using dual-color stimulated emission depletion (STED) super resolution microscopy. Piccolo puncta sandwiched Bassoon puncta and aligned in a Piccolo-Bassoon-Piccolo structure in adult NMJs. P/Q-type voltage-gated calcium channel (VGCC) puncta colocalized with Bassoon puncta. The P/Q-type VGCC and Bassoon protein levels decreased significantly in NMJs from aged mouse. In contrast, the Piccolo levels in NMJs from aged mice were comparable to levels in adult mice. This study revealed the molecular architecture of active zones in mouse NMJs at sub-diffraction limited resolution, and described the selective degeneration mechanism of active zone proteins in NMJs from aged mice. Interestingly, the localization pattern of active zone proteins described herein is similar to active zone structures described using electron microscope tomography.

Decreasing annual nest counts in a globally important loggerhead sea turtle population.

PubMed

Witherington, Blair; Kubilis, Paul; Brost, Beth; Meylan, Anne

2009-01-01

The loggerhead sea turtle (Caretta caretta) nests on sand beaches, has both oceanic and neritic life stages, and migrates internationally. We analyzed an 18-year time series of Index Nesting Beach Survey (Index) nest-count data to describe spatial and temporal trends in loggerhead nesting on Florida (USA) beaches. The Index data were highly resolved: 368 fixed zones (mean length 0.88 km) were surveyed daily during annual 109-day survey seasons. Spatial and seasonal coverage averaged 69% of estimated total nesting by loggerheads in the state. We carried out trend analyses on both annual survey-region nest-count totals (N = 18) and annual zone-level nest densities (N = 18 x 368 = 6624). In both analyses, negative binomial regression models were used to fit restricted cubic spline curves to aggregated nest counts. Between 1989 and 2006, loggerhead nest counts on Florida Index beaches increased and then declined, with a net decrease over the 18-year period. This pattern was evident in both a trend model of annual survey-region nest-count totals and a mixed-effect, "single-region" trend model of annual zone-level nest densities that took into account both spatial and temporal correlation between counts. We also saw this pattern in a zone-level model that allowed trend line shapes to vary between six coastal subregions. Annual mean zone-level nest density declined significantly (-28%; 95% CI: -34% to -21%) between 1989 and 2006 and declined steeply (-43%; 95% CI: -48% to -39%) during 1998-2006. Rates of change in annual mean nest density varied more between coastal subregions during the "mostly increasing" period prior to 1998 than during the "steeply declining" period after 1998. The excellent fits (observed vs. expected count R2 > 0.91) of the mixed-effect zone-level models confirmed the presence of strong, positive, within-zone autocorrelation (R > 0.93) between annual counts, indicating a remarkable year-to-year consistency in the longshore spatial distribution of nests over the survey region. We argue that the decline in annual loggerhead nest counts in peninsular Florida can best be explained by a decline in the number of adult female loggerheads in the population. Causes of this decline are explored.

[The effect of forest exploitation on structure, diversity, and floristic composition of palmito-dominated Atlantic forests at Misiones, Argentina].

PubMed

Chediack, Sandra E

2008-06-01

The effect of forest exploitation--timber and palmito (Euterpe edulis, Palmae) extraction--on structure, diversity, and floristic composition of forests known as palmitals of the Atlantic Forest of Argentina was analyzed. These palmitals are located in Misiones (54 degrees 13' W and 25 degrees 41' S). Three 1 ha permanent plots were established: two in the "intangible" zone of the Iguazu National Park (PNI), and another in an exploited forest site bordering the PNI. Three 0.2 ha non-permanent plots were also measured. One was located in the PNI reserve zone where illegal palmito extraction occurs. The other two were in logged forest. All trees and palmitos with DBH >10 cm were identified and DBH and height were measured. For each of the six sites, richness and diversity of tree species, floristic composition, number of endemic species, and density of harvestable tree species were estimated. The harvest of E. edulis increases density of other tree species, diminishing palmito density. Forest explotation (logging and palmito harvest) is accompanied by an increase in diversity and density of heliophilic species, which have greater timber value in the region. However, this explotation also diminishes the density of palmito, of endemic species which normally grow in low densities, and of species found on the IUCN Red List. Results suggest that forest structure may be managed for timber and palmito production. The "intangible" zone of the PNI has the greatest conservation value in the Atlantic Forest, since a greater number of endemisms and endangered species are found here.

Water quality assessment in the Mexican Caribbean: Impacts on the coastal ecosystem

NASA Astrophysics Data System (ADS)

Hernández-Terrones, Laura M.; Null, Kimberly A.; Ortega-Camacho, Daniela; Paytan, Adina

2015-07-01

Coastal zones are dominated by economically important ecosystems, and excessive urban, industrial, agricultural, and tourism activities can lead to rapid degradation of those habitats and resources. Groundwater in the Eastern Yucatan Peninsula coastal aquifer discharges directly into the coastal ocean affecting the coral reefs, which are part of the Mesoamerican Coral Reef System. The composition and impacts of groundwater were studied at different coastal environments around Akumal (SE Yucatan Peninsula). Radium isotopes and salinity were used to quantify fresh groundwater and recirculated seawater contributions to the coastal zone. Excess Ra distribution suggests spatially variable discharge rates of submarine groundwater. High NO3- levels and high coliform bacteria densities indicate that groundwater is polluted at some sites. Dissolved phosphorous content is elevated in the winter and during the high tourism season, likely released from untreated sewage discharge and from aquifer sediments under reducing conditions.

Distribution and sediment production of large benthic foraminifers on reef flats of the Majuro Atoll, Marshall Islands

NASA Astrophysics Data System (ADS)

Fujita, K.; Osawa, Y.; Kayanne, H.; Ide, Y.; Yamano, H.

2009-03-01

The distributions and population densities of large benthic foraminifers (LBFs) were investigated on reef flats of the Majuro Atoll, Marshall Islands. Annual sediment production by foraminifers was estimated based on population density data. Predominant LBFs were Calcarina and Amphistegina, and the population densities of these foraminifers varied with location and substratum type on reef flats. Both foraminifers primarily attached to macrophytes, particularly turf-forming algae, and were most abundant on an ocean reef flat (ORF) and in an inter-island channel near windward, sparsely populated islands. Calcarina density was higher on windward compared to leeward sides of ORFs, whereas Amphistegina density was similar on both sides of ORFs. These foraminifers were more common on the ocean side relative to the lagoon side of reef flats around a windward reef island, and both were rare or absent in nearshore zones around reef islands and on an ORF near windward, densely populated islands. Foraminiferal production rates varied with the degree to which habitats were subject to water motion and human influences. Highly productive sites (>103 g CaCO3 m-2 year-1) included an ORF and an inter-island channel near windward, sparsely populated islands, and a seaward area of a reef flat with no reef islands. Low-productivity sites (<10 g CaCO3 m-2 year-1) included generally nearshore zones of lagoonal reef flats, leeward ORFs, and a windward ORF near densely populated islands. These results suggest that the distribution and production of LBFs were largely influenced by a combination of natural environmental factors, including water motion, water depth, elevation relative to the lowest tidal level at spring tide, and the distribution of suitable substratum. The presence of reef islands may limit the distribution and production of foraminifers by altering water circulation in nearshore environments. Furthermore, increased anthropogenic factors (population and activities) may adversely affect foraminiferal distribution and production.

Do microplastic loads reflect the population demographics along the southern African coastline?

PubMed

Nel, Holly Astrid; Hean, Jeffrey William; Noundou, Xavier Siwe; Froneman, Pierre William

2017-02-15

Plastic pollution is a major anthropogenic contaminant effecting the marine environment and is often associated with high human population densities and industrial activities. The microplastic (63 to 5000μm) burden of beach sediment and surf-zone water was investigated at selected sites along the entire length of the South African coastline. It was predicted that samples collected in areas of high population density, would contain a higher microplastic burden than those along coasts that demonstrate very low population densities. With the exception of water column microplastics within Richard's Bay Harbour (413.3±77.53particles·m -3 ) and Durban Harbour (1200±133.2particles·m -3 ), there were no significant spatial differences in microplastic loads. This supports the theory that harbours act as a source of microplastics for the surrounding marine environment. Additionally, the absence of any spatial variation highlights the possible long range distribution of microplastic pollutants by large scale ocean currents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Runout distance and dynamic pressure of pyroclastic density currents: Evidence from 18 May 1980 blast surge of Mount St. Helens

NASA Astrophysics Data System (ADS)

Gardner, J. E.; Andrews, B. J.

2016-12-01

Pyroclastic density currents (flows and surges) are one of the most deadly hazards associated with volcanic eruptions. Understanding what controls how far such currents will travel, and how their dynamic pressure evolves, could help mitigate their hazards. The distance a ground hugging, pyroclastic density current travels is partly limited by when it reverses buoyancy and lifts off into the atmosphere. The 1980 blast surge of Mount St. Helens offers an example of a current seen to lift off. Before lofting, it had traveled up to 20 km and leveled more than 600 km3 of thick forest (the blowdown zone). The outer edge of the devastated area - where burned trees that were left standing (the singe zone) - is where the surge is thought to have lifted off. We recently examined deposits in the outer parts of the blowdown and in the singe zone at 32 sites. The important finding is that the laterally moving surge travelled into the singe zone, and hence the change in tree damage does not mark the run out distance of the ground hugging surge. Eyewitness accounts and impacts on trees and vehicles reveal that the surge consisted of a fast, dilute "overcurrent" and a slower "undercurrent", where most of the mass (and heat) was retained. Reasonable estimates for flow density and velocity show that dynamic pressure of the surge (i.e., its ability to topple trees) peaked near the base of the overcurrent. We propose that when the overcurrent began to lift off, the height of peak dynamic pressure rose above the trees and stopped toppling them. The slower undercurrent continued forward, burning trees but it lacked the dynamic pressure needed to topple them. Grain-size variations argue that it slowed from 30 m/s when it entered the singe zone to 3 m/s at the far end. Buoyancy reversal and liftoff are thus not preserved in the deposits where the surge lofted upwards.

Hunting, law enforcement, and African primate conservation.

PubMed

N'Goran, Paul K; Boesch, Christophe; Mundry, Roger; N'Goran, Eliezer K; Herbinger, Ilka; Yapi, Fabrice A; Kühl, Hjalmar S

2012-06-01

Primates are regularly hunted for bushmeat in tropical forests, and systematic ecological monitoring can help determine the effect hunting has on these and other hunted species. Monitoring can also be used to inform law enforcement and managers of where hunting is concentrated. We evaluated the effects of law enforcement informed by monitoring data on density and spatial distribution of 8 monkey species in Taï National Park, Côte d'Ivoire. We conducted intensive surveys of monkeys and looked for signs of human activity throughout the park. We also gathered information on the activities of law-enforcement personnel related to hunting and evaluated the relative effects of hunting, forest cover and proximity to rivers, and conservation effort on primate distribution and density. The effects of hunting on monkeys varied among species. Red colobus monkeys (Procolobus badius) were most affected and Campbell's monkeys (Cercopithecus campbelli) were least affected by hunting. Density of monkeys irrespective of species was up to 100 times higher near a research station and tourism site in the southwestern section of the park, where there is little hunting, than in the southeastern part of the park. The results of our monitoring guided law-enforcement patrols toward zones with the most hunting activity. Such systematic coordination of ecological monitoring and law enforcement may be applicable at other sites. ©2012 Society for Conservation Biology.

Hard time to be parents? Sea urchin fishery shifts potential reproductive contribution of population onto the shoulders of the young adults.

PubMed

Loi, Barbara; Guala, Ivan; Pires da Silva, Rodrigo; Brundu, Gianni; Baroli, Maura; Farina, Simone

2017-01-01

In Sardinia, as in other regions of the Mediterranean Sea, sustainable fisheries of the sea urchin Paracentrotus lividus have become a necessity. At harvesting sites, the systematic removal of large individuals (diameter ≥ 50 mm) seriously compromises the biological and ecological functions of sea urchin populations. Specifically, in this study, we compared the reproductive potential of the populations from Mediterranean coastal areas which have different levels of sea urchin fishing pressure. The areas were located at Su Pallosu Bay, where pressure is high and Tavolara-Punta Coda Cavallo, a marine protected area where sea urchin harvesting is low. Reproductive potential was estimated by calculating the gonadosomatic index (GSI) from June 2013 to May 2014 both for individuals of commercial size (diameter without spines, TD ≥ 50 mm) and the undersized ones with gonads (30 ≤ TD < 40 mm and 40 ≤ TD < 50 mm). Gamete output was calculated for the commercial-size class and the undersized individuals with fertile gonads (40 ≤ TD < 50 mm) in relation to their natural density (gamete output per m 2 ). The reproductive potential of populations was slightly different at the beginning of the sampling period but it progressed at different rates with an early spring spawning event in the high-pressure zone and two gamete depositions in early and late spring in the low-pressure zone. For each fertile size class, GSI values changed significantly during the year of our study and between the two zones. Although the multiple spawning events determined a two-fold higher total gamete output of population (popTGO) in the low-pressure zone, the population mean gamete output (popMGO) was similar in the two zones. In the high-pressure zone, the commercial-sized individuals represented approximatively 5% of the population, with almost all the individuals smaller than 60 mm producing an amount of gametes nearly three times lower than the undersized ones. Conversely, the high density of the undersized individuals released a similar amount of gametes to the commercial-size class in the low-pressure zone. Overall, the lack of the commercial-size class in the high-pressure zone does not seem to be very alarming for the self-supporting capacity of the population, and the reproductive potential contribution seems to depend more on the total density of fertile sea urchins than on their size. However, since population survival in the high-pressure zone is supported by the high density of undersized sea urchins between 30 and 50 mm, management measures should be addressed to maintain these sizes and to shed light on the source of the larval supply.

Hard time to be parents? Sea urchin fishery shifts potential reproductive contribution of population onto the shoulders of the young adults

PubMed Central

Guala, Ivan; Pires da Silva, Rodrigo; Brundu, Gianni; Baroli, Maura; Farina, Simone

2017-01-01

Background In Sardinia, as in other regions of the Mediterranean Sea, sustainable fisheries of the sea urchin Paracentrotus lividus have become a necessity. At harvesting sites, the systematic removal of large individuals (diameter ≥ 50 mm) seriously compromises the biological and ecological functions of sea urchin populations. Specifically, in this study, we compared the reproductive potential of the populations from Mediterranean coastal areas which have different levels of sea urchin fishing pressure. The areas were located at Su Pallosu Bay, where pressure is high and Tavolara-Punta Coda Cavallo, a marine protected area where sea urchin harvesting is low. Methods Reproductive potential was estimated by calculating the gonadosomatic index (GSI) from June 2013 to May 2014 both for individuals of commercial size (diameter without spines, TD ≥ 50 mm) and the undersized ones with gonads (30 ≤ TD < 40 mm and 40 ≤ TD < 50 mm). Gamete output was calculated for the commercial-size class and the undersized individuals with fertile gonads (40 ≤ TD < 50 mm) in relation to their natural density (gamete output per m2). Results The reproductive potential of populations was slightly different at the beginning of the sampling period but it progressed at different rates with an early spring spawning event in the high-pressure zone and two gamete depositions in early and late spring in the low-pressure zone. For each fertile size class, GSI values changed significantly during the year of our study and between the two zones. Although the multiple spawning events determined a two-fold higher total gamete output of population (popTGO) in the low-pressure zone, the population mean gamete output (popMGO) was similar in the two zones. In the high-pressure zone, the commercial-sized individuals represented approximatively 5% of the population, with almost all the individuals smaller than 60 mm producing an amount of gametes nearly three times lower than the undersized ones. Conversely, the high density of the undersized individuals released a similar amount of gametes to the commercial-size class in the low-pressure zone. Discussion Overall, the lack of the commercial-size class in the high-pressure zone does not seem to be very alarming for the self-supporting capacity of the population, and the reproductive potential contribution seems to depend more on the total density of fertile sea urchins than on their size. However, since population survival in the high-pressure zone is supported by the high density of undersized sea urchins between 30 and 50 mm, management measures should be addressed to maintain these sizes and to shed light on the source of the larval supply. PMID:28289567

Spatial characterization of innervation zones under electrically elicited M-wave.

PubMed

Zhang, C; Peng, Y; Li, S; Zhou, P; Munoz, A; Tang, D; Zhang, Y

2016-08-01

The three dimensional (3D) innervation zone (IZ) imaging approach (3DIZI) has been developed in our group to localize the IZ of a particular motor unit (MU) from its motor unit action potentials decomposed from high-density surface electromyography (EMG) recordings. In this study, the developed 3DIZI approach was combined with electrical stimulation to investigate global distributions of IZs in muscles from electrically elicited M-wave recordings. Electrical stimulations were applied to the musculocutaneous nerve to activate supramaximal muscle response of the biceps brachii in one healthy subject, and high-density (128 channels) surface EMG signals of the biceps brachii muscles were recorded. The 3DIZI approach was then employed to image the IZ distribution of IZs in the 3D space of the biceps brachii. The performance of the M-wave based 3DIZI approach was evaluated with different stimulation intensities. Results show that the reconstructed IZs under supramaximal stimulation are spatially distributed in the center region of muscle belly which is consistent with previous studies. With sub-maximal stimulation intensity, the imaged IZ centers became more proximally and deeply located. The proposed M-wave based 3DIZI approach demonstrated its capability of imaging global distribution of IZs in muscles, which provide valuable information for clinical applications such as guiding botulinum toxin injection in treating muscle spasticity.

Platelet-Derived Growth Factor Promotes Repair of Chronically Demyelinated White Matter

PubMed Central

Vana, Adam C.; Flint, Nicole C.; Harwood, Norah E.; Le, Tuan Q.; Fruttiger, Marcus; Armstrong, Regina C.

2009-01-01

In multiple sclerosis, remyelination becomes limited after repeated or prolonged episodes of demyelination. To test the effect of platelet-derived growth factor-A (PDGF-A) in recovery from chronic demyelination we induced corpus callosum demyelination using cuprizone treatment in hPDGF-A transgenic (tg) mice with the human PDGF-A gene under control of an astrocyte-specific promoter. After chronic demyelination and removal of cuprizone from the diet, remyelination and oligodendrocyte density improved significantly in hPDGF-A tg mice compared with wild-type mice. In hPDGF-A tg mice, oligodendrocyte progenitor density and proliferation values were increased in the corpus callosum during acute demyelination but not during chronic demyelination or the subsequent recovery period, compared with hPDGF-A tg mice without cuprizone or to treatment-matched wild-type mice. Proliferation within the subventricular zone and subcallosal zone was elevated throughout cuprizone treatment but was not different between hPDGF-A tg and wild-type mice. Importantly, hPDGF-A tg mice had reduced apoptosis in the corpus callosum during the recovery period after chronic demyelination. Therefore, PDGF-A may support oligodendrocyte generation and survival to promote remyelination of chronic lesions. Furthermore, preventing oligodendrocyte apoptosis may be important not only during active demyelination but also for supporting the generation of new oligodendrocytes to remyelinate chronic lesions. PMID:17984680

[Influence of preoperative bone mass density in periprosthetic bone remodeling after implantation of ABG-II prosthesis: A 10-year follow-up].

PubMed

Aguilar Ezquerra, A; Panisello Sebastiá, J J; Mateo Agudo, J

2016-01-01

Preoperative bone mass index has shown to be an important factor in peri-prosthetic bone remodelling in short follow-up studies. Bone density scans (DXA) were used to perform a 10-year follow-up study of 39 patients with a unilateral, uncemented hip replacement. Bone mass index measurements were made at 6 months, one year, 3 years, 5 years, and 10 years after surgery. Pearson coefficient was used to quantify correlations between preoperative bone mass density (BMD) and peri-prosthetic BMD in the 7 Gruen zones at 6 months, one year, 3 years, 5 years, and 10 years. Pre-operative BMD was a good predictor of peri-prosthetic BMD one year after surgery in zones 1, 2, 4, 5 and 6 (Pearson index from 0.61 to 0.75). Three years after surgery it has good predictive power in zones 1, 4 and 5 (0.71-0.61), although in zones 3 and 7 low correlation was observed one year after surgery (0.51 and 0.57, respectively). At the end of the follow-up low correlation was observed in the 7 Gruen zones. Sex and BMI were found to not have a statistically significant influence on peri-prosthetic bone remodelling. Although preoperative BMD seems to be an important factor in peri-prosthetic remodelling one year after hip replacement, it loses its predictive power progressively, until not being a major factor in peri-prosthetic remodelling ten years after surgery. Copyright © 2015 SECOT. Published by Elsevier Espana. All rights reserved.

Exploring seismicity using geomagnetic and gravity data - a case study for Bulgaria

NASA Astrophysics Data System (ADS)

Trifonova, P.; Simeonova, S.; Solakov, D.; Metodiev, M.

2012-04-01

Seismicity exploration certainly requires comprehensive analysis of location, orientation and length distribution of fault and block systems with a variety of geophysical methods. In the present research capability of geomagnetic and gravity anomalous field data are used for revealing of buried structures inside the earth's upper layers. Interpretation of gravity and magnetic data is well known and often applied to delineate various geological structures such as faults, flexures, thrusts, borders of dislocated blocks etc. which create significant rock density contrast in horizontal planes. Study area of the present research covers the territory of Bulgaria which is part of the active continental margin of the Eurasian plate. This region is a typical example of high seismic risk area. The epicentral map shows that seismicity in the region is not uniformly distributed in space. Therefore the seismicity is described in distributed geographical zones (seismic source zones). Each source zone is characterized by its specific tectonic, seismic, and geological particulars. From the analysis of the depth distribution it was recognized that the earthquakes in the region occurred in the Earth's crust. Hypocenters are mainly located in the upper crust, and only a few events are related to the lower crust. The maximum depth reached is about 50 km in southwestern Bulgaria; outside, the foci affect only the surficial 30-35 km. Maximum density of seismicity involves the layer between 5 and 25 km. This fact determines the capability of potential fields data to reveal crustal structures and to examine their parameters as possible seismic sources. Results showed that a number of geophysically interpreted structures coincide with observed on the surface dislocations and epicenter clusters (well illustrated in northern Bulgaria) which confirms the reliability of the applied methodology. The complicated situation in southern Bulgaria is demonstrated by mosaics structure of geomagnetic field, complex configuration of gravity anomalies and spatial seismicity distribution. Well defined (confirmed by geophysical, geological and seismological data) are the known earthquake source zones (such as Sofia, Kresna, Maritsa, Yambol ) in this part of the territory of Bulgaria. Worth while are the results where no surface structures are present (e.g. Central Rhodope zone and East Rhodope zone, where the 2006 Kurdzhali earthquake sequence is realized). In those cases, gravity and magnetic interpretations proved to be a suitable enough technique which allows determining of position and parameters of the geological structures in depth.

Axial length variation impacts on retinal vessel density and foveal avascular zone area measurement using optical coherence tomography angiography

NASA Astrophysics Data System (ADS)

Sampson, Danuta M.; Gong, Peijun; An, Di; Menghini, Moreno; Hansen, Alex; Mackey, David A.; Sampson, David D.; Chen, Fred K.

2017-04-01

We examined the impact of axial length on superficial retinal vessel density (SRVD) and foveal avascular zone area (FAZA) measurement using optical coherence tomography angiography. The SRVD and FAZA were quantified before and after correction for magnification error associated with axial length variation. Although SRVD did not differ before and after correction for magnification error in the parafoveal region, change in foveal SRVD and FAZA were significant. This has implications for clinical trials outcome in diseased eyes where significant capillary dropout may occur in the parafovea.

Liprin-α3 controls vesicle docking and exocytosis at the active zone of hippocampal synapses.

PubMed

Wong, Man Yan; Liu, Changliang; Wang, Shan Shan H; Roquas, Aram C F; Fowler, Stephen C; Kaeser, Pascal S

2018-02-27

The presynaptic active zone provides sites for vesicle docking and release at central nervous synapses and is essential for speed and accuracy of synaptic transmission. Liprin-α binds to several active zone proteins, and loss-of-function studies in invertebrates established important roles for Liprin-α in neurodevelopment and active zone assembly. However, Liprin-α localization and functions in vertebrates have remained unclear. We used stimulated emission depletion superresolution microscopy to systematically determine the localization of Liprin-α2 and Liprin-α3, the two predominant Liprin-α proteins in the vertebrate brain, relative to other active-zone proteins. Both proteins were widely distributed in hippocampal nerve terminals, and Liprin-α3, but not Liprin-α2, had a prominent component that colocalized with the active-zone proteins Bassoon, RIM, Munc13, RIM-BP, and ELKS. To assess Liprin-α3 functions, we generated Liprin-α3-KO mice by using CRISPR/Cas9 gene editing. We found reduced synaptic vesicle tethering and docking in hippocampal neurons of Liprin-α3-KO mice, and synaptic vesicle exocytosis was impaired. Liprin-α3 KO also led to mild alterations in active zone structure, accompanied by translocation of Liprin-α2 to active zones. These findings establish important roles for Liprin-α3 in active-zone assembly and function, and suggest that interplay between various Liprin-α proteins controls their active-zone localization.

Preparation of active antibacterial LDPE surface through multistep physicochemical approach: I. Allylamine grafting, attachment of antibacterial agent and antibacterial activity assessment.

PubMed

Bílek, František; Křížová, Táňa; Lehocký, Marián

2011-11-01

Low-density polyethylene (LDPE) samples were treated in air plasma discharge, coated by polyallyamine brush thought copolymeric grafting surface-from reaction and deposited four common antibacterial agents (benzalkonium chloride, bronopol, chlorhexidine and triclosan) to gain material with active antibacterial properties. Surface characteristics were evaluated by static contact angle measurement with surface energy evaluation ATR-FTIR, X-ray Photoelectron Spectroscopy (XPS) and SEM analysis. Inhibition zone on agar was used as in vitro test of antibacterial properties on two representative gram positive Staphylococcus aureus (S. aureus) and gram negative Escherichia coli (E. coli) strains. It was confirmed, that after grafting of polyallyamine, more antibacterial agent is immobilized on the surface. The highest increase of antibacterial activity was observed by the sample containing triclosan. Samples covered by bronopol did not show significant antibacterial activity. Copyright © 2011 Elsevier B.V. All rights reserved.

The neural correlates of dreaming.

PubMed

Siclari, Francesca; Baird, Benjamin; Perogamvros, Lampros; Bernardi, Giulio; LaRocque, Joshua J; Riedner, Brady; Boly, Melanie; Postle, Bradley R; Tononi, Giulio

2017-06-01

Consciousness never fades during waking. However, when awakened from sleep, we sometimes recall dreams and sometimes recall no experiences. Traditionally, dreaming has been identified with rapid eye-movement (REM) sleep, characterized by wake-like, globally 'activated', high-frequency electroencephalographic activity. However, dreaming also occurs in non-REM (NREM) sleep, characterized by prominent low-frequency activity. This challenges our understanding of the neural correlates of conscious experiences in sleep. Using high-density electroencephalography, we contrasted the presence and absence of dreaming in NREM and REM sleep. In both NREM and REM sleep, reports of dream experience were associated with local decreases in low-frequency activity in posterior cortical regions. High-frequency activity in these regions correlated with specific dream contents. Monitoring this posterior 'hot zone' in real time predicted whether an individual reported dreaming or the absence of dream experiences during NREM sleep, suggesting that it may constitute a core correlate of conscious experiences in sleep.

Earthquake clustering in modern seismicity and its relationship with strong historical earthquakes around Beijing, China

NASA Astrophysics Data System (ADS)

Wang, Jian; Main, Ian G.; Musson, Roger M. W.

2017-11-01

Beijing, China's capital city, is located in a typical intraplate seismic belt, with relatively high-quality instrumental catalogue data available since 1970. The Chinese historical earthquake catalogue contains six strong historical earthquakes of Ms ≥ 6 around Beijing, the earliest in 294 AD. This poses a significant potential hazard to one of the most densely populated and economically active parts of China. In some intraplate areas, persistent clusters of events associated with historical events can occur over centuries, for example, the ongoing sequence in the New Madrid zone of the eastern US. Here we will examine the evidence for such persistent clusters around Beijing. We introduce a metric known as the `seismic density index' that quantifies the degree of clustering of seismic energy release. For a given map location, this multi-dimensional index depends on the number of events, their magnitudes, and the distances to the locations of the surrounding population of earthquakes. We apply the index to modern instrumental catalogue data between 1970 and 2014, and identify six clear candidate zones. We then compare these locations to earthquake epicentre and seismic intensity data for the six largest historical earthquakes. Each candidate zone contains one of the six historical events, and the location of peak intensity is within 5 km or so of the reported epicentre in five of these cases. In one case—the great Ms 8 earthquake of 1679—the peak is closer to the area of strongest shaking (Intensity XI or more) than the reported epicentre. The present-day event rates are similar to those predicted by the modified Omori law but there is no evidence of ongoing decay in event rates. Accordingly, the index is more likely to be picking out the location of persistent weaknesses in the lithosphere. Our results imply zones of high seismic density index could be used in principle to indicate the location of unrecorded historical of palaeoseismic events, in China and elsewhere.

The role of sexual vs. asexual recruitment of Artemisia wudanica in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China

NASA Astrophysics Data System (ADS)

Wang, Yongcui; Alberto, Busso Carlos; Jiang, Deming; Ala, Musa; Li, Xuehua; Zhou, Quanlai; Lin, Jixiang; Ren, Guohua; Jia, Lian

2016-04-01

Artemisia wudanica is an endemic, perennial, pioneering psammophyte species in the sand dune ecosystems of western Horqin Sand Land in northern China. However, no studies have addressed how sexual and asexual reproduction modes of A. wudanica perform at the transitional zones between active dune inter-dune lowlands and active dunes. In early spring, quadrats were randomly set up in the study area to monitor surviving seedling and/or ramet density and frequency coming from sexual/asexual reproduction of A. wudanica. Iron sticks were inserted near each quadrat to determine wind erosion intensity (WE). Additionally, soil samples were collected nearby each quadrat to test for soil moisture (SM), organic matter (OM) and pH. Surviving seedlings of A. wudanica showed an inverse response in comparison with ramets to SM, OM and WE. Soil moisture showed the most positive effect, and WE the negative effect, on surviving, sexual reproduction seedlings. Contrarily, WE had the most positive effect, and SM the negative effect, on asexual reproduction ramets. This suggests that increases in SM and decreases in WE should benefit recruitment of A. wudanica seedlings. On the contrary, ramets coming from asexual reproduction showed a different response to environmental factors in transition zone habitats. While SM was not a key constraint for the survival of seedlings, they showed a better, positive response to wind erosion environments. Overall, various study environmental parameters could be improved to foster A. wudanica invasion and settlement in the plant community through different reproductive modes, thereby promoting vegetation restoration and rehabilitation.

Response of deformation patterns to reorganization of the southern San Andreas fault system since ca. 1.5 Ma

NASA Astrophysics Data System (ADS)

Fattaruso, Laura A.; Cooke, Michele L.; Dorsey, Rebecca J.; Housen, Bernard A.

2016-12-01

Between 1.5 and 1.1 Ma, the southern San Andreas fault system underwent a major reorganization that included initiation of the San Jacinto fault zone and termination of slip on the extensional West Salton detachment fault. The southern San Andreas fault itself has also evolved since this time, with several shifts in activity among fault strands within San Gorgonio Pass. We use three-dimensional mechanical Boundary Element Method models to investigate the impact of these changes to the fault network on deformation patterns. A series of snapshot models of the succession of active fault geometries explore the role of fault interaction and tectonic loading in abandonment of the West Salton detachment fault, initiation of the San Jacinto fault zone, and shifts in activity of the San Andreas fault. Interpreted changes to uplift patterns are well matched by model results. These results support the idea that initiation and growth of the San Jacinto fault zone led to increased uplift rates in the San Gabriel Mountains and decreased uplift rates in the San Bernardino Mountains. Comparison of model results for vertical-axis rotation to data from paleomagnetic studies reveals a good match to local rotation patterns in the Mecca Hills and Borrego Badlands. We explore the mechanical efficiency at each step in the modeled fault evolution, and find an overall trend toward increased efficiency through time. Strain energy density patterns are used to identify regions of incipient faulting, and support the notion of north-to-south propagation of the San Jacinto fault during its initiation.

Zooxanthellae harvested by ciliates associated with brown band syndrome of corals remain photosynthetically competent.

PubMed

Ulstrup, Karin E; Kühl, Michael; Bourne, David G

2007-03-01

Brown band syndrome is a new coral affliction characterized by a local accumulation of yet-unidentified ciliates migrating as a band along the branches of coral colonies. In the current study, morphologically intact zooxanthellae (= Symbiodinium) were observed in great numbers inside the ciliates (>50 dinoflagellates per ciliate). Microscale oxygen measurements and variable chlorophyll a fluorescence analysis along with microscopic observations demonstrated that zooxanthellae within the ciliates are photosynthetically competent and do not become compromised during the progression of the brown band zone. Zooxanthellae showed similar trends in light acclimation in a comparison of rapid light curve and steady-state light curve measures of variable chlorophyll a fluorescence. Extended light exposure of steady-state light curves resulted in higher quantum yields of photosystem II. The brown band tissue exhibited higher photosynthetically active radiation absorptivity, indicating more efficient light absorption due to a higher density of zooxanthellae in the ciliate-dominated zone. This caused relatively higher gross photosynthesis rates in the zone with zooxanthella-containing ciliates compared to healthy coral tissue. The observation of photosynthetically active intracellular zooxanthellae in the ciliates suggests that the latter can benefit from photosynthates produced by ingested zooxanthellae and from photosynthetic oxygen production that alleviates diffusion limitation of oxic respiration in the densely populated brown band tissue. It remains to be shown whether the zooxanthellae form a stable symbiotic association with the ciliate or are engulfed incidentally during grazing on coral tissue and then maintained as active inside the ciliate for a period before being digested and replaced by new zooxanthellae.

Zooxanthellae Harvested by Ciliates Associated with Brown Band Syndrome of Corals Remain Photosynthetically Competent▿

PubMed Central

Ulstrup, Karin E.; Kühl, Michael; Bourne, David G.

2007-01-01

Brown band syndrome is a new coral affliction characterized by a local accumulation of yet-unidentified ciliates migrating as a band along the branches of coral colonies. In the current study, morphologically intact zooxanthellae (= Symbiodinium) were observed in great numbers inside the ciliates (>50 dinoflagellates per ciliate). Microscale oxygen measurements and variable chlorophyll a fluorescence analysis along with microscopic observations demonstrated that zooxanthellae within the ciliates are photosynthetically competent and do not become compromised during the progression of the brown band zone. Zooxanthellae showed similar trends in light acclimation in a comparison of rapid light curve and steady-state light curve measures of variable chlorophyll a fluorescence. Extended light exposure of steady-state light curves resulted in higher quantum yields of photosystem II. The brown band tissue exhibited higher photosynthetically active radiation absorptivity, indicating more efficient light absorption due to a higher density of zooxanthellae in the ciliate-dominated zone. This caused relatively higher gross photosynthesis rates in the zone with zooxanthella-containing ciliates compared to healthy coral tissue. The observation of photosynthetically active intracellular zooxanthellae in the ciliates suggests that the latter can benefit from photosynthates produced by ingested zooxanthellae and from photosynthetic oxygen production that alleviates diffusion limitation of oxic respiration in the densely populated brown band tissue. It remains to be shown whether the zooxanthellae form a stable symbiotic association with the ciliate or are engulfed incidentally during grazing on coral tissue and then maintained as active inside the ciliate for a period before being digested and replaced by new zooxanthellae. PMID:17259357

Bacterioplankton communities of Crater Lake, OR: Dynamic changes with euphotic zone food web structure and stable deep water populations

USGS Publications Warehouse

Urbach, E.; Vergin, K.L.; Larson, G.L.; Giovannoni, S.J.

2007-01-01

The distribution of bacterial and archaeal species in Crater Lake plankton varies dramatically over depth and with time, as assessed by hybridization of group-specific oligonucleotides to RNA extracted from lakewater. Nonmetric, multidimensional scaling (MDS) analysis of relative bacterial phylotype densities revealed complex relationships among assemblages sampled from depth profiles in July, August and September of 1997 through 1999. CL500-11 green nonsulfur bacteria (Phylum Chloroflexi) and marine Group I crenarchaeota are consistently dominant groups in the oxygenated deep waters at 300 and 500 m. Other phylotypes found in the deep waters are similar to surface and mid-depth populations and vary with time. Euphotic zone assemblages are dominated either by ??-proteobacteria or CL120-10 verrucomicrobia, and ACK4 actinomycetes. MDS analyses of euphotic zone populations in relation to environmental variables and phytoplankton and zooplankton population structures reveal apparent links between Daphnia pulicaria zooplankton population densities and microbial community structure. These patterns may reflect food web interactions that link kokanee salmon population densities to community structure of the bacterioplankton, via fish predation on Daphnia with cascading consequences to Daphnia bacterivory and predation on bacterivorous protists. These results demonstrate a stable bottom-water microbial community. They also extend previous observations of food web-driven changes in euphotic zone bacterioplankton community structure to an oligotrophic setting. ?? 2007 Springer Science+Business Media B.V.

Response of Ca2+-ATPase to clinorotaion of pea seedlings. O. M. Nedukha and E. L. Kordyum

NASA Astrophysics Data System (ADS)

Nedukha, Olena

2016-07-01

The present study was aimed to reveal of response of Ca2+-ATPase activity of cortex cells in distal elongation zone of Pisum sativum root to slow clinorotation. Pea seedlings were grown on a horizontal clinostat (2 rpm) and in the stationary control for 6 days. The electron-cytochemical method was used to examine the effects of imitated microgravity on the distribution of Ca2+-ATPase in outer layers of root cortex. The quantitative analysis of the density of cytochemical reaction products was measured using the Image J program. Electron microscopy showed the presence of electron-dense lead phosphate precipitated grains, the enzymatic activity reaction products on the plasma membrane, membranes of vesicular structures, endoplasmic reticulum (ER) and on organelles envelope in both of samples of the stationary control and clinorotated seedlings. We revealed the sensitivity of Ca2+-ATPase to clinorotation. The quantitative analysis of the area and density of enzymatic activity reaction products revealed that clinorotation led to the decrease of 3.4 times the density of reaction products on the plasma membrane and the increase of reaction products density on endomembranes and organelles membranes, in particular: in 2.2 times on mitochondria membranes; in 1.3 times - on membranes of ER; in 2.5 times - on tonoplast; by an order of magnitude greater - on contacting membranes of organelles with plasma membrane in comparison with such in cells of control samples. The data analysis can indicate an intensification of calcium pump on endomembranes, on envelopes of cytoplasmic organelles and nucleus. The obtained data suggest that the redistribution of Ca2+-ATPase activity in cells can be mediated by the activation of certain isoforms of enzyme or/and by an activation of Ca2+/H+ antiporter in plasma membrane that helps to maintain optimal calcium balance in plant cells under imitated microgravity.

Conduits and dike distribution analysis in San Rafael Swell, Utah

NASA Astrophysics Data System (ADS)

Kiyosugi, K.; Connor, C.; Wetmore, P. H.; Ferwerda, B. P.; Germa, A.

2011-12-01

Volcanic fields generally consist of scattered monogenetic volcanoes, such as cinder cones and maars. The temporal and spatial distribution of monogenetic volcanoes and probability of future activity within volcanic fields is studied with the goals of understanding the origins of these volcano groups, and forecasting potential future volcanic hazards. The subsurface magmatic plumbing systems associated with volcanic fields, however, are rarely observed or studied. Therefore, we investigated a highly eroded and exposed magmatic plumbing system on the San Rafael Swell (UT) that consists of dikes, volcano conduits and sills. San Rafael Swell is part of the Colorado Plateau and is located east of the Rocky Mountain seismic belt and the Basin and Range. The overburden thickness at the time of mafic magma intrusion (Pliocene; ca. 4 Ma) into Jurassic sandstone is estimated to be ~800 m based on paleotopographical reconstructions. Based on a geologic map by P. Delaney and colleagues, and new field research, a total of 63 conduits are mapped in this former volcanic field. The conduits each reveal features of root zone and / or lower diatremes, including rapid dike expansion, peperite and brecciated intrusive and host rocks. Recrystallized baked zone of host rock is also observed around many conduits. Most conduits are basaltic or shonkinitic with thickness of >10 m and associated with feeder dikes intruded along N-S trend joints in the host rock, whereas two conduits are syenitic and suggesting development from underlying cognate sills. Conduit distribution, which is analyzed by a kernel function method with elliptical bandwidth, illustrates a N-S elongate higher conduit density area regardless of the azimuth of closely distributed conduits alignment (nearest neighbor distance <200 m). In addition, dike density was calculated as total dike length in unit area (km/km^2). Conduit and sill distribution is concordant with the high dike density area. Especially, the distribution of conduits is not random with respect to the dike distribution with greater than 99% confidence on the basis of the Kolmogorov-Smirnov test. On the other hand, dike density at each conduits location also suggests that there is no threshold of dike density for conduit formation. In other words, conduits may be possible to develop from even short mapped dikes in low dike density areas. These results show effectiveness of studying volcanic vent distribution to infer the size of magmatic system below volcanic fields and highlight the uncertainty of forecasting the location of new monogenetic volcanoes in active fields, which may be associated with a single dike intrusion.

Desensitization shortens the high-quantal-content endplate current time course in frog muscle with intact cholinesterase.

PubMed

Giniatullin, R A; Talantova, M; Vyskocil, F

1997-08-01

1. The desensitization induced by bath-applied carbachol or acetylcholine (ACh) and potentiated by proadifen (SKF 525A) was studied in the frog sartorius with intact synaptic acetylcholinesterase (AChE). 2. The reduction in the density and number of postsynaptic receptors produced by desensitization lowered the amplitude of the endplate currents (EPCs) and shortened the EPC decay when the quantal content (m) of the EPC was about 170 and when multiple release of quanta at single active zones was highly probably. The shortening of high-quantal-content EPCs persisted for at least 15 min after the wash-out of agonists, at a time when the amplitude had recovered fully. 3. The decay times of the low-quantal-content EPCs recorded from preparations pretreated with 5 mM Mg2+ (m approximately 70) and single-quantum miniature endplate currents (MEPCs) were not affected by carbachol, ACh or proadifen. 4. The desensitization of ACh receptors potentiated by proadifen, prevented completely the 6- to 8-fold prolongation of EPC which was induced by neostigmine inhibition of synaptic AChE. 5. It is assumed that high-quantal-content EPCs increase the incidence of multiple quanta release at single active zones and the probability of repetitive binding of ACh molecules which leads to EPC prolongation. The shortening which persists after complete recovery of the amplitude during wash-out of the exogenous agonist is probably due to 'trapping' of ACh molecules onto rapidly desensitized receptors and the reduced density of functional AChRs during the quantum action.

C-O-H-N fluids circulations and graphite precipitation in reactivated Hudsonian shear zones during basement uplift of the Wollaston-Mudjatik Transition Zone: Example of the Cigar Lake U deposit

NASA Astrophysics Data System (ADS)

Martz, Pierre; Cathelineau, Michel; Mercadier, Julien; Boiron, Marie-Christine; Jaguin, Justine; Tarantola, Alexandre; Demacon, Mickael; Gerbeaud, Olivier; Quirt, David; Doney, Amber; Ledru, Patrick

2017-12-01

Graphitic shear zones are spatially associated with unconformity-related uranium deposits that are located around the unconformity between the strata of the Paleo- to Mesoproterozoic Athabasca Basin (Saskatchewan, Canada) and its underlying Archean to Paleoproterozoic basement. The present study focuses on basement-hosted ductile-brittle graphitic shear zones near the Cigar Lake U deposit, one of the largest unconformity-related U deposits. The goal of the study is to decipher the pre-Athabasca Basin fluid migration history recorded within such structures and its potential role on the formation of such exceptional deposit. Dominantly C-O-H(-N) metamorphic fluids have been trapped in Fluid Inclusion Planes (FIPs) in magmatic quartz within ductile-brittle graphitic shear zones active during retrograde metamorphism associated with the formation of the Wollaston-Mudjatik Transition Zone (WMTZ) between ca. 1805 and 1720 Ma. Such fluids show a compositional evolution along the retrograde path, from a dense and pure CO2 fluid during the earliest stages, through a lower density CO2 ± CH4-N2 (± H2O) fluid and, finally, to a very low density CH4-N2 fluid. Statistical study of the orientation, distribution, proportion, and chemical characterization of the FIPs shows that: i) CO2 (δ13CCO2 around - 9‰ PDB) from decarbonation reactions and/or partial water-metamorphic graphite equilibrium initially migrated regionally and pervasively under lithostatic conditions at about 500 to 800 °C and 150 to 300 MPa. Such P-T conditions attest to a high geothermal gradient of around 60 to 90 °C/km, probably related to rapid exhumation of the basement or a large-scale heat source. ii) Later brittle reactivation of the shear zone at around 450 °C and 25-50 MPa favored circulation of CO2-CH4-N2(± H2O) fluids in equilibrium with metamorphic graphite (δ13CCO2 around - 14‰) under hydrostatic conditions and only within the shear zones. Cooling of these fluids and the water uptake linked to fluid-basement rock reactions led to the precipitation at around 450 °C of poorly-crystallized hydrothermal graphite. This graphite presents isotopic (δ13C - 30 to - 26‰ PDB) and morphological differences from the high-T metamorphic graphite (> 600 °C, - 29 to - 20‰ δ13C) derived from metamorphism of C-rich sedimentary material. The brittle structural reactivation and the related fluid migration and graphite precipitation were specifically focused within the shear zones and related damage zones. The brittle reactivation produced major changes in the petro-physical, mineralogical, and chemical characteristics of the structures and their damage zones. It especially increased the fracture paleoporosity and rock weakness toward the fault cores. These major late metamorphic modifications of the graphitic shear zones were likely key parameters favoring the enhanced reactivity of these basement zones under tectonic stress following deposition of the Athabasca Basin, and so controlled basinal brine movement at the basin/basement interface related to the formation of the unconformity-related uranium deposits. This relationship consequently readily explains the specific spatial relationships between unconformity-related U deposits and the ductile-brittle graphitic shear zones.

EUV observations of quiescent prominences from Skylab

NASA Technical Reports Server (NTRS)

Moe, O. K.; Cook, J. W.; Mango, S. A.

1979-01-01

Measurements of line intensities and line widths for three quiescent prominences observed with Naval Research Laboratory slit spectrograph on ATM/Skylab are reported. The wavelengths of the observed lines cover the range 1175 A to 1960 A. The measured intensities have been calibrated to within approximately a factor 2 and are average intensities over a 2 arcsec by 60 arcsec slit. Nonthermal velocities from the measured line widths are derived. The nonthermal velocity is found to increase with temperature in the prominence transition zone. Electron densities and pressures are derived from density sensitive line ratios. Electron pressures for two of the prominences are found to lie in the range 0.04-0.08 dyn/sq cm, while values for the third and most intense and active of the three prominences are in the range 0.07-0.22 dyn/sq cm.

Seismic Hazard Legislation in California: Challenges and Changes

NASA Astrophysics Data System (ADS)

Testa, S. M.

2015-12-01

Seismic hazards in California are legislatively controlled by three specific Acts: the Field Act of 1933; the Alquist-Priolo Earthquake Fault Zoning Act (AP) of 1975; and the Seismic Hazards Mapping Act (SHMA) of 1980. The Field Act recognized the need for earthquake resistant construction for California schools and banned unreinforced masonry buildings, and imposed structural design under seismic conditions. The AP requires the California Geological Survey (CGS) to delineate "active fault zones" for general planning and mitigation by various state and local agencies. Under the AP, surface and near-surface faults are presumed active (about 11,000 years before present) unless proven otherwise; and can only be mitigated by avoidance (setback zones). The SHMA requires that earthquake-induced landslides, liquefaction zones, high ground accelerations, tsunamis and seiches similarly be demarcated on CGS-issued maps. Experience over the past ~45 years and related technological advances now show that more than ~95 percent of seismically induced damage and loss of life stems from high ground accelerations, from related ground deformation and from catastrophic structural failure, often far beyond State-mapped AP zones. The SHMA therefore enables the engineering community to mitigate natural hazards from a holistic standpoint that considers protection of public health, safety and welfare. In conformance with the SHMA, structural design and related planning and building codes focus on acceptable risk for natural hazards with a typical recurrence of ~100 yrs to a few thousand years. This contrasts with the current AP "total avoidance" for surface-fault rupture that may have occurred within the last 11,000 years. Accordingly, avoidance may be reasonable for well expressed surface faults in high-density urban areas or where relative fault activity is uncertain. However, in the interest of overall public, health and safety, and for consistency with the SHMA and current professional standards-of-practice, we now propose changes to the AP and related regulations, including consideration for permitting construction near or across surface or near-surface faults that are geologically reasonably well characterized and amenable to structural mitigation.

Preliminary study of near surface detections at geothermal field using optic and SAR imageries

NASA Astrophysics Data System (ADS)

Kurniawahidayati, Beta; Agoes Nugroho, Indra; Syahputra Mulyana, Reza; Saepuloh, Asep

2017-12-01

Current remote sensing technologies shows that surface manifestation of geothermal system could be detected with optical and SAR remote sensing, but to assess target beneath near the surface layer with the surficial method needs a further study. This study conducts a preliminary result using Optic and SAR remote sensing imagery to detect near surface geothermal manifestation at and around Mt. Papandayan, West Java, Indonesia. The data used in this study were Landsat-8 OLI/TIRS for delineating geothermal manifestation prospect area and an Advanced Land Observing Satellite(ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) level 1.1 for extracting lineaments and their density. An assumption was raised that the lineaments correlated with near surface structures due to long L-band wavelength about 23.6 cm. Near surface manifestation prospect area are delineated using visual comparison between Landsat 8 RGB True Colour Composite band 4,3,2 (TCC), False Colour Composite band 5,6,7 (FCC), and lineament density map of ALOS PALSAR. Visual properties of ground object were distinguished from interaction of the electromagnetic radiation and object whether it reflect, scatter, absorb, or and emit electromagnetic radiation based on characteristic of their molecular composition and their macroscopic scale and geometry. TCC and FCC composite bands produced 6 and 7 surface manifestation zones according to its visual classification, respectively. Classified images were then compared to a Normalized Different Vegetation Index (NDVI) to obtain the influence of vegetation at the ground surface to the image. Geothermal area were classified based on vegetation index from NDVI. TCC image is more sensitive to the vegetation than FCC image. The later composite produced a better result for identifying visually geothermal manifestation showed by detail-detected zones. According to lineament density analysis high density area located on the peak of Papandayan overlaid with zone 1 and 2 of FCC. Comparing to the extracted lineament density, we interpreted that the near surface manifestation is located at zone 1 and 2 of FCC image.

Earthquake Rupture at Focal Depth, Part I: Structure and Rupture of the Pretorius Fault, TauTona Mine, South Africa

NASA Astrophysics Data System (ADS)

Heesakkers, V.; Murphy, S.; Reches, Z.

2011-12-01

We analyze the structure of the Archaean Pretorius fault in TauTona mine, South Africa, as well as the rupture-zone that recently reactivated it. The analysis is part of the Natural Earthquake Laboratory in South African Mines (NELSAM) project that utilizes the access to 3.6 km depth provided by the mining operations. The Pretorius fault is a ~10 km long, oblique-strike-slip fault with displacement of up to 200 m that crosscuts fine to very coarse grain quartzitic rocks in TauTona mine. We identify here three structural zones within the fault-zone: (1) an outer damage zone, ~100 m wide, of brittle deformation manifested by multiple, widely spaced fractures and faults with slip up to 3 m; (2) an inner damage zone, 25-30 m wide, with high density of anastomosing conjugate sets of fault segments and fractures, many of which carry cataclasite zones; and (3) a dominant segment, with a cataclasite zone up to 50 cm thick that accommodated most of the Archaean slip of the Pretorius fault, and is regarded as the `principal slip zone' (PSZ). This fault-zone structure indicates that during its Archaean activity, the Pretorius fault entered the mature fault stage in which many slip events were localized along a single, PSZ. The mining operations continuously induce earthquakes, including the 2004, M2.2 event that rejuvenated the Pretorius fault in the NELSAM project area. Our analysis of the M2.2 rupture-zone shows that (1) slip occurred exclusively along four, pre-existing large, quasi-planer segments of the ancient fault-zone; (2) the slipping segments contain brittle cataclasite zones up to 0.5 m thick; (3) these segments are not parallel to each other; (4) gouge zones, 1-5 mm thick, composed of white `rock-flour' formed almost exclusively along the cataclasite-host rock contacts of the slipping segments; (5) locally, new, fresh fractures branched from the slipping segments and propagated in mixed shear-tensile mode; (6) the maximum observed shear displacement is 25 mm in oblique-normal slip. The mechanical analysis of this rupture-zone is presented in Part II (H eesakkers et al., Earthquake Rupture at Focal Depth, Part II: Mechanics of the 2004 M2.2 Earthquake Along the Pretorius Fault, TauTona mine, South Africa 2011, this volume).

Electrophoretic separator for purifying biologicals

NASA Technical Reports Server (NTRS)

1976-01-01

This technique separates a single narrow zone of sample mixture in an electrolyte medium into many zones containing a single component of the mixture and electrolyte between them. Since the densities of the separated zones generally differ from that of the intervening medium, such systems are gravitationally unstable and stabilization is required. The various techniques for stabilization include using the capillary space provided by thin films, the interstices of solid material such as filter paper and a variety of gel-forming substances.

A Survey of Aflatoxin-Producing Aspergillus sp. from Peanut Field Soils in Four Agroecological Zones of China

PubMed Central

Zhang, Chushu; Selvaraj, Jonathan Nimal; Yang, Qingli; Liu, Yang

2017-01-01

Peanut pods are easily infected by aflatoxin-producing Aspergillus sp.ecies from field soil. To assess the aflatoxin-producing Aspergillus sp. in different peanut field soils, 344 aflatoxin-producing Aspergillus strains were isolated from 600 soil samples of four agroecological zones in China (the Southeast coastal zone (SEC), the Yangtze River zone (YZR), the Yellow River zone (YR) and the Northeast zone (NE)). Nearly 94.2% (324/344) of strains were A. flavus and 5.8% (20/344) of strains were A. parasiticus. YZR had the highest population density of Aspergillus sp. and positive rate of aflatoxin production in isolated strains (1039.3 cfu·g−1, 80.7%), the second was SEC (191.5 cfu·g−1, 48.7%), the third was YR (26.5 cfu·g−1, 22.7%), and the last was NE (2.4 cfu·g−1, 6.6%). The highest risk of AFB1 contamination on peanut was in YZR which had the largest number of AFB1 producing isolates in 1g soil, followed by SEC and YR, and the lowest was NE. The potential risk of AFB1 contamination in peanuts can increase with increasing population density and a positive rate of aflatoxin-producing Aspergillus sp. in field soils, suggesting that reducing aflatoxigenic Aspergillus sp. in field soils could prevent AFB1 contamination in peanuts. PMID:28117685

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

NASA Astrophysics Data System (ADS)

Whitfield, A. K.

1989-12-01

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

A Survey of Aflatoxin-Producing Aspergillus sp. from Peanut Field Soils in Four Agroecological Zones of China.

PubMed

Zhang, Chushu; Selvaraj, Jonathan Nimal; Yang, Qingli; Liu, Yang

2017-01-20

Peanut pods are easily infected by aflatoxin-producing Aspergillus sp.ecies from field soil. To assess the aflatoxin-producing Aspergillus sp. in different peanut field soils, 344 aflatoxin-producing Aspergillus strains were isolated from 600 soil samples of four agroecological zones in China (the Southeast coastal zone (SEC), the Yangtze River zone (YZR), the Yellow River zone (YR) and the Northeast zone (NE)). Nearly 94.2% (324/344) of strains were A. flavus and 5.8% (20/344) of strains were A. parasiticus . YZR had the highest population density of Aspergillus sp. and positive rate of aflatoxin production in isolated strains (1039.3 cfu·g -1 , 80.7%), the second was SEC (191.5 cfu·g -1 , 48.7%), the third was YR (26.5 cfu·g -1 , 22.7%), and the last was NE (2.4 cfu·g -1 , 6.6%). The highest risk of AFB₁ contamination on peanut was in YZR which had the largest number of AFB₁ producing isolates in 1g soil, followed by SEC and YR, and the lowest was NE. The potential risk of AFB₁ contamination in peanuts can increase with increasing population density and a positive rate of aflatoxin-producing Aspergillus sp. in field soils, suggesting that reducing aflatoxigenic Aspergillus sp. in field soils could prevent AFB₁ contamination in peanuts.

Gravity study through the Tualatin Mountains, Oregon: Understanding crustal structure and earthquake hazards in the Portland urban area

USGS Publications Warehouse

Blakely, R.J.; Beeson, M.H.; Cruikshank, K.; Wells, R.E.; Johnson, Aaron H.; Walsh, K.

2004-01-01

A high-resolution gravity survey through the Tualatin Mountains (Portland Nills) west of downtown Portland exhibits evidence of faults previously identified from surface geologic and aeromagnetic mapping. The gravity survey was conducted in 1996 along the 4.5-km length of a twin-bore tunnel, then under construction and now providing light-rail service between downtown Portland and communities west of the Portland Hills. Gravitational attraction gradually increases from west to east inside the tunnel, which reflects the tunnel's location between low-density sedimentary deposits of the Tualatin basin to the west and high-density, mostly concealed Eocene basalt to the east. Superimposed on this gradient are several steplike anomalies that we interpret as evidence for faulted contacts between rocks of contrasting density. The largest of these anomalies occurs beneath Sylvan Creek, where a fault had previously been mapped inside the tunnel. Another occurs 1200 m from the west portal, at the approximate intersection of the tunnel with an aeromagnetic anomaly associated with the Sylvan fault (formerly called the Oatfield fault). Lithologic cross sections based on these gravity data show that the steplike anomalies are consistent with steeply dipping reverse faults, although strike-slip displacements also may be important. Three gravity lows correspond with topographic lows directly overhead and may reflect zones of shearing. Several moderate earthquakes (M ??? 3.5) occurred near the present-day location of the tunnel in 1991, suggesting that some of these faults or other faults in the Portland Hills fault zone are seismically active.

Density and Habitat Relationships of the Endemic White Mountain Fritillary (Boloria chariclea montinus) (Lepidoptera: Nymphalidae).

PubMed

McFarland, Kent P; Lloyd, John D; Hardy, Spencer P

2017-06-04

We conducted point counts in the alpine zone of the Presidential Range of the White Mountains, New Hampshire, USA, to estimate the distribution and density of the rare endemic White Mountain Fritillary ( Boloria chariclea montinus ). Incidence of occurrence and density of the endemic White Mountain Fritillary during surveys in 2012 and 2013 were greatest in the herbaceous-snowbank plant community. Densities at points in the heath-shrub-rush plant community were lower, but because this plant community is more widespread in the alpine zone, it likely supports the bulk of adult fritillaries. White Mountain Fritillary used cushion-tussock, the other alpine plant community suspected of providing habitat, only sparingly. Detectability of White Mountain Fritillaries varied as a consequence of weather conditions during the survey and among observers, suggesting that raw counts yield biased estimates of density and abundance. Point counts, commonly used to study and monitor populations of birds, were an effective means of sampling White Mountain Fritillary in the alpine environment where patches of habitat are small, irregularly shaped, and widely spaced, rendering line-transect methods inefficient and difficult to implement.

Approach for computing 1D fracture density: application to fracture corridor characterization

NASA Astrophysics Data System (ADS)

Viseur, Sophie; Chatelée, Sebastien; Akriche, Clement; Lamarche, Juliette

2016-04-01

Fracture density is an important parameter for characterizing fractured reservoirs. Many stochastic simulation algorithms that generate fracture networks indeed rely on the determination of a fracture density on volumes (P30) to populate the reservoir zones with individual fracture surfaces. However, only 1D fracture density (P10) are available from subsurface data and it is then important to be able to accurately estimate this entity. In this paper, a novel approach is proposed to estimate fracture density from scan-line or well data. This method relies on regression, hypothesis testing and clustering techniques. The objective of the proposed approach is to highlight zones where fracture density are statistically very different or similar. This technique has been applied on both synthetic and real case studies. These studies concern fracture corridors, which are particular tectonic features that are generally difficult to characterize from subsurface data. These tectonic features are still not well known and studies must be conducted to better understand their internal spatial organization and variability. The presented synthetic cases aim at showing the ability of the approach to extract known features. The real case study illustrates how this approach allows the internal spatial organization of fracture corridors to be characterized.

Magmatic densities control erupted volumes in Icelandic volcanic systems

NASA Astrophysics Data System (ADS)

Hartley, Margaret; Maclennan, John

2018-04-01

Magmatic density and viscosity exert fundamental controls on the eruptibility of magmas. In this study, we investigate the extent to which magmatic physical properties control the eruptibility of magmas from Iceland's Northern Volcanic Zone (NVZ). By studying subaerial flows of known age and volume, we are able to directly relate erupted volumes to magmatic physical properties, a task that has been near-impossible when dealing with submarine samples dredged from mid-ocean ridges. We find a strong correlation between magmatic density and observed erupted volumes on the NVZ. Over 85% of the total volume of erupted material lies close to a density and viscosity minimum that corresponds to the composition of basalts at the arrival of plagioclase on the liquidus. These magmas are buoyant with respect to the Icelandic upper crust. However, a number of small-volume eruptions with densities greater than typical Icelandic upper crust are also found in Iceland's neovolcanic zones. We use a simple numerical model to demonstrate that the eruption of magmas with higher densities and viscosities is facilitated by the generation of overpressure in magma chambers in the lower crust and uppermost mantle. This conclusion is in agreement with petrological constraints on the depths of crystallisation under Iceland.

Investigation of the geologic setting and geomorphic processes that control the formation and preservation of precarious rock zones

NASA Astrophysics Data System (ADS)

Haddad, D.; Arrowsmith, R.

2008-12-01

Zones of precariously balanced rocks have been used as negative indicators of previous strong ground motion in seismically active regions of Southern California and Nevada (e.g. Brune 1996). Understanding the geologic context and the geomorphic framework that control the formation and preservation of precarious rocks is essential to testing their fidelity for extreme ground motion analyses. In this study we assess the geologic settings and the geomorphic processes nested within them using precarious rock zones (Granite Dells, Texas Canyon, and Granite Pediment) in low-seismicity regions of Arizona and Southern California. The Granite Dells locality is a ~20 km2 Proterozoic granite field that is ~5 km from the Prescott Valley graben faults (<0.2 mm/yr of Quaternary slip). The Texas Canyon locality is a ~132 km2 Mesozoic granite field that is ~23 km from the Little Rincon Mountains fault (<0.2 mm/yr of Quaternary slip). The Granite Pediment locality is a ~12 km2 Mesozoic granite pediment located ~96 km from the eastern section of the Garlock fault (<5 mm/yr of Quaternary slip). Characterization of the geologic context of each site included assembling a digital geologic database for Arizona, Southern California, and southern Nevada. The geologic database was queried for granitic bodies and Quaternary deposits. Active faults were categorized by their Quaternary slip rates, and a 20 km zone of no precarious rocks was created around each active fault based on the field surveys of Brune (1996). Aerial photographs were used to map the spatial distribution and geometry of joint sets within each site. Ground surveys using hand-held GPS units and digital photography were conducted to document the characteristics (lithology, size, fragility, weathering characteristics) and spatial density of precariously balanced rocks. Morphometric analyses of digital elevation data may indicate if there is a slope or relief range which the precarious rocks are optimally produced and/or preserved.

Localization of the interband transitions in the bulk of the Brillouin zone of III–V compound crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sobolev, V. V., E-mail: sobolev@uni.udm.ru; Perevoshchikov, D. A.

2016-05-15

The localization of the transitions in the bulk of the Brillouin zone that form the main structures in the spectra of the imaginary part of the permittivity in the range up to ~7 eV for III–V semiconductors (AlSb, GaSb, InSb, and InAs) is determined using electron density functional theory. It is established that intense transitions occur not only in the vicinity of the high-symmetry axes of the Brillouin zone, but also in some specific large volumes of the irreducible part of the Brillouin zone.

Structure and composition of streamside management zones following reproduction cutting in shortleaf pine stands

Treesearch

Hal O. Liechty; James M. Guldin

2009-01-01

Streamside management zones (SMZs) in the Ouachita Mountains of Arkansas and Oklahoma are frequently established along headwater ephemeral and intermittent streams to protect water quality, provide wildlife habitat, and increase landscape diversity. To better understand the function of these riparian forest corridors, we characterized the tree density and composition,...

Exploiting the locality of periodic subsystem density-functional theory: efficient sampling of the Brillouin zone.

PubMed

Genova, Alessandro; Pavanello, Michele

2015-12-16

In order to approximately satisfy the Bloch theorem, simulations of complex materials involving periodic systems are made n(k) times more complex by the need to sample the first Brillouin zone at n(k) points. By combining ideas from Kohn-Sham density-functional theory (DFT) and orbital-free DFT, for which no sampling is needed due to the absence of waves, subsystem DFT offers an interesting middle ground capable of sizable theoretical speedups against Kohn-Sham DFT. By splitting the supersystem into interacting subsystems, and mapping their quantum problem onto separate auxiliary Kohn-Sham systems, subsystem DFT allows an optimal topical sampling of the Brillouin zone. We elucidate this concept with two proof of principle simulations: a water bilayer on Pt[1 1 1]; and a complex system relevant to catalysis-a thiophene molecule physisorbed on a molybdenum sulfide monolayer deposited on top of an α-alumina support. For the latter system, a speedup of 300% is achieved against the subsystem DTF reference by using an optimized Brillouin zone sampling (600% against KS-DFT).

Integrating geospatial and ground geophysical information as guidelines for groundwater potential zones in hard rock terrains of south India.

PubMed

Rashid, Mehnaz; Lone, Mahjoor Ahmad; Ahmed, Shakeel

2012-08-01

The increasing demand of water has brought tremendous pressure on groundwater resources in the regions were groundwater is prime source of water. The objective of this study was to explore groundwater potential zones in Maheshwaram watershed of Andhra Pradesh, India with semi-arid climatic condition and hard rock granitic terrain. GIS-based modelling was used to integrate remote sensing and geophysical data to delineate groundwater potential zones. In the present study, Indian Remote Sensing RESOURCESAT-1, Linear Imaging Self-Scanner (LISS-4) digital data, ASTER digital elevation model and vertical electrical sounding data along with other data sets were analysed to generate various thematic maps, viz., geomorphology, land use/land cover, geology, lineament density, soil, drainage density, slope, aquifer resistivity and aquifer thickness. Based on this integrated approach, the groundwater availability in the watershed was classified into four categories, viz. very good, good, moderate and poor. The results reveal that the modelling assessment method proposed in this study is an effective tool for deciphering groundwater potential zones for proper planning and management of groundwater resources in diverse hydrogeological terrains.

Upper crustal densities derived from sea floor gravity measurements: Northern Juan De Fuca Ridge

USGS Publications Warehouse

Holmes, Mark L.; Johnson, H. Paul

1993-01-01

A transect of sea floor gravity stations has been analyzed to determine upper crustal densities on the Endeavour segment of the northern Juan de Fuca Ridge. Data were obtained using ALVIN along a corridor perpendicular to the axis of spreading, over crustal ages from 0 to 800,000 years. Calculated elevation factors from the gravity data show an abrupt increase in density with age (distance) for the upper 200 m of crust. This density change is interpreted as a systematic reduction in bulk porosity of the upper crustal section, from 23% for the axial ridge to 10% for the off-axis flanking ridges. The porosity decrease is attributed to the collapse and filling of large-scale voids as the abyssal hills move out of the crustal formation zone. Forward modeling of a plausible density structure for the near-axis region agrees with the observed anomaly data only if the model includes narrow, along-strike, low-density regions adjacent to both inner and outer flanks of the abyssal hills. The required low density zones could be regions of systematic upper crustal fracturing and faulting that were mapped by submersible observers and side-scan sonar images, and whose presence was suggested by the distribution of heat flow data in the same area.

Current Seismicity in the Vicinity of Yucca Mountain, Nevada

NASA Astrophysics Data System (ADS)

Smith, K.; von Seggern, D.; dePolo, D.

2001-12-01

The 1992 to 2000 earthquakes in the Southern Great Basin have been relocated in order to better recognize the active tectonic processes in the vicinity of Yucca Mountain. During this time period seismic monitoring in the Southern Great Basin transitioned from a primarily single-component analog network to a 3-component digital network. Through the transition analog and digital networks were run in tandem. The station density over this period is as great as any prior recording period. The analog and digital networks were administered separately during the transition, and we have merged the phase data from the two operations. We performed relocations starting in October 1992, thus creating a hypocentral list for FY1993-FY2000. Aftershocks of the June 1992 M 5.6 Little Skull Mountain earthquake, located approximately 20 km southeast of Yucca Mountain, dominate the seismicity in the Southern Great Basin from 1992-2000. After the Little Skull Mountain earthquake, there was a general increase in earthquake activity in southern NTS, principally associated with the Rock Valley fault zone. There was no corresponding increase in seismicity west of Little Skull Mountain near the potential repository site. The distribution of high-quality earthquake locations generally reflects trends in Miocene tectonism. In particular, a general north-south trending gravity low, interpreted by Carr (1984) as the Kawich-Greenwater Rift, is highlighted by the microseismicity in many areas. Locally small magnitude earthquakes tend to outline the 8-10 Ma Timber Mountain caldera in northern and central NTS. Although these structures do not generally correlate with Quaternary faults, the micro-earthquake activity may reflect zones of weakness within these older structures. A 100 km long, conspicuous, north-south trending seismic zone, which shows no correlation with know Quaternary features, aligns along the steep gravity gradient bordering the western side of the Kawich-Greenwater gravity structure. This apparently is an indication that at least some of the seismicity near Yucca Mountain is driven by density contrasts in the lower crust or upper mantle as well as by low regional tectonic strain rates. Overall, the seismicity near Yucca Mountain is low compared to other areas of the southern Great Basin and to the west in the Eastern California Shear Zone. We have calculated the Coulomb stress changes on Yucca Mountain area faults due to large (M > 7) faulting events on the Furnace Creek Fault Zone and interpreted this result in terms of the implications for understanding the distribution of the current seismicity. Because of the significant difference in the Quaternary geologic slip rates between the Furnace Creek and Yucca Mountain area faults (a factor of 250-500) and the stress modeling results, we investigate the hypothesis that the Furnace Creek and Death Valley faults act to decrease the long-term recurrence rate for normal faulting events in the Yucca Mountain block.

Defining Incipient Subduction by Detecting Serpentenised Mantle in the Regional Magnetic Field

NASA Astrophysics Data System (ADS)

Pires, Rui; Clark, Stuart; Reis, Rui

2017-04-01

Keywords: Subduction initiation, Incipient Subduction, Active Margins, Southeast Asia, Mantle wedge The mechanisms of subduction initiation are poorly understood. One idea is to look for incipient subduction zones in the present day and see what features are common in these zones. However, incipient subduction zones are very difficult to detect and debate surrounds particular cases as to whether they qualify as incipient or not. In the analysis conducted in this work, we use the signal of the presence of a mantle wedge in the magnetic anomaly field as an indicator of incipient subduction. Each subduction zone exhibits variations in the particular responses of the system, such as slab-dip angle, maximum earthquake depths and volcanism to various parameters. So far, attempts to reduce the system to a dominate controlling parameter have failed, probably as a result of the limited number of cases and the large variety of controlling parameters. Parameters such as down-going and overriding plate morphology and velocity, mantle flow, the presence of plumes or not, sediment transport into the trench are a few of the parameters that have been studied in the literature. However, one of the characteristics associated with a subduction zones is the presence of a mantelic wedge as a result of the partial melt of the subducting plate and the development of a mantle wedge between the subducting plate and the overriding plate. The wedge is characterised by the presence of water (coming from sediments in the down-going plate) as well as lower temperatures (because the wedge is between two relatively cold lithospheres). As a results a serpentinized mantle wedge is formed that contains hydrous minerals, of which magnetite is an example, that alter the composition and properties of this region. According to Blakely et.al. (2005), this region exhibits both higher magnetic susceptibility and lower densities than the surrounding medium. We analysed five active margin boundaries located worldwide to investigate the link between magnetic and gravity anomalies and seismic activity and slab structure. In the Southeast Asia region, transects were taken in the Andaman, Sumatra, Marianas and Philippines, while the Central American region is represented by the Ecuadorian subduction zone. The Magnetic data was obtained from the World Digital Magnetic Anomaly Map (WDMAM), the gravimetric data from the International Gravimetric Bureau while data on seismic activity and slab structure was obtained from the USGS earthquake hazards program. We present an initial investigation on the correlation of magnetic and gravimetric anomalies on the one-hand and seismic activity and slab structure on the other to search for patterns that can help detect mantelic wedges and incipient subduction and further our understanding of subduction initiation processes. References Blakely, R.J., Brocher, T.M., Wells, R.E., 2005. Subduction-zone magnetic anomalies and implications for hydrated forearc mantle. Geology 33, 445-448.

Metamorphic density controls on early-stage subduction dynamics

NASA Astrophysics Data System (ADS)

Duesterhoeft, Erik; Oberhänsli, Roland; Bousquet, Romain

2013-04-01

Subduction is primarily driven by the densification of the downgoing oceanic slab, due to dynamic P-T-fields in subduction zones. It is crucial to unravel slab densification induced by metamorphic reactions to understand the influence on plate dynamics. By analyzing the density and metamorphic structure of subduction zones, we may gain knowledge about the driving, metamorphic processes in a subduction zone like the eclogitization (i.e., the transformation of a MORB to an eclogite), the breakdown of hydrous minerals and the release of fluid or the generation of partial melts. We have therefore developed a 2D subduction zone model down to 250 km that is based on thermodynamic equilibrium assemblage computations. Our model computes the "metamorphic density" of rocks as a function of pressure, temperature and chemical composition using the Theriak-Domino software package at different time stages. We have used this model to investigate how the hydration, dehydration, partial melting and fractionation processes of rocks all influence the metamorphic density and greatly depend on the temperature field within subduction systems. These processes are commonly neglected by other approaches (e.g., gravitational or thermomechanical in nature) reproducing the density distribution within this tectonic setting. The process of eclogitization is assumed as being important to subduction dynamics, based on the very high density (3.6 g/cm3) of eclogitic rocks. The eclogitization in a MORB-type crust is possible only if the rock reaches the garnet phase stability field. This process is primarily temperature driven. Our model demonstrates that the initiation of eclogitization of the slab is not the only significant process that makes the descending slab denser and is responsible for the slab pull force. Indeed, our results show that the densification of the downgoing lithospheric mantle (due to an increase of pressure) starts in the early subduction stage and makes a significant contribution to the slab pull, where eclogitization does not occur. Thus, the lithospheric mantle acts as additional ballast below the sinking slab shortly after the initiation of subduction. Our calculation shows that the dogma of eclogitized basaltic, oceanic crust as the driving force of slab pull is overestimated during the early stage of subduction. These results improve our understanding of the force budget for slab pull during the intial and early stage of subduction. Therefore, the complex metamorphic structure of a slab and mantle wedge has an important impact on the development and dynamics of subduction zones. Further Reading: Duesterhoeft, Oberhänsli & Bousquet (2013), submitted to Earth and Planetary Science Letters

Denitrification potential of riparian soils in relation to multiscale spatial environmental factors: a case study of a typical watershed, China.

PubMed

Wei, Jianbing; Feng, Hao; Cheng, Quanguo; Gao, Shiqian; Liu, Haiyan

2017-02-01

The objective of this study was to test the hypothesis that environmental regulators of riparian zone soil denitrification potential differ according to spatial scale within a watershed; consequently, a second objective was to provide spatial strategies for conserving and restoring the purification function of runoff in riparian ecosystems. The results show that soil denitrification in riparian zones was more heterogeneous at the profile scale than at the cross-section and landscape scales. At the profile scale, biogeochemical factors (including soil total organic carbon, total nitrogen, and nitrate-nitrogen) were the major direct regulators of the spatial distribution of soil denitrification enzyme activity (DEA). At the cross-section scale, factors included distance from river bank and vegetation density, while landscape-scale factors, including topographic index, elevation, and land use types, indirectly regulated the spatial distribution of DEA. At the profile scale, soil DEA was greatest in the upper soil layers. At the cross-section scale, maximum soil DEA occurred in the mid-part of the riparian zone. At the landscape scale, soil DEA showed an increasing trend towards downstream sites, except for those in urbanized areas.

Quantitative Characterisation of Fracturing Around the Damage Zone Surrounding New Zealand's Alpine Fault Using X-ray CT Scans of DFDP-1 Core

NASA Astrophysics Data System (ADS)

Williams, J. N.; Toy, V.; Massiot, C.; Mcnamara, D. D.; Wang, T.

2015-12-01

X-ray computer tomography (CT) scans of core recovered from the first phase of the Deep Fault Drilling Project (DFDP-1) through the Alpine Fault provide an excellent opportunity to analyse brittle deformation around the fault. In particular, assessment can be made of the heavily fractured protolith constituting the damage zone. Damage zone structures are divided into two types that result from two distinct processes: (1) "off fault damage" formed by stress changes induced by the passage of a seismic rupture and (2) "off fault deformation" that represent structures, which accommodate strain around the fault that was not localised on the principal slip zone (PSZ). The distribution of these damage zones structures within CT scans of the recovered core was measured along a scanline parallel to the core axis and assessed using a weighted moving average technique to account for orientation bias. The results of this analysis reveal that within the part of the fault rocks sampled by DFDP-1 there is no increase in density of these structures towards the PSZ. This is in agreement with independent analysis using Borehole Televiewer Data of the DFDP-1B borehole. Instead, we consider the density of these structures to be controlled to the first order by lithology, which modulates the mechanical properties of the fault rocks such as its frictional strength and cohesion. Comparisons of fracture density to p-wave velocities obtained from wireline logs indicate they are independent of each other, therefore, for the cores sampled in this study fractures impart no influence on the elastic properties of the rock. This is consistent with the observation from core that the majority of fractures are cemented. We consider how this might influence future rupture dynamics.

High gain photoconductive semiconductor switch having tailored doping profile zones

DOEpatents

Baca, Albert G.; Loubriel, Guillermo M.; Mar, Alan; Zutavern, Fred J; Hjalmarson, Harold P.; Allerman, Andrew A.; Zipperian, Thomas E.; O'Malley, Martin W.; Helgeson, Wesley D.; Denison, Gary J.; Brown, Darwin J.; Sullivan, Charles T.; Hou, Hong Q.

2001-01-01

A photoconductive semiconductor switch with tailored doping profile zones beneath and extending laterally from the electrical contacts to the device. The zones are of sufficient depth and lateral extent to isolate the contacts from damage caused by the high current filaments that are created in the device when it is turned on. The zones may be formed by etching depressions into the substrate, then conducting epitaxial regrowth in the depressions with material of the desired doping profile. They may be formed by surface epitaxy. They may also be formed by deep diffusion processes. The zones act to reduce the energy density at the contacts by suppressing collective impact ionization and formation of filaments near the contact and by reducing current intensity at the contact through enhanced current spreading within the zones.

Parkin Deficiency Reduces Hippocampal Glutamatergic Neurotransmission by Impairing AMPA Receptor Endocytosis.

PubMed

Cortese, Giuseppe P; Zhu, Mei; Williams, Damian; Heath, Sarah; Waites, Clarissa L

2016-11-30

Mutations in the gene encoding Parkin, an E3 ubiquitin ligase, lead to juvenile-onset Parkinson's disease by inducing the selective death of midbrain dopaminergic neurons. Accumulating evidence indicates that Parkin also has an important role in excitatory glutamatergic neurotransmission, although its precise mechanism of action remains unclear. Here, we investigate Parkin's role at glutamatergic synapses of rat hippocampal neurons. We find that Parkin-deficient neurons exhibit significantly reduced AMPA receptor (AMPAR)-mediated currents and cell-surface expression, and that these phenotypes result from decreased postsynaptic expression of the adaptor protein Homer1, which is necessary for coupling AMPAR endocytic zones with the postsynaptic density. Accordingly, Parkin loss of function leads to the reduced density of postsynaptic endocytic zones and to impaired AMPAR internalization. These findings demonstrate a novel and essential role for Parkin in glutamatergic neurotransmission, as a stabilizer of postsynaptic Homer1 and the Homer1-linked endocytic machinery necessary for maintaining normal cell-surface AMPAR levels. Mutations in Parkin, a ubiquitinating enzyme, lead to the selective loss of midbrain dopaminergic neurons and juvenile-onset Parkinson's disease (PD). Parkin loss of function has also been shown to alter hippocampal glutamatergic neurotransmission, providing a potential explanation for PD-associated cognitive impairment. However, very little is known about Parkin's specific sites or mechanisms of action at glutamatergic synapses. Here, we show that Parkin deficiency leads to decreased AMPA receptor-mediated activity due to disruption of the postsynaptic endocytic zones required for maintaining proper cell-surface AMPA receptor levels. These findings demonstrate a novel role for Parkin in synaptic AMPA receptor internalization and suggest a Parkin-dependent mechanism for hippocampal dysfunction that may explain cognitive deficits associated with some forms of PD. Copyright © 2016 the authors 0270-6474/16/3612243-16$15.00/0.

Nitrogen loss by anaerobic ammonium oxidation in unconfined aquifer soils

NASA Astrophysics Data System (ADS)

Wang, Shanyun; Radny, Dirk; Huang, Shuangbing; Zhuang, Linjie; Zhao, Siyan; Berg, Michael; Jetten, Mike S. M.; Zhu, Guibing

2017-01-01

Anaerobic ammonium oxidation (anammox) is recognized as an important process for nitrogen cycling, yet little is known about its role in the subsurface biosphere. In this study, we investigated the presence, abundance, and role of anammox bacteria in upland soil cores from Tianjin, China (20 m depth) and Basel, Switzerland (10 m depth), using isotope-tracing techniques, (q)PCR assays, and 16 S rRNA & hzsB gene clone libraries, along with nutrient profiles of soil core samples. Anammox in the phreatic (water-saturated) zone contributed to 37.5-67.6% of the N-loss (up to 0.675 gN m-2 d-1), with anammox activities of 0.005-0.74 nmolN g-1 soil h-1, which were even higher than the denitrification rates. By contrast, no significant anammox was measured in the vadose zone. Higher anammox bacterial cell densities were observed (0.75-1.4 × 107 copies g-1 soil) in the phreatic zone, where ammonia-oxidizing bacteria (AOB) maybe the major source of nitrite for anammox bacteria. The anammox bacterial cells in soils of the vadose zone were all <103 copies g-1 soil. We suggest that the subsurface provides a favorable niche for anammox bacteria whose contribution to N cycling and groundwater nitrate removal seems considerably larger than previously known.

Nitrogen loss by anaerobic ammonium oxidation in unconfined aquifer soils

PubMed Central

Wang, Shanyun; Radny, Dirk; Huang, Shuangbing; Zhuang, Linjie; Zhao, Siyan; Berg, Michael; Jetten, Mike S. M.; Zhu, Guibing

2017-01-01

Anaerobic ammonium oxidation (anammox) is recognized as an important process for nitrogen cycling, yet little is known about its role in the subsurface biosphere. In this study, we investigated the presence, abundance, and role of anammox bacteria in upland soil cores from Tianjin, China (20 m depth) and Basel, Switzerland (10 m depth), using isotope-tracing techniques, (q)PCR assays, and 16 S rRNA & hzsB gene clone libraries, along with nutrient profiles of soil core samples. Anammox in the phreatic (water-saturated) zone contributed to 37.5–67.6% of the N-loss (up to 0.675 gN m−2 d−1), with anammox activities of 0.005–0.74 nmolN g−1 soil h−1, which were even higher than the denitrification rates. By contrast, no significant anammox was measured in the vadose zone. Higher anammox bacterial cell densities were observed (0.75–1.4 × 107 copies g−1 soil) in the phreatic zone, where ammonia-oxidizing bacteria (AOB) maybe the major source of nitrite for anammox bacteria. The anammox bacterial cells in soils of the vadose zone were all <103 copies g−1 soil. We suggest that the subsurface provides a favorable niche for anammox bacteria whose contribution to N cycling and groundwater nitrate removal seems considerably larger than previously known. PMID:28071702

High-Latitude Neutral Mass Density Maxima

NASA Astrophysics Data System (ADS)

Huang, C. Y.; Huang, Y.; Su, Y.-J.; Huang, T.; Sutton, E. K.

2017-10-01

Recent studies have reported that thermospheric effects due to solar wind driving can be observed poleward of auroral latitudes. In these papers, the measured neutral mass density perturbations appear as narrow, localized maxima in the cusp and polar cap. They conclude that Joule heating below the spacecraft is the cause of the mass density increases, which are sometimes associated with local field-aligned current structures, but not always. In this paper we investigate neutral mass densities measured by accelerometers on the CHAllenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) spacecraft from launch until years 2010 (CHAMP) and 2012 (GRACE), approximately 10 years of observations from each satellite. We extract local maxima in neutral mass densities over the background using a smoothing window with size of one quarter of the orbit. The maxima have been analyzed for each year and also for the duration of each set of satellite observations. We show where they occur, under what solar wind conditions, and their relation to magnetic activity. The region with the highest frequency of occurrence coincides approximately with the cusp and mantle, with little direct evidence of an auroral zone source. Our conclusions agree with the "hot polar cap" observations that have been reported and studied in the past.

Functional mapping of the pelvic floor and sphincter muscles from high-density surface EMG recordings.

PubMed

Peng, Yun; He, Jinbao; Khavari, Rose; Boone, Timothy B; Zhang, Yingchun

2016-11-01

Knowledge of the innervation of pelvic floor and sphincter muscles is of great importance to understanding the pathophysiology of female pelvic floor dysfunctions. This report presents our high-density intravaginal and intrarectal electromyography (EMG) probes and a comprehensive innervation zone (IZ) imaging technique based on high-density EMG readings to characterize the IZ distribution. Both intravaginal and intrarectal probes are covered with a high-density surface electromyography electrode grid (8 × 8). Surface EMG signals were acquired in ten healthy women performing maximum voluntary contractions of their pelvic floor. EMG decomposition was performed to separate motor-unit action potentials (MUAPs) and then localize their IZs. High-density surface EMG signals were successfully acquired over the vaginal and rectal surfaces. The propagation patterns of muscle activity were clearly visualized for multiple muscle groups of the pelvic floor and anal sphincter. During each contraction, up to 218 and 456 repetitions of motor units were detected by the vaginal and rectal probes, respectively. MUAPs were separated with their IZs identified at various orientations and depths. The proposed probes are capable of providing a comprehensive mapping of IZs of the pelvic floor and sphincter muscles. They can be employed as diagnostic and preventative tools in clinical practices.

Effects of rapid urban sprawl on urban forest carbon stocks: integrating remotely sensed, GIS and forest inventory data.

PubMed

Ren, Yin; Yan, Jing; Wei, Xiaohua; Wang, Yajun; Yang, Yusheng; Hua, Lizhong; Xiong, Yongzhu; Niu, Xiang; Song, Xiaodong

2012-12-30

Research on the effects of urban sprawl on carbon stocks within urban forests can help support policy for sustainable urban design. This is particularly important given climate change and environmental deterioration as a result of rapid urbanization. The purpose of this study was to quantify the effects of urban sprawl on dynamics of forest carbon stock and density in Xiamen, a typical city experiencing rapid urbanization in China. Forest resource inventory data collected from 32,898 patches in 4 years (1972, 1988, 1996 and 2006), together with remotely sensed data (from 1988, 1996 and 2006), were used to investigate vegetation carbon densities and stocks in Xiamen, China. We classified the forests into four groups: (1) forest patches connected to construction land; (2) forest patches connected to farmland; (3) forest patches connected to both construction land and farmland and (4) close forest patches. Carbon stocks and densities of four different types of forest patches during different urbanization periods in three zones (urban core, suburb and exurb) were compared to assess the impact of human disturbance on forest carbon. In the urban core, the carbon stock and carbon density in all four forest patch types declined over the study period. In the suburbs, different urbanization processes influenced forest carbon density and carbon stock in all four forest patch types. Urban sprawl negatively affected the surrounding forests. In the exurbs, the carbon stock and carbon density in all four forest patch types tended to increase over the study period. The results revealed that human disturbance played the dominant role in influencing the carbon stock and density of forest patches close to the locations of human activities. In forest patches far away from the locations of human activities, natural forest regrowth was the dominant factor affecting carbon stock and density. Copyright © 2012 Elsevier Ltd. All rights reserved.

Fractography of glass at the nanometer scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guilloteau, E.; Arribart, H.; Creuzet, F.

1996-12-01

The authors present a nanometer scale description of the fracture surface of soda-lime glass. This is achieved by the use of Atomic Force Microscopy. The mirror zone is shown to be built with elementary entities, the density of which increases continuously while the mist and hackle zones are approached. Moreover, the overall picture leads to some kind of self-similarity, in the sense that small regions of the hackle zone exhibit the full set of mirror, mist and hackle areas.

Strain Measurements within Fibreboard. Part III: Analyzing the Process Zone at the Crack Tip of Medium Density Fiberboards (MDF) Double Cantilever I-Beam Specimens

PubMed Central

Rathke, Jörn; Müller, Ulrich; Konnerth, Johannes; Sinn, Gerhard

2012-01-01

This paper is the third part of a study dealing with the mechanical and fracture mechanical characterization of Medium Density Fiberboards (MDF). In the first part, an analysis of internal bond strength testing was performed and in the second part MDF was analyzed by means of the wedge splitting experiment; this part deals with the double cantilever I beam test, which is designed for measuring the fracture energy as well as stress intensity factor in Mode I. For a comparison of isotropic and orthotropic material behavior, finite element modeling was performed. In addition to the calculation of fracture energy the stress intensity factor was analyzed by means of finite elements simulation and calculation. In order to analyze strain deformations and the process zone, electronic speckle pattern interferometry measurements were performed. The results revealed an elongated process zone and lower results for KIC if compared to the wedge splitting experiment. The Gf numbers are higher compared to the wedge splitting results and can be explained by the thicker process zone formed during the crack propagation. The process zone width on its part is influenced by the stiff reinforcements and yields a similar crack surface as with the internal bond test.

Macro and micro rate zonal analytical centrifugation of polydisperse and slowly diffusing sedimenting systems in isovolumetric density gradients. Application to cartilage proteoglycans.

PubMed

Müller, F J; Pezon, C F; Pita, J C

1989-06-13

A method to study the polydispersity of zonally sedimenting and slowly diffusing macromolecules or particles in isokinetic or isovolumetric density gradients is presented. First, a brief theory is given for predicting the zonal profile after a "triangular" (or "inverse") zone is centrifuged. This type of zone is essential to preserve hydrodynamic stability of the very slowly diffusing polydisperse solutes. It is proven, both by semitheoretical considerations and by computer calculations, that the resulting concentration profile of macrosolute is almost identical with that obtainable with a rectangular zone coextensive with the triangular one and carrying the same total mass. Next, practical procedures are described for the convectionless layering of very small triangular zones (50 microL or less). The linearity and stability of the zones are experimentally tested and verified. Finally, the method is applied to cartilage proteoglycan preparations that included either the monomeric molecules only or both the monomeric and the aggregated ones. The zonal results are compared with those obtained by using conventional boundary sedimentation. The two sets of results are seen to coincide fairly well, thus proving that the present technique can add to preparative zonal centrifugation the analytical precision of boundary sedimentation. A multimodal polydisperse system is suggested to describe the aggregated proteoglycan macromolecules.

Current Status of Mimosa pigra L. Infestation in Peninsular Malaysia

PubMed Central

Mansor, Asyraf; Crawley, Micheal J.

2011-01-01

The status and distribution of Mimosa pigra L., a semi-aquatic invasive species in Peninsular Malaysia, were continuously assessed between 2004 and 2007. This assessment investigated its population stand density and related weed management activities. In total, 106 sites of 6 main habitat types i.e., construction site (CS), dam/ reservoir (DM), forest reserve (FR), plantation (PL), river bank/waterway (RB) and roadside (RD) were assessed, and 55 sites were recorded with M. pigra populations. A CS is the most likely habitat to be infested with M. pigra (16 out of 18 assessed sites have this weed), whereas none of the FR visited were found to harbour M. pigra. In terms of population stand density, 41 populations were in the low range of stand density (individual plant of ≤5 m−2), compared to only 9 populations in the high range of stand density (individual plant of >10 m−2). In general, the current impact of M. pigra infestation on natural habitats is relatively low, as its distribution is only confined to disturbed areas. However, continuous monitoring of this weed species is highly recommended, especially in the riparian zone and wetland habitats. PMID:24575208

33 CFR 3.70-20 - Activities Far East Marine Inspection Zone.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Activities Far East Marine... SECURITY GENERAL COAST GUARD AREAS, DISTRICTS, SECTORS, MARINE INSPECTION ZONES, AND CAPTAIN OF THE PORT ZONES Fourteenth Coast Guard District § 3.70-20 Activities Far East Marine Inspection Zone. (a...

33 CFR 3.70-20 - Activities Far East Marine Inspection Zone.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Activities Far East Marine... SECURITY GENERAL COAST GUARD AREAS, DISTRICTS, SECTORS, MARINE INSPECTION ZONES, AND CAPTAIN OF THE PORT ZONES Fourteenth Coast Guard District § 3.70-20 Activities Far East Marine Inspection Zone. (a...

A microstructural study of fault rocks from the SAFOD: Implications for the deformation mechanisms and strength of the creeping segment of the San Andreas Fault

NASA Astrophysics Data System (ADS)

Hadizadeh, Jafar; Mittempergher, Silvia; Gratier, Jean-Pierre; Renard, Francois; Di Toro, Giulio; Richard, Julie; Babaie, Hassan A.

2012-09-01

The San Andreas Fault zone in central California accommodates tectonic strain by stable slip and microseismic activity. We study microstructural controls of strength and deformation in the fault using core samples provided by the San Andreas Fault Observatory at Depth (SAFOD) including gouge corresponding to presently active shearing intervals in the main borehole. The methods of study include high-resolution optical and electron microscopy, X-ray fluorescence mapping, X-ray powder diffraction, energy dispersive X-ray spectroscopy, white light interferometry, and image processing. The fault zone at the SAFOD site consists of a strongly deformed and foliated core zone that includes 2-3 m thick active shear zones, surrounded by less deformed rocks. Results suggest deformation and foliation of the core zone outside the active shear zones by alternating cataclasis and pressure solution mechanisms. The active shear zones, considered zones of large-scale shear localization, appear to be associated with an abundance of weak phases including smectite clays, serpentinite alteration products, and amorphous material. We suggest that deformation along the active shear zones is by a granular-type flow mechanism that involves frictional sliding of microlithons along phyllosilicate-rich Riedel shear surfaces as well as stress-driven diffusive mass transfer. The microstructural data may be interpreted to suggest that deformation in the active shear zones is strongly displacement-weakening. The fault creeps because the velocity strengthening weak gouge in the active shear zones is being sheared without strong restrengthening mechanisms such as cementation or fracture sealing. Possible mechanisms for the observed microseismicity in the creeping segment of the SAF include local high fluid pressure build-ups, hard asperity development by fracture-and-seal cycles, and stress build-up due to slip zone undulations.

The roles of prostate-specific antigen (PSA) density, prostate volume, and their zone-adjusted derivatives in predicting prostate cancer in patients with PSA less than 20.0 ng/mL.

PubMed

Shen, P; Zhao, J; Sun, G; Chen, N; Zhang, X; Gui, H; Yang, Y; Liu, J; Shu, K; Wang, Z; Zeng, H

2017-05-01

The aim of this study was to develop nomograms for predicting prostate cancer and its zonal location using prostate-specific antigen density, prostate volume, and their zone-adjusted derivatives. A total of 928 consecutive patients with prostate-specific antigen (PSA) less than 20.0 ng/mL, who underwent transrectal ultrasound-guided transperineal 12-core prostate biopsy at West China Hospital between 2011 and 2014, were retrospectively enrolled. The patients were randomly split into training cohort (70%, n = 650) and validation cohort (30%, n = 278). Predicting models and the associated nomograms were built using the training cohort, while the validations of the models were conducted using the validation cohort. Univariate and multivariate logistic regression was performed. Then, new nomograms were generated based on multivariate regression coefficients. The discrimination power and calibration of these nomograms were validated using the area under the ROC curve (AUC) and the calibration curve. The potential clinical effects of these models were also tested using decision curve analysis. In total, 285 (30.7%) patients were diagnosed with prostate cancer. Among them, 131 (14.1%) and 269 (29.0%) had transition zone prostate cancer and peripheral zone prostate cancer. Each of zone-adjusted derivatives-based nomogram had an AUC more than 0.75. All nomograms had higher calibration and much better net benefit than the scenarios in predicting patients with or without different zones prostate cancer. Prostate-specific antigen density, prostate volume, and their zone-adjusted derivatives have important roles in detecting prostate cancer and its zonal location for patients with PSA 2.5-20.0 ng/mL. To the best of our knowledge, this is the first nomogram using these parameters to predict outcomes of 12-core prostate biopsy. These instruments can help clinicians to increase the accuracy of prostate cancer screening and to avoid unnecessary prostate biopsy. © 2017 American Society of Andrology and European Academy of Andrology.

A Novel Synaptic Vesicle Fusion Path in the Rat Cerebral Cortex: The “Saddle” Point Hypothesis

PubMed Central

Zampighi, Guido A.; Serrano, Raul; Vergara, Julio L.

2014-01-01

We improved freeze-fracture electron microscopy to study synapses in the neuropil of the rat cerebral cortex at ∼2 nm resolution and in three-dimensions. In the pre-synaptic axon, we found that “rods” assembled from short filaments protruding from the vesicle and the plasma membrane connects synaptic vesicles to the membrane of the active zone. We equated these “connector rods” to protein complexes involved in “docking” and “priming” vesicles to the active zone. Depending on their orientation, the “rods” define two synaptic vesicle-fusion paths: When parallel to the plasma membrane, the vesicles hemi-fuse anywhere (“randomly”) in the active zone following the conventional path anticipated by the SNARE hypothesis. When perpendicular to the plasma membrane, the vesicles hemi-fuse at the base of sharp crooks, called “indentations,” that are spaced 75–85 nm center-to-center, arranged in files and contained within gutters. They result from primary and secondary membrane curvatures that intersect at stationary inflection (“saddle”) points. Computer simulations indicate that this novel vesicle-fusion path evokes neurotransmitter concentration domains on the post-synaptic spine that are wider, shallower, and that reach higher average concentrations than the more conventional vesicle fusion path. In the post-synaptic spine, large (∼9× ∼15 nm) rectangular particles at densities of 72±10/ µm2 (170–240/spine) match the envelopes of the homotetrameric GluR2 AMPA-sensitive receptor. While these putative receptors join clusters, called the “post-synaptic domains,” the overwhelming majority of the rectangular particles formed bands in the “non-synaptic” plasma membrane of the spine. In conclusion, in the neuropil of the rat cerebral cortex, curvatures of the plasma membrane define a novel vesicle-fusion path that preconditions specific regions of the active zone for neurotransmitter release. We hypothesize that a change in the hybridization of the R-SNARE synaptobrevin from parallel to antiparallel swings the synapse into this novel vesicle-fusion path. PMID:24959848

Effective rate constants for nanostructured heterogeneous catalysts

NASA Astrophysics Data System (ADS)

Hendy, Shaun; Gaston, Nicola; Zhang, Philip; Lund, Nat

2012-02-01

There is currently a high level of interest in the use of nanostructured materials for catalysis. For instance, gold, which is largely inert in the bulk, can exhibit strong catalytic activity when in nanoparticle form. With precious metal catalysts such as Pt and Pd in high demand, the use of these materials in nanoparticle form can also substantially reduce costs by exposure of more surface area for the same volume of material. When reactants are plentiful, the effective activity of a nanoparticulate catalyst will increase roughly with its surface area. However, under diffusion-limited conditions, the reactant must diffuse to active sites on the catalyst, so a high surface area and a high density of active sites may bring diminishing returns if reactant is consumed faster than it arrives. Here we apply a mathematical homogenisation approach to derive simple expressions for the effective reactivity of a nanostructured catalyst under diffusion limited conditions that relate the intrinsic rate constants of the surfaces presented by the catalyst to an effective rate constant. When highly active catalytic sites, such as step edges or other defects are present, we show that distinct limiting cases emerge depending on the degree of overlap of the reactant depletion zone about each site. In gases, the size of this depletion zone is approximately the mean free path, so the effective reactivity will depend on the structure of the catalyst on that scale. We discuss implications for the optimal design of nanoparticle catalysts.

Storage and mobilization of natural and septic nitrate in thick unsaturated zones, California

USGS Publications Warehouse

Izbicki, John A.; Flint, Alan L.; O'Leary, David R.; Nishikawa, Tracy; Martin, Peter; Johnson, Russell D.; Clark, Dennis A.

2015-01-01

Mobilization of natural and septic nitrate from the unsaturated zone as a result of managed aquifer recharge has degraded water quality from public-supply wells near Yucca Valley in the western Mojave Desert, California. The effect of nitrate storage and potential for denitrification in the unsaturated zone to mitigate increasing nitrate concentrations were investigated. Storage of water extractable nitrate in unsaturated alluvium up to 160 meters (m) thick, ranged from 420 to 6600 kilograms per hectare (kg/ha) as nitrogen (N) beneath undeveloped sites, from 6100 to 9200 kg/ha as N beneath unsewered sites. Nitrate reducing and denitrifying bacteria were less abundant under undeveloped sites and more abundant under unsewered sites; however, δ15N–NO3, and δ18O–NO3 data show only about 5–10% denitrification of septic nitrate in most samples—although as much as 40% denitrification occurred in some parts the unsaturated zone and near the top of the water table. Storage of nitrate in thick unsaturated zones and dilution with low-nitrate groundwater are the primary attenuation mechanisms for nitrate from septic discharges in the study area. Numerical simulations of unsaturated flow, using the computer program TOUGH2, showed septic effluent movement through the unsaturated zone increased as the number and density of the septic tanks increased, and decreased with increased layering, and increased slope of layers, within the unsaturated zone. Managing housing density can delay arrival of septic discharges at the water table, especially in layered unsaturated alluvium, allowing time for development of strategies to address future water-quality issues.

Storage and mobilization of natural and septic nitrate in thick unsaturated zones, California

NASA Astrophysics Data System (ADS)

Izbicki, John A.; Flint, Alan L.; O'Leary, David R.; Nishikawa, Tracy; Martin, Peter; Johnson, Russell D.; Clark, Dennis A.

2015-05-01

Mobilization of natural and septic nitrate from the unsaturated zone as a result of managed aquifer recharge has degraded water quality from public-supply wells near Yucca Valley in the western Mojave Desert, California. The effect of nitrate storage and potential for denitrification in the unsaturated zone to mitigate increasing nitrate concentrations were investigated. Storage of water extractable nitrate in unsaturated alluvium up to 160 meters (m) thick, ranged from 420 to 6600 kilograms per hectare (kg/ha) as nitrogen (N) beneath undeveloped sites, from 6100 to 9200 kg/ha as N beneath unsewered sites. Nitrate reducing and denitrifying bacteria were less abundant under undeveloped sites and more abundant under unsewered sites; however, δ15N-NO3, and δ18O-NO3 data show only about 5-10% denitrification of septic nitrate in most samples-although as much as 40% denitrification occurred in some parts the unsaturated zone and near the top of the water table. Storage of nitrate in thick unsaturated zones and dilution with low-nitrate groundwater are the primary attenuation mechanisms for nitrate from septic discharges in the study area. Numerical simulations of unsaturated flow, using the computer program TOUGH2, showed septic effluent movement through the unsaturated zone increased as the number and density of the septic tanks increased, and decreased with increased layering, and increased slope of layers, within the unsaturated zone. Managing housing density can delay arrival of septic discharges at the water table, especially in layered unsaturated alluvium, allowing time for development of strategies to address future water-quality issues.

Prostate-specific antigen density values among patients with symptomatic prostatic enlargement in Nigeria.

PubMed

Udeh, Emeka I; Nnabugwu, Ikenna I; Ozoemena, Francis O; Ugwumba, Fred O; Aderibigbe, Adesina S O; Ohayi, Samuel R; Echetabu, Kevin N

2016-06-29

This study aims to estimate the prostate-specific antigen density (PSAD) cutoff level for detecting prostate cancer (CAP) in Nigerian men with "grey zone PSA" (4-10 ng/ml) and normal digital rectal examination findings. We addressed this research question: Is the international PSAD cutoff of 0.15 ideal for detecting CAP in our symptomatic patients with "grey zone PSA?" To estimate the prostate-specific antigen density (PSAD) cutoff level for detecting CAP in Nigerian men with "grey zone PSA" (4-10 ng/ml) and normal digital rectal examination findings. Prospective. A tertiary medical center in Enugu, Nigeria. Two hundred and fifty-four men with either benign prostatic hyperplasia (BPH) or CAP were recruited. Patients with PSA above 4 ng/ml or abnormal digital rectal examination or hypoechoic lesion in the prostate were biopsied. PSAD and histology report of BPH or CAP. Ninety-seven patients had CAP while 157 had benign prostatic hyperplasia (BPH). Seventy-two patients had their serum PSA value within the range of 4.0 and 10 ng/ml. PSAD cutoff level to detect CAP was 0.04 (sensitivity 95.88 %; specificity 28.7 %). The PSAD cutoff level generated for Nigerian men in this study is 0.04 which is relatively different from international consensus. This PSAD cutoff level has a positive correlation with histology and could detect patients with CAP who have "grey zone PSA."

Active core profile and transport modification by application of ion Bernstein wave power in the Princeton Beta Experiment-Modification

NASA Astrophysics Data System (ADS)

LeBlanc, B.; Batha, S.; Bell, R.; Bernabei, S.; Blush, L.; de la Luna, E.; Doerner, R.; Dunlap, J.; England, A.; Garcia, I.; Ignat, D.; Isler, R.; Jones, S.; Kaita, R.; Kaye, S.; Kugel, H.; Levinton, F.; Luckhardt, S.; Mutoh, T.; Okabayashi, M.; Ono, M.; Paoletti, F.; Paul, S.; Petravich, G.; Post-Zwicker, A.; Sauthoff, N.; Schmitz, L.; Sesnic, S.; Takahashi, H.; Talvard, M.; Tighe, W.; Tynan, G.; von Goeler, S.; Woskov, P.; Zolfaghari, A.

1995-03-01

Application of Ion Bernstein Wave Heating (IBWH) into the Princeton Beta Experiment-Modification (PBX-M) [Phys. Fluids B 2, 1271 (1990)] tokamak stabilizes sawtooth oscillations and generates peaked density profiles. A transport barrier, spatially correlated with the IBWH power deposition profile, is observed in the core of IBWH-assisted neutral beam injection (NBI) discharges. A precursor to the fully developed barrier is seen in the soft x-ray data during edge localized mode (ELM) activity. Sustained IBWH operation is conducive to a regime where the barrier supports large ∇ne, ∇Te, ∇νφ, and ∇Ti, delimiting the confinement zone. This regime is reminiscent of the H(high) mode, but with a confinement zone moved inward. The core region has better than H-mode confinement while the peripheral region is L(low)-mode-like. The peaked profile enhances NBI core deposition and increases nuclear reactivity. An increase in central Ti results from χi reduction (compared to the H mode) and better beam penetration. Bootstrap current fractions of up to 0.32-0.35 locally and 0.28 overall were obtained when an additional NBI burst is applied to this plasma.

High efficiency x-ray nanofocusing by the blazed stacking of binary zone plates

NASA Astrophysics Data System (ADS)

Mohacsi, I.; Karvinen, P.; Vartiainen, I.; Diaz, A.; Somogyi, A.; Kewish, C. M.; Mercere, P.; David, C.

2013-09-01

The focusing efficiency of binary Fresnel zone plate lenses is fundamentally limited and higher efficiency requires a multi step lens profile. To overcome the manufacturing problems of high resolution and high efficiency multistep zone plates, we investigate the concept of stacking two different binary zone plates in each other's optical near-field. We use a coarse zone plate with π phase shift and a double density fine zone plate with π/2 phase shift to produce an effective 4- step profile. Using a compact experimental setup with piezo actuators for alignment, we demonstrated 47.1% focusing efficiency at 6.5 keV using a pair of 500 μm diameter and 200 nm smallest zone width. Furthermore, we present a spatially resolved characterization method using multiple diffraction orders to identify manufacturing errors, alignment errors and pattern distortions and their effect on diffraction efficiency.

Is Littoral Habitat Affected by Residential Development and Land Use in Watersheds of Wisconsin Lakes?

Treesearch

Martin J. Jennings; Edward E. Emmons; Gene R. Hatzenbeler; Clayton Edwards; Michael A. Bozek

2003-01-01

We measured differences in nearshore littoral zone habitat among lakes with different amounts of residential development and different patterns of watershed land use. Sampling stations were located at randomly selected sites within the nearshore littoral zone of limnologically similar lakes. An index of development density (based on counts of residential structures)...

The Three-part Structure of a Filament-unrelated Solar Coronal Mass Ejection

NASA Astrophysics Data System (ADS)

Song, H. Q.; Cheng, X.; Chen, Y.; Zhang, J.; Wang, B.; Li, L. P.; Li, B.; Hu, Q.; Li, G.

2017-10-01

Coronal mass ejections (CMEs) often exhibit the typical three-part structure in the corona when observed with white-light coronagraphs, I.e., the bright leading front, dark cavity, and bright core, corresponding to a high-low-high density sequence. As CMEs result from eruptions of magnetic flux ropes (MFRs), which can possess either lower (e.g., coronal-cavity MFRs) or higher (e.g., hot-channel MFRs) density compared to their surroundings in the corona, the traditional opinion regards the three-part structure as the manifestations of coronal plasma pileup (high density), coronal-cavity MFR (low density), and filament (high density) contained in the trailing part of MFR, respectively. In this paper, we demonstrate that filament-unrelated CMEs can also exhibit the classical three-part structure. The observations were made from different perspectives through an event that occurred on 2011 October 4. The CME cavity corresponds to the low-density zone between the leading front and the high-density core, and it is obvious in the low corona and gradually becomes fuzzy when propagating outward. The bright core corresponds to a high-density structure that is suggested to be an erupting MFR. The MFR is recorded from both edge-on and face-on perspectives, exhibiting different morphologies that are due to projection effects. We stress that the zone (MFR) with lower (higher) density in comparison to the surroundings can appear as the dark cavity (bright core) when observed through white-light coronagraphs, which is not necessarily the coronal-cavity MFR (erupted filament).

Near-surface Density Currents Observed in the Southeast Pacific Stratocumulus-topped Marine Boundary Layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilbanks, Matt C.; Yuter, S. E.; de Szoeke, S.

2015-09-01

Density currents (i.e. cold pools or outflows) beneath marine stratocumulus clouds are characterized using a 30-d data set of ship-based observations obtained during the 2008 Variability of American Monsoon Systems (VAMOS) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) in the southeast Pacific. An objective method identifies 71 density current fronts using an air density criterion and isolates each density current’s core (peak density) and tail (dissipating) zone. Compared to front and core zones, most density current tails exhibited weaker density gradients and wind anomalies elongated about the axis of the mean wind. The mean cloud-level advection relative to the surface layer windmore » (1.9 m s-1) nearly matches the mean density current propagation speed (1.8 m s-1). The similarity in speeds allows drizzle cells to deposit tails in their wakes. Based on high-resolution scanning Doppler lidar data, prefrontal updrafts had a mean intensity of 0.91 m s-1, reached an average altitude of 800 m, and were often surmounted by low-lying shelf clouds not connected to the overlying stratocumulus cloud. Nearly 90% of density currents were identified when C-band radar estimated 30-km diameter areal average rain rates exceeded 1 mm d-1. Rather than peaking when rain rates are highest overnight, density current occurrence peaks between 0600 and 0800 local solar time when enhanced local drizzle co-occurs with shallow subcloud dry and stable layers. The dry layers may contribute to density current formation by enhancing subcloud evaporation of drizzle. Density currents preferentially occur in regions of open cells but also occur in regions of closed cells.« less

78 FR 30269 - Foreign-Trade Zone 129-Bellingham, Washington; Authorization of Production Activity; T.C. Trading...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-22

... proposed production activity to the Foreign-Trade Zones (FTZ) Board on behalf of T.C. Trading Company, Inc... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-8-2013] Foreign-Trade Zone 129--Bellingham, Washington; Authorization of Production Activity; T.C. Trading Company, Inc. (Eyeglass Assembly and Kitting...

15 CFR 930.98 - Federally assisted activities outside of the coastal zone or the described geographic area.

Code of Federal Regulations, 2010 CFR

2010-01-01

... of the coastal zone or the described geographic area. 930.98 Section 930.98 Commerce and Foreign... Federally assisted activities outside of the coastal zone or the described geographic area. State agencies should monitor proposed federal assistance activities outside of the coastal zone or the described...

15 CFR 930.98 - Federally assisted activities outside of the coastal zone or the described geographic area.

Code of Federal Regulations, 2011 CFR

2011-01-01

... of the coastal zone or the described geographic area. 930.98 Section 930.98 Commerce and Foreign... Federally assisted activities outside of the coastal zone or the described geographic area. State agencies should monitor proposed federal assistance activities outside of the coastal zone or the described...

78 FR 56859 - Foreign-Trade Zone 267-Fargo, North Dakota; Authorization of Production Activity; CNH America...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-16

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-51-2013] Foreign-Trade Zone 267--Fargo, North Dakota; Authorization of Production Activity; CNH America, LLC, (Construction and Agricultural Equipment..., submitted a notification of proposed production activity to the Foreign-Trade Zones (FTZ) Board on behalf of...

Enhancing hair follicle regeneration by nonablative fractional laser: Assessment of irradiation parameters and tissue response.

PubMed

Wu, Yueh-Feng; Wang, Shiou-Han; Wu, Pei-Shan; Fan, Sabrina Mai-Yi; Chiu, Hsien-Yi; Tsai, Tsung-Hua; Lin, Sung-Jan

2015-04-01

Identification of methods to enhance anagen entry can be helpful for alopecia. Recently, nonablative laser has been proposed as a potential treatment for alopecia. However, how the laser parameters affect stem cell activity, hair cycles and the associated side effects have not been well characterized. Here we examine the effects of irradiation parameters of 1,550-nm fractional laser on hair cycles. The dorsal skin of eight-week-old female C57BL/6 mice with hair follicles in synchronized telogen was shaved and irradiated with a 1,550-nm fractional erbium-glass laser (Fraxel RE:STORE (SR1500) Laser System, Solta Medical, U.S.A.) with varied beam energies (5-35 mJ) and beam densities (500-3500 microthermal zones/cm(2) ). The cutaneous changes were evaluated both grossly and histologically. Hair follicle stem cell activity was detected by BrdU incorporation and changes in gene expression were quantified by real-time PCR. Direct thermal injury to hair follicles could be observed early after irradiation, especially at higher beam energy. Anagen induction in the irradiated skin showed an all-or-non change. Anagen induction and ulcer formation were affected by the combination of beam energy and density. The lowest beam energy of 5 mJ failed to promote anagen entry at all beam densities tested. As beam energy increased from 10 mJ to 35 mJ, we found a decreasing trend of beam density that could induce anagen entry within 7-9 days with activation of hair follicle stem cells. Beam density above the pro-regeneration density could lead to ulcers and scarring followed by anagen entry in adjacent skin. Analysis of inflammatory cytokines, including TNF-α, IL-1β, and IL-6, revealed that transient moderate inflammation was associated with anagen induction and intense prolonged inflammation preceded ulcer formation. To avoid side effects of hair follicle injury and scarring, appropriate combination of beam energy and density is required. Parameters outside the therapeutic window can result in either no anagen promotion or ulcer formation. © 2015 Wiley Periodicals, Inc.

On the Structure of the Mixing Zone at an Unstable Contact Boundary

NASA Astrophysics Data System (ADS)

Meshkov, E. E.

2018-01-01

The interface between two media of different densities (contact boundary) moving with an acceleration directed from the less dense medium to the more dense one is unstable (Rayleigh-Taylor instability) [1, 2]. The initial perturbations of the interface grow indefinitely and, as a result, a medium mixing zone growing with time is formed at the interface. The structure of such a mixing zone at gas-gas and gas-liquid interfaces is discussed on the basis of laboratory experiments on shock tubes of various types. It is concluded that the regions of turbulent and laminar flows are combined in the mixing zone.

Buoyant densities of phototrophic sulfur bacteria and cyanobacteria

NASA Technical Reports Server (NTRS)

Guerrero, R.

1985-01-01

The buoyant densities of bacterial cells are greatly influenced by the accumulation of intracellular reserve material. The buoyant density of phototrophic bacteria that are planktonic is of particular interest, since these organisms must remain in the photic zone of the water column for optimal growth. Separation of cells by their buoyant density may also be of use in separating and identifying organisms from a natural population. The bacteria used were obtained from pure cultures, enrichments, or samples taken directly from the environment.

Correction of localized shape errors on optical surfaces by altering the localized density of surface or near-surface layers

DOEpatents

Taylor, John S.; Folta, James A.; Montcalm, Claude

2005-01-18

Figure errors are corrected on optical or other precision surfaces by changing the local density of material in a zone at or near the surface. Optical surface height is correlated with the localized density of the material within the same region. A change in the height of the optical surface can then be caused by a change in the localized density of the material at or near the surface.

Retrogressive Failures in Sand Deposits of the Mississippi River. Report 1. Field Investigations, Laboratory Studies and Analysis of the Hypothesized Failure Mechanism

DTIC Science & Technology

1988-06-01

densities of Mississippi River point bar sands . 73. It is particularly conclusive to compare the available critical void ratio data for point bar sands on... River encounters the difficulty that the density of large parts of Zone A sands is between the upper and lower critical densities . All laboratory... sands of the Lower Mississippi River point bar deposits generally contain some strata of subcritical density , and the initial tendenc% of such sands

Molecular Mechanism of Active Zone Organization at Vertebrate Neuromuscular Junctions

PubMed Central

Nishimune, Hiroshi

2013-01-01

Organization of presynaptic active zones is essential for development, plasticity, and pathology of the nervous system. Recent studies indicate a trans-synaptic molecular mechanism that organizes the active zones by connecting the pre- and the postsynaptic specialization. The presynaptic component of this trans-synaptic mechanism is comprised of cytosolic active zone proteins bound to the cytosolic domains of voltage-dependent calcium channels (P/Q-, N-, and L-type) on the presynaptic membrane. The postsynaptic component of this mechanism is the synapse organizer (laminin β2) that is expressed by the postsynaptic cell and accumulates specifically on top of the postsynaptic specialization. The pre- and the postsynaptic components interact directly between the extracellular domains of calcium channels and laminin β2 to anchor the presynaptic protein complex in front of the postsynaptic specialization. Hence, the presynaptic calcium channel functions as a scaffolding protein for active zone organization and as an ion-conducting channel for synaptic transmission. In contrast to the requirement of calcium influx for synaptic transmission, the formation of the active zone does not require the calcium influx through the calcium channels. Importantly, the active zones of adult synapses are not stable structures and require maintenance for their integrity. Furthermore, aging or diseases of the central and peripheral nervous system impair the active zones. This review will focus on the molecular mechanisms that organize the presynaptic active zones and summarize recent findings at the neuromuscular junctions and other synapses. PMID:22135013

Characterization of the Fault Core and Damage Zone of the Borrego Fault, 2010 M7.2 Rupture

NASA Astrophysics Data System (ADS)

Dorsey, M. T.; Rockwell, T. K.; Girty, G.; Ostermeijer, G.; Mitchell, T. M.; Fletcher, J. M.

2017-12-01

We collected a continuous sample of the fault core and 23 samples of the damage zone out to 52 m across the rupture trace of the 2010 M7.2 El Mayor-Cucapa earthquake to characterize the physical damage and chemical transformations associated with this active seismic source. In addition to quantifying fracture intensity from macroscopic analysis, we cut a continuous thin section through the fault core and from various samples in the damage zone, and ran each sample for XRD analyses for clay mineralogy, XRF for bulk geochemical analyses, and bulk and grain density from which porosity and volumetric strain were derived. The parent rock is a hydrothermally-altered biotite tonalite, with biotite partially altered to chlorite. The presence of epidote with chlorite suggests that these rocks were subjected to relatively high temperatures of 300-400° C. Adjacent to the outermost damage zone is a chaotic breccia zone with distinct chemical and physical characteristics, indicating possible connection to an ancestral fault to the southwest. The damage zone consists of an outer zone of protocataclasite, which grades inward towards mesocataclasite with seams of ultracataclasite. The fault core is anomalous in that it is largely composed of a sliver of marble that has been translated along the fault, so direct comparison with the damage zone is impaired. From collected data, we observe that chloritization increases into the breccia and damage zones, as does the presence of illite. Porosity reaches maximum values in the damage zone adjacent to the core, and closely follows trends in fracture intensity. Statistically significant gains in Mg, Na, K, Mn, and total bulk mass occurred within the inner damage zone, with losses of Ca and P mass, which led to the formation of chlorite and albite. The outer damage zone displays gains in Mg and Na mass with losses in Ca and P mass. The breccia zone shows gains in mass of Mg and Mn and loss in total bulk mass. A gain in LOI in both the breccia and damage zones is attributed to formation of clay. Volumetric strain tracks porosity, as expected, and increases towards the core. Notably, damage appears to be superposed on chemical alterations, which supports the idea that much of the hydrothermal alteration occurred at depth followed by brecciation and cataclasis once the fault zone rocks were exhumed closer to the surface.

Research on vulnerability assessments of the Huanghe (Yellow River) delta

NASA Astrophysics Data System (ADS)

qiao, shuqing; shi, xuefa

2014-05-01

Coastal zone located at the juncture of the sea, river and land, and under the influence of both land and ocean (including atmosphere), especially the sea-level rise and human activities, are vulnerable to environment and ecology. At highest risk are coastal zone of South, Southeast and East Asia with dense populations, low elevations and inadequate adaptive capacity. In China, more than 40% of the population live on the 15% of the land in coastal area and more than 70% cities located around the coastal area. The Chinese coastal region, especially river delta area has been experienced erosion, seawater intrusion and decrease in biodiversity under the combined influence of sea-level rise, tectonic subsidence and flooding. Furthermore, some kinds of human activity, such as land use, building, dam construction, reclamation from the sea and waste dumping strengthen the vulnerability of environment and ecosystem in coastal region. The coastal hazards (e.g. coastal erosion, seawater intrusion, land subsidence) and vulnerability of the Huanghe (Yelllow River) delta area are studied during the past several years. A systematic coastal assessment index is built and an evaluation model is developed using the development platform of Visual studio.Net 2005. The assessment index system includes two parts, inherent (sea level rise rate, elevation, morphology, water and sediment discharge, mean tidal range, mean wave height etc) and specific vulnerability index (population density, GDP, land utilization, protection structures etc). The assessment index are determined the weight using Analytic hierarchy process (AHP) method. Based on the research results, we better understand the current status and future change of coastal vulnerability and hazards, discuss the impact of the natural possess and human activities. Furthermore, we provide defending strategies for coastal zone vulnerability and typical coastal hazards.

Numbers of presynaptic Ca2+ channel clusters match those of functionally defined vesicular docking sites in single central synapses.

PubMed

Miki, Takafumi; Kaufmann, Walter A; Malagon, Gerardo; Gomez, Laura; Tabuchi, Katsuhiko; Watanabe, Masahiko; Shigemoto, Ryuichi; Marty, Alain

2017-06-27

Many central synapses contain a single presynaptic active zone and a single postsynaptic density. Vesicular release statistics at such "simple synapses" indicate that they contain a small complement of docking sites where vesicles repetitively dock and fuse. In this work, we investigate functional and morphological aspects of docking sites at simple synapses made between cerebellar parallel fibers and molecular layer interneurons. Using immunogold labeling of SDS-treated freeze-fracture replicas, we find that Ca v 2.1 channels form several clusters per active zone with about nine channels per cluster. The mean value and range of intersynaptic variation are similar for Ca v 2.1 cluster numbers and for functional estimates of docking-site numbers obtained from the maximum numbers of released vesicles per action potential. Both numbers grow in relation with synaptic size and decrease by a similar extent with age between 2 wk and 4 wk postnatal. Thus, the mean docking-site numbers were 3.15 at 2 wk (range: 1-10) and 2.03 at 4 wk (range: 1-4), whereas the mean numbers of Ca v 2.1 clusters were 2.84 at 2 wk (range: 1-8) and 2.37 at 4 wk (range: 1-5). These changes were accompanied by decreases of miniature current amplitude (from 93 pA to 56 pA), active-zone surface area (from 0.0427 μm 2 to 0.0234 μm 2 ), and initial success rate (from 0.609 to 0.353), indicating a tightening of synaptic transmission with development. Altogether, these results suggest a close correspondence between the number of functionally defined vesicular docking sites and that of clusters of voltage-gated calcium channels.

The specific features of gold ore provinces of the south of Siberia in a magnetic field at ground height and heights of flight of satellite Champ.

NASA Astrophysics Data System (ADS)

Litvinova, Tamara; Petrova, Alevtina

2010-05-01

The specific features of gold ore provinces of the south of Siberia in a magnetic field at ground height and heights of flight of satellite Champ. T.Litvinova -All-Russian Geological Research Institute (VSEGEI) A. Petrova - St. Petersburg, SPbF IZMIRAN, Russian Academy of Sciences, St. Petersburg For allocation of specific features known gold ore objects (Olimpiadninskoje, Suchoi Log, etc.) is executed the morphological analysis of the magnetic field received on materials of aeromagnetic data and satellite measurements at heights of 100 and 400 km. On the ground data on a map of magnetic anomalies of Russia of scale 1:2 500000 of 50 km on the extended structures crossing known gold ore deposits and promising ore units have been constructed geomagnetic and densitys sections up to depth. On geomagnetic and densitys sections to known large gold ore to deposits are dated deep synvertical the permeable zones described by a synlenticular -layered structure. Extended horizons of not magnetic formations are located on depths about 10, 12, 15-18, 30 and 40 km. On deep densitys sections reference sites ¬ the Suchoi Log, Olimpiadninskoje and Vodorazdelnoje ¬ is characterized by zones of inversion of density. Areas of the loosened breeds are dated to synvertical to deep zones of hydrothermal and fluid study of breeds inside which the loosened lenses in intervals of depths from 2 up to 5 km are formed, 8-13 km, 18-20 and 25-30 km of 35-40 km within the limits of the bottom bark. The analysis of a magnetic field has shown, that gold mineralization in researched region is dated for zones of long-living regional explosive infringements, to permeable terrigenous to thicknesses of depressions, to adjournment depression structures in units of crossing of tectonofluid zones of diagonal orientation. Terrigenous adjournment depression structures are shown on a geomagnetic section as the powerful deflections filled with low-magnetic thicknesses. These deflections are dated to synvertical to deep zones of low-magnetic breeds, probably, reflecting influence of the high-temperature tectonofluid processes occuring on the big depths (up to 30 - 35 km), and explosive infringements shown through systems. It testifies to presence of a long-living deep zone of differentiation of substance when inside the base lenses of the loosened breeds are formed, and more dense breeds mapping in near-surface formations. It was represented interesting to track as the laws allocated on the ground aeromagnetic data are reflected in satellite anomalies. The analysis has shown, that gold ore areas Barguzino - Vitim evgeosynclinal zones gravitate to a local minimum of a magnetic field of satellite Champ at height of 100 km. Zones of minima at height of 100 km coincide with position of permeable blocks of the earth's crust allocated on extended structures, executed by results of ground shooting. The considered zones of minima at height of 400 km practically do not change the morphology. Local steady minima in area Barguzino - Vitim zones on maps of satellite Champ can be connected with heattd-up long-living fluidized the channels providing gold ore and rare-metal a mineralization of the region.

Seismotectonics of northeastern United States and adjacent Canada

NASA Astrophysics Data System (ADS)

Yang, Jih-Ping; Aggarwal, Yash Pal

1981-06-01

Data for local earthquakes recorded by a network of stations in northeastern United States and adjacent Canada were analyzed to study the seismicity, the relationship between earthquakes and known faults, the state of stress, and crustal and upper mantle velocity structure. In addition, portable seismographs were deployed in the field to study aftershocks. As a result, accurate locations for about 364 local earthquakes (2 ≤ mb ≤ 5) and 22 focal mechanism solutions were determined. A comparison of the spatial distribution of these events (1970-1979) with historical earthquakes (1534-1959) reveals that seismic activity in the northeast is relatively stationary in space: those areas that have had little or no seismicity historically are relatively aseismic today, whereas the historically active areas are also active today. The instrumental locations, historical seismicity, and focal mechanism solutions show an internal consistency that help us distinguish two distinct seismogenic provinces. (1) The Adirondack-western Quebec province is a northwesterly trending zone of seismic activity, about 200 km wide and at least 500 km long, extending from the SE Adirondacks into western Quebec, Canada. Thrust faulting on planes striking NNW to NW appears to predominate, and the inferred axis of maximum horizontal compression is largely uniform and trends WSW, nearly parallel to the calculated absolute plate motion of North America. Little or no seismicity is found where anorthosite outcrops at the surface. Correlations between gravity anomalies and earthquake locations suggest that seismic activity in this zone is localized to regions of steep NE or SW gradient in Bouguer anomalies. This zone does not appear to extend southeastward to Boston, as proposed by some workers. (2) The Appalachian province is a northeasterly trending zone of seismic activity extending from northern Virginia to New Brunswick, Canada. Highangle reverse or thrust faulting on N to NE trending planes appears to predominate. The western margin of this province, however, appears to be relatively aseismic. We attribute this relative lack of activity to one or more of the following: the presence of igneous activity postdating rifting of Africa from North America, the occurrence of intense metamorphism during the Acadian orogeny which may have annealed preexisting faults, and the predominance of ductile as opposed to brittle deformation in the geologic past. The inferred axis of maximum horizontal compression along the eastern margin of the Appalachians is rather uniform and trends W-WNW, almost perpendicular to the magnetic lineations offshore. We suggest that this W-WNW compression reflects the gravitational force arising from horizontal density variations in the oceanic lithosphere as it cools and moves away from spreading centers.

The Proterozoic Mount Isa Fault Zone, northeastern Australia: is it really a ca. 1.9 Ga terrane-bounding suture?

NASA Astrophysics Data System (ADS)

Bierlein, Frank P.; Betts, Peter G.

2004-09-01

In marked contrast to Palaeoproterozoic Laurentia, the location of sutures and boundaries of discrete crustal fragments amalgamated during Palaeoproterozoic formation of the North Australian Craton remain highly speculative. Interpretations of suture locations have relied heavily on the analysis of regional geophysical datasets because of sparse exposure of rocks of the appropriate age. The Mount Isa Fault Zone has been interpreted as one such Palaeoproterozoic terrane-bounding suture. Furthermore, the coincidence of this fault zone with major shale-hosted massive sulphide Pb-Zn-Ag orebodies has led to speculations that trans-lithospheric faults may be an important ingredient for the development of this deposit type. This study has integrated geophysical and geochemical data to test the statute of the Mount Isa Fault as a terrane-bounding suture. Forward modelling of gravity data shows that basement rocks on either side of the Mount Isa Fault have similar densities. These interpretations are consistent with geochemical observations and Sm-Nd data that suggest that basement lithologies on either side of the Mount Isa Fault are geochemically and isotopically indistinguishable from each other, and that the Mount Isa Fault is unlikely to represent a suture zone that separates different Palaeoproterozoic terranes. Our data indicate that the crustal blocks on both sides of the Mount Isa Fault Zone must have been in within close proximity of each other since the Palaeoproterozoic, and that the Western Fold Belt was part of the (ancestral) North Australian Craton well before the ˜1.89-1.87 Ga Barramundi Orogeny. It appears that deep crustal variations in density may be related to the boundary between a shallowly west-dipping high-density mafic to ultramafic plate and low-density basement rocks. This interpretation in turn impacts on crustal-scale models for the development of shale-hosted massive sulphide Pb-Zn mineralisation, which do not require trans-lithospheric faults to tap deep-seated metal reservoirs and/or mantle plumbing systems. The approach applied herein demonstrates the value of multi-disciplinary investigations to the critical assessment of long-lived Proterozoic fault systems which, in the absence of methodical analysis, are commonly assumed to represent terrane-bounding sutures.

Kepler planet-detection mission: introduction and first results.

PubMed

Borucki, William J; Koch, David; Basri, Gibor; Batalha, Natalie; Brown, Timothy; Caldwell, Douglas; Caldwell, John; Christensen-Dalsgaard, Jørgen; Cochran, William D; DeVore, Edna; Dunham, Edward W; Dupree, Andrea K; Gautier, Thomas N; Geary, John C; Gilliland, Ronald; Gould, Alan; Howell, Steve B; Jenkins, Jon M; Kondo, Yoji; Latham, David W; Marcy, Geoffrey W; Meibom, Søren; Kjeldsen, Hans; Lissauer, Jack J; Monet, David G; Morrison, David; Sasselov, Dimitar; Tarter, Jill; Boss, Alan; Brownlee, Don; Owen, Toby; Buzasi, Derek; Charbonneau, David; Doyle, Laurance; Fortney, Jonathan; Ford, Eric B; Holman, Matthew J; Seager, Sara; Steffen, Jason H; Welsh, William F; Rowe, Jason; Anderson, Howard; Buchhave, Lars; Ciardi, David; Walkowicz, Lucianne; Sherry, William; Horch, Elliott; Isaacson, Howard; Everett, Mark E; Fischer, Debra; Torres, Guillermo; Johnson, John Asher; Endl, Michael; MacQueen, Phillip; Bryson, Stephen T; Dotson, Jessie; Haas, Michael; Kolodziejczak, Jeffrey; Van Cleve, Jeffrey; Chandrasekaran, Hema; Twicken, Joseph D; Quintana, Elisa V; Clarke, Bruce D; Allen, Christopher; Li, Jie; Wu, Haley; Tenenbaum, Peter; Verner, Ekaterina; Bruhweiler, Frederick; Barnes, Jason; Prsa, Andrej

2010-02-19

The Kepler mission was designed to determine the frequency of Earth-sized planets in and near the habitable zone of Sun-like stars. The habitable zone is the region where planetary temperatures are suitable for water to exist on a planet's surface. During the first 6 weeks of observations, Kepler monitored 156,000 stars, and five new exoplanets with sizes between 0.37 and 1.6 Jupiter radii and orbital periods from 3.2 to 4.9 days were discovered. The density of the Neptune-sized Kepler-4b is similar to that of Neptune and GJ 436b, even though the irradiation level is 800,000 times higher. Kepler-7b is one of the lowest-density planets (approximately 0.17 gram per cubic centimeter) yet detected. Kepler-5b, -6b, and -8b confirm the existence of planets with densities lower than those predicted for gas giant planets.

Enhanced neovascularization of dermis substitutes via low-pressure plasma-mediated surface activation.

PubMed

Ring, Andrej; Langer, Stefan; Schaffran, Angela; Stricker, Ingo; Awakowicz, Peter; Steinau, Hans-Ulrich; Hauser, Jörg

2010-12-01

The effect of cold low-pressure plasma treatment on neovascularization of a dermis substitute was evaluated in a mouse model. Collagen-elastin matrices (Matriderm(®)) were used as scaffolds. Low-pressure argon/hydrogene plasma-treated scaffolds were transplanted into the dorsal skinfold chambers of balb/c mice (group 1, n=10). Untreated scaffolds served as controls (group 2, n=10). Intravital fluorescence microscopy was performed within the border zone of the scaffolds on days 1, 5 and 10. Functional vessel density (FVD), vessel diameter, intervascular distance, microvascular permeability, and leukocyte-endothelium interaction were analyzed. An increase of FVD associated with a reduction of the intervascular distance was observed. Statistical analysis revealed that the functional vessel density in the border zone of the scaffolds was significantly enhanced in the plasma-treated group compared to controls. For group 1, an increase of FVD from 282±8 cm/cm(2) on days 5 to 315±8 cm/cm(2) on day 10 was observed. Whereas values of 254±7 cm/cm(2) on day 5 and 275±13 cm/cm(2) on day 10 have resulted in group 2 (mean±S.E.M., Student's t-test, p<0.05). The surface treatment by cold low-pressure plasma intensifies the angiogenesis and accelerates the neovascularization of collagen-elastin matrix. Copyright © 2010 Elsevier Ltd and ISBI. All rights reserved.

Gravity anomaly and crustal density structure in Jilantai rift zone and its adjacent region

NASA Astrophysics Data System (ADS)

Wu, Guiju; Shen, Chongyang; Tan, Hongbo; Yang, Guangliang

2016-08-01

This paper deals with the interpretation of Bouguer gravity anomalies measured along a 250 km long Suhaitu-Etuokeqi gravity profile located at the transitional zone of the Alxa and Ordos blocks where geophysical characteristics are very complex. The analysis is carried out in terms of the ratio of elevation and Bouguer gravity anomaly, the normalized full gradient of a section of the Bouguer gravity anomaly ( G h ) and the crustal density structure reveal that (1) the ratio of highs and lows of elevation and Bouguer gravity anomaly is large between Zhengyiguan fault (F4) and Helandonglu fault (F6), which can be explained due to crustal inhomogeneities related to the uplift of the Qinghai-Tibet block in the northeast; (2) the main active faults correspond to the G h contour strip or cut the local region, and generally show strong deformation characteristics, for example the Bayanwulashan mountain front fault ( F1) or the southeast boundary of Alxa block is in accord with the western change belt of G h , a belt about 10 km wide that extends to about 30 km; (3) Yinchuan-Pingluo fault ( F8) is the seismogenic structure of the Pingluo M earthquake, and its focal depth is about 15 km; (4) the Moho depth trend and Bouguer gravity anomaly variation indicates that the regional gravity field is strongly correlated with the Moho discontinuity.

Fracture properties from tight reservoir outcrop analogues with application to geothermal exploration

NASA Astrophysics Data System (ADS)

Philipp, Sonja L.; Reyer, Dorothea; Afsar, Filiz; Bauer, Johanna F.; Meier, Silke; Reinecker, John

2015-04-01

In geothermal reservoirs, similar to other tight reservoirs, fluid flow may be intensely affected by fracture systems, in particular those associated with fault zones. When active (slipping) the fault core, that is, the inner part of a fault zone, which commonly consists of breccia or gouge, can suddenly develop high permeability. Fault cores of inactive fault zones, however, may have low permeabilities and even act as flow barriers. In the outer part of a fault zone, the damage zone, permeability depends mainly on the fracture properties, that is, the geometry (orientation, aperture, density, connectivity, etc.) of the fault-associated fracture system. Mineral vein networks in damage zones of deeply eroded fault zones in palaeogeothermal fields demonstrate their permeability. In geothermal exploration, particularly for hydrothermal reservoirs, the orientation of fault zones in relation to the current stress field as well as their internal structure, in particular the properties of the associated fracture system, must be known as accurately as possible for wellpath planning and reservoir engineering. Here we present results of detailed field studies and numerical models of fault zones and associated fracture systems in palaeogeo¬thermal fields and host rocks for geothermal reservoirs from various stratigraphies, lithologies and tectonic settings: (1) 74 fault zones in three coastal sections of Upper Triassic and Lower Jurassic age (mudstones and limestone-marl alternations) in the Bristol Channel Basin, UK. (2) 58 fault zones in 22 outcrops from Upper Carboniferous to Upper Cretaceous in the Northwest German Basin (siliciclastic, carbonate and volcanic rocks); and (3) 16 fault zones in 9 outcrops in Lower Permian to Middle Triassic (mainly sandstone and limestone) in the Upper Rhine Graben shoulders. Whereas (1) represent palaeogeothermal fields with mineral veins, (2) and (3) are outcrop analogues of reservoir horizons from geothermal exploration. In the study areas of palaeo¬geothermal fields in the Bristol Channel (1), all mineral veins, most of which are extension fractures, are of calcite. They are clearly associated with the faults and indicate that geothermal water was transported along the then-active faults into the host rocks with evidence of injection as hydrofractures. Layers with contrasting mechanical properties (in particular, stiffnesses), however, acted as stress barriers and lead to fracture arrest. Along some faults, veins propagated through the barriers along faults to shallower levels. In the Northwest German Basin (2) there are pronounced differences between normal-fault zones in carbonate and clastic rocks. Only in carbonate rocks clear damage zones occur, characterized by increased fracture frequencies and high amounts of fractures with large apertures. On the Upper Rhine Graben shoulders (3) damage zones in Triassic Muschelkalk limestones are well developed; fault cores are narrow and comprise breccia, clay smear, host rock lenses and mineralization. A large fault zone in Triassic Bunter sandstone shows a clearly developed fault core with fault gouge, slip zones, deformation bands and host rock lenses, a transition zone with mostly disturbed layering and highest fracture frequency, and a damage zone. The latter damage zone is compared to the damage zone of a large Bunter sandstone fault zone currently explored for geothermal energy production. The numerical models focus on stress field development, fracture propagation and associated permeability changes. These studies contribute to the understanding of the hydromechanical behaviour of fault zones and related fluid transport in fractured reservoirs complementing predictions based on geophysical measurements. Eventually we aim at classifying and quantifying fracture system properties in fault zones to improve exploration and exploitation of geothermal reservoirs. Acknowledgements The authors appreciate the support of 'Niedersächsisches Ministerium für Wissen¬schaft und Kultur' and 'Baker Hughes' within the gebo research project (http://www.gebo-nds.de), the Bundesministerium für Umwelt, Naturschutz, Bau und Reaktorsicherheit (BMU; FKZ: 0325302, AuGE) and the Deutsche Forschungsgemeinschaft. GeoEnergy GmbH, Karlsruhe, is thanked for explorational data.

34 CFR 299.3 - What priority may the Secretary establish for activities in an Empowerment Zone or Enterprise...

Code of Federal Regulations, 2012 CFR

2012-07-01

... activities in an Empowerment Zone or Enterprise Community? 299.3 Section 299.3 Education Regulations of the... activities in an Empowerment Zone or Enterprise Community? For any ESEA discretionary grant program, the... significant portion of the program funds to address substantial problems in an Empowerment Zone, including a...

34 CFR 299.3 - What priority may the Secretary establish for activities in an Empowerment Zone or Enterprise...

Code of Federal Regulations, 2014 CFR

2014-07-01

... activities in an Empowerment Zone or Enterprise Community? 299.3 Section 299.3 Education Regulations of the... activities in an Empowerment Zone or Enterprise Community? For any ESEA discretionary grant program, the... significant portion of the program funds to address substantial problems in an Empowerment Zone, including a...

34 CFR 299.3 - What priority may the Secretary establish for activities in an Empowerment Zone or Enterprise...

Code of Federal Regulations, 2013 CFR

2013-07-01

... activities in an Empowerment Zone or Enterprise Community? 299.3 Section 299.3 Education Regulations of the... activities in an Empowerment Zone or Enterprise Community? For any ESEA discretionary grant program, the... significant portion of the program funds to address substantial problems in an Empowerment Zone, including a...

78 FR 20091 - Foreign-Trade Zone 26-Atlanta, Georgia, Authorization of Production Activity, Perkins Shibaura...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-03

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-90-2012] Foreign-Trade Zone 26--Atlanta, Georgia, Authorization of Production Activity, Perkins Shibaura Engines, LLC (Diesel Engines), Griffin, Georgia On November 29, 2012, Georgia Foreign-Trade Zone, Inc., grantee of FTZ 26, submitted a notification of proposed production activity to the...

34 CFR 299.3 - What priority may the Secretary establish for activities in an Empowerment Zone or Enterprise...

Code of Federal Regulations, 2010 CFR

2010-07-01

... activities in an Empowerment Zone or Enterprise Community? 299.3 Section 299.3 Education Regulations of the... activities in an Empowerment Zone or Enterprise Community? For any ESEA discretionary grant program, the... significant portion of the program funds to address substantial problems in an Empowerment Zone, including a...

34 CFR 299.3 - What priority may the Secretary establish for activities in an Empowerment Zone or Enterprise...

Code of Federal Regulations, 2011 CFR

2011-07-01

... activities in an Empowerment Zone or Enterprise Community? 299.3 Section 299.3 Education Regulations of the... activities in an Empowerment Zone or Enterprise Community? For any ESEA discretionary grant program, the... significant portion of the program funds to address substantial problems in an Empowerment Zone, including a...

Phreatomagmatic eruptive and depositional processes during the 1949 eruption on La Palma (Canary Islands)

NASA Astrophysics Data System (ADS)

White, James D. L.; Schmincke, Hans-Ulrich

1999-12-01

In 1949, a 5-week-long magmatic and phreatomagmatic eruption took place along the active volcanic ridge of La Palma (Canary Islands). Two vents, Duraznero and Hoyo Negro, produced significant pyroclastic deposits. The eruption began from Duraznero vent, which produced a series of deposits with an upward decrease in accidental fragments and increase in fluidal ash and spatter, together inferred to indicate decreasing phreatomagmatic interaction. Hoyo Negro erupted over a 2-week period, producing a variety of pyroclastic density currents and ballistic blocks and bombs. Hoyo Negro erupted within and modified an older crater having high walls on the northern to southeastern edges. Southwestern to western margins of the crater lay 50 to 100 m lower. Strongly contrasting deposits in the different sectors (N-SE vs. SW-W) were formed as a result of interaction between topography, weak eruptive columns and stratified pyroclastic density currents. Tephra ring deposits are thicker and coarser-grained than upper rim deposits formed along the higher edges of the crater, and beyond the crater margin, valley-confined deposits are thicker than more thinly bedded mantling deposits on higher topography. These differences indicate that the impact zone for the bulk of the collapsing, tephra-laden column lay within the crater and that the high crater walls inhibited escape of pyroclastic density currents to the north and east. The impact zone lay outside the low SW-W rims, however, thus allowing stratified pyroclastic density currents to move freely away from the crater in those directions, depositing thin sections (<30 cm) of well-bedded ash (mantling deposits) on ridges and thicker sections (1-3 m) of structureless ash beds in valleys and small basins. Such segregation of dense pyroclastic currents from more dilute ones at the crater wall is likely to be common for small eruptions from pre-existing craters and is an important factor to be taken into account in volcanic hazards assessments.

Lithospheric density structure beneath the Tarim basin and surroundings, northwestern China, from the joint inversion of gravity and topography

USGS Publications Warehouse

Deng, Yangfan; Levandowski, William Brower; Kusky, Tim

2017-01-01

Intraplate strain generally focuses in discrete zones, but despite the profound impact of this partitioning on global tectonics, geodynamics, and seismic hazard, the processes by which deformation becomes localized are not well understood. Such heterogeneous intraplate strain is exemplified in central Asia, where the Indo-Eurasian collision has caused widespread deformation while the Tarim block has experienced minimal Cenozoic shortening. The apparent stability of Tarim may arise either because strain is dominantly accommodated by pre-existing faults in the continental suture zones that bound it—essentially discretizing Eurasia into microplates—or because the lithospheric-scale strength (i.e., viscosity) of the Tarim block is greater than its surroundings. Here, we jointly analyze seismic velocity, gravity, topography, and temperature to develop a 3-D density model of the crust and upper mantle in this region. The Tarim crust is characterized by high density, vs, vp, and vp/vs, consistent with a dominantly mafic composition and with the presence of an oceanic plateau beneath Tarim. Low-density but high-velocity mantle lithosphere beneath southern (southwestern) Tarim underlies a suite of Permian plume-related mafic intrusions and A-type granites sourced in previously depleted mantle lithosphere; we posit that this region was further depleted, dehydrated, and strengthened by Permian plume magmatism. The actively deforming western and southern margins of Tarim—the Tien Shan, Kunlun Shan, and Altyn Tagh fault—are underlain by buoyant upper mantle with low velocity; we hypothesize that this material has been hydrated by mantle-derived fluids that have preferentially migrated along Paleozoic continental sutures. Such hydrous material should be weak, and herein strain focuses there because of lithospheric-scale variations in rheology rather than the pre-existence of faults in the brittle crust. Thus this world-class example of strain partitioning arises not simply from the pre-existence of brittle faults but from the thermo-chemical and therefore rheological variations inherited from prior tectonism.

Detailed Velocity and Density models of the Cascadia Subduction Zone from Prestack Full-Waveform Inversion

NASA Astrophysics Data System (ADS)

Fortin, W.; Holbrook, W. S.; Mallick, S.; Everson, E. D.; Tobin, H. J.; Keranen, K. M.

2014-12-01

Understanding the geologic composition of the Cascadia Subduction Zone (CSZ) is critically important in assessing seismic hazards in the Pacific Northwest. Despite being a potential earthquake and tsunami threat to millions of people, key details of the structure and fault mechanisms remain poorly understood in the CSZ. In particular, the position and character of the subduction interface remains elusive due to its relative aseismicity and low seismic reflectivity, making imaging difficult for both passive and active source methods. Modern active-source reflection seismic data acquired as part of the COAST project in 2012 provide an opportunity to study the transition from the Cascadia basin, across the deformation front, and into the accretionary prism. Coupled with advances in seismic inversion methods, this new data allow us to produce detailed velocity models of the CSZ and accurate pre-stack depth migrations for studying geologic structure. While still computationally expensive, current computing clusters can perform seismic inversions at resolutions that match that of the seismic image itself. Here we present pre-stack full waveform inversions of the central seismic line of the COAST survey offshore Washington state. The resultant velocity model is produced by inversion at every CMP location, 6.25 m laterally, with vertical resolution of 0.2 times the dominant seismic frequency. We report a good average correlation value above 0.8 across the entire seismic line, determined by comparing synthetic gathers to the real pre-stack gathers. These detailed velocity models, both Vp and Vs, along with the density model, are a necessary step toward a detailed porosity cross section to be used to determine the role of fluids in the CSZ. Additionally, the P-velocity model is used to produce a pre-stack depth migration image of the CSZ.

Modern Processes of Hydrocarbon Migration and Re-Formation of Oil and Gas Fields (Based on the Results of Monitoring and Geochemical Studies)

NASA Astrophysics Data System (ADS)

Plotnikova, Irina; Salakhidinova, Gulmira; Nosova, Fidania; Pronin, Nikita; Ostroukhov, Sergey

2015-04-01

Special geochemical studies of oils allowed to allocate a movable migration component of oils in the industrial oil deposits. In the field the migration component of oils varies in different parts of the field. The largest percentage of the light migration component (gas condensate of the oil) was detected in the central part of the Kama-Kinel troughs system. Monitoring of the composition of water, oil and gas (condensate light oil component) in the sedimentary cover and ni crystalline basement led to the conclusion of modern migration of hydrocarbons in sedimentary cover. This proves the existence of the modern processes of formation and reformation of oil and gas fields. This presentation is dedicated to the problem of definition of geochemical criteria of selection of hydrocarbons deposit reformation zone in the sample wells of Minibaevskaya area of Romashkinskoye field. While carrying out this work we examined 11 samples of oil from the Upper Devonian Pashiysky horizon. Four oil samples were collected from wells reckoned among the "anomalous" zones that were marked out according to the results of geophysical, oil field and geological research. Geochemical studies of oils were conducted in the laboratory of geochemistry of the Kazan (Volga-region) Federal University. The wells where the signs of hydrocarbons influx from the deep zones of the crust were recorded are considered to be "anomalous". A number of scientists connect this fact to the hypothesis about periodic influx of deep hydrocarbons to the oil deposits of Romashkinskoye field. Other researchers believe that the source rocks of the adjacent valleys sedimentary cover generate gases when entering the main zone of gas formation, which then migrate up the section and passing through the previously formed deposits of oil, change and "lighten" their composition. Regardless of the point of view on the source of the hydrocarbons, the study of the process of deposits refilling with light hydrocarbons is an important fundamental task of exceptional practical importance. The reservoir water monitoring has been conducted in five wells that have penetrated the water-saturated, loosely aggregated zones of the South Tatarstan Arch's basement. The long-term testing resulted in the production of reservoir water from the basement. The sedimentary cover in these wells is blocked by the column, which prevents water cross-flowing from the sedimentary cover. The observations have shown that the levels, gas saturation, mineralisation, density, and composition of reservoir waters from the loosely aggregated zones of the basement change with time. The varying characteristics of the water include its component composition, redox potential, and amount of chlorine and some other components and trace elements. Compositional changes in gases of the loosely aggregated zones of the basement, variations in the gas saturation of reservoir waters and of their composition, the decreasing density of oil in the sedimentary cover, - all result from one cause. This cause is the movement of fluids (solutions and gases dissolved in them) through the loosely aggregated zones and faults of the Earth's crust and the sedimentary cover. The fluids mainly move vertically in an upward direction, although their migration through subhorizontal, loosely aggregated zones of the crystalline basement is also possible. Fluid migration still takes place in the Earth's crust of ancient platforms. This phenomenon indicates that some portions of the platforms - primarily, their margins - periodically resume tectonic activities. The fluid dynamic activity of the crust define the processes in the sedimentary cover. It affects the development of the sedimentary basin during the sedimentation period, and the formation of mineral deposits. The monitoring of the present-day movement of fluid systems in the loosely aggregated zones of the basement will permit the more detailed study of the present-day fluid regime in the upper portion of the Earth's crust and the sedimentary cover.

Simulating the Evolving Behavior of Secondary Slow Slip Fronts

NASA Astrophysics Data System (ADS)

Peng, Y.; Rubin, A. M.

2017-12-01

High-resolution tremor catalogs of slow slip events reveal secondary slow slip fronts behind the main front that repetitively occupy the same source area during a single episode. These repetitive fronts are most often observed in regions with high tremor density. Their recurrence intervals gradually increase from being too short to be tidally modulated (tens of minutes) to being close to tidal periods (about 12 or 24 hours). This could be explained by a decreasing loading rate from creep in the surrounding regions (with few or no observable tremor events) as the main front passes by. As the recurrence intervals of the fronts increase, eventually they lock in on the tidal periods. We attempt to simulate this numerically using a rate-and-state friction law that transitions from velocity-weakening at low slip speeds to velocity strengthening at high slip speeds. Many small circular patches with a cutoff velocity an order of magnitude higher than that of the background are randomly placed on the fault, in order to simulate the average properties of the high-density tremor zone. Preliminary results show that given reasonable parameters, this model produces similar propagation speeds of the forward-migrating main front inside and outside the high-density tremor zone, consistent with observations. We will explore the behavior of the secondary fronts that arise in this model, in relation to the local density of the small tremor-analog patches, the overall geometry of the tremor zone and the tides.

Controls on fault zone structure and brittle fracturing in the foliated hanging wall of the Alpine Fault

NASA Astrophysics Data System (ADS)

Williams, Jack N.; Toy, Virginia G.; Massiot, Cécile; McNamara, David D.; Smith, Steven A. F.; Mills, Steven

2018-04-01

Three datasets are used to quantify fracture density, orientation, and fill in the foliated hanging wall of the Alpine Fault: (1) X-ray computed tomography (CT) images of drill core collected within 25 m of its principal slip zones (PSZs) during the first phase of the Deep Fault Drilling Project that were reoriented with respect to borehole televiewer images, (2) field measurements from creek sections up to 500 m from the PSZs, and (3) CT images of oriented drill core collected during the Amethyst Hydro Project at distances of ˜ 0.7-2 km from the PSZs. Results show that within 160 m of the PSZs in foliated cataclasites and ultramylonites, gouge-filled fractures exhibit a wide range of orientations. At these distances, fractures are interpreted to have formed at relatively high confining pressures and/or in rocks that had a weak mechanical anisotropy. Conversely, at distances greater than 160 m from the PSZs, fractures are typically open and subparallel to the mylonitic or schistose foliation, implying that fracturing occurred at low confining pressures and/or in rocks that were mechanically anisotropic. Fracture density is similar across the ˜ 500 m width of the field transects. By combining our datasets with measurements of permeability and seismic velocity around the Alpine Fault, we further develop the hierarchical model for hanging-wall damage structure that was proposed by Townend et al. (2017). The wider zone of foliation-parallel fractures represents an outer damage zone that forms at shallow depths. The distinct < 160 m wide interval of widely oriented gouge-filled fractures constitutes an inner damage zone. This zone is interpreted to extend towards the base of the seismogenic crust given that its width is comparable to (1) the Alpine Fault low-velocity zone detected by fault zone guided waves and (2) damage zones reported from other exhumed large-displacement faults. In summary, a narrow zone of fracturing at the base of the Alpine Fault's hanging-wall seismogenic crust is anticipated to widen at shallow depths, which is consistent with fault zone flower structure models.

Hybrid friction stir welding for dissimilar materials through electro-plastic effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xun; Lan, Shuhuai; Ni, Jun

A hybrid Friction Stir Welding approach and device for dissimilar materials joining employing Electro-Plastic Effect. The approach and device include an introduction of high density, short period current pulses into traditional friction stir welding process, which therefore can generate a localized softened zone in the workpiece during plastic stirring without significant additional temperature increase. This material softened zone is created by high density current pulses based on Electro-Plastic Effect and will move along with the friction stir welding tool. Smaller downward force, larger processing window and better joint quality for dissimilar materials are expected to be achieved through this hybridmore » welding technique.« less

A minimalist probabilistic description of root zone soil water

USGS Publications Warehouse

Milly, P.C.D.

2001-01-01

The probabilistic response of depth‐integrated soil water to given climatic forcing can be described readily using an existing supply‐demand‐storage model. An apparently complex interaction of numerous soil, climate, and plant controls can be reduced to a relatively simple expression for the equilibrium probability density function of soil water as a function of only two dimensionless parameters. These are the index of dryness (ratio of mean potential evaporation to mean precipitation) and a dimensionless storage capacity (active root zone soil water capacity divided by mean storm depth). The first parameter is mainly controlled by climate, with surface albedo playing a subsidiary role in determining net radiation. The second is a composite of soil (through moisture retention characteristics), vegetation (through rooting characteristics), and climate (mean storm depth). This minimalist analysis captures many essential features of a more general probabilistic analysis, but with a considerable reduction in complexity and consequent elucidation of the critical controls on soil water variability. In particular, it is shown that (1) the dependence of mean soil water on the index of dryness approaches a step function in the limit of large soil water capacity; (2) soil water variance is usually maximized when the index of dryness equals 1, and the width of the peak varies inversely with dimensionless storage capacity; (3) soil water has a uniform probability density function when the index of dryness is 1 and the dimensionless storage capacity is large; and (4) the soil water probability density function is bimodal if and only if the index of dryness is <1, but this bimodality is pronounced only for artificially small values of the dimensionless storage capacity.

47 CFR 101.113 - Transmitter power limitations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... notice and opportunity for hearing, order a change in the effective radiated power of this station... are in the same 1 MHz within the designated frequency band. (ii) The climate zones in Table 1 are... Regulations. Table 1 1 Climate zone e.i.r.p. Spectral Density (Clear Air) (dBW/MHz-km 2) 2 1 −23 2 −25 3,4,5...

A Theoretical Analysis of the Influence of Electroosmosis on the Effective Ionic Mobility in Capillary Zone Electrophoresis

ERIC Educational Resources Information Center

Hijnen, Hens

2009-01-01

A theoretical description of the influence of electroosmosis on the effective mobility of simple ions in capillary zone electrophoresis is presented. The mathematical equations derived from the space-charge model contain the pK[subscript a] value and the density of the weak acid surface groups as parameters characterizing the capillary. It is…

Variability of soil properties within large termite mounds in South Katanga, DRC - origins and applications.

NASA Astrophysics Data System (ADS)

Erens, Hans; Bazirake Mujinya, Basile; Boeckx, Pascal; Baert, Geert; Mees, Florias; Van Ranst, Eric

2014-05-01

The miombo woodlands of South Katanga (D.R. Congo) are characterized by a high spatial density of large conic termite mounds built by Macrotermes falciger (3 to 5 ha-1). With an average height of 5.05 m and diameter of 14.88 m, these are some of the largest biogenic structures in the world. The mound material is known to differ considerably from the surrounding Ferralsols. Specifically, mound material exhibits a finer texture, higher CEC and exchangeable basic cation content, lower organic matter content, and an accumulation of phosphorous, nitrate and secondary carbonates. However, as demonstrated by the present study, these soil properties are far from uniform within the volume of the mound. The termites' nesting and foraging activity, combined with pedogenic processes over extended periods of time, generates a wide range of physical, chemical, and biological conditions in different parts of the mound. Analysis of samples taken along a cross-section of a large active mound allowed generating contour plots, thus visualizing the variability of soil properties within the mound. The central columns of three other mounds were sampled to confirm apparent trends. The contour plots show that the mounds comprise four functional zones: (i) the active nest, found at the top; (ii) an accumulation zone , in more central parts of the mound; (iii) a dense inactive zone, surrounding the accumulation zone and consisting of accumulated erosion products from former active nests; and (iv) the outer mantle, characterized by intense varied biological activity and by a well-developed soil structure. Intermittent leaching plays a key role in explaining these patterns. Using radiocarbon dating, we found that some of these mounds are at least 2000 years old. Their current size and shape is likely the result of successive stages of erosion and rebuilding, in the course of alternating periods of mound abandonment and recolonization. Over time, termite foraging combined with limited leaching results in the mounds becoming nutrient sinks. As the mounds contain over 1000 m³ ha-1 of soil, they represent a considerable part of the total nutrient budget of the ecosystem. A recent development in the Lubumbashi region is the advent of large-scale pivot-irrigated agriculture. The termite mounds in new fields are completely leveled, thus dispersing the accumulated nutrients. Our study predicts short- and long-term effects of termite mound spreading on soil fertility.

Prevention of the spread of rabies to wildlife by oral vaccination of raccoons in Massachusetts.

PubMed

Robbins, A H; Borden, M D; Windmiller, B S; Niezgoda, M; Marcus, L C; O'Brien, S M; Kreindel, S M; McGuill, M W; DeMaria, A; Rupprecht, C E; Rowell, S

1998-11-15

To evaluate the use of bait containing rabies vaccine to create a barrier of rabies-vaccinated raccoons in Massachusetts and to determine the effectiveness of various bait distribution strategies in halting the spread of rabies. Prospective study. Free-ranging raccoons. Baits were distributed twice yearly in a 207-km2 (80-mi2) area in the vicinity of the Cape Cod Canal. Bait density and distribution strategy varied among 3 treatment areas. Raccoons were caught in live traps after bait distribution and anesthetized; blood samples were obtained to measure serum antibody titers to rabies virus. Vaccination rates were determined by the percentage of captured raccoons with antibody titers to rabies virus > or = 1:5. In addition, raccoons with clinical signs of illness inside the vaccination zone and adjacent areas were euthanatized and submitted for rabies testing. The percentage of vaccinated raccoons differed significantly among the following 3 areas with various bait densities: high-density area with uniform bait distribution (103 baits/km2 [267 baits/mi2]) = 37%; low-density area with additional targeted bait distribution (93 baits/km2 [240 baits/mi2]) = 67%; and, high-density area with additional targeted bait distribution (135 baits/km2 [350 baits/mi2]) = 77%. Nineteen animals with rabies (15 raccoons, 3 skunks, 1 cat) were reported in the area just outside of the vaccination zone, but only 1 raccoon with rabies was reported from inside the vaccination zone. In this suburban study area, an approximate vaccination rate of 63% was sufficient to halt the spread of rabies in free-ranging raccoons. Compared with uniform bait distribution, targeting raccoon habitats increased vaccination rates.

78 FR 68026 - Foreign-Trade Zone 32-Miami, Florida, Authorization of Production Activity, Almod Diamonds, Ltd...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-13

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-69-2013] Foreign-Trade Zone 32--Miami, Florida, Authorization of Production Activity, Almod Diamonds, Ltd. (Jewelry and Precious Stones), Miami, Florida On June 21, 2013, the Greater Miami Foreign-Trade Zone, Inc., grantee of FTZ 32, submitted a notification of proposed production activity to...

Geology and Geohydrology at CRREL, Hanover, New Hampshire: Relationship to Subsurface Contamination

DTIC Science & Technology

1992-11-01

8217 4345’ -. . . p L E G E N D --------O :------- ’ 0. .. -/ KYANITE - STAUROLITE / ~ . -*ZONE - • STAUROLITE ZONE / ,’’"’’":’:": E• GARNJET ZONE...water partition coefficient: 126 mL/g to the following equation (after Hubbert 1953) Density: 1.46 g/cm 3 Boiling point at 760 torr pressure: 87°C...Washington, D.C.: U.S. Govern-Bullein No 19.ment Printing Office. Stewart, D.P. and P. MacClintock (1969) The surfi- melt Png O.cial geology and pleistocene

Response of soft-bottom macrobenthic assemblages to artisanal trawling fisheries in a subtropical estuary

NASA Astrophysics Data System (ADS)

Ortega, Ileana; Colling, Leonir André; Dumont, Luiz Felipe Cestari

2018-07-01

Bottom trawling is one of the most harmful and widespread activities affecting benthic habitats and fauna. In this study, we analyzed the impact of shrimp trawling fisheries on the densities, assemblage structure and vertical stratification of the benthic macrofauna in shallow mudflats of the Patos Lagoon Estuary (Brazil). Experimental trawls of different intensities were performed during three shrimp fishing seasons (2015-2017), comparing macrofauna among before and after trawling, and a control zone. The changes in macrofaunal assemblages were more consistently related to natural variability than to trawling impact, being mostly influenced by sediment structure and salinity variation. The trawling impact was mainly detected in the area with higher percentages of fine sediments, with different macrofaunal responses in each month and stratum. Some non-significant decreases on total densities after trawling were observed, mainly on the superficial stratum, and signs of burial activities. The response to trawling disturbance of each species was different and it highly depended on their natural variability. Only five species showed significant variation to the trawling treatment (Erodona mactroides, Heleobia australis, H. charruana, Heteromastus similis and Laeonereis acuta), with temporally different responses. Decreasing densities were more related to the high impact treatment. In some seasons, decreases on the abundance of Monokalliapseudes schubarti after high impact trawls were up to 60% of the seasonal mean densities. Trawling fisheries may reduce macrobenthic densities but not their vertical stratification. The impact of trawling on key species may compromise the ecosystem function, as benthic macrofauna provide food sources for many aquatic resources. This study highlights trawling impacts in an estuarine nursery area, which should be fully considered since they may be reflected in the trophic webs.

Extrapolating cetacean densities to quantitatively assess human impacts on populations in the high seas.

PubMed

Mannocci, Laura; Roberts, Jason J; Miller, David L; Halpin, Patrick N

2017-06-01

As human activities expand beyond national jurisdictions to the high seas, there is an increasing need to consider anthropogenic impacts to species inhabiting these waters. The current scarcity of scientific observations of cetaceans in the high seas impedes the assessment of population-level impacts of these activities. We developed plausible density estimates to facilitate a quantitative assessment of anthropogenic impacts on cetacean populations in these waters. Our study region extended from a well-surveyed region within the U.S. Exclusive Economic Zone into a large region of the western North Atlantic sparsely surveyed for cetaceans. We modeled densities of 15 cetacean taxa with available line transect survey data and habitat covariates and extrapolated predictions to sparsely surveyed regions. We formulated models to reduce the extent of extrapolation beyond covariate ranges, and constrained them to model simple and generalizable relationships. To evaluate confidence in the predictions, we mapped where predictions were made outside sampled covariate ranges, examined alternate models, and compared predicted densities with maps of sightings from sources that could not be integrated into our models. Confidence levels in model results depended on the taxon and geographic area and highlighted the need for additional surveying in environmentally distinct areas. With application of necessary caution, our density estimates can inform management needs in the high seas, such as the quantification of potential cetacean interactions with military training exercises, shipping, fisheries, and deep-sea mining and be used to delineate areas of special biological significance in international waters. Our approach is generally applicable to other marine taxa and geographic regions for which management will be implemented but data are sparse. © 2016 The Authors. Conservation Biology published by Wiley Periodicals, Inc. on behalf of Society for Conservation Biology.

Gravity and magnetic anomalies used to delineate geologic features associated with earthquakes and aftershocks in the central Virginia seismic zone

NASA Astrophysics Data System (ADS)

Shah, A. K.; Horton, J.; McNamara, D. E.; Spears, D.; Burton, W. C.

2013-12-01

Estimating seismic hazard in intraplate environments can be challenging partly because events are relatively rare and associated data thus limited. Additionally, in areas such as the central Virginia seismic zone, numerous pre-existing faults may or may not be candidates for modern tectonic activity, and other faults may not have been mapped. It is thus important to determine whether or not specific geologic features are associated with seismic events. Geophysical and geologic data collected in response to the Mw5.8 August 23, 2011 central Virginia earthquake provide excellent tools for this purpose. Portable seismographs deployed within days of the main shock showed a series of aftershocks mostly occurring at depths of 3-8 km along a southeast-dipping tabular zone ~10 km long, interpreted as the causative fault or fault zone. These instruments also recorded shallow (< 4 km) aftershocks clustered in several areas at distances of ~2-15 km from the main fault zone. We use new airborne geophysical surveys (gravity, magnetics, radiometrics, and LiDAR) to delineate the distribution of various surface and subsurface geologic features of interest in areas where the earthquake and aftershocks took place. The main (causative fault) aftershock cluster coincides with a linear, NE-trending gravity gradient (~ 2 mgal/km) that extends over 20 km in either direction from the Mw5.8 epicenter. Gravity modeling incorporating seismic estimates of Moho variations suggests the presence of a shallow low-density body overlying the main aftershock cluster, placing it within the upper 2-4 km of the main-fault hanging wall. The gravity, magnetic, and radiometric data also show a bend in generally NE-SW orientation of anomalies close to the Mw5.8 epicenter. Most shallow aftershock clusters occur near weaker short-wavelength gravity gradients of one to several km length. In several cases these gradients correspond to geologic contacts mapped at the surface. Along the gravity gradients, the aftershocks appear to cluster near areas with cross-cutting geologic features such as Jurassic diabase dikes. These associations suggest that local variations in rock density and/or rheology may have contributed to modifications of local stress regimes in a manner encouraging localized seismicity associated with the Mw5.8 event and its aftershocks. Such associations are comparable to results of previous studies recognizing correspondences between seismicity and features such as intrusive bodies and failed rifts in the New Madrid seismic zone and elsewhere. To explore whether similar correspondences may have occurred in the past, we use regional gravity and magnetic data to consider possible relations between historical earthquakes and comparable geologic features elsewhere in the central Virginia seismic zone.

Comparative study of He bubble formation in nanostructured reduced activation steel and its coarsen-grained counterpart

NASA Astrophysics Data System (ADS)

Liu, W. B.; Zhang, J. H.; Ji, Y. Z.; Xia, L. D.; Liu, H. P.; Yun, D.; He, C. H.; Zhang, C.; Yang, Z. G.

2018-03-01

High temperature (550 °C) He ions irradiation was performed on nanostructured (NS) and coarsen-grained (CG) reduced activation steel to investigate the effects of GBs/interfaces on the formation of bubbles during irradiation. Experimental results showed that He bubbles were preferentially trapped at dislocations and/or grain boundaries (GBs) for both of the samples. Void denuded zones (VDZs) were observed in the CG samples, while VDZs near GBs were unobvious in NS sample. However, both the average bubble size and the bubble density in peak damage region of the CG sample were significantly larger than that observed in the NS sample, which indicated that GBs play an important role during the irradiation, and the NS steel had better irradiation resistance than its CG counterpart.

Assessment of groundwater potential zones using multi-influencing factor (MIF) and GIS: a case study from Birbhum district, West Bengal

NASA Astrophysics Data System (ADS)

Thapa, Raju; Gupta, Srimanta; Guin, Shirshendu; Kaur, Harjeet

2017-11-01

Remote sensing and GIS play a vital role in exploration and assessment of groundwater and has wide application in detection, monitoring, assessment, conservation and various other fields of groundwater-related studies. In this research work, delineation of groundwater potential zone in Birbhum district has been carried out. Various thematic layers viz. geology, geomorphology, soil type, elevation, lineament and fault density, slope, drainage density, land use/land cover, soil texture, and rainfall are digitized and transformed into raster data in ArcGIS 10.3 environment as input factors. Thereafter, multi-influencing factor (MIF) technique is employed where ranks and weights, assigned to each factor are computed statistically. Finally, groundwater potential zones are classified into four categories namely low, medium, high and very high zone. It is observed that 18.41% (836.86 km2) and 34.41% (1563.98 km2) of the study area falls under `low' and `medium' groundwater potential zone, respectively. Approximately 1601.19 km2 area accounting for 35.23% of the study area falls under `high' category and `very high' groundwater potential zone encompasses an area of 542.98 km2 accounting for 11.95% of the total study area. Finally, the model generated groundwater potential zones are validated with reported potential yield data of various wells in the study area. Success and prediction rate curve reveals an accuracy achievement of 83.03 and 78%, respectively. The outcome of the present research work will help the local authorities, researchers, decision makers and planners in formulating better planning and management of groundwater resources in the study area in future perspectives.

The damage is done: Low fault friction recorded in the damage zone of the shallow Japan Trench décollement

NASA Astrophysics Data System (ADS)

Keren, Tucker T.; Kirkpatrick, James D.

2016-05-01

Fault damage zones record the integrated deformation caused by repeated slip on faults and reflect the conditions that control slip behavior. To investigate the Japan Trench décollement, we characterized the damage zone close to the fault from drill core recovered during Integrated Ocean Drilling Program Expedition 343 (Japan Trench Fast Drilling Project (JFAST)). Core-scale and microscale structures include phyllosilicate bands, shear fractures, and joints. They are most abundant near the décollement and decrease in density sharply above and below the fault. Power law fits describing the change in structure density with distance from the fault result in decay exponents (n) of 1.57 in the footwall and 0.73 in the hanging wall. Microstructure decay exponents are 1.09 in the footwall and 0.50 in the hanging wall. Observed damage zone thickness is on the order of a few tens of meters. Core-scale structures dip between ~10° and ~70° and are mutually crosscutting. Compared to similar offset faults, the décollement has large decay exponents and a relatively narrow damage zone. Motivated by independent constraints demonstrating that the plate boundary is weak, we tested if the observed damage zone characteristics could be consistent with low-friction fault. Quasi-static models of off-fault stresses and deformation due to slip on a wavy, frictional fault under conditions similar to the JFAST site predict that low-friction fault produces narrow damage zones with no preferred orientations of structures. These results are consistent with long-term frictional weakness on the décollement at the JFAST site.

Examining patterns of bat activity in Bandelier National Monument, New Mexico, using walking point transects

USGS Publications Warehouse

Ellison, L.E.; Everette, A.L.; Bogan, M.A.

2005-01-01

We conducted a preliminary study using small field crews, a single Anabat II detector coupled with a laptop computer, and point transects to examine patterns of bat activity at a scale of interest to local resource managers. The study was conducted during summers of 1996–1998 in Bandelier National Monument in the Jemez Mountains of northern New Mexico, a landscape with distinct vegetation zones and high species richness of bats. We developed simple models that described general patterns of acoustic activity within 4 vegetation zones based primarily on nightly variation and a qualitative index of habitat complexity. Bat acoustic activity (number of bat passes&sol point) did not vary dramatically among a limited sample of transects within a vegetation zone during 1996. In 1997 and 1998, single transects within each vegetation zone were established, and bat activity did not vary annually within these zones. Acoustic activity differed among the 4 vegetation zones of interest, with the greatest activity occurring in riparian canyon bottomland, intermediate activity in coniferous forest and a 1977 burned zone, and lowest activity in piñon-juniper woodlands. We identified 68.5% of 2,529 bat passes recorded during point-transect surveys to species using an echolocation call reference library we established for the area and qualitative characteristics of bat calls. Bat species richness and composition differed among vegetation zones. Results of these efforts were consistent with general knowledge of where different bat species typically forage and with the natural history of bats of New Mexico, suggesting such a method might have value for drawing inferences about bat activity in different vegetation zones.

Performance analysis of a brushless dc motor due to magnetization distribution in a continuous ring magnet

NASA Astrophysics Data System (ADS)

Hur, Jin; Jung, In-Soung; Sung, Ha-Gyeong; Park, Soon-Sup

2003-05-01

This paper represents the force performance of a brushless dc motor with a continuous ring-type permanent magnet (PM), considering its magnetization patterns: trapezoidal, trapezoidal with dead zone, and unbalanced trapezoidal magnetization with dead zone. The radial force density in PM motor causes vibration, because vibration is induced the traveling force from the rotating PM acting on the stator. Magnetization distribution of the PM as well as the shape of the teeth determines the distribution of force density. In particular, the distribution has a three-dimensional (3-D) pattern because of overhang, that is, it is not uniform in axial direction. Thus, the analysis of radial force density required dynamic analysis considering the 3-D shape of the teeth and overhang. The results show that the force density as a source of vibration varies considerably depending on the overhang and magnetization distribution patterns. In addition, the validity of the developed method, coupled 3-D equivalent magnetic circuit network method, with driving circuit and motion equation, is confirmed by comparison of conventional method using 3D finite element method.

On the mechanism of the ring zone effect obtained with the mixed haemadsorption technique

PubMed Central

Jonsson, J.; Fagraeus, Astrid

1969-01-01

A ring zone effect noted with the radial diffusion disc test modification of the mixed haemadsorption technique has been studied using human anti-thyroid sera reacting with thyroid monolayer cultures. Results are presented which suggest that the `empty' centre of the ring zones is due to an excess of attached antibody. Sera giving the ring zone effect contain a larger number of antibody specificities than those producing filled zones. The appearance of ring zones is favoured by a low density of antigens on the culture. These findings and a number of synergistic effects produced by mixing ring and filled zone reactions are compatible with the hypothesis that the ring zone is produced when several antibodies of different specificities react with restricted antigenic areas carrying densely located clusters of antigenic determinants representing the different specificities contained in the ring zone sera. The crowding of antibodies on the clusters in the centre of the ring zones creates a steric hindrance for the indicator cells so that they are not firmly attached in this area. The antibody zone is therefore indicated as a peripheral haemadsorption ring. ImagesFIG. 1FIG. 2FIG. 4FIG. 6FIG. 7FIG. 9 PMID:5307718

Eggshells as an index of aedine mosquito production. 2: Relationship of Aedes taeniorhynchus eggshell density to larval production.

PubMed

Addison, D S; Ritchie, S A; Webber, L A; Van Essen, F

1992-03-01

To test if eggshell density could be used as an index of aedine mosquito production, we compared eggshell density with the larval production of Aedes taeniorhynchus in Florida mangrove basin forests. Quantitative (n = 7) and categorical (n = 34) estimates of annual larval production were regressed against the number of eggshells per cc of soil. Significant regressions were obtained in both instances. Larval production was concentrated in zones with the highest eggshell density. We suggest that eggshell density and distribution can be used to identify oviposition sites and the sequence of larval appearance.

Subduction factory 1. Theoretical mineralogy, densities, seismic wave speeds, and H2O contents

NASA Astrophysics Data System (ADS)

Hacker, Bradley R.; Abers, Geoffrey A.; Peacock, Simon M.

2003-01-01

We present a new compilation of physical properties of minerals relevant to subduction zones and new phase diagrams for mid-ocean ridge basalt, lherzolite, depleted lherzolite, harzburgite, and serpentinite. We use these data to calculate H2O content, density and seismic wave speeds of subduction zone rocks. These calculations provide a new basis for evaluating the subduction factory, including (1) the presence of hydrous phases and the distribution of H2O within a subduction zone; (2) the densification of the subducting slab and resultant effects on measured gravity and slab shape; and (3) the variations in seismic wave speeds resulting from thermal and metamorphic processes at depth. In considering specific examples, we find that for ocean basins worldwide the lower oceanic crust is partially hydrated (<1.3 wt % H2O), and the uppermost mantle ranges from unhydrated to ˜20% serpentinized (˜2.4 wt % H2O). Anhydrous eclogite cannot be distinguished from harzburgite on the basis of wave speeds, but its ˜6% greater density may render it detectable through gravity measurements. Subducted hydrous crust in cold slabs can persist to several gigapascals at seismic velocities that are several percent slower than the surrounding mantle. Seismic velocities and VP/VS ratios indicate that mantle wedges locally reach 60-80% hydration.

EMITTING ELECTRONS AND SOURCE ACTIVITY IN MARKARIAN 501

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mankuzhiyil, Nijil; Ansoldi, Stefano; Persic, Massimo

2012-07-10

We study the variation of the broadband spectral energy distribution (SED) of the BL Lac object Mrk 501 as a function of source activity, from quiescent to flaring. Through {chi}{sup 2}-minimization we model eight simultaneous SED data sets with a one-zone synchrotron self-Compton (SSC) model, and examine how model parameters vary with source activity. The emerging variability pattern of Mrk 501 is complex, with the Compton component arising from {gamma}-e scatterings that sometimes are (mostly) Thomson and sometimes (mostly) extreme Klein-Nishina. This can be seen from the variation of the Compton to synchrotron peak distance according to source state. Themore » underlying electron spectra are faint/soft in quiescent states and bright/hard in flaring states. A comparison with Mrk 421 suggests that the typical values of the SSC parameters are different in the two sources: however, in both jets the energy density is particle-dominated in all states.« less

Vessel architecture in human knee cartilage in children: an in vivo susceptibility-weighted imaging study at 7 T.

PubMed

Kolb, Alexander; Robinson, Simon; Stelzeneder, David; Schreiner, Markus; Chiari, Catharina; Windhager, Reinhard; Trattnig, Siegfried; Bohndorf, Klaus

2018-02-26

To evaluate the clinical feasibility of ultrahigh field 7-T SWI to visualize vessels and assess their density in the immature epiphyseal cartilage of human knee joints. 7-T SWI of 12 knees (six healthy volunteers, six patients with osteochondral abnormalities; mean age 10.7 years; 3 female, 9 male) were analysed by two readers, classifying intracartilaginous vessel densities (IVD) in three grades (no vessels, low IVD and high IVD) in defined femoral, tibial and patellar zones. Differences between patients and volunteers, IVDs in different anatomic locations, differences between cartilage overlying osteochondral abnormalities and corresponding normal zones, and differences in age groups were analysed. Interrater reliability showed moderate agreement between the two readers (κ = 0.58, p < 0.001). The comparison of IVDs between patients and volunteers revealed no significant difference (p = 0.706). The difference between zones in the cartilage overlying osteochondral abnormalities to corresponding normal zones showed no significant difference (p = 0.564). IVDs were related to anatomic location, with decreased IVDs in loading areas (p = 0.003). IVD was age dependent, with more vessels present in the younger participants (p = 0.001). The use of SWI in conjunction with ultrahigh field MRI makes the in vivo visualization of vessels in the growing cartilage of humans feasible, providing insights into the role of the vessel network in acquired disturbances. • SWI facilitates in vivo visualization of vessels in the growing human cartilage. • Interrater reliability of the intracartilaginous vessel grading was moderate. • Intracartilaginous vessel densities are dependent on anatomical location and age.

Significant inconsistency of vegetation carbon density in CMIP5 Earth system models against observational data

NASA Astrophysics Data System (ADS)

Song, Xia; Hoffman, Forrest M.; Iversen, Colleen M.; Yin, Yunhe; Kumar, Jitendra; Ma, Chun; Xu, Xiaofeng

2017-09-01

Earth system models (ESMs) have been widely used for projecting global vegetation carbon dynamics, yet how well ESMs performed for simulating vegetation carbon density remains untested. We compiled observational data of vegetation carbon density from literature and existing data sets to evaluate nine ESMs at site, biome, latitude, and global scales. Three variables—root (including fine and coarse roots), total vegetation carbon density, and the root:total vegetation carbon ratios (R/T ratios), were chosen for ESM evaluation. ESM models performed well in simulating the spatial distribution of carbon densities in root (r = 0.71) and total vegetation (r = 0.62). However, ESM models had significant biases in simulating absolute carbon densities in root and total vegetation biomass across the majority of land ecosystems, especially in tropical and arctic ecosystems. Particularly, ESMs significantly overestimated carbon density in root (183%) and total vegetation biomass (167%) in climate zones of 10°S-10°N. Substantial discrepancies between modeled and observed R/T ratios were found: the R/T ratios from ESMs were relatively constant, approximately 0.2 across all ecosystems, along latitudinal gradients, and in tropic, temperate, and arctic climatic zones, which was significantly different from the observed large variations in the R/T ratios (0.1-0.8). There were substantial inconsistencies between ESM-derived carbon density in root and total vegetation biomass and the R/T ratio at multiple scales, indicating urgent needs for model improvements on carbon allocation algorithms and more intensive field campaigns targeting carbon density in all key vegetation components.

The Three-part Structure of a Filament-unrelated Solar Coronal Mass Ejection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, H. Q.; Chen, Y.; Wang, B.

Coronal mass ejections (CMEs) often exhibit the typical three-part structure in the corona when observed with white-light coronagraphs, i.e., the bright leading front, dark cavity, and bright core, corresponding to a high-low-high density sequence. As CMEs result from eruptions of magnetic flux ropes (MFRs), which can possess either lower (e.g., coronal-cavity MFRs) or higher (e.g., hot-channel MFRs) density compared to their surroundings in the corona, the traditional opinion regards the three-part structure as the manifestations of coronal plasma pileup (high density), coronal-cavity MFR (low density), and filament (high density) contained in the trailing part of MFR, respectively. In this paper,more » we demonstrate that filament-unrelated CMEs can also exhibit the classical three-part structure. The observations were made from different perspectives through an event that occurred on 2011 October 4. The CME cavity corresponds to the low-density zone between the leading front and the high-density core, and it is obvious in the low corona and gradually becomes fuzzy when propagating outward. The bright core corresponds to a high-density structure that is suggested to be an erupting MFR. The MFR is recorded from both edge-on and face-on perspectives, exhibiting different morphologies that are due to projection effects. We stress that the zone (MFR) with lower (higher) density in comparison to the surroundings can appear as the dark cavity (bright core) when observed through white-light coronagraphs, which is not necessarily the coronal-cavity MFR (erupted filament).« less

Assessment of groundwater recharge potential zone using GIS approach in Purworejo regency, Central Java province, Indonesia

NASA Astrophysics Data System (ADS)

Aryanto, Daniel Eko; Hardiman, Gagoek

2018-02-01

Floods and droughts in Purworejo regency are an indication of problems in groundwater management. The current development progress has led to land conversion which has an impact on the problem of water infiltration in Purworejo regency. This study aims to determine the distribution of groundwater recharge potential zones by using geographic information system as the basis for ground water management. The groundwater recharge potential zone is obtained by overlaying all the thematic maps that affect the groundwater infiltration. Each thematic map is weighted according to its effect on groundwater infiltration such as land-use - 25%, rainfall - 20%, litology - 20%, soil - 15%, slope - 10%, lineament - 5%, and river density - 5% to find groundwater recharge potential zones. The groundwater recharge potential zones thus obtained were divided into five categories, viz., very high, high, medium, low and very low zones. The results of this study may be useful for better groundwater planning and management.

Ocean Exploration and Drug Discovery in the Twilight Zone

NASA Astrophysics Data System (ADS)

Slattery, M.; Gochfeld, D.; Lesser, M.

2006-12-01

The transition between shallow coral reef communities and aphotic deep-water communities in the tropics (= 50m to 150m) is often called the "twilight zone", and it is characterized by reduced light and consequently photosynthesis. But while reef-building coral diversity decreases with increasing depth, many sponges, soft corals, and even low-light acclimatized primary producers are abundant. Thus, this is a zone of potentially incredible ecological significance, unique biodiversity, and unusual physiological adaptations where one might expect to find important natural products that might be used as pharmaceuticals or other biotechnology products. This is also one of the least studied ecosystems in the marine environment since it exceeds the limits of traditional SCUBA, but is considered too shallow to warrant costly submersible time. We have examined the Twilight Zone off the Exuma Sound Shelf, Bahamas, over the last three years using technical mixed gas diving. Biodiversity data indicate a rich sponge community consisting of 92 species and approximately 15% endemism. Sponge diversity and density increased with depth as picoplankton food abundance increased. Sponges were also larger and faster growing at depth than in shallow-water conspecific populations. This unique biodiversity represents an important biotechnological resource as well; two thirds of the sponges exhibit promising biomedical activity compared to less than one third of the shallow reef sponge species. In addition, 5 of 7 species that co-occur at shallow and deep sites exhibited greater bioactivity due to quantitative and qualitative differences in the natural products produced in each depth range.

Mechanism of abnormally slow crystal growth of CuZr alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, X. Q.; Lü, Y. J., E-mail: yongjunlv@bit.edu.cn; State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027

2015-10-28

Crystal growth of the glass-forming CuZr alloy is shown to be abnormally slow, which suggests a new method to identify the good glass-forming alloys. The crystal growth of elemental Cu, Pd and binary NiAl, CuZr alloys is systematically studied with the aid of molecular dynamics simulations. The temperature dependence of the growth velocity indicates the different growth mechanisms between the elemental and the alloy systems. The high-speed growth featuring the elemental metals is dominated by the non-activated collision between liquid-like atoms and interface, and the low-speed growth for NiAl and CuZr is determined by the diffusion across the interface. Wemore » find that, in contrast to Cu, Pd, and NiAl, a strong stress layering arisen from the density and the local order layering forms in front of the liquid-crystal interface of CuZr alloy, which causes a slow diffusion zone. The formation of the slow diffusion zone suppresses the interface moving, resulting in much small growth velocity of CuZr alloy. We provide a direct evidence of this explanation by applying the compressive stress normal to the interface. The compression is shown to boost the stress layering in CuZr significantly, correspondingly enhancing the slow diffusion zone, and eventually slowing down the crystal growth of CuZr alloy immediately. In contrast, the growth of Cu, Pd, and NiAl is increased by the compression because the low diffusion zones in them are never well developed.« less

Seismo-ionospheric anomalies in ionospheric TEC and plasma density before the 17 July 2006 M7.7 south of Java earthquake

NASA Astrophysics Data System (ADS)

Tao, Dan; Cao, Jinbin; Battiston, Roberto; Li, Liuyuan; Ma, Yuduan; Liu, Wenlong; Zhima, Zeren; Wang, Lanwei; Wray Dunlop, Malcolm

2017-04-01

In this paper, we report significant evidence for preseismic ionospheric anomalies in total electron content (TEC) of the global ionosphere map (GIM) and plasma density appearing on day 2 before the 17 July 2006 M7.7 south of Java earthquake. After distinguishing other anomalies related to the geomagnetic activities, we found a temporal precursor around the epicenter on day 2 before the earthquake (15 July 2006), which agrees well with the spatial variations in latitude-longitude-time (LLT) maps. Meanwhile, the sequences of latitude-time-TEC (LTT) plots reveal that the TECs on epicenter side anomalously decrease and lead to an anomalous asymmetric structure with respect to the magnetic equator in the daytime from day 2 before the earthquake. This anomalous asymmetric structure disappears after the earthquake. To further confirm these anomalies, we studied the plasma data from DEMETER satellite in the earthquake preparation zone (2046.4 km in radius) during the period from day 45 before to day 10 after the earthquake, and also found that the densities of both electron and total ion in the daytime significantly increase on day 2 before the earthquake. Very interestingly, O+ density increases significantly and H+ density decreases, while He+ remains relatively stable. These results indicate that there exists a distinct preseismic signal (preseismic ionospheric anomaly) over the epicenter.

Neoarchean ductile deformation of the Northeastern North China Craton: The Shuangshanzi ductile shear zone in Qinglong, eastern Hebei, North China

NASA Astrophysics Data System (ADS)

Liu, Boran; Neubauer, Franz; Liu, Junlai; Jin, Wei; Li, Weimin; Liang, Chenyue

2017-05-01

Archean granitic gneiss domes and greenstone belts are well-preserved in eastern North China Craton (NCC), one of the oldest Archean terrains in the world. The Shuangshanzi ductile shear zone in Qinglong, eastern Hebei Province is located between an Archean granitic gneiss dome and a greenstone belt within an uplift in eastern NCC. Supracrustal rocks from the Neoarchean Shuangshanzi and Zhuzhangzi Groups, and some Archean granitic gneisses were involved in the shearing along the eastern margin. In the southern part, the narrow NE-trending shear zone dips NW with dip angles of 40-60° and, in the northern part, the shear zone dips NWN with dip angles of 70-85°. Microstructural and EBSD fabric analyses suggest that the shear zone was developed at upper greenschist facies to lower amphibolite facies conditions with deformation temperatures of 400-550 °C. LA-ICP-MS zircon U-Pb dating of mylonitized granitic rocks and undeformed quartz diorite cutting the shear zone suggest that the Shuangshanzi ductile shear zone was formed between 2550 Ma and 2452 Ma. Detailed kinematic studies of the shear zone show a clear sinistral shear sense with a slightly oblique-slip component in the northern part and a sinistral transtensional slip component in the southern part. It is therefore suggested that the shear zone was formed during the Anziling doming with respect to the down-slipping Neoarchean Shuangshanzi and Zhuzhangzi Groups. The difference in kinematics along the southern and the northern sections is interpreted to be caused by the doming with an uneven clockwise spiral rotation. The BIF-rich supracrustal rocks have higher density than their neighboring granitic gneisses, and therefore can easily sink to form synclines by sagduction processes. The sagduction is mainly triggered by gravitational inversion of high density supracrustal rocks with respect to relatively light granitic gneisses within the dome. As a result, the gneisses synchronously moved upward. A shear zone was thus developed in accommodation of the upward and downward movements. It is possible that such a tectonic model also applies to many Archean granite-greenstone terrains.

47 CFR 69.123 - Density pricing zones for special access and switched transport.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., calculated pursuant to the methodology set forth in § 69.725. (2) Such a system of pricing zones shall be....3(e)(7), in study areas in which a telephone company offers a cross-connect, as described in § 69... one of the locations between which the service is offered. (d) Notwithstanding § 69.3(e)(7), in study...

47 CFR 69.123 - Density pricing zones for special access and switched transport.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., calculated pursuant to the methodology set forth in § 69.725. (2) Such a system of pricing zones shall be....3(e)(7), in study areas in which a telephone company offers a cross-connect, as described in § 69... one of the locations between which the service is offered. (d) Notwithstanding § 69.3(e)(7), in study...

47 CFR 69.123 - Density pricing zones for special access and switched transport.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., calculated pursuant to the methodology set forth in § 69.725. (2) Such a system of pricing zones shall be....3(e)(7), in study areas in which a telephone company offers a cross-connect, as described in § 69... one of the locations between which the service is offered. (d) Notwithstanding § 69.3(e)(7), in study...

Snow duration effects on density of the alpine endemic plant Packera franciscana

Treesearch

James F. Fowler; Steven Overby

2016-01-01

Packera franciscana (Greene) W.A. Weber and Á. Löve (Asteraceae) (San Francisco Peaks ragwort) is an alpine-zone endemic of the San Francisco Peaks in northern Arizona. Previous studies have shown that P. franciscana is patchily distributed in alpine-zone talus habitats. The purpose of this study was to describe the relationship between snow duration and P. franciscana...

Ab-Initio Molecular Dynamics Simulations of Molten Ni-Based Superalloys (Preprint)

DTIC Science & Technology

2011-10-01

in liquid–metal density with composition and temperature across the solidification zone. Here, fundamental properties of molten Ni -based alloys ...temperature across the solidification zone. Here, fundamental properties of molten Ni -based alloys , required for modeling these instabilities, are...temperature is assessed in model Ni -Al-W and RENE-N4 alloys . Calculations are performed using a recently implemented constant pressure methodology (NPT) which

Characteristics of spacecraft charging in low Earth orbit

NASA Astrophysics Data System (ADS)

Anderson, Phillip C.

2012-07-01

It has been found that the DMSP spacecraft at 840 km can charge to very large negative voltages (up to -2000 V) when encountering intense precipitating electron events (auroral arcs). We present an 11-year study of over 1600 charging events, defined as when the spacecraft charged to levels exceeding 100 V negative during an auroral crossing. The occurrence frequency of events was highly correlated with the 11-year solar cycle with the largest number of events occurring during solar minimum. This was due to the requirement that the background thermal plasma density be low, at most 104 cm-3. During solar maximum, the plasma density is typically well above that level due to the solar EUV ionizing radiation, and although the occurrence frequency of auroral arcs is considerably greater than at solar minimum, the occurrence of high-level charging is minimal. As a result of this study, we produced a model spectrum for precipitating electrons that can be used as a specification for the low-altitude auroral charging environment. There are implications from this study on a number of LEO satellite programs, including the International Space Station, which does enter the auroral zone, particularly during geomagnetic activity when the auroral boundary can penetrate to very low latitudes. The plasma density in the ISS orbit is usually well above the minimum required density for charging. However, in the wake of the ISS, the plasma density can be 2 orders of magnitude or more lower than the background density and thus conditions are ripe for charging.

Health workforce deployment, attrition and density in East wollega zone, Western ethiopia.

PubMed

Hailemichael, Yohannes; Jira, Challi; Girma, Belayneh; Tushune, Kora

2010-03-01

In East Wollega Zone, despite the success in creating considerable number of health facilities, short-age of health personnel, geographical imbalance and increasing attrition is found to be a persistent barrier to the effectiveness of the health system. However, available data is not rich enough to provide reliable information as to what extent these problems exist in the Zone. Hence, this study was conducted to assess health workforce density, deployment and attrition in East Wollega Zone. A six years retrospective record review from 2000-2005 was conducted between February 1, and March 30, 2006 in eleven randomly selected districts of East Wollega Zone. Data obtained from records and interviews made with selected resource persons were organized by triangulating quantitatively and qualitatively. Quantitative data was analyzed using SPSS 12.01 for windows and thematic frame work analysis was used for qualitative data. Health workforce deployment rate for the years 2000-2005 ranged from 8.2% to 15.4 %. In contrast, attrition rate for the same period ranged from 2.9 % to 8.5 %. Attrition rate for the time after decentralization (2003-2005) was nearly two times greater than before decentralization (OR, 2.04, CI, 1.51, 2.85, P=0.00). Moreover, attrition rate was nearly three times greater for a high level professional when compared to the lower level (OR, 3.15, CI , 2.63, 4.37, P=0.00). Attrition rate for males was two times higher as compared to females (OR, 2.07, CI, 1.67, 3.74, P=0.00). About (26.3%) of all health workers and (36.7%) of nurses and midwives were deployed to the capital town of the zone. Factors identified as most likely cause for the lower deployment and higher attritions were budget related constraints, lack of continuing education opportunity and poor career development. The number of health personnel in East Wollega was low both by international standards and relative to the national density. Moreover, attrition was higher for the time after decentralization process. Hence, measures that seek to increase the size of the health workforce through increased recruitment, higher retention of existing staff and better geographical balance have to be urgently explored.

Environment of ore deposition in the creede mining district, San Juan Mountains, Colorado: Part V. Epithermal mineralization from fluid mixing in the OH vein

USGS Publications Warehouse

Hayba, D.O.

1997-01-01

Detailed fluid inclusion studies on coarse-grained sphalerite from the OH vein, Creede, Colorado, have shown that the abrupt color changes between growth zones correspond to abrupt changes in the nature of the ore fluids. Within each growth zone, however, the composition of the fluids remained constant. The base of a distinctive orange-brown growth zone marks a sharp increase in both temperature and salinity relative to the preceding yellow-white zone. The orange-brown growth zone can be correlated along much of the vein and is believed to represent a time-stratigraphic interval. Along the vein, temperatures and salinities of fluid inclusions within this interval show a systematic decrease from about 285??C and 11.5 wt percent NaCl equiv near the base of the vein to about 250??C and 8 wt percent NaCl equiv, respectively, near the top of the vein. The iron concentration of this sphalerite growth zone shows a similar pattern, decreasing from about 2.8 to 1.2 mole percent FeS. When plotted on an enthalpy-salinity diagram, the fluid inclusion data define a spatial trend indicating the progressive mixing of deeply circulating hydrothermal brines with overlying, dilute ground waters. The hydrothermal brines entered the OH vein from below at a temperature, salinity, and density of approximately 285??C, 11.5 wt percent NaCl equiv, and 860 kg/m3, respectively, whereas the overlying ground waters appear to have been preheated to roughly 150??C and had an assumed salinity of 0 wt percent and a density of 920 kg/m3. The greater density of the heated ground water promoted mixing with the hydrothermal brine within the open fractures, causing sphalerite deposition. Although there were also episodes of boiling during vein mineralization, boiling appears unimportant for this sphalerite. Isotopic evidence and geochemical modeling studies also indicate that mixing was the depositional mechanism for sphalerite. An important aspect of the mixing hydrology of the Creede system involves an aquitard overlying the OH vein. This low permeability zone restricted the flow of ground water into the vein from above and forced the upwelling hydrothermal fluids to flow laterally along the vein. The mixing environment thus occurred along the interface between a deeply circulating hydrothermal convection cell and a topographically driven shallow ground-water system.

Clarinet (CLA-1), a novel active zone protein required for synaptic vesicle clustering and release

PubMed Central

Nelson, Jessica; Richmond, Janet E; Colón-Ramos, Daniel A; Shen, Kang

2017-01-01

Active zone proteins cluster synaptic vesicles at presynaptic terminals and coordinate their release. In forward genetic screens, we isolated a novel Caenorhabditis elegans active zone gene, clarinet (cla-1). cla-1 mutants exhibit defects in synaptic vesicle clustering, active zone structure and synapse number. As a result, they have reduced spontaneous vesicle release and increased synaptic depression. cla-1 mutants show defects in vesicle distribution near the presynaptic dense projection, with fewer undocked vesicles contacting the dense projection and more docked vesicles at the plasma membrane. cla-1 encodes three isoforms containing common C-terminal PDZ and C2 domains with homology to vertebrate active zone proteins Piccolo and RIM. The C-termini of all isoforms localize to the active zone. Specific loss of the ~9000 amino acid long isoform results in vesicle clustering defects and increased synaptic depression. Our data indicate that specific isoforms of clarinet serve distinct functions, regulating synapse development, vesicle clustering and release. PMID:29160205

Significant inconsistency of vegetation carbon density in CMIP5 Earth system models against observational data: Vegetation Carbon Density in ESMs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Xia; Hoffman, Forrest M.; Iversen, Colleen M.

Earth system models (ESMs) have been widely used for projecting global vegetation carbon dynamics, yet how well ESMs performed for simulating vegetation carbon density remains untested. Here we have compiled observational data of vegetation carbon density from literature and existing data sets to evaluate nine ESMs at site, biome, latitude, and global scales. Three variables—root (including fine and coarse roots), total vegetation carbon density, and the root:total vegetation carbon ratios (R/T ratios), were chosen for ESM evaluation. ESM models performed well in simulating the spatial distribution of carbon densities in root (r = 0.71) and total vegetation (r = 0.62).more » However, ESM models had significant biases in simulating absolute carbon densities in root and total vegetation biomass across the majority of land ecosystems, especially in tropical and arctic ecosystems. Particularly, ESMs significantly overestimated carbon density in root (183%) and total vegetation biomass (167%) in climate zones of 10°S–10°N. Substantial discrepancies between modeled and observed R/T ratios were found: the R/T ratios from ESMs were relatively constant, approximately 0.2 across all ecosystems, along latitudinal gradients, and in tropic, temperate, and arctic climatic zones, which was significantly different from the observed large variations in the R/T ratios (0.1–0.8). There were substantial inconsistencies between ESM-derived carbon density in root and total vegetation biomass and the R/T ratio at multiple scales, indicating urgent needs for model improvements on carbon allocation algorithms and more intensive field campaigns targeting carbon density in all key vegetation components.« less

Significant inconsistency of vegetation carbon density in CMIP5 Earth system models against observational data: Vegetation Carbon Density in ESMs

DOE PAGES

Song, Xia; Hoffman, Forrest M.; Iversen, Colleen M.; ...

2017-09-09

Earth system models (ESMs) have been widely used for projecting global vegetation carbon dynamics, yet how well ESMs performed for simulating vegetation carbon density remains untested. Here we have compiled observational data of vegetation carbon density from literature and existing data sets to evaluate nine ESMs at site, biome, latitude, and global scales. Three variables—root (including fine and coarse roots), total vegetation carbon density, and the root:total vegetation carbon ratios (R/T ratios), were chosen for ESM evaluation. ESM models performed well in simulating the spatial distribution of carbon densities in root (r = 0.71) and total vegetation (r = 0.62).more » However, ESM models had significant biases in simulating absolute carbon densities in root and total vegetation biomass across the majority of land ecosystems, especially in tropical and arctic ecosystems. Particularly, ESMs significantly overestimated carbon density in root (183%) and total vegetation biomass (167%) in climate zones of 10°S–10°N. Substantial discrepancies between modeled and observed R/T ratios were found: the R/T ratios from ESMs were relatively constant, approximately 0.2 across all ecosystems, along latitudinal gradients, and in tropic, temperate, and arctic climatic zones, which was significantly different from the observed large variations in the R/T ratios (0.1–0.8). There were substantial inconsistencies between ESM-derived carbon density in root and total vegetation biomass and the R/T ratio at multiple scales, indicating urgent needs for model improvements on carbon allocation algorithms and more intensive field campaigns targeting carbon density in all key vegetation components.« less

Super-resolution Microscopical Localization of Dopamine Receptors 1 and 2 in Rat Hippocampal Synaptosomes.

PubMed

Miklosi, Andras G; Del Favero, Giorgia; Bulat, Tanja; Höger, Harald; Shigemoto, Ryuichi; Marko, Doris; Lubec, Gert

2018-06-01

Although dopamine receptors D1 and D2 play key roles in hippocampal function, their synaptic localization within the hippocampus has not been fully elucidated. In order to understand precise functions of pre- or postsynaptic dopamine receptors (DRs), the development of protocols to differentiate pre- and postsynaptic DRs is essential. So far, most studies on determination and quantification of DRs did not discriminate between subsynaptic localization. Therefore, the aim of the study was to generate a robust workflow for the localization of DRs. This work provides the basis for future work on hippocampal DRs, in light that DRs may have different functions at pre- or postsynaptic sites. Synaptosomes from rat hippocampi isolated by a sucrose gradient protocol were prepared for super-resolution direct stochastic optical reconstruction microscopy (dSTORM) using Bassoon as a presynaptic zone and Homer1 as postsynaptic density marker. Direct labeling of primary validated antibodies against dopamine receptors D1 (D1R) and D2 (D2R) with Alexa Fluor 594 enabled unequivocal assignment of D1R and D2R to both, pre- and postsynaptic sites. D1R immunoreactivity clusters were observed within the presynaptic active zone as well as at perisynaptic sites at the edge of the presynaptic active zone. The results may be useful for the interpretation of previous studies and the design of future work on DRs in the hippocampus. Moreover, the reduction of the complexity of brain tissue by the use of synaptosomal preparations and dSTORM technology may represent a useful tool for synaptic localization of brain proteins.

ACCRETION DISK DYNAMO AS THE TRIGGER FOR X-RAY BINARY STATE TRANSITIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Begelman, Mitchell C.; Armitage, Philip J.; Reynolds, Christopher S., E-mail: mitch@jila.colorado.edu

2015-08-20

Magnetohydrodynamic accretion disk simulations suggest that much of the energy liberated by the magnetorotational instability (MRI) can be channeled into large-scale toroidal magnetic fields through dynamo action. Under certain conditions, this field can dominate over gas and radiation pressure in providing vertical support against gravity, even close to the midplane. Using a simple model for the creation of this field, its buoyant rise, and its coupling to the gas, we show how disks could be driven into this magnetically dominated state and deduce the resulting vertical pressure and density profiles. Applying an established criterion for MRI to operate in themore » presence of a toroidal field, we show that magnetically supported disks can have two distinct MRI-active regions, separated by a “dead zone” where local MRI is suppressed, but where magnetic energy continues to flow upward from the dynamo region below. We suggest that the relative strengths of the MRI zones, and the local poloidal flux, determine the spectral states of X-ray binaries. Specifically, “intermediate” and “hard” accretion states occur when MRI is triggered in the hot, upper zone of the corona, while disks in “soft” states do not develop the upper MRI zone. We discuss the conditions under which various transitions should take place and speculate on the relationship of dynamo activity to the various types of quasi-periodic oscillations that sometimes appear in the hard spectral components. The model also explains why luminous accretion disks in the “soft” state show no signs of the thermal/viscous instability predicted by standard α-models.« less

System and method for coproduction of activated carbon and steam/electricity

DOEpatents

Srinivasachar, Srivats [Sturbridge, MA; Benson, Steven [Grand Forks, ND; Crocker, Charlene [Newfolden, MN; Mackenzie, Jill [Carmel, IN

2011-07-19

A system and method for producing activated carbon comprising carbonizing a solid carbonaceous material in a carbonization zone of an activated carbon production apparatus (ACPA) to yield a carbonized product and carbonization product gases, the carbonization zone comprising carbonaceous material inlet, char outlet and carbonization gas outlet; activating the carbonized product via activation with steam in an activation zone of the ACPA to yield activated carbon and activation product gases, the activation zone comprising activated carbon outlet, activation gas outlet, and activation steam inlet; and utilizing process gas comprising at least a portion of the carbonization product gases or a combustion product thereof; at least a portion of the activation product gases or a combustion product thereof; or a combination thereof in a solid fuel boiler system that burns a solid fuel boiler feed with air to produce boiler-produced steam and flue gas, the boiler upstream of an air heater within a steam/electricity generation plant, said boiler comprising a combustion zone, a boiler-produced steam outlet and at least one flue gas outlet.

78 FR 60826 - Foreign-Trade Zone 155-Calhoun/Victoria Counties, Texas; Authorization of Production Activity...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-02

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board Foreign-Trade Zone 155--Calhoun/Victoria Counties, Texas; Authorization of Production Activity; Caterpillar, Inc. (Excavator and Frame Assembly Production); Victoria, Texas On May 29, 2013, The Calhoun-Victoria Foreign Trade Zone, Inc., grantee of FTZ 155...

78 FR 48647 - Foreign-Trade Zone 225-Springfield, Missouri; Authorization of Production Activity; General...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-09

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-30-2013] Foreign-Trade Zone 225--Springfield, Missouri; Authorization of Production Activity; General Dynamics Ordnance and Tactical Systems Munitions...-Trade Zones (FTZ) Board on behalf of General Dynamics Ordnance and Tactical Systems Munitions Services...

Deep structure of the Alborz Mountains by joint inversion of P receiver functions and dispersion curves

NASA Astrophysics Data System (ADS)

Rastgoo, Mehdi; Rahimi, Habib; Motaghi, Khalil; Shabanian, Esmaeil; Romanelli, Fabio; Panza, Giuliano F.

2018-04-01

The Alborz Mountains represent a tectonically and seismically active convergent boundary in the Arabia - Eurasia collision zone, in western Asia. The orogenic belt has undergone a long-lasted tectono-magmatic history since the Cretaceous. The relationship between shallow and deep structures in this complex tectonic domain is not straightforward. We present a 2D velocity model constructed by the assemblage of 1D shear wave velocity (Vs) models from 26 seismic stations, mainly distributed along the southern flank of the Alborz Mountains. The shear wave velocity structure has been estimated beneath each station using joint inversion of P-waves receiver functions and Rayleigh wave dispersion curves. A substantiation of the Vs inversion results sits on the modeling of Bouguer gravity anomaly data. Our velocity and density models show low velocity/density anomalies in uppermost mantle of western and central Alborz at a depth range of ∼50-100 km. In deeper parts of the uppermost mantle (depth range of 100-150 km), a high velocity/density anomaly is located beneath most of the Mountain range. The spatial pattern of these low and high velocity/density structures in the upper mantle is interpreted as the result of post collisional delamination of lower part of the western and central Alborz lithosphere.

Application of gamma ray spectrometric measurements and VLF-EM data for tracing vein type uranium mineralization

NASA Astrophysics Data System (ADS)

Gaafar, Ibrahim

2015-12-01

This study is an attempt to use the gamma ray spectrometric measurements and VLF-EM data to identify the subsurface structure and map uranium mineralization along El Sela shear zone, South Eastern Desert of Egypt. Many injections more or less mineralized with uranium and associated with alteration processes were recorded in El Sela shear zone. As results from previous works, the emplacement of these injections is structurally controlled and well defined by large shear zones striking in an ENE-WSW direction and crosscut by NW-SE to NNW-SSE fault sets. VLF method has been applied to map the structure and the presence of radioactive minerals that have been delineated by the detection of high uranium mineralization. The electromagnetic survey was carried out to detect the presence of shallow and deep conductive zones that cross the granites along ENE-WSW fracturing directions and to map its spatial distribution. The survey comprised seventy N-S spectrometry and VLF-EM profiles with 20 m separation. The resulted data were displayed as composite maps for K, eU and eTh as well as VLF-Fraser map. Twelve profiles with 100 m separation were selected for detailed description. The VLF-EM data were interpreted qualitatively as well as quantitatively using the Fraser and the Karous-Hjelt filters. Fraser filtered data and relative current density pseudo-sections indicate the presence of shallow and deep conductive zones that cross the granites along ENE-WSW shearing directions. High uranium concentrations found just above the higher apparent current-density zones that coincide with El-Sela shear zone indicate a positive relation between conductivity and uranium minerals occurrence. This enables to infer that the anomalies detected by VLF-EM data are due to the highly conductive shear zone enriched with uranium mineralization extending for more than 80 m.

Freshwater-Brine Mixing Zone Hydrodynamics in Salt Flats (Salar de Atacama)

NASA Astrophysics Data System (ADS)

Marazuela, M. A.; Vázquez-Suñé, E.; Custodio, E.; Palma, T.; García-Gil, A.

2017-12-01

The increase in the demand of strategic minerals for the development of medicines and batteries require detailed knowledge of the salt flats freshwater-brine interface to make its exploitation efficient. The interface zone is the result of a physical balance between the recharged and evaporated water. The sharp interface approach assumes the immiscibility of the fluids and thus neglects the mixing between them. As a consequence, for miscible fluids it is more accurate and often needed to use the mixing zone concept, which results from the dynamic equilibrium of flowing freshwater and brine. In this study, we consider two and three-dimensional scale approaches for the management of the mixing zone. The two-dimensional approach is used to understand the dynamics and the characteristics of the salt flat mixing zone, especially in the Salar de Atacama (Atacama salt flat) case. By making use of this model we analyze and quantify the effects of the aquitards on the mixing zone geometry. However, the understanding of the complex physical processes occurring in the salt flats and the management of these environments requires the adoption of three-dimensional regional scale numerical models. The models that take into account the effects of variable density represent the best management tool, but they require large computational resources, especially in the three-dimensional case. In order to avoid these computational limitations in the modeling of salt flats and their valuable ecosystems, we propose a three-step methodology, consisting of: (1) collection, validation and interpretation of the hydrogeochemical data, (2) identification and three-dimensional mapping of the mixing zone on the land surface and in depth, and (3) application of a water head correction to the freshwater and mixed water heads in order to compensate the density variations and to transform them to brine water heads. Finally, an evaluation of the sensibility of the mixing zone to anthropogenic and climate changes is included.

Fault and fracture patterns in low porosity chalk and their potential influence on sub-surface fluid flow-A case study from Flamborough Head, UK

NASA Astrophysics Data System (ADS)

Sagi, D. A.; De Paola, N.; McCaffrey, K. J. W.; Holdsworth, R. E.

2016-10-01

To better understand fault zone architecture and fluid flow in mesoscale fault zones, we studied normal faults in chalks with displacements up to 20 m, at two representative localities in Flamborough Head (UK). At the first locality, chalk contains cm-thick, interlayered marl horizons, whereas at the second locality marl horizons were largely absent. Cm-scale displacement faults at both localities display ramp-flat geometries. Mesoscale fault patterns in the marl-free chalk, including a larger displacement fault (20 m) containing multiple fault strands, show widespread evidence of hydraulically-brecciated rocks, whereas clays smears along fault planes, and injected into open fractures, and a simpler fault zone architecture is observed where marl horizons are present. Hydraulic brecciation and veins observed in the marl-free chalk units suggest that mesoscale fault patterns acted as localized fault conduit allowing for widespread fluid flow. On the other hand, mesoscale fault patterns developed in highly fractured chalk, which contains interlayered marl horizons can act as localized barriers to fluid flow, due to the sealing effect of clays smears along fault planes and introduced into open fractures in the damage zone. To support our field observations, quantitative analyses carried out on the large faults suggest a simple fault zone in the chalk with marl units with fracture density/connectivity decreasing towards the protolith. Where marls are absent, density is high throughout the fault zone, while connectivity is high only in domains nearest the fault core. We suggest that fluid flow in fractured chalk is especially influenced by the presence of marls. When present, it can smear onto fault planes, forming localised barriers. Fluid flow along relatively large displacement faults is additionally controlled by the complexity of the fault zone, especially the size/geometry of weakly and intensely connected damage zone domains.

Evaluation of Sidestream Darkfield Microscopy for Real-Time Imaging Acellular Dermal Matrix Revascularization.

PubMed

DeGeorge, Brent R; Olenczak, J Bryce; Cottler, Patrick S; Drake, David B; Lin, Kant Y; Morgan, Raymond F; Campbell, Christopher A

2016-06-01

Acellular dermal matrices (ADMs) serve as a regenerative framework for host cell integration and collagen deposition to augment the soft tissue envelope in ADM-assisted breast reconstruction-a process dependent on vascular ingrowth. To date noninvasive intra-operative imaging techniques have been inadequate to evaluate the revascularization of ADM. We investigated the safety, feasibility, and efficacy of sidestream darkfield (SDF) microscopy to assess the status of ADM microvascular architecture in 8 patients at the time of tissue expander to permanent implant exchange during 2-stage ADM-assisted breast reconstruction. The SDF microscopy is a handheld device, which can be used intraoperatively for the real-time assessment of ADM blood flow, vessel density, vessel size, and branching pattern. The SDF microscopy was used to assess the microvascular architecture in the center and border zone of the ADM and to compare the native, non-ADM-associated capsule in each patient as a within-subject control. No incidences of periprosthetic infection, explantation, or adverse events were reported after SDF image acquisition. Native capsules demonstrate a complex, layered architecture with an average vessel area density of 14.9 mm/mm and total vessel length density of 12.3 mm/mm. In contrast to native periprosthetic capsules, ADM-associated capsules are not uniformly vascularized structures and demonstrate 2 zones of microvascular architecture. The ADM and native capsule border zone demonstrates palisading peripheral vascular arcades with continuous antegrade flow. The central zone of the ADM demonstrates punctate perforating vascular plexi with intermittent, sluggish flow, and intervening 2- to 3-cm watershed zones. Sidestream darkfield microscopy allows for real-time intraoperative assessment of ADM revascularization and serves as a potential methodology to compare revascularization parameters among commercially available ADMs. Thr SDF microscopy demonstrates that the periprosthetic capsule in ADM-assisted implant-based breast reconstruction is not a uniformly vascularized structure.

Patterns of livestock depredation by tiger (Panthera tigris) and leopard (Panthera pardus) in and around Corbett Tiger Reserve, Uttarakhand, India.

PubMed

Bargali, Harendra Singh; Ahmed, Tanveer

2018-01-01

India with estimated more than 2000 tigers (across 18 states) accounts for more than half of the remaining tigers across its range countries. Long-term conservation requires measures to protect the large carnivores and its prey base beyond the Protect Areas. The Corbett Tiger Reserve (CTR) and adjoining forest divisions with high density of tigers play a crucial role in conservation of tiger in Uttarakhand state as well as the Terai-Arc Landscape. However, CTR is surrounded with multiple-use forest (forest divisions), agriculture land, human habitation, townships and developmental projects. The movement of large carnivores and other wildlife through such habitats adds to the chances of human-wildlife conflict. The aim of the current study was to understand the patterns of livestock depredation by tigers and leopards in and around CTR. We examined a total of 8365 incidents of livestock depredation between 2006 and 2015 with tigers killing more livestock in a year (573.3±41.2) than leopards (263.2±9.9). Geographically, in north zone of CTR leopards were the major livestock predator (166.6±11), whereas tigers (547.7±40.1) in south zone. Examination of livestock kills indicated cows (75%) as the main victim, followed by buffaloes and other species. Analysis revealed that the livestock depredation by tigers varied significantly among seasons in south zone but not in north zone. However, such an explicit seasonal variation was not observed for leopards in north and south zone of CTR. Hotspots of livestock predation were identified around CTR. Addressing a conflict situation in a time-bound manner, timely disbursement of ex-gratia payment, involving locals at various tourism related activities and consistent rapport building initiatives are required to mitigate the human-wildlife conflict.

New Hydrologic Insights to Advance Geophysical Investigation of the Unsaturated Zone

NASA Astrophysics Data System (ADS)

Nimmo, J. R.; Perkins, K. S.

2015-12-01

Advances in hydrology require information from the unsaturated zone, especially for problems related to groundwater contamination, water-supply sustainability, and ecohydrology. Unsaturated-zone processes are notoriously difficult to quantify; soils and rocks are visually opaque, spatially variable in the extreme, and easily disturbed by instrument installation. Thus there is great value in noninvasive techniques that produce water-related data of high density in space and time. Methods based on resistivity and electromagnetic waves have already produced significant new understanding of percolation processes, root-zone water retention, influences of evapotranspiration on soil-water, and effects of preferential flow. Further developments are underway for such purposes as noninvasive application to greater depths, increased resolution, adaptation for lab-scale experiments, and calibration in heterogeneous media. Beyond these, however, there is need for a stronger marriage of hydrologic and geophysical knowledge and perspective. Possible means to greater and faster progress include: Apply the latest hydrologic understanding, both pore-scale and macroscopic, to the detection of preferential flow paths and their degree of activation. In the continuing advancement of hardware and techniques, draw creatively from developments in such fields as high-energy physics, medical imaging, astrogeology, high-tech semiconductors, and bioinstrumentation. Sidestep the imaging process where possible to measure essential properties and fluxes more directly. Pose questions that have a strong end-use character, like "how does storm intensity relate to aquifer recharge rate" rather than "what is the shape of the wetting front". The greatest advances in geophysical investigation of the unsaturated zone will come from methods informed by the latest understanding of unsaturated systems and processes, and aimed as directly as possible at the answers to important hydrologic questions.

Vertical surface displacements along a part of the Newport-Inglewood zone of folds and faults, Los Angeles and Orange counties, California

USGS Publications Warehouse

Castle, Robert O.; Buchanan-Banks, Jane M.

1989-01-01

During the past half century, the onshore section of the Newport- Inglewood zone of folds and faults between the Dominguez oil field and Corona del Mar (fig. 1) has been repeatedly leveled to geodetic standards. These essentially fortuitous surveys are unrelated to either the tectonic framework or the urbanization of the Los Angeles basin, but were established instead because the Newport-Inglewood zone southward from the Long Beach area is roughly coincident with the coastline--and, hence, is roughly coincident with a naturally defined leveling route. Although these have been several relevelings athwart this zone north of the long Beach area, notably in the Baldwin Hills area (Castle and Yerkes, 1976), about 25 km to the northwest, the survey density, in both space and time, diminishes markedly northward. Thus, the results of the indicated relevelings along the Los Angeles-Orange County coast have permitted the relatively detailed appraisal of historic vertical surface movements described in this report. The Newport-Inglewood zone of folds and faults forms the surface expression of a major crustal boundary separating the Peninsular Ranges province on the east from the Continental Borderland province on the west (Castle and others, 1984, p. 8-9, pl. 1). Transcurrent fault movement along this boundary has produced not only continuing seismic activity, for which this zone is justly famous, but also folds and other structural features within the sedimentary veneer that have entrapped the petroleum deposits for which the Newport-Inglewood zone is even more famous. Although the northeast boundary of the exceptionally prolific Wilmington oil field is roughly coincident with the southeast edge of the Newport-Inglewood zone, we have deliberately excluded this area from consideration--in other than a peripheral way--simply because compaction-induced subsidence centering on the Wilmington field is viewed as a singularly spectacular example of this phenomenon and, hence, has been the subject of a series of detailed investigation (Harris and Harlow, 1947; Gilluly and Grant, 1949; Hudson, 1956; Miller, 1966; Poland and Davis, 1969; Allen and Mayuga, 1970; Castle and Yerkes, 1976).

Aerated drilling cutting transport analysis in geothermal well

NASA Astrophysics Data System (ADS)

Wakhyudin, Aris; Setiawan, Deni; Dwi Marjuan, Oscar

2017-12-01

Aeratad drilling widely used for geothermal drilling especially when drilled into predicted production zone. Aerated drilling give better performance on preventing lost circulation problem, improving rate of penetration, and avoiding drilling fluid invasion to productive zone. While well is drilled, cutting is produced and should be carried to surface by drilling fluid. Hole problem, especially pipe sticking will occur while the cutting is not lifted properly to surface. The problem will effect on drilling schedule; non-productive time finally result more cost to be spent. Geothermal formation has different characteristic comparing oil and gas formation. Geothermal mainly has igneous rock while oil and gas mostly sedimentary rock. In same depth, formation pressure in geothermal well commonly lower than oil and gas well while formation temperature geothermal well is higher. While aerated drilling is applied in geothermal well, Igneous rock density has higher density than sedimentary rock and aerated drilling fluid is lighter than water based mud hence minimum velocity requirement to transport cutting is larger than in oil/gas well drilling. Temperature and pressure also has impact on drilling fluid (aerated) density. High temperature in geothermal well decrease drilling fluid density hence the effect of pressure and temperature also considered. In this paper, Aerated drilling cutting transport performance on geothermal well will be analysed due to different rock and drilling fluid density. Additionally, temperature and pressure effect on drilling fluid density also presented to merge.

Transmission of a detonation across a density interface

NASA Astrophysics Data System (ADS)

Tang Yuk, K. C.; Mi, X. C.; Lee, J. H. S.; Ng, H. D.

2018-05-01

The present study investigates the transmission of a detonation wave across a density interface. The problem is first studied theoretically considering an incident Chapman-Jouguet (CJ) detonation wave, neglecting its detailed reaction-zone structure. It is found that, if there is a density decrease at the interface, a transmitted strong detonation wave and a reflected expansion wave would be formed; if there is a density increase, one would obtain a transmitted CJ detonation wave followed by an expansion wave and a reflected shock wave. Numerical simulations are then performed considering that the incident detonation has the Zel'dovich-von Neumann-Döring reaction-zone structure. The transient process that occurs subsequently to the detonation-interface interaction has been captured by the simulations. The effects of the magnitude of density change across the interface and different reaction kinetics (i.e., single-step Arrhenius kinetics vs. two-step induction-reaction kinetics) on the dynamics of the transmission process are explored. After the transient relaxation process, the transmitted wave reaches the final state in the new medium. For the cases with two-step induction-reaction kinetics, the transmitted wave fails to evolve to a steady detonation wave if the magnitude of density increase is greater than a critical value. For the cases wherein the transmitted wave can evolve to a steady detonation, the numerical results for both reaction models give final propagation states that agree with the theoretical solutions.

Method of deep drilling

DOEpatents

Colgate, Stirling A.

1984-01-01

Deep drilling is facilitated by the following steps practiced separately or in any combination: (1) Periodically and sequentially fracturing zones adjacent the bottom of the bore hole with a thixotropic fastsetting fluid that is accepted into the fracture to overstress the zone, such fracturing and injection being periodic as a function of the progression of the drill. (2) Casing the bore hole with ductile, pre-annealed casing sections, each of which is run down through the previously set casing and swaged in situ to a diameter large enough to allow the next section to run down through it. (3) Drilling the bore hole using a drill string of a low density alloy and a high density drilling mud so that the drill string is partially floated.

Sound velocity and density of magnesiowüstites: Implications for ultralow-velocity zone topography: Sound velocities of Iron-rich Oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wicks, June; Jackson, Jennifer M.; Sturhahn, Wolfgang

We explore the effect of Mg/Fe substitution on the sound velocities of iron-rich (Mg 1 - xFe x)O, where x = 0.84, 0.94, and 1.0. Sound velocities were determined using nuclear resonance inelastic X-ray scattering as a function of pressure, approaching those of the lowermost mantle. The systematics of cation substitution in the Fe-rich limit has the potential to play an important role in the interpretation of seismic observations of the core-mantle boundary. By determining a relationship between sound velocity, density, and composition of (Mg,Fe)O, this study explores the potential constraints on ultralow-velocity zones at the core-mantle boundary.

MAGNETIC END CLOSURES FOR PLASMA CONFINING AND HEATING DEVICES

DOEpatents

Post, R.F.

1963-08-20

More effective magnetic closure field regions for various open-ended containment magnetic fields used in fusion reactor devices are provided by several spaced, coaxially-aligned solenoids utilized to produce a series of nodal field regions of uniform or, preferably, of incrementally increasing intensity separated by lower intensity regions outwardly from the ends of said containment zone. Plasma sources may also be provided to inject plasma into said lower intensity areas to increase plasma density therein. Plasma may then be transported, by plasma diffusion mechanisms provided by the nodal fields, into the containment field. With correlated plasma densities and nodal field spacings approximating the mean free partl cle collision path length in the zones between the nodal fields, optimum closure effectiveness is obtained. (AEC)

Vessel density, retinal thickness, and choriocapillaris vascular flow in myopic eyes on OCT angiography.

PubMed

Milani, Paolo; Montesano, Giovanni; Rossetti, Luca; Bergamini, Fulvio; Pece, Alfredo

2018-06-06

To investigate foveal avascular zone area, macular vascular density, choroidal thickness, and outer retina and choriocapillaris flow in myopic eyes by OCT angiography. Automated macular maps and flow calculations were retrospectively evaluated in 42 myopic and in 40 control eyes. Myopic eyes presented lower whole superficial vessel density (46.4 ± 4.9 vs. 51.6 ± 3.6%, P < 0.0001) and higher flow area in the outer retina (1.3 ± 0.2 vs. 1.1 ± 0.3 mm 2 , P = 0.0012). Between the myopic and non-myopic eyes, no significant differences could be detected in the choriocapillaris perfusion area (1.9 ± 0.07 vs. 1.9 ± 0.05 mm 2 , respectively; P = 0.55) and in the foveal avascular zone area (0.23 ± 0.1 vs. 0.26 ± 0.1 mm 2 , respectively; P = 0.12). The spherical correction positively correlated with superficial vessel density and negatively correlated with outer retina perfusion (P ≤ 0.0021). The superficial vessel density and the local retinal thickness positively correlated at all macular locations (P < 0.005), especially in the foveal region (P < 0.0001). Eyes with high myopia present reduced superficial vascular density and increased outer retina flow. Superficial vascular density and retinal thickness appear to be significantly correlated.

Inbreeding and immigration in urban and rural zones of Chile, with an endogamy index.

PubMed

Lazo, B; Campusano, C; Figueroa, H; Pinto-Cisternas, J; Zambra, E

1978-01-01

In order to establish relationships among immigration, inbreeding, and age at marriage in urban and rural zones in Chile, and to formulate an endogamy index, ecclesiastical and civil data on consanguinity from 1865-1914 were analyzed, and a random mating deviation index was developed, with resulting values indicating deviation toward endogamy in both zones. Data grouped by zones and decades include means of population and density, nuptiality, consanguineous marriages (number, types, frequencies, and inbreeding coefficients), and frequencies of immigrants among consanguineous and nonconsanguineous couples. All of these values differ markedly between zones, with values in the rural zone double those in the urban zone. In the 2 zones, there are no clear differences in age at marriage between consanguineous and nonconsanguineous couples, and this is an important finding. From the point of view of fertility, one can expect a similar length period of fertility for both groups of couples. In this case, lower fertility might be expected in consanguineous marriages, only because of a higher probability of homozygosis of deleterious genes.

Intraplate mafic magmatism: New insights from Africa and N. America

NASA Astrophysics Data System (ADS)

Ebinger, C. J.; van der Lee, S.; Tepp, G.; Pierre, S.

2017-12-01

Plate tectonic concepts consider that continental interiors are stable, with magmatism and strain localized to plate boundaries. We re-evaluate the role of pre-existing and evolving lithospheric heterogeneities in light of perspectives afforded by surface to mantle results from active and ancient rift zones in Africa and N. America. Our process-oriented approach addresses the localization of strain and magmatism and stability of continental plate interiors. In both Africa and N. America, geophysical imaging and xenolith studies reveal that thick, buoyant, and chemically distinct Archaean cratons with deep roots may deflect mantle flow, and localize magmatism and strain over many tectonic cycles. Studies of the Colorado Plateau and East African rift reveal widespread mantle metasomatism, and high levels of magma degassing along faults and at active volcanoes. The volcanoes and magmatic systems show a strong dependence on pre-existing heterogeneities in plate structure. Syntheses of the EarthScope program ishow that lateral density contrasts and migration of volatiles that accumulated during subduction can refertilize mantle lithosphere, and enable volatile-rich magmatism beneath relatively thick continental lithosphere. For example, the passive margin of eastern N. America shows uplift and magmatism long after the onset of seafloor spreading, demonstrating the dynamic nature of coupling between the lithosphere, asthenosphere, and deeper mantle. As demonstrated by the East African Rift, the Mid-Continent Rift, and other active and ancient rift zones, the interiors of continents, including thick, cold Archaean cratons are not immune to mafic magmatism and tectonism. Recent studies in N. America and Africa reveal ca. 1000 km-wide zones of dynamic uplift, low upper mantle velocities, and broadly distributed strain. The distribution of magmatism and volatile release, in combination with geophysical signals, indicates a potentially convective origin for widespread intraplate earthquakes and magmatism, across areas broader than the surface expression of rifting. Integrated geophysical, geological and geochemical studies reveal large volumes and rates of magmatism at rift zones, provoking re-evaluation of crustal accretion and carbon and water cycles, as well as earthquake and volcanic hazards.

Pedestrian-oriented zoning is associated with reduced income and poverty disparities in adult active travel to work, United States.

PubMed

Chriqui, Jamie F; Leider, Julien; Thrun, Emily; Nicholson, Lisa M; Slater, Sandy J

2017-02-01

Active travel to work can provide additional minutes of daily physical activity. While the literature points to the relationship between zoning, equity and socioeconomic status, and physical activity, no study has quantitatively explored these connections. This study examined whether zoning may help to moderate any income and poverty inequities in active travel and taking public transit to work. Research was conducted between May 2012 and June 2015. Zoning data were compiled for 3914 jurisdictions covering 45.45% of the U.S. population located in 471 of the most populous U.S. counties and 2 consolidated cities located in 48 states and the District of Columbia. (Sensitivity analyses also captured unincorporated areas which, with the municipalities, collectively covered ~72% of the U.S. ) Zoning codes were obtained and evaluated to assess the pedestrian-orientation of the zoning codes. Public transit use, active travel to work, median household income, and poverty data were obtained for all study jurisdictions from the 2010-2014 American Community Survey estimates. Associations were examined through multivariate regression models, controlling for community sociodemographics, clustered on county, with robust standard errors. We found that certain pedestrian-oriented zoning provisions (e.g., crosswalks, bike-pedestrian connectivity, street connectivity, bike lanes, bike parking, and more zoning provisions) were associated with reduced income and/or poverty disparities in rates of public transit use and active travel to work. Findings from this study can help to inform cross-sectoral collaborations between the public health, planning, and transportation fields regarding zoning for pedestrian-orientation and active travel. Copyright © 2016 Elsevier Inc. All rights reserved.

Impact of kinetic mass transfer on free convection in a porous medium

NASA Astrophysics Data System (ADS)

Lu, Chunhui; Shi, Liangsheng; Chen, Yiming; Xie, Yueqing; Simmons, Craig T.

2016-05-01

We investigate kinetic mass transfer effects on unstable density-driven flow and transport processes by numerical simulations of a modified Elder problem. The first-order dual-domain mass transfer model coupled with a variable-density-flow model is employed to describe transport behavior in porous media. Results show that in comparison to the no-mass-transfer case, a higher degree of instability and more unstable system is developed in the mass transfer case due to the reduced effective porosity and correspondingly a larger Rayleigh number (assuming permeability is independent on the mobile porosity). Given a constant total porosity, the magnitude of capacity ratio (i.e., immobile porosity/mobile porosity) controls the macroscopic plume profile in the mobile domain, while the magnitude of mass transfer timescale (i.e., the reciprocal of the mass transfer rate coefficient) dominates its evolution rate. The magnitude of capacity ratio plays an important role on the mechanism driving the mass flux into the aquifer system. Specifically, for a small capacity ratio, solute loading is dominated by the density-driven transport, while with increasing capacity ratio local mass transfer dominated solute loading may occur at later times. At significantly large times, however, both mechanisms contribute comparably to solute loading. Sherwood Number could be a nonmonotonic function of mass transfer timescale due to complicated interactions of solute between source zone, mobile zone and immobile zone in the top boundary layer, resulting in accordingly a similar behavior of the total mass. The initial assessment provides important insights into unstable density-driven flow and transport in the presence of kinetic mass transfer.

Regional variations in the density and arrangement of elastic fibres in the anulus fibrosus of the human lumbar disc

PubMed Central

Smith, Lachlan J; Fazzalari, Nicola L

2006-01-01

Elastic fibres are critical components of the extracellular matrix in dynamic biological structures that undergo extension and recoil. Their presence has been demonstrated in the anulus fibrosus of the human lumbar intervertebral disc; however, a detailed regional analysis of their density and arrangement has not been undertaken, limiting our understanding of their structural and functional roles. In this investigation we have quantitatively described regional variations in elastic fibre density in the anulus fibrosus of the human L3–L4 intervertebral disc using histochemistry and light microscopy. Additionally, a multiplanar comparison of patterns of elastic fibre distribution in the intralamellar and interlamellar zones was undertaken. Novel imaging techniques were developed to facilitate the visualization of elastic fibres otherwise masked by dense surrounding matrix. Elastic fibre density was found to be significantly higher in the lamellae of the posterolateral region of the anulus than the anterolateral, and significantly higher in the outer regions than the inner, suggesting that elastic fibre density in each region of the anulus is commensurate with the magnitude of the tensile deformations experienced in bending and torsion. Elastic fibre arrangments in intralamellar and interlamellar zones were shown to be architecturally distinct, suggesting that they perform multiple functional roles within the anulus matrix structural hierarchy. PMID:16928204

In vitro and in vivo MR evaluation of internal gradient to assess trabecular bone density

NASA Astrophysics Data System (ADS)

De Santis, S.; Rebuzzi, M.; Di Pietro, G.; Fasano, F.; Maraviglia, B.; Capuani, S.

2010-10-01

Here we propose a new magnetic resonance (MR) strategy based on the evaluation of internal gradient (Gi) to assess the trabecular bone (TB) density in spongy bone. Spongy bone is a porous system characterized by a solid trabecular network immersed in bone marrow and characterized by a different relative percentage of water and fats. Using a 9.4 T MR micro-imaging system, we first evaluated the relative water and fat Gi as extracted from the Spin-Echo decay function in vitro of femoral head samples from calves. Indeed, the differential effects of fat and water diffusion result in different types of Gi behavior. Using a clinical MR 3T scanner, we then investigated in vivo the calcanei of individuals characterized by different known TB densities. We demonstrate, on these samples, that water is more prevalent in the boundary zone, while fats are rearranged primarily in the central zone of each pore. In vitro experiments showed that water Gi magnitude from the samples was directly proportional to their TB density. Similar behavior was also observed in the clinical measures. Conversely, fat Gi did not provide any information on spongy-bone density. Our results suggest that water Gi may be a reliable marker to assess the status of spongy bone.

Snow Densification and Recent Accumulation Along the iSTAR Traverse, Pine Island Glacier, Antarctica

NASA Astrophysics Data System (ADS)

Morris, E. M.; Mulvaney, R.; Arthern, R. J.; Davies, D.; Gurney, R. J.; Lambert, P.; De Rydt, J.; Smith, A. M.; Tuckwell, R. J.; Winstrup, M.

2017-12-01

Neutron probe measurements of snow density from 22 sites in the Pine Island Glacier basin have been used to determine mean annual accumulation using an automatic annual layer identification routine. A mean density profile which can be used to convert radar two-way travel times to depth has been derived, and the effect of annual fluctuations in density on estimates of the depth of radar reflectors is shown to be insignificant, except very near the surface. Vertical densification rates have been derived from the neutron probe density profiles and from deeper firn core density profiles available at 9 of the sites. These rates are consistent with the rates predicted by the Herron and Langway model for stage 1 densification (by grain-boundary sliding, grain growth and intracrystalline deformation) and stage 2 densification (predominantly by sintering), except in a transition zone extending from ≈8 to ≈13 m from the surface in which 10-14% of the compaction occurs. Profiles of volumetric strain rate at each site show that in this transition zone the rates are consistent with the Arthern densification model. Comparison of the vertical densification rates and volumetric strain rates indicates that the expected relation to mean annual accumulation breaks down at high accumulation rates even when corrections are made for horizontal ice velocity divergence.

77 FR 55455 - Foreign-Trade Zone 235-Lakewood, NJ, Authorization of Production Activity, Cosmetic Essence...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-10

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-31-2012] Foreign-Trade Zone 235--Lakewood, NJ, Authorization of Production Activity, Cosmetic Essence Innovations, LLC, (Fragrance Bottling), Holmdel, NJ Cosmetic Essence Innovations, LLC (CEI) submitted a notification of proposed production activity to the...

Growth and Deposition of Inorganic Nutrient Elements in Developing Leaves of Zea mays L. 1

PubMed Central

Meiri, Avraham; Silk, Wendy Kuhn; Läuchli, André

1992-01-01

Spatial distributions of growth and of the concentration of some inorganic nutrient elements were analyzed in developing leaves of maize (Zea mays L.). Growth was analyzed by pinprick experiments with numerical analysis to characterize fields of velocity and relative elemental elongation rate. Inductively coupled plasma and atomic emission spectroscopy were used to measure nutrients extracted from segments of leaf tissue collected by position. Leaves 7 and 8, both elongating 3 millimeters per hour had maximum relative elemental growth rates of 0.06 to 0.08 millimeters per hour with maximum rates 20 to 50 millimeters from the node and cessation of growth by 90 millimeters from the node. Spatial distribution of dry weight density revealed that the rate of biomass deposition was maximum in the most rapidly expanding region and continued beyond the elongation zone. The nutrient elements K, Cl, Ca, Mg, and P showed different distribution patterns of ion density (on a dry weight basis). K and Cl had minimal density in the leaf tips; K density was maximum in the growing region, whereas Cl density was maximum at the region of growth cessation. Ca, Mg, and P had relatively high densities at the base of the elongation zone near the node and also in the tip regions. Near the node, P and Mg densities were higher in the young, growing leaves, whereas Ca density near the node was higher in older leaves that had completed elongation. Deposition rates of all nutrients were greatest in the region of maximum elongation rate. PMID:16669027

Simulation of dispersion in layered coastal aquifer systems

USGS Publications Warehouse

Reilly, T.E.

1990-01-01

A density-dependent solute-transport formulation is used to examine ground-water flow in layered coastal aquifers. The numerical experiments indicate that although the transition zone may be thought of as an impermeable 'sharp' interface with freshwater flow parallel to the transition zone in homogeneous aquifers, this is not the case for layered systems. Freshwater can discharge through the transition zone in the confining units. Further, for the best simulation of layered coastal aquifer systems, either a flow-direction-dependent dispersion formulation is required, or the dispersivities must change spatially to reflect the tight thin confining unit. ?? 1990.

Fluidized-bed catalytic coal-gasification process. [US patent; pretreatment to minimize agglomeration

DOEpatents

Euker, C.A. Jr.; Wesselhoft, R.D.; Dunkleman, J.J.; Aquino, D.C.; Gouker, T.R.

1981-09-14

Coal or similar carbonaceous solids impregnated with gasification catalyst constituents are oxidized by contact with a gas containing between 2 vol % and 21 vol % oxygen at a temperature between 50 and 250/sup 0/C in an oxidation zone and the resultant oxidized, catalyst impregnated solids are then gasified in a fluidized bed gasification zone at an elevated pressure. The oxidation of the catalyst impregnated solids under these conditions insures that the bed density in the fluidized bed gasification zone will be relatively high even though the solids are gasified at elevated pressure and temperature.

Antibacterial Activity of Cinnamaldehyde and Estragole Extracted from Plant Essential Oils against Pseudomonas syringae pv. actinidiae Causing Bacterial Canker Disease in Kiwifruit

PubMed Central

Song, Yu-Rim; Choi, Min-Seon; Choi, Geun-Won; Park, Il-Kwon; Oh, Chang-Sik

2016-01-01

Pseudomonas syringae pv. actinidiae (Psa) causes bacterial canker disease in kiwifruit. Antibacterial activity of plant essential oils (PEOs) originating from 49 plant species were tested against Psa by a vapor diffusion and a liquid culture assays. The five PEOs from Pimenta racemosa, P. dioica, Melaleuca linariifolia, M. cajuputii, and Cinnamomum cassia efficiently inhibited Psa growth by either assays. Among their major components, estragole, eugenol, and methyl eugenol showed significant antibacterial activity by only the liquid culture assay, while cinnamaldehyde exhibited antibacterial activity by both assays. The minimum inhibitory concentrations (MICs) of estragole and cinnamaldehyde by the liquid culture assay were 1,250 and 2,500 ppm, respectively. The MIC of cinnamaldehyde by the vapor diffusion assay was 5,000 ppm. Based on the formation of clear zones or the decrease of optical density caused by these compounds, they might kill the bacterial cells and this feature might be useful for managing the bacterial canker disease in kiwifruit. PMID:27493612

15 CFR 400.49 - Monitoring and reviews of zone operations and activity.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 15 Commerce and Foreign Trade 2 2013-01-01 2013-01-01 false Monitoring and reviews of zone operations and activity. 400.49 Section 400.49 Commerce and Foreign Trade Regulations Relating to Commerce... FOREIGN-TRADE ZONES BOARD Operation of Zones and Administrative Requirements § 400.49 Monitoring and...

15 CFR 400.49 - Monitoring and reviews of zone operations and activity.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 15 Commerce and Foreign Trade 2 2014-01-01 2014-01-01 false Monitoring and reviews of zone operations and activity. 400.49 Section 400.49 Commerce and Foreign Trade Regulations Relating to Commerce... FOREIGN-TRADE ZONES BOARD Operation of Zones and Administrative Requirements § 400.49 Monitoring and...

78 FR 28801 - Foreign-Trade Zone 117-Orange, TX, Authorization of Production Activity, Signal International...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-16

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-2-2013] Foreign-Trade Zone 117--Orange, TX, Authorization of Production Activity, Signal International Texas GP, LLC (Shipbuilding), Orange, TX On January 10, 2013, the Foreign Trade Zone of Southeast Texas, Inc., grantee of FTZ 117, submitted a...

77 FR 59890 - Foreign-Trade Zone 92-Gulfport, MS; Authorization of Production Activity; Gulf Ship, LLC...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-01

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-36-2012] Foreign-Trade Zone 92--Gulfport, MS; Authorization of Production Activity; Gulf Ship, LLC (Shipbuilding); Gulfport, MS On May 10, 2012, the Mississippi Coast Foreign-Trade Zone, Inc., grantee of FTZ 92, submitted a notification of proposed production...

78 FR 16465 - Foreign-Trade Zone 7-Mayaguez, Puerto Rico, Authorization of Production Activity, Pepsi Cola...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-15

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-84-2012] Foreign-Trade Zone 7--Mayaguez, Puerto Rico, Authorization of Production Activity, Pepsi Cola Puerto Rico Distributing, LLC (Soft Drink...-Trade Zones (FTZ) Board on behalf of Pepsi Cola Puerto Rico Distributing, LLC, in Toa Baja, Puerto Rico...

77 FR 47429 - Agency Information Collection Activities; Petroleum Refineries in Foreign Trade Sub-zones

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-08

... Activities; Petroleum Refineries in Foreign Trade Sub-zones AGENCY: U.S. Customs and Border Protection (CBP... requirement concerning the Petroleum Refineries in Foreign Trade Sub-zones. This request for comment is being...: Title: Petroleum Refineries in Foreign Trade Sub-zones. OMB Number: 1651-0063. Form Number: None...

Sky Compass Orientation in Desert Locusts-Evidence from Field and Laboratory Studies.

PubMed

Homberg, Uwe

2015-01-01

Locusts are long-range migratory insects. At high population density, immature animals form marching hopper bands while adults take off and form huge swarms of millions of animals. At low population densities animals are solitarious, but likewise migrate, mostly during the night. Numerous studies aimed at predicting locust infestations showed that migrations both as hopper bands and as adults are largely downwind following seasonal shifts of the tropical convergence zone taking the animals to areas of rainfall. Only a few studies provided evidence for active orientation mechanisms, including the involvement of a sun compass. This scarcity of evidence stands in contrast to recent neurobiological data showing sophisticated neuronal adaptations suited for sky compass navigation. These include a special dorsal eye region with photoreceptors suited to analyze the polarization pattern of the sky and a system of topographically arranged sky compass neurons in the central complex of the brain. Laboratory experiments, moreover, demonstrated polarotaxis in tethered flying animals. The discrepancy of these findings call for more rigorous field studies on active orientation mechanisms in locusts. It remains to be shown how locusts use their internal sky compass during mass migrations and what role it plays to guide solitarious locusts in their natural habitat.

Estimating organic maturity from well logs, Upper Cretaceous Austin Chalk, Texas Gulf coast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hines, G.A.; Berg, R.R.

1990-09-01

The Austin Chalk is both a source rock for oil and a fractured reservoir, and the evaluation of its organic maturity from well logs could be an aid to exploration and production. Geochemical measurements have shown three zones of organic maturity for source materials: (1) an immature zone to depths of 6,000 ft, (2) a peak-generation and accumulation zone from 6,000 to 6,500 ft, and (3) a mature, expulsion and migration zone below 6,500 ft. The response of common well logs identifies these zones. True resistivity (R{sub t}) is low in the immature zone, increases to a maximum in themore » peak-generation zone, and decreases to intermediate values in the expulsion zone. Density and neutron porosities are different in the immature zone but are nearly equal in the peak generation and expulsion zones. Correlations with conventional core analyses indicate that R{sub t} values between 9 and 40 ohm-m in the expulsion zone reflect a moveable oil saturation of 10 to 20% in the rock matrix. The moveable saturation provides oil from the matrix to fractures and is essential for sustained oil production. Therefore, the evaluation of moveable oil from well logs could be important in exploration.« less

Mutational Analysis of Rab3 Function for Controlling Active Zone Protein Composition at the Drosophila Neuromuscular Junction

PubMed Central

Roche, John P.; Alsharif, Peter; Graf, Ethan R.

2015-01-01

At synapses, the release of neurotransmitter is regulated by molecular machinery that aggregates at specialized presynaptic release sites termed active zones. The complement of active zone proteins at each site is a determinant of release efficacy and can be remodeled to alter synapse function. The small GTPase Rab3 was previously identified as playing a novel role that controls the distribution of active zone proteins to individual release sites at the Drosophila neuromuscular junction. Rab3 has been extensively studied for its role in the synaptic vesicle cycle; however, the mechanism by which Rab3 controls active zone development remains unknown. To explore this mechanism, we conducted a mutational analysis to determine the molecular and structural requirements of Rab3 function at Drosophila synapses. We find that GTP-binding is required for Rab3 to traffick to synapses and distribute active zone components across release sites. Conversely, the hydrolytic activity of Rab3 is unnecessary for this function. Through a structure-function analysis we identify specific residues within the effector-binding switch regions that are required for Rab3 function and determine that membrane attachment is essential. Our findings suggest that Rab3 controls the distribution of active zone components via a vesicle docking mechanism that is consistent with standard Rab protein function. PMID:26317909

Effects of heterogeneous traffic with speed limit zone on the car accidents

NASA Astrophysics Data System (ADS)

Marzoug, R.; Lakouari, N.; Bentaleb, K.; Ez-Zahraouy, H.; Benyoussef, A.

2016-06-01

Using the extended Nagel-Schreckenberg (NS) model, we numerically study the impact of the heterogeneity of traffic with speed limit zone (SLZ) on the probability of occurrence of car accidents (Pac). SLZ in the heterogeneous traffic has an important effect, typically in the mixture velocities case. In the deterministic case, SLZ leads to the appearance of car accidents even in the low densities, in this region Pac increases with increasing of fraction of fast vehicles (Ff). In the nondeterministic case, SLZ decreases the effect of braking probability Pb in the low densities. Furthermore, the impact of multi-SLZ on the probability Pac is also studied. In contrast with the homogeneous case [X. Li, H. Kuang, Y. Fan and G. Zhang, Int. J. Mod. Phys. C 25 (2014) 1450036], it is found that in the low densities the probability Pac without SLZ (n = 0) is low than Pac with multi-SLZ (n > 0). However, the existence of multi-SLZ in the road decreases the risk of collision in the congestion phase.

Understanding exchanges across turbulent/stratified zones interfaces

NASA Astrophysics Data System (ADS)

Le Bars, M.; Ribeiro, A.; Le Gal, P.; Aurnou, J. M.

2013-12-01

In many geophysical and astrophysical situations, a turbulent fluid layer is separated from a stably stratified one by a relatively sharp but deformable interface. Examples include the convective and radiative zones in stars, the atmospheric convective layer and overlying stratosphere, the Earth's outer core... While motions in the stratified layer are often neglected, it actually supports oscillatory motions called gravito-inertial waves (GIW) excited by Reynolds stresses, entropy fluctuations and interface deformations associated with the turbulence. Besides their direct observation as for instance in asteroseismology, GIW transport energy, carry momentum, break, mix... and are thus essential for accurate models of global climate and solar or core dynamics. Global integrated models including length scales and time scales spanning many orders of magnitude are required to fully address motions in turbulent and stratified zones and to understand the details of the highly non-linear couplings between rotation, meridional circulation, turbulence and waves: this is clearly very challenging from both analytical and numerical points of view. Here, we present results from two complementary laboratory experiments using water as a working fluid and salt or temperature to control the buoyancy effects, allowing to address the whole range of relevant physical issues in simplified models. In the first set-up, we take benefit from the unusual property of water that its density has a maximum value near 4oC to study its convective and oscillatory motions in a tank with a bottom boundary at about 0oC and a hotter upper surface. High precision local measurements of temperature fluctuations are performed simultaneously in the convective and stratified zones to produce the corresponding power density spectrum and probability density function. In the second set-up, a turbulent jet generated by injection of water impinges upon the interface between a uniform density layer and a stratified one of salted water. The experiment is performed on a rotating table. Velocity measurements are carried out non-intrusively using Particle Imaging Velocimetry in both regions. Our combined results show that (i) the interface acts as a filter which mostly allows for the passing of low frequency perturbations, while (ii) the further propagation of the excited waves in the stratified zone gives rise to selective wave damping, focusing the transported energy and momentum around given frequencies corresponding to selected propagation angles. We explain those results with a simple analytical model, allowing their extension to natural configurations.

Radio Studies of Coronal Holes.

DTIC Science & Technology

1981-03-01

Withbroe (1978) has pointed out, "The transport of energy by thermal conduction into the transition zone is a primary coronal cooling mechanism." Thus, the...temperature and particle density gradients in the transition zone are of critical importance in understanding the energy balance of a coronal hole. The...coronal hole has been provided by Konp and Orrall (1977), but a quantitative understanding requires a detailed knowledge of the energy balance in the

Can Supersaturation Affect Protein Crystal Quality?

NASA Technical Reports Server (NTRS)

Gorti, Sridhar

2013-01-01

In quiescent environments (microgravity, capillary tubes, gels) formation of a depletion zone is to be expected, due either to limited sedimentation, density driven convection or a combination of both. The formation of a depletion zone can: Modify solution supersaturation near crystal; Give rise to impurity partitioning. It is conjectured that both supersaturation and impurity partitioning affect protein crystal quality and size. Further detailed investigations on various proteins are needed to assess above hypothesis.

Mathematical modeling of velocity and number density profiles of particles across the flame propagation through a micro-iron dust cloud.

PubMed

Bidabadi, Mehdi; Haghiri, Ali; Rahbari, Alireza

2010-04-15

In this study, an attempt has been made to analytically investigate the concentration and velocity profiles of particles across flame propagation through a micro-iron dust cloud. In the first step, Lagrangian particle equation of motion during upward flame propagation in a vertical duct is employed and then forces acting upon the particle, such as thermophoretic force (resulted from the temperature gradient), gravitation and buoyancy are introduced; and consequently, the velocity profile as a function of the distance from the leading edge of the combustion zone is extracted. In the resumption, a control volume above the leading edge of the combustion zone is considered and the change in the particle number density in this control volume is obtained via the balance of particle mass fluxes passing through it. This study explains that the particle concentration at the leading edge of the combustion zone is more than the particle agglomeration in a distance far from the flame front. This increase in the particle aggregation above the combustion zone has a remarkable effect on the lower flammability limits of combustible particle cloud. It is worth noticing that the velocity and particle concentration profiles show a reasonable compatibility with the experimental data. 2009 Elsevier B.V. All rights reserved.

Structural characteristics of epicentral areas in Central Europe: study case Cheb Basin (Czech Republic)

NASA Astrophysics Data System (ADS)

Bankwitz, P.; Schneider, G.; Kämpf, H.; Bankwitz, E.

2003-03-01

The earthquake distribution pattern of Central Europe differs systematically from the neighbouring areas of NW and southern Europe regarding the fault plane kinematics. Within a belt between the French Massif Central and the northern part of the Bohemian Massif (1000 km) sinistral faulting along N-S zones dominates on the contrary to the Alps and their foreland with common bookshelf shears. One of the prominent N-S structures is the Regensburg-Leipzig-Rostock Zone (A) with several epicentral areas, where the main seismic center occurs in the northern Cheb Basin (NW Bohemia). The study demonstrates new structural results for the swarm-quake region in NW-Bohemia, especially for the Nový Kostel area in the Cheb Basin. There the N-S-trending newly found Počatky-Plesná zone (PPZ) is identical with the main earthquake line. The PPZ is connected with a mofette line between Hartušov and Bublák with evidence for CO 2 degassing from the subcrustal mantle. The morphologically more prominent Mariánské Lázně fault (MLF) intersects the PPZ obliquely under an acuate angle. In the past the MLF was supposed to be the tectonic structure connected with the epicentral area of Nový Kostel. But evidence from the relocated hypocentres along the PPZ (at 7-12 kms depth) indicate that the MLF is seismically non-active. Asymmetric drainage patterns of the Cheb Basin are caused by fault related movement along Palaeozoic basement faults which initiate a deformation of the cover (Upper Pliocene to Holocene basin filling). The PPZ forms an escarpment in Pliocene and Pleistocene soft rock and is supposingly acting as an earthquake zone since late Pleistocene time. The uppermost Pleistocene of 0.12-0.01 Ma deposited only in front of the fault scarp dates the fault activity. The crossing faults envelope crustal wedges under different local stress conditions. Their intersection line forms a zone beginning at the surface near Nový Kostel, dipping south with increasing depth, probably down to about 12 km. The intersection zone represents a crustal anomaly. There fault movements can be blocked up and peculiar stress condition influence the behaviour of the adjacent crust. An ENE-WNW striking dextral wrench fault was detected which is to expect as kinematic counterpart to the ca. N-S striking sinistral shear zones. Nearly E-W striking fracture segments were formerly only known as remote sensing lineaments or as joint density zones. The ENE shear zone is characterized by a set of compressional m-scale folds and dm-scale faults scattered within a 20 m wide wrench zone. It is built up of different sets of cleavage-like clay plate pattern of microscopical scale. The associated shear planes fit into a Riedel shear system. One characteristic feature are tiny channels of micrometer scale. They have originated after shear plane bending and are the sites of CO 2 mantle degassing.

Reservoir zonation based on statistical analyses: A case study of the Nubian sandstone, Gulf of Suez, Egypt

NASA Astrophysics Data System (ADS)

El Sharawy, Mohamed S.; Gaafar, Gamal R.

2016-12-01

Both reservoir engineers and petrophysicists have been concerned about dividing a reservoir into zones for engineering and petrophysics purposes. Through decades, several techniques and approaches were introduced. Out of them, statistical reservoir zonation, stratigraphic modified Lorenz (SML) plot and the principal component and clustering analyses techniques were chosen to apply on the Nubian sandstone reservoir of Palaeozoic - Lower Cretaceous age, Gulf of Suez, Egypt, by using five adjacent wells. The studied reservoir consists mainly of sandstone with some intercalation of shale layers with varying thickness from one well to another. The permeability ranged from less than 1 md to more than 1000 md. The statistical reservoir zonation technique, depending on core permeability, indicated that the cored interval of the studied reservoir can be divided into two zones. Using reservoir properties such as porosity, bulk density, acoustic impedance and interval transit time indicated also two zones with an obvious variation in separation depth and zones continuity. The stratigraphic modified Lorenz (SML) plot indicated the presence of more than 9 flow units in the cored interval as well as a high degree of microscopic heterogeneity. On the other hand, principal component and cluster analyses, depending on well logging data (gamma ray, sonic, density and neutron), indicated that the whole reservoir can be divided at least into four electrofacies having a noticeable variation in reservoir quality, as correlated with the measured permeability. Furthermore, continuity or discontinuity of the reservoir zones can be determined using this analysis.

Effects of Nautical Traffic and Noise on Foraging Patterns of Mediterranean Damselfish (Chromis chromis)

PubMed Central

Bracciali, Claudia; Campobello, Daniela; Giacoma, Cristina; Sarà, Gianluca

2012-01-01

Chromis chromis is a key species in the Mediterranean marine coastal ecosystems where, in summer, recreational boating and its associated noise overlap. Anthropogenic noise could induce behavioural modifications in marine organisms, thereby affecting population dynamics. In the case of an important species for the ecosystem like C. chromis, this could rebound on the community structure. Here, we measured nautical traffic during the summer of 2007 in a Southern Mediterranean Marine Protected Area (MPA) and simultaneously the feeding behaviour of C. chromis was video-recorded, within both the no-take A-zone and the B-zone where recreational use is allowed. Feeding frequencies, escape reaction and school density were analysed. C. chromis specimens were also collected from 2007 to 2008 to evaluate their physiological state using the Body Condition Index as a proxy of feeding efficiency. The MPA was more exploited by nautical tourism during holidays than on weekdays, particularly in the middle of the day. Greater traffic volume corresponded with lower feeding frequencies. The escape reaction was longer in duration (>1 min) when boat passed nearby, while moored boats did not induce an escape response. We found no differences in density between schools in the A- and B-zones and worse body conditions among those individuals inhabiting the B-zone in one area only. Overall, our findings revealed a significant modification of the daily foraging habits of C. chromis due to boat noise, which was slightly buffered by no-take zones established within the MPA. PMID:22792375

Multifocal electroretinography changes at the 1-year follow-up in a cohort of diabetic macular edema patients treated with ranibizumab.

PubMed

Baget-Bernaldiz, Marc; Romero-Aroca, Pedro; Bautista-Perez, Angel; Mercado, Joaquin

2017-10-01

To determine the changes in the multifocal electroretinogram (mfERG) at 1 year in a clinical series of diabetic macular edema (DME) patients treated with ranibizumab (RNBZ) using a pro re nata protocol. We analyzed a clinical series of 35 eyes of 35 patients with DME at baseline and after treating them with RNBZ over 1 year, in order to determine the change in the macular function, which was assessed by means of the response density and the implicit time of the first-order kernel (FOK) P1 wave of the mfERG at the foveola (R1), fovea (R2) and parafovea (R3). These electrophysiological parameters were studied taking into account different independent variables, such as DME type, degree of diabetic retinopathy (DR), level of preservation of both the ellipsoid zone (IS/OS) and the external limiting membrane (ELM) and changes in central retinal thickness (CRT) and total macular volume (TMV). We also studied the relationship between the response density and the best-corrected visual acuity (BCVA). Eyes with cystic and spongiform DME showed better response density with respect to the serous type (p < 0.001) at baseline. Similarly, eyes with high IS/OS and ELM preservation rates showed higher initial response density compared to the others (p < 0.001). Eyes with moderate DR had better response density compared to those with severe and proliferative DR (p = 0.001). At the beginning of the study, those eyes with proliferative and severe DR showed longer implicit times with respect to those with moderate DR (p = 0.04). The response density significantly increased in eyes that anatomically restored the IS/OS and the ELM after being treated with RNBZ (both p < 0.001). Similarly, eyes with spongiform DME further improved the response density with respect to those with cystic and serous DME (p < 0.001). On the contrary, eyes with hard exudates showed less improvement in their response density at the end of the study (p < 0.001). We observed a significant relationship between BCVA and the response density achieved at the end of the study (p = 0.012). Eyes with severe and proliferative DR significantly shortened implicit time compared to those with moderate DR (p = 0.04). The multifocal electroretinogram allowed us to differentiate groups of eyes with DME according to their electrophysiological profile, both initially and after being treated with RNBZ. Ranibizumab increased the response density in all DME types included in the study, with a maximum response in those eyes with spongiform type. Once treated with RNBZ, the macular electrophysiological activity improved in eyes that had a well-preserved ellipsoid zone and ELM. The presence of hard exudates was a limitation to the response density achieved at the foveola.

Response of megabenthic assemblages to different scales of habitat heterogeneity on the Mauritanian slope

NASA Astrophysics Data System (ADS)

Jones, Daniel O. B.; Brewer, Michael E.

2012-09-01

The topographically complex deep seabed on the Mauritanian slope, from 990 to 1460 m water depth, was imaged with video in an extensive quantitative survey of 17,199 m2 of seafloor using a Remote Operated Vehicle (ROV). This study investigated the influence of habitat heterogeneity at two scales on the megafaunal assemblages observed by ROV. Changes in megafaunal assemblages on the Mauritanian slope were assessed at a broad scale, within depth zones, and at a finer scale, in response to changes in local geomorphology associated with submarine landslides. Geomorphology was determined by classification of habitat parameters (slope, aspect, bathymetric position, curvature, fractal dimension and ruggedness) derived from an autonomous underwater vehicle-based multibeam bathymetry survey. Habitat parameters were classified by Iterative Self Organizing Clustering into six major geomorphological groups, four of which were assessed in the ROV video survey. A total of 29 megafaunal taxa were observed along the entire survey, with an overall average faunal density of 0.344 ind m-2. Megafaunal assemblage density, species richness and evenness varied significantly across the depth range of the survey in the most common geomorphological zone (sedimentary plains of low slope and complexity). Characteristic species inhabited the shallow areas (asteroid, ophiuroid, anemone, small macrourid), intermediate areas (Benthothuria funabris, black cerianthid, squat lobster) and deeper areas (the holothurians Enypniastes eximia and Elipidia echinata). Megafaunal density, species richness and evenness were not significantly different between geomorphogical groups within one depth zone (1300-1400 m). However, the steepest zone, on the edge of a major headwall feature, had four unique taxa (Parapagurus pilosimanus, a comatulid crinoid, a gorgonian and its associated ophiuroid).

Specific Reactions of Different Striatal Neuron Types in Morphology Induced by Quinolinic Acid in Rats

PubMed Central

Mu, Shuhua; Wu, Jiajia; Chen, Si; OuYang, Lisi; Lei, Wanlong

2014-01-01

Huntington's disease (HD) is a neurological degenerative disease and quinolinic acid (QA) has been used to establish HD model in animals through the mechanism of excitotoxicity. Yet the specific pathological changes and the underlying mechanisms are not fully elucidated. We aimed to reveal the specific morphological changes of different striatal neurons in the HD model. Sprague-Dawley (SD) rats were subjected to unilaterally intrastriatal injections of QA to mimic the HD model. Behavioral tests, histochemical and immunhistochemical stainings as well as Western blots were applied in the present study. The results showed that QA-treated rats had obvious motor and cognitive impairments when compared with the control group. Immunohistochemical detection showed a great loss of NeuN+ neurons and Darpp32+ projection neurons in the transition zone in the QA group when compared with the control group. The numbers of parvalbumin (Parv)+ and neuropeptide Y (NPY)+ interneurons were both significantly reduced while those of calretinin (Cr)+ and choline acetyltransferase (ChAT)+ were not changed notably in the transition zone in the QA group when compared to the controls. Parv+, NPY+ and ChAT+ interneurons were not significantly increased in fiber density while Cr+ neurons displayed an obvious increase in fiber density in the transition zone in QA-treated rats. The varicosity densities of Parv+, Cr+ and NPY+ interneurons were all raised in the transition zone after QA treatment. In conclusion, the present study revealed that QA induced obvious behavioral changes as well as a general loss of striatal projection neurons and specific morphological changes in different striatal interneurons, which may help further explain the underlying mechanisms and the specific functions of various striatal neurons in the pathological process of HD. PMID:24632560

Microstructural and Compositional Features of the Fibrous and Hyaline Cartilage on the Medial Tibial Plateau Imply a Unique Role for the Hopping Locomotion of Kangaroo

PubMed Central

He, Bo; Wu, Jian Ping; Xu, Jiake; Day, Robert E.; Kirk, Thomas Brett

2013-01-01

Hopping provides efficient and energy saving locomotion for kangaroos, but it results in great forces in the knee joints. A previous study has suggested that a unique fibrous cartilage in the central region of the tibial cartilage could serve to decrease the peak stresses generated within kangaroo tibiofemoral joints. However, the influences of the microstructure, composition and mechanical properties of the central fibrous and peripheral hyaline cartilage on the function of the knee joints are still to be defined. The present study showed that the fibrous cartilage was thicker and had a lower chondrocyte density than the hyaline cartilage. Despite having a higher PG content in the middle and deep zones, the fibrous cartilage had an inferior compressive strength compared to the peripheral hyaline cartilage. The fibrous cartilage had a complex three dimensional collagen meshwork with collagen bundles parallel to the surface in the superficial zone, and with collagen bundles both parallel and perpendicular to the surface in the middle and deep zones. The collagen in the hyaline cartilage displayed a typical Benninghoff structure, with collagen fibres parallel to the surface in the superficial zone and collagen fibres perpendicular to the surface in the deep zone. Elastin fibres were found throughout the entire tissue depth of the fibrous cartilage and displayed a similar alignment to the adjacent collagen bundles. In comparison, the elastin fibres in the hyaline cartilage were confined within the superficial zone. This study examined for the first time the fibrillary structure, PG content and compressive properties of the central fibrous cartilage pad and peripheral hyaline cartilage within the kangaroo medial tibial plateau. It provided insights into the microstructure and composition of the fibrous and peripheral hyaline cartilage in relation to the unique mechanical properties of the tissues to provide for the normal activities of kangaroos. PMID:24058543

Microstructural and compositional features of the fibrous and hyaline cartilage on the medial tibial plateau imply a unique role for the hopping locomotion of kangaroo.

PubMed

He, Bo; Wu, Jian Ping; Xu, Jiake; Day, Robert E; Kirk, Thomas Brett

2013-01-01

Hopping provides efficient and energy saving locomotion for kangaroos, but it results in great forces in the knee joints. A previous study has suggested that a unique fibrous cartilage in the central region of the tibial cartilage could serve to decrease the peak stresses generated within kangaroo tibiofemoral joints. However, the influences of the microstructure, composition and mechanical properties of the central fibrous and peripheral hyaline cartilage on the function of the knee joints are still to be defined. The present study showed that the fibrous cartilage was thicker and had a lower chondrocyte density than the hyaline cartilage. Despite having a higher PG content in the middle and deep zones, the fibrous cartilage had an inferior compressive strength compared to the peripheral hyaline cartilage. The fibrous cartilage had a complex three dimensional collagen meshwork with collagen bundles parallel to the surface in the superficial zone, and with collagen bundles both parallel and perpendicular to the surface in the middle and deep zones. The collagen in the hyaline cartilage displayed a typical Benninghoff structure, with collagen fibres parallel to the surface in the superficial zone and collagen fibres perpendicular to the surface in the deep zone. Elastin fibres were found throughout the entire tissue depth of the fibrous cartilage and displayed a similar alignment to the adjacent collagen bundles. In comparison, the elastin fibres in the hyaline cartilage were confined within the superficial zone. This study examined for the first time the fibrillary structure, PG content and compressive properties of the central fibrous cartilage pad and peripheral hyaline cartilage within the kangaroo medial tibial plateau. It provided insights into the microstructure and composition of the fibrous and peripheral hyaline cartilage in relation to the unique mechanical properties of the tissues to provide for the normal activities of kangaroos.

77 FR 70417 - Foreign-Trade Zone 7-Mayaguez, Puerto Rico; Notification of Proposed Production Activity; Pepsi...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-26

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Active faults and minor plates in NE Asia

NASA Astrophysics Data System (ADS)

Kozhurin, Andrey I.; Zelenin, Egor A.

2014-05-01

Stated nearly 40 yr ago the uncertainty with plate boundaries location in NE Asia (Chapman, Solomon, 1976) still remains unresolved. Based on the prepositions that a plate boundary must, first, reveal itself in linear sets of active structures, and, second, be continuous and closed, we have undertaken interpretation of medium-resolution KH-9 Hexagon satellite imageries, mostly in stereoscopic regime, for nearly the entire region of NE Asia. Main findings are as follows. There are two major active fault zones in the region north of the Bering Sea. One of them, the Khatyrka-Vyvenka zone, stretches NE to ENE skirting the Bering Sea from the Kamchatka isthmus to the Navarin Cape. Judging by the kinematics of the Olyutorsky 2006 earthquake fault, the fault zones move both right-laterally and reversely. The second active fault zone, the Lankovaya-Omolon zone, starts close to the NE margin of the Okhotsk Sea and extends NE up to nearly the margin of the Chukcha Sea. The fault zone is mostly right-lateral, with topographically expressed cumulative horizontal offsets amounting to 2.5-2.6 km. There may be a third NE-SW zone between the major two coinciding with the Penzhina Range as several active faults found in the southern termination of the Range indicate. The two active fault zones divide the NE Asia area into two large domains, which both could be parts of the Bering Sea plate internally broken and with uncertain western limit. Another variant implies the Khatyrka-Vyvenka zone as the Bering Sea plate northern limit, and the Lankovaya-Omolon zone as separating an additional minor plate from the North-American plate. The choice is actually not crucial, and more important is that both variants leave the question of where the Bering Sea plate boundary is in Alaska. The Lankovaya-Omolon zone stretches just across the proposed northern boundary of the Okhorsk Sea plate. NW of the zone, there is a prominent left-lateral Ulakhan fault, which is commonly interpreted to be a portion of the plate northern boundary. With this, we have discovered no active faults or fault zones of the Ulakhan fault strike, which could be the portion of the boundary between the Lankovaya-Omolon zone and either the western margin of the Komandor basin or the westernmost Aleutians. We conclude that there is a certain disagreement between active faulting pattern and plate models for NE Asia, relating to the extent of the plates and missing portions of the plate boundaries. The research was supported by grant # 110500136-a from the Russian Foundation for Basic Research.

78 FR 51707 - Foreign-Trade Zone 59-Lincoln, Nebraska; Authorization of Production Activity; CNH America, LLC...

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2013-08-21

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2013-12-11

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Variability of E. coli density and sources in an urban watershed.

PubMed

Wu, J; Rees, P; Dorner, S

2011-03-01

The objective of this study was to characterize the variability of Escherichia coli density and sources in an urban watershed, particularly to focus on the influences of weather and land use. E. coli as a microbial indicator was measured at fourteen sites in four wet weather events and four dry weather conditions in the upper Blackstone River watershed. The sources of E. coli were identified by ribotyping. The results showed that wet weather led to sharp increases of E. coli densities. Interestingly, an intense storm of short duration led to a higher E. coli density than a moderate storm of long duration (p<0.01). The ribotyping patterns revealed microbial sources were mainly attributed to humans and wildlife, but varied in different weather conditions and were associated with the patterns of land use. Human sources accounted for 24.43% in wet weather but only 9.09% in dry weather. In addition, human sources were more frequently observed in residential zones (>30% of the total sources), while wildlife sources were dominant in open land and forest zones (54%). The findings provide useful information for developing optimal management strategies aimed at reducing the level of pathogens in urban watersheds.

Factors influencing fish and macrocrustacean communities in the surf zone of sandy beaches in Belgium: temporal variation

NASA Astrophysics Data System (ADS)

Beyst, Bregje; Hostens, Kris; Mees, Jan

2001-12-01

Monthly samples were taken in the surf zone of sandy beaches along the Belgian coast from May 1996 until July 1997 at four selected stations. Temporal patterns of the macrocrustacean and fish species residing the surf zone were investigated, as well as the abiotic variables structuring the community. In total 34 species were recorded belonging to caridean shrimps (3), anomuran and brachyuran crabs (5), cephalopods (2) and fish (24). The brown shrimp Crangon crangon dominated almost all samples (>80%). Total densities often exceeded 400 ind per 100 m2, and if C. crangon was excluded 10 ind per 100 m2. Notwithstanding the harsh hydrodynamic conditions, the surf zone of Belgian sandy beaches is used intensively by a number of epibenthic macro-crustaceans and demersal fish species. Seven resident and ten migrant species were identified. As mainly juvenile fishes were present, the surf zone of the Belgian sandy beaches may act as a nursery for longer (e.g. plaice Pleuronectes platessa) or shorter (e.g. brill Scophthalmus rhombus) periods. However, its nursery function should be studied in more detail, since the highly dynamic circumstances and more specifically wave height and wind speed may be important structuring factors for the epibenthic communities. The surf zone of Belgian sandy beaches also seems to function as a transient area to other nurseries (e.g. bass Dicentrarchus labrax) or between a nursery and the true marine environment (e.g. dab Limanda limanda). Temporal variation in community structure was greatly masked by spatial differences between sites. Although variables such as salinity and hydrodynamic factors may have influenced the data, clear temperature-related, seasonal patterns occur. Most likely, extreme winter conditions and subsequent migration of organisms to deeper waters caused a decline in winter in both density and diversity.

Färoe-Iceland Ridge Experiment: 1. Crustal structure of northeastern Iceland

USGS Publications Warehouse

Staples, Robert K.; White, Robert S.; Brandsdottir, Bryndis; Menke, William; Maguire, Peter K.H.; McBride, John H.

1997-01-01

Results from the Färoe-Iceland Ridge Experiment (FIRE) constrain the crustal thickness as 19 km under the Northern Volcanic Zone of Iceland and 35 km under older Tertiary areas of northeastern Iceland. The Moho is defined by strong P wave and S wave reflections. Synthetic seismogram modeling of the Moho reflection indicates mantle velocities of at least 8.0 km/s beneath the Tertiary areas of northeastern Iceland and at least 7.9 km/s beneath the neovolcanic zone. Crustal diving rays resolve the structure of the upper and lower crust. Surface P wave velocities are 1.1–4.0 km/s in Quaternary rocks and are rather higher, 4.4–4.7 km/s, in the Tertiary basalts that outcrop elsewhere. The highest crustal P wave velocities observed directly from diving rays are 7.1 km/s, from rays that turn at 24 km depth. Velocities of 7.35 km/s at the base of the crust are inferred from extrapolation of the lower crustal velocity gradient (0.024 s−1). A Poisson's ratio of approximately 0.27, equivalent to an S wave to P wave travel time ratio of 1.78, is measured throughout the crust east of the neovolcanic zone. The Poisson's ratio and the steep Moho topography (in places up to 30° from the horizontal) indicate that the entire crust outside the neovolcanic zone is cool (<800°C). Gravity data are well matched by a velocity/density conversion of our seismic crustal model and indicate a region of low mantle density beneath the neovolcanic zone, believed to be due to elevated mantle temperatures. The crustal thickness in the neovolcanic zone is consistent with geochemical estimates of the melt generation, placing constraints on the flow within the Iceland mantle plume.

Diatom assemblages from a turbid coastal plain estuary: Río de la Plata (South America)

NASA Astrophysics Data System (ADS)

Licursi, Magdalena; Sierra, María Victoria; Gómez, Nora

2006-08-01

The Río de la Plata is located on the East coast of South America and is a shallow, large-scale, turbid coastal plain estuary that covers an approximate area of 35,000 km 2. Despite the socio-economic importance of the Río de la Plata, studies related to the biological aspects of this ecosystem are scarce, particularly in the freshwater tidal zone. The objective of this study was to explore the diatom composition and distribution of density, biomass and empty frustules along the fluvial-mixohaline axis. Furthermore it was to analyze the spatial succession of diatom assemblages and the environmental variables during an extensive sampling carried out during spring 2001. Two replicate sub-surface water samples were collected at 29 sites for quantitative analysis of phytoplankton. The greatest number of species, mainly pennate taxa, were observed in the freshwater tidal zone. The average density of the diatoms was 59 cells ml - 1 . Chains or filaments of centric diatoms were frequent and dominant in the samples along the fluvial-mixohaline axis. The carbon content of the diatoms increased downstream, with an average value of 2.5 μg C l - 1 in the freshwater tidal zone and 4.4 μg C l - 1 in the mixohaline zone. Diatoms supplied 65% of the total phytoplankton carbon content in the freshwater tidal zone and reached 17% in the mixohaline zone. Canonical Correspondence Analysis (CCA) allowed us to identify two species assemblages in the Río de la Plata differentiated mainly by salinity, pH and silicate gradients. In our study species exclusive to brackish waters were not identified, but some freshwater and marine taxa with wide ranges of salinity tolerance were observed.

Seismic Characterization of a Gas Hydrate Chimney Associated with Acoustic Blanking: Pegasus Basin, New Zealand

NASA Astrophysics Data System (ADS)

Henrys, S. A.; Fraser, D. R. A.; Gorman, A. R.; Pecher, I. A.; Crutchley, G. J.

2016-12-01

The Pegasus Basin on the east coast of New Zealand's North Island in the southern part of the Hikurangi Margin is a frontier petroleum basin that is also expected to contain significant gas hydrate deposits. Extensive faulting in the basin has lead to the development of many interesting and unique focused accumulations of gas hydrates. A 2D seismic dataset acquired in 2009/2010 was reprocessed to examine the gas hydrate systems within the basin. Here, we present one of the more interesting hydrate features in the dataset: a presumed gas chimney within the regional gas hydrate stability zone at the centre of a roughly triangular (in 2D) region of low reflectivity, approximately 8 km wide, that is interpreted to be the result of acoustic blanking. Using automated high density velocity picking, the chimney structure is interpreted to be cored by a 200 m wide low-velocity zone which contains free gas and is flanked by high-velocity bands that are 200-400 m wide. The high-velocity zone is interpreted to correspond to concentrated hydrate deposits within the sedimentary pore spaces. Amplitude vs offset (AVO) and inversion techniques have been applied and the results of this work correspond well to the high-density velocity analyses. The analysis methods all indicate zones of free gas below the Bottom Simulating Reflection (BSR) and within the chimney. Areas of increased hydrate concentrations, including at the base of the gas hydrate stability zone, were also identified. A model for fluid flow and how free gas within the chimney at the centre of the blanking zone is converted to hydrate is discussed. The potential size of the gas hydrate resource present in this feature can be estimated based on the seismic velocities and physical properties determined by inversion.

H α and H β Raman scattering line profiles of the symbiotic star AG Pegasi

NASA Astrophysics Data System (ADS)

Lee, Seong-Jae; Hyung, Siek

2018-04-01

The H α and H β line profiles of the symbiotic star AG Pegasi, observed in 1998 September (phase ϕ = 10.24), display top narrow double Gaussian components and bottom broad components (FWHM = 200-400 km s-1). The photoionization model indicates that the ionized zone, responsible for the hydrogen Balmer and Lyman lines, is radiation-bounded, with a hydrogen gas number density of nH ˜ 109.85 cm-3 and a gas temperature of Te = 12 000-15 000 K. We have carried out Monte Carlo simulations to fit the Raman scattering broad wings, assuming that the hydrogen Ly β and Ly γ lines emitted within the radiation-bounded H II zone around a white dwarf have the same double Gaussian line profile shape as the hydrogen Balmer lines. The simulation shows that the scattering H I zones are attached to (or located just outside) the inner H II shells. The best fit to the observed broad H I line profiles indicates that the column density of the scattering neutral zone is NH ≃ 3-5 × 1019 cm-2. We have examined whether the geometrical structure responsible for the observed H α and H β line profiles is a bipolar conical shell structure, consisting of the radiation-bounded ionized zone and the outer material bounded neutral zone. The expanding bipolar structure might be two opposite regions of the common envelope or the outer shell of the Roche lobe around the hot white dwarf, formed through the mass inflows from the giant star and pushed out by the fast winds from the hot white dwarf.

2014 Mainshock-Aftershock Activity Versus Earthquake Swarms in West Bohemia, Czech Republic

NASA Astrophysics Data System (ADS)

Jakoubková, Hana; Horálek, Josef; Fischer, Tomáš

2018-01-01

A singular sequence of three episodes of ML3.5, 4.4 and 3.6 mainshock-aftershock occurred in the West Bohemia/Vogtland earthquake-swarm region during 2014. We analysed this activity using the WEBNET data and compared it with the swarms of 1997, 2000, 2008 and 2011 from the perspective of cumulative seismic moment, statistical characteristics, space-time distribution of events, and prevailing focal mechanisms. For this purpose, we improved the scaling relation between seismic moment M0 and local magnitude ML by WEBNET. The total seismic moment released during 2014 episodes (M_{0tot}≈ 1.58× 10^{15} Nm) corresponded to a single ML4.6+ event and was comparable to M_{0tot} of the swarms of 2000, 2008 and 2011. We inferred that the ML4.8 earthquake is the maximum expected event in Nový Kostel (NK), the main focal zone. Despite the different character of the 2014 sequence and the earthquake swarms, the magnitude-frequency distributions (MFDs) show the b-values ≈ 1 and probability density functions (PDFs) of the interevent times indicate the similar event rate of the individual swarms and 2014 activity. Only the a-value (event-productivity) in the MFD of the 2014 sequence is significantly lower than those of the swarms. A notable finding is a significant acceleration of the seismic moment release in each subsequent activity starting from the 2000 swarm to the 2014 sequence, which may indicate an alteration from the swarm-like to the mainshocks-aftershock character of the seismicity. The three mainshocks are located on a newly activated fault segment/asperity (D in out notation) of the NK zone situated in the transition area among fault segments A, B, C, which hosted the 2000, 2008 and 2011 swarms. The segment D appears to be predisposed to an oblique-thrust faulting while strike-slip faulting is typical of segments A, B and C. In conclusion, we propose a basic segment scheme of the NK zone which should be improved gradually.

Effect of emergent aquatic insects on bat foraging in a riparian forest.

PubMed

Fukui, Dai; Murakami, Masashi; Nakano, Shigeru; Aoi, Toshiki

2006-11-01

1. Riparian zones serve several ecological functions for bats. They provide a source of prey and likely provide favourable structural habitats and shelter from predators. Many studies have shown that bats use the space above streams, ponds or riparian vegetation as feeding habitat. These studies, however, have never distinguished between the effects of habitat structure and prey availability on the foraging activities of bats. Such effects can only be distinguished by an experimental approach. We predicted that bat activity along a stream is influenced by the number of emerged aquatic insects. 2. We evaluated the response of terrestrial consumers, insectivorous bats, to changes in the abundance of emergent aquatic insects by conducting a manipulative field experiment. In a deciduous riparian forest in Japan, aquatic insect flux from the stream to the riparian zone was controlled with an insect-proof cover over a 1.2 km stream reach. 3. We estimated the abundance of emergent aquatic and flying terrestrial arthropods near the treatment and control reaches using Malaise traps. The foraging activity of bats was evaluated in both treatment and control reaches using ultrasonic detectors. 4. The insect-proof cover effectively reduced the flux of emergent aquatic insects to the riparian zone adjacent to the treatment reach. Adjacent to the control reach, adult aquatic insect biomass was highest in spring, and then decreased gradually. Terrestrial insect biomass increased gradually during the summer at both treatment and control reaches. 5. Foraging activity of bats was correlated with insect abundance. In spring, foraging activity of bats at the control reach was significantly greater than at the treatment reach, and increased at both sites with increasing terrestrial insect abundance. 6. Our result suggests that the flux of aquatic insects emerging from streams is one of the most important factors affecting the distribution of riparian-foraging bats. As is the case with other riparian consumers, resource subsidies from streams can directly enhance the performance or population density of riparian-dependent bats. To conserve and manage bat populations, it is important to protect not only forest ecosystems, but also adjacent aquatic systems such as streams.

High power density proton exchange membrane fuel cells

NASA Technical Reports Server (NTRS)

Murphy, Oliver J.; Hitchens, G. Duncan; Manko, David J.

1993-01-01

Proton exchange membrane (PEM) fuel cells use a perfluorosulfonic acid solid polymer film as an electrolyte which simplifies water and electrolyte management. Their thin electrolyte layers give efficient systems of low weight, and their materials of construction show extremely long laboratory lifetimes. Their high reliability and their suitability for use in a microgravity environment makes them particularly attractive as a substitute for batteries in satellites utilizing high-power, high energy-density electrochemical energy storage systems. In this investigation, the Dow experimental PEM (XUS-13204.10) and unsupported high platinum loading electrodes yielded very high power densities, of the order of 2.5 W cm(exp -2). A platinum black loading of 5 mg per cm(exp 2) was found to be optimum. On extending the three-dimensional reaction zone of fuel cell electrodes by impregnating solid polymer electrolyte into the electrode structures, Nafion was found to give better performance than the Dow experimental PEM. The depth of penetration of the solid polymer electrolyte into electrode structures was 50-70 percent of the thickness of the platinum-catalyzed active layer. However, the degree of platinum utilization was only 16.6 percent and the roughness factor of a typical electrode was 274.

Development and validation of chemistry agnostic flow battery cost performance model and application to nonaqueous electrolyte systems: Chemistry agnostic flow battery cost performance model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crawford, Alasdair; Thomsen, Edwin; Reed, David

2016-04-20

A chemistry agnostic cost performance model is described for a nonaqueous flow battery. The model predicts flow battery performance by estimating the active reaction zone thickness at each electrode as a function of current density, state of charge, and flow rate using measured data for electrode kinetics, electrolyte conductivity, and electrode-specific surface area. Validation of the model is conducted using a 4kW stack data at various current densities and flow rates. This model is used to estimate the performance of a nonaqueous flow battery with electrode and electrolyte properties used from the literature. The optimized cost for this system ismore » estimated for various power and energy levels using component costs provided by vendors. The model allows optimization of design parameters such as electrode thickness, area, flow path design, and operating parameters such as power density, flow rate, and operating SOC range for various application duty cycles. A parametric analysis is done to identify components and electrode/electrolyte properties with the highest impact on system cost for various application durations. A pathway to 100$kWh -1 for the storage system is identified.« less

ELKS active zone proteins as multitasking scaffolds for secretion

PubMed Central

Held, Richard G.

2018-01-01

Synaptic vesicle exocytosis relies on the tethering of release ready vesicles close to voltage-gated Ca2+ channels and specific lipids at the future site of fusion. This enables rapid and efficient neurotransmitter secretion during presynaptic depolarization by an action potential. Extensive research has revealed that this tethering is mediated by an active zone, a protein dense structure that is attached to the presynaptic plasma membrane and opposed to postsynaptic receptors. Although roles of individual active zone proteins in exocytosis are in part understood, the molecular mechanisms that hold the protein scaffold at the active zone together and link it to the presynaptic plasma membrane have remained unknown. This is largely due to redundancy within and across scaffolding protein families at the active zone. Recent studies, however, have uncovered that ELKS proteins, also called ERC, Rab6IP2 or CAST, act as active zone scaffolds redundant with RIMs. This redundancy has led to diverse synaptic phenotypes in studies of ELKS knockout mice, perhaps because different synapses rely to a variable extent on scaffolding redundancy. In this review, we first evaluate the need for presynaptic scaffolding, and we then discuss how the diverse synaptic and non-synaptic functional roles of ELKS support the hypothesis that ELKS provides molecular scaffolding for organizing vesicle traffic at the presynaptic active zone and in other cellular compartments. PMID:29491150

Driver behavior and accident frequency in school zones: Assessing the impact of sign saturation.

PubMed

Strawderman, Lesley; Rahman, Md Mahmudur; Huang, Yunchen; Nandi, Apurba

2015-09-01

Based on the models of human information processing, if a driver observes too many of the same signs, he or she may no longer pay attention to those signs. In the case of school zones, this expected effect may lead to non-compliance to posted speeds, negatively impacting safety around nearby schools. This study aims to investigate the effect of the number of nearby school zones on driver behavior (vehicle speed and compliance) and accident frequency. As a measure of the density of school zones, this study introduced and defined a new term sign saturation and presented a methodology to calculate sign saturation for school zones. Results found a significant effect of sign saturation on vehicle speed, compliance, and accident frequency. This study also examined the speeding behavior in school zones for different time of the day and day of the week. Results found that speeding was more prevalent in the early mornings and during the weekends. Copyright © 2015 Elsevier Ltd. All rights reserved.

Geologic constraints on the setting and dynamics of subduction initiation

NASA Astrophysics Data System (ADS)

Encarnacion, John; Keenan, Timothy

2017-04-01

Understanding where and how subduction zones have and can initiate is important because, besides being a critical step in the plate tectonic system, it can provide insight into the complex interactions of crust and mantle rheology, forces acting on the plates, strain, metamorphic reactions, and erosional and depositional processes at the surface. Insight into the possibilities of where and how subduction zones start has been provided by numerical and analog modeling. All sites for subduction initiation are potential weak zones in the lithosphere and include the continent-ocean boundary, oceanic arc-oceanic crust boundary, oceanic transform faults and fracture zones, oceanic detachment faults, and active or recently extinct oceanic ridges/spreading centers. Within the constraints of modeling, it has also been shown that the forces involved in the initiation of subduction can be largely horizontal (induced by a collision, say, or through 'ridge push') or vertical (driven by density contrasts). The latter scenario is often referred to as "spontaneous" subduction initiation, whereas the former situation may be called "forced"or "induced" subduction initiation. It is prudent, however, not to assume that "what can happen, did happen." So, the challenge for geologists is to infer from the rock record, through structural mapping, thermochronology, thermobarometry, geochemistry, paleomagnetics, and sedimentological studies, how any given subduction zone began. Even with a complete data set, it is not always possible to fully constrain the specific geologic setting or dynamics involved in the initiation of a given subduction zone. One can, however, often rule out certain scenarios, increasing the probability of others. Part of the geologic record of subduction initiation preserved at some subduction zones are so-called "metamorphic soles," which include high-temperature (T) and high-pressure (P) metamorphosed oceanic crust that was underthrust to asthenospheric mantle depths, metamorphosed, and then preserved in the hanging wall of the eventual subduction zone. These metamorphic soles may preserve important information bearing on the timing of subduction initiation, the evolving P and T conditions during subduction initiation, and, importantly, the protolith age of the initially subducted crust. The latter parameter—the age of the initially subducted oceanic crust at the time of subduction initiation—is an important constraint that has been lacking in many previous geologic studies of subduction initiation. Recent work on metamorphic soles has provided new information on subduction initiation, including the possibility of rapidly converting oceanic divergent boundaries into subduction zones.

Continental land cover classification using meteorological satellite data

NASA Technical Reports Server (NTRS)

Tucker, C. J.; Townshend, J. R. G.; Goff, T. E.

1983-01-01

The use of the National Oceanic and Atmospheric Administration's advanced very high resolution radiometer satellite data for classifying land cover and monitoring of vegetation dynamics over an extremely large area is demonstrated for the continent of Africa. Data from 17 imaging periods of 21 consecutive days each were composited by a technique sensitive to the in situ green-leaf biomass to provide cloud-free imagery for the whole continent. Virtually cloud-free images were obtainable even for equatorial areas. Seasonal variation in the density and extent of green leaf vegetation corresponded to the patterns of rainfall associated with the inter-tropical convergence zone. Regional variations, such as the 1982 drought in east Africa, were also observed. Integration of the weekly satellite data with respect to time produced a remotely sensed assessment of biological activity based upon density and duration of green-leaf biomass. Two of the 21-day composited data sets were used to produce a general land cover classification. The resultant land cover distributions correspond well to those of existing maps.

Low-energy plasma observations at synchronous orbit

NASA Technical Reports Server (NTRS)

Lennartsson, W.; Reasoner, D. L.

1978-01-01

The University of California at San Diego Auroral Particles Experiment on the ATS 6 satellite in synchronous orbit has detected a low-energy plasma population which is separate and distinct from both the ring current and the plasma sheet populations. The density and temperature of this low-energy population are highly variable, with temperatures in the range kT = 1-30 eV and densities ranging from less than 1 per cu cm to more than 10 per cu cm. The occurrence of a dense low-energy plasma is most likely in the afternoon and dusk local time sectors, whereas n greater than 1 per cu cm is seen in the local night sector only during magnetically quiet periods. These observations suggest that this plasma is the outer zone of the plasmasphere. During magnetically active periods this low-energy plasma is often observed flowing sunward. In the dusk sector, strong sunward plasma flow is often observed for 1-2 hours prior to the onset of a substorm-associated particle injection.

Investigation of phase synchronization of interictal EEG in right temporal lobe epilepsy

NASA Astrophysics Data System (ADS)

Yu, Haitao; Cai, Lihui; Wu, Xinyu; Song, Zhenxi; Wang, Jiang; Xia, Zijie; Liu, Jing; Cao, Yibin

2018-02-01

Epilepsy is commonly associated with abnormally synchronous activity of neurons located in epileptogenic zones. In this study, we investigated the synchronization characteristic of right temporal lobe epilepsy (RTLE). Multichannel electroencephalography (EEG) data were recorded from the RTLE patients during interictal period and normal controls. Power spectral density was first used to analyze the EEG power for two groups of subjects. It was found that the power of epileptics is increased in the whole brain compared with that of the control. We calculated phase lag index (PLI) to measure the phase synchronization between each pair of EEG signals. A higher degree of synchronization was observed in the epileptics especially between distant channels. In particular, the regional synchronization degree was negatively correlated with power spectral density and the correlation was weaker for epileptics. Moreover, the synchronization degree decayed with the increase of relative distance of channels for both the epilepsy and control, but the dependence was weakened in the former. The obtained results may provide new insights into the generation mechanism of epilepsy.

Pentacene Schottky diodes studied by impedance spectroscopy: Doping properties and trap response

NASA Astrophysics Data System (ADS)

Pahner, Paul; Kleemann, Hans; Burtone, Lorenzo; Tietze, Max L.; Fischer, Janine; Leo, Karl; Lüssem, Björn

2013-11-01

We study doping properties and charge carrier trap distributions in pentacene Schottky diodes doped by the fluorinated fullerene derivate C60F36 and 2,2'-(perdiylidene)dimalononitrile (F6-TCNNQ) upon small signal excitation. We show that the charge carrier depletion zones present in these Schottky diodes are tunable by the applied bias and temperature. Mott-Schottky evaluations yield reduced doping efficiencies and dopant activation energies between 19 and 54 meV. In the low-frequency regime, we resolve additional capacitive contributions from inherent charge carrier traps. A Gaussian distributed trap center 0.6 eV above the hole transport level with a density in the range of 1016 cm-3 depending on the material purity is found to be an intrinsic feature of the pentacene matrix. Upon doping, the deep Gaussian trap center saturates in density and broad exponentially tailing trap distributions arise. Subsequent ultraviolet photoelectron spectroscopy measurements are conducted to inspect for energetic broadening due to doping.

Application of indexes of underground structure using land gravity data to the Eastern Boundary Fault zone of the Shonai Plain, northeastern Japan.

NASA Astrophysics Data System (ADS)

Tanaka, T.; Hiramatsu, Y.; Matsumoto, N.; Honda, R.; Wada, S.; Sawada, A.; Okada, S.

2016-12-01

Gravity gradients, which are directly measured and are also derived by differentiating land gravity anomaly data, are sensitive to the density structure of shallow subsurfaces and therefore can be used to formulate ratings for Indexes of Underground Structure (IUS) [e.g., Kusumoto,2015,2016]. Recently, dense land gravity data measurements for almost entire Japan have been available [Honda et al., 2012]. In this study, we use gravity gradient tensors from the data to apply IUS to the Eastern Boundary Fault zone of the Shonai Plain (EBFSP), which spans 40 km in length and caused the historical Mjma 7.0 earthquake in 1894. The IUS we adopt here comprises the dip angle of the structural boundary (Beta) [Beiki, 2013], the dimensionality index (I) [Pedersen and Rasmussen, 1990], the structural boundary (Horizontal First Derivation(HFD) and TDX [Cooper and Cowan, 2006]), and density anomaly cylinder bodies in the depth direction (TD) [Copper, 2011]. The IUS show that the northern part of the EBFSP is characterized by high-Beta, low-I (dyke-like), intense-(HFD and TDX), and many short TD. Contrary to this, the southern part exhibits low-Beta, high-I, mild-(HFD and TDX), and few long TD. Previous geological/geomorphological surveys of the EBFSP [Ikeda et al., 2002] distinguish between the northern part comprising parallel/echelon short faults and the southern part comprising a single long fault. These findings are consistent with the gravimetrical IUS. However, the IUS more emphasizes the Aosawa Fault zone, which is geologically old and runs nearly parallel to the EBFSP at about 5-10 km distance on the eastern side of the EBFSP. Because gravity anomalies are a time-integrated representation of crustal activity, it is difficult to identify the relative timing of faulting events in an analysis range. However, the IUS can objectively contribute to producing comprehensive characterizations of target faults. This study is supported by JSPS KAKENHI Grant Number 26400450.

Geophysics in Mejillones Basin, Chile: Dynamic analysis and associatedseismic hazard

NASA Astrophysics Data System (ADS)

Maringue, J. I.; Yanez, G. A.; Lira, E.; Podestá, L., Sr.; Figueroa, R.; Estay, N. P.; Saez, E.

2016-12-01

The active margin of South America has a high seismogenic potential. In particular, the Mejillones peninsula, located in northern Chile, represents a site of interest for seismic hazard due to 100-year seismic gap, the potentially large site effects, and the presence of the most important port in the region. We perform a dynamic analysis of the zone from a spatial and petrophysical model of the Mejillones Basin, to understand its behavior under realistic seismic scenarios. Geometry and petrophysics of the basin were obtained from an integrated modeling of geophysics observations (gravity, seismic and electromagnetic data) distributed mainly in Pampa Mejillones whose western edge is limited by Mejillones Fault, oriented north-south. This regional-scale normal fault shows a half-graben geometry which controls the development of the Mejillones basin eastwards. The gravimetric and magnetotelluric methods allow to define the geometry of the basin, through a cover/basement density contrast, and the transition zone from very low-moderate electrical resistivities, respectively. The seismic method complements the petrophysics in terms of the shear wave depth profile. The results show soil's thicknesses up to 700 meters on deeper zone, with steeper slopes to the west and lower slopes to the east, in agreement with the normal-fault-half-graben basin geometry. Along the N-S direction there are not great differences in basin depth, comprising an almost 2D problem. In terms of petrophysics, the sedimentary stratum is characterized by shear velocities between 300-700 m/s, extremely low electrical resistivities, below 1 ohm-m, and densities from 1.4 to 1.8 gr/cc. The numerical simulation of the seismic waves amplification gives values in the order of 0.8g, which implying large surface damages. The results demonstrate a potential risk in Mejillones bay to future events, therefore is very important to generate mitigations policies for infrastructure and human settlements.

Spectral Decomposition and Other Seismic Attributes for Gas Hydrate Prospecting

DOE Office of Scientific and Technical Information (OSTI.GOV)

McConnell, Dan

Studying the sediments at the base of gas hydrate stability is ideal for determining the seismic response to gas hydrate saturation. First, assuming gas migration to the shallow section, this area is more likely to have concentrated gas hydrate because it encompasses the zone in which upward moving buoyant gas transitions to form immobile gas hydrate deposits. Second, this zone is interesting because these areas have the potential to show a hydrate filled zone and a gas filled zone within the same sediments. Third, the fundamental measurement within seismic data is impedance contrasts between velocity*density layers. High saturation gas hydratesmore » and free gas inhabit opposite ends of these measurements making the study of this zone ideal for investigating the seismic characteristics of gas hydrate and, hence, the investigation of other seismic attributes that may indicate gas hydrate fill.« less

The impact of habitat fragmentation on tsetse abundance on the plateau of eastern Zambia.

PubMed

Ducheyne, E; Mweempwa, C; De Pus, C; Vernieuwe, H; De Deken, R; Hendrickx, G; Van den Bossche, P

2009-09-01

Tsetse-transmitted human or livestock trypanosomiasis is one of the major constraints to rural development in sub-Saharan Africa. The epidemiology of the disease is determined largely by tsetse fly density. A major factor, contributing to tsetse population density is the availability of suitable habitat. In large parts of Africa, encroachment of people and their livestock resulted in a destruction and fragmentation of such suitable habitat. To determine the effect of habitat change on tsetse density a study was initiated in a tsetse-infested zone of eastern Zambia. The study area represents a gradient of habitat change, starting from a zone with high levels of habitat destruction and ending in an area where livestock and people are almost absent. To determine the distribution and density of the fly, tsetse surveys were conducted throughout the study area in the dry and in the rainy season. Landsat ETM+ imagery covering the study area were classified into four land cover classes (munga, miombo, agriculture and settlements) and two auxiliary spectral classes (clouds and shadow) using a Gaussian Maximum Likelihood Classifier. The classes were regrouped into natural vegetation and agricultural zone. The binary images were overlaid with hexagons to obtain the spatial spectrum of spatial pattern. Hexagonal coverage was selected because of its compact and regular form. To identify scale-specific spatial patterns and associated entomological phenomena, the size of the hexagonal coverage was varied (250 and 500 m). Per coverage, total class area, mean patch size, number of patches and patch size standard deviation were used as fragmentation indices. Based on the fragmentation index values, the study zone was classified using a Partitioning Around Mediods (PAM) method. The number of classes was determined using the Wilks' lambda coefficient. To determine the impact of habitat fragmentation on tsetse abundance, the correlation between the fragmentation indices and the index of apparent density of the flies was determined and habitat changes most affecting tsetse abundance was identified. From this it followed that there is a clear relationship between habitat fragmentation and the abundance of tsetse flies. Heavily fragmented areas have lower numbers of tsetse flies, but when the fragmentation of natural vegetation decreases, the number of tsetse flies increases following a sigmoidal-like curve.

Comparative study of two active faults in different stages of the earthquake cycle in central Japan -The Atera fault (with 1586 Tensho earthquake) and the Nojima fault (with 1995 Kobe earthquake)-

NASA Astrophysics Data System (ADS)

Matsuda, T.; Omura, K.; Ikeda, R.

2003-12-01

National Research Institute for Earth Science and Disaster Prevention (NIED) has been conducting _gFault zone drilling_h. Fault zone drilling is especially important in understanding the structure, composition, and physical properties of an active fault. In the Chubu district of central Japan, large active faults such as the Atotsugawa (with 1858 Hietsu earthquake) and the Atera (with 1586 Tensho earthquake) faults exist. After the occurrence of the 1995 Kobe earthquake, it has been widely recognized that direct measurements in fault zones by drilling. This time, we describe about the Atera fault and the Nojima fault. Because, these two faults are similar in geological situation (mostly composed of granitic rocks), so it is easy to do comparative study of drilling investigation. The features of the Atera fault, which have been dislocated by the 1586 Tensho earthquake, are as follows. Total length is about 70 km. That general trend is NW45 degree with a left-lateral strike slip. Slip rate is estimated as 3-5 m / 1000 years. Seismicity is very low at present and lithologies around the fault are basically granitic rocks and rhyolite. Six boreholes have been drilled from the depth of 400 m to 630 m. Four of these boreholes (Hatajiri, Fukuoka, Ueno and Kawaue) are located on a line crossing in a direction perpendicular to the Atera fault. In the Kawaue well, mostly fractured and alternating granitic rock continued from the surface to the bottom at 630 m. X-ray fluorescence analysis (XRF) is conducted to estimate the amount of major chemical elements using the glass bead method for core samples. The amounts of H20+ are about from 0.5 to 2.5 weight percent. This fractured zone is also characterized by the logging data such as low resistivity, low P-wave velocity, low density and high neutron porosity. The 1995 Kobe (Hyogo-ken Nanbu) earthquake occurred along the NE-SW-trending Rokko-Awaji fault system, and the Nojima fault appeared on the surface on Awaji Island when this rupture occurred. It is more than 10 km long with 1-2 m offset along the Nojima fault. About one year after the earthquake, NIED drilled a borehole (the Hirabayashi NIED borehole) and penetrated the Nojima fault. The Hirabayashi NIED borehole was drilled to a depth of 1838 m and recovered the drill core. The main types of rock intersected by the borehole are granodiorite and cataclastic fault rocks. Three fracture zones were recognized in cores at approximate depth of 1140 m, 1300 m and 1800 m. There is remarkable foliated blue-gray gouge at a depth of 1140 m. We investigate chemical compositions by XRF analysis in the fracture zone. The amounts of H20+ are about from 1.0 to 15.0 weight percent. We investigate mineral assemblage in both drilling cores by X-ray powder diffraction analysis. From the results, we can_ft recognize so difference between the two faults. But the amount of H2O+ is very different. In the Hirabayashi NIED core at a depth of 1140 m, there is about ten times as much as the average of the Kawaue core. This is probably due to the greater degree of wall-rock fracturing in the fracture zone. We suggest that this characteristic is associated with the fault activity at the time of the 1995 Kobe earthquake and the nature of fluid-rock interactions in the fracture zone.

Evidence for Seismic and Aseismic Slip along a Foreland Thrust Fault, Southern Appalachians

NASA Astrophysics Data System (ADS)

Newman, J.; Wells, R. K.; Holyoke, C. W.; Wojtal, S. F.

2013-12-01

Studies of deformation along ancient thrust faults form the basis for much of our fundamental understanding of fault and shear zone processes. These classic studies interpreted meso- and microstructures as formed during aseismic creep. Recent experimental studies, and studies of naturally deformed rocks in seismically active regions, reveal similar microstructures to those observed locally in a carbonate foreland thrust from the southern Appalachians, suggesting that this thrust fault preserves evidence of both seismic and aseismic deformation. The Copper Creek thrust, TN, accommodated 15-20 km displacement, at depths of 4-6 km, as estimated from balanced cross-sections. At the Diggs Gap exposure of the Copper Creek thrust, an approximately 2 cm thick, vein-like shear zone separates shale layers in the hanging wall and footwall. The shear zone is composed of anastomosing layers of ultrafine-grained calcite and/or shale as well as aggregate clasts of ultrafine-grained calcite or shale. The boundary between the shear zone and the hanging wall is sharp, with slickensides along the boundary, parallel to the shear zone movement direction. A 350 μm-thick layer of ultrafine-grained calcite separates the shear zone and the footwall. Fault parallel and perpendicular calcite veins are common in the footwall and increase in density towards the shear zone. Microstructures within the vein-like shear zone that are similar to those observed in experimental studies of unstable slip include: ultrafine-grained calcite (~0.34 μm), nano-aggregate clasts (100-300 nm), injection structures, and vein-wrapped and matrix-wrapped clasts. Not all structures within the shear zone and ultrafine-grained calcite layer suggest seismic slip. Within the footwall veins and calcite aggregate clasts within the shear zone, pores at twin-twin intersections suggest plasticity-induced fracturing as the main mechanism for grain size reduction. Interpenetrating grain boundaries in ultrafine-grained calcite and a lack of a lattice preferred orientation suggest ultrafine-grained calcite deformed by diffusion creep accommodated grain boundary sliding. These structures suggest a strain-rate between 10-15 - 10-11 s-1, using calcite flow laws at temperatures 150-250 °C. Microstructures suggest both seismic and aseismic slip along this ancient fault zone. During periods of aseismic slip, deformation is accommodated by plasticity-induced fracturing and diffusion creep. Calcite veins suggest an increase in pore-fluid pressure, contributing to fluidized and unstable flow, but also providing the calcite that deformed by diffusion creep during aseismic creep.

FORMATION OF INTRACYTOPLASMIC MEMBRANE SYSTEM OF MYCOBACTERIA RELATED TO CELL DIVISION

PubMed Central

Imaeda, Tamotsu; Ogura, Mituo

1963-01-01

Imaeda, Tamotsu (Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela) and Mitua Ogura. Formation of intracytoplasmic membrane system of mycobacteria related to cell division. J. Bacteriol. 85:150–163. 1963.—Mycobacterium leprae, M. lepraemurium, and a Mycobacterium sp. were observed with an electron microscope. In these bacilli, the three-dimensional structure of the intracytoplasmic membrane system consists of tubular infoldings of the invaginated plasma membrane. The moderately dense substance, presumably representing the cell-wall precursor, is found in the membranous system, especially in the rapid growth phase of mycobacteria. This system always shows an intimate relationship with cell division. A low-density zone, probably corresponding to the low-density substance which coats the cell wall, appears in the connecting regions of the system and in the longitudinal portion of the cell wall. These zones extend centripetally, and the separation of the cell wall occurs after the two zones meet. Based on these results, we hypothesize that the intracytoplasmic membrane system may produce cell-wall material during cell division of mycobacteria. Images PMID:13956365

Low-Cost HTS Based Magnet System with an Inductively Coupled Pulsed Energy Extraction Protection System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agustsson, Ronald

In this project, RadiaBeam Technologies was tasked with developing a novel solution for a cost effective quench protection based on fast expansion of the normal zone. By inductively coupling a strong electromagnetic pulse via a resonant LC circuit, we attempted to demonstrate accelerated normal zone propagation. The AC field induces currents in the superconducting layer with the current density exceeding that of the critical current density, J c. This creates a large normal zone, uniformly distributing the dissipation through the magnet body. The method does not rely on thermal heating of the conductor, thus enabling nearly instantaneous protection. Through themore » course of the Phase II project, RadiaBeam Technologies continued extensive numerical modeling of the inductive quench system, re-designed and built several iterations of the POC system for testing and observed evidence of a transient partial quench being induced. However the final device was not fabricated. This was a consequence of the fundamentally complex nature of the energy extraction process and the challenges associated even with demonstrating the proof of concept in a bench top device.« less

Variable residence time vortex combustor

DOEpatents

Melconian, Jerry O.

1987-01-01

A variable residence time vortex combustor including a primary combustion chamber for containing a combustion vortex, and a plurality of louvres peripherally disposed about the primary combustion chamber and longitudinally distributed along its primary axis. The louvres are inclined to impel air about the primary combustion chamber to cool its interior surfaces and to impel air inwardly to assist in driving the combustion vortex in a first rotational direction and to feed combustion in the primary combustion chamber. The vortex combustor also includes a second combustion chamber having a secondary zone and a narrowed waist region in the primary combustion chamber interconnecting the output of the primary combustion chamber with the secondary zone for passing only lower density particles and trapping higher density particles in the combustion vortex in the primary combustion chamber for substantial combustion.

78 FR 7395 - Foreign-Trade Zone 129-Bellingham, WA; Notification of Proposed Production Activity; T.C. Trading...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-01

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-8-2013] Foreign-Trade Zone 129--Bellingham, WA; Notification of Proposed Production Activity; T.C. Trading Company, Inc. (Eyeglass Assembly and Kitting... activity on behalf of T.C. Trading Company, Inc. (T.C. Trading), located in Blaine, Washington. The...

77 FR 72816 - Foreign-Trade Zone 20-Suffolk, VA; Authorization of Production Activity; Usui International...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-06

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-53-2012] Foreign-Trade Zone 20--Suffolk, VA; Authorization of Production Activity; Usui International Corporation (Diesel Engine Fuel Lines); Chesapeake, VA On June 28, 2012, the Virginia Port Authority, grantee of FTZ 20, submitted a notification of proposed production activity to the...

77 FR 75406 - Foreign-Trade Zone 26-Atlanta, GA; Notification of Proposed Production Activity; Perkins Shibaura...

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2012-12-20

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-90-2012] Foreign-Trade Zone 26--Atlanta, GA; Notification of Proposed Production Activity; Perkins Shibaura Engines LLC, (Diesel Engines), Griffin, GA Perkins Shibaura Engines LLC (Perkins Shibaura), an operator of FTZ 26, submitted a notification of proposed production activity for its facilit...

77 FR 48127 - Foreign-Trade Zone 20-Suffolk, VA; Notification of Proposed Production Activity, Usui...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-13

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-53-2012] Foreign-Trade Zone 20--Suffolk, VA; Notification of Proposed Production Activity, Usui International Corporation, (Diesel Engine Fuel Lines), Chesapeake, VA The Virginia Port Authority, grantee of FTZ 20, submitted a notification of proposed production activity on behalf of Usui...

78 FR 41911 - Foreign-Trade Zone 161-Sedgwick County, Kansas; Authorization of Production Activity; Siemens...

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2013-07-12

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-27-2013] Foreign-Trade Zone 161--Sedgwick County, Kansas; Authorization of Production Activity; Siemens Energy, Inc. (Wind Turbine Nacelles and Hubs); Hutchinson, Kansas On March 7, 2013, Siemens Energy, Inc., an operator of FTZ 161, submitted a notification of proposed production activity to...

78 FR 48413 - Foreign-Trade Zone 75-Phoenix, Arizona, Authorization of Production Activity, Orbital Sciences...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-08

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-33-2013] Foreign-Trade Zone 75--Phoenix, Arizona, Authorization of Production Activity, Orbital Sciences Corporation, (Satellites and Spacecraft Launch Vehicles); Gilbert, Arizona On April 2, 2013, the City of Phoenix, grantee of FTZ 75, submitted a notification of proposed production activity...

Implications of a localized zone of seismic activity near the Inner Piedmont-Blue Ridge boundary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Douglas, S.; Powell, C.

1994-03-01

A small but distinct cluster of earthquake activity is located in Henderson County, NC, near the boundary of the Inner Piedmont and Blue Ridge physiographic provinces. Over twenty events have occurred within the cluster since 1776 and four had body-wave magnitudes exceeding 3.0. Average focal depth for instrumentally recorded events is 7.7 km. Epicenters plot within the Inner Piedmont, roughly 13 km from the surface expression of the Brevard fault zone. The reason for sustained earthquake activity in Henderson County is not known but the close spatial association of the events with the Brevard fault suggests a causal relationship. Themore » Brevard zone dips steeply to the SE and the events could be associated with the fault at depth. An even more intriguing possibility is that the events are associated with the intersection of the Brevard zone and the decollemont; this possibility is compatible with available information concerning the depth to the decollemont and the dip on the Brevard zone. An association of seismic activity with the Brevard zone at depth is supported by the presence of another small cluster of activity located in Rutherford County, NC. This cluster is located in the Inner Piedmont, roughly 30 km NE of the Henderson cluster and 16 km from the Brevard fault zone. Association of seismic activity with known faults is very rare in the eastern US and has implications for tectonic models and hazard evaluation. Additional research must be conducted to determine the feasibility that activity is associated with the Brevard zone.« less

Architectural and microstructural characterization of a seismogenic normal fault in dolostones (Central Apennines, Italy)

NASA Astrophysics Data System (ADS)

Demurtas, Matteo; Fondriest, Michele; Clemenzi, Luca; Balsamo, Fabrizio; Storti, Fabrizio; Di Toro, Giulio

2015-04-01

Fault zones cutting carbonate sequences represent significant seismogenic sources worldwide (e.g. L'Aquila 2009, MW 6.1). Though seismological and geophysical techniques (double differences method, trapped waves, etc.) allow us to investigate down to the decametric scale the structure of active fault zones, further geological field surveys and microstructural studies of exhumed seismogenic fault zones are required to support interpretation of geophysical data, quantify the geometry of fault zones and identify the fault processes active during the seismic cycle. Here we describe the architecture (i.e. fault geometry and fault rock distribution) of the well-exposed footwall-block of the Campo Imperatore Fault Zone (CIFZ) by means of remote sensed analyses, field surveys, mineralogical (XRD, micro-Raman spectroscopy) and microstructural (FE-SEM, optical microscope cathodoluminescence) investigations. The CIFZ dips 58° towards N210 and its strike mimics that of the arcuate Gran Sasso Thrust Belt (Central Apennines). The CIFZ was exhumed from 2-3 km depth and accommodated a normal throw of ~2 km starting from the Early-Pleistocene. In the studied area, the CIFZ puts in contact the Holocene deposits at the hangingwall with dolomitized Jurassic carbonate platform successions (Calcare Massiccio) at the footwall. From remote sensed analyses, structural lineaments both inside and outside the CIFZ have a typical NW-SE Apenninic strike, which is parallel to the local trend of the Gran Sasso Thrust. Based on the density of the fracture/fault network and the type of fault zone rocks, we distinguished four main structural domains within the ~300 m thick CIFZ footwall-block, which include (i) a well-cemented (white in color) cataclastic zone (up to ~40 m thick) at the contact with the Holocene deposits, (ii) a well-cemented (brown to grey in color) breccia zone (up to ~15 m thick), (iii) an high strain damage zone (fracture spacing < 2-3 cm), and (iv) a low strain damage zone (fracture spacing > 10 cm). Other than by the main boundary normal fault, slip was accommodated in the cataclastic zone by minor sub-parallel synthetic and antithetic normal faults and by few tear strike-slip fault; the rest of the footwall shows progressively less pervasive damage down to the background intensity of deformation. High strain domains include (1) pervasively fragmented dolostones with radial fractures (evidence of in-situ shattering), (2) shiny (mirror-like) fault surfaces truncating dolostone clasts, (3) mm-thick ultra-cataclastic layers with lobate and cuspate boundaries, (4) mixed calcite-dolomite "foliated cataclasites". The above microstructures can be associated with seismic faulting. Fluids infiltration during deformation is attested by the occurrence of multiple generations of carbonate-filled veins, often exploited as minor faults with a mylonite-like fabric (e.g. presence of micrometer in size euhedral calcite grains). The attitude of the studied segment of the CIFZ, the thickness of the footwall block and the kinematics of the minor faults compares well with the hypocentral and focal mechanisms distribution typical of the earthquake sequences in the Apennines. In particular, the CIFZ can be considered as an exhumed analogue of the normal fault system that caused the L'Aquila 2009 seismic sequence.

Holocene phreatomagmatic eruptions alongside the densely populated northern shoreline of Lake Kivu, East African Rift: timing and hazard implications

NASA Astrophysics Data System (ADS)

Poppe, Sam; Smets, Benoît; Fontijn, Karen; Rukeza, Montfort Bagalwa; De Marie Fikiri Migabo, Antoine; Milungu, Albert Kyambikwa; Namogo, Didier Birimwiragi; Kervyn, François; Kervyn, Matthieu

2016-11-01

The Virunga Volcanic Province (VVP) represents the most active zone of volcanism in the western branch of the East African Rift System. While the VVP's two historically active volcanoes, Nyamulagira and Nyiragongo, have built scoria cones and lava flows in the adjacent lava fields, several small phreatomagmatic eruptive centers lie along Lake Kivu's northern shoreline, highlighting the potential for explosive magma-water interaction. Their presence in the densely urbanized Sake-Goma-Gisenyi area necessitates an assessment of their eruptive mechanisms and chronology. Some of these eruptive centers possess multiple vents, and depositional contacts suggest distinct eruptive phases within a single structure. Depositional facies range from polymict tuff breccia to tuff and loose lapilli, often impacted by blocks and volcanic bombs. Along with the presence of dilute pyroclastic density current (PDC) deposits, indicators of magma-water interaction include the presence of fine palagonitized ash, ash aggregates, cross-bedding, and ballistic impact sags. We estimate that at least 15 phreatomagmatic eruptions occurred in the Holocene, during which Lake Kivu rose to its current water level. Radiocarbon dates of five paleosols in the top of volcanic tuff deposits range between ˜2500 and ˜150 cal. year bp and suggest centennial- to millennial-scale recurrence of phreatomagmatic activity. A vast part of the currently urbanized zone on the northern shoreline of Lake Kivu was most likely impacted by products from phreatomagmatic activity, including PDC events, during the Late Holocene, highlighting the need to consider explosive magma-water interaction as a potential scenario in future risk assessments.

Visualization of Synchronous or Asynchronous Release of Single Synaptic Vesicle in Active-Zone-Like Membrane Formed on Neuroligin-Coated Glass Surface.

PubMed

Funahashi, Junichiro; Tanaka, Hiromitsu; Hirano, Tomoo

2018-01-01

Fast repetitive synaptic transmission depends on efficient exocytosis and retrieval of synaptic vesicles around a presynaptic active zone. However, the functional organization of an active zone and regulatory mechanisms of exocytosis, endocytosis and reconstruction of release-competent synaptic vesicles have not been fully elucidated. By developing a novel visualization method, we attempted to identify the location of exocytosis of a single synaptic vesicle within an active zone and examined movement of synaptic vesicle protein synaptophysin (Syp) after exocytosis. Using cultured hippocampal neurons, we induced formation of active-zone-like membranes (AZLMs) directly adjacent and parallel to a glass surface coated with neuroligin, and imaged Syp fused to super-ecliptic pHluorin (Syp-SEP) after its translocation to the plasma membrane from a synaptic vesicle using total internal reflection fluorescence microscopy (TIRFM). An AZLM showed characteristic molecular and functional properties of a presynaptic active zone. It contained active zone proteins, cytomatrix at the active zone-associated structural protein (CAST), Bassoon, Piccolo, Munc13 and RIM, and showed an increase in intracellular Ca 2+ concentration upon electrical stimulation. In addition, single-pulse stimulation sometimes induced a transient increase of Syp-SEP signal followed by lateral spread in an AZLM, which was considered to reflect an exocytosis event of a single synaptic vesicle. The diffusion coefficient of Syp-SEP on the presynaptic plasma membrane after the membrane fusion was estimated to be 0.17-0.19 μm 2 /s, suggesting that Syp-SEP diffused without significant obstruction. Synchronous exocytosis just after the electrical stimulation tended to occur at multiple restricted sites within an AZLM, whereas locations of asynchronous release occurring later after the stimulation tended to be more scattered.

Effect of soil compaction on the degradation and ecotoxicological impact of isoproturon

NASA Astrophysics Data System (ADS)

Mamy, L.; Vrignaud, P.; Cheviron, N.; Perreau, F.; Belkacem, M.; Brault, A.; Breuil, S.; Delarue, G.; Touton, I.; Chaplain, V.

2009-04-01

Soil is essentially a non-renewable resource which performs many functions and delivers services vital to human activities and ecosystems survival. However the capacity of soil to keep on fully performing its broad variety of crucial functions is damaged by several threats and, among them, chemical contamination by pesticides and compaction due to intensive agriculture practices. How these two threats could interact is largely unknown: compaction may modify the fate of pesticides in soil therefore their effects on the biological functioning of soil. The aim of this work was to study the effect of soil compaction on (1) the degradation of one herbicide, isoproturon (2) the ecotoxicological impact of this herbicide measured through two enzyme activities involved in C (beta-glucosidase) and N (urease) cycles in soil. Undisturbed soil cylinders were sampled in the 2-4 cm layer of La Cage experimental site (INRA, Versailles, France), under intensive agriculture practices. Several soil samples were prepared with different bulk density then treated with isoproturon (IPU). The samples were incubated at 18 ± 1°C in darkness for 63 days. At 0, 2, 7, 14, 28 and 63 days, the concentrations of isoproturon and of two of its main metabolites in soil (monodesmethyl-isoproturon, IPPMU; didesmethyl-isoproturon, IPPU), and the enzyme activities were measured. The results showed that there was no significant difference in IPU degradation under no and moderate soil compaction. IPU was less persistent in the highly compacted soil, but this soil had also higher humidity which is known to increase the degradation. Only one metabolite, IPPMU, was detected independently of the conditions of compaction. The compaction did not modify the effect of IPU on beta-glucosidase and urease activities in the long term, but microbial communities were probably the same in all the soil samples that were initially not compacted. The communities developed in durably compacted zones in the field are possibly different and modification in enzyme activities might be observed as a result. These first results seem to show that compaction did not modify the degradation and ecotoxicological impact of isoproturon in the soil. However, further studies should be performed using soil samples taken in different zones of compaction in the field, and taking into account the relation between bulk density and soil humidity.

Comparison of fast food consumption and dietary guideline practices for children and adolescents by clustering of fast food outlets around schools in the Gyeonggi area of Korea.

PubMed

Joo, Soonnam; Ju, Seyoung; Chang, Hyeja

2015-01-01

This study investigated the distribution density of fast food outlets around schools, and the relationship between dietary health of children and adolescents and the density of fast food outlets in Korea. A distribution map of fast food outlets was drawn by collecting information on 401 locations of 16 brands within a 15-minute walk (800 meter) of 342 elementary and secondary schools in Suwon, Hwaseong and Osan. A questionnaire was used to gather data on the dietary life of 243 sixth and eighth grade students at eight schools. Schools in the upper 20% and lower 20% of the fast food outlet distribution were classified as high-density and low-density groups, respectively. The practice rate of dietary guidelines published by the Health and Welfare Ministry and the fast food consumption pattern of children and adolescents from low and high density groups were determined. The number of schools with a fast food outlet within 200 meters or in the Green Food Zone around its location was 48 of 189 (25.4%) in Suwon and 14 of 153 (9.2%) in Hwaseong and Osan. Students in the low-density group visited fast food outlets less often than those in the high-density group (p<0.01). Dietary guideline practice scores for children did not show a significant difference between the two groups. The distribution map of fast food outlets within 200 meters of schools was useful for identifying the effectiveness of the Green Food Zone Act and nutrition education programs.

Effect of temporary open-air markets on the sound environment and acoustic perception based on the crowd density characteristics.

PubMed

Meng, Qi; Sun, Yang; Kang, Jian

2017-12-01

The sound environment and acoustic perception of open-air markets, which are very common in high-density urban open spaces, play important roles in terms of the urban soundscape. Based on objective and subjective measurements of a typical temporary open-air market in Harbin city, China, the effects of the temporary open-air market on the sound environment and acoustic perception were studied, considering different crowd densities. It was observed that a temporary open-air market without zoning increases the sound pressure level and subjective loudness by 2.4dBA and 0.21dBA, respectively, compared to the absence of a temporary market. Different from the sound pressure level and subjective loudness, the relationship between crowd density and the perceived acoustic comfort is parabolic. Regarding the effect of a temporary open-air market with different zones on the sound environment and acoustic perception, when the crowd densities were the same, subjective loudness in the fruit and vegetable sales area was always higher than in the food sales area and the clothing sales area. In terms of acoustic comfort, with an increase in crowd density, acoustic comfort in the fruit and vegetable sales area decreased, and acoustic comfort in the food sales area and the clothing sales area exhibited a parabolic change trend of increase followed by decrease. Overall, acoustic comfort can be effectively improved by better planning temporary open-air markets in high-density urban open spaces. Copyright © 2017 Elsevier B.V. All rights reserved.

Local seismicity preceding the March 14, 1979, Petatlan, Mexico Earthquake (Ms = 7.6)

NASA Astrophysics Data System (ADS)

Hsu, Vindell; Gettrust, Joseph F.; Helsley, Charles E.; Berg, Eduard

1983-05-01

Local seismicity surrounding the epicenter of the March 14, 1979, Petatlan, Mexico earthquake was monitored by a network of portable seismographs of the Hawaii Institute of Geophysics from 6 weeks before to 4 weeks after the main shock. Prior to the main shock, the recorded local seismic activity was shallow and restricted within the continental plate above the Benioff zone. The relocated main shock hypocenter also lay above the Benioff zone, suggesting an initial failure within the continental lithosphere. Four zones can be recognized that showed relatively higher seismic activity than the background. Activity within these zones has followed a number of moderate earthquakes that occurred before or after the initial deployment of the network. Three of these moderate earthquakes were near the Mexican coastline and occurred sequentially from southeast to northwest during the three months before the Petatlan earthquake. The Petatlan event occurred along the northwestern extension of this trend. We infer a possible connection between this observed earthquake migration pattern and the subduction of a fracture zone because the 200-km segment that includes the aftershock zones of the Petatlan earthquake and the three preceding moderate earthquakes matches the intersection of the southeastern limb of the Orozco Fracture Zone and the Middle America Trench. The Petatlan earthquake source region includes the region of the last of the three near-coast seismic activities (zone A). Earthquakes of zone A migrated toward the Petatlan main shock epicenter and were separated from it by an aseismic zone about 10 km wide. We designate this group of earthquakes as the foreshocks of the Petatlan earthquake. These foreshocks occurred within the continental lithosphere and their observed characteristics are interpreted as due to the high-stress environment before the main shock. Pre-main shock seismicity of the Petatlan earthquake source region shows a good correlation with the aftershocks in their spatial distribution. This suggests that an asperity existing along the Benioff zone may have affected both the pre-main shock activity in the continental lithosphere and the aftershocks along the Benioff zone. Although major thrust earthquakes at trenches occur along Benioff zones, in the present study we find little activity on this interplate boundary before the Petatlan earthquake. The overlying continental block, on the contrary, is very active seismically. Our data suggest that the activity is probably governed by the stress transmitted from below due to coupling between two plates and the heterogeneity within the continental lithosphere. The continental material is probably the more likely place for precursors.

A spatial approach for the epidemiology of antibiotic use and resistance in community-based studies: the emergence of urban clusters of Escherichia coli quinolone resistance in Sao Paulo, Brasil

PubMed Central

2011-01-01

Background Population antimicrobial use may influence resistance emergence. Resistance is an ecological phenomenon due to potential transmissibility. We investigated spatial and temporal patterns of ciprofloxacin (CIP) population consumption related to E. coli resistance emergence and dissemination in a major Brazilian city. A total of 4,372 urinary tract infection E. coli cases, with 723 CIP resistant, were identified in 2002 from two outpatient centres. Cases were address geocoded in a digital map. Raw CIP consumption data was transformed into usage density in DDDs by CIP selling points influence zones determination. A stochastic model coupled with a Geographical Information System was applied for relating resistance and usage density and for detecting city areas of high/low resistance risk. Results E. coli CIP resistant cluster emergence was detected and significantly related to usage density at a level of 5 to 9 CIP DDDs. There were clustered hot-spots and a significant global spatial variation in the residual resistance risk after allowing for usage density. Conclusions There were clustered hot-spots and a significant global spatial variation in the residual resistance risk after allowing for usage density. The usage density of 5-9 CIP DDDs per 1,000 inhabitants within the same influence zone was the resistance triggering level. This level led to E. coli resistance clustering, proving that individual resistance emergence and dissemination was affected by antimicrobial population consumption. PMID:21356088

Gravity modelling of the Hellenic subduction zone — a regional study

NASA Astrophysics Data System (ADS)

Casten, U.; Snopek, K.

2006-05-01

The Hellenic subduction zone is clearly expressed in the arc-shaped distribution of earthquake epicenters and gravity anomalies, which connect the Peloponnesos with Crete and Anatolia. In this region, oceanic crust of the African plate collides northward with continental crust of the Aegean microplate, which itself is pushed apart to the south-west by the Anatolian plate and, at the same time, is characterised by crustal extension. The result is an overall collision rate of up to 4 cm/year and a retreating subduction process. Recent passive and active seismic studies on and around Crete gave first, but not in all details consistent, structural results useful for supporting gravity modelling. This was undertaken with the aim of presenting the first 3D density structure of the entire subduction zone. Gravity interpretation was based on a Bouguer map, newly compiled using data from land, marine and satellite sources. The anomalies range from + 170 mGal (Cretan Sea) to - 10 mGal (Mediterranean Ridge). 3D gravity modelling was done applying the modelling software IGMAS. The computed Bouguer map fits the low frequency part of the observed one, which is controlled by variations in Moho depth (less than 20 km below the Cretan Sea and extending 30 km below Crete) and the extremely thick sedimentary cover (partly up to 18 km) of the Mediterranean Ridge. The southernmost edge of the Eurasian plate, with its more triangular-shaped backstop area, was traced south off Crete. Only 50 to 100 km further to the south, the edge of the African continent was traced as well. In between these boundaries there is African oceanic crust, which has a clear arc-shaped detachment line situated at the Eurasian continental edge. The subduction arc is open towards the north, its slab separates hotter mantle material (lower density) below the updoming Moho of the Cretan Sea from colder one (higher density) in the south. Subjacent to the upper continental crust of Crete is a thickened layer of lower crust followed by the subducted oceanic crust with some mantle material as intermediate layer. The depth of the oceanic Moho below Crete is 50 km. The presence and structure of subducted or underplated sediments remains uncertain.

Ecosystem services response to urbanization in metropolitan areas: Thresholds identification.

PubMed

Peng, Jian; Tian, Lu; Liu, Yanxu; Zhao, Mingyue; Hu, Yi'na; Wu, Jiansheng

2017-12-31

Ecosystem service is the key comprehensive indicator for measuring the ecological effects of urbanization. Although various studies have found a causal relationship between urbanization and ecosystem services degradation, the linear or non-linear characteristics are still unclear, especially identifying the impact thresholds in this relationship. This study quantified four ecosystem services (i.e. soil conservation, carbon sequestration and oxygen production, water yield, and food production) and total ecosystem services (TES), and then identified multiple advantageous area of ecosystem services in the peri-urban area of Beijing City. Using piecewise linear regression, the response of TES to urbanization (i.e., population density, GDP density, and construction land proportion) and its thresholds were detected. The results showed that, the TES was high in the north and west and low in the southeast, and there were seven multiple advantageous areas (distributed in the new urban development zone and ecological conservation zone), one single advantageous area (distributed in the ecological conservation zone), and six disadvantageous areas (mainly distributed in the urban function extended zone). TES response to population and economic urbanization each had a threshold (229personkm -2 and 107.15millionyuankm -2 , respectively), above which TES decreased rapidly with intensifying urbanization. However, there was a negative linear relationship between land urbanization and TES, which indicated that the impact of land urbanization on ecosystem services was more direct and effective than that of population and economic urbanization. It was also found that the negative impact of urbanization on TES was highest in the urban function extended zone, followed in descending order by that in the new urban development zone and ecological conservation zone. According to the detected relationships between urbanization and TES, the economic and population urbanization should be strengthened accompanied by slowing or even reducing land urbanization, so as to achieve urban ecological sustainability with less ecosystem services degradation. Copyright © 2017 Elsevier B.V. All rights reserved.

Threatened by mining, polymetallic nodules are required to preserve abyssal epifauna

PubMed Central

Vanreusel, Ann; Hilario, Ana; Ribeiro, Pedro A.; Menot, Lenaick; Arbizu, Pedro Martínez

2016-01-01

Polymetallic nodule mining at abyssal depths in the Clarion Clipperton Fracture Zone (Eastern Central Pacific) will impact one of the most remote and least known environments on Earth. Since vast areas are being targeted by concession holders for future mining, large-scale effects of these activities are expected. Hence, insight into the fauna associated with nodules is crucial to support effective environmental management. In this study video surveys were used to compare the epifauna from sites with contrasting nodule coverage in four license areas. Results showed that epifaunal densities are more than two times higher at dense nodule coverage (>25 versus ≤10 individuals per 100 m2), and that taxa such as alcyonacean and antipatharian corals are virtually absent from nodule-free areas. Furthermore, surveys conducted along tracks from trawling or experimental mining simulations up to 37 years old, suggest that the removal of epifauna is almost complete and that its full recovery is slow. By highlighting the importance of nodules for the epifaunal biodiversity of this abyssal area, we urge for cautious consideration of the criteria for determining future preservation zones. PMID:27245847

Threatened by mining, polymetallic nodules are required to preserve abyssal epifauna.

PubMed

Vanreusel, Ann; Hilario, Ana; Ribeiro, Pedro A; Menot, Lenaick; Arbizu, Pedro Martínez

2016-06-01

Polymetallic nodule mining at abyssal depths in the Clarion Clipperton Fracture Zone (Eastern Central Pacific) will impact one of the most remote and least known environments on Earth. Since vast areas are being targeted by concession holders for future mining, large-scale effects of these activities are expected. Hence, insight into the fauna associated with nodules is crucial to support effective environmental management. In this study video surveys were used to compare the epifauna from sites with contrasting nodule coverage in four license areas. Results showed that epifaunal densities are more than two times higher at dense nodule coverage (>25 versus ≤10 individuals per 100 m(2)), and that taxa such as alcyonacean and antipatharian corals are virtually absent from nodule-free areas. Furthermore, surveys conducted along tracks from trawling or experimental mining simulations up to 37 years old, suggest that the removal of epifauna is almost complete and that its full recovery is slow. By highlighting the importance of nodules for the epifaunal biodiversity of this abyssal area, we urge for cautious consideration of the criteria for determining future preservation zones.

Three-Dimensional Innervation Zone Imaging from Multi-Channel Surface EMG Recordings.

PubMed

Liu, Yang; Ning, Yong; Li, Sheng; Zhou, Ping; Rymer, William Z; Zhang, Yingchun

2015-09-01

There is an unmet need to accurately identify the locations of innervation zones (IZs) of spastic muscles, so as to guide botulinum toxin (BTX) injections for the best clinical outcome. A novel 3D IZ imaging (3DIZI) approach was developed by combining the bioelectrical source imaging and surface electromyogram (EMG) decomposition methods to image the 3D distribution of IZs in the target muscles. Surface IZ locations of motor units (MUs), identified from the bipolar map of their MU action potentials (MUAPs) were employed as a prior knowledge in the 3DIZI approach to improve its imaging accuracy. The performance of the 3DIZI approach was first optimized and evaluated via a series of designed computer simulations, and then validated with the intramuscular EMG data, together with simultaneously recorded 128-channel surface EMG data from the biceps of two subjects. Both simulation and experimental validation results demonstrate the high performance of the 3DIZI approach in accurately reconstructing the distributions of IZs and the dynamic propagation of internal muscle activities in the biceps from high-density surface EMG recordings.

Structure of the southern Rio Grande rift from gravity interpretation

NASA Technical Reports Server (NTRS)

Daggett, P. H.; Keller, G. R.; Wen, C.-L.; Morgan, P.

1986-01-01

Regional Bouguer gravity anomalies in southern New Mexico have been analyzed by two-dimensional wave number filtering and poly-nomial trend surface analysis of the observed gravity field. A prominent, regional oval-shaped positive gravity anomaly was found to be associated with the southern Rio Grande rift. Computer modeling of three regional gravity profiles suggests that this anomaly is due to crustal thinning beneath the southern Rio Grande rift. These models indicate a 25 to 26-km minimum crustal thickness within the rift and suggest that the rift is underlain by a broad zone of anomalously low-density upper mantle. The southern terminus of the anomalous zone is approximately 50 km southwest of El Paso, Texas. A thinning of the rifted crust of 2-3 km relative to the adjacent Basin and Range province indicates an extension of about 9 percent during the formation of the modern southern Rio Grande rift. This extension estimate is consistent with estimates from other data sources. The crustal thinning and anomalous mantle is thought to result from magmatic activity related to surface volcanism and high heat flow in this area.

Gravity and magnetic anomaly modeling and correlation using the SPHERE program and Magsat data

NASA Technical Reports Server (NTRS)

Braile, L. W.; Hinze, W. J. (Principal Investigator); Vonfrese, R. R. B.

1980-01-01

The spherical Earth inversion, modeling, and contouring software were tested and modified for processing data in the Southern Hemisphere. Preliminary geologic/tectonic maps and selected cross sections for South and Central America and the Caribbean region are being compiled and as well as gravity and magnetic models for the major geological features of the area. A preliminary gravity model of the Andeas Beniff Zone was constructed so that the density columns east and west of the subducted plates are in approximate isostatic equilibrium. The magnetic anomaly for the corresponding magnetic model of the zone is being computed with the SPHERE program. A test tape containing global magnetic measurements was converted to a tape compatible with Purdue's CDC system. NOO data were screened for periods of high diurnal activity and reduced to anomaly form using the IGS-75 model. Magnetic intensity anomaly profiles were plotted on the conterminous U.S. map using the track lines as the anomaly base level. The transcontinental magnetic high seen in POGO and MAGSAT data is also represented in the NOO data.

THREE-DIMENSIONAL INNERVATION ZONE IMAGING FROM MULTI-CHANNEL SURFACE EMG RECORDINGS

PubMed Central

LIU, YANG; NING, YONG; LI, SHENG; ZHOU, PING; RYMER, WILLIAM Z.; ZHANG, YINGCHUN

2017-01-01

There is an unmet need to accurately identify the locations of innervation zones (IZs) of spastic muscles, so as to guide botulinum toxin (BTX) injections for the best clinical outcome. A novel 3-dimensional IZ imaging (3DIZI) approach was developed by combining the bioelectrical source imaging and surface electromyogram (EMG) decomposition methods to image the 3D distribution of IZs in the target muscles. Surface IZ locations of motor units (MUs), identified from the bipolar map of their motor unit action potentials (MUAPs) were employed as a prior knowledge in the 3DIZI approach to improve its imaging accuracy. The performance of the 3DIZI approach was first optimized and evaluated via a series of designed computer simulations, and then validated with the intramuscular EMG data, together with simultaneously recorded 128-channel surface EMG data from the biceps of two subjects. Both simulation and experimental validation results demonstrate the high performance of the 3DIZI approach in accurately reconstructing the distributions of IZs and the dynamic propagation of internal muscle activities in the biceps from high-density surface EMG recordings. PMID:26160432

Density fluctuation in HT-6M tokamak by CO2 laser scattering

NASA Astrophysics Data System (ADS)

Zeng, Lei; Cao, Jinxiang; Zhu, Guoliang; Ding, Weixing; Yu, Chang-Xuan; Zhang, Daqing; Li, Youyi

1993-09-01

The small scale density fluctuations in the interior of HT-6M Ohmic plasma have been studied by CO2 laser collective scattering system in deuterium discharges covering a wide range of nqa (chord-average density times safety factor at the limiter) and energy confinement time. The relative density fluctuation level in the interior is inversely proportional to the toroidal magnetic field and average density, and the energy confinement time (tau) E decreases with the fluctuation level increasing in the region where (tau) E linearly increases with nq0.5a and satisfies the Goldston scaling law. It is suggested that the microturbulence in the interior zone is responsible for anomalous transport in tokamaks.

Ionospheric density perturbations recorded by DEMETER above intense thunderstorms

NASA Astrophysics Data System (ADS)

Parrot, M.; Sauvaud, J. A.; Soula, S.; PinçOn, J. L.; Velde, O.

2013-08-01

(Detection of Electromagnetic Emissions Transmitted From Earthquake Regions) was a three-axis stabilized Earth-pointing spacecraft launched on 29 June 2004 into a low-altitude (710 km) polar and circular orbit that was subsequently lowered to 650 km until the end of the mission in December 2010. DEMETER measured electromagnetic waves all around the Earth, except in the auroral zones (invariant latitude >65°). The frequency range for the electric field was from DC up to 3.5 MHz, and for the magnetic field, it was from a few hertz up to 20 kHz. At its altitude, the phenomena observed on the E field and B field spectrograms recorded during nighttime by the satellite in the very low frequency range are mainly dominated by whistlers. In a first step, the more intense whistlers have been searched. They correspond to the most powerful lightning strokes occurring below DEMETER. Then, it is shown that this intense lightning activity is able to perturb the electron and ion densities at the satellite altitude (up to 133%) during nighttime. These intense lightning strokes are generally associated with transient luminous events, and one event with many sprites recorded on 17 November 2006 above Europe is reported. Examining the charged particle precipitation, it is shown that this density enhancement in the high ionosphere can be related to the energetic particle precipitation induced by the strong whistlers emitted during a long-duration thunderstorm activity at the same location.

Investigation with an Interferometer of the Turbulent Mixing of a Free Supersonic Jet

NASA Technical Reports Server (NTRS)

Gooderum, Paul B; Wood, George P; Brevoort, Maurice J

1950-01-01

The free turbulent mixing of a supersonic jet of Mach number 1.6 has been experimentally investigated. An interferometer, of which a description is given, was used for the investigation. Density and velocity distributions through the mixing zone have been obtained. It was found that there was similarity in distribution at the cross sections investigated and that, in the subsonic portion of the mixing zone, the velocity distribution fitted the theoretical distribution for incompressible flow. It was found that the rates of spread of the mixing zone both into the jet and into the ambient air were less than those of subsonic jets.

Microwave plasma generation of hydrogen atoms for rocket propulsion

NASA Technical Reports Server (NTRS)

Chapman, R.; Filpus, J.; Morin, T.; Snellenberger, R.; Asmussen, J.; Hawley, M.; Kerber, R.

1981-01-01

A flow microwave plasma reaction system is used to study the conversion of hydrogen to hydrogen atoms as a function of pressure, power density, cavity tuning, cavity mode, and time in the plasma zone. Hydrogen atom concentration is measured down-stream from the plasma by NOCl titration. Extensive modeling of the plasma and recombination zones is performed with the plasma zone treated as a backmix reaction system and the recombination zone treated as a plug flow. The thermodynamics and kinetics of the recombination process are examined in detail to provide an understanding of the conversion of recombination energy to gas kinetic energy. It is found that cavity tuning, discharge stability, and optimum power coupling are critically dependent on the system pressure, but nearly independent of the flow rate.

Multi-zone cooling/warming garment

NASA Technical Reports Server (NTRS)

Leon, Gloria R. (Inventor); Koscheyev, Victor S. (Inventor); Dancisak, Michael J. (Inventor)

2006-01-01

A thermodynamically efficient garment for cooling and/or heating a human body. The thermodynamic efficiency is provided in part by targeting the heat exchange capabilities of the garment to specific areas and/or structures of the human body. The heat exchange garment includes heat exchange zones and one or more non-heat exchange zones, where the heat exchange zones are configured to correspond to one or more high density tissue areas of the human body when the garment is worn. A system including the garment can be used to exchange heat with the adjacent HD tissue areas under the control of a feedback control system. Sensed physiological parameters received by the feedback control system can be used to adjust the characteristics of heat exchange fluid moving within the heat exchange garment.

Density structure and geometry of the Costa Rican subduction zone from 3-D gravity modeling and local earthquake data

NASA Astrophysics Data System (ADS)

Lücke, O. H.; Arroyo, I. G.

2015-07-01

The eastern part of the oceanic Cocos Plate presents a heterogeneous crustal structure due to diverse origins and ages as well as plate-hot spot interactions which originated the Cocos Ridge, a structure that converges with the Caribbean Plate in southeastern Costa Rica. The complex structure of the oceanic plate directly influences the dynamics and geometry of the subduction zone along the Middle American Trench. In this paper an integrated interpretation of the slab geometry is presented based on three-dimensional density modeling of combined satellite and surface gravity data, constrained by available geophysical and geological data and seismological information obtained from local networks. The results show the continuation of steep subduction geometry from the Nicaraguan margin into Northwestern Costa Rica, followed by a moderate dipping slab under the Central Cordillera toward the end of the Central American Volcanic Arc. To the southeast end of the volcanic arc, our preferred model shows a steep, coherent slab that extends up to the landward projection of the Panama Fracture Zone. Overall, a gradual change in the depth of the intraplate seismicity is observed, reaching 220 km in the northwestern part, and becoming progressively shallower toward the southeast, where it reaches a terminal depth of 75 km. The changes in the terminal depth of the observed seismicity correlate with the increased density in the modeled slab. The absence of intermediate depth intraplate seismicity in the southeastern section and the higher densities for the subducted slab in this area, support a model in which dehydration reactions in the subducted slab cease at a shallower depth, originating an anhydrous and thus aseismic slab.

Density structure and geometry of the Costa Rican subduction zone from 3-D gravity modeling and local earthquake data

NASA Astrophysics Data System (ADS)

Lücke, O. H.; Arroyo, I. G.

2015-10-01

The eastern part of the oceanic Cocos Plate presents a heterogeneous crustal structure due to diverse origins and ages as well as plate-hot spot interactions which originated the Cocos Ridge, a structure that converges with the Caribbean Plate in southeastern Costa Rica. The complex structure of the oceanic plate directly influences the dynamics and geometry of the subduction zone along the Middle American Trench. In this paper an integrated interpretation of the slab geometry in Costa Rica is presented based on 3-D density modeling of combined satellite and surface gravity data, constrained by available geophysical and geological data and seismological information obtained from local networks. The results show the continuation of steep subduction geometry from the Nicaraguan margin into northwestern Costa Rica, followed by a moderate dipping slab under the Central Cordillera toward the end of the Central American Volcanic Arc. Contrary to commonly assumed, to the southeast end of the volcanic arc, our preferred model shows a steep, coherent slab that extends up to the landward projection of the Panama Fracture Zone. Overall, a gradual change in the depth of the intraplate seismicity is observed, reaching 220 km in the northwestern part, and becoming progressively shallower toward the southeast, where it reaches a maximum depth of 75 km. The changes in the terminal depth of the observed seismicity correlate with the increased density in the modeled slab. The absence of intermediate depth (> 75 km) intraplate seismicity in the southeastern section and the higher densities for the subducted slab in this area, support a model in which dehydration reactions in the subducted slab cease at a shallower depth, originating an anhydrous and thus aseismic slab.

Influence of stretching and density contrasts on the chemical evolution of continental magmas: An example from the Ivrea-Verbano Zone

USGS Publications Warehouse

Sinigoi, S.; Quick, J.E.; Mayer, A.; Budahn, J.

1996-01-01

The southern Ivrea-Verbano Zone of the Italian Western Alps contains a huge mafic complex that intruded high-grade metamorphic rocks while they were resident in the lower crust. Geologic mapping and chemical variations of the igneous body were used to study the evolution of underplated crust. Slivers of crustal rocks (septa) interlayered with igneous mafic rocks are concentrated in a narrow zone deep in the complex (Paragneiss-bearing Belt) and show evidence of advanced degrees of partial melting. Variations of rare-earth-element patterns and Sr isotope composition of the igneous rocks across the sequence are consistent with increasing crustal contamination approaching the septa. Therefore, the Paragneiss-bearing Belt is considered representative of an "assimilation region" where in-situ interaction between mantle- and crust-derived magmas resulted in production of hybrid melts. Buoyancy caused upwards migration of the hybrid melts that incorporated the last septa and were stored at higher levels, feeding the Upper Mafic Complex. Synmagmatic stretching of the assimilation region facilitated mixing and homogenization of melts. Chemical variations of granitoids extracted from the septa show that deep septa are more depleted than shallow ones. This suggests that the first incorporated septa were denser than the later ones, as required by the high density of the first-injected mafic magmas. It is inferred that density contrasts between mafic melts and crustal rocks play a crucial role for the processes of contamination of continental magmas. In thick under- plated crust, the extraction of early felsic/hybrid melts from the lower crust may be required to increase the density of the lower crust and to allow the later mafic magmas to penetrate higher crustal levels.

Integral field spectroscopy of selected areas of the Bright bar and Orion-S cloud in the Orion nebula

NASA Astrophysics Data System (ADS)

Mesa-Delgado, A.; Núñez-Díaz, M.; Esteban, C.; López-Martín, L.; García-Rojas, J.

2011-10-01

We present integral field spectroscopy of two selected zones in the Orion nebula obtained with the Potsdam Multi-Aperture Spectrophotometer, covering the optical spectral range from 3500 to 7200 Å and with a spatial resolution of 1 arcsec. The observed zones are located on the prominent Bright bar and on the brightest area at the north-east of the Orion south cloud, both containing remarkable ionization fronts. We obtain maps of emission-line fluxes and ratios, electron density and temperatures, and chemical abundances. We study the ionization structure and morphology of both fields, whose ionization fronts show different inclination angles with respect to the plane of the sky. We find that the maps of electron density, O+/H+ and O/H ratios show a rather similar structure. We interpret this as produced by the strong dependence on density of the [O II] lines used to derive the O+ abundance, and that our nominal values of electron density - derived from the [S II] line ratio - may be slightly higher than the appropriate value for the O+ zone. We measure the faint recombination lines of O II in the field at the north-east of the Orion south cloud, allowing us to explore the so-called abundance discrepancy problem. We find a rather constant abundance discrepancy across the field and a mean value similar to that determined in other areas of the Orion nebula, indicating that the particular physical conditions of this ionization front do not contribute to this discrepancy. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

Internal structure of Puna Ridge: evolution of the submarine East Rift Zone of Kilauea Volcano, Hawai ̀i

NASA Astrophysics Data System (ADS)

Leslie, Stephen C.; Moore, Gregory F.; Morgan, Julia K.

2004-01-01

Multichannel seismic reflection, sonobuoy, gravity and magnetics data collected over the submarine length of the 75 km long Puna Ridge, Hawai ̀i, resolve the internal structure of the active rift zone. Laterally continuous reflections are imaged deep beneath the axis of the East Rift Zone (ERZ) of Kilauea Volcano. We interpret these reflections as a layer of abyssal sediments lying beneath the volcanic edifice of Kilauea. Early arrival times or 'pull-up' of sediment reflections on time sections imply a region of high P-wave velocity ( Vp) along the submarine ERZ. Refraction measurements along the axis of the ridge yield Vp values of 2.7-4.85 km/s within the upper 1 km of the volcanic pile and 6.5-7 km/s deeper within the edifice. Few coherent reflections are observed on seismic reflection sections within the high-velocity area, suggesting steeply dipping dikes and/or chaotic and fractured volcanic materials. Southeastward dipping reflections beneath the NW flank of Puna Ridge are interpreted as the buried flank of the older Hilo Ridge, indicating that these two ridges overlap at depth. Gravity measurements define a high-density anomaly coincident with the high-velocity region and support the existence of a complex of intrusive dikes associated with the ERZ. Gravity modeling shows that the intrusive core of the ERZ is offset to the southeast of the topographic axis of the rift zone, and that the surface of the core dips more steeply to the northwest than to the southeast, suggesting that the dike complex has been progressively displaced to the southeast by subsequent intrusions. The gravity signature of the dike complex decreases in width down-rift, and is absent in the distal portion of the rift zone. Based on these observations, and analysis of Puna Ridge bathymetry, we define three morphological and structural regimes of the submarine ERZ, that correlate to down-rift changes in rift zone dynamics and partitioning of intrusive materials. We propose that these correspond to evolutionary stages of developing rift zones, which may partially control volcano growth, mobility, and stability, and may be observable at many other oceanic volcanoes.

Geological modeling of a fault zone in clay rocks at the Mont-Terri laboratory (Switzerland)

NASA Astrophysics Data System (ADS)

Kakurina, M.; Guglielmi, Y.; Nussbaum, C.; Valley, B.

2016-12-01

Clay-rich formations are considered to be a natural barrier for radionuclides or fluids (water, hydrocarbons, CO2) migration. However, little is known about the architecture of faults affecting clay formations because of their quick alteration at the Earth's surface. The Mont Terri Underground Research Laboratory provides exceptional conditions to investigate an un-weathered, perfectly exposed clay fault zone architecture and to conduct fault activation experiments that allow explore the conditions for stability of such clay faults. Here we show first results from a detailed geological model of the Mont Terri Main Fault architecture, using GoCad software, a detailed structural analysis of 6 fully cored and logged 30-to-50m long and 3-to-15m spaced boreholes crossing the fault zone. These high-definition geological data were acquired within the Fault Slip (FS) experiment project that consisted in fluid injections in different intervals within the fault using the SIMFIP probe to explore the conditions for the fault mechanical and seismic stability. The Mont Terri Main Fault "core" consists of a thrust zone about 0.8 to 3m wide that is bounded by two major fault planes. Between these planes, there is an assembly of distinct slickensided surfaces and various facies including scaly clays, fault gouge and fractured zones. Scaly clay including S-C bands and microfolds occurs in larger zones at top and bottom of the Mail Fault. A cm-thin layer of gouge, that is known to accommodate high strain parts, runs along the upper fault zone boundary. The non-scaly part mainly consists of undeformed rock block, bounded by slickensides. Such a complexity as well as the continuity of the two major surfaces are hard to correlate between the different boreholes even with the high density of geological data within the relatively small volume of the experiment. This may show that a poor strain localization occurred during faulting giving some perspectives about the potential for reactivation and leakage of faults affecting clay materials.

Time-evolution of uniform momentum zones in a turbulent boundary layer

NASA Astrophysics Data System (ADS)

Laskari, Angeliki; Hearst, R. Jason; de Kat, Roeland; Ganapathisubramani, Bharathram

2016-11-01

Time-resolved planar particle image velocimetry (PIV) is used to analyse the organisation and evolution of uniform momentum zones (UMZs) in a turbulent boundary layer. Experiments were performed in a recirculating water tunnel on a streamwise-wall-normal plane extending approximately 0 . 5 δ × 1 . 8 δ , in x and y, respectively. In total 400,000 images were captured and for each of the resulting velocity fields, local peaks in the probability density distribution of the streamwise velocity were detected, indicating the instantaneous presence of UMZs throughout the boundary layer. The main characteristics of these zones are outlined and more specifically their velocity range and wall-normal extent. The variation of these characteristics with wall normal distance and total number of zones are also discussed. Exploiting the time information available, time-scales of zones that have a substantial coherence in time are analysed and results show that the zones' lifetime is dependent on both their momentum deficit level and the total number of zones present. Conditional averaging of the flow statistics seems to further indicate that a large number of zones is the result of a wall-dominant mechanism, while the opposite implies an outer-layer dominance.

Influence of the Density Structure of the Caribbean Plate Forearc on the Static Stress State and Asperity Distribution along the Costa Rican Seismogenic Zone

NASA Astrophysics Data System (ADS)

Lücke, O. H.; Gutknecht, B. D.

2014-12-01

Most of the forearc region along the Central American Subduction Zone shows a series of trench-parallel, positive gravity anomalies with corresponding gravity lows along the trench and toward the coast. These features extend from Guatemala to northern Nicaragua. However, the Costa Rican segment of the forearc does not follow this pattern. In this region, the along-trench gravity low is segmented, the coastal low is absent, and the forearc gravity high is located onshore at the Nicoya Peninsula which overlies the seismogenic zone. Geodetic and seismological studies along the Costa Rican Subduction Zone suggest the presence of coupled areas beneath the Nicoya Peninsula prior to the 2012, magnitude Mw 7.6 earthquake. These areas had previously been associated with asperities. Previous publications have proposed a mechanical model for the generation of asperities along the Chilean convergent margin based on the structure of the overriding plate above the seismogenic zone in which dense igneous bodies disturb the state of stress on the seismogenic zone and may influence seismogenic processes. In Costa Rica, surface geology and gravity data indicate the presence of dense basalt/gabbro crust overlying the seismogenic zone where the coupling is present. Bouguer anomaly values in this region reach up to 120×10-5 m/s2, which are the highest for Costa Rica. In this work, the state of stress on the Cocos-Caribbean plate interface is calculated based on the geometry and mass distribution of a 3D density model of the subduction zone as interpreted from gravity data from combined geopotential models. Results show a correlation between the coupled areas at the Nicoya Peninsula and the presence of stress anomalies on the plate interface. The stress anomalies are calculated for the normal component of the vertical stress on the seismogenic zone and are interpreted as being generated by the dense material which makes up the forearc in the area. The dense material of the Nicoya Complex mafic rocks and the topographic load of the peninsula on the seismogenic zone may play a role in the distribution of coupled areas and the seismic behavior of the region since the anomalous normal stress on the plate interface may increase the shear stress threshold for rupture.

[Effects of hyposalinity in Thalassia testudinum (Hydrocharitaceae) from Parque Nacional Morrocoy, Venezuela].

PubMed

Pérez, D; Galindo, L

2000-12-01

The year 1996 had a high pluviosity in Morrocoy National Park (western coastal zone, Venezuela) and low salinity in December 1996 affected the seagrass beds, dominated by Thalassia testudinum. Patches without T. testudinum were observed in localities of the park that used to have very dense populations of this plant. Sampling was done at Las Luisas to determine leaf productivity, turnover rate, short shoot density and relative biomass of plant sections, in order to compare with data obtained in September 1996, previous to the event. Green leaves, roots and rhizomes were the most affected parts. Mean green leaf biomass decreased in January and February 1997 to 5% of the plant's total biomass; mean root biomass decreased in March to 40% and mean rhi zome biomass decreased in February to 30%. The density of the active short shoots decreased to a minimum in February, but in April it reached a value similar to that of September 1996. The density of the inactive short shoots decreased to a minimum in March, and they dissappeared in April, matching the increasing density of the active short shoots between these two months. In February 1997, 56% of the inactive short shoots showed evidence of leaf initiation. In January 1997 the leaf productivity and turnover rate values (2.72 +/- 0.35 g/m2/d and 2.15% leaf DW/d) were similar to the annual mean previously determined from Las Luisas (2.35 +/- 0.72 g/m2/d and 1.96% leaf DW/d). Nevertheless, the values of productivity and turnover rate detected at Las Luisas in April 1997 (4.88 +/- 2.14 g/m2/d and 4.66% leaf DW/d) were higher than those values previously reported for this location. In response to the mortality episode, the leaf productivity and turnover rate of T. testudinum increased and the leaf initiation was activated in the inactive short shoots.

A smoothed stochastic earthquake rate model considering seismicity and fault moment release for Europe

NASA Astrophysics Data System (ADS)

Hiemer, S.; Woessner, J.; Basili, R.; Danciu, L.; Giardini, D.; Wiemer, S.

2014-08-01

We present a time-independent gridded earthquake rate forecast for the European region including Turkey. The spatial component of our model is based on kernel density estimation techniques, which we applied to both past earthquake locations and fault moment release on mapped crustal faults and subduction zone interfaces with assigned slip rates. Our forecast relies on the assumption that the locations of past seismicity is a good guide to future seismicity, and that future large-magnitude events occur more likely in the vicinity of known faults. We show that the optimal weighted sum of the corresponding two spatial densities depends on the magnitude range considered. The kernel bandwidths and density weighting function are optimized using retrospective likelihood-based forecast experiments. We computed earthquake activity rates (a- and b-value) of the truncated Gutenberg-Richter distribution separately for crustal and subduction seismicity based on a maximum likelihood approach that considers the spatial and temporal completeness history of the catalogue. The final annual rate of our forecast is purely driven by the maximum likelihood fit of activity rates to the catalogue data, whereas its spatial component incorporates contributions from both earthquake and fault moment-rate densities. Our model constitutes one branch of the earthquake source model logic tree of the 2013 European seismic hazard model released by the EU-FP7 project `Seismic HAzard haRmonization in Europe' (SHARE) and contributes to the assessment of epistemic uncertainties in earthquake activity rates. We performed retrospective and pseudo-prospective likelihood consistency tests to underline the reliability of our model and SHARE's area source model (ASM) using the testing algorithms applied in the collaboratory for the study of earthquake predictability (CSEP). We comparatively tested our model's forecasting skill against the ASM and find a statistically significant better performance for testing periods of 10-20 yr. The testing results suggest that our model is a viable candidate model to serve for long-term forecasting on timescales of years to decades for the European region.

Spatio-temporal changes in the structure of an Australian frog hybrid zone: a 40-year perspective.

PubMed

Smith, Katie L; Hale, Joshua M; Gay, Laurène; Kearney, Michael; Austin, Jeremy J; Parris, Kirsten M; Melville, Jane

2013-12-01

Spatio-temporal studies of hybrid zones provide an opportunity to test evolutionary hypotheses of hybrid zone maintenance and movement. We conducted a landscape genetics study on a classic hybrid zone of the south-eastern Australian frogs, Litoria ewingii and Litoria paraewingi. This hybrid zone has been comprehensively studied since the 1960s, providing the unique opportunity to directly assess changes in hybrid zone structure across time. We compared both mtDNA and male advertisement call data from two time periods (present and 1960s). Clinal analysis of the coincidence (same center) and concordance (same width) of these traits indicated that the center of the hybrid zone has shifted 1 km south over the last 40 years, although the width of the zone and the rate of introgression remained unchanged. The low frequency of hybrids, the strong concordance of clines within a time period, and the small but significant movement across the study period despite significant anthropogenic changes through the region, suggest the hybrid zone is a tension zone located within a low-density trough. Hybrid zone movement has not been considered common in the past but our findings highlight that it should be considered a crucial component to our understanding of evolution. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Spatial and temporal variations of thunderstorm activities over Sri Lanka

NASA Astrophysics Data System (ADS)

Sonnadara, Upul

2016-05-01

Spatial and temporal variation of frequencies of thunderstorms over Sri Lanka using thunder day data is presented. A thunder day is simply a calendar day in which thunder is heard at least once at a given location. Two sets of data were collected and analyzed: annual totals for 10 climatological stations for a period of 50 years and monthly totals for 20 climatological stations for a period of 20 years. The average annual thunder days over Sri Lanka was found to be 76. Among the climatological stations considered, a high number of annual thunder days was recorded in Ratnapura (150 days/year), followed by Colombo (108 days/year) and Bandarawela (106 days/year). It appears that there are no widespread long-term increasing or decreasing trends in thunderstorm frequencies. However, Colombo, the capital of Sri Lanka which has over two million people shows an increasing trend of 0.8 thunder days per year. Although there is a high variability between stations reporting the number of thunder days, the overall pattern within a year is clear. Thunderstorm frequencies are high during two periods: March-May and September-November, which coincide with the first inter-monsoon and second inter-monsoon periods. Compared to the dry zone, the wet zone, especially the southwestern region, has high thunderstorm activity. There is a clear spatial difference in thunderstorm activities during the southwest and northeast monsoon seasons. During both these seasons, enhanced thunderstorm activities are reported on the leeward side of the mountain range. A slight reduction in the thunderstorm activities was found in the high elevation areas of the hill country compared to the surrounding areas. A lightning ground flash density map derived using annual thunder days is also presented.

Total-hip arthroplasty: Periprosthetic indium-111-labeled leukocyte activity and complementary technetium-99m-sulfur colloid imaging in suspected infection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palestro, C.J.; Kim, C.K.; Swyer, A.J.

1990-12-01

Indium-111-labeled leukocyte images of 92 cemented total-hip arthroplasties were correlated with final diagnoses. Prostheses were divided into four zones: head (including acetabulum), trochanter, shaft, and tip. The presence (or absence) and intensity of activity in each zone was noted, and compared to the corresponding contralateral zone. Though present in all 23 infected arthroplasties, periprosthetic activity was also present in 77% of uninfected arthroplasties, and was greater than the contralateral zone 51% of the time. When analyzed by zone, head zone activity was the best criterion for infection (87% sensitivity, 94% specificity, 92% accuracy). Fifty of the arthroplasties were studied withmore » combined labeled leukocyte/sulfur colloid imaging. Using incongruence of images as the criterion for infection, the sensitivity, specificity, and accuracy of the study were 100%, 97%, and 98%, respectively. While variable periprosthetic activity makes labeled leukocyte imaging alone unreliable for diagnosing hip arthroplasty infection, the addition of sulfur colloid imaging results in a highly accurate diagnostic procedure.« less

High exhaust temperature, zoned, electrically-heated particulate matter filter

DOEpatents

Gonze, Eugene V.; Paratore, Jr., Michael J.; Bhatia, Garima

2015-09-22

A system includes a particulate matter (PM) filter, an electric heater, and a control circuit. The electric heater includes multiple zones, which each correspond to longitudinal zones along a length of the PM filter. A first zone includes multiple discontinuous sub-zones. The control circuit determines whether regeneration is needed based on an estimated level of loading of the PM filter and an exhaust flow rate. In response to a determination that regeneration is needed, the control circuit: controls an operating parameter of an engine to increase an exhaust temperature to a first temperature during a first period; after the first period, activates the first zone; deactivates the first zone in response to a minimum filter face temperature being reached; subsequent to deactivating the first zone, activates a second zone; and deactivates the second zone in response to the minimum filter face temperature being reached.

An in situ approach to detect tree root ecology: linking ground-penetrating radar imaging to isotope-derived water acquisition zones

PubMed Central

Isaac, Marney E; Anglaaere, Luke C N

2013-01-01

Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite–granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground-penetrating radar and root activity via soil water acquisition using isotopic matching of δ18O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified by edaphic conditions. Soil δ18O isotopic signature declined with depth, providing conditions for plant–soil δ18O isotopic matching. This pattern held only under sandstone conditions where water acquisition zones were identifiably narrow in the 10–20 cm depth but broader under phyllite–granite conditions, presumably due to resource patchiness. Detected coarse root count by depth and measured fine root density were strongly correlated as were detected coarse root count and identified water acquisition zones, thus validating root detection capability of ground-penetrating radar, but exclusively on sandstone soils. This approach was able to characterize trends between intraspecific root architecture and edaphic-dependent resource availability, however, limited by site conditions. This study successfully demonstrates a new approach for in situ root studies that moves beyond invasive point sampling to nondestructive detection of root architecture and function. We discuss the transfer of such an approach to answer root ecology questions in various tree-based landscapes. PMID:23762519

Petrology of deep drill hole, Kilauea Volcano

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grose, L.T.; Keller, G.V.

1976-12-01

The first deep drill hole (1262 m TD) at the summit of an active volcano (1102 m elev) was drilled in 1973 at Kilauea volcano, Hawaii with support from NSF and USGS. The hole is located within southern margin of Kilauea caldera in northern part of a 15 km/sup 2/ triangular block bounded by east rift zone, Koae fault zone, and southwest rift zone-a summit area relatively free of faults, rifts, and extrusions. Nearest eruptions are from fissures 1.2 km away which are active in 1974 and which do not trend toward the drill hole. Core recovery totals 47 mmore » from 29 core runs at rather evenly spaced intervals to total depth. Megascopic, thin-section, and X-ray examination reveals: (1) Recovered core is essentially vesicular, intergranular, nonporphyritic to porphyritic olivine basalt with minor olivine diabase, picrite diabase, and basalt, (2) Hyaloclastite and pillow basalt are absent, (3) Below water table (614 m elev) with increasing depth, vesicularity decreases, and density, crystallinity, competence, vesicle fill, and alteration irregularly increase, (4) Alteration first occurs at water table where calcite and silica partially fill vesticles and olivine is partially serpentinized, (5) At about 570 m elev massive serpentinization of olivine and deposition of montmorillonite-nontronite occur; at about 210 m elev truscottite and tobermorite occur in vesicles; at about 35 m elev mordenite occurs in vesicles, (6) Bottom-hole cores have complete filling of vesicles with silica, minor silica replacement, and complete alteration of olivine, and (7) Plagioclase is unaltered. Chemical analyses of bottom-hole cores are similar to those of modern summit lavas. Alteration and low porosity in bottom-hole cores plus abrupt temperature increase suggest the drill hole penetrated a self-sealed ''cap rock'' to a hydrothermal convection cell and possibly a magma body.« less

Archaeology in the Kilauea East Rift Zone: Part 1, Land-use model and research design, Kapoho, Kamaili and Kilauea Geothermal Subzones, Puna District, Hawaii Island

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burtchard, G.C.; Moblo, P.

1994-07-01

The Puna Geothermal Resource Subzones (GRS) project area encompasses approximately 22,000 acres centered on the Kilauea East Rift Zone in Puna District, Hawaii Island. The area is divided into three subzones proposed for geothermal power development -- Kilauea Middle East Rift, Kamaili and Kapoho GRS. Throughout the time of human occupation, eruptive episodes along the rift have maintained a dynamic landscape. Periodic volcanic events, for example, have changed the coastline configuration, altered patterns of agriculturally suitable sediments, and created an assortment of periodically active, periodically quiescent, volcanic hazards. Because of the active character of the rift zone, then, the area`smore » occupants have always been obliged to organize their use of the landscape to accommodate a dynamic mosaic of lava flow types and ages. While the specific configuration of settlements and agricultural areas necessarily changed in response to volcanic events, it is possible to anticipate general patterns in the manner in which populations used the landscape through time. This research design offers a model that predicts the spatial results of long-term land-use patterns and relates them to the character of the archaeological record of that use. In essence, the environmental/land-use model developed here predicts that highest population levels, and hence the greatest abundance and complexity of identifiable prehistoric remains, tended to cluster near the coast at places that maximized access to productive fisheries and agricultural soils. With the possible exception of a few inland settlements, the density of archaeological remains expected to decrease with distance from the coastline. The pattern is generally supported in the regions existing ethnohistoric and archaeological record.« less

Wet plume atop of the flattening slab: Insight into intraplate volcanism in East Asia

NASA Astrophysics Data System (ADS)

He, Lijuan

2017-08-01

Geophysical observations imply the intraplate volcanism in East Asia is related to dehydration of slab stagnating in the transition zone. To better understand the dynamics of such process, a thermochemical mantle convection model is constructed to simulate numerically the thermal evolution of slab and the transportation of water in the process of slab downgoing, flattening and stagnation. Equation of water transfer is included, and water effects on density and viscosity are considered. Model results indicate the warming of slab by surrounding mantle is rather slow. Water could be successfully dragged into the transition zone if the reference viscosity of the hydrous layer (with initial water of 2 wt%) is higher than 1017 Pa s and that of mantle is 1021 Pa s. Wet plumes could then originate in the flat-lying part of the slab, relatively far from the trench. Generally, the viscosity of the hydrous layer governs the initiation of wet plume, whereas the viscosity of the overlying mantle wedge controls the activity of the ascending wet plumes - they are more active in the weaker wedge. The complex fluid flow superposed by corner flow and free thermal convection influences greatly the water transport pattern in the upper mantle. Modeling results together with previous modeling infer three stages of water circulation in the big mantle wedge: 1) water is brought into the mantle transition zone by downward subducting slab under some specific thermo-rheological conditions, otherwise water is released at shallow depth near wedge tip; 2) wet plume generates from surface of the flattening slab warmed by surrounding mantle, and 3) water spreads over the big mantle wedge. Wet plume from the flattening Pacific Plate arrives at the lithospheric base and induces melting, which can explain the intraplate Cenozoic volcanoes in East Asia.

Detecting Taiwan's Shanchiao Active Fault Using AMT and Gravity Methods

NASA Astrophysics Data System (ADS)

Liu, H.-C.; Yang, C.-H.

2009-04-01

Taiwan's Shanchiao normal fault runs in a northeast-southwest direction and is located on the western edge of the Taipei Basin in northern Taiwan. The overburden of the fault is late Quaternary sediment with a thickness of approximately a few tenth of a meter to several hundred meters. No detailed studies of the western side of the Shanchiao fault are available. As Taiwan is located on the Neotectonic Belt in the western Pacific, detecting active faults near the Taipei metropolitan area will provide necessary information for further disaster prevention. It is the responsibility of geologists and geophysicists in Taiwan to perform this task. Examination of the resistivity and density contrasts of subsurface layers permits a mapping of the Shanchiao fault and the deformed Tertiary strata of the Taipei Basin. The audio-frequency magnetotelluric (AMT) method and gravity method were chosen for this study. Significant resistivity and gravity anomalies were observed in the suspected fault zone. The interpretation reveals a good correlation between the features of the Shanchiao fault and resistivity and density distribution at depth. In this observation, AMT and gravity methods provides a viable means for mapping the Shanchiao fault position and studying its features associated with the subsidence of the western side of the Taipei Basin. This study indicates the AMT and gravity methods' considerable potential for accurately mapping an active fault.

Dechlorination kinetics of TCE at toxic TCE concentrations: Assessment of different models.

PubMed

Haest, P J; Springael, D; Smolders, E

2010-01-01

The reductive dechlorination of trichloroethene (TCE) in a TCE source zone can be self-inhibited by TCE toxicity. A study was set up to examine the toxicity of TCE in terms of species specific degradation kinetics and microbial growth and to evaluate models that describe this self-inhibition. A batch experiment was performed using the TCE dechlorinating KB-1 culture at initial TCE concentrations ranging from 0.04mM to saturation (8.4mM). Biodegradation activity was highest at 0.3mM TCE and no activity was found at concentrations from 4 to 8mM. Species specific TCE and cis-DCE (cis-dichloroethene) degradation rates and Dehalococcoides numbers were modeled with Monod kinetics combined with either Haldane inhibition or a log-logistic dose-response inhibition on these rates. The log-logistic toxicity model appeared the most appropriate model and predicts that the species specific degradation activities are reduced by a factor 2 at about 1mM TCE, respectively cis-DCE. However, the model showed that the inhibitive effects on the time for TCE to ethene degradation are a complex function of degradation kinetics and the initial cell densities of the dechlorinating species. Our analysis suggests that the self-inhibition on biodegradation cannot be predicted by a single concentration threshold without information on the cell densities.

Regional imbalanced activation of the calcineurin/BAD apoptotic pathway and the PI3K/Akt survival pathway after myocardial infarction.

PubMed

Li, Tieluo; Kilic, Ahmet; Wei, Xufeng; Wu, Changfu; Schwartzbauer, Gary; Yankey, G Kwame; DeFilippi, Christopher; Bond, Meredith; Wu, Zhongjun J; Griffith, Bartley P

2013-06-05

The underlying molecular mechanisms of the remodeling after myocardial infarction (MI) remain unclear. The purpose of this study was to investigate the role of a survival pathway (PI3K/Akt) and an apoptosis pathway (calcineurin/BAD) in the remodeling after MI in a large animal model. Ten Dorset hybrid sheep underwent 25% MI in the left ventricle (LV, n=10). Five sheep were used as sham control. The regional strain was calculated from sonomicrometry. Apoptosis and the activation of the PI3K/Akt and calcineurin/BAD pathways were evaluated in the non-ischemic adjacent zone and the remote zone relative to infarct by immunoblotting, immunoprecipitation, and immunofluorescence staining. Dilation and dysfunction of LV were present at 12 weeks after MI. The regional strain in the adjacent zone was significantly higher than in the remote zone at 12 weeks (36.6 ± 4.0% vs 9.5 ± 3.6%, p<0.05). Apoptosis was more severe in the adjacent zone than in the remote zone. The PI3K/Akt and calcineurin/BAD pathways were activated in the adjacent zone. Dephosphorylation and translocation of BAD were evident in the adjacent zone. Regional correlation between the strain and the expression of calcineurin/BAD indicated that the activation was strain-related (R(2)=0.46, 0.48, 0.39 for calcineurin, BAD, mitochondrial BAD, respectively, p<0.05). The PI3K/Akt survival and calcineurin/BAD apoptotic pathways were concomitantly activated in the non-ischemic adjacent zone after MI. The calcineurin/BAD pathway is strain related and its imbalanced activation may be one of the causes of progressive remodeling after MI. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Regional imbalanced activation of the calcineurin/BAD apoptotic pathway and the PI3K/Akt survival pathway after myocardial infarction

PubMed Central

Li, Tieluo; Kilic, Ahmet; Wei, Xufeng; Wu, Changfu; Schwartzbauer, Gary; Yankey, G. Kwame; DeFilippi, Christopher; Bond, Meredith; Wu, Zhongjun J; Griffith, Bartley P

2011-01-01

Background The underlying molecular mechanisms of the remodeling after myocardial infarction (MI) remain unclear. The purpose of this study was to investigate the role of a survival pathway (PI3K/Akt) and an apoptosis pathway (calcineurin/BAD) in the remodeling after MI in a large animal model. Methods Ten Dorset hybrid sheep underwent 25% MI in the left ventricle (LV, n=10). Five sheep were used as sham control. The regional strain was calculated from sonomicrometry. Apoptosis and the activation of the PI3K/Akt and calcineurin/BAD pathways were evaluated in the non-ischemic adjacent zone and the remote zone relative to infarct by immunoblotting, immunoprecipitation, and immunofluorescence staining. Results Dilation and dysfunction of LV were present at 12 weeks after MI. The regional strain in the adjacent zone was significantly higher than in the remote zone at 12 weeks (36.6 ± 4.0% vs 9.5 ± 3.6%, p < 0.05). Apoptosis was more severe in the adjacent zone than in the remote zone. The PI3K/Akt and calcineurin/BAD pathways were activated in the adjacent zone. Dephosphorylation and translocation of BAD were evident in the adjacent zone. Regional correlation between the strain and the expression of calcineurin/BAD indicated that the activation was strain-related (R2 = 0.46, 0.48, 0.39 for calcineurin, BAD, mitochondrial BAD, respectively, p < 0.05). Conclusions The PI3K/Akt survival and calcineurin/BAD apoptotic pathways were concomitantly activated in the non-ischemic adjacent zone after MI. The calcineurin/BAD pathway is strain related and its imbalanced activation may be one of the causes of progressive remodeling after MI. PMID:22088220

Brown bear-human interactions associated with deer hunting on Kodiak Island

USGS Publications Warehouse

Barnes, Victor G.

1994-01-01

I compared distribution and range of brown bears (Ursus arctos middendorffi) with temporal and spatial distribution of Sitka black-tailed deer (Odocoileus hemionus sitkensis) hunting activity on westside Kodiak Island, Alaska, to examine impacts of deer hunting on bears. Mean number of bears that annually ranged ≤5 km from the coast, >5 km inland from the coast, or in both areas was 10, 8, and 11, respectively. Bears that exclusively or seasonally occupied the coast zone were usually classed as having moderate or high potential to interact with hunters because most hunter access and effort (>95%) was via the coast. Bears that ranged exclusively inland were considered unlikely to encounter hunters. Animals that ranged in both zones often (39%) moved inland during fall (Oct-Dec) and most bears (70%) denned in the inland zone. Females that denned near the coast entered dens later (x̄ = 22 Nov) than females that denned inland (x̄ = 12 Nov). Two radio-collared bears were known to raid deer-hunting camps and 9 other marked bears were observed by hunters or were located <200 m from hunting camps. Deer-hunter surveys revealed that more than two-thirds of the deer harvest occurred during October-November. About half of the hunters observed at least 1 bear during their hunt. Seven to 21% of the respondents reported having a threatening encounter with a bear and 5-26% reported losing deer meat to bears. Human-induced mortality to radio-collared bears occurred more often near the coast (5) than inland (3); 7 bears were harvested by sport hunters and 1 was killed (nonsport) in a Native village. Deer hunters killed 2 unmarked females in defense of life or property situations in the study area. High bear densities and concentrated deer-hunting activity combine to make conflicts unavoidable. Adverse impacts to bears can be minimized by maintaining low levels of human activity in inland areas and improving hunter awareness of bear ecology and behavior.

Malaria vector abundance is associated with house structures in Baringo County, Kenya.

PubMed

Ondiba, Isabella M; Oyieke, Florence A; Ong'amo, George O; Olumula, Macrae M; Nyamongo, Isaac K; Estambale, Benson B A

2018-01-01

Malaria, a major cause of morbidity and mortality, is the most prevalent vector borne disease in Baringo County; a region which has varied house designs in arid and semi-arid areas. This study investigated the association between house structures and indoor-malaria vector abundance in Baringo County. The density of malaria vectors in houses with open eaves was higher than that for houses with closed eaves. Grass thatched roof houses had higher density of malaria vectors than corrugated iron sheet roofs. Similarly, mud walled houses had higher vector density than other wall types. Houses in the riverine zone were significantly associated with malaria vector abundance (p<0.000) possibly due to more varied house structures. In Kamnarok village within riverine zone, a house made of grass thatched roof and mud wall but raised on stilts with domestic animals (sheep/goats) kept at the lower level had lower mosquito density (5.8 per collection) than ordinary houses made of same materials but at ground level (30.5 mosquitoes per collection), suggestive of a change in behavior of mosquito feeding and resting. House modifications such as screening of eaves, improvement of construction material and building stilted houses can be incorporated in the integrated vector management (IVM) strategy to complement insecticide treated bed nets and indoor residual spray to reduce indoor malaria vector density.

The hydrometeorological implications of zoning laws: Can land use regulations of urban density and sprawl improve a city's resilience?

NASA Astrophysics Data System (ADS)

Bou-Zeid, E.; Ryu, Y. H.; Smith, J. A.; Newburn, D. A.

2015-12-01

The intensification of heat waves and of the hydrological cycle due to global climate change pose particularly high risks to urban residents. Cities are already hotter than their surroundings due to the urban heat island effect and are known to result in local intensification of rainfall and flooding due to their coupled impacts on the surface and the lower atmosphere. These interacting local and global changes can adversely affect the health and well being of urban residents, and city administrators are increasing efforts to mitigate and adapt to the potential disruptions though various infrastructure and preparedness programs. However, as cities worldwide continue to expand, a key decision is how to manage that urban sprawl and regulate its spatial features to aid in the mitigation and adaptation effort. This study assesses whether alternative zoning regulations that modify the density and extent of a metropolitan region, but have a minimal impact on total population and demographic growth, have an appreciable impact on its response to extreme weather events, and as such, whether they can be used to increase urban resilience. We consider Baltimore (the city and its surrounding suburbs), which in 1967 adopted one of the first urban growth boundaries (UGBs) in the United States, as our test case. Departing from the urban extent circa 1900, we create alternative land use patterns that, compared to the actual current land use baseline, would have resulted from drastically different policy scenarios and approaches to zoning that the city would have undertaken. We consider various alternatives where the city is smaller and denser, due to stricter regulation, versus larger and less dense than the actual baseline, while maintaining the same total population. Our findings indicate that lower densities have significant benefits: compared to the current landscape and to denser patterns, they reduce both extreme temperatures during heat waves and spatio-temporal rainfall peaks. While the particular findings hold for Baltimore and many cities with comparable climates, the conclusion that zoning laws and the resulting spatial patterns for urban density have important implications on a city's response to changing climate and extreme weather are more broadly applicable.

Counterintuitive effect of fall mixed layer deepening on eukaryotic new production in the Sargasso Sea

NASA Astrophysics Data System (ADS)

Fawcett, S. E.; Lomas, M. W.; Ward, B. B.; Sigman, D. M.

2012-12-01

The Sargasso Sea is characterized by a short period of deep vertical mixing in the late winter and early spring, followed by strong thermal stratification during the summer. Stratification persists into the fall, impeding the upward flux of nitrate from depth so that recycled forms of nitrogen (N) such as ammonium are thought to support most primary production. We collected particles from surface waters during March, July, October, and December, used flow cytometry to separate the prokaryotic and eukaryotic phytoplankton, and analyzed their respective 15N/14N. In all months, the 15N/14N of the prokaryotic genera, Prochlorococcus and Synechococcus, was low, indicative of reliance on recycled N throughout the year. In July, the 15N/14N of eukaryotic phytoplankton was variable but consistently higher than that of the prokaryotes, reflecting eukaryotic consumption of subsurface nitrate. Two eukaryotic profiles from October and December were similar to those from July. In three other fall profiles, the eukaryotes had a 15N/14N similar to that of the prokaryotes, suggesting a switch toward greater reliance on recycled N. This change in the dominant N source supporting eukaryotic production appears to be driven by the density structure of the upper water column. The very shallow low-density surface "mixed layer" (≤20 m) that develops in early-to-mid summer does not contribute to stratification at the base of the euphotic zone, and subsurface nitrate can mix up into the lower euphotic zone, facilitating continued production. The deepening of the mixed layer into the fall, typically taken as an indication of weaker overall stratification, actually strengthens the isolation of the euphotic zone as a whole, reducing the upward supply of nitrate to the photosynthetically active layer. The same counterintuitive dynamic explains the latitudinal patterns in a set of three October depth profiles. Two northern stations (32°N and 27°N) were characterized by a thick, low-density surface layer, and the 15N/14N of all phytoplankton was low, consistent with assimilation of recycled N. The southernmost station (23°N) had a shallower mixed layer, and eukaryote 15N/14N reflects growth on nitrate. In the subtropics, evidence for the direct supply of nitrate into surface waters in the face of the strong upper ocean stratification has long been sought. Our N isotope results suggest a mechanism by which subsurface nitrate is imported into shallow waters. This interpretation offers a new perspective on the relationship between euphotic zone stratification and nitrate assimilation, implying that significant new production occurs under conditions previously assumed to drive oligotrophy.