Contour mapping of relic structures in the Precambrian basement of the Reelfoot rift, North American midcontinent

USGS Publications Warehouse

Dart, R.L.; Swolfs, H.S.

1998-01-01

A new contour map of the basement of the Reelfoot rift constructed from drill hole and seismic reflection data shows the general surface configuration as well as several major and minor structural features. The major features are two asymmetric intrarift basins, bounded by three structural highs, and the rift margins. The basins are oriented normal to the northeast trend of the rift. Two of the highs appear to be ridges of undetermined width that extend across the rift. The third high is an isolated dome or platform located between the basins. The minor features are three linear structures of low relief oriented subparallel to the trend of the rift. Two of these, located within the rift basins, may divide the rift basins into paired subbasins. These mapped features may be the remnants of initial extensional rifting, half graben faulting, and basement subsidence. The rift basins are interpreted as having formed as opposing half graben, and the structural highs are interpreted as having formed as associated accommodation zones. Some of these features appear to be reactivated seismogenic structures within the modem midcontinent compressional stress regime. A detailed knowledge of the geometries of the Reelfoot rift's basement features, therefore, is essential when evaluating their seismic risk potential.

Algorithms for Determining Physical Responses of Structures Under Load

NASA Technical Reports Server (NTRS)

Richards, W. Lance; Ko, William L.

2012-01-01

Ultra-efficient real-time structural monitoring algorithms have been developed to provide extensive information about the physical response of structures under load. These algorithms are driven by actual strain data to measure accurately local strains at multiple locations on the surface of a structure. Through a single point load calibration test, these structural strains are then used to calculate key physical properties of the structure at each measurement location. Such properties include the structure s flexural rigidity (the product of the structure's modulus of elasticity, and its moment of inertia) and the section modulus (the moment of inertia divided by the structure s half-depth). The resulting structural properties at each location can be used to determine the structure s bending moment, shear, and structural loads in real time while the structure is in service. The amount of structural information can be maximized through the use of highly multiplexed fiber Bragg grating technology using optical time domain reflectometry and optical frequency domain reflectometry, which can provide a local strain measurement every 10 mm on a single hair-sized optical fiber. Since local strain is used as input to the algorithms, this system serves multiple purposes of measuring strains and displacements, as well as determining structural bending moment, shear, and loads for assessing real-time structural health. The first step is to install a series of strain sensors on the structure s surface in such a way as to measure bending strains at desired locations. The next step is to perform a simple ground test calibration. For a beam of length l (see example), discretized into n sections and subjected to a tip load of P that places the beam in bending, the flexural rigidity of the beam can be experimentally determined at each measurement location x. The bending moment at each station can then be determined for any general set of loads applied during operation.

Concentration Measurements in Self-Excited, Momentum-Dominated Helium Jets

NASA Technical Reports Server (NTRS)

Yildirim, Bekir Sedat

2004-01-01

Flow structure of momentum-dominated pure helium jets discharged vertically into ambient air was investigated using high-speed rainbow schlieren deflectometry (RSD) technique. Effects of the operating parameters, i.e., Reynolds number (Re) and Richardson number (Ri), on the oscillatory behavior of the flow were examined over a range of experimental conditions. To seek the individual effect of these parameters, one of them was fixed and the other was varied with certain constraints. Measurements revealed highly periodic oscillations in the laminar region as well as high regularity in transition and turbulent regions. Maximum spectral power profiles at different axial locations indicated the oscillation amplitude increasing until the breakdown of the jet in the turbulent regime. The transition from the laminar to turbulent flow was also investigated. Fast Fourier transform analysis performed in the transition regime showed that the flow oscillates at a unique frequency, which was the same in the upstream laminar flow region. Measured deflection angle data were used in Abel inversion algorithm to construct the helium concentration fields. Instantaneous helium concentration contours revealed changes in the flow structure and evolution of vortical structures during an oscillation cycle. Temporal evolution plots of helium concentration at different axial location showed repeatable oscillations at all axial and radial locations up to the turbulent regime. A cross-correlation technique, applied to find the spatial displacements of the vortical structures, provided correlation coefficient peaks between consecutive schlieren images. Results show that the vortical structure convected and accelerated only in the axial direction.

Individual Differences in the Alignment of Structural and Functional Markers of the V5/MT Complex in Primates

PubMed Central

Large, I.; Bridge, H.; Ahmed, B.; Clare, S.; Kolasinski, J.; Lam, W. W.; Miller, K. L.; Dyrby, T. B.; Parker, A. J.; Smith, J. E. T.; Daubney, G.; Sallet, J.; Bell, A. H.; Krug, K.

2016-01-01

Extrastriate visual area V5/MT in primates is defined both structurally by myeloarchitecture and functionally by distinct responses to visual motion. Myelination is directly identifiable from postmortem histology but also indirectly by image contrast with structural magnetic resonance imaging (sMRI). First, we compared the identification of V5/MT using both sMRI and histology in Rhesus macaques. A section-by-section comparison of histological slices with in vivo and postmortem sMRI for the same block of cortical tissue showed precise correspondence in localizing heavy myelination for V5/MT and neighboring MST. Thus, sMRI in macaques accurately locates histologically defined myelin within areas known to be motion selective. Second, we investigated the functionally homologous human motion complex (hMT+) using high-resolution in vivo imaging. Humans showed considerable intersubject variability in hMT+ location, when defined with myelin-weighted sMRI signals to reveal structure. When comparing sMRI markers to functional MRI in response to moving stimuli, a region of high myelin signal was generally located within the hMT+ complex. However, there were considerable differences in the alignment of structural and functional markers between individuals. Our results suggest that variation in area identification for hMT+ based on structural and functional markers reflects individual differences in human regional brain architecture. PMID:27371764

Magnesium content within the skeletal architecture of the coral Montastraea faveolata: locations of brucite precipitation and implications to fine-scale data fluctuations

USGS Publications Warehouse

Buster, N.A.; Holmes, C.W.

2006-01-01

Small portions of coral cores were analyzed using a high-resolution laser ablation inductively coupled plasma mass spectrometer (LA ICP-MS) to determine the geochemical signatures within and among specific skeletal structures in the large framework coral, Montastraea faveolata. Vertical transects were sampled along three parallel skeletal structures: endothecal (septal flank), corallite wall, and exothecal (costal flank) areas. The results demonstrate that trace element levels varied among the three structures. Magnesium (Mg) varied among adjacent structures and was most abundant within the exothecal portion of the skeleton. Scanning electron microscopy (SEM) revealed the presence of hexagonal crystals forming thick discs, pairs or doublets of individual crystals, and rosettes in several samples. High Mg within these crystals was confirmed with energy dispersive spectroscopy (EDS), infrared spectrometry, and LA ICP-MS. The chemical composition is consistent with the mineral brucite [Mg(OH2)]. These crystals are located exclusively in the exothecal area of the skeleton, are often associated with green endolithic algae, and are commonly associated with increased Mg levels found in the adjacent corallite walls. Although scattered throughout the exothecal, the brucite crystals are concentrated within green bands where levels of Mg increase substantially relative to other portions of the skeleton. The presence and locations of high-Mg crystals may explain the fine-scale fluctuations in Mg data researchers have been questioning for years.

Streaks, multiplets, and holes: High-resolution spatio-temporal behavior of Parkfield seismicity

USGS Publications Warehouse

Waldhauser, F.; Ellsworth, W.L.; Schaff, D.P.; Cole, A.

2004-01-01

Double-difference locations of ???8000 earthquakes from 1969-2002 on the Parkfield section of the San Andreas Fault reveal detailed fault structures and seismicity that is, although complex, highly organized in both space and time. Distinctive features of the seismicity include: 1) multiple recurrence of earthquakes of the same size at precisely the same location on the fault (multiplets), implying frictional or geometric controls on their location and size; 2) sub-horizontal alignments of hypocenters along the fault plane (streaks), suggestive of rheological transitions within the fault zone and/or stress concentrations between locked and creeping areas; 3) regions devoid of microearthquakes with typical dimensions of 1-5 km (holes), one of which contains the M6 1966 Parkfield earthquake hypocenter. These features represent long lived structures that persist through many cycles of individual event. Copyright 2004 by the American Geophysical Union.

Automated Interpretation of Subcellular Patterns in Fluorescence Microscope Images for Location Proteomics

PubMed Central

Chen, Xiang; Velliste, Meel; Murphy, Robert F.

2010-01-01

Proteomics, the large scale identification and characterization of many or all proteins expressed in a given cell type, has become a major area of biological research. In addition to information on protein sequence, structure and expression levels, knowledge of a protein’s subcellular location is essential to a complete understanding of its functions. Currently subcellular location patterns are routinely determined by visual inspection of fluorescence microscope images. We review here research aimed at creating systems for automated, systematic determination of location. These employ numerical feature extraction from images, feature reduction to identify the most useful features, and various supervised learning (classification) and unsupervised learning (clustering) methods. These methods have been shown to perform significantly better than human interpretation of the same images. When coupled with technologies for tagging large numbers of proteins and high-throughput microscope systems, the computational methods reviewed here enable the new subfield of location proteomics. This subfield will make critical contributions in two related areas. First, it will provide structured, high-resolution information on location to enable Systems Biology efforts to simulate cell behavior from the gene level on up. Second, it will provide tools for Cytomics projects aimed at characterizing the behaviors of all cell types before, during and after the onset of various diseases. PMID:16752421

Small-scale lacustrine drifts in Lake Champlain, Vermont

USGS Publications Warehouse

Manley, Patricia L.; Manley, T.O.; Hayo, Kathryn; Cronin, Thomas

2012-01-01

High resolution CHIRP (Compressed High Intensity Radar Pulse) seismic profiles reveal the presence of two lacustrine sediment drifts located in Lake Champlain's Juniper Deep. Both drifts are positive features composed of highly laminated sediments. Drift B sits on a basement high while Drift A is built on a trough-filling acoustically-transparent sediment unit inferred to be a mass-transport event. These drifts are oriented approximately north–south and are parallel to a steep ridge along the eastern shore of the basin. Drift A, located at the bottom of a structural trough, is classified as a confined, elongate drift that transitions northward to become a system of upslope asymmetric mudwaves. Drift B is perched atop a structural high to the west of Drift A and is classified as a detached elongate drift. Bottom current depositional control was investigated using Acoustic Doppler Current Profilers (ADCPs) located across Drift A. Sediment cores were taken at the crest and at the edges of the Drift A and were dated. Drift source, deposition, and evolution show that these drifts are formed by a water column shear with the highest deposition occurring along its crest and western flank and began developing circa 8700–8800 year BP.

CMOS-Compatible Fabrication for Photonic Crystal-Based Nanofluidic Structure.

PubMed

Peng, Wang; Chen, Youping; Ai, Wu; Zhang, Dailin; Song, Han; Xiong, Hui; Huang, Pengcheng

2017-12-01

Photonic crystal (PC)-based devices have been widely used since 1990s, while PC has just stepped into the research area of nanofluidic. In this paper, photonic crystal had been used as a complementary metal oxide semiconductors (CMOS) compatible part to create a nanofluidic structure. A nanofluidic structure prototype had been fabricated with CMOS-compatible techniques. The nanofluidic channels were sealed by direct bonding polydimethylsiloxane (PDMS) and the periodic gratings on photonic crystal structure. The PC was fabricated on a 4-in. Si wafer with Si 3 N 4 as the guided mode layer and SiO 2 film as substrate layer. The higher order mode resonance wavelength of PC-based nanofluidic structure had been selected, which can confine the enhanced electrical field located inside the nanochannel area. A design flow chart was used to guide the fabrication process. By optimizing the fabrication device parameters, the periodic grating of PC-based nanofluidic structure had a high-fidelity profile with fill factor at 0.5. The enhanced electric field was optimized and located within the channel area, and it can be used for PC-based nanofluidic applications with high performance.

The Role of the Dynamic Plasmapause on Outer Radiation Belt Electron Flux Enhancement and Three-Belt Structure Formation

NASA Astrophysics Data System (ADS)

Bruff, M.; Jaynes, A. N.; Zhao, H.; Malaspina, D.

2017-12-01

The plasmasphere is a highly dynamic toroidal region of cold, dense plasma around Earth. Plasma waves exist both inside and outside this region and can contribute to the loss and acceleration of high energy outer radiation belt electrons. Early observational studies found an apparent correlation on long time scales between the observed inner edge of the outer radiation belt and the simulated innermost plasmapause location. More recent work using high resolution Van Allen Probe satellite data has found a more complex relationship. The aim of this project was to provide a systematic study of the location and dynamics of the plasmapause compared to the MeV electrons in the outer radiation belt. We used spin-averaged electron flux data from the Relativistic Electron Proton Telescope (REPT) and density data derived from the EFW instrument on the Van Allen Probe satellites. We analyzed these data to determine the standoff distance of the location of peak electron flux of the outer belt MeV electrons from the plasmapause. We found that the location of peak flux was consistently outside but within ΔL=2.5 from the innermost location of the plasmapause at enhancement times, with an average standoff distance ΔL=1.0 +/- 0.5. This is consistent with the current model of chorus enhancement and previous observations of chorus activity. Finally, we identified "three-belt" structure events where a second outer belt formed and found a repeated pattern of plasmapause dynamics associated with specific changes in electron flux required to generate and sustain these structures. This study is significant to improving our understanding of how the plasmasphere under differing conditions can both shield Earth from or worsen the impacts of geomagnetic activity.

Acute posterior cruciate ligament injuries: effect of location, severity, and associated injuries on surgical management.

PubMed

Anderson, Mark A; Simeone, F Joseph; Palmer, William E; Chang, Connie Y

2018-06-01

To correlate MRI findings of patients with posterior cruciate ligament (PCL) injury and surgical management. A retrospective search yielded 79 acute PCL injuries (36 ± 16 years old, 21 F, 58 M). Two independent readers graded PCL tear location (proximal, middle, or distal third) and severity (low-grade or high-grade partial/complete) and evaluated injury of other knee structures. When available, operative reports were examined and the performed surgical procedure was compared with injury grade, location, and presence of associated injuries. The most commonly injured knee structures in acute PCL tears were posterolateral corner (58/79, 73%) and anterior cruciate ligament (ACL) (48/79, 61%). Of the 64 patients with treatment information, 31/64 (48%) were managed surgically: 12/31 (39%) had PCL reconstruction, 13/31 (42%) had ACL reconstruction, 10/31 (32%) had posterolateral corner reconstruction, 9/31 (29%) had LCL reconstruction, 8/31 (26%) had meniscectomy, and 8/31 (26%) had fixation of a fracture. Proximal third PCL tear and multiligamentous injury were more commonly associated with surgical management (P < 0.05). Posterolateral and posteromedial corner, ACL, collateral ligament, meniscus, patellar retinaculum, and gastrocnemius muscle injury, and fracture were more likely to result in surgical management (P < 0.05). Patients with high-grade partial/complete PCL tear were more likely to have PCL reconstruction as a portion of surgical management (P < 0.05). Location of PCL tear and presence of other knee injuries were associated with surgical management while high-grade/complete PCL tear grade was associated with PCL reconstruction. MRI reporting of PCL tear location, severity, and of other knee structure injuries is important for guiding clinical management.

Investigating the effective range of vacuum ultraviolet-mediated breakdown in high-power microwave metamaterials

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

Liu, Chien-Hao, E-mail: cliu82@wisc.edu; Neher, Joel D., E-mail: jdneher@wisc.edu; Booske, John H., E-mail: booske@engr.wisc.edu

2014-10-14

Metamaterials and periodic structures operating under high-power excitations are susceptible to breakdown. It was recently demonstrated that a localized breakdown created in a given region of a periodic structure can facilitate breakdown in other regions of the structure where the intensity of the incident electromagnetic fields may not be high enough to cause breakdown under normal circumstances. It was also demonstrated that this phenomenon is due to the generation of vacuum ultraviolet radiation at the location of the initial discharge, which propagates to the neighboring regions (e.g., other unit cells in a periodic structure) and facilitates the generation of amore » discharge at a lower incident power level. In this paper, we present the results of an experimental study conducted to determine the effective range of this physical phenomenon for periodic structures that operate in air and in pure nitrogen gas at atmospheric pressure levels. It is demonstrated that when breakdown is induced in a periodic structure using a high-power pulse with a frequency of 9.382 GHz, duration of 0.8 μs, and peak power level of 25 kW, this phenomenon is highly likely to happen in radii of approximately 16–17 mm from the location of the initial discharge under these test conditions. The results of this study are significant in designing metamaterials and periodic structures for high-power microwave applications as they suggest that a localized discharge created in such a periodic structure with a periodicity less than 16–17 mm can spread over a large surface and result in a distributed discharge.« less

Gold grade distribution within an epithermal quartz vein system, Kestanelik, NW Turkey: implications for gold exploration

NASA Astrophysics Data System (ADS)

Gulyuz, Nilay; Shipton, Zoe; Gulyuz, Erhan; Lord, Richard; Kaymakci, Nuretdin; Kuscu, İlkay

2017-04-01

Vein-hosted gold deposits contribute a large part to the global gold production. Discovery of these deposits mainly include drilling of hundreds of holes, collecting thousands of soil and rock samples and some geophysical surveys which are expensive and time consuming. Understanding the structures hosting the veins and the variations in gold concentrations within the veins is crucial to constrain a more economic exploration program. The main aim of this study is to investigate the gold grade distribution in the mineralized quartz veins of a well exposed epithermal gold deposit hosted by Paleozoic schist and Eocene quartz-feldspar-hornblende porphyry in Lapseki, NW Turkey. We have constructed 3D architecture of the vein surfaces by mapping their outcrop geometries using a highly sensitive Trimble GPS, collecting detailed field data, well-logs and geochemistry data from 396 drill holes (255 diamond cut and 141 reverse circulation holes). Modelling was performed in MOVE Structural Modelling and Analysis software granted by Midland Valley's Academic Software Initiative, and GIS application softwares Global Mapper and Esri-ArcGIS. We envisaged that while fluid entering the conduit ascents, a sudden thickness increase in the conduit would lead to a drop in the fluid pressure causing boiling (the most dominant gold precipitation mechanism) and associated gold precipitation. Regression analysis was performed between the orthogonal thickness values and gold grades of each vein, and statistical analyses were performed to see if the gold is concentrated at specific structural positions along dip. Gold grades in the alteration zones were compared to those in the adjacent veins to understand the degree of mineralization in alteration zones. A possible correlation was also examined between the host rock type and the gold grades in the veins. These studies indicated that gold grades are elevated in the adjacent alteration zones where high gold grades exist in the veins. Schist-hosted veins host the majority of gold mineralization (94.39%). While there is almost no correlation between the true vein thickness and the gold grade, 77.65% of high gold grades are located where the veins bend along dip. These results suggest that multiple gold precipitation mechanisms may have been active and boiling mechanism responsible for gold precipitation along the structural pathways was more effective than possible fluid-rock interaction or throttling mechanisms which will precipitate gold at adjacent alteration zones around the pathways at Kestanelik. In addition, specific structural locations such as vein bends are favorable for gold precipitation. This study emphasizes that structural architecture of the veins is one of the key controls on the location of high gold grades. In addition, adding structural data collection and mapping specific structural locations such as bends to the exploration program could permit the key locations of high gold grade to be identified faster, and to focus further drilling and assays.

Incorporation of spatial interactions in location networks to identify critical geo-referenced routes for assessing disease control measures on a large-scale campus.

PubMed

Wen, Tzai-Hung; Chin, Wei Chien Benny

2015-04-14

Respiratory diseases mainly spread through interpersonal contact. Class suspension is the most direct strategy to prevent the spread of disease through elementary or secondary schools by blocking the contact network. However, as university students usually attend courses in different buildings, the daily contact patterns on a university campus are complicated, and once disease clusters have occurred, suspending classes is far from an efficient strategy to control disease spread. The purpose of this study is to propose a methodological framework for generating campus location networks from a routine administration database, analyzing the community structure of the network, and identifying the critical links and nodes for blocking respiratory disease transmission. The data comes from the student enrollment records of a major comprehensive university in Taiwan. We combined the social network analysis and spatial interaction model to establish a geo-referenced community structure among the classroom buildings. We also identified the critical links among the communities that were acting as contact bridges and explored the changes in the location network after the sequential removal of the high-risk buildings. Instead of conducting a questionnaire survey, the study established a standard procedure for constructing a location network on a large-scale campus from a routine curriculum database. We also present how a location network structure at a campus could function to target the high-risk buildings as the bridges connecting communities for blocking disease transmission.

Sensitivity of dual-wall structures under hypervelocity impact to multi-layer thermal insulation thickness and placement

NASA Astrophysics Data System (ADS)

Schonberg, William P.

1993-04-01

Results are presented from an experimental study in which Al dual-wall structures were tested, under various high-speed impact conditions, with a view to the effect of multilayer insulation thickness and location on perforation resistance. Attention is given to comparisons of the damage sustained by dual-wall systems with multilayer insulation blankets of various thicknesses and at various locations within the dual-wall system, under comparable impact loading conditions. The placement of the insulation has a significant effect on the ballistic limit of the dual-wall structures considered, while reducing insulation thickness by as much as a third did not.

Physical, Structural and Operational Vulnerability of Critical Facilities in Valle de Chalco Solidaridad, Estado de Mexico, Mexico. Case of study: Avándaro, San Isidro and El Triunfo

NASA Astrophysics Data System (ADS)

Garcia Payne, D. G.; Novelo-Casanova, D. A.; Ponce-Pacheco, A. B.; Espinosa-Campos, O.; Huerta-Parra, M.; Reyes-Pimentel, T.; Rodriguez, F.; Benitez-Olivares, I.

2010-12-01

Valle de Chalco Solidaridad is located in Mexico City Metropolitan Area in Estado de Mexico, Mexico. In this town there is a sewage canal called “La Compañía”. A wall of this canal collapsed on February 5, 2010 due to heavy rains creating the flooding of four surrounding communities. It is important to point out that this area is frequently exposed to floods. In this work, we consider a critical facility as an essential structure for performance, health care and welfare within a community or/and as a place that can be used as shelter in case of emergency or disaster. Global vulnerability (the sum of the three measured vulnerabilities) of the 25 critical facilities identified in the locations of Avándaro, San Isidro and El Triunfo was assessed using the Community Vulnerability Assessment Tool developed by the National Oceanic and Atmospheric Administration (NOAA). For each critical facility we determined its operational, structural and physical vulnerabilities. For our analysis, we considered the four main natural hazards to which Valle de Chalco is exposed: earthquakes, floods, landslides and sinking. We considered five levels of vulnerability using a scale from 1 to 5, where values range from very low to very high vulnerability, respectively. A critical facilities database was generated by collecting general information for three categories: schools, government and church. Each facility was evaluated considering its location in relation to identified high-risk areas. Our results indicate that in average, the global vulnerability of all facilities is low, however, there are particular cases in which this global vulnerability is high. The average operational vulnerability of the three communities is moderate. The global structural vulnerability (sum of the structural vulnerability for the four analyzed hazards) is moderate. In particular, the structural vulnerability to earthquakes is low, to landslides is very low, to flooding is moderate and to sinking is low. Due to the location of the critical facilities, its global physical vulnerability (sum of the physical vulnerability to the four analyzed hazards) is moderate. Only three facilities have very high physical vulnerability to floods. Churches (six facilities) have the highest operational vulnerability, whereas its structural vulnerability is the lowest. Schools (13 facilities) have the lowest operational vulnerability, nevertheless, there are two schools with very high vulnerability. Regarding the six government facilities, we identified that their structural vulnerability range from moderate to high. As a result of this work, we believe in the importance of strengthening the culture of civil protection within the critical facilities of the communities of Valle de Chalco.

Thin-walled reinforcement lattice structure for hollow CMC buckets

DOEpatents

de Diego, Peter

2017-06-27

A hollow ceramic matrix composite (CMC) turbine bucket with an internal reinforcement lattice structure has improved vibration properties and stiffness. The lattice structure is formed of thin-walled plies made of CMC. The wall structures are arranged and located according to high stress areas within the hollow bucket. After the melt infiltration process, the mandrels melt away, leaving the wall structure to become the internal lattice reinforcement structure of the bucket.

Structural control of co-continuous poly(L-lactide)/poly(butylene succinate)/clay nanocomposites.

PubMed

Zhao, Li; Li, Yongjin; Shimizu, Hiroshi

2009-04-01

Poly(L-lactide) (PLLA)/poly(butylene succinate) (PBS) (55/45 w/w) blends with different amounts of nanoclay loadings were prepared using a specially designed high-shear extruder, HSE3000mini, which can reach a maximum shear rate of 4400 sec(-1). The resulted co-continuous structural morphologies were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM observation revealed that through the combination of various amounts of nanoclay loadings and processing under various shear conditions, the phase size of co-continuous structures of PLLA/PBS blends can be controlled over a wide range from several tens of micrometers to submicrometers. TEM observation shows that all the nanoclays are selectively dispersed in the PBS phase. We also found that clays in low-shear processed sample were mainly located at the interface of PBS phase, while in high-shear sample, the clays were mainly located inside of the PBS phase. It was considered that the dependence of nanoclay location in the PBS phase on the shear conditions, as well as the changing of the viscosity ratio of PBS and PLLA phase with different amounts of clay loading, play important roles in controlling the phase size of the co-continuous structures of PLLA/PBS blends.

Use of high-resolution satellite images for detection of geological structures related to Calerias geothermal field, Chile

NASA Astrophysics Data System (ADS)

Arellano-Baeza, A. A.; Urzua, L.

2011-12-01

Chile has enormous potential to use the geothermal resources for electric energy generation. The main geothermal fields are located in the Central Andean Volcanic Chain in the North, between the Central valley and the border with Argentina in the center, and in the fault system Liquiñe-Ofqui in the South of the country. High resolution images from the LANDSAT and ASTER satellites have been used to delineate the geological structures related to the Calerias geothermal field located at the northern end of the Southern Volcanic Zone of Chile. It was done by applying the lineament extraction technique developed by authors. These structures have been compared with the distribution of main geological structures obtained in the field. It was found that the lineament density increases in the areas of the major heat flux indicating that the lineament analysis could be a power tool for the detection of faults and joint zones associated to the geothermal fields.

Screening actuator locations for static shape control

NASA Technical Reports Server (NTRS)

Haftka, Raphael T.

1990-01-01

Correction of shape distortion due to zero-mean normally distributed errors in structural sizes which are random variables is examined. A bound on the maximum improvement in the expected value of the root-mean-square shape error is obtained. The shape correction associated with the optimal actuators is also characterized. An actuator effectiveness index is developed and shown to be helpful in screening actuator locations in the structure. The results are specialized to a simple form for truss structures composed of nominally identical members. The bound and effectiveness index are tested on a 55-m radiometer antenna truss structure. It is found that previously obtained results for optimum actuators had a performance close to the bound obtained here. Furthermore, the actuators associated with the optimum design are shown to have high effectiveness indices. Since only a small fraction of truss elements tend to have high effectiveness indices, the proposed screening procedure can greatly reduce the number of truss members that need to be considered as actuator sites.

3-D Resistivity Structure of La Soufrière Volcano (Guadeloupe): New Insights into the Hydrothermal System and Associated Hazards

NASA Astrophysics Data System (ADS)

Rosas-Carbajal, M.; Nicollin, F.; Komorowski, J. C.; Gibert, D.; Deroussi, S.

2015-12-01

The 3-D electrical resistivity model of the dome of La Soufrière of Guadeloupe volcano was obtained by inverting more than 23000 electrical resistivity tomography (ERT) and mise-a-la-masse data points. Data acquisition involved 2-D and 3-D protocols, including several pairs of injection electrodes located on opposite sides of the volcano. For the mise-a-la-masse measurements, the contact with a conductive mass was achieved by immersing one of the current electrodes in the Tarissan acid pond (~25 Siemens/m) located in the volcano's summit. The 3-D inversion was performed using a deterministic smoothness-constrained least-squares algorithm with unstructured grid modeling to accurately account for topography. Resistivity contrasts of more than 4 orders of magnitude are observed. A thick and high-angle conductive structure is located in the volcano's southern flank. It extends from the Tarissan Crater's acid pond on the summit to a hot spring region located close to the dome's southern base. This suggests that a large hydrothermal reservoir is located below the southern base of the dome, and connected to the acid pond of the summit's main crater. Therefore, the steep southern flanks of the volcano could be resting on a low-strength, high-angle discontinuity saturated with circulating and possibly pressurized hydrothermal fluids. This could favor partial edifice collapse and lateral directed explosions as shown recurrently in the volcano's history. The resistivity model also reveals smaller hydrothermal reservoirs in the south-east and northern flanks that are linked to the main historical eruptive fractures and to ancient collapse structures such as the Cratère Amic structure. We discuss the main resistivity structures in relation with the geometry of observed faults, historical eruptive fractures, the dynamics of the near surface hydrothermal system manifestations on the dome and the potential implications for future hazards scenarios .

Space Shuttle Main Engine structural analysis and data reduction/evaluation. Volume 3A: High pressure oxidizer turbo-pump preburner pump housing stress analysis report

NASA Technical Reports Server (NTRS)

Shannon, Robert V., Jr.

1989-01-01

The model generation and structural analysis performed for the High Pressure Oxidizer Turbopump (HPOTP) preburner pump volute housing located on the main pump end of the HPOTP in the space shuttle main engine are summarized. An ANSYS finite element model of the volute housing was built and executed. A static structural analysis was performed on the Engineering Analysis and Data System (EADS) Cray-XMP supercomputer

Performances of different global positioning system devices for time-location tracking in air pollution epidemiological studies.

PubMed

Wu, Jun; Jiang, Chengsheng; Liu, Zhen; Houston, Douglas; Jaimes, Guillermo; McConnell, Rob

2010-11-23

People's time-location patterns are important in air pollution exposure assessment because pollution levels may vary considerably by location. A growing number of studies are using global positioning systems (GPS) to track people's time-location patterns. Many portable GPS units that archive location are commercially available at a cost that makes their use feasible for epidemiological studies. We evaluated the performance of five portable GPS data loggers and two GPS cell phones by examining positional accuracy in typical locations (indoor, outdoor, in-vehicle) and factors that influence satellite reception (building material, building type), acquisition time (cold and warm start), battery life, and adequacy of memory for data storage. We examined stationary locations (eg, indoor, outdoor) and mobile environments (eg, walking, traveling by vehicle or bus) and compared GPS locations to highly-resolved US Geological Survey (USGS) and Digital Orthophoto Quarter Quadrangle (DOQQ) maps. The battery life of our tested instruments ranged from <9 hours to 48 hours. The acquisition of location time after startup ranged from a few seconds to >20 minutes and varied significantly by building structure type and by cold or warm start. No GPS device was found to have consistently superior performance with regard to spatial accuracy and signal loss. At fixed outdoor locations, 65%-95% of GPS points fell within 20-m of the corresponding DOQQ locations for all the devices. At fixed indoor locations, 50%-80% of GPS points fell within 20-m of the corresponding DOQQ locations for all the devices except one. Most of the GPS devices performed well during commuting on a freeway, with >80% of points within 10-m of the DOQQ route, but the performance was significantly impacted by surrounding structures on surface streets in highly urbanized areas. All the tested GPS devices had limitations, but we identified several devices which showed promising performance for tracking subjects' time location patterns in epidemiological studies.

Performances of Different Global Positioning System Devices for Time-Location Tracking in Air Pollution Epidemiological Studies

PubMed Central

Wu, Jun; Jiang, Chengsheng; Liu, Zhen; Houston, Douglas; Jaimes, Guillermo; McConnell, Rob

2010-01-01

Background: People’s time-location patterns are important in air pollution exposure assessment because pollution levels may vary considerably by location. A growing number of studies are using global positioning systems (GPS) to track people’s time-location patterns. Many portable GPS units that archive location are commercially available at a cost that makes their use feasible for epidemiological studies. Methods: We evaluated the performance of five portable GPS data loggers and two GPS cell phones by examining positional accuracy in typical locations (indoor, outdoor, in-vehicle) and factors that influence satellite reception (building material, building type), acquisition time (cold and warm start), battery life, and adequacy of memory for data storage. We examined stationary locations (eg, indoor, outdoor) and mobile environments (eg, walking, traveling by vehicle or bus) and compared GPS locations to highly-resolved US Geological Survey (USGS) and Digital Orthophoto Quarter Quadrangle (DOQQ) maps. Results: The battery life of our tested instruments ranged from <9 hours to 48 hours. The acquisition of location time after startup ranged from a few seconds to >20 minutes and varied significantly by building structure type and by cold or warm start. No GPS device was found to have consistently superior performance with regard to spatial accuracy and signal loss. At fixed outdoor locations, 65%–95% of GPS points fell within 20-m of the corresponding DOQQ locations for all the devices. At fixed indoor locations, 50%–80% of GPS points fell within 20-m of the corresponding DOQQ locations for all the devices except one. Most of the GPS devices performed well during commuting on a freeway, with >80% of points within 10-m of the DOQQ route, but the performance was significantly impacted by surrounding structures on surface streets in highly urbanized areas. Conclusions: All the tested GPS devices had limitations, but we identified several devices which showed promising performance for tracking subjects’ time location patterns in epidemiological studies. PMID:21151593

HRTEM and neutron diffraction study of Li{sub x}Mo{sub 5}O{sub 17}: From the ribbon (x=5) structure to the rock salt (x=12) structure

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

Lebedev, O.I.; Caignaert, V.; Raveau, B.

2011-04-15

Structure determination of the fully intercalated phase Li{sub 12}Mo{sub 5}O{sub 17} and of the deintercalated oxide Li{sub 5}Mo{sub 5}O{sub 17} has been carried out by electron microscopy and neutron powder diffraction. The reversible topotactic transformation between the ordered rock salt structure of the former and the ribbon structure of the latter (closely related to that of Li{sub 4}Mo{sub 5}O{sub 17}) is explained on the following basis: both structures can be described as strips built up as an assembly of infinite ribbons of MoO{sub 6} octahedra that are five octahedra thick, and that differ by slight displacements of the octahedral ribbons.more » We show that the electrochemical behavior of the Li{sub x}Mo{sub 5}O{sub 17} system is based on two sorts of Li{sup +} sites; those that are located within the strips between the ribbons, and those that are located at the border of the strips. The high rate of Li intercalation in this oxide and its reversibility are discussed in terms of its peculiar structure. -- Graphical abstract: Structure determination of the fully intercalated phase Li{sub 12}Mo{sub 5}O{sub 17} and of the deintercalated oxide Li{sub 5}Mo{sub 5}O{sub 17} has been carried out by electron microscopy and neutron powder diffraction. The reversible topotactic transformation between the ordered rock salt structure of the former and the ribbon structure of the latter is explained on the following basis: both structures can be described as strips built up as an assembly of infinite ribbons of MoO{sub 6} octahedra that are five octahedra thick, and that differ by slight displacements of the octahedral ribbons. We show that the electrochemical behavior of the Li{sub x}Mo{sub 5}O{sub 17} system is based on two sorts of Li{sup +} sites; those that are located within the strips between the ribbons, and those that are located at the border of the strips. The high rate of Li intercalation in this oxide and its reversibility are discussed in terms of its peculiar structure. Research highlights: {yields} Electron microscopy and neutron powder diffraction structure determination {yields} We have explained the reversible topotactic transformation between an ordered rock salt structure and a ribbon structure {yields} We show that the electrochemical behavior of the Li{sub x}Mo{sub 5}O{sub 17} system is based on two sorts of Li{sup +} sites {yields} The high rate of Li intercalation in this oxide and its reversibility are discussed in terms of its peculiar structure.« less

Study of the effects of wind power and vortex-induced vibrations to establish fatigue design criteria for high-mast poles.

DOT National Transportation Integrated Search

2011-08-01

Traffic signal and high-mast poles are used by transportation agencies to control and illuminate intersections; their structural design is governed by national specifications. High-mast poles are luminaire supports located near highway interchanges t...

Blacktip reef sharks, Carcharhinus melanopterus, have high genetic structure and varying demographic histories in their Indo-Pacific range.

PubMed

Vignaud, Thomas M; Mourier, Johann; Maynard, Jeffrey A; Leblois, Raphael; Spaet, Julia; Clua, Eric; Neglia, Valentina; Planes, Serge

2014-11-01

For free-swimming marine species like sharks, only population genetics and demographic history analyses can be used to assess population health/status as baseline population numbers are usually unknown. We investigated the population genetics of blacktip reef sharks, Carcharhinus melanopterus; one of the most abundant reef-associated sharks and the apex predator of many shallow water reefs of the Indian and Pacific Oceans. Our sampling includes 4 widely separated locations in the Indo-Pacific and 11 islands in French Polynesia with different levels of coastal development. Four-teen microsatellite loci were analysed for samples from all locations and two mitochondrial DNA fragments, the control region and cytochrome b, were examined for 10 locations. For microsatellites, genetic diversity is higher for the locations in the large open systems of the Red Sea and Australia than for the fragmented habitat of the smaller islands of French Polynesia. Strong significant structure was found for distant locations with FST values as high as ~0.3, and a smaller but still significant structure is found within French Polynesia. Both mitochondrial genes show only a few mutations across the sequences with a dominant shared haplotype in French Polynesia and New Caledonia suggesting a common lineage different to that of East Australia. Demographic history analyses indicate population expansions in the Red Sea and Australia that may coincide with sea level changes after climatic events. Expansions and flat signals are indicated for French Polynesia as well as a significant recent bottleneck for Moorea, the most human-impacted lagoon of the locations in French Polynesia. © 2014 John Wiley & Sons Ltd.

3-D seismic results in the discovery of significant reserves bypassed for 55 years in the Chocolate Bayou Field

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

Pennington, A.; Plant, C.; Davis, C.

1994-12-31

The Chocolate Bayou Field is located 25 miles south of Houston, in Southeast Brazoria County, Texas. Discovered in 1938, the field has produced over 2 trillion cubic feet of natural gas and 65 million barrels of oil from approximately 30 sands and 300 wellbores. The majority of the production is from the sands of the upper and middle Frio (Oligocene) section. Accumulation is found on structural highs on both the downthrown and upthrown side of a major basinward growth fault. A 3-D seismic survey was conducted over the field in 1988 in an effort to locate bypassed reserves. Interpretation ofmore » the data revealed and unexpected paleo structure associated with a buried and previously undetected counter-regional fault located almost 3 miles south of the structural crest at the Upper Frio level. Detailed structural and isochron mapping with adequate depth conversions indicated that the structure was prospective for trapping of the Lower Frio Sand which were well developed but wet under the Upper Frio structural crest. Although the feature was located on the absolute edge of the survey, the data were adequate to locate two wells which have now been completed in the Lower Frio (RA{sub 4}) section. The sands ranged in thickness from 65 to 115 feet of net pay with porosities from 27 to 30% with sustained production rates in excess of 10,000 million cubic feet of gas and 140 barrels of oil per day per completion.« less

1-D seismic velocity model and hypocenter relocation using double difference method around West Papua region

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

Sabtaji, Agung, E-mail: sabtaji.agung@gmail.com, E-mail: agung.sabtaji@bmkg.go.id; Indonesia’s Agency for Meteorological, Climatological and Geophysics Region V, Jayapura 1572; Nugraha, Andri Dian, E-mail: nugraha@gf.itb.ac.id

2015-04-24

West Papua region has fairly high of seismicity activities due to tectonic setting and many inland faults. In addition, the region has a unique and complex tectonic conditions and this situation lead to high potency of seismic hazard in the region. The precise earthquake hypocenter location is very important, which could provide high quality of earthquake parameter information and the subsurface structure in this region to the society. We conducted 1-D P-wave velocity using earthquake data catalog from BMKG for April, 2009 up to March, 2014 around West Papua region. The obtained 1-D seismic velocity then was used as inputmore » for improving hypocenter location using double-difference method. The relocated hypocenter location shows fairly clearly the pattern of intraslab earthquake beneath New Guinea Trench (NGT). The relocated hypocenters related to the inland fault are also observed more focus in location around the fault.« less

Structural Health Monitoring in Composite Structures by Fiber-Optic Sensors.

PubMed

Güemes, Alfredo; Fernández-López, Antonio; F Díaz-Maroto, Patricia; Lozano, Angel; Sierra-Perez, Julian

2018-04-04

Fiber-optic sensors cannot measure damage; to get information about damage from strain measurements, additional strategies are needed, and several alternatives are available in the existing literature. This paper discusses two independent procedures. The first is based on detecting new strains appearing around a damage spot. The structure does not need to be under loads, the technique is very robust, and damage detectability is high, but it requires sensors to be located very close to the damage, so it is a local technique. The second approach offers wider coverage of the structure; it is based on identifying the changes caused by damage on the strain field in the whole structure for similar external loads. Damage location does not need to be known a priori, and detectability is dependent upon the sensor's network density, the damage size, and the external loads. Examples of application to real structures are given.

Structural Health Monitoring in Composite Structures by Fiber-Optic Sensors †

PubMed Central

Güemes, Alfredo; Díaz-Maroto, Patricia F.; Lozano, Angel; Sierra-Perez, Julian

2018-01-01

Fiber-optic sensors cannot measure damage; to get information about damage from strain measurements, additional strategies are needed, and several alternatives are available in the existing literature. This paper discusses two independent procedures. The first is based on detecting new strains appearing around a damage spot. The structure does not need to be under loads, the technique is very robust, and damage detectability is high, but it requires sensors to be located very close to the damage, so it is a local technique. The second approach offers wider coverage of the structure; it is based on identifying the changes caused by damage on the strain field in the whole structure for similar external loads. Damage location does not need to be known a priori, and detectability is dependent upon the sensor’s network density, the damage size, and the external loads. Examples of application to real structures are given. PMID:29617345

Waveform Based Acoustic Emission Detection and Location of Matrix Cracking in Composites

NASA Technical Reports Server (NTRS)

Prosser, W. H.

1995-01-01

The operation of damage mechanisms in a material or structure under load produces transient acoustic waves. These acoustic waves are known as acoustic emission (AE). In composites they can be caused by a variety of sources including matrix cracking, fiber breakage, and delamination. AE signals can be detected and analyzed to determine the location of the acoustic source by triangulation. Attempts are also made to analyze the signals to determine the type and severity of the damage mechanism. AE monitoring has been widely used for both laboratory studies of materials, and for testing the integrity of structures in the field. In this work, an advanced, waveform based AE system was used in a study of transverse matrix cracking in cross-ply graphite/epoxy laminates. This AE system featured broad band, high fidelity sensors, and high capture rate digital acquisition and storage of acoustic signals. In addition, analysis techniques based on plate wave propagation models were employed. These features provided superior source location and noise rejection capabilities.

D Nearest Neighbour Search Using a Clustered Hierarchical Tree Structure

NASA Astrophysics Data System (ADS)

Suhaibah, A.; Uznir, U.; Anton, F.; Mioc, D.; Rahman, A. A.

2016-06-01

Locating and analysing the location of new stores or outlets is one of the common issues facing retailers and franchisers. This is due to assure that new opening stores are at their strategic location to attract the highest possible number of customers. Spatial information is used to manage, maintain and analyse these store locations. However, since the business of franchising and chain stores in urban areas runs within high rise multi-level buildings, a three-dimensional (3D) method is prominently required in order to locate and identify the surrounding information such as at which level of the franchise unit will be located or is the franchise unit located is at the best level for visibility purposes. One of the common used analyses used for retrieving the surrounding information is Nearest Neighbour (NN) analysis. It uses a point location and identifies the surrounding neighbours. However, with the immense number of urban datasets, the retrieval and analysis of nearest neighbour information and their efficiency will become more complex and crucial. In this paper, we present a technique to retrieve nearest neighbour information in 3D space using a clustered hierarchical tree structure. Based on our findings, the proposed approach substantially showed an improvement of response time analysis compared to existing approaches of spatial access methods in databases. The query performance was tested using a dataset consisting of 500,000 point locations building and franchising unit. The results are presented in this paper. Another advantage of this structure is that it also offers a minimal overlap and coverage among nodes which can reduce repetitive data entry.

Shear-lag effect and its effect on the design of high-rise buildings

NASA Astrophysics Data System (ADS)

Thanh Dat, Bui; Traykov, Alexander; Traykova, Marina

2018-03-01

For super high-rise buildings, the analysis and selection of suitable structural solutions are very important. The structure has not only to carry the gravity loads (self-weight, live load, etc.), but also to resist lateral loads (wind and earthquake loads). As the buildings become taller, the demand on different structural systems dramatically increases. The article considers the division of the structural systems of tall buildings into two main categories - interior structures for which the major part of the lateral load resisting system is located within the interior of the building, and exterior structures for which the major part of the lateral load resisting system is located at the building perimeter. The basic types of each of the main structural categories are described. In particular, the framed tube structures, which belong to the second main category of exterior structures, seem to be very efficient. That type of structure system allows tall buildings resist the lateral loads. However, those tube systems are affected by shear lag effect - a nonlinear distribution of stresses across the sides of the section, which is commonly found in box girders under lateral loads. Based on a numerical example, some general conclusions for the influence of the shear-lag effect on frequencies, periods, distribution and variation of the magnitude of the internal forces in the structure are presented.

Study on control of defect mode in hybrid mirror chirped porous silicon photonic crystal

NASA Astrophysics Data System (ADS)

Chen, Ying; Luo, Pei; Han, Yangyang; Cui, Xingning; He, Lei

2018-03-01

Based on the optical resonance principle and the tight-binding theory, a hybrid mirror chirped porous silicon photonic crystal is proposed. The control of the defect mode in hybrid mirror chirped porous silicon photonic crystal is studied. Through the numerical simulation, the control regulations of the defect modes resulted by the number of the periodical layers for the fundamental unit and the cascading number of the chirped structures are analyzed, and the split and the degeneration of the defect modes resulted by the change of the relative location between the mirror structures and the quasi-mirror structures are discussed. The simulation results show that the band gap would be broadened with the increase of the chirp quantity and the layer number of unilateral chirp. Adjusting the structural parameters of the hybrid mirror structure, the multimode characteristics will occur in the band gap. The more the cascading number of the chirped units, the more the number of the filtering channels will be. In addition, with the increase of the relative location between the mirror structures and the quasi-mirror structures, the degeneration of the defect modes will occur and can obtain high Q value. The structure can provide effective theoretical references for the design the multi-channel filters and high Q value sensors.

The crustal structure in the transition zone between the western and eastern Barents Sea

NASA Astrophysics Data System (ADS)

Shulgin, Alexey; Mjelde, Rolf; Faleide, Jan Inge; Høy, Tore; Flueh, Ernst; Thybo, Hans

2018-07-01

We present a crustal-scale seismic profile in the Barents Sea based on new data. Wide-angle seismic data were recorded along a 600 km long profile at 38 ocean bottom seismometer and 52 onshore station locations. The modelling uses the joint refraction/reflection tomography approach where co-located multichannel seismic reflection data constrain the sedimentary structure. Further, forward gravity modelling is based on the seismic model. We also calculate net regional erosion based on the calculated shallow velocity structure. Our model reveals a complex crustal structure of the Baltic Shield to Barents shelf transition zone, as well as strong structural variability on the shelf itself. We document large volumes of pre-Carboniferous sedimentary strata in the transition zone which reach a total thickness of 10 km. A high-velocity crustal domain found below the Varanger Peninsula likely represents an independent crustal block. Large lower crustal bodies with very high velocity and density below the Varanger Peninsula and the Fedynsky High are interpreted as underplated material that may have fed mafic dykes in the Devonian. We speculate that these lower crustal bodies are linked to the Devonian rifting processes in the East European Craton, or belonging to the integral part of the Timanides, as observed onshore in the Pechora Basin.

Protective immunity provided by a new modified SERA protein peptide: its immunogenetic characteristics and correlation with 3D structure.

PubMed

Bermúdez, Adriana; Moreno-Vranich, Armando; Patarroyo, Manuel E

2012-07-01

The serine repeat antigen (SERA) protein is a leading candidate molecule for inclusion as a component in a multi-antigen, multi-stage, minimal subunit-based, chemically synthesised anti-malarial vaccine. Peptides having high red blood cell binding affinity (known as HABPs) have been identified in this protein. The 6733 HABP was located in the C-terminal portion of the 47-kDa fragment while HABP 6754 was located in the C-terminal region of the 56-kDa fragment. These conserved HABPs failed to induce an immune response. Critical red blood cell binding residues and/or their neighbours (assessed by glycine-analogue scanning) were replaced by others having the same mass, volume and surface but different polarity, rendering some of them highly immunogenic when assessed by antibody production against the parasite or its proteins and protection-inducers against experimental challenge with a highly infectious Aotus monkey-adapted Plasmodium falciparum strain. This manuscript presents some modified HABPs as vaccine candidate components for enriching our tailor-made anti-malarial vaccine repertoire, as well as their 3D structure obtained by 1H-NMR displaying a short-structured region, differently from the native ones having random structures.

Coronal Structures in Cool Stars

NASA Technical Reports Server (NTRS)

Oliversen, Ronald (Technical Monitor); Dupree, Andrea K.

2004-01-01

Many papers have been published that further elucidate the structure of coronas in cool stars as determined from EUVE, HST, FUSE, Chandra, and XMM-Newton observations. In addition we are exploring the effects of coronas on the He I 1083081 transition that is observed in the infrared. Highlights of these are summarized below including publications during this reporting period and presentations. Ground-based magnetic Doppler imaging of cool stars suggests that active stars have active regions located at high latitudes on their surface. We have performed similar imaging in X-ray to locate the sites of enhanced activity using Chandra spectra. Chandra HETG observations of the bright eclipsing contact binary 44i Boo and Chandra LETG observations for the eclipsing binary VW Cep show X-ray line profiles that are Doppler-shifted by orbital motion. After careful analysis of the spectrum of each binary, a composite line-profile is constructed by adding the individual spectral lines. This high signal-to-noise ratio composite line-profile yields orbital velocities for these binaries that are accurate to 30 km/sec and allows their orbital motion to be studied at higher time resolutions. In conjunction with X-ray lightcurves, the phase-binned composite line-profiles constrain coronal structures to be small and located at high latitudes. These observations and techniques show the power of the Doppler Imaging Technique applied to X-ray line emission.

Axial Structure of High-Vacuum Planar Magnetron Discharge Space

NASA Astrophysics Data System (ADS)

Miura, Tsutomu

1999-09-01

The spatial structure of high-vacuum planar magnetron discharge is theoretically investigated taking into account the electron confinement. The boundary xes of the electron confinement region depends on BA with Ea/BA as the parameter (BA: the magnetic flux density at the anode, Ea: the average electric field strength). The location at which the frequency of ionization events takes the maximum is expressed as CnNxiep (CnN: a factor related to the electron density distribution, xiep: the distance of the location from the cathode at which the ionization is most efficient). With increasing Ea and BA at a fixed Ea/BA, the density of the confined energetic electrons increases. With increasing Ea, the region where ionization is efficient shifts to the cathode side to give a high efficiency of the magnet. The boundary xes as determined by the probe method agreed with the theoretical prediction.

Terahop and Lawrence Livermore National LaboratoryStructural Fire RF Testing

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

Haugen, P; Pratt, G

The Georgia Public Safety Training Center's Live Fire Training Facility in Forsyth, GA is a three story structure constructed of rebar-reinforced concrete wall and floors. All the door and window coverings on the building are constructed of thick, plate metal to withstand the high temperatures generated inside the building during training exercises. All of the building's walls and floors are 1-foot thick, and regular concrete columns run up along the inside of the wall increasing the thickness to 20-inches in those locations. A center concrete staircase divides the structure in half. For typical exercises, fires are started in the backmore » right corner of the building on the first floor and in the front right corner on the second floor as shown in Figure 2. Due to the high heat generated during these exercises, measured at 300 F on the floor and 700 F near the ceilings, there were limited locations at which equipment could be placed that did not incorporate heat shielding, such as the Lawrence Livermore National Laboratory's UWB system. However, upon inspection of the building, two preferable locations were identified in which equipment could be placed that would be protected from the temperature extremes generated by the fires. These locations are identified in Figure 2 as the tested TX locations. These were preferred locations because, while they protected the hardware from temperature extremes, they also force the RF transmission path through the building to cross very near the fire locations and anticipated plasma generation regions. Both of the locations listed in Figure 2 were tested by the UWB equipment and found to be suitable deployment locations to establish a solid RF link for data collection. The transmission location on the first floor was ultimately chosen for use during the actual exercises because it was accessible to the data collection team during the exercises. This allowed them to remove the hardware once the testing was complete without having to wait for the entire day of exercises to complete. Unfortunately, RF transmission directly through the central location of the fire on the first floor was not possible, so the transmission path had to be shifted approximately 6-feet off the side of the fire's center. The corner where the fire was located on the first floor was re-enforced with a mixture of concrete and metal fibers for heat resistance. This material was highly reflective, permitting very little RF energy to pass through it. This phenomenon was also observed and verified by Terahop's testing, discussed in the next section. An image of these re-enforced walls and a close up of the actual wall material containing the metal fibers can bee seen in Figure 3.« less

NEW VACUUM SOLAR TELESCOPE OBSERVATIONS OF A FLUX ROPE TRACKED BY A FILAMENT ACTIVATION

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

Yang, Shuhong; Zhang, Jun; Liu, Zhong

2014-04-01

One main goal of the New Vacuum Solar Telescope (NVST) which is located at the Fuxian Solar Observatory is to image the Sun at high resolution. Based on the high spatial and temporal resolution NVST Hα data and combined with the simultaneous observations from the Solar Dynamics Observatory for the first time, we investigate a flux rope tracked by filament activation. The filament material is initially located at one end of the flux rope and fills in a section of the rope; the filament is then activated by magnetic field cancellation. The activated filament rises and flows along helical threads,more » tracking the twisted flux rope structure. The length of the flux rope is about 75 Mm, the average width of its individual threads is 1.11 Mm, and the estimated twist is 1π. The flux rope appears as a dark structure in Hα images, a partial dark and partial bright structure in 304 Å, and as a bright structure in 171 Å and 131 Å images. During this process, the overlying coronal loops are quite steady since the filament is confined within the flux rope and does not erupt successfully. It seems that, for the event in this study, the filament is located and confined within the flux rope threads, instead of being suspended in the dips of twisted magnetic flux.« less

Growing Cobalt Silicide Columns In Silicon

NASA Technical Reports Server (NTRS)

Fathauer, Obert W.

1991-01-01

Codeposition by molecular-beam epitaxy yields variety of structures. Proposed fabrication process produces three-dimensional nanometer-sized structures on silicon wafers. Enables control of dimensions of metal and semiconductor epitaxial layers in three dimensions instead of usual single dimension (perpendicular to the plane of the substrate). Process used to make arrays of highly efficient infrared sensors, high-speed transistors, and quantum wires. For fabrication of electronic devices, both shapes and locations of columns controlled. One possible technique for doing this electron-beam lithography, see "Making Submicron CoSi2 Structures on Silicon Substrates" (NPO-17736).

33 CFR 222.6 - National Program for Inspection of Non-Federal Dams.

Code of Federal Regulations, 2011 CFR

2011-07-01

... based upon the location of the dams relative to developed areas): (i) Dams which are in the high hazard... Appreciable (Notable agriculture, industry or structures). High Urban development with more than a small... constructed by the Soil Conservation Service of the U.S. Department of Agriculture; high hazard mine tailings...

33 CFR 222.6 - National Program for Inspection of Non-Federal Dams.

Code of Federal Regulations, 2014 CFR

2014-07-01

... based upon the location of the dams relative to developed areas): (i) Dams which are in the high hazard... Appreciable (Notable agriculture, industry or structures). High Urban development with more than a small... constructed by the Soil Conservation Service of the U.S. Department of Agriculture; high hazard mine tailings...

33 CFR 222.6 - National Program for Inspection of Non-Federal Dams.

Code of Federal Regulations, 2010 CFR

2010-07-01

... based upon the location of the dams relative to developed areas): (i) Dams which are in the high hazard... Appreciable (Notable agriculture, industry or structures). High Urban development with more than a small... constructed by the Soil Conservation Service of the U.S. Department of Agriculture; high hazard mine tailings...

33 CFR 222.6 - National Program for Inspection of Non-Federal Dams.

Code of Federal Regulations, 2013 CFR

2013-07-01

... based upon the location of the dams relative to developed areas): (i) Dams which are in the high hazard... Appreciable (Notable agriculture, industry or structures). High Urban development with more than a small... constructed by the Soil Conservation Service of the U.S. Department of Agriculture; high hazard mine tailings...

33 CFR 222.6 - National Program for Inspection of Non-Federal Dams.

Code of Federal Regulations, 2012 CFR

2012-07-01

... based upon the location of the dams relative to developed areas): (i) Dams which are in the high hazard... Appreciable (Notable agriculture, industry or structures). High Urban development with more than a small... constructed by the Soil Conservation Service of the U.S. Department of Agriculture; high hazard mine tailings...

Structural Investigations of Afghanistan Deduced from Remote Sensing and Potential Field Data

NASA Astrophysics Data System (ADS)

Saibi, Hakim; Azizi, Masood; Mogren, Saad

2016-08-01

This study integrates potential gravity and magnetic field data with remotely sensed images and geological data in an effort to understand the subsurface major geological structures in Afghanistan. Integrated analysis of Landsat SRTM data was applied for extraction of geological lineaments. The potential field data were analyzed using gradient interpretation techniques, such as analytic signal (AS), tilt derivative (TDR), horizontal gradient of the tilt derivative (HG-TDR), Euler Deconvolution (ED) and power spectrum methods, and results were correlated with known geological structures. The analysis of remote sensing data and potential field data reveals the regional geological structural characteristics of Afghanistan. The power spectrum analysis of magnetic and gravity data suggests shallow basement rocks at around 1 to 1.5 km depth. The results of TDR of potential field data are in agreement with the location of the major regional fault structures and also the location of the basins and swells, except in the Helmand region (SW Afghanistan) where many high potential field anomalies are observed and attributed to batholiths and near-surface volcanic rocks intrusions. A high-resolution airborne geophysical survey in the data sparse region of eastern Afghanistan is recommended in order to have a complete image of the potential field anomalies.

High resolution seismic-reflection imaging of shallow deformation beneath the northeast margin of the Manila high at Big Lake, Arkansas

USGS Publications Warehouse

Odum, J.K.; Stephenson, W.J.; Williams, R.A.; Worley, D.M.; Guccione, M.J.; Van Arsdale, R.B.

2001-01-01

The Manila high, an elliptical area 19 km long (N-S) by 6 km wide (E-W) located west-southwest of Big Lake. Arkansas, has less than 3 m of topographic relief. Geomorphic, stratigraphic and chronology data indicate that Big Lake formed during at least two periods of Holocene uplift and subsequent damming of the south-flowing Little River. Age data of an organic mat located at the base of an upper lacustrine deposit indicates an abrupt, possibly tectonic, formation of the present Big Lake between AD 1640 and 1950. We acquired 7 km of high-resolution seismic-reflection data across the northeastern margin of the Manila high to examine its near-surface bedrock structure and possible association with underlying structures such as the Blytheville arch. Sense of displacement and character of imaged faults support interpretations for either a northwest trending, 1.5 km-wide, block of uplifted strata or a series of parallel northeast-trending faults that bound horst and graben structures. We interpret deformation of the Manila high to result from faulting generated by the reactivation of right-lateral strike-slip fault motion along this portion of the Blytheville arch. The most recent uplift of the Manila high may have occurred during the December 16, 1811, New Madrid earthquake. Published by Elsevier Science B.V.

How Deep is Shallow? Improving Absolute and Relative Locations of Upper Crustal Seismicity in Switzerland

NASA Astrophysics Data System (ADS)

Diehl, T.; Kissling, E. H.; Singer, J.; Lee, T.; Clinton, J. F.; Waldhauser, F.; Wiemer, S.

2017-12-01

Information on the structure of upper-crustal fault systems and their connection with seismicity is key to the understanding of neotectonic processes. Precisely determined focal depths in combination with structural models can provide important insight into deformation styles of the upper crust (e.g. thin- vs. versus thick-skinned tectonics). Detailed images of seismogenic fault zones in the upper crust, on the other hand, will contribute to the assessment of the hazard related to natural and induced earthquakes, especially in regions targeted for radioactive waste repositories or geothermal energy production. The complex velocity structure of the uppermost crust and unfavorable network geometries, however, often hamper precise locations (i.e. focal depth) of shallow seismicity and therefore limit tectonic interpretations. In this study we present a new high-precision catalog of absolute locations of seismicity in Switzerland. High-quality travel-time data from local and regional earthquakes in the period 2000-2017 are used to solve the coupled hypocenter-velocity structure problem in 1D. For this purpose, the well-known VELEST inversion software was revised and extended to improve the quality assessment of travel-time data and to facilitate the identification of erroneous picks in the bulletin data. Results from the 1D inversion are used as initial parameters for a 3D local earthquake tomography. Well-studied earthquakes and high-quality quarry blasts are used to assess the quality of 1D and 3D relocations. In combination with information available from various controlled-source experiments, borehole data, and geological profiles, focal depths and associated host formations are assessed through comparison with the resolved 3D velocity structure. The new absolute locations and velocity models are used as initial values for relative double-difference relocation of earthquakes in Switzerland. Differential times are calculated from bulletin picks and waveform cross-correlation. The resulting double-difference catalog is used as a regional background catalog for a real-time double-difference approach. We will present our implementation strategy and test its performance for local applications using examples from well-recorded natural and induced earthquake sequences in Switzerland.

Design and Application of a High Sensitivity Piezoresistive Pressure Sensor for Low Pressure Conditions

PubMed Central

Yu, Huiyang; Huang, Jianqiu

2015-01-01

In this paper, a pressure sensor for low pressure detection (0.5 kPa–40 kPa) is proposed. In one structure (No. 1), the silicon membrane is partly etched to form a crossed beam on its top for stress concentration. An aluminum layer is also deposited as part of the beam. Four piezoresistors are fabricated. Two are located at the two ends of the beam. The other two are located at the membrane periphery. Four piezoresistors connect into a Wheatstone bridge. To demonstrate the stress concentrate effect of this structure, two other structures were designed and fabricated. One is a flat membrane structure (No. 2), the other is a structure with the aluminum beam, but without etched silicon (No. 3). The measurement results of these three structures show that the No.1 structure has the highest sensitivity, which is about 3.8 times that of the No. 2 structure and 2.7 times that of the No. 3 structure. They also show that the residual stress in the beam has some backside effect on the sensor performance. PMID:26371001

Luminance gradient at object borders communicates object location to the human oculomotor system.

PubMed

Kilpeläinen, Markku; Georgeson, Mark A

2018-01-25

The locations of objects in our environment constitute arguably the most important piece of information our visual system must convey to facilitate successful visually guided behaviour. However, the relevant objects are usually not point-like and do not have one unique location attribute. Relatively little is known about how the visual system represents the location of such large objects as visual processing is, both on neural and perceptual level, highly edge dominated. In this study, human observers made saccades to the centres of luminance defined squares (width 4 deg), which appeared at random locations (8 deg eccentricity). The phase structure of the square was manipulated such that the points of maximum luminance gradient at the square's edges shifted from trial to trial. The average saccade endpoints of all subjects followed those shifts in remarkable quantitative agreement. Further experiments showed that the shifts were caused by the edge manipulations, not by changes in luminance structure near the centre of the square or outside the square. We conclude that the human visual system programs saccades to large luminance defined square objects based on edge locations derived from the points of maximum luminance gradients at the square's edges.

Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007-09

USGS Publications Warehouse

Rydlund, Jr., Paul H.

2009-01-01

Scour and depositional responses to hydrologic events have been important to the scientific community studying sediment transport as well as potential effects on bridges and other hydraulic structures within riverine systems. A river channel-bed monitor composed of a single-beam transducer was installed on a bridge crossing the Chariton River near Prairie Hill, Missouri (structure L-344) as a pilot study to evaluate channel-bed change in response to the hydrologic condition disseminated from an existing streamgage. Initial results at this location led to additional installations in cooperation with the Missouri Department of Transportation at an upstream Chariton River streamgage location at Novinger, Missouri (structure L-534) and a Mississippi River streamgage location near Mehlville, Missouri (structures A-1850 and A-4936). In addition to stage, channel-bed elevation was collected at all locations every 15 minutes and transmitted hourly to a U.S. Geological Survey database. Bed elevation data for the Chariton River location at Novinger and the Mississippi River location near Mehlville were provided to the World Wide Web for real-time monitoring. Channel-bed data from the three locations indicated responses to hydrologic events depicted in the stage record; however, notable bedforms apparent during inter-event flows also may have affected the relation of scour and deposition to known hydrologic events. Throughout data collection periods, Chariton River locations near Prairie Hill and Novinger reflected bed changes as much as 13 feet and 5 feet. Nearly all of the bed changes correlated well with the hydrographic record at these locations. The location at the Mississippi River near Mehlville indicated a much more stable channel bed throughout the data collection period. Despite missing data resulting from damage to one of the river channel-bed monitors from ice accumulation at the upstream nose of the bridge pier early in the record, the record from the downstream river channel-bed monitor demonstrated a good correlation (regardless of a 7 percent high bias) between bedform movement and the presence of bedforms surrounding the bridge as indicated by coincident bathymetric surveys using multibeam sonar.

46 CFR 177.410 - Structural fire protection.

Code of Federal Regulations, 2013 CFR

2013-10-01

... not considered high fire hazards areas (galleys) as long as they do not contain medium to high heat... must be located as far as practical from heat sources. Internal combustion engine exhausts, boiler and... be lined with noncombustible panels or insulation approved in accordance with § 164.009 in subchapter...

46 CFR 177.410 - Structural fire protection.

Code of Federal Regulations, 2010 CFR

2010-10-01

... considered high fire hazards areas (galleys) as long as they do not contain medium to high heat appliances... must be located as far as practical from heat sources. Internal combustion engine exhausts, boiler and... be lined with noncombustible panels or insulation approved in accordance with § 164.009 in subchapter...

46 CFR 177.410 - Structural fire protection.

Code of Federal Regulations, 2011 CFR

2011-10-01

... considered high fire hazards areas (galleys) as long as they do not contain medium to high heat appliances... must be located as far as practical from heat sources. Internal combustion engine exhausts, boiler and... be lined with noncombustible panels or insulation approved in accordance with § 164.009 in subchapter...

46 CFR 177.410 - Structural fire protection.

Code of Federal Regulations, 2012 CFR

2012-10-01

... considered high fire hazards areas (galleys) as long as they do not contain medium to high heat appliances... must be located as far as practical from heat sources. Internal combustion engine exhausts, boiler and... be lined with noncombustible panels or insulation approved in accordance with § 164.009 in subchapter...

46 CFR 177.410 - Structural fire protection.

Code of Federal Regulations, 2014 CFR

2014-10-01

... not considered high fire hazards areas (galleys) as long as they do not contain medium to high heat... must be located as far as practical from heat sources. Internal combustion engine exhausts, boiler and... be lined with noncombustible panels or insulation approved in accordance with § 164.009 in subchapter...

A semiparametric spatio-temporal model for solar irradiance data

DOE PAGES

Patrick, Joshua D.; Harvill, Jane L.; Hansen, Clifford W.

2016-03-01

Here, we evaluate semiparametric spatio-temporal models for global horizontal irradiance at high spatial and temporal resolution. These models represent the spatial domain as a lattice and are capable of predicting irradiance at lattice points, given data measured at other lattice points. Using data from a 1.2 MW PV plant located in Lanai, Hawaii, we show that a semiparametric model can be more accurate than simple interpolation between sensor locations. We investigate spatio-temporal models with separable and nonseparable covariance structures and find no evidence to support assuming a separable covariance structure. These results indicate a promising approach for modeling irradiance atmore » high spatial resolution consistent with available ground-based measurements. Moreover, this kind of modeling may find application in design, valuation, and operation of fleets of utility-scale photovoltaic power systems.« less

High-resolution x-ray absorption spectroscopy studies of metal compounds in neurodegenerative brain tissue

NASA Astrophysics Data System (ADS)

Collingwood, J. F.; Mikhaylova, A.; Davidson, M. R.; Batich, C.; Streit, W. J.; Eskin, T.; Terry, J.; Barrea, R.; Underhill, R. S.; Dobson, J.

2005-01-01

Fluorescence mapping and microfocus X-ray absorption spectroscopy are used to detect, locate and identify iron biominerals and other inorganic metal accumulations in neurodegenerative brain tissue at sub-cellular resolution (<5 microns). Recent progress in developing the technique is reviewed. Synchrotron X-rays are used to map tissue sections for metals of interest, and XANES and XAFS are used to characterise anomalous concentrations of the metals in-situ so that they can be correlated with tissue structures and disease pathology. Iron anomalies associated with biogenic magnetite, ferritin and haemoglobin are located and identified in an avian tissue model with a pixel resolution ~5 microns. Subsequent studies include brain tissue sections from transgenic Huntington's mice, and the first high-resolution mapping and identification of iron biominerals in human Alzheimer's and control autopsy brain tissue. Technical developments include use of microfocus diffraction to obtain structural information about biominerals in-situ, and depositing sample location grids by lithography for the location of anomalies by conventional microscopy. The combined techniques provide a breakthrough in the study of both intra- and extra-cellular iron compounds and related metals in tissue. The information to be gained from this approach has implications for future diagnosis and treatment of neurodegeneration, and for our understanding of the mechanisms involved.

Moose (Alces alces) reacts to high summer temperatures by utilizing thermal shelters in boreal forests - an analysis based on airborne laser scanning of the canopy structure at moose locations.

PubMed

Melin, Markus; Matala, Juho; Mehtätalo, Lauri; Tiilikainen, Raisa; Tikkanen, Olli-Pekka; Maltamo, Matti; Pusenius, Jyrki; Packalen, Petteri

2014-04-01

The adaptation of different species to warming temperatures has been increasingly studied. Moose (Alces alces) is the largest of the ungulate species occupying the northern latitudes across the globe, and in Finland it is the most important game species. It is very well adapted to severe cold temperatures, but has a relatively low tolerance to warm temperatures. Previous studies have documented changes in habitat use by moose due to high temperatures. In many of these studies, the used areas have been classified according to how much thermal cover they were assumed to offer based on satellite/aerial imagery data. Here, we identified the vegetation structure in the areas used by moose under different thermal conditions. For this purpose, we used airborne laser scanning (ALS) data extracted from the locations of GPS-collared moose. This provided us with detailed information about the relationships between moose and the structure of forests it uses in different thermal conditions and we were therefore able to determine and differentiate between the canopy structures at locations occupied by moose during different thermal conditions. We also discovered a threshold beyond which moose behaviour began to change significantly: as day temperatures began to reach 20 °C and higher, the search for areas with higher and denser canopies during daytime became evident. The difference was clear when compared to habitat use at lower temperatures, and was so strong that it provides supporting evidence to previous studies, suggesting that moose are able to modify their behaviour to cope with high temperatures, but also that the species is likely to be affected by warming climate. © 2013 John Wiley & Sons Ltd.

A new methodology for automating acoustic emission detection of metallic fatigue fractures in highly demanding aerospace environments: An overview

NASA Astrophysics Data System (ADS)

Holford, Karen M.; Eaton, Mark J.; Hensman, James J.; Pullin, Rhys; Evans, Sam L.; Dervilis, Nikolaos; Worden, Keith

2017-04-01

The acoustic emission (AE) phenomenon has many attributes that make it desirable as a structural health monitoring or non-destructive testing technique, including the capability to continuously and globally monitor large structures using a sparse sensor array and with no dependency on defect size. However, AE monitoring is yet to fulfil its true potential, due mainly to limitations in location accuracy and signal characterisation that often arise in complex structures with high levels of background noise. Furthermore, the technique has been criticised for a lack of quantitative results and the large amount of operator interpretation required during data analysis. This paper begins by introducing the challenges faced in developing an AE based structural health monitoring system and then gives a review of previous progress made in addresing these challenges. Subsequently an overview of a novel methodology for automatic detection of fatigue fractures in complex geometries and noisy environments is presented, which combines a number of signal processing techniques to address the current limitations of AE monitoring. The technique was developed for monitoring metallic landing gear components during pre-flight certification testing and results are presented from a full-scale steel landing gear component undergoing fatigue loading. Fracture onset was successfully identify automatically at 49,000 fatigue cycles prior to final failure (validated by the use of dye penetrant inspection) and the fracture position was located to within 10 mm of the actual location.

Selection of actuator locations for static shape control of large space structures by heuristic integer programing

NASA Technical Reports Server (NTRS)

Haftka, R. T.; Adelman, H. M.

1984-01-01

Orbiting spacecraft such as large space antennas have to maintain a highly accurate space to operate satisfactorily. Such structures require active and passive controls to mantain an accurate shape under a variety of disturbances. Methods for the optimum placement of control actuators for correcting static deformations are described. In particular, attention is focused on the case were control locations have to be selected from a large set of available sites, so that integer programing methods are called for. The effectiveness of three heuristic techniques for obtaining a near-optimal site selection is compared. In addition, efficient reanalysis techniques for the rapid assessment of control effectiveness are presented. Two examples are used to demonstrate the methods: a simple beam structure and a 55m space-truss-parabolic antenna.

Structural monitoring for rare events in remote locations

NASA Astrophysics Data System (ADS)

Hale, J. M.

2005-01-01

A structural monitoring system has been developed for use on high value engineering structures, which is particularly suitable for use in remote locations where rare events such as accidental impacts, seismic activity or terrorist attack might otherwise go undetected. The system comprises a low power intelligent on-site data logger and a remote analysis computer that communicate with one another using the internet and mobile telephone technology. The analysis computer also generates e-mail alarms and maintains a web page that displays detected events in near real-time to authorised users. The application of the prototype system to pipeline monitoring is described in which the analysis of detected events is used to differentiate between impacts and pressure surges. The system has been demonstrated successfully and is ready for deployment.

Early Opening of Seychelles and India: the Gop Basin Revisited

NASA Astrophysics Data System (ADS)

Dyment, J.; Vadakkeyakath, Y.; Bhattacharya, G.

2012-12-01

The deep offshore region located between the India-Pakistan continental margin and the Laxmi Ridge continental sliver contains valuable imprints of the early oceanic opening phase between India and the Seychelles. The acquisition of wide-angle deep seismic data by British scientists in 2003 provided new information about the deep structure and nature of the crust [1,2]. These data complement the large amount of seismic reflection profiles, altimetry-derived gravity and marine magnetic data which allow mapping the structure and determining the age of the oceanic crust [3,4,5]. Although these authors all agree on the oceanic nature of the Gop Basin, they surprisingly differ on the extent of the oceanic crust, the location of the extinct spreading center and the age of the basin. Here we re-evaluate published interpretations of the Gop Basin in light of all available data. The major discrepancy between [1,2,4] and [5] is the location of the extinct spreading center. [1,2,4] place it on an unnamed basement high located at 19°55'N, whereas [5] identify it with the Palitana Ridge at 19°25'N. Checking the location of the basement high of [1,2,4] on the basement isobath map of [3], based on many seismic reflection profiles, reveals that this basement high actually is an isolated feature of limited extent, which at best can be considered as part of a NE-SW trending basement high zone. This basement high locally coincides with a strong positive magnetic anomaly and a narrow gravity anomaly low but the trend of these anomalies is E-W, in contrast to the NE-SW trend of the basement in this area. For these reasons, this basement high probably is not the location of the Gop Basin extinct spreading center. Conversely, on the basement isobath map of [3], the Palitana Ridge appears as a prominent E-W high, located in the middle of a broad E-W graben, the Gop Basin. It extends over 200 km and is flanked on both sides by basement 2000 m deeper. On free air gravity anomaly maps, the Palitana Ridge lies in the center of the broad gravity high that delineates the Gop Basin. It corresponds, to the west, to a narrow gravity low, a typical signature of fossil spreading centers. The crustal structure determined by the wide angle seismic data of [1,2] shows that the base of the lower crust, the best seismically constrained interface (according to the ray diagram of [1]), is flat in the Arabian Basin, deeper under the Laxmi Ridge, shallower in the Gop Basin under the Palitana Ridge, and deeper again further north. For these reasons, the Palitana Ridge probably is the location of the Gop Basin extinct spreading centre. Further, the Gop Basin, being narrow, does not exhibit long sequences of magnetic anomalies, thereby making their interpretation difficult. Many models may fit the observed anomalies, so [4] and [5] each proposed different hypotheses. We note, however, that [4] consider a plausible (and preferred) model with "initial" spreading rates, i.e. just after break up, as fast as 68 mm/yr half-rate, which implies the Gop Basin to form in 1 Myr. Such a fast initial rate appears unrealistic, considering that initial spreading rates are usually much slower, about one fourth of that rate. [1] Minshull et al., Nature Geo., 2008 [2] Collier et al., JGR, 2009 [3] Malod et al., Tectonophys., 1997 [4] Collier et al., EPSL, 2008 [5] Yatheesh et al., EPSL, 2009

Convergence of topological domain boundaries, insulators, and polytene interbands revealed by high-resolution mapping of chromatin contacts in the early Drosophila melanogaster embryo

PubMed Central

Stadler, Michael R; Haines, Jenna E

2017-01-01

High-throughput assays of three-dimensional interactions of chromosomes have shed considerable light on the structure of animal chromatin. Despite this progress, the precise physical nature of observed structures and the forces that govern their establishment remain poorly understood. Here we present high resolution Hi-C data from early Drosophila embryos. We demonstrate that boundaries between topological domains of various sizes map to DNA elements that resemble classical insulator elements: short genomic regions sensitive to DNase digestion that are strongly bound by known insulator proteins and are frequently located between divergent promoters. Further, we show a striking correspondence between these elements and the locations of mapped polytene interband regions. We believe it is likely this relationship between insulators, topological boundaries, and polytene interbands extends across the genome, and we therefore propose a model in which decompaction of boundary-insulator-interband regions drives the organization of interphase chromosomes by creating stable physical separation between adjacent domains. PMID:29148971

Delta-configurations - Flare activity and magnetic-field structure

NASA Technical Reports Server (NTRS)

Patty, S. R.; Hagyard, M. J.

1986-01-01

Complex sunspots in four active regions of April and May 1980, all exhibiting regions of magnetic classification delta, were studied using data from the NASA Marshall Space Flight Center vector magnetograph. The vector magnetic field structure in the vicinity of each delta was determined, and the location of the deltas in each active region was correlated with the locations and types of flare activity for the regions. Two types of delta-configuration were found to exist, active and inactive, as defined by the relationships between magnetic field structure and activity. The active delta exhibited high flare activity, strong horizontal gradients of the longitudinal (line-of-sight) magnetic field component, a strong transverse (perpendicular to line-of-sight) component, and a highly nonpotential orientation of the photospheric magnetic field, all indications of a highly sheared magnetic field. The inactive delta, on the other hand, exhibited little or no flare production, weaker horizontal gradients of the longitudinal component, weaker transverse components, and a nearly potential, nonsheared orientation of the magnetic field. It is concluded that the presence of such sheared fields is the primary signature by which the active delta may be distinguished, and that it is this shear which produces the flare activity of the active delta.

Controls of repeating earthquakes' location from a- and b- values imaging

NASA Astrophysics Data System (ADS)

Chen, K. H.; Kawamura, M.

2017-12-01

The locations where creeping and locked fault areas abut have commonly found to be delineated by the foci of small repeating earthquakes (REs). REs not only represent the finer structure of high creep-rate location, they also function as fault slip-rate indicators. Knowledge of the expected location of REs therefore, is crucial for fault deformation monitoring and assessment of earthquake potential. However, a precise description of factors determining REs locations is lacking. To explore where earthquakes tend to recur, we statistically investigated repeating earthquake catalogs and background seismicity from different regions including six fault segments in California and Taiwan. We show that the location of repeating earthquakes can be mapped using the spatial distribution of the seismic a- and b-values obtained from the background seismicity. Molchan's error diagram statistically confirmed that repeating earthquakes occur within areas with high a-values (2.8-3.8) and high b-values (0.9-1.1) on both strike-slip and thrust fault segments. However, no significant association held true for fault segments with more complicated geometry or for wider areas with a complex fault network. The productivity of small earthquakes responsible for high a- and b-values may thus be the most important factor controlling the location of repeating earthquakes. We hypothesize that, given that the deformation conditions within a fault zone are suitable for a planar fault plane, the location of repeating earthquakes can be best described by a-value 3 and b-value 1. This feature of a- and b-values may be useful for foresee the location of REs for measuring creep rate at depth. Further investigation of REs-rich areas may allow testing of this hypothesis.

Evaluation of lightning accommodation systems for wind-driven turbine rotors

NASA Technical Reports Server (NTRS)

Bankaitis, H.

1982-01-01

Wind-driven turbine generators are being evaluated as an alternative source of electric energy. Areas of favorable location for the wind-driven turbines (high wind density) coincide with areas of high incidence of thunderstorm activity. These locations, coupled with the 30-m or larger diameter rotor blades, make the wind-driven turbine blades probable terminations for lightning strikes. Several candidate systems of lightning accommodation for composite-structural-material blades were designed and their effectiveness evaluated by submitting the systems to simulated lightning strikes. The test data were analyzed and system design were reviewed on the basis of the analysis.

A robust statistical estimation (RoSE) algorithm jointly recovers the 3D location and intensity of single molecules accurately and precisely

NASA Astrophysics Data System (ADS)

Mazidi, Hesam; Nehorai, Arye; Lew, Matthew D.

2018-02-01

In single-molecule (SM) super-resolution microscopy, the complexity of a biological structure, high molecular density, and a low signal-to-background ratio (SBR) may lead to imaging artifacts without a robust localization algorithm. Moreover, engineered point spread functions (PSFs) for 3D imaging pose difficulties due to their intricate features. We develop a Robust Statistical Estimation algorithm, called RoSE, that enables joint estimation of the 3D location and photon counts of SMs accurately and precisely using various PSFs under conditions of high molecular density and low SBR.

Spatial and temporal changes in household structure locations using high-resolution satellite imagery for population assessment: an analysis in southern Zambia, 2006-2011.

PubMed

Shields, Timothy; Pinchoff, Jessie; Lubinda, Jailos; Hamapumbu, Harry; Searle, Kelly; Kobayashi, Tamaki; Thuma, Philip E; Moss, William J; Curriero, Frank C

2016-05-31

Satellite imagery is increasingly available at high spatial resolution and can be used for various purposes in public health research and programme implementation. Comparing a census generated from two satellite images of the same region in rural southern Zambia obtained four and a half years apart identified patterns of household locations and change over time. The length of time that a satellite image-based census is accurate determines its utility. Households were enumerated manually from satellite images obtained in 2006 and 2011 of the same area. Spatial statistics were used to describe clustering, cluster detection, and spatial variation in the location of households. A total of 3821 household locations were enumerated in 2006 and 4256 in 2011, a net change of 435 houses (11.4% increase). Comparison of the images indicated that 971 (25.4%) structures were added and 536 (14.0%) removed. Further analysis suggested similar household clustering in the two images and no substantial difference in concentration of households across the study area. Cluster detection analysis identified a small area where significantly more household structures were removed than expected; however, the amount of change was of limited practical significance. These findings suggest that random sampling of households for study participation would not induce geographic bias if based on a 4.5-year-old image in this region. Application of spatial statistical methods provides insights into the population distribution changes between two time periods and can be helpful in assessing the accuracy of satellite imagery.

Proteome approaches to characterize seed storage proteins related to ditelocentric chromosomes in common wheat (Triticum aestivum L.).

PubMed

Islam, Nazrul; Woo, Sun-Hee; Tsujimoto, Hisashi; Kawasaki, Hiroshi; Hirano, Hisashi

2002-09-01

Changes in protein composition of wheat endosperm proteome were investigated in 39 ditelocentric chromosome lines of common wheat (Triticum aestivum L.) cv. Chinese Spring. Two-dimensional gel electrophoresis followed by Coomassie Brilliant Blue staining has resolved a total of 105 protein spots in a gel. Quantitative image analysis of protein spots was performed by PDQuest. Variations in protein spots between the euploid and the 39 ditelocentric lines were evaluated by spot number, appearance, disappearance and intensity. A specific spot present in all gels was taken as an internal standard, and the intensity of all other spots was calculated as the ratio of the internal standard. Out of the 1755 major spots detected in 39 ditelocentric lines, 1372 (78%) spots were found variable in different spot parameters: 147 (11%) disappeared, 978 (71%) up-regulated and 247 (18%) down-regulated. Correlation studies in changes in protein intensities among 24 protein spots across the ditelocentric lines were performed. High correlations in changes of protein intensities were observed among the proteins encoded by genes located in the homoeologous arms. Locations of structural genes controlling 26 spots were identified in 10 chromosomal arms. Multiple regulators of the same protein located at various chromosomal arms were also noticed. Identification of structural genes for most of the proteins was found difficult due to multiple regulators encoding the same protein. Two novel subunits (1B(Z,) 1BDz), the structure of which are very similar to the high molecular weight glutenin subunit 12, were identified, and the chromosome arm locations of these subunits were assigned.

Conceptual design of new metrology laboratories for the National Physical Laboratory, United Kingdom

NASA Astrophysics Data System (ADS)

Manning, Christopher J.

1994-10-01

The National Physical Laboratory is planning to house the Division of Mechanical and Optical Metrology and the Division of Material Metrology in a new purpose built laboratory building on its site at Teddington, London, England. The scientific staff were involved in identifying and agreeing the vibration performance requirements of the conceptual design. This was complemented by an extensive surgery of vibration levels within the existing facilities and ambient vibration studies at the proposed site. At one end of the site there is significant vibration input from road traffic. Some of the test equipment is also in itself a source of vibration input. These factors, together with normal occupancy inputs, footfalls and door slams, and a highly serviced building led to vibration being dominant in influencing the structural form. The resulting structural concept comprises three separate structural elements for vibration and geotechnical reasons. The laboratories most sensitive to disturbance by vibration are located at the end of the site farthest from local roads on a massive ground bearing slab. Less sensitive laboratories and those containing vibration sources are located on a massive slab in deep, piled foundations. A common central plant area is located alongside on its own massive slab. Medium sensitivity laboratories and offices are located at first floor level on a reinforced concrete suspended floor of maximum stiffness per unit mass. The whole design has been such as to permit upgrading of areas, eg office to laboratory; laboratory to `high sensitivity' laboratory, to cater for changes in future use of the building.

SU-E-T-170: Characterization of the Location, Extent, and Proximity to Critical Structures of Target Volumes Provides Detail for Improved Outcome Predictions Among Pancreatic Cancer Patients

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

Cheng, Z; Moore, J; Rosati, L

Purpose: In radiotherapy, size, location and proximity of the target to critical structures influence treatment decisions. It has been shown that proximity of the target predicts dosimetric sparing of critical structures. In addition to dosimetry, precise location of disease has further implications such as tumor invasion, or proximity to major arteries that inhibit surgery. Knowledge of which patients can be converted to surgical candidates by radiation may have high impact on future treat/no-treat decisions. We propose a method to improve our characterization of the location of pancreatic cancer and treatment volume extent with respect to nearby arteries with the goalmore » of developing features to improve clinical predictions and decisions. Methods: Oncospace is a local learning health system that systematically captures clinical outcomes and all aspects of radiotherapy treatment plans, including overlap volume histograms (OVH) – a measure of spatial relationships between two structures. Minimum and maximum distances of PTV and OARs based on OVH, PTV volume, anatomic location by ICD-9 code, and surgical outcome were queried. Normalized distance to center from the left and right kidney was calculated to indicate tumor location and laterality. Distance to critical arteries (celiac, superior mesenteric, common hepatic) is validated by surgical status (borderline resectable, locally advanced converted to resectable). Results: There were 205 pancreas stereotactic body radiotherapy patients treated from 2009–2015 queried. Location/laterality of tumor based on kidney OVH show strong trends between location by OVH and by ICD-9. Compared to the locally advanced group, the borderline resectable group showed larger geometrical distance from critical arteries (p=0.03). Conclusion: Our platform enabled analysis of shape/size-location relationships. These data suggest that PTV volume and attention to distance between PTVs and surrounding OARs and major arteries may be promising for improving characterization of treatment anatomy that can refine our ability for outcome predictions and decision making. Elekta, Toshiba.« less

Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors.

PubMed

Jenkins, R Brian; Joyce, Peter; Mechtel, Deborah

2017-01-27

Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay.

Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors

PubMed Central

Jenkins, R. Brian; Joyce, Peter; Mechtel, Deborah

2017-01-01

Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay. PMID:28134815

Structure and function of methanotrophic communities in a landfill-cover soil.

PubMed

Henneberger, Ruth; Lüke, Claudia; Mosberger, Lona; Schroth, Martin H

2012-07-01

In landfill-cover soils, aerobic methane-oxidizing bacteria (MOB) convert CH(4) to CO(2), mitigating emissions of the greenhouse gas CH(4) to the atmosphere. We investigated overall MOB community structure and assessed spatial differences in MOB diversity, abundance and activity in a Swiss landfill-cover soil. Molecular cloning, terminal restriction-fragment length polymorphism (T-RFLP) and quantitative PCR of pmoA genes were applied to soil collected from 16 locations at three different depths to study MOB community structure, diversity and abundance; MOB activity was measured in the field using gas push-pull tests. The MOB community was highly diverse but dominated by Type Ia MOB, with novel pmoA sequences present. Type II MOB were detected mainly in deeper soil with lower nutrient and higher CH(4) concentrations. Substantial differences in MOB community structure were observed between one high- and one low-activity location. MOB abundance was highly variable across the site [4.0 × 10(4) to 1.1 × 10(7) (g soil dry weight)(-1)]. Potential CH(4) oxidation rates were high [1.8-58.2 mmol CH(4) (L soil air)(-1) day(-1) ] but showed significant lateral variation and were positively correlated with mean CH(4) concentrations (P < 0.01), MOB abundance (P < 0.05) and MOB diversity (weak correlation, P < 0.17). Our findings indicate that Methylosarcina and closely related MOB are key players and that MOB abundance and community structure are driving factors in CH(4) oxidation at this landfill. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Correlation Between Interphase Chromatin Structure and - and High-Let Radiation-Induced - and Intra-Chromosome Exchange Hotspots

NASA Astrophysics Data System (ADS)

Zhang, Ye; Wu, Honglu; Mangala, Lingegowda; Asaithamby, Aroumougame; Chen, David

2012-07-01

CORRELATION BETWEEN INTERPHASE CHROMATIN STRUCTURE AND LOW- AND HIGH-LET RADIATION-INDUCED INTER- AND INTRA-CHROMOSOME EXCHANGE HOTSPOTS Ye Zhang1,2, Lingegowda S. Mangala1,3, Aroumougame Asaithamby4, David J. Chen4, and Honglu Wu1 1 NASA Johnson Space Center, Houston, Texas, USA 2 Wyle Integrated Science and Engineering Group, Houston, Texas, USA 3 University of Houston Clear Lake, Houston, Texas, USA 4 University of Texas, Southwestern Medical Center, Dallas, Texas, USA To investigate the relationship between chromosome aberrations induced by low- and high-LET radiation and chromatin folding, we reconstructed the three dimensional structure of chromosome 3 and measured the physical distances between different regions of this chromosome. Previously, we investigated the location of breaks involved in inter- and intrachromosomal type exchange events in chromosome 3 of human epithelial cells, using the multicolor banding in situ hybridization (mBAND) technique. After exposure to both low- and high-LET radiations in vitro, intra-chromosome exchanges occurred preferentially between a break in the 3p21 and one in the 3q11 regions, and the breaks involved in inter-chromosome exchanges occurred in two regions near the telomeres of the chromosome. In this study, human epithelial cells were fixed in G1 phase and interphase chromosomes hybridized with an mBAND probe for chromosome 3 were captured with a laser scanning confocal microscope. The 3-dimensional structure of interphase chromosome 3 with different colored regions was reconstructed, and the distance between different regions was measured. We show that, in most of the G1 cells, the regions containing 3p21 and 3q11 are colocalized in the center of the chromosome domain, whereas, the regions towards the telomeres of the chromosome are located in the peripherals of the chromosome domain. Our results demonstrate that the distribution of breaks involved in radiation-induced inter and intra-chromosome aberrations depends upon both the location of fragile sites and the folding of chromatins.

Spatial Heterogeneity as a Genetic Mixing Mechanism in Highly Philopatric Colonial Seabirds

PubMed Central

Cristofari, Robin; Trucchi, Emiliano; Whittington, Jason D.; Vigetta, Stéphanie; Gachot-Neveu, Hélène; Stenseth, Nils Christian; Le Maho, Yvon; Le Bohec, Céline

2015-01-01

How genetic diversity is maintained in philopatric colonial systems remains unclear, and understanding the dynamic balance of philopatry and dispersal at all spatial scales is essential to the study of the evolution of coloniality. In the King penguin, Aptenodytes patagonicus, return rates of post-fledging chicks to their natal sub-colony are remarkably high. Empirical studies have shown that adults return year after year to their previous breeding territories within a radius of a few meters. Yet, little reliable data are available on intra- and inter-colonial dispersal in this species. Here, we present the first fine-scale study of the genetic structure in a king penguin colony in the Crozet Archipelago. Samples were collected from individual chicks and analysed at 8 microsatellite loci. Precise geolocation data of hatching sites and selective pressures associated with habitat features were recorded for all sampling locations. We found that despite strong natal and breeding site fidelity, king penguins retain a high degree of panmixia and genetic diversity. Yet, genetic structure appears markedly heterogeneous across the colony, with higher-than-expected inbreeding levels, and local inbreeding and relatedness hotspots that overlap predicted higher-quality nesting locations. This points towards heterogeneous population structure at the sub-colony level, in which fine-scale environmental features drive local philopatric behaviour, while lower-quality patches may act as genetic mixing mechanisms at the colony level. These findings show how a lack of global genetic structuring can emerge from small-scale heterogeneity in ecological parameters, as opposed to the classical model of homogeneous dispersal. Our results also emphasize the importance of sampling design for estimation of population parameters in colonial seabirds, as at high spatial resolution, basic genetic features are shown to be location-dependent. Finally, this study stresses the importance of understanding intra-colonial dispersal and genetic mixing mechanisms in order to better estimate species-wide gene flows and population dynamics. PMID:25680103

Spatial heterogeneity as a genetic mixing mechanism in highly philopatric colonial seabirds.

PubMed

Cristofari, Robin; Trucchi, Emiliano; Whittington, Jason D; Vigetta, Stéphanie; Gachot-Neveu, Hélène; Stenseth, Nils Christian; Le Maho, Yvon; Le Bohec, Céline

2015-01-01

How genetic diversity is maintained in philopatric colonial systems remains unclear, and understanding the dynamic balance of philopatry and dispersal at all spatial scales is essential to the study of the evolution of coloniality. In the King penguin, Aptenodytes patagonicus, return rates of post-fledging chicks to their natal sub-colony are remarkably high. Empirical studies have shown that adults return year after year to their previous breeding territories within a radius of a few meters. Yet, little reliable data are available on intra- and inter-colonial dispersal in this species. Here, we present the first fine-scale study of the genetic structure in a king penguin colony in the Crozet Archipelago. Samples were collected from individual chicks and analysed at 8 microsatellite loci. Precise geolocation data of hatching sites and selective pressures associated with habitat features were recorded for all sampling locations. We found that despite strong natal and breeding site fidelity, king penguins retain a high degree of panmixia and genetic diversity. Yet, genetic structure appears markedly heterogeneous across the colony, with higher-than-expected inbreeding levels, and local inbreeding and relatedness hotspots that overlap predicted higher-quality nesting locations. This points towards heterogeneous population structure at the sub-colony level, in which fine-scale environmental features drive local philopatric behaviour, while lower-quality patches may act as genetic mixing mechanisms at the colony level. These findings show how a lack of global genetic structuring can emerge from small-scale heterogeneity in ecological parameters, as opposed to the classical model of homogeneous dispersal. Our results also emphasize the importance of sampling design for estimation of population parameters in colonial seabirds, as at high spatial resolution, basic genetic features are shown to be location-dependent. Finally, this study stresses the importance of understanding intra-colonial dispersal and genetic mixing mechanisms in order to better estimate species-wide gene flows and population dynamics.

Genetic structure and gene flow among European corn borer populations from the Great Plains to the Appalachians of North America

EPA Science Inventory

Earlier population genetic spatial analysis of European corn borer, Ostrinia nubilalis (Hubner), indicated no genetic differentiation even between locations separated by 720 km. This result suggests either high dispersal resulting in high gene flow, or that populations are not in...

Placement Assistance Services: Procedures Manual. S.P.A.C.E. Student Placement and Counseling Effort.

ERIC Educational Resources Information Center

Irvin, Donald E.; Galey, Stephen B.

This manual represents an attempt to develop a model and procedures for implementing career planning and placement assistance services in Minnesota high schools. The procedures described were developed for and tested in four participating high schools of different sizes, administrative structures, and geographic locations. Divided into seven…

The effect of ground borne vibrations from high speed train on overhead line equipment (OHLE) structure considering soil-structure interaction.

PubMed

Ngamkhanong, Chayut; Kaewunruen, Sakdirat

2018-06-15

At present, railway infrastructure experiences harsh environments and aggressive loading conditions from increased traffic and load demands. Ground borne vibration has become one of these environmental challenges. Overhead line equipment (OHLE) provides electric power to the train and is, for one or two tracks, normally supported by cantilever masts. A cantilever mast, which is made of H-section steel, is slender and has a poor dynamic behaviour by nature. It can be seen from the literature that ground borne vibrations cause annoyance to people in surrounding areas especially in buildings. Nonetheless, mast structures, which are located nearest and alongside the railway track, have not been fully studied in terms of their dynamic behaviour. This paper presents the effects of ground borne vibrations generated by high speed trains on cantilever masts and contact wire located alongside railway tracks. Ground borne vibration velocities at various train speeds, from 100 km/h to 300 km/h, are considered based on the consideration of semi-empirical models for predicting low frequency vibration on ground. A three-dimensional mast structure with varying soil stiffness is made using a finite element model. The displacement measured is located at the end of cantilever mast which is the position of contact wire. The construction tolerance of contact stagger is used as an allowable movement of contact wire in transverse direction. The results show that the effect of vibration velocity from train on the transverse direction of mast structure is greater than that on the longitudinal direction. Moreover, the results obtained indicate that the ground bourn vibrations caused by high speed train are not strong enough to cause damage to the contact wire. The outcome of this study will help engineers improve the design standard of cantilever mast considering the effect of ground borne vibration as preliminary parameter for construction tolerances. Copyright © 2018 Elsevier B.V. All rights reserved.

Continuous cryopump with a method for removal of solidified gases

DOEpatents

Carlson, Larry W.; Herman, Harold

1989-01-01

An improved cryopump for the removal of gases from a high vacuum, comprising a cryopanel incorporating honeycomb structure, refrigerant means thermally connected to the cryopanel, and a rotatable channel moving azimuthally around an axis located near the center of the cryopanel, removing gases absorbed within the honeycomb structure by subliming them and conducting them outside the vacuum vessel.

Continuous cryopump with a method for removal of solidified gases

DOEpatents

Carlson, L.W.; Herman, H.

1988-05-05

An improved cryopump for the removal of gases from a high vacuum, comprising a cryopanel incorporating honeycomb structure, refrigerant means thermally connected to the cryopanel, and a rotatable channel moving azimuthally around an axis located near the center of the cryopanel, removing gases adsorbed within the honeycomb structure by subliming them and conducting them outside the vacuum vessel. 4 figs.

Basement structure of the United Arab Emirates derived from an analysis of regional gravity and aeromagnetic database

NASA Astrophysics Data System (ADS)

Ali, M. Y.; Fairhead, J. D.; Green, C. M.; Noufal, A.

2017-08-01

Gravity and aeromagnetic data covering the whole territory of the United Arab Emirates (UAE) have been used to evaluate both shallow and deep geological structures, in particular the depth to basement since it is not imaged by seismic data anywhere within the UAE. Thus, the aim has been to map the basement so that its structure can help to assess its control on the distribution of hydrocarbons within the UAE. Power spectrum analysis reveals gravity and magnetic signatures to have some similarities, in having two main density/susceptibility interfaces widely separated in depth such that regional-residual anomaly separation could effectively be undertaken. The upper density/susceptibility interface occurs at a depth of about 1.0 km while the deeper interface varies in depth throughout the UAE. For gravity, this deeper interface is assumed to be due to the combined effect of lateral changes in density structures within the sediments and in depth of basement while for magnetics it is assumed the sediments have negligible susceptibility and the anomalies unrelated to the volcanic/magmatic bodies result from only changes in depth to basement. The power spectrum analysis over the suspect volcanic/magmatic bodies indicates they occur at 5 km depth. The finite tilt-depth and finite local wavenumber methods were used to estimate depth to source and only depths that agree to within 10% of each other were used to generate the depth to basement map. This depth to basement map, to the west of the UAE-Oman Mountains, varies in depth from 5 km to in excess of 15 km depth and is able to structurally account for the location of the shear structures, seen in the residual magnetic data, and the location of the volcanic/magmatic centres relative to a set of elongate N-S to NE-SW trending basement highs. The majority of oilfields in the UAE are located within these basement highs. Therefore, the hydrocarbon distribution in the UAE basin appears to be controlled by the location of the basement ridges.

Acoustic emission source location in complex structures using full automatic delta T mapping technique

NASA Astrophysics Data System (ADS)

Al-Jumaili, Safaa Kh.; Pearson, Matthew R.; Holford, Karen M.; Eaton, Mark J.; Pullin, Rhys

2016-05-01

An easy to use, fast to apply, cost-effective, and very accurate non-destructive testing (NDT) technique for damage localisation in complex structures is key for the uptake of structural health monitoring systems (SHM). Acoustic emission (AE) is a viable technique that can be used for SHM and one of the most attractive features is the ability to locate AE sources. The time of arrival (TOA) technique is traditionally used to locate AE sources, and relies on the assumption of constant wave speed within the material and uninterrupted propagation path between the source and the sensor. In complex structural geometries and complex materials such as composites, this assumption is no longer valid. Delta T mapping was developed in Cardiff in order to overcome these limitations; this technique uses artificial sources on an area of interest to create training maps. These are used to locate subsequent AE sources. However operator expertise is required to select the best data from the training maps and to choose the correct parameter to locate the sources, which can be a time consuming process. This paper presents a new and improved fully automatic delta T mapping technique where a clustering algorithm is used to automatically identify and select the highly correlated events at each grid point whilst the "Minimum Difference" approach is used to determine the source location. This removes the requirement for operator expertise, saving time and preventing human errors. A thorough assessment is conducted to evaluate the performance and the robustness of the new technique. In the initial test, the results showed excellent reduction in running time as well as improved accuracy of locating AE sources, as a result of the automatic selection of the training data. Furthermore, because the process is performed automatically, this is now a very simple and reliable technique due to the prevention of the potential source of error related to manual manipulation.

Nucleosome Positioning and NDR Structure at RNA Polymerase III Promoters

NASA Astrophysics Data System (ADS)

Helbo, Alexandra Søgaard; Lay, Fides D.; Jones, Peter A.; Liang, Gangning; Grønbæk, Kirsten

2017-02-01

Chromatin is structurally involved in the transcriptional regulation of all genes. While the nucleosome positioning at RNA polymerase II (pol II) promoters has been extensively studied, less is known about the chromatin structure at pol III promoters in human cells. We use a high-resolution analysis to show substantial differences in chromatin structure of pol II and pol III promoters, and between subtypes of pol III genes. Notably, the nucleosome depleted region at the transcription start site of pol III genes extends past the termination sequences, resulting in nucleosome free gene bodies. The +1 nucleosome is located further downstream than at pol II genes and furthermore displays weak positioning. The variable position of the +1 location is seen not only within individual cell populations and between cell types, but also between different pol III promoter subtypes, suggesting that the +1 nucleosome may be involved in the transcriptional regulation of pol III genes. We find that expression and DNA methylation patterns correlate with distinct accessibility patterns, where DNA methylation associates with the silencing and inaccessibility at promoters. Taken together, this study provides the first high-resolution map of nucleosome positioning and occupancy at human pol III promoters at specific loci and genome wide.

Leak detection utilizing analog binaural (VLSI) techniques

NASA Technical Reports Server (NTRS)

Hartley, Frank T. (Inventor)

1995-01-01

A detection method and system utilizing silicon models of the traveling wave structure of the human cochlea to spatially and temporally locate a specific sound source in the presence of high noise pandemonium. The detection system combines two-dimensional stereausis representations, which are output by at least three VLSI binaural hearing chips, to generate a three-dimensional stereausis representation including both binaural and spectral information which is then used to locate the sound source.

High-Resolution NMR Reveals Secondary Structure and Folding of Amino Acid Transporter from Outer Chloroplast Membrane

PubMed Central

Zook, James D.; Molugu, Trivikram R.; Jacobsen, Neil E.; Lin, Guangxin; Soll, Jürgen; Cherry, Brian R.; Brown, Michael F.; Fromme, Petra

2013-01-01

Solving high-resolution structures for membrane proteins continues to be a daunting challenge in the structural biology community. In this study we report our high-resolution NMR results for a transmembrane protein, outer envelope protein of molar mass 16 kDa (OEP16), an amino acid transporter from the outer membrane of chloroplasts. Three-dimensional, high-resolution NMR experiments on the 13C, 15N, 2H-triply-labeled protein were used to assign protein backbone resonances and to obtain secondary structure information. The results yield over 95% assignment of N, HN, CO, Cα, and Cβ chemical shifts, which is essential for obtaining a high resolution structure from NMR data. Chemical shift analysis from the assignment data reveals experimental evidence for the first time on the location of the secondary structure elements on a per residue basis. In addition T 1Z and T2 relaxation experiments were performed in order to better understand the protein dynamics. Arginine titration experiments yield an insight into the amino acid residues responsible for protein transporter function. The results provide the necessary basis for high-resolution structural determination of this important plant membrane protein. PMID:24205117

Diversity and biogeochemical structuring of bacterial communities across the Porangahau ridge accretionary prism, New Zealand

USGS Publications Warehouse

Hamdan, L.J.; Gillevet, P.M.; Pohlman, J.W.; Sikaroodi, M.; Greinert, J.; Coffin, R.B.

2011-01-01

Sediments from the Porangahau ridge, located off the northeastern coast of New Zealand, were studied to describe bacterial community structure in conjunction with differing biogeochemical regimes across the ridge. Low diversity was observed in sediments from an eroded basin seaward of the ridge and the community was dominated by uncultured members of the Burkholderiales. Chloroflexi/GNS and Deltaproteobacteria were abundant in sediments from a methane seep located landward of the ridge. Gas-charged and organic-rich sediments further landward had the highest overall diversity. Surface sediments, with the exception of those from the basin, were dominated by Rhodobacterales sequences associated with organic matter deposition. Taxa related to the Desulfosarcina/Desulfococcus and the JS1 candidates were highly abundant at the sulfate-methane transition zone (SMTZ) at three sites. To determine how community structure was influenced by terrestrial, pelagic and in situ substrates, sequence data were statistically analyzed against geochemical data (e.g. sulfate, chloride, nitrogen, phosphorous, methane, bulk inorganic and organic carbon pools) using the Biota-Environmental matching procedure. Landward of the ridge, sulfate was among the most significant structuring factors. Seaward of the ridge, silica and ammonium were important structuring factors. Regardless of the transect location, methane was the principal structuring factor on SMTZ communities. FEMS Microbiology Ecology ?? 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. No claim to original US government works.

Bioenvironmental Engineering Guide for Composite Materials

DTIC Science & Technology

2014-03-31

Russell J. Advanced composite cargo aircraft proves large structure practicality. High- Performance Composites 2010 Jan. Retrieved 3 January 2014 from...fuel or hydraulic fluid; location of radioactive components associated with the aircraft, such as depleted uranium counterweights, isotopes

Hybrid photonic crystal cavity and waveguide for coupling to diamond NV-centers.

PubMed

Barclay, Paul E; Fu, Kai-Mei; Santori, Charles; Beausoleil, Raymond G

2009-06-08

A design for an ultra-high Q photonic crystal nanocavity engineered to interact with nitrogen-vacancy (NV) centers located near the surface of a single crystal diamond sample is presented. The structure is based upon a nanowire photonic crystal geometry, and consists of a patterned high refractive index thin film, such as gallium phosphide (GaP), supported by a diamond substrate. The nanocavity supports a mode with quality factor Q > 1.5 x 10(6) and mode volume V < 0.52(lambda/nGaP)(3), and promises to allow Purcell enhanced collection of spontaneous emission from an NV located more than 50 nm below the diamond surface. The nanowire photonic crystal waveguide can be used to efficiently couple light into and out of the cavity, or as an efficient broadband collector of NV phonon sideband emission. The proposed structures can be fabricated using existing materials and processing techniques.

Aircraft engine with inter-turbine engine frame supported counter rotating low pressure turbine rotors

NASA Technical Reports Server (NTRS)

Seda, Jorge F. (Inventor); Dunbar, Lawrence W. (Inventor); Gliebe, Philip R. (Inventor); Szucs, Peter N. (Inventor); Brauer, John C. (Inventor); Johnson, James E. (Inventor); Moniz, Thomas (Inventor); Steinmetz, Gregory T. (Inventor)

2003-01-01

An aircraft gas turbine engine assembly includes an inter-turbine frame axially located between high and low pressure turbines. Low pressure turbine has counter rotating low pressure inner and outer rotors with low pressure inner and outer shafts which are at least in part rotatably disposed co-axially within a high pressure rotor. Inter-turbine frame includes radially spaced apart radially outer first and inner second structural rings disposed co-axially about a centerline and connected by a plurality of circumferentially spaced apart struts. Forward and aft sump members having forward and aft central bores are fixedly joined to axially spaced apart forward and aft portions of the inter-turbine frame. Low pressure inner and outer rotors are rotatably supported by a second turbine frame bearing mounted in aft central bore of aft sump member. A mount for connecting the engine to an aircraft is located on first structural ring.

The Coso geothermal area: A laboratory for advanced MEQ studies for geothermal monitoring

USGS Publications Warehouse

Julian, B.R.; Foulger, G.R.; Richards-Dinger, K.

2004-01-01

The permanent 16-station network of three-component digital seismometers at the Coso geothermal area, California, supplemented by 14 temporary instruments deployed in connection with the DOE Enhanced Geothermal Systems (EGS) Project, provides high-quality microearthquake (MEQ) recordings that are well suited to monitoring a producing geothermal area. We are currently using these data to investigate structure and active processes within the geothermal reservoir by applying three advanced methods: a) high-precision MEQ hypocenter location; b) time-dependent tomography; c) complete (moment tensor) MEQ source mechanism determination. Preliminary results to date resolve seismogenic structures in the producing field more clearly than is possible with conventional earthquake-location techniques. A shallow part of the producing field shows clear changes in the ratio of the seismic wave speeds, Vp/V s, between 1996 and 2002, which are probably related to physical changes in the reservoir caused by fluid extraction.

[Design and Analysis of CT High-speed Data Transmission Rotating Connector Ring System Retaining Ring].

PubMed

Pan, Li; Cao, Jujiang; Liu, Min; Fu, Weiwei

2017-11-30

High speed data transmission rotating connector system for signal high-speed transmission used in the fixed end and rotating end, it is one of the core component in the CT system. This paper involves structure design and analysis of the retaining ring in the CT high speed data transmission rotating connector system based on the principle of off-axis free space optical transmission. According to the problem of the actual engineering application of space limitations, optical fiber fixed and collimator installation location, we designed the structure of the retaining ring. Using the static analysis function of ANSYS Workbench, it verifies rationality and safety of the strength of retaining ring structure. And based on modal analysis function of ANSYS Workbench, it evaluates the effect of the retaining ring on the stability of the system date transmission, and provides theoretical basis for the feasibility of the structure in practical application.

Distributed measurement of acoustic vibration location with frequency multiplexed phase-OTDR

NASA Astrophysics Data System (ADS)

Iida, Daisuke; Toge, Kunihiro; Manabe, Tetsuya

2017-07-01

All-fiber distributed vibration sensing is attracting attention in relation to structural health monitoring because it is cost effective, offers high coverage of the monitored area and can detect various structural problems. And in particular the demand for high-speed vibration sensing operating at more than 10 kHz has increased because high frequency vibration indicates high energy and severe trouble in the monitored object. Optical fiber vibration sensing with phase-sensitive optical time domain reflectometry (phase-OTDR) has long been studied because it can be used for distributed vibration sensing in optical fiber. However, pulse reflectometry such as OTDR cannot measure high-frequency vibration whose cycle is shorter than the repetition time of the OTDR. That is, the maximum detectable frequency depends on fiber length. In this paper, we describe a vibration sensing technique with frequency-multiplexed OTDR that can detect the entire distribution of a high-frequency vibration thus allowing us to locate a high-speed vibration point. We can measure the position, frequency and dynamic change of a high-frequency vibration whose cycle is shorter than the repetition time. Both frequency and position are visualized simultaneously for a 5-km fiber with an 80-kHz frequency response and a 20-m spatial resolution.

An Ultrahigh CO2-Loaded Silicalite-1 Zeolite: Structural Stability and Physical Properties at High Pressures and Temperatures.

PubMed

Marqueño, Tomas; Santamaria-Perez, David; Ruiz-Fuertes, Javier; Chuliá-Jordán, Raquel; Jordá, Jose L; Rey, Fernando; McGuire, Chris; Kavner, Abby; MacLeod, Simon; Daisenberger, Dominik; Popescu, Catalin; Rodriguez-Hernandez, Placida; Muñoz, Alfonso

2018-06-04

We report the formation of an ultrahigh CO 2 -loaded pure-SiO 2 silicalite-1 structure at high pressure (0.7 GPa) from the interaction of empty zeolite and fluid CO 2 medium. The CO 2 -filled structure was characterized in situ by means of synchrotron powder X-ray diffraction. Rietveld refinements and Fourier recycling allowed the location of 16 guest carbon dioxide molecules per unit cell within the straight and sinusoidal channels of the porous framework to be analyzed. The complete filling of pores by CO 2 molecules favors structural stability under compression, avoiding pressure-induced amorphization below 20 GPa, and significantly reduces the compressibility of the system compared to that of the parental empty one. The structure of CO 2 -loaded silicalite-1 was also monitored at high pressures and temperatures, and its thermal expansivity was estimated.

Diversity and community structure of pelagic cnidarians in the Celebes and Sulu Seas, southeast Asian tropical marginal seas

NASA Astrophysics Data System (ADS)

Grossmann, Mary M.; Nishikawa, Jun; Lindsay, Dhugal J.

2015-06-01

The Sulu Sea is a semi-isolated, marginal basin surrounded by high sills that greatly reduce water inflow at mesopelagic depths. For this reason, the entire water column below 400 m is stable and homogeneous with respect to salinity (ca. 34.00) and temperature (ca. 10 °C). The neighbouring Celebes Sea is more open, and highly influenced by Pacific waters at comparable depths. The abundance, diversity, and community structure of pelagic cnidarians was investigated in both seas in February 2000. Cnidarian abundance was similar in both sampling locations, but species diversity was lower in the Sulu Sea, especially at mesopelagic depths. At the surface, the cnidarian community was similar in both marginal seas, but, at depth, community structure was dependent first on sampling location and then on depth within each Sea. Cnidarians showed different patterns of dominance at the two sampling locations, with Sulu Sea communities often dominated by species that are rare elsewhere in the Indo-Pacific. Mesopelagic and bathypelagic species recorded in the Sulu Sea did not have significantly different vertical distributions in the Celebes Sea. However, some deep mesopelagic genera were absent from the Sulu Sea in the sampled depth range. These results suggest that a combination of environmental and physiological parameters determine the distribution and dominance of pelagic cnidarians.

Use of high-resolution satellite images for detection of geological structures related to Central Andes geothermal field, Chile.

NASA Astrophysics Data System (ADS)

Benavides-Rivas, C. L.; Soto-Pinto, C. A.; Arellano-Baeza, A. A.

2014-12-01

Central valley and the border with Argentina in the center, and in the fault system Liquiñe-Ofqui in the South of the country. High resolution images from the LANDSAT 8 satellite have been used to delineate the geological structures related to the potential geothermal reservoirs located at the northern end of the Southern Volcanic Zone of Chile. It was done by applying the lineament extraction technique, using the ADALGEO software, developed by [Soto et al., 2013]. These structures have been compared with the distribution of main geological structures obtained in the field. It was found that the lineament density increases in the areas of the major heat flux indicating that the lineament analysis could be a power tool for the detection of faults and joint zones associated to the geothermal fields. A lineament is generally defined as a straight or slightly curved feature in the landscape visible satellite image as an aligned sequence of pixel intensity contrast compared to the background. The system features extracted from satellite images is not identical to the geological lineaments that are generally determined by ground surveys, however, generally reflects the structure of faults and fractures in the crust. A temporal sequence of eight Landsat multispectral images of Central Andes geothermal field, located in VI region de Chile, was used to study changes in the configuration of the lineaments during 2011. The presence of minerals with silicification, epidotization, and albitization, which are typical for geothrmal reservoirs, was also identified, using their spectral characteristics, and subsequently corroborated in the field. Both lineament analysis and spectral analysis gave similar location of the reservoir, which increases reliability of the results.

Taxonomy of Caribbean Tourism Alcohol Venues: Implications for HIV Transmission*

PubMed Central

GUILAMO-RAMOS, Vincent; JACCARD, James; MCCARTHY, Katharine; QUIÑONES, Zahira; LUSHIN, Viktor; SKINNER-DAY, Molly; PADILLA, Mark; MEISTERLIN, Leah

2013-01-01

Background Tourism areas represent ecologies of heightened HIV vulnerability characterized by a disproportionate concentration of alcohol venues. Limited research has explored how alcohol venues facilitate HIV transmission. Methods We spatially mapped locations of alcohol venues in a Dominican tourism town and conducted a venue-based survey of key informants (n=135) focused on three facets of alcohol venues: structural features, type of patrons, and HIV risk behaviors. Using latent class analysis, we identified evidence-based typologies of alcohol venues for each of the three facets. Focused contrasts identified the co-occurrence of classes of structural features, classes of types of patrons, and classes of HIV risk behavior, thus elaborating the nature of high risk venues. Results We identified three categories of venue structural features, three for venue patrons, and five for HIV risk behaviors. Analysis revealed that alcohol venues with the greatest structural risks (e.g., sex work on site with lack of HIV prevention services) were most likely frequented by the venue patron category characterized by high population-mixing between locals and foreign tourists, who were in turn most likely to engage in the riskiest behaviors. Conclusion Our results highlight the stratification of venue patrons into groups who engage in behaviors of varying risk in structural settings that vary in risk. The convergence of high-risk patron groups in alcohol venues with the greatest structural risk suggests these locations have potential for HIV transmission. Policymakers and prevention scientists can use these methods and data to target HIV prevention resources to identified priority areas. PMID:23478154

Taxonomy of Caribbean tourism alcohol venues: implications for HIV transmission.

PubMed

Guilamo-Ramos, Vincent; Jaccard, James; McCarthy, Katharine; Quiñones, Zahira; Lushin, Viktor; Skinner-Day, Molly; Padilla, Mark; Meisterlin, Leah

2013-09-01

Tourism areas represent ecologies of heightened HIV vulnerability characterized by a disproportionate concentration of alcohol venues. Limited research has explored how alcohol venues facilitate HIV transmission. We spatially mapped locations of alcohol venues in a Dominican tourism town and conducted a venue-based survey of key informants (n=135) focused on three facets of alcohol venues: structural features, type of patrons, and HIV risk behaviors. Using latent class analysis, we identified evidence-based typologies of alcohol venues for each of the three facets. Focused contrasts identified the co-occurrence of classes of structural features, classes of types of patrons, and classes of HIV risk behavior, thus elaborating the nature of high risk venues. We identified three categories of venue structural features, three for venue patrons, and five for HIV risk behaviors. Analysis revealed that alcohol venues with the greatest structural risks (e.g. sex work on-site with lack of HIV prevention services) were most likely frequented by the venue patron category characterized by high population-mixing between locals and foreign tourists, who were in turn most likely to engage in the riskiest behaviors. Our results highlight the stratification of venue patrons into groups who engage in behaviors of varying risk in structural settings that vary in risk. The convergence of high-risk patron groups in alcohol venues with the greatest structural risk suggests these locations have potential for HIV transmission. Policymakers and prevention scientists can use these methods and data to target HIV prevention resources to identified priority areas. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Large-Deformation Displacement Transfer Functions for Shape Predictions of Highly Flexible Slender Aerospace Structures

NASA Technical Reports Server (NTRS)

Ko, William L.; Fleischer, Van Tran

2013-01-01

Large deformation displacement transfer functions were formulated for deformed shape predictions of highly flexible slender structures like aircraft wings. In the formulation, the embedded beam (depth wise cross section of structure along the surface strain sensing line) was first evenly discretized into multiple small domains, with surface strain sensing stations located at the domain junctures. Thus, the surface strain (bending strains) variation within each domain could be expressed with linear of nonlinear function. Such piecewise approach enabled piecewise integrations of the embedded beam curvature equations [classical (Eulerian), physical (Lagrangian), and shifted curvature equations] to yield closed form slope and deflection equations in recursive forms.

Benthic Crustacea from tropical and temperate reef locations: differences in assemblages and their relationship with habitat structure

NASA Astrophysics Data System (ADS)

Kramer, Michael J.; Bellwood, David R.; Taylor, Richard B.; Bellwood, Orpha

2017-09-01

Tropical and temperate marine habitats have long been recognised as fundamentally different system, yet comparative studies are rare, particularly for small organisms such as Crustacea. This study investigates the ecological attributes (abundance, biomass and estimated productivity) of benthic Crustacea in selected microhabitats from a tropical and a temperate location, revealing marked differences in the crustacean assemblages. In general, microhabitats from the tropical location (dead coral, the epilithic algal matrix [algal turfs] and sand) supported high abundances of small individuals (mean length = 0.53 mm vs. 0.96 mm in temperate microhabitats), while temperate microhabitats (the brown seaweed Carpophyllum sp., coralline turf and sand) had substantially greater biomasses of crustaceans and higher estimated productivity rates. In both locations, the most important microhabitats for crustaceans (per unit area) were complex structures: tropical dead coral and temperate Carpophyllum sp. It appears that the differences between microhabitats are largely driven by the size and relative abundance of key crustacean groups. Temperate microhabitats have a higher proportion of relatively large Peracarida (Amphipoda and Isopoda), whereas tropical microhabitats are dominated by small detrital- and microalgal-feeding crustaceans (harpacticoid copepods and ostracods). These differences highlight the vulnerability of tropical and temperate systems to the loss of complex benthic structures and their associated crustacean assemblages.

A Re-Examination of the Bedout High, Offshore Canning Basin, Western Australia - Possible Impact Site for the Permian-Triassic Mass Extinction Event?

NASA Astrophysics Data System (ADS)

Becker, L.; Nicholson, C.; Poreda, R. J.

2002-12-01

The Bedout High, located offshore Canning basin in Western Australia, is an unusual structure and its origin remains problematic. K-Ar dating of volcanic samples encountered at total depth in the Lagrange-1 exploration well indicated an age of about 253+/-5 Ma consistent with the Permian-Triassic boundary event. Gorter (PESA News, pp. 33-34, 1996) speculates that the Bedout High is the uplifted core (30 km) of a circular feature, some 220 km across, formed by the impact of a large bolide (cometary or asteroidal) with the Earth near the end-Permian. Accepting a possible impact origin for the Bedout structure, with the indicated dimensions, would have had profound effects on global climate as well as significant changes in lithotratigraphic, biostratigraphic and chemostratigraphic indicators as seen in several Permian-Triassic boundary locations worldwide. In this work, we re-examine some of the structural data previously presented by Gorter (1996) using some additional seismic lines. We have also evaluated several impact tracers including iridium, shocked quartz, productivity collapse, helium-3, chromium-53 and fullerenes with trapped noble gases from some Permian-Triassic boundary sites in the Tethys and Circum-Pacific regions. Our findings suggest that the Bedout structure is a good candidate for an oceanic impact at the end Permian, triggering the most severe mass extinction in the history of life on Earth.

Localised Effects of a Mega-Disturbance: Spatiotemporal Responses of Intertidal Sandy Shore Communities to the 2010 Chilean Earthquake.

PubMed

Sepúlveda, Roger D; Valdivia, Nelson

2016-01-01

Determining the effects of unpredictable disturbances on dynamic ecological systems is challenged by the paucity of appropriate temporal and spatial coverage of data. On 27 February 2010, an 8.8 Mw mega-earthquake and tsunami struck central Chile and caused coastal land-level changes, massive damage to coastal infrastructure, and widespread mortality of coastal organisms. Wave-exposed sandy beaches showed significant changes of species abundances from before to after the earthquake, but the highly dynamic biotic and abiotic conditions of these habitats make difficult to draw clear-cut conclusions from these patterns. Here, we analysed a beyond-BACI (Before-After Control-Impact) sampling design to test whether the effects of the Maule earthquake on sandy-shore species diversity, abundance, and structure were heterogeneous along the shore. Invertebrate species abundances were quantified before (i.e. February 2010) and after (i.e. March 2010, September 2010, and March 2011) the earthquake at three sandy shores randomly located within the earthquake rupture area and three sites within a "control" area located >400 km southward from epicentre. Immediately after the earthquake took place, the three sites located in the rupture area showed anomalous beach-profile uplifts that did not comply with the erosion (i.e. "negative" uplifts) that regularly occurs during late summer in the region. Species richness, abundance, and community structure significantly varied from before to after the strike, but these patterns of change varied among sites within both areas. Only the site with the strongest and persistent beach-profile uplift within the rupture area showed significant concomitant changes in species richness and community structure; after 13 months, this community showed a similar multivariate structure to the before-disturbance state. This site, in particular, was located in the section of the rupture area that received most of the impact of the after-earthquake tsunami. Therefore, our results suggest that the effects of the Maule mega-earthquake on the ecological communities were spatially heterogeneous and highly localised. We suggest that high mobility and other species' adaptations to the dynamic environmental conditions of sandy beaches might explain the comparatively high resilience of these assemblages. With this work we hope to motivate further experimental research on the role of individual- and population-level properties in the response of sandy-beach communities to interacting sources of disturbances.

Localised Effects of a Mega-Disturbance: Spatiotemporal Responses of Intertidal Sandy Shore Communities to the 2010 Chilean Earthquake

PubMed Central

Sepúlveda, Roger D.; Valdivia, Nelson

2016-01-01

Determining the effects of unpredictable disturbances on dynamic ecological systems is challenged by the paucity of appropriate temporal and spatial coverage of data. On 27 February 2010, an 8.8 Mw mega-earthquake and tsunami struck central Chile and caused coastal land-level changes, massive damage to coastal infrastructure, and widespread mortality of coastal organisms. Wave-exposed sandy beaches showed significant changes of species abundances from before to after the earthquake, but the highly dynamic biotic and abiotic conditions of these habitats make difficult to draw clear-cut conclusions from these patterns. Here, we analysed a beyond-BACI (Before-After Control-Impact) sampling design to test whether the effects of the Maule earthquake on sandy-shore species diversity, abundance, and structure were heterogeneous along the shore. Invertebrate species abundances were quantified before (i.e. February 2010) and after (i.e. March 2010, September 2010, and March 2011) the earthquake at three sandy shores randomly located within the earthquake rupture area and three sites within a “control” area located >400 km southward from epicentre. Immediately after the earthquake took place, the three sites located in the rupture area showed anomalous beach-profile uplifts that did not comply with the erosion (i.e. “negative” uplifts) that regularly occurs during late summer in the region. Species richness, abundance, and community structure significantly varied from before to after the strike, but these patterns of change varied among sites within both areas. Only the site with the strongest and persistent beach-profile uplift within the rupture area showed significant concomitant changes in species richness and community structure; after 13 months, this community showed a similar multivariate structure to the before-disturbance state. This site, in particular, was located in the section of the rupture area that received most of the impact of the after-earthquake tsunami. Therefore, our results suggest that the effects of the Maule mega-earthquake on the ecological communities were spatially heterogeneous and highly localised. We suggest that high mobility and other species’ adaptations to the dynamic environmental conditions of sandy beaches might explain the comparatively high resilience of these assemblages. With this work we hope to motivate further experimental research on the role of individual- and population-level properties in the response of sandy-beach communities to interacting sources of disturbances. PMID:27383744

Fault structure and mechanics of the Hayward Fault, California from double-difference earthquake locations

USGS Publications Warehouse

Waldhauser, F.; Ellsworth, W.L.

2002-01-01

The relationship between small-magnitude seismicity and large-scale crustal faulting along the Hayward Fault, California, is investigated using a double-difference (DD) earthquake location algorithm. We used the DD method to determine high-resolution hypocenter locations of the seismicity that occurred between 1967 and 1998. The DD technique incorporates catalog travel time data and relative P and S wave arrival time measurements from waveform cross correlation to solve for the hypocentral separation between events. The relocated seismicity reveals a narrow, near-vertical fault zone at most locations. This zone follows the Hayward Fault along its northern half and then diverges from it to the east near San Leandro, forming the Mission trend. The relocated seismicity is consistent with the idea that slip from the Calaveras Fault is transferred over the Mission trend onto the northern Hayward Fault. The Mission trend is not clearly associated with any mapped active fault as it continues to the south and joins the Calaveras Fault at Calaveras Reservoir. In some locations, discrete structures adjacent to the main trace are seen, features that were previously hidden in the uncertainty of the network locations. The fine structure of the seismicity suggest that the fault surface on the northern Hayward Fault is curved or that the events occur on several substructures. Near San Leandro, where the more westerly striking trend of the Mission seismicity intersects with the surface trace of the (aseismic) southern Hayward Fault, the seismicity remains diffuse after relocation, with strong variation in focal mechanisms between adjacent events indicating a highly fractured zone of deformation. The seismicity is highly organized in space, especially on the northern Hayward Fault, where it forms horizontal, slip-parallel streaks of hypocenters of only a few tens of meters width, bounded by areas almost absent of seismic activity. During the interval from 1984 to 1998, when digital waveforms are available, we find that fewer than 6.5% of the earthquakes can be classified as repeating earthquakes, events that rupture the same fault patch more than one time. These most commonly are located in the shallow creeping part of the fault, or within the streaks at greater depth. The slow repeat rate of 2-3 times within the 15-year observation period for events with magnitudes around M = 1.5 is indicative of a low slip rate or a high stress drop. The absence of microearthquakes over large, contiguous areas of the northern Hayward Fault plane in the depth interval from ???5 to 10 km and the concentrations of seismicity at these depths suggest that the aseismic regions are either locked or retarded and are storing strain energy for release in future large-magnitude earthquakes.

Lithospheric Structure of Central Asia

NASA Astrophysics Data System (ADS)

Martin, R. J.; Gulen, L.; Sun, Y.; Toksoz, M. N.

2009-12-01

The active tectonics of Central Asia is the result of ongoing, active continental collision between the Indian and the Eurasian plates. This geologically and tectonically complex area is also one of the most seismically active regions in the world. Previous studies in this region mostly depended on teleseismic data and the local and regional data from the stations located in China. In this study we used the local travel time data from Kazakhstan, Kyrgyzstan, Tajikistan, and Uzbekistan to study the lithospheric structure in this region. We selected the events and stations between 32°N-65°E and 45°N-85°E and focused on the areas of Pamir and Tien Shan. In this data set, there are more than 3000 P and S arrivals received at 68 stations from about 220 events. The double difference tomography is applied to relocate events and to invert for seismic structure simultaneously. Our results provide accurate locations of earthquakes and high resolution lithospheric structure in this region. We use both; the local travel times, and also the regional travel times to invert the 3D lithospheric velocity structure in this region. More than 2200 P wave phase picks were used in the inversion. The average grid spacing is 100km and the inverted grids lay on six layers. Then we use the Double Difference Tomography method developed by Zhang and Thurber (2003, 2006) to invert the 3-D P-wave velocity structure. Our tomographic results show highly heterogeneous crust and upper mantle structure for Central Asia. Some crustal low velocity zones are found beneath Tien Shan, the northern Pamir, and the Tajik depression, while high velocity anomalies are found beneath the Kazakh shield, the southern Pamir, and the Tarim basin.

ALMA Observations of a Quiescent Molecular Cloud in the Large Magellanic Cloud

NASA Astrophysics Data System (ADS)

Wong, Tony; Hughes, Annie; Tokuda, Kazuki; Indebetouw, Rémy; Bernard, Jean-Philippe; Onishi, Toshikazu; Wojciechowski, Evan; Bandurski, Jeffrey B.; Kawamura, Akiko; Roman-Duval, Julia; Cao, Yixian; Chen, C.-H. Rosie; Chu, You-hua; Cui, Chaoyue; Fukui, Yasuo; Montier, Ludovic; Muller, Erik; Ott, Juergen; Paradis, Deborah; Pineda, Jorge L.; Rosolowsky, Erik; Sewiło, Marta

2017-12-01

We present high-resolution (subparsec) observations of a giant molecular cloud in the nearest star-forming galaxy, the Large Magellanic Cloud. ALMA Band 6 observations trace the bulk of the molecular gas in 12CO(2-1) and the high column density regions in 13CO(2-1). Our target is a quiescent cloud (PGCC G282.98-32.40, which we refer to as the “Planck cold cloud” or PCC) in the southern outskirts of the galaxy where star formation activity is very low and largely confined to one location. We decompose the cloud into structures using a dendrogram and apply an identical analysis to matched-resolution cubes of the 30 Doradus molecular cloud (located near intense star formation) for comparison. Structures in the PCC exhibit roughly 10 times lower surface density and five times lower velocity dispersion than comparably sized structures in 30 Dor, underscoring the non-universality of molecular cloud properties. In both clouds, structures with relatively higher surface density lie closer to simple virial equilibrium, whereas lower surface-density structures tend to exhibit supervirial line widths. In the PCC, relatively high line widths are found in the vicinity of an infrared source whose properties are consistent with a luminous young stellar object. More generally, we find that the smallest resolved structures (“leaves”) of the dendrogram span close to the full range of line widths observed across all scales. As a result, while the bulk of the kinetic energy is found on the largest scales, the small-scale energetics tend to be dominated by only a few structures, leading to substantial scatter in observed size-line-width relationships.

Watershed evapotranspiration increased due to changes in vegetation composition and structure under a subtropical climate

Treesearch

Ge Sun; Changqing Zuo; Shiyu Liu; Mingliang Liu; Steven G McNulty; James M. Vose

2008-01-01

Natural forests in southern China have been severely logged due to high human demand for timber, food, and fuels during the past century, but are recovering in the past decade. The objective of this study was to investigate how vegetation cover changes in composition and structure affected the water budgets of a 9.6-km2 Dakeng watershed located...

Space Shuttle Main Engine structural analysis and data reduction/evaluation. Volume 3B: High pressure fuel turbo-pump preburner pump bearing assembly analysis

NASA Technical Reports Server (NTRS)

Power, Gloria B.; Violett, Rebeca S.

1989-01-01

The analysis performed on the High Pressure Oxidizer Turbopump (HPOTP) preburner pump bearing assembly located on the Space Shuttle Main Engine (SSME) is summarized. An ANSYS finite element model for the inlet assembly was built and executed. Thermal and static analyses were performed.

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

Shao, Shuai; Wang, Jian

In this work, using the Cu–Ni (111) semi-coherent interface as a model system, we combine atomistic simulations and defect theory to reveal the relaxation mechanisms, structure, and properties of semi-coherent interfaces. By calculating the generalized stacking fault energy (GSFE) profile of the interface, two stable structures and a high-energy structure are located. During the relaxation, the regions that possess the stable structures expand and develop into coherent regions; the regions with high-energy structure shrink into the intersection of misfit dislocations (nodes). This process reduces the interface excess potential energy but increases the core energy of the misfit dislocations and nodes.more » The core width is dependent on the GSFE of the interface. The high-energy structure relaxes by relative rotation and dilatation between the crystals. The relative rotation is responsible for the spiral pattern at nodes. The relative dilatation is responsible for the creation of free volume at nodes, which facilitates the nodes’ structural transformation. Several node structures have been observed and analyzed. In conclusion, the various structures have significant impact on the plastic deformation in terms of lattice dislocation nucleation, as well as the point defect formation energies.« less

Volcano-tectonic structures, gravity and helium in geothermal areas of Tuscany and Latium (Vulsini volcanic district), Italy

USGS Publications Warehouse

Di, Filippo M.; Lombardi, S.; Nappi, G.; Reimer, G.M.; Renzulli, A.; Toro, B.

1999-01-01

Since the early 1980s, geological and structural mapping, gravity, and helium soil-gas studies have been performed in the eastern sector of the Vulsini Volcanic District (Roman Magmatic Province) in an attempt to locate potential geothermal reservoirs. This area is characterised by an anomalous geothermal gradient of > 100??C/km, and by widespread hydrothermal mineralization, thermal springs, high gas fluxes, and fossil and current travertine deposits. The results of these surveys indicate the existence of a number of fault systems, with N-S and E-W structures that appear to be superimposed on older NW-SE and NE-SW features. Comparison of the results of the various studies also reveals differences in permeability and potential reservoir structures at depth.Since the early 1980s, geological and structural mapping, gravity, and helium soil-gas studies have been performed in the eastern sector of the Vulsini Volcanic District (Roman Magmatic Province) in an attempt to locate potential geothermal reservoirs. This area is characterised by an anomalous geothermal gradient of > 100??C/km, and by widespread hydrothermal mineralization, thermal springs, high gas fluxes, and fossil and current travertine deposits. The results of these surveys indicate the existence of a number of fault systems, with N-S and E-W structures that appear to be superimposed on older NW-SE and NE-SW features. Comparison of the results of the various studies also reveals differences in permeability and potential reservoir structures at depth.

High-resolution high-sensitivity and truly distributed optical frequency domain reflectometry for structural crack detection

NASA Astrophysics Data System (ADS)

Li, Wenhai; Bao, Xiaoyi; Chen, Liang

2014-05-01

Optical Frequency Domain Reflectometry (OFDR) with the use of polarization maintaining fiber (PMF) is capable of distinguishing strain and temperature, which is critical for successful field applications such as structural health monitoring (SHM) and smart material. Location-dependent measurement sensitivities along PMF are compensated by cross- and auto-correlations measurements of the spectra form a distributed parameter matrix. Simultaneous temperature and strain measurement accuracy of 1μstrain and 0.1°C is achieved with 2.5mm spatial resolution in over 180m range.

The Astro-E/XRS Blocking Filter Calibration

NASA Technical Reports Server (NTRS)

Audley, Michael D.; Arnaud, Keith A.; Gendreau, Keith C.; Boyce, Kevin R.; Fleetwood, Charles M.; Kelley, Richard L.; Keski-Kuha, Ritva A.; Porter, F. Scott; Stahle, Caroline K.; Szymkowiak, Andrew E.

1999-01-01

We describe the transmission calibration of the Astro-E XRS blocking filters. The XRS instrument has five aluminized polyimide blocking filters. These filters are located at thermal stages ranging from 200 K to 60 mK. They are each about 1000 A thick. XRS will have high energy resolution which will enable it to see some of the extended fine structure around the oxygen and aluminum K edges of these filters. Thus, we are conducting a high spectral resolution calibration of the filters near these energies to resolve out extended flue structure and absorption lines.

Location, Reprocessing, and Analysis of Two Dimensional Seismic Reflection Data on the Jicarilla Apache Indian Reservation, New Mexico, Final Report, September 1, 1997-February 1, 2000

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

Ridgley, Jennie; Taylor, David J.; Huffman, Jr., A. Curtis

2000-06-08

Multichannel surface seismic reflection data recording is a standard industry tool used to examine various aspects of geology, especially the stratigraphic characteristics and structural style of sedimentary formations in the subsurface. With the help of the Jicarilla Apache Tribe and the Bureau of Indian Affairs we were able to locate over 800 kilometers (500 miles) of multichannel seismic reflection data located on the Jicarilla Apache Indian reservation. Most of the data was received in hardcopy form, but there were data sets where either the demultiplexed digital field data or the processed data accompanied the hardcopy sections. The seismic data wasmore » acquired from the mid 1960's to the early 1990's. The most extensive seismic coverage is in the southern part of the reservation, although there are two good surveys located on the northeastern and northwestern parts of the reservation. Most of the data show that subsurface formations are generally flat-lying in the southern and western portion of the reservation. There is, however, a significant amount of structure imaged on seismic data located over the San Juan Basin margin along the east-central and northern part of the reservation. Several west to east trending lines in these areas show a highly faulted monoclinal structure from the deep basin in the west up onto the basin margin to the east. Hydrocarbon exploration in flat lying formations is mostly stratigraphic in nature. Where there is structure in the subsurface and indications are that rocks have been folded, faulted, and fractured, exploration has concentrated on structural traps and porosity/permeability "sweet spots" caused by fracturing. Therefore, an understanding of the tectonics influencing the entire section is critical in understanding mechanisms for generating faults and fractures in the Cretaceous. It is apparent that much of the hydrocarbon production on the reservation is from fracture porosity in either source or reservoir sequences. Therefore it is important to understand the mechanism that controls the location and intensity of the fractures. A possible mechanism may be deep seated basement faulting that has been active through time. Examining the basement fault patterns in this part of the basin and their relation to fracture production may provide a model for new plays on the Jicarilla Indian Reservation. There are still parts of the reservation where the subsurface has not been imaged geophysically with either conventional two-dimensional or three-dimensional reflection seismic techniques. These methods, especially 3-D seismic, would provide the best data for mapping deep basement faulting. The authors would recommend that 3-D seismic be acquired along the Basin margin located along the eastern edge of the reservation and the results be used to construct detailed fault maps which may help to locate areas with the potential to contain highly fractured zones in the subsurface.« less

An evaluation of ionizing radiation emitted by high power microwave generators

NASA Astrophysics Data System (ADS)

Lovell, C. David; Bolch, W. Emmett

1992-02-01

Ionizing radiation emitted by electron-beam driven high power microwave (HPM) generators were measured in the near and far-field using lithium fluoride (LiF) thermoluminescent dosimeters (TLD's). Simplified photon energy spectra were determined by measuring radiation transmission, at electron beam energies of 300 to 650 keV, through various thicknesses of steel and lead attenuators. These data were used to calculate the effective energy of the x-rays produced by interactions between the electrons and the walls or other structures of the HPM generators. Operators were polled to determine locations of burn marks or other visible damage to locate potential ionizing radiation source regions.

Modeling livestock population structure: a geospatial database for Ontario swine farms.

PubMed

Khan, Salah Uddin; O'Sullivan, Terri L; Poljak, Zvonimir; Alsop, Janet; Greer, Amy L

2018-01-30

Infectious diseases in farmed animals have economic, social, and health consequences. Foreign animal diseases (FAD) of swine are of significant concern. Mathematical and simulation models are often used to simulate FAD outbreaks and best practices for control. However, simulation outcomes are sensitive to the population structure used. Within Canada, access to individual swine farm population data with which to parameterize models is a challenge because of privacy concerns. Our objective was to develop a methodology to model the farmed swine population in Ontario, Canada that could represent the existing population structure and improve the efficacy of simulation models. We developed a swine population model based on the factors such as facilities supporting farm infrastructure, land availability, zoning and local regulations, and natural geographic barriers that could affect swine farming in Ontario. Assigned farm locations were equal to the swine farm density described in the 2011 Canadian Census of Agriculture. Farms were then randomly assigned to farm types proportional to the existing swine herd types. We compared the swine population models with a known database of swine farm locations in Ontario and found that the modeled population was representative of farm locations with a high accuracy (AUC: 0.91, Standard deviation: 0.02) suggesting that our algorithm generated a reasonable approximation of farm locations in Ontario. In the absence of a readily accessible dataset providing details of the relative locations of swine farms in Ontario, development of a model livestock population that captures key characteristics of the true population structure while protecting privacy concerns is an important methodological advancement. This methodology will be useful for individuals interested in modeling the spread of pathogens between farms across a landscape and using these models to evaluate disease control strategies.

Adaptive Control of Truss Structures for Gossamer Spacecraft

NASA Technical Reports Server (NTRS)

Yang, Bong-Jun; Calise, Anthony J.; Craig, James I.; Whorton, Mark S.

2007-01-01

Neural network-based adaptive control is considered for active control of a highly flexible truss structure which may be used to support solar sail membranes. The objective is to suppress unwanted vibrations in SAFE (Solar Array Flight Experiment) boom, a test-bed located at NASA. Compared to previous tests that restrained truss structures in planar motion, full three dimensional motions are tested. Experimental results illustrate the potential of adaptive control in compensating for nonlinear actuation and modeling error, and in rejecting external disturbances.

Traversing Microphone Track Installed in NASA Lewis' Aero-Acoustic Propulsion Laboratory Dome

NASA Technical Reports Server (NTRS)

Bauman, Steven W.; Perusek, Gail P.

1999-01-01

The Aero-Acoustic Propulsion Laboratory is an acoustically treated, 65-ft-tall dome located at the NASA Lewis Research Center. Inside this laboratory is the Nozzle Acoustic Test Rig (NATR), which is used in support of Advanced Subsonics Technology (AST) and High Speed Research (HSR) to test engine exhaust nozzles for thrust and acoustic performance under simulated takeoff conditions. Acoustic measurements had been gathered by a far-field array of microphones located along the dome wall and 10-ft above the floor. Recently, it became desirable to collect acoustic data for engine certifications (as specified by the Federal Aviation Administration (FAA)) that would simulate the noise of an aircraft taking off as heard from an offset ground location. Since nozzles for the High-Speed Civil Transport have straight sides that cause their noise signature to vary radially, an additional plane of acoustic measurement was required. Desired was an arched array of 24 microphones, equally spaced from the nozzle and each other, in a 25 off-vertical plane. The various research requirements made this a challenging task. The microphones needed to be aimed at the nozzle accurately and held firmly in place during testing, but it was also essential that they be easily and routinely lowered to the floor for calibration and servicing. Once serviced, the microphones would have to be returned to their previous location near the ceiling. In addition, there could be no structure could between the microphones and the nozzle, and any structure near the microphones would have to be designed to minimize noise reflections. After many concepts were considered, a single arched truss structure was selected that would be permanently affixed to the dome ceiling and to one end of the dome floor.

3D P-Wave Velocity Structure of the Crust and Relocation of Earthquakes in 21 the Lushan Source Area

NASA Astrophysics Data System (ADS)

Yu, X.; Wang, X.; Zhang, W.

2014-12-01

The double difference seismic tomography method is applied to the absolute first arrival P wave arrival times and high quality relative P arrival times of the Lushan seismic sequence to determine the detailed crustal 3D P wave velocity structure and the hypocenter parameters in the Lushan seismic area. The results show that the Lushan mainshock locates at 30.28 N, 103.98 E, with the depth of 16.38 km. The leading edge of aftershock in the northeast of mainshock present a spade with a steep dip angle, the aftershocks' extended length is about 12 km. In the southwest of the Lushan mainshock, the leading edge of aftershock in low velocity zone slope gently, the aftershocks' extended length is about 23 km. The P wave velocity structure of the Lushan seismic area shows obviously lateral heterogeneity. The P wave velocity anomalies represent close relationship with topographic relief and geological structure. In Baoxing area the complex rocks correspond obvious high-velocity anomalies extending down to 15 km depth，while the Cenozoic rocks are correlated with low-velocity anomalies. Our high-resolution tomographic model not only displays the general features contained in the previous models, but also reveals some new features. An obvious high-velocity anomaly is visible in Daxing area. The high-velocity anomalies beneath Baoxing and Daxing connect each other in 10 km depth, which makes the contrast between high and low velocity anomalies more sharp. Above 20 km depth the velocity structure in southwest and northeast segment of the mainshock shows a big difference: low-velocity anomalies are dominated the southwest segment, while high-velocity anomalies rule the northeast segment. The Lushan mainshock locates at the leading edge of a low-velocity anomaly surrounded by the Baoxing and Daxing high-velocity anomalies. The Lushan aftershocks in southwest are distributed in low-velocity anomalies or the transition belt: the footwall represents low-velocity anomalies, while the hanging wall shows high-velocity anomalies. The northeastern aftershocks are distributed at the boundary between high-velocity anomalies in Baoxing and Daxing area. The main seismogenic layer dips to northwest.

Spatial-Temporal Dynamics of High-Resolution Animal Networks: What Can We Learn from Domestic Animals?

PubMed

Chen, Shi; Ilany, Amiyaal; White, Brad J; Sanderson, Michael W; Lanzas, Cristina

2015-01-01

Animal social network is the key to understand many ecological and epidemiological processes. We used real-time location system (RTLS) to accurately track cattle position, analyze their proximity networks, and tested the hypothesis of temporal stationarity and spatial homogeneity in these networks during different daily time periods and in different areas of the pen. The network structure was analyzed using global network characteristics (network density), subgroup clustering (modularity), triadic property (transitivity), and dyadic interactions (correlation coefficient from a quadratic assignment procedure) at hourly level. We demonstrated substantial spatial-temporal heterogeneity in these networks and potential link between indirect animal-environment contact and direct animal-animal contact. But such heterogeneity diminished if data were collected at lower spatial (aggregated at entire pen level) or temporal (aggregated at daily level) resolution. The network structure (described by the characteristics such as density, modularity, transitivity, etc.) also changed substantially at different time and locations. There were certain time (feeding) and location (hay) that the proximity network structures were more consistent based on the dyadic interaction analysis. These results reveal new insights for animal network structure and spatial-temporal dynamics, provide more accurate descriptions of animal social networks, and allow more accurate modeling of multiple (both direct and indirect) disease transmission pathways.

Sub-Frequency Interval Approach in Electromechanical Impedance Technique for Concrete Structure Health Monitoring

PubMed Central

Yang, Yaowen; Divsholi, Bahador Sabet

2010-01-01

The electromechanical (EM) impedance technique using piezoelectric lead zirconate titanate (PZT) transducers for structural health monitoring (SHM) has attracted considerable attention in various engineering fields. In the conventional EM impedance technique, the EM admittance of a PZT transducer is used as a damage indicator. Statistical analysis methods such as root mean square deviation (RMSD) have been employed to associate the damage level with the changes in the EM admittance signatures, but it is difficult to determine the location of damage using such methods. This paper proposes a new approach by dividing the large frequency (30–400 kHz) range into sub-frequency intervals and calculating their respective RMSD values. The RMSD of the sub-frequency intervals (RMSD-S) will be used to study the severity and location of damage. An experiment is carried out on a real size concrete structure subjected to artificial damage. It is observed that damage close to the PZT changes the high frequency range RMSD-S significantly, while the damage far away from the PZT changes the RMSD-S in the low frequency range significantly. The relationship between the frequency range and the PZT sensing region is also presented. Finally, a damage identification scheme is proposed to estimate the location and severity of damage in concrete structures. PMID:22163548

Experimental assessment and analysis of super-resolution in fluorescence microscopy based on multiple-point spread function fitting of spectrally demultiplexed images

NASA Astrophysics Data System (ADS)

Nishimura, Takahiro; Kimura, Hitoshi; Ogura, Yusuke; Tanida, Jun

2018-06-01

This paper presents an experimental assessment and analysis of super-resolution microscopy based on multiple-point spread function fitting of spectrally demultiplexed images using a designed DNA structure as a test target. For the purpose, a DNA structure was designed to have binding sites at a certain interval that is smaller than the diffraction limit. The structure was labeled with several types of quantum dots (QDs) to acquire their spatial information as spectrally encoded images. The obtained images are analyzed with a point spread function multifitting algorithm to determine the QD locations that indicate the binding site positions. The experimental results show that the labeled locations can be observed beyond the diffraction-limited resolution using three-colored fluorescence images that were obtained with a confocal fluorescence microscope. Numerical simulations show that labeling with eight types of QDs enables the positions aligned at 27.2-nm pitches on the DNA structure to be resolved with high accuracy.

Functional gene diversity of soil microbial communities from five oil-contaminated fields in China.

PubMed

Liang, Yuting; Van Nostrand, Joy D; Deng, Ye; He, Zhili; Wu, Liyou; Zhang, Xu; Li, Guanghe; Zhou, Jizhong

2011-03-01

To compare microbial functional diversity in different oil-contaminated fields and to know the effects of oil contaminant and environmental factors, soil samples were taken from typical oil-contaminated fields located in five geographic regions of China. GeoChip, a high-throughput functional gene array, was used to evaluate the microbial functional genes involved in contaminant degradation and in other major biogeochemical/metabolic processes. Our results indicated that the overall microbial community structures were distinct in each oil-contaminated field, and samples were clustered by geographic locations. The organic contaminant degradation genes were most abundant in all samples and presented a similar pattern under oil contaminant stress among the five fields. In addition, alkane and aromatic hydrocarbon degradation genes such as monooxygenase and dioxygenase were detected in high abundance in the oil-contaminated fields. Canonical correspondence analysis indicated that the microbial functional patterns were highly correlated to the local environmental variables, such as oil contaminant concentration, nitrogen and phosphorus contents, salt and pH. Finally, a total of 59% of microbial community variation from GeoChip data can be explained by oil contamination, geographic location and soil geochemical parameters. This study provided insights into the in situ microbial functional structures in oil-contaminated fields and discerned the linkages between microbial communities and environmental variables, which is important to the application of bioremediation in oil-contaminated sites.

Functional gene diversity of soil microbial communities from five oil-contaminated fields in China

PubMed Central

Liang, Yuting; Van Nostrand, Joy D; Deng, Ye; He, Zhili; Wu, Liyou; Zhang, Xu; Li, Guanghe; Zhou, Jizhong

2011-01-01

To compare microbial functional diversity in different oil-contaminated fields and to know the effects of oil contaminant and environmental factors, soil samples were taken from typical oil-contaminated fields located in five geographic regions of China. GeoChip, a high-throughput functional gene array, was used to evaluate the microbial functional genes involved in contaminant degradation and in other major biogeochemical/metabolic processes. Our results indicated that the overall microbial community structures were distinct in each oil-contaminated field, and samples were clustered by geographic locations. The organic contaminant degradation genes were most abundant in all samples and presented a similar pattern under oil contaminant stress among the five fields. In addition, alkane and aromatic hydrocarbon degradation genes such as monooxygenase and dioxygenase were detected in high abundance in the oil-contaminated fields. Canonical correspondence analysis indicated that the microbial functional patterns were highly correlated to the local environmental variables, such as oil contaminant concentration, nitrogen and phosphorus contents, salt and pH. Finally, a total of 59% of microbial community variation from GeoChip data can be explained by oil contamination, geographic location and soil geochemical parameters. This study provided insights into the in situ microbial functional structures in oil-contaminated fields and discerned the linkages between microbial communities and environmental variables, which is important to the application of bioremediation in oil-contaminated sites. PMID:20861922

Isotopic structure of Lake Whitefish in Lake Huron: Evidence for regional and local populations based on resource use

USGS Publications Warehouse

Eberts, Rebecca L.; Wissel, Bjorn; Simpson, Gavin L.; Crawford, Stephen S.; Stott, Wendylee; Hanner, Robert H.; Manzon, Richard G.; Wilson, Joanna Y.; Boreham, Douglas R.; Somers, Christopher M.

2017-01-01

Lake Whitefish Coregonus clupeaformis is the most commercially valuable species in Lake Huron. The fishery for this species has historically been managed based on 25 management units (17 in Canada, 8 in the USA). However, congruence between the contemporary population structure of Lake Whitefish and management units is poorly understood. We used stable isotopes of carbon (δ13C) and nitrogen (δ15N), food web markers that reflect patterns in resource use (i.e., prey, location, habitat), to assess the population structure of spawning-phase Lake Whitefish collected from 32 sites (1,474 fish) across Lake Huron. We found large isotopic variation among fish from different sites (ranges: δ13C = 10.2‰, δ15N = 5.5‰) and variable niche size and levels of overlap (standard ellipse area = 1.0–4.3‰2). Lake Huron contained spawning-phase fish from four major isotopic clusters largely defined by extensive variation in δ13C, and the isotopic composition of fish sampled was spatially structured both within and between lake basins. Based on cluster compositions, we identified six putative regional groups, some of which represented sites of high diversity (three to four clusters) and others with less (one to two clusters). Analysis of isotopic values from Lake Whitefish collected from summer feeding locations and baseline prey items showed similar isotopic variation and established spatial linkage between spawning-phase and summer fish. Our results show that summer feeding location contributes strongly to the isotopic structure we observed in spawning-phase fish. One of the regional groups we identified in northern Georgian Bay is highly distinct based on isotopic composition and possibly ecologically unique within Lake Huron. Our findings are congruent with several previous studies using different markers (genetics, mark–recapture), and we conclude that current management units are generally too small and numerous to reflect the population structure of Lake Whitefish in Lake Huron.

Wave Propagation in Aluminum Honeycomb Plate and Debonding Detection Using Scanning Laser Vibrometer.

PubMed

Zhao, Jingjing; Li, Fucai; Cao, Xiao; Li, Hongguang

2018-05-23

Both the aerospace and marine industry have widely relied on a honeycomb sandwich structure (HSS) because of its high strength-to-weight ratio. However, the intrinsic nature of an adhesively bonded multi-layer structure increases the risk of debonding when the structure is under strain or exposed to varying temperatures. Such defects are normally concealed under the surface but can significantly compromise the strength and stiffness of a structure. In this paper, the guided wave method is used to detect debondings which are located between the skin and the honeycomb in sandwich plates. The propagation of guided waves in honeycomb plates is investigated via numerical techniques, with emphasis placed on demonstrating the behavior of structure-based wave interactions (SWIs). The SWI technique is effective to distinguish heterogeneous structures from homogeneous structures. The excitation frequency is necessary to generate obvious SWIs in HSSs; accordingly, a novel strategy is proposed to select the optimal excitation frequencies. A series of experiments are conducted, the results of which show that the presented procedure can be used to effectively detect the locations and the sizes of single- and multi-damage zones in HSSs.

CENDI Indexing Workshop

NASA Technical Reports Server (NTRS)

1994-01-01

The CENDI Indexing Workshop held at NASA Headquarters, Two Independence Square, 300 E Street, Washington, DC, on September 21-22, 1994 focused on the following topics: machine aided indexing, indexing quality, an indexing pilot project, the MedIndEx Prototype, Department of Energy/Office of Scientific and Technical Information indexing activities, high-tech coding structures, category indexing schemes, and the Government Information Locator Service. This publication consists mostly of viewgraphs related to the above noted topics. In an appendix is a description of the Government Information Locator Service.

SEGMENTATION OF MITOCHONDRIA IN ELECTRON MICROSCOPY IMAGES USING ALGEBRAIC CURVES.

PubMed

Seyedhosseini, Mojtaba; Ellisman, Mark H; Tasdizen, Tolga

2013-01-01

High-resolution microscopy techniques have been used to generate large volumes of data with enough details for understanding the complex structure of the nervous system. However, automatic techniques are required to segment cells and intracellular structures in these multi-terabyte datasets and make anatomical analysis possible on a large scale. We propose a fully automated method that exploits both shape information and regional statistics to segment irregularly shaped intracellular structures such as mitochondria in electron microscopy (EM) images. The main idea is to use algebraic curves to extract shape features together with texture features from image patches. Then, these powerful features are used to learn a random forest classifier, which can predict mitochondria locations precisely. Finally, the algebraic curves together with regional information are used to segment the mitochondria at the predicted locations. We demonstrate that our method outperforms the state-of-the-art algorithms in segmentation of mitochondria in EM images.

Carbon Nanotube-Based Structural Health Monitoring Sensors

NASA Technical Reports Server (NTRS)

Wincheski, Russell; Jordan, Jeffrey; Oglesby, Donald; Watkins, Anthony; Patry, JoAnne; Smits, Jan; Williams, Phillip

2011-01-01

Carbon nanotube (CNT)-based sensors for structural health monitoring (SHM) can be embedded in structures of all geometries to monitor conditions both inside and at the surface of the structure to continuously sense changes. These CNTs can be manipulated into specific orientations to create small, powerful, and flexible sensors. One of the sensors is a highly flexible sensor for crack growth detection and strain field mapping that features a very dense and highly ordered array of single-walled CNTs. CNT structural health sensors can be mass-produced, are inexpensive, can be packaged in small sizes (0.5 micron(sup 2)), require less power than electronic or piezoelectric transducers, and produce less waste heat per square centimeter than electronic or piezoelectric transducers. Chemically functionalized lithographic patterns are used to deposit and align the CNTs onto metallic electrodes. This method consistently produces aligned CNTs in the defined locations. Using photo- and electron-beam lithography, simple Cr/Au thin-film circuits are patterned onto oxidized silicon substrates. The samples are then re-patterned with a CNT-attracting, self-assembled monolayer of 3-aminopropyltriethoxysilane (APTES) to delineate the desired CNT locations between electrodes. During the deposition of the solution-suspended single- wall CNTs, the application of an electric field to the metallic contacts causes alignment of the CNTs along the field direction. This innovation is a prime candidate for smart skin technologies with applications ranging from military, to aerospace, to private industry.

Preliminary results of the study of lightning location relative to storm structure and dynamics

NASA Technical Reports Server (NTRS)

Rust, W. D.; Taylor, W. L.; Macgorman, D.

1981-01-01

Lightning is being studied relative to storm structure using a VHF space-time discharge mapping system, radar, a cloud-to-ground flash locator, acoustic reconstruction of thunder, and other instrumentation. The horizontal discharge processes within the cloud generally propagate at speeds of 10,000-100,000 m/s. Horizontal extents of lightning were found up to 90 km. In an analysis of a limited number of flashes, lightning occurred in or near regions of high cyclonic shear. Positive cloud-to-ground flashes have been observed emanating from several identifiable regions of severe storms. Lightning echoes observed with 10-cm radar generally are 10-25 dB greater than the largest precipitation echo in the storm.

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

Unkelbach, Jan, E-mail: junkelbach@mgh.harvard.edu; Botas, Pablo; Faculty of Physics, Ruprecht-Karls-Universität Heidelberg, Heidelberg

Purpose: We describe a treatment plan optimization method for intensity modulated proton therapy (IMPT) that avoids high values of linear energy transfer (LET) in critical structures located within or near the target volume while limiting degradation of the best possible physical dose distribution. Methods and Materials: To allow fast optimization based on dose and LET, a GPU-based Monte Carlo code was extended to provide dose-averaged LET in addition to dose for all pencil beams. After optimizing an initial IMPT plan based on physical dose, a prioritized optimization scheme is used to modify the LET distribution while constraining the physical dosemore » objectives to values close to the initial plan. The LET optimization step is performed based on objective functions evaluated for the product of LET and physical dose (LET×D). To first approximation, LET×D represents a measure of the additional biological dose that is caused by high LET. Results: The method is effective for treatments where serial critical structures with maximum dose constraints are located within or near the target. We report on 5 patients with intracranial tumors (high-grade meningiomas, base-of-skull chordomas, ependymomas) in whom the target volume overlaps with the brainstem and optic structures. In all cases, high LET×D in critical structures could be avoided while minimally compromising physical dose planning objectives. Conclusion: LET-based reoptimization of IMPT plans represents a pragmatic approach to bridge the gap between purely physical dose-based and relative biological effectiveness (RBE)-based planning. The method makes IMPT treatments safer by mitigating a potentially increased risk of side effects resulting from elevated RBE of proton beams near the end of range.« less

Tree species composition and structure in an old bottomland hardwood forest in south-central Arkansas

Treesearch

Brian Roy Lockhart; James M. Guldin; Thomas Foti

2010-01-01

Tree species composition and structure was determined for an old bottomland hardwood forest located in the Moro Creek Bottoms Natural Area in south-central Arkansas. Diversity for this forest was high with species richness ranging from 33 for the overstory and sapling strata to 26 for the seedling stratum and Shannon-Weiner values of 2.54 to 1.02 for the overstory and...

Passive Bistatic Radar and Waveform Diversity

DTIC Science & Technology

2009-11-01

transmission, but these are significantly beyond the detection ranges of interest. The sidelobe structure of the ambiguity function is flat , as would...kHz (corresponding to a monostatic range resolution c/2B = 3000 m). The transmitters are usually sited on tall towers or masts in high locations. The...peak and the sidelobe structure are well-defined, though the peak Passive Bistatic Radar and Waveform Diversity RTO-EN-SET-119(2009) 3 - 5

Combined X-ray and neutron fibre diffraction studies of biological and synthetic polymers

NASA Astrophysics Data System (ADS)

Parrot, I. M.; Urban, V.; Gardner, K. H.; Forsyth, V. T.

2005-08-01

The fibrous state is a natural one for polymer molecules which tend to assume regular helical conformations rather than the globular structures characteristic of many proteins. Fibre diffraction therefore has broad application to the study of a wide range of biological and synthetic polymers. The purpose of this paper is to illustrate the general scope of the method and in particular to demonstrate the impact of a combined approach involving both X-ray and neutron diffraction methods. While the flux of modern X-ray synchrotron radiation sources allows high quality datasets to be recorded with good resolution within a very short space of time, neutron studies can provide unique information through the ability to locate hydrogen or deuterium atoms that are often difficult or impossible to locate using X-ray methods. Furthermore, neutron fibre diffraction methods can, through the ability to selectively label specific parts of a structure, be used to highlight novel aspects of polymer structure that can not be studied using X-rays. Two examples are given. The first describes X-ray and neutron diffraction studies of conformational transitions in DNA. The second describes structural studies of the synthetic high-performance polymer poly(p-phenylene terephthalamide) (PPTA), known commercially as Kevlar® or Twaron®.

Analysis of a Hybrid Wing Body Center Section Test Article

NASA Technical Reports Server (NTRS)

Wu, Hsi-Yung T.; Shaw, Peter; Przekop, Adam

2013-01-01

The hybrid wing body center section test article is an all-composite structure made of crown, floor, keel, bulkhead, and rib panels utilizing the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) design concept. The primary goal of this test article is to prove that PRSEUS components are capable of carrying combined loads that are representative of a hybrid wing body pressure cabin design regime. This paper summarizes the analytical approach, analysis results, and failure predictions of the test article. A global finite element model of composite panels, metallic fittings, mechanical fasteners, and the Combined Loads Test System (COLTS) test fixture was used to conduct linear structural strength and stability analyses to validate the specimen under the most critical combination of bending and pressure loading conditions found in the hybrid wing body pressure cabin. Local detail analyses were also performed at locations with high stress concentrations, at Tee-cap noodle interfaces with surrounding laminates, and at fastener locations with high bearing/bypass loads. Failure predictions for different composite and metallic failure modes were made, and nonlinear analyses were also performed to study the structural response of the test article under combined bending and pressure loading. This large-scale specimen test will be conducted at the COLTS facility at the NASA Langley Research Center.

Developments of sulcal pattern and subcortical structures of the forebrain in cynomolgus monkey fetuses: 7-tesla magnetic resonance imaging provides high reproducibility of gross structural changes.

PubMed

Sawada, Kazuhiko; Sun, Xue-Zhi; Fukunishi, Katsuhiro; Kashima, Masatoshi; Sakata-Haga, Hiromi; Tokado, Hiroshi; Aoki, Ichio; Fukui, Yoshihiro

2009-09-01

The aim of this study was to spatio-temporally clarify gross structural changes in the forebrain of cynomolgus monkey fetuses using 7-tesla magnetic resonance imaging (MRI). T(1)-weighted coronal, horizontal, and sagittal MR slices of fixed left cerebral hemispheres were obtained from one male fetus at embryonic days (EDs) 70-150. The timetable for fetal sulcation by MRI was in good agreement with that by gross observations, with a lag time of 10-30 days. A difference in detectability of some sulci seemed to be associated with the length, depth, width, and location of the sulci. Furthermore, MRI clarified the embryonic days of the emergence of the callosal (ED 70) and circular (ED 90) sulci, which remained unpredictable under gross observations. Also made visible by the present MRI were subcortical structures of the forebrain such as the caudate nucleus, globus pallidus, putamen, major subdivisions of the thalamus, and hippocampal formation. Their adult-like features were formed by ED 100, corresponding to the onset of a signal enhancement in the gray matter, which reflects neuronal maturation. The results reveal a highly reproducible level of gross structural changes in the forebrain using a high spatial 7-tesla MRI. The present MRI study clarified some changes that are difficult to demonstrate nondestructively using only gross observations, for example, the development of cerebral sulci located on the deep portions of the cortex, as well as cortical and subcortical neuronal maturation.

Geological indicators for impact: The anomalous case of the Vredefort structure, South Africa

NASA Technical Reports Server (NTRS)

Antoine, L. A. G.; Reimold, W. U.

1988-01-01

The Vredefort Dome is located within and almost central to the Witwatersrand basin in its presently known extent. It exposes a central Archean granite core which is surrounded by a collar of supracrustal rocks. These collar rocks outline a strong polygonal geometry. The Archean core is comprised of two concentric zones, the Outer Granite Gneiss (OGG), and the core central Inlandsee Leucogranofels (ILG). The rocks of the inner core display granulite facies metamorphism, while the OGG is in amphibolite facies. The inner core is believed from recent drill hole information to be underlain by mafic and ultramafic gneisses, the extent of which cannot be assessed at present. A fairly broad zone of charnockites separates the OGG and ILG domains. This zone is characterized by a high concentration of pseudotachylite and ductile shearing. Whereas a number of other domical structures are located within or surrounding the Witwatersrand basin, the Vredefort structure is anomalous, in that it has: a partly polygonal geometry; extensive alkali intrusives in the northwestern sector; granophyre dykes (ring-dykes peripheral to the contact collar-basement and NW-SE or NE-SW trending dykes within the Archean basement); contact metamorphism of the collar supracrustal rocks; the overturning of collar supracrustals in the northern sectors; deformation phenomena widely regarded as representing shock metamorphism (pseudotachylite, (sub)planar microdeformation features in quartz, shatter cones and occurrences of high-P quartz polymorphs); a positive 30 mgal gravity anomaly; and high amplitude magnetic anomalies. Recent geophysical, structural and petrological evidence pertinent for the identification of the processes that led to the formation of the Vredefort structure are summarized.

High spatial resolution mapping of folds and fractures using Unmanned Aerial Vehicle (UAV) photogrammetry

NASA Astrophysics Data System (ADS)

Cruden, A. R.; Vollgger, S.

2016-12-01

The emerging capability of UAV photogrammetry combines a simple and cost-effective method to acquire digital aerial images with advanced computer vision algorithms that compute spatial datasets from a sequence of overlapping digital photographs from various viewpoints. Depending on flight altitude and camera setup, sub-centimeter spatial resolution orthophotographs and textured dense point clouds can be achieved. Orientation data can be collected for detailed structural analysis by digitally mapping such high-resolution spatial datasets in a fraction of time and with higher fidelity compared to traditional mapping techniques. Here we describe a photogrammetric workflow applied to a structural study of folds and fractures within alternating layers of sandstone and mudstone at a coastal outcrop in SE Australia. We surveyed this location using a downward looking digital camera mounted on commercially available multi-rotor UAV that autonomously followed waypoints at a set altitude and speed to ensure sufficient image overlap, minimum motion blur and an appropriate resolution. The use of surveyed ground control points allowed us to produce a geo-referenced 3D point cloud and an orthophotograph from hundreds of digital images at a spatial resolution < 10 mm per pixel, and cm-scale location accuracy. Orientation data of brittle and ductile structures were semi-automatically extracted from these high-resolution datasets using open-source software. This resulted in an extensive and statistically relevant orientation dataset that was used to 1) interpret the progressive development of folds and faults in the region, and 2) to generate a 3D structural model that underlines the complex internal structure of the outcrop and quantifies spatial variations in fold geometries. Overall, our work highlights how UAV photogrammetry can contribute to new insights in structural analysis.

Stirling engine - Approach for long-term durability assessment

NASA Technical Reports Server (NTRS)

Tong, Michael T.; Bartolotta, Paul A.; Halford, Gary R.; Freed, Alan D.

1992-01-01

The approach employed by NASA Lewis for the long-term durability assessment of the Stirling engine hot-section components is summarized. The approach consists of: preliminary structural assessment; development of a viscoplastic constitutive model to accurately determine material behavior under high-temperature thermomechanical loads; an experimental program to characterize material constants for the viscoplastic constitutive model; finite-element thermal analysis and structural analysis using a viscoplastic constitutive model to obtain stress/strain/temperature at the critical location of the hot-section components for life assessment; and development of a life prediction model applicable for long-term durability assessment at high temperatures. The approach should aid in the provision of long-term structural durability and reliability of Stirling engines.

Acoustic emission source location in composite structure by Voronoi construction using geodesic curve evolution.

PubMed

Gangadharan, R; Prasanna, G; Bhat, M R; Murthy, C R L; Gopalakrishnan, S

2009-11-01

Conventional analytical/numerical methods employing triangulation technique are suitable for locating acoustic emission (AE) source in a planar structure without structural discontinuities. But these methods cannot be extended to structures with complicated geometry, and, also, the problem gets compounded if the material of the structure is anisotropic warranting complex analytical velocity models. A geodesic approach using Voronoi construction is proposed in this work to locate the AE source in a composite structure. The approach is based on the fact that the wave takes minimum energy path to travel from the source to any other point in the connected domain. The geodesics are computed on the meshed surface of the structure using graph theory based on Dijkstra's algorithm. By propagating the waves in reverse virtually from these sensors along the geodesic path and by locating the first intersection point of these waves, one can get the AE source location. In this work, the geodesic approach is shown more suitable for a practicable source location solution in a composite structure with arbitrary surface containing finite discontinuities. Experiments have been conducted on composite plate specimens of simple and complex geometry to validate this method.

Variation in the helminth community structure of Thrichomys pachyurus (Rodentia: Echimyidae) in two sub-regions of the Brazilian Pantanal: the effects of land use and seasonality.

PubMed

Simões, R; Gentile, R; Rademaker, V; D'Andrea, P; Herrera, H; Freitas, T; Lanfredi, R; Maldonado, A

2010-09-01

The Pantanal is a large ecosystem located in South America. This preserved area is seasonally flooded due to abundant rainfall during the summer and the subsequent overflow of the Paraguai River. In this paper, we examine the helminth community structure in the wild rodent Thrichomys pachyurus during the wet and dry seasons in two locations of the preserved and cattle ranching areas in the Southern Pantanal. We identified 12 species of helminth, and, although we did not find any differences in species richness between locations within the Pantanal, we found that richness was higher during the wet season. Helminth species were largely aggregated in both farm locations and during seasons. The most common helminth species were more abundant during the dry season than during the wet season, which may have been due to the increased habitat availability and rodent population increase. The intensity of the infection also followed the same pattern for most helminths. The trichostrongylids (Heligmostrongylus crucifer, H. almeidai and Pudica cercomysi) were dominant at both farm locations. The land use of each area was not correlated with helminth diversity. However, species composition of the helminth community of T. pachyurus differed between locations and may be correlated with environmental differences between the habitats. The seasonality of the Pantanal was highly correlated with helminth parasitism in T. pachyurus.

The persistence of the attentional bias to regularities in a changing environment.

PubMed

Yu, Ru Qi; Zhao, Jiaying

2015-10-01

The environment often is stable, but some aspects may change over time. The challenge for the visual system is to discover and flexibly adapt to the changes. We examined how attention is shifted in the presence of changes in the underlying structure of the environment. In six experiments, observers viewed four simultaneous streams of objects while performing a visual search task. In the first half of each experiment, the stream in the structured location contained regularities, the shapes in the random location were randomized, and gray squares appeared in two neutral locations. In the second half, the stream in the structured or the random location may change. In the first half of all experiments, visual search was facilitated in the structured location, suggesting that attention was consistently biased toward regularities. In the second half, this bias persisted in the structured location when no change occurred (Experiment 1), when the regularities were removed (Experiment 2), or when new regularities embedded in the original or novel stimuli emerged in the previously random location (Experiments 3 and 6). However, visual search was numerically but no longer reliably faster in the structured location when the initial regularities were removed and new regularities were introduced in the previously random location (Experiment 4), or when novel random stimuli appeared in the random location (Experiment 5). This suggests that the attentional bias was weakened. Overall, the results demonstrate that the attentional bias to regularities was persistent but also sensitive to changes in the environment.

Intraoperative high-field magnetic resonance imaging, multimodal neuronavigation, and intraoperative electrophysiological monitoring-guided surgery for treating supratentorial cavernomas.

PubMed

Li, Fang-Ye; Chen, Xiao-Lei; Xu, Bai-Nan

2016-09-01

To determine the beneficial effects of intraoperative high-field magnetic resonance imaging (MRI), multimodal neuronavigation, and intraoperative electrophysiological monitoring-guided surgery for treating supratentorial cavernomas. Twelve patients with 13 supratentorial cavernomas were prospectively enrolled and operated while using a 1.5 T intraoperative MRI, multimodal neuronavigation, and intraoperative electrophysiological monitoring. All cavernomas were deeply located in subcortical areas or involved critical areas. Intraoperative high-field MRIs were obtained for the intraoperative "visualization" of surrounding eloquent structures, "brain shift" corrections, and navigational plan updates. All cavernomas were successfully resected with guidance from intraoperative MRI, multimodal neuronavigation, and intraoperative electrophysiological monitoring. In 5 cases with supratentorial cavernomas, intraoperative "brain shift" severely deterred locating of the lesions; however, intraoperative MRI facilitated precise locating of these lesions. During long-term (>3 months) follow-up, some or all presenting signs and symptoms improved or resolved in 4 cases, but were unchanged in 7 patients. Intraoperative high-field MRI, multimodal neuronavigation, and intraoperative electrophysiological monitoring are helpful in surgeries for the treatment of small deeply seated subcortical cavernomas.

Relaxation mechanisms, structure and properties of semi-coherent interfaces

DOE PAGES

Shao, Shuai; Wang, Jian

2015-10-15

In this work, using the Cu–Ni (111) semi-coherent interface as a model system, we combine atomistic simulations and defect theory to reveal the relaxation mechanisms, structure, and properties of semi-coherent interfaces. By calculating the generalized stacking fault energy (GSFE) profile of the interface, two stable structures and a high-energy structure are located. During the relaxation, the regions that possess the stable structures expand and develop into coherent regions; the regions with high-energy structure shrink into the intersection of misfit dislocations (nodes). This process reduces the interface excess potential energy but increases the core energy of the misfit dislocations and nodes.more » The core width is dependent on the GSFE of the interface. The high-energy structure relaxes by relative rotation and dilatation between the crystals. The relative rotation is responsible for the spiral pattern at nodes. The relative dilatation is responsible for the creation of free volume at nodes, which facilitates the nodes’ structural transformation. Several node structures have been observed and analyzed. In conclusion, the various structures have significant impact on the plastic deformation in terms of lattice dislocation nucleation, as well as the point defect formation energies.« less

High pressure hydrogen stabilised by quantum nuclear motion

NASA Astrophysics Data System (ADS)

Needs, Richard; Monserrat, Bartomeu; Pickard, Chris

Hydrogen under extreme pressures is of fundamental interest, as it might exhibit exotic physical phenomena, and of practical interest, as it is a major component of many astrophysical objects. Structure searches have been successful at identifying promising candidates for the known phases of high pressure hydrogen. However, these searches have so far been restricted to the location of minima of the potential energy landscape. In this talk, we will describe a new structure searching method, ``saddle-point ab initio random structure searching'' (sp-AIRSS), that allows us to identify structures associated with saddle points of the potential energy landscape. Using sp-AIRSS, we find two new high-pressure hydrogen structures that exhibit a harmonic dynamical instability, but quantum and thermal anharmonic motion render them dynamically stable. These structures are formed by mixed layers of strongly and softly bound hydrogen molecules, and become thermodynamically competitive at the highest pressures reached in experiment. The experimental implications of these new structures will also be discussed. BM is supported by Robinson College, Cambridge, and the Cambridge Philosophical Society. RJN and CJP are supported by the Engineering and Physical Sciences Research Council (EPSRC) of the UK.

Corrosion monitoring using high-frequency guided waves

NASA Astrophysics Data System (ADS)

Fromme, P.

2016-04-01

Corrosion can develop due to adverse environmental conditions during the life cycle of a range of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Generalized corrosion leading to wall thickness loss can cause the reduction of the strength and thus degradation of the structural integrity. The monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic wedge transducers with single sided access to the structure, guided wave modes were selectively generated that penetrate through the complete thickness of the structure. The wave propagation and interference of the different guided wave modes depends on the thickness of the structure. Laboratory experiments were conducted for wall thickness reduction due to milling of the steel structure. From the measured signal changes due to the wave mode interference the reduced wall thickness was monitored. Good agreement with theoretical predictions was achieved. The high frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

Corrosion monitoring using high-frequency guided ultrasonic waves

NASA Astrophysics Data System (ADS)

Fromme, Paul

2014-02-01

Corrosion develops due to adverse environmental conditions during the life cycle of a range of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Both pitting corrosion and generalized corrosion leading to wall thickness loss can cause the degradation of the structural integrity. The nondestructive detection and monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic transducers with single sided access to the structure, guided wave modes were generated that penetrate through the complete thickness of the structure. The wave propagation and interference of the different guided wave modes depends on the thickness of the structure. Laboratory experiments were conducted and the wall thickness reduced by consecutive milling of the steel structure. Further measurements were conducted using accelerated corrosion in a salt water bath and the damage severity monitored. From the measured signal change due to the wave mode interference the wall thickness reduction was monitored. The high frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

Flow rate measurement in a volume

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

Galvez, Cristhian

A system for measuring flow rate within a volume includes one or more transmission devices that transmit one or more signals through fluid contained within the volume. The volume may be bounded, at least in part, by an outer structure and by an object at least partially contained within the outer structure. A transmission device located at a first location of the outer structure transmits a first signal to a second location of the outer structure. A second signal is transmitted through the fluid from the second location to a third location of the outer structure. The flow rate ofmore » the fluid within the volume may be determined based, at least in part, on the time of flight of both the first signal and the second signal.« less

Mars Life? - Microscopic Tube-like Structures

NASA Technical Reports Server (NTRS)

1996-01-01

This high-resolution scanning electron microscope image shows an unusual tube-like structural form that is less than 1/100th the width of a human hair in size found in meteorite ALH84001, a meteorite believed to be of Martian origin. Although this structure is not part of the research published in the Aug. 16 issue of the journal Science, it is located in a similar carbonate glob in the meteorite. This structure will be the subject of future investigations that could confirm whether or not it is fossil evidence of primitive life on Mars 3.6 billion years ago.

Geo Techno Park potential at Arjuno-Welirang Volcano hosted geothermal area, Batu, East Java, Indonesia (Multi geophysical approach)

NASA Astrophysics Data System (ADS)

Maryanto, Sukir

2017-11-01

Arjuno Welirang Volcano Geothermal (AWVG) is located around Arjuno-Welirang Volcano in Malang, East Java, about 100 km southwest of Surabaya, the capital city of East Java province, and is still an undeveloped area of the geothermal field. The occurrence of solfatara and fumaroles with magmatic gasses indicated the existence of a volcanic geothermal system in the subsurface. A few hot springs are found in the Arjuno-Welirang volcanic complex, such as Padusan hot spring, Songgoriti hot spring, Kasinan hot spring, and Cangar hot spring. Multi geophysical observations in AWVG complex was carried out in order to explore the subsurface structure in supporting the plan of Geo Techno Park at the location. Gravity, Magnetic, Microearthquake, and Electrical Resistivity Tomography (ERT) methods were used to investigate the major and minor active faulting zones whether hot springs circulation occurs in these zones. The gravity methods allowed us to locate the subsurface structure and to evaluate their geometrical relationship base on density anomaly. Magnetic methods allow us to discriminate conductive areas which could correspond to an increase in thermal fluid circulation in the investigated sites. Micro-earthquakes using particle motion analysis to locate the focal depth related with hydrothermal activity and electrical resistivity tomography survey offers methods to locate more detail subsurface structure and geothermal fluids near the surface by identifying areas affected by the geothermal fluid. The magnetic and gravity anomaly indicates the subsurface structure of AWVG is composed of basalt rock, sulfide minerals, sandstone, and volcanic rock with high minor active fault structure as a medium for fluid circulation. While using micro-earthquake data in AWVG shown shallow focal depth range approximate 60 meters which indicates shallow hydrothermal circulation in AWVG. The geothermal fluid circulation zones along the fault structure resulted in some hot springs in a central and north-western part of AWVG detected by the Electrical Resistivity Tomography, appear to be well correlated with corresponding features derived from the gravity, magnetic, and micro-earthquake survey. We just ongoing process to develop Arjuno Welirang Volcano & Geothermal Research Center (AWVGRC) located at Universitas Brawijaya Agro Techno Park, Cangar in the flank of Arjuno Welirang volcano complex. Due to our initial observations, AWVG has a great potential for a pilot project of an educational geo technopark development area.

Specific β-Turns Precede PPIIL Structures Binding to Allele-Specific HLA-DRβ1* PBRs in Fully-Protective Malaria Vaccine Components

PubMed Central

Bermudez, Adriana; Alba, Martha P.; Vanegas, Magnolia; Patarroyo, Manuel A.; Patarroyo, Manuel E.

2018-01-01

The 3D structural analysis of 62 peptides derived from highly pathogenic Plasmodium falciparum malaria parasite proteins involved in host cell invasion led to finding a striking association between particular β-turn types located in the N-terminal peripheral flanking residue region (preceding the polyproline II left-handed structures fitting into the HLA-DRβ* allele family) and modified immune protection-inducing protein structure induced long-lasting protective immunity. This is the first time association between two different secondary structures associated with a specific immunological function has been described: full, long-lasting protective immunity. PMID:29682500

Specific β-Turns Precede PPIIL Structures Binding to Allele-Specific HLA-DRβ1* PBRs in Fully-Protective Malaria Vaccine Components.

PubMed

Bermudez, Adriana; Alba, Martha P; Vanegas, Magnolia; Patarroyo, Manuel A; Patarroyo, Manuel E

2018-01-01

The 3D structural analysis of 62 peptides derived from highly pathogenic Plasmodium falciparum malaria parasite proteins involved in host cell invasion led to finding a striking association between particular β-turn types located in the N-terminal peripheral flanking residue region (preceding the polyproline II left-handed structures fitting into the HLA-DRβ * allele family) and modified i mmune protection-inducing protein structure induced long-lasting protective immunity. This is the first time association between two different secondary structures associated with a specific immunological function has been described: full, long-lasting protective immunity.

Specific β-turns precede PPIIL structures binding to allele-specific HLA-DRβ1* PBRs in fully-protective malaria vaccine components

NASA Astrophysics Data System (ADS)

Bermudez, Adriana; Alba, Martha P.; Vanegas, Magnolia; Patarroyo, Manuel A.; Patarroyo, Manuel E.

2018-04-01

The 3D structural analysis of 62 peptides derived from highly pathogenic Plasmodium falciparum malaria parasite proteins involved in host cell invasion led to finding a striking association between particular β-turn types located in the N-terminal peripheral flanking residue region (preceding the polyproline II left-handed structures fitting into the HLA-DRβ* allele family) and modified immune protection-inducing protein structure induced long-lasting protective immunity. This is the first time association between two different secondary structures associated with a specific immunological function has been described: full, long-lasting protective immunity.

Crystallization of dienelactone hydrolase in two space groups: structural changes caused by crystal packing

PubMed Central

Porter, Joanne L.; Carr, Paul D.; Collyer, Charles A.; Ollis, David L.

2014-01-01

Dienelactone hydrolase (DLH) is a monomeric protein with a simple α/β-hydrolase fold structure. It readily crystallizes in space group P212121 from either a phosphate or ammonium sulfate precipitation buffer. Here, the structure of DLH at 1.85 Å resolution crystallized in space group C2 with two molecules in the asymmetric unit is reported. When crystallized in space group P212121 DLH has either phosphates or sulfates bound to the protein in crucial locations, one of which is located in the active site, preventing substrate/inhibitor binding. Another is located on the surface of the enzyme coordinated by side chains from two different molecules. Crystallization in space group C2 from a sodium citrate buffer results in new crystallographic protein–protein interfaces. The protein backbone is highly similar, but new crystal contacts cause changes in side-chain orientations and in loop positioning. In regions not involved in crystal contacts, there is little change in backbone or side-chain configuration. The flexibility of surface loops and the adaptability of side chains are important factors enabling DLH to adapt and form different crystal lattices. PMID:25005082

Comment on "The May 20 (MW 6.1) and 29 (MW 6.0), 2012, Emilia (Po Plain, Northern Italy) earthquakes: New seismotectonic implications from subsurface geology and high-quality hypocenter location" by Carannante et al., 2015

NASA Astrophysics Data System (ADS)

Bonini, Lorenzo; Toscani, Giovanni; Seno, Silvio

2016-10-01

Carannante et al. (2015) proposed an original seismotectonic interpretation of the Ferrara arc in the Po Plain (Italy) based on an accurate hypocenter relocation of the 2012 Emilia earthquake sequence and on structural analyses of sub-surface data. They contend that the causative faults of the 2012 sequence do not belong to the fold-and-thrusts system comprising the Ferrara Arc but in fact are located in the underlying basement. In our view this interpretation does not agree with observations, including: 1) the structural interpretation of the seismic reflection lines, that contrasts with some of the available data, e.g. the stratigraphy inferred from deep wells; 2) the seismotectonic setting, that is based exclusively on the correlation between inferred structural features and the location of late aftershocks; and 3) the inconsistency of the proposed seismogenic sources with the elevation changes caused by the sequence. All these points compromise the Carannante et al.'s interpretation and, as a consequence, previously proposed seismotectonic models are still valid.

High-resolution resistivity imaging of marine gas hydrate structures by combined inversion of CSEM towed and ocean-bottom receiver data

NASA Astrophysics Data System (ADS)

Attias, Eric; Weitemeyer, Karen; Hölz, Sebastian; Naif, Samer; Minshull, Tim A.; Best, Angus I.; Haroon, Amir; Jegen-Kulcsar, Marion; Berndt, Christian

2018-06-01

We present high-resolution resistivity imaging of gas hydrate pipe-like structures, as derived from marine controlled-source electromagnetic (CSEM) inversions that combine towed and ocean-bottom electric field receiver data, acquired from the Nyegga region, offshore Norway. Two-dimensional CSEM inversions applied to the towed receiver data detected four new prominent vertical resistive features that are likely gas hydrate structures, located in proximity to a major gas hydrate pipe-like structure, known as the CNE03 pockmark. The resistivity model resulting from the CSEM data inversion resolved the CNE03 hydrate structure in high resolution, as inferred by comparison to seismically constrained inversions. Our results indicate that shallow gas hydrate vertical features can be delineated effectively by inverting both ocean-bottom and towed receiver CSEM data simultaneously. The approach applied here can be utilised to map and monitor seafloor mineralisation, freshwater reservoirs, CO2 sequestration sites and near-surface geothermal systems.

Flame structure of methane/oxygen shear coaxial jet with velocity ratio using high-speed imaging and OH*, CH* chemiluminescence

NASA Astrophysics Data System (ADS)

Shim, Myungbo; Noh, Kwanyoung; Yoon, Woongsup

2018-06-01

In this study, the effects of gaseous methane/oxygen injection velocity ratio on the shear coaxial jet flame structure are analyzed using high-speed imaging along with OH* and CH* chemiluminescence. The images show that, as the velocity ratio is increased, the visual flame length increases and wrinkles of the flame front are developed further downstream. The region near the equivalence ratio 1 condition in the flame could be identified by the maximum OH* position, and this region is located further downstream as the velocity ratio is increased. The dominant CH* chemiluminescence is found in the near-injector region. As the velocity ratio is decreased, the signal intensity is higher at the same downstream distance in each flame. From the results, as the velocity ratio is decreased, there is increased entrainment of the external jet, the mixing of the two jets is enhanced, the region near the stoichiometric mixture condition is located further upstream, and consequently, the flame length decreases.

Automatic lung lobe segmentation using particles, thin plate splines, and maximum a posteriori estimation.

PubMed

Ross, James C; San José Estépar, Rail; Kindlmann, Gordon; Díaz, Alejandro; Westin, Carl-Fredrik; Silverman, Edwin K; Washko, George R

2010-01-01

We present a fully automatic lung lobe segmentation algorithm that is effective in high resolution computed tomography (CT) datasets in the presence of confounding factors such as incomplete fissures (anatomical structures indicating lobe boundaries), advanced disease states, high body mass index (BMI), and low-dose scanning protocols. In contrast to other algorithms that leverage segmentations of auxiliary structures (esp. vessels and airways), we rely only upon image features indicating fissure locations. We employ a particle system that samples the image domain and provides a set of candidate fissure locations. We follow this stage with maximum a posteriori (MAP) estimation to eliminate poor candidates and then perform a post-processing operation to remove remaining noise particles. We then fit a thin plate spline (TPS) interpolating surface to the fissure particles to form the final lung lobe segmentation. Results indicate that our algorithm performs comparably to pulmonologist-generated lung lobe segmentations on a set of challenging cases.

Automatic Lung Lobe Segmentation Using Particles, Thin Plate Splines, and Maximum a Posteriori Estimation

PubMed Central

Ross, James C.; Estépar, Raúl San José; Kindlmann, Gordon; Díaz, Alejandro; Westin, Carl-Fredrik; Silverman, Edwin K.; Washko, George R.

2011-01-01

We present a fully automatic lung lobe segmentation algorithm that is effective in high resolution computed tomography (CT) datasets in the presence of confounding factors such as incomplete fissures (anatomical structures indicating lobe boundaries), advanced disease states, high body mass index (BMI), and low-dose scanning protocols. In contrast to other algorithms that leverage segmentations of auxiliary structures (esp. vessels and airways), we rely only upon image features indicating fissure locations. We employ a particle system that samples the image domain and provides a set of candidate fissure locations. We follow this stage with maximum a posteriori (MAP) estimation to eliminate poor candidates and then perform a post-processing operation to remove remaining noise particles. We then fit a thin plate spline (TPS) interpolating surface to the fissure particles to form the final lung lobe segmentation. Results indicate that our algorithm performs comparably to pulmonologist-generated lung lobe segmentations on a set of challenging cases. PMID:20879396

Reduced-Order Modeling and Wavelet Analysis of Turbofan Engine Structural Response Due to Foreign Object Damage (FOD) Events

NASA Technical Reports Server (NTRS)

Turso, James; Lawrence, Charles; Litt, Jonathan

2004-01-01

The development of a wavelet-based feature extraction technique specifically targeting FOD-event induced vibration signal changes in gas turbine engines is described. The technique performs wavelet analysis of accelerometer signals from specified locations on the engine and is shown to be robust in the presence of significant process and sensor noise. It is envisioned that the technique will be combined with Kalman filter thermal/health parameter estimation for FOD-event detection via information fusion from these (and perhaps other) sources. Due to the lack of high-frequency FOD-event test data in the open literature, a reduced-order turbofan structural model (ROM) was synthesized from a finite element model modal analysis to support the investigation. In addition to providing test data for algorithm development, the ROM is used to determine the optimal sensor location for FOD-event detection. In the presence of significant noise, precise location of the FOD event in time was obtained using the developed wavelet-based feature.

Reduced-Order Modeling and Wavelet Analysis of Turbofan Engine Structural Response Due to Foreign Object Damage "FOD" Events

NASA Technical Reports Server (NTRS)

Turso, James A.; Lawrence, Charles; Litt, Jonathan S.

2007-01-01

The development of a wavelet-based feature extraction technique specifically targeting FOD-event induced vibration signal changes in gas turbine engines is described. The technique performs wavelet analysis of accelerometer signals from specified locations on the engine and is shown to be robust in the presence of significant process and sensor noise. It is envisioned that the technique will be combined with Kalman filter thermal/ health parameter estimation for FOD-event detection via information fusion from these (and perhaps other) sources. Due to the lack of high-frequency FOD-event test data in the open literature, a reduced-order turbofan structural model (ROM) was synthesized from a finite-element model modal analysis to support the investigation. In addition to providing test data for algorithm development, the ROM is used to determine the optimal sensor location for FOD-event detection. In the presence of significant noise, precise location of the FOD event in time was obtained using the developed wavelet-based feature.

Multi-scale multi-point observation of dipolarization in the near-Earth's magnetotail

NASA Astrophysics Data System (ADS)

Nakamura, R.; Varsani, A.; Genestreti, K.; Nakamura, T.; Baumjohann, W.; Birn, J.; Le Contel, O.; Nagai, T.

2017-12-01

We report on evolution of the dipolarization in the near-Earth plasma sheet during two intense substorms based on observations when the four spacecraft of the Magnetospheric Multiscale (MMS) together with GOES and Geotail were located in the near Earth magnetotail. These multiple spacecraft together with the ground-based magnetogram enabled to obtain the location of the large- scale substorm current wedge (SCW) and overall changes in the plasma sheet configuration. MMS was located in the southern hemisphere at the outer plasma sheet and observed fast flow disturbances associated with dipolarizations. The high time-resolution measurements from MMS enable us to detect the rapid motion of the field structures and the flow disturbances separately and to resolve signatures below the ion-scales. We found small-scale transient field-aligned current sheets associated with upward streaming cold plasmas and Hall-current layers in the fast flow shear region. Observations of these current structures are compared with simulations of reconnection jets.

The Mysterious Bar of the Large Magellanic Cloud: What Is It?

NASA Astrophysics Data System (ADS)

Subramaniam, Annapurni; Subramanian, Smitha

2009-09-01

The bar of the Large Magellanic Cloud (LMC) is one of the prominent, but controversial, features regarding its location with respect to the disk of the LMC. In order to study the relative location of the bar with respect to the disk, we present the high-resolution map of the structure across the LMC. We used the reddening corrected mean magnitudes (I 0) of red clump (RC) stars from the OGLE III catalog to map the relative variation in distance (vertical structure) or variation in RC population across the LMC. The bar does not appear as an identifiable vertical feature in the map, as there is no difference in I 0 values between the bar and the disk regions. We conclude that the LMC bar is very much part of the disk (within 0.02 mag), located in the plane of the disk and not a separate component. We identify warps or variation in RC population with increase in radial distance.

The SAFOD Pilot Hole seismic array: Wave propagation effects as a function of sensor depth and source location

NASA Astrophysics Data System (ADS)

Chavarria, J. Andres; Malin, Peter E.; Shalev, Eylon

2004-05-01

In July 2002 we installed a vertical array of seismometers in the San Andreas Fault Observatory at Depth (SAFOD) Pilot Hole (PH). The bottom of this 32 level, 1240 m long array of 3- components is located at a depth of ~2100 m below ground. Surface-explosion and microearthquake seismograms recorded by the array give valuable insights into the structure of the SAFOD site. The ratios of P- and S-wave velocities (Vp/Vs) along the array suggest the presence of two faults intersecting the PH. The Vp/Vs ratios also depend on source location, with high values to the NW, and lower ones to the SE, correlating with high and low creep rates along the SAF, respectively. Since higher ratios can be produced by increasing fluid saturation, we suggest that this effect might account for both our observations and their correlation with the creep distribution.

Chemodetection and Destruction of Host Urea Allows Helicobacter pylori to Locate the Epithelium

PubMed Central

Huang, Julie Y.; Sweeney, Emily Goers; Sigal, Michael; Zhang, Hai C.; Remington, S. James; Cantrell, Michael A.; Kuo, Calvin J.; Guillemin, Karen; Amieva, Manuel R.

2015-01-01

SUMMARY The gastric pathogen Helicobacter pylori interacts intimately with the gastric mucosa to avoid the microbicidal acid in the stomach lumen. The cues H. pylori senses to locate and colonize the gastric epithelium have not been well defined. We show that metabolites emanating from human gastric organoids rapidly attract H. pylori. This response is largely controlled by the bacterial chemoreceptor TlpB, and the main attractant emanating from epithelia is urea. Our previous structural analyses show that TlpB binds urea with high affinity. Here we demonstrate that this tight binding controls highly sensitive responses, allowing detection of urea concentrations as low as 50 nanomolar. Attraction to urea requires that H. pylori urease simultaneously destroys the signal. We propose that H. pylori has evolved a sensitive urea chemodetection and destruction system that allows the bacterium to dynamically and locally modify the host environment to locate the epithelium. PMID:26269952

Capacitance-based damage detection sensing for aerospace structural composites

NASA Astrophysics Data System (ADS)

Bahrami, P.; Yamamoto, N.; Chen, Y.; Manohara, H.

2014-04-01

Damage detection technology needs improvement for aerospace engineering application because detection within complex composite structures is difficult yet critical to avoid catastrophic failure. Damage detection is challenging in aerospace structures because not all the damage detection technology can cover the various defect types (delamination, fiber fracture, matrix crack etc.), or conditions (visibility, crack length size, etc.). These defect states are expected to become even more complex with future introduction of novel composites including nano-/microparticle reinforcement. Currently, non-destructive evaluation (NDE) methods with X-ray, ultrasound, or eddy current have good resolutions (< 0.1 mm), but their detection capabilities is limited by defect locations and orientations and require massive inspection devices. System health monitoring (SHM) methods are often paired with NDE technologies to signal out sensed damage, but their data collection and analysis currently requires excessive wiring and complex signal analysis. Here, we present a capacitance sensor-based, structural defect detection technology with improved sensing capability. Thin dielectric polymer layer is integrated as part of the structure; the defect in the structure directly alters the sensing layer's capacitance, allowing full-coverage sensing capability independent of defect size, orientation or location. In this work, capacitance-based sensing capability was experimentally demonstrated with a 2D sensing layer consisting of a dielectric layer sandwiched by electrodes. These sensing layers were applied on substrate surfaces. Surface indentation damage (~1mm diameter) and its location were detected through measured capacitance changes: 1 to 250 % depending on the substrates. The damage detection sensors are light weight, and they can be conformably coated and can be part of the composite structure. Therefore it is suitable for aerospace structures such as cryogenic tanks and rocket fairings for example. The sensors can also be operating in space and harsh environment such as high temperature and vacuum.

Gravity investigation of the Manson impact structure, Iowa

NASA Technical Reports Server (NTRS)

Plescia, J. B.

1993-01-01

The Manson crater, of probable Cretaceous/Tertiary age, is located in northwestern Iowa (center at 42 deg. 34.44 min N; 94 deg. 33.60 min W). A seismic reflection profile along an east west line across the crater and drill hole data indicate a crater about 35 km in diameter having the classic form for an impact crater, an uplifted central peak composed of uplifted Proterozoic crystalline bedrock, surrounded by a 'moat' filled with impact produced breccia and a ring graben zone composed of tilted fault blocks of the Proterozoic and Paleozoic country rocks. The structure has been significantly eroded. This geologic structure would be expected to produce a significant gravity signature and study of that signature would shed additional light on the details of the crater structure. A gravity study was undertaken to better resolve the crustal structure. The regional Bouguer gravity field is characterized by a southeastward decreasing field. To first order, the Bouguer gravity field can be understood in the context of the geology of the Precambrian basement. The high gravity at the southeast corner is associated with the mid-continent gravity high; the adjacent low to the northwest results from a basin containing low-density clastic sediments shed from the basement high. Modeling of a simple basin and adjacent high predicts much of the observed Bouguer gravity signature. A gravity signature due to structure associated with the Manson impact is not apparent in the Bouguer data. To resolve the gravity signature of the impact, a series of polynomial surfaces were fit to the Bouguer gravity field to isolate the small wavelength residual anomalies. The residual gravity obtained after subtracting a 5th- or 6th-order polynomial seems to remove most of the regional effects and isolate local anomalies. The pattern resolved in the residual gravity is one of a gravity high surrounded by gravity lows and in turn surrounded by isolated gravity highs. The central portion of the crater is characterized by two positive anomalies having amplitudes of about plus 4 mGal separated by a gentle saddle located approximately at the crater center.

Robust QRS detection for HRV estimation from compressively sensed ECG measurements for remote health-monitoring systems.

PubMed

Pant, Jeevan K; Krishnan, Sridhar

2018-03-15

To present a new compressive sensing (CS)-based method for the acquisition of ECG signals and for robust estimation of heart-rate variability (HRV) parameters from compressively sensed measurements with high compression ratio. CS is used in the biosensor to compress the ECG signal. Estimation of the locations of QRS segments is carried out by applying two algorithms on the compressed measurements. The first algorithm reconstructs the ECG signal by enforcing a block-sparse structure on the first-order difference of the signal, so the transient QRS segments are significantly emphasized on the first-order difference of the signal. Multiple block-divisions of the signals are carried out with various block lengths, and multiple reconstructed signals are combined to enhance the robustness of the localization of the QRS segments. The second algorithm removes errors in the locations of QRS segments by applying low-pass filtering and morphological operations. The proposed CS-based method is found to be effective for the reconstruction of ECG signals by enforcing transient QRS structures on the first-order difference of the signal. It is demonstrated to be robust not only to high compression ratio but also to various artefacts present in ECG signals acquired by using on-body wireless sensors. HRV parameters computed by using the QRS locations estimated from the signals reconstructed with a compression ratio as high as 90% are comparable with that computed by using QRS locations estimated by using the Pan-Tompkins algorithm. The proposed method is useful for the realization of long-term HRV monitoring systems by using CS-based low-power wireless on-body biosensors.

Conformational Dissection of a Viral Intrinsically Disordered Domain Involved in Cellular Transformation

PubMed Central

Perrone, Sebastián; Salvay, Andres G.; Chemes, Lucía B.; de Prat-Gay, Gonzalo

2013-01-01

Intrinsic disorder is abundant in viral genomes and provides conformational plasticity to its protein products. In order to gain insight into its structure-function relationships, we carried out a comprehensive analysis of structural propensities within the intrinsically disordered N-terminal domain from the human papillomavirus type-16 E7 oncoprotein (E7N). Two E7N segments located within the conserved CR1 and CR2 regions present transient α-helix structure. The helix in the CR1 region spans residues L8 to L13 and overlaps with the E2F mimic linear motif. The second helix, located within the highly acidic CR2 region, presents a pH-dependent structural transition. At neutral pH the helix spans residues P17 to N29, which include the retinoblastoma tumor suppressor LxCxE binding motif (residues 21–29), while the acidic CKII-PEST region spanning residues E33 to I38 populates polyproline type II (PII) structure. At pH 5.0, the CR2 helix propagates up to residue I38 at the expense of loss of PII due to charge neutralization of acidic residues. Using truncated forms of HPV-16 E7, we confirmed that pH-induced changes in α-helix content are governed by the intrinsically disordered E7N domain. Interestingly, while at both pH the region encompassing the LxCxE motif adopts α-helical structure, the isolated 21–29 fragment including this stretch is unable to populate an α-helix even at high TFE concentrations. Thus, the E7N domain can populate dynamic but discrete structural ensembles by sampling α-helix-coil-PII-ß-sheet structures. This high plasticity may modulate the exposure of linear binding motifs responsible for its multi-target binding properties, leading to interference with key cell signaling pathways and eventually to cellular transformation by the virus. PMID:24086265

Use of high-resolution satellite images for characterization of geothermal reservoirs in the Tarapaca Region, Chile

NASA Astrophysics Data System (ADS)

Arellano-Baeza, A. A.; Montenegro A., C.

2010-12-01

The use of renewable and clean sources of energy is becoming crucial for sustainable development of all countries, including Chile. Chilean Government plays special attention to the exploration and exploitation of geothermal energy, total electrical power capacity of which could reach 16.000 MW. In Chile the main geothermal fields are located in the Central Andean Volcanic Chain in the North, between the Central valley and the border with Argentina in the center, and in the fault system Liquiñe-Ofqui in the South of the country. High resolution images from the Lansat satellite have been used to characterize the geothermal field in the region of the Puchuldiza geysers, Colchane, Region of Tarapaca, North of Chile, located at the altitude of 4000 m. Structure of lineaments associated to the geothermal field have been extracted from the images using the lineament detection technique developed by authors. These structures have been compared with the distribution of main geological structures obtained in the field. It was found that the lineament analysis is a power tool for the detection of faults and joint zones associated to the geothermal fields.

Diverse high-torque bacterial flagellar motors assemble wider stator rings using a conserved protein scaffold

PubMed Central

Ribardo, Deborah A.; Brennan, Caitlin A.; Ruby, Edward G.; Jensen, Grant J.; Hendrixson, David R.

2016-01-01

Although it is known that diverse bacterial flagellar motors produce different torques, the mechanism underlying torque variation is unknown. To understand this difference better, we combined genetic analyses with electron cryo-tomography subtomogram averaging to determine in situ structures of flagellar motors that produce different torques, from Campylobacter and Vibrio species. For the first time, to our knowledge, our results unambiguously locate the torque-generating stator complexes and show that diverse high-torque motors use variants of an ancestrally related family of structures to scaffold incorporation of additional stator complexes at wider radii from the axial driveshaft than in the model enteric motor. We identify the protein components of these additional scaffold structures and elucidate their sequential assembly, demonstrating that they are required for stator-complex incorporation. These proteins are widespread, suggesting that different bacteria have tailored torques to specific environments by scaffolding alternative stator placement and number. Our results quantitatively account for different motor torques, complete the assignment of the locations of the major flagellar components, and provide crucial constraints for understanding mechanisms of torque generation and the evolution of multiprotein complexes. PMID:26976588

Ground vibration tests of a high fidelity truss for verification of on orbit damage location techniques

NASA Technical Reports Server (NTRS)

Kashangaki, Thomas A. L.

1992-01-01

This paper describes a series of modal tests that were performed on a cantilevered truss structure. The goal of the tests was to assemble a large database of high quality modal test data for use in verification of proposed methods for on orbit model verification and damage detection in flexible truss structures. A description of the hardware is provided along with details of the experimental setup and procedures for 16 damage cases. Results from selected cases are presented and discussed. Differences between ground vibration testing and on orbit modal testing are also described.

Chapter in book "Many Body Structure of Strongly Interacting Systems, Refereed and Selected Contributions from the Symposium '20 Years of Physics at the Mainz Microtron MAMI,'" Part I, Editors: Arenhövel, H.; Backe, H.; Drechsel, D.; Friedrich, J.; Kaiser, K.-H.; Walcher, Th., p.7-17 (contribution entitled Physics at the Thomas Jefferson National Accelerator Facility)

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

Lawrence Cardman

2006-09-01

The Continuous Electron Accelerator Facility, CEBAF, located at the Thomas Jefferson National Accelerator Facility, is devoted to the investigation of the electromagnetic structure of mesons, nucleons, and nuclei using high energy, high duty-cycle electron and photon beams. Selected experimental results of particular interest to the MAMI community are presented.

Structural features based genome-wide characterization and prediction of nucleosome organization

PubMed Central

2012-01-01

Background Nucleosome distribution along chromatin dictates genomic DNA accessibility and thus profoundly influences gene expression. However, the underlying mechanism of nucleosome formation remains elusive. Here, taking a structural perspective, we systematically explored nucleosome formation potential of genomic sequences and the effect on chromatin organization and gene expression in S. cerevisiae. Results We analyzed twelve structural features related to flexibility, curvature and energy of DNA sequences. The results showed that some structural features such as DNA denaturation, DNA-bending stiffness, Stacking energy, Z-DNA, Propeller twist and free energy, were highly correlated with in vitro and in vivo nucleosome occupancy. Specifically, they can be classified into two classes, one positively and the other negatively correlated with nucleosome occupancy. These two kinds of structural features facilitated nucleosome binding in centromere regions and repressed nucleosome formation in the promoter regions of protein-coding genes to mediate transcriptional regulation. Based on these analyses, we integrated all twelve structural features in a model to predict more accurately nucleosome occupancy in vivo than the existing methods that mainly depend on sequence compositional features. Furthermore, we developed a novel approach, named DLaNe, that located nucleosomes by detecting peaks of structural profiles, and built a meta predictor to integrate information from different structural features. As a comparison, we also constructed a hidden Markov model (HMM) to locate nucleosomes based on the profiles of these structural features. The result showed that the meta DLaNe and HMM-based method performed better than the existing methods, demonstrating the power of these structural features in predicting nucleosome positions. Conclusions Our analysis revealed that DNA structures significantly contribute to nucleosome organization and influence chromatin structure and gene expression regulation. The results indicated that our proposed methods are effective in predicting nucleosome occupancy and positions and that these structural features are highly predictive of nucleosome organization. The implementation of our DLaNe method based on structural features is available online. PMID:22449207

Identification of minute damage in composite bridge structures equipped with fiber optic sensors using the location of neutral axis and finite element analysis

NASA Astrophysics Data System (ADS)

Li, Xi; Glisic, Branko

2016-04-01

By definition, the neutral axis of a loaded composite beam structure is the curve along which the section experiences zero bending strain. When no axial loading is present, the location of the neutral axis passes through the centroid of stiffness of the beam cross-section. In the presence of damage, the centroid of stiffness, as well as the neutral axis, shift from the healthy position. The concept of neutral axis can be widely applied to all beam-like structures. According to literature, a change in location of the neutral axis can be associated with damage in the corresponding cross-section. In this paper, the movement of neutral axis near locations of minute damage in a composite bridge structure was studied using finite element analysis and experimental results. The finite element model was developed based on a physical scale model of a composite simply-supported structure with controlled minute damage in the reinforced concrete deck. The structure was equipped with long-gauge fiber optic strain and temperature sensors at a healthy reference location as well as two locations of damage. A total of 12 strain sensors were installed during construction and used to monitor the structure during various loading events. This paper aims to explain previous experimental results which showed that the observed positions of neutral axis near damage locations were higher than the predicted healthy locations in some loading events. Analysis has shown that finite element analysis has potential to simulate and explain the physical behavior of the test structure.

Blast Load Simulator Experiments for Computational Model Validation: Report 1

DTIC Science & Technology

2016-08-01

involving the inclusion of non-responding box-type structures in a BLS simulated blast environment. The BLS is a highly tunable com- pressed-gas-driven...Blast Load Simulator (BLS) to evaluate its suitability for a future effort involving the inclusion of non-responding box-type structures located in...Recommendations Preliminary testing indicated that inclusion of the grill and diaphragm striker resulted in a decrease in peak pressure of about 12

Application of guided acoustic waves to delamination detection

NASA Technical Reports Server (NTRS)

Sun, Keun J.

1992-01-01

Guided plate waves are able to interact with structural flaws such as delaminations and cracks due to their propagation properties highly sensitive to the thickness change in materials. A technique which employs an acoustic damper to probe the results of this interaction and then to locate flaws in a relatively short period of time is developed. With its technical advantages, this technique shows its potential application to large area structural integrity assessment.

Low temperature superconductor and aligned high temperature superconductor magnetic dipole system and method for producing high magnetic fields

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

Gupta, Ramesh; Scanlan, Ronald; Ghosh, Arup K.

A dipole-magnet system and method for producing high-magnetic-fields, including an open-region located in a radially-central-region to allow particle-beam transport and other uses, low-temperature-superconducting-coils comprised of low-temperature-superconducting-wire located in radially-outward-regions to generate high magnetic-fields, high-temperature-superconducting-coils comprised of high-temperature-superconducting-tape located in radially-inward-regions to generate even higher magnetic-fields and to reduce erroneous fields, support-structures to support the coils against large Lorentz-forces, a liquid-helium-system to cool the coils, and electrical-contacts to allow electric-current into and out of the coils. The high-temperature-superconducting-tape may be comprised of bismuth-strontium-calcium-copper-oxide or rare-earth-metal, barium-copper-oxide (ReBCO) where the rare-earth-metal may be yttrium, samarium, neodymium, or gadolinium. Advantageously, alignment of themore » large-dimension of the rectangular-cross-section or curved-cross-section of the high-temperature-superconducting-tape with the high-magnetic-field minimizes unwanted erroneous magnetic fields. Alignment may be accomplished by proper positioning, tilting the high-temperature-superconducting-coils, forming the high-temperature-superconducting-coils into a curved-cross-section, placing nonconducting wedge-shaped-material between windings, placing nonconducting curved-and-wedge-shaped-material between windings, or by a combination of these techniques.« less

Broadband integrated polarization rotator using three-layer metallic grating structures

DOE PAGES

Fan, Ren -Hao; Liu, Dong; Peng, Ru -Wen; ...

2018-01-05

In this work, we demonstrate broadband integrated polarization rotator (IPR) with a series of three-layer rotating metallic grating structures. This transmissive optical IPR can conveniently rotate the polarization of linearly polarized light to any desired directions at different spatial locations with high conversion efficiency, which is nearly constant for different rotation angles. The linear polarization rotation originates from multi-wave interference in the three-layer grating structure. As a result, we anticipate that this type of IPR will find wide applications in analytical chemistry, biology, communication technology, imaging, etc.

Broadband integrated polarization rotator using three-layer metallic grating structures

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

Fan, Ren -Hao; Liu, Dong; Peng, Ru -Wen

In this work, we demonstrate broadband integrated polarization rotator (IPR) with a series of three-layer rotating metallic grating structures. This transmissive optical IPR can conveniently rotate the polarization of linearly polarized light to any desired directions at different spatial locations with high conversion efficiency, which is nearly constant for different rotation angles. The linear polarization rotation originates from multi-wave interference in the three-layer grating structure. As a result, we anticipate that this type of IPR will find wide applications in analytical chemistry, biology, communication technology, imaging, etc.

Rainfall characteristics and thresholds for periglacial debris flows in the Parlung Zangbo Basin, southeast Tibetan Plateau

NASA Astrophysics Data System (ADS)

Deng, Mingfeng; Chen, Ningsheng; Ding, Haitao

2018-02-01

The Parlung Zangbo Basin in the southeastern Tibet Plateau is affected by the summer monsoon from the Indian Ocean, which produces large rainfall gradients in the basin. Rainfall data during 2012-2015 from five new meteorological stations are used to analyse the rainfall characteristics. The daily rainfall, rainfall duration, mean rainfall intensity, and peak rainfall intensity are consistent, but sometimes contrasting. For example, these values decrease with increasing altitude, and the gradient is large downstream and small upstream, respectively. Moreover, the rainfall intensity peaks between 01:00 and 06:00 and increases during the afternoon. Based on the analysis of 14 debris flow cases in the basin, differences in the rainfall threshold differ depending on the location as sediment varieties. The sediment in the middle portions of the basin is wet and well structured; thus, long-duration, high-intensity rainfall is required to generate debris flows. Ravels in the upstream area are arid and not well structured, and short-duration rainfall is required to trigger debris flows. Between the above two locations, either long-duration, low-intensity rainfall or short-duration, high-intensity rainfall could provoke debris flows. Clearly, differences in rainfall characteristics and rainfall thresholds that are associated with the location must be considered in debris flow monitoring and warnings.

Literacy Gets "a" Makeover: Engaged Learning Boosts Student Achievement at Michigan High School

ERIC Educational Resources Information Center

Wood, Richard E.; Burz, Helen L.

2013-01-01

E.A. Johnson High School is located in Mt. Morris, Michigan, near Flint, where the city has felt deeply the impact of the area's economic decline. 72% of the student population qualify for free and reduced lunch. The staff was willing to make the changes necessary for success, but needed more than a book study. Many of the structures for…

High Tech High School Interns Develop a Mid-Ocean Ridge Database for Research and Education

NASA Astrophysics Data System (ADS)

Staudigel, D.; Delaney, R.; Staudigel, H.; Koppers, A. A.; Miller, S. P.

2004-12-01

Mid-ocean ridges (MOR) represent one of the most important geographical and geological features on planet Earth. MORs are the locations where plates spread apart, they are the locations of the majority of the Earths' volcanoes that harbor some of the most extreme life forms. These concepts attract much research, but mid-ocean ridges are still effectively underrepresented in the Earth science class rooms. As two High Tech High School students, we began an internship at Scripps to develop a database for mid-ocean ridges as a resource for science and education. This Ridge Catalog will be accessible via http://earthref.org/databases/RC/ and applies a similar structure, design and data archival principle as the Seamount Catalog under EarthRef.org. Major research goals of this project include the development of (1) an archival structure for multibeam and sidescan data, standard bathymetric maps (including ODP-DSDP drill site and dredge locations) or any other arbitrary digital objects relating to MORs, and (2) to compile a global data set for some of the most defining characteristics of every ridge segment including ridge segment length, depth and azimuth and half spreading rates. One of the challenges included the need of making MOR data useful to the scientist as well as the teacher in the class room. Since the basic structure follows the design of the Seamount Catalog closely, we could move our attention to the basic data population of the database. We have pulled together multibeam data for the MOR segments from various public archives (SIOExplorer, SIO-GDC, NGDC, Lamont), and pre-processed it for public use. In particular, we have created individual bathymetric maps for each ridge segment, while merging the multibeam data with global satellite bathymetry data from Smith & Sandwell (1997). The global scale of this database will give it the ability to be used for any number of applications, from cruise planning to data

Development a heuristic method to locate and allocate the medical centers to minimize the earthquake relief operation time.

PubMed

Aghamohammadi, Hossein; Saadi Mesgari, Mohammad; Molaei, Damoon; Aghamohammadi, Hasan

2013-01-01

Location-allocation is a combinatorial optimization problem, and is defined as Non deterministic Polynomial Hard (NP) hard optimization. Therefore, solution of such a problem should be shifted from exact to heuristic or Meta heuristic due to the complexity of the problem. Locating medical centers and allocating injuries of an earthquake to them has high importance in earthquake disaster management so that developing a proper method will reduce the time of relief operation and will consequently decrease the number of fatalities. This paper presents the development of a heuristic method based on two nested genetic algorithms to optimize this location allocation problem by using the abilities of Geographic Information System (GIS). In the proposed method, outer genetic algorithm is applied to the location part of the problem and inner genetic algorithm is used to optimize the resource allocation. The final outcome of implemented method includes the spatial location of new required medical centers. The method also calculates that how many of the injuries at each demanding point should be taken to any of the existing and new medical centers as well. The results of proposed method showed high performance of designed structure to solve a capacitated location-allocation problem that may arise in a disaster situation when injured people has to be taken to medical centers in a reasonable time.

Numerical models for continental break-up: Implications for the South Atlantic

NASA Astrophysics Data System (ADS)

Beniest, A.; Koptev, A.; Burov, E.

2017-03-01

We propose a mechanism that explains in one unified framework the presence of continental break-up features such as failed rift arms and high-velocity and high-density bodies that occur along the South Atlantic rifted continental margins. We used 2D and 3D numerical models to investigate the impact of thermo-rheological structure of the continental lithosphere and initial plume position on continental rifting and break-up processes. 2D experiments show that break-up can be 1) "central", mantle plume-induced and directly located above the centre of the mantle anomaly, 2) "shifted", mantle plume-induced and 50 to 200 km shifted from the initial plume location or 3) "distant", self-induced due to convection and/or slab-subduction/delamination and 300 to 800 km off-set from the original plume location. With a 3D, perfectly symmetrical and laterally homogeneous setup, the location of continental break-up can be shifted hundreds of kilometres from the initial position of the mantle anomaly. We demonstrate that in case of shifted or distant continental break-up with respect to the original plume location, multiple features can be explained. Its deep-seated source can remain below the continent at one or both sides of the newly-formed ocean. This mantle material, glued underneath the margins at lower crustal levels, resembles the geometry and location of high velocity/high density bodies observed along the South Atlantic conjugate margins. Impingement of vertically up-welled plume material on the base of the lithosphere results in pre-break-up topography variations that are located just above this initial anomaly impingement. This can be interpreted as aborted rift features that are also observed along the rifted margins. When extension continues after continental break-up, high strain rates can relocalize. This relocation has been so far attributed to rift jumps. Most importantly, this study shows that there is not one, single rift mode for plume-induced crustal break-up.

Combined electromechanical impedance and fiber optic diagnosis of aerospace structures

NASA Astrophysics Data System (ADS)

Schlavin, Jon; Zagrai, Andrei; Clemens, Rebecca; Black, Richard J.; Costa, Joey; Moslehi, Behzad; Patel, Ronak; Sotoudeh, Vahid; Faridian, Fereydoun

2014-03-01

Electromechanical impedance is a popular diagnostic method for assessing structural conditions at high frequencies. It has been utilized, and shown utility, in aeronautic, space, naval, civil, mechanical, and other types of structures. By contrast, fiber optic sensing initially found its niche in static strain measurement and low frequency structural dynamic testing. Any low frequency limitations of the fiber optic sensing, however, are mainly governed by its hardware elements. As hardware improves, so does the bandwidth (frequency range * number of sensors) provided by the appropriate enabling fiber optic sensor interrogation system. In this contribution we demonstrate simultaneous high frequency measurements using fiber optic and electromechanical impedance structural health monitoring technologies. A laboratory specimen imitating an aircraft wing structure, incorporating surfaces with adjustable boundary conditions, was instrumented with piezoelectric and fiber optic sensors. Experiments were conducted at different structural boundary conditions associated with deterioration of structural health. High frequency dynamic responses were collected at multiple locations on a laboratory wing specimen and conclusions were drawn about correspondence between structural damage and dynamic signatures as well as correlation between electromechanical impedance and fiber optic sensors spectra. Theoretical investigation of the effect of boundary conditions on electromechanical impedance spectra is presented and connection to low frequency structural dynamics is suggested. It is envisioned that acquisition of high frequency structural dynamic responses with multiple fiber optic sensors may open new diagnostic capabilities for fiber optic sensing technologies.

Integrated Risk Research. Case of Study: Motozintla, Chiapas, Mexico

NASA Astrophysics Data System (ADS)

Novelo-Casanova, D. A.; Jaimes, M.

2015-12-01

This integrated risk research include the analysis of all components of individual constituents of risk such hazard identification, hazard exposure, and vulnerability. We determined risk to natural hazards in the community of Motozintla located in southern Mexico in the state of Chiapas (15.37ºN, 92.25ºW. Due to its geographical and geological location, this community is continuously exposed mainly to earthquakes, landslides and floods. We developed integrated studies and analysis of seismic zonation, landslides and flood susceptibility using standard methodologies. Vulnerability was quantified from data collected from local families interviews considering five social variables: characteristics of housing construction, availability of basic public services, family economic conditions, existing community plans for disaster preparedness, and risk perception. Local families surveyed were randomly selected considering a sample statistically significant. Our results were spatially represented using a Geographical Information System (GIS). Structural vulnerability curves were generated for typical housing constructions. Our integrated risk analysis demonstrates that the community of Motozintla has a high level of structural and socio-economical risk to floods and earthquakes. More than half of the population does not know any existing Civil Protection Plan and perceive that they are in high risk to landslides and floods. Although the community is located in a high seismic risk zone, most of the local people believe that cannot be impacted by a large earthquake. These natural and social conditions indicate that the community of Motozintla has a very high level of risk to natural hazards. This research will support local decision makers in developing an integrated comprehensive natural hazards mitigation and prevention program.

Tectonic History and Deep Structure of the Demerara Plateau from Combined Wide-Angle and Reflection Seismic Data and Plate Kinematic Reconstructions

NASA Astrophysics Data System (ADS)

Klingelhoefer, F.; Museur, T.; Roest, W. R.; Graindorge, D.; Chauvet, F.; Loncke, L.; Basile, C.; Poetisi, E.; Deverchere, J.; Lebrun, J. F.; Perrot, J.; Heuret, A.

2017-12-01

Many transform margins have associated intermediate depth marginal plateaus, which are commonly located between two oceanic basins. The Demerara plateau is located offshore Surinam and French Guiana. Plate kinematic reconstructions show that the plateau is located between the central and equatorial Atlantic in a position conjugate to the Guinean Plateau. In the fall of 2016, the MARGATS cruise acquired geophysical data along the 400 km wide Demerara plateau. The main objective of the cruise was to image the deep structure of the Demerara plateau and to study its tectonic history. A set of 4 combined wide-angle and reflection seismic profiles was acquired along the plateau, using 80 ocean-bottom seismometers, a 3 km long seismic streamer and a 8000 cu inch tuned airgun array. Forward modelling of the wide-angle seismic data on a profile, located in the eastern part of the plateau and oriented in a NE-SW direction, images the crustal structure of the plateau, the transition zone and the neighbouring crust of oceanic origin, up to a depth of 40 km. The plateau itself is characterised by a crust of 30 km thickness, subdivided into three distinct layers. However, the velocities and velocity gradients do not fit typical continental crust, with a lower crustal layer showing untypically high velocities and an upper layer having a steep velocity gradient. From this model we propose that the lowermost layer is probably formed from volcanic underplated material and that the upper crustal layer likely consists of the corresponding extrusive volcanic material, forming thick seaward-dipping reflector sequences on the plateau. A basement high is imaged at the foot of the slope and forms the ocean-continent transition zone. Further oceanward, a 5-6 km thick crust is imaged with velocities and velocity gradients corresponding to a thin oceanic crust. A compilation of magnetic data from the MARGATS and 3 previous cruises shows a high amplitude magnetic anomaly along the northern edge of the plateau thereby strengthening the hypothesis of an volcanic origin of at least part of the structure. We propose, that the plateau was formed by large-scale volcanism, possibly intruding into a thinner existing continental crust.

Design, installation, and condition assessment of a concrete bridge deck constructed with ASTM A1035 CS no. 4 bars.

DOT National Transportation Integrated Search

2017-06-01

Recently developed corrosion-resistant reinforcing structural design guidelines were used to design, construct, and : assess a reinforced concrete bridge deck with high-strength ASTM A1035 CS steel bars. The bridge replacement is located : along the ...

Detection, location, and quantification of structural damage by neural-net-processed moiré profilometry

NASA Astrophysics Data System (ADS)

Grossman, Barry G.; Gonzalez, Frank S.; Blatt, Joel H.; Hooker, Jeffery A.

1992-03-01

The development of efficient high speed techniques to recognize, locate, and quantify damage is vitally important for successful automated inspection systems such as ones used for the inspection of undersea pipelines. Two critical problems must be solved to achieve these goals: the reduction of nonuseful information present in the video image and automatic recognition and quantification of extent and location of damage. Artificial neural network processed moire profilometry appears to be a promising technique to accomplish this. Real time video moire techniques have been developed which clearly distinguish damaged and undamaged areas on structures, thus reducing the amount of extraneous information input into an inspection system. Artificial neural networks have demonstrated advantages for image processing, since they can learn the desired response to a given input and are inherently fast when implemented in hardware due to their parallel computing architecture. Video moire images of pipes with dents of different depths were used to train a neural network, with the desired output being the location and severity of the damage. The system was then successfully tested with a second series of moire images. The techniques employed and the results obtained are discussed.

Motor abundance and control structure in the golf swing.

PubMed

Morrison, A; McGrath, D; Wallace, E S

2016-04-01

Variability and control structure are under-represented areas of golf swing research. This study investigated the use of the abundant degrees of freedom in the golf swing of high and intermediate skilled golfers using uncontrolled manifold (UCM) analysis. The variance parallel to (VUCM) and orthogonal to (VOrth) the UCM with respect to the orientation and location of the clubhead were calculated. The higher skilled golfers had proportionally higher values of VUCM than lower skilled players for all measured outcome variables. Motor synergy was found in the control of the orientation of the clubhead and the combined outcome variables but not for clubhead location. Clubhead location variance zeroed-in on impact as has been previously shown, whereas clubhead orientation variance increased near impact. Both skill levels increased their control over the clubhead location leading up to impact, with more control exerted over the clubhead orientation in the early downswing. The results suggest that to achieve higher skill levels in golf may not lie simply in optimal technique, but may lie more in developing control over the abundant degrees of freedom in the body. Copyright © 2016 Elsevier B.V. All rights reserved.

Dynamics and control of high precision magnetically levitated vibration isolation systems

NASA Technical Reports Server (NTRS)

Youcef-Toumi, K.; Yeh, T-J.

1992-01-01

Vibration control of flexible structures has received a great deal of interest in recent years. Several authors have investigated this topic in the areas of robot manipulators, space structures, and flexible rotors. Key issues associated with the dynamics and control of vibration isolation systems are addressed. Among other important issues to consider in the control of such systems, the location and number of actuators and sensors are essential to effectively control and suppress vibration. We first address the selection of proper actuator and sensor locations leading to a controllable and observable system. The Rayleigh-Ritz modal analysis method is used to develop a lumped-parameter model of a flexible vibration isolation table top. This model is then used to investigate the system's controllability and observability including the coupling effects introduced by the magnetic bearing. This analysis results in necessary and sufficient conditions for proper selection of actuator and sensor locations. These locations are also important for both controller system's complexity and stability of point of views. A favorable pole-zero plot of the open loop transfer functions is presented. Necessary and sufficient conditions for reducing the controller complexity are derived. The results are illustrated by examples using approximate mode shape functions.

Cross Flow Parameter Calculation for Aerodynamic Analysis

NASA Technical Reports Server (NTRS)

Norman, David, Jr. (Inventor)

2014-01-01

A system and method for determining a cross flow angle for a feature on a structure. A processor unit receives location information identifying a location of the feature on the structure, determines an angle of the feature, identifies flow information for the location, determines a flow angle using the flow information, and determines the cross flow angle for the feature using the flow angle and the angle of the feature. The flow information describes a flow of fluid across the structure. The flow angle comprises an angle of the flow of fluid across the structure for the location of the feature.

Dynamic tests on the NASA Langley CSI evolutionary model

NASA Technical Reports Server (NTRS)

Troidl, H.; Elliott, K. B.

1993-01-01

A modal analysis study, representing one of the anticipated 'Cooperative Spacecraft Structural Dynamics Experiments on the NASA Langley CSI Evolutionary Model', was carried out as a sub-task under the NASA/DLR collaboration in dynamics and control of large space systems. The CSI evolutionary testbed (CEM) is designed for the development of Controls-Structures Interaction (CSI) technology to improve space science platform pointing. For orbiting space structures like large flexible trusses, new identification challenges arise due to their specific dynamic characteristics (low frequencies and high modal density) on the one hand, and the limited possibilities of exciting such structures and measuring their responses on orbit on the other. The main objective was to investigate the modal identification potential of several different types of forcing functions that could possibly be realized with on-board excitation equipment using a minimum number of exciter locations as well as response locations. These locations were defined in an analytical test prediction process used to study the implications of measuring and analyzing the responses thus produced. It turned out that broadband excitation is needed for a general modal survey, but if only certain modes are of particular interest, combinations of exponentially decaying sine functions provide favorable excitation conditions as they allow to concentrate the available energy on the modes being of special interest. From a practical point-of-view structural nonlinearities as well as noisy measurements make the analysis more difficult, especially in the low frequency range and when the modes are closely spaced.

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

Cornaggia, F.; Congo, S.A.; Agostino, M.

Kitina field is located in Marine VII permit, offshore Congo. The field was discovered in 1991 by a joint venture composed of Agip Recherches Congo (operator), Hydrocongo and Chevron International Limited. The field is a structural four-way dip closure trap shaped as turtle-back. Halokinetic movements are responsible for the structuring. The seismic imaging of the reservoir is affected by strong lateral velocity variations caused by different sedimentation across the paleo-shelf edge in the post-Albian sequence. One pass 3D poststack depth migration, performed with a velocity field obtained by means of geostatistical integration of 2D seismic and wellbore velocities, achieved amore » good compromise between high dip reflector imaging and depths at well location. Three main reservoirs of lower Albian age exist between -2100 and -3100m. They are separated by tight mudstones which act as intraformational seal. Seismic trace inversion improved the resolution of petrophysical variations in some of the field reservoirs, which have the following characteristics (from top to bottom): reservoir 2A is composed of bioclastic and oolitic packstone-grainstone laid down during regional regressive phase in insulated offshore bars on the crest of structural high. Early diagenetic phenomena lead to the development of world class permeability framework. Reservoir 1A-1B are composed of sandstone bodies which were deposited as shoreface to offshore bars during short-term regressive pulse. The 1A-1B reservoir, are embedded in mudstones deposited during long lasting phases of relative high stand in relatively deep offshore setting characterised by high, halokinetic driven subsidence.« less

Measurements of unsteady pressure and structural response for an elastic supercritical wing

NASA Technical Reports Server (NTRS)

Eckstrom, Clinton V.; Seidel, David A.; Sandford, Maynard C.

1994-01-01

Results are presented which define unsteady flow conditions associated with the high-dynamic structural response of a high-aspect-ratio, elastic, supercritical wing at transonic speeds. The wing was tested in the Langley Transonic Dynamics Tunnel with a heavy gas test medium. The supercritical wing, designed for a cruise lift coefficient of 0.53 at a Mach number of 0.80, experienced the high-dynamic structural response from Mach 0.90 to 0.94 with the maximum response occurring at about Mach 0.92. At the maximum response conditions of the wing, the forcing function appears to be the oscillatory chordwise movement of strong shocks located on the upper and lower surfaces of the wing in conjunction with the flow separation on the lower surface of the wing in the trailing-edge cove region.

Accurate high-throughput structure mapping and prediction with transition metal ion FRET

PubMed Central

Yu, Xiaozhen; Wu, Xiongwu; Bermejo, Guillermo A.; Brooks, Bernard R.; Taraska, Justin W.

2013-01-01

Mapping the landscape of a protein’s conformational space is essential to understanding its functions and regulation. The limitations of many structural methods have made this process challenging for most proteins. Here, we report that transition metal ion FRET (tmFRET) can be used in a rapid, highly parallel screen, to determine distances from multiple locations within a protein at extremely low concentrations. The distances generated through this screen for the protein Maltose Binding Protein (MBP) match distances from the crystal structure to within a few angstroms. Furthermore, energy transfer accurately detects structural changes during ligand binding. Finally, fluorescence-derived distances can be used to guide molecular simulations to find low energy states. Our results open the door to rapid, accurate mapping and prediction of protein structures at low concentrations, in large complex systems, and in living cells. PMID:23273426

Flood Plain Lakes Along the Elbe River - a Forgotten Risk

NASA Astrophysics Data System (ADS)

Heise, Susanne

2014-05-01

Flood Plain Lakes Along the Elbe River - a Forgotten Risk Introduction: Along the German part of the Elbe River, more than 1000 "side structures" form potential sinks of contaminated sediment. They are mostly remains of previous river courses which have been cut off by natural causes or anthropogenic alterations of the river (oxbow lakes), or are floodplain lakes that were formed during high water conditions. These water bodies sometimes have a small opening towards the Elbe, or are hydrodynamically connected only in situations of high discharges. High discharges in the Elbe River, however, are mainly responsible for transporting historic contaminants along with suspended matter from former historic sources in the middle Elbe downstream. As these may settle when the current dies down at the end of a high discharge period, side structures have been under suspicion to have accumulated contaminated material over the last decades. Until this study was conducted, nothing was known about erodibility and contamination of sediment in these lakes even though they could have a large impact on the Elbe River itself: A preliminary investigation showed that the total surface of side structures in the Elbe floodplain adds up to about 50 km2. In case that deposited sediment is contaminated and only the upper 20 cm are prone to resuspension and transport during flooding, 10 Mio m3 of contaminated sediment could potentially be added to the contaminant load during a high water event. This study was carried out to evaluate the risk from these side structures for the environmental quality of the Elbe River. Methods: 15 side structures were investigated. Sediment cores were taken on 1 to 3 locations per water body in order to obtain the following information: • Depth of sediment layer • Erodibility of surface sediment, measured immediately after sampling - using the "Gust Microcosm", • Eroded mass at over-critical shear stress, measured in the lab by eroding a sediment core for one hour and collecting the suspended sediment matter. • Chemical contamination • Ecotoxicological effects Results and Discussion All side structures that were sampled exceeded the national quality guidelines for sediments which have been set by the International Commission for the Protection of the Elbe. In some cases very high concentrations were reached such as 1300 µg/kg dw for p,p-DDD, up to 61 mg/kg for Hg and 39 mg/kg for Cd. Erodibility varied a lot with critical shear stresses of less than 1 cm/s to more than 2 cm/s. Ecotoxicological data were also very different between side structures and sampling locations, but partly indicating very high inhibitions. Methanol extracts of sediments on all locations were screened using the luminescence bacteria test with Vibrio fischeri. Selected sediemt samples were tested applying the sediment contact test with Arthrobacter globiformes and the algae growth inhibition test with Pseudokirchneriella subcapitata. An integrated evaluation of all information led to a classification of 7 sites out of 15 to be of high risk, 7 to be of medium risk and only one site to be of low risk for the environmental quality of the Elbe River.

Statistical survey of day-side magnetospheric current flow using Cluster observations: magnetopause

NASA Astrophysics Data System (ADS)

Liebert, Evelyn; Nabert, Christian; Perschke, Christopher; Fornaçon, Karl-Heinz; Glassmeier, Karl-Heinz

2017-05-01

We present a statistical survey of current structures observed by the Cluster spacecraft at high-latitude day-side magnetopause encounters in the close vicinity of the polar cusps. Making use of the curlometer technique and the fluxgate magnetometer data, we calculate the 3-D current densities and investigate the magnetopause current direction, location, and magnitude during varying solar wind conditions. We find that the orientation of the day-side current structures is in accordance with existing magnetopause current models. Based on the ambient plasma properties, we distinguish five different transition regions at the magnetopause surface and observe distinctive current properties for each region. Additionally, we find that the location of currents varies with respect to the onset of the changes in the plasma environment during magnetopause crossings.

A 3-D velocity model for earthquake location from combined geological and geophysical data: a case study from the TABOO near fault observatory (Northern Apennines, Italy)

NASA Astrophysics Data System (ADS)

Latorre, Diana; Lupattelli, Andrea; Mirabella, Francesco; Trippetta, Fabio; Valoroso, Luisa; Lomax, Anthony; Di Stefano, Raffaele; Collettini, Cristiano; Chiaraluce, Lauro

2014-05-01

Accurate hypocenter location at the crustal scale strongly depends on our knowledge of the 3D velocity structure. The integration of geological and geophysical data, when available, should contribute to a reliable seismic velocity model in order to guarantee high quality earthquake locations as well as their consistency with the geological structure. Here we present a 3D, P- and S-wave velocity model of the Upper Tiber valley region (Northern Apennines) retrieved by combining an extremely robust dataset of surface and sub-surface geological data (seismic reflection profiles and boreholes), in situ and laboratory velocity measurements, and earthquake data. The study area is a portion of the Apennine belt undergoing active extension where a set of high-angle normal faults is detached on the Altotiberina low-angle normal fault (ATF). From 2010, this area hosts a scientific infrastructure (the Alto Tiberina Near Fault Observatory, TABOO; http://taboo.rm.ingv.it/), consisting of a dense array of multi-sensor stations, devoted to studying the earthquakes preparatory phase and the deformation processes along the ATF fault system. The proposed 3D velocity model is a layered model in which irregular shaped surfaces limit the boundaries between main lithological units. The model has been constructed by interpolating depth converted seismic horizons interpreted along 40 seismic reflection profiles (down to 4s two way travel times) that have been calibrated with 6 deep boreholes (down to 5 km depth) and constrained by detailed geological maps and structural surveys data. The layers of the model are characterized by similar rock types and seismic velocity properties. The P- and S-waves velocities for each layer have been derived from velocity measurements coming from both boreholes (sonic logs) and laboratory, where measurements have been performed on analogue natural samples increasing confining pressure in order to simulate crustal conditions. In order to test the 3D velocity model, we located a selected dataset of the 2010-2013 TABOO catalogue, which is composed of about 30,000 micro-earthquakes (see Valoroso et al., same session). Earthquake location was performed by applying the global-search earthquake location method NonLinLoc, which is able to manage strong velocity contrasts as that observed in the study area. The model volume is 65km x 55km x 20km and is parameterized by constant velocity, cubic cells of side 100 m. For comparison, we applied the same inversion code by using the best 1D model of the area obtained with earthquake data. The results show a significant quality improvement with the 3D model both in terms of location parameters and correlation between seismicity distribution and known geological structures.

Monitoring of corrosion damage using high-frequency guided ultrasonic waves

NASA Astrophysics Data System (ADS)

Chew, D.; Fromme, P.

2014-03-01

Due to adverse environmental conditions corrosion can develop during the life cycle of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Both pitting corrosion and generalized corrosion leading to wall thickness loss can cause the degradation of the integrity and load bearing capacity of the structure. Structural health monitoring of corrosion damage in difficult to access areas can in principle be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic transducers with single sided access to the structure, high frequency guided wave modes were generated that penetrate through the complete thickness of the structure. Wall thickness reduction was induced using accelerated corrosion in a salt water bath. The corrosion damage was monitored based on the effect on the wave propagation and interference of the different modes. The change in the wave interference was quantified based on an analysis in the frequency domain (Fourier transform) and was found to match well with theoretical predictions for the wall thickness loss. High frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

Monitoring of corrosion damage using high-frequency guided ultrasonic waves

NASA Astrophysics Data System (ADS)

Chew, D.; Fromme, P.

2015-03-01

Due to adverse environmental conditions corrosion can develop during the life cycle of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Both pitting corrosion and generalized corrosion leading to wall thickness loss can cause the degradation of the integrity and load bearing capacity of the structure. Structural health monitoring of corrosion damage in difficult to access areas can in principle be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic transducers with single sided access to the structure, high frequency guided wave modes were generated that penetrate through the complete thickness of the structure. Wall thickness reduction was induced using accelerated corrosion in a salt water bath. The corrosion damage was monitored based on the effect on the wave propagation and interference of the different modes. The change in the wave interference was quantified based on an analysis in the frequency domain (Fourier transform) and was found to match well with theoretical predictions for the wall thickness loss. High frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

The effect of residential choice on the travel distance and the implications for sustainable development

NASA Astrophysics Data System (ADS)

Eka Putra, Kaspan

2018-03-01

For Medan citizens, the choice of residence location depends on the ability to buy a house. House price is determined by the price of land where the housing is located. The more to the edge of the city the location of a house, then the price will be lower. So that the suburbs of Medan become the residential choice for the citizens of low-income. The residential choice will affect the distance of the journey to the workplace. This study analyzed the effect of residential choice on the travel distance and the implications for the implementation of sustainable development. The data used in this study is the primary data obtained through the survey held in Medan. The research approach is quantitative with the data analysis technique of Structural Equation Model (SEM). The results show that low-income citizens tend to choose the location of suburbs, while they work in the urban area. The location of the residence affects the daily travel distance is very high. The travel distance that is the very high effect the use of private vehicle mode. The use of private vehicles for long travel distance requires a huge energy. The use of very high fuel oils is a waste of energy and can increase air pollution. This is not in accordance with the concept of sustainable development.

Seismicity of the St. Lawrence paleorift faults overprinted by a meteorite impact crater: Implications for crustal strength based on new earthquake relocations in the Charlevoix Seismic Zone, Eastern Canada

NASA Astrophysics Data System (ADS)

Yu, H.; Harrington, R. M.; Liu, Y.; Lamontagne, M.; Pang, M.

2015-12-01

The Charlevoix Seismic Zone (CSZ), located along the St. Lawrence River (SLR) ~100 km downstream from Quebec City, is the most active seismic zone in eastern Canada with five historic earthquakes of M 6-7 and ~ 200 events/year reported by the Canadian National Seismograph Network. Cataloged earthquake epicenters outline two broad linear zones along the SLR with little shallow seismicity in between. Earthquakes form diffuse clusters between major dipping faults rather than concentrating on fault planes. Detailed fault geometry in the CSZ is uncertain and the effect on local seismicity of a meteorite impact structure that overprints the paleorift faults remains ambiguous. Here we relocate 1639 earthquakes occurring in the CSZ between 01/1988 - 10/2010 using the double-difference relocation method HypoDD and waveforms primarily from 7 local permanent stations. We use the layered SLR north shore velocity model from Lamontagne (1999), and travel time differences based on both catalog and cross-correlated P and S-phase picks. Of the 1639 relocated earthquakes, 1236 (75.4%) satisfied selection criteria of horizontal and vertical errors less than 2 km and 1 km respectively. Cross-sections of relocated seismicity show hypocenters along distinct active fault segments. Earthquakes located beneath the north shore of the SLR are likely correlated with the NW Gouffre fault, forming a ~10 km wide seismic zone parallel to the river, with dip angle changing to near vertical at the northern edge of the impact zone. In contrast, seismicity beneath the SLR forms a diffuse cloud within the impact structure, likely representing a highly fractured volume. It further implies that faults could be locally weak and subject to high pore-fluid pressures. Seismicity outside the impact structure defines linear structures aligning with the Charlevoix fault. Relocated events of M > 4 all locate outside the impact structure, indicating they nucleated on the NE-SW-oriented paleorift faults.

Different Histories, Different Destinies‒Impact of Evolutionary History and Population Genetic Structure on Extinction Risk of the Adriatic Spined Loaches (Genus Cobitis; Cypriniformes, Actinopterygii).

PubMed

Buj, Ivana; Ćaleta, Marko; Marčić, Zoran; Šanda, Radek; Vukić, Jasna; Mrakovčić, Milorad

2015-01-01

The region of Balkans is often considered as an ichthyologic "hot spot", with a great number of species and high portion of endemics living in fresh waters in a relatively small area. The Adriatic watershed in Croatia and Herzegovina is inhabited by six spined loach species (genus Cobitis) whose extinction risk estimations were based solely on their extent of occurrence (and/or area of occupancy) and its fragmentation, and conservation proposals do not consider diversity below species level. In this investigation we employed molecular genetic methods to describe present genetic structure of the Adriatic spined loaches and reveal their demographic history. The divergence of the Adriatic lineages inside the genus Cobitis started in Miocene and lasted until Pleistocene epoch. Geological events responsible for shaping recent diversity of spined loaches in the Adriatic basin are: the Dinarid Mountains upwelling, the evolution of Dinaric Lake system, local tectonic activity, river connections during glaciations and differences in sea level. Even though all the investigated species inhabit karstic rivers located in the same geographic area and that were subject of similar geological events, the results obtained reveal great differences in their genetic diversity and structure and point out the necessity of different conservation measures to ensure their future viability. High level of genetic polymorphism is characteristic for species located more to the south. Two species comprised of more than one population have completely different intraspecific structure; populations of C. illyrica are genetically distinct and represent separate evolutionary significant units, whereas intraspecific structure of C. narentana corresponds to metapopulational pattern. Without population genetic data, evolutionary significant units could be easily misidentified. Furthermore, the obtained results affirm that population genetic measurements are able to detect differences among closely located and related species and estimate extinction risk even more accurately than currently applied IUCN criteria.

The predicted secondary structures of class I fructose-bisphosphate aldolases.

PubMed Central

Sawyer, L; Fothergill-Gilmore, L A; Freemont, P S

1988-01-01

The results of several secondary-structure prediction programs were combined to produce an estimate of the regions of alpha-helix, beta-sheet and reverse turns for fructose-bisphosphate aldolases from human and rat muscle and liver, from Trypanosoma brucei and from Drosophila melanogaster. All the aldolase sequences gave essentially the same pattern of secondary-structure predictions despite having sequences up to 50% different. One exception to this pattern was an additional strongly predicted helix in the rat liver and Drosophila enzymes. Regions of relatively high sequence variation generally were predicted as reverse turns, and probably occur as surface loops. Most of the positions corresponding to exon boundaries are located between regions predicted to have secondary-structural elements consistent with a compact structure. The predominantly alternating alpha/beta structure predicted is consistent with the alpha/beta-barrel structure indicated by preliminary high-resolution X-ray diffraction studies on rabbit muscle aldolase [Sygusch, Beaudry & Allaire (1986) Biophys. J. 49, 287a]. Images Fig. 1. (cont.) Fig. 1. PMID:3128269

System for plotting subsoil structure and method therefor

NASA Technical Reports Server (NTRS)

Narasimhan, K. Y.; Nathan, R.; Parthasarathy, S. P. (Inventor)

1980-01-01

Data for use in producing a tomograph of subsoil structure between boreholes is derived by pacing spaced geophones in one borehole, on the Earth surface if desired, and by producing a sequence of shots at spaced apart locations in the other borehole. The signals, detected by each of the geophones from the various shots, are processed either on a time of arrival basis, or on the basis of signal amplitude, to provide information of the characteristics of a large number of incremental areas between the boreholes. Such information is useable to produce a tomograph of the subsoil structure between the boreholes. By processing signals of relatively high frequencies, e.g., up to 100 Hz, and by closely spacing the geophones, a high resolution tomograph can be produced.

The Ischia volcanic island (Southern Italy): Inferences from potential field data interpretation

NASA Astrophysics Data System (ADS)

Paoletti, V.; Di Maio, R.; Cella, F.; Florio, G.; Motschka, K.; Roberti, N.; Secomandi, M.; Supper, R.; Fedi, M.; Rapolla, A.

2009-01-01

In this paper we present a study of the structural setting of the volcanic island of Ischia by the analysis and interpretation of high-resolution aeromagnetic and self-potential data recently acquired over the island. The magnetic data allowed us to locate the main anomaly sources and lineaments of the island and its offshore surroundings, while the self-potential (SP) data provided information on both the structural pattern of the resurgent caldera and the high-temperature fluid circulation. An inversion of the acquired magnetic and SP data, and a joint modelling of the magnetic data and of a previous gravity data set along a SW-NE profile allowed us to build a model of the island. The model is characterized by the presence of an igneous-very likely trachytic-structure, whose top is located at 1200-1750 m b.s.l. Such a body, possibly formed by several neighbouring intrusions, has a density contrast with the pyroclastic cover of about 0.4 gr/cm 3 and its central-western part, below Mt. Epomeo, seems to be demagnetized. The demagnetization should be connected to the high geothermal gradient measured in this portion of the island and may be due to hydro-chemical alteration processes and/or to the possible presence of partially melted spots within the intrusion. Our outcome is consistent with the results of previous geophysical, geo-volcanological and geothermal studies.

Integrating limnological characteristics of high mountain lakes into the landscape of a natural area

USGS Publications Warehouse

Larson, Gary L.; Wones, A.; McIntire, C.D.; Samora, B.

1994-01-01

A general conceptual watershed-lake model of the complex interactions among climatic conditions, watershed location and characteristics, lake morphology, and fish predation was used to evaluate limnological characteristics of high mountain lakes. Our main hypothesis was that decreasing elevation in mountainous terrain corresponds to an increase in diversity of watershed size and lake area, depth, temperature, nutrient concentrations, and productivity. A second hypothesis was that watershed location and aspect relative to climatic gradients within mountainous terrain influences the limnological characteristics of the lakes. We evaluated these hypotheses by examining watershed location, aspect and size; lake morphology; water quality; and phytoplankton and zooplankton community characteristics among high mountain forest and subalpine lakes in Mount Rainier National Park. Although many of the comparisons between all forest and subalpine lakes were statistically insignificant, the results revealed trends that were consistent with our hypotheses. The forest lake group included more lakes with larger watersheds, larger surface areas, greater depths, higher concentrations of nutrients, and higher algal biovolumes than did the group of subalpine lakes. Deep lakes, which were mostly of the forest lake type, exhibited thermal stratification and relatively high values of some of the water-quality variables near the lake bottoms. However, the highest near-surface water temperatures and phytoplankton densities and the taxonomic structures of the phytoplankton and zooplankton assemblages were more closely related to geographical location, which corresponded to a west-east climate gradient in the park, than to lake type. Some crustacean and rotifer taxa, however, were limited in distribution by lake type. Fish predation did not appear to play an important role in the structure of the crustacean zooplankton communities at the genus level with the exception of Mowich Lake, where crustacean taxa were absent from the zooplankton community. This was the only lake inhabited by a true zooplanktivourous species of fish.

Structural styles of the western onshore and offshore termination of the High Atlas, Morocco

NASA Astrophysics Data System (ADS)

Hafid, Mohamad; Zizi, Mahmoud; Bally, Albert W.; Ait Salem, Abdellah

2006-01-01

The present work aims (1) at documenting, by regional seismic transects, how the structural style varies in the western High Atlas system and its prolongation under the present-day Atlantic margin, (2) at understanding how this variation is related to the local geological framework, especially the presence of salt within the sedimentary cover, and (3) at discussing the exact geographic location of the northern front of the western High Atlas and how it links with the most western Atlas front in the offshore Cap Tafelney High Atlas. Previous work showed that the structural style of the Atlas belt changes eastward from a dominantly thick-skinned one in central and eastern High Atlas and Middle Atlas of Morocco to a dominantly thin-skinned one in Algeria and Tunisia. We propose here to show that a similar structural style change can be observed in the other direction of the Atlas Belt within its western termination, where the western High Atlas intersects at right angle the Atlantic passive margin and develops into a distinct segment, namely the High Atlas of Cap Tafelney, where salt/evaporite-based décollement tectonics prevail. To cite this article: M. Hafid et al., C. R. Geoscience 338 (2006).

SuperDARN HF Scattering and Propagation in the Presence of Polar Patches Imaged Using RISR

NASA Astrophysics Data System (ADS)

Gillies, R. G.; Perry, G. W.; Varney, R. H.; Gillies, D. M.; Donovan, E.

2017-12-01

The global array of High Frequency (HF) Super Dual Auroral Radar Network (SuperDARN) radars continuously monitors ionospheric convection in the middle-to-high latitude region. The radars measure coherent backscatter from decameter scale field-aligned irregularities. One of the main generation mechanisms for these field-aligned irregularities is the gradient drift instability (GDI). The edges of ionospheric density structures, such as polar cap patches, provide ideal locations for GDI growth. The geometry required for GDI growth results in irregularities forming on the trailing edge of polar patches. However, irregularities generated by the non-linear evolution of the GDI can become prevalent throughout the patch within minutes. Modelling the irregularity growth and measurements of backscatter within patches have both confirmed this. One aspect that has often been overlooked in studies of coherent backscatter within patches is the effect of HF propagation on echo location. This study examines HF echo locations in the vicinity of patches that were imaged using the Resolute Bay Incoherent Scatter Radars (RISR). The effect of both vertical and lateral refraction of the HF wave on echo location is examined.

High-density, fail-in-place switches for computer and data networks

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

Coteus, Paul W.; Doany, Fuad E.; Hall, Shawn A.

A structure for a network switch. The network switch may include a plurality of spine chips arranged on a plurality of spine cards, where one or more spine chips are located on each spine card; and a plurality of leaf chips arranged on a plurality of leaf cards, wherein one or more leaf chips are located on each leaf card, where each spine card is connected to every leaf chip and the plurality of spine chips are surrounded on at least two sides by leaf cards.

On the failure behaviour to striking bow penetration of impacted marine-steel structures

NASA Astrophysics Data System (ADS)

Prabowo, Aditya Rio; Muttaqie, Teguh; Sohn, Jung Min; Bae, Dong Myung; Setiyawan, Agus

2018-04-01

Demands for water transportation modes are continuously increasing as rapid economic and industrial growths in the recent decade. Ship as representative of the water transportation is generally needed to carry various products from one location to another. Besides as product carrier, ship also acts as public facility to transport human across islands for number of reasons, such as tourism and vehicle. Considering its importance, structural damage due to accidental loads or so-called impact can cause unacceptable casualties which threat ship passenger, shipping industry and maritime environment in same time. The most frequent impact phenomena occur in forms of collision and grounding, which are targeting side structure and double bottom consecutively. However, since responses of the impacts on structure are highly nonlinear and vary due to development of ship structures, sustainable analysis as an update of pioneer calculation can be beneficial as rational reference for improving safety and navigational instruments. This work aims to assess failures of the side structures subjected to penetration of striking bow in ship-ship collision scenario. Locations of impact are idealized to happen on after-end, midsection and fore-end to provide complete assessment. Striking bow is to be deployed by varying input velocity to observe significance of the fractures on the side structure. This configuration is implemented on the designed collision scenario, and later calculated using nonlinear finite element method (NLFEM). Summary of the solution indicated that the midsection produced the highest resistance against side collision. Breaching of the inner shell was successfully avoided on the fore-end, but the critical damage to the cargo was observed during bow penetration to the after-end region. This location was recommended to be added by longitudinal framing to increase its resistance against ship collision.

Differences in Intertidal Microbial Assemblages on Urban Structures and Natural Rocky Reef

PubMed Central

Tan, Elisa L.-Y.; Mayer-Pinto, Mariana; Johnston, Emma L.; Dafforn, Katherine A.

2015-01-01

Global seascapes are increasingly modified to support high levels of human activity in the coastal zone. Modifications include the addition of defense structures and boating infrastructure, such as seawalls and marinas that replace natural habitats. Artificial structures support different macrofaunal communities to those found on natural rocky shores; however, little is known about differences in microbial community structure or function in urban seascapes. Understanding how artificial constructions in marine environments influence microbial communities is important as these assemblages contribute to many basic ecological processes. In this study, the bacterial communities of intertidal biofilms were compared between artificial structures (seawalls) and natural habitats (rocky shores) within Sydney Harbour. Plots were cleared on each type of habitat at eight locations. After 3 weeks the newly formed biofilm was sampled and the 16S rRNA gene sequenced using the Illumina Miseq platform. To account for differences in orientation and substrate material between seawalls and rocky shores that might have influenced our survey, we also deployed recruitment blocks next to the habitats at all locations for 3 weeks and then sampled and sequenced their microbial communities. Intertidal bacterial community structure sampled from plots differed between seawalls and rocky shores, but when substrate material, age and orientation were kept constant (with recruitment blocks) then bacterial communities were similar in composition and structure among habitats. This suggests that changes in bacterial communities on seawalls are not related to environmental differences between locations, but may be related to other intrinsic factors that differ between the habitats such as orientation, complexity, or predation. This is one of the first comparisons of intertidal microbial communities on natural and artificial surfaces and illustrates substantial ecological differences with potential consequences for biofilm function and the recruitment of macrofauna. PMID:26635747

Strong population structure in the marine sponge Crambe crambe (Poecilosclerida) as revealed by microsatellite markers.

PubMed

Duran, S; Pascual, M; Estoup, A; Turon, X

2004-03-01

Different categories of molecular markers have been used so far to study the population structure of sponges. However, these markers often did not have the resolution power to address precisely questions on structuring processes, especially at the intrapopulational level. In this study we show that microsatellites fulfil these expectations, allowing a fine description of population structure at different geographical scales in the marine sponge Crambe crambe. Specimens were collected in 11 locations, representing most of the Atlanto-Mediterranean range of the species, and were analysed at six loci. As expected for a sessile invertebrate with lecitotrophic larvae, high levels of between-population structure were found (FST = 0.18) and a significant isolation-by-distance pattern was observed. A strong genetic structure was also found within sampled sites (FIS = 0.21) that may be explained by several factors including inbreeding, selfing and the Wahlund effect. In spite of a sampling design planned to avoid the sampling of clones, genotypically identical individuals for the six loci were found in some locations. The significance of these potential clones is discussed and their effect on the observed pattern of population structure assessed. Patterns of allelic distribution within populations suggest the possibility of a recent colonization of the Atlantic range from the Mediterranean Sea.

Genetic diversity and population structure analysis in Perilla frutescens from Northern areas of China based on simple sequence repeats.

PubMed

Ma, S J; Sa, K J; Hong, T K; Lee, J K

2017-09-21

In this study, 21 simple sequence repeat (SSR) markers were used to evaluate the genetic diversity and population structure among 77 Perilla accessions from high-latitude and middle-latitude areas of China. Ninety-five alleles were identified with an average of 4.52 alleles per locus. The average polymorphic information content (PIC) and genetic diversity values were 0.346 and 0.372, respectively. The level of genetic diversity and PIC value for cultivated accessions of Perilla frutescens var. frutescens from middle-latitude areas were higher than accessions from high-latitude areas. Based on the dendrogram of unweighted pair group method with arithmetic mean (UPGMA), all accessions were classified into four major groups with a genetic similarity of 46%. All accessions of the cultivated var. frutescens were discriminated from the cultivated P. frutescens var. crispa. Furthermore, most accessions of the cultivated var. frutescens collected in high-latitude and middle-latitude areas were distinguished depending on their geographical location. However, the geographical locations of several accessions of the cultivated var. frutescens have no relation with their positions in the UPGMA dendrogram and population structure. This result implies that the diffusion of accessions of the cultivated Perilla crop in the northern areas of China might be through multiple routes. On the population structure analysis, 77 Perilla accessions were divided into Group I, Group II, and an admixed group based on a membership probability threshold of 0.8. Finally, the findings in this study can provide useful theoretical knowledge for further study on the population structure and genetic diversity of Perilla and benefit for Perilla crop breeding and germplasm conservation.

Three-dimensional P-wave velocity structure of Mt. Etna, Italy

USGS Publications Warehouse

Villasenor, A.; Benz, H.M.; Filippi, L.; De Luca, G.; Scarpa, R.; Patane, G.; Vinciguerra, S.

1998-01-01

The three-dimensional P-wave velocity structure of Mt. Etna is determined to depths of 15 km by tomographic inversion of first arrival times from local earthquakes recorded by a network of 29 permanent and temporary seismographs. Results show a near-vertical low-velocity zone that extends from beneath the central craters to a depth of 10 km. This low-velocity region is coincident with a band of steeply-dipping seismicity, suggesting a magmatic conduit that feeds the summit eruptions. The most prominent structure is an approximately 8-km-diameter high-velocity body located between 2 and 12 km depth below the southeast flank of the volcano. This high-velocity body is interpreted as a remnant mafic intrusion that is an important structural feature influencing both volcanism and east flank slope stability and faulting.

Regional-scale drivers of marine nematode distribution in Southern Ocean continental shelf sediments

NASA Astrophysics Data System (ADS)

Hauquier, Freija; Verleyen, Elie; Tytgat, Bjorn; Vanreusel, Ann

2018-07-01

Many marine meiofauna taxa seem to possess cosmopolitan species distributions, despite their endobenthic lifestyle and restricted long-distance dispersal capacities. In light of this paradox we used a metacommunity framework to study spatial turnover in free-living nematode distribution and assess the importance of local environmental conditions in explaining differences between communities in surface and subsurface sediments of the Southern Ocean continental shelf. We analysed nematode community structure in two sediment layers (0-3 cm and 3-5 cm) of locations maximum 2400 km apart. We first focused on a subset of locations to evaluate whether the genus level is sufficiently taxonomically fine-grained to study large-scale patterns in nematode community structure. We subsequently used redundancy and variation partitioning analyses to quantify the unique and combined effects of local environmental conditions and spatial descriptors on genus-level community composition. Macroecological patterns in community structure were highly congruent at the genus and species level. Nematode community composition was highly divergent between both depth strata, likely as a result of local abiotic conditions. Variation in community structure between the different regions largely stemmed from turnover (i.e. genus/species replacement) rather than nestedness (i.e. genus/species loss). The level of turnover among communities increased with geographic distance and was more pronounced in subsurface layers compared to surface sediments. Variation partitioning analysis revealed that both environmental and spatial predictors significantly explained variation in community structure. Moreover, the shared fraction of both sets of variables was high, which suggested a substantial amount of spatially structured environmental variation. Additionally, the effect of space independent of environment was much higher than the effect of environment independent of space, which shows the importance of including spatial descriptors in meiofauna and nematode community ecology. Large-scale assessment of free-living nematode diversity and abundance in the Southern Ocean shelf zone revealed strong horizontal and vertical spatial structuring in response to local environmental conditions, in combination with (most likely) dispersal limitation.

36 CFR 327.30 - Shoreline Management on Civil Works Projects.

Code of Federal Regulations, 2011 CFR

2011-07-01

... excessive siltation, erosion, rapid dewatering, or exposure to high wind, wave, or current action and/or in..., hydro-electric power stations, work areas, water intake structures, etc. No shoreline use permits will... costs, one year permits should be issued only when the location or nature of the activity requires...

Forecasting Urban Forest Ecosystem Structure, Function, and Vulnerability

Treesearch

James W. N. Steenberg; Andrew A. Millward; David J. Nowak; Pamela J. Robinson; Alexis Ellis

2016-01-01

The benefits derived from urban forest ecosystems are garnering increasing attention in ecological research and municipal planning. However, because of their location in heterogeneous and highly-altered urban landscapes, urban forests are vulnerable and commonly suffer disproportionate and varying levels of stress and disturbance. The objective of this study is to...

Lightning Mapping With an Array of Fast Antennas

NASA Astrophysics Data System (ADS)

Wu, Ting; Wang, Daohong; Takagi, Nobuyuki

2018-04-01

Fast Antenna Lightning Mapping Array (FALMA), a low-frequency lightning mapping system comprising an array of fast antennas, was developed and established in Gifu, Japan, during the summer of 2017. Location results of two hybrid flashes and a cloud-to-ground flash comprising 11 return strokes (RSs) are described in detail in this paper. Results show that concurrent branches of stepped leaders can be readily resolved, and K changes and dart leaders with speeds up to 2.4 × 107 m/s are also well imaged. These results demonstrate that FALMA can reconstruct three-dimensional structures of lightning flashes with great details. Location accuracy of FALMA is estimated by comparing the located striking points of successive RSs in cloud-to-ground flashes. Results show that distances between successive RSs are mainly below 25 m, indicating exceptionally high location accuracy of FALMA.

Structural conservation, variability, and immunogenicity of the T6 backbone pilin of serotype M6 Streptococcus pyogenes.

PubMed

Young, Paul G; Moreland, Nicole J; Loh, Jacelyn M; Bell, Anita; Atatoa Carr, Polly; Proft, Thomas; Baker, Edward N

2014-07-01

Group A streptococcus (GAS; Streptococcus pyogenes) is a Gram-positive human pathogen that causes a broad range of diseases ranging from acute pharyngitis to the poststreptococcal sequelae of acute rheumatic fever. GAS pili are highly diverse, long protein polymers that extend from the cell surface. They have multiple roles in infection and are promising candidates for vaccine development. This study describes the structure of the T6 backbone pilin (BP; Lancefield T-antigen) from the important M6 serotype. The structure reveals a modular arrangement of three tandem immunoglobulin-like domains, two with internal isopeptide bonds. The T6 pilin lysine, essential for polymerization, is located in a novel VAKS motif that is structurally homologous to the canonical YPKN pilin lysine in other three- and four-domain Gram-positive pilins. The T6 structure also highlights a conserved pilin core whose surface is decorated with highly variable loops and extensions. Comparison to other Gram-positive BPs shows that many of the largest variable extensions are found in conserved locations. Studies with sera from patients diagnosed with GAS-associated acute rheumatic fever showed that each of the three T6 domains, and the largest of the variable extensions (V8), are targeted by IgG during infection in vivo. Although the GAS BP show large variations in size and sequence, the modular nature of the pilus proteins revealed by the T6 structure may aid the future design of a pilus-based vaccine. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Acoustically Mounted Microcrystals Yield High Resolution X-ray Structures†,‡

PubMed Central

Soares, Alexei S.; Engel, Matthew A.; Stearns, Richard; Datwani, Sammy; Olechno, Joe; Ellson, Richard; Skinner, John M.; Allaire, Marc; Orville, Allen M.

2011-01-01

We demonstrate a general strategy to determine structures from showers of microcrystals. It uses acoustic droplet ejection (ADE) to transfer 2.5 nanoliter droplets from the surface of microcrystal slurries, through the air, and onto mounting micromesh pins. Individual microcrystals are located by raster-scanning a several micron X-ray beam across the cryocooled micromeshes. X-ray diffraction datasets merged from several micron-sized crystals are used to solve 1.8 Å resolution crystal structures. PMID:21542590

Determining the Thickness and the Sub-Structure Details of the Magnetopause from MMS Data

NASA Astrophysics Data System (ADS)

Manuzzo, R.; Belmont, G.; Rezeau, L.

2017-12-01

The magnetopause thickness, like its mean location, is a notion that can have different meanings depending which parameters are considered (magnetic field or plasma properties). In any case, all the determinations have been done, up to now, considering the magnetopause boundary as a structure strictly stationary and 1D (or with a simple curvature). These determinations have shown to be very sensitive to the accuracy of the normal direction, because it affects the projection of the quantities of interest in studying geometrical sensitive phenomena such as the magnetic reconnection. Furthermore, the 1D stationary assumptions are likely to be rarely verified at the real magnetopause. The high quality measurements of MMS and their high time resolution now allow investigating the magnetopause structure in its more delicate features and with an unequal spatio-temporal accuracy. We make use here of the MDD tool developed by [Shi et al., 2005], which gives the dimensionality of the gradients from the four-point measurements of MMS and allows estimating the direction of the local normal when defined. Extending this method to various quantities, we can draw their profiles as functions of a physical abscissa (length instead of time) along a sensible normal. This procedure allows answering quantitatively the questions concerning the locations and the thicknesses of the different sub-structures encountered inside the "global magnetopause" [Rezeau, 2017, paper submitted to JGR-Space Physics].

Biophysical connectivity explains population genetic structure in a highly dispersive marine species

NASA Astrophysics Data System (ADS)

Truelove, Nathan K.; Kough, Andrew S.; Behringer, Donald C.; Paris, Claire B.; Box, Stephen J.; Preziosi, Richard F.; Butler, Mark J.

2017-03-01

Connectivity, the exchange of individuals among locations, is a fundamental ecological process that explains how otherwise disparate populations interact. For most marine organisms, dispersal occurs primarily during a pelagic larval phase that connects populations. We paired population structure from comprehensive genetic sampling and biophysical larval transport modeling to describe how spiny lobster ( Panulirus argus) population differentiation is related to biological oceanography. A total of 581 lobsters were genotyped with 11 microsatellites from ten locations around the greater Caribbean. The overall F ST of 0.0016 ( P = 0.005) suggested low yet significant levels of structuring among sites. An isolation by geographic distance model did not explain spatial patterns of genetic differentiation in P. argus ( P = 0.19; Mantel r = 0.18), whereas a biophysical connectivity model provided a significant explanation of population differentiation ( P = 0.04; Mantel r = 0.47). Thus, even for a widely dispersing species, dispersal occurs over a continuum where basin-wide larval retention creates genetic structure. Our study provides a framework for future explorations of wide-scale larval dispersal and marine connectivity by integrating empirical genetic research and probabilistic modeling.

Detecting Structural Failures Via Acoustic Impulse Responses

NASA Technical Reports Server (NTRS)

Bayard, David S.; Joshi, Sanjay S.

1995-01-01

Advanced method of acoustic pulse reflectivity testing developed for use in determining sizes and locations of failures within structures. Used to detect breaks in electrical transmission lines, detect faults in optical fibers, and determine mechanical properties of materials. In method, structure vibrationally excited with acoustic pulse (a "ping") at one location and acoustic response measured at same or different location. Measured acoustic response digitized, then processed by finite-impulse-response (FIR) filtering algorithm unique to method and based on acoustic-wave-propagation and -reflection properties of structure. Offers several advantages: does not require training, does not require prior knowledge of mathematical model of acoustic response of structure, enables detection and localization of multiple failures, and yields data on extent of damage at each location.

Fine-scale delineation of the location of and relative ground shaking within the San Andreas Fault zone at San Andreas Lake, San Mateo County, California

USGS Publications Warehouse

Catchings, R.D.; Rymer, M.J.; Goldman, M.R.; Prentice, C.S.; Sickler, R.R.

2013-01-01

The San Francisco Public Utilities Commission is seismically retrofitting the water delivery system at San Andreas Lake, San Mateo County, California, where the reservoir intake system crosses the San Andreas Fault (SAF). The near-surface fault location and geometry are important considerations in the retrofit effort. Because the SAF trends through highly distorted Franciscan mélange and beneath much of the reservoir, the exact trace of the 1906 surface rupture is difficult to determine from surface mapping at San Andreas Lake. Based on surface mapping, it also is unclear if there are additional fault splays that extend northeast or southwest of the main surface rupture. To better understand the fault structure at San Andreas Lake, the U.S. Geological Survey acquired a series of seismic imaging profiles across the SAF at San Andreas Lake in 2008, 2009, and 2011, when the lake level was near historical lows and the surface traces of the SAF were exposed for the first time in decades. We used multiple seismic methods to locate the main 1906 rupture zone and fault splays within about 100 meters northeast of the main rupture zone. Our seismic observations are internally consistent, and our seismic indicators of faulting generally correlate with fault locations inferred from surface mapping. We also tested the accuracy of our seismic methods by comparing our seismically located faults with surface ruptures mapped by Schussler (1906) immediately after the April 18, 1906 San Francisco earthquake of approximate magnitude 7.9; our seismically determined fault locations were highly accurate. Near the reservoir intake facility at San Andreas Lake, our seismic data indicate the main 1906 surface rupture zone consists of at least three near-surface fault traces. Movement on multiple fault traces can have appreciable engineering significance because, unlike movement on a single strike-slip fault trace, differential movement on multiple fault traces may exert compressive and extensional stresses on built structures within the fault zone. Such differential movement and resulting distortion of built structures appear to have occurred between fault traces at the gatewell near the southern end of San Andreas Lake during the 1906 San Francisco earthquake (Schussler, 1906). In addition to the three fault traces within the main 1906 surface rupture zone, our data indicate at least one additional fault trace (or zone) about 80 meters northeast of the main 1906 surface rupture zone. Because ground shaking also can damage structures, we used fault-zone guided waves to investigate ground shaking within the fault zones relative to ground shaking outside the fault zones. Peak ground velocity (PGV) measurements from our guided-wave study indicate that ground shaking is greater at each of the surface fault traces, varying with the frequency of the seismic data and the wave type (P versus S). S-wave PGV increases by as much as 5–6 times at the fault traces relative to areas outside the fault zone, and P-wave PGV increases by as much as 3–10 times. Assuming shaking increases linearly with increasing earthquake magnitude, these data suggest strong shaking may pose a significant hazard to built structures that extend across the fault traces. Similarly complex fault structures likely underlie other strike-slip faults (such as the Hayward, Calaveras, and Silver Creek Faults) that intersect structures of the water delivery system, and these fault structures similarly should be investigated.

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

Polat, Orhan, E-mail: orhan.polat@deu.edu.tr; Özer, Çaglar, E-mail: caglar.ozer@deu.edu.tr; Dokuz Eylul University, The Graduate School of Natural and Applied Sciences, Department of Geophysical Engineering, Izmir-Turkey

In this study; we examined one dimensional crustal velocity structure of Izmir gulf and surroundings. We used nearly one thousand high quality (A and B class) earthquake data which recorded by Disaster and Emergency Management Presidency (AFAD) [1], Bogazici University (BU-KOERI) [2] and National Observatory of Athens (NOA) [3,4]. We tried several synthetic tests to understand power of new velocity structure, and examined phase residuals, RMS values and shifting tests. After evaluating these tests; we decided one dimensional velocity structure and minimum 1-D P wave velocities, hypocentral parameter and earthquake locations from VELEST algorithm. Distribution of earthquakes was visibly improvedmore » by using new minimum velocity structure.« less

Experimental measurement of structural power flow on an aircraft fuselage

NASA Technical Reports Server (NTRS)

Cuschieri, J. M.

1991-01-01

An experimental technique is used to measure structural intensity through an aircraft fuselage with an excitation load applied near one of the wing attachment locations. The fuselage is a relatively large structure, requiring a large number of measurement locations to analyze the whole of the structure. For the measurement of structural intensity, multiple point measurements are necessary at every location of interest. A tradeoff is therefore required between the number of measurement transducers, the mounting of these transducers, and the accuracy of the measurements. Using four transducers mounted on a bakelite platform, structural intensity vectors are measured at locations distributed throughout the fuselage. To minimize the errors associated with using the four transducer technique, the measurement locations are selected to be away from bulkheads and stiffeners. Furthermore, to eliminate phase errors between the four transducer measurements, two sets of data are collected for each position, with the orientation of the platform with the four transducers rotated by 180 degrees and an average taken between the two sets of data. The results of these measurements together with a discussion of the suitability of the approach for measuring structural intensity on a real structure are presented.

Food choice effects on herbivory: Intra-specific seagrass palatability and inter-specific macrophyte palatability in seagrass communities

NASA Astrophysics Data System (ADS)

Jiménez-Ramos, Rocío; Brun, Fernando G.; Egea, Luis G.; Vergara, Juan J.

2018-05-01

Interactions between the palatability and abundance of different food sources may influence herbivory patterns in seagrass-dominated communities. In addition, intra-specific differences in nutrient and structural quality of leaves may also alter seagrass palatability and generate different rates of consumption within these communities. We offered two temperate seagrasses species, (Cymodocea nodosa and Zostera noltei) from two different locations to look at intraspecific differences, and two other macrophytes, both of which occur at the same location as seagrasses but represent the extremes of palatability, to a generalist herbivore Paracentrotus lividus (purple sea urchin). Using feeding assays, we compared the consumption rates in individual (single plant species) and combined diets at different food availabilities. Intra-specific differences between seagrass species growing at different locations (inner and outer bay) were indeed found to significantly modify the consumption rate for one species. Structural traits such as carbon content were linked to the low consumption found in Cymodocea nodosa from the inner bay location. In addition, we found that the co-occurrence of different macrophyte species can result in preferential consumption of the more palatable macrophyte with high nutritional content and low structural defence over seagrasses, especially when P. lividus has an abundant food supply. Overall, our findings suggest that intra- and inter-specific differences in seagrass traits and the relative abundance of other macrophytes may explain the variability in patterns of herbivory found within seagrass communities.

Measures to reduce construction time of high-rise buildings

NASA Astrophysics Data System (ADS)

Kolchedantsev, Leonid; Adamtsevich, Aleksey; Stupakova, Olga; Drozdov, Alexander

2018-03-01

The organizational and technological solutions for high-rise buildings construction efficiency increase are considered, primarily - decrease of typical floor construction time and improvement of bearing structures concrete quality. The essence of offered technology is: a concrete mixing station and a polygon mainly for load-bearing wall panels with starter bars casting are located on the building site; for reinforced concrete components manufacturing and butt joints grouting the warmed-up concrete mixtures are used. The results of researches and elaborations carried out by the SPSUACE in area of a preliminary warming-up of concrete mixtures are presented. The possibility and feasibility of their usage in high-rise buildings and of excess height buildings construction including cast-in-place and precast execution are shown. The essence of heat-vibro treating of concrete mixture is revealed as a kind of prior electroresistive curing, and the achieved results are: accelerated concrete strength gain, power inputs decrease, concrete quality improvement. It is shown that the location of a concrete mixing station on the building site enables to broaden possibilities of the "thermos" method use and to avoid concrete mixtures warming up in medium-mass structures erection (columns, girders) during the high-rise buildings construction. It is experimentally proved that the splice between precast elements encased with warmed-up concrete mixture is equal with conjugated elements in strength.

Hydrophilic structures for condensation management in appliances

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

Kuehl, Steven John; Vonderhaar, John J.; Wu, Guolian

2016-02-02

An appliance that includes a cabinet having an exterior surface; a refrigeration compartment located within the cabinet; and a hydrophilic structure disposed on the exterior surface. The hydrophilic structure is configured to spread condensation. The appliance further includes a wicking structure located in proximity to the hydrophilic structure, and the wicking structure is configured to receive the condensation.

Variation and genetic structure of Melipona quadrifasciata Lepeletier (Hymenoptera, Apidae) populations based on ISSR pattern

PubMed Central

2010-01-01

For a study of diversity and genetic structuring in Melipona quadrifasciata, 61 colonies were collected in eight locations in the state of Minas Gerais, Brazil. By means of PCR analysis, 119 ISSR bands were obtained, 80 (68%) being polymorphic. He and H B were 0.20 and 0.16, respectively. Two large groups were obtained by the UPGMA method, one formed by individuals from Januária, Urucuia, Rio Vermelho and Caeté and the other by individuals from São João Del Rei, Barbacena, Ressaquinha and Cristiano Otoni. The Φst and θB values were 0.65 and 0.58, respectively, thereby indicating high population structuring. UPGMA grouping did not reveal genetic structuring of M. quadrifasciata in function of the tergite stripe pattern. The significant correlation between dissimilarity values and geographic distances (r = 0.3998; p < 0.05) implies possible geographic isolation. The genetic differentiation in population grouping was probably the result of an interruption in gene flow, brought about by geographic barriers between mutually close geographical locations. Our results also demonstrate the potential of ISSR markers in the study of Melipona quadrifasciata population structuring, possibly applicable to the studies of other bee species. PMID:21637500

Variation and genetic structure of Melipona quadrifasciata Lepeletier (Hymenoptera, Apidae) populations based on ISSR pattern.

PubMed

Nascimento, Marcília A; Batalha-Filho, Henrique; Waldschmidt, Ana M; Tavares, Mara G; Campos, Lucio A O; Salomão, Tânia M F

2010-04-01

For a study of diversity and genetic structuring in Melipona quadrifasciata, 61 colonies were collected in eight locations in the state of Minas Gerais, Brazil. By means of PCR analysis, 119 ISSR bands were obtained, 80 (68%) being polymorphic. H(e) and H (B) were 0.20 and 0.16, respectively. Two large groups were obtained by the UPGMA method, one formed by individuals from Januária, Urucuia, Rio Vermelho and Caeté and the other by individuals from São João Del Rei, Barbacena, Ressaquinha and Cristiano Otoni. The Φst and θ(B) values were 0.65 and 0.58, respectively, thereby indicating high population structuring. UPGMA grouping did not reveal genetic structuring of M. quadrifasciata in function of the tergite stripe pattern. The significant correlation between dissimilarity values and geographic distances (r = 0.3998; p < 0.05) implies possible geographic isolation. The genetic differentiation in population grouping was probably the result of an interruption in gene flow, brought about by geographic barriers between mutually close geographical locations. Our results also demonstrate the potential of ISSR markers in the study of Melipona quadrifasciata population structuring, possibly applicable to the studies of other bee species.

Geoarchaeological results from geophysical prospections at the Roman city of Urbs Salvia, central Italy

NASA Astrophysics Data System (ADS)

Schettino, Antonio; Perna, Roberto; Pierantoni, Pietro Paolo; Ghezzi, Annalisa; Tassi, Luca; Cingolani, Sofia

2017-04-01

We report on a combined magnetic-GPR survey performed in 2015 and 2016 at the ancient Roman city of Urbs Salvia, located in central Italy. The main objective of this survey was to reconstruct the urban organization of the city forum and determine possible sites of future excavations. We found a complex pattern of buried structures, possibly resulting from the coexistence of republican and imperial artifacts and burned structures. A test excavation at the location where we detected a long linear structure characterized by strong magnetic signal revealed the presence of thermal baths. GPR data were acquired in areas characterized by high magnetic noise induced by metallic infrastructures (e.g., fences), which prevented a correct acquisition of archaeological anomalies. These data not only allowed to overcome the magnetic noise, but provided interesting 3D reconstructions of the buried structures. A detailed GPR survey in the theatre area was also performed, with the aim to investigate the plan of the porticus post scaenam. This survey allowed to identify some interesting structures related to different chronological phases and confirms the epigraphic data related to the development of the monument.

Force Criterion Prediction of Damage for Carbon/Epoxy Composite Panels Impacted by High Velocity Ice

NASA Astrophysics Data System (ADS)

Rhymer, Jennifer D.

The use of advanced fiber-reinforced polymer matrix composites in load-bearing aircraft structures is increasing, as evident by the various composites-intensive transport aircraft presently under development. A major impact source of concern for these structures is hail ice, which affects design and skin-sizing (skin thickness determination) at various locations of the aircraft. Impacts onto composite structures often cause internal damage that is not visually detectable due to the high strength and resiliency of the composite material (unlike impacts onto metallic structures). This internal damage and its effect on the performance of the structure are of great concern to the aircraft industry. The prediction of damage in composite structures due to SHI impact has been accomplished via experimental work, explicit dynamic nonlinear finite element analysis (FEA) and the definition of design oriented relationships. Experiments established the critical threshold and corresponding analysis provided contact force results not readily measurable in high velocity SHI impact experiments. The design oriented relationships summarize the FEA results and experimental database into contact force estimation curves that can be easily applied for damage prediction. Failure thresholds were established for the experimental conditions (panel thickness ranging from 1.56 to 4.66 mm and ice diameters from 38.1 to 61.0 mm). Additionally, the observations made by high-speed video during the impact event, and ultrasonic C-scan post-impact, showed how the ice failed during impact and the overall shape and location of the panel damage. Through analysis, the critical force, the force level where damage occurs above but not below, of a SHI impact onto the panel was found to be dependent only on the target structure. However, the peak force generated during impact was dependent on both the projectile and target. Design-oriented curves were generated allowing the prediction of the allowable velocity for given SHI diameter impact onto a known panel in order to estimated damage. Finally, a scaling relationship was established to predict the peak force developed onto composite panels impacted by SHI. This is useful in reducing the amount of experimental investigations, or computationally expensive simulation work, that would otherwise need to be performed to obtain these results.

Application of ground-penetrating radar imagery for three-dimensional visualisation of near-surface structures in ice-rich permafrost, Barrow, Alaska

USGS Publications Warehouse

Munroe, Jeffrey S.; Doolittle, James A.; Kanevskiy, Mikhail; Hinkel, Kenneth M.; Nelson, Frederick E.; Jones, Benjamin M.; Shur, Yuri; Kimble, John M.

2007-01-01

Three-dimensional ground-penetrating radar (3D GPR) was used to investigate the subsurface structure of ice-wedge polygons and other features of the frozen active layer and near-surface permafrost near Barrow, Alaska. Surveys were conducted at three sites located on landscapes of different geomorphic age. At each site, sediment cores were collected and characterised to aid interpretation of GPR data. At two sites, 3D GPR was able to delineate subsurface ice-wedge networks with high fidelity. Three-dimensional GPR data also revealed a fundamental difference in ice-wedge morphology between these two sites that is consistent with differences in landscape age. At a third site, the combination of two-dimensional and 3D GPR revealed the location of an active frost boil with ataxitic cryostructure. When supplemented by analysis of soil cores, 3D GPR offers considerable potential for imaging, interpreting and 3D mapping of near-surface soil and ice structures in permafrost environments.

Population differentiation in the red-legged kittiwake (Rissa brevirostris) as revealed by mitochondrial DNA

USGS Publications Warehouse

Patirana, A.; Hatcher, S.A.; Friesen, Vicki L.

2002-01-01

Population decline in red-legged kittiwakes (Rissa brevirostris) over recent decades has necessitated the collection of information on the distribution of genetic variation within and among colonies for implementation of suitable management policies. Here we present a preliminary study of the extent of genetic structuring and gene flow among the three principal breeding locations of red-legged kittiwakes using the hypervariable Domain I of the mitochondrial control region. Genetic variation was high relative to other species of seabirds, and was similar among locations. Analysis of molecular variance indicated that population genetic structure was statistically significant, and nested clade analysis suggested that kittiwakes breeding on Bering Island maybe genetically isolated from those elsewhere. However, phylogeographic structure was weak. Although this analysis involved only a single locus and a small number of samples, it suggests that red-legged kittiwakes probably constitute a single evolutionary significant unit; the possibility that they constitute two management units requires further investigation.

Prediction of Fretting Crack Location and Orientation in a Single Crystal Nickel Alloy

NASA Technical Reports Server (NTRS)

Matlik, J. F.; Farris, T. N.; Haynes, J.; Swanson, G. R.; Ham-Battista, G.

2005-01-01

Fretting is a structural damage mechanism arising between two nominally clamped surfaces subjected to an oscillatory loading. A critical location for fretting induced damage has been identified at the blade/disk and blade/damper interfaces of gas turbine engine turbomachinery and space propulsion components. The high- temperature, high-frequency loading environment seen by these components lead to severe stress gradients at the edge-of-contact that could potentially foster crack growth leading to component failure. These contact stresses drive crack nucleation in fretting and are very sensitive to the geometry of the contacting bodies, the contact loads, materials, temperature, and contact surface tribology (friction). Recently, a high-frequency, high-temperature load frame has been designed for experimentally investigating fretting damage of single crystal nickel materials employed in aircraft and spacecraft turbomachinery. A modeling method for characterizing the fretting stresses of the spherical fretting contact stress behavior in this experiment is developed and described. The calculated fretting stresses for a series of experiments are then correlated to the observed fretting damage. Results show that knowledge of the normal stresses and resolved shear stresses on each crystal plane can aid in predicting crack locations and orientations.

Lipid and glycolipid isomer analyses using ultra-high resolution ion mobility spectrometry separations

DOE PAGES

Wojcik, Roza; Webb, Ian K.; Deng, Liulin; ...

2017-01-18

Understanding the biological mechanisms related to lipids and glycolipids is challenging due to the vast number of possible isomers. Mass spectrometry (MS) measurements are currently the dominant approach for studying and providing detailed information on lipid and glycolipid structures. However, difficulties in distinguishing many structural isomers (e.g. distinct acyl chain positions, double bond locations, as well as glycan isomers) inhibit the understanding of their biological roles. Here we utilized ultra-high resolution ion mobility spectrometry (IMS) separations based upon the use of traveling waves in a serpentine long path length multi-pass Structures for Lossless Manipulations (SLIM) to enhance isomer resolution. Themore » multi-pass arrangement allowed separations ranging from ~16 m (1 pass) to ~470 m (32 passes) to be investigated for the distinction of lipids and glycolipids with extremely small structural differences. Lastly, these ultra-high resolution SLIM IMS-MS analyses provide a foundation for exploring and better understanding isomer specific biological and disease processes.« less

Investigation of SSME alternate high pressure fuel turbopump lift-off seal fluid and structural dynamic interaction

NASA Technical Reports Server (NTRS)

Elrod, David A.

1989-01-01

The Space Shuttle main engine (SSME) alternate turbopump development program (ATD) high pressure fuel turbopump (HPFTP) design utilizes an innovative lift-off seal (LOS) design that is located in close proximity to the turbine end bearing. Cooling flow exiting the bearing passes through the lift-off seal during steady state operation. The potential for fluid excitation of lift-off seal structural resonances is investigated. No fluid excitation of LOS resonances is predicted. However, if predicted LOS natural frequencies are significantly lowered by the presence of the coolant, pressure oscillations caused by synchronous whirl of the HPFTP rotor may excite a resonance.

System identification of a tied arch bridge using reference-based wireless sensor networks

NASA Astrophysics Data System (ADS)

Hietbrink, Colby; Whelan, Matthew J.

2012-04-01

Vibration-based methods of structural health monitoring are generally founded on the principle that localized damage to a structure would exhibit changes within the global dynamic response. Upon this basis, accelerometers provide a unique health monitoring strategy in that a distributed network of sensors provides the technical feasibility to isolate the onset of damage without requiring that any sensor be located exactly on or in close proximity to the damage. While in theory this may be sufficient, practical experience has shown significant improvement in the application of damage diagnostic routines when mode shapes characterized by strongly localized behavior of specific elements are captured by the instrumentation array. In traditional applications, this presents a challenge since the cost and complexity of cable-based systems often effectively limits the number of instrumented locations thereby constraining the modal parameter extraction to only global modal responses. The advent of the low-cost RF chip transceiver with wireless networking capabilities has afforded a means by which a substantial number of output locations can be measured through referencebased testing using large-scale wireless sensor networks. In the current study, this approach was applied to the Prairie du Chien Bridge over the Mississippi River to extract operational mode shapes with high spatial reconstruction, including strongly localized modes. The tied arch bridge was instrumented at over 230 locations with single-axis accelerometers conditioned and acquired over a high-rate lossless wireless sensor network with simultaneous sampling capabilities. Acquisition of the dynamic response of the web plates of the arch rib was specifically targeted within the instrumentation array for diagnostic purposes. Reference-based operational modal analysis of the full structure through data-driven stochastic subspace identification is presented alongside finite element analysis results for confirmation of modal parameter plausibility. Particular emphasis is placed on the identification and reconstruction of modal response with large contribution from the arch rib web plates.

Method of fan sound mode structure determination computer program user's manual: Microphone location program

NASA Technical Reports Server (NTRS)

Pickett, G. F.; Wells, R. A.; Love, R. A.

1977-01-01

A computer user's manual describing the operation and the essential features of the microphone location program is presented. The Microphone Location Program determines microphone locations that ensure accurate and stable results from the equation system used to calculate modal structures. As part of the computational procedure for the Microphone Location Program, a first-order measure of the stability of the equation system was indicated by a matrix 'conditioning' number.

Raman study of high temperature insulator-insulator transition in Ba2Co9O14

NASA Astrophysics Data System (ADS)

Zaghrioui, M.; Delorme, F.; Chen, C.; Camara, N. R.; Giovannelli, F.

2018-05-01

The insulator-insulator transition, at Tt = 570 K, in layered cobalt oxide Ba2Co9O14 was investigated using Raman scattering technique. High temperature (300-800 K) measurements have evidenced no structural transition occurring at Tt. The obtained results are rather consistent with low to high spin-state transition of Co3+ ions in the Co3O12 octahedral trimer. More precisely, only one cobalt ion located in the central octahedron of the trimer undergoes this transition.

A GPR system for the high-resolution inspection of walls and structures

NASA Astrophysics Data System (ADS)

Manacorda, Guido; Simi, Alessandro; Barsacchi, Giorgio

2014-05-01

Nowadays GPR systems are used in a broad range of applications, including the non-destructive inspection of man-made concrete structures such as pillars and bridge decks. Concrete inspection involves several aspects including: location of reinforced bars in walls and floors, concrete condition assessment, concrete cover detection, etc. These surveys are very demanding as far as the system is concerned, because of the strict requirements in terms of resolution and accuracy. Specifically, a key GPR application concerns the condition assessment of a structure that has undergone rehabilitation (e.g. for the removal of architectural barriers or new openings); in this case, the current practice requires to re-check the stability of the entire structure that includes the identification of the number of rebars in reinforced concrete beams location of pre-tensioned cables and early detection of corrosion. This can be done by verification holes (coring) that is costly and intrusive practice or by using a pachometer, but this tool has a limited field of investigation (up to 7-8 cm from the surface). GPR can instead be a useful investigative tool especially when the surface of the beam is not accessible because it is covered by screed or floor. The need of detecting rebars with diameter in the millimeter range as well as the identification of small cavities and cracks, require the development of GPR antennas featuring linear phase and constant polarization, and capable to radiate a very short pulse (i.e. with a duration in the order of few hundreds of picosecond) with no ring-down in order to achieve a high range resolution. A novel 3 GHz center frequency antenna has been recently developed and tested; it has been found capable of providing a very clear image of the concrete internal structure that helps in locating targets and enables an early detection of damages, thus providing a fast and efficient maintenance of the structure itself. The Authors thank COST for funding COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

Correlations and clustering in wholesale electricity markets

DOE PAGES

Cui, Tianyu; Caravelli, Francesco; Ududec, Cozmin

2017-11-24

We study the structure of locational marginal prices in day-ahead and real-time wholesale electricity markets. In particular, we consider the case of two North American markets and show that the price correlations contain information on the locational structure of the grid. We study various clustering methods and introduce a type of correlation function based on event synchronization for spiky time series, and another based on string correlations of location names provided by the markets. As a result, this allows us to reconstruct aspects of the locational structure of the grid.

Correlations and clustering in wholesale electricity markets

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

Cui, Tianyu; Caravelli, Francesco; Ududec, Cozmin

We study the structure of locational marginal prices in day-ahead and real-time wholesale electricity markets. In particular, we consider the case of two North American markets and show that the price correlations contain information on the locational structure of the grid. We study various clustering methods and introduce a type of correlation function based on event synchronization for spiky time series, and another based on string correlations of location names provided by the markets. As a result, this allows us to reconstruct aspects of the locational structure of the grid.

Correlations and clustering in wholesale electricity markets

NASA Astrophysics Data System (ADS)

Cui, Tianyu; Caravelli, Francesco; Ududec, Cozmin

2018-02-01

We study the structure of locational marginal prices in day-ahead and real-time wholesale electricity markets. In particular, we consider the case of two North American markets and show that the price correlations contain information on the locational structure of the grid. We study various clustering methods and introduce a type of correlation function based on event synchronization for spiky time series, and another based on string correlations of location names provided by the markets. This allows us to reconstruct aspects of the locational structure of the grid.

Mitochondrial DNA variation in natural populations of endangered Indian feather-back fish, Chitala chitala.

PubMed

Mandal, Anup; Mohindra, Vindhya; Singh, Rajeev Kumar; Punia, Peyush; Singh, Ajay Kumar; Lal, Kuldeep Kumar

2012-02-01

Genetic variation at mitochondrial cytochrome b (cyt b) and D-loop region reveals the evidence of population sub-structuring in Indian populations of highly endangered primitive feather-back fish Chitala chitala. Samples collected through commercial catches from eight riverine populations from different geographical locations of India were analyzed for cyt b region (307 bp) and D-loop region (636-716 bp). The sequences of the both the mitochondrial regions revealed high haplotype diversity and low nucleotide diversity. The patterns of genetic diversity, haplotypes networks clearly indicated two distinct mitochondrial lineages and mismatch distribution strongly suggest a historical influence on the genetic structure of C. chitala populations. The baseline information on genetic variation and the evidence of population sub-structuring generated from this study would be useful for planning effective strategies for conservation and rehabilitation of this highly endangered species.

High Resolution Three-Dimensional MR Imaging of the Skull Base: Compartments, Boundaries, and Critical Structures.

PubMed

Blitz, Ari Meir; Aygun, Nafi; Herzka, Daniel A; Ishii, Masaru; Gallia, Gary L

2017-01-01

High-resolution 3D MRI of the skull base allows for a more detailed and accurate assessment of normal anatomic structures as well as the location and extent of skull base pathologies than has previously been possible. This article describes the techniques employed for high-resolution skull base MRI including pre- and post-contrast constructive interference in the steady state (CISS) imaging and their utility for evaluation of the many small structures of the skull base, focusing on those regions and concepts most pertinent to localization of cranial nerve palsies and in providing pre-operative guidance and post-operative assessment. The concept of skull base compartments as a means of conceptualizing the various layers of the skull base and their importance in assessment of masses of the skull base is discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

Genetic structure of the carnivorous plant Pinguicula moranensis (Lentibulariaceae) on the transvolcanic Mexican belt.

PubMed

Alcalá, Raúl E; Domínguez, César A

2012-06-01

Most species of Pinguicula present a montane distribution with populations located at high altitudes. In this context, we proposed that populations of Pinguicula species could be genetically differentiated even at a local scale. This study supported that prediction, as a RAPD-based analysis of molecular variance revealed a high degree of genetic structure (Φ (st) = 0.157, P = 0.001) and low gene flow (Nm = 1.0) among four central populations of Pinguicula moranensis in Mexico, with a maximum geographic separation of about 140 km. The four populations also exhibited high levels of genetic diversity (mean Nei's genetic diversity = 0.3716; % polymorphism = 95.45%). The evolutionary implications of the genetic structure found in P. moranensis for other species in the genus are discussed in the context of the naturally fragmented distribution and a set of life history traits shared by most Pinguicula species that could promote geographic isolation and limited gene flow.

Polycrystalline silicon thin-film transistors with location-controlled crystal grains fabricated by excimer laser crystallization

NASA Astrophysics Data System (ADS)

Tsai, Chun-Chien; Lee, Yao-Jen; Chiang, Ko-Yu; Wang, Jyh-Liang; Lee, I.-Che; Chen, Hsu-Hsin; Wei, Kai-Fang; Chang, Ting-Kuo; Chen, Bo-Ting; Cheng, Huang-Chung

2007-11-01

In this paper, location-controlled silicon crystal grains are fabricated by the excimer laser crystallization method which employs amorphous silicon spacer structure and prepatterned thin films. The amorphous silicon spacer in nanometer-sized width formed using spacer technology is served as seed crystal to artificially control superlateral growth phenomenon during excimer laser irradiation. An array of 1.8-μm-sized disklike silicon grains is formed, and the n-channel thin-film transistors whose channels located inside the artificially-controlled crystal grains exhibit higher performance of field-effect-mobility reaching 308cm2/Vs as compared with the conventional ones. This position-manipulated silicon grains are essential to high-performance and good uniformity devices.

Effect of multi-layer thermal insulation thickness and location on the hypervelocity impact response of dual-wall structures

NASA Astrophysics Data System (ADS)

Schonberg, William P.

Traditional perforation-resistant wall design for long-duration spacecraft consists of a "bumper" that is placed a small distance away from the main "pressure wall" of a spacecraft compartment or module. This concept has been studied extensively as a means of reducing the perforation threat of hypervelocity projectiles such as meteoroids and orbital debris. If a dual-wall system is employed on an earth-orbiting spacecraft, then a blanket of multi-layer insulation (MLI) will typically be included within the dual-wall system for thermal protection purposes. This paper presents the results of an experimental study in which aluminum dual-wall structures were tested under a variety of high-speed impact conditions to study the effect of MLI thickness and location on perforation resistance. The results presented consist of test-by-test comparisons of the damage sustained by similar dual-wall systems with blanket MLI of various thicknesses and at various locations within the dual-wall systems under similar impact loading conditions. The analyses performed revealed that the placement of the MLI had a significant effect on the ballistic limit of the dual-wall structures considered while reducing the thickness of the MLI by as much as 1/3 did not.

Localization of an NH2-Terminal Disease-Causing Mutation Hotspot to the “Clamp” Region in the Three-Dimensional Structure of the Cardiac Ryanodine Receptor

PubMed Central

Wang, Ruiwu; Chen, Wenqian; Cai, Shitian; Zhang, Jing; Bolstad, Jeff; Wagenknecht, Terence; Liu, Zheng; Chen, S. R. Wayne

2009-01-01

A region between residues 414 and 466 in the cardiac ryanodine receptor (RyR2) harbors more than half of the known NH2-terminal mutations associated with cardiac arrhythmias and sudden death. To gain insight into the structural basis of this NH2-terminal mutation hotspot, we have determined its location in the three-dimensional structure of RyR2. Green fluorescent protein (GFP), used as a structural marker, was inserted into the middle of this mutation hotspot after Ser-437 in the RyR2 sequence. The resultant GFP-RyR2 fusion protein, RyR2S437-GFP, was expressed in HEK293 cells and characterized using Ca2+ release, [3H]ryanodine binding, and single cell Ca2+ imaging studies. These functional analyses revealed that RyR2S437-GFP forms a caffeine-and ryanodine-sensitive Ca2+ release channel that possesses Ca2+- and caffeine-dependence of activation indistinguishable from that of wild type (wt) RyR2. HEK293 cells expressing RyR2S437-GFP displayed a propensity for store-overload induced Ca2+ release similar to that in cells expressing RyR2-wt. The three-dimensional structure of the purified RyR2S437-GFP was reconstructed using cryo-electron microscopy and single particle image processing. Subtraction of the three-dimensional reconstructions of RyR2-wt and RyR2S437-GFP revealed the location of the inserted GFP, and hence the NH2-terminal mutation hotspot, in a region between domains 5 and 9 in the clamp-shaped structure. This location is close to a previously mapped central disease-causing mutation site located in a region between domains 5 and 6. These results, together with findings from previous studies, suggest that the proposed interactions between the NH2-terminal and central regions of RyR2 are likely to take place between domains 5 and 6, and that the clamp-shaped structure, which shows substantial conformational differences between the closed and open states, is highly susceptible to disease-causing mutations. PMID:17452324

Experimental high gradient testing of a 17.1 GHz photonic band-gap accelerator structure

DOE PAGES

Munroe, Brian J.; Zhang, JieXi; Xu, Haoran; ...

2016-03-29

In this paper, we report the design, fabrication, and high gradient testing of a 17.1 GHz photonic band-gap (PBG) accelerator structure. Photonic band-gap (PBG) structures are promising candidates for electron accelerators capable of high-gradient operation because they have the inherent damping of high order modes required to avoid beam breakup instabilities. The 17.1 GHz PBG structure tested was a single cell structure composed of a triangular array of round copper rods of radius 1.45 mm spaced by 8.05 mm. The test assembly consisted of the test PBG cell located between conventional (pillbox) input and output cells, with input power ofmore » up to 4 MW from a klystron supplied via a TM 01 mode launcher. Breakdown at high gradient was observed by diagnostics including reflected power, downstream and upstream current monitors and visible light emission. The testing procedure was first benchmarked with a conventional disc-loaded waveguide structure, which reached a gradient of 87 MV=m at a breakdown probability of 1.19 × 10 –1 per pulse per meter. The PBG structure was tested with 100 ns pulses at gradient levels of less than 90 MV=m in order to limit the surface temperature rise to 120 K. The PBG structure reached up to 89 MV=m at a breakdown probability of 1.09 × 10 –1 per pulse per meter. These test results show that a PBG structure can simultaneously operate at high gradients and low breakdown probability, while also providing wakefield damping.« less

Fatigue of titanium alloys in a supersonic-cruise airplane environment

NASA Technical Reports Server (NTRS)

Imig, L. A.

1976-01-01

The test programs conducted by several aerospace companies and NASA, summarized in this paper, studied several titanium materials previously identified as having high potential for application to supersonic cruise airplane structures. These studies demonstrate that the temperature (560 K) by itself produced no significant degradation of the materials. However, the fatigue resistance of titanium-alloy structures, in which thermal and loading effects are combined, has been studied insufficiently. The predominant topic for future study of fatigue problems in Mach 3 structures should be the influences of thermal stress particularly, the effects of thermal stress on failure location.

Morphometric analysis of astrocytes in brainstem respiratory regions.

PubMed

Sheikhbahaei, Shahriar; Morris, Brian; Collina, Jared; Anjum, Sommer; Znati, Sami; Gamarra, Julio; Zhang, Ruli; Gourine, Alexander V; Smith, Jeffrey C

2018-06-11

Astrocytes, the most abundant and structurally complex glial cells of the central nervous system, are proposed to play an important role in modulating the activities of neuronal networks, including respiratory rhythm-generating circuits of the preBötzinger complex (preBötC) located in the ventrolateral medulla of the brainstem. However, structural properties of astrocytes residing within different brainstem regions are unknown. In this study astrocytes in the preBötC, an intermediate reticular formation (IRF) region with respiratory-related function, and a region of the nucleus tractus solitarius (NTS) in adult rats were reconstructed and their morphological features were compared. Detailed morphological analysis revealed that preBötC astrocytes are structurally more complex than those residing within the functionally distinct neighboring IRF region, or the NTS, located at the dorsal aspect of the medulla oblongata. Structural analyses of the brainstem microvasculature indicated no significant regional differences in vascular properties. We hypothesize that high morphological complexity of preBötC astrocytes reflects their functional role in providing structural/metabolic support and modulation of the key neuronal circuits essential for breathing, as well as constraints imposed by arrangements of associated neurons and/or other local structural features of the brainstem parenchyma. This article is protected by copyright. All rights reserved. © 2018 Wiley Periodicals, Inc.

Structure-based Insights into the Catalytic Power and Conformational Dexterity of Peroxiredoxins

PubMed Central

Hall, Andrea; Nelson, Kimberly; Poole, Leslie B.

2011-01-01

Abstract Peroxiredoxins (Prxs), some of nature's dominant peroxidases, use a conserved Cys residue to reduce peroxides. They are highly expressed in organisms from all kingdoms, and in eukaryotes they participate in hydrogen peroxide signaling. Seventy-two Prx structures have been determined that cover much of the diversity of the family. We review here the current knowledge and show that Prxs can be effectively classified by a structural/evolutionary organization into six subfamilies followed by specification of a 1-Cys or 2-Cys mechanism, and for 2-Cys Prxs, the structural location of the resolving Cys. We visualize the varied catalytic structural transitions and highlight how they differ depending on the location of the resolving Cys. We also review new insights into the question of how Prxs are such effective catalysts: the enzyme activates not only the conserved Cys thiolate but also the peroxide substrate. Moreover, the hydrogen-bonding network created by the four residues conserved in all Prx active sites stabilizes the transition state of the peroxidatic SN2 displacement reaction. Strict conservation of the peroxidatic active site along with the variation in structural transitions provides a fascinating picture of how the diverse Prxs function to break down peroxide substrates rapidly. Antioxid. Redox Signal. 15, 795–815. PMID:20969484

Identify Structural Flaw Location and Type with an Inverse Algorithm of Resonance Inspection

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

Xu, Wei; Lai, Canhai; Sun, Xin

To evaluate the fitness-for-service of a structural component and to quantify its remaining useful life, aging and service-induced structural flaws must be quantitatively determined in service or during scheduled maintenance shutdowns. Resonance inspection (RI), a non-destructive evaluation (NDE) technique, distinguishes the anomalous parts from the good parts based on changes in the natural frequency spectra. Known for its numerous advantages, i.e., low inspection cost, high testing speed, and broad applicability to complex structures, RI has been widely used in the automobile industry for quality inspection. However, compared to other contemporary direct visualization-based NDE methods, a more widespread application of RImore » faces a fundamental challenge because such technology is unable to quantify the flaw details, e.g. location, dimensions, and types. In this study, the applicability of a maximum correlation-based inverse RI algorithm developed by the authors is further studied for various flaw cases. It is demonstrated that a variety of common structural flaws, i.e. stiffness degradation, voids, and cracks, can be accurately retrieved by this algorithm even when multiple different types of flaws coexist. The quantitative relations between the damage identification results and the flaw characteristics are also developed to assist the evaluation of the actual state of health of the engineering structures.« less

Why are some plant-pollinator networks more nested than others?

PubMed

Song, Chuliang; Rohr, Rudolf P; Saavedra, Serguei

2017-10-01

Empirical studies have found that the mutualistic interactions forming the structure of plant-pollinator networks are typically more nested than expected by chance alone. Additionally, theoretical studies have shown a positive association between the nested structure of mutualistic networks and community persistence. Yet, it has been shown that some plant-pollinator networks may be more nested than others, raising the interesting question of which factors are responsible for such enhanced nested structure. It has been argued that ordered network structures may increase the persistence of ecological communities under less predictable environments. This suggests that nested structures of plant-pollinator networks could be more advantageous under highly seasonal environments. While several studies have investigated the link between nestedness and various environmental variables, unfortunately, there has been no unified answer to validate these predictions. Here, we move from the problem of describing network structures to the problem of comparing network structures. We develop comparative statistics, and apply them to investigate the association between the nested structure of 59 plant-pollinator networks and the temperature seasonality present in their locations. We demonstrate that higher levels of nestedness are associated with a higher temperature seasonality. We show that the previous lack of agreement came from an extended practice of using standardized measures of nestedness that cannot be compared across different networks. Importantly, our observations complement theory showing that more nested network structures can increase the range of environmental conditions compatible with species coexistence in mutualistic systems, also known as structural stability. This increase in nestedness should be more advantageous and occur more often in locations subject to random environmental perturbations, which could be driven by highly changing or seasonal environments. This synthesis of theory and observations could prove relevant for a better understanding of the ecological processes driving the assembly and persistence of ecological communities. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

On singular cases in the design derivative of Green's functional

NASA Technical Reports Server (NTRS)

Reiss, Robert

1987-01-01

The author's prior development of a general abstract representation for the design sensitivities of Green's functional for linear structural systems is extended to the case where the structural stiffness vanishes at an internal location. This situation often occurs in the optimal design of structures. Most optimality criteria require that optimally designed beams be statically determinate. For clamped-pinned beams, for example, this is possible only if the flexural stiffness vanishes at some intermediate location. The Green's function for such structures depends upon the stiffness and the location where it vanishes. A precise representation for Green's function's sensitivity to the location of vanishing stiffness is presented for beams and axisymmetric plates.

Controls on mineralisation in the Sierra Foothills gold province, central California, USA: A GIS-based reconnaissance prospectivity analysis

USGS Publications Warehouse

Bierlein, F.P.; Northover, H.J.; Groves, D.I.; Goldfarb, R.J.; Marsh, E.E.

2008-01-01

The assessment of spatial relationships between the location, abundance and size of orogenic-gold deposits in the highly endowed Sierra Foothills gold province in California, via the combination of field studies and a GIS-based analysis, illustrates the power of such an approach to the characterisation of important parameters of mineral systems, and the prediction of districts likely to host economic mineralisation. Regional- to deposit-scale reconnaissance mapping suggests that deposition of gold-bearing quartz veins occurred in second- and third-order, east-over-west thrusts during regional east - west compression and right-lateral transpression. At the district-scale, significant zones of mineralisation correspond with such transpressional reactivation zones and dilational jogs that developed during the Late Jurassic - Early Cretaceous along the misaligned segments of first-order faults throughout the Sierra Nevada Foothills Metamorphic Belt. Field-based observations and interpretation of GIS data (including solid geology, structural elements, deposit locations, magnetics, gravity) also highlight the importance of structural permeability contrasts, rheological gradients, and variations in fault orientation for localising mineralisation. Although this approach confirms empirical findings and produces promising results at the province scale, enhanced geological, structural, geophysical and geochronological data density is required to generate regionally consistent, high-quality input layers that improve predictive targeting at the goldfield to deposit-scale.

Structure of mangrove meiofaunal assemblages associated with local sediment conditions in subtropical eastern australia

NASA Astrophysics Data System (ADS)

Abdullah, Maizah M.; Lee, S. Y.

2017-11-01

Meiofauna are ubiquitous but poorly-studied components of soft-bottom marine habitats around the world, including mangroves. The dynamic environmental conditions and heterogeneous sediments of mangroves present challenges to understanding the structure of mangrove meiofaunal assemblages at various spatial and temporal scales. In this study, we investigated the meiofaunal assemblage structure of sediments colonised by three mangrove species, namely, Avicennia marina, Rhizophora stylosa and Aegiceras corniculatum, at three locations in subtropical eastern Australia. Spatial and temporal variations were tested by sampling at the three mangrove locations (i.e. Tallebudgera, Currumbin and Terranora) in autumn, with samplings repeated at Tallebudgera at two other times broadly representing during dry/cool winter and wet/hot summer seasons. We examined the variability of the sediment environments within each of the different mangrove species, and investigated how meiofaunal assemblages would respond to the particular changes in their habitats to result in differences in assemblage structure between and within sites. Total meiofaunal density was highest in Tallebudgera and Currumbin and lowest in Terranora (mean density of 424, 393 and 239 ind.10 cm-2, respectively). In Tallebudgera, the density was higher in winter and summer (mean density of 546 and 530 ind.10 cm-2, respectively). The meiofaunal assemblage in this study shows a trend and association with the environmental variables. High availability of food proxies such phaeopigments, Chl a or TOC, with moderate tannin content and appropriate habitat structure (sediment particle size, belowground root biomass and/or moisture content provide the best condition for the meiofauna to achieve the highest density. However, given the complex dynamic habitats and the spatial heterogeneity of the mangrove environments across different locations and seasons, no clear generalization could be made regarding the key environmental variables that predominantly shape the meiofaunal assemblages' structure.

Human cell structure-driven model construction for predicting protein subcellular location from biological images.

PubMed

Shao, Wei; Liu, Mingxia; Zhang, Daoqiang

2016-01-01

The systematic study of subcellular location pattern is very important for fully characterizing the human proteome. Nowadays, with the great advances in automated microscopic imaging, accurate bioimage-based classification methods to predict protein subcellular locations are highly desired. All existing models were constructed on the independent parallel hypothesis, where the cellular component classes are positioned independently in a multi-class classification engine. The important structural information of cellular compartments is missed. To deal with this problem for developing more accurate models, we proposed a novel cell structure-driven classifier construction approach (SC-PSorter) by employing the prior biological structural information in the learning model. Specifically, the structural relationship among the cellular components is reflected by a new codeword matrix under the error correcting output coding framework. Then, we construct multiple SC-PSorter-based classifiers corresponding to the columns of the error correcting output coding codeword matrix using a multi-kernel support vector machine classification approach. Finally, we perform the classifier ensemble by combining those multiple SC-PSorter-based classifiers via majority voting. We evaluate our method on a collection of 1636 immunohistochemistry images from the Human Protein Atlas database. The experimental results show that our method achieves an overall accuracy of 89.0%, which is 6.4% higher than the state-of-the-art method. The dataset and code can be downloaded from https://github.com/shaoweinuaa/. dqzhang@nuaa.edu.cn Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Molecular studies on structural changes and oligomerisation of violaxanthin de-epoxidase associated with the pH-dependent activation.

PubMed

Hallin, Erik Ingmar; Hasan, Mahmudul; Guo, Kuo; Åkerlund, Hans-Erik

2016-07-01

Violaxanthin de-epoxidase (VDE) is a conditionally soluble enzyme located in the thylakoid lumen and catalyses the conversion of violaxanthin to antheraxanthin and zeaxanthin, which are located in the thylakoid membrane. These reactions occur when the plant or algae are exposed to saturating light and the zeaxanthin formed is involved in the process of non-photochemical quenching that protects the photosynthetic machinery during stress. Oversaturation by light results in a reduction of the pH inside the thylakoids, which in turn activates VDE and the de-epoxidation of violaxanthin. To elucidate the structural events responsible for the pH-dependent activation of VDE, full length and truncated forms of VDE were studied at different pH using circular dichroism (CD) spectroscopy, crosslinking and small angle X-ray scattering (SAXS). CD spectroscopy showed the formation of α-helical coiled-coil structure, localised in the C-terminal domain. Chemical crosslinking of VDE showed that oligomers were formed at low pH, and suggested that the position of the N-terminal domain is located near the opening of lipocalin-like barrel, where violaxanthin has been predicted to bind. SAXS was used to generate models of monomeric VDE at high pH and also a presumably dimeric structure of VDE at low pH. For the dimer, the best fit suggests that the interaction is dominated by one of the domains, preferably the C-terminal domain due to the lost ability to oligomerise at low pH, shown in earlier studies, and the predicted formation of coiled-coil structure.

Center for Computational Structures Technology

NASA Technical Reports Server (NTRS)

Noor, Ahmed K.; Perry, Ferman W.

1995-01-01

The Center for Computational Structures Technology (CST) is intended to serve as a focal point for the diverse CST research activities. The CST activities include the use of numerical simulation and artificial intelligence methods in modeling, analysis, sensitivity studies, and optimization of flight-vehicle structures. The Center is located at NASA Langley and is an integral part of the School of Engineering and Applied Science of the University of Virginia. The key elements of the Center are: (1) conducting innovative research on advanced topics of CST; (2) acting as pathfinder by demonstrating to the research community what can be done (high-potential, high-risk research); (3) strong collaboration with NASA scientists and researchers from universities and other government laboratories; and (4) rapid dissemination of CST to industry, through integration of industrial personnel into the ongoing research efforts.

Microwave sintering of single plate-shaped articles

DOEpatents

Katz, Joel D.; Blake, Rodger D.

1995-01-01

Apparatus and method for high temperature sintering of plate-shaped articles of alumina, magnesia, silica, yttria, zirconia, and mixtures thereof using microwave radiation. An article is placed within a sintering structure located within a sintering container which is placed in a microwave cavity for heating. The rates at which heating and cooling take place is controlled.

Does Participation in Extracurricular Activities Impact Student Achievement?

ERIC Educational Resources Information Center

Abruzzo, Kristen J.; Lenis, Cristina; Romero, Yansi V.; Maser, Kevin J.; Morote, Elsa-Sofia

2016-01-01

This study was conducted in two high schools located in suburban, Long Island, New York, with a predominantly white population. The respondents in this study consisted of 234, 11th grade students. The data was analyzed using the structural equation model. Findings show that there is a positive correlation between percent of participation in…

Soil microbial community response to corn stover harvesting under rain-fed, no-till conditions at multiple U.S. locations

USDA-ARS?s Scientific Manuscript database

Harvesting of corn stover for cellulosic ethanol production must be balanced with the requirement for returning plant residues to agricultural fields to maintain soil structure, fertility, crop protection, and other ecosystem services. High rates of corn stover removal can be associated with decrea...

Locating the source of spreading in temporal networks

NASA Astrophysics Data System (ADS)

Huang, Qiangjuan; Zhao, Chengli; Zhang, Xue; Yi, Dongyun

2017-02-01

The topological structure of many real networks changes with time. Thus, locating the sources of a temporal network is a creative and challenging problem, as the enormous size of many real networks makes it unfeasible to observe the state of all nodes. In this paper, we propose an algorithm to solve this problem, named the backward temporal diffusion process. The proposed algorithm calculates the shortest temporal distance to locate the transmission source. We assume that the spreading process can be modeled as a simple diffusion process and by consensus dynamics. To improve the location accuracy, we also adopt four strategies to select which nodes should be observed by ranking their importance in the temporal network. Our paper proposes a highly accurate method for locating the source in temporal networks and is, to the best of our knowledge, a frontier work in this field. Moreover, our framework has important significance for controlling the transmission of diseases or rumors and formulating immediate immunization strategies.

The Use of Convolutional Neural Network in Relating Precipitation to Circulation

NASA Astrophysics Data System (ADS)

Pan, B.; Hsu, K. L.; AghaKouchak, A.; Sorooshian, S.

2017-12-01

Precipitation prediction in dynamical weather and climate models depends on 1) the predictability of pressure or geopotential height for the forecasting period and 2) the successive work of interpreting the pressure field in terms of precipitation events. The later task is represented as parameterization schemes in numerical models, where detailed computing inevitably blurs the hidden cause-and-effect relationship in precipitation generation. The "big data" provided by numerical simulation, reanalysis and observation networks requires better causation analysis for people to digest and realize their use. While classic synoptical analysis methods are very-often insufficient for spatially distributed high dimensional data, a Convolutional Neural Network(CNN) is developed here to directly relate precipitation with circulation. Case study carried over west coast United States during boreal winter showed that CNN can locate and capture key pressure zones of different structures to project precipitation spatial distribution with high accuracy across hourly to monthly scales. This direct connection between atmospheric circulation and precipitation offers a probe for attributing precipitation to the coverage, location, intensity and spatial structure of characteristic pressure zones, which can be used for model diagnosis and improvement.

Third Generation RLV Structural Seal Development Programs at NASA GRC

NASA Technical Reports Server (NTRS)

Dunlap, Patrick H., Jr.; Steinetz, Bruce M.; DeMange, Jeffrey J.

2002-01-01

NASA GRC's work on high temperature structural seal development began in the late 1980's and early 1990's under the NASP (National Aero-Space Plane) project. Bruce Steinetz led the in-house propulsion system seal development program and oversaw industry efforts for propulsion system and airframe seal development for this vehicle. a propulsion system seal location in the NASP engine is shown. The seals were located along the edge of a movable panel in the engine to seal the gap between the panel and adjacent engine sidewalls. More recently, we worked with Rocketdyne on high temperature seals for the linear aerospike engine ramps. In applications such as the former X-33 program, multiple aerospike engine modules would be installed side by side on the vehicle. Seals are required in between adjacent engine modules along the edges and base of the engines. The seals have to withstand the extreme temperatures produced byt he thrusters at the top of the ramps while accommodating large deflections between adjacent ramps. We came up with several promising seal concepts for this application and shared them with Rocketdyne.

Controlled removal of ceramic surfaces with combination of ions implantation and ultrasonic energy

DOEpatents

Boatner, Lynn A.; Rankin, Janet; Thevenard, Paul; Romana, Laurence J.

1995-01-01

A method for tailoring or patterning the surface of ceramic articles is provided by implanting ions to predetermined depth into the ceramic material at a selected surface location with the ions being implanted at a fluence and energy adequate to damage the lattice structure of the ceramic material for bi-axially straining near-surface regions of the ceramic material to the predetermined depth. The resulting metastable near-surface regions of the ceramic material are then contacted with energy pulses from collapsing, ultrasonically-generated cavitation bubbles in a liquid medium for removing to a selected depth the ion-damaged near-surface regions containing the bi-axially strained lattice structure from the ceramic body. Additional patterning of the selected surface location on the ceramic body is provided by implanting a high fluence of high-energy, relatively-light ions at selected surface sites for relaxing the bi-axial strain in the near-surface regions defined by these sites and thereby preventing the removal of such ion-implanted sites by the energy pulses from the collapsing ultrasonic cavitation bubbles.

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

Wojcik, Roza; Webb, Ian K.; Deng, Liulin

Understanding the biological mechanisms related to lipids and glycolipids is challenging due to the vast number of possible isomers. Mass spectrometry (MS) measurements are currently the dominant approach for studying and providing detailed information on lipid and glycolipid structures. However, difficulties in distinguishing many structural isomers (e.g. distinct acyl chain positions, double bond locations, as well as glycan isomers) inhibit the understanding of their biological roles. Here we utilized ultra-high resolution ion mobility spectrometry (IMS) separations based upon the use of traveling waves in a serpentine long path length multi-pass Structures for Lossless Manipulations (SLIM) to enhance isomer resolution. Themore » multi-pass arrangement allowed separations ranging from ~16 m (1 pass) to ~470 m (32 passes) to be investigated for the distinction of lipids and glycolipids with extremely small structural differences. Lastly, these ultra-high resolution SLIM IMS-MS analyses provide a foundation for exploring and better understanding isomer specific biological and disease processes.« less

Crystal structures of two Bordetella pertussis periplasmic receptors contribute to defining a novel pyroglutamic acid binding DctP subfamily.

PubMed

Rucktooa, Prakash; Antoine, Rudy; Herrou, Julien; Huvent, Isabelle; Locht, Camille; Jacob-Dubuisson, Françoise; Villeret, Vincent; Bompard, Coralie

2007-06-29

Gram-negative bacteria have developed several different transport systems for solute uptake. One of these, the tripartite ATP independent periplasmic transport system (TRAP-T), makes use of an extracytoplasmic solute receptor (ESR) which captures specific solutes with high affinity and transfers them to their partner permease complex located in the bacterial inner membrane. We hereby report the structures of DctP6 and DctP7, two such ESRs from Bordetella pertussis. These two proteins display a high degree of sequence and structural similarity and possess the "Venus flytrap" fold characteristic of ESRs, comprising two globular alpha/beta domains hinged together to form a ligand binding cleft. DctP6 and DctP7 both show a closed conformation due to the presence of one pyroglutamic acid molecule bound by highly conserved residues in their respective ligand binding sites. BLAST analyses have revealed that the DctP6 and DctP7 residues involved in ligand binding are strictly present in a number of predicted TRAP-T ESRs from other bacteria. In most cases, the genes encoding these TRAP-T systems are located in the vicinity of a gene coding for a pyroglutamic acid metabolising enzyme. Both the high degree of conservation of these ligand binding residues and the genomic context of these TRAP-T-coding operons in a number of bacterial species, suggest that DctP6 and DctP7 constitute the prototypes of a novel TRAP-T DctP subfamily involved in pyroglutamic acid transport.

Localizing Submarine Earthquakes by Listening to the Water Reverberations

NASA Astrophysics Data System (ADS)

Castillo, J.; Zhan, Z.; Wu, W.

2017-12-01

Mid-Ocean Ridge (MOR) earthquakes generally occur far from any land based station and are of moderate magnitude, making it complicated to detect and in most cases, locate accurately. This limits our understanding of how MOR normal and transform faults move and the manner in which they slip. Different from continental events, seismic records from earthquakes occurring beneath the ocean floor show complex reverberations caused by P-wave energy trapped in the water column that are highly dependent of the source location and the efficiency to which energy propagated to the near-source surface. These later arrivals are commonly considered to be only a nuisance as they might sometimes interfere with the primary arrivals. However, in this study, we take advantage of the wavefield's high sensitivity to small changes in the seafloor topography and the present-day availability of worldwide multi-beam bathymetry to relocate submarine earthquakes by modeling these water column reverberations in teleseismic signals. Using a three-dimensional hybrid method for modeling body wave arrivals, we demonstrate that an accurate hypocentral location of a submarine earthquake (<5 km) can be achieved if the structural complexities near the source region are appropriately accounted for. This presents a novel way of studying earthquake source properties and will serve as a means to explore the influence of physical fault structure on the seismic behavior of transform faults.

A new look at a polar crown cavity as observed by SDO/AIA. Structure and dynamics

NASA Astrophysics Data System (ADS)

Régnier, S.; Walsh, R. W.; Alexander, C. E.

2011-09-01

Context. The Solar Dynamics Observatory (SDO) was launched in February 2010 and is now providing an unprecedented view of the solar activity at high spatial resolution and high cadence covering a broad range of temperature layers of the atmosphere. Aims: We aim at defining the structure of a polar crown cavity and describing its evolution during the erupting process. Methods: We use the high-cadence time series of SDO/AIA observations at 304 Å (50 000 K) and 171 Å (0.6 MK) to determine the structure of the polar crown cavity and its associated plasma, as well as the evolution of the cavity during the different phases of the eruption. We report on the observations recorded on 13 June 2010 located on the north-west limb. Results: We observe coronal plasma shaped by magnetic field lines with a negative curvature (U-shape) sitting at the bottom of a cavity. The cavity is located just above the polar crown filament material. We thus observe the inner part of the cavity above the filament as depicted in the classical three part coronal mass ejection (CME) model composed of a filament, a cavity, and a CME front. The filament (in this case a polar crown filament) is part of the cavity, and it makes a continuous structuring from the filament to the CME front depicted by concentric ellipses (in a 2D cartoon). Conclusions: We propose to define a polar crown cavity as a density depletion sitting above denser polar crown filament plasma drained down the cavity by gravity. As part of the polar crown filament, plasma at different temperatures (ranging from 50 000 K to 0.6 MK) is observed at the same location on the cavity dips and sustained by a competition between the gravity and the curvature of magnetic field lines. The eruption of the polar crown cavity as a solid body can be decomposed into two phases: a slow rise at a speed of 0.6 km s-1 and an acceleration phase at a mean speed of 25 km s-1. Two movies are only available at http://www.aanda.org

High Resolution Vp and Vp/Vs Local Earthquake Tomography of the Val d'Agri Region (Southern Apennines, Italy).

NASA Astrophysics Data System (ADS)

Improta, L.; Bagh, S.; De Gori, P.; Pastori, M.; Piccinini, D.; Valoroso, L.; Anselmi, M.; Buttinelli, M.; Chiarabba, C.

2015-12-01

The Val d'Agri (VA) Quaternary basin in the southern Apennines extensional belt hosts the largest oilfield in onshore Europe and normal-fault systems with high (up to M7) seismogenic potential. Frequent small-magnitude swarms related to both active crustal extension and anthropogenic activity have occurred in the region. Causal factors for induced seismicity are a water impoundment with severe seasonal oscillations and a high-rate wastewater injection well. We analyzed around 1200 earthquakes (ML<3.3) occurred in the VA and surrounding regions between 2001-2014. We integrated waveforms recorded at 46 seismic stations belonging to 3 different networks: a dense temporary network installed by INGV in 2005-2006, the permanent national network of INGV, and the trigger-mode monitoring network managed by the local operator ENI petroleum company. We used local earthquake tomography to investigate static and transient features of the crustal velocity structure and to accurately locate earthquakes. Vp and Vp/Vs models are parameterized by a 3x3x2 km spacing and well resolved down to about 12 km depth. The complex Vp model illuminates broad antiformal structures corresponding to wide ramp-anticlines involving Mesozoic carbonates of the Apulia hydrocarbon reservoir, and NW-SE trending low Vp regions related to thrust-sheet-top clastic basins. The VA basin corresponds to shallow low-Vp region. Focal mechanisms show normal faulting kinematics with minor strike slip solutions in agreement with the local extensional regime. Earthquake locations and focal solutions depict shallow (< 5 km depth) E-dipping extensional structures beneath the artificial lake located in the southern sector of the basin, and along the western margin of the VA. A few swarms define relatively deep transfer structures accommodating the differential extension between main normal faults. The spatio-temporal distribution of around 220 events correlates with wastewater disposal activity, illuminating a NE-dipping fault between 2-5 km depth in the carbonate reservoir. The fault measures 5 km along dip and corresponds to a pre-existing thrust fault favorably oriented with respect to the local extensional field.

Global Vulnerability Assessment in Santa María Tixmadeje, Estado de México, México

NASA Astrophysics Data System (ADS)

Monroy Salazar, S.; Novelo-Casanova, D. A.

2010-12-01

Santa María Tixmadejé (SMT), Estado de México, Mexico is a town located very close to the Acambay-Tixmadejé fault. This fault is located in the middle of the Trans Volcanic Belt in the center of the Mexican territory and generated a large seismic event in 1912 with magnitude 6.9 which combined with the local vulnerability, caused a disaster. In this work we measure the different vulnerabilities of the SMT community: structural, economical, social and educational. In addition, we determinate the total vulnerability, by summing all estimated vulnerabilities, for the critical facilities identified in this town. Vulnerability was determined using the methodology proposed by National Oceanic Atmospheric Administration (NOAA) and by Disaster Prevention National Center (CENAPRED). Besides, we considered a minimum sample statistically significant of the total houses with a random sampling for our survey. Our results indicate that 50% of the critical facilities have high and very high and the other 50% between low and moderate level of total vulnerability. The results for independent vulnerabilities are as follows: (1) Near to 75% of the community has high and very high level of social vulnerability and the range for the another 25% is between low and moderate; (2) About 43% of the community has high and very high economical vulnerability and 57% low and moderate; (3) Approximately 38% of the population has high and very high educational vulnerability. The 62% present low and moderate vulnerability; and (4) About 42% of the community has very high structural vulnerability and 58% between low and moderate.

Earthquake location in island arcs

USGS Publications Warehouse

Engdahl, E.R.; Dewey, J.W.; Fujita, K.

1982-01-01

A comprehensive data set of selected teleseismic P-wave arrivals and local-network P- and S-wave arrivals from large earthquakes occurring at all depths within a small section of the central Aleutians is used to examine the general problem of earthquake location in island arcs. Reference hypocenters for this special data set are determined for shallow earthquakes from local-network data and for deep earthquakes from combined local and teleseismic data by joint inversion for structure and location. The high-velocity lithospheric slab beneath the central Aleutians may displace hypocenters that are located using spherically symmetric Earth models; the amount of displacement depends on the position of the earthquakes with respect to the slab and on whether local or teleseismic data are used to locate the earthquakes. Hypocenters for trench and intermediate-depth events appear to be minimally biased by the effects of slab structure on rays to teleseismic stations. However, locations of intermediate-depth events based on only local data are systematically displaced southwards, the magnitude of the displacement being proportional to depth. Shallow-focus events along the main thrust zone, although well located using only local-network data, are severely shifted northwards and deeper, with displacements as large as 50 km, by slab effects on teleseismic travel times. Hypocenters determined by a method that utilizes seismic ray tracing through a three-dimensional velocity model of the subduction zone, derived by thermal modeling, are compared to results obtained by the method of joint hypocenter determination (JHD) that formally assumes a laterally homogeneous velocity model over the source region and treats all raypath anomalies as constant station corrections to the travel-time curve. The ray-tracing method has the theoretical advantage that it accounts for variations in travel-time anomalies within a group of events distributed over a sizable region of a dipping, high-velocity lithospheric slab. In application, JHD has the practical advantage that it does not require the specification of a theoretical velocity model for the slab. Considering earthquakes within a 260 km long by 60 km wide section of the Aleutian main thrust zone, our results suggest that the theoretical velocity structure of the slab is presently not sufficiently well known that accurate locations can be obtained independently of locally recorded data. Using a locally recorded earthquake as a calibration event, JHD gave excellent results over the entire section of the main thrust zone here studied, without showing a strong effect that might be attributed to spatially varying source-station anomalies. We also calibrated the ray-tracing method using locally recorded data and obtained results generally similar to those obtained by JHD. ?? 1982.

High-frequency guided ultrasonic waves for hidden defect detection in multi-layered aircraft structures.

PubMed

Masserey, Bernard; Raemy, Christian; Fromme, Paul

2014-09-01

Aerospace structures often contain multi-layered metallic components where hidden defects such as fatigue cracks and localized disbonds can develop, necessitating non-destructive testing. Employing standard wedge transducers, high frequency guided ultrasonic waves that penetrate through the complete thickness were generated in a model structure consisting of two adhesively bonded aluminium plates. Interference occurs between the wave modes during propagation along the structure, resulting in a frequency dependent variation of the energy through the thickness with distance. The wave propagation along the specimen was measured experimentally using a laser interferometer. Good agreement with theoretical predictions and two-dimensional finite element simulations was found. Significant propagation distance with a strong, non-dispersive main wave pulse was achieved. The interaction of the high frequency guided ultrasonic waves with small notches in the aluminium layer facing the sealant and on the bottom surface of the multilayer structure was investigated. Standard pulse-echo measurements were conducted to verify the detection sensitivity and the influence of the stand-off distance predicted from the finite element simulations. The results demonstrated the potential of high frequency guided waves for hidden defect detection at critical and difficult to access locations in aerospace structures from a stand-off distance. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Automated framework for estimation of lung tumor locations in kV-CBCT images for tumor-based patient positioning in stereotactic lung body radiotherapy

NASA Astrophysics Data System (ADS)

Yoshidome, Satoshi; Arimura, Hidetaka; Terashima, Koutarou; Hirakawa, Masakazu; Hirose, Taka-aki; Fukunaga, Junichi; Nakamura, Yasuhiko

2017-03-01

Recently, image-guided radiotherapy (IGRT) systems using kilovolt cone-beam computed tomography (kV-CBCT) images have become more common for highly accurate patient positioning in stereotactic lung body radiotherapy (SLBRT). However, current IGRT procedures are based on bone structures and subjective correction. Therefore, the aim of this study was to evaluate the proposed framework for automated estimation of lung tumor locations in kV-CBCT images for tumor-based patient positioning in SLBRT. Twenty clinical cases are considered, involving solid, pure ground-glass opacity (GGO), mixed GGO, solitary, and non-solitary tumor types. The proposed framework consists of four steps: (1) determination of a search region for tumor location detection in a kV-CBCT image; (2) extraction of a tumor template from a planning CT image; (3) preprocessing for tumor region enhancement (edge and tumor enhancement using a Sobel filter and a blob structure enhancement (BSE) filter, respectively); and (4) tumor location estimation based on a template-matching technique. The location errors in the original, edge-, and tumor-enhanced images were found to be 1.2 ± 0.7 mm, 4.2 ± 8.0 mm, and 2.7 ± 4.6 mm, respectively. The location errors in the original images of solid, pure GGO, mixed GGO, solitary, and non-solitary types of tumors were 1.2 ± 0.7 mm, 1.3 ± 0.9 mm, 0.4 ± 0.6 mm, 1.1 ± 0.8 mm and 1.0 ± 0.7 mm, respectively. These results suggest that the proposed framework is robust as regards automatic estimation of several types of tumor locations in kV-CBCT images for tumor-based patient positioning in SLBRT.

Phylogeography on the rocks: The contribution of current and historical factors in shaping the genetic structure of Chthamalus montagui (Crustacea, Cirripedia).

PubMed

Pannacciulli, Federica G; Maltagliati, Ferruccio; de Guttry, Christian; Achituv, Yair

2017-01-01

The model marine broadcast-spawner barnacle Chthamalus montagui was investigated to understand its genetic structure and quantify levels of population divergence, and to make inference on historical demography in terms of time of divergence and changes in population size. We collected specimens from rocky shores of the north-east Atlantic Ocean (4 locations), Mediterranean Sea (8) and Black Sea (1). The 312 sequences 537 bp) of the mitochondrial cytochrome c oxidase I allowed to detect 130 haplotypes. High within-location genetic variability was recorded, with haplotype diversity ranging between h = 0.750 and 0.967. Parameters of genetic divergence, haplotype network and Bayesian assignment analysis were consistent in rejecting the hypothesis of panmixia. C. montagui is genetically structured in three geographically discrete populations, which corresponded to north-eastern Atlantic Ocean, western-central Mediterranean Sea, and Aegean Sea-Black Sea. These populations are separated by two main effective barriers to gene flow located at the Almeria-Oran Front and in correspondence of the Cyclades Islands. According to the 'isolation with migration' model, adjacent population pairs diverged during the early to middle Pleistocene transition, a period in which geological events provoked significant changes in the structure and composition of palaeocommunities. Mismatch distributions, neutrality tests and Bayesian skyline plots showed past population expansions, which started approximately in the Mindel-Riss interglacial, in which ecological conditions were favourable for temperate species and calcium-uptaking marine organisms.

Phylogeography on the rocks: The contribution of current and historical factors in shaping the genetic structure of Chthamalus montagui (Crustacea, Cirripedia)

PubMed Central

Pannacciulli, Federica G.; de Guttry, Christian; Achituv, Yair

2017-01-01

The model marine broadcast-spawner barnacle Chthamalus montagui was investigated to understand its genetic structure and quantify levels of population divergence, and to make inference on historical demography in terms of time of divergence and changes in population size. We collected specimens from rocky shores of the north-east Atlantic Ocean (4 locations), Mediterranean Sea (8) and Black Sea (1). The 312 sequences 537 bp) of the mitochondrial cytochrome c oxidase I allowed to detect 130 haplotypes. High within-location genetic variability was recorded, with haplotype diversity ranging between h = 0.750 and 0.967. Parameters of genetic divergence, haplotype network and Bayesian assignment analysis were consistent in rejecting the hypothesis of panmixia. C. montagui is genetically structured in three geographically discrete populations, which corresponded to north-eastern Atlantic Ocean, western-central Mediterranean Sea, and Aegean Sea-Black Sea. These populations are separated by two main effective barriers to gene flow located at the Almeria-Oran Front and in correspondence of the Cyclades Islands. According to the ‘isolation with migration’ model, adjacent population pairs diverged during the early to middle Pleistocene transition, a period in which geological events provoked significant changes in the structure and composition of palaeocommunities. Mismatch distributions, neutrality tests and Bayesian skyline plots showed past population expansions, which started approximately in the Mindel-Riss interglacial, in which ecological conditions were favourable for temperate species and calcium-uptaking marine organisms. PMID:28594840

Persistent Structures in the Turbulent Boundary Layer

NASA Technical Reports Server (NTRS)

Palumbo, Dan; Chabalko, Chris

2005-01-01

Persistent structures in the turbulent boundary layer are located and analyzed. The data are taken from flight experiments on large commercial aircraft. An interval correlation technique is introduced which is able to locate the structures. The Morlet continuous wavelet is shown to not only locates persistent structures but has the added benefit that the pressure data are decomposed in time and frequency. To better understand how power is apportioned among these structures, a discrete Coiflet wavelet is used to decompose the pressure data into orthogonal frequency bands. Results indicate that some structures persist a great deal longer in the TBL than would be expected. These structure contain significant power and may be a primary source of vibration energy in the airframe.

Three Dimensional Aerosol Climatology over India and the North Indian Ocean

NASA Astrophysics Data System (ADS)

Adams, A.; Zhang, C.

2013-12-01

Numerical models are indispensable tools to study aerosol effects on climate, including both aerosol direct and indirect radiative effects and their role in precipitation. But, agreement among the models has not been achieved, and thus it is not possible to accurately and confidently attain estimates of aerosol effects on climate. The lack of reliable knowledge on global three-dimensional (3D) aerosol climatology has prevented us from assessing the degree to which the disagreement in their aerosol climatic effects may come from differences of aerosol vertical structures in their simulations. To that end, we created a six year, global 3D extinction coefficient dataset for each aerosol species identifiable by the Level 2, Version 3, 5 km Aerosol Profile product from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) as a tool to improve 3D model representations. Here we describe the 3D structure of aerosol in the Middle East, India, and the Northern Indian Ocean and some of the interesting dynamical features responsible for the vertical structure and external mixing of aerosol species. One interesting feature in the 3D structure during boreal summer is a well-defined EC core located 0 - 10°N, 40°E - 90°E (Somalia across the Indian subcontinent), centered at 3 km. This is controlled by a shallow meridional circulation about the core. Additionally, the Somali Low-Level Jet exists at this location, but is usually located below the core (~850 mb). Another interesting feature is a strong EC core located 0 - 15°N, 60°E - 90°E below 0.5 km. Polluted dust (external mixture of dust and smoke) and marine aerosol are collocated in this area with maximum AODs of ~0.5 and ~0.2 respectively. Due to the wind stress over ocean, collocation of aerosol species, altitude, and lack of transport pathway for polluted dust, it is possible that this is an example of aerosol misclassification by the CALIPSO algorithm, probably misclassifying marine aerosol as polluted dust. The origin of much of the polluted dust, the most prominent aerosol species in the region, is the mixing of dust and smoke from Africa. Low-level southerly winds south of 10°N transport smoke northward while northerly winds north of 10°N transport dust southward and upward due to orographic lifting. At their area of convergence, zonal wind transports the now elevated polluted dust eastward toward the Indian subcontinent. Subsidence and monsoon circulation reversal during boreal winter and fall limit vertical and horizontal aerosol transport from the India, particularly in the highly populated and always polluted Indo¬-Gangetic Plain. Polluted dust, polluted continental (non-elevated smoke), and smoke aerosols are confined near the surface and located over high population density areas and known biomass burning locations. Himalayan topography is an obvious barrier for the northward extent of aerosol. However, it also acts to create a meridional circulation limiting the southward extent of aerosol. Although transport pathways and the spatial structure of aerosol are well documented in the 2D sense, understanding the mechanisms controlling the vertical structure in concert with observation of the structure will be a valuable tool in reducing the uncertainty of aerosol effects in model simulations.

High field side launch of RF waves: A new approach to reactor actuators

NASA Astrophysics Data System (ADS)

Wallace, G. M.; Baek, S. G.; Bonoli, P. T.; Faust, I. C.; LaBombard, B. L.; Lin, Y.; Mumgaard, R. T.; Parker, R. R.; Shiraiwa, S.; Vieira, R.; Whyte, D. G.; Wukitch, S. J.

2015-12-01

Launching radio frequency (RF) waves from the high field side (HFS) of a tokamak offers significant advantages over low field side (LFS) launch with respect to both wave physics and plasma material interactions (PMI). For lower hybrid (LH) waves, the higher magnetic field opens the window between wave accessibility (n∥≡c k∥/ω >√{1 -ωpi 2/ω2+ωpe 2/ωce 2 }+ωp e/|ωc e| ) and the condition for strong electron Landau damping (n∥˜√{30 /Te } with Te in keV), allowing LH waves from the HFS to penetrate into the core of a burning plasma, while waves launched from the LFS are restricted to the periphery of the plasma. The lower n∥ of waves absorbed at higher Te yields a higher current drive efficiency as well. In the ion cyclotron range of frequencies (ICRF), HFS launch allows for direct access to the mode conversion layer where mode converted waves absorb strongly on thermal electrons and ions, thus avoiding the generation of energetic minority ion tails. The absence of turbulent heat and particle fluxes on the HFS, particularly in double null configuration, makes it the ideal location to minimize PMI damage to the antenna structure. The quiescent SOL also eliminates the need to couple LH waves across a long distance to the separatrix, as the antenna can be located close to plasma without risking damage to the structure. Improved impurity screening on the HFS will help eliminate the long-standing issues of high Z impurity accumulation with ICRF. Looking toward a fusion reactor, the HFS is the only possible location for a plasma-facing RF antenna that will survive long-term. By integrating the antenna into the blanket module it is possible to improve the tritium breeding ratio compared with an antenna occupying an equatorial port plug. Blanket modules will require remote handling of numerous cooling pipes and electrical connections, and the addition of transmission lines will not substantially increase the level of complexity. The obvious engineering challenges associated with locating antenna structures on the HFS can be overcome if HFS antennas are incorporated in the overall experimental design from the start. The Advanced Divertor and radio frequency eXperiment(ADX) will include LH and ICRF antennas located on the HFS. Compact antenna designs based on proven technologies (e.g. multi-junction and "4-way splitter" antennas) fit within the available space on the HFS of ADX. Field aligned ICRF antennas are also located on the HFS. The ADX vacuum vessel design includes dedicated space for transmission lines, pressure windows, and vacuum feedthrus for accessing the HFS wall.

Simultaneous optimisation of earwig hindwings for flight and folding

PubMed Central

Deiters, Julia; Kowalczyk, Wojciech; Seidl, Tobias

2016-01-01

ABSTRACT Earwig wings are highly foldable structures that lack internal muscles. The behaviour and shape changes of the wings during flight are yet unknown. We assume that they meet a great structural challenge to control the occurring deformations and prevent the wing from collapsing. At the folding structures especially, the wing could easily yield to the pressure. Detailed microscopy studies reveal adaptions in the structure and material which are not relevant for folding purposes. The wing is parted into two structurally different areas with, for example, a different trend or stiffness of the wing veins. The storage of stiff or more flexible material shows critical areas which undergo great changes or stress during flight. We verified this with high-speed video recordings. These reveal the extent of the occurring deformations and their locations, and support our assumptions. The video recordings reveal a dynamical change of a concave flexion line. In the static unfolded state, this flexion line blocks a folding line, so that the wing stays unfolded. However, during flight it extends and blocks a second critical folding line and prevents the wing from collapsing. With these results, more insight in passive wing control, especially within high foldable structures, is gained. PMID:27113958

Preliminary determination of geothermal working area based on Thermal Infrared and Synthetic Aperture Radar (SAR) remote sensing

NASA Astrophysics Data System (ADS)

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

2017-12-01

Remote sensing is one of the methods for geothermal exploration. This method can be used to map the geological structures, manifestations, and predict the geothermal potential area. The results from remote sensing were used as guidance for the next step exploration. Analysis of target in remote sensing is an efficient method to delineate geothermal surface manifestation without direct contact to the object. The study took a place in District Merangin, Jambi Province, Indonesia. The area was selected due to existing of Merangin volcanic complex composed by Mounts Sumbing and Hulunilo with surface geothermal manifestations presented by hot springs and hot pools. The location of surface manifestations could be related with local and regional structures of Great Sumatra Fault. The methods used in this study were included identification of volcanic products, lineament extraction, and lineament density quantification. The objective of this study is to delineate the potential zones for sitting the geothermal working site based on Thermal Infrared and Synthetic Aperture Radar (SAR) sensors. The lineament-related to geological structures, was aimed for high lineament density, is using ALOS - PALSAR (Advanced Land Observing Satellite - The Phased Array type L-band Synthetic Aperture Radar) level 1.1. The Normalized Difference Vegetation Index (NDVI) analysis was used to predict the vegetation condition using Landsat 8 OLI-TIRS (The Operational Land Imager - Thermal Infrared Sensor). The brightness temperature was extracted from TIR band to estimate the surface temperature. Geothermal working area identified based on index overlay method from extracted parameter of remote sensing data was located at the western part of study area (Graho Nyabu area). This location was identified because of the existence of high surface temperature about 30°C, high lineament density about 4 - 4.5 km/km2 and low NDVI values less than 0.3.

Simultaneous growth of pure hyperbranched Zn3As2 structures and long Ga2O3 nanowires.

PubMed

Li, Jianye; Wang, Lung-Shen; Buchholz, D Bruce; Chang, Robert P H

2009-05-01

Through a facile and highly repeatable chemical vapor method, pure three-dimensional hyperbranched Zn(3)As(2) structures and ultralong Ga(2)O(3) nanowires were simultaneously grown with controllable locations in the same experiment. The hyperbranched Zn(3)As(2) consists of cone-shaped submicro-/nanowires and has a single-crystalline tetragonal structure. This is the first report of nano Zn(3)As(2) and hyperbranched Zn(3)As(2) structures. The as-grown Ga(2)O(3) nanowires are monoclinic single crystals. A vapor-solid-solid mechanism is suggested for the growth of the Ga(2)O(3) nanowires, and a vapor-solid mechanism, for the Zn(3)As(2) structures.

Coronal magnetic structure and the latitude and longitude distribution of energetic particles, 1-5 AU

NASA Technical Reports Server (NTRS)

Roelof, E. C.; Mitchell, D. G.

1979-01-01

The relation of the coronal magnetic field structure to the distribution of approximately 1 MeV protons in interplanetary space between 1 and 5 AU is discussed. After ordering the interplanetary data by its estimated coronal emission source location in heliographic coordinates, the multispacecraft measured proton fluxes are compared with coronal magnetic field structure infrared as observed in soft X-ray photographs and potential field calculations. Evidence for the propagation and possible acceleration of solar flare protons on high magnetic loop structure in the corona is presented. Further, it is shown that corotating proton flux enhancements are associated with regions of low coronal X-ray emission (including coronal holes), usually in association with solar wind stream structure.

Magnetic Braids in Eruptions of a Spiral Structure in the Solar Atmosphere

NASA Astrophysics Data System (ADS)

Huang, Zhenghua; Xia, Lidong; Nelson, Chris J.; Liu, Jiajia; Wiegelmann, Thomas; Tian, Hui; Klimchuk, James A.; Chen, Yao; Li, Bo

2018-02-01

We report on high-resolution imaging and spectral observations of eruptions of a spiral structure in the transition region, which were taken with the Interface Region Imaging Spectrograph, and the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). The eruption coincided with the appearance of two series of jets, with velocities comparable to the Alfvén speeds in their footpoints. Several pieces of evidence of magnetic braiding in the eruption are revealed, including localized bright knots, multiple well-separated jet threads, transition region explosive events, and the fact that all three of these are falling into the same locations within the eruptive structures. Through analysis of the extrapolated 3D magnetic field in the region, we found that the eruptive spiral structure corresponded well to locations of twisted magnetic flux tubes with varying curl values along their lengths. The eruption occurred where strong parallel currents, high squashing factors, and large twist numbers were obtained. The electron number density of the eruptive structure is found to be ∼3 × 1012 cm‑3, indicating that a significant amount of mass could be pumped into the corona by the jets. Following the eruption, the extrapolations revealed a set of seemingly relaxed loops, which were visible in the AIA 94 Å channel, indicating temperatures of around 6.3 MK. With these observations, we suggest that magnetic braiding could be part of the mechanisms explaining the formation of solar eruption and the mass and energy supplement to the corona.

Crustal structure of central Lake Baikal: Insights into intracontinental rifting

USGS Publications Warehouse

ten Brink, Uri S.; Taylor, M.H.

2002-01-01

The Cenozoic rift system of Baikal, located in the interior of the largest continental mass on Earth, is thought to represent a potential analog of the early stage of breakup of supercontinents. We present a detailed P wave velocity structure of the crust and sediments beneath the Central Basin, the deepest basin in the Baikal rift system. The structure is characterized by a Moho depth of 39-42.5 km; an 8-km-thick, laterally continuous high-velocity (7.05-7.4 km/s) lower crust, normal upper mantle velocity (8 km/s), a sedimentary section reaching maximum depths of 9 km, and a gradual increase of sediment velocity with depth. We interpret the high-velocity lower crust to be part of the Siberian Platform that was not thinned or altered significantly during rifting. In comparison to published results from the Siberian Platform, Moho under the basin is elevated by <3 km. On the basis of these results we propose that the basin was formed by upper crustal extension, possibly reactivating structures in an ancient fold-and-thrust belt. The extent and location of upper mantle extension are not revealed by our data, and it may be offset from the rift. We believe that the Baikal rift structure is similar in many respects to the Mesozoic Atlantic rift system, the precursor to the formation of the North Atlantic Ocean. We also propose that the Central Baikal rift evolved by episodic fault propagation and basin enlargement, rather than by two-stage rift evolution as is commonly assumed.

Single-protein detection in crowded molecular environments in cryo-EM images

PubMed Central

Rickgauer, J Peter; Grigorieff, Nikolaus; Denk, Winfried

2017-01-01

We present an approach to study macromolecular assemblies by detecting component proteins’ characteristic high-resolution projection patterns, calculated from their known 3D structures, in single electron cryo-micrographs. Our method detects single apoferritin molecules in vitreous ice with high specificity and determines their orientation and location precisely. Simulations show that high spatial-frequency information and—in the presence of protein background—a whitening filter are essential for optimal detection, in particular for images taken far from focus. Experimentally, we could detect small viral RNA polymerase molecules, distributed randomly among binding locations, inside rotavirus particles. Based on the currently attainable image quality, we estimate a threshold for detection that is 150 kDa in ice and 300 kDa in 100 nm thick samples of dense biological material. DOI: http://dx.doi.org/10.7554/eLife.25648.001 PMID:28467302

Structural, electronic, and vibrational properties of high-density amorphous silicon: a first-principles molecular-dynamics study.

PubMed

Morishita, Tetsuya

2009-05-21

We report a first-principles study of the structural, electronic, and dynamical properties of high-density amorphous (HDA) silicon, which was found to be formed by pressurizing low-density amorphous (LDA) silicon (a normal amorphous Si) [T. Morishita, Phys. Rev. Lett. 93, 055503 (2004); P. F. McMillan, M. Wilson, D. Daisenberger, and D. Machon, Nature Mater. 4, 680 (2005)]. Striking structural differences between HDA and LDA are revealed. The LDA structure holds a tetrahedral network, while the HDA structure contains a highly distorted tetrahedral network. The fifth neighboring atom in HDA tends to be located at an interstitial position of a distorted tetrahedron composed of the first four neighboring atoms. Consequently, the coordination number of HDA is calculated to be approximately 5 unlike that of LDA. The electronic density of state (EDOS) shows that HDA is metallic, which is consistent with a recent experimental measurement of the electronic resistance of HDA Si. We find from local EDOS that highly distorted tetrahedral configurations enhance the metallic nature of HDA. The vibrational density of state (VDOS) also reflects the structural differences between HDA and LDA. Some of the characteristic vibrational modes of LDA are dematerialized in HDA, indicating the degradation of covalent bonds. The overall profile of the VDOS for HDA is found to be an intermediate between that for LDA and liquid Si under pressure (high-density liquid Si).

Characterization of a novel domain ‘GATE’ in the ABC protein DrrA and its role in drug efflux by the DrrAB complex

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

Zhang, Han; Rahman, Sadia; Li, Wen

2015-03-27

A novel domain, GATE (Glycine-loop And Transducer Element), is identified in the ABC protein DrrA. This domain shows sequence and structural conservation among close homologs of DrrA as well as distantly-related ABC proteins. Among the highly conserved residues in this domain are three glycines, G215, G221 and G231, of which G215 was found to be critical for stable expression of the DrrAB complex. Other conserved residues, including E201, G221, K227 and G231, were found to be critical for the catalytic and transport functions of the DrrAB transporter. Structural analysis of both the previously published crystal structure of the DrrA homologmore » MalK and the modeled structure of DrrA showed that G215 makes close contacts with residues in and around the Walker A motif, suggesting that these interactions may be critical for maintaining the integrity of the ATP binding pocket as well as the complex. It is also shown that G215A or K227R mutation diminishes some of the atomic interactions essential for ATP catalysis and overall transport function. Therefore, based on both the biochemical and structural analyses, it is proposed that the GATE domain, located outside of the previously identified ATP binding and hydrolysis motifs, is an additional element involved in ATP catalysis. - Highlights: • A novel domain ‘GATE’ is identified in the ABC protein DrrA. • GATE shows high sequence and structural conservation among diverse ABC proteins. • GATE is located outside of the previously studied ATP binding and hydrolysis motifs. • Conserved GATE residues are critical for stability of DrrAB and for ATP catalysis.« less

Structural characterization of framework-gas interactions in the metal-organic framework Co2(dobdc) by in situ single-crystal X-ray diffraction.

PubMed

Gonzalez, Miguel I; Mason, Jarad A; Bloch, Eric D; Teat, Simon J; Gagnon, Kevin J; Morrison, Gregory Y; Queen, Wendy L; Long, Jeffrey R

2017-06-01

The crystallographic characterization of framework-guest interactions in metal-organic frameworks allows the location of guest binding sites and provides meaningful information on the nature of these interactions, enabling the correlation of structure with adsorption behavior. Here, techniques developed for in situ single-crystal X-ray diffraction experiments on porous crystals have enabled the direct observation of CO, CH 4 , N 2 , O 2 , Ar, and P 4 adsorption in Co 2 (dobdc) (dobdc 4- = 2,5-dioxido-1,4-benzenedicarboxylate), a metal-organic framework bearing coordinatively unsaturated cobalt(ii) sites. All these molecules exhibit such weak interactions with the high-spin cobalt(ii) sites in the framework that no analogous molecular structures exist, demonstrating the utility of metal-organic frameworks as crystalline matrices for the isolation and structural determination of unstable species. Notably, the Co-CH 4 and Co-Ar interactions observed in Co 2 (dobdc) represent, to the best of our knowledge, the first single-crystal structure determination of a metal-CH 4 interaction and the first crystallographically characterized metal-Ar interaction. Analysis of low-pressure gas adsorption isotherms confirms that these gases exhibit mainly physisorptive interactions with the cobalt(ii) sites in Co 2 (dobdc), with differential enthalpies of adsorption as weak as -17(1) kJ mol -1 (for Ar). Moreover, the structures of Co 2 (dobdc)·3.8N 2 , Co 2 (dobdc)·5.9O 2 , and Co 2 (dobdc)·2.0Ar reveal the location of secondary (N 2 , O 2 , and Ar) and tertiary (O 2 ) binding sites in Co 2 (dobdc), while high-pressure CO 2 , CO, CH 4 , N 2 , and Ar adsorption isotherms show that these binding sites become more relevant at elevated pressures.

Structural domains and main-chain flexibility in prion proteins.

PubMed

Blinov, N; Berjanskii, M; Wishart, D S; Stepanova, M

2009-02-24

In this study we describe a novel approach to define structural domains and to characterize the local flexibility in both human and chicken prion proteins. The approach we use is based on a comprehensive theory of collective dynamics in proteins that was recently developed. This method determines the essential collective coordinates, which can be found from molecular dynamics trajectories via principal component analysis. Under this particular framework, we are able to identify the domains where atoms move coherently while at the same time to determine the local main-chain flexibility for each residue. We have verified this approach by comparing our results for the predicted dynamic domain systems with the computed main-chain flexibility profiles and the NMR-derived random coil indexes for human and chicken prion proteins. The three sets of data show excellent agreement. Additionally, we demonstrate that the dynamic domains calculated in this fashion provide a highly sensitive measure of protein collective structure and dynamics. Furthermore, such an analysis is capable of revealing structural and dynamic properties of proteins that are inaccessible to the conventional assessment of secondary structure. Using the collective dynamic simulation approach described here along with a high-temperature simulations of unfolding of human prion protein, we have explored whether locations of relatively low stability could be identified where the unfolding process could potentially be facilitated. According to our analysis, the locations of relatively low stability may be associated with the beta-sheet formed by strands S1 and S2 and the adjacent loops, whereas helix HC appears to be a relatively stable part of the protein. We suggest that this kind of structural analysis may provide a useful background for a more quantitative assessment of potential routes of spontaneous misfolding in prion proteins.

Revision of earthquake hypocentre locations in global bulletin data sets using source-specific station terms

NASA Astrophysics Data System (ADS)

Nooshiri, Nima; Saul, Joachim; Heimann, Sebastian; Tilmann, Frederik; Dahm, Torsten

2017-02-01

Global earthquake locations are often associated with very large systematic travel-time residuals even for clear arrivals, especially for regional and near-regional stations in subduction zones because of their strongly heterogeneous velocity structure. Travel-time corrections can drastically reduce travel-time residuals at regional stations and, in consequence, improve the relative location accuracy. We have extended the shrinking-box source-specific station terms technique to regional and teleseismic distances and adopted the algorithm for probabilistic, nonlinear, global-search location. We evaluated the potential of the method to compute precise relative hypocentre locations on a global scale. The method has been applied to two specific test regions using existing P- and pP-phase picks. The first data set consists of 3103 events along the Chilean margin and the second one comprises 1680 earthquakes in the Tonga-Fiji subduction zone. Pick data were obtained from the GEOFON earthquake bulletin, produced using data from all available, global station networks. A set of timing corrections varying as a function of source position was calculated for each seismic station. In this way, we could correct the systematic errors introduced into the locations by the inaccuracies in the assumed velocity structure without explicitly solving for a velocity model. Residual statistics show that the median absolute deviation of the travel-time residuals is reduced by 40-60 per cent at regional distances, where the velocity anomalies are strong. Moreover, the spread of the travel-time residuals decreased by ˜20 per cent at teleseismic distances (>28°). Furthermore, strong variations in initial residuals as a function of recording distance are smoothed out in the final residuals. The relocated catalogues exhibit less scattered locations in depth and sharper images of the seismicity associated with the subducting slabs. Comparison with a high-resolution local catalogue reveals that our relocation process significantly improves the hypocentre locations compared to standard locations.

Combined mine tremors source location and error evaluation in the Lubin Copper Mine (Poland)

NASA Astrophysics Data System (ADS)

Leśniak, Andrzej; Pszczoła, Grzegorz

2008-08-01

A modified method of mine tremors location used in Lubin Copper Mine is presented in the paper. In mines where an intensive exploration is carried out a high accuracy source location technique is usually required. The effect of the flatness of the geophones array, complex geological structure of the rock mass and intense exploitation make the location results ambiguous in such mines. In the present paper an effective method of source location and location's error evaluations are presented, combining data from two different arrays of geophones. The first consists of uniaxial geophones spaced in the whole mine area. The second is installed in one of the mining panels and consists of triaxial geophones. The usage of the data obtained from triaxial geophones allows to increase the hypocenter vertical coordinate precision. The presented two-step location procedure combines standard location methods: P-waves directions and P-waves arrival times. Using computer simulations the efficiency of the created algorithm was tested. The designed algorithm is fully non-linear and was tested on the multilayered rock mass model of the Lubin Copper Mine, showing a computational better efficiency than the traditional P-wave arrival times location algorithm. In this paper we present the complete procedure that effectively solves the non-linear location problems, i.e. the mine tremor location and measurement of the error propagation.

Localization of optic disc and fovea in retinal images using intensity based line scanning analysis.

PubMed

Kamble, Ravi; Kokare, Manesh; Deshmukh, Girish; Hussin, Fawnizu Azmadi; Mériaudeau, Fabrice

2017-08-01

Accurate detection of diabetic retinopathy (DR) mainly depends on identification of retinal landmarks such as optic disc and fovea. Present methods suffer from challenges like less accuracy and high computational complexity. To address this issue, this paper presents a novel approach for fast and accurate localization of optic disc (OD) and fovea using one-dimensional scanned intensity profile analysis. The proposed method utilizes both time and frequency domain information effectively for localization of OD. The final OD center is located using signal peak-valley detection in time domain and discontinuity detection in frequency domain analysis. However, with the help of detected OD location, the fovea center is located using signal valley analysis. Experiments were conducted on MESSIDOR dataset, where OD was successfully located in 1197 out of 1200 images (99.75%) and fovea in 1196 out of 1200 images (99.66%) with an average computation time of 0.52s. The large scale evaluation has been carried out extensively on nine publicly available databases. The proposed method is highly efficient in terms of quickly and accurately localizing OD and fovea structure together compared with the other state-of-the-art methods. Copyright © 2017 Elsevier Ltd. All rights reserved.

Informing geobiology through GIS site suitability analysis: locating springs in mantle units of ophiolites

NASA Astrophysics Data System (ADS)

Bowman, A.; Cardace, D.; August, P.

2012-12-01

Springs sourced in the mantle units of ophiolites serve as windows to the deep biosphere, and thus hold promise in elucidating survival strategies of extremophiles, and may also inform discourse on the origin of life on Earth. Understanding how organisms can survive in extreme environments provides clues to how microbial life responds to gradients in pH, temperature, and oxidation-reduction potential. Spring locations associated with serpentinites have traditionally been located using a variety of field techniques. The aqueous alteration of ultramafic rocks to serpentinites is accompanied by the production of very unusual formation fluids, accessed by drilling into subsurface flow regimes or by sampling at related surface springs. The chemical properties of these springs are unique to water associated with actively serpentinizing rocks; they reflect a reducing subsurface environment reacting at low temperatures producing high pH, Ca-rich formation fluids with high dissolved hydrogen and methane. This study applies GIS site suitability analysis to locate high pH springs upwelling from Coast Range Ophiolite serpentinites in Northern California. We used available geospatial data (e.g., geologic maps, topography, fault locations, known spring locations, etc.) and ArcGIS software to predict new spring localities. Important variables in the suitability model were: (a) bedrock geology (i.e., unit boundaries and contacts for peridotite, serpentinite, possibly pyroxenite, or chromite), (b) fault locations, (c) regional data for groundwater characteristics such as pH, Ca2+, and Mg2+, and (d) slope-aspect ratio. The GIS model derived from these geological and environmental data sets predicts the latitude/longitude points for novel and known high pH springs sourced in serpentinite outcrops in California. Field work confirms the success of the model, and map output can be merged with published environmental microbiology data (e.g., occurrence of hydrogen-oxidizers) to showcase patterns in microbial community structure. Discrepancies between predicted and actual spring locations are then used to tune GIS suitability analysis, re-running the model with corrected geo-referenced data. This presentation highlights a powerful GIS-based technique for accelerating field exploration in this area of ongoing research.

Development of double-pair double difference location algorithm and its application to the regular earthquakes and non-volcanic tremors

NASA Astrophysics Data System (ADS)

Guo, H.; Zhang, H.

2016-12-01

Relocating high-precision earthquakes is a central task for monitoring earthquakes and studying the structure of earth's interior. The most popular location method is the event-pair double-difference (DD) relative location method, which uses the catalog and/or more accurate waveform cross-correlation (WCC) differential times from event pairs with small inter-event separations to the common stations to reduce the effect of the velocity uncertainties outside the source region. Similarly, Zhang et al. [2010] developed a station-pair DD location method which uses the differential times from common events to pairs of stations to reduce the effect of the velocity uncertainties near the source region, to relocate the non-volcanic tremors (NVT) beneath the San Andreas Fault (SAF). To utilize advantages of both DD location methods, we have proposed and developed a new double-pair DD location method to use the differential times from pairs of events to pairs of stations. The new method can remove the event origin time and station correction terms from the inversion system and cancel out the effects of the velocity uncertainties near and outside the source region simultaneously. We tested and applied the new method on the northern California regular earthquakes to validate its performance. In comparison, among three DD location methods, the new double-pair DD method can determine more accurate relative locations and the station-pair DD method can better improve the absolute locations. Thus, we further proposed a new location strategy combining station-pair and double-pair differential times to determine accurate absolute and relative locations at the same time. For NVTs, it is difficult to pick the first arrivals and derive the WCC event-pair differential times, thus the general practice is to measure station-pair envelope WCC differential times. However, station-pair tremor locations are scattered due to the low-precision relative locations. The ability that double-pair data can be directly constructed from the station-pair data means that double-pair DD method can be used for improving NVT locations. We have applied the new method to the NVTs beneath the SAF near Cholame, California. Compared to the previous results, the new double-pair DD tremor locations are more concentrated and show more detailed structures.

Pt3Co concave nanocubes: synthesis, formation understanding, and enhanced catalytic activity toward hydrogenation of styrene.

PubMed

Wang, Chenyu; Lin, Cuikun; Zhang, Lihua; Quan, Zewei; Sun, Kai; Zhao, Bo; Wang, Feng; Porter, Nathan; Wang, Yuxuan; Fang, Jiye

2014-02-03

We report a facile synthesis route to prepare high-quality Pt3Co nanocubes with a concave structure, and further demonstrate that these concave Pt3Co nanocubes are terminated with high-index crystal facets. The success of this preparation is highly dependent on an appropriate nucleation process with a successively anisotropic overgrowth and a preservation of the resultant high-index planes by control binding of oleyl-amine/oleic acid with a fine-tuned composition. Using a hydrogenation of styrene as a model reaction, these Pt3Co concave nanocubes as a new class of nanocatalysts with more open structure and active atomic sites located on their high-index crystallographic planes exhibit an enhanced catalytic activity in comparison with low-indexed surface terminated Pt3Co nanocubes in similar size. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Genetic Diversity and Genetic Relationships of Purple Willow (Salix purpurea L.) from Natural Locations

PubMed Central

Prinz, Kathleen; Przyborowski, Jerzy A.

2017-01-01

In this study, the genetic diversity and structure of 13 natural locations of Salix purpurea were determined with the use of AFLP (amplified length polymorphism), RAPD (randomly amplified polymorphic DNA) and ISSR (inter-simple sequence repeats). The genetic relationships between 91 examined S. purpurea genotypes were evaluated by analyses of molecular variance (AMOVA), principal coordinates analyses (PCoA) and UPGMA (unweighted pair group method with arithmetic mean) dendrograms for both single marker types and a combination of all marker systems. The locations were assigned to distinct regions and the analysis of AMOVA (analysis of molecular variance) revealed a high genetic diversity within locations. The genetic diversity between both regions and locations was relatively low, but typical for many woody plant species. The results noted for the analyzed marker types were generally comparable with few differences in the genetic relationships among S. purpurea locations. A combination of several marker systems could thus be ideally suited to understand genetic diversity patterns of the species. This study makes the first attempt to broaden our knowledge of the genetic parameters of the purple willow (S. purpurea) from natural location for research and several applications, inter alia breeding purposes. PMID:29301207

Impact of anthropogenic pressure on the formation of population structure and genetic diversity of raccoon dog Nyctereutes procyonoides

PubMed Central

Griciuvienė, Loreta; Paulauskas, Algimantas; Radzijevskaja, Jana; Žukauskienė, Judita; Pūraitė, Irma

2016-01-01

Abstract The raccoon dog Nyctereutes procyonoides experienced an active introduction and acclimatization in the European part of Russia followed by its migration to and colonization in the neighboring countries. Eventually, it has spread rapidly into many European countries. N. procyonoides probably invaded Lithuania from the neighboring countries of Belarus and Latvia where the species was introduced. However, the data on genetic diversity and population structure of the raccoon dogs in the recently invaded territories are still scarce. The objectives of this study were to investigate genetic diversity of N. procyonoides in Lithuania after acclimatization, and to assess the impact of anthropogenic pressure on the formation of population structure. A total of 147 N. procyonoides individuals collected from different regions of Lithuania were genotyped using 17 microsatellite markers. The microsatellite analysis of raccoon dogs indicated high levels of genetic diversity within the population. The Bayesian clustering analysis in STRUCTURE identified 4 genetic clusters among sampled raccoon dogs that could not reveal a clear separation between subpopulations. The widespread distribution of raccoon dogs in Lithuania, high level of genetic variation observed within subpopulations, and low level of variation portioned among subpopulations suggest migration and gene flow among locations. The significant correlation between genetic and geographic distances indicated isolation that reflected the distance between locations. The fencing of highways and very intensive traffic could be barriers to gene flow between the western and eastern sampling areas of raccoon dogs. PMID:29491930

Geoelectrical Characterization of the Punta Banda System: A Possible Structural Control for the Geothermal Anomalies

NASA Astrophysics Data System (ADS)

Arango-Galvan, C.; Flores-Marquez, E.; Prol-Ledesma, R.; Working Group, I.

2007-05-01

The lack of sufficient drinking water in México has become a very serious problem, especially in the northern desert regions of the country. In order to give a real solution to this phenomenon the IMPULSA research program has been created to develope novel technologies based on desalination of sea and brackish water using renewable sources of energy to face the problem. The Punta Banda geothermal anomaly is located towards the northern part of Baja California Peninsula (Mexico). High water temperatures in some wells along the coast depicted a geothermal anomaly. An audiomagnetotelluric survey was carried out in the area as a preliminary study, both to understand the process generating these anomalous temperatures and to assess its potential exploitation to supply hot water to desalination plants. Among the electromagnetic methods, the audiomagnetotellurics (AMT) method is appropriated for deep groundwater and geothermal studies. The survey consisted of 27 AMT stations covering a 5 km profile along the Agua Blanca Fault. The employed array allowed us to characterize the geoelectrical properties of the main structures up to 500 m depth. Two main geoelectrical zones were identified: 1) a shallow low resistivity media located at the central portion of the profile, coinciding with the Maneadero valley and 2) two high resitivity structures bordering the conductive zone possibly related to NS faulting, already identified by previous geophysical studies. These results suggest that the main geothermal anomalies are controlled by the dominant structural regime in the zone.

Assistance to neurosurgical planning: using a fuzzy spatial graph model of the brain for locating anatomical targets in MRI

NASA Astrophysics Data System (ADS)

Villéger, Alice; Ouchchane, Lemlih; Lemaire, Jean-Jacques; Boire, Jean-Yves

2007-03-01

Symptoms of neurodegenerative pathologies such as Parkinson's disease can be relieved through Deep Brain Stimulation. This neurosurgical technique relies on high precision positioning of electrodes in specific areas of the basal ganglia and the thalamus. These subcortical anatomical targets must be located at pre-operative stage, from a set of MRI acquired under stereotactic conditions. In order to assist surgical planning, we designed a semi-automated image analysis process for extracting anatomical areas of interest. Complementary information, provided by both patient's data and expert knowledge, is represented as fuzzy membership maps, which are then fused by means of suitable possibilistic operators in order to achieve the segmentation of targets. More specifically, theoretical prior knowledge on brain anatomy is modelled within a 'virtual atlas' organised as a spatial graph: a list of vertices linked by edges, where each vertex represents an anatomical structure of interest and contains relevant information such as tissue composition, whereas each edge represents a spatial relationship between two structures, such as their relative directions. The model is built using heterogeneous sources of information such as qualitative descriptions from the expert, or quantitative information from prelabelled images. For each patient, tissue membership maps are extracted from MR data through a classification step. Prior model and patient's data are then matched by using a research algorithm (or 'strategy') which simultaneously computes an estimation of the location of every structures. The method was tested on 10 clinical images, with promising results. Location and segmentation results were statistically assessed, opening perspectives for enhancements.

Modular, Reconfigurable, High-Energy Systems Stepping Stones

NASA Technical Reports Server (NTRS)

Howell, Joe T.; Carrington, Connie K.; Mankins, John C.

2005-01-01

Modular, Reconfigurable, High-Energy Systems are Stepping Stones to provide capabilities for energy-rich infrastructure strategically located in space to support a variety of exploration scenarios. Abundant renewable energy at lunar or L1 locations could support propellant production and storage in refueling scenarios that enable affordable exploration. Renewable energy platforms in geosynchronous Earth orbits can collect and transmit power to satellites, or to Earth-surface locations. Energy-rich space technologies also enable the use of electric-powered propulsion systems that could efficiently deliver cargo and exploration facilities to remote locations. A first step to an energy-rich space infrastructure is a 100-kWe class solar-powered platform in Earth orbit. The platform would utilize advanced technologies in solar power collection and generation, power management and distribution, thermal management, and electric propulsion. It would also provide a power-rich free-flying platform to demonstrate in space a portfolio of technology flight experiments. This paper presents a preliminary design concept for a 100-kWe solar-powered satellite with the capability to flight-demonstrate a variety of payload experiments and to utilize electric propulsion. State-of-the-art solar concentrators, highly efficient multi-junction solar cells, integrated thermal management on the arrays, and innovative deployable structure design and packaging make the 100-kW satellite feasible for launch on one existing launch vehicle. Higher voltage arrays and power management and distribution (PMAD) systems reduce or eliminate the need for massive power converters, and could enable direct- drive of high-voltage solar electric thrusters.

Factors influencing ruminal bacterial community diversity and composition and microbial fibrolytic enzyme abundance in lactating dairy cows with a focus on the role of active dry yeast.

PubMed

AlZahal, Ousama; Li, Fuyong; Guan, Le Luo; Walker, Nicola D; McBride, Brian W

2017-06-01

The objective of the current study was to employ a DNA-based sequencing technology to study the effect of active dry yeast (ADY) supplementation, diet type, and sample location within the rumen on rumen bacterial community diversity and composition, and to use an RNA-based method to study the effect of ADY supplementation on rumen microbial metabolism during high-grain feeding (HG). Our previous report demonstrated that the supplementation of lactating dairy cows with ADY attenuated the effect of subacute ruminal acidosis. Therefore, we used samples from that study, where 16 multiparous, rumen-cannulated lactating Holstein cows were randomly assigned to 1 of 2 dietary treatments: ADY (Saccharomyces cerevisiae strain Y1242, 80 billion cfu/animal per day) or control (carrier only). Cows received a high-forage diet (77:23, forage:concentrate), then were abruptly switched to HG (49:51, forage:concentrate). Rumen bacterial community diversity and structure were highly influenced by diet and sampling location (fluid, solids, epimural). The transition to HG reduced bacterial diversity, but epimural bacteria maintained a greater diversity than fluid and solids. Analysis of molecular variance indicated a significant separation due to diet × sampling location, but not due to treatment. Across all samples, the analysis yielded 6,254 nonsingleton operational taxonomic units (OTU), which were classified into several phyla: mainly Firmicutes, Bacteroidetes, Fibrobacteres, Tenericutes, and Proteobacteria. High forage and solids were dominated by OTU from Fibrobacter, whereas HG and fluid were dominated by OTU from Prevotella. Epimural samples, however, were dominated in part by Campylobacter. Active dry yeast had no effect on bacterial community diversity or structure. The phylum SR1 was more abundant in all ADY samples regardless of diet or sampling location. Furthermore, on HG, OTU2 and OTU3 (both classified into Fibrobacter succinogenes) were more abundant with ADY in fluid and solids than control samples. This increase with ADY was paralleled by a reduction in prominent Prevotella OTU. Metatranscriptomic profiling of rumen microbiome conducted on random samples from the HG phase showed that ADY increased the abundance of the cellulase endo-β-1,4-glucanase and had a tendency to increase the hemicellulase α-glucuronidase. In conclusion, the shift from high forage to HG and sampling location had a more significant influence on ruminal bacterial community abundance and structure compared with ADY. However, evidence suggested that ADY can increase the abundance of some dominant anaerobic OTU belonging to F. succinogenes and phylum SR1. Further, microbial mRNA-based evidence suggested that ADY can increase the abundance of a specific microbial fibrolytic enzymes. The Authors. Published by the Federation of Animal Science Societies and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

Structural Characterization of the 216-Z-9 Crib Prior to Decontamination and Demolition Using Robot Crawler and High Resolution Photography

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

Hopkins, A.; Sutter, C.; Klos, D.B.

2008-07-01

The Department of Energy, Richland Operations Office is preparing to conduct a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) removal action for the decontamination and demolition of the above-grade mining structures and equipment at the 216-Z-9 Crib. An investigation of the condition of the mining complex was initiated to determine constraints necessary for safely conducting the removal of the buildings. While crib headspace chemical analysis and nondestructive analysis of the interior of the buildings was completed to address radiological contamination concerns, the primary concern regarding the removal of the above-grade structures located on the crib cover involves determining themore » loading capacity and structural integrity of the crib cover slab. Additional concerns included headspace gases and radionuclide contamination. Until the structural analysis was completed, loading limits on the crib cover had been restricted. Photographic documentation revealed the loss of protective tiles and acid resistant coating from the underside of the cover raising a question of concrete stability. The investigation relied heavily on the use of high resolution photography with high intensity lighting for photographic documentation of the underside of the crib cover, followed by structural analysis of the documentation by a team of qualified engineers. Deployment of a robot crawler with attached camera and positioning of a fixed camera were integral to this structural characterization effort. Results of the photographic documentation were of sufficient quality to allow for bounding decisions to be made regarding the loading of the crib cover while performing the demolition of the mining structures (glovebox, excavator, bucket) and the associated buildings. The 216-Z-9 Crib, also known as the 216 Z-9 Recuplex CAW (CA column waste) Waste Disposal Cavern, the Z-9 Trench and the Z-9 Crib was constructed as an engineered trench with an open area beneath a concrete slab. The crib is located near the Plutonium Finishing Plant (PFP) facility, at the Hanford Nuclear Reservation in Eastern Washington State. The crib was used as a disposal site for effluent chemical and radiological wastes from the recovery of uranium and plutonium through extraction or RECUPLEX process, a method that recovered uranium and plutonium from liquid and solid wastes and scraps from other PFP processes. During its operating life, from 1955 through 1962, the Z-9 Crib received liquid wastes totaling approximately four million liters, or one million gallons. Analyses of the crib soil in seven locations to a depth of up to two meters (six feet) beneath the crib floor indicated that the plutonium content of the crib soil ranged from 50 to 150 kg (the highest concentration measured was 34.5 g/L of soil). While performing the structural evaluation of the crib cover, additional characterization information was obtained on the radiological and chemical conditions of the crib and structures. (authors)« less

Spacecraft Leak Location Using Structure-Borne Noise

NASA Astrophysics Data System (ADS)

Reusser, R. S.; Chimenti, D. E.; Holland, S. D.; Roberts, R. A.

2010-02-01

Guided ultrasonic waves, generated by air escaping through a small hole, have been measured with an 8×8 piezoelectric phased-array detector. Rapid location of air leaks in a spacecraft skin, caused by high-speed collisions with small objects, is essential for astronaut survival. Cross correlation of all 64 elements, one pair at a time, on a diced PZT disc combined with synthetic aperture analysis determines the dominant direction of wave propagation. The leak location is triangulated by combining data from two or more detector. To optimize the frequency band selection for the most robust direction finding, noise-field measurements of a plate with integral stiffeners have been performed using laser Doppler velocimetry. We compare optical and acoustic measurements to analyze the influence of the PZT array detector and its mechanical coupling to the plate.

3D Thermal and Electrochemical Model for Spirally Wound Large Format Lithium-ion Batteries (Presentation)

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

Lee, K. J.; Kim, G. H.; Smith, K.

In many commercial cells, long tabs at both cell sides, leading to uniform potentials along the spiral direction of wound jelly rolls, are rarely seen because of their high manufacturing cost. More often, several metal strips are welded at discrete locations along both current collector foils. With this design, the difference of electrical potentials is easily built up along current collectors in the spiral direction. Hence, the design features of the tabs, such as number, location and size, can be crucial factors for spiral-shaped battery cells. This paper presents a Li-ion battery cell model having a 3-dimensional spiral mesh involvingmore » a wound jellyroll structure. Further results and analysis will be given regarding impacts of tab location, number, and size.« less

Status of astigmatism-corrected Czerny-Turner spectrometers

NASA Astrophysics Data System (ADS)

Li, Xinhang; Dong, Keyan; An, Yan; Wang, Zhenye

2016-10-01

In order to analysis and design the Czerny-Turner structure spectrometer with the high resolution and high energy reception, various astigmatism methods of the Czerny-Turner structure are reported. According to the location of plane grating, the astigmatism correction methods are divided into two categories, one is the plane grating in divergent illumination, another is the plane grating in parallel illumination. Basing on the different methods, the anastigmatic principle and methods are analyzed, the merits and demerits of the above methods are summarized and evaluated. The theoretical foundation for design of broadband eliminating astigmatism Czerny-Turner spectrometer and the reference value for the further design work are laid by the summary and analyzing in this paper.

Learning primary care in medical school: does specialty or geographic location of the teaching site make a difference?

PubMed

Irigoyen, M M; Kurth, R J; Schmidt, H J

1999-05-01

The Liaison Committee on Medical Education mandates a core curriculum in primary care but does not specify its content or structure. In this study, we explored the question of whether primary care specialty or geographic location affects student learning and satisfaction. From 1994 to 1996, 294 third-year medical students at one medical school in New York state were randomly assigned to multiple teaching sites for a required 5-week primary care clerkship. Independent predictor variables were primary care specialty of the preceptor (family medicine, medicine, pediatrics, or joint medicine and pediatrics) and geographic location of the site (urban, suburban, rural). Outcome measures included four areas of student satisfaction, one of patient volume, and two of student performance. Primary care specialty had no detectable association with the outcome measures, except for a lower rating of patient diversity in pediatric experiences (P <0.001). Geographic location of the site had a significant association with all measures of student satisfaction and patient volume (all P values <0.001). Students at rural sites rated the experience more highly and saw on average 15 more patients per rotation. Ratings of student satisfaction remained high after adjusting for patient volume. Primary care specialty and geographic location did not influence student performance in the clerkship or scores on standardized patient examination. Rural geographic location of teaching site, but not primary care specialty, was associated with higher student satisfaction. However, higher student satisfaction ratings did not correspond to better student performance. Provided that all sites meet the screening criteria for inclusion in a teaching program, these findings support the continued development of high-quality, heterogeneous, interdisciplinary, primary care experiences.

Structural health monitoring to detect the presence, location and magnitude of structural damage in cadaveric porcine spines.

PubMed

Kawchuk, Gregory Neil; Decker, Colleen; Dolan, Ryan; Carey, Jason

2009-01-19

Structural health monitoring has been used successfully to identify defects in civil infrastructure and aerospace applications. Given that the majority of low back pain is thought to be mechanical in nature, our objective was to determine if structural health monitoring techniques could be employed successfully to identify the presence, location and magnitude of structural alterations within the spine. In six eviscerated cadaveric pigs, bone screws were drilled into the anterior bodies of L1-L5 and tri-axial accelerometers fixed to each spinous process. Vibration was then applied to the L3 spinous and frequency response functions obtained from each sensor axis before and after specific alterations of spinal structure. These alterations were produced at four unique locations and included (1) use of a cable tie to link anterior bone pins together and (2) progressive disc sectioning. Eighty percent of all data were used to train a neural network while the remaining data were used to test the network's ability to distinguish between structural states. The presence, location and magnitude of structural change within the spine was identified correctly in 5030/5040 possible neural network decisions. The diagnostic sensitivity and specificity of this technique ranged from 0.994 to 1.000. These results indicate that there is sufficient information embedded in frequency response data to identify the presence, location and magnitude of specific structural changes in the spine. If these techniques can be evolved for human use, structural health monitoring may provide a new approach toward understanding the underlying relations between spinal structure and function.

Flaws detection and localization in weld structure using the topological energy method

NASA Astrophysics Data System (ADS)

Lubeigt, Emma; Mensah, Serge; Rakotonarivo, Sandrine; Chaix, Jean-François; Gobillot, Gilles; Baqué, François

2017-02-01

The non-destructive testing of austenitic welds using ultrasound plays an important role in the assessment of the structural integrity and safety of critical structures in a nuclear reactor. The bedspring and the deck are complex welded structures of very restricted access; the ability to reliably detect and locate defects like cracks is therefore a difficult challenge. Ultrasonic testing is a well-recognized non-invasive technique which exhibits high characterization performances in homogeneous media (steel). However, its capabilities are hampered when operating in heterogeneous and anisotropic austenitic welds because of deviation and splitting of the ultrasonic beam. In order to rise to this important challenge, a model-based method is proposed, which takes into account a prior knowledge corresponding to the welding procedure specifications that condition the austenitic grains orientation within the weld and thus the wave propagation. The topological imaging method implemented is a differential approach which, compares signals from the reference defect-free medium to the inspected medium. It relies on combinations of two computed ultrasonic fields, one forward and one adjoint. Numerical simulations and experiments have been carried out to validate the practical relevance of this approach to detect and locate a flaw in a weld.

Mesoscale influence on long-range transport — evidence from ETEX modelling and observations

NASA Astrophysics Data System (ADS)

Sørensen, Jens Havskov; Rasmussen, Alix; Ellermann, Thomas; Lyck, Erik

During the first European Tracer Experiment (ETEX) tracer gas was released from a site in Brittany, France, and subsequently observed over a range of 2000 km. Hourly measurements were taken at the National Environmental Research Institute (NERI) located at Risø, Denmark, using two measurement techniques. At this location, the observed concentration time series shows a double-peak structure occurring between two and three days after the release. By using the Danish Emergency Response Model of the Atmosphere (DERMA), which is developed at the Danish Meteorological Institute (DMI), simulations of the dispersion of the tracer gas have been performed. Using numerical weather-prediction data from the European Centre for Medium-Range Weather Forecast (ECMWF) by DERMA, the arrival time of the tracer is quite well predicted, so also is the duration of the passage of the plume, but the double-peak structure is not reproduced. However, using higher-resolution data from the DMI version of the HIgh Resolution Limited Area Model (DMI-HIRLAM), DERMA reproduces the observed structure very well. The double-peak structure is caused by the influence of a mesoscale anti-cyclonic eddy on the tracer gas plume about one day earlier.

Polymorphic design of DNA origami structures through mechanical control of modular components.

PubMed

Lee, Chanseok; Lee, Jae Young; Kim, Do-Nyun

2017-12-12

Scaffolded DNA origami enables the bottom-up fabrication of diverse DNA nanostructures by designing hundreds of staple strands, comprised of complementary sequences to the specific binding locations of a scaffold strand. Despite its exceptionally high design flexibility, poor reusability of staples has been one of the major hurdles to fabricate assorted DNA constructs in an effective way. Here we provide a rational module-based design approach to create distinct bent shapes with controllable geometries and flexibilities from a single, reference set of staples. By revising the staple connectivity within the desired module, we can control the location, stiffness, and included angle of hinges precisely, enabling the construction of dozens of single- or multiple-hinge structures with the replacement of staple strands up to 12.8% only. Our design approach, combined with computational shape prediction and analysis, can provide a versatile and cost-effective procedure in the design of DNA origami shapes with stiffness-tunable units.

Predicting the effectiveness of viscoelastic damping pockets in beams

NASA Astrophysics Data System (ADS)

Butler, Nigel D.; Oyadiji, S. O.

2005-05-01

This paper looks at the use of viscoelastic damping pockets in the suppression of structural vibration. These are in the form of cavities filled with a viscoelastic material. The benefits and uses of these designed-in damping treatments are highlighted. The vibration responses of viscoelastically-damped beams are predicted using the finite element method. A series of cantilevered beams are considered and the damping performance of several configurations of designed-in dampers are predicted and compared to that of a traditional CLD treatment. It is shown that the effectiveness of the damping pockets and sinks depends on their location and size with respect to the highly stressed regions of the beams. Although there is a practical limit on the sizes of the geometrical features that can be designed-in, it is shown that if located correctly the damping pockets and sinks can be more effective at suppressing structural vibration than traditional CLD treatments.

Impact of Rate Design Alternatives on Residential Solar Customer Bills. Increased Fixed Charges, Minimum Bills and Demand-based Rates

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

Bird, Lori; Davidson, Carolyn; McLaren, Joyce

With rapid growth in energy efficiency and distributed generation, electric utilities are anticipating stagnant or decreasing electricity sales, particularly in the residential sector. Utilities are increasingly considering alternative rates structures that are designed to recover fixed costs from residential solar photovoltaic (PV) customers with low net electricity consumption. Proposed structures have included fixed charge increases, minimum bills, and increasingly, demand rates - for net metered customers and all customers. This study examines the electricity bill implications of various residential rate alternatives for multiple locations within the United States. For the locations analyzed, the results suggest that residential PV customers offset,more » on average, between 60% and 99% of their annual load. However, roughly 65% of a typical customer's electricity demand is non-coincidental with PV generation, so the typical PV customer is generally highly reliant on the grid for pooling services.« less

Atomic sites and stability of Cs+ captured within zeolitic nanocavities

PubMed Central

Yoshida, Kaname; Toyoura, Kazuaki; Matsunaga, Katsuyuki; Nakahira, Atsushi; Kurata, Hiroki; Ikuhara, Yumi H.; Sasaki, Yukichi

2013-01-01

Zeolites have potential application as ion-exchangers, catalysts and molecular sieves. Zeolites are once again drawing attention in Japan as stable adsorbents and solidification materials of fission products, such as 137Cs+ from damaged nuclear-power plants. Although there is a long history of scientific studies on the crystal structures and ion-exchange properties of zeolites for practical application, there are still open questions, at the atomic-level, on the physical and chemical origins of selective ion-exchange abilities of different cations and detailed atomic structures of exchanged cations inside the nanoscale cavities of zeolites. Here, the precise locations of Cs+ ions captured within A-type zeolite were analyzed using high-resolution electron microscopy. Together with theoretical calculations, the stable positions of absorbed Cs+ ions in the nanocavities are identified, and the bonding environment within the zeolitic framework is revealed to be a key factor that influences the locations of absorbed cations. PMID:23949184

Auditing hierarchical cycles to locate other inconsistencies in the UMLS.

PubMed

Halper, Michael; Morrey, C Paul; Chen, Yan; Elhanan, Gai; Hripcsak, George; Perl, Yehoshua

2011-01-01

A cycle in the parent relationship hierarchy of the UMLS is a configuration that effectively makes some concept(s) an ancestor of itself. Such a structural inconsistency can easily be found automatically. A previous strategy for disconnecting cycles is to break them with the deletion of one or more parent relationships-irrespective of the correctness of the deleted relationships. A methodology is introduced for auditing of cycles that seeks to discover and delete erroneous relationships only. Cycles involving three concepts are the primary consideration. Hypotheses about the high probability of locating an erroneous parent relationship in a cycle are proposed and confirmed with statistical confidence and lend credence to the auditing approach. A cycle may serve as an indicator of other non-structural inconsistencies that are otherwise difficult to detect automatically. An extensive auditing example shows how a cycle can indicate further inconsistencies.

Auditing Hierarchical Cycles to Locate Other Inconsistencies in the UMLS

PubMed Central

Halper, Michael; Morrey, C. Paul; Chen, Yan; Elhanan, Gai; Hripcsak, George; Perl, Yehoshua

2011-01-01

A cycle in the parent relationship hierarchy of the UMLS is a configuration that effectively makes some concept(s) an ancestor of itself. Such a structural inconsistency can easily be found automatically. A previous strategy for disconnecting cycles is to break them with the deletion of one or more parent relationships—irrespective of the correctness of the deleted relationships. A methodology is introduced for auditing of cycles that seeks to discover and delete erroneous relationships only. Cycles involving three concepts are the primary consideration. Hypotheses about the high probability of locating an erroneous parent relationship in a cycle are proposed and confirmed with statistical confidence and lend credence to the auditing approach. A cycle may serve as an indicator of other non-structural inconsistencies that are otherwise difficult to detect automatically. An extensive auditing example shows how a cycle can indicate further inconsistencies. PMID:22195107

Structure and Function of Ephemeral Streams in the Arid and Semiarid Southwest: Implications for Conservation and Management

DTIC Science & Technology

2015-07-24

stream flow, trade-offs were apparent between riparian plant biomass (high at wetter sites) and plant species diversity (high at dry sites with...iv) between wet and dry seasons? Technical Approach. A space-for-time substitution approach was followed in which changes across spatial water...For arthropods, pitfall traps were set during dry and wet seasons in channel, riparian and upland locations in canyon and piedmont reaches to

Investigations in the ionosphere on Kosmos 378. IV. Structure of regions where electrons with energies 0. 5-12 keV and their convection are recorded

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

Khokhlov, M.Z.

1975-01-01

The position of regions where electron fluxes were recorded in November 1970 is analyzed from the data of satellite-borne charged particle analyzers. These regions are located at invariant latitudes ..lambda.. > 65/sup 0/ under geomagnetically quiet conditions and separate into low- and high-latitude zones. The electric drift speed in the high-latitude zone is estimated. 37 references.

Flow prediction over a transport multi-element high-lift system and comparison with flight measurements

NASA Technical Reports Server (NTRS)

Vijgen, P. M. H. W.; Hardin, J. D.; Yip, L. P.

1992-01-01

Accurate prediction of surface-pressure distributions, merging boundary-layers, and separated-flow regions over multi-element high-lift airfoils is required to design advanced high-lift systems for efficient subsonic transport aircraft. The availability of detailed measurements of pressure distributions and both averaged and time-dependent boundary-layer flow parameters at flight Reynolds numbers is critical to evaluate computational methods and to model the turbulence structure for closure of the flow equations. Several detailed wind-tunnel measurements at subscale Reynolds numbers were conducted to obtain detailed flow information including the Reynolds-stress component. As part of a subsonic-transport high-lift research program, flight experiments are conducted using the NASA-Langley B737-100 research aircraft to obtain detailed flow characteristics for support of computational and wind-tunnel efforts. Planned flight measurements include pressure distributions at several spanwise locations, boundary-layer transition and separation locations, surface skin friction, as well as boundary-layer profiles and Reynolds stresses in adverse pressure-gradient flow.

JNSViewer—A JavaScript-based Nucleotide Sequence Viewer for DNA/RNA secondary structures

PubMed Central

Dong, Min; Graham, Mitchell; Yadav, Nehul

2017-01-01

Many tools are available for visualizing RNA or DNA secondary structures, but there is scarce implementation in JavaScript that provides seamless integration with the increasingly popular web computational platforms. We have developed JNSViewer, a highly interactive web service, which is bundled with several popular tools for DNA/RNA secondary structure prediction and can provide precise and interactive correspondence among nucleotides, dot-bracket data, secondary structure graphs, and genic annotations. In JNSViewer, users can perform RNA secondary structure predictions with different programs and settings, add customized genic annotations in GFF format to structure graphs, search for specific linear motifs, and extract relevant structure graphs of sub-sequences. JNSViewer also allows users to choose a transcript or specific segment of Arabidopsis thaliana genome sequences and predict the corresponding secondary structure. Popular genome browsers (i.e., JBrowse and BrowserGenome) were integrated into JNSViewer to provide powerful visualizations of chromosomal locations, genic annotations, and secondary structures. In addition, we used StructureFold with default settings to predict some RNA structures for Arabidopsis by incorporating in vivo high-throughput RNA structure profiling data and stored the results in our web server, which might be a useful resource for RNA secondary structure studies in plants. JNSViewer is available at http://bioinfolab.miamioh.edu/jnsviewer/index.html. PMID:28582416

Cryo-EM structure of the spinach chloroplast ribosome reveals the location of plastid-specific ribosomal proteins and extensions

PubMed Central

Graf, Michael; Arenz, Stefan; Huter, Paul; Dönhöfer, Alexandra; Nováček, Jiří

2017-01-01

Abstract Ribosomes are the protein synthesizing machines of the cell. Recent advances in cryo-EM have led to the determination of structures from a variety of species, including bacterial 70S and eukaryotic 80S ribosomes as well as mitoribosomes from eukaryotic mitochondria, however, to date high resolution structures of plastid 70S ribosomes have been lacking. Here we present a cryo-EM structure of the spinach chloroplast 70S ribosome, with an average resolution of 5.4 Å for the small 30S subunit and 3.6 Å for the large 50S ribosomal subunit. The structure reveals the location of the plastid-specific ribosomal proteins (RPs) PSRP1, PSRP4, PSRP5 and PSRP6 as well as the numerous plastid-specific extensions of the RPs. We discover many features by which the plastid-specific extensions stabilize the ribosome via establishing additional interactions with surrounding ribosomal RNA and RPs. Moreover, we identify a large conglomerate of plastid-specific protein mass adjacent to the tunnel exit site that could facilitate interaction of the chloroplast ribosome with the thylakoid membrane and the protein-targeting machinery. Comparing the Escherichia coli 70S ribosome with that of the spinach chloroplast ribosome provides detailed insight into the co-evolution of RP and rRNA. PMID:27986857

Microwave sintering of single plate-shaped articles

DOEpatents

Katz, J.D.; Blake, R.D.

1995-07-11

Apparatus and method are disclosed for high temperature sintering of plate-shaped articles of alumina, magnesia, silica, yttria, zirconia, and mixtures thereof using microwave radiation. An article is placed within a sintering structure located within a sintering container which is placed in a microwave cavity for heating. The rates at which heating and cooling take place is controlled. 2 figs.

Invasive plants transform the three-dimensional structure of rain forests

Treesearch

Gegory P. Asner; R. Flint Hughes; Peter M. Vitousek; David E. Knapp; Ty Kennedy-Bowdoin; Joseph Boardman; Roberta E. Martin; Michael Eastwood; Robert O. Green

2008-01-01

Biological invasions contribute to global environmental change, but the dynamics and consequences of most invasions are difficult to assess at regional scales. We deployed an airborne remote sensing system that mapped the location and impacts of five highly invasive plant species across 221,875 ha of Hawaiian ecosystems, identifying four distinct ways that these...

Beyond Classroom Walls: Developing Innovative Work Roles for Teachers

ERIC Educational Resources Information Center

Kowal, Julie; Brinson, Dana

2011-01-01

The teaching profession has long been structured around full-time classroom responsibilities that are defined by the location, timing, and schedule of the school day and a ubiquitous one-teacher-per-classroom model. In most districts, the only option for highly successful teachers to advance in the profession or serve more students is to leave the…

School-Based Clinics: A Guide for Advocates. Developing Policy Statements, Educating Decision Makers, Enlisting Local Support.

ERIC Educational Resources Information Center

Center for Population Options, Washington, DC.

School-based clinics (SBCs) are comprehensive primary health care facilities located within or on the grounds of middle, junior, or senior high schools. Varying in size and organizational structure, SBCs have emerged as an effective model for advancing adolescent health. They have gained attention because of their potential for treating problems…

A new GIS-based tsunami risk evaluation: MeTHuVA (METU tsunami human vulnerability assessment) at Yenikapı, Istanbul

NASA Astrophysics Data System (ADS)

Cankaya, Zeynep Ceren; Suzen, Mehmet Lutfi; Yalciner, Ahmet Cevdet; Kolat, Cagil; Zaytsev, Andrey; Aytore, Betul

2016-07-01

Istanbul is a mega city with various coastal utilities located on the northern coast of the Sea of Marmara. At Yenikapı, there are critical vulnerable coastal utilities, structures, and active metropolitan life. Fishery ports, commercial ports, small craft harbors, passenger terminals of intercity maritime transportation, waterfront commercial and/or recreational structures with residential/commercial areas and public utility areas are some examples of coastal utilization that are vulnerable to marine disasters. Therefore, the tsunami risk in the Yenikapı region is an important issue for Istanbul. In this study, a new methodology for tsunami vulnerability assessment for areas susceptible to tsunami is proposed, in which the Yenikapı region is chosen as a case study. Available datasets from the Istanbul Metropolitan Municipality and Turkish Navy are used as inputs for high-resolution GIS-based multi-criteria decision analysis (MCDA) evaluation of tsunami risk in Yenikapı. Bathymetry and topography database is used for high-resolution tsunami numerical modeling where the tsunami hazard, in terms of coastal inundation, is deterministically computed using the NAMI DANCE numerical code, considering earthquake worst case scenarios. In order to define the tsunami human vulnerability of the region, two different aspects, vulnerability at location and evacuation resilience maps were created using the analytical hierarchical process (AHP) method of MCDA. A vulnerability at location map is composed of metropolitan use, geology, elevation, and distance from shoreline layers, whereas an evacuation resilience map is formed by slope, distance within flat areas, distance to buildings, and distance to road networks layers. The tsunami risk map is then computed by the proposed new relationship which uses flow depth maps, vulnerability at location maps, and evacuation resilience maps.

Developing a system for blind acoustic source localization and separation

NASA Astrophysics Data System (ADS)

Kulkarni, Raghavendra

This dissertation presents innovate methodologies for locating, extracting, and separating multiple incoherent sound sources in three-dimensional (3D) space; and applications of the time reversal (TR) algorithm to pinpoint the hyper active neural activities inside the brain auditory structure that are correlated to the tinnitus pathology. Specifically, an acoustic modeling based method is developed for locating arbitrary and incoherent sound sources in 3D space in real time by using a minimal number of microphones, and the Point Source Separation (PSS) method is developed for extracting target signals from directly measured mixed signals. Combining these two approaches leads to a novel technology known as Blind Sources Localization and Separation (BSLS) that enables one to locate multiple incoherent sound signals in 3D space and separate original individual sources simultaneously, based on the directly measured mixed signals. These technologies have been validated through numerical simulations and experiments conducted in various non-ideal environments where there are non-negligible, unspecified sound reflections and reverberation as well as interferences from random background noise. Another innovation presented in this dissertation is concerned with applications of the TR algorithm to pinpoint the exact locations of hyper-active neurons in the brain auditory structure that are directly correlated to the tinnitus perception. Benchmark tests conducted on normal rats have confirmed the localization results provided by the TR algorithm. Results demonstrate that the spatial resolution of this source localization can be as high as the micrometer level. This high precision localization may lead to a paradigm shift in tinnitus diagnosis, which may in turn produce a more cost-effective treatment for tinnitus than any of the existing ones.

Evaluation of Disulfide Bond Position to Enhance the Thermal Stability of a Highly Stable Single Domain Antibody

PubMed Central

Zabetakis, Dan; Olson, Mark A.; Anderson, George P.; Legler, Patricia M.; Goldman, Ellen R.

2014-01-01

Single domain antibodies are the small recombinant variable domains derived from camelid heavy-chain-only antibodies. They are renowned for their stability, in large part due to their ability to refold following thermal or chemical denaturation. In addition to refolding after heat denaturation, A3, a high affinity anti-Staphylococcal Enterotoxin B single domain antibody, possesses a melting temperature of ∼84°C, among the highest reported for a single domain antibody. In this work we utilized the recently described crystal structure of A3 to select locations for the insertion of a second disulfide bond and evaluated the impact that the addition of this second bond had on the melting temperature. Four double-disulfide versions of A3 were constructed and each was found to improve the melting temperature relative to the native structure without reducing affinity. Placement of the disulfide bond at a previously published position between framework regions 2 and 3 yielded the largest improvement (>6°C), suggesting this location is optimal, and seemingly provides a universal route to raise the melting temperature of single domain antibodies. This study further demonstrates that even single domain antibodies with extremely high melting points can be further stabilized by addition of disulfide bonds. PMID:25526640

Spatial structure in the diet of imperial eagles Aquila heliaca in Kazakhstan

USGS Publications Warehouse

Katzner, T.E.; Bragin, E.A.; Knick, S.T.; Smith, A.T.

2006-01-01

We evaluated the relationship between spatial variability in prey and food habits of eastern imperial eagles Aquila heliaca at a 90,000 ha national nature reserve in north-central Kazakhstan. Eagle diet varied greatly within the population and the spatial structure of eagle diet within the population varied according to the scale of measurement. Patterns in dietary response were inconsistent with expectations if either ontogenetic imprinting or competition determined diet choice, but they met expectations if functional response determined diet. Eagles nesting near a high-density prey resource used that resource almost exclusively. In contrast, in locations with no single high-density prey species, eagles' diet was more diverse. Our results demonstrate that spatial structuring of diet of vertebrate predators can provide important insight into the mechanisms that drive dietary decisions. ?? OIKOS.

Cyclic structural analyses of anisotropic turbine blades for reusable space propulsion systems. [ssme fuel turbopump

NASA Technical Reports Server (NTRS)

Manderscheid, J. M.; Kaufman, A.

1985-01-01

Turbine blades for reusable space propulsion systems are subject to severe thermomechanical loading cycles that result in large inelastic strains and very short lives. These components require the use of anisotropic high-temperature alloys to meet the safety and durability requirements of such systems. To assess the effects on blade life of material anisotropy, cyclic structural analyses are being performed for the first stage high-pressure fuel turbopump blade of the space shuttle main engine. The blade alloy is directionally solidified MAR-M 246 alloy. The analyses are based on a typical test stand engine cycle. Stress-strain histories at the airfoil critical location are computed using the MARC nonlinear finite-element computer code. The MARC solutions are compared to cyclic response predictions from a simplified structural analysis procedure developed at the NASA Lewis Research Center.

Open-Section Composite Structural Elements

NASA Technical Reports Server (NTRS)

Loftin, T. A.; Smith, C. A.; Raheb, S. J.; Nowitzky, A. M.

1991-01-01

Report describes investigation of manufacture and mechanical properties of graphite-fiber/aluminum-matrix open-section structural elements; e.g., channels and angle bars. Conducted with view toward using such elements to build lightweight, thermally stable truss structures in outer space. Other applications transport to, and assembly at, remote or otherwise uninviting locations. Advantages include shapes permitting high packing density during shipment, convenient paths for routing tubes, hoses, and cables; accessibility of both inner and outer surfaces for repair; and ease of attachment of additional hardware. Easier and require less equipment to fabricate, and more amenable to automated fabrication and assembly at remote site. Disadvantages, not as resistant to some kinds of deformation under load.

Quiet Clean Short-haul Experimental Engine (QCSEE). Composite fan frame subsystem test report

NASA Technical Reports Server (NTRS)

Stotler, C. L., Jr.; Bowden, J. H.

1977-01-01

The element and subcomponent testing conducted to verify the composite fan frame design of two experimental high bypass geared turbofan engines and propulsion systems for short haul passenger aircraft is described. Emphasis is placed on the propulsion technology required for future externally blown flap aircraft with engines located both under the wing and over the wing, including technology in composite structures and digital engine controls. The element tests confirmed that the processes used in the frame design would produce the predicted mechanical properties. The subcomponent tests verified that the detail structural components of the frame had adequate structural integrity.

An approximation method for configuration optimization of trusses

NASA Technical Reports Server (NTRS)

Hansen, Scott R.; Vanderplaats, Garret N.

1988-01-01

Two- and three-dimensional elastic trusses are designed for minimum weight by varying the areas of the members and the location of the joints. Constraints on member stresses and Euler buckling are imposed and multiple static loading conditions are considered. The method presented here utilizes an approximate structural analysis based on first order Taylor series expansions of the member forces. A numerical optimizer minimizes the weight of the truss using information from the approximate structural analysis. Comparisons with results from other methods are made. It is shown that the method of forming an approximate structural analysis based on linearized member forces leads to a highly efficient method of truss configuration optimization.

Anthropomorphic master/slave manipulator system

NASA Technical Reports Server (NTRS)

Vykukal, H. C.; King, R. F.; Vallotton, W. C. (Inventor)

1977-01-01

An anthropomorphic master/slave manipulator system including master arm apparatus with a plurality of master tubular articulated portions is outlined. Objectives of this investion were to provide a system that accurately and smoothly simulates human limb movement at a remote location. The system has a high frequency response, a high structural stiffness and a design that protects the components of the slave mechanism. Simulation of human movements is possible in outer space, underwater, and in a hazardous environment such as in a high radiation area. The equivalent ability, dexterity, and strength of a human arm are simulated.

National Program for Inspection of Non-Federal Dams. Lake Gardner Dam (MA 00152), Merrimack River Basin, Amesbury, Massachusetts. Phase I Inspection Report.

DTIC Science & Technology

1978-09-01

embankmenr approximately 750 ft. long and 25 ft. high and an ungrated granite block spillway about 73. ft. wide and 16 ft. high. A 24-in. reservoir...the Location Map, page viii. B. Dam and Appurtenances. Lake Gardner Dam is approxi- mately 1000 ft. long, consisting mainly of an ungated granite block...is a broad crested granite masonry structure, about 16 ft. high and 72. 6 ft. wide. The nine courses of stone ex- posed on the downstream face of the

Tsunami shelter in Padang city: Location suitability and management issue

NASA Astrophysics Data System (ADS)

Rita, Eva; Permata, Robby; Yonne, Hilma; Carlo, Nasfryzal

2017-11-01

The building of Temporary Evacuation Sites (TES/shelter) is an effort to minimize the vulnerability of the population who live in coastal city areas with high risk of tsunami. Padang city in Indonesia, one of the cities with high risk of tsunami, has built shelter in North Ulak Karang Village, North Padang Sub-district. The problems are the location of shelter does not meet the standard of population number, how to manage the shelter in normal condition (without disaster), and who will be responsible for the management of the shelter. The aim of the study is to learn the suitability of shelter location and the management of the shelter in normal condition as well as the expectation of the people who live near the shelter location. This research uses evaluative-descriptive method with the collection of secondary and primary data through structured interviews with 200 respondents in the area of shelter building. The result shows that the furthest location of the shelter is located at RW 03 with a distance of 1.3 kms which takes 12.15-24.30 minutes. It shows that the shelter location in Padang meets the requirement of FEMA P646. At normal condition, shelter can be used for sport and educational activities, as a center for socialisation and simulation of disaster and other activities. The management of the shelter is done together by government and stakeholders. The proposed management is by forming a team (organization) which involves Disaster Alert groups (KSB) and by making the Standard Operational Procedures (SOP) for their implementation. People expect that the number of shelter is added and the building of the shelter is based on the suitability of location, number of population and availability of land.

Options for Location in the Organizational Structure.

ERIC Educational Resources Information Center

Taylor, Alton L.

1990-01-01

The location of the institutional research unit within the organizational structure influences the role it plays in supporting effective decision making. A theoretical framework of organizational structure based on division of labor can be applied to higher education institutions, with implications for staffing and expectations for performance.…

Large stationary wave features appearing repeatedly at the cloud top of Venus

NASA Astrophysics Data System (ADS)

Kouyama, Toru; Imamura, Takeshi; Taguchi, Makoto; Fukuhara, Tetsuya; Sato, Takao M.; Hashimoto, George L.; Futaguchi, Masahiko; Takamura, Mao; Yamada, Takeru; Satoh, Takehiko; Nakamura, Masato; Akatsuki Science Team

2017-10-01

At the first observation sequence after Akatsuki’s Venus orbiter re-insertion (VOI-R) on December 7, 2015, Akatsuki revealed an existence of a large-scale “bow-shaped” feature staying at almost same geographic location (above Aphrodite Terra) at the cloud top level with the Longwave Infrared Camera (LIR) and Ultra Violet Imager (UVI). It expanded ~10,000 km from south to north and bended to downstream side of the super-rotation of Venus. A numerical calculation in Fukuhara et al. (2017) suggested that a gravity wave generated in the lower atmosphere can propagate upward to the cloud top and reproduce the observed bow-shape structure. Because the wave can transport momentum to the upper atmosphere which possibly decelerates the super-rotation, it is an interesting topic whether the stationary wave event is regular or just an occasional event. For more than three Venus years, or four Venus solar days, Akatsuki has observed huge stationary wave features in LIR images again and again since the VOI-R. It has been confirmed that four high-altitude regions, east and west part of Aphrodite Terra, Atra Regio, and Beta Regio, accompany with the large stationary features. All four regions are located in lower latitudes (< 30°), while no clear stationary feature has been confirmed above Maxwell Mountain, which is the highest mountain but located at a high latitude (60°), indicating geographical and latitudinal dependencies of the generation of the stationary waves. Akatsuki also reveals the stationary features can be considered as "daily" phenomena in Venus atmosphere. At every timing when the four high-altitude regions were passing afternoon region of Venus, huge stationary waves became clearer. On the other hand, when the high mountains were located around mid-night and morning, stationary features were much weaker than that in afternoon, or cannot be confirmed, indicating strong local time dependency of the appearance. Since lower latitude has more incident solar flux and afternoon area experiences longer solar heating than morning area, the geographical and the local time dependencies indicate that interaction between mountains and solar heating or solar fixed atmospheric structure may cause the large-scale features.

Acoustic emission based damage localization in composites structures using Bayesian identification

NASA Astrophysics Data System (ADS)

Kundu, A.; Eaton, M. J.; Al-Jumali, S.; Sikdar, S.; Pullin, R.

2017-05-01

Acoustic emission based damage detection in composite structures is based on detection of ultra high frequency packets of acoustic waves emitted from damage sources (such as fibre breakage, fatigue fracture, amongst others) with a network of distributed sensors. This non-destructive monitoring scheme requires solving an inverse problem where the measured signals are linked back to the location of the source. This in turn enables rapid deployment of mitigative measures. The presence of significant amount of uncertainty associated with the operating conditions and measurements makes the problem of damage identification quite challenging. The uncertainties stem from the fact that the measured signals are affected by the irregular geometries, manufacturing imprecision, imperfect boundary conditions, existing damages/structural degradation, amongst others. This work aims to tackle these uncertainties within a framework of automated probabilistic damage detection. The method trains a probabilistic model of the parametrized input and output model of the acoustic emission system with experimental data to give probabilistic descriptors of damage locations. A response surface modelling the acoustic emission as a function of parametrized damage signals collected from sensors would be calibrated with a training dataset using Bayesian inference. This is used to deduce damage locations in the online monitoring phase. During online monitoring, the spatially correlated time data is utilized in conjunction with the calibrated acoustic emissions model to infer the probabilistic description of the acoustic emission source within a hierarchical Bayesian inference framework. The methodology is tested on a composite structure consisting of carbon fibre panel with stiffeners and damage source behaviour has been experimentally simulated using standard H-N sources. The methodology presented in this study would be applicable in the current form to structural damage detection under varying operational loads and would be investigated in future studies.

Study of Seismic Clusters at Bahía de Banderas Region, Mexico

NASA Astrophysics Data System (ADS)

Nunez-Cornu, F. J.; Rutz-Lopez, M.; Suarez-Plascencia, C.; Trejo-Gomez, E.

2010-12-01

Given that the coast in the states of Jalisco and south of the state of Nayarit is located within a region of high seismic potential and also because population is increasing, perhaps motivated by the development of tourism, the Civil Defense authorities of Jalisco and the Centro de Sismología y Volcanología de Occidente-SisVOc of Universidad de Guadalajara started in the year 2000 a joint project to study the seismic risk of the region, including the seismic monitoring of Colima volcano (located between the states of Jalisco and Colima). This work focuses on the study of seismicity in the area of Bahía de Banderas and northern coast of Jalisco. To this end, we perform an analysis of available seismograms to characterize active structures, their relationship to surface morphology, and possible reach of these structures into the shallow parts of the bay. The data used in this work are waveforms recorded during the year 2003 during which the seismograph network spanned the region of study. Our method is based on the identification of seismic clusters or families using cross-correlation of waveforms, earthquake relocation and modeling of fault planes. From an initial data set of 404 earthquakes located during 2003, 96 earthquakes could be related to 17 potentially active continental structures. A modeling of fault planes was possible for 11 of these structures. Subgroups of 7 structures are aligned parallel to the Middle America Trench, a possible consequence of oblique subduction. The magnitudes of earthquakes grouped into families is less than 3.6 (Ml), corresponding to fault dimensions of hundreds of meters.

Crystal structure of papaya glutaminyl cyclase, an archetype for plant and bacterial glutaminyl cyclases.

PubMed

Wintjens, René; Belrhali, Hassan; Clantin, Bernard; Azarkan, Mohamed; Bompard, Coralie; Baeyens-Volant, Danielle; Looze, Yvan; Villeret, Vincent

2006-03-24

Glutaminyl cyclases (QCs) (EC 2.3.2.5) catalyze the intramolecular cyclization of protein N-terminal glutamine residues into pyroglutamic acid with the concomitant liberation of ammonia. QCs may be classified in two groups containing, respectively, the mammalian enzymes, and the enzymes from plants, bacteria, and parasites. The crystal structure of the QC from the latex of Carica papaya (PQC) has been determined at 1.7A resolution. The structure was solved by the single wavelength anomalous diffraction technique using sulfur and zinc as anomalous scatterers. The enzyme folds into a five-bladed beta-propeller, with two additional alpha-helices and one beta hairpin. The propeller closure is achieved via an original molecular velcro, which links the last two blades into a large eight stranded beta-sheet. The zinc ion present in the PQC is bound via an octahedral coordination into an elongated cavity located along the pseudo 5-fold axis of the beta-propeller fold. This zinc ion presumably plays a structural role and may contribute to the exceptional stability of PQC, along with an extended hydrophobic packing, the absence of long loops, the three-joint molecular velcro and the overall folding itself. Multiple sequence alignments combined with structural analyses have allowed us to tentatively locate the active site, which is filled in the crystal structure either by a Tris molecule or an acetate ion. These analyses are further supported by the experimental evidence that Tris is a competitive inhibitor of PQC. The active site is located at the C-terminal entrance of the PQC central tunnel. W83, W110, W169, Q24, E69, N155, K225, F22 and F67 are highly conserved residues in the C-terminal entrance, and their putative role in catalysis is discussed. The PQC structure is representative of the plants, bacterial and parasite enzymes and contrasts with that of mammalian enzymes, that may possibly share a conserved scaffold of the bacterial aminopeptidase.

Modular Track System For Positioning Mobile Robots

NASA Technical Reports Server (NTRS)

Miller, Jeff

1995-01-01

Conceptual system for positioning mobile robotic manipulators on large main structure includes modular tracks and ancillary structures assembled easily along with main structure. System, called "tracked robotic location system" (TROLS), originally intended for application to platforms in outer space, but TROLS concept might also prove useful on Earth; for example, to position robots in factories and warehouses. T-cross-section rail keeps mobile robot on track. Bar codes mark locations along track. Each robot equipped with bar-code-recognizing circuitry so it quickly finds way to assigned location.

Resistivity and Seismic Surface Wave Tomography Results for the Nevşehir Kale Region: Cappadocia, Turkey

NASA Astrophysics Data System (ADS)

Coşkun, Nart; Çakır, Özcan; Erduran, Murat; Arif Kutlu, Yusuf

2014-05-01

The Nevşehir Kale region located in the middle of Cappadocia with approximately cone shape is investigated for existence of an underground city using the geophysical methods of electrical resistivity and seismic surface wave tomography together. Underground cities are generally known to exist in Cappadocia. The current study has obtained important clues that there may be another one under the Nevşehir Kale region. Two-dimensional resistivity and seismic profiles approximately 4-km long surrounding the Nevşehir Kale are measured to determine the distribution of electrical resistivities and seismic velocities under the profiles. Several high resistivity anomalies with a depth range 8-20 m are discovered to associate with a systematic void structure beneath the region. Because of the high resolution resistivity measurement system currently employed we were able to isolate the void structure from the embedding structure. Low seismic velocity zones associated with the high resistivity depths are also discovered. Using three-dimensional visualization techniques we show the extension of the void structure under the measured profiles.

Structural zeros in high-dimensional data with applications to microbiome studies.

PubMed

Kaul, Abhishek; Davidov, Ori; Peddada, Shyamal D

2017-07-01

This paper is motivated by the recent interest in the analysis of high-dimensional microbiome data. A key feature of these data is the presence of "structural zeros" which are microbes missing from an observation vector due to an underlying biological process and not due to error in measurement. Typical notions of missingness are unable to model these structural zeros. We define a general framework which allows for structural zeros in the model and propose methods of estimating sparse high-dimensional covariance and precision matrices under this setup. We establish error bounds in the spectral and Frobenius norms for the proposed estimators and empirically verify them with a simulation study. The proposed methodology is illustrated by applying it to the global gut microbiome data of Yatsunenko and others (2012. Human gut microbiome viewed across age and geography. Nature 486, 222-227). Using our methodology we classify subjects according to the geographical location on the basis of their gut microbiome. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Hydrocarbon provinces and productive trends in Libya and adjacent areas

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

Missallati, A.A.

1988-08-01

According to the age of major reservoirs, hydrocarbon occurrences in Libya and adjacent areas can be grouped into six major systems which, according to their geographic locations, can be classified into two major hydrocarbon provinces: (1) Sirte-Pelagian basins province, with major reservoirs ranging from middle-late Mesozoic to early Tertiary, and (2) Murzog-Ghadames basins province, with major reservoirs ranging from early Paleozoic to early Mesozoic. In the Sirte-Pelagian basins province, hydrocarbons have been trapped in structural highs or in stratigraphic wedge-out against structural highs and in carbonate buildups. Here, hydrocarbon generation is characterized by the combined effect of abundant structural reliefmore » and reservoir development in the same hydrocarbon systems of the same age, providing an excellent example of hydrocarbon traps in sedimentary basins that have undergone extensive tensional fracturing in a shallow marine environment. In the Murzog-Ghadames basins province, hydrocarbons have been trapped mainly in structural highs controlled by paleostructural trends as basement arches which acted as focal points for oil migration and accumulation.« less

Structural Health Monitoring for Impact Damage in Composite Structures.

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

Roach, Dennis P.; Raymond Bond; Doug Adams

Composite structures are increasing in prevalence throughout the aerospace, wind, defense, and transportation industries, but the many advantages of these materials come with unique challenges, particularly in inspecting and repairing these structures. Because composites of- ten undergo sub-surface damage mechanisms which compromise the structure without a clear visual indication, inspection of these components is critical to safely deploying composite re- placements to traditionally metallic structures. Impact damage to composites presents one of the most signi fi cant challenges because the area which is vulnerable to impact damage is generally large and sometimes very dif fi cult to access. This workmore » seeks to further evolve iden- ti fi cation technology by developing a system which can detect the impact load location and magnitude in real time, while giving an assessment of the con fi dence in that estimate. Fur- thermore, we identify ways by which impact damage could be more effectively identi fi ed by leveraging impact load identi fi cation information to better characterize damage. The impact load identi fi cation algorithm was applied to a commercial scale wind turbine blade, and results show the capability to detect impact magnitude and location using a single accelerometer, re- gardless of sensor location. A technique for better evaluating the uncertainty of the impact estimates was developed by quantifying how well the impact force estimate meets the assump- tions underlying the force estimation technique. This uncertainty quanti fi cation technique was found to reduce the 95% con fi dence interval by more than a factor of two for impact force estimates showing the least uncertainty, and widening the 95% con fi dence interval by a fac- tor of two for the most uncertain force estimates, avoiding the possibility of understating the uncertainty associated with these estimates. Linear vibration based damage detection tech- niques were investigated in the context of structural stiffness reductions and impact damage. A method by which the sensitivity to damage could be increased for simple structures was presented, and the challenges of applying that technique to a more complex structure were identi fi ed. The structural dynamic changes in a weak adhesive bond were investigated, and the results showed promise for identifying weak bonds that show little or no static reduction in stiffness. To address these challenges in identifying highly localized impact damage, the possi- bility of detecting damage through nonlinear dynamic characteristics was also identi fi ed, with a proposed technique which would leverage impact location estimates to enable the detection of impact damage. This nonlinear damage identi fi cation concept was evaluated on a composite panel with a substructure disbond, and the results showed that the nonlinear dynamics at the damage site could be observed without a baseline healthy reference. By further developing impact load identi fi cation technology and combining load and damage estimation techniques into an integrated solution, the challenges associated with impact detection in composite struc- tures can be effectively solved, thereby reducing costs, improving safety, and enhancing the operational readiness and availability of high value assets.« less

Anatomy of a subduction zone - seismicity structure of the northern Chilean forearc from >100,000 double-difference relocated earthquake hypocenters

NASA Astrophysics Data System (ADS)

Sippl, Christian; Schurr, Bernd

2017-04-01

We present a catalog of >100k well-located earthquake hypocenters for the northern Chilean forearc region, between the latitudes of 18.5°S and 24°S. The detected events cover the timespan 2007-2014 and were extracted from the IPOC permanent station network dataset. Previously published earthquake catalogs for the region contain significantly fewer earthquakes. Using this new, high-resolution set of hypocenters, we can outline the slab structure in unprecedented detail, allowing e.g. the determination of along-strike changes in slab dip angle or the resolution of structures inside the zone of intermediate-depth seismicity. For the compilation of the catalog, we relied on an automated multi-step process for event detection, association and phase picking. Thus retrieved earthquake hypocenters were then relocated in a 2.5D velocity model for the Northern Chile forearc region with a probabilistic approach that also allows the determination of uncertainties. In a final step, double-difference re-location incorporating cross-correlation lag times was performed, which sharpened event clusters through relative location. We estimate that the completeness magnitude of the catalog is around 3. The majority of all >100k earthquakes are located at intermediate depths (between 80 and 140 km) inside the subducted slab. This area of pervasive activity extends along the entire strike of the investigated area, but shows a clear offset at 21°S, which may hint at a slab tear at this location. Events of comparable hypocentral depths to the south of this offset are located further east than the ones to the north of it. Further updip, a triple seismic zone at depths between 40 and around 80 km is visible, which grades into the highly active event cluster at intermediate depths: below the plate interface, which is clearly delineated by seismic activity, a second parallel band of hypocenters only about 5 km below likely corresponds to earthquakes occurring within the oceanic crust or close to the oceanic Moho. A third band of earthquakes, paralleling the other two at about 20-25 km below the interface, clearly indicates the presence of seismicity in the oceanic lithospheric mantle. Seismicity in the upper plate is pervasive throughout the entire crustal thickness near the coast but gets shallower towards the volcanic arc. Shallow clusters related to regional mining activities are also clearly visible.

Preparation and Catalytic Activity for Aerobic Glucose Oxidation of Crown Jewel Structured Pt/Au Bimetallic Nanoclusters

NASA Astrophysics Data System (ADS)

Zhang, Haijun; Wang, Liqiong; Lu, Lilin; Toshima, Naoki

2016-08-01

Understanding of the “structure-activity” relations for catalysts at an atomic level has been regarded as one of the most important objectives in catalysis studies. Bimetallic nanoclusters (NCs) in its many types, such as core/shell, random alloy, cluster-in-cluster, bi-hemisphere, and crown jewel (one kind of atom locating at the top position of another kind of NC), attract significant attention owing to their excellent optical, electronic, and catalytic properties. PVP-protected crown jewel-structured Pt/Au (CJ-Pt/Au) bimetallic nanoclusters (BNCs) with Au atoms located at active top sites were synthesized via a replacement reaction using 1.4-nm Pt NCs as mother clusters even considering the fact that the replacement reaction between Pt and Au3+ ions is difficult to be occurred. The prepared CJ-Pt/Au colloidal catalysts characterized by UV-Vis, TEM, HR-TEM and HAADF-STEM-EELS showed a high catalytic activity for aerobic glucose oxidation, and the top Au atoms decorating the Pt NCs were about 15 times more active than the Au atoms of Au NCs with similar particle size.

Preparation and Catalytic Activity for Aerobic Glucose Oxidation of Crown Jewel Structured Pt/Au Bimetallic Nanoclusters

PubMed Central

Zhang, Haijun; Wang, Liqiong; Lu, Lilin; Toshima, Naoki

2016-01-01

Understanding of the “structure-activity” relations for catalysts at an atomic level has been regarded as one of the most important objectives in catalysis studies. Bimetallic nanoclusters (NCs) in its many types, such as core/shell, random alloy, cluster-in-cluster, bi-hemisphere, and crown jewel (one kind of atom locating at the top position of another kind of NC), attract significant attention owing to their excellent optical, electronic, and catalytic properties. PVP-protected crown jewel-structured Pt/Au (CJ-Pt/Au) bimetallic nanoclusters (BNCs) with Au atoms located at active top sites were synthesized via a replacement reaction using 1.4-nm Pt NCs as mother clusters even considering the fact that the replacement reaction between Pt and Au3+ ions is difficult to be occurred. The prepared CJ-Pt/Au colloidal catalysts characterized by UV-Vis, TEM, HR-TEM and HAADF-STEM-EELS showed a high catalytic activity for aerobic glucose oxidation, and the top Au atoms decorating the Pt NCs were about 15 times more active than the Au atoms of Au NCs with similar particle size. PMID:27476577

Choosing a DIVA: a comparison of emerging digital imagery vegetation analysis techniques

USGS Publications Warehouse

Jorgensen, Christopher F.; Stutzman, Ryan J.; Anderson, Lars C.; Decker, Suzanne E.; Powell, Larkin A.; Schacht, Walter H.; Fontaine, Joseph J.

2013-01-01

Question: What is the precision of five methods of measuring vegetation structure using ground-based digital imagery and processing techniques? Location: Lincoln, Nebraska, USA Methods: Vertical herbaceous cover was recorded using digital imagery techniques at two distinct locations in a mixed-grass prairie. The precision of five ground-based digital imagery vegetation analysis (DIVA) methods for measuring vegetation structure was tested using a split-split plot analysis of covariance. Variability within each DIVA technique was estimated using coefficient of variation of mean percentage cover. Results: Vertical herbaceous cover estimates differed among DIVA techniques. Additionally, environmental conditions affected the vertical vegetation obstruction estimates for certain digital imagery methods, while other techniques were more adept at handling various conditions. Overall, percentage vegetation cover values differed among techniques, but the precision of four of the five techniques was consistently high. Conclusions: DIVA procedures are sufficient for measuring various heights and densities of standing herbaceous cover. Moreover, digital imagery techniques can reduce measurement error associated with multiple observers' standing herbaceous cover estimates, allowing greater opportunity to detect patterns associated with vegetation structure.

Structural vibration passive control and economic analysis of a high-rise building in Beijing

NASA Astrophysics Data System (ADS)

Chen, Yongqi; Cao, Tiezhu; Ma, Liangzhe; Luo, Chaoying

2009-12-01

Performance analysis of the Pangu Plaza under earthquake and wind loads is described in this paper. The plaza is a 39-story steel high-rise building, 191 m high, located in Beijing close to the 2008 Olympic main stadium. It has both fluid viscous dampers (FVDs) and buckling restrained braces or unbonded brace (BRB or UBB) installed. A repeated iteration procedure in its design and analysis was adopted for optimization. Results from the seismic response analysis in the horizontal and vertical directions show that the FVDs are highly effective in reducing the response of both the main structure and the secondary system. A comparative analysis of structural seismic performance and economic impact was conducted using traditional methods, i.e., increased size of steel columns and beams and/or use of an increased number of seismic braces versus using FVD. Both the structural response and economic analysis show that using FVD to absorb seismic energy not only satisfies the Chinese seismic design code for a “rare” earthquake, but is also the most economical way to improve seismic performance both for one-time direct investment and long term maintenance.

Crystal structure of human tooth enamel studied by neutron diffraction

NASA Astrophysics Data System (ADS)

Ouladdiaf, Bachir; Rodriguez-Carvajal, Juan; Goutaudier, Christelle; Ouladdiaf, Selma; Grosgogeat, Brigitte; Pradelle, Nelly; Colon, Pierre

2015-02-01

Crystal structure of human tooth enamel was investigated using high-resolution neutron powder diffraction. Excellent agreement between observed and refined patterns is obtained, using the hexagonal hydroxyapatite model for the tooth enamel, where a large hydroxyl deficiency ˜70% is found in the 4e site. Rietveld refinements method combined with the difference Fourier maps have revealed, however, that the hydroxyl ions are not only disordered along the c-axis but also within the basal plane. Additional H ions located at the 6h site and forming HPO42- anions were found.

Heat pipe investigations

NASA Technical Reports Server (NTRS)

Marshburn, J. P.

1972-01-01

The OAO-C spacecraft has three circular heat pipes, each of a different internal design, located in the space between the spacecraft structural tube and the experiment tube, which are designed to isothermalize the structure. Two of the pipes are used to transport high heat loads, and the third is for low heat loads. The test problems deal with the charging of the pipes, modifications, the mobile tilt table, the position indicator, and the heat input mechanisms. The final results showed that the techniques used were adequate for thermal-vacuum testing of heat pipes.

Toroidal magnetic detector for high resolution measurement of muon momenta

DOEpatents

Bonanos, P.

1992-01-07

A muon detector system including central and end air-core superconducting toroids and muon detectors enclosing a central calorimeter/detector. Muon detectors are positioned outside of toroids and all muon trajectory measurements are made in a nonmagnetic environment. Internal support for each magnet structure is provided by sheets, located at frequent and regularly spaced azimuthal planes, which interconnect the structural walls of the toroidal magnets. In a preferred embodiment, the shape of the toroidal magnet volume is adjusted to provide constant resolution over a wide range of rapidity. 4 figs.

Thermal imaging of afterburning plumes

NASA Astrophysics Data System (ADS)

Ajdari, E.; Gutmark, E.; Parr, T. P.; Wilson, K. J.; Schadow, K. C.

1989-01-01

Afterburning and nonafterburning exhaust plumes were studied experimentally for underexpanded sonic and supersonic conical circular nozzles. The plume structure was visualized using thermal imaging camera and regular photography. IR emission by the plume is mainly dependent on the presence of afterburning. Temperature and reducing power of the exhaust gases, in addition to the nozzle configuration, determine the structure of the plume core, the location where the afterburning is initiated, its size and intensity. Comparison between single shot and average thermal images of the plume show that afterburning is a highly turbulent combustion process.

Toroidal magnetic detector for high resolution measurement of muon momenta

DOEpatents

Bonanos, Peter

1992-01-01

A muon detector system including central and end air-core superconducting toroids and muon detectors enclosing a central calorimeter/detector. Muon detectors are positioned outside of toroids and all muon trajectory measurements are made in a nonmagnetic environment. Internal support for each magnet structure is provided by sheets, located at frequent and regularly spaced azimuthal planes, which interconnect the structural walls of the toroidal magnets. In a preferred embodiment, the shape of the toroidal magnet volume is adjusted to provide constant resolution over a wide range of rapidity.

Locating damage using integrated global-local approach with wireless sensing system and single-chip impedance measurement device.

PubMed

Lin, Tzu-Hsuan; Lu, Yung-Chi; Hung, Shih-Lin

2014-01-01

This study developed an integrated global-local approach for locating damage on building structures. A damage detection approach with a novel embedded frequency response function damage index (NEFDI) was proposed and embedded in the Imote2.NET-based wireless structural health monitoring (SHM) system to locate global damage. Local damage is then identified using an electromechanical impedance- (EMI-) based damage detection method. The electromechanical impedance was measured using a single-chip impedance measurement device which has the advantages of small size, low cost, and portability. The feasibility of the proposed damage detection scheme was studied with reference to a numerical example of a six-storey shear plane frame structure and a small-scale experimental steel frame. Numerical and experimental analysis using the integrated global-local SHM approach reveals that, after NEFDI indicates the approximate location of a damaged area, the EMI-based damage detection approach can then identify the detailed damage location in the structure of the building.

Can Intonational Phrase Structure be Primed (like Syntactic Structure)?

PubMed Central

Tooley, Kristen M.; Konopka, Agnieszka E.; Watson, Duane G.

2013-01-01

In three experiments, we investigated whether intonational phrase structure can be primed. In all experiments, participants listened to sentences in which the presence and location of intonational phrase boundaries was manipulated such that the recording either included no intonational phrase boundaries, a boundary in a structurally dispreferred location, in a preferred location, or in both locations. In Experiment 1, participants repeated the sentences to test whether they would reproduce the prosodic structure they had just heard. Experiments 2 and 3 used a prime-target paradigm to evaluate whether the intonational phrase structure heard in the prime sentence might influence that of a novel target sentence. Experiment 1 showed that participants did repeat back sentences that they just heard with the original intonational phrase structure, yet Experiments 2 and 3 found that exposure to intonational phrase boundaries on prime trials did not influence how a novel target sentence was prosodically phrased. These results suggest that speakers may retain the intonational phrasing of a sentence, but this effect is not long-lived and does not generalize across unrelated sentences. Furthermore, these findings provide no evidence that intonational phrase structure is formulated during a planning stage that is separate from other sources of linguistic information. PMID:24188467

18 CFR 1304.410 - Navigation restrictions.

Code of Federal Regulations, 2010 CFR

2010-04-01

..., structures, land based or water use, shall not be located within the limits of safety harbors and landings established for commercial navigation. (b) Structures shall not be located in such a way as to block the... OF CONSTRUCTION IN THE TENNESSEE RIVER SYSTEM AND REGULATION OF STRUCTURES AND OTHER ALTERATIONS...

18 CFR 1304.410 - Navigation restrictions.

Code of Federal Regulations, 2011 CFR

2011-04-01

..., structures, land based or water use, shall not be located within the limits of safety harbors and landings established for commercial navigation. (b) Structures shall not be located in such a way as to block the... OF CONSTRUCTION IN THE TENNESSEE RIVER SYSTEM AND REGULATION OF STRUCTURES AND OTHER ALTERATIONS...

Sparse trees and shrubs confers a high biodiversity to pastures: Case study on spiders from Transylvania.

PubMed

Gallé, Róbert; Urák, István; Nikolett, Gallé-Szpisjak; Hartel, Tibor

2017-01-01

The integration of food production and biodiversity conservation represents a key challenge for sustainability. Several studies suggest that even small structural elements in the landscape can make a substantial contribution to the overall biodiversity value of the agricultural landscapes. Pastures can have high biodiversity potential. However, their intensive and monofunctional use typically erodes its natural capital, including biodiversity. Here we address the ecological value of fine scale structural elements represented by sparsely scattered trees and shrubs for the spider communities in a moderately intensively grazed pasture in Transylvania, Eastern Europe. The pasture was grazed with sheep, cattle and buffalo (ca 1 Livestock Unit ha-1) and no chemical fertilizers were applied. Sampling sites covered the open pasture as well as the existing fine-scale heterogeneity created by scattered trees and shrub. 40 sampling locations each being represented by three 1 m2 quadrats were situated in a stratified design while assuring spatial independency of sampling locations. We identified 140 species of spiders, out of which 18 were red listed and four were new for the Romanian fauna. Spider species assemblages of open pasture, scattered trees, trees and shrubs and the forest edge were statistically distinct. Our study shows that sparsely scattered mature woody vegetation and shrubs substantially increases the ecological value of managed pastures. The structural complexity provided by scattered trees and shrubs makes possible the co-occurrence of high spider diversity with a moderately high intensity grazing possible in this wood-pasture. Our results are in line with recent empirical research showing that sparse trees and shrubs increases the biodiversity potential of pastures managed for commodity production.

Sparse trees and shrubs confers a high biodiversity to pastures: Case study on spiders from Transylvania

PubMed Central

Nikolett, Gallé-Szpisjak; Hartel, Tibor

2017-01-01

The integration of food production and biodiversity conservation represents a key challenge for sustainability. Several studies suggest that even small structural elements in the landscape can make a substantial contribution to the overall biodiversity value of the agricultural landscapes. Pastures can have high biodiversity potential. However, their intensive and monofunctional use typically erodes its natural capital, including biodiversity. Here we address the ecological value of fine scale structural elements represented by sparsely scattered trees and shrubs for the spider communities in a moderately intensively grazed pasture in Transylvania, Eastern Europe. The pasture was grazed with sheep, cattle and buffalo (ca 1 Livestock Unit ha-1) and no chemical fertilizers were applied. Sampling sites covered the open pasture as well as the existing fine-scale heterogeneity created by scattered trees and shrub. 40 sampling locations each being represented by three 1 m2 quadrats were situated in a stratified design while assuring spatial independency of sampling locations. We identified 140 species of spiders, out of which 18 were red listed and four were new for the Romanian fauna. Spider species assemblages of open pasture, scattered trees, trees and shrubs and the forest edge were statistically distinct. Our study shows that sparsely scattered mature woody vegetation and shrubs substantially increases the ecological value of managed pastures. The structural complexity provided by scattered trees and shrubs makes possible the co-occurrence of high spider diversity with a moderately high intensity grazing possible in this wood-pasture. Our results are in line with recent empirical research showing that sparse trees and shrubs increases the biodiversity potential of pastures managed for commodity production. PMID:28886058

Three-dimensional structure of the crust in the central Tien Shan and implications for the geodynamic process of continental mountain building

NASA Astrophysics Data System (ADS)

Omuralieva, A.; Nakajima, J.; Hasegawa, A.

2006-12-01

Applying a tomographic method to arrival-time data from shallow local earthquakes registered by Kyrgyz seismic NETwork (KNET), the three-dimensional (3D) velocity structure of the crust beneath Central Tien Shan has been studied. Kyrgyzstan occupies western and central parts of the Tien-Shan and northern Pamir which are prominent consequences of India-Asia Collision surrounded by relatively stable Kazakh shield, Tarim Basin and Turan plate. Accurate and precise tomographic imaging helps us to better understand dynamics of the mountain building, interaction of these tectonic blocks associated with simultaneous mountain building and crustal deformation processes in this complicated region. This study is the first attempt to investigate crustal structure of the Central Tien Shan by means of relatively new data set. Study area is enclosed by 42.00-43.50N and 73.50-76.50E owing to dense station distribution and ray coverage. Arrival time data from ~1500 local earthquakes recorded by a broadband network KNET consisting of 10 stations located in the northern part of Kyrgyzstan during 1995-2005 have been used. We selected earthquakes as uniform as possible in the study area. Most of the earthquakes are located in a depth range of 10 and 20 km. The tomography method by Zhao et al. (JGR, 1992) has been used in this study. We set all layers of grid-net up to Moho discontinuity in the upper and lower crust with spacing 5 km and 10 km depths, respectively. The spacing between grid nodes is 0.3 degree (about 30 km) in horizontal direction. The total number of grid nodes is ~400. The 3-D structure of the upper crust reveals thick sediments within each of the major depression in the region bounded by high-V zone that are believed to be basement. The study area is characterized by an alternation of high-V and low-V layers beneath ranges and basins. The tomographic results exhibit considerable amount of crustal heterogeneities, which confirms the tectonic complexities of the study area. Earthquakes are located either in or on the edge (transition zone) of low-V layers in the southern and northern foot-hills of Tien Shan, respectively. Location of the faults is consistent with transition basin-range zones.

Using Receiver Functions to Image the Montana Crust and Upper Mantle

NASA Astrophysics Data System (ADS)

Sirianni, R. T.; Russo, R. M.

2008-12-01

We determined receiver functions (RFs) at six permanent Advanced National Seismic System (ANSS) stations to examine crust and upper mantle structure of the Wyoming craton (WC) and Medicine Hat block (MHB). The Deep Probe & SAREX projects (Henstock et al., 1998; Clowes et al., 2002; Gorman et al., 2002) used active source seismics to model a high velocity crustal layer (the so-called 7x layer) beneath the WC. This layer exhibits P wave velocities that are high for lower continental crust (~7+ km/s) and extends from 30-55 km below the surface. Interpretations of the active source data indicate that this layer may represent wide scale crustal underplating of the WC, implying post-Archean craton modification with implications for Laurentia assembly. We used 43 earthquakes from a wide azimuthal distribution recorded at the Montana ANSS stations; high signal-to-noise ratios of 25 of these RFs were acceptable for further analysis. Receiver functions constrain crustal velocity structure beneath a seismometer by using P-to-S wave conversions at sharp velocity contrast boundaries. Preliminary results for seismic stations DGMT, EGMT, and LAO, located to the east of the Deep Probe and SAREX seismic line on the Wyoming craton/Medicine Hat block show the influence of sedimentary cover and a strong Ps phase at approximately four seconds after P. At BOZ and MSO, located in the Rocky mountains, the sedimentary cover signal previously noted is absent, and instead we observe a sharp Ps phase at about four and a half seconds after P. RFs at station RLMT (on the WC) are highly anomalous, probably reflecting complex conversions from two differently oriented dipping layers. We will use the RFs to produce suites of acceptable structural models to test for the presence and lateral extent of the 7x layer and other structural features of the Rocky Mountains-craton transition.

A non-contacting approach for full field dynamic strain monitoring of rotating structures using the photogrammetry, finite element, and modal expansion techniques

NASA Astrophysics Data System (ADS)

Baqersad, Javad

Health monitoring of rotating structures such as wind turbines and helicopter rotors is generally performed using conventional sensors that provide a limited set of data at discrete locations near or on the hub. These sensors usually provide no data on the blades or interior locations where failures may occur. Within this work, an unique expansion algorithm was extended and combined with finite element (FE) modeling and an optical measurement technique to identify the dynamic strain in rotating structures. The merit of the approach is shown by using the approach to predict the dynamic strain on a small non-rotating and rotating wind turbine. A three-bladed wind turbine having 2.3-meter long blades was placed in a semi-built-in boundary condition using a hub, a machining chuck, and a steel block. A finite element model of the three wind turbine blades assembled to the hub was created and used to extract resonant frequencies and mode shapes. The FE model was validated and updated using experimental modal tests. For the non-rotating optical test, the turbine was excited using a sinusoidal excitation, a pluck test, arbitrary impacts on three blades, and random force excitations with a mechanical shaker. The response of the structure to the excitations was measured using three-dimensional point tracking. A pair of high-speed cameras was used to measure the displacement of optical targets on the structure when the blades were vibrating. The measured displacements at discrete locations were expanded and applied to the finite element model of the structure to extract the full-field dynamic strain. The results of the work show an excellent correlation between the strain predicted using the proposed approach and the strain measured with strain-gages for all of the three loading conditions. Similar to the non-rotating case, optical measurements were also preformed on a rotating wind turbine. The point tracking technique measured both rigid body displacement and flexible deformation of the blades at target locations. The measured displacements were expanded and applied to the finite element model of the turbine to extract full-field dynamic strain on the structure. In order to validate the results for the rotating turbine, the predicted strain was compared to strain measured at four locations on the spinning blades using a wireless strain-gage system. The approach used in this work to predict the strain showed higher accuracy than measurements obtainable by using the digital image correlation technique. The new expansion approach is able to extract dynamic strain all over the entire structure, even inside the structure beyond the line of sight of the measurement system. Because the method is based on a non-contacting measurement approach, it can be readily applied to a variety of structures having different boundary and operating conditions, including rotating blades.

The Hartousov Mofette Field in the Cheb Basin, Western Eger Rift (Czech Republic/Europe): a Comperative Geoelectric, Sedimentologic and Soil Gas Study of a Magmatic Diffuse Degassing Structure

NASA Astrophysics Data System (ADS)

Flechsig, C.; Schuetze, C.; Bussert, R.

2008-12-01

The mofette field of Hartoušov is located in the Cheb Basin, a shallow Neogene intracontinental basin in Central Europe. The north-eastern part of the Cheb Basin is one of the most seismically active regions of Central Europe. Seismic activity in the Cheb Basin has mainly a swarm-like character. The numerous cold CO2 emanations (>99 Vol.% CO2) at the surface of the basin are supposed to be generally connected to the seismic activity and to stem from the upper mantle. The Hartoušov mofette field has been investigated by combining geophysical measurements (geoelectrical resistivity tomography, self potential) with sedimentological studies (grain size, Corg, mineralogy) and soil gas (CO2 flux and CO2 concentration) data. Key question of the research was to evaluate the structural and sedimentological control at a CO2 degassing location. The investigations reveal a positive correlation between areas of high soil gas (CO2) concentration and flux with geophysical anomalies (negative self potential, positive structures of low electrical resistivity) as well as with specific sediment properties (content of pyrite and organic material, occurrence of dispersed pebbles, uplifted clay layer). These features are thought to be directly or indirectly related to the magmatic caused CO2 flow. Soil gas (CO2) measurements indicate areas of high CO2 content to be marked by anomalous vegetation patterns. These anomalies spread out with a linear trend, suggesting a fault control on gas ascent. Places of highest gas flow form small hummocks, with minor depressions on top. Negative geoelectrical self potentials at such locations were interpreted considering as having been caused by a downward movement of the meteoric water balancing the upward CO2 flux. The top of a pre-Quaternary clay-rich unit with a high content of smectite is highest in the location nearest to the mofette showing the most intense CO2 emanation. Most probably the clays form a domal feature below this mofette, as confirmed by the 3-D geoelectric measurements by low electrical resistivities. The driving force behind the updoming of the clays might be the pressure of uprising CO2. Additionally, the more intense swelling of smectite due to higher rates of fluid flow at these locations might also contribute to this phenomenon. Isolated quartz pebbles dispersed in fine-grained sediments could have been transported upward by gas jets bonded to vents during periods or events of intense gas emanation. The model for the sedimentation at the active mofettes has to consider its bonding to deep-seated faults, the presence of sediment deformation structures due to gas pressure, upward transport of sediment particles by gas jets and reducing conditions caused by the magmatic CO2 flux.

Assessment of Genetic Diversity and Population Genetic Structure of Corylus mandshurica in China Using SSR Markers.

PubMed

Zong, Jian-Wei; Zhao, Tian-Tian; Ma, Qing-Hua; Liang, Li-Song; Wang, Gui-Xi

2015-01-01

Corylus mandshurica, also known as pilose hazelnut, is an economically and ecologically important species in China. In this study, ten polymorphic simple sequence repeat (SSR) markers were applied to evaluate the genetic diversity and population structure of 348 C. mandshurica individuals among 12 populations in China. The SSR markers expressed a relatively high level of genetic diversity (Na = 15.3, Ne = 5.6604, I = 1.8853, Ho = 0.6668, and He = 0.7777). According to the coefficient of genetic differentiation (Fst = 0.1215), genetic variation within the populations (87.85%) were remarkably higher than among populations (12.15%). The average gene flow (Nm = 1.8080) significantly impacts the genetic structure of C. mandshurica populations. The relatively high gene flow (Nm = 1.8080) among wild C. mandshurica may be caused by wind-pollinated flowers, highly nutritious seeds and self-incompatible mating system. The UPGMA (unweighted pair group method of arithmetic averages) dendrogram was divided into two main clusters. Moreover, the results of STRUCTURE analysis suggested that C. mandshurica populations fell into two main clusters. Comparison of the UPGMA dendrogram and the Bayesian STRUCTURE analysis showed general agreement between the population subdivisions and the genetic relationships among populations of C. mandshurica. Group I accessions were located in Northeast China, while Group II accessions were in North China. It is worth noting that a number of genetically similar populations were located in the same geographic region. The results further showed that there was obvious genetic differentiation among populations from Northeast China to North China. Results from the Mantel test showed a weak but still significant positive correlation between Nei's genetic distance and geographic distance (km) among populations (r = 0.419, P = 0.005), suggesting that genetic differentiation in the 12 C. mandshurica populations might be related to geographic distance. These data provide comprehensive information for the development of conservation strategies of these valuable hazelnut resources.

Assessing the population coverage of a health demographic surveillance system using satellite imagery and crowd-sourcing.

PubMed

Di Pasquale, Aurelio; McCann, Robert S; Maire, Nicolas

2017-01-01

Remotely sensed data can serve as an independent source of information about the location of residential structures in areas under demographic and health surveillance. We report on results obtained combining satellite imagery, imported from Bing, with location data routinely collected using the built-in GPS sensors of tablet computers, to assess completeness of population coverage in a Health and Demographic Surveillance System in Malawi. The Majete Malaria Project Health and Demographic Surveillance System, in Malawi, started in 2014 to support a project with the aim of studying the reduction of malaria using an integrated control approach by rolling out insecticide treated nets and improved case management supplemented with house improvement and larval source management. In order to support the monitoring of the trial a Health and Demographic Surveillance System was established in the area that surrounds the Majete Wildlife Reserve (1600 km2), using the OpenHDS data system. We compared house locations obtained using GPS recordings on mobile devices during the demographic surveillance census round with those acquired from satellite imagery. Volunteers were recruited through the crowdcrafting.org platform to identify building structures on the images, which enabled the compilation of a database with coordinates of potential residences. For every building identified on these satellite images by the volunteers (11,046 buildings identified of which 3424 (ca. 30%) were part of the censused area), we calculated the distance to the nearest house enumerated on the ground by fieldworkers during the census round of the HDSS. A random sample of buildings (85 structures) identified on satellite images without a nearby location enrolled in the census were visited by a fieldworker to determine how many were missed during the baseline census survey, if any were missed. The findings from this ground-truthing effort suggest that a high population coverage was achieved in the census survey, however the crowd-sourcing did not locate many of the inhabited structures (52.3% of the 6543 recorded during the census round). We conclude that using auxiliary data can play a useful role in quality assurance in population based health surveillance, but improved algorithms would be needed if crowd-sourced house locations are to be used as the basis of population databases.

a Climatology of Synoptic Scale Atmospheric Structure Prior to Severe Convective Storms

NASA Astrophysics Data System (ADS)

Taylor, Gregory Eugene

1982-03-01

This investigation determines those unique properties of the thermodynamic and kinematic structure of the atmosphere in the region where tornado bearing thunderstorms develop as compared to surrounding locations. One hundred five upper air soundings from the operational rawinsonde network, hereafter called tornado proximity soundings, comprise the core of the data base. In each instance, a confirmed tornado occurred within 50 statute miles of and within 105 minutes after the release of the radiosonde. In earlier research of this nature, the thermodynamic and kinematic properties of the atmosphere in the region of tornado bearing thunderstorm development were interpolated or inferred from upper air soundings made at locations surrounding the severe storm location. These surrounding locations, however, were characterized by at most non-tornado bearing thunderstorm development. In this investigation, however, measurements of the atmospheric structure near in space and time to the subsequent tornado bearing thunderstorm development have been utilized. This fact should enhance the probability of detecting the presumably unique properties of the atmospheric structure prior to severe storm development as compared to previous investigations. Height, temperature, mixing ratio, and U and V wind component data from the tornado proximity sounding station and surrounding upper air stations were objectively analyzed to a regularly spaced three dimensional grid network centered on the tornado proximity sounding station. From the basic data, a large number of derived variables which had been previously linked to severe storms were computed. Each case was categorized into one of six different classifications based on the geographical location and date of the tornado proximity sounding. The results from the six categories indicate that the most pronounced unique properties of the pre-severe storm environment are within the lower levels of the atmosphere. In particular, the low level moisture content and the low level V-component tended to maximize near the region of subsequent severe storm development in most of the six categories. Also, a number of variables which are highly dependent upon low level moisture content and/or low level wind data such as horizontal moisture flux and stability indices delineated well the region of subsequent severe storm development.

Deployable antenna kinematics using tensegrity structure design

NASA Astrophysics Data System (ADS)

Knight, Byron Franklin

With vast changes in spacecraft development over the last decade, a new, cheaper approach was needed for deployable kinematic systems such as parabolic antenna reflectors. Historically, these mesh-surface reflectors have resembled folded umbrellas, with incremental redesigns utilized to save packaging size. These systems are typically over-constrained designs, the assumption being that high reliability necessary for space operations requires this level of conservatism. But with the rapid commercialization of space, smaller launch platforms and satellite buses have demanded much higher efficiency from all space equipment than can be achieved through this incremental approach. This work applies an approach called tensegrity to deployable antenna development. Kenneth Snelson, a student of R. Buckminster Fuller, invented Tensegrity structures in 1948. Such structures use a minimum number of compression members (struts); stability is maintain using tension members (ties). The novelty introduced in this work is that the ties are elastic, allowing the struts to extend or contract, and in this way changing the surface of the antenna. Previously, the University of Florida developed an approach to quantify the stability and motion of parallel manipulators. This approach was applied to deployable, tensegrity, antenna structures. Based on the kinematic analyses for the 3-3 (octahedron) and 4-4 (square anti-prism) structures, the 6-6 (hexagonal anti-prism) analysis was completed which establishes usable structural parameters. The primary objective for this work was to prove the stability of this class of deployable structures, and their potential application to space structures. The secondary objective is to define special motions for tensegrity antennas, to meet the subsystem design requirements, such as addressing multiple antenna-feed locations. This work combines the historical experiences of the artist (Snelson), the mathematician (Ball), and the space systems engineer (Wertz) to develop a new, practical design approach. This kinematic analysis of tensegrity structures blends these differences to provide the design community with a new approach to lightweight, robust, adaptive structures with the high reliability that space demands. Additionally, by applying Screw Theory, a tensegrity structure antenna can be commanded to move along a screw axis, and therefore meeting the requirement to address multiple feed locations.

Use of optical coherence tomography in delineating airways microstructure: comparison of OCT images to histopathological sections

NASA Astrophysics Data System (ADS)

Yang, Ying; Whiteman, Suzanne; Gey van Pittius, Daniel; He, Yonghong; Wang, Ruikang K.; Spiteri, Monica A.

2004-04-01

An ideal diagnostic system for the human airways should be able to detect and define early development of premalignant pathological lesions, to facilitate optimal curative treatment and prevent irreversible and/or invasive lung disease. There is great need for exploration of safe, repeatable imaging techniques which can run at real-time and with high spatial resolution. In this study, optical coherence tomography (OCT) was utilized to acquire cross-sectional images of upper and lower airways using fresh pig lung resections as a model system. Obtained OCT images were compared with parallel tissue characterization by conventional histological analysis. Our objective was to determine whether OCT differentiates the composite structural layers and inherent anatomical variations along different airway locations. The data show that OCT can clearly display the multilayered structure of the airways. The subtle architectural differences in three separate anatomical locations including trachea, main bronchus and tertiary bronchus were clearly delineated. Images of the appropriate anatomical profiles, with depth of up to 2 mm and 10 µm spatial resolution were obtained by our current OCT system, which was sufficient for recognition of the epithelium, subepithelial tissues and cartilage. In addition, the relative thickness of individual structural components was accurately reflected and comparable to histological sections. These data support OCT as a highly feasible, optical biopsy tool, which merits further exploration for early diagnosis of human airway epithelial pathology.

Controls on coral-ground development along the northern Mesoamerican Reef tract.

PubMed

Rodríguez-Martínez, Rosa E; Jordán-Garza, Adán G; Maldonado, Miguel A; Blanchon, Paul

2011-01-01

Coral-grounds are reef communities that colonize rocky substratum but do not form framework or three-dimensional reef structures. To investigate why, we used video transects and underwater photography to determine the composition, structure and status of a coral-ground community located on the edge of a rocky terrace in front of a tourist park, Xcaret, in the northern Mesoamerican Reef tract, Mexico. The community has a relatively low coral, gorgonian and sponge cover (<10%) and high algal cover (>40%). We recorded 23 species of Scleractinia, 14 species of Gorgonacea and 30 species of Porifera. The coral community is diverse but lacks large coral colonies, being dominated instead by small, sediment-tolerant, and brooding species. In these small colonies, the abundance of potentially lethal interactions and partial mortality is high but decreases when colonies are larger than 40 cm. Such characteristics are consistent with an environment control whereby storm waves periodically remove larger colonies and elevate sediment flux. The community only survives these storm conditions due to its slope-break location, which ensures lack of burial and continued local recruitment. A comparison with similar coral-ground communities in adjacent areas suggests that the narrow width of the rock terrace hinders sediment stabilization, thereby ensuring that communities cannot escape bottom effects and develop into three-dimensional reef structures on geological time scales.

Investigating subduction reversal in Papua New Guinea from automatic analysis of seismicity recorded on a temporary local network

NASA Astrophysics Data System (ADS)

Hicks, S. P.; Harmon, N.; Rychert, C.; Tharimena, S.; Bogiatzis, P.; Savage, B.; Shen, Y.; Baillard, C.

2017-12-01

The area of Papua New Guinea is one of the most seismically active regions on the planet. Seismicity in the region results from oblique convergence between the Pacific and India-Australia plates, with deformation occurring across a broad region involving several microplates. The region gives an excellent natural laboratory to test geodynamic models of subduction polarity reversal, microplate interaction, and to delineate the structure of subducting plates and relic structures at depth. However, a lack of permanent seismic stations means that routine earthquake locations for small to intermediate sized earthquakes have significant location errors. In 2014, we deployed a temporary network of eight broadband stations on islands in eastern Papua New Guinea to record ongoing seismic deformation. The network straddles a complex region where subduction of the Solomon plate occurs to the south and possible subduction of the Ontong-Java plateau occurs to the north. The stations were installed for 27 months. During the deployment period, there were 13 M>6.5 earthquakes in the area, including M7.5 doublet events in 2015, giving a rich seismic dataset. A high-quality catalogue of local events was formed by a multi-step process. Using the scanloc module of SeisComp3, we first detect P-onsets using a STA/LTA detection. Once clusters of P onsets are found, S-wave picks are incorporated based on a pre-defined window length of maximum S-P time. Groups of onsets are then associated to events, giving us a starting catalogue of 269 events (1765 P-onsets) with minimum magnitude of M 3.5. In a second step, we refine onset times using a Kurtosis picker to improve location accuracy. To form robust hypocentral locations using an appropriate structural model for the area and to constrain crust and mantle structure in the region, we derive a minimum 1-D velocity model using the VELEST program. We use a starting model from Abers et al. (1991) and we restrict our catalogue to events with an azimuthal gap of <270°, leaving 147 well-located events. This new seismic catalogue gives a detailed insight into the plate boundary structures at depth in the Papua New Guinea region. We are also able to delineate Wadati-Benioff seismicity to 600 km depth in the subducting Solomon Sea plate beneath the New Britain arc.

Investigating subduction reversal in Papua New Guinea from automatic analysis of seismicity recorded on a temporary local network

NASA Astrophysics Data System (ADS)

Hicks, S. P.; Harmon, N.; Rychert, C.; Tharimena, S.; Bogiatzis, P.; Savage, B.; Shen, Y.; Baillard, C.

2016-12-01

The area of Papua New Guinea is one of the most seismically active regions on the planet. Seismicity in the region results from oblique convergence between the Pacific and India-Australia plates, with deformation occurring across a broad region involving several microplates. The region gives an excellent natural laboratory to test geodynamic models of subduction polarity reversal, microplate interaction, and to delineate the structure of subducting plates and relic structures at depth. However, a lack of permanent seismic stations means that routine earthquake locations for small to intermediate sized earthquakes have significant location errors. In 2014, we deployed a temporary network of eight broadband stations on islands in eastern Papua New Guinea to record ongoing seismic deformation. The network straddles a complex region where subduction of the Solomon plate occurs to the south and possible subduction of the Ontong-Java plateau occurs to the north. The stations were installed for 27 months. During the deployment period, there were 13 M>6.5 earthquakes in the area, including M7.5 doublet events in 2015, giving a rich seismic dataset. A high-quality catalogue of local events was formed by a multi-step process. Using the scanloc module of SeisComp3, we first detect P-onsets using a STA/LTA detection. Once clusters of P onsets are found, S-wave picks are incorporated based on a pre-defined window length of maximum S-P time. Groups of onsets are then associated to events, giving us a starting catalogue of 269 events (1765 P-onsets) with minimum magnitude of M 3.5. In a second step, we refine onset times using a Kurtosis picker to improve location accuracy. To form robust hypocentral locations using an appropriate structural model for the area and to constrain crust and mantle structure in the region, we derive a minimum 1-D velocity model using the VELEST program. We use a starting model from Abers et al. (1991) and we restrict our catalogue to events with an azimuthal gap of <270°, leaving 147 well-located events. This new seismic catalogue gives a detailed insight into the plate boundary structures at depth in the Papua New Guinea region. We are also able to delineate Wadati-Benioff seismicity to 600 km depth in the subducting Solomon Sea plate beneath the New Britain arc.

Origin and migration of hydrocarbon gases and carbon dioxide, Bekes Basin, southeastern Hungary

USGS Publications Warehouse

Clayton, J.L.; Spencer, C.W.; Koncz, I.; Szalay, A.

1990-01-01

The Bekes Basin is a sub-basin within the Pannonian Basin, containing about 7000 m of post-Cretaceous sedimentary rocks. Natural gases are produced from reservoirs (Precambrian to Tertiary in age) located on structural highs around the margins of the basin. Gas composition and stable carbon isotopic data indicate that most of the flammable gases were derived from humic kerogen contained in source rocks located in the deep basin. The depth of gas generation and vertical migration distances were estimated using quantitative source rock maturity-carbon isotope relationships for methane compared to known Neogene source rock maturity-depth relationships in the basin. These calculations indicate that as much as 3500 m of vertical migration has occured in some cases. Isotopically heavy (> - 7 > 0) CO2 is the predominant species present in some shallow reservoirs located on basin-margin structural highs and has probably been derived via long-distance vertical and lateral migration from thermal decompositon of carbonate minerals in Mesozoic and older rocks in the deepest parts of the basin. A few shallow reservoirs (< 2000m) contain isotopically light (-50 to -60%0) methane with only minor amounts of C2+ homologs (< 3% v/v). This methane is probably mostly microbial in origin. Above-normal pressures, occuring at depths greater than 1800 m, are believed to be the principal driving force for lateral and vertical gas migration. These pressures are caused in part by active hydrocarbon generation, undercompaction, and thermal decomposition of carbonates. 

High-Frequency, High-Temperature Fretting Experiments

NASA Technical Reports Server (NTRS)

Matlik, J. F.; Farris, T. N.; Haake, F. K.; Swanson, G. R.; Duke, G. C.

2005-01-01

Fretting is a structural damage mechanism observed when two nominally clamped surfaces are subjected to an oscillatory loading. A critical location for fretting induced damage has been identified at the blade/disk and blade/damper interfaces of gas turbine engine turbomachinery and space propulsion components. The high-temperature, high-frequency loading environment seen by these components lead to severe stress gradients at the edge-of-contact. These contact stresses drive crack nucleation and propagation in fretting and are very sensitive to the geometry of the contacting bodies, the contact loads, materials, temperature, and contact surface tribology (friction). To diagnose the threat that small and relatively undetectable fretting cracks pose to damage tolerance and structural integrity of in-service components, the objective of this work is to develop a well-characterized experimental fretting rig capable of investigating fretting behavior of advanced aerospace alloys subjected to load and temperature conditions representative of such turbomachinery components.

Application of level set method to optimal vibration control of plate structures

NASA Astrophysics Data System (ADS)

Ansari, M.; Khajepour, A.; Esmailzadeh, E.

2013-02-01

Vibration control plays a crucial role in many structures, especially in the lightweight ones. One of the most commonly practiced method to suppress the undesirable vibration of structures is to attach patches of the constrained layer damping (CLD) onto the surface of the structure. In order to consider the weight efficiency of a structure, the best shapes and locations of the CLD patches should be determined to achieve the optimum vibration suppression with minimum usage of the CLD patches. This paper proposes a novel topology optimization technique that can determine the best shape and location of the applied CLD patches, simultaneously. Passive vibration control is formulated in the context of the level set method, which is a numerical technique to track shapes and locations concurrently. The optimal damping set could be found in a structure, in its fundamental vibration mode, such that the maximum modal loss factor of the system is achieved. Two different plate structures will be considered and the damping patches will be optimally located on them. At the same time, the best shapes of the damping patches will be determined too. In one example, the numerical results will be compared with those obtained from the experimental tests to validate the accuracy of the proposed method. This comparison reveals the effectiveness of the level set approach in finding the optimum shape and location of the CLD patches.

Silicon nitride ceramic development in Thales Alenia Space : qualification achievement and further developments for future applications

NASA Astrophysics Data System (ADS)

Cornillon, L.; Devilliers, C.; Behar-Lafenetre, S.; Ait-Zaid, S.; Berroth, K.; Bravo, A. C.

2017-11-01

Dealing with ceramic materials for more than two decades, Thales Alenia Space - France has identified Silicon Nitride Si3N4 as a high potential material for the manufacturing of stiff, stable and lightweight truss structure for future large telescopes. Indeed, for earth observation or astronomic observation, space mission requires more and more telescopes with high spatial resolution, which leads to the use of large primary mirrors, and a long distance between primary and secondary mirrors. Therefore current and future large space telescopes require a huge truss structure to hold and locate precisely the mirrors. Such large structure requires very strong materials with high specific stiffness and a low coefficient of thermal expansion (CTE). Based on the silicon nitride performances and on the know how of FCT Ingenieurkeramik to manufacture complex parts, Thales Alenia Space (TAS) has engaged, in cooperation with FCT, activities to develop and qualify silicon nitride parts for other applications for space projects.

Silicon nitride ceramic development in Thales Alenia Space: qualification achiement and further developments for future applications

NASA Astrophysics Data System (ADS)

Cornillon, L.; Devilliers, C.; Behar-Lafenetre, S.; Ait-Zaid, S.; Berroth, K.; Bravo, A. C.

2017-11-01

Dealing with ceramic materials for more than two decades, Thales Alenia Space - France has identified Silicon Nitride Si3N4 as a high potential material for the manufacturing of stiff, stable and lightweight truss structure for future large telescopes. Indeed, for earth observation or astronomic observation, space mission requires more and more telescopes with high spatial resolution, which leads to the use of large primary mirrors, and a long distance between primary and secondary mirrors. Therefore current and future large space telescopes require a huge truss structure to hold and locate precisely the mirrors. Such large structure requires very strong materials with high specific stiffness and a low coefficient of thermal expansion (CTE). Based on the silicon nitride performances and on the know how of FCT Ingenieurkeramik to manufacture complex parts, Thales Alenia Space (TAS) has engaged, in cooperation with FCT, activities to develop and qualify silicon nitride parts for other applications for space projects.

A Close Look At The Relationship Between WMAP (ILC) Small-Scale Features And Galactic HI Structure

NASA Astrophysics Data System (ADS)

Verschuur, Gerrit L.

2012-05-01

Galactic HI emission profiles surrounding two pairs of features located where large-scale filaments at very different velocities overlap were decomposed into Gaussian components. Families of components defined by similarity of center velocities and line widths were identified and found to be spatially related. Each of the two pairs of HI peaks straddle a high-frequency continuum source revealed in the WMAP survey data. It is suggested that where filamentary HI features are directly interacting high-frequency continuum radiation is being produced. The previously hypothesized mechanism for producing high-frequency continuum radiation involving free-free emission from electrons in the interstellar medium, in this case created where HI filaments interact to produce fractional ionizations of order 5 to 15%, fit the data very closely. The results confirm that WMAP data on small-scale structures believed to be cosmological in origin are in fact compromised by the presence of intervening galactic sources of interstellar electrons clumped on scales typical of interstellar HI structure.

Full-Field Measurements of Self-Excited Oscillations in Momentum-Dominated Helium Jets

NASA Technical Reports Server (NTRS)

Yildirim, B. S.; Agrawal, A. K.

2005-01-01

Flow structure of momentum-dominated helium jets discharged vertically into ambient air was investigated using a high-speed rainbow schlieren deflectometry (RSD) apparatus operated at up to 2000 Hz. The operating parameters, i.e., Reynolds number and Richardson number were varied independently to examine the self-excited, flow oscillatory behavior over a range of experimental conditions. Measurements revealed highly periodic oscillations in the laminar region at a unique frequency as well as high regularity in the flow transition and initial turbulent regions. The buoyancy was shown to affect the oscillation frequency and the distance from the jet exit to the flow transition plane. Instantaneous helium concentration contours across the field of view revealed changes in the jet flow structure and the evolution of the vortical structures during an oscillation cycle. A cross-correlation technique was applied to track the vortices and to find their convection velocity. Time-traces of helium concentration at different axial locations provided detailed information about the oscillating flow.

S-velocity structure in Cimandiri fault zone derived from neighbourhood inversion of teleseismic receiver functions

NASA Astrophysics Data System (ADS)

Syuhada; Anggono, T.; Febriani, F.; Ramdhan, M.

2018-03-01

The availability information about realistic velocity earth model in the fault zone is crucial in order to quantify seismic hazard analysis, such as ground motion modelling, determination of earthquake locations and focal mechanism. In this report, we use teleseismic receiver function to invert the S-velocity model beneath a seismic station located in the Cimandiri fault zone using neighbourhood algorithm inversion method. The result suggests the crustal thickness beneath the station is about 32-38 km. Furthermore, low velocity layers with high Vp/Vs exists in the lower crust, which may indicate the presence of hot material ascending from the subducted slab.

A Double-difference Earthquake location algorithm: Method and application to the Northern Hayward Fault, California

USGS Publications Warehouse

Waldhauser, F.; Ellsworth, W.L.

2000-01-01

We have developed an efficient method to determine high-resolution hypocenter locations over large distances. The location method incorporates ordinary absolute travel-time measurements and/or cross-correlation P-and S-wave differential travel-time measurements. Residuals between observed and theoretical travel-time differences (or double-differences) are minimized for pairs of earthquakes at each station while linking together all observed event-station pairs. A least-squares solution is found by iteratively adjusting the vector difference between hypocentral pairs. The double-difference algorithm minimizes errors due to unmodeled velocity structure without the use of station corrections. Because catalog and cross-correlation data are combined into one system of equations, interevent distances within multiplets are determined to the accuracy of the cross-correlation data, while the relative locations between multiplets and uncorrelated events are simultaneously determined to the accuracy of the absolute travel-time data. Statistical resampling methods are used to estimate data accuracy and location errors. Uncertainties in double-difference locations are improved by more than an order of magnitude compared to catalog locations. The algorithm is tested, and its performance is demonstrated on two clusters of earthquakes located on the northern Hayward fault, California. There it colapses the diffuse catalog locations into sharp images of seismicity and reveals horizontal lineations of hypocenter that define the narrow regions on the fault where stress is released by brittle failure.

The complex architecture of the 2009 MW 6.1 L'Aquila normal fault system (Central Italy) as imaged by 64,000 high-resolution aftershock locations

NASA Astrophysics Data System (ADS)

Valoroso, L.; Chiaraluce, L.; Di Stefano, R.; Piccinini, D.; Schaff, D. P.; Waldhauser, F.

2011-12-01

On April 6th 2009, a MW 6.1 normal faulting earthquake struck the axial area of the Abruzzo region in Central Italy. We present high-precision hypocenter locations of an extraordinary dataset composed by 64,000 earthquakes recorded at a very dense seismic network of 60 stations operating for 9 months after the main event. Events span in magnitude (ML) between -0.9 to 5.9, reaching a completeness magnitude of 0.7. The dataset has been processed by integrating an accurate automatic picking procedure together with cross-correlation and double-difference relative location methods. The combined use of these procedures results in earthquake relative location uncertainties in the range of a few meters to tens of meters, comparable/lower than the spatial dimension of the earthquakes themselves). This data set allows us to image the complex inner geometry of individual faults from the kilometre to meter scale. The aftershock distribution illuminates the anatomy of the en-echelon fault system composed of two major faults. The mainshock breaks the entire upper crust from 10 km depth to the surface along a 14-km long normal fault. A second segment, located north of the normal fault and activated by two Mw>5 events, shows a striking listric geometry completely blind. We focus on the analysis of about 300 clusters of co-located events to characterize the mechanical behavior of the different portions of the fault system. The number of events in each cluster ranges from 4 to 24 events and they exhibit strongly correlated seismograms at common stations. They mostly occur where secondary structures join the main fault planes and along unfavorably oriented segments. Moreover, larger clusters nucleate on secondary faults located in the overlapping area between the two main segments, where the rate of earthquake production is very high with a long-lasting seismic decay.

Standoff spectroscopic interrogation of samples irradiated by high energy lasers

NASA Astrophysics Data System (ADS)

Daigle, Jean-François; Pudo, Dominik; Théberge, Francis

2017-10-01

We report on a novel method that shows the potential to provide real-time, standoff forensic analysis of samples being irradiated by a high energy laser (HEL). The interaction of the HEL beam with matter produces specific optical signatures that can be detected from the location of the HEL system. A spectroscopic analysis of these signals can then provide useful information to the operator including the impact the laser has on the sample as well as providing data about the its structure and composition.

Arteriovenous fistula complicating iliac artery pseudo aneurysm: diagnosis by CT angiography.

PubMed

Huawei, L; Bei, D; Huan, Z; Zilai, P; Aorong, T; Kemin, C

2002-01-01

Fistula formation to the inferior vena cava is a rare complication of aortic aneurysm which is often misdiagnosed clinically. In one hundred of reported arteriocaval fistulae, none was originating from the right common iliac artery. We report a case of ileo-caval fistula due to a iatrogenic pseudoaneurysm. High resolution 3D imaging using breath-hold CT angiography is highly specific in identifying the location, extent of the aortocaval fistula as well as the neighbouring anatomic structures.

Latitudinal variation in population structure of wintering Pacific Black Brant

USGS Publications Warehouse

Schamber, J.L.; Sedinger, J.S.; Ward, D.H.; Hagmeier, K.R.

2007-01-01

Latitudinal variation in population structure during the winter has been reported in many migratory birds, but has been documented in few species of waterfowl. Variation in environmental and social conditions at wintering sites can potentially influence the population dynamics of differential migrants. We examined latitudinal variation in sex and age classes of wintering Pacific Black Brant (Branta bernicla nigricans). Brant are distributed along a wide latitudinal gradient from Alaska to Mexico during the winter. Accordingly, migration distances for brant using different wintering locations are highly variable and winter settlement patterns are likely associated with a spatially variable food resource. We used resightings of brant banded in southwestern Alaska to examine sex and age ratios of birds wintering at Boundary Bay in British Columbia, and at San Quintin Bay, Ojo de Liebre Lagoon, and San Ignacio Lagoon in Baja California from 1998 to 2000. Sex ratios were similar among wintering locations for adults and were consistent with the mating strategy of geese. The distribution of juveniles varied among wintering areas, with greater proportions of juveniles observed at northern (San Quintin Bay and Ojo de Liebre Lagoon) than at southern (San Ignacio Lagoon) locations in Baja California. We suggest that age-related variation in the winter distribution of Pacific Black Brant is mediated by variation in productivity among individuals at different wintering locations and by social interactions among wintering family groups.

Age-related changes in the topological organization of the white matter structural connectome across the human lifespan.

PubMed

Zhao, Tengda; Cao, Miao; Niu, Haijing; Zuo, Xi-Nian; Evans, Alan; He, Yong; Dong, Qi; Shu, Ni

2015-10-01

Lifespan is a dynamic process with remarkable changes in brain structure and function. Previous neuroimaging studies have indicated age-related microstructural changes in specific white matter tracts during development and aging. However, the age-related alterations in the topological architecture of the white matter structural connectome across the human lifespan remain largely unknown. Here, a cohort of 113 healthy individuals (ages 9-85) with both diffusion and structural MRI acquisitions were examined. For each participant, the high-resolution white matter structural networks were constructed by deterministic fiber tractography among 1024 parcellation units and were quantified with graph theoretical analyses. The global network properties, including network strength, cost, topological efficiency, and robustness, followed an inverted U-shaped trajectory with a peak age around the third decade. The brain areas with the most significantly nonlinear changes were located in the prefrontal and temporal cortices. Different brain regions exhibited heterogeneous trajectories: the posterior cingulate and lateral temporal cortices displayed prolonged maturation/degeneration compared with the prefrontal cortices. Rich-club organization was evident across the lifespan, whereas hub integration decreased linearly with age, especially accompanied by the loss of frontal hubs and their connections. Additionally, age-related changes in structural connections were predominantly located within and between the prefrontal and temporal modules. Finally, based on the graph metrics of structural connectome, accurate predictions of individual age were obtained (r = 0.77). Together, the data indicated a dynamic topological organization of the brain structural connectome across human lifespan, which may provide possible structural substrates underlying functional and cognitive changes with age. © 2015 Wiley Periodicals, Inc.

New Perspectives on Southern Ocean Frontal Variability

NASA Astrophysics Data System (ADS)

Chapman, Christopher

2017-04-01

The frontal structure of the Southern Ocean is investigated using a the Wavelet/Higher Order Statistics Enhancement (WHOSE) frontal detection method, introduced in Chapman (2014). This methodology is applied to 21 years of daily gridded sea-surface height (SSH) data to obtain daily maps of the locations of the fronts. By forming frontal occurrence frequency maps and then approximating these occurrence-maps by a superposition of simple functions, the time-mean locations of the fronts, as well as a measure of their capacity to meander, are obtained and related to the frontal locations found by previous studies. The spatial and temporal variability of the frontal structure is then considered. The number of fronts is found to be highly variable throughout the Southern Ocean, increasing (`splitting') downstream of large bathymetric features and decreasing (`merging') in regions where the fronts are tightly controlled by the underlying topography. In contrast, frontal meandering remains relatively constant. Contrary to many previous studies, little no southward migration of the fronts over the 1993-2014 time period is found, and there is only weak sensitivity to atmospheric forcing related to SAM or ENSO. Finally, the implications of splitting and merging for the flux of tracers will be discussed.

Organ of Corti Micromechanics with Local Electrical Stimulation

NASA Astrophysics Data System (ADS)

Chen, Fangyi; Zheng, Jiefu; Choudhury, Niloy; Jaques, Steve; Nuttall, Alfred L.

2009-02-01

Optical low coherence interferometry is able to both image and measure the vibration of the cellular and non-cellular structures of the organ of Corti in vivo. In this study we applied an electric current to the basal turn from a pair of electrodes, one in scala tympani and the other in scala vestibuli, at the location corresponding to ~17 kHz when interferometry measurements were made. The coherence gate of the interferometer was positioned 1) at the basilar membrane (BM) near the radial location of the outer hair cells (OHCs) (approximately 1/2 the width of the BM) and 2) at the reticular lamina (RL) where the OHCs are located. We confirmed that electrical stimulation with a frequency sweep (12 kHz -25 kHz) caused a mechanical BM displacement with a peak and a traveling wave-like phase delay as we reported previously using laser Doppler velocimetry and reflective beads on the BM. Reflective beads were not used in the current study. The vibration of the RL had little or no phase delay that would characterize a traveling wave. These data suggest a very high compliance system for the electrically activated cellular structure of the organ.

Genetic Pathway of HIV-1 Resistance to Novel Fusion Inhibitors Targeting the Gp41 Pocket

PubMed Central

Su, Yang; Chong, Huihiui; Xiong, Shengwen; Qiao, Yuanyuan; Qiu, Zonglin

2015-01-01

ABSTRACT The peptide drug enfuvirtide (T20) is the only HIV-1 fusion inhibitor in clinical use, but it easily induces drug resistance, calling for new strategies for developing effective drugs. On the basis of the M-T hook structure, we recently developed highly potent short-peptide HIV-1 fusion inhibitors (MTSC22 and HP23), which mainly target the conserved gp41 pocket and possess high genetic barriers to resistance. Here, we focused on the selection and characterization of HIV-1 escape mutants of MTSC22, which revealed new resistance pathways and mechanisms. Two mutations (E49K and L57R) located at the inhibitor-binding site and two mutations (N126K and E136G) located at the C-terminal heptad repeat region of gp41 were identified as conferring high resistance either singly or in combination. While E49K reduced the C-terminal binding of inhibitors via an electrostatic repulsion, L57R dramatically disrupted the N-terminal binding of M-T hook structure and pocket-binding domain. Unlike E49K and N126K, which enhanced the stability of the endogenous viral six-helical bundle core (6-HB), L57R and E136G conversely destabilized the 6-HB structure. We also demonstrated that both primary and secondary mutations caused the structural changes in 6-HB and severely impaired the capability for HIV-1 entry. Collectively, our data provide novel insights into the mechanisms of short-peptide fusion inhibitors targeting the gp41 pocket site and help increase our understanding of the structure and function of gp41 and HIV-1 evolution. IMPORTANCE The deep pocket on the N-trimer of HIV-1 gp41 has been considered an ideal drug target because of its high degree of conservation and essential role in viral entry. Short-peptide fusion inhibitors, which contain an M-T hook structure and mainly target the pocket site, show extremely high binding and inhibitory activities as well as high genetic barriers to resistance. In this study, the HIV-1 mutants resistant to MTSC22 were selected and characterized, which revealed that the E49K and L57R substitutions at the inhibitor-binding site and the N126K and E136G substitutions at the C-terminal heptad repeat region of gp41 critically determine the resistance phenotype. The data provide novel insights into the mechanisms of action of the M-T hook structure-based fusion inhibitors which will help further our understanding of the structure-function relationship of gp41 and molecular pathways of HIV-1 evolution and eventually facilitate the development of new anti-HIV drugs. PMID:26446597

Marine magnetotellurics imaged no distinct plume beneath the Tristan da Cunha hotspot in the southern Atlantic Ocean

NASA Astrophysics Data System (ADS)

Baba, Kiyoshi; Chen, Jin; Sommer, Malte; Utada, Hisashi; Geissler, Wolfram H.; Jokat, Wilfried; Jegen, Marion

2017-10-01

The Tristan da Cunha (TDC) is a volcanic island located above a prominent hotspot in the Atlantic Ocean. Many geological and geochemical evidences support a deep origin of the mantle material feeding the hotspot. However, the existence of a plume has not been confirmed as an anomalous structure in the mantle resolved by geophysical data because of lack of the observations in the area. Marine magnetotelluric and seismological observations were conducted in 2012-2013 to examine the upper mantle structure adjacent to TDC. The electrical conductivity structure of the upper mantle beneath the area was investigated in this study. Three-dimensional inversion analysis depicted a high conductive layer at 120 km depth but no distinct plume-like vertical structure. The conductive layer is mostly flat independently on seafloor age and bulges upward beneath the lithospheric segment where the TDC islands are located compared to younger segment south of the TDC Fracture Zone, while the bathymetry is rather deeper than prediction for the northern segment. The apparent inconsistency between the absence of vertical structure in this study and geochemical evidences on deep origin materials suggests that either the upwelling is too small and/or weak to be resolved by the current data set or that the upwelling takes place elsewhere outside of the study area. Other observations suggest that 1) the conductivity of the upper mantle can be explained by the fact that the mantle above the high conductivity layer is depleted in volatiles as the result of partial melting beneath the spreading ridge, 2) the potential temperature of the segments north of the TDC Fracture Zone is lower than that of the southern segment at least during the past 30 Myr.

Automated laser-based barely visible impact damage detection in honeycomb sandwich composite structures

NASA Astrophysics Data System (ADS)

Girolamo, D.; Girolamo, L.; Yuan, F. G.

2015-03-01

Nondestructive evaluation (NDE) for detection and quantification of damage in composite materials is fundamental in the assessment of the overall structural integrity of modern aerospace systems. Conventional NDE systems have been extensively used to detect the location and size of damages by propagating ultrasonic waves normal to the surface. However they usually require physical contact with the structure and are time consuming and labor intensive. An automated, contactless laser ultrasonic imaging system for barely visible impact damage (BVID) detection in advanced composite structures has been developed to overcome these limitations. Lamb waves are generated by a Q-switched Nd:YAG laser, raster scanned by a set of galvano-mirrors over the damaged area. The out-of-plane vibrations are measured through a laser Doppler Vibrometer (LDV) that is stationary at a point on the corner of the grid. The ultrasonic wave field of the scanned area is reconstructed in polar coordinates and analyzed for high resolution characterization of impact damage in the composite honeycomb panel. Two methodologies are used for ultrasonic wave-field analysis: scattered wave field analysis (SWA) and standing wave energy analysis (SWEA) in the frequency domain. The SWA is employed for processing the wave field and estimate spatially dependent wavenumber values, related to discontinuities in the structural domain. The SWEA algorithm extracts standing waves trapped within damaged areas and, by studying the spectrum of the standing wave field, returns high fidelity damage imaging. While the SWA can be used to locate the impact damage in the honeycomb panel, the SWEA produces damage images in good agreement with X-ray computed tomographic (X-ray CT) scans. The results obtained prove that the laser-based nondestructive system is an effective alternative to overcome limitations of conventional NDI technologies.

Prediction of Ordered Water Molecules in Protein Binding Sites from Molecular Dynamics Simulations: The Impact of Ligand Binding on Hydration Networks.

PubMed

Rudling, Axel; Orro, Adolfo; Carlsson, Jens

2018-02-26

Water plays a major role in ligand binding and is attracting increasing attention in structure-based drug design. Water molecules can make large contributions to binding affinity by bridging protein-ligand interactions or by being displaced upon complex formation, but these phenomena are challenging to model at the molecular level. Herein, networks of ordered water molecules in protein binding sites were analyzed by clustering of molecular dynamics (MD) simulation trajectories. Locations of ordered waters (hydration sites) were first identified from simulations of high resolution crystal structures of 13 protein-ligand complexes. The MD-derived hydration sites reproduced 73% of the binding site water molecules observed in the crystal structures. If the simulations were repeated without the cocrystallized ligands, a majority (58%) of the crystal waters in the binding sites were still predicted. In addition, comparison of the hydration sites obtained from simulations carried out in the absence of ligands to those identified for the complexes revealed that the networks of ordered water molecules were preserved to a large extent, suggesting that the locations of waters in a protein-ligand interface are mainly dictated by the protein. Analysis of >1000 crystal structures showed that hydration sites bridged protein-ligand interactions in complexes with different ligands, and those with high MD-derived occupancies were more likely to correspond to experimentally observed ordered water molecules. The results demonstrate that ordered water molecules relevant for modeling of protein-ligand complexes can be identified from MD simulations. Our findings could contribute to development of improved methods for structure-based virtual screening and lead optimization.

Resonant tunneling through electronic trapping states in thin MgO magnetic junctions.

PubMed

Teixeira, J M; Ventura, J; Araujo, J P; Sousa, J B; Wisniowski, P; Cardoso, S; Freitas, P P

2011-05-13

We report an inelastic electron tunneling spectroscopy study on MgO magnetic junctions with thin barriers (0.85-1.35 nm). Inelastic electron tunneling spectroscopy reveals resonant electronic trapping within the barrier for voltages V>0.15  V. These trapping features are associated with defects in the barrier crystalline structure, as confirmed by high-resolution transmission electron microscopy. Such defects are responsible for resonant tunneling due to energy levels that are formed in the barrier. A model was applied to determine the average location and energy level of the traps, indicating that they are mostly located in the middle of the MgO barrier, in accordance with the high-resolution transmission electron microscopy data and trap-assisted tunneling conductance theory. Evidence of the influence of trapping on the voltage dependence of tunnel magnetoresistance is shown.

High-resolution forest mapping for behavioural studies in the Nature Reserve ‘Les Nouragues’, French Guiana

PubMed Central

Ringler, Max; Mangione, Rosanna; Pašukonis, Andrius; Rainer, Gerhard; Gyimesi, Kristin; Felling, Julia; Kronaus, Hannes; Réjou-Méchain, Maxime; Chave, Jérôme; Reiter, Karl; Ringler, Eva

2015-01-01

For animals with spatially complex behaviours at relatively small scales, the resolution of a global positioning system (GPS) receiver location is often below the resolution needed to correctly map animals’ spatial behaviour. Natural conditions such as canopy cover, canyons or clouds can further degrade GPS receiver reception. Here we present a detailed, high-resolution map of a 4.6 ha Neotropical river island and a 8.3 ha mainland plot with the location of every tree >5 cm DBH and all structures on the forest floor, which are relevant to our study species, the territorial frog Allobates femoralis (Dendrobatidae). The map was derived using distance- and compass-based survey techniques, rooted on dGPS reference points, and incorporates altitudinal information based on a LiDAR survey of the area. PMID:27053943

Structure and properties of microporous titanosilicate determined by first-principles calculations

NASA Astrophysics Data System (ADS)

Ching, W. Y.; Xu, Yong-Nian; Gu, Zong-Quan

1996-12-01

The structure of EST-10, a member of synthetic microporous titanosilicates, was recently determined by an ingenious combination of experimental and simulational techniques. However, the locations of the alkali atoms in the framework remain elusive and its electronic structure is totally unknown. Based on first-principles local density calculations, the possible locations of the alkali atoms are identified and its electronic structure and bonding fully elucidated. ETS-10 is a semiconductor with a direct band gap of 2.33 eV. The Na atoms are likely to locate inside the seven-member ring pore adjacent to the one-dimensional Ti-O-Ti-O- chain.

Autonomous Assembly of Modular Structures in Space and on Extraterrestrial Locations

NASA Astrophysics Data System (ADS)

Alhorn, Dean C.

2005-02-01

The new U.S. National Vision for Space Exploration requires many new enabling technologies to accomplish the goals of space commercialization and returning humans to the moon and extraterrestrial environments. Traditionally, flight elements are complete sub-systems requiring humans to complete the integration and assembly. These bulky structures also require the use of heavy launch vehicles to send the units to a desired location. This philosophy necessitates a high degree of safety, numerous space walks at a significant cost. Future space mission costs must be reduced and safety increased to reasonably achieve exploration goals. One proposed concept is the autonomous assembly of space structures. This concept is an affordable, reliable solution to in-space and extraterrestrial assembly. Assembly is autonomously performed when two components join after determining that specifications are correct. Local sensors continue monitor joint integrity post assembly, which is critical for safety and structural reliability. Achieving this concept requires a change in space structure design philosophy and the development of innovative technologies to perform autonomous assembly. Assembly of large space structures will require significant numbers of integrity sensors. Thus simple, low-cost sensors are integral to the success of this concept. This paper addresses these issues and proposes a novel concept for assembling space structures autonomously. Core technologies required to achieve in space assembly are presented. These core technologies are critical to the goal of utilizing space in a cost efficient and safe manner. Additionally, these novel technologies can be applied to other systems both on earth and extraterrestrial environments.

Autonomous Assembly of Modular Structures in Space and on Extraterrestrial Locations

NASA Technical Reports Server (NTRS)

Alhorn, Dean C.

2005-01-01

The new U.S. National Vision for Space Exploration requires many new enabling technologies to accomplish the goals of space commercialization and returning humans to the moon and extraterrestrial environments. Traditionally, flight elements are complete subsystems requiring humans to complete the integration and assembly. These bulky structures also require the use of heavy launch vehicles to send the units to a desired location. This philosophy necessitates a high degree of safety, numerous space walks at a significant cost. Future space mission costs must be reduced and safety increased to reasonably achieve exploration goals. One proposed concept is the autonomous assembly of space structures. This concept is an affordable, reliable solution to in-space and extraterrestrial assembly. Assembly is autonomously performed when two components join after determining that specifications are correct. Local sensors continue monitor joint integrity post assembly, which is critical for safety and structural reliability. Achieving this concept requires a change in space structure design philosophy and the development of innovative technologies to perform autonomous assembly. Assembly of large space structures will require significant numbers of integrity sensors. Thus simple, low-cost sensors are integral to the success of this concept. This paper addresses these issues and proposes a novel concept for assembling space structures autonomously. Core technologies required to achieve in space assembly are presented. These core technologies are critical to the goal of utilizing space in a cost efficient and safe manner. Additionally, these novel technologies can be applied to other systems both on earth and extraterrestrial environments.

Recognition of coarse-grained protein tertiary structure.

PubMed

Lezon, Timothy; Banavar, Jayanth R; Maritan, Amos

2004-05-15

A model of the protein backbone is considered in which each residue is characterized by the location of its C(alpha) atom and one of a discrete set of conformal (phi, psi) states. We investigate the key differences between a description that offers a locally precise fit to known backbone structures and one that provides a globally accurate fit to protein structures. Using a statistical scoring scheme and threading, a protein's local best-fit conformation is highly recognizable, but its global structure cannot be directly determined from an amino acid sequence. The incorporation of information about the conformal states of neighboring residues along the chain allows one to accurately translate the local structure into a global structure. We present a two-step algorithm, which recognizes up to 95% of the tested protein native-state structures to within a 2.5 A root mean square deviation. Copyright 2004 Wiley-Liss, Inc.

Housing arrangement and location determine the likelihood of housing loss due to wildfire

USGS Publications Warehouse

Syphard, Alexandra D.; Keeley, Jon E.; Massada, Avi Bar; Brennan, Teresa J.; Radeloff, Volker C.

2012-01-01

Surging wildfires across the globe are contributing to escalating residential losses and have major social, economic, and ecological consequences. The highest losses in the U.S. occur in southern California, where nearly 1000 homes per year have been destroyed by wildfires since 2000. Wildfire risk reduction efforts focus primarily on fuel reduction and, to a lesser degree, on house characteristics and homeowner responsibility. However, the extent to which land use planning could alleviate wildfire risk has been largely missing from the debate despite large numbers of homes being placed in the most hazardous parts of the landscape. Our goal was to examine how housing location and arrangement affects the likelihood that a home will be lost when a wildfire occurs. We developed an extensive geographic dataset of structure locations, including more than 5500 structures that were destroyed or damaged by wildfire since 2001, and identified the main contributors to property loss in two extensive, fire-prone regions in southern California. The arrangement and location of structures strongly affected their susceptibility to wildfire, with property loss most likely at low to intermediate structure densities and in areas with a history of frequent fire. Rates of structure loss were higher when structures were surrounded by wildland vegetation, but were generally higher in herbaceous fuel types than in higher fuel-volume woody types. Empirically based maps developed using housing pattern and location performed better in distinguishing hazardous from non-hazardous areas than maps based on fuel distribution. The strong importance of housing arrangement and location indicate that land use planning may be a critical tool for reducing fire risk, but it will require reliable delineations of the most hazardous locations.

Simultaneous Determination of Structure and Event Location Using Body and Surface Wave Measurements at a Single Station: Preparation for Mars Data from the InSight Mission

NASA Astrophysics Data System (ADS)

Panning, M. P.; Banerdt, W. B.; Beucler, E.; Blanchette-Guertin, J. F.; Boese, M.; Clinton, J. F.; Drilleau, M.; James, S. R.; Kawamura, T.; Khan, A.; Lognonne, P. H.; Mocquet, A.; van Driel, M.

2015-12-01

An important challenge for the upcoming InSight mission to Mars, which will deliver a broadband seismic station to Mars along with other geophysical instruments in 2016, is to accurately determine event locations with the use of a single station. Locations are critical for the primary objective of the mission, determining the internal structure of Mars, as well as a secondary objective of measuring the activity of distribution of seismic events. As part of the mission planning process, a variety of techniques have been explored for location of marsquakes and inversion of structure, and preliminary procedures and software are already under development as part of the InSight Mars Quake and Mars Structure Services. One proposed method, involving the use of recordings of multiple-orbit surface waves, has already been tested with synthetic data and Earth recordings. This method has the strength of not requiring an a priori velocity model of Mars for quake location, but will only be practical for larger events. For smaller events where only first orbit surface waves and body waves are observable, other methods are required. In this study, we implement a transdimensional Bayesian inversion approach to simultaneously invert for basic velocity structure and location parameters (epicentral distance and origin time) using only measurements of body wave arrival times and dispersion of first orbit surface waves. The method is tested with synthetic data with expected Mars noise and Earth data for single events and groups of events and evaluated for errors in both location and structural determination, as well as tradeoffs between resolvable parameters and the effect of 3D crustal variations.

Incompletely Mixed Surface Transient Storage Zones at River Restoration Structures: Modeling Implications

NASA Astrophysics Data System (ADS)

Endreny, T. A.; Robinson, J.

2012-12-01

River restoration structures, also known as river steering deflectors, are designed to reduce bank shear stress by generating wake zones between the bank and the constricted conveyance region. There is interest in characterizing the surface transient storage (STS) and associated biogeochemical processing in the STS zones around these structures to quantify the ecosystem benefits of river restoration. This research explored how the hydraulics around river restoration structures prohibits application of transient storage models designed for homogenous, completely mixed STS zones. We used slug and constant rate injections of a conservative tracer in a 3rd order river in Onondaga County, NY over the course of five experiments at varying flow regimes. Recovered breakthrough curves spanned a transect including the main channel and wake zone at a j-hook restoration structure. We noted divergent patterns of peak solute concentration and times within the wake zone regardless of transect location within the structure. Analysis reveals an inhomogeneous STS zone which is frequently still loading tracer after the main channel has peaked. The breakthrough curve loading patterns at the restoration structure violated the assumptions of simplified "random walk" 2 zone transient storage models which seek to identify representative STS zones and zone locations. Use of structure-scale Weiner filter based multi-rate mass transfer models to characterize STS zones residence times are similarly dependent on a representative zone location. Each 2 zone model assumes 1 zone is a completely mixed STS zone and the other a completely mixed main channel. Our research reveals limits to simple application of the recently developed 2 zone models, and raises important questions about the measurement scale necessary to identify critical STS properties at restoration sites. An explanation for the incompletely mixed STS zone may be the distinct hydraulics at restoration sites, including a constrained high velocity conveyance region closely abutting a wake zone that receives periodic disruption from the upstream structure shearing vortices.igure 1. River restoration j-hook with blue dye revealing main channel and edge of wake zone with multiple surface transient storage zones.

Assignment of the Stereochemistry and Anomeric Configuration of Sugars within Oligosaccharides Via Overlapping Disaccharide Ladders Using MSn

NASA Astrophysics Data System (ADS)

Konda, Chiharu; Londry, Frank A.; Bendiak, Brad; Xia, Yu

2014-08-01

A systematic approach is described that can pinpoint the stereo-structures (sugar identity, anomeric configuration, and location) of individual sugar units within linear oligosaccharides. Using a highly modified mass spectrometer, dissociation of linear oligosaccharides in the gas phase was optimized along multiple-stage tandem dissociation pathways (MSn, n = 4 or 5). The instrument was a hybrid triple quadrupole/linear ion trap mass spectrometer capable of high-efficiency bidirectional ion transfer between quadrupole arrays. Different types of collision-induced dissociation (CID), either on-resonance ion trap or beam-type CID could be utilized at any given stage of dissociation, enabling either glycosidic bond cleavages or cross-ring cleavages to be maximized when wanted. The approach first involves optimizing the isolation of disaccharide units as an ordered set of overlapping substructures via glycosidic bond cleavages during early stages of MSn, with explicit intent to minimize cross-ring cleavages. Subsequently, cross-ring cleavages were optimized for individual disaccharides to yield key diagnostic product ions ( m/ z 221). Finally, fingerprint patterns that establish stereochemistry and anomeric configuration were obtained from the diagnostic ions via CID. Model linear oligosaccharides were derivatized at the reducing end, allowing overlapping ladders of disaccharides to be isolated from MSn. High confidence stereo-structural determination was achieved by matching MSn CID of the diagnostic ions to synthetic standards via a spectral matching algorithm. Using this MSn ( n = 4 or 5) approach, the stereo-structures, anomeric configurations, and locations of three individual sugar units within two pentasaccharides were successfully determined.

Three-dimensional Magnetotelluric Characterization of the Xinzhou Geothermal Field, Southeastern China

NASA Astrophysics Data System (ADS)

Han, Q.; Hu, X.; Cai, J.; Wei, W.

2016-12-01

Xinzhou geothermal field is located in the Guangdong province and adjacent to the China South Sea, and its hot springs can reach up to 92 degree Celsius. Yanshanian granite expose widely in the south of this geothermal field and four faults cut across each other over it. A dense grid of 176 magnetotelluric (MT) sites with broadband has been acquired over the Xinzhou geothermal field and its surrounding area. Due to the related electromagnetic (EM) noise one permanent observatory was placed as a remote reference to suppress this cultural EM noise interference. The datasets are processed using the mutual reference technique, static shift correction, and structural strike and dimensionality analysis based on tensor decomposition. Data analysis reveals that the underground conductivity structure has obvious three-dimensional characterization. For the high resolution result ,two and three dimensional inversion are both applied in this area employing the non-linear conjugate gradient method (NLCG).These MT data sets are supposed to detect the deep subsurface resistivity structure correlated to the distribution of geothermal reservoir (such as faults and fractured granite) and investigate the channel of the upwelling magma. The whole and cold granite usually present high resistivity but once it functions as reservoir the resistivity will decrease, sometimes it is hard to separate the reservoir from the cap layer. The 3D inversion results delineate three high resistivity anomalies distributed in different locations. At last we put forward that the large areas of granite form the major thermal source for the study area and discuss whether any melt under these magma intrusions exists.

The new emergency structure of the Istituto Nazionale di Geofisica e Vulcanologia during the L’Aquila 2009 seismic sequence: the contribution of the COES (Seismological Emergency Operation Center - Centro Operativo Emergenza Sismica)

NASA Astrophysics Data System (ADS)

Moretti, M.; Govoni, A.; Nostro, C.; La Longa, F.; Crescimbene, M.; Pignone, M.; Selvaggi, G.; Working Group, C.

2009-12-01

The Centro Nazionale Terremoti (CNT - National Earthquake Center), departement of Istituto Nazionale di Geofisica e Vulcanologia (INGV), has designed and setup a rapid response emergency structure to face the occurrence of strong earthquakes. This structure is composed by a real time satellite telemetered temporary seismic network (see Abruzzese et al., 2009 Fall AGU) used to improve the hypocentral locations of the INGV National Seismic Network, a stand alone temporary seismic network whose goal is primarily the high dynamic/high resolution data acquisition in the epicentral area and a mobile operational center, the COES (Centro Operativo Emergenza Sismica, Seismological Emergency Operational Center). The COES structure is a sort of mobile office equipped with satellite internet communication that can be rapidly installed in the disaster area to support all the INGV staff operative needs and to cooperate with the Civil Protection department (DPC) aggregating all the scientific information available on the seismic sequence and providing updated information to Civil Protection for the decision making stage during the emergency. The structure is equipped with a heavy load trolley that carries a 6x6 inflatable tent, a satellite router, an UPS, computers, monitors and furniture. The facility can be installed in a couple of hours in the epicentral area and provides a full featured office with dedicated internet connection and VPN access to the INGV data management center in Rome. Just after the April 6 2009 Mw 6.3 earthquake in L’Aquila (Central Italy) the COES has been installed upon request of the Italian Civil Protection (DPC) in the DICOMAC (Directorate of Command and Control - which is the central structure of the DPC that coordinates the emergency activities in the areas affected by the earthquake) located in the Guardia di Finanza headquarters in Coppito nearby L'Aquila (the same location that hosted the G8 meeting). The COES produces real time reports on the seismic sequence evolution constituted by a detailed sequence map, histograms showing the evolution of the magnitude and the number of earthquakes in time and a daily event list. Moreover, it is possible to see the real time hypocentral locations using “SISMAP” (Doumaz et al., 2008), the same tool used in the Seismic Monitoring Center in Rome. During the emergency the COES has been also a reference information point for all people involved in the crisis management and has provided also psychological support to the rescuers and to the earthquake affected population. This education and outreach activity has proved to be extremely effective. References Abruzzese L. et al., AGU Fall Meeting 2009. Doumaz F. et al., Geomedia, speciale geologia, pp. 10-13, 2008.

Projecting social contact matrices in 152 countries using contact surveys and demographic data.

PubMed

Prem, Kiesha; Cook, Alex R; Jit, Mark

2017-09-01

Heterogeneities in contact networks have a major effect in determining whether a pathogen can become epidemic or persist at endemic levels. Epidemic models that determine which interventions can successfully prevent an outbreak need to account for social structure and mixing patterns. Contact patterns vary across age and locations (e.g. home, work, and school), and including them as predictors in transmission dynamic models of pathogens that spread socially will improve the models' realism. Data from population-based contact diaries in eight European countries from the POLYMOD study were projected to 144 other countries using a Bayesian hierarchical model that estimated the proclivity of age-and-location-specific contact patterns for the countries, using Markov chain Monte Carlo simulation. Household level data from the Demographic and Health Surveys for nine lower-income countries and socio-demographic factors from several on-line databases for 152 countries were used to quantify similarity of countries to estimate contact patterns in the home, work, school and other locations for countries for which no contact data are available, accounting for demographic structure, household structure where known, and a variety of metrics including workforce participation and school enrolment. Contacts are highly assortative with age across all countries considered, but pronounced regional differences in the age-specific contacts at home were noticeable, with more inter-generational contacts in Asian countries than in other settings. Moreover, there were variations in contact patterns by location, with work-place contacts being least assortative. These variations led to differences in the effect of social distancing measures in an age structured epidemic model. Contacts have an important role in transmission dynamic models that use contact rates to characterize the spread of contact-transmissible diseases. This study provides estimates of mixing patterns for societies for which contact data such as POLYMOD are not yet available.

Quiet Clean Short-haul Experimental Engine (QCSEE) Over The Wing (OTW) design report

NASA Technical Reports Server (NTRS)

1977-01-01

The design, fabrication, and testing of two experimental high bypass geared turbofan engines and propulsion systems for short haul passenger aircraft are described. The propulsion technology required for future externally blown flap aircraft with engines located both under the wing and over the wing is demonstrated. Composite structures and digital engine controls are among the topics included.

Strength of beams with laminae located according to stiffness

Treesearch

Peter Koch

1964-01-01

Southern Pine boltwood is in abundant supply, but it contains high proportions of juvenile wood, and hence utilization for structural purposes is difficult when conventional means of conversion are employed. As a different approach, it is proposed that heart-center cants be cut from coltwood and then sliced into thick veneers for assembly into beams. The veneers can be...

Structural variability and species diversity of a dwarf Caribbean dry forest

Treesearch

E. Medina; E. Cuevas; S. Molina; A.E. Lugo; O. Ramos

2010-01-01

Low stature woody vegetation of the south-west coast of Puerto Rico grows on a rocky calcareous substrate where plants can only root in holes, cracks, and crevices accumulating water and sediments that allow seed germination and seedling development. Being in a coastal location these communities are influenced by steady onshore winds, high solar radiation, and salt...

Characteristics of Declining Forest Stands on the Allegheny National Forest

Treesearch

William H. McWilliams; Robert White; Stanford L. Arner; Christopher, A. Nowak; Susan L. Stout; Susan L. Stout

1996-01-01

Forest stands with advanced symptoms of forest decline located on the Allegheny National Forest in northwestern Pennsylvania were studied to describe contemporary stand structure and composition, and the status of regeneration. Across all 340 stands, 12 percent of the total basal area per acre was in dead trees and 16 percent was in trees at high risk of mortality. For...

[Melanoma of the mucosa of the mouth and upper respiratory tract].

PubMed

Nepomniashchaia, E M; Svetitskiĭ, P V; Birina, L M

1993-01-01

3 cases of extracutaneous melanoma are described: those of the alveolar process of maxilla, nose septum and ethmoidal cavity. Clinical symptoms were nose haemorrhages, difficulties of the nose respiration, pains in the month. Histologically melanomas were of a typical structure being formed of the epithelioid and naevus-like cells with high content of melanine with an extra- and intracellular location.

77 FR 5502 - Stuyvesant Falls Hydroelectric Project; Notice of Application Ready for Environmental Analysis...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-03

... Kinderhook Creek; (2) an existing 46-acre impoundment with a normal water surface elevation of 174.3 feet...) minimum flow turbine located adjacent to the intake structure; (5) two existing 7.5-foot-diameter, 2,860..., approximately 144 feet long, 84 feet wide, and 60 feet high; (7) two single-runner Francis turbines, each with a...

Tunable optical and excitonic properties of phosphorene via oxidation

NASA Astrophysics Data System (ADS)

Sadki, S.; Drissi, L. B.

2018-06-01

The optical properties and excitonic wave function of phosphorene oxides (PO) are studied using the first principle many-body Green function and the Bethe–Salpeter equation formalism. In this work, the optical properties are determined using ab initio calculations of the dielectric function. At the long wavelength limit q of EM wave (i.e. ), the dielectric function, the absorption spectrum, the lectivity, the electron energy loss spectra (EELS) and the wave function are calculated. The results show an excitonic binding energy of 818 meV with a bright exciton located in the armchair direction in pristine phosphorene. For PO, the arrangement of the oxygen atoms significantly influences the optical properties. In particular, the absorption spectrum is extended along the solar spectrum, with a high absorption coefficient observed in the dangling structures. The maximum lectivity values are observed for the high energies of the light spectrum. Moreover, the first EELS peak is located in the visible region in all the structures except for one configuration that exhibits the same behavior as pure phosphorene. Finally, the exciton effect reveals that all PO conformers have a dark exciton state, which is suitable for long-lived applications.

O' Connell bridge inspection by means of Ground Penetrating Radar

NASA Astrophysics Data System (ADS)

Santos Assuncao, Sonia, ,, Dr

2016-04-01

Ground Penetrating Radar (GPR) is a well-known technique successfully applied in different areas. In structural inspection the methodology may expose information about structural arrangement and pathologies. GPR emits high frequency electromagnetic impulses allowing to detect changes on the electromagnetic properties: electrical conductivity, dielectric constant and magnetic permeability. The central frequency of the each antenna is characterized by a specific resolution and penetration depth. Therefore, different scales of structures can be analysed. High frequency antennas output high resolution images/signals about the shallowest elements such as rebar and the thickness of the first layer. On the other hand, intermediate or lower frequency antennas locate deeper structures, such as the thickness of the arch. The compilation of distinct frequencies gives a better understanding and a more accurate detection of elements in the inner structure. O'Connell Bridge (1877) is one of 24 bridges along River Liffey and one the most famous historical structures in Dublin. It is composed by sandstones and granite and covered by asphalt which represents a suitable structure to evaluate by means of GPR. The lack of inner structural information, especially the thickness of the layer, presence of reinforcement or other metallic elements of support required, at least, a dual frequency analysis of the bridge. In this case, it was applied the (200 MHz and 600 MHz) Multi-Channel Stream EM combined with 1.6 GHz GSSI high frequency antenna. The inspection of bridges by means of GPR may provide not exclusively interesting structural data but historical information and the state of conservation.

Modification of electronic structure, magnetic structure, and topological phase of bismuthene by point defects

NASA Astrophysics Data System (ADS)

Kadioglu, Yelda; Kilic, Sevket Berkay; Demirci, Salih; Aktürk, O. Üzengi; Aktürk, Ethem; Ciraci, Salim

2017-12-01

This paper reveals how the electronic structure, magnetic structure, and topological phase of two-dimensional (2D), single-layer structures of bismuth are modified by point defects. We first showed that a free-standing, single-layer, hexagonal structure of bismuth, named h-bismuthene, exhibits nontrivial band topology. We then investigated interactions between single foreign adatoms and bismuthene structures, which comprise stability, bonding, electronic structure, and magnetic structures. Localized states in diverse locations of the band gap and resonant states in band continua of bismuthene are induced upon the adsorption of different adatoms, which modify electronic and magnetic properties. Specific adatoms result in reconstruction around the adsorption site. Single vacancies and divacancies can form readily in bismuthene structures and remain stable at high temperatures. Through rebondings, Stone-Whales-type defects are constructed by divacancies, which transform into a large hole at high temperature. Like adsorbed adatoms, vacancies induce also localized gap states, which can be eliminated through rebondings in divacancies. We also showed that not only the optical and magnetic properties, but also the topological features of pristine h-bismuthene can be modified by point defects. The modification of the topological features depends on the energies of localized states and also on the strength of coupling between point defects.

Ensemble clustering in visual working memory biases location memories and reduces the Weber noise of relative positions.

PubMed

Lew, Timothy F; Vul, Edward

2015-01-01

People seem to compute the ensemble statistics of objects and use this information to support the recall of individual objects in visual working memory. However, there are many different ways that hierarchical structure might be encoded. We examined the format of structured memories by asking subjects to recall the locations of objects arranged in different spatial clustering structures. Consistent with previous investigations of structured visual memory, subjects recalled objects biased toward the center of their clusters. Subjects also recalled locations more accurately when they were arranged in fewer clusters containing more objects, suggesting that subjects used the clustering structure of objects to aid recall. Furthermore, subjects had more difficulty recalling larger relative distances, consistent with subjects encoding the positions of objects relative to clusters and recalling them with magnitude-proportional (Weber) noise. Our results suggest that clustering improved the fidelity of recall by biasing the recall of locations toward cluster centers to compensate for uncertainty and by reducing the magnitude of encoded relative distances.

Precise seismic velocity structure beneath the Hokkaido corner, northern Japan: Arc-arc collision and the 1970 M 6.7 Hidaka region earthquake and the 1982 M 7.1 Urakawa-oki earthquake

NASA Astrophysics Data System (ADS)

Kita, S.; Hasegawa, A.; Nakajima, J.; Okada, T.; Matsuzawa, T.; Katsumata, K.

2011-12-01

Using arrival-time data both from the nationwide Kiban seismic network and from a dense temporary seismic network covering the area of the Hokkaido corner [Katsumata et al., 2002a; 2003, JGR], we precisely determined three-dimensional seismic velocity structure beneath this area to understand the collision process between the Kuril and northeasetern Japan forearcs. Tomographic inversions were performed with smaller grid spacing [5 x 10 x 5 km] than our previous study [Kita et al., 2010b, EPSL] by using the double-difference tomography method [Zhang and Thurber, 2003; 2006]. Inhomogeneous seismic velocity structure was more precisely imaged in the Hokkaido corner at depths of 0-120 km. A broad low-velocity zone of P- and S- waves having velocities of crust materials with a total volume of 80 km x 100 km x 50 km is distributed to the west of the Hidaka metamorphic belt (the Hidaka main thrust) at depths of 30-90km. On the other hand, several small-scale high-velocity zones having velocities of mantle materials were detected at depths of 0-35 km), inclined east-northeastward at a high angle of 40-60 degrees. All of these anomaly high velocity zones are respectively located in the deeper extension of the Neogene thrust faults, striking almost N-S direction and dipping 40-50 degrees at depths of 0-10km [e.g. Ito 2000]. The largest high-velocity zone is located in the deeper extension of the Hidaka main thrust, being in contact with the eastern edge of the low-V zone. This high-V zone reaches near the surface at the Hidaka metamorphic belt and its southern edge is located just beneath the Horoman-peridotite, which is one of the most famous peridotite outcrops. Moreover, the boundary of the high-V zone with the broad low-V zone corresponds to the fault plane of the 1970 Mj 6.7 Hidaka region earthquake [Moriya 1972]. Another high-V zone is located within the broad low-V zone at depths of 20-30km and in the deeper extension of thrust, which belongs to the Ishikari Low land eastern edge fault groups. The western boundary of this small high-V zone corresponds to the fault plane of the 1982 Mj 7.1 Urakawa-oki earthquake [Moriya et al, 1983]. Both of the hanging walls of the fault planes of two M 7 class big earthquakes have anomalously high velocities, while both of the foot walls have low velocities. A considerable number of earthquakes, including aftershocks of these two big earthquake and, occur in the broad low-V zone at depths of 0-80 km (even at depths of the mantle wedge), whereas seismicity is very low in other areas. These present observations provide important in formation to deepen our understanding of the ongoing arc-arc collision process and earthquake generation mechanism in the Hokkaido corner.

3D radar wavefield tomography of comet interiors

NASA Astrophysics Data System (ADS)

Sava, Paul; Asphaug, Erik

2018-04-01

Answering fundamental questions about the origin and evolution of small planetary bodies hinges on our ability to image their surface and interior structure in detail and at high resolution. The interior structure is not easily accessible without systematic imaging using, e.g., radar transmission and reflection data from multiple viewpoints, as in medical tomography. Radar tomography can be performed using methodology adapted from terrestrial exploration seismology. Our feasibility study primarily focuses on full wavefield methods that facilitate high quality imaging of small body interiors. We consider the case of a monostatic system (co-located transmitters and receivers) operated in various frequency bands between 5 and 15 MHz, from a spacecraft in slow polar orbit around a spinning comet nucleus. Using realistic numerical experiments, we demonstrate that wavefield techniques can generate high resolution tomograms of comets nuclei with arbitrary shape and complex interior properties.

High resolution iridocorneal angle imaging system by axicon lens assisted gonioscopy.

PubMed

Perinchery, Sandeep Menon; Shinde, Anant; Fu, Chan Yiu; Jeesmond Hong, Xun Jie; Baskaran, Mani; Aung, Tin; Murukeshan, Vadakke Matham

2016-07-29

Direct visualization and assessment of the iridocorneal angle (ICA) region with high resolution is important for the clinical evaluation of glaucoma. However, the current clinical imaging systems for ICA do not provide sufficient structural details due to their poor resolution. The key challenges in achieving high quality ICA imaging are its location in the anterior region of the eye and the occurrence of total internal reflection due to refractive index difference between cornea and air. Here, we report an indirect axicon assisted gonioscopy imaging probe with white light illumination. The illustrated results with this probe shows significantly improved visualization of structures in the ICA including TM region, compared to the current available tools. It could reveal critical details of ICA and expected to aid management by providing information that is complementary to angle photography and gonioscopy.

High resolution iridocorneal angle imaging system by axicon lens assisted gonioscopy

PubMed Central

Perinchery, Sandeep Menon; Shinde, Anant; Fu, Chan Yiu; Jeesmond Hong, Xun Jie; Baskaran, Mani; Aung, Tin; Murukeshan, Vadakke Matham

2016-01-01

Direct visualization and assessment of the iridocorneal angle (ICA) region with high resolution is important for the clinical evaluation of glaucoma. However, the current clinical imaging systems for ICA do not provide sufficient structural details due to their poor resolution. The key challenges in achieving high quality ICA imaging are its location in the anterior region of the eye and the occurrence of total internal reflection due to refractive index difference between cornea and air. Here, we report an indirect axicon assisted gonioscopy imaging probe with white light illumination. The illustrated results with this probe shows significantly improved visualization of structures in the ICA including TM region, compared to the current available tools. It could reveal critical details of ICA and expected to aid management by providing information that is complementary to angle photography and gonioscopy. PMID:27471000

High resolution iridocorneal angle imaging system by axicon lens assisted gonioscopy

NASA Astrophysics Data System (ADS)

Perinchery, Sandeep Menon; Shinde, Anant; Fu, Chan Yiu; Jeesmond Hong, Xun Jie; Baskaran, Mani; Aung, Tin; Murukeshan, Vadakke Matham

2016-07-01

Direct visualization and assessment of the iridocorneal angle (ICA) region with high resolution is important for the clinical evaluation of glaucoma. However, the current clinical imaging systems for ICA do not provide sufficient structural details due to their poor resolution. The key challenges in achieving high quality ICA imaging are its location in the anterior region of the eye and the occurrence of total internal reflection due to refractive index difference between cornea and air. Here, we report an indirect axicon assisted gonioscopy imaging probe with white light illumination. The illustrated results with this probe shows significantly improved visualization of structures in the ICA including TM region, compared to the current available tools. It could reveal critical details of ICA and expected to aid management by providing information that is complementary to angle photography and gonioscopy.

Modeling Particle Exposure in US Trucking Terminals

PubMed Central

Davis, ME; Smith, TJ; Laden, F; Hart, JE; Ryan, LM; Garshick, E

2007-01-01

Multi-tiered sampling approaches are common in environmental and occupational exposure assessment, where exposures for a given individual are often modeled based on simultaneous measurements taken at multiple indoor and outdoor sites. The monitoring data from such studies is hierarchical by design, imposing a complex covariance structure that must be accounted for in order to obtain unbiased estimates of exposure. Statistical methods such as structural equation modeling (SEM) represent a useful alternative to simple linear regression in these cases, providing simultaneous and unbiased predictions of each level of exposure based on a set of covariates specific to the exposure setting. We test the SEM approach using data from a large exposure assessment of diesel and combustion particles in the US trucking industry. The exposure assessment includes data from 36 different trucking terminals across the United States sampled between 2001 and 2005, measuring PM2.5 and its elemental carbon (EC), organic carbon (OC) components, by personal monitoring, and sampling at two indoor work locations and an outdoor “background” location. Using the SEM method, we predict: 1) personal exposures as a function of work related exposure and smoking status; 2) work related exposure as a function of terminal characteristics, indoor ventilation, job location, and background exposure conditions; and 3) background exposure conditions as a function of weather, nearby source pollution, and other regional differences across terminal sites. The primary advantage of SEMs in this setting is the ability to simultaneously predict exposures at each of the sampling locations, while accounting for the complex covariance structure among the measurements and descriptive variables. The statistically significant results and high R2 values observed from the trucking industry application supports the broader use of this approach in exposure assessment modeling. PMID:16856739

Structure Function Scaling Exponent and Intermittency in the Wake of a Wind Turbine Array

NASA Astrophysics Data System (ADS)

Aseyev, Aleksandr; Ali, Naseem; Cal, Raul

2015-11-01

Hot-wire measurements obtained in a 3 × 3 wind turbine array boundary layer are utilized to analyze high order structure functions, intermittency effects as well as the probability density functions of velocity increments at different scales within the energy cascade. The intermittency exponent is found to be greater in the far wake region in comparison to the near wake. At hub height, the intermittency exponent is found to be null. ESS scaling exponents of the second, fourth, and fifth order structure functions remain relatively constant as a function of height in the far-wake whereas in the near-wake these highly affected by the passage of the rotor thus showing a dependence on physical location. When comparing with proposed models, these generally over predict the structure functions in the far wake region. The pdf distributions in the far wake region display wider tails compared to the near wake region, and constant skewness hypothesis based on the local isotropy is verified in the wake. CBET-1034581.

Structure-Function Perturbation and Dissociation of Tetrameric Urate Oxidase by High Hydrostatic Pressure

PubMed Central

Girard, Eric; Marchal, Stéphane; Perez, Javier; Finet, Stéphanie; Kahn, Richard; Fourme, Roger; Marassio, Guillaume; Dhaussy, Anne-Claire; Prangé, Thierry; Giffard, Marion; Dulin, Fabienne; Bonneté, Françoise; Lange, Reinhard; Abraini, Jacques H.; Mezouar, Mohamed; Colloc'h, Nathalie

2010-01-01

Abstract Structure-function relationships in the tetrameric enzyme urate oxidase were investigated using pressure perturbation. As the active sites are located at the interfaces between monomers, enzyme activity is directly related to the integrity of the tetramer. The effect of hydrostatic pressure on the enzyme was investigated by x-ray crystallography, small-angle x-ray scattering, and fluorescence spectroscopy. Enzymatic activity was also measured under pressure and after decompression. A global model, consistent with all measurements, discloses structural and functional details of the pressure-induced dissociation of the tetramer. Before dissociating, the pressurized protein adopts a conformational substate characterized by an expansion of its substrate binding pocket at the expense of a large neighboring hydrophobic cavity. This substate should be adopted by the enzyme during its catalytic mechanism, where the active site has to accommodate larger intermediates and product. The approach, combining several high-pressure techniques, offers a new (to our knowledge) means of exploring structural and functional properties of transient states relevant to protein mechanisms. PMID:20483346

Localization of multiple defects using the compact phased array (CPA) method

NASA Astrophysics Data System (ADS)

Senyurek, Volkan Y.; Baghalian, Amin; Tashakori, Shervin; McDaniel, Dwayne; Tansel, Ibrahim N.

2018-01-01

Array systems of transducers have found numerous applications in detection and localization of defects in structural health monitoring (SHM) of plate-like structures. Different types of array configurations and analysis algorithms have been used to improve the process of localization of defects. For accurate and reliable monitoring of large structures by array systems, a high number of actuator and sensor elements are often required. In this study, a compact phased array system consisting of only three piezoelectric elements is used in conjunction with an updated total focusing method (TFM) for localization of single and multiple defects in an aluminum plate. The accuracy of the localization process was greatly improved by including wave propagation information in TFM. Results indicated that the proposed CPA approach can locate single and multiple defects with high accuracy while decreasing the processing costs and the number of required transducers. This method can be utilized in critical applications such as aerospace structures where the use of a large number of transducers is not desirable.

Advances in high-resolution imaging--techniques for three-dimensional imaging of cellular structures.

PubMed

Lidke, Diane S; Lidke, Keith A

2012-06-01

A fundamental goal in biology is to determine how cellular organization is coupled to function. To achieve this goal, a better understanding of organelle composition and structure is needed. Although visualization of cellular organelles using fluorescence or electron microscopy (EM) has become a common tool for the cell biologist, recent advances are providing a clearer picture of the cell than ever before. In particular, advanced light-microscopy techniques are achieving resolutions below the diffraction limit and EM tomography provides high-resolution three-dimensional (3D) images of cellular structures. The ability to perform both fluorescence and electron microscopy on the same sample (correlative light and electron microscopy, CLEM) makes it possible to identify where a fluorescently labeled protein is located with respect to organelle structures visualized by EM. Here, we review the current state of the art in 3D biological imaging techniques with a focus on recent advances in electron microscopy and fluorescence super-resolution techniques.

The Retreat from Locative Overgeneralisation Errors: A Novel Verb Grammaticality Judgment Study

PubMed Central

Bidgood, Amy; Ambridge, Ben; Pine, Julian M.; Rowland, Caroline F.

2014-01-01

Whilst some locative verbs alternate between the ground- and figure-locative constructions (e.g. Lisa sprayed the flowers with water/Lisa sprayed water onto the flowers), others are restricted to one construction or the other (e.g. *Lisa filled water into the cup/*Lisa poured the cup with water). The present study investigated two proposals for how learners (aged 5–6, 9–10 and adults) acquire this restriction, using a novel-verb-learning grammaticality-judgment paradigm. In support of the semantic verb class hypothesis, participants in all age groups used the semantic properties of novel verbs to determine the locative constructions (ground/figure/both) in which they could and could not appear. In support of the frequency hypothesis, participants' tolerance of overgeneralisation errors decreased with each increasing level of verb frequency (novel/low/high). These results underline the need to develop an integrated account of the roles of semantics and frequency in the retreat from argument structure overgeneralisation. PMID:24830412

Genetic diversity and structure of Atta robusta (Hymenoptera, Formicidae, Attini), an endangered species endemic to the restinga ecoregion

PubMed Central

dos Reis, Evelyze Pinheiro; Fernandes Salomão, Tânia Maria; de Oliveira Campos, Lucio Antonio; Tavares, Mara Garcia

2014-01-01

The genetic diversity and structure of the ant Atta robusta were assessed by ISSR (inter-simple sequence repeats) in 72 colonies collected from 10 localities in the Brazilian states of Espírito Santo (48 colonies) and Rio de Janeiro (24 colonies). The ISSR pattern included 67 bands, 51 of them (76.1%) polymorphic. Analysis of molecular variance (AMOVA) revealed a high level (57.4%) of inter-population variation, which suggested a high degree of genetic structure that was confirmed by UPGMA (unweighted pair-group method using an arithmetic average) cluster analysis. The significant correlation between genetic and geographic distances (r = 0.64, p < 0.05) indicated isolation that reflected the distance between locations. Overall, the populations were found to be genetically divergent. This finding indicates the need for management plans to preserve and reduce the risk of extinction of A. robusta. PMID:25249782

Genetic diversity and structure of Atta robusta (Hymenoptera, Formicidae, Attini), an endangered species endemic to the restinga ecoregion.

PubMed

Dos Reis, Evelyze Pinheiro; Fernandes Salomão, Tânia Maria; de Oliveira Campos, Lucio Antonio; Tavares, Mara Garcia

2014-09-01

The genetic diversity and structure of the ant Atta robusta were assessed by ISSR (inter-simple sequence repeats) in 72 colonies collected from 10 localities in the Brazilian states of Espírito Santo (48 colonies) and Rio de Janeiro (24 colonies). The ISSR pattern included 67 bands, 51 of them (76.1%) polymorphic. Analysis of molecular variance (AMOVA) revealed a high level (57.4%) of inter-population variation, which suggested a high degree of genetic structure that was confirmed by UPGMA (unweighted pair-group method using an arithmetic average) cluster analysis. The significant correlation between genetic and geographic distances (r = 0.64, p < 0.05) indicated isolation that reflected the distance between locations. Overall, the populations were found to be genetically divergent. This finding indicates the need for management plans to preserve and reduce the risk of extinction of A. robusta.

Cellular imaging of deep organ using two-photon Bessel light-sheet nonlinear structured illumination microscopy

PubMed Central

Zhao, Ming; Zhang, Han; Li, Yu; Ashok, Amit; Liang, Rongguang; Zhou, Weibin; Peng, Leilei

2014-01-01

In vivo fluorescent cellular imaging of deep internal organs is highly challenging, because the excitation needs to penetrate through strong scattering tissue and the emission signal is degraded significantly by photon diffusion induced by tissue-scattering. We report that by combining two-photon Bessel light-sheet microscopy with nonlinear structured illumination microscopy (SIM), live samples up to 600 microns wide can be imaged by light-sheet microscopy with 500 microns penetration depth, and diffused background in deep tissue light-sheet imaging can be reduced to obtain clear images at cellular resolution in depth beyond 200 microns. We demonstrate in vivo two-color imaging of pronephric glomeruli and vasculature of zebrafish kidney, whose cellular structures located at the center of the fish body are revealed in high clarity by two-color two-photon Bessel light-sheet SIM. PMID:24876996

Oculomotor selection underlies feature retention in visual working memory.

PubMed

Hanning, Nina M; Jonikaitis, Donatas; Deubel, Heiner; Szinte, Martin

2016-02-01

Oculomotor selection, spatial task relevance, and visual working memory (WM) are described as three processes highly intertwined and sustained by similar cortical structures. However, because task-relevant locations always constitute potential saccade targets, no study so far has been able to distinguish between oculomotor selection and spatial task relevance. We designed an experiment that allowed us to dissociate in humans the contribution of task relevance, oculomotor selection, and oculomotor execution to the retention of feature representations in WM. We report that task relevance and oculomotor selection lead to dissociable effects on feature WM maintenance. In a first task, in which an object's location was encoded as a saccade target, its feature representations were successfully maintained in WM, whereas they declined at nonsaccade target locations. Likewise, we observed a similar WM benefit at the target of saccades that were prepared but never executed. In a second task, when an object's location was marked as task relevant but constituted a nonsaccade target (a location to avoid), feature representations maintained at that location did not benefit. Combined, our results demonstrate that oculomotor selection is consistently associated with WM, whereas task relevance is not. This provides evidence for an overlapping circuitry serving saccade target selection and feature-based WM that can be dissociated from processes encoding task-relevant locations. Copyright © 2016 the American Physiological Society.

Automated Recognition of RNA Structure Motifs by Their SHAPE Data Signatures.

PubMed

Radecki, Pierce; Ledda, Mirko; Aviran, Sharon

2018-06-14

High-throughput structure profiling (SP) experiments that provide information at nucleotide resolution are revolutionizing our ability to study RNA structures. Of particular interest are RNA elements whose underlying structures are necessary for their biological functions. We previously introduced patteRNA , an algorithm for rapidly mining SP data for patterns characteristic of such motifs. This work provided a proof-of-concept for the detection of motifs and the capability of distinguishing structures displaying pronounced conformational changes. Here, we describe several improvements and automation routines to patteRNA . We then consider more elaborate biological situations starting with the comparison or integration of results from searches for distinct motifs and across datasets. To facilitate such analyses, we characterize patteRNA ’s outputs and describe a normalization framework that regularizes results. We then demonstrate that our algorithm successfully discerns between highly similar structural variants of the human immunodeficiency virus type 1 (HIV-1) Rev response element (RRE) and readily identifies its exact location in whole-genome structure profiles of HIV-1. This work highlights the breadth of information that can be gleaned from SP data and broadens the utility of data-driven methods as tools for the detection of novel RNA elements.

Structural molecular biology: Recent results from neutron diffraction

NASA Astrophysics Data System (ADS)

Timmins, Peter A.

1995-02-01

Neutron diffraction is of importance in structural biology at several different levels of resolution. In most cases the unique possibility arising from deuterium labelling or contrast variation is of fundamental importance in providing information complementary to that which can be obtained from X-ray diffraction. At high resolution, neutron crystallography of proteins allows the location of hydrogen atoms in the molecule or of the hydration water, both of which may be central to biological activity. A major difficulty in this field has been the poor signal-to-noise ratio of the data arising not only from relatively low beam intensities and small crystals but, most importantly from the incoherent background due to hydrogen atoms in the sample. Modern methods of molecular biology now offer ways of producing fully deuterated proteins by cloning in bacteria grown on fully deuterated media. At a slightly lower resolution, there are a number of systems which may be ordered in one or two dimensions. This is the case in the purple membrane where neutron diffraction with deuterium labelling has complemented high resolution electron diffraction. Finally there is a class of very large macromolecular systems which can be crystallised and have been studied by X-ray diffraction but in which part of the structure is locally disordered and usually has insufficient contrast to be seen with X-rays. In this case the use of H 2O/D 2O contrast variation allows these components to be located. Examples of this are the nucleic acid in virus structures and detergent bound to membrane proteins.

Response of Ocean Circulation to Different Wind Forcing in Puerto Rico and US Virgin Islands

NASA Astrophysics Data System (ADS)

Solano, Miguel; Garcia, Edgardo; Leonardi, Stafano; Canals, Miguel; Capella, Jorge

2013-11-01

The response of the ocean circulation to various wind forcing products has been studied using the Regional Ocean Modeling System. The computational domain includes the main islands of Puerto Rico, Saint John and Saint Thomas, located on the continental shelf dividing the Caribbean Sea and the Atlantic Ocean. Data for wind forcing is provided by an anemometer located in a moored buoy, the Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPS) model and the National Digital Forecast Database (NDFD). Hindcast simulations have been validated using hydrographic data at different locations in the area of study. Three cases are compared to quantify the impact of high resolution wind forcing on the ocean circulation and the vertical structure of salinity, temperature and velocity. In the first case a constant wind velocity field is used to force the model as measured by an anemometer on top of a buoy. In the second case, a forcing field provided by the Navy's COAMPS model is used and in the third case, winds are taken from NDFD in collaboration with the National Centers for Environmental Prediction. Validated results of ocean currents against data from Acoustic Doppler Current Profilers at different locations show better agreement using high resolution wind data as expected. Thanks to CariCOOS and NOAA.

PERSPECTIVE VIEW OF THE C. 1925 AUTO SALES/GARAGE STRUCTURE LOCATED ...

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

PERSPECTIVE VIEW OF THE C. 1925 AUTO SALES/GARAGE STRUCTURE LOCATED AT 205-209 SECOND STREET NORTHWEST. - Corvallis Downtown Historic District, Bounded by First & Sixth Streets, Van Buren & Western Avenues, Corvallis, Benton County, OR

Improved Location of Microseismic Events in Borehole Monitoring by Inclusion of Particle Motion Analysis: a Case Study at a CBM Field in Indonesia

NASA Astrophysics Data System (ADS)

Verdhora Ry, Rexha; Septyana, T.; Widiyantoro, S.; Nugraha, A. D.; Ardjuna, A.

2017-04-01

Microseismic monitoring and constraining its hypocenters in and around hydrocarbon reservoirs provides insight into induced deformation related to hydraulic fracturing. In this study, we used data from a single vertical array of sensors in a borehole, providing measures of arrival times and polarizations. Microseismic events are located using 1-D velocity models and arrival times of P- and S-waves. However, in the case of all the sensors being deployed in a near-vertical borehole, there is a high ambiguity in the source location. Herein, we applied a procedure using azimuth of P-wave particle motion to constrain and improve the source location. We used a dataset acquired during 1-day of fracture stimulation at a CBM field in Indonesia. We applied five steps of location procedure to investigate microseismic events induced by these hydraulic fracturing activities. First, arrival times for 1584 candidate events were manually picked. Then we refined the arrival times using energy ratio method to obtain high consistency picking. Using these arrival times, we estimated back-azimuth using P-wave polarization analysis. We also added the combination of polarities analysis to remove 180° ambiguity. In the end, we determined hypocenter locations using grid-search method that guided in the back-azimuth trace area to minimize the misfit function of arrival times. We have successfully removed the ambiguity and produced a good solution for hypocenter locations as indicated statistically by small RMS. Most of the events clusters highlight coherent structures around the treatment well site and revealed faults. The same procedure can be applied to various other cases such as microseismic monitoring in the field of geothermal and shale gas/oil exploration, also CCS (Carbon Capture and Storage) development.

Wildfire risk in the wildland-urban interface: A simulation study in northwestern Wisconsin

USGS Publications Warehouse

Massada, Avi Bar; Radeloff, Volker C.; Stewart, Susan I.; Hawbaker, Todd J.

2009-01-01

The rapid growth of housing in and near the wildland–urban interface (WUI) increases wildfirerisk to lives and structures. To reduce fire risk, it is necessary to identify WUI housing areas that are more susceptible to wildfire. This is challenging, because wildfire patterns depend on fire behavior and spread, which in turn depend on ignition locations, weather conditions, the spatial arrangement of fuels, and topography. The goal of our study was to assess wildfirerisk to a 60,000 ha WUI area in northwesternWisconsin while accounting for all of these factors. We conducted 6000 simulations with two dynamic fire models: Fire Area Simulator (FARSITE) and Minimum Travel Time (MTT) in order to map the spatial pattern of burn probabilities. Simulations were run under normal and extreme weather conditions to assess the effect of weather on fire spread, burn probability, and risk to structures. The resulting burn probability maps were intersected with maps of structure locations and land cover types. The simulations revealed clear hotspots of wildfire activity and a large range of wildfirerisk to structures in the study area. As expected, the extreme weather conditions yielded higher burn probabilities over the entire landscape, as well as to different land cover classes and individual structures. Moreover, the spatial pattern of risk was significantly different between extreme and normal weather conditions. The results highlight the fact that extreme weather conditions not only produce higher fire risk than normal weather conditions, but also change the fine-scale locations of high risk areas in the landscape, which is of great importance for fire management in WUI areas. In addition, the choice of weather data may limit the potential for comparisons of risk maps for different areas and for extrapolating risk maps to future scenarios where weather conditions are unknown. Our approach to modeling wildfirerisk to structures can aid fire risk reduction management activities by identifying areas with elevated wildfirerisk and those most vulnerable under extreme weather conditions.

Genetic structure of Zymoseptoria tritici in northern France at region, field, plant and leaf layer scales.

PubMed

Siah, Ali; Bomble, Myriam; Tisserant, Benoit; Cadalen, Thierry; Holvoet, Maxime; Hilbert, Jean-Louis; Halama, Patrice; Reignault, Philippe Lucien

2018-04-16

Population genetic structure of the worldwide-distributed wheat pathogen Zymoseptoria tritici has been extensively studied at large geographical scales, but to a much less extent at small or local spatial scales. A total of 627 single-conidial fungal isolates were sampled from several locations in northern France (Hauts-de-France Region) to assess fungal genetic structure at region, field, plant and leaf layer scales, using highly polymorphic microsatellite markers and mating type idiomorphs. Important and overall similar levels of both gene and genotype diversities (gene diversity values ≥ 0.44 and haplotype frequencies ≥ 94 %) were found at all the examined scales. Such rates of diversity are likely due to an active sexual recombination in the investigated areas, as revealed by equal proportions of the two mating types scored in all sampled populations. Interestingly, a rare occurrence of clones among lesions from a same leaf, as well as among leaves from different plant leaf layers (e.g. upper vs lower leaves), was highlighted, indicating that ascospores contribute much more than expected to Z. tritci epidemics, compared to pycnidiospores. Population structure and AMOVA analyses revealed significant genetic differentiation at the regional scale (GST = 0.23) and, as expected, not at the other more local scales (GST ≤ 0.01). Further analyses using Bayesian and unweighted neighbor-joining statistical methods detected six genetic clusters within the regional population, overall distributed according to the locations from which the isolates were sampled. Neither clear directional relative migration linked to the geographical distribution of the locations, nor isolation by distance, were observed. Separate evolutionary trajectories caused by selection and adaptations to habitat heterogeneity could be the main forces shaping such structuration. This study provides new insights into the epidemiology and the genetic structure of Z. tritici at small local and, for the first time, at single plant and leaf layer scales. Such findings would be helpful in implementing effective control strategies.

Imaging of the 3D crustal structure off the Joetsu region in Japan Sea and its implication of the activity of the tectonic zone by using LT-OBSs

NASA Astrophysics Data System (ADS)

Machida, Y.; Shinbo, T.; Shinohara, M.; Yamada, T.; Mochizuki, K.; Kanazawa, T.

2011-12-01

At the eastern margin of the Japan Sea, large earthquakes have been occurred (e.g., 1964 Niigata earthquake, the 1983 Japan Sea earthquake, the 2004 Chuetsu earthquake and the 2007 Chuetsu-oki earthquake) along the Niigata-Kobe Tectonic Zone (NKTZ). The NKTZ is recognized as a region of large strain rate along the Japan Sea coast and in the northern Chubu and Kinki distinct. Among these events, the 2004 Chuetsu earthquake and the 2007 Chuetsu-oki earthquake is triggered by reactivation of pre-existing faults within ancient rift systems by stress loading through a ductile creeping of the weak lower crust (Kato et al., 2008). Because a source region of the 2007 Chuetsu-oki earthquake is distributed under the Japan Sea, aftershock observation using Ocean Bottom Seismometers were carried out (Shinohara et al., 2008). It is necessary to estimate precise aftershock distribution in order to understand the mechanism of earthquake generation. In addition, a seismic refraction survey was carried out to reveal crustal structure in the region (Nakahigashi et al., submitted). They indicated that most of aftershocks were occurred in the upper crust. Because the tectonic zone is thought to be spread in offshore region, it is difficult to understand a precise activity of the tectonic zone from only land-base observations. To compare the seismic activity with the crustal structure in the region is indispensable to understand the stress field in the tectonic zone and the tectonics in the eastern margin of the Japan Sea. In order to investigate a seismic activity in the tectonic zone, 10 Long-Term Ocean Bottom Seismometers (LT-OBS) were deployed from December, 2008, to October, 2009, in the off Joetsu region. First we estimated hypocenters of events using a location program for finding a maximum likelihood solution using a Bayesian approach (Hirata and Matsu'ura, 1987). The velocity structure for the location was modeled from a previous refraction survey conducted in the same region. Foci of over one thousand and two hundreds earthquakes were estimated with high spatial resolution during the observation period. The hypocentral distribution revealed that most of events are occurred within the upper crust. It is consistent with a result of Shinohara et al. (2008). Our precise locations of the events are useful for crustal structure studies. For example, reliability of results from tomographic study is thought to increase by using our precise locations of the events as initial locations of the inversion. We performed a high resolution 3D tomographic analysis and relocation of earthquake applying the double-difference tomography method (Zhang and Thurber, 2003). We can compare the seismic activity with heterogeneity in crust of the tectonic zone off the coast of Joetsu region.

10 AU scale halo structure around DG Tauri

NASA Technical Reports Server (NTRS)

Chen, Wen P.; Howell, R. R.; Simon, M.; Benson, J. A.

1992-01-01

Lunar occultation observations of the active T Tauri star DG Tau show that in the infrared K band it has a core-halo structure: 20-25 percent of the flux comes from a region 10 AU in extent and the rest from an unresolved core smaller than an AU. These results are consistent with those reported by Leinert et al. from a separate observation. The results obtained here and those of Leinert et al., measuring the intensity distribution projected along directions spanning roughly 40 deg, indicate that the resolved structure is not highly elongated. The extended emission is interpreted as star light scattered by optically thin dust located in a halo surrounding the star.

Structure solution of DNA-binding proteins and complexes with ARCIMBOLDO libraries

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

Pröpper, Kevin; Instituto de Biologia Molecular de Barcelona; Meindl, Kathrin

2014-06-01

The structure solution of DNA-binding protein structures and complexes based on the combination of location of DNA-binding protein motif fragments with density modification in a multi-solution frame is described. Protein–DNA interactions play a major role in all aspects of genetic activity within an organism, such as transcription, packaging, rearrangement, replication and repair. The molecular detail of protein–DNA interactions can be best visualized through crystallography, and structures emphasizing insight into the principles of binding and base-sequence recognition are essential to understanding the subtleties of the underlying mechanisms. An increasing number of high-quality DNA-binding protein structure determinations have been witnessed despite themore » fact that the crystallographic particularities of nucleic acids tend to pose specific challenges to methods primarily developed for proteins. Crystallographic structure solution of protein–DNA complexes therefore remains a challenging area that is in need of optimized experimental and computational methods. The potential of the structure-solution program ARCIMBOLDO for the solution of protein–DNA complexes has therefore been assessed. The method is based on the combination of locating small, very accurate fragments using the program Phaser and density modification with the program SHELXE. Whereas for typical proteins main-chain α-helices provide the ideal, almost ubiquitous, small fragments to start searches, in the case of DNA complexes the binding motifs and DNA double helix constitute suitable search fragments. The aim of this work is to provide an effective library of search fragments as well as to determine the optimal ARCIMBOLDO strategy for the solution of this class of structures.« less

Star formation and ISM morphology in tidally induced spiral structures

NASA Astrophysics Data System (ADS)

Pettitt, Alex R.; Tasker, Elizabeth J.; Wadsley, James W.; Keller, Ben W.; Benincasa, Samantha M.

2017-07-01

Tidal encounters are believed to be one of the key drivers of galactic spiral structure in the Universe. Such spirals are expected to produce different morphological and kinematic features compared to density wave and dynamic spiral arms. In this work, we present high-resolution simulations of a tidal encounter of a small mass companion with a disc galaxy. Included are the effects of gas cooling and heating, star formation and stellar feedback. The structure of the perturbed disc differs greatly from the isolated galaxy, showing clear spiral features that act as sites of new star formation, and displaying interarm spurs. The two arms of the galaxy, the bridge and tail, appear to behave differently; with different star formation histories and structure. Specific attention is focused on offsets between gas and stellar spiral features which can be directly compared to observations. We find that some offsets do exist between different media, with gaseous arms appearing mostly on the convex side of the stellar arms, though the exact locations appear highly time dependent. These results further highlight the differences between tidal spirals and other theories of arm structure.

A highly-sensitive label-free biosensor based on two dimensional photonic crystals with negative refraction

NASA Astrophysics Data System (ADS)

Malmir, Narges; Fasihi, Kiazand

2017-11-01

In this work, we present a novel high-sensitive optical label-free biosensor based on a two-dimensional photonic crystal (2D PC). The suggested structure is composed of a negative refraction structure in a hexagonal lattice PC, along with a positive refraction structure which is arranged in a square lattice PC. The frequency shift of the transmission peak is measured respect to the changes of refractive indices of the studied materials (the blood plasma, water, dry air and normal air). The studied materials are filled into a W1 line-defect waveguide which is located in the PC structure with positive refraction (the microfluidic nanochannel). Our numerical simulations, which are based on finite-difference time-domain (FDTD) method, show that in the proposed structure, a sensitivity about 1100 nm/RIU and a transmission efficiency more than 75% can be achieved. With this design, to the best of our knowledge, the obtained sensitivity and the transmission efficiency are one of the highest values in the reported PC label-free biosensors.

Long Period Seismic Waves Developped at Local Distances and Their Importance for EEWs

NASA Astrophysics Data System (ADS)

Kalkan Ertan, Esra; Pınar, Ali

2017-04-01

Long period ground motions is an highly importance topic nowadays because of the number of the large-scale structures increases day by day in metropolitan areas. Their effect on the large-scale structure (high rise buildings, suspension bridges, off-shore oil drilling platforms etc.) are more perceivable than small structures. Studies show that long period ground motions especially occurs in distant sedimentary basins with the help of the path effects. (Koketsu and Miyake, 2008) Period of the waves is ranging from several to ten seconds and that causes dramatic resonance and severe damage to the structures which are located in deep sedimentary basins (Furumura et al., 2013). There are so many examples of how destructive these waves can be. A devastating example is Mexico City, which is located 400 km away from the 1985 Michoacan Earthquake (Mw=8.0) epicenter, where 300 buldings collapsed and 800 buildings were demolished beyond repair. (Celebi et al, 1987). Another example is 2003 Tokachi-oki Earthquake associated with severe damage on large oil tanks, and fires lasting two days at the city of Tomakomani 250 km away from the source (Koketsu et al, 2005). Lots of studies revealed that the sedimentary basins amplifiy the long period seismic waves. In the case of Marmara Region, three important basins namely Çınarcık, Central and Tekirdaǧ Basins exist in Marmara Sea. The primary objective of the proposed study is to investigate if any relations exist between basins structures and generation of long period seismic waves which can be effective in Istanbul Metropolitan Area and develop reliable early warning applications or systems for structures which are under such risk. Three types of algorithms are in use for EEW applications used for this study, Virtual Seismologist, PRESTo and ELARMS2. The early warning signal is communicated to the appropriate server shut-down systems of the recipient facilities, that automatically decide proper action based on the alarm levels. The stations are located at basin-edges, outside and inside the basins. So we have a chance to compare the seismograms whether or not the earthquake generates long period ground motions and to send signals to early warning systems. Until now, we have a good example for long period seismic waves which was caused by North Aegean Earthquake on 24 May 2014 (Mw=6.9). It was located approximately 30 km north-west of Gökçeada Island and widely felt in İstanbul Metropolitan area. The earthquake epicenter was 300 km away from Istanbul, but the shaking duration of tall buildings was high up to 10 minutes. The travel time of the long period waves from the epicenter to the metropolitan area of Istanbul is about 85 seconds providing more than 50 seconds warning time. Although, the amplitude of the strong motion waveforms were small, the long period and the long duration of the velocity waveforms acquired at more than 100 strong motion stations within the city, explains to some degree the causatives of the long shaking duration of tall buildings.

Locating air leaks in manned spacecraft using structure-borne noise.

PubMed

Holland, Stephen D; Chimenti, D E; Roberts, Ron; Strei, Michael

2007-06-01

All manned spacecraft are vulnerable to leaks generated by micrometeorite or debris impacts. Methods for locating such leaks using leak-generated, structure-borne ultrasonic noise are discussed and demonstrated. Cross-correlations of ultrasonic noise waveforms from a leak into vacuum are used to find the location of the leak. Four methods for sensing and processing leak noise have been developed and tested and each of these can be used to reveal the leak location. The methods, based on phased-array, distributed sensor, and dual sensor approaches, utilize the propagation patterns of guided ultrasonic Lamb waves in the spacecraft skin structure to find the source or direction of the leak noise. It is shown that each method can be used to successfully locate the leak to within a few millimeters on a 0.6-m2 aluminum plate. The relative merits of the four methods are discussed.

Ecological monitoring of intertidal phytobenthic communities of the Basque Coast (N. Spain) following the Prestige oil spill.

PubMed

Díez, I; Secilla, A; Santolaria, A; Gorostiaga, J M

2009-12-01

Following the Prestige oil spill, six-monthly samplings (spring and autumn) of intertidal macroalgal assemblages were carried out from 2004 to 2006 in twelve locations along the Basque coast. Macroalgal species appeared to be little modified, but species richness, diversity, and algal cover were significantly lower in the first year of the study, so it cannot be ruled out that the arrival of oil on the Basque coast might have had a damaging effect on intertidal communities. On the other hand, no significant differences were detected between locations slightly and moderately affected by oil in any of the structural parameters considered. By contrast, significant differences were detected between locations within each oiling level that indicate that other natural environmental factors play a greater role in the differences between locations than the oiling level. Likewise, significant differences were detected between areas within each location which were not consistent with time, indicating that communities are highly heterogeneous in species richness, diversity and algal cover at the scale of tens of meters. The dominant Corallina elongata and most of the accompanying species did not show significant year-on-year differences in terms of cover. Also, there were no differences between the two oiling levels. Analyses revealed a high spatial variability at the scale of kilometers (locations) and tens of meters (areas) for most of the taxa. The results obtained provide detailed quantitative data on intertidal phytobenthic assemblages of the Basque coast at different spatial and temporal scales that were hitherto unavailable for the region.

Response-only method for damage detection of beam-like structures using high accuracy frequencies with auxiliary mass spatial probing

NASA Astrophysics Data System (ADS)

Zhong, Shuncong; Oyadiji, S. Olutunde; Ding, Kang

2008-04-01

This paper proposes a new approach based on auxiliary mass spatial probing using spectral centre correction method (SCCM), to provide a simple solution for damage detection by just using the response time history of beam-like structures. The natural frequencies of a damaged beam with a traversing auxiliary mass change due to change in the inertia of the beam as the auxiliary mass is traversed along the beam, as well as the point-to-point variations in the flexibility of the beam. Therefore the auxiliary mass can enhance the effects of the crack on the dynamics of the beam and, therefore, facilitate the identification and location of damage in the beam. That is, the auxiliary mass can be used to probe the dynamic characteristic of the beam by traversing the mass from one end of the beam to the other. However, it is impossible to obtain accurate modal frequencies by the direct operation of the fast Fourier transform (FFT) of the response data of the structure because the frequency spectrum can be only calculated from limited sampled time data which results in the well-known leakage effect. SCCM is identical to the energy centrobaric correction method (ECCM) which is a practical and effective method used in rotating mechanical fault diagnosis and which resolves the shortcoming of FFT and can provide high accuracy estimate of frequency, amplitude and phase. In the present work, the modal responses of damaged simply supported beams with auxiliary mass are computed using the finite element method (FEM). The graphical plots of the natural frequencies calculated by SCCM versus axial location of auxiliary mass are obtained. However, it is difficult to locate the crack directly from the curve of natural frequencies. A simple and fast method, the derivatives of natural frequency curve, is proposed in the paper which can provide crack information for damage detection of beam-like structures. The efficiency and practicability of the proposed method is illustrated via numerical simulation. For real cases, experimental noise is expected to corrupt the response data and, ultimately, the natural frequencies of beam-like structures. Therefore, the response data with a normally distributed random noise is also studied. Also, the effects of crack depth, auxiliary mass and damping ratios on the proposed method are investigated. From the simulated results, the efficiency and robustness of the proposed method is demonstrated. The results show that the proposed method has low computational cost and high precision.

High-resolution image of Calaveras fault seismicity

USGS Publications Warehouse

Schaff, D.P.; Bokelmann, G.H.R.; Beroza, G.C.; Waldhauser, F.; Ellsworth, W.L.

2002-01-01

By measuring relative earthquake arrival times using waveform cross correlation and locating earthquakes using the double difference technique, we are able to reduce hypocentral errors by 1 to 2 orders of magnitude over routine locations for nearly 8000 events along a 35-km section of the Calaveras Fault. This represents ~92% of all seismicity since 1984 and includes the rupture zone of the M 6.2 1984 Morgan Hill, California, earthquake. The relocated seismicity forms highly organized structures that were previously obscured by location errors. There are abundant repeating earthquake sequences as well as linear clusters of earthquakes. Large voids in seismicity appear with dimensions of kilometers that have been aseismic over the 30-year time interval, suggesting that these portions of the fault are either locked or creeping. The area of greatest slip in the Morgan Hill main shock coincides with the most prominent of these voids, suggesting that this part of the fault may be locked between large earthquakes. We find that the Calaveras Fault at depth is extremely thin, with an average upper bound on fault zone width of 75 m. Given the location error, however, this width is not resolvably different from zero. The relocations reveal active secondary faults, which we use to solve for the stress field in the immediate vicinity of the Calaveras Fault. We find that the maximum compressive stress is at a high angle, only 13 from the fault normal, supporting previous interpretations that this fault is weak.

Structure and properties of microporous titanosilicate determined by first-principles calculations

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

Ching, W.Y.; Xu, Y.; Gu, Z.

1996-12-01

The structure of EST-10, a member of synthetic microporous titanosilicates, was recently determined by an ingenious combination of experimental and simulational techniques. However, the locations of the alkali atoms in the framework remain elusive and its electronic structure is totally unknown. Based on first-principles local density calculations, the possible locations of the alkali atoms are identified and its electronic structure and bonding fully elucidated. ETS-10 is a semiconductor with a direct band gap of 2.33 eV. The Na atoms are likely to locate inside the seven-member ring pore adjacent to the one-dimensional Ti-O-Ti-O- chain. {copyright} {ital 1996 The American Physicalmore » Society.}« less

Subsonic Aerodynamic Assessment of Vortex Flow Management Devices on a High-Speed Civil Transport Configuration

NASA Technical Reports Server (NTRS)

Campbell, Bryan A.; Applin, Zachary T.; Kemmerly, Guy T.

1999-01-01

An experimental investigation of the effects of leading-edge vortex management devices on the subsonic performance of a high-speed civil transport (HSCT) configuration was conducted in the Langley 14- by 22-Foot Subsonic Tunnel. Data were obtained over a Mach number range of 0.14 to 0.27, with corresponding chord Reynolds numbers of 3.08 x 10 (sup 6) to 5.47 x 10 (sup 6). The test model was designed for a cruise Mach number of 2.7. During the subsonic high-lift phase of flight, vortical flow dominates the upper surface flow structure, and during vortex breakdown, this flow causes adverse pitch-up and a reduction of usable lift. The experimental results showed that the beneficial effects of small leading-edge vortex management devices located near the model reference center were insufficient to substantially affect the resulting aerodynamic forces and moments. However, devices located at or near the wiring apex region demonstrated potential for pitch control with little effect on overall lift.

A Portable Infrasonic Detection System

NASA Technical Reports Server (NTRS)

Shams, Qamar A.; Burkett, Cecil G.; Zuckerwar, Allan J.; Lawrenson, Christopher C.; Masterman, Michael

2008-01-01

During last couple of years, NASA Langley has designed and developed a portable infrasonic detection system which can be used to make useful infrasound measurements at a location where it was not possible previously. The system comprises an electret condenser microphone, having a 3-inch membrane diameter, and a small, compact windscreen. Electret-based technology offers the lowest possible background noise, because Johnson noise generated in the supporting electronics (preamplifier) is minimized. The microphone features a high membrane compliance with a large backchamber volume, a prepolarized backplane and a high impedance preamplifier located inside the backchamber. The windscreen, based on the high transmission coefficient of infrasound through matter, is made of a material having a low acoustic impedance and sufficiently thick wall to insure structural stability. Close-cell polyurethane foam has been found to serve the purpose well. In the proposed test, test parameters will be sensitivity, background noise, signal fidelity (harmonic distortion), and temporal stability. The design and results of the compact system, based upon laboratory and field experiments, will be presented.

Dynamic Disturbance Processes Create Dynamic Lek Site Selection in a Prairie Grouse.

PubMed

Hovick, Torre J; Allred, Brady W; Elmore, R Dwayne; Fuhlendorf, Samuel D; Hamilton, Robert G; Breland, Amber

2015-01-01

It is well understood that landscape processes can affect habitat selection patterns, movements, and species persistence. These selection patterns may be altered or even eliminated as a result of changes in disturbance regimes and a concomitant management focus on uniform, moderate disturbance across landscapes. To assess how restored landscape heterogeneity influences habitat selection patterns, we examined 21 years (1991, 1993-2012) of Greater Prairie-Chicken (Tympanuchus cupido) lek location data in tallgrass prairie with restored fire and grazing processes. Our study took place at The Nature Conservancy's Tallgrass Prairie Preserve located at the southern extent of Flint Hills in northeastern Oklahoma. We specifically addressed stability of lek locations in the context of the fire-grazing interaction, and the environmental factors influencing lek locations. We found that lek locations were dynamic in a landscape with interacting fire and grazing. While previous conservation efforts have treated leks as stable with high site fidelity in static landscapes, a majority of lek locations in our study (i.e., 65%) moved by nearly one kilometer on an annual basis in this dynamic setting. Lek sites were in elevated areas with low tree cover and low road density. Additionally, lek site selection was influenced by an interaction of fire and patch edge, indicating that in recently burned patches, leks were located near patch edges. These results suggest that dynamic and interactive processes such as fire and grazing that restore heterogeneity to grasslands do influence habitat selection patterns in prairie grouse, a phenomenon that is likely to apply throughout the Greater Prairie-Chicken's distribution when dynamic processes are restored. As conservation moves toward restoring dynamic historic disturbance patterns, it will be important that siting and planning of anthropogenic structures (e.g., wind energy, oil and gas) and management plans not view lek locations as static points, but rather as sites that shift around the landscape in response to shifting vegetation structure. Acknowledging shifting lek locations in these landscapes will help ensure conservation efforts are successful by targeting the appropriate areas for protection and management.

Calibrated Multiple Event Relocations of the Central and Eastern United States

NASA Astrophysics Data System (ADS)

Yeck, W. L.; Benz, H.; McNamara, D. E.; Bergman, E.; Herrmann, R. B.; Myers, S. C.

2015-12-01

Earthquake locations are a first-order observable which form the basis of a wide range of seismic analyses. Currently, the ANSS catalog primarily contains published single-event earthquake locations that rely on assumed 1D velocity models. Increasing the accuracy of cataloged earthquake hypocenter locations and origin times and constraining their associated errors can improve our understanding of Earth structure and have a fundamental impact on subsequent seismic studies. Multiple-event relocation algorithms often increase the precision of relative earthquake hypocenters but are hindered by their limited ability to provide realistic location uncertainties for individual earthquakes. Recently, a Bayesian approach to the multiple event relocation problem has proven to have many benefits including the ability to: (1) handle large data sets; (2) easily incorporate a priori hypocenter information; (3) model phase assignment errors; and, (4) correct for errors in the assumed travel time model. In this study we employ bayseloc [Myers et al., 2007, 2009] to relocate earthquakes in the Central and Eastern United States from 1964-present. We relocate ~11,000 earthquakes with a dataset of ~439,000 arrival time observations. Our dataset includes arrival-time observations from the ANSS catalog supplemented with arrival-time data from the Reviewed ISC Bulletin (prior to 1981), targeted local studies, and arrival-time data from the TA Array. One significant benefit of the bayesloc algorithm is its ability to incorporate a priori constraints on the probability distributions of specific earthquake locations parameters. To constrain the inversion, we use high-quality calibrated earthquake locations from local studies, including studies from: Raton Basin, Colorado; Mineral, Virginia; Guy, Arkansas; Cheneville, Quebec; Oklahoma; and Mt. Carmel, Illinois. We also add depth constraints to 232 earthquakes from regional moment tensors. Finally, we add constraints from four historic (1964-1973) ground truth events from a verification database. We (1) evaluate our ability to improve our location estimations, (2) use improved locations to evaluate Earth structure in seismically active regions, and (3) examine improvements to the estimated locations of historic large magnitude earthquakes.

Four cavity efficiency enhanced magnetically insulated line oscillator

DOEpatents

Lemke, Raymond W.; Clark, Miles C.; Calico, Steve E.

1998-04-21

A four cavity, efficient magnetically insulated line oscillator (C4-E MILO) having seven vanes and six cavities formed within a tube-like structure surrounding a cathode. The C4-E MILO has a primary slow wave structure which is comprised of four vanes and the four cavities located near a microwave exit end of the tube-like structure. The primary slow wave structure is the four cavity (C4) portion of the magnetically insulated line oscillator (MILO). An RF choke is provided which is comprised of three of the vanes and two of the cavities. The RF choke is located near a pulsed power source portion of the tube-like structure surrounding the cathode. The RF choke increases feedback in the primary slow wave structure, prevents microwaves generated in the primary slow wave structure from propagating towards the pulsed power source and modifies downstream electron current so as to enhance microwave power generation. A beam dump/extractor is located at the exit end of the oscillator tube for extracting microwave power from the oscillator, and in conjunction with an RF extractor vane, which comprises the fourth vane of the primary slow wave structure (nearest the exit) having a larger gap radius than the other vanes of the primary SWS, comprises an RF extractor. Uninsulated electron flow is returned downstream towards the exit along an anode/beam dump region located between the beam dump/extractor and the exit where the RF is radiated at said RF extractor vane located near the exit and the uninsulated electron flow is disposed at the beam dump/extractor.

Four cavity efficiency enhanced magnetically insulated line oscillator

DOEpatents

Lemke, R.W.; Clark, M.C.; Calico, S.E.

1998-04-21

A four cavity, efficient magnetically insulated line oscillator (C4-E MILO) having seven vanes and six cavities formed within a tube-like structure surrounding a cathode is disclosed. The C4-E MILO has a primary slow wave structure which is comprised of four vanes and the four cavities located near a microwave exit end of the tube-like structure. The primary slow wave structure is the four cavity portion of the magnetically insulated line oscillator (MILO). An RF choke is provided which is comprised of three of the vanes and two of the cavities. The RF choke is located near a pulsed power source portion of the tube-like structure surrounding the cathode. The RF choke increases feedback in the primary slow wave structure, prevents microwaves generated in the primary slow wave structure from propagating towards the pulsed power source and modifies downstream electron current so as to enhance microwave power generation. A beam dump/extractor is located at the exit end of the oscillator tube for extracting microwave power from the oscillator, and in conjunction with an RF extractor vane, which comprises the fourth vane of the primary slow wave structure (nearest the exit) having a larger gap radius than the other vanes of the primary SWS, comprises an RF extractor. Uninsulated electron flow is returned downstream towards the exit along an anode/beam dump region located between the beam dump/extractor and the exit where the RF is radiated at said RF extractor vane located near the exit and the uninsulated electron flow is disposed at the beam dump/extractor. 34 figs.

Imaging inhomogeneous seismic velocity structure in and around the fault plane of the 2008 Iwate-Miyagi, Japan, Nairiku Earthquake (M7.2) - spatial variation in depth of seismic-aseismic transition and possible high-T/overpressurized fluid distribution

NASA Astrophysics Data System (ADS)

Okada, T.; Umino, N.; Hasegawa, A.; 2008 Iwate-Miyagi Nairiku Earthquake, G. O.

2008-12-01

A large shallow earthquake (named the 2008 Iwate-Miyagi Nairiku Earthquake) with a JMA magnitude of 7.2 occurred in the central part of NE Japan on June 14, 2008. Focal area of the present earthquake is located in the Tohoku backbone range strain concentration zone (Miura et al., 2004) along the volcanic front. Just after the occurrence of this earthquake, Japanese universities (Hokkaido, Hirosaki, Tohoku, Tokyo, Nagoya, Kyoto, Kochi, Kyusyu, Kagoshima) and NIED deployed a dense aftershock observation network in and around the focal area. Total number of temporal stations is 128. Using data from this dense aftershock observation and other temporary and routinely operated stations, we estimate hypocenter distribution and seismic velocity structure of the crust in and around the focal area of the present earthquake. We determined three-dimensional seismic velocity structure and relocated hypocenters simultaneously using the double- difference tomography method (Zhang and Thurber, 2003). Spatial extent of the aftershock area is about 45 km (NNE-SSW) by 15 km (WNW-ESE). Most of aftershocks are aligned in westward dipping. Shallower extensions of aftershock alignments seem to be located nearly at the coseismic surface deformations, which are along a geological fault, and the surface trace of the active fault (Detana fault). Note that some aftershocks seem to occur off the fault plane of the mainshock. The focal area of the present earthquake is located at a high Vs area. In the lower crust, we found some distinct low-Vs areas. These low velocity zones are located just beneath the strain concentration zones / seismic belts along the backbone range and in the northern Miyagi region. Focal area of the present earthquake is also located just above the low velocity zone in the lower crust. Beneath active volcanoes, these low velocity zones become more distinct and shallower, and aftershocks tend to occur shallower and not occur within such low-velocity zones. These low-velocity zones in the lower crust might be caused by high temperature upwelling flow of fluid originating from the mantle wedge. The present observation supports the hypothesis by Hasegawa et al. (2005) that anelastic deformation of the crust weakened by fluid forms the strain concentration zone and promotes the occurrence of large shallow inland earthquakes. We used data from JMA, Hi-net/NIED, NAO-Mizusawa and TITECH. We also used data from JNES. This work was conducted under the support of Grant-in-Aid for Special Purposes, MEXT, Japan. We thank Prof. Cliff Thurber and Dr. Haijiang Zhang for providing their programs and valuable discussions.

Subduction structure beneath the eastern part of the Kii Peninsula, southwestern Japan, revealed by dense seismic array observation

NASA Astrophysics Data System (ADS)

Kurashimo, E.; Iidaka, T.; Tsumura, N.; Iwasaki, T.

2016-12-01

The Nankai trough region, where the Philippine Sea Plate (PHS) subducts beneath the SW Japan arc, is a well-known seismogenic zone of interplate earthquakes. In recent years, various slip motions with a different time scale, including episodic tremors and very low-frequency earthquakes have been recognized at or near the updip and downdip limits of seismogenic zone [e.g., Obara, 2002; Ito and Obara, 2006]. Revealing structural factors that control the fault slip behavior is important to understand the earthquake rupture dynamics. In 2006, active-source seismic experiment was conducted to obtain the subduction structure beneath the eastern part of the Kii Peninsula [Iwasaki et al., 2008]. Iwasaki et al. (2008) provided the geometry of the subducting PHS and the overlying crustal structure. However, little is known about the deeper part of the plate boundary, especially Vp/Vs structure in and around the source region of the tremor. Previous studies indicate the fluid pressure on a plate interface is one of the key factors to understand the fault slip process [e.g., Saffer and Tobin, 2011]. Seismic velocity variation provides important information on the fluid-related heterogeneous structure. Passive seismic data is useful to obtain a deep image including the S-wave velocity. Therefore, we conducted passive seismic experiment in the eastern part of the Kii Peninsula. Ninety 3-component portable seismographs were installed on a 90-km-long line nearly parallel to the direction of the subduction of the PHS. Waveforms were continuously recorded during a six-month period from May, 2015. Seismic data from 116 permanent stations around the survey line were also incorporated into our analysis to obtain a high-resolution velocity model. Arrival times of 356 local earthquakes were used in a joint inversion for earthquake locations and 3-D Vp and Vp/Vs structures. Velocity structures are resolved down to 50 km depth. Clustered tremors are located in and around the low Vp and high Vp/Vs zone. Reported strong reflector interpreted to be the top of the PHS [Iwasaki et al., 2008] well corresponds to the top of the low Vp and high Vp/Vs zone. The low Vp and high Vp/Vs zone generally suggests the existence of fluid (e.g., Zhao et al., 1996). These results suggest the occurrence of the tremors may be associated with fluids dehydrated from the PHS.

Location and characterization of the Sancti Spiritus Fort from geophysical investigations

NASA Astrophysics Data System (ADS)

Bonomo, Néstor; Osella, Ana; Martinelli, Patricia; la Vega, Matías de; Cocco, Gabriel; Letieri, Fabian; Frittegotto, Guillermo

2012-08-01

A geophysical investigation was carried out to locate and characterize the remains of the Sancti Spiritus Fort, the first European settlement in the South Cone of America (1527-1529). In an initial stage, we used three complementary methods, ground penetrating radar, multifrequency electromagnetic induction and dipole-dipole electric profiling, to increase the possibility of detecting the structures of the Fort whose physical properties were expected to be similar to those of the surrounding soil, as they were constructed with raw earth probably extracted from it. From different views of the data, a number of electromagnetic signals apparently related to these structures were identified. Test excavations confirmed these hypotheses and showed that the structures were poorly preserved. Furthermore, they were almost indistinguishable through direct inspection of the excavated sections of soil, and very difficult to track. Therefore, in a second stage of geophysical studies, we acquired high-density grids of GPR data at relevant areas, looking for more detailed information about the structures. The results of these studies allowed to determine with precision their continuity through the site and also to interpret a number of areas which had remained unclear from the first survey. Extensive archaeological excavations were designed from the geophysical maps and carried out. From them, the geophysical interpretations were fully confirmed, and the presence of structural elements of previous and later native settlements was established.

Al{sub 2}O{sub 3} multi-density layer structure as a moisture permeation barrier deposited by radio frequency remote plasma atomic layer deposition

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

Jung, Hyunsoo; Samsung Display Co. Ltd., Tangjeong, Chungcheongnam-Do 336-741; Jeon, Heeyoung

2014-02-21

Al{sub 2}O{sub 3} films deposited by remote plasma atomic layer deposition have been used for thin film encapsulation of organic light emitting diode. In this study, a multi-density layer structure consisting of two Al{sub 2}O{sub 3} layers with different densities are deposited with different deposition conditions of O{sub 2} plasma reactant time. This structure improves moisture permeation barrier characteristics, as confirmed by a water vapor transmission rate (WVTR) test. The lowest WVTR of the multi-density layer structure was 4.7 × 10{sup −5} gm{sup −2} day{sup −1}, which is one order of magnitude less than WVTR for the reference single-density Al{submore » 2}O{sub 3} layer. This improvement is attributed to the location mismatch of paths for atmospheric gases, such as O{sub 2} and H{sub 2}O, in the film due to different densities in the layers. This mechanism is analyzed by high resolution transmission electron microscopy, elastic recoil detection, and angle resolved X-ray photoelectron spectroscopy. These results confirmed that the multi-density layer structure exhibits very good characteristics as an encapsulation layer via location mismatch of paths for H{sub 2}O and O{sub 2} between the two layers.« less

3D Velocity Structure in Southern Haiti from Local Earthquake Tomography

NASA Astrophysics Data System (ADS)

Douilly, R.; Ellsworth, W. L.; Kissling, E. H.; Freed, A. M.; Deschamps, A.; de Lepinay, B. M.

2016-12-01

We investigate 3D local earthquake tomography for high-quality travel time arrivals from aftershocks following the 2010 M7.0 Haiti earthquake on the Léogâne fault. The data were recorded by 35 stations, including 19 ocean bottom seismometers, from which we selected 595 events to simultaneously invert for hypocenter location and 3D Vp and Vs velocity structures in southern Haiti. We performed several resolution tests and concluded that clear features can be recovered to a depth of 15 km. At 5km depth we distinguish a broad low velocity zone in the Vp and Vs structure offshore near Gonave Island, which correlate with layers of marine sediments. Results show a pronounced low velocity zone in the upper 5 km across the city of Léogâne, which is consistent with the sedimentary basin location from geologic map. At 10 km depth, we detect a low velocity anomaly offshore near the Trois Baies fault and a NW-SE directed low velocity zone onshore across Petit-Goâve and Jacmel, which is consistent with a suspected fault from a previous study and that we refer to it in our study as the Petit-Goâve-Jacmel fault (PGJF). These observations suggest that low velocity structures delineate fault structures and the sedimentary basins across the southern peninsula, which is extremely useful for seismic hazard assessment in Haiti.

Advanced technique for ultra-thin residue inspection with sub-10nm thickness using high-energy back-scattered electrons

NASA Astrophysics Data System (ADS)

Han, Jin-Hee

2018-03-01

Recently the aspect ratio of capacitor and via hole of memory semiconductor device has been dramatically increasing in order to store more information in a limited area. A small amount of remained residues after etch process on the bottom of the high aspect ratio structure can make a critical failure in device operation. Back-scattered electrons (BSE) are mainly used for inspecting the defect located at the bottom of the high aspect ratio structure or analyzing the overlay of the multi-layer structure because these electrons have a high linearity with the direction of emission and a high kinetic energy above 50eV. However, there is a limitation on that it cannot detect ultra-thin residue material having a thickness of several nanometers because the surface sensitivity is extremely low. We studied the characteristics of BSE spectra using Monte Carlo simulations for several cases which the high aspect ratio structures have extreme microscopic residues. Based on the assumption that most of the electrons emitted without energy loss are localized on the surface, we selected the detection energy window which has a range of 20eV below the maximum energy of the BSE. This window section is named as the high-energy BSE region. As a result of comparing the detection sensitivity of the conventional and the high-energy BSE detection mode, we found that the detection sensitivity for the residuals which have 2nm thickness is improved by more than 10 times in the high-energy BSE mode. This BSE technology is a new inspection method that can greatly be improved the inspection sensitivity for the ultra-thin residual material presented in the high aspect ratio structure, and its application will be expanded.

A new approach for structural health monitoring by applying anomaly detection on strain sensor data

NASA Astrophysics Data System (ADS)

Trichias, Konstantinos; Pijpers, Richard; Meeuwissen, Erik

2014-03-01

Structural Health Monitoring (SHM) systems help to monitor critical infrastructures (bridges, tunnels, etc.) remotely and provide up-to-date information about their physical condition. In addition, it helps to predict the structure's life and required maintenance in a cost-efficient way. Typically, inspection data gives insight in the structural health. The global structural behavior, and predominantly the structural loading, is generally measured with vibration and strain sensors. Acoustic emission sensors are more and more used for measuring global crack activity near critical locations. In this paper, we present a procedure for local structural health monitoring by applying Anomaly Detection (AD) on strain sensor data for sensors that are applied in expected crack path. Sensor data is analyzed by automatic anomaly detection in order to find crack activity at an early stage. This approach targets the monitoring of critical structural locations, such as welds, near which strain sensors can be applied during construction and/or locations with limited inspection possibilities during structural operation. We investigate several anomaly detection techniques to detect changes in statistical properties, indicating structural degradation. The most effective one is a novel polynomial fitting technique, which tracks slow changes in sensor data. Our approach has been tested on a representative test structure (bridge deck) in a lab environment, under constant and variable amplitude fatigue loading. In both cases, the evolving cracks at the monitored locations were successfully detected, autonomously, by our AD monitoring tool.

A compilation of information and data on the Manson impact structure

NASA Technical Reports Server (NTRS)

Hartung, Jack B.; Anderson, Raymond R.

1988-01-01

A problem for the impact hypothesis for the Cretaceous-Tertiary (K-T) mass extinction is the apparent absence of an identifiable impact site. The Manson Impact Structure is a candidate because it is the largest recognized in the U.S.; it is relatively close to the largest and most abundant shocked quartz grains found at the K-T boundary; and its age is indistinguishable from that of the K-T boundary based on paleontological evidence, fission track dates, and preliminary Ar-40/Ar-39 measurements. The region of northwest central Iowa containing the Manson Impact Structure is covered by Quaternary glacial deposits underlain by Phanerozoic sedimentary rocks (mostly flat-lying carbonates) and Proterozoic red clastic, metamorphic, volcanic, and plutonic rocks. In a circular area about 22 miles (35 km) in diameter around Manson, Iowa, this normal sequence is absent or disturbed and near the center of the disturbed area granitic basement rocks have been uplifted some 20,000 ft (6000m). Attention was drawn to Manson initially by the unusual quality of the groundwater there. Within the structure three roughly concentric zones of rock associations have been identified: (1) displaced strata; (2) completely disrupted strata, and igneous and metamorphic rocks. Manson was established as an impact structure based on its circular shape, its central uplift, and the presence of shocked quartz within the granitic central uplift. A gravity survey identified locations of low-density brecciated rocks and high-density uplifted crystalline rocks, but the outer boundary of the structure could not be established. Aeromagnetic and ground magnetic surveys showed locations and depths of shallowly buried crystalline rock and the locations of faults. A refraction seismic survey identified the crystalline central uplift, determined that the average elevation of bedrock is 70 ft (20 m) higher outside the structure than within, and was used to map the bedrock topography within the structure. A connection between the Manson impact and the K-T boundary may be established or refuted through study of the impact energy, the impact time, and composition of host rock, possible impactors, and impact melts.

An analysis of penetration and ricochet phenomena in oblique hypervelocity impact

NASA Technical Reports Server (NTRS)

Schonberg, William P.; Taylor, Roy A.; Horn, Jennifer R.

1988-01-01

An experimental investigation of phenomena associated with the oblique hypervelocity impact of spherical projectiles on multisheet aluminum structures is described. A model that can be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations that relate crater and perforation damage of a multisheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multisheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to the meteoroid and space debris environment.

Continuous wavelet transform analysis and modal location analysis acoustic emission source location for nuclear piping crack growth monitoring

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

Mohd, Shukri; Holford, Karen M.; Pullin, Rhys

2014-02-12

Source location is an important feature of acoustic emission (AE) damage monitoring in nuclear piping. The ability to accurately locate sources can assist in source characterisation and early warning of failure. This paper describe the development of a novelAE source location technique termed 'Wavelet Transform analysis and Modal Location (WTML)' based on Lamb wave theory and time-frequency analysis that can be used for global monitoring of plate like steel structures. Source location was performed on a steel pipe of 1500 mm long and 220 mm outer diameter with nominal thickness of 5 mm under a planar location test setup usingmore » H-N sources. The accuracy of the new technique was compared with other AE source location methods such as the time of arrival (TOA) techniqueand DeltaTlocation. Theresults of the study show that the WTML method produces more accurate location resultscompared with TOA and triple point filtering location methods. The accuracy of the WTML approach is comparable with the deltaT location method but requires no initial acoustic calibration of the structure.« less

Tertiary thrust systems and fluid flow beneath the Beaufort coastal plain (1002 area), Arctic National Wildlife Refuge, Alaska, U.S.A.

USGS Publications Warehouse

Potter, Christopher J.; Grow, John A.; Perry, William J.; Moore, Thomas E.; O'Sullivan, Paul B.; Phillips, Jeffrey D.; Saltus, Richard W.

2004-01-01

In the eastern part of the 1002 area, a northward-younging pattern of thin-skinned deformation is apparent. Converging patterns of Paleocene reflectors on the north flank of the Sabbath syncline indicate that the Aichilik high and the Sabbath syncline formed as a passive-roof duplex and piggyback basin, respectively, just behind the Paleocene deformation front. During the Eocene and possibly the Oligocene, thin-skinned thrusting advanced northward over the present location of the Niguanak high. A passive-roof duplex occupied the frontal part of this system. The Kingak and Hue shales exposed above the Niguanak high were transported into their present structural position during the Eocene to Oligocene motion on the long thrust ramps above the present south flank of the Niguanak high. Broad, basement-cored subsurface domes (Niguanak high and Aurora dome) formed near the deformation front in the Oligocene, deforming the overlying thin-skinned structures and feeding a new increment of displacement into thin-skinned structures directly to the north. Deformation continued through the Miocene above a detachment in the basement. Offshore seismicity and Holocene shortening documented by previous workers may indicate that contractional deformation continues to the present day.

Beta-propeller crystal structure of Psathyrella velutina lectin: an integrin-like fungal protein interacting with monosaccharides and calcium.

PubMed

Cioci, Gianluca; Mitchell, Edward P; Chazalet, Valerie; Debray, Henri; Oscarson, Stefan; Lahmann, Martina; Gautier, Catherine; Breton, Christelle; Perez, Serge; Imberty, Anne

2006-04-14

The lectin from the mushroom Psathyrella velutina recognises specifically N-acetylglucosamine and N-acetylneuraminic acid containing glycans. The crystal structure of the 401 amino acid residue lectin shows that it adopts a very regular seven-bladed beta-propeller fold with the N-terminal region tucked into the central cavity around the pseudo 7-fold axis. In the complex with N-acetylglucosamine, six monosaccharides are bound in pockets located between two consecutive propeller blades. Due to the repeats shown by the sequence the binding sites are very similar. Five hydrogen bonds between the protein and the sugar hydroxyl and N-acetyl groups stabilize the complex, together with the hydrophobic interactions with a conserved tyrosine and histidine. The complex with N-acetylneuraminic acid shows molecular mimicry with the same hydrogen bond network, but with different orientations of the carbohydrate ring in the binding site. The beta-hairpin loops connecting the two inner beta-strands of each blade are metal binding sites and two to three calcium ions were located in the structure. The multispecificity and high multivalency of this mushroom lectin, combined with its similarity to the extracellular domain of an important class of cell adhesion molecules, integrins, are another example of the outstanding success of beta-propeller structures as molecular binding machines in nature.

Fine crustal and uppermost mantle S-wave velocity structure beneath the Tengchong volcanic area inferred from receiver function and surface-wave dispersion: constraints on magma chamber distribution

NASA Astrophysics Data System (ADS)

Li, Mengkui; Zhang, Shuangxi; Wu, Tengfei; Hua, Yujin; Zhang, Bo

2018-03-01

The Tengchong volcanic area is located in the southeastern margin of the collision zone between the Indian and Eurasian Plates. It is one of the youngest intraplate volcano groups in mainland China. Imaging the S-wave velocity structure of the crustal and uppermost mantle beneath the Tengchong volcanic area is an important means of improving our understanding of its volcanic activity and seismicity. In this study, we analyze teleseismic data from nine broadband seismic stations in the Tengchong Earthquake Monitoring Network. We then image the crustal and uppermost mantle S-wave velocity structure by joint analysis of receiver functions and surface-wave dispersion. The results reveal widely distributed low-velocity zones. We find four possible magma chambers in the upper-to-middle crust and one in the uppermost mantle. The chamber in the uppermost mantle locates in the depth range from 55 to 70 km. The four magma chambers in the crust occur at different depths, ranging from the depth of 7 to 25 km in general. They may be the heat sources for the high geothermal activity at the surface. Based on the fine crustal and uppermost mantle S-wave velocity structure, we propose a model for the distribution of the magma chambers.