Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK.

PubMed

Kanellopoulos, Anastasios John

2016-01-01

To evaluate the safety, efficacy, and contralateral eye comparison of topography-guided myopic LASIK with two different refraction treatment strategies. Private clinical ophthalmology practice. A total of 100 eyes (50 patients) in consecutive cases of myopic topography-guided LASIK procedures with the same refractive platform (FS200 femtosecond and EX500 excimer lasers) were randomized for treatment as follows: one eye with the standard clinical refraction (group A) and the contralateral eye with the topographic astigmatic power and axis (topography-modified treatment refraction; group B). All cases were evaluated pre- and post-operatively for the following parameters: refractive error, best corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), topography (Placido-disk based) and tomography (Scheimpflug-image based), wavefront analysis, pupillometry, and contrast sensitivity. Follow-up visits were conducted for at least 12 months. Mean refractive error was -5.5 D of myopia and -1.75 D of astigmatism. In group A versus group B, respectively, the average UDVA improved from 20/200 to 20/20 versus 20/16; post-operative CDVA was 20/20 and 20/13.5; 1 line of vision gained was 27.8% and 55.6%; and 2 lines of vision gained was 5.6% and 11.1%. In group A, 27.8% of eyes had over -0.50 diopters of residual refractive astigmatism, in comparison to 11.7% in group B ( P <0.01). The residual percentages in both groups were measured with refractive astigmatism of more than -0.5 diopters. Topography-modified refraction (TMR): topographic adjustment of the amount and axis of astigmatism treated, when different from the clinical refraction, may offer superior outcomes in topography-guided myopic LASIK. These findings may change the current clinical paradigm of the optimal subjective refraction utilized in laser vision correction.

Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK

PubMed Central

Kanellopoulos, Anastasios John

2016-01-01

Purpose To evaluate the safety, efficacy, and contralateral eye comparison of topography-guided myopic LASIK with two different refraction treatment strategies. Setting Private clinical ophthalmology practice. Patients and methods A total of 100 eyes (50 patients) in consecutive cases of myopic topography-guided LASIK procedures with the same refractive platform (FS200 femtosecond and EX500 excimer lasers) were randomized for treatment as follows: one eye with the standard clinical refraction (group A) and the contralateral eye with the topographic astigmatic power and axis (topography-modified treatment refraction; group B). All cases were evaluated pre- and post-operatively for the following parameters: refractive error, best corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), topography (Placido-disk based) and tomography (Scheimpflug-image based), wavefront analysis, pupillometry, and contrast sensitivity. Follow-up visits were conducted for at least 12 months. Results Mean refractive error was −5.5 D of myopia and −1.75 D of astigmatism. In group A versus group B, respectively, the average UDVA improved from 20/200 to 20/20 versus 20/16; post-operative CDVA was 20/20 and 20/13.5; 1 line of vision gained was 27.8% and 55.6%; and 2 lines of vision gained was 5.6% and 11.1%. In group A, 27.8% of eyes had over −0.50 diopters of residual refractive astigmatism, in comparison to 11.7% in group B (P<0.01). The residual percentages in both groups were measured with refractive astigmatism of more than −0.5 diopters. Conclusion Topography-modified refraction (TMR): topographic adjustment of the amount and axis of astigmatism treated, when different from the clinical refraction, may offer superior outcomes in topography-guided myopic LASIK. These findings may change the current clinical paradigm of the optimal subjective refraction utilized in laser vision correction. PMID:27843292

On effects of topography in rotating flows

NASA Astrophysics Data System (ADS)

Burmann, Fabian; Noir, Jerome; Jackson, Andrew

2017-11-01

Both, seismological studies and geodynamic arguments suggest that there is significant topography at the core mantle boundary (CMB). This leads to the question whether the topography of the CMB could influence the flow in the Earth's outer core. As a preliminary experiment, we investigate the effects of bottom topography in the so-called Spin-Up, where motion of a contained fluid is created by a sudden increase of rotation rate. Experiments are performed in a cylindrical container mounted on a rotating table and quantitative results are obtained with particle image velocimetry. Several horizontal length scales of topography (λ) are investigated, ranging from cases where λ is much smaller then the lateral extend of the experiment (R) to cases where λ is a fraction of R. We find that there is an optimal λ that creates maximum dissipation of kinetic energy. Depending on the length scale of the topography, kinetic energy is either dissipated in the boundary layer or in the bulk of the fluid. Two different phases of fluid motion are present: a starting flow in the from of solid rotation (phase I), which is later replaced by meso scale vortices on the length scale of bottom topography (phase II).

Accuracy of Canadian CT head rule in predicting positive findings on CT of the head of patients after mild head injury in a large trauma centre in Saudi Arabia

PubMed Central

Arab, Ala Faisal; Ahmed, Anwar E; Hussein, Mohamed Ahmed; Khankan, Azzam A; Alokaili, Riyadh Nasser

2015-01-01

Background Investigation of unjustified computed tomography (CT) scan in patients with minor head injury is lacking in Saudi Arabia. The purpose of the study was to evaluate the compliance and effectiveness of the Canadian computed tomography head rule (CCHR) in our emergency department (ED) and trauma centre and also to reduce the number of unjustified CT studies of the head in the centre. Methods A retrospective study of 368 ED patients with minor head injury was conducted. Patients who underwent CT scan between July 2010 and June 2011were selected from the ED head trauma registry by systematic randomisation. The CCHR was retrospectively applied on the patients’ charts to calculate the prevalence of unjustified head CT scans. A separate survey was conducted to evaluate three emergency physicians’ level of awareness about the CCHR and their ability to determine the necessity of CT scans with various clinical scenarios of head injury. Results The prevalence of unjustified CT scans as per the CCHR was 61.8% (95% confidence interval (CI) 56.5–66.9%). Approximately 5% of the sample had positive CT findings with 95% CI 2.9–7.6%. The CCHR correctly identified 12 cases with positive CT findings with 66.67% sensitivity. Only 24 (6.7%) had Glasgow coma scale scores less than 15 (13/14). The Glasgow coma scale correctly identified only two cases with positive CT findings with 11.11% sensitivity. The percentage of skull fracture (0.9% vs 5%, P = 0.030) was significantly lower in patients with unjustified CT scans than in patients with clinically justified CT scans. There was fair to substantial agreement between the ED physicians and the CCHR (κ = 35–61%). Two ED physicians identified all cases of justified CT scan with 100% sensitivity (95% CI 71.51–100%). Conclusion The level of education regarding the CCHR was found to be optimal among emergency physicians using a case-based scenario survey. The CCHR was found to have a poor compliance potential in

The role of erosion by fish in shaping topography around Hudson submarine canyon.

USGS Publications Warehouse

Twichell, D.C.; Grimes, Craig B.; Jones, R. S.; Able, K.W.

1985-01-01

An 800-km 2 area of rough topography around the head of Hudson Canyon off the eastern United States is attributed to erosion by tilefish ( Lopholatilus chamaeleonticeps ) and associated species of crustaceans. The rough topography has a relief of 1-10 m, occurs in water depths of 120-500 m, and has been cut into a semilithified, silty clay substrate since the onset of the Holocene transgression. Commercial fishing activity indicates that a large population of tilefish, which dig burrows in the sea floor, occupy the area of the rough topography. Average tilefish burrows are 1.6 m in diameter and 1.7 m in depth. They have a clustered, not uniform, distribution, and their average density is 2,500 per km 2 . The close match of areas of rough topography and high tilefish populations, the active burrowing of the sea floor, and the clustered distribution of the burrows suggest that the hummocky topography in this area may be the result of continuous erosion by tilefish and associated crustaceans during the Holocene. An erosion rate of 13 cm per 1,000 years is necessary to create this topography during the past 13,000 years--and 18 cm per 1,000 years if(as is more likely based on the depths at which tilefish presently are found) the erosion started 9,000 years ago.

Spike voltage topography in temporal lobe epilepsy.

PubMed

Asadi-Pooya, Ali A; Asadollahi, Marjan; Shimamoto, Shoichi; Lorenzo, Matthew; Sperling, Michael R

2016-07-15

We investigated the voltage topography of interictal spikes in patients with temporal lobe epilepsy (TLE) to see whether topography was related to etiology for TLE. Adults with TLE, who had epilepsy surgery for drug-resistant seizures from 2011 until 2014 at Jefferson Comprehensive Epilepsy Center were selected. Two groups of patients were studied: patients with mesial temporal sclerosis (MTS) on MRI and those with other MRI findings. The voltage topography maps of the interictal spikes at the peak were created using BESA software. We classified the interictal spikes as polar, basal, lateral, or others. Thirty-four patients were studied, from which the characteristics of 340 spikes were investigated. The most common type of spike orientation was others (186 spikes; 54.7%), followed by lateral (146; 42.9%), polar (5; 1.5%), and basal (3; 0.9%). Characteristics of the voltage topography maps of the spikes between the two groups of patients were somewhat different. Five spikes in patients with MTS had polar orientation, but none of the spikes in patients with other MRI findings had polar orientation (odds ratio=6.98, 95% confidence interval=0.38 to 127.38; p=0.07). Scalp topographic mapping of interictal spikes has the potential to offer different information than visual inspection alone. The present results do not allow an immediate clinical application of our findings; however, detecting a polar spike in a patient with TLE may increase the possibility of mesial temporal sclerosis as the underlying etiology. Copyright © 2016 Elsevier B.V. All rights reserved.

Insect Wing Membrane Topography Is Determined by the Dorsal Wing Epithelium

PubMed Central

Belalcazar, Andrea D.; Doyle, Kristy; Hogan, Justin; Neff, David; Collier, Simon

2013-01-01

The Drosophila wing consists of a transparent wing membrane supported by a network of wing veins. Previously, we have shown that the wing membrane cuticle is not flat but is organized into ridges that are the equivalent of one wing epithelial cell in width and multiple cells in length. These cuticle ridges have an anteroposterior orientation in the anterior wing and a proximodistal orientation in the posterior wing. The precise topography of the wing membrane is remarkable because it is a fusion of two independent cuticle contributions from the dorsal and ventral wing epithelia. Here, through morphological and genetic studies, we show that it is the dorsal wing epithelium that determines wing membrane topography. Specifically, we find that wing hair location and membrane topography are coordinated on the dorsal, but not ventral, surface of the wing. In addition, we find that altering Frizzled Planar Cell Polarity (i.e., Fz PCP) signaling in the dorsal wing epithelium alone changes the membrane topography of both dorsal and ventral wing surfaces. We also examined the wing morphology of two model Hymenopterans, the honeybee Apis mellifera and the parasitic wasp Nasonia vitripennis. In both cases, wing hair location and wing membrane topography are coordinated on the dorsal, but not ventral, wing surface, suggesting that the dorsal wing epithelium also controls wing topography in these species. Because phylogenomic studies have identified the Hymenotera as basal within the Endopterygota family tree, these findings suggest that this is a primitive insect character. PMID:23316434

Topography of the Betics: crustal thickening, dynamic topography and relief inheritance

NASA Astrophysics Data System (ADS)

Janowski, Marianne; Loget, Nicolas; Bellahsen, Nicolas; Husson, Laurent; Le Pourhiet, Laetitia; Meyer, Bertrand

2017-04-01

The main mechanism that explains high orogenic topographies is the isostatic adjustment due to crustal thickening. However in the Betic Cordillera (South Spain), the present-day elevation and crustal thickness are not correlated. That is at odds with the general premise of isostasy and requires reappraising the question of the driving mechanisms leading to the current topography. The Betics are located at the western edge of the alpine Mediterranean belt. Its Cenozoic orogenic building was disrupted by a major crustal thinning event induced by a slab rollback in the internal zones (Alboran domain) during Neogene. Topography was largely levelled and flooded by the sea during Neogene extension, and then has been folded since the Late Tortonian inversion. The present-day topography shows flat summits still preserved from fluvial regression in the internal zones (central and eastern Betics). These low-relief surfaces may be inherited from the Neogene planation toward sea-level as rocks cooling histories inferred from low-temperature thermochronology seem to point it out. Post-Tortonian shortening estimated thanks to a crustal-scale N-S cross-section in the eastern Betics (at the Sierra Nevada longitude) does not exceed few kilometers which is much lower than the shortening required by isostatic equilibrium, and is thus insufficient to explain the post-Tortonian topography building. We tested the hypothesis that mantle dynamics could in fact be an important mechanism that explains the topography of the Betics. We first computed the residual topography (i.e. the non-isostatic component of the elevation) using the most recent published Moho mapping of the area. In the western Betics, our results show important negative residual topography (down to -3 km) possibly associated with the west-Alboran slab suction. In the eastern Betics however, positive residual topography is important (up to +3 km) and can be explained by the dynamic mantle support of the topography, possibly

External factors affecting data acquisition during corneal topography examination.

PubMed

González-Méijome, José Manuel; Queirós, Antonio; Jorge, Jorge; Fernandes, Paulo; Cerviño, Alejandro; de Almeida, José Borges

2007-03-01

To analyze the factors affecting data acquisition during corneal topography examination with the Medmont E-300 videokeratoscope and to provide strategies to minimize their effects. Sixty eyes from thirty young adults were examined. A second observer registered incidences with the potential to affect data acquisition. Those factors were correlated with the difficulty of measurements as judged subjectively by the practitioner who performed the examination. Measurements of axial curvature were analyzed to evaluate the variability expressed as intrasession and intersession coefficient of variation and the standard error of the mean (SEM). The level of difficulty rated by the practitioner was in general low, with 70% of the eyes being easy or very easy to measure. For the remaining 30% of the eyes, corneal topography measurements were considered to be difficult (27%) or very difficult (3%). Of the external parameters investigated, only fixation instability (P<0.001, chi2) and the need for head repositioning (P=0.024, chi2) were associated significantly with a higher level of difficulty, as rated subjectively by the practitioner. Further analysis showed that some external factors, including those previously mentioned and others related to tear instability, affect the variability of measurements at certain corneal locations, particularly in the vertical meridian when related to tear instability and in the horizontal meridian when related to the need for head repositioning on the chin rest owing to physiognomy interferences with the keratoscope cone. Intersession SEM improved when three readings from each session were considered. The level of subjective difficulty found during videokeratoscopy examination is correlated strongly with fixation instability and the need for head reorientation in the chin rest, whereas tear-related events seem to be less relevant in the practitioner perception of test ease or difficulty. Those factors have relevance in measurement variability.

Dynamic Topography Revisited

NASA Astrophysics Data System (ADS)

Moresi, Louis

2015-04-01

Dynamic Topography Revisited Dynamic topography is usually considered to be one of the trinity of contributing causes to the Earth's non-hydrostatic topography along with the long-term elastic strength of the lithosphere and isostatic responses to density anomalies within the lithosphere. Dynamic topography, thought of this way, is what is left over when other sources of support have been eliminated. An alternate and explicit definition of dynamic topography is that deflection of the surface which is attributable to creeping viscous flow. The problem with the first definition of dynamic topography is 1) that the lithosphere is almost certainly a visco-elastic / brittle layer with no absolute boundary between flowing and static regions, and 2) the lithosphere is, a thermal / compositional boundary layer in which some buoyancy is attributable to immutable, intrinsic density variations and some is due to thermal anomalies which are coupled to the flow. In each case, it is difficult to draw a sharp line between each contribution to the overall topography. The second definition of dynamic topography does seem cleaner / more precise but it suffers from the problem that it is not measurable in practice. On the other hand, this approach has resulted in a rich literature concerning the analysis of large scale geoid and topography and the relation to buoyancy and mechanical properties of the Earth [e.g. refs 1,2,3] In convection models with viscous, elastic, brittle rheology and compositional buoyancy, however, it is possible to examine how the surface topography (and geoid) are supported and how different ways of interpreting the "observable" fields introduce different biases. This is what we will do. References (a.k.a. homework) [1] Hager, B. H., R. W. Clayton, M. A. Richards, R. P. Comer, and A. M. Dziewonski (1985), Lower mantle heterogeneity, dynamic topography and the geoid, Nature, 313(6003), 541-545, doi:10.1038/313541a0. [2] Parsons, B., and S. Daly (1983), The

Outcomes and radiographic findings of anatomic press-fit radial head arthroplasty.

PubMed

Levy, Jonathan C; Formaini, Nathan T; Kurowicki, Jennifer

2016-05-01

Radial head arthroplasty (RHA) is a popular method of treatment for complex fractures of the radial head. The purpose of this study was to investigate patient outcomes and radiographic findings associated with a single anatomic monopolar press-fit radial head system commonly used for the treatment of radial head fractures. A retrospective review of prospectively collected data was performed for a consecutive series of patients treated with a press-fit anatomically designed RHA between November 2007 and April 2014. The most recent radiographs were evaluated for loosening, stress shielding, and instability. Postoperative motion and outcomes were reported at most recent follow-up. At an average follow-up of 30 months, 6 of the 15 patients (40%) demonstrated radiographic loosening. Six of the 9 patients (67%) without loosening demonstrated stress shielding (average, 6 mm). Functional outcome scores included a mean American Shoulder and Elbow Surgeons score of 70, Mayo Elbow Performance Score of 85, visual analog scale score for pain of 2, visual analog scale score for function of 7, and Single Assessment Numeric Evaluation score of 75. Average flexion-extension arc was 14° to 138°, and average pronation-supination was 75° to 74°. All 6 of the patients with radiographic loosening had undergone RHA with an associated ligamentous injury repair. Satisfaction among patients was high as no patient reported an unsatisfactory outcome. The use of an anatomic, press-fit monopolar RHA in the management of acute complex radial head fractures has yielded excellent clinical outcomes despite high rates of radiographic loosening and stress shielding. Press-fit RHA in the setting of ligamentous injury warrants further investigation because of a high rate of implant loosening observed. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Fine-scale topography in sensory systems: insights from Drosophila and vertebrates

PubMed Central

Kaneko, Takuya; Ye, Bing

2015-01-01

To encode the positions of sensory stimuli, sensory circuits form topographic maps in the central nervous system through specific point-to-point connections between pre- and post-synaptic neurons. In vertebrate visual systems, the establishment of topographic maps involves the formation of a coarse topography followed by that of fine-scale topography that distinguishes the axon terminals of neighboring neurons. It is known that intrinsic differences in the form of broad gradients of guidance molecules instruct coarse topography while neuronal activity is required for fine-scale topography. On the other hand, studies in the Drosophila visual system have shown that intrinsic differences in cell adhesion among the axon terminals of neighboring neurons instruct the fine-scale topography. Recent studies on activity-dependent topography in the Drosophila somatosensory system have revealed a role of neuronal activity in creating molecular differences among sensory neurons for establishing fine-scale topography, implicating a conserved principle. Here we review the findings in both Drosophila and vertebrates and propose an integrated model for fine-scale topography. PMID:26091779

Fine-scale topography in sensory systems: insights from Drosophila and vertebrates.

PubMed

Kaneko, Takuya; Ye, Bing

2015-09-01

To encode the positions of sensory stimuli, sensory circuits form topographic maps in the central nervous system through specific point-to-point connections between pre- and postsynaptic neurons. In vertebrate visual systems, the establishment of topographic maps involves the formation of a coarse topography followed by that of fine-scale topography that distinguishes the axon terminals of neighboring neurons. It is known that intrinsic differences in the form of broad gradients of guidance molecules instruct coarse topography while neuronal activity is required for fine-scale topography. On the other hand, studies in the Drosophila visual system have shown that intrinsic differences in cell adhesion among the axon terminals of neighboring neurons instruct the fine-scale topography. Recent studies on activity-dependent topography in the Drosophila somatosensory system have revealed a role of neuronal activity in creating molecular differences among sensory neurons for establishing fine-scale topography, implicating a conserved principle. Here we review the findings in both Drosophila and vertebrates and propose an integrated model for fine-scale topography.

Silk Film Topography Directs Collective Epithelial Cell Migration

PubMed Central

Rosenblatt, Mark I.

2012-01-01

The following study provides new insight into how surface topography dictates directed collective epithelial cell sheet growth through the guidance of individual cell movement. Collective cell behavior of migrating human corneal limbal-epithelial cell sheets were studied on highly biocompatible flat and micro-patterned silk film surfaces. The silk film edge topography guided the migratory direction of individual cells making up the collective epithelial sheet, which resulted in a 75% increase in total culture elongation. This was due to a 3-fold decrease in cell sheet migration rate efficiency for movement perpendicular to the topography edge. Individual cell migration direction is preferred in the parallel approach to the edge topography where localization of cytoskeletal proteins to the topography’s edge region is reduced, which results in the directed growth of the collective epithelial sheet. Findings indicate customized biomaterial surfaces may be created to direct both the migration rate and direction of tissue epithelialization. PMID:23185573

Head multidetector computed tomography: emergency medicine physicians overestimate the pretest probability and legal risk of significant findings.

PubMed

Baskerville, Jerry Ray; Herrick, John

2012-02-01

This study focuses on clinically assigned prospective estimated pretest probability and pretest perception of legal risk as independent variables in the ordering of multidetector computed tomographic (MDCT) head scans. Our primary aim is to measure the association between pretest probability of a significant finding and pretest perception of legal risk. Secondarily, we measure the percentage of MDCT scans that physicians would not order if there was no legal risk. This study is a prospective, cross-sectional, descriptive analysis of patients 18 years and older for whom emergency medicine physicians ordered a head MDCT. We collected a sample of 138 patients subjected to head MDCT scans. The prevalence of a significant finding in our population was 6%, yet the pretest probability expectation of a significant finding was 33%. The legal risk presumed was even more dramatic at 54%. These data support the hypothesis that physicians presume the legal risk to be significantly higher than the risk of a significant finding. A total of 21% or 15% patients (95% confidence interval, ±5.9%) would not have been subjected to MDCT if there was no legal risk. Physicians overestimated the probability that the computed tomographic scan would yield a significant result and indicated an even greater perceived medicolegal risk if the scan was not obtained. Physician test-ordering behavior is complex, and our study queries pertinent aspects of MDCT testing. The magnification of legal risk vs the pretest probability of a significant finding is demonstrated. Physicians significantly overestimated pretest probability of a significant finding on head MDCT scans and presumed legal risk. Copyright © 2012 Elsevier Inc. All rights reserved.

Topography as a contextual variable in infectious disease transmission.

PubMed

Montoya, Isaac D

2004-01-01

This paper examines whether or not topography is a contextual variable that indirectly influences the transmission of infectious diseases. Age, gender, race/ethnicity, education level, economic status, injection drug use, and high-risk sexual behavior are known to influence infectious diseases transmission, but the effects of topography are often overlooked. A sample of 395 drug users were chosen from census tracts based upon a target profile of drug use behavior and demographics for the city of Houston. HIV was chosen as the infectious disease used to test this hypothesis. Residents of 16 census tracts in Houston, Texas participated in this study. The findings revealed that census tracts that were 'isolated' by topographic barriers, such as bayous, parks, railroad tracks, railway yards, major thoroughfares, freeways, and unique street grids had fewer cases of HIV than census tracks that were more accessible to thru-traffic. The research findings suggest that future research studies should consider topography as being contextually related to infectious disease transmission.

Preventing probe induced topography correlated artifacts in Kelvin Probe Force Microscopy.

PubMed

Polak, Leo; Wijngaarden, Rinke J

2016-12-01

Kelvin Probe Force Microscopy (KPFM) on samples with rough surface topography can be hindered by topography correlated artifacts. We show that, with the proper experimental configuration and using homogeneously metal coated probes, we are able to obtain amplitude modulation (AM) KPFM results on a gold coated sample with rough topography that are free from such artifacts. By inducing tip inhomogeneity through contact with the sample, clear potential variations appear in the KPFM image, which correlate with the surface topography and, thus, are probe induced artifacts. We find that switching to frequency modulation (FM) KPFM with such altered probes does not remove these artifacts. We also find that the induced tip inhomogeneity causes a lift height dependence of the KPFM measurement, which can therefore be used as a check for the presence of probe induced topography correlated artifacts. We attribute the observed effects to a work function difference between the tip and the rest of the probe and describe a model for such inhomogeneous probes that predicts lift height dependence and topography correlated artifacts for both AM and FM-KPFM methods. This work demonstrates that using a probe with a homogeneous work function and preventing tip changes is essential for KPFM on non-flat samples. From the three investigated probe coatings, PtIr, Au and TiN, the latter appears to be the most suitable, because of its better resistance against coating damage. Copyright © 2016 Elsevier B.V. All rights reserved.

Tectonic control on the persistence of glacially sculpted topography

PubMed Central

Prasicek, Günther; Larsen, Isaac J.; Montgomery, David R.

2015-01-01

One of the most fundamental insights for understanding how landscapes evolve is based on determining the extent to which topography was shaped by glaciers or by rivers. More than 104 years after the last major glaciation the topography of mountain ranges worldwide remains dominated by characteristic glacial landforms such as U-shaped valleys, but an understanding of the persistence of such landforms is lacking. Here we use digital topographic data to analyse valley shapes at sites worldwide to demonstrate that the persistence of U-shaped valleys is controlled by the erosional response to tectonic forcing. Our findings indicate that glacial topography in Earth's most rapidly uplifting mountain ranges is rapidly replaced by fluvial topography and hence valley forms do not reflect the cumulative action of multiple glacial periods, implying that the classic physiographic signature of glaciated landscapes is best expressed in, and indeed limited by, the extent of relatively low-uplift terrain. PMID:26271245

Modeling Earth's surface topography: decomposition of the static and dynamic components

NASA Astrophysics Data System (ADS)

Guerri, M.; Cammarano, F.; Tackley, P. J.

2017-12-01

Isolating the portion of topography supported by mantle convection, the so-called dynamic topography, would give us precious information on vigor and style of the convection itself. Contrasting results on the estimate of dynamic topography motivate us to analyse the sources of uncertainties affecting its modeling. We obtain models of mantle and crust density, leveraging on seismic and mineral physics constraints. We use the models to compute isostatic topography and residual topography maps. Estimates of dynamic topography and associated synthetic geoid are obtained by instantaneous mantle flow modeling. We test various viscosity profiles and 3D viscosity distributions accounting for inferred lateral variations in temperature. We find that the patterns of residual and dynamic topography are robust, with an average correlation coefficient of 0.74 and 0.71, respectively. The amplitudes are however poorly constrained. For the static component, the considered lithospheric mantle density models result in topographies that differ, on average, 720 m, with peaks reaching 1.7 km. The crustal density models produce variations in isostatic topography averaging 350 m, with peaks of 1 km. For the dynamic component, we obtain peak-to-peak topography amplitude exceeding 3 km for all the tested mantle density and viscosity models. Such values of dynamic topography produce geoid undulations that are not in agreement with observations. Assuming chemical heterogeneities in the lower mantle, in correspondence with the LLSVPs (Large Low Shear wave Velocity Provinces), helps to decrease the amplitudes of dynamic topography and geoid, but reduces the correlation between synthetic and observed geoid. The correlation coefficients between the residual and dynamic topography maps is always less than 0.55. In general, our results indicate that, i) current knowledge of crust density, mantle density and mantle viscosity is still limited, ii) it is important to account for all the various

Laser-based nanoengineering of surface topographies for biomedical applications

NASA Astrophysics Data System (ADS)

Schlie, Sabrina; Fadeeva, Elena; Koroleva, Anastasia; Ovsianikov, Aleksandr; Koch, Jürgen; Ngezahayo, Anaclet; Chichkov, Boris. N.

2011-04-01

In this study femtosecond laser systems were used for nanoengineering of special surface topographies in silicon and titanium. Besides the control of feature sizes, we demonstrated that laser structuring caused changes in material wettability due to a reduced surface contact area. These laser-engineered topographies were tested for their capability to control cellular behavior of human fibroblasts, SH-SY5Y neuroblastoma cells, and MG-63 osteoblasts. We found that fibroblasts reduced cell growth on the structures, while the other cell types proliferated at the same rate. These findings make laser-surface structuring very attractive for biomedical applications. Finally, to explain the results the correlation between topography and the biophysics of cellular adhesion, which is the key step of selective cell control, is discussed.

The interaction of plume heads with compositional discontinuities in the Earth's mantle

NASA Technical Reports Server (NTRS)

Manga, Michael; Stone, Howard A.; O'Connell, Richard J.

1993-01-01

The effects of compositional discontinuities of density and viscosity in the Earth's mantle on the ascent of mantle plume heads is studied using a boundary integral numerical technique. Three specific problems are considered: (1) a plume head rising away from a deformable interface, (2) a plume head passing through an interface, and (3) a plume head approaching the surface of the Earth. For the case of a plume attached to a free-surface, the calculated time-dependent plume shapesare compared with experimental results. Two principle modes of plume head deformation are observed: plume head elingation or the formation of a cavity inside the plume head. The inferred structure of mantle plumes, namely, a large plume head with a long tail, is characteristic of plumes attached to their source region, and also of buoyant material moving away from an interface and of buoyant material moving through an interface from a high- to low-viscosity region. As a rising plume head approaches the upper mantle, most of the lower mantle will quickly drain from the gap between the plume head and the upper mantle if the plume head enters the upper mantle. If the plume head moves from a high- to low-viscosity region, the plume head becomes significantly elongated and, for the viscosity contrasts thought to exist in the Earth, could extend from the 670 km discontinuity to the surface. Plume heads that are extended owing to a viscosity decrease in the upper mantle have a cylindrical geometry. The dynamic surface topography induced by plume heads is bell-shaped when the top of the plume head is at depths greater than about 0.1 plume head radii. As the plume head approaches the surface and spreads, the dynamic topography becomes plateau-shaped. The largest stresses are produced in the early stages of plume spreading when the plume head is still nearly spherical, and the surface expression of these stresses is likely to be dominated by radial extension. As the plume spreads, compressional

Isostatic and dynamic support of high topography on a North Atlantic passive margin

NASA Astrophysics Data System (ADS)

Pedersen, Vivi K.; Huismans, Ritske S.; Moucha, Robert

2016-07-01

Substantial controversy surrounds the origin of high topography along passive continental margins. Here we focus on the well-documented elevated passive margin in southwestern Scandinavia, and quantify the relative contributions of crustal isostasy and dynamic topography in controlling the present topography. We find that majority of the topography is compensated by the crustal structure, suggesting a topographic age that is in accord with the 400 Myr old Caledonian orogenesis. In addition, we propose that dynamic uplift of ∼300 m has rejuvenated existing topography locally in the coastal region over the last 10 Myr. Such uplift, combined with a general sea level fall, can help explain a variety of observations that have traditionally been interpreted in favor of a peneplain uplift model. We conclude that high topography along the Scandinavian margin cannot represent remnants of a peneplain uplifted within the last 20 Myr. The topography must have been high since the Caledonian orogeny.

Computed tomographic findings in dogs with head trauma and development of a novel prognostic computed tomography-based scoring system.

PubMed

Chai, Orit; Peery, Dana; Bdolah-Abram, Tali; Moscovich, Efrat; Kelmer, Efrat; Klainbart, Sigal; Milgram, Joshua; Shamir, Merav H

2017-09-01

OBJECTIVE To characterize CT findings and outcomes in dogs with head trauma and design a prognostic scale. ANIMALS 27 dogs admitted to the Koret School Veterinary Teaching Hospital within 72 hours after traumatic head injury that underwent CT imaging of the head. PROCEDURES Data were extracted from medical records regarding dog signalment, history, physical and neurologic examination findings, and modified Glasgow coma scale scores. All CT images were retrospectively evaluated by a radiologist unaware of dog status. Short-term (10 days after trauma) and long-term (≥ 6 months after trauma) outcomes were determined, and CT findings and other variables were analyzed for associations with outcome. A prognostic CT-based scale was developed on the basis of the results. RESULTS Cranial vault fractures, parenchymal abnormalities, or both were identified via CT in 24 of 27 (89%) dogs. Three (11%) dogs had only facial bone fractures. Intracranial hemorrhage was identified in 16 (59%) dogs, cranial vault fractures in 15 (56%), midline shift in 14 (52%), lateral ventricle asymmetry in 12 (44%), and hydrocephalus in 7 (26%). Hemorrhage and ventricular asymmetry were significantly and negatively associated with short- and long-term survival, respectively. The developed 7-point prognostic scale included points for hemorrhage, midline shift or lateral ventricle asymmetry, cranial vault fracture, and depressed fracture (1 point each) and infratentorial lesion (3 points). CONCLUSIONS AND CLINICAL RELEVANCE The findings reported here may assist in determining prognoses for other dogs with head trauma. The developed scale may be useful for outcome assessment of dogs with head trauma; however, it must be validated before clinical application.

Topography at the inner core boundary

NASA Astrophysics Data System (ADS)

Lasbleis, M.; Forquenot, Q.; Deguen, R.

2017-12-01

Topography at the inner core boundary has been proposed to explain surprising seismic observations of some regional studies. Such observations are still debatted, and numerical values of possible inner core topography have been proposed ranging from no topography to "inner core mountains" (10km heigth over lengthscales of 20km, as in Dai et al. 2012). The inner core boundary is a peculiar boundary, as it is the place where the iron alloy constituting the core freezes. The existence of a significant topography on such a boundary is possible, but unlikely. At thermodynamic equilibrium, no topography is expected, as any material above the equilibrium radius would have melted and any below would have freezed. However, mechanical forcing may push the system out of equilibrium. Dynamical topography could be forced by convective flows in the inner core or by outer core heterogeneities. A topography induced by outer core convection would be short-lived when compared to geodynamical processes in the bulk of the inner core (τ ≈ 10-100 Myears), but long-lived compared to observations. Here, we would like to give a geodynamical perspective over inner core topography. We constrain plausible amplitude of inner core topography, and discuss the implications for seismic observations. We consider topography created by viscous flows in the bulk of the inner core and by variations of growth rate on regional lengthscale due to outer core convection. This approach allows us to consider both internal and external forcings on the topography. We treat topography forcings as stochastic processes, and calculate the probability of observing a given topography. Based on preliminary results, the high values for observed topography can not be interpreted as a normal behavior of core dynamics. If confirmed, the regions are likely to be anomalous and originated from outliers in the distribution of stochastic processes.

OpenTopography: Enabling Online Access to High-Resolution Lidar Topography Data and Processing Tools

NASA Astrophysics Data System (ADS)

Crosby, Christopher; Nandigam, Viswanath; Baru, Chaitan; Arrowsmith, J. Ramon

2013-04-01

High-resolution topography data acquired with lidar (light detection and ranging) technology are revolutionizing the way we study the Earth's surface and overlying vegetation. These data, collected from airborne, tripod, or mobile-mounted scanners have emerged as a fundamental tool for research on topics ranging from earthquake hazards to hillslope processes. Lidar data provide a digital representation of the earth's surface at a resolution sufficient to appropriately capture the processes that contribute to landscape evolution. The U.S. National Science Foundation-funded OpenTopography Facility (http://www.opentopography.org) is a web-based system designed to democratize access to earth science-oriented lidar topography data. OpenTopography provides free, online access to lidar data in a number of forms, including the raw point cloud and associated geospatial-processing tools for customized analysis. The point cloud data are co-located with on-demand processing tools to generate digital elevation models, and derived products and visualizations which allow users to quickly access data in a format appropriate for their scientific application. The OpenTopography system is built using a service-oriented architecture (SOA) that leverages cyberinfrastructure resources at the San Diego Supercomputer Center at the University of California San Diego to allow users, regardless of expertise level, to access these massive lidar datasets and derived products for use in research and teaching. OpenTopography hosts over 500 billion lidar returns covering 85,000 km2. These data are all in the public domain and are provided by a variety of partners under joint agreements and memoranda of understanding with OpenTopography. Partners include national facilities such as the NSF-funded National Center for Airborne Lidar Mapping (NCALM), as well as non-governmental organizations and local, state, and federal agencies. OpenTopography has become a hub for high-resolution topography

Morphometric findings in avascular necrosis of the femoral head.

PubMed

Kamal, Diana; Trăistaru, Rodica; Alexandru, D O; Kamal, C K; Pirici, D; Pop, O T; Mălăescu, D Gh

2012-01-01

Avascular necrosis of the femoral head is an illness with a controversial etiology, the trigger event being the suppression of blood flow to the femoral head. The disease affects mostly young adults within their third and fifth decade, the majority of the patients being men. The main risk factors are trauma, chronic alcohol consumption, smoking, corticotherapy. The main goal of our study is to describe the morphometric changes found in the bone tissue of patients diagnosed with avascular necrosis of the femoral head, with different risk factors, by comparing the area of bone trabeculae inside the area of necrosis with that from the adjacent viable tissue. The morphometric study used biological material from 16 patients with ages between 29 and 57 years, who underwent surgery for avascular necrosis of the femoral head. They were admitted in the Orthopedics Department at the Emergency County Hospital in Craiova between 2010 and 2011 and were split into four groups. Group I presented trauma as the main risk factor, Group II had corticotherapy as the defining risk factor, Group III presented chronic alcohol consumption and Group IV was represented by the patients who smoked and exhibited chronic alcohol consumption. There was not a significant statistical difference between the areas of bone trabeculae of the four groups when we compared viable bone tissue to the necrotized one. Knowing the risk factors of the avascular necrosis of the femoral head is critical to the management of the disease, because diagnosing it in an early stage is a necessity for obtaining a good result for conservative treatment.

Spectral Topography Generation for Arbitrary Grids

NASA Astrophysics Data System (ADS)

Oh, T. J.

2015-12-01

A new topography generation tool utilizing spectral transformation technique for both structured and unstructured grids is presented. For the source global digital elevation data, the NASA Shuttle Radar Topography Mission (SRTM) 15 arc-second dataset (gap-filling by Jonathan de Ferranti) is used and for land/water mask source, the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) 30 arc-second land water mask dataset v5 is used. The original source data is coarsened to a intermediate global 2 minute lat-lon mesh. Then, spectral transformation to the wave space and inverse transformation with wavenumber truncation is performed for isotropic topography smoothness control. Target grid topography mapping is done by bivariate cubic spline interpolation from the truncated 2 minute lat-lon topography. Gibbs phenomenon in the water region can be removed by overwriting ocean masked target coordinate grids with interpolated values from the intermediate 2 minute grid. Finally, a weak smoothing operator is applied on the target grid to minimize the land/water surface height discontinuity that might have been introduced by the Gibbs oscillation removal procedure. Overall, the new topography generation approach provides spectrally-derived, smooth topography with isotropic resolution and minimum damping, enabling realistic topography forcing in the numerical model. Topography is generated for the cubed-sphere grid and tested on the KIAPS Integrated Model (KIM).

The shallow water equation and the vorticity equation for a change in height of the topography.

PubMed

Da, ChaoJiu; Shen, BingLu; Yan, PengCheng; Ma, DeShan; Song, Jian

2017-01-01

We consider the shallow water equation and the vorticity equations for a variable height of topography. On the assumptions that the atmosphere is incompressible and a constant density, we simplify the coupled dynamic equations. The change in topographic height is handled as the sum of the inherent and changing topography using the perturbation method, together with appropriate boundary conditions of the atmosphere, to obtain the relationship between the relative height of the flow, the inherent topography and the changing topography. We generalize the conservation of the function of relative position, and quantify the relationship between the height of the topography and the relative position of a fluid element. If the height of the topography increases (decreases), the relative position of a fluid element descends (ascends). On this basis, we also study the relationship between the vorticity and the topography to find the vorticity decreasing (increasing) for an increasing (decreasing) height of the topography.

The shallow water equation and the vorticity equation for a change in height of the topography

PubMed Central

Shen, BingLu; Yan, PengCheng; Ma, DeShan; Song, Jian

2017-01-01

We consider the shallow water equation and the vorticity equations for a variable height of topography. On the assumptions that the atmosphere is incompressible and a constant density, we simplify the coupled dynamic equations. The change in topographic height is handled as the sum of the inherent and changing topography using the perturbation method, together with appropriate boundary conditions of the atmosphere, to obtain the relationship between the relative height of the flow, the inherent topography and the changing topography. We generalize the conservation of the function of relative position, and quantify the relationship between the height of the topography and the relative position of a fluid element. If the height of the topography increases (decreases), the relative position of a fluid element descends (ascends). On this basis, we also study the relationship between the vorticity and the topography to find the vorticity decreasing (increasing) for an increasing (decreasing) height of the topography. PMID:28591129

Theoretical evaluation of accuracy in position and size of brain activity obtained by near-infrared topography

NASA Astrophysics Data System (ADS)

Kawaguchi, Hiroshi; Hayashi, Toshiyuki; Kato, Toshinori; Okada, Eiji

2004-06-01

Near-infrared (NIR) topography can obtain a topographical distribution of the activated region in the brain cortex. Near-infrared light is strongly scattered in the head, and the volume of tissue sampled by a source-detector pair on the head surface is broadly distributed in the brain. This scattering effect results in poor resolution and contrast in the topographic image of the brain activity. In this study, a one-dimensional distribution of absorption change in a head model is calculated by mapping and reconstruction methods to evaluate the effect of the image reconstruction algorithm and the interval of measurement points for topographic imaging on the accuracy of the topographic image. The light propagation in the head model is predicted by Monte Carlo simulation to obtain the spatial sensitivity profile for a source-detector pair. The measurement points are one-dimensionally arranged on the surface of the model, and the distance between adjacent measurement points is varied from 4 mm to 28 mm. Small intervals of the measurement points improve the topographic image calculated by both the mapping and reconstruction methods. In the conventional mapping method, the limit of the spatial resolution depends upon the interval of the measurement points and spatial sensitivity profile for source-detector pairs. The reconstruction method has advantages over the mapping method which improve the results of one-dimensional analysis when the interval of measurement points is less than 12 mm. The effect of overlapping of spatial sensitivity profiles indicates that the reconstruction method may be effective to improve the spatial resolution of a two-dimensional reconstruction of topographic image obtained with larger interval of measurement points. Near-infrared topography with the reconstruction method potentially obtains an accurate distribution of absorption change in the brain even if the size of absorption change is less than 10 mm.

Seismic waveform inversion for core-mantle boundary topography

NASA Astrophysics Data System (ADS)

Colombi, Andrea; Nissen-Meyer, Tarje; Boschi, Lapo; Giardini, Domenico

2014-07-01

The topography of the core-mantle boundary (CMB) is directly linked to the dynamics of both the mantle and the outer core, although it is poorly constrained and understood. Recent studies have produced topography models with mutual agreement up to degree 2. A broad-band waveform inversion strategy is introduced and applied here, with relatively low computational cost and based on a first-order Born approximation. Its performance is validated using synthetic waveforms calculated in theoretical earth models that include different topography patterns with varying lateral wavelengths, from 600 to 2500 km, and magnitudes (˜10 km peak-to-peak). The source-receiver geometry focuses mainly on the Pdiff, PKP, PcP and ScS phases. The results show that PKP branches, PcP and ScS generally perform well and in a similar fashion, while Pdiff yields unsatisfactory results. We investigate also how 3-D mantle correction influences the output models, and find that despite the disturbance introduced, the models recovered do not appear to be biased, provided that the 3-D model is correct. Using cross-correlated traveltimes, we derive new topography models from both P and S waves. The static corrections used to remove the mantle effect are likely to affect the inversion, compromising the agreement between models derived from P and S data. By modelling traveltime residuals starting from sensitivity kernels, we show how the simultaneous use of volumetric and boundary kernels can reduce the bias coming from mantle structures. The joint inversion approach should be the only reliable method to invert for CMB topography using absolute cross-correlation traveltimes.

Analysis of high-throughput screening reveals the effect of surface topographies on cellular morphology.

PubMed

Hulsman, Marc; Hulshof, Frits; Unadkat, Hemant; Papenburg, Bernke J; Stamatialis, Dimitrios F; Truckenmüller, Roman; van Blitterswijk, Clemens; de Boer, Jan; Reinders, Marcel J T

2015-03-01

Surface topographies of materials considerably impact cellular behavior as they have been shown to affect cell growth, provide cell guidance, and even induce cell differentiation. Consequently, for successful application in tissue engineering, the contact interface of biomaterials needs to be optimized to induce the required cell behavior. However, a rational design of biomaterial surfaces is severely hampered because knowledge is lacking on the underlying biological mechanisms. Therefore, we previously developed a high-throughput screening device (TopoChip) that measures cell responses to large libraries of parameterized topographical material surfaces. Here, we introduce a computational analysis of high-throughput materiome data to capture the relationship between the surface topographies of materials and cellular morphology. We apply robust statistical techniques to find surface topographies that best promote a certain specified cellular response. By augmenting surface screening with data-driven modeling, we determine which properties of the surface topographies influence the morphological properties of the cells. With this information, we build models that predict the cellular response to surface topographies that have not yet been measured. We analyze cellular morphology on 2176 surfaces, and find that the surface topography significantly affects various cellular properties, including the roundness and size of the nucleus, as well as the perimeter and orientation of the cells. Our learned models capture and accurately predict these relationships and reveal a spectrum of topographies that induce various levels of cellular morphologies. Taken together, this novel approach of high-throughput screening of materials and subsequent analysis opens up possibilities for a rational design of biomaterial surfaces. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Global Topography of Titan from Cassini RADAR Data (Invited)

NASA Astrophysics Data System (ADS)

Lorenz, R. D.; Cassini RADAR Team

2010-12-01

Cassini RADAR data are used to construct a global, albeit sparsely-sampled, topography map, and to generate a hypsometric profile to compare with other planetary bodies. Titan’s hypsogram is unimodal and strikingly narrow compared with the terrestrial planets. To investigate topographic extremes, a novel variant on the classic hypsogram is introduced, with a logarithmic abscissa to highlight mountainous terrain. In such a plot, the top of the terrestrial hypsogram is quite distinct from those of Mars and Venus due to the ‘glacial buzz-saw’ that clips terrestrial topography above the snowline. In contrast to the positive skew seen in other hypsograms, with a long tail of positive relief due to mountains, there is an indication (weak, given the limited data for Titan so far) that the Titan hypsogram appears slightly negatively skewed, suggesting a significant population of unfilled depressions. Limited data permit only a simplistic comparison of Titan topography with other icy satellites but we find that the standard deviation of terrain height (albeit at different scales) is similar to those of Ganymede and Europa. The topography of terrestrial planets is sampled with the same coverage that we have for Titan to gauge what as-yet-undiscovered topographic surprises may yet be hidden by Titan’s haze.

Cytological Findings of Malignant and Benign Head and Neck Masses in Somalia.

PubMed

Baş, Yılmaz

2018-04-11

There are no up-to-date records on head and neck masses (HNMs) in Somalia. This cytological study is the first to demonstrate the benefits and findings of fine-needle aspiration cytology in evaluating HNMs in the adult population of Somalia. A total of 116 aspiration samples were taken from different levels of the neck region, except for the thyroid. Cases were classified as salivary gland, lymph node, or soft tissue/cystic lesions. They were classified according to age, gender, and cytological diagnosis. Patients included 54 (46.6%) males and 62 (53.4%) females, with a mean age of 40.6 years. Seventy-two patients (62.1%) had benign lesions, while 44 (37.9%) had malignant lesions. Necrotizing granulomatous lymphadenitis (n = 51, 70.8% of the benign findings) and lymph node metastasis of squamous cell carcinoma (n = 13, 29.5% of the malignant findings) were the most frequent findings. Fine-needle aspiration is a useful procedure in the diagnosis of neck masses. It is a cheap and easy guiding method for diagnosing granulomatous lymphadenitis and advanced-stage metastatic cancers, which are common in this country. © 2018 S. Karger AG, Basel.

Finding the most accurate method to measure head circumference for fetal weight estimation.

PubMed

Schmidt, Ulrike; Temerinac, Dunja; Bildstein, Katharina; Tuschy, Benjamin; Mayer, Jade; Sütterlin, Marc; Siemer, Jörn; Kehl, Sven

2014-07-01

Accurate measurement of fetal head biometry is important for fetal weight estimation (FWE) and is therefore an important prognostic parameter for neonatal morbidity and mortality and a valuable tool for determining the further obstetric management. Measurement of the head circumference (HC) in particular is employed in many commonly used weight equations. The aim of the present study was to find the most accurate method to measure head circumference for fetal weight estimation. This prospective study included 481 term pregnancies. Inclusion criteria were a singleton pregnancy and ultrasound examination with complete fetal biometric parameters within 3 days of delivery, and an absence of structural or chromosomal malformations. Different methods were used for ultrasound measurement of the HC (ellipse-traced, ellipse-calculated, and circle-calculated). As a reference method, HC was also determined using a measuring tape immediately after birth. FWE was carried out with Hadlock formulas, including either HC or biparietal diameter (BPD), and differences were compared using percentage error (PE), absolute percentage error (APE), limits of agreement (LOA), and cumulative distribution. The ellipse-traced method showed the best results for FWE among all of the ultrasound methods assessed. It had the lowest median APE and the narrowest LOA. With regard to the cumulative distribution, it included the largest number of cases at a discrepancy level of ±10%. The accuracy of BPD was similar to that of the ellipse-traced method when it was used instead of HC for weight estimation. Differences between the three techniques for calculating HC were small but significant. For clinical use, the ellipse-traced method should be recommended. However, when BPD is used instead of HC for FWE, the accuracy is similar to that of the ellipse-traced method. The BPD might therefore be a good alternative to head measurements in estimating fetal weight. Copyright © 2014 Elsevier Ireland Ltd. All

Online and offline tools for head movement compensation in MEG.

PubMed

Stolk, Arjen; Todorovic, Ana; Schoffelen, Jan-Mathijs; Oostenveld, Robert

2013-03-01

Magnetoencephalography (MEG) is measured above the head, which makes it sensitive to variations of the head position with respect to the sensors. Head movements blur the topography of the neuronal sources of the MEG signal, increase localization errors, and reduce statistical sensitivity. Here we describe two novel and readily applicable methods that compensate for the detrimental effects of head motion on the statistical sensitivity of MEG experiments. First, we introduce an online procedure that continuously monitors head position. Second, we describe an offline analysis method that takes into account the head position time-series. We quantify the performance of these methods in the context of three different experimental settings, involving somatosensory, visual and auditory stimuli, assessing both individual and group-level statistics. The online head localization procedure allowed for optimal repositioning of the subjects over multiple sessions, resulting in a 28% reduction of the variance in dipole position and an improvement of up to 15% in statistical sensitivity. Offline incorporation of the head position time-series into the general linear model resulted in improvements of group-level statistical sensitivity between 15% and 29%. These tools can substantially reduce the influence of head movement within and between sessions, increasing the sensitivity of many cognitive neuroscience experiments. Copyright © 2012 Elsevier Inc. All rights reserved.

Restricting the Time of Injury in Fatal Inflicted Head Injuries.

ERIC Educational Resources Information Center

Willman, Kristal Y.; Bank, David E.; Scenic, Melvin; Catwalk, David L.

1997-01-01

Review of the cases of 95 fatal head injuries in children found that brain swelling could be detected as early as 1 hour 17 minutes postinjury using computerized topography scans. Results also suggested that a reported history of a lucid interval in a case not involving an epidural hematoma is likely to be false and the injury probably inflicted.…

Evidence for a Low Bulk Crustal Density for Mars from Gravity and Topography.

PubMed

Goossens, Sander; Sabaka, Terence J; Genova, Antonio; Mazarico, Erwan; Nicholas, Joseph B; Neumann, Gregory A

2017-08-16

Knowledge of the average density of the crust of a planet is important in determining its interior structure. The combination of high-resolution gravity and topography data has yielded a low density for the Moon's crust, yet for other terrestrial planets the resolution of the gravity field models has hampered reasonable estimates. By using well-chosen constraints derived from topography during gravity field model determination using satellite tracking data, we show that we can robustly and independently determine the average bulk crustal density directly from the tracking data, using the admittance between topography and imperfect gravity. We find a low average bulk crustal density for Mars, 2582 ± 209 kg m -3 . This bulk crustal density is lower than that assumed until now. Densities for volcanic complexes are higher, consistent with earlier estimates, implying large lateral variations in crustal density. In addition, we find indications that the crustal density increases with depth.

An anencephalic monocephalus diprosopus "headed twin": postmortem and CT findings with emphasis on the cranial bones.

PubMed

Ekinci, Gazanfer; Balci, Sevim; Erzen, Canan

2005-01-01

Monocephalus diprosopus is a form of conjoined twinning characterized by a single body, one unusual head and two faces or a spectrum of duplication of the craniofacial structures. Such cases have been mainly described according to postmortem pathologic examination. This presented case is a 26-week-stillborn female fetus, with unusual facial appearance with four eyes, two mouths, two noses, two ears and a defective cranial vault. To our knowledge, a detailed computerized tomography (CT) examination of the aberrant facial and cranial bones of such a case has not been reported to date. In this reported case, we present an anencephalic monocephalus diprosopus "headed twin", and describe the CT findings with emphasis on the cranial bones.

Measuring topographies from conventional SEM acquisitions.

PubMed

Shi, Qiwei; Roux, Stéphane; Latourte, Félix; Hild, François; Loisnard, Dominique; Brynaert, Nicolas

2018-04-27

The present study extends the stereoscopic imaging principle for estimating the surface topography to two orientations, namely, normal to the electron beam axis and inclined at 70° as suited for EBSD analyses. In spite of the large angle difference, it is shown that the topography can be accurately determined using regularized global Digital Image Correlation. The surface topography is compared to another estimate issued from a 3D FIB-SEM procedure where the sample surface is first covered by a Pt layer, and its initial topography is progressively revealed from successive FIB-milling. These two methods are successfully compared on a 6% strained steel specimen in an in situ mechanical test. This analysis is supplemented by a third approach estimating the change of topography from crystal rotations as measured from successive EBSD images. This last technique ignores plastic deformation, and thus only holds in an elastic regime. For the studied example, despite the large plastic flow, it is shown that crystal rotation already accounts for a significant part of the deformation-induced topography. Copyright © 2018 Elsevier B.V. All rights reserved.

YAP-dependent Mechanotransduction is Required for Proliferation and Migration on Native-like Substrate Topography

PubMed Central

Mascharak, Shamik; Benitez, Patrick L.; Proctor, Amy C.; Madl, Christopher M.; Hu, Kenneth H.; Dewi, Ruby E.; Butte, Manish J.; Heilshorn, Sarah C.

2017-01-01

Native vascular extracellular matrices (vECM) consist of elastic fibers that impart varied topographical properties, yet most in vitro models designed to study the effects of topography on cell behavior are not representative of native architecture. Here, we engineer an electrospun elastin-like protein (ELP) system with independently tunable, vECM-mimetic topography and demonstrate that increasing topographical variation causes loss of endothelial cell-cell junction organization. This loss of VE-cadherin signaling and increased cytoskeletal contractility on more topographically varied ELP substrates in turn promote YAP activation and nuclear translocation, resulting in significantly increased endothelial cell migration and proliferation. Our findings identify YAP as a required signaling factor through which fibrous substrate topography influences cell behavior and highlights topography as a key design parameter for engineered biomaterials. PMID:27889666

Importance of Including Topography in Numerical Simulations of Venus' Atmospheric Circulation

NASA Astrophysics Data System (ADS)

Parish, H. F.; Schubert, G.; Lebonnois, S.; Covey, C. C.; Walterscheid, R. L.; Grossman, A.

2012-12-01

Venus' atmosphere is characterized by strong superrotation, in which the wind velocities at cloud heights are around 60 times faster than the surface rotation rate. The reasons for this strong superrotation are still not well understood. Since the surface of the planet is both a source and sink of atmospheric angular momentum it is important to understand and properly account for the interactions at the surface-atmosphere boundary. A key aspect of the surface-atmosphere interaction is the topography. Topography has been introduced into different general circulation models (GCMs) of Venus' atmosphere, producing significant, but widely varying effects on the atmospheric circulation. The reasons for the inconsistencies among model results are not well known, but our studies suggest they might be related to the influences of different dynamical cores. In our recent study, we have analyzed the angular momentum budget for two Venus GCMs, the Venus Community Atmosphere model (Venus CAM) and the Laboratoire de Meteorologie Dynamique (LMD) Venus GCM. Because of Venus' low magnitude surface winds, surface friction alone supplies only a relatively weak angular momentum forcing to the atmosphere. We find that if surface friction is introduced without including surface topography, the angular momentum balance of the atmosphere may be dominated by effects such as numerical diffusion, a sponge layer, or other numerical residuals that are generally included in all GCMs, and can themselves be sources of angular momentum. However, we find the mountain torque associated with realistic Venus surface topography supplies a much larger source of angular momentum than the surface friction, and dominates nonphysical numerical terms. (A similar effect occurs for rapidly rotating planets like Earth, but in this case numerical errors in the angular momentum budget are relatively small even in the absence of mountain torque). Even if surface friction dominates numerical terms in the angular

Eye and head motion during head turns in spaceflight

NASA Technical Reports Server (NTRS)

Thornton, William E.; Uri, John J.; Moore, Thomas P.; Pool, Sam L.

1988-01-01

Eye-head motion was studied pre-, in- and postflight during single voluntary head turns. A transient increase in vestibulo-ocular reflex (VOR) gain occurred early in the flight, but later trended toward normal. This increased gain was produced by a relative increase in eye counterrotation velocity. Asymmetries in gain with right and left turns also occurred, caused by asymmetries in eye counterrotation velocities. These findings were remarkably similar to those from Soviet primate studies using gaze fixation targets, except the human study trended more rapidly toward normal. These findings differ substantially from those measuring VOR gain by head oscillation, in which no significant changes were found inflight. No visual disturbances were noted in either test condition or in normal activities. These head turn studies are the only ones to date documenting any functional change in VOR in weightlessness.

Controlled surface topography regulates collective 3D migration by epithelial-mesenchymal composite embryonic tissues.

PubMed

Song, Jiho; Shawky, Joseph H; Kim, YongTae; Hazar, Melis; LeDuc, Philip R; Sitti, Metin; Davidson, Lance A

2015-07-01

Cells in tissues encounter a range of physical cues as they migrate. Probing single cell and collective migratory responses to physically defined three-dimensional (3D) microenvironments and the factors that modulate those responses are critical to understanding how tissue migration is regulated during development, regeneration, and cancer. One key physical factor that regulates cell migration is topography. Most studies on surface topography and cell mechanics have been carried out with single migratory cells, yet little is known about the spreading and motility response of 3D complex multi-cellular tissues to topographical cues. Here, we examine the response to complex topographical cues of microsurgically isolated tissue explants composed of epithelial and mesenchymal cell layers from naturally 3D organized embryos of the aquatic frog Xenopus laevis. We control topography using fabricated micropost arrays (MPAs) and investigate the collective 3D migration of these multi-cellular systems in these MPAs. We find that the topography regulates both collective and individual cell migration and that dense MPAs reduce but do not eliminate tissue spreading. By modulating cell size through the cell cycle inhibitor Mitomycin C or the spacing of the MPAs we uncover how 3D topographical cues disrupt collective cell migration. We find surface topography can direct both single cell motility and tissue spreading, altering tissue-scale processes that enable efficient conversion of single cell motility into collective movement. Copyright © 2015 Elsevier Ltd. All rights reserved.

YAP-dependent mechanotransduction is required for proliferation and migration on native-like substrate topography.

PubMed

Mascharak, Shamik; Benitez, Patrick L; Proctor, Amy C; Madl, Christopher M; Hu, Kenneth H; Dewi, Ruby E; Butte, Manish J; Heilshorn, Sarah C

2017-01-01

Native vascular extracellular matrices (vECM) consist of elastic fibers that impart varied topographical properties, yet most in vitro models designed to study the effects of topography on cell behavior are not representative of native architecture. Here, we engineer an electrospun elastin-like protein (ELP) system with independently tunable, vECM-mimetic topography and demonstrate that increasing topographical variation causes loss of endothelial cell-cell junction organization. This loss of VE-cadherin signaling and increased cytoskeletal contractility on more topographically varied ELP substrates in turn promote YAP activation and nuclear translocation, resulting in significantly increased endothelial cell migration and proliferation. Our findings identify YAP as a required signaling factor through which fibrous substrate topography influences cell behavior and highlights topography as a key design parameter for engineered biomaterials. Copyright © 2016 Elsevier Ltd. All rights reserved.

Surface Topography Hinders Bacterial Surface Motility.

PubMed

Chang, Yow-Ren; Weeks, Eric R; Ducker, William A

2018-03-21

We demonstrate that the surface motility of the bacterium, Pseudomonas aeruginosa, is hindered by a crystalline hemispherical topography with wavelength in the range of 2-8 μm. The motility was determined by the analysis of time-lapse microscopy images of cells in a flowing growth medium maintained at 37 °C. The net displacement of bacteria over 5 min is much lower on surfaces containing 2-8 μm hemispheres than on flat topography, but displacement on the 1 μm hemispheres is not lower. That is, there is a threshold between 1 and 2 μm for response to the topography. Cells on the 4 μm hemispheres were more likely to travel parallel to the local crystal axis than in other directions. Cells on the 8 μm topography were less likely to travel across the crowns of the hemispheres and were also more likely to make 30°-50° turns than on flat surfaces. These results show that surface topography can act as a significant barrier to surface motility and may therefore hinder surface exploration by bacteria. Because surface exploration can be a part of the process whereby bacteria form colonies and seek nutrients, these results help to elucidate the mechanism by which surface topography hinders biofilm formation.

Perspectives about family meals from single-headed and dual-headed households: a qualitative analysis.

PubMed

Berge, Jerica M; Hoppmann, Caroline; Hanson, Carrie; Neumark-Sztainer, Dianne

2013-12-01

Cross-sectional and longitudinal research has shown that family meals are protective for adolescent healthful eating behaviors. However, little is known about what parents think of these findings and whether parents from single- vs dual-headed households have differing perspectives about the findings. In addition, parents' perspectives regarding barriers to applying the findings on family meals in their own homes and suggestions for more widespread adoption of the findings are unknown. The current study aimed to identify single- and dual-headed household parents' perspectives regarding the research findings on family meals, barriers to applying the findings in their own homes, and suggestions for helping families have more family meals. The current qualitative study included 59 parents who participated in substudy of two linked multilevel studies-EAT 2010 (Eating and Activity in Teens) and Families and Eating and Activity in Teens (F-EAT). Parents (91.5% female) were racially/ethnically and socioeconomically diverse. Data were analyzed using a grounded theory approach. Results from the current study suggest that parents from both single- and dual-headed households have similar perspectives regarding why family meals are protective for healthful eating habits for adolescents (eg, provides structure/routine, opportunities for communication, connection), but provide similar and different reasons for barriers to family meals (eg, single-headed=cost vs dual-headed=lack of creativity) and ideas and suggestions for how to increase the frequency of family meals (eg, single-headed=give fewer options vs dual-headed=include children in the meal preparation). Findings can help inform public health intervention researchers and providers who work with adolescents and their families to understand how to approach discussions regarding reasons for having family meals, barriers to carrying out family meals, and ways to increase family meals depending on family structure. Copyright �

Perspectives about Family Meals from Single-Headed and Dual-Headed Households: A Qualitative Analysis

PubMed Central

Berge, Jerica M.; Hoppmann, Caroline; Hanson, Carrie; Neumark-Sztainer, Dianne

2013-01-01

Cross-sectional and longitudinal research has shown that family meals are protective for adolescent healthful eating behaviors. However, little is known about what parents think of these findings and whether parents from single- versus dual-headed households have differing perspectives about the findings. Additionally, parents’ perspectives regarding barriers to applying the findings on family meals in their own homes and suggestions for more wide-spread adoption of the findings are unknown. The current study aimed to identify single- and dual-headed household parents’ perspectives regarding the research findings on family meals, barriers to applying the findings in their own homes and suggestions for helping families have more family meals. The current qualitative study included 59 parents who participated in sub-study of two linked multi-level studies—EAT 2010 (Eating and Activity in Teens) and Families and Eating and Activity in Teens (F-EAT). Parents (91.5% female) were racially/ethnically and socio-economically diverse. Data were analyzed using a grounded theory approach. Results from the current study suggest that parents from both single- and dual-headed households have similar perspectives regarding why family meals are protective for healthful eating habits for adolescents (e.g., provides structure/routine, opportunities for communication, connection), but provide similar and different reasons for barriers to family meals (e.g., single-headed=cost vs. dual-headed=lack of creativity) and ideas and suggestions for how to increase the frequency of family meals (e.g., single-headed=give fewer options vs. dual-headed=include children in the meal preparation). Findings may help inform public health intervention researchers and providers who work with adolescents and their families to understand how to approach discussions regarding reasons for having family meals, barriers to carrying out family meals and ways to increase family meals depending on family

Venous malformations of the head and neck: a diagnostic approach and a proposed management approach based on clinical, radiological, and histopathology findings.

PubMed

Aboelatta, Yasser Abdallah; Nagy, Eman; Shaker, Mohamed; Massoud, Karim Samir

2014-07-01

There is no easy road map for venous malformations (VMs) of the head and neck according to which treatment modality can be chosen. The purpose of this study was to identify different types of VMs of the head and neck based on clinical, histopathology, MRI, and venography findings that help in specification of different treatment modalities. Sixty-nine patients with VMs of the head and neck were included in this study. Our results proposed a diagnostic approach for VMs of the head and neck. MRI, venography, and clinical examination had important impact in decision-making, whereas histopathology had no impact. A management approach has been suggested for each type and its subtypes. Copyright © 2013 Wiley Periodicals, Inc.

Ecomorphology of eye shape and retinal topography in waterfowl (Aves: Anseriformes: Anatidae) with different foraging modes.

PubMed

Lisney, Thomas J; Stecyk, Karyn; Kolominsky, Jeffrey; Schmidt, Brian K; Corfield, Jeremy R; Iwaniuk, Andrew N; Wylie, Douglas R

2013-05-01

Despite the large body of literature on ecomorphological adaptations to foraging in waterfowl, little attention has been paid to their sensory systems, especially vision. Here, we compare eye shape and retinal topography across 12 species representing 4 different foraging modes. Eye shape was significantly different among foraging modes, with diving and pursuit-diving species having relatively smaller corneal diameters compared to non-diving species. This may be associated with differences in ambient light intensity while foraging or an ability to tightly constrict the pupil in divers in order to facilitate underwater vision. Retinal topography was similar across all species, consisting of an oblique visual streak, a central area of peak cell density, and no discernible fovea. Because the bill faces downwards when the head is held in the normal posture in waterfowl, the visual streak will be held horizontally, allowing the horizon to be sampled with higher visual acuity. Estimates of spatial resolving power were similar among species with only the Canada goose having a higher spatial resolution. Overall, we found no evidence of ecomorphological adaptations to different foraging modes in the retinal ganglion cell layer in waterfowl. Rather, retinal topography in these birds seems to reflect the 'openness' of their habitats.

Constraints on core-mantle boundary topography from models of thermal and thermochemical convection

NASA Astrophysics Data System (ADS)

Deschamps, Frédéric; Rogister, Yves; Tackley, Paul J.

2018-01-01

Mantle flow induces dynamic topography at the core-mantle boundary (CMB), with distribution and amplitude that depend on details of the flow. To assess whether observations of CMB topography can give constraints on deep mantle structure, we determine CMB dynamic topography associated with different models of mantle convection, including thermochemical and purely thermal models. We investigate the influence of key controlling parameters, specifically the thermal viscosity ratio (ΔηT) and, for thermochemical models, the density contrast (ΔρC) and viscosity ratio (ΔηC) between primordial and regular materials. In purely thermal models, plume clusters induce positive topography with an amplitude that decreases with increasing ΔηT. In thermochemical models with moderate density contrasts, around 100-200 kg m-3, reservoirs of dense material induce depressions in CMB topography, surrounded by a ridge of positive topography. The average depression depth and ridge height increase with increasing ΔρC and ΔηC, but decrease with increasing ΔηT. We find that for purely thermal models or thermochemical models with ΔρC ˜ 90 kg m-3 and less, the long-wavelength (spherical harmonic degrees up to l = 4) dynamic topography and shear wave velocity anomalies predicted by thermochemical distributions anticorrelate. By contrast, for models with ΔρC ≥ 100 kg m-3 and ΔηC > 1, long-wavelength dynamic topography and shear wave velocity anomalies correlate well. This potentially provides a test to infer the nature, that is, either purely or mostly thermal (ΔρC ≤ 100 kg m-3 m-3) or strongly thermochemical (ΔρC ≥ 100 kg m-3), of the low shear wave velocity provinces observed by global tomographic images. The presence of post-perovskite, provided that its viscosity is similar to that of bridgmanite, does not alter these conclusions.

Asymmetric three-dimensional topography over mantle plumes.

PubMed

Burov, Evgueni; Gerya, Taras

2014-09-04

The role of mantle-lithosphere interactions in shaping surface topography has long been debated. In general, it is supposed that mantle plumes and vertical mantle flows result in axisymmetric, long-wavelength topography, which strongly differs from the generally asymmetric short-wavelength topography created by intraplate tectonic forces. However, identification of mantle-induced topography is difficult, especially in the continents. It can be argued therefore that complex brittle-ductile rheology and stratification of the continental lithosphere result in short-wavelength modulation and localization of deformation induced by mantle flow. This deformation should also be affected by far-field stresses and, hence, interplay with the 'tectonic' topography (for example, in the 'active/passive' rifting scenario). Testing these ideas requires fully coupled three-dimensional numerical modelling of mantle-lithosphere interactions, which so far has not been possible owing to the conceptual and technical limitations of earlier approaches. Here we present new, ultra-high-resolution, three-dimensional numerical experiments on topography over mantle plumes, incorporating a weakly pre-stressed (ultra-slow spreading), rheologically realistic lithosphere. The results show complex surface evolution, which is very different from the smooth, radially symmetric patterns usually assumed as the canonical surface signature of mantle upwellings. In particular, the topography exhibits strongly asymmetric, small-scale, three-dimensional features, which include narrow and wide rifts, flexural flank uplifts and fault structures. This suggests a dominant role for continental rheological structure and intra-plate stresses in controlling dynamic topography, mantle-lithosphere interactions, and continental break-up processes above mantle plumes.

Dynamic Topography at Earth's Surface: Fact or Fiction? (Invited)

NASA Astrophysics Data System (ADS)

Lithgow-Bertelloni, C. R.; Silver, P. G.

2009-12-01

Contributions to Earth’s surface topography range from short-wavelength uncompensated features due to tectonic activity, to variations in crustal structure and long-wavelength deflections of the lithosphere caused by mantle dynamics. The latter we call dynamic topography. Dynamic topography elevates or depresses the surface even if the density anomaly giving rise to flow is deep in the mantle. Dynamic topography is also a major contributor to Earth’s gravitational potential and to surface deformation. However, direct observations of dynamic topography are elusive, because signals are obscured by the isostatic contribution due to crustal and lithospheric structure. The only seemingly unequivocal signals of dynamically supported topography have been found over mantle upwellings on both continents (Africa [Lithgow-Bertelloni and Silver, 1998] and Arabia [Daradich et al., 2004]) and oceanic basins (North-Atlantic [Conrad et al., 2004]). Recent work on Africa’s geomorphic history [Moore et al., 2009] and North Atlantic gravity and topography have called even these results into questions. In downwelling regions (near slabs) no clear signals have been found. I will explore why this dichotomy may exist and relate it to the need for dynamic topography in mantle flow models, with an eye towards the effects of phase transitions, lateral variations in viscosity and layered convection. I will also present recent results on dynamic topography over flat slab segments that overturn the conventional wisdom and explain basin topography in the Andean foreland. Along with the new models I will discuss a recent global lithospheric structure model with which to compute the residual topography, i.e. the “observed” dynamic topography.

Corneal topography measurements for biometric applications

NASA Astrophysics Data System (ADS)

Lewis, Nathan D.

The term biometrics is used to describe the process of analyzing biological and behavioral traits that are unique to an individual in order to confirm or determine his or her identity. Many biometric modalities are currently being researched and implemented including, fingerprints, hand and facial geometry, iris recognition, vein structure recognition, gait, voice recognition, etc... This project explores the possibility of using corneal topography measurements as a trait for biometric identification. Two new corneal topographers were developed for this study. The first was designed to function as an operator-free device that will allow a user to approach the device and have his or her corneal topography measured. Human subject topography data were collected with this device and compared to measurements made with the commercially available Keratron Piccolo topographer (Optikon, Rome, Italy). A third topographer that departs from the standard Placido disk technology allows for arbitrary pattern illumination through the use of LCD monitors. This topographer was built and tested to be used in future research studies. Topography data was collected from 59 subjects and modeled using Zernike polynomials, which provide for a simple method of compressing topography data and comparing one topographical measurement with a database for biometric identification. The data were analyzed to determine the biometric error rates associated with corneal topography measurements. Reasonably accurate results, between three to eight percent simultaneous false match and false non-match rates, were achieved.

Role of the unfolded protein response in topography-induced osteogenic differentiation in rat bone marrow mesenchymal stem cells.

PubMed

Shi, Mengqi; Song, Wen; Han, Tianxiao; Chang, Bei; Li, Guangwen; Jin, Jianfeng; Zhang, Yumei

2017-05-01

The topography of biomaterials can significantly influence the osteogenic differentiation of cells. Understanding topographical signal transduction is critical for developing biofunctional surfaces, but the current knowledge is insufficient. Recently, numerous reports have suggested that the unfolded protein response (UPR) and osteogenic differentiation are inter-linked. Therefore, we hypothesize that the UPR pathway may be involved in the topography-induced osteogenesis. In the present study, different surface topographies were fabricated on pure titanium foils and the endoplasmic reticulum (ER) stress and UPR pathway were systematically investigated. We found that ER stress and the PERK-eIF2α-ATF4 pathway were activated in a time- and topography-dependent manner. Additionally, the activation of the PERK-eIF2α-ATF4 pathway by different topographies was in line with their osteogenic induction capability. More specifically, the osteogenic differentiation could be enhanced or weakened when the PERK-eIF2α-ATF4 pathway was promoted or inhibited, respectively. Furthermore, tuning of the degree of ER stress with different concentrations of thapsigargin revealed that mild ER stress promotes osteogenic differentiation, whereas excessive ER stress inhibits osteogenic differentiation and causes apoptosis. Taken together, our findings suggest that the UPR may play a critical role in topography-induced osteogenic differentiation, which may help to provide new insights into topographical signal transduction. Suitable implant surface topography can effectively improve bioactivity and eventual bone affinity. However, the mechanism of topographical signaling transduction is unclear and criteria for designation of an appropriate implant surface topography is lacking. This study shows that the ER stress and PERK-eIF2α-ATF4 pathway were activated by micro- and micro/nano-topographies, which is corresponding to the osteogenic induction abilities of these topographies. Furthermore

Quantitating Human Optic Disc Topography

NASA Astrophysics Data System (ADS)

Graebel, William P.; Cohan, Bruce E.; Pearch, Andrew C.

1980-07-01

A method is presented for quantitatively expressing the topography of the human optic disc, applicable in a clinical setting to the diagnosis and management of glaucoma. Pho-tographs of the disc illuminated by a pattern of fine, high contrast parallel lines are digitized. From the measured deviation of the lines as they traverse the disc surface, disc topography is calculated, using the principles of optical sectioning. The quantitators applied to express this topography have the the following advantages : sensitivity to disc shape; objectivity; going beyond the limits of cup-disc ratio estimates and volume calculations; perfect generality in a mathematical sense; an inherent scheme for determining a non-subjective reference frame to compare different discs or the same disc over time.

Multiscale Study of Currents Affected by Topography

DTIC Science & Technology

2015-09-30

1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Multiscale Study of Currents Affected by Topography ...the effects of topography on the ocean general and regional circulation with a focus on the wide range of scales of interactions. The small-scale...details of the topography and the waves, eddies, drag, and turbulence it generates (at spatial scales ranging from meters to mesoscale) interact in the

Multiscale Study of Currents Affected by Topography

DTIC Science & Technology

2015-09-30

1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Multiscale Study of Currents Affected by Topography ... topography on the ocean general circulation is challenging because of the multiscale nature of the flow interactions. Small-scale details of the... topography , and the waves, drag, and turbulence generated at the boundary, from meter scale to mesoscale, interact in the boundary layers to influence the

Impacts of Social-Emotional Curricula on Three-Year-Olds: Exploratory Findings from the Head Start CARES Demonstration. Research Snapshot. OPRE Report 2014-78

ERIC Educational Resources Information Center

Hsueh, JoAnn; Lowenstein, Amy E.; Morris, Pamela; Mattera, Shira K.; Bangser, Michael

2014-01-01

This report presents exploratory impact findings for 3-year-olds from the Head Start CARES demonstration, a large-scale randomized controlled trial implemented in Head Start centers for one academic year across the country. The study was designed primarily to test the effects of the enhancements on 4-year-olds, but it also provides an opportunity…

Enhanced Characterization of Niobium Surface Topography

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

Chen Xu, Hui Tian, Charles Reece, Michael Kelley

2011-12-01

Surface topography characterization is a continuing issue for the Superconducting Radio Frequency (SRF) particle accelerator community. Efforts are underway to both to improve surface topography, and its characterization and analysis using various techniques. In measurement of topography, Power Spectral Density (PSD) is a promising method to quantify typical surface parameters and develop scale-specific interpretations. PSD can also be used to indicate how chemical processes modifiesy the roughnesstopography at different scales. However, generating an accurate and meaningful topographic PSD of an SRF surface requires careful analysis and optimization. In this report, polycrystalline surfaces with different process histories are sampled with AFMmore » and stylus/white light interferometer profilometryers and analyzed to indicate trace topography evolution at different scales. evolving during etching or polishing. Moreover, Aan optimized PSD analysis protocol will be offered to serve the SRF surface characterization needs is presented.« less

Functional analysis screening for multiple topographies of problem behavior.

PubMed

Bell, Marlesha C; Fahmie, Tara A

2018-04-23

The current study evaluated a screening procedure for multiple topographies of problem behavior in the context of an ongoing functional analysis. Experimenters analyzed the function of a topography of primary concern while collecting data on topographies of secondary concern. We used visual analysis to predict the function of secondary topographies and a subsequent functional analysis to test those predictions. Results showed that a general function was accurately predicted for five of six (83%) secondary topographies. A specific function was predicted and supported for a subset of these topographies. The experimenters discuss the implication of these results for clinicians who have limited time for functional assessment. © 2018 Society for the Experimental Analysis of Behavior.

Mechanisms of Cdc42-mediated rat MSC differentiation on micro/nano-textured topography.

PubMed

Li, Guangwen; Song, Yanyan; Shi, Mengqi; Du, Yuanhong; Wang, Wei; Zhang, Yumei

2017-02-01

/nano-textured topography and the underlying mechanisms are not well understood. This study shows that the micropitted/nanotubular hierarchical topography produced by etching and anodic oxidation treatment drives fusiform cell morphology, cytoskeletal reorganization as well as better MSCs osteogenic differentiation. The cross-talk between Cdc42 pathway and Wnt/β-catenin pathway though GSK3β modulates the osteoinductive effect of the micro/nano-textured topography on MSCs. This finding sheds light on a novel mechanism involved in micro/nano-textured surface-mediated MSCs osteogenic differentiation and is a major step in the development of new surface modifications aiming to accelerate and enhance the process of osseointegration. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Importance of dynamic topography in Himalaya-Tibetan plateau region

NASA Astrophysics Data System (ADS)

Ghosh, A.; Singh, S.

2017-12-01

Himalaya-Tibetan plateau region has the highest topography in the world. Various studies have been done to understand the mechanisms responsible for sustaining this high topography. However, the existence of dynamic topography in this region is still uncertain, though there have been some studies exploring the role of channel flow in lower crust leading to some topography. We investigated the role of radial mantle flow in this region by studying the relationship between geoid and topography. High geoid-to-topography ratios (GTR) were observed along the Himalayas suggesting deeper compensation mechanisms. However, further north, the geoid and topography relationship became a lot more complex as high as well as low GTR values were observed. The high GTR regions also coincided with area of high filtered free air gravity anomalies, indicating dynamic support. We also looked at the spectral components of gravity, geoid and topography, and calculated response functions to distinguish between different compensation mechanisms. We estimated the average elastic thickness of the whole region to be around 40 km from coherence and admittance studies. The GTR and admittance-coherence studies suggest deeper mass anomalies playing a role in supporting the topography along Himalayas and the area between Altyn Tagh and Kunlun faults.

Impact of lithospheric rheology on surface topography

NASA Astrophysics Data System (ADS)

Liao, K.; Becker, T. W.

2017-12-01

The expression of mantle flow such as due to a buoyant plume as surface topography is a classical problem, yet the role of rheological complexities could benefit from further exploration. Here, we investigate the topographic expressions of mantle flow by means of numerical and analytical approaches. In numerical modeling, both conventional, free-slip and more realistic, stress-free boundary conditions are applied. For purely viscous rheology, a high viscosity lithosphere will lead to slight overestimates of topography for certain settings, which can be understood by effectively modified boundary conditions. Under stress-free conditions, numerical and analytical results show that the magnitude of dynamic topography decreases with increasing lithosphere thickness (L) and viscosity (ηL), as L-1 and ηL-3. The wavelength of dynamic topography increases linearly with L and (ηL/ ηM) 1/3. We also explore the time-dependent interactions of a rising plume with the lithosphere. For a layered lithosphere with a decoupling weak lower crust embedded between stronger upper crust and lithospheric mantle, dynamic topography increases with a thinner and weaker lower crust. The dynamic topography saturates when the decoupling viscosity is 3-4 orders lower than the viscosity of upper crust and lithospheric mantle. We further explore the role of visco-elastic and visco-elasto-plastic rheologies.

Global snowline and mountain topography: a contrasted view

NASA Astrophysics Data System (ADS)

Champagnac, Jean-Daniel; Herman, Frédéric; Valla, Pierre

2013-04-01

~40 and ~60° (or between ELA of ~500m to ~2500m a.s.l.). This mid-latitude relatively greater relief challenges the straightforward relationship between glaciations, erosion and topography. Oppositely, it suggests that glacier may be more efficient agent in temperate area, with an important amplitude between glacial and interglacial climate. This is consistent with the view of a very variable glacier erodibility that can erode and protect the landscape, as well as with studies documenting a bimodal location of the preferred glacial erosion, at relatively high elevation (around the long-term ELA), and at much lower elevation (close to the glacial maximum lower reaches), thanks to efficient water lubrication of the glacier bases that greatly enhance the sliding velocity (Herman et al., 2011). These findings show that the relation between the mountain topography and the long term snowline is not as straightforward as previously proposed (e.g. Egholm et al., 2009) . Beside the role of tectonic forcing highlighted by several authors (e.g. Pedersen et al., 2010;Spotila and Berger, 2010),, the importance of the glacial erosion appears to be crucial at mid latitude, but more complex at both high and low latitude. Moreover, the relief at mid latitude appears to be higher, hence suggesting a positive correlation between relief and topographic control of glacier on the landscape Champagnac, J.-D., Molnar, P., Sue, C., and Herman, F.: Tectonics, Climate, and Mountain Topography, Journal of Geophysical Research B: Solid Earth, 117, doi:10.1029/2011JB008348, 2012. Egholm, D. L., Nielsen, S. B., Pedersen, V. K., and Lesemann, J. E.: Glacial effects limiting mountain height, Nature, 460, 884-888, 2009. Herman, F., Beaud, F., Champagnac, J.-D., Lemieux, J.-M., and Sternai, P.: Glacial hydrology and erosion patterns: A mechanism for carving glacial valleys, Earth and Planetary Science Letters, 310, 498-508, 2011. Pedersen, V. K., Egholm, D. L., and Nielsen, S. B.: Alpine glacial

Early Head Start: Research Findings. Early Childhood Highlights. Volume 1, Issue 2

ERIC Educational Resources Information Center

Child Trends, 2010

2010-01-01

Early Head Start is a federally funded community-based program for low-income families with infants and toddlers and for low-income pregnant women. Created in 1995, Early Head Start strives to promote healthy prenatal outcomes for pregnant women, to enhance the development of children ages birth to three, and to promote healthy family functioning.…

Artificial topography changes the growth strategy of Spartina alterniflora, case study with wave exposure as a comparison.

PubMed

Hong, Hualong; Dai, Minyue; Lu, Haoliang; Liu, Jingchun; Zhang, Jie; Chen, Chaoqi; Xia, Kang; Yan, Chongling

2017-11-17

This paper reports findings about the growth of Spartina alterniflora (Loisel.) near an engineered coastal protection defences to discover the potential influences on vegetation growth from the artificial topography. Impacts of the artificial topography on the sediment element composition were detected by comparing the fixed effects caused by artificial topography and wave exposure using linear mixed models. Surficial sediments under the impacts of artificial topography contain elevated levels of biogenic elements and heavy metals, including C (and organic carbon), N, S, Al, Fe, Mn, Cu, Zn, As, Cd, Cr, Ni, and Pb. The results showed that element enrichment caused by artificial topography reduced the vegetation sexual reproduction. Contrary to the potential inhibition caused by direct wave exposure, which was due to the biomass accumulation limit, the inhibition caused by artificial topography was related to the transition of growth strategy. The contents of Cu, Mn, N, Ni, S and As in the sediments were critical in considering the relationship between the change in the sediment element composition and the alteration in the plant growth. Our study emphasizes the importance of rethinking the impacts of coastal development projects, especially regarding the heterogeneity of sediment element composition and its ecological consequences.

Constraints on Gusev Basin Infill from the Mars Orbiter Laser Altimeter (MOLA) Topography

NASA Technical Reports Server (NTRS)

Carter, B. L.; Frey, H.; Sakimoto, S. E. H.; Roark, J.

2001-01-01

MOLA topography provides volume estimates for Gusev crater based on higher resolution. Revisiting work previously done by Grin and Cabrol (1997), we find a substantial increase in original sedimentation estimates. Additional information is contained in the original extended abstract.

Origin of bending in uncoated microcantilever - Surface topography?

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

Lakshmoji, K.; Prabakar, K.; Tripura Sundari, S., E-mail: sundari@igcar.gov.in

2014-01-27

We provide direct experimental evidence to show that difference in surface topography on opposite sides of an uncoated microcantilever induces bending, upon exposure to water molecules. Examination on opposite sides of the microcantilever by atomic force microscopy reveals the presence of localized surface features on one side, which renders the induced stress non-uniform. Further, the root mean square inclination angle characterizing the surface topography shows a difference of 73° between the opposite sides. The absence of deflection in another uncoated microcantilever having similar surface topography confirms that in former microcantilever bending is indeed induced by differences in surface topography.

Microstructure analysis and wear behavior of titanium cermet femoral head with hard TiC layer.

PubMed

Luo, Yong; Ge, Shirong; Liu, Hongtao; Jin, Zhongmin

2009-12-11

Titanium cermet was successfully synthesized and formed a thin gradient titanium carbide coating on the surface of Ti6Al4V alloy by using a novel sequential carburization under high temperature, while the titanium cermet femoral head was produced. The titanium cermet phase and surface topography were characterized with X-ray diffraction (XRD) and backscattered electron imaging (BSE). And then the wear behavior of titanium cermet femoral head was investigated by using CUMT II artificial joint hip simulator. The surface characterization indicates that carbon effectively diffused into the titanium alloys and formed a hard TiC layer on the Ti6Al4V alloys surface with a micro-porous structure. The artificial hip joint experimental results show that titanium cermet femoral head could not only improve the wear resistance of artificial femoral head, but also decrease the wear of UHMWPE joint cup. In addition, the carburized titanium alloy femoral head could effectively control the UHMWPE debris distribution, and increase the size of UHMWPE debris. All of the results suggest that titanium cermet is a prospective femoral head material in artificial joint.

The Effects of Head Start Health Services: Executive Summary of the Head Start Health Evaluation.

ERIC Educational Resources Information Center

Fosburg, Linda B.; And Others

This report summarizes findings of an evaluation of Head Start health services. Chapter one presents an overview of the background of the evaluation project. Chapter two highlights findings for the major evaluation questions. These questions focus specifically on children's health status prior to entry into Head Start, health services subsequently…

Vesta Topography Map

NASA Image and Video Library

2013-07-08

This color-coded topography map from NASA Dawn mission shows the giant asteroid Vesta in an equirectangular projection at 32 pixels per degree, relative to an ellipsoid of 177 miles by 177 miles by 142 miles.

A Retrospective Study of Cervical Spine MRI Findings in Children with Abusive Head Trauma.

PubMed

Governale, Lance S; Brink, Farah W; Pluto, Charles P; Schunemann, Victoria A; Weber, Rachel; Rusin, Jerome; Fischer, Beth A; Letson, Megan M

2018-01-01

Increasing attention has been given to the possible association of cervical spine (c-spine) injuries with abusive head trauma (AHT). The aims of this study were to describe c-spine MRI findings in hospitalized AHT patients. This is a retrospective study of children under the age of 5 years with AHT admitted to hospital in 2004-2013. Those with c-spine MRI were identified, and the images were reviewed. 250 AHT cases were identified, with 34 (14%) undergoing c-spine MRI. Eleven patients (32%) had 25 findings, including hematoma in 2, occiput-C1-C2 edema in 3, prevertebral edema in 6, facet edema in 2, and interspinous and/or muscular edema in 10. No patients had a clinically evident c-spine injury, a clinically unstable c-spine, or required c-spine surgery. C-spine MRI may identify abnormalities not apparent upon physical examination and the procedure should therefore be considered in cases of suspected AHT. © 2017 S. Karger AG, Basel.

Electronic Cigarette Topography in the Natural Environment

PubMed Central

Morabito, P. N.; Roundtree, K. A.

2015-01-01

This paper presents the results of a clinical, observational, descriptive study to quantify the use patterns of electronic cigarette users in their natural environment. Previously published work regarding puff topography has been widely indirect in nature, and qualitative rather than quantitative, with the exception of three studies conducted in a laboratory environment for limited amounts of time. The current study quantifies the variation in puffing behaviors among users as well as the variation for a given user throughout the course of a day. Puff topography characteristics computed for each puffing session by each subject include the number of subject puffs per puffing session, the mean puff duration per session, the mean puff flow rate per session, the mean puff volume per session, and the cumulative puff volume per session. The same puff topography characteristics are computed across all puffing sessions by each single subject and across all subjects in the study cohort. Results indicate significant inter-subject variability with regard to puffing topography, suggesting that a range of representative puffing topography patterns should be used to drive machine-puffed electronic cigarette aerosol evaluation systems. PMID:26053075

Electronic Cigarette Topography in the Natural Environment.

PubMed

Robinson, R J; Hensel, E C; Morabito, P N; Roundtree, K A

2015-01-01

This paper presents the results of a clinical, observational, descriptive study to quantify the use patterns of electronic cigarette users in their natural environment. Previously published work regarding puff topography has been widely indirect in nature, and qualitative rather than quantitative, with the exception of three studies conducted in a laboratory environment for limited amounts of time. The current study quantifies the variation in puffing behaviors among users as well as the variation for a given user throughout the course of a day. Puff topography characteristics computed for each puffing session by each subject include the number of subject puffs per puffing session, the mean puff duration per session, the mean puff flow rate per session, the mean puff volume per session, and the cumulative puff volume per session. The same puff topography characteristics are computed across all puffing sessions by each single subject and across all subjects in the study cohort. Results indicate significant inter-subject variability with regard to puffing topography, suggesting that a range of representative puffing topography patterns should be used to drive machine-puffed electronic cigarette aerosol evaluation systems.

Minimal erosion of Arctic alpine topography during late Quaternary glaciation

NASA Astrophysics Data System (ADS)

Gjermundsen, Endre F.; Briner, Jason P.; Akçar, Naki; Foros, Jørn; Kubik, Peter W.; Salvigsen, Otto; Hormes, Anne

2015-10-01

The alpine topography observed in many mountainous regions is thought to have formed during repeated glaciations of the Quaternary period. Before this time, landscapes had much less relief. However, the spatial patterns and rates of Quaternary exhumation at high latitudes--where cold-based glaciers may protect rather than erode landscapes--are not fully quantified. Here we determine the exposure and burial histories of rock samples from eight summits of steep alpine peaks in northwestern Svalbard (79.5° N) using analyses of 10Be and 26Al concentrations. We find that the summits have been preserved for at least the past one million years. The antiquity of Svalbard’s alpine landscape is supported by the preservation of sediments older than one million years along a fjord valley, which suggests that both mountain summits and low-elevation landscapes experienced very low erosion rates over the past million years. Our findings support the establishment of northwestern Svalbard’s alpine topography during the early Quaternary. We suggest that, as the Quaternary ice age progressed, glacial erosion in the Arctic became inefficient and confined to ice streams, and high-relief alpine landscapes were preserved by minimally erosive glacier armour.

The development and evaluation of head probes for optical imaging of the infant head

NASA Astrophysics Data System (ADS)

Branco, Gilberto

The objective of this thesis was to develop and evaluate optical imaging probes for mapping oxygenation and haemodynamic changes in the newborn infant brain. Two imaging approaches are being developed at University College London (UCL): optical topography (surface mapping of the cortex) and optical tomography (volume imaging). Both have the potential to provide information about the function of the normal brain and about a variety of neurophysiologies! abnormalities. Both techniques require an array of optical fibres/fibre bundles to be held in contact with the head, for periods of time from tens of seconds to an hour or more. The design of suitable probes must ensure the comfort and safety of the subject, and provide measurements minimally sensitive to external sources of light and patient motion. A series of prototype adaptable helmets were developed for optical tomography of the premature infant brain using the UCL 32-channel time-resolved system. They were required to attach 32 optical fibre bundles over the infant scalp, and were designed to accommodate infants with a variety of head shapes and sizes, aged between 24-weeks gestational age and term. Continual improvements to the helmet design were introduced following the evaluation of each prototype on infants in the hospital. Data were acquired to generate images revealing the concentration and oxygenation of blood in the brain, and the response of the brain to sensory stimulation. This part of the project also involved designing and testing new methods of acquiring calibration data using reference phantoms. The second focus of the project was the development of probes for use with the UCL frequency-multiplexed near-infrared topography system. This is being used to image functional activation in the infant cortex. A series of probes were developed and experiments were conducted to evaluate their sensitivity to patient motion and to compression of the probe. The probes have been used for a variety of

Characterizing smoking topography of cannabis in heavy users

PubMed Central

Stitzer, Maxine L.; Vandrey, Ryan

2013-01-01

Rationale Little is known about the smoking topography characteristics of heavy cannabis users. Such measures may be able to predict cannabis use-related outcomes and could be used to validate self-reported measures of cannabis use. Objectives The current study was conducted to measure cannabis smoking topography characteristics during periods of ad libitum use and to correlate topography assessments with measures of self-reported cannabis use, withdrawal and craving during abstinence, and cognitive task performance. Methods Participants (N=20) completed an inpatient study in which they alternated between periods of ad libitum cannabis use and abstinence. Measures of self-reported cannabis use, smoking topography, craving, withdrawal, and sleep measures were collected. Results Participants smoked with greater intensity (e.g., greater volume, longer duration) on initial cigarette puffs with a steady decline on subsequent puffs. Smoking characteristics were significantly correlated with severity of withdrawal, notably sleep quality and architecture, and craving during abstinence, suggesting dose-related effects of cannabis use on these outcomes. Smoking characteristics generally were not significantly associated with cognitive performance. Smoking topography measures were significantly correlated with self-reported measures of cannabis use, indicating validity of these assessments, but topography measures were more sensitive than self-report in predicting cannabis-related outcomes. Conclusions A dose–effect relationship between cannabis consumption and outcomes believed to be clinically important was observed. With additional research, smoking topography assessments may become a useful clinical tool. PMID:21922170

Finite-frequency sensitivity kernels for head waves

NASA Astrophysics Data System (ADS)

Zhang, Zhigang; Shen, Yang; Zhao, Li

2007-11-01

Head waves are extremely important in determining the structure of the predominantly layered Earth. While several recent studies have shown the diffractive nature and the 3-D Fréchet kernels of finite-frequency turning waves, analogues of head waves in a continuous velocity structure, the finite-frequency effects and sensitivity kernels of head waves are yet to be carefully examined. We present the results of a numerical study focusing on the finite-frequency effects of head waves. Our model has a low-velocity layer over a high-velocity half-space and a cylindrical-shaped velocity perturbation placed beneath the interface at different locations. A 3-D finite-difference method is used to calculate synthetic waveforms. Traveltime and amplitude anomalies are measured by the cross-correlation of synthetic seismograms from models with and without the velocity perturbation and are compared to the 3-D sensitivity kernels constructed from full waveform simulations. The results show that the head wave arrival-time and amplitude are influenced by the velocity structure surrounding the ray path in a pattern that is consistent with the Fresnel zones. Unlike the `banana-doughnut' traveltime sensitivity kernels of turning waves, the traveltime sensitivity of the head wave along the ray path below the interface is weak, but non-zero. Below the ray path, the traveltime sensitivity reaches the maximum (absolute value) at a depth that depends on the wavelength and propagation distance. The sensitivity kernels vary with the vertical velocity gradient in the lower layer, but the variation is relatively small at short propagation distances when the vertical velocity gradient is within the range of the commonly accepted values. Finally, the depression or shoaling of the interface results in increased or decreased sensitivities, respectively, beneath the interface topography.

The Earth isn't flat: The (large) influence of topography on geodetic fault slip imaging.

NASA Astrophysics Data System (ADS)

Thompson, T. B.; Meade, B. J.

2017-12-01

While earthquakes both occur near and generate steep topography, most geodetic slip inversions assume that the Earth's surface is flat. We have developed a new boundary element tool, Tectosaur, with the capability to study fault and earthquake problems including complex fault system geometries, topography, material property contrasts, and millions of elements. Using Tectosaur, we study the model error induced by neglecting topography in both idealized synthetic fault models and for the cases of the MW=7.3 Landers and MW=8.0 Wenchuan earthquakes. Near the steepest topography, we find the use of flat Earth dislocation models may induce errors of more than 100% in the inferred slip magnitude and rake. In particular, neglecting topographic effects leads to an inferred shallow slip deficit. Thus, we propose that the shallow slip deficit observed in several earthquakes may be an artefact resulting from the systematic use of elastic dislocation models assuming a flat Earth. Finally, using this study as an example, we emphasize the dangerous potential for forward model errors to be amplified by an order of magnitude in inverse problems.

Mars topography harmonics and geophysical implications

NASA Technical Reports Server (NTRS)

Bills, B. G.; Ferrari, A. J.

1978-01-01

The paper describes an improved model of Martian global topography which has been obtained by fitting a sixteenth-degree harmonic series to occultation, radar, spectral, and photogrammetric measurements. Empirical elevation data based on photographic data are used to supplement the observations in areas without data. Values for the mean radius, the mean density, and the displacement of the center of the figure from the center of mass are presented. The reported geometric flattening is too great and the reported dynamic flattening is too small for Mars to be homogeneous and hydrostatic. Maps of the data distribution, global topography, and Bouguer gravity anomaly are interpreted in terms of a crustal thickness map which is consistent with gravity, topography, and recent preliminary Viking seismic results.

Video Animation of Ocean Topography From TOPEX/POSEIDON

NASA Technical Reports Server (NTRS)

Fu, Lee-Lueng; Leconte, Denis; Pihos, Greg; Davidson, Roger; Kruizinga, Gerhard; Tapley, Byron

1993-01-01

Three video loops showing various aspects of the dynamic ocean topography obtained from the TOPEX/POSEIDON radar altimetry data will be presented. The first shows the temporal change of the global ocean topography during the first year of the mission. The time-averaged mean is removed to reveal the temporal variabilities. Temporal interpolation is performed to create daily maps for the animation. A spatial smoothing is also performed to retain only the large-sale features. Gyre-scale seasonal changes are the main features. The second shows the temporal evolution of the Gulf Stream. The high resolution gravimetric geoid of Rapp is used to obtain the absolute ocean topography. Simulated drifters are used to visualize the flow pattern of the current. Meanders and rings of the current are the main features. The third is an animation of the global ocean topography on a spherical earth. The JGM-2 geoid is used to obtain the ocean topography...

Influence of tissue resistivities on neuromagnetic fields and electric potentials studied with a finite element model of the head.

PubMed

Haueisen, J; Ramon, C; Eiselt, M; Brauer, H; Nowak, H

1997-08-01

Modeling in magnetoencephalography (MEG) and electroencephalography (EEG) requires knowledge of the in vivo tissue resistivities of the head. The aim of this paper is to examine the influence of tissue resistivity changes on the neuromagnetic field and the electric scalp potential. A high-resolution finite element method (FEM) model (452,162 elements, 2-mm resolution) of the human head with 13 different tissue types is employed for this purpose. Our main finding was that the magnetic fields are sensitive to changes in the tissue resistivity in the vicinity of the source. In comparison, the electric surface potentials are sensitive to changes in the tissue resistivity in the vicinity of the source and in the vicinity of the position of the electrodes. The magnitude (strength) of magnetic fields and electric surface potentials is strongly influenced by tissue resistivity changes, while the topography is not as strongly influenced. Therefore, an accurate modeling of magnetic field and electric potential strength requires accurate knowledge of tissue resistivities, while for source localization procedures this knowledge might not be a necessity.

Glacial reorganization of topography in a tectonically active mountain range

NASA Astrophysics Data System (ADS)

Adams, Byron; Ehlers, Todd

2016-04-01

Tests of the interactions between tectonic and climate forcing on Earth's topography often focus on the concept of steady-state whereby processes of rock deformation and erosion are opposing and equal. However, when conditions change such as the climate or tectonic rock uplift, then surface processes act to restore the balance between rock deformation and erosion by adjusting topography. Most examples of canonical steady-state mountain ranges lie within the northern hemisphere, which underwent a radical change in the Quaternary due to the onset of widespread glaciation. The activity of glaciers changed erosion rates and topography in many of these mountain ranges, which likely violates steady-state assumptions. With new topographic analysis, and existing patterns of climate and rock uplift, we explore a mountain range previously considered to be in steady-state, the Olympic Mountains, USA. The details of our analysis suggest the dominant topographic signal in the Olympic Mountains is a spatial, and likely temporal, variation in erosional efficiency dictated by orographic precipitation, and Pleistocene glacier ELA patterns, and not tectonic rock uplift rates. Alpine glaciers drastically altered the relief structure of the Olympic Mountains. The details of these relief changes are recorded in channel profiles as overdeepenings, reduced slopes, and associated knickpoints. We find the position of these relief changes within the orogen is dependent on the position of the Pleistocene ELA. While alpine glaciers overdeepened valleys in regions near the Pleistocene ELA (which has a tendency to increase relief), headward erosion of west and north flowing glacier systems captured significant area from opposing systems and caused drainage divide lowering. This divide lowering reduced relief throughout the range. We demonstrate similar topographic effects recorded in the basin hypsometries of other Cenozoic mountain ranges around the world. The significant glacial overprint on

Shortwave radiation parameterization scheme for subgrid topography

NASA Astrophysics Data System (ADS)

Helbig, N.; LöWe, H.

2012-02-01

Topography is well known to alter the shortwave radiation balance at the surface. A detailed radiation balance is therefore required in mountainous terrain. In order to maintain the computational performance of large-scale models while at the same time increasing grid resolutions, subgrid parameterizations are gaining more importance. A complete radiation parameterization scheme for subgrid topography accounting for shading, limited sky view, and terrain reflections is presented. Each radiative flux is parameterized individually as a function of sky view factor, slope and sun elevation angle, and albedo. We validated the parameterization with domain-averaged values computed from a distributed radiation model which includes a detailed shortwave radiation balance. Furthermore, we quantify the individual topographic impacts on the shortwave radiation balance. Rather than using a limited set of real topographies we used a large ensemble of simulated topographies with a wide range of typical terrain characteristics to study all topographic influences on the radiation balance. To this end slopes and partial derivatives of seven real topographies from Switzerland and the United States were analyzed and Gaussian statistics were found to best approximate real topographies. Parameterized direct beam radiation presented previously compared well with modeled values over the entire range of slope angles. The approximation of multiple, anisotropic terrain reflections with single, isotropic terrain reflections was confirmed as long as domain-averaged values are considered. The validation of all parameterized radiative fluxes showed that it is indeed not necessary to compute subgrid fluxes in order to account for all topographic influences in large grid sizes.

The absolute dynamic ocean topography (ADOT)

NASA Astrophysics Data System (ADS)

Bosch, Wolfgang; Savcenko, Roman

The sea surface slopes relative to the geoid (an equipotential surface) basically carry the in-formation on the absolute velocity field of the surface circulation. Pure oceanographic models may remain unspecific with respect to the absolute level of the ocean topography. In contrast, the geodetic approach to estimate the ocean topography as difference between sea level and the geoid gives by definition an absolute dynamic ocean topography (ADOT). This approach requires, however, a consistent treatment of geoid and sea surface heights, the first being usually derived from a band limited spherical harmonic series of the Earth gravity field and the second observed with much higher spectral resolution by satellite altimetry. The present contribution shows a procedure for estimating the ADOT along the altimeter profiles, preserving as much sea surface height details as the consistency w.r.t. the geoid heights will allow. The consistent treatment at data gaps and the coast is particular demanding and solved by a filter correction. The ADOT profiles are inspected for their innocent properties towards the coast and compared to external estimates of the ocean topography or the velocity field of the surface circulation as derived, for example, by ARGO floats.

Topography and refractometry of sperm cells using spatial light interference microscopy

NASA Astrophysics Data System (ADS)

Liu, Lina; Kandel, Mikhail E.; Rubessa, Marcello; Schreiber, Sierra; Wheeler, Mathew B.; Popescu, Gabriel

2018-02-01

Characterization of spermatozoon viability is a common test in treating infertility. Recently, it has been shown that label-free, phase-sensitive imaging can provide a valuable alternative for this type of assay. We employ spatial light interference microscopy (SLIM) to perform high-accuracy single-cell phase imaging and decouple the average thickness and refractive index information for the population. This procedure was enabled by quantitative-phase imaging cells on media of two different refractive indices and using a numerical tool to remove the curvature from the cell tails. This way, we achieved ensemble averaging of topography and refractometry of 100 cells in each of the two groups. The results show that the thickness profile of the cell tail goes down to 150 nm and the refractive index can reach values of 1.6 close to the head.

Estimating 3D topographic map of optic nerve head from a single fundus image

NASA Astrophysics Data System (ADS)

Wang, Peipei; Sun, Jiuai

2018-04-01

Optic nerve head also called optic disc is the distal portion of optic nerve locating and clinically visible on the retinal surface. It is a 3 dimensional elliptical shaped structure with a central depression called the optic cup. This shape of the ONH and the size of the depression can be varied due to different retinopathy or angiopathy, therefore the estimation of topography of optic nerve head is significant for assisting diagnosis of those retinal related complications. This work describes a computer vision based method, i.e. shape from shading (SFS) to recover and visualize 3D topographic map of optic nerve head from a normal fundus image. The work is expected helpful for assessing those complications associated the deformation of optic nerve head such as glaucoma and diabetes. The illumination is modelled as uniform over the area around optic nerve head and its direction estimated from the available image. The Tsai discrete method has been employed to recover the 3D topographic map of the optic nerve head. The initial experimental result demonstrates our approach works on most of fundus images and provides a cheap, but good alternation for rendering and visualizing the topographic information of the optic nerve head for potential clinical use.

Early Head CT Findings Are Associated With Outcomes After Pediatric Out-of-Hospital Cardiac Arrest.

PubMed

Starling, Rebecca M; Shekdar, Karuna; Licht, Dan; Nadkarni, Vinay M; Berg, Robert A; Topjian, Alexis A

2015-07-01

Head CT after out-of-hospital cardiac arrest is often obtained to evaluate intracranial pathology. Among children admitted to the PICU following pediatric out-of-hospital cardiac arrest, we hypothesized that loss of gray-white matter differentiation and basilar cistern and sulcal effacement are associated with mortality and unfavorable neurologic outcome. Retrospective, cohort study. Single, tertiary-care center PICU. Seventy-eight patients less than 18 years old who survived out-of-hospital cardiac arrest to PICU admission and had a head CT within 24 hours of return of spontaneous circulation were evaluated from July 2005 through May 2012. None. Median time to head CT from return of spontaneous circulation was 3.3 hours (1.0, 6.0). Median patient age was 2.3 years (0.4, 9.5). Thirty-nine patients (50%) survived, of whom 29 (74%) had favorable neurologic outcome. Nonsurvivors were more likely than survivors to have 1) loss of gray-white matter differentiation (Hounsfield unit ratios, 0.96 [0.88, 1.07] vs 1.1 [1.07, 1.2]; p < 0.001), 2) basilar cistern effacement (93% vs 7%; p = 0.001; positive predictive value, 94%; negative predictive value, 59%), and 3) sulcal effacement (100% vs 0%; p ≤ 0.001; positive predictive value, 100%; negative predictive value, 68%). All patients with poor gray-white matter differentiation or sulcal effacement had unfavorable neurologic outcomes. Only one patient with basilar cistern effacement had favorable outcome. Loss of gray-white matter differentiation and basilar cistern effacement and sulcal effacement are associated with poor outcome after pediatric out-of-hospital cardiac arrest. Select patients may have favorable outcomes despite these findings.

Sensory properties of menthol and smoking topography

PubMed Central

2011-01-01

Although there is a great deal known about menthol as a flavoring agent in foods and confections, less is known about the particular sensory properties of menthol cigarette smoke. Similarly, although smoking topography (the unique way an individual smokes a cigarette) has been well studied using non-menthol cigarettes, there is relatively less known about how menthol affects smoking behavior. The objective of this review is to assess the sensory properties of menthol tobacco smoke, and smoking topography associated with menthol cigarettes. The cooling, analgesic, taste, and respiratory effects of menthol are well established, and studies have indicated that menthol’s sensory attributes can have an influence on the positive, or rewarding, properties associated smoking, including ratings of satisfaction, taste, perceived smoothness, and perceived irritation. Despite these sensory properties, the data regarding menthol’s effect on smoking topography are inconsistent. Many of the topography studies have limitations due to various methodological issues. PMID:21624149

Learning topography with Tangible Landscape games

NASA Astrophysics Data System (ADS)

Petrasova, A.; Tabrizian, P.; Harmon, B. A.; Petras, V.; Millar, G.; Mitasova, H.; Meentemeyer, R. K.

2017-12-01

Understanding topography and its representations is crucial for correct interpretation and modeling of surface processes. However, novice earth science and landscape architecture students often find reading topographic maps challenging. As a result, many students struggle to comprehend more complex spatial concepts and processes such as flow accumulation or sediment transport.We developed and tested a new method for teaching hydrology, geomorphology, and grading using Tangible Landscape—a tangible interface for geospatial modeling. Tangible Landscape couples a physical and digital model of a landscape through a real-time cycle of hands-on modeling, 3D scanning, geospatial computation, and projection. With Tangible Landscape students can sculpt a projection-augmented topographic model of a landscape with their hands and use a variety of tangible objects to immediately see how they are changing geospatial analytics such as contours, profiles, water flow, or landform types. By feeling and manipulating the shape of the topography, while seeing projected geospatial analytics, students can intuitively learn about 3D topographic form, its representations, and how topography controls physical processes. Tangible Landscape is powered by GRASS GIS, an open source geospatial platform with extensive libraries for geospatial modeling and analysis. As such, Tangible Landscape can be used to design a wide range of learning experiences across a large number of geoscience disciplines.As part of a graduate level course that teaches grading, 16 students participated in a series of workshops, which were developed as serious games to encourage learning through structured play. These serious games included 1) diverting rain water to a specified location with minimal changes to landscape, 2) building different combinations of landforms, and 3) reconstructing landscapes based on projected contour information with feedback.In this poster, we will introduce Tangible Landscape, and

The Head Bone's Connected to the Neck Bone: When do Toddlers Represent Their Own Body Topography?

PubMed Central

Brownell, Celia A.; Nichols, Sara R.; Svetlova, Margarita; Zerwas, Stephanie; Ramani, Geetha

2010-01-01

Developments in very young children's topographic representations of their own bodies were examined. Sixty one 20- and 30-month old children were administered tasks that indexed the ability to locate specific body parts on oneself and knowledge of how one's body parts are spatially organized, as well as body-size knowledge and self-awareness. Age differences in performance emerged for every task. Body-part localization and body spatial configuration knowledge were associated; however, body topography knowledge was not associated with body-size knowledge. Both were related to traditional measures of self-awareness, mediated by their common associations with age. It is concluded that children possess an explicit, if rudimentary, topographic representation of their own body's shape, structure, and size by 30 months of age. PMID:20573105

How Escherichia coli lands and forms cell clusters on a surface: a new role of surface topography

PubMed Central

Gu, Huan; Chen, Aaron; Song, Xinran; Brasch, Megan E.; Henderson, James H.; Ren, Dacheng

2016-01-01

Bacterial response to surface topography during biofilm formation was studied using 5 μm tall line patterns of poly (dimethylsiloxane) (PDMS). Escherichia coli cells attached on top of protruding line patterns were found to align more perpendicularly to the orientation of line patterns when the pattern narrowed. Consistently, cell cluster formation per unit area on 5 μm wide line patterns was reduced by 14-fold compared to flat PDMS. Contrasting the reduced colony formation, cells attached on narrow patterns were longer and had higher transcriptional activities, suggesting that such unfavorable topography may present a stress to attached cells. Results of mutant studies indicate that flagellar motility is involved in the observed preference in cell orientation on narrow patterns, which was corroborated by the changes in cell rotation pattern before settling on different surface topographies. These findings led to a set of new design principles for creating antifouling topographies, which was validated using 10 μm tall hexagonal patterns. PMID:27412365

An approximate fluvial equilibrium topography for the Alps

NASA Astrophysics Data System (ADS)

Stüwe, K.; Hergarten, S.

2012-04-01

This contribution addresses the question whether the present topography of the Alps can be approximated by a fluvial equilibrium topography and whether this can be used to determine uplift rates. Based on a statistical analysis of the present topography we use a stream-power approach for erosion where the erosion rate is proportional to the square root of the catchment size for catchment sizes larger than 12 square kilometers and a logarithmic dependence to mimic slope processes at smaller catchment sizes. If we assume a homogeneous uplift rate over the entire region (block uplift), the best-fit fluvial equilibrium topography differs from the real topography by about 500 m RMS (root mean square) with a strong systematic deviation. Regions of low elevation are too high in the equilibrium topography, while high-mountain regions are too low. The RMS difference significantly decreases if a spatially variable uplift function is allowed. If a strong variation of the uplift rate on a scale of 5 km is allowed, the systematic deviation becomes rather small, and the RMS difference decreases to about 150 m. A significant part of the remaining deviation apparently arises from glacially-shaped valleys, while another part may result from prematurity of the relief (Hergarten, Wagner & Stüwe, EPSL 297:453, 2010). The best-fit uplift function can probably be used for forward or backward simulation of the landform evolution.

Effects of patterned topography on biofilm formation

NASA Astrophysics Data System (ADS)

Vasudevan, Ravikumar

2011-12-01

Bacterial biofilms are a population of bacteria attached to each other and irreversibly to a surface, enclosed in a matrix of self-secreted polymers, among others polysaccharides, proteins, DNA. Biofilms cause persisting infections associated with implanted medical devices and hospital acquired (nosocomial) infections. Catheter-associated urinary tract infections (CAUTIs) are the most common type of nosocomial infections accounting for up to 40% of all hospital acquired infections. Several different strategies, including use of antibacterial agents and genetic cues, quorum sensing, have been adopted for inhibiting biofilm formation relevant to CAUTI surfaces. Each of these methods pertains to certain types of bacteria, processes and has shortcomings. Based on eukaryotic cell topography interaction studies and Ulva linza spore studies, topographical surfaces were suggested as a benign control method for biofilm formation. However, topographies tested so far have not included a systematic variation of size across basic topography shapes. In this study patterned topography was systematically varied in size and shape according to two approaches 1) confinement and 2) wetting. For the confinement approach, using scanning electron microscopy and confocal microscopy, orienting effects of tested topography based on staphylococcus aureus (s. aureus) (SH1000) and enterobacter cloacae (e. cloacae) (ATCC 700258) bacterial models were identified on features of up to 10 times the size of the bacterium. Psuedomonas aeruginosa (p. aeruginosa) (PAO1) did not show any orientational effects, under the test conditions. Another important factor in medical biofilms is the identification and quantification of phenotypic state which has not been discussed in the literature concerning bacteria topography characterizations. This was done based on antibiotic susceptibility evaluation and also based on gene expression analysis. Although orientational effects occur, phenotypically no difference

Femoral head avascular necrosis: a frequently missed incidental finding on multidetector CT.

PubMed

Barille, M F; Wu, Jim S; McMahon, Colm J

2014-03-01

To determine the incidence of missed femoral head avascular necrosis (AVN) on pelvic computed tomography (CT) performed for clinical indications other than assessment for AVN. The study was a Health Insurance Portability and Accountability Act (HIPAA)-compliant retrospective study. The picture archiving and communication system (PACS) database was queried for patients with diagnosis of femoral head AVN on magnetic resonance imaging (MRI), who also underwent pelvic multidetector CT after or <30 days before the MRI examination. The MRI and CT images of 144 hips of 72 patients (39 patients with reported AVN on MRI and 33 age-matched controls; mean age = 60 years, 28 male, 44 female), were reviewed in consensus by two readers in a randomized, blinded manner. Using MRI-proven CT-visible AVN as a reference standard, the incidence of missed AVN on initial CT interpretation was determined. Readers confirmed AVN in 33 patients on the MRI images. Nine hips with AVN underwent joint replacement of the affected joint(s) prior to subsequent CT and were excluded. Forty-three MRI-proven AVN cases in 28 patients (15 bilateral, 13 unilateral) were available for analysis. The study readers diagnosed 35/43 (81%) MRI-proven AVN cases in 22/28 (79%) patients. Four of the 35 (11%) cases of MRI-proven, CT-visible AVN were prospectively reported in 3/22 (14%) patients at initial clinical interpretation, with a miss rate of 89% per hip and 86% per patient. Multidetector CT has high accuracy for detection of AVN; however, this is frequently missed as an incidental finding (89% missed in the present study). Assessment for signs of femoral AVN should be part of routine search pattern in interpretation of pelvic CT. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Design and implementation of optical system for Placido-disc topography

NASA Astrophysics Data System (ADS)

Sui, Chenghua; Wo, Shengjie; Cai, Pinggen; Gao, Nan; Xu, Danyang; Han, Yonghao; Du, Chunnian

2017-11-01

Corneal topography provides powerful support in the diagnosis and treatment of corneal disease by displaying the corneal surface topography in data or image format. To realize the precise detection of corneal surface topography, an optical system for the corneal topography that is based on a Placido disc is designed, which includes a ring distribution on a Placido disc, an imaging system and a collimating illumination system. First, a mathematical model that is based on the corneal topography working principles is established with MATLAB to determine the distribution of white-and-black rings on the Placido disc, in which the ellipsoid facial rings-target of the Placido disc is utilized. Second, the imaging lens structure is designed and optimized by Zemax software. Last, the collimating illumination lens structure is designed by paraxial ray trace equations. The quality of the corneal topography, which is based on our designed optical system, is evaluated. The high-contrast image of uniformly distributed white-and-black rings is observed through the CCD camera. Our optical system for the corneal topography has high precision, with a measuring region of the cornea with a diameter of approximately 10 mm. Therefore, the creation of this optical system offers guidance for designing and improving the optical system of Placido-disc topography.

Experiments on topographies lacking tidal conversion

NASA Astrophysics Data System (ADS)

Maas, Leo; Paci, Alexandre; Yuan, Bing

2015-11-01

In a stratified sea, internal tides are supposedly generated when the tide passes over irregular topography. It has been shown that for any given frequency in the internal wave band there are an infinite number of exceptions to this rule of thumb. This ``stealth-like'' property of the topography is due to a subtle annihilation of the internal waves generated during the surface tide's passage over the irregular bottom. We here demonstrate this in a lab-experiment. However, for any such topography, subsequently changing the surface tide's frequency does lead to tidal conversion. The upshot of this is that a tidal wave passing over an irregular bottom is for a substantial part trapped to this irregularity, and only partly converted into freely propagating internal tides. Financially supported by the European Community's 7th Framework Programme HYDRALAB IV.

Vomiting--is this a good indication for CT head scans in patients with minor head injury?

PubMed

Bainbridge, J; Khirwadkar, H; Hourihan, M D

2012-02-01

The National Institute for Health and Clinical Excellence head injury guidelines advise CT imaging within 1 h if there is more than one episode of vomiting post-head injury in adults and three or more episodes in children. Since the guideline publication, studies have found that, following head injury, vomiting alone is associated with an abnormal CT head scan in 13-45% of cases. CT head scan requests referred from the emergency department between 1 May 2009 and 30 April 2010 were retrospectively reviewed. Patients with vomiting as the sole indication for an "immediate" CT head scan performed within 1 h were included in the study. Reports produced by experienced neuroradiologists were reviewed and the detection of significant head injury was noted. There were 1264 CT head scans performed during our study period. 151 (124 adults, 27 children) were indicated owing to vomiting following head injury. 5 of the 124 adult scans and 1 of the 27 paediatric scans showed an abnormal finding, giving positive predictive values (PPV) of 4% and 3.7%, respectively. None of these patients required either acute or delayed neurosurgical intervention. In our experience, vomiting alone has a PPV of 4% for significant head injury in adults. However, none of these injuries were serious enough to warrant acute or delayed intervention. Given these findings, vomiting following head injury is a reasonable indication for a CT head scan; however, as none of the patients required acute intervention, we suggest that these scans do not usually need to be performed within 1 h of request.

Head Start Impact Study. Technical Report

ERIC Educational Resources Information Center

Puma, Michael; Bell, Stephen; Cook, Ronna; Heid, Camilla; Shapiro, Gary; Broene, Pam; Jenkins, Frank; Fletcher, Philip; Quinn, Liz; Friedman, Janet; Ciarico, Janet; Rohacek, Monica; Adams, Gina; Spier, Elizabeth

2010-01-01

This Technical Report is designed to provide technical detail to support the analysis and findings presented in the "Head Start Impact Study Final Report" (U.S. Department of Health and Human Services, January 2010). Chapter 1 provides an overview of the Head Start Impact Study and its findings. Chapter 2 provides technical information on the…

Craters on Mars: Global Geometric Properties from Gridded MOLA Topography

NASA Technical Reports Server (NTRS)

Garvin, J. B.; Sakimoto, S. E. H.; Frawley, J. J.

2003-01-01

Impact craters serve as natural probes of the target properties of planetary crusts and the tremendous diversity of morphological expressions of such features on Mars attests to their importance for deciphering the history of crustal assembly, modification, and erosion. This paper summarizes the key findings associated with a five year long survey of the three-dimensional properties of approx. 6000 martian impact craters using finely gridded MOLA topography. Previous efforts have treated representative subpopulations, but this effort treats global properties from the largest survey of impact features from the perspective of their topography ever assimilated. With the Viking missions of the mid-1970 s, the most intensive and comprehensive robotic expeditions to any Deep Space location in the history of humanity were achieved, with scientifically stunning results associated with the morphology of impact craters. The relationships illustrated and suggest that martian impact features are remarkably sensitive to target properties and to the local depositional processes.

Effects of topography on the spin-up of a Venus atmospheric model

NASA Astrophysics Data System (ADS)

Herrnstein, A.; Dowling, T. E.

2007-04-01

We study how topography affects the spin-up from rest of a model of the atmosphere of Venus. The simulations are performed with the EPIC model using its isentropic, terrain-following hybrid vertical coordinate, and are forced with the Newtonian-cooling profile used to achieve superrotation in a Venus model with no topography by Lee et al. (2005). We are able to reproduce their results with our model, which was developed independently and uses a different vertical coordinate. Both groups use a horizontal resolution of 5°, which is dictated by the need for reasonable computer runtime and is not a claim of numerical convergence. We find that the addition of topography substantially changes both the evolution and end state of the model's spin-up: the magnitude of the superrotation is diminished from 55 ms-1 to 35 ms-1, and it reaches steady state faster, in a few years instead of a few decades. A large, stationary eddy associated with Ishtar Terra forms that has a local horizontal temperature anomaly of order 2 K at the 0.7 bar level; such a feature may be observable in high-resolution infrared images.

The Dawn Topography Investigation

NASA Technical Reports Server (NTRS)

Raymond, C. A.; Jaumann, R.; Nathues, A.; Sierks, H.; Roatsch, T.; Preusker, E; Scholten, F.; Gaskell, R. W.; Jorda, L.; Keller, H.-U.;

Crater topography on Titan: Implications for landscape evolution

NASA Astrophysics Data System (ADS)

Neish, C.; Kirk, R.; Lorenz, R.; Bray, V.; Schenk, P.; Stiles, B.; Turtle, E.; Cassini Radar Team

2012-04-01

Unique among the icy satellites, Titan’s surface shows evidence for extensive modification by fluvial and aeolian erosion, which act to change the topography of its surface over time. Quantifying the extent of this landscape evolution is difficult, since the original, ‘non-eroded’ surface topography is generally unknown. However, fresh craters on icy satellites have a well-known shape and morphology, which has been determined from extensive studies on the airless worlds of the outer solar system (Schenk et al., 2004). By comparing the topography of craters on Titan to similarly sized, pristine analogues on airless bodies, we can obtain one of the few direct measures of the amount of erosion that has occurred on Titan. Cassini RADAR has imaged >30% of the surface of Titan, and more than 60 potential craters have been identified in this data set (Wood et al., 2010; Neish and Lorenz, 2012). Topographic information for these craters can be obtained from a technique known as ‘SARTopo’, which estimates surface heights by comparing the calibration of overlapping synthetic aperture radar (SAR) beams (Stiles et al., 2009). We present topography data for several craters on Titan, and compare the data to similarly sized craters on Ganymede, for which topography has been extracted from stereo-derived digital elevation models (Bray et al., 2012). We find that the depths of craters on Titan are generally within the range of depths observed on Ganymede, but several hundreds of meters shallower than the average (Fig. 1). A statistical comparison between the two data sets suggests that it is extremely unlikely that Titan’s craters were selected from the depth distribution of fresh craters on Ganymede, and that is it much more probable that the relative depths of Titan are uniformly distributed between ‘fresh’ and ‘completely infilled’. This is consistent with an infilling process that varies linearly with time, such as aeolian infilling. Figure 1: Depth of

Early Head CT Findings Are Associated With Outcomes After Pediatric Out-of-Hospital Cardiac Arrest

PubMed Central

Starling, Rebecca M.; Shekdar, Karuna; Licht, Dan; Nadkarni, Vinay M.; Berg, Robert A.; Topjian, Alexis A.

2015-01-01

Objectives Head CT after out-of-hospital cardiac arrest is often obtained to evaluate intracranial pathology. Among children admitted to the PICU following pediatric out-of-hospital cardiac arrest, we hypothesized that loss of gray-white matter differentiation and basilar cistern and sulcal effacement are associated with mortality and unfavorable neurologic outcome. Design Retrospective, cohort study. Setting Single, tertiary-care center PICU. Patients Seventy-eight patients less than 18 years old who survived out-of-hospital cardiac arrest to PICU admission and had a head CT within 24 hours of return of spontaneous circulation were evaluated from July 2005 through May 2012. Interventions None. Measurements and Main Results Median time to head CT from return of spontaneous circulation was 3.3 hours (1.0, 6.0). Median patient age was 2.3 years (0.4, 9.5). Thirty-nine patients (50%) survived, of whom 29 (74%) had favorable neurologic outcome. Nonsurvivors were more likely than survivors to have 1) loss of gray-white matter differentiation (Hounsfield unit ratios, 0.96 [0.88, 1.07] vs 1.1 [1.07, 1.2]; p < 0.001), 2) basilar cistern effacement (93% vs 7%; p = 0.001; positive predictive value, 94%; negative predictive value, 59%), and 3) sulcal effacement (100% vs 0%; p ≤ 0.001; positive predictive value, 100%; negative predictive value, 68%). All patients with poor gray-white matter differentiation or sulcal effacement had unfavorable neurologic outcomes. Only one patient with basilar cistern effacement had favorable outcome. Conclusions Loss of gray-white matter differentiation and basilar cistern effacement and sulcal effacement are associated with poor outcome after pediatric out-of-hospital cardiac arrest. Select patients may have favorable outcomes despite these findings. PMID:25844694

Topography and refractometry of sperm cells using spatial light interference microscopy.

PubMed

Liu, Lina; Kandel, Mikhail E; Rubessa, Marcello; Schreiber, Sierra; Wheeler, Mathew B; Popescu, Gabriel

2018-02-01

Characterization of spermatozoon viability is a common test in treating infertility. Recently, it has been shown that label-free, phase-sensitive imaging can provide a valuable alternative for this type of assay. We employ spatial light interference microscopy (SLIM) to perform high-accuracy single-cell phase imaging and decouple the average thickness and refractive index information for the population. This procedure was enabled by quantitative-phase imaging cells on media of two different refractive indices and using a numerical tool to remove the curvature from the cell tails. This way, we achieved ensemble averaging of topography and refractometry of 100 cells in each of the two groups. The results show that the thickness profile of the cell tail goes down to 150 nm and the refractive index can reach values of 1.6 close to the head. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Sea bottom topography imaging with SAR

NASA Technical Reports Server (NTRS)

Vanderkooij, M. W. A.; Wensink, G. J.; Vogelzang, J.

1992-01-01

It is well known that under favorable meteorological and hydrodynamical conditions the bottom topography of shallow seas can be mapped with airborne or spaceborne imaging radar. This phenomenon was observed for the first time in 1969 by de Loor and co-workers in Q-band Side Looking Airborne Radar (SLAR) imagery of sandwaves in the North Sea. It is now generally accepted that the imaging mechanism consists of three steps: (1) interaction between (tidal) current and bottom topography causes spatial modulations in the surface current velocity; (2) modulations in the surface current velocity give rise to variations in the spectrum of wind-generated waves, as described by the action balance equation; and (3) variations in the wave spectrum show up as intensity modulations in radar imagery. In order to predict radar backscatter modulations caused by sandwaves, an imaging model, covering the three steps, was developed by the Dutch Sea Bottom Topography Group. This model and some model results will be shown. On 16 Aug. 1989 an experiment was performed with the polarimetric P-, L-, and C-band synthetic aperture radar (SAR) of NASA/JPL. One scene was recorded in SAR mode. On 12 Jul. 1991 another three scenes were recorded, of which one was in the ATI-mode (Along-Track Interferometer). These experiments took place in the test area of the Sea Bottom Topography Group, 30 km off the Dutch coast, where the bottom topography is dominated by sand waves. In-situ data were gathered by a ship in the test area and on 'Measuring Platform Noordwijk', 20 km from the center of the test area. The radar images made during the experiment were compared with digitized maps of the bottom. Furthermore, the profiles of radar backscatter modulation were compared with the results of the model. During the workshop some preliminary results of the ATI measurements will be shown.

The Two Faces of Secondary Headship: Women Deputy Head Teachers' Perceptions of the Secondary Head Teacher Role

ERIC Educational Resources Information Center

Guihen, Laura

2017-01-01

Men continue to outnumber women at the secondary head teacher level. This article reports on some of the preliminary findings of a larger study exploring the ways in which women deputy head teachers, as potential aspirants to headship, perceive the secondary head teacher role. Using an Interpretative Phenomenological Analysis methodology,…

Effects of upper mantle heterogeneities on the lithospheric stress field and dynamic topography

NASA Astrophysics Data System (ADS)

Osei Tutu, Anthony; Steinberger, Bernhard; Sobolev, Stephan V.; Rogozhina, Irina; Popov, Anton A.

2018-05-01

The orientation and tectonic regime of the observed crustal/lithospheric stress field contribute to our knowledge of different deformation processes occurring within the Earth's crust and lithosphere. In this study, we analyze the influence of the thermal and density structure of the upper mantle on the lithospheric stress field and topography. We use a 3-D lithosphere-asthenosphere numerical model with power-law rheology, coupled to a spectral mantle flow code at 300 km depth. Our results are validated against the World Stress Map 2016 (WSM2016) and the observation-based residual topography. We derive the upper mantle thermal structure from either a heat flow model combined with a seafloor age model (TM1) or a global S-wave velocity model (TM2). We show that lateral density heterogeneities in the upper 300 km have a limited influence on the modeled horizontal stress field as opposed to the resulting dynamic topography that appears more sensitive to such heterogeneities. The modeled stress field directions, using only the mantle heterogeneities below 300 km, are not perturbed much when the effects of lithosphere and crust above 300 km are added. In contrast, modeled stress magnitudes and dynamic topography are to a greater extent controlled by the upper mantle density structure. After correction for the chemical depletion of continents, the TM2 model leads to a much better fit with the observed residual topography giving a good correlation of 0.51 in continents, but this correction leads to no significant improvement of the fit between the WSM2016 and the resulting lithosphere stresses. In continental regions with abundant heat flow data, TM1 results in relatively small angular misfits. For example, in western Europe the misfit between the modeled and observation-based stress is 18.3°. Our findings emphasize that the relative contributions coming from shallow and deep mantle dynamic forces are quite different for the lithospheric stress field and dynamic

Effects of Topography-driven Micro-climatology on Evaporation

NASA Astrophysics Data System (ADS)

Adams, D. D.; Boll, J.; Wagenbrenner, N. S.

2017-12-01

The effects of spatial-temporal variation of climatic conditions on evaporation in micro-climates are not well defined. Current spatially-based remote sensing and modeling for evaporation is limited for high resolutions and complex topographies. We investigated the effect of topography-driven micro-climatology on evaporation supported by field measurements and modeling. Fourteen anemometers and thermometers were installed in intersecting transects over the complex topography of the Cook Agronomy Farm, Pullman, WA. WindNinja was used to create 2-D vector maps based on recorded observations for wind. Spatial analysis of vector maps using ArcGIS was performed for analysis of wind patterns and variation. Based on field measurements, wind speed and direction show consequential variability based on hill-slope location in this complex topography. Wind speed and wind direction varied up to threefold and more than 45 degrees, respectively for a given time interval. The use of existing wind models enables prediction of wind variability over the landscape and subsequently topography-driven evaporation patterns relative to wind. The magnitude of the spatial-temporal variability of wind therefore resulted in variable evaporation rates over the landscape. These variations may contribute to uneven crop development patterns observed during the late growth stages of the agricultural crops at the study location. Use of hill-slope location indexes and appropriate methods for estimating actual evaporation support development of methodologies to better define topography-driven heterogeneity in evaporation. The cumulative effects of spatially-variable climatic factors on evaporation are important to quantify the localized water balance and inform precision farming practices.

Expressions for tidal conversion at seafloor topography using physical space integrals

NASA Astrophysics Data System (ADS)

Schorghofer, Norbert

2010-12-01

The barotropic tide interacts with seafloor topography to generate internal gravity waves. Equations for streamfunction and power conversion are derived in terms of integrals over the topography in spatial coordinates. The slope of the topography does not need to be small. Explicit equations are derived up to second order in slope for general topography, and conversion by a bell-shaped topography is calculated analytically to this order. A concise formalism using Hilbert transforms is developed, the minimally converting topographic shape is discussed, and a numerical scheme for the evaluation of power conversion is designed that robustly deals with the singular integrand.

Experimental investigation of internal tides generated by finite-height topography

NASA Astrophysics Data System (ADS)

Wang, Shuya; Chen, Xu; Wang, Jinhu; Meng, Jing

2018-06-01

Internal tides generated by finite-height topography are investigated in the laboratory, and the particle image velocimetry (PIV) technique is applied to measure the velocity fields. The energy, energy flux, and vertical mode structure of the internal tides are calculated and analyzed. The experimental results indicate that the strength of the wave field is mainly affected by the normalized topography height. The rays radiated from the taller topography are wider than those radiated from the lower topography. Both the experimental and theoretical results indicate that the normalized energy and energy flux of the internal tides are mainly determined by the normalized topography height, and the increase of the two quantities follows a quadratic function, and they almost remain unchanged with different normalized frequencies except for higher frequency. The percentage of energy for mode-1 and mode-2 internal tides is determined not only by frequency but also by topography height. In addition, an "inherent normalized frequency" is observed in the experiment, at which the percentage of energy for mode 1 and mode 2 does not vary with topography height. The decay rate of internal tide energy in the near field and far field is also estimated, with average values of 36.5 and 7.5%, respectively.

Ocean Surface Topography Mission/Jason 2 Artist Concept

NASA Image and Video Library

2008-09-23

An artist concept of the Ocean Surface Topography Mission/Jason 2 Earth satellite. The Ocean Surface Topography Mission/Jason 2 is an Earth satellite designed to make observations of ocean topography for investigations into sea-level rise and the relationship between ocean circulation and climate change. The satellite also provides data on the forces behind such large-scale climate phenomena as El Niño and La Niña. The mission is a follow-on to the French-American Jason 1 mission, which began collecting data on sea-surface levels in 1992. http://photojournal.jpl.nasa.gov/catalog/PIA18158

Smoking topography and abstinence in adult female smokers

PubMed Central

McClure, Erin A.; Saladin, Michael E.; Baker, Nathaniel L.; Carpenter, Matthew J.; Gray, Kevin M.

2013-01-01

Preliminary evidence, within both adults and adolescents, suggests that the intensity with which cigarettes are smoked (i.e. smoking topography) is predictive of success during a cessation attempt. These reports have also shown topography to be superior compared to other variables, such as cigarettes per day, in the prediction of abstinence. The possibility that gender may influence this predictive relationship has not been evaluated, but may be clinically useful in tailoring gender-specific interventions. Within the context of a clinical trial for smoking cessation among women, adult daily smokers completed a laboratory session that included a 1-hour ad-libitum smoking period in which measures of topography were collected (N=135). Participants were then randomized to active medication (nicotine patch vs. varenicline) and abstinence was monitored for 4 weeks. Among all smoking topography measures and all abstinence outcomes, a moderate association was found between longer puff duration and greater puff volume and continued smoking during the active 4-week treatment phase, but only within the nicotine patch group. Based on the weak topography-abstinence relationship among female smokers found in the current study, future studies should focus on explicit gender comparisons to examine if these associations are specific to or more robust in male smokers. PMID:24018226

Smoking topography and abstinence in adult female smokers.

PubMed

McClure, Erin A; Saladin, Michael E; Baker, Nathaniel L; Carpenter, Matthew J; Gray, Kevin M

2013-12-01

Preliminary evidence, within both adults and adolescents, suggests that the intensity with which cigarettes are smoked (i.e., smoking topography) is predictive of success during a cessation attempt. These reports have also shown topography to be superior compared to other variables, such as cigarettes per day, in the prediction of abstinence. The possibility that gender may influence this predictive relationship has not been evaluated but may be clinically useful in tailoring gender-specific interventions. Within the context of a clinical trial for smoking cessation among women, adult daily smokers completed a laboratory session that included a 1-hour ad libitum smoking period in which measures of topography were collected (N=135). Participants were then randomized to active medication (nicotine patch vs. varenicline) and abstinence was monitored for 4weeks. Among all smoking topography measures and all abstinence outcomes, a moderate association was found between longer puff duration and greater puff volume and continued smoking during the active 4-week treatment phase, but only within the nicotine patch group. Based on the weak topography-abstinence relationship among female smokers found in the current study, future studies should focus on explicit gender comparisons to examine if these associations are specific to or more robust in male smokers. © 2013 Elsevier Ltd. All rights reserved.

Payload topography camera of Chang'e-3

NASA Astrophysics Data System (ADS)

Yu, Guo-Bin; Liu, En-Hai; Zhao, Ru-Jin; Zhong, Jie; Zhou, Xiang-Dong; Zhou, Wu-Lin; Wang, Jin; Chen, Yuan-Pei; Hao, Yong-Jie

2015-11-01

Chang'e-3 was China's first soft-landing lunar probe that achieved a successful roving exploration on the Moon. A topography camera functioning as the lander's “eye” was one of the main scientific payloads installed on the lander. It was composed of a camera probe, an electronic component that performed image compression, and a cable assembly. Its exploration mission was to obtain optical images of the lunar topography in the landing zone for investigation and research. It also observed rover movement on the lunar surface and finished taking pictures of the lander and rover. After starting up successfully, the topography camera obtained static images and video of rover movement from different directions, 360° panoramic pictures of the lunar surface around the lander from multiple angles, and numerous pictures of the Earth. All images of the rover, lunar surface, and the Earth were clear, and those of the Chinese national flag were recorded in true color. This paper describes the exploration mission, system design, working principle, quality assessment of image compression, and color correction of the topography camera. Finally, test results from the lunar surface are provided to serve as a reference for scientific data processing and application.

Detecting and Quantifying Topography in Neural Maps

PubMed Central

Yarrow, Stuart; Razak, Khaleel A.; Seitz, Aaron R.; Seriès, Peggy

2014-01-01

Topographic maps are an often-encountered feature in the brains of many species, yet there are no standard, objective procedures for quantifying topography. Topographic maps are typically identified and described subjectively, but in cases where the scale of the map is close to the resolution limit of the measurement technique, identifying the presence of a topographic map can be a challenging subjective task. In such cases, an objective topography detection test would be advantageous. To address these issues, we assessed seven measures (Pearson distance correlation, Spearman distance correlation, Zrehen's measure, topographic product, topological correlation, path length and wiring length) by quantifying topography in three classes of cortical map model: linear, orientation-like, and clusters. We found that all but one of these measures were effective at detecting statistically significant topography even in weakly-ordered maps, based on simulated noisy measurements of neuronal selectivity and sparse sampling of the maps. We demonstrate the practical applicability of these measures by using them to examine the arrangement of spatial cue selectivity in pallid bat A1. This analysis shows that significantly topographic arrangements of interaural intensity difference and azimuth selectivity exist at the scale of individual binaural clusters. PMID:24505279

Topography of Vesta Surface

NASA Image and Video Library

2011-08-26

This view of the topography of asteroid Vesta surface is composed of several images obtained with the framing camera on NASA Dawn spacecraft on August 6, 2011. The image mosaic is shown superimposed on a digital terrain model.

Recent advances in engineering topography mediated antibacterial surfaces

PubMed Central

Hasan, Jafar

2015-01-01

The tendency of bacterial cells to adhere and colonize a material surface leading to biofilm formation is a fundamental challenge underlying many different applications including microbial infections associated with biomedical devices and products. Although, bacterial attachment to surfaces has been extensively studied in the past, the effect of surface topography on bacteria–material interactions has received little attention until more recently. We review the recent progress in surface topography based approaches for engineering antibacterial surfaces. Biomimicry of antibacterial surfaces in nature is a popular strategy. Whereas earlier endeavors in the field aimed at minimizing cell attachment, more recent efforts have focused on developing bactericidal surfaces. However, not all such topography mediated bactericidal surfaces are necessarily cytocompatible thus underscoring the need for continued efforts for research in this area for developing antibacterial and yet cytocompatible surfaces for use in implantable biomedical applications. This mini-review provides a brief overview of the current strategies and challenges in the emerging field of topography mediated antibacterial surfaces. PMID:26372264

Recent advances in engineering topography mediated antibacterial surfaces

NASA Astrophysics Data System (ADS)

Hasan, Jafar; Chatterjee, Kaushik

2015-09-01

The tendency of bacterial cells to adhere and colonize a material surface leading to biofilm formation is a fundamental challenge underlying many different applications including microbial infections associated with biomedical devices and products. Although, bacterial attachment to surfaces has been extensively studied in the past, the effect of surface topography on bacteria-material interactions has received little attention until more recently. We review the recent progress in surface topography based approaches for engineering antibacterial surfaces. Biomimicry of antibacterial surfaces in nature is a popular strategy. Whereas earlier endeavors in the field aimed at minimizing cell attachment, more recent efforts have focused on developing bactericidal surfaces. However, not all such topography mediated bactericidal surfaces are necessarily cytocompatible thus underscoring the need for continued efforts for research in this area for developing antibacterial and yet cytocompatible surfaces for use in implantable biomedical applications. This mini-review provides a brief overview of the current strategies and challenges in the emerging field of topography mediated antibacterial surfaces.

Three-dimensional digital mapping of the optic nerve head cupping in glaucoma

NASA Astrophysics Data System (ADS)

Mitra, Sunanda; Ramirez, Manuel; Morales, Jose

1992-08-01

Visualization of the optic nerve head cupping is clinically achieved by stereoscopic viewing of a fundus image pair of the suspected eye. A novel algorithm for three-dimensional digital surface representation of the optic nerve head, using fusion of stereo depth map with a linearly stretched intensity image of a stereo fundus image pair, is presented. Prior to depth map acquisition, a number of preprocessing tasks including feature extraction, registration by cepstral analysis, and correction for intensity variations are performed. The depth map is obtained by using a coarse to fine strategy for obtaining disparities between corresponding areas. The required matching techniques to obtain the translational differences in every step, uses cepstral analysis and correlation-like scanning technique in the spatial domain for the finest details. The quantitative and precise representation of the optic nerve head surface topography following this algorithm is not computationally intensive and should provide more useful information than just qualitative stereoscopic viewing of the fundus as one of the diagnostic criteria for diagnosis of glaucoma.

ATM Coastal Topography-Alabama 2001

USGS Publications Warehouse

Nayegandhi, Amar; Yates, Xan; Brock, John C.; Sallenger, A.H.; Bonisteel, Jamie M.; Klipp, Emily S.; Wright, C. Wayne

2009-01-01

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Alabama coastline, acquired October 3-4, 2001. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative scanning Lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning Lidar system that measures high-resolution topography of the land surface, and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for pre-survey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create maps that

ATM Coastal Topography-Mississippi, 2001

USGS Publications Warehouse

Nayegandhi, Amar; Yates, Xan; Brock, John C.; Sallenger, A.H.; Klipp, Emily S.; Wright, C. Wayne

2009-01-01

These remotely sensed, geographically referenced elevation measurements of lidar-derived first-surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Mississippi coastline, from Lakeshore to Petit Bois Island, acquired September 9-10, 2001. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative scanning lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of lidar data in an interactive or batch mode. Modules for presurvey flight-line definition, flight-path plotting, lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS

Topography- and management-mediated resource gradients maintain rare and common plant diversity around paddy terraces.

PubMed

Uematsu, Yuta; Ushimaru, Atushi

2013-09-01

Examining the causes of interspecific differences in susceptibility to bidirectional land-use changes (land abandonment and use-intensification) is important for understanding the mechanisms of global biodiversity loss in agricultural landscapes. We tested the hypothesis that rare (endangered) plant species prefer wet and oligotrophic areas within topography- and management-mediated resource (soil water content, nutrient, and aboveground biomass) gradients, making them more susceptible to both abandonment and use-intensification of agricultural lands. We demonstrated that topography and management practices generated resource gradients in seminatural grasslands around traditional paddy terraces. Terraced topography and management practices produced a soil moisture gradient within levees and a nutrient gradient within paddy terraces. Both total and rare species diversity increased with soil water content. Total species diversity increased in more eutrophied areas with low aboveground biomass, whereas rare species diversity was high under oligotrophic conditions. Rare and common species were differentially distributed along the human-induced nutrient gradient, with rare species preferring wet, nutrient-poor environments in the agricultural landscapes studied. We suggest that conservation efforts should concentrate on wet, nutrient-poor areas within such landscapes, which can be located easily using land-use and topography maps. This strategy would reduce the costs of finding and conserving rare grassland species in a given agricultural landscape.

Spectral analysis of the gravity and topography of Mars

NASA Technical Reports Server (NTRS)

Bills, Bruce G.; Frey, Herbert V.; Kiefer, Walter S.; Nerem, R. Steven; Zuber, Maria T.

1993-01-01

New spherical harmonic models of the gravity and topography of Mars place important constraints on the structure and dynamics of the interior. The gravity and topography models are significantly phase coherent for harmonic degrees n less than 30 (wavelengths greater than 700 km). Loss of coherence below that wavelength is presumably due to inadequacies of the models, rather than a change in behavior of the planet. The gravity/topography admittance reveals two very different spectral domains: for n greater than 4, a simple Airy compensation model, with mean depth of 100 km, faithfully represents the observed pattern; for degrees 2 and 3, the effective compensation depths are 1400 and 550 km, respectively, strongly arguing for dynamic compensation at those wavelengths. The gravity model has been derived from a reanalysis of the tracking data for Mariner 9 and the Viking Orbiters, The topography model was derived by harmonic analysis of the USGS digital elevation model of Mars. Before comparing gravity and topography for internal structure inferences, we must ensure that both are consistently referenced to a hydrostatic datum. For the gravity, this involves removal of hydrostatic components of the even degree zonal coefficients. For the topography, it involves adding the degree 4 equipotential reference surface, to get spherically referenced values, and then subtracting the full degree 50 equipotential. Variance spectra and phase coherence of orthometric heights and gravity anomalies are addressed.

Global mountain topography and the fate of montane species under climate change

NASA Astrophysics Data System (ADS)

Elsen, Paul R.; Tingley, Morgan W.

2015-08-01

Increasing evidence indicates that species throughout the world are responding to climate change by shifting their geographic distributions. Although shifts can be directionally heterogeneous, they often follow warming temperatures polewards and upslope. Montane species are of particular concern in this regard, as they are expected to face reduced available area of occupancy and increased risk of extinction with upslope movements. However, this expectation hinges on the assumption that surface area decreases monotonically as species move up mountainsides. We analysed the elevational availability of surface area for a global data set containing 182 of the world's mountain ranges. Sixty-eight per cent of these mountain ranges had topographies in which area did not decrease monotonically with elevation. Rather, mountain range topographies exhibited four distinct area-elevation patterns: decreasing (32% of ranges), increasing (6%), a mid-elevation peak in area (39%), and a mid-elevation trough in area (23%). These findings suggest that many species, particularly those of foothills and lower montane zones, may encounter increases in available area as a result of shifting upslope. A deeper understanding of underlying mountain topography can inform conservation priorities by revealing where shifting species stand to undergo area increases, decreases and bottlenecks as they respond to climate change.

The global topography mission gains momentum

USGS Publications Warehouse

Farr, Tom; Evans, Diane; Zebker, Howard; Harding, David; Bufton, Jack; Dixon, Timothy; Vetrella, S.; Gesch, Dean B.

1995-01-01

An accurate description of the surface elevation of the Earth is of fundamental importance to many branches of Earth science. Continental topographic data are required for studies of hydrology, ecology, glaciology, geomorphology, and atmospheric circulation. For example, in hydrologic and terrestrial ecosystem studies, topography exerts significant control on intercepted solar radiation, water runoff and subsurface water inventory, microclimate, vegetation type and distribution, and soil development. The topography of the polar ice caps and mountain glaciers directly reflects ice-flow dynamics and is closely linked to global climate and sea level change.

Seafloor Topography Estimation from Gravity Gradient Using Simulated Annealing

NASA Astrophysics Data System (ADS)

Yang, J.; Jekeli, C.; Liu, L.

2017-12-01

Inferring seafloor topography from gravimetry is an indirect yet proven and efficient means to map the ocean floor. Standard techniques rely on an approximate, linear relationship (Parker's formula) between topography and gravity. It has been reported that in the very rugged areas the discrepancies between prediction and ship soundings are very large, partly because the linear term of Parker's infinite series is dominant only in areas where the local topography is small compared with the regional topography. The validity of the linear approximation is therefore in need of analysis. In this study the nonlinear effects caused by terrain are quantified by both numerical tests and an algorithmic approach called coherency. It is shown that the nonlinear effects are more significant at higher frequencies, which suggests that estimation algorithms with nonlinear approximation in the modeled relationship between gravity gradient and topography should be developed in preparation for future high-resolution gravity gradient missions. The simulated annealing (SA) method is such an optimization technique that can process nonlinear inverse problems, and is used to estimate the seafloor topography parameters in a forward model by minimizing the difference between the observed and forward-computed vertical gravity gradients. Careful treatments like choosing suitable truncation distance, padding the vicinity of the study area with a known topography model, and using the relative cost function, are considered to improve the estimation accuracy. This study uses the gravity gradient, which is more sensitive to topography at short wavelengths than gravity anomaly. The gravity gradient data are derived from satellite altimetry, but the SA has no restrictions on data distribution, as required in Parker's infinite series model, thus enabling the use of airborne gravity gradient data, whose survey trajectories are irregular. The SA method is tested in an area of Guyots (E 156°-158° in

The Influence of Higher-Order Epistasis on Biological Fitness Landscape Topography

NASA Astrophysics Data System (ADS)

Weinreich, Daniel M.; Lan, Yinghong; Jaffe, Jacob; Heckendorn, Robert B.

2018-07-01

The effect of a mutation on the organism often depends on what other mutations are already present in its genome. Geneticists refer to such mutational interactions as epistasis. Pairwise epistatic effects have been recognized for over a century, and their evolutionary implications have received theoretical attention for nearly as long. However, pairwise epistatic interactions themselves can vary with genomic background. This is called higher-order epistasis, and its consequences for evolution are much less well understood. Here, we assess the influence that higher-order epistasis has on the topography of 16 published, biological fitness landscapes. We find that on average, their effects on fitness landscape declines with order, and suggest that notable exceptions to this trend may deserve experimental scrutiny. We conclude by highlighting opportunities for further theoretical and experimental work dissecting the influence that epistasis of all orders has on fitness landscape topography and on the efficiency of evolution by natural selection.

The Influence of Higher-Order Epistasis on Biological Fitness Landscape Topography

NASA Astrophysics Data System (ADS)

Weinreich, Daniel M.; Lan, Yinghong; Jaffe, Jacob; Heckendorn, Robert B.

2018-02-01

The effect of a mutation on the organism often depends on what other mutations are already present in its genome. Geneticists refer to such mutational interactions as epistasis. Pairwise epistatic effects have been recognized for over a century, and their evolutionary implications have received theoretical attention for nearly as long. However, pairwise epistatic interactions themselves can vary with genomic background. This is called higher-order epistasis, and its consequences for evolution are much less well understood. Here, we assess the influence that higher-order epistasis has on the topography of 16 published, biological fitness landscapes. We find that on average, their effects on fitness landscape declines with order, and suggest that notable exceptions to this trend may deserve experimental scrutiny. We conclude by highlighting opportunities for further theoretical and experimental work dissecting the influence that epistasis of all orders has on fitness landscape topography and on the efficiency of evolution by natural selection.

Eocene to mid-Pliocene landscape evolution in Scandinavia inferred from offshore sediment volumes and pre-glacial topography using inverse modelling

NASA Astrophysics Data System (ADS)

Pedersen, Vivi K.; Braun, Jean; Huismans, Ritske S.

2018-02-01

The origin of high topography in Scandinavia is highly debated, both in terms of its age and the underlying mechanism for its formation. Traditionally, the current high topography is assumed to have formed by several Cenozoic (mainly Neogene) phases of surface uplift and dissection of an old peneplain surface. These same surface uplift events are suggested to explain the increased deposition observed in adjacent offshore basins on the Norwegian shelf and in the North Sea. However, more recently it has been suggested that erosion and isostatic rock uplift of existing topography may also explain the recent evolution of topography in Scandinavia. For this latter view, the increased sedimentation towards the present is assumed to be a consequence of a climate related increase in erosion. In this study we explore whether inverse modelling of landscape evolution can give new insight into Eocene to mid-Pliocene (54-4 Ma) landscape evolution in the Scandinavian region. We do this by combining a highly efficient forward-in-time landscape evolution model (FastScape) with an optimization scheme suitable for non-linear inverse problems (the neighbourhood algorithm - NA). To limit our approach to the fluvial regime, we exclude the most recent mid-Pliocene-Quaternary time period where glacial erosion processes are expected to dominate landscape evolution. The "goodness" of our landscape evolution models is evaluated using i) sediment fluxes based on decompacted offshore sediment volumes and ii) maximum pre-glacial topography from a mid-Pliocene landscape, reconstructed using geophysical relief and offshore sediment volumes from the mid-Pliocene-Quaternary. We find several tested scenarios consistent with the offshore sediment record and the maximum elevation for our reconstructed pre-glacial (mid-Pliocene) landscape reconstruction, including: I) substantial initial topography ( 2 km) at 54 Ma and no induced tectonic rock uplift, II) the combination of some initial topography ( 1

Elucidating Dynamical Processes Relevant to Flow Encountering Abrupt Topography (FLEAT)

DTIC Science & Technology

2015-09-30

Encountering Abrupt Topography (FLEAT) Bo Qiu Dept of Oceanography, University of Hawaii at Manoa 1000 Pope Rd. Honolulu, HI 96822 phone: (808) 956...c) to explore relevant dynamics by using both simplified models and OGCM output with realistic topography and surface boundary conditions...scale abyssal circulation, we propose to use the Hallberg Isopycnal Model (HIM). The HIM allows sloping isopycnals to interact with bottom topography

Interactions Between Ocean Circulation and Topography in Icy Worlds

NASA Astrophysics Data System (ADS)

Goodman, J. C.

2018-05-01

To what extent does topography at the water-rock interface control the general circulation patterns of icy world oceans? And contrariwise, to what extent does liquid flow control the topography at the ice-water interface (or interfaces)?

EAARL topography: Cape Cod National Seashore

USGS Publications Warehouse

Brock, John C.; Wright, C. Wayne; Patterson, Matt; Nayegandhi, Amar; Travers, Laurinda J.

2007-01-01

This Web site contains 90 Lidar-derived bare earth topography maps and GIS files for the Cape Cod National Seashore. These Lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Florida Integrated Science Center (FISC) St. Petersburg, Florida, the National Park Service (NPS), Northeast Coastal and Barrier Network, Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to coastal resource managers.

EAARL topography: Assateague Island National Seashore

USGS Publications Warehouse

Brock, John C.; Wright, C. Wayne; Patterson, Matt; Nayegandhi, Amar; Travers, Laurinda J.

2007-01-01

This Web site contains 58 lidar-derived bare earth topography maps and GIS files for the Assateague Island National Seashore. These lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, Florida, the National Park Service (NPS) South Florida/Caribbean Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to costal resource managers.

EAARL Topography-Padre Island National Seashore

USGS Publications Warehouse

Brock, John C.; Wright, C. Wayne; Nayegandhi, Amar; Patterson, Matt; Wilson, Iris; Travers, Laurinda J.

2007-01-01

This Web site contains 116 Lidar-derived bare earth topography maps and GIS files for Padre Island National Seashore-Texas. These Lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Florida Integrated Science Center (FISC) St. Petersburg, Florida, the National Park Service (NPS) Gulf Coast Network, Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to costal resource managers.

Long wavelength gravity and topography anomalies

NASA Technical Reports Server (NTRS)

Watts, A. B.; Daly, S. F.

1981-01-01

It is shown that gravity and topography anomalies on the earth's surface may provide new information about deep processes occurring in the earth, such as those associated with mantle convection. Two main reasons are cited for this. The first is the steady improvement that has occurred in the resolution of the long wavelength gravity field, particularly in the wavelength range of a few hundred to a few thousand km, mainly due to increased coverage of terrestrial gravity measurements and the development of radar altimeters in orbiting satellites. The second reason is the large number of numerical and laboratory experiments of convection in the earth, including some with deformable upper and lower boundaries and temperature-dependent viscosity. The oceans are thought to hold the most promise for determining long wavelength gravity and topography anomalies, since their evolution has been relatively simple in comparison with that of the continents. It is also shown that good correlation between long wavelength gravity and topography anomalies exists over some portions of the ocean floor

Nanotubular topography enhances the bioactivity of titanium implants.

PubMed

Huang, Jingyan; Zhang, Xinchun; Yan, Wangxiang; Chen, Zhipei; Shuai, Xintao; Wang, Anxun; Wang, Yan

2017-08-01

Surface modification on titanium implants plays an important role in promoting mesenchymal stem cell (MSC) response to enhance osseointegration persistently. In this study, nano-scale TiO 2 nanotube topography (TNT), micro-scale sand blasted-acid etched topography (SLA), and hybrid sand blasted-acid etched/nanotube topography (SLA/TNT) were fabricated on the surfaces of titanium implants. Although the initial cell adherence at 60 min among TNT, SLA and TNT/SLA was not different, SLA and SLA/TNT presented to be rougher and suppressed the proliferation of MSC. TNT showed hydrophilic surface and balanced promotion of cellular functions. After being implanted in rabbit femur models, TNT displayed the best osteogenesis inducing ability as well as strong bonding strength to the substrate. These results indicate that nano-scale TNT provides favorable surface topography for improving the clinical performance of endosseous implants compared with micro and hybrid micro/nano surfaces, suggesting a promising and reliable surface modification strategy of titanium implants for clinical application. Copyright © 2017 Elsevier Inc. All rights reserved.

Evaluating the relationship between topography and groundwater using outputs from a continental-scale integrated hydrology model

NASA Astrophysics Data System (ADS)

Condon, Laura E.; Maxwell, Reed M.

2015-08-01

We study the influence of topography on groundwater fluxes and water table depths across the contiguous United States (CONUS). Groundwater tables are often conceptualized as subdued replicas of topography. While it is well known that groundwater configuration is also controlled by geology and climate, nonlinear interactions between these drivers within large real-world systems are not well understood and are difficult to characterize given sparse groundwater observations. We address this limitation using the fully integrated physical hydrology model ParFlow to directly simulate groundwater fluxes and water table depths within a complex heterogeneous domain that incorporates all three primary groundwater drivers. Analysis is based on a first of its kind, continental-scale, high-resolution (1 km), groundwater-surface water simulation spanning more than 6.3 million km2. Results show that groundwater fluxes are most strongly driven by topographic gradients (as opposed to gradients in pressure head) in humid regions with small topographic gradients or low conductivity. These regions are generally consistent with the topographically controlled groundwater regions identified in previous studies. However, we also show that areas where topographic slopes drive groundwater flux do not generally have strong correlations between water table depth and elevation. Nonlinear relationships between topography and water table depth are consistent with groundwater flow systems that are dominated by local convergence and could also be influenced by local variability in geology and climate. One of the strengths of the numerical modeling approach is its ability to evaluate continental-scale groundwater behavior at a high resolution not possible with other techniques. This article was corrected on 11 SEP 2015. See the end of the full text for details.

Head and Neck Cancer—Patient Version

Cancer.gov

Head and neck cancers include cancers in the larynx (voice box), throat, lips, mouth, nose, and salivary glands. Start here to find information on head and neck cancer treatment in adults and children, causes and prevention, screening, research, and statistics.

Countermanding eye-head gaze shifts in humans: marching orders are delivered to the head first.

PubMed

Corneil, Brian D; Elsley, James K

2005-07-01

The countermanding task requires subjects to cancel a planned movement on appearance of a stop signal, providing insights into response generation and suppression. Here, we studied human eye-head gaze shifts in a countermanding task with targets located beyond the horizontal oculomotor range. Consistent with head-restrained saccadic countermanding studies, the proportion of gaze shifts on stop trials increased the longer the stop signal was delayed after target presentation, and gaze shift stop-signal reaction times (SSRTs: a derived statistic measuring how long it takes to cancel a movement) averaged approximately 120 ms across seven subjects. We also observed a marked proportion of trials (13% of all stop trials) during which gaze remained stable but the head moved toward the target. Such head movements were more common at intermediate stop signal delays. We never observed the converse sequence wherein gaze moved while the head remained stable. SSRTs for head movements averaged approximately 190 ms or approximately 70-75 ms longer than gaze SSRTs. Although our findings are inconsistent with a single race to threshold as proposed for controlling saccadic eye movements, movement parameters on stop trials attested to interactions consistent with a race model architecture. To explain our data, we tested two extensions to the saccadic race model. The first assumed that gaze shifts and head movements are controlled by parallel but independent races. The second model assumed that gaze shifts and head movements are controlled by a single race, preceded by terminal ballistic intervals not under inhibitory control, and that the head-movement branch is activated at a lower threshold. Although simulations of both models produced acceptable fits to the empirical data, we favor the second alternative as it is more parsimonious with recent findings in the oculomotor system. Using the second model, estimates for gaze and head ballistic intervals were approximately 25 and 90 ms

Preliminary Results of an Examination of Electronic Cigarette User Puff Topography: The Effect of a Mouthpiece-Based Topography Measurement Device on Plasma Nicotine and Subjective Effects

PubMed Central

Spindle, Tory R.; Breland, Alison B.; Karaoghlanian, Nareg V.; Shihadeh, Alan L.

2015-01-01

Introduction: Electronic cigarettes (ECIGs) heat a nicotine-containing solution; the resulting aerosol is inhaled by the user. Nicotine delivery may be affected by users’ puffing behavior (puff topography), and little is known about the puff topography of ECIG users. Puff topography can be measured using mouthpiece-based computerized systems. However, the extent to which a mouthpiece influences nicotine delivery and subjective effects in ECIG users is unknown. Methods: Plasma nicotine concentration, heart rate, and subjective effects were measured in 13 experienced ECIG users who used their preferred ECIG and liquid (≥12mg/ml nicotine) during 2 sessions (with or without a mouthpiece). In both sessions, participants completed an ECIG use session in which they were instructed to take 10 puffs with 30-second inter-puff intervals. Puff topography was recorded in the mouthpiece condition. Results: Almost all measures of the effects of ECIG use were independent of topography measurement. Collapsed across session, mean plasma nicotine concentration increased by 16.8ng/ml, and mean heart rate increased by 8.5 bpm (ps < .05). Withdrawal symptoms decreased significantly after ECIG use. Participants reported that the mouthpiece affected awareness and made ECIG use more difficult. Relative to previously reported data for tobacco cigarette smokers using similar topography measurement equipment, ECIG-using participants took larger and longer puffs with lower flow rates. Conclusions: In experienced ECIG users, measuring ECIG topography did not influence ECIG-associated nicotine delivery or most measures of withdrawal suppression. Topography measurement systems will need to account for the low flow rates observed for ECIG users. PMID:25239957

Computed tomography findings in young children with minor head injury presenting to the emergency department greater than 24h post injury.

PubMed

Gelernter, Renana; Weiser, Giora; Kozer, Eran

2018-01-01

Large studies which developed decision rules for the use of Computed tomography (CT) in children with minor head trauma excluded children with late presentation (more than 24h). To assess the prevalence of significant traumatic brain injury (TBI) on CT in infants with head trauma presenting to the emergency department (ED) more than 24h from the injury. A retrospective chart review of infants less than 24 months old referred for head CT because of traumatic brain injury from January 2004 to December 2014 in Assaf-Harofeh medical center was conducted. We used the PECARN definitions of TBI on CT to define significant CT findings. 344 cases were analyzed, 68 with late presentation. There was no significant difference in the age between children with late and early presentation (mean 11.4 (SD 5.6) month vs 10. 5 (SD 7.0) month, P=0.27). There was no significant difference between the groups in the incidence of significant TBI (22% vs 19%, p=0.61). Any TBI on CT (e.g. fracture) was found in 43 (63%) patients with late presentation compared with 116 (42%) patients with early presentation (p=0.002, OR 2.37, 95% CI 1.37-4.1). A similar rate of CT-identified traumatic brain injury was detected in both groups.‏ There was no significant difference in the incidence of significant TBI on CT between the groups.‏ Young children presenting to the ED more than 24 hours after the injury may have abnormal findings on CT. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dynamic topography in subduction zones: insights from laboratory models

NASA Astrophysics Data System (ADS)

Bajolet, Flora; Faccenna, Claudio; Funiciello, Francesca

2014-05-01

The topography in subduction zones can exhibit very complex patterns due to the variety of forces operating this setting. If we can deduce the theoretical isostatic value from density structure of the lithosphere, the effect of flexural bending and the dynamic component of topography are difficult to quantify. In this work, we attempt to measure and analyze the topography of the overriding plate during subduction compared to a pure shortening setting. We use analog models where the lithospheres are modeled by thin-sheet layers of silicone putty lying on low-viscosity syrup (asthenosphere). The model is shorten by a piston pushing an oceanic plate while a continental plate including a weak zone to localize the deformation is fixed. In one type of experiments, the oceanic plate bends and subducts underneath the continental one; in a second type the two plates are in contact without any trench, and thus simply shorten. The topography evolution is monitored with a laser-scanner. In the shortening model, the elevation increases progressively, especially in the weak zone, and is consistent with expected isostatic values. In the subduction model, the topography is characterized, from the piston to the back-wall, by a low elevation of the dense oceanic plate, a flexural bulge, the trench forming a deep depression, the highly elevated weak zone, and the continental upper plate of intermediate elevation. The topography of the upper plate is consistent with isostatic values for very early stages, but exhibits lower elevations than expected for later stages. For a same amount of shortening of the continental plate, the thickening is the same and the plate should have the same elevation in both types of models. However, comparing the topography at 20, 29 and 39% of shortening, we found that the weak zone is 0.4 to 0.6 mm lower when there is an active subduction. Theses values correspond to 2.6 to 4 km in nature. Although theses values are high, there are of the same order as

Sea Level Change due to Time-Dependent Long-Wavelength Dynamic Topography Inferred from Plate Tectonic Reconstructions

NASA Astrophysics Data System (ADS)

Conrad, Clinton P.; Steinberger, Bernhard; Torsvik, Trond H.

2017-04-01

Earth's surface is deflected vertically by stresses associated with convective mantle flow. Although dynamic topography is important for both sea level change and continental uplift and subsidence, the time history of dynamic topography is difficult to constrain because the time-dependence of mantle flow is not known. However, the motions of the tectonic plates contain information about the mantle flow patterns that drive them. In particular, we show that the longest wavelengths of mantle flow are tightly linked to the dipole and quadrupole moments (harmonic degrees 1 and 2) of plate motions. This coupling allows us to infer patterns of long-wavelength mantle flow, and the associated dynamic topography, from tectonic plate motions. After calibrating this linkage using models of present-day mantle flow, we can use reconstructions of global plate motions to infer the basic patterns of long-wavelength dynamic topography back to 250 Ma. We find relatively stable dynamic uplift persists above large-scale mantle upwelling beneath Africa and the Central Pacific. Regions of major downwelling encircled the periphery of these stable upwellings, alternating between primarily east-west and north-south orientations. The amplitude of long-wavelength dynamic topography was likely largest in the Cretaceous, when global plate motions were fastest. Continental motions over this time-evolving dynamic topography predict patterns of continental uplift and subsidence that are confirmed by geological observations of continental surfaces relative to sea level. Net uplift or subsidence of the global seafloor can also induce eustatic sea level changes. We infer that dispersal of the Pangean supercontinent away from stable upwelling beneath Africa may have exposed the seafloor to an increasingly larger area of growing positive dynamic topography during the Mesozoic. This net uplift of the seafloor caused 60 m of sea level rise during the Triassic and Jurassic, ceasing in the Cenozoic once

Mapping of sea bottom topography

NASA Technical Reports Server (NTRS)

Calkoen, C. J.; Wensink, G. J.; Hesselmans, G. H. F. M.

1992-01-01

Under suitable conditions the bottom topography of shallow seas is visible in remote sensing radar imagery. Two experiments were performed to establish which remote sensing technique or combination yields optimal imaging of bottom topography and which hydro-meteorological conditions are favorable. A further goal is to gain experience with these techniques. Two experiments were performed over an area in the North Sea near the measuring platform Meetpost Noordwijk (MPN). The bottom topography in the test area is dominated by sand waves. The crests of the sand waves are perpendicular to the coast line and the dominating (tidal-)current direction. A 4x4 sq km wide section of the test area was studied in more detail. The first experiment was undertaken on 16 Aug. 1989. During the experiment the following remote sensing instruments were used: Landsat-Thematic Mapper, and NASA/JPL Airborne Imaging Radar (AIR). The hydro-meteorological conditions; current, wind, wave, and air and water temperature were monitored by MPN, a ship of Rijkswaterstaat (the OCTANS), and a pitch-and-roll WAVEC-buoy. The second experiment took place on 12 July 1992. During this experiment data were collected with the NASA/JPL polarimetric synthetic aperture radar (SAR), and a five-band helicopter-borne scatterometer. Again the hydro-meteorological conditions were monitored at MPN and the OCTANS. Furthermore, interferometric radar data were collected.

Assessing Mand Topography Preference When Developing a Functional Communication Training Intervention.

PubMed

Kunnavatana, S Shanun; Wolfe, Katie; Aguilar, Alexandra N

2018-05-01

Functional communication training (FCT) is a common function-based behavioral intervention used to decrease problem behavior by teaching an alternative communication response. Therapists often arbitrarily select the topography of the alternative response, which may influence long-term effectiveness of the intervention. Assessing individual mand topography preference may increase treatment effectiveness and promote self-determination in the development of interventions. This study sought to reduce arbitrary selection of FCT mand topography by determining preference during response training and acquisition for two adults with autism who had no functional communication skills. Both participants demonstrated a clear preference for one mand topography during choice probes, and the preferred topography was then reinforced during FCT to reduce problem behavior and increase independent communication. The implications of the results for future research on mand selection during FCT are discussed.

Retest reliability of individual alpha ERD topography assessed by human electroencephalography.

PubMed

Vázquez-Marrufo, Manuel; Galvao-Carmona, Alejandro; Benítez Lugo, María Luisa; Ruíz-Peña, Juan Luis; Borges Guerra, Mónica; Izquierdo Ayuso, Guillermo

2017-01-01

Despite the immense literature related to diverse human electroencephalographic (EEG) parameters, very few studies have focused on the reliability of these measures. Some of the most studied components (i.e., P3 or MMN) have received more attention regarding the stability of their main parameters, such as latency, amplitude or topography. However, spectral modulations have not been as extensively evaluated considering that different analysis methods are available. The main aim of the present study is to assess the reliability of the latency, amplitude and topography of event-related desynchronization (ERD) for the alpha band (10-14 Hz) observed in a cognitive task (visual oddball). Topography reliability was analysed at different levels (for the group, within-subjects individually and between-subjects individually). The latency for alpha ERD showed stable behaviour between two sessions, and the amplitude exhibited an increment (more negative) in the second session. Alpha ERD topography exhibited a high correlation score between sessions at the group level (r = 0.903, p<0.001). The mean value for within-subject correlations was 0.750 (with a range from 0.391 to 0.954). Regarding between-subject topography comparisons, some subjects showed a highly specific topography, whereas other subjects showed topographies that were more similar to those of other subjects. ERD was mainly stable between the two sessions with the exception of amplitude, which exhibited an increment in the second session. Topography exhibits excellent reliability at the group level; however, it exhibits highly heterogeneous behaviour at the individual level. Considering that the P3 was previously evaluated for this group of subjects, a direct comparison of the correlation scores was possible, and it showed that the ERD component is less reliable in individual topography than in the ERP component (P3).

Retest reliability of individual alpha ERD topography assessed by human electroencephalography

PubMed Central

Vázquez-Marrufo, Manuel; Benítez Lugo, María Luisa; Ruíz-Peña, Juan Luis; Borges Guerra, Mónica; Izquierdo Ayuso, Guillermo

2017-01-01

Background Despite the immense literature related to diverse human electroencephalographic (EEG) parameters, very few studies have focused on the reliability of these measures. Some of the most studied components (i.e., P3 or MMN) have received more attention regarding the stability of their main parameters, such as latency, amplitude or topography. However, spectral modulations have not been as extensively evaluated considering that different analysis methods are available. The main aim of the present study is to assess the reliability of the latency, amplitude and topography of event-related desynchronization (ERD) for the alpha band (10–14 Hz) observed in a cognitive task (visual oddball). Topography reliability was analysed at different levels (for the group, within-subjects individually and between-subjects individually). Results The latency for alpha ERD showed stable behaviour between two sessions, and the amplitude exhibited an increment (more negative) in the second session. Alpha ERD topography exhibited a high correlation score between sessions at the group level (r = 0.903, p<0.001). The mean value for within-subject correlations was 0.750 (with a range from 0.391 to 0.954). Regarding between-subject topography comparisons, some subjects showed a highly specific topography, whereas other subjects showed topographies that were more similar to those of other subjects. Conclusion ERD was mainly stable between the two sessions with the exception of amplitude, which exhibited an increment in the second session. Topography exhibits excellent reliability at the group level; however, it exhibits highly heterogeneous behaviour at the individual level. Considering that the P3 was previously evaluated for this group of subjects, a direct comparison of the correlation scores was possible, and it showed that the ERD component is less reliable in individual topography than in the ERP component (P3). PMID:29088307

Journal Club: Head CT scans in the emergency department for syncope and dizziness.

PubMed

Mitsunaga, Myles M; Yoon, Hyo-Chun

2015-01-01

The purpose of this study was to determine the yield of acutely abnormal findings on head CT scans in patients presenting to the emergency department with dizziness, near-syncope, or syncope and to determine the clinical factors that potentially predicted acutely abnormal head CT findings and hospital admission. We retrospectively reviewed the electronic medical records of all patients presenting to an HMO emergency department between July 1, 2012, and December 31, 2012, who underwent head CT for a primary complaint of dizziness, syncope, or near-syncope. The primary outcomes were head CT scans with acutely abnormal findings and hospital admission. Binary logistic regression was used to assess the association between clinical variables and acute head CT findings and between clinical variables and hospital admission. Of the 253 patients who presented with dizziness, 7.1% had head CT scans with acutely abnormal findings, and 18.6% were admitted. Of the 236 patients who presented with syncope or near-syncope, 6.4% had head CT scans with acutely abnormal findings, and 39.8% were admitted. The following three clinical factors were found to be significantly correlated with acutely abnormal head CT findings: a focal neurologic deficit (p = 0.003), age greater than 60 years (p = 0.011), and acute head trauma (p = 0.026). Our results suggest that most patients presenting with syncope or dizziness to the emergency department may not benefit from head CT unless they are older, have a focal neurologic deficit, or have a history of recent head trauma.

The Topography Tub Learning Activity

NASA Astrophysics Data System (ADS)

Glesener, G. B.

2014-12-01

Understanding the basic elements of a topographic map (i.e. contour lines and intervals) is just a small part of learning how to use this abstract representational system as a resource in geologic mapping. Interpretation of a topographic map and matching its features with real-world structures requires that the system is utilized for visualizing the shapes of these structures and their spatial orientation. To enrich students' skills in visualizing topography from topographic maps a spatial training activity has been developed that uses 3D objects of various shapes and sizes, a sighting tool, a plastic basin, water, and transparencies. In the first part of the activity, the student is asked to draw a topographic map of one of the 3D objects. Next, the student places the object into a plastic tub in which water is added to specified intervals of height. The shoreline at each interval is used to reference the location of the contour line the student draws on a plastic inkjet transparency directly above the object. A key part of this activity is the use of a sighting tool by the student to assist in keeping the pencil mark directly above the shoreline. It (1) ensures the accurate positioning of the contour line and (2) gives the learner experience with using a sight before going out into the field. Finally, after the student finishes drawing the contour lines onto the transparency, the student can compare and contrast the two maps in order to discover where improvements in their visualization of the contours can be made. The teacher and/or peers can also make suggestions on ways to improve. A number of objects with various shapes and sizes are used in this exercise to produce contour lines representing the different types of topography the student may encounter while field mapping. The intended outcome from using this visualization training activity is improvement in performance of visualizing topography as the student moves between the topographic representation and

Prediction value of the Canadian CT head rule and the New Orleans criteria for positive head CT scan and acute neurosurgical procedures in minor head trauma: a multicenter external validation study.

PubMed

Bouida, Wahid; Marghli, Soudani; Souissi, Sami; Ksibi, Hichem; Methammem, Mehdi; Haguiga, Habib; Khedher, Sonia; Boubaker, Hamdi; Beltaief, Kaouthar; Grissa, Mohamed Habib; Trimech, Mohamed Naceur; Kerkeni, Wiem; Chebili, Nawfel; Halila, Imen; Rejeb, Imen; Boukef, Riadh; Rekik, Noureddine; Bouhaja, Bechir; Letaief, Mondher; Nouira, Semir

2013-05-01

The New Orleans Criteria and the Canadian CT Head Rule have been developed to decrease the number of normal computed tomography (CT) results in mild head injury. We compare the performance of both decision rules for identifying patients with intracranial traumatic lesions and those who require an urgent neurosurgical intervention after mild head injury. This was an observational cohort study performed between 2008 and 2011 on patients with mild head injury who were aged 10 years or older. We collected prospectively clinical head CT scan findings and outcome. Primary outcome was need for neurosurgical intervention, defined as either death or craniotomy, or the need of intubation within 15 days of the traumatic event. Secondary outcome was the presence of traumatic lesions on head CT scan. New Orleans Criteria and Canadian CT Head Rule decision rules were compared by using sensitivity specifications and positive and negative predictive value. We enrolled 1,582 patients. Neurosurgical intervention was performed in 34 patients (2.1%) and positive CT findings were demonstrated in 218 patients (13.8%). Sensitivity and specificity for need for neurosurgical intervention were 100% (95% confidence interval [CI] 90% to 100%) and 60% (95% CI 44% to 76%) for the Canadian CT Head Rule and 82% (95% CI 69% to 95%) and 26% (95% CI 24% to 28%) for the New Orleans Criteria. Negative predictive values for the above-mentioned clinical decision rules were 100% and 99% and positive values were 5% and 2%, respectively, for the Canadian CT Head Rule and New Orleans Criteria. Sensitivity and specificity for clinical significant head CT findings were 95% (95% CI 92% to 98%) and 65% (95% CI 62% to 68%) for the Canadian CT Head Rule and 86% (95% CI 81% to 91%) and 28% (95% CI 26% to 30%) for the New Orleans Criteria. A similar trend of results was found in the subgroup of patients with a Glasgow Coma Scale score of 15. For patients with mild head injury, the Canadian CT Head Rule had higher

Refining the ischemic penumbra with topography.

PubMed

Thirugnanachandran, Tharani; Ma, Henry; Singhal, Shaloo; Slater, Lee-Anne; Davis, Stephen M; Donnan, Geoffrey A; Phan, Thanh

2018-04-01

It has been 40 years since the ischemic penumbra was first conceptualized through work on animal models. The topography of penumbra has been portrayed as an infarcted core surrounded by penumbral tissue and an extreme rim of oligemic tissue. This picture has been used in many review articles and textbooks before the advent of modern imaging. In this paper, we review our understanding of the topography of the ischemic penumbra from the initial experimental animal models to current developments with neuroimaging which have helped to further define the temporal and spatial evolution of the penumbra and refine our knowledge. The concept of the penumbra has been successfully applied in clinical trials of endovascular therapies with a time window as long as 24 h from onset. Further, there are reports of "good" outcome even in patients with a large ischemic core. This latter observation of good outcome despite having a large core requires an understanding of the topography of the penumbra and the function of the infarcted regions. It is proposed that future research in this area takes departure from a time-dependent approach to a more individualized tissue and location-based approach.

EAARL topography: Gateway National Recreation Area

USGS Publications Warehouse

Brock, John C.; Wright, C. Wayne; Patterson, Matt; Nayegandhi, Amar; Patterson, Judd

2007-01-01

This Web site contains Lidar-derived topography (bare earth) maps and GIS files for the Sandy Hook Unit within Gateway National Recreation Area in New Jersey. These Lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, the National Park Service (NPS) South Florida/Caribbean Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to costal resource managers.

Gravity/Topography Admittances and Lithospheric Evolution on Mars: The Importance of Finite-Amplitude Topography

NASA Technical Reports Server (NTRS)

McGovern, Patrick J.; Solomon, Sean C.; Smith, David E.; Zuber, Maria T.; Neumann, Gregory A.; Head, J. W., III; Phillips, Roger J.; Simons, Mark

2001-01-01

We calculate localized gravity/topography admittances for Mars, in order to estimate elastic lithosphere thickness. A finite-amplitude correction to modeled gravity is required to properly interpret admittances in high-relief regions of Mars. Additional information is contained in the original extended abstract.

Preliminary results of an examination of electronic cigarette user puff topography: the effect of a mouthpiece-based topography measurement device on plasma nicotine and subjective effects.

PubMed

Spindle, Tory R; Breland, Alison B; Karaoghlanian, Nareg V; Shihadeh, Alan L; Eissenberg, Thomas

2015-02-01

Electronic cigarettes (ECIGs) heat a nicotine-containing solution; the resulting aerosol is inhaled by the user. Nicotine delivery may be affected by users' puffing behavior (puff topography), and little is known about the puff topography of ECIG users. Puff topography can be measured using mouthpiece-based computerized systems. However, the extent to which a mouthpiece influences nicotine delivery and subjective effects in ECIG users is unknown. Plasma nicotine concentration, heart rate, and subjective effects were measured in 13 experienced ECIG users who used their preferred ECIG and liquid (≥ 12 mg/ml nicotine) during 2 sessions (with or without a mouthpiece). In both sessions, participants completed an ECIG use session in which they were instructed to take 10 puffs with 30-second inter-puff intervals. Puff topography was recorded in the mouthpiece condition. Almost all measures of the effects of ECIG use were independent of topography measurement. Collapsed across session, mean plasma nicotine concentration increased by 16.8 ng/ml, and mean heart rate increased by 8.5 bpm (ps < .05). Withdrawal symptoms decreased significantly after ECIG use. Participants reported that the mouthpiece affected awareness and made ECIG use more difficult. Relative to previously reported data for tobacco cigarette smokers using similar topography measurement equipment, ECIG-using participants took larger and longer puffs with lower flow rates. In experienced ECIG users, measuring ECIG topography did not influence ECIG-associated nicotine delivery or most measures of withdrawal suppression. Topography measurement systems will need to account for the low flow rates observed for ECIG users. © The Author 2014. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Can weak crust explain the correlation of geoid and topography on Venus?

NASA Technical Reports Server (NTRS)

Buck, W. Roger

1993-01-01

The effect on geoid and topography of low viscosity crust overlying a steady-state convecting mantle is estimated under the assumption that the shear between crust and mantle does not alter the mantle flow. The weak crustal layer can change the sign of the geoid to topography ratio (admittance). The positive long wavelength admittance for Venus is consistent with a weak crust overlying a mantle with a viscosity that increases strongly with depth. The accepted interpretation of the strong positive correlation of geoid and topography on Venus, is that the convecting mantle of Venus has a constant viscosity with depth. Topography results from vertical normal stresses caused by mantle convection and highlands occur where mantle upwells. For topography to be supported by normal stress, the time scale for crustal flow must be long compared to the time scale for changes in the pattern of mantle flow. Because the high surface temperature of Venus may cause the crust to have a low viscosity, this assumption may be false. Topography should then be dominated by shear coupling between the crust and mantle. In the absence of a crustal layer, convection in a constant viscosity layer gives rise to a geoid anomaly that correlates positively with surface topography. When the viscosity in the layer increases with depth by several orders of magnitude, the surface topography and geoid anomaly become anti-correlated.

Constraints on the shear speed, crust thickness and residual topography of western Tibet from surface wave tomography and virtual deep seismic sounding

NASA Astrophysics Data System (ADS)

Matchette-Downes, H.; van der Hilst, R. D.; Priestley, K. F.

2017-12-01

We have estimated the thickness of the crust in western Tibet by measuring the time delays between the direct S and the SsPmp seismic phases. We find that the thickness of the crust increases from around 50 km beneath the Tethyan Himalayas to around 80 km beneath the Lhasa block, and then decreases to around 70 km beneath the Qiangtang terrane.This method, virtual deep seismic sounding (VDSS), also yields robust estimates of the contribution of crust buoyancy to elevation. By subtracting the predicted elevation from the real topography, we find there is no observable deviation from hydrostatic topography beneath the Tethyan Himalaya, but there is negative residual topography of 1.5 to 2.0 km beneath the Lhasa and Qiangtang terranes. It is also known that the interior of the Plateau is isostatically compensated, as it has small free air gravity anomalies.Additionally, we have estimated the 3D shear speed structure of the crust and upper mantle. This model is derived from maps of the fundamental mode Rayleigh wave phase speed dispersion in the period range from 20 to 140 s, obtained from a standard two-plane-wave inversion constrained with receiver functions and group speeds from ambient noise. The observations agree with previous observations of a low-wavespeed zone in the mid-crust and a gradual Moho. Furthermore, the long-period Rayleigh waves detect a high-wavespeed upper mantle.Together, the observations of high upper mantle wavespeeds, negative residual topography, and small free air gravity anomalies support the hypothesis that cold, dense Indian lithosphere has underthrust the Plateau in this region. However, in the presentation we also consider contributions to residual topography from plate flexure, lower crustal flow, or deeper mantle flow (dynamic topography).

Topography-guided photorefractive keratectomy for irregular astigmatism after small incision lenticule extraction.

PubMed

Ivarsen, Anders; Hjortdal, Jesper Ø

2014-06-01

To report the outcome of topography-guided photorefractive keratectomy (PRK) after complicated small incision lenticule extraction (SMILE). Retrospective case series of 5 eyes with irregular topography and ghost images after complicated SMILE. All eyes received transepithelial topography-guided PRK. Two eyes were treated with 0.02% mitomycin C. Patients were examined after a minimum of 3 months with evaluation of uncorrected (UDVA) and corrected (CDVA) distance visual acuity, Pentacam tomography (Oculus Optikgeräte, Wetzlar, Germany), and whole-eye aberrometry. In 3 eyes, subjective symptoms were diminished and UDVA, CDVA, topography, and corneal wavefront aberrations were improved. The remaining 2 eyes developed significant haze with worsened topography and wavefront aberrations. One eye experienced a two-line reduction in CDVA. Eyes with haze development had not been treated with mitomycin C. Transepithelial topography-guided PRK may reduce visual symptoms after complicated SMILE if postoperative haze can be controlled. To reduce the risk of haze development, application of mitomycin C may be considered. Copyright 2014, SLACK Incorporated.

Risk factors and topographies for self-injurious behaviour in a sample of adults with intellectual developmental disorders.

PubMed

Folch, A; Cortés, M J; Salvador-Carulla, L; Vicens, P; Irazábal, M; Muñoz, S; Rovira, L; Orejuela, C; Haro, J M; Vilella, E; Martínez-Leal, R

2018-04-01

Self-injurious behaviour (SIB) is a prevalent form of challenging behaviour in people with intellectual developmental disorders (IDD). Existing research has yielded conflicting findings concerning the major risk factors involved, and in addition, SIB shows multiple topographies and presentations. Although presence of autism spectrum disorders (ASD) and severity of intellectual disability (ID) are known risk factors for SIB, there are no studies comparing SIB topographies by severity degrees of ID and ASD. The purpose of the present paper has been to identify risk factors and topographies for SIB in a representative, stratified and randomised sample of adults with IDD. This study was conducted on the basis of data collected by the POMONA-ESP project, in a sample of 833 adults with IDD. Data concerning demographic and health information, ASD symptoms, psychopathology and ID, have been analysed to determine the presence of risk factors for SIB among participants and to explore the occurrence and topographies of SIB across different severity levels of ID and ASD symptoms. Self-injurious behaviour prevalence in the sample was 16.2%. Younger age, oral pain, greater severity of ID, presence of dual diagnosis, psychiatric medication intake and higher scores on Childhood Autism Rating Scale were risk factors for SIB among participants, whereas number of areas with functioning limitations, place of residence, diagnosis of epilepsy and sex were not. SIB was more frequent in participants with ASD symptoms regardless of its severity level, and they displayed a higher number of different topographies of SIB. People with profound ID without co-morbid ASD symptoms showed similar results concerning SIB prevalence and topographies. Knowledge on risk factors and topographies of SIB might play a vital role in the development of prevention strategies and management of SIB in people with IDD. The mere presence of ASD symptoms, regardless of its severity level, can be a crucial factor to

Assessment of the effectiveness of head only and back-of-the-head electrical stunning of chickens

PubMed Central

Gibson, T. J.; Taylor, A. H.; Gregory, N. G.

2016-01-01

Abstract The study assesses the effectiveness of reversible head-only and back-of-the-head electrical stunning of chickens using 130–950 mA per bird at 50 Hz AC.Three trials were conducted to compare both stunning systems: (a) behavioural assessment of return of consciousness, (b) insensibility to thermal pain, and (c) assessment of return of brain activity with visually evoked potentials (VEPs).Assessment of behaviour suggested that the period of unconsciousness following head-only electrical stunning was shorter in hens compared to broilers.Stunning across the back-of-the-head delayed the time to return of brainstem function compared to stunning with standard head-only electrodes. Additionally, back-of-the-head stunning produced a more prolonged period of electroanalgesia compared to head-only.Based on examination of return of brain function with VEPs in hens, back-of-the-head stunning produced a shorter-lasting stun than standard head-only. However, even for standard head-only, the stun was notably shorter than previously reported. In some birds, brain function had returned within 9 s after the end of stunning.The results suggest that some birds may recover consciousness prior to or during the neck cut. Based on these findings, back-of-the-head stunning and standard head-only stunning of hens should not be recommended without further development. PMID:27023411

Head and Neck Cancer—Health Professional Version

Cancer.gov

Head and neck cancers include hypopharyngeal, laryngeal, lip and oral cavity, metastatic squamous neck, nasopharyngeal, oropharyngeal, paranasal sinus, and salivary gland cancers. Find evidence-based information on head and neck cancer treatment, causes and prevention, research, screening, and statistics.

Assessing the Impact of Laurentide Ice-sheet Topography on Glacial Climate

NASA Technical Reports Server (NTRS)

Ullman, D. J.; LeGrande, A. N.; Carlson, A. E.; Anslow, F. S.; Licciardi, J. M.

2014-01-01

Simulations of past climates require altered boundary conditions to account for known shifts in the Earth system. For the Last Glacial Maximum (LGM) and subsequent deglaciation, the existence of large Northern Hemisphere ice sheets caused profound changes in surface topography and albedo. While ice-sheet extent is fairly well known, numerous conflicting reconstructions of ice-sheet topography suggest that precision in this boundary condition is lacking. Here we use a high-resolution and oxygen-isotopeenabled fully coupled global circulation model (GCM) (GISS ModelE2-R), along with two different reconstructions of the Laurentide Ice Sheet (LIS) that provide maximum and minimum estimates of LIS elevation, to assess the range of climate variability in response to uncertainty in this boundary condition.We present this comparison at two equilibrium time slices: the LGM, when differences in ice-sheet topography are maximized, and 14 ka, when differences in maximum ice-sheet height are smaller but still exist. Overall, we find significant differences in the climate response to LIS topography, with the larger LIS resulting in enhanced Atlantic Meridional Overturning Circulation and warmer surface air temperatures, particularly over northeastern Asia and the North Pacific. These up- and downstream effects are associated with differences in the development of planetary waves in the upper atmosphere, with the larger LIS resulting in a weaker trough over northeastern Asia that leads to the warmer temperatures and decreased albedo from snow and sea-ice cover. Differences between the 14 ka simulations are similar in spatial extent but smaller in magnitude, suggesting that climate is responding primarily to the larger difference in maximum LIS elevation in the LGM simulations. These results suggest that such uncertainty in ice-sheet boundary conditions alone may significantly impact the results of paleoclimate simulations and their ability to successfully simulate past climates

The Impact of Head Start on Children, Families and Communities. Final Report of the Head Start Evaluation, Synthesis and Utilization Project.

ERIC Educational Resources Information Center

McKey, Ruth Hubbell; And Others

Including all Head Start research (both published and unpublished) and using, when possible, the statistical technique of meta-analysis, this final report of the Head Start Evaluation, Synthesis, and Utilization Project presents findings on the impact of Head Start on children's cognitive and socioemotional development, on child health and health…

Navigating neurites utilize cellular topography of Schwann cell somas and processes for optimal guidance

PubMed Central

Lopez-Fagundo, Cristina; Mitchel, Jennifer A.; Ramchal, Talisha D.; Dingle, Yu-Ting L.; Hoffman-Kim, Diane

2013-01-01

The path created by aligned Schwann cells (SCs) after nerve injury underlies peripheral nerve regeneration. We developed geometric bioinspired substrates to extract key information needed for axon guidance by deconstructing the topographical cues presented by SCs. We have previously reported materials that directly replicate SC topography with micro- and nanoscale resolution, but a detailed explanation of the means of directed axon extension on SC topography has not yet been described. Here, using neurite tracing and time-lapse microscopy, we analyzed the SC features that influence axon guidance. Novel poly(dimethylsiloxane) materials, fabricated via photolithography, incorporated bioinspired topographical components with the shapes and sizes of aligned SCs, namely somas and processes, where the length of the processes were varied but the soma geometry and dimensions were kept constant. Rat dorsal root ganglia neurites aligned to all materials presenting bioinspired topography after a 5 days in culture and to bioinspired materials presenting soma and process features after only 17 hours in culture. Key findings of this study were: Neurite response to underlying bioinspired topographical features was time dependent, where at 5 days, neurites aligned most strongly to materials presenting combinations of soma and process features, with higher than average density of either process or soma features; but at 17 hours they aligned more strongly to materials presenting average densities of soma and process features and to materials presenting process features only. These studies elucidate the influence of SC topography on axon guidance in a time-dependent setting and have implications for the optimization of nerve regeneration strategies. PMID:23557939

Effects of Topography-based Subgrid Structures on Land Surface Modeling

NASA Astrophysics Data System (ADS)

Tesfa, T. K.; Ruby, L.; Brunke, M.; Thornton, P. E.; Zeng, X.; Ghan, S. J.

2017-12-01

Topography has major control on land surface processes through its influence on atmospheric forcing, soil and vegetation properties, network topology and drainage area. Consequently, accurate climate and land surface simulations in mountainous regions cannot be achieved without considering the effects of topographic spatial heterogeneity. To test a computationally less expensive hyper-resolution land surface modeling approach, we developed topography-based landunits within a hierarchical subgrid spatial structure to improve representation of land surface processes in the ACME Land Model (ALM) with minimal increase in computational demand, while improving the ability to capture the spatial heterogeneity of atmospheric forcing and land cover influenced by topography. This study focuses on evaluation of the impacts of the new spatial structures on modeling land surface processes. As a first step, we compare ALM simulations with and without subgrid topography and driven by grid cell mean atmospheric forcing to isolate the impacts of the subgrid topography on the simulated land surface states and fluxes. Recognizing that subgrid topography also has important effects on atmospheric processes that control temperature, radiation, and precipitation, methods are being developed to downscale atmospheric forcings. Hence in the second step, the impacts of the subgrid topographic structure on land surface modeling will be evaluated by including spatial downscaling of the atmospheric forcings. Preliminary results on the atmospheric downscaling and the effects of the new spatial structures on the ALM simulations will be presented.

The fragility of statistically significant findings from randomized trials in head and neck surgery.

PubMed

Noel, Christopher W; McMullen, Caitlin; Yao, Christopher; Monteiro, Eric; Goldstein, David P; Eskander, Antoine; de Almeida, John R

2018-04-23

The Fragility Index (FI) is a novel tool for evaluating the robustness of statistically significant findings in a randomized control trial (RCT). It measures the number of events upon which statistical significance depends. We sought to calculate the FI scores for RCTs in the head and neck cancer literature where surgery was a primary intervention. Potential articles were identified in PubMed (MEDLINE), Embase, and Cochrane without publication date restrictions. Two reviewers independently screened eligible RCTs reporting at least one dichotomous and statistically significant outcome. The data from each trial were extracted and the FI scores were calculated. Associations between trial characteristics and FI were determined. In total, 27 articles were identified. The median sample size was 67.5 (interquartile range [IQR] = 42-143) and the median number of events per trial was 8 (IQR = 2.25-18.25). The median FI score was 1 (IQR = 0-2.5), meaning that changing one patient from a nonevent to an event in the treatment arm would change the result to a statistically nonsignificant result, or P > .05. The FI score was less than the number of patients lost to follow-up in 71% of cases. The FI score was found to be moderately correlated with P value (ρ = -0.52, P = .007) and with journal impact factor (ρ = 0.49, P = .009) on univariable analysis. On multivariable analysis, only the P value was found to be a predictor of FI score (P = .001). Randomized trials in the head and neck cancer literature where surgery is a primary modality are relatively nonrobust statistically with low FI scores. Laryngoscope, 2018. © 2018 The American Laryngological, Rhinological and Otological Society, Inc.

Understanding the mechanisms of solid-water reactions through analysis of surface topography.

PubMed

Bandstra, Joel Z; Brantley, Susan L

2015-12-01

The topography of a reactive surface contains information about the reactions that form or modify the surface and, therefore, it should be possible to characterize reactivity using topography parameters such as surface area, roughness, or fractal dimension. As a test of this idea, we consider a two-dimensional (2D) lattice model for crystal dissolution and examine a suite of topography parameters to determine which may be useful for predicting rates and mechanisms of dissolution. The model is based on the assumption that the reactivity of a surface site decreases with the number of nearest neighbors. We show that the steady-state surface topography in our model system is a function of, at most, two variables: the ratio of the rate of loss of sites with two neighbors versus three neighbors (d(2)/d(3)) and the ratio of the rate of loss of sites with one neighbor versus three neighbors (d(1)/d(3)). This means that relative rates can be determined from two parameters characterizing the topography of a surface provided that the two parameters are independent of one another. It also means that absolute rates cannot be determined from measurements of surface topography alone. To identify independent sets of topography parameters, we simulated surfaces from a broad range of d(1)/d(3) and d(2)/d(3) and computed a suite of common topography parameters for each surface. Our results indicate that the fractal dimension D and the average spacing between steps, E[s], can serve to uniquely determine d(1)/d(3) and d(2)/d(3) provided that sufficiently strong correlations exist between the steps. Sufficiently strong correlations exist in our model system when D>1.5 (which corresponds to D>2.5 for real 3D reactive surfaces). When steps are uncorrelated, surface topography becomes independent of step retreat rate and D is equal to 1.5. Under these conditions, measures of surface topography are not independent and any single topography parameter contains all of the available mechanistic

Corneal topography with an aberrometry-topography system.

PubMed

Mülhaupt, Michael; Dietzko, Sven; Wolffsohn, James; Bandlitz, Stefan

2018-05-07

To investigate the agreement between the central corneal radii and corneal eccentricity measurements generated by the new Wave Analyzer 700 Medica (WAV) compared to the Keratograph 4 (KER) and to test the repeatability of the instruments. 20 subjects (10 male, mean age 29.1 years, range 21-50 years) were recruited from the students and staff of the Cologne School of Optometry. Central corneal radii for the flat (r c/fl ) and steep (r c/st ) meridian as well as corneal eccentricity for the nasal (e nas ), temporal (e temp ), inferior (e inf ) and superior (e sup ) directions were measured using WAV and KER by one examiner in a randomized order. Central radii of the flat (r c/fl ) and steep (r c/st ) meridian measured with both instruments were statically significantly correlated (r = 0.945 and r = 0.951; p < 0.001). Comparison between the WAV and KER showed that r c/fl and r c/st measured with WAV were significantly steeper than those measured with KER (p < 0.001). Corneal eccentricities were statistically significantly correlated in all meridians (p < 0.05). Compared to KER, e temp and e sup measured with WAV were greater (p < 0.05), while there were no statistically significant differences for e nas and e inf (p = 0.350 and p = 0.083). For the central radii, repeated measurements were not significantly different for the KER or WAV (p > 0.05). Limits of agreement (LoA) indicate a better repeatability for the KER compared to WAV. Corneal topography measurements captured with the WAV were strongly correlated with the KER. However, due to the differences in measured corneal radii and eccentricities, the devices cannot be used interchangeably. For corneal topography the KER demonstrated better repeatability. Copyright © 2018 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Does Dry Eye Affect Repeatability of Corneal Topography Measurements?

PubMed

Doğan, Aysun Şanal; Gürdal, Canan; Köylü, Mehmet Talay

2018-04-01

The purpose of this study was to assess the repeatability of corneal topography measurements in dry eye patients and healthy controls. Participants underwent consecutive corneal topography measurements (Sirius; Costruzione Strumenti Oftalmici, Florence, Italy). Two images with acquisition quality higher than 90% were accepted. The following parameters were evaluated: minimum and central corneal thickness, aqueous depth, apex curvature, anterior chamber volume, horizontal anterior chamber diameter, iridocorneal angle, cornea volume, and average simulated keratometry. Repeatability was assessed by calculating intra-class correlation coefficient. Thirty-three patients with dry eye syndrome and 40 healthy controls were enrolled to the study. The groups were similar in terms of age (39 [18-65] vs. 30.5 [18-65] years, p=0.198) and gender (M/F: 4/29 vs. 8/32, p=0.366). Intra-class correlation coefficients among all topography parameters within both groups showed excellent repeatability (>0.90). The anterior segment measurements provided by the Sirius corneal topography system were highly repeatable for dry eye patients and are sufficiently reliable for clinical practice and research.

EAARL topography: Thomas Stone National Historic Site

USGS Publications Warehouse

Brock, John C.; Wright, C. Wayne; Patterson, Matt; Nayegandhi, Amar; Patterson, Judd

2007-01-01

This Web site contains Lidar-derived topography (first return and bare earth) maps and GIS files for Thomas Stone National Historic Site in Maryland. These Lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, the National Park Service (NPS) South Florida/Caribbean Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to costal resource managers.

EAARL topography: Gulf Islands National Seashore: Florida

USGS Publications Warehouse

Brock, John C.; Wright, C. Wayne; Nayegandhi, Amar; Patterson, Matt; Wilson, Iris; Travers, Laurinda J.

2007-01-01

This Web site contains 33 lidar-derived bare earth topography maps and GIS files for the Gulf Islands National Seashore-Florida. These lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, Florida, the National Park Service (NPS), Gulf Coast Network, Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to costal resource managers.

EAARL topography: Gulf Islands National Seashore: Mississippi

USGS Publications Warehouse

Brock, John C.; Wright, C. Wayne; Nayegandhi, Amar; Patterson, Matt; Wilson, Iris; Travers, Laurinda J.

2007-01-01

This Web site contains 30 lidar-derived bare earth topography maps and GIS files for the Gulf Islands National Seashore-Mississippi. These lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, Florida, the National Park Service (NPS) Gulf Coast Network, Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to costal resource managers.

EAARL topography: George Washington Birthplace National Monument

USGS Publications Warehouse

Brock, John C.; Wright, C. Wayne; Patterson, Matt; Nayegandhi, Amar; Patterson, Judd

2007-01-01

This Web site contains Lidar-derived topography (first return and bare earth) maps and GIS files for George Washington Birthplace National Monument in Virginia. These lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, the National Park Service (NPS), Northeast Coastal and Barrier Network, Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to coastal resource managers.

Tonal frequency affects amplitude but not topography of rhesus monkey cranial EEG components.

PubMed

Teichert, Tobias

2016-06-01

The rhesus monkey is an important model of human auditory function in general and auditory deficits in neuro-psychiatric diseases such as schizophrenia in particular. Several rhesus monkey studies have described homologs of clinically relevant auditory evoked potentials such as pitch-based mismatch negativity, a fronto-central negativity that can be observed when a series of regularly repeating sounds is disrupted by a sound of different tonal frequency. As a result it is well known how differences of tonal frequency are represented in rhesus monkey EEG. However, to date there is no study that systematically quantified how absolute tonal frequency itself is represented. In particular, it is not known if frequency affects rhesus monkey EEG component amplitude and topography in the same way as previously shown for humans. A better understanding of the effect of frequency may strengthen inter-species homology and will provide a more solid foundation on which to build the interpretation of frequency MMN in the rhesus monkey. Using arrays of up to 32 cranial EEG electrodes in 4 rhesus macaques we identified 8 distinct auditory evoked components including the N85, a fronto-central negativity that is the presumed homolog of the human N1. In line with human data, the amplitudes of most components including the N85 peaked around 1000 Hz and were strongly attenuated above ∼1750 Hz. Component topography, however, remained largely unaffected by frequency. This latter finding may be consistent with the known absence of certain anatomical structures in the rhesus monkey that are believed to cause the changes in topography in the human by inducing a rotation of generator orientation as a function of tonal frequency. Overall, the findings are consistent with the assumption of a homolog representation of tonal frequency in human and rhesus monkey EEG. Copyright © 2016 Elsevier B.V. All rights reserved.

Skull Defects in Finite Element Head Models for Source Reconstruction from Magnetoencephalography Signals

PubMed Central

Lau, Stephan; Güllmar, Daniel; Flemming, Lars; Grayden, David B.; Cook, Mark J.; Wolters, Carsten H.; Haueisen, Jens

2016-01-01

Magnetoencephalography (MEG) signals are influenced by skull defects. However, there is a lack of evidence of this influence during source reconstruction. Our objectives are to characterize errors in source reconstruction from MEG signals due to ignoring skull defects and to assess the ability of an exact finite element head model to eliminate such errors. A detailed finite element model of the head of a rabbit used in a physical experiment was constructed from magnetic resonance and co-registered computer tomography imaging that differentiated nine tissue types. Sources of the MEG measurements above intact skull and above skull defects respectively were reconstructed using a finite element model with the intact skull and one incorporating the skull defects. The forward simulation of the MEG signals reproduced the experimentally observed characteristic magnitude and topography changes due to skull defects. Sources reconstructed from measured MEG signals above intact skull matched the known physical locations and orientations. Ignoring skull defects in the head model during reconstruction displaced sources under a skull defect away from that defect. Sources next to a defect were reoriented. When skull defects, with their physical conductivity, were incorporated in the head model, the location and orientation errors were mostly eliminated. The conductivity of the skull defect material non-uniformly modulated the influence on MEG signals. We propose concrete guidelines for taking into account conducting skull defects during MEG coil placement and modeling. Exact finite element head models can improve localization of brain function, specifically after surgery. PMID:27092044

Dual Use of Cigarettes, Little Cigars, Cigarillos, and Large Cigars: Smoking Topography and Toxicant Exposure.

PubMed

Pickworth, Wallace B; Rosenberry, Zachary R; O'Grady, Kevin E; Koszowski, Bartosz

2017-04-01

Smoking topography variables and toxicant exposure (plasma nicotine and exhaled CO) were examined in 3 groups of study participants that smoked both cigarettes and either filtered little cigars (Winchester), cigarillos (Black & Mild), or large cigars (Phillies Blunt). Laboratory ad lib smoking of the cigar products was collected with a smoking puff analyzer; plasma levels of nicotine and exhaled CO were collected before and after smoking. Although there were no statistically significant differences in demographic and cigarette smoking topography among the groups, there were significant differences in how the different cigar products were smoked. Plasma nicotine boost was similar after all products but exhaled CO was greater after the cigarillo and large cigar than the little cigar. Some of the differences were due to the differences in article size but other differences were apparent even after adjustment for the amount of tobacco burned or the mouth intake (puff volume). The topography findings of differences among products challenge the practice of grouping cigars as a single entity in surveys, regulatory decisions, and discussions of toxicant exposure. The results add to the discussion of distinctions among products in the scientific assessment of public health risk and regulatory decisions.

Effects of realistic topography on the ground motion of the Colombian Andes - A case study at the Aburrá Valley, Antioquia

NASA Astrophysics Data System (ADS)

Restrepo, Doriam; Bielak, Jacobo; Serrano, Ricardo; Gómez, Juan; Jaramillo, Juan

2016-03-01

This paper presents a set of deterministic 3-D ground motion simulations for the greater metropolitan area of Medellín in the Aburrá Valley, an earthquake-prone region of the Colombian Andes that exhibits moderate-to-strong topographic irregularities. We created the velocity model of the Aburrá Valley region (version 1) using the geological structures as a basis for determining the shear wave velocity. The irregular surficial topography is considered by means of a fictitious domain strategy. The simulations cover a 50 × 50 × 25 km3 volume, and four Mw = 5 rupture scenarios along a segment of the Romeral fault, a significant source of seismic activity in Colombia. In order to examine the sensitivity of ground motion to the irregular topography and the 3-D effects of the valley, each earthquake scenario was simulated with three different models: (i) realistic 3-D velocity structure plus realistic topography, (ii) realistic 3-D velocity structure without topography, and (iii) homogeneous half-space with realistic topography. Our results show how surface topography affects the ground response. In particular, our findings highlight the importance of the combined interaction between source-effects, source-directivity, focusing, soft-soil conditions, and 3-D topography. We provide quantitative evidence of this interaction and show that topographic amplification factors can be as high as 500 per cent at some locations. In other areas within the valley, the topographic effects result in relative reductions, but these lie in the 0-150 per cent range.

Topography of Troughs on Vesta

NASA Image and Video Library

2011-08-23

This view of the topography of asteroid Vesta surface is composed of several images obtained with the clear filter in the framing camera on NASA Dawn spacecraft on August 6, 2011. The image has a resolution of about 260 meters per pixel.

Investigating Flow Features Near Abrupt Topography in the Mariana Basin

DTIC Science & Technology

2015-09-30

1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Investigating Flow Features Near Abrupt Topography in...waves generated by flow over topography and mesoscale eddies generated by flow past islands. Having identified the prime locations in the region for such

Golden angle based scanning for robust corneal topography with OCT

PubMed Central

Wagner, Joerg; Goldblum, David; Cattin, Philippe C.

2017-01-01

Corneal topography allows the assessment of the cornea’s refractive power which is crucial for diagnostics and surgical planning. The use of optical coherence tomography (OCT) for corneal topography is still limited. One limitation is the susceptibility to disturbances like blinking of the eye. This can result in partially corrupted scans that cannot be evaluated using common methods. We present a new scanning method for reliable corneal topography from partial scans. Based on the golden angle, the method features a balanced scan point distribution which refines over measurement time and remains balanced when part of the scan is removed. The performance of the method is assessed numerically and by measurements of test surfaces. The results confirm that the method enables numerically well-conditioned and reliable corneal topography from partially corrupted scans and reduces the need for repeated measurements in case of abrupt disturbances. PMID:28270961

Feature-based characterisation of signature topography in laser powder bed fusion of metals

NASA Astrophysics Data System (ADS)

Senin, Nicola; Thompson, Adam; Leach, Richard

2018-04-01

The use of state-of-the-art areal topography measurement instrumentation allows for a high level of detail in the acquisition of topographic information at micrometric scales. The 3D geometric models of surface topography obtained from measured data create new opportunities for the investigation of manufacturing processes through characterisation of the surfaces of manufactured parts. Conventional methods for quantitative assessment of topography usually only involve the computation of texture parameters, summary indicators of topography-related characteristics that are computed over the investigated area. However, further useful information may be obtained through characterisation of signature topographic formations, as more direct indicators of manufacturing process behaviour and performance. In this work, laser powder bed fusion of metals is considered. An original algorithmic method is proposed to isolate relevant topographic formations and to quantify their dimensional and geometric properties, using areal topography data acquired by state-of-the-art areal topography measurement instrumentation.

A Comparison of Topography-based and Selection-based Verbal Behavior in Typically Developed Children and Developmentally Disabled Persons with Autism

PubMed Central

Vignes, Tore

2007-01-01

This study is a replication of Sundberg and Sundberg (1990) that compared topography-based verbal behavior with selection-based verbal behavior in terms of acquisition, accuracy, and testing for the emergence of a new verbal relation. Participants were three typical children and three developmentally disabled persons with autism. The study sought to determine which paradigm (topography-based or selection-based) resulted in more rapid acquisition of tacts and intraverbals, which was associated with the fewest errors, and which paradigm resulted in the emergence of the highest number of new verbal relations. The results of the study showed that the six participants performed quite differently from one another. Most importantly, the results from the person with autism contradicted previous findings favoring selection-based verbal behavior over topography-based approaches for teaching verbal behavior to low-functioning individuals. PMID:22477385

Surface topography and ultrastructural changes of mucinous carcinoma breast cells.

PubMed

Voloudakis, G E; Baltatzis, G E; Agnantis, N J; Arnogianaki, N; Misitzis, J; Voloudakis-Baltatzis, I

2007-01-01

Mucinous carcinoma of the breast (MCB) is histologically classified into 2 groups: (1) pure MCB and (2) mixed MCB. Pure MCB carries a better diagnosis than mixed MCB. This research relates to the cell surface topography and ultrastructure of the cells in the above cases and aims to find the differences between them, by means of two methods: scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For the SEM examination, it was necessary to initially culture the MCB tissues and then proceed with the usual SEM method. In contrast, for the TEM technique, MCB tissues were initially fixed followed by the classic TEM method. The authors found the topography of pure MCB cases to be without nodes. The cell membrane was smooth, with numerous pores and small ruffles that covered the entire cell. The ultrastructural appearance of the same cases was with a normal cell membrane containing abundant collagen fibers. They also had many small vesicles containing mucin as well as secretory droplets. In contrast the mixed MCB had a number of lymph nodes and their cell surface topography showed stronger changes such as microvilli, numerous blebs, ruffles and many long projections. Their ultrastructure showed very long microvilli with large cytoplasmic inclusions and extracellular mucin collections, electron-dense material vacuoles, and many important cytoplasmic organelles. An important fact is that mixed MCB also contains areas of infiltrating ductal carcinoma. These cells of the cytoplasmic organelles are clearly responsible for the synthesis, storage, and secretion of the characteristic mucin of this tumor type. Evidently, this abnormal mucin production and the abundance of secretory granules along with the long projections observed in the topographical structure might be responsible for transferring tumor cells to neighboring organs, thus being responsible for metastatic disease.

Modelling low-frequency volcanic earthquakes in a viscoelastic medium with topography

NASA Astrophysics Data System (ADS)

Jousset, P.; Neuberg, J.

2003-04-01

Magma properties are fundamental to explain the volcanic eruption style as well as the generation and propagation of seismic waves. This study focusses on rheological magma properties and their impact on low-frequency volcanic earthquakes. We investigate the effects of anelasticity and topography on the amplitudes and spectra of synthetic low-frequency earthquakes. Using a 2D finite difference scheme, we model the propagation of seismic energy initiated in a fluid-filled conduit embedded in a 2D homogeneous viscoelastic medium with topography. Topography is introduced by using a mapping procedure that stretches the computational rectangular grid into a grid which follows the topography. We model intrinsic attenuation by linear viscoelastic theory and we show that volcanic media can be approximated by a standard linear solid for seismic frequencies (i.e., above 2 Hz). Results demonstrate that attenuation modifies both amplitude and dispersive characteristics of low-frequency earthquakes. Low-frequency events are dispersive by nature; however, if attenuation is introduced, their dispersion characteristics will be altered. The topography modifies the amplitudes, depending on the position of seismographs at the surface. This study shows that we need to take into account attenuation and topography to interpret correctly observed low-frequency volcanic earthquakes. It also suggests that the rheological properties of magmas may be constrained by the analysis of low-frequency seismograms.

Inner core boundary topography explored with reflected and diffracted P waves

NASA Astrophysics Data System (ADS)

deSilva, Susini; Cormier, Vernon F.; Zheng, Yingcai

2018-03-01

The existence of topography of the inner core boundary (ICB) can affect the amplitude, phase, and coda of body waves incident on the inner core. By applying pseudospectral and boundary element methods to synthesize compressional waves interacting with the ICB, these effects are predicted and compared with waveform observations in pre-critical, critical, post-critical, and diffraction ranges of the PKiKP wave reflected from the ICB. These data sample overlapping regions of the inner core beneath the circum-Pacific belt and the Eurasian, North American, and Australian continents, but exclude large areas beneath the Pacific and Indian Oceans and the poles. In the pre-critical range, PKiKP waveforms require an upper bound of 2 km at 1-20 km wavelength for any ICB topography. Higher topography sharply reduces PKiKP amplitude and produces time-extended coda not observed in PKiKP waveforms. The existence of topography of this scale smooths over minima and zeros in the pre-critical ICB reflection coefficient predicted from standard earth models. In the range surrounding critical incidence (108-130 °), this upper bound of topography does not strongly affect the amplitude and waveform behavior of PKIKP + PKiKP at 1.5 Hz, which is relatively insensitive to 10-20 km wavelength topography height approaching 5 km. These data, however, have a strong overlap in the regions of the ICB sampled by pre-critical PKiKP that require a 2 km upper bound to topography height. In the diffracted range (>152°), topography as high as 5 km attenuates the peak amplitudes of PKIKP and PKPCdiff by similar amounts, leaving the PKPCdiff/PKIKP amplitude ratio unchanged from that predicted by a smooth ICB. The observed decay of PKPCdiff into the inner core shadow and the PKIKP-PKPCdiff differential travel time are consistent with a flattening of the outer core P velocity gradient near the ICB and iron enrichment at the bottom of the outer core.

A scanning radar altimeter for mapping continental topography

NASA Technical Reports Server (NTRS)

Dixon, T. H.

1986-01-01

Topographic information constitutes a fundamental data set for the Earth sciences. In the geological and geophysical sciences, topography combined with gravitational information provides an important constraint on the structure and rheologic properties of the crust and lithosphere. Detailed topography data can also be used to map offsets associated with faulting and to reveal the effects of tectonic deformation. In the polar regions, elevation data form a crucial but as yet largely unavailable resource for studying ice sheet mass balance and ice flow dynamics. The vast Antarctic ice sheet is the largest fresh water reservoir on Earth and is an important influence on ocean circulation and global climate. However, our knowledge of its stability is so limited that we cannot even specify whether the Antarctic ice sheet is growing or shrinking. It is clear that there is need for high quality global topography data. A summary of potential applications with their resolution requirements is shown.

Implications of MOLA Global Roughness, Statistics, and Topography

NASA Technical Reports Server (NTRS)

Aharonson, O.; Zuber, M. T.; Neumann, G. A.

1999-01-01

New insights are emerging as the ongoing high-quality measurements of the Martian surface topography by Mars Orbiter Laser Altimeter (MOLA) on board the Mars Global Surveyor (MGS) spacecraft increase in coverage, resolution, and diversity. For the first time, a global characterization of the statistical properties of topography is possible. The data were collected during the aerobreaking hiatus, science phasing, and mapping orbits of MGS, and have a resolution of 300-400 m along track, a range resolution of 37.5 cm, a range precision of 1-10 m for surface slopes up to 30 deg., and an absolute accuracy of topography of 13 m. The spacecraft's orbit inclination dictates that nadir observations have latitude coverage of about 87.1S to 87.1N; the addition of observations obtained during a period of off-nadir pointing over the north pole extended coverage to 90N. Additional information is contained in the original extended abstract.

Topography of the overriding plate during progressive subduction: A dynamic model to explain forearc subsidence

NASA Astrophysics Data System (ADS)

Chen, Z.; Schellart, W. P.; Duarte, J. C.; Strak, V.

2017-12-01

Topography that forms at the free top surface of the lithosphere contains important information about the dynamics of the tectonic plates and the sub-lithospheric mantle. Investigating topography around subduction zones can provide quantitative and conceptual insights into the interaction between the plates, the slabs, mantle flow, and the associated stresses. To achieve this, geodynamic modelling can be an effective tool. In this study, we used techniques of stereoscopic photogrammetry and Particle Image Velocimetry to monitor simultaneously the topography of the overriding plate and the velocity field of the subduction-induced mantle flow occurring in the mantle wedge. Model results show that the overriding plate topography is characterized by an area of forearc topographic subsidence, with a magnitude scaling to 1.44-3.97 km in nature, and a transient local topographic high located between the forearc depression and the trench. These topographic features rapidly develop during the slab sinking phase and gradually decrease during the slab rollback phase. We propose that these topographic transient features predominantly result from the variation of the vertical component of the trench suction along the subduction zone interface, which is minimum near the trench and maximum near the tip of the mantle wedge and is caused by the gradual slab steepening during the initial transient slab sinking phase. The downward mantle flow in the nose of the mantle wedge plays a minor role in the formation of the forearc subsidence. Our findings provide a new mechanism for the formation of forearc topographic subsidence, which has been commonly observed at natural subduction zones.

EAARL Topography-Sagamore Hill National Historic Site

USGS Publications Warehouse

Brock, John C.; Wright, C. Wayne; Nayegandhi, Amar; Patterson, Matt; Travers, Laurinda J.

2007-01-01

This Web site contains lidar-derived bare earth (BE) and first return (FR) topography maps and GIS files for the Sagamore Hill National Historic Site. These lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, Florida, the National Park Service (NPS), Northeast Coastal and Barrier Network, Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to costal resource managers.

Triangular Quantum Loop Topography for Machine Learning

NASA Astrophysics Data System (ADS)

Zhang, Yi; Kim, Eun-Ah

Despite rapidly growing interest in harnessing machine learning in the study of quantum many-body systems there has been little success in training neural networks to identify topological phases. The key challenge is in efficiently extracting essential information from the many-body Hamiltonian or wave function and turning the information into an image that can be fed into a neural network. When targeting topological phases, this task becomes particularly challenging as topological phases are defined in terms of non-local properties. Here we introduce triangular quantum loop (TQL) topography: a procedure of constructing a multi-dimensional image from the ''sample'' Hamiltonian or wave function using two-point functions that form triangles. Feeding the TQL topography to a fully-connected neural network with a single hidden layer, we demonstrate that the architecture can be effectively trained to distinguish Chern insulator and fractional Chern insulator from trivial insulators with high fidelity. Given the versatility of the TQL topography procedure that can handle different lattice geometries, disorder, interaction and even degeneracy our work paves the route towards powerful applications of machine learning in the study of topological quantum matters.

An Improved 360 Degree and Order Model of Venus Topography

NASA Technical Reports Server (NTRS)

Rappaport, Nicole J.; Konopliv, Alex S.; Kucinskas, Algis B.; Ford, Peter G.

1999-01-01

We present an improved 360 degree and order spherical harmonic solution for Venus' topography. The new model uses the most recent set of Venus altimetry data with spacecraft positions derived from a recent high resolution gravity model. Geometric analysis indicates that the offset between the center of mass and center of figure of Venus is about 10 times smaller than that for the Earth, the Moon, or Mars. Statistical analyses confirm that the RMS topography follows a power law over the central part of the spectrum. Compared to the previous topography model, the new model is more highly correlated with Venus' harmonic gravity field.

The Role of the Primary School Head.

ERIC Educational Resources Information Center

Davies, Lester

1987-01-01

This study uses Henry Mintzberg's structural observation method to examine British primary school head teachers' work patterns and determine the nature of their role. Head teachers' days were characterized by brevity, variety, and fragmentation similar to those discussed in findings of other empirical managerial studies. Leadership roles stressed…

Higher similarity in beta topography between tasks than subjects.

PubMed

Basile, Luis F H; Sato, João R; Pasquini, Henrique A; Velasques, Bruna; Ribeiro, Pedro; Anghinah, Renato

2018-05-01

We have recently provided evidence for highly idiosyncratic topographic distributions of beta oscillations (as well as slow potentials) across individuals. More recently, by emphasizing the analysis of similarity instead of differences across tasks, we concluded that differences between an attention task and quiet resting may be negligible or at least unsystematic across subjects. Due to the possibility that individual differences could be due to noise in a wide sense or some inherent instability of beta activity, we designed a replication study to explicitly test whether pairs of individuals matched for head size and shape would still present less similar beta topography than each individual between sessions or tasks. We used independent component analysis (ICA) for an exhaustive decomposition of beta activity in a visual attention task and in quiet resting, recorded by 256-channel EEG in 20 subjects, on two separate days. We evaluated whether each ICA component obtained in one task and in one given individual could be explained by a linear regression model based on the topographic patterns of the complementary task (correlation between one component with a linear combination of components from complementary conditions), of the same task in a second session and of a matched individual. Results again showed a high topographic similarity between conditions, as previously seen between reasoning and simple visual attention beta correlates. From an overall number of 16 components representing brain activity obtained for the tasks (out of 60 originally computed where the remaining were considered noise), over 92% could satisfactorily be explained by the complementary task. Although the similarity between sessions was significantly smaller than between tasks on each day, the similarity between sessions was statistically higher than that between subjects in a highly significant way. We discuss the possible biases of group spatial averaging and the emphasis on differences

Interferometer for measuring dynamic corneal topography

NASA Astrophysics Data System (ADS)

Micali, Jason Daniel

The cornea is the anterior most surface of the eye and plays a critical role in vision. A thin fluid layer, the tear film, coats the outer surface of the cornea and serves to protect, nourish, and lubricate the cornea. At the same time, the tear film is responsible for creating a smooth continuous surface where the majority of refraction takes place in the eye. A significant component of vision quality is determined by the shape of the cornea and stability of the tear film. It is desirable to possess an instrument that can measure the corneal shape and tear film surface with the same accuracy and resolution that is currently performed on common optical elements. A dual interferometer system for measuring the dynamic corneal topography is designed, built, and verified. The completed system is validated by testing on human subjects. The system consists of two co-aligned polarization splitting Twyman-Green interferometers designed to measure phase instantaneously. The primary interferometer measures the surface of the tear film while the secondary interferometer simultaneously tracks the absolute position of the cornea. Eye motion, ocular variation, and a dynamic tear film surface will result in a non-null configuration of the surface with respect to the interferometer system. A non-null test results in significant interferometer induced errors that add to the measured phase. New algorithms are developed to recover the absolute surface topography of the tear film and corneal surface from the simultaneous interferometer measurements. The results are high-resolution and high-accuracy surface topography measurements of the in vivo cornea that are captured at standard camera frame rates. This dissertation will cover the development and construction of an interferometer system for measuring the dynamic corneal topography of the human eye. The discussion starts with the completion of an interferometer for measuring the tear film. The tear film interferometer is part of an

Venus gravity anomalies and their correlations with topography

NASA Technical Reports Server (NTRS)

Sjogren, W. L.; Bills, B. G.; Birkeland, P. W.; Esposito, P. B.; Konopliv, A. R.; Mottinger, N. A.; Ritke, S. J.; Phillips, R. J.

1983-01-01

This report provides a summary of the high-resolution gravity data obtained from the Pioneer Venus Orbiter radio tracking data. Gravity maps, covering a 70 deg latitude band through 360 deg of longitude, are displayed as line-of-sight and vertical gravity. Topography converted to gravity and Bouguer gravity maps are also shown in both systems. Topography to gravity ratios are made over several regions of the planet. There are markedly different ratios for the Aphrodite area as compared to the Beta and Atla areas.

Heading and head injuries in soccer.

PubMed

Kirkendall, D T; Jordan, S E; Garrett, W E

2001-01-01

In the world of sports, soccer is unique because of the purposeful use of the unprotected head for controlling and advancing the ball. This skill obviously places the player at risk of head injury and the game does carry some risk. Head injury can be a result of contact of the head with another head (or other body parts), ground, goal post, other unknown objects or even the ball. Such impacts can lead to contusions, fractures, eye injuries, concussions or even, in rare cases, death. Coaches, players, parents and physicians are rightly concerned about the risk of head injury in soccer. Current research shows that selected soccer players have some degree of cognitive dysfunction. It is important to determine the reasons behind such deficits. Purposeful heading has been blamed, but a closer look at the studies that focus on heading has revealed methodological concerns that question the validity of blaming purposeful heading of the ball. The player's history and age (did they play when the ball was leather and could absorb significant amounts of water), alcohol intake, drug intake, learning disabilities, concussion definition and control group use/composition are all factors that cloud the ability to blame purposeful heading. What does seem clear is that a player's history of concussive episodes is a more likely explanation for cognitive deficits. While it is likely that the subconcussive impact of purposeful heading is a doubtful factor in the noted deficits, it is unknown whether multiple subconcussive impacts might have some lingering effects. In addition, it is unknown whether the noted deficits have any affect on daily life. Proper instruction in the technique is critical because if the ball contacts an unprepared head (as in accidental head-ball contacts), the potential for serious injury is possible. To further our understanding of the relationship of heading, head injury and cognitive deficits, we need to: learn more about the actual impact of a ball on the

Alcohol consumption patterns among Mexican American mothers and among children from single- and dual-headed households: findings from HHANES 1982-84.

PubMed Central

Stroup-Benham, C A; Treviño, F M; Treviño, D B

1990-01-01

Data from the southwestern United States sample of the Hispanic Health and Nutrition Examination Survey were employed to compare the patterns of alcohol use among Mexican American mothers and children in female-headed households with use patterns among mothers and children in couple-headed households. Single female heads of household drank more alcoholic beverages on more days than females from dual-headed households. As a whole, the children of single heads of household still living at home did not demonstrate significantly different drinking patterns from their dual-headed household counterparts. While male children of single-headed households drank more days and total drinks than their dual-headed household counterparts, female children of dual-headed households drank more days and total drinks than female children from single-headed households. PMID:9187580

Dust-Mantled Topography near Zephyria Tholus

NASA Image and Video Library

2010-03-31

This image captured by NASA Mars Reconnaissance Orbiter covers some high-standing topography just outside the rim of an impact crater about 30 kilometers 19 miles in diameter near a Martian hill named Zephyria Tholus.

Leveraging High Resolution Topography for Education and Outreach: Updates to OpenTopography to make EarthScope and Other Lidar Datasets more Prominent in Geoscience Education

NASA Astrophysics Data System (ADS)

Kleber, E.; Crosby, C. J.; Arrowsmith, R.; Robinson, S.; Haddad, D. E.

2013-12-01

The use of Light Detection and Ranging (lidar) derived topography has become an indispensable tool in Earth science research. The collection of high-resolution lidar topography from an airborne or terrestrial platform allows landscapes and landforms to be represented at sub-meter resolution and in three dimensions. In addition to its high value for scientific research, lidar derived topography has tremendous potential as a tool for Earth science education. Recent science education initiatives and a community call for access to research-level data make the time ripe to expose lidar data and derived data products as a teaching tool. High resolution topographic data fosters several Disciplinary Core Ideas (DCIs) of the Next Generation Science Standards (NGS, 2013), presents respective Big Ideas of the new community-driven Earth Science Literacy Initiative (ESLI, 2009), teaches to a number National Science Education Standards (NSES, 1996), and Benchmarks for Science Literacy (AAAS, 1993) for science education for undergraduate physical and environmental earth science classes. The spatial context of lidar data complements concepts like visualization, place-based learning, inquiry based teaching and active learning essential to teaching in the geosciences. As official host to EarthScope lidar datasets for tectonically active areas in the western United States, the NSF-funded OpenTopography facility provides user-friendly access to a wealth of data that is easily incorporated into Earth science educational materials. OpenTopography (www.opentopography.org), in collaboration with EarthScope, has developed education and outreach activities to foster teacher, student and researcher utilization of lidar data. These educational resources use lidar data coupled with free tools such as Google Earth to provide a means for students and the interested public to visualize and explore Earth's surface in an interactive manner not possible with most other remotely sensed imagery. The

Retest reliability of individual p3 topography assessed by high density electroencephalography.

PubMed

Vázquez-Marrufo, Manuel; González-Rosa, Javier J; Galvao-Carmona, Alejandro; Hidalgo-Muñoz, Antonio; Borges, Mónica; Peña, Juan Luis Ruiz; Izquierdo, Guillermo

2013-01-01

Some controversy remains about the potential applicability of cognitive potentials for evaluating the cerebral activity associated with cognitive capacity. A fundamental requirement is that these neurophysiological parameters show a high level of stability over time. Previous studies have shown that the reliability of diverse parameters of the P3 component (latency and amplitude) ranges between moderate and high. However, few studies have paid attention to the retest reliability of the P3 topography in groups or individuals. Considering that changes in P3 topography have been related to different pathologies and healthy aging, the main objective of this article was to evaluate in a longitudinal study (two sessions) the reliability of P3 topography in a group and at the individual level. The correlation between sessions for P3 topography in the grand average of groups was high (r = 0.977, p<0.001). The within-subject correlation values ranged from 0.626 to 0.981 (mean: 0.888). In the between-subjects topography comparisons, the correlation was always lower for comparisons between different subjects than for within-subjects correlations in the first session but not in the second session. The present study shows that P3 topography is highly reliable for group analysis (comprising the same subjects) in different sessions. The results also confirmed that retest reliability for individual P3 maps is suitable for follow-up studies for a particular subject. Moreover, P3 topography appears to be a specific marker considering that the between-subjects correlations were lower than the within-subject correlations. However, P3 topography appears more similar between subjects in the second session, demonstrating that is modulated by experience. Possible clinical applications of all these results are discussed.

Variability in Puff Topography and Exhaled CO in Waterpipe Tobacco Smoking.

PubMed

Kim, Hyoshin; Brinkman, Marielle C; Sharma, Eva; Gordon, Sydney M; Clark, Pamela I

2016-10-01

We examined intra-individual variability in puff topography and CO measures collected during laboratory waterpipe (WP) tobacco smoking using a research-grade waterpipe (RWP). WP smoking topography and exhaled CO measures were obtained from 10 established WP smokers in a single-blind, crossover design. Using a previously validated RWP, each participant smoked "Two Apples" WP tobacco ad libitum with a single quick-light charcoal to satiation in 3 laboratory sessions spaced at least one week apart. To examine the intra-individual variability, the intraclass correlation coefficient ( ρ ) for topography and CO measures were estimated. Results: The majority of the topography and CO measures were stable. Most stable were puff frequency ( ρ = 0.88), number of puffs ( ρ = 0.86), and puff duration (ρ = 0.80). Less stable were peak flow ( ρ = 0.57) and total puff volume ( ρ = 0.52). The results provide the first set of empirical evidence that most topography and CO measurements collected using the RWP from a single laboratory smoking session are stable such that they can be representative of a smoker's puffing behaviors and reproducible among 3 sessions spread equally across 3 weeks.

Basal Topography of the South Polar Layered Deposits

NASA Astrophysics Data System (ADS)

Davies, C. W.; Murray, B. C.; Byrne, S.

2004-12-01

The ice inferred to comprise the south polar layered deposits (SPLD) represents a significant fraction of the total water reservoir of the planet. The basal topography of these deposits is currently unconstrained but may be expected to contain considerable relief based on the heavily cratered nature of the surrounding terrain. In this work we report on our efforts to characterize the overall nature of this basal topography and in so doing better constrain the volume of this important volatile reservoir. Our approach has been to measure elevations at the periphery of the SPLD (defined by [1]) and use various interpolation techniques to estimate the basal topography. We used 1300 control points from the edges and areas surrounding the SPLD and included extensive control points from within the Chasmae and other features to fit a surface beneath the SPLD. No assumptions were made about any lithospheric flexure, nor did the results suggest that possibility. We first tested a variety of surface interpolation routines on a comparable area of cratered terrain immediately adjacent to the SPLD, using the same spatial distribution of 1300 height control points as we used for the SPLD itself, and found that the topography was broadly reproducible (ignoring craters) to within a few hundred meters. The SPLD basal topography we derive can be subtracted from the current spatial topography to produce isopach maps of the layered deposits. All interpolation methods we tested (within the ArcMap 8.3) indicate a lower total SPLD volume than that previous published [Smith et al., 2001]. Our best estimate for the SPLD volume is ~1 million km3, with a formal error in volume of ~5%, corresponding to an average thickness of ~950 meters. In comparison, [2] estimated this volume to be ~1.2-1.7 million km3. The Prometheus impact basin is present as a rimmed depression, consistent with the inference by [3]. More unexpected is the presence of a broad ridge underlying nearly the entire eastern

Dual Use of Cigarettes, Little Cigars, Cigarillos, and Large Cigars: Smoking Topography and Toxicant Exposure

PubMed Central

Pickworth, Wallace B.; Rosenberry, Zachary R.; O’Grady, Kevin E.; Koszowski, Bartosz

2017-01-01

Objective Smoking topography variables and toxicant exposure (plasma nicotine and exhaled CO) were examined in 3 groups of study participants that smoked both cigarettes and either filtered little cigars (Winchester), cigarillos (Black & Mild), or large cigars (Phillies Blunt). Methods Laboratory ad lib smoking of the cigar products was collected with a smoking puff analyzer; plasma levels of nicotine and exhaled CO were collected before and after smoking. Results Although there were no statistically significant differences in demographic and cigarette smoking topography among the groups, there were significant differences in how the different cigar products were smoked. Plasma nicotine boost was similar after all products but exhaled CO was greater after the cigarillo and large cigar than the little cigar. Some of the differences were due to the differences in article size but other differences were apparent even after adjustment for the amount of tobacco burned or the mouth intake (puff volume). Conclusions The topography findings of differences among products challenge the practice of grouping cigars as a single entity in surveys, regulatory decisions, and discussions of toxicant exposure. The results add to the discussion of distinctions among products in the scientific assessment of public health risk and regulatory decisions. PMID:28966952

On the ratio of dynamic topography and gravity anomalies in a dynamic Earth

NASA Astrophysics Data System (ADS)

Colli, L.; Ghelichkhan, S.; Bunge, H. P.

2016-12-01

Growing evidence from a variety of geologic indicators points to significant topography maintained convectively by viscous stresses in the mantle. However, while gravity is sensitive to dynamically supported topography, there are only small free-air gravity anomalies (<30 mGal) associated with Earth's long-wavelength topography. This has been used to suggest that surface heights computed assuming a complete isostatic equilibrium provide a good approximation to observed topography. Here we show that the apparent paradox is resolved by the well-established formalism of global, self-gravitating, viscously stratified Earth models. The models predict a complex relation between dynamic topography, mass, and gravity anomalies that is not summarized by a constant admittance—i.e., ratio of gravity anomalies to surface deflections—as one would infer from analytic flow solutions formulated in a half-space.

SRTM Anaglyph: Inverted Topography, Patagonia, Argentina

NASA Image and Video Library

2000-07-20

This anaglyph, from NASA Shuttle Radar Topography Mission, shows Meseta de Somuncura, a broad plateau capped by basalt. Near its western edge is evidence of multiple volcanic events. 3D glasses are necessary to view this image.

Coupled influences of topography and wind on wildland fire behaviour

Treesearch

Rodman Linn; Judith Winterkamp; Carleton Edminster; Jonah J. Colman; William S. Smith

2007-01-01

Ten simulations were performed with the HIGRAD/FIRETEC wildfire behaviour model in order to explore its utility in studying wildfire behaviour in inhomogeneous topography. The goal of these simulations is to explore the potential extent of the coupling between the fire, atmosphere, and topography. The ten simulations described in this paper include five different...

Sound propagation over uneven ground and irregular topography

NASA Technical Reports Server (NTRS)

Berthelot, Yves H.; Pierce, Allan D.; Kearns, James A.; Zhou, Ji-Xun

1988-01-01

Theoretical, computational, and experimental techniques were developed for predicting the effects of irregular topography on long range sound propagation in the atmosphere. Irregular topography is understood to imply a ground surface that: (1) is not idealizable as being perfectly flat, or (2) that is not idealizable as having a constant specific acoustic impedance. The focus is on circumstances where the propagation is similar to what might be expected for noise from low altitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence.

Sound propagation over uneven ground and irregular topography

NASA Technical Reports Server (NTRS)

Kearns, J. A.; Pierce, A. D.; Main, G. L.

1986-01-01

Theoretical, computational, and experimental techniques for predicting the effects of irregular topography on long range sound propagation in the atmosphere was developed. Irregular topography here is understood to imply a ground surface that is not idealized as being perfectly flat or that is not idealized as having a constant specific acoustic impedance. The interest focuses on circumstances where the propagation is similar to what might be expected for noise from low altitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence.

Surface topography analysis and performance on post-CMP images (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lee, Jusang; Bello, Abner F.; Kakita, Shinichiro; Pieniazek, Nicholas; Johnson, Timothy A.

2017-03-01

Surface topography on post-CMP processing can be measured with white light interference microscopy to determine the planarity. Results are used to avoid under or over polishing and to decrease dishing. The numerical output of the surface topography is the RMS (root-mean-square) of the height. Beyond RMS, the topography image is visually examined and not further quantified. Subjective comparisons of the height maps are used to determine optimum CMP process conditions. While visual comparison of height maps can determine excursions, it's only through manual inspection of the images. In this work we describe methods of quantifying post-CMP surface topography characteristics that are used in other technical fields such as geography and facial-recognition. The topography image is divided into small surface patches of 7x7 pixels. Each surface patch is fitted to an analytic surface equation, in this case a third order polynomial, from which the gradient, directional derivatives, and other characteristics are calculated. Based on the characteristics, the surface patch is labeled as peak, ridge, flat, saddle, ravine, pit or hillside. The number of each label and thus the associated histogram is then used as a quantified characteristic of the surface topography, and could be used as a parameter for SPC (statistical process control) charting. In addition, the gradient for each surface patch is calculated, so the average, maximum, and other characteristics of the gradient distribution can be used for SPC. Repeatability measurements indicate high confidence where individual labels can be lower than 2% relative standard deviation. When the histogram is considered, an associated chi-squared value can be defined from which to compare other measurements. The chi-squared value of the histogram is a very sensitive and quantifiable parameter to determine the within wafer and wafer-to-wafer topography non-uniformity. As for the gradient histogram distribution, the chi-squared could

The effect of asteroid topography on surface ablation deflection

NASA Astrophysics Data System (ADS)

McMahon, Jay W.; Scheeres, Daniel J.

2017-02-01

Ablation techniques for deflecting hazardous asteroids deposit energy into the asteroid's surface, causing an effective thrust on the asteroid as the ablating material leaves normal to the surface. Although it has long been recognized that surface topography plays an important role in determining the deflection capabilities, most studies to date have ignored this aspect of the model. This paper focuses on understanding the topography for real asteroid shapes, and how this topography can change the deflection performance of an ablation technique. The near Earth asteroids Golevka, Bennu, and Itokawa are used as the basis for this study, as all three have high-resolution shape models available. This paper shows that naive targeting of an ablation method without accounting for the surface topography can lower the deflection performance by up to 20% in the cases studied in terms of the amount of acceleration applied in the desired direction. If the ablation thrust level is assumed to be 100 N, as used elsewhere in the literature, this misapplication of thrust translates to tens of kilometers per year in decreased semimajor axis change. However, if the ablation method can freely target any visible point on the surface of the asteroid, almost all of this performance can be recovered.

River bathymetry estimation based on the floodplains topography.

NASA Astrophysics Data System (ADS)

Bureš, Luděk; Máca, Petr; Roub, Radek; Pech, Pavel; Hejduk, Tomáš; Novák, Pavel

2017-04-01

Topographic model including River bathymetry (bed topography) is required for hydrodynamic simulation, water quality modelling, flood inundation mapping, sediment transport, ecological and geomorphologic assessments. The most common way to create the river bathymetry is to use of the spatial interpolation of discrete points or cross sections data. The quality of the generated bathymetry is dependent on the quality of the measurements, on the used technology and on the size of input dataset. Extensive measurements are often time consuming and expensive. Other option for creating of the river bathymetry is to use the methods of mathematical modelling. In the presented contribution we created the river bathymetry model. Model is based on the analytical curves. The curves are bent into shape of the cross sections. For the best description of the river bathymetry we need to know the values of the model parameters. For finding these parameters we use of the global optimization methods. The global optimization schemes is based on heuristics inspired by the natural processes. We use new type of DE (differential evolution) for finding the solutions of inverse problems, related to the parameters of mathematical model of river bed surfaces. The presented analysis discuss the dependence of model parameters on the selected characteristics. Selected characteristics are: (1) Topographic characteristics (slope and curvature in the left and right floodplains) determined on the base of DTM 5G (digital terrain model). (2) Optimization scheme. (3) Type of used analytical curves. The novel approach is applied on the three parts of Vltava river in Czech Republic. Each part of the river is described on the base of the point field. The point fields was measured with ADCP probe River surveyor M9. This work was supported by the Technology Agency of the Czech Republic, programme Alpha (project TA04020042 - New technologies bathymetry of rivers and reservoirs to determine their storage

Allometric scaling of infraorbital surface topography in Homo.

PubMed

Maddux, Scott D; Franciscus, Robert G

2009-02-01

Infraorbital morphology is often included in phylogenetic and functional analyses of Homo. The inclusion of distinct infraorbital configurations, such as the "canine fossa" in Homo sapiens or the "inflated" maxilla in Neandertals, is generally based on either descriptive or qualitative assessments of this morphology, or simple linear chord and subtense measurements. However, the complex curvilinear surface of the infraorbital region has proven difficult to quantify through these traditional methods. In this study, we assess infraorbital shape and its potential allometric scaling in fossil Homo (n=18) and recent humans (n=110) with a geometric morphometric method well-suited for quantifying complex surface topographies. Our results indicate that important aspects of infraorbital shape are correlated with overall infraorbital size across Homo. Specifically, individuals with larger infraorbital areas tend to exhibit relatively flatter infraorbital surface topographies, taller and narrower infraorbital areas, sloped inferior orbital rims, anteroinferiorly oriented maxillary body facies, posteroinferiorly oriented maxillary processes of the zygomatic, and non-everted lateral nasal margins. In contrast, individuals with smaller infraorbital regions generally exhibit relatively depressed surface topographies, shorter and wider infraorbital areas, projecting inferior orbital rims, posteroinferiorly oriented maxillary body facies, anteroinferiorly oriented maxillary processes, and everted lateral nasal margins. These contrasts form a continuum and only appear dichotomized at the ends of the infraorbital size spectrum. In light of these results, we question the utility of incorporating traditionally polarized infraorbital morphologies in phylogenetic and functional analyses without due consideration of continuous infraorbital and facial size variation in Homo. We conclude that the essentially flat infraorbital surface topography of Neandertals is not unique and can be

Geoid Anomalies and Dynamic Topography from Time Dependent, Spherical Axisymmetric Mantle Convection

NASA Technical Reports Server (NTRS)

Kiefer, Walter S.; Kellogg, Louise H.

1998-01-01

Geoid anomalies and dynamic topography are two important diagnostics of mantle convection. We present geoid and topography results for several time-dependent convection models in spherical axisymmetric geometry for Rayleigh numbers between 10(exp 6) and 10(exp 7) with depth-dependent viscosity and mixtures of bottom and internal heating. The models are strongly chaotic, with boundary layer instabilities erupting out of both thermal boundary layers. In some instances, instabilities from one boundary layer influence the development of instabilities in the other boundary layer. Such coupling between events at the top and bottom of the mantle has been suggested to play a role in a mid-Cretaceous episode of enhanced volcanism in the Pacific. These boundary layer instabilities produce large temporal variations in the geoid anomalies and dynamic nd to the topography associated with the convection. The amplitudes of these fluctuations depend on the detailed model parameter,.% it of this but fluctuations of 30-50% relative to the time-averaged geoid and topography are common. The convective planform is strongly sensitive to the specific initial conditions. Convection cells with larger aspect ratio tend to have larger fractional fluctuations in their geoid and topography amplitudes, because boundary layer instabilities have more time to develop in long cells. In some instances, we observe low-amplitude topographic highs adjacent to the topographic lows produced by cold downwellings. We discuss applications of these results to several situations, including the temporal variability of m basis. hotspots such as Hawaii, the topography of subduction zone outer rises, and the topography of coronae on Venus.

ATM Coastal Topography-Florida 2001: Western Panhandle

USGS Publications Warehouse

Yates, Xan; Nayegandhi, Amar; Brock, John C.; Sallenger, A.H.; Bonisteel, Jamie M.; Klipp, Emily S.; Wright, C. Wayne

2009-01-01

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the western Florida panhandle coastline, acquired October 2-4 and 7-10, 2001. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative scanning Lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning Lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used

ATM Coastal Topography-Florida 2001: Eastern Panhandle

USGS Publications Warehouse

Yates, Xan; Nayegandhi, Amar; Brock, John C.; Sallenger, A.H.; Bonisteel, Jamie M.; Klipp, Emily S.; Wright, C. Wayne

2009-01-01

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the eastern Florida panhandle coastline, acquired October 2, 2001. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative scanning Lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning Lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create

Long-term effects of grazing and topography on extra-radical hyphae of arbuscular mycorrhizal fungi in semi-arid grasslands.

PubMed

Ren, Haiyan; Gui, Weiyang; Bai, Yongfei; Stein, Claudia; Rodrigues, Jorge L M; Wilson, Gail W T; Cobb, Adam B; Zhang, Yingjun; Yang, Gaowen

2018-02-01

Grazing and topography have drastic effects on plant communities and soil properties. These effects are thought to influence arbuscular mycorrhizal (AM) fungi. However, the simultaneous impacts of grazing pressure (sheep ha -1 ) and topography on plant and soil factors and their relationship to the production of extra-radical AM hyphae are not well understood. Our 10-year study assessed relationships between grazing, plant species richness, aboveground plant productivity, soil nutrients, edaphic properties, and AM hyphal length density (HLD) in different topographic areas (flat or sloped). We found HLD linearly declined with increasing grazing pressure (1.5-9.0 sheep ha -1 ) in sloped areas, but HLD was greatest at moderate grazing pressure (4.5 sheep ha -1 ) in flat areas. Structural equation modeling indicates grazing reduces HLD by altering soil nutrient dynamics in sloped areas, but non-linearly influences HLD through plant community and edaphic changes in flat areas. Our findings highlight how topography influences key plant and soil factors, thus regulating the effects of grazing pressure on extra-radical hyphal production of AM fungi in grasslands. Understanding how grazing and topography influence AM fungi in semi-arid grasslands is vital, as globally, severe human population pressure and increasing demand for food aggravate the grazing intensity in grasslands.

The effect of skin surface topography and skin colouration cues on perception of male facial age, health and attractiveness.

PubMed

Fink, B; Matts, P J; Brauckmann, C; Gundlach, S

2018-04-01

Previous studies investigating the effects of skin surface topography and colouration cues on the perception of female faces reported a differential weighting for the perception of skin topography and colour evenness, where topography was a stronger visual cue for the perception of age, whereas skin colour evenness was a stronger visual cue for the perception of health. We extend these findings in a study of the effect of skin surface topography and colour evenness cues on the perceptions of facial age, health and attractiveness in males. Facial images of six men (aged 40 to 70 years), selected for co-expression of lines/wrinkles and discolouration, were manipulated digitally to create eight stimuli, namely, separate removal of these two features (a) on the forehead, (b) in the periorbital area, (c) on the cheeks and (d) across the entire face. Omnibus (within-face) pairwise combinations, including the original (unmodified) face, were presented to a total of 240 male and female judges, who selected the face they considered younger, healthier and more attractive. Significant effects were detected for facial image choice, in response to skin feature manipulation. The combined removal of skin surface topography resulted in younger age perception compared with that seen with the removal of skin colouration cues, whereas the opposite pattern was found for health preference. No difference was detected for the perception of attractiveness. These perceptual effects were seen particularly on the forehead and cheeks. Removing skin topography cues (but not discolouration) in the periorbital area resulted in higher preferences for all three attributes. Skin surface topography and colouration cues affect the perception of age, health and attractiveness in men's faces. The combined removal of these features on the forehead, cheeks and in the periorbital area results in the most positive assessments. © 2018 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

A framework for integration of scientific applications into the OpenTopography workflow

NASA Astrophysics Data System (ADS)

Nandigam, V.; Crosby, C.; Baru, C.

2012-12-01

The NSF-funded OpenTopography facility provides online access to Earth science-oriented high-resolution LIDAR topography data, online processing tools, and derivative products. The underlying cyberinfrastructure employs a multi-tier service oriented architecture that is comprised of an infrastructure tier, a processing services tier, and an application tier. The infrastructure tier consists of storage, compute resources as well as supporting databases. The services tier consists of the set of processing routines each deployed as a Web service. The applications tier provides client interfaces to the system. (e.g. Portal). We propose a "pluggable" infrastructure design that will allow new scientific algorithms and processing routines developed and maintained by the community to be integrated into the OpenTopography system so that the wider earth science community can benefit from its availability. All core components in OpenTopography are available as Web services using a customized open-source Opal toolkit. The Opal toolkit provides mechanisms to manage and track job submissions, with the help of a back-end database. It allows monitoring of job and system status by providing charting tools. All core components in OpenTopography have been developed, maintained and wrapped as Web services using Opal by OpenTopography developers. However, as the scientific community develops new processing and analysis approaches this integration approach is not scalable efficiently. Most of the new scientific applications will have their own active development teams performing regular updates, maintenance and other improvements. It would be optimal to have the application co-located where its developers can continue to actively work on it while still making it accessible within the OpenTopography workflow for processing capabilities. We will utilize a software framework for remote integration of these scientific applications into the OpenTopography system. This will be accomplished by

Hematologic, cytochemical, ultrastructural, and molecular findings of Hepatozoon-infected flat-headed cats (Prionailurus planiceps).

PubMed

Salakij, Chaleow; Salakij, Jarernsak; Narkkong, Nual-Anong; Sirinarumitr, Theerapol; Pattanarangsan, Rattapan

2008-03-01

The flat-headed cat (Prionailurus planiceps) is a small wild cat of Southeast Asia and is considered extremely endangered. Little is known about the hematologic values, blood cell morphology, or hemoparasites of this species in relation to other Felidae. The objective of this study was to report basic hematologic values and describe the light microscopic, cytochemical, and ultrastructural characteristics of blood cells in 2 wild-caught flat-headed cats. In addition, molecular analysis was done of a Hepatozoon organism found in the neutrophils of both cats. Blood samples were collected into EDTA from the cephalic vein. A CBC, manual differential count, manual reticulocyte count, cytochemical stains (Sudan black B [SBB], alpha-naphthyl acetate esterase [ANAE], and beta-glucuronidase), and scanning and transmission electron microscopy were done using standard methods. HCT was slightly lower and reticulocyte counts and red cell distribution width were higher than the expected values for other species of cats. Hepatozoon organisms were found in the cytoplasm of neutrophils in both cats, but the number of infected neutrophils was very low (1%-2%). Neutrophils stained strongly positive for SBB, but were negative for ANAE and beta-glucuronidase. Hepatozoon-infected neutrophils were negative for SBB, but focally positive for ANAE and beta-glucuronidase. By transmission electron microscopy, gamonts of Hepatozoon sp were observed in neutrophils, and rarely free in plasma. Infected neutrophils had fewer specific granules and more mitochondria compared with noninfected neutrophils. PCR products of partial 18S rRNA revealed that the isolate of Hepatozoon in the flat-headed cats was closely related to that of the frog Hepatozoon sp. These results add to our understanding of hematologic values and blood cell morphology in Hepatozoon-infected flat-headed cats as well as the molecular analysis of the Hepatozoon organism, and may be useful for the health management and evaluation of

Role of the Nucleus as a Sensor of Cell Environment Topography.

PubMed

Anselme, Karine; Wakhloo, Nayana Tusamda; Rougerie, Pablo; Pieuchot, Laurent

2018-04-01

The proper integration of biophysical cues from the cell vicinity is crucial for cells to maintain homeostasis, cooperate with other cells within the tissues, and properly fulfill their biological function. It is therefore crucial to fully understand how cells integrate these extracellular signals for tissue engineering and regenerative medicine. Topography has emerged as a prominent component of the cellular microenvironment that has pleiotropic effects on cell behavior. This progress report focuses on the recent advances in the understanding of the topography sensing mechanism with a special emphasis on the role of the nucleus. Here, recent techniques developed for monitoring the nuclear mechanics are reviewed and the impact of various topographies and their consequences on nuclear organization, gene regulation, and stem cell fate is summarized. The role of the cell nucleus as a sensor of cell-scale topography is further discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Applications of corneal topography and tomography: a review.

PubMed

Fan, Rachel; Chan, Tommy Cy; Prakash, Gaurav; Jhanji, Vishal

2018-03-01

Corneal imaging is essential for diagnosing and management of a wide variety of ocular diseases. Corneal topography is used to characterize the shape of the cornea, specifically, the anterior surface of the cornea. Most corneal topographical systems are based on Placido disc that analyse rings that are reflected off the corneal surface. The posterior corneal surface cannot be characterized using Placido disc technology. Imaging of the posterior corneal surface is useful for diagnosis of corneal ectasia. Unlike corneal topographers, tomographers generate a three-dimensional recreation of the anterior segment and provide information about the corneal thickness. Scheimpflug imaging is one of the most commonly used techniques for corneal tomography. The cross-sectional images generated by a rotating Scheimpflug camera are used to locate the anterior and posterior corneal surfaces. The clinical uses of corneal topography include, diagnosis of corneal ectasia, assessment of corneal astigmatism, and refractive surgery planning. This review will discuss the applications of corneal topography and tomography in clinical practice. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

High Resolution Global Topography of Eros from NEAR Imaging and LIDAR Data

NASA Technical Reports Server (NTRS)

Gaskell, Robert W.; Konopliv, A.; Barnouin-Jha, O.; Scheeres, D.

2006-01-01

Principal Data Products: Ensemble of L-maps from SPC, Spacecraft state, Asteroid pole and rotation. Secondary Products: Global topography model, inertia tensor, gravity. Composite high resolution topography. Three dimensional image maps.

Photogrammetric portrayal of Mars topography.

USGS Publications Warehouse

Wu, S.S.C.

1979-01-01

Special photogrammetric techniques have been developed to portray Mars topography, using Mariner and Viking imaging and nonimaging topographic information and earth-based radar data. Topography is represented by the compilation of maps at three scales: global, intermediate, and very large scale. The global map is a synthesis of topographic information obtained from Mariner 9 and earth-based radar, compiled at a scale of 1:25,000,000 with a contour interval of 1 km; it gives a broad quantitative view of the planet. At intermediate scales, Viking Orbiter photographs of various resolutions are used to compile detailed contour maps of a broad spectrum of prominent geologic features; a contour interval as small as 20 m has been obtained from very high resolution orbital photography. Imagery from the Viking lander facsimile cameras permits construction of detailed, very large scale (1:10) topographic maps of the terrain surrounding the two landers; these maps have a contour interval of 1 cm. This paper presents several new detailed topographic maps of Mars.-Author

Photogrammetric portrayal of Mars topography

NASA Technical Reports Server (NTRS)

Wu, S. S. C.

1979-01-01

Special photogrammetric techniques have been developed to portray Mars topography, using Mariner and Viking imaging and nonimaging topographic information and earth-based radar data. Topography is represented by the compilation of maps at three scales: global, intermediate, and very large scale. The global map is a synthesis of topographic information obtained from Mariner 9 and earth-based radar, compiled at a scale of 1:25,000,000 with a contour interval of 1 km; it gives a broad quantitative view of the planet. At intermediate scales, Viking Orbiter photographs of various resolutions are used to compile detailed contour maps of a broad spectrum of prominent geologic features; a contour interval as small as 20 m has been obtained from very high resolution orbital photography. Imagery from the Viking lander facsimile cameras permits construction of detailed, very large scale (1:10) topographic maps of the terrain surrounding the two landers; these maps have a contour interval of 1 cm. This paper presents several new detailed topographic maps of Mars.

Topography changes monitoring of small islands using camera drone

NASA Astrophysics Data System (ADS)

Bang, E.

2017-12-01

Drone aerial photogrammetry was conducted for monitoring topography changes of small islands in the east sea of Korea. Severe weather and sea wave is eroding the islands and sometimes cause landslide and falling rock. Due to rugged cliffs in all direction and bad accessibility, ground based survey methods are less efficient in monitoring topography changes of the whole area. Camera drones can provide digital images and movie in every corner of the islands, and drone aerial photogrammetry is powerful to get precise digital surface model (DSM) for a limited area. We have got a set of digital images to construct a textured 3D model of the project area every year since 2014. Flight height is in less than 100m from the top of those islands to get enough ground sampling distance (GSD). Most images were vertically captured with automatic flights, but we also flied drones around the islands with about 30°-45° camera angle for constructing 3D model better. Every digital image has geo-reference, but we set several ground control points (GCPs) on the islands and their coordinates were measured with RTK surveying methods to increase the absolute accuracy of the project. We constructed 3D textured model using photogrammetry tool, which generates 3D spatial information from digital images. From the polygonal model, we could get DSM with contour lines. Thematic maps such as hill shade relief map, aspect map and slope map were also processed. Those maps make us understand topography condition of the project area better. The purpose of this project is monitoring topography change of these small islands. Elevation difference map between DSMs of each year is constructed. There are two regions showing big negative difference value. By comparing constructed textured models and captured digital images around these regions, it is checked that a region have experienced real topography change. It is due to huge rock fall near the center of the east island. The size of fallen rock can be

Stress distribution and topography of Tellus Regio, Venus

NASA Technical Reports Server (NTRS)

Williams, David R.; Greeley, Ronald

1989-01-01

The Tellus Regio area of Venus represents a subset of a narrow latitude band where Pioneer Venus Orbiter (PVO) altimetry data, line-of-sight (LOS) gravity data, and Venera 15/16 radar images have all been obtained with good resolution. Tellus Regio also has a wide variety of surface morphologic features, elevations ranging up to 2.5 km, and a relatively low LOS gravity anomaly. This area was therefore chosen in order to examine the theoretical stress distributions resulting from various models of compensation of the observed topography. These surface stress distributions are then compared with the surface morphology revealed in the Venera 15/16 radar images. Conclusions drawn from these comparisons will enable constraints to be put on various tectonic parameters relevant to Tellus Regio. The stress distribution is calculated as a function of the topography, the equipotential anomaly, and the assumed model parameters. The topography data is obtained from the PVO altimetry. The equipotential anomaly is estimated from the PVO LOS gravity data. The PVO LOS gravity represents the spacecraft accelerations due to mass anomalies within the planet. These accelerations are measured at various altitudes and angles to the local vertical and therefore do not lend themselves to a straightforward conversion. A minimum variance estimator of the LOS gravity data is calculated, taking into account the various spacecraft altitudes and LOS angles and using the measured PVO topography as an a priori constraint. This results in an estimated equivalent surface mass distribution, from which the equipotential anomaly is determined.

Electronic cigarettes: abuse liability, topography and subjective effects.

PubMed

Evans, Sarah E; Hoffman, Allison C

2014-05-01

To review the available evidence evaluating the abuse liability, topography, subjective effects, craving and withdrawal suppression associated with e-cigarette use in order to identify information gaps and provide recommendations for future research. Literature searches were conducted between October 2012 and January 2014 using five electronic databases. Studies were included in this review if they were peer-reviewed scientific journal articles evaluating clinical laboratory studies, national surveys or content analyses. A total of 15 peer-reviewed articles regarding behavioural use and effects of e-cigarettes published between 2010 and 2014 were included in this review. Abuse liability studies are limited in their generalisability. Topography (consumption behaviour) studies found that, compared with traditional cigarettes, e-cigarette average puff duration was significantly longer, and e-cigarette use required stronger suction. Data on e-cigarette subjective effects (such as anxiety, restlessness, concentration, alertness and satisfaction) and withdrawal suppression are limited and inconsistent. In general, study data should be interpreted with caution, given limitations associated with comparisons of novel and usual products, as well as the possible effects associated with subjects' previous experience/inexperience with e-cigarettes. Currently, very limited information is available on abuse liability, topography and subjective effects of e-cigarettes. Opportunities to examine extended e-cigarette use in a variety of settings with experienced e-cigarette users would help to more fully assess topography as well as behavioural and subjective outcomes. In addition, assessment of 'real-world' use, including amount and timing of use and responses to use, would clarify behavioural profiles and potential adverse health effects.

Abyssal hills: Influence of topography on benthic foraminiferal assemblages

NASA Astrophysics Data System (ADS)

Stefanoudis, Paris V.; Bett, Brian J.; Gooday, Andrew J.

2016-11-01

Abyssal plains, often thought of as vast flat areas, encompass a variety of terrains including abyssal hills, features that constitute the single largest landscape type on Earth. The potential influence on deep-sea benthic faunas of mesoscale habitat complexity arising from the presence of abyssal hills is still poorly understood. To address this issue we focus on benthic foraminifera (testate protists) in the >150-μm fraction of Megacorer samples (0-1 cm layer) collected at five different sites in the area of the Porcupine Abyssal Plain Sustained Observatory (NE Atlantic, 4850 m water depth). Three sites are located on the tops of small abyssal hills (200-500 m elevation) and two on the adjacent abyssal plain. We examined benthic foraminiferal assemblage characteristics (standing stock, diversity, composition) in relation to seafloor topography (hills vs. plain). Density and rarefied diversity were not significantly different between the hills and the plain. Nevertheless, hills do support a higher species density (i.e. species per unit area), a distinct fauna, and act to increase the regional species pool. Topographically enhanced bottom-water flows that influence food availability and sediment type are suggested as the most likely mechanisms responsible for these differences. Our findings highlight the potential importance of mesoscale heterogeneity introduced by relatively modest topography in regulating abyssal foraminiferal diversity. Given the predominance of abyssal hill terrain in the global ocean, we suggest the need to include faunal data from abyssal hills in assessments of abyssal ecology.

Climate dominated topography in a tectonically active mountain range

NASA Astrophysics Data System (ADS)

Adams, B. A.; Ehlers, T. A.

2015-12-01

Tests of the interactions between tectonic and climate forcing on Earth's topography often focus on the concept of steady-state whereby processes of rock deformation and erosion are opposing and equal. However, when conditions change such as the climate or tectonic rock uplift, then surface processes act to restore the balance between rock deformation and erosion by adjusting topography. Most examples of canonical steady-state mountain ranges lie within the northern hemisphere, which underwent a radical change in the Quaternary due to the onset of widespread glaciation. The activity of glaciers changed erosion rates and topography in many of these mountain ranges, which likely violates steady-state assumptions. With new topographic analysis, and existing patterns of climate and rock uplift, we explore a mountain range previously considered to be in steady-state, the Olympic Mountains, USA. The broad spatial trend in channel steepness values suggests that the locus of high rock uplift rates is coincident with the rugged range core, in a similar position as high temperature and pressure lithologies, but not in the low lying foothills as has been previously suggested by low-temperature thermochronometry. The details of our analysis suggest the dominant topographic signal in the Olympic Mountains is a spatial, and likely temporal, variation in erosional efficiency dictated by orographic precipitation, and Pleistocene glacier ELA patterns. We demonstrate the same topographic effects are recorded in the basin hypsometries of other Cenozoic mountain ranges around the world. The significant glacial overprint on topography makes the argument of mountain range steadiness untenable in significantly glaciated settings. Furthermore, our results suggest that most glaciated Cenozoic ranges are likely still in a mode of readjustment as fluvial systems change topography and erosion rates to equilibrate with rock uplift rates.

The global topography of Mars and implications for surface evolution

NASA Technical Reports Server (NTRS)

Smith, D. E.; Zuber, M. T.; Solomon, S. C.; Phillips, R. J.; Head, J. W.; Garvin, J. B.; Banerdt, W. B.; Muhleman, D. O.; Pettengill, G. H.; Neumann, G. A.;

Effects of reinforcing preselected approximations on the topography of the rat's bar press

PubMed Central

Stokes, Patricia D.; Balsam, Peter D.

1991-01-01

The effects of different shaping approximations on the topography of the rat's bar press were investigated in two experiments. Behavior was classified into discrete components, and changes in components and their sequential organization were analyzed. Experiment 1 examined response form early in training and found that specific components reinforced during shaping were incorporated into press sequences. Experiment 2 investigated how response form changed when a shaping contingency was relaxed later in training. Two topographies were selected for reinforcement, and both appeared in the press sequences of all subjects by the end of shaping. Subsequently, all variations of bar pressing were reinforced, and neither topography was necessary to satisfy the contingency. Although the frequency of the topographies reinforced during shaping declined for 3 of 4 subjects during this phase, the most frequent press sequence for 2 rats at the end of training included both unnecessary topographies. Variability in press topographies declined when all emitted variants were reinforced. However, all subjects emitted novel response forms throughout training. The results demonstrate that specific response–reinforcer contingencies influence response form by modulating component availability and organization. PMID:16812634

Topographic Diagnosis of Craniopharyngiomas: The Accuracy of MRI Findings Observed on Conventional T1 and T2 Images.

PubMed

Prieto, R; Pascual, J M; Barrios, L

2017-11-01

The topography of craniopharyngiomas has proved fundamental in predicting the involvement of vital brain structures and the possibility of achieving a safe radical resection. Beyond the imprecise term "suprasellar," indiscriminately used for craniopharyngiomas, an accurate definition of craniopharyngioma topography should be assessed by preoperative MR imaging. The objective of this study was to investigate the MRI findings that help define craniopharyngioma topography. This study retrospectively investigated a cohort of 200 surgically treated craniopharyngiomas with their corresponding preoperative midsagittal and coronal conventional T1- and T2-weighted MR images, along with detailed descriptions of the surgical findings. Radiologic variables related to the occupation of the tumor of intracranial compartments and the distortions of anatomic structures along the sella turcica-third ventricle axis were analyzed and correlated with the definitive craniopharyngioma topography observed during the surgical procedures. A predictive model for craniopharyngioma topography was generated by multivariate analysis. Five major craniopharyngioma topographies can be defined according to the degree of hypothalamic distortion caused by the tumor: sellar-suprasellar, pseudointraventricular, secondary intraventricular, not strictly intraventricular, and strictly intraventricular. Seven key radiologic variables identified on preoperative MRI allowed a correct overall prediction of craniopharyngioma topography in 86% of cases: 1) third ventricle occupation, 2) pituitary stalk distortion, 3) relative level of the hypothalamus in relation to the tumor, 4) chiasmatic cistern occupation, 5) mammillary body angle, 6) type of chiasm distortion, and 7) tumor shape. Systematic assessment of these 7 variables on conventional preoperative T1 and T2 MRI is a useful and reliable method to ascertain individual craniopharyngioma topography. © 2017 by American Journal of Neuroradiology.

Influence of dynamic topography on landscape evolution and passive continental margin stratigraphy

NASA Astrophysics Data System (ADS)

Ding, Xuesong; Salles, Tristan; Flament, Nicolas; Rey, Patrice

2017-04-01

Quantifying the interaction between surface processes and tectonics/deep Earth processes is one important aspect of landscape evolution modelling. Both observations and results from numerical modelling indicate that dynamic topography - a surface expression of time-varying mantle convection - plays a significant role in shaping landscape through geological time. Recent research suggests that dynamic topography also has non-negligible effects on stratigraphic architecture by modifying accommodation space available for sedimentation. In addition, dynamic topography influences the sediment supply to continental margins. We use Badlands to investigate the evolution of a continental-scale landscape in response to transient dynamic uplift or subsidence, and to model the stratigraphic development on passive continental margins in response to sea-level change, thermal subsidence and dynamic topography. We consider a circularly symmetric landscape consisting of a plateau surrounded by a gently sloping continental plain and a continental margin, and a linear wave of dynamic topography. We analyze the evolution of river catchments, of longitudinal river profiles and of the χ values to evaluate the dynamic response of drainage systems to dynamic topography. We calculate the amount of cumulative erosion and deposition, and sediment flux at shoreline position, as a function of precipitation rate and erodibility coefficient. We compute the stratal stacking pattern and Wheeler diagram on vertical cross-sections at the continental margin. Our results indicate that dynamic topography 1) has a considerable influence on drainage reorganization; 2) contributes to shoreline migration and the distribution of depositional packages by modifying the accommodation space; 3) affects sediment supply to the continental margin. Transient dynamic topography contributes to the migration of drainage divides and to the migration of the mainstream in a drainage basin. The dynamic uplift

Sound propagation over uneven ground and irregular topography

NASA Technical Reports Server (NTRS)

Berthelot, Yves H.; Pierce, Allan D.; Main, Geoffrey L.; Zhou, Ji-Xun; Kearns, James A.

1988-01-01

The goal of this research is to develop theoretical, computational, and experimental techniques for predicting the effects of irregular topography on long range sound propagation in the atmosphere. Irregular topography is understood to imply a ground surface that is not idealizable as being perfectly flat or that is no idealizable as having a constant specific acoustic impedance. The focus is on circumstances where the propagation is similar to what might be expected for noise from low-altitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence.

Sound propagation over uneven ground and irregular topography

NASA Technical Reports Server (NTRS)

Pierce, A. D.; Main, G. L.; Kearns, J. A.; Benator, D. R.; Parish, J. R., Jr.

1986-01-01

The development of theoretical, computational, and experimental techniques for predicting the effects of irregular topography on long range sound propagation in the atmosphere is discussed. Irregular topography here is understood to imply a ground surface that (1) is not idealizable as being perfectly flat or (2) that is not idealizable as having a constant specific acoustic impedance. The study focuses on circumstances where the propagation is similar to what might be expected for noise from low-altitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence.

Narrow-headed garter snake (Thamnophis rufipunctatus)

USGS Publications Warehouse

Nowak, Erika M.

2006-01-01

The narrow-headed garter snake is a harmless, nonvenomous snake that is distinguished by its elongated, triangular-shaped head and the red or dark spots on its olive to tan body. Today, the narrow-headed garter snake is a species of special concern in the United States because of its decline over much of its historic range. Arizona's Oak Creek has historically contained the largest population of narrow-headed garter snakes in the United States. The U.S. Geological Survey (USGS) and the Arizona Game and Fish Department jointly funded research by USGS scientists in Oak Creek to shed light on the factors causing declining population numbers. The research resulted in better understanding of the snake's habitat needs, winter and summer range, and dietary habits. Based on the research findings, the U.S. Forest Service has developed recommendations that visitors and local residents can adopt to help slow the decline of the narrow-headed garter snake in Oak Creek.

Hospitalised and Fatal Head Injuries in Viti Levu, Fiji: Findings from an Island-Wide Trauma Registry (TRIP 4)

PubMed Central

Kool, Bridget; Raj, Naina; Wainiqolo, Iris; Kafoa, Berlin; McCaig, Eddie; Ameratunga, Shanthi

2012-01-01

Background Globally, head injury is a substantial cause of mortality and morbidity. A disproportionately greater burden is borne by low- and middle-income countries. The incidence and characteristics of fatal and hospitalised head injuries in Fiji are unknown. Methods Using prospective data from the Fiji Injury Surveillance in Hospital system, the epidemiology of fatal and hospitalised head injuries was investigated (2004–2005). Results In total, 226 hospital admissions and 50 fatalities (66% died prior to admission) with a principal diagnosis of head injury were identified (crude annual rates of 34.7 and 7.7/100,000, respectively). Males were more likely to die and be hospitalised as a result of head injury than females. The highest fatality rate was among those in the 30–44-year age group. Road traffic crashes were the leading causes of injuries resulting in death (70%), followed by ‘hit by person or object’ and falls (14% each). Among people admitted to hospital, road traffic crashes (34.5%) and falls (33.2%) were the leading causes of injury. The leading cause of head injuries in children was falls, in 15–29-year-olds road traffic crashes, and in adults aged 30–44 years or 45 years and older ‘hit by person or object’. Among the two major ethnic groups, Fijians had higher rates of falls and ‘hit by person or object’ and Indians higher rates for road traffic crashes. There were no statistically significant differences between the overall rates of head injuries or the fatal and non-fatal rates among Fijians or Indians by gender following age standardisation to the total Fijian national population. Conclusion Despite underestimating the overall burden, this study identified head injury to be a major cause of death and hospitalisation in Fiji. The predominance of males and road traffic-related injuries is consistent with studies on head injuries conducted in other low- and middle-income countries. The high fatality rate among those aged 30–44

Localized Gravity/Topography Admittances on Mars

NASA Technical Reports Server (NTRS)

McGovern, Patrick J.; Solomon, Sean C.; Smith, David E.; Zuber, Maria T.; Neumann, Gregory A.; Head, James W.

2000-01-01

Admittances from Mars Global Surveyor (MGS) gravity and topography yield estimates of lithosphere thickness on Mars: central Tharsis > 100 km, Alba Patera = 50 km, southern highlands < 20 km (but south polar cap > 50 km). Alba Patera and Elysium Rise are similar structures.

Enabling Access to High-Resolution Lidar Topography for Earth Science Research

NASA Astrophysics Data System (ADS)

Crosby, Christopher; Nandigam, Viswanath; Arrowsmith, Ramon; Baru, Chaitan

2010-05-01

High-resolution topography data acquired with lidar (light detection and ranging a.k.a. laser scanning) technology are revolutionizing the way we study the geomorphic processes acting along the Earth's surface. These data, acquired from either an airborne platform or from a tripod-mounted scanner, are emerging as a fundamental tool for research on a variety of topics ranging from earthquake hazards to ice sheet dynamics. Lidar topography data allow earth scientists to study the processes that contribute to landscape evolution at resolutions not previously possible yet essential for their appropriate representation. These datasets also have significant implications for earth science education and outreach because they provide an accurate digital representation of landforms and geologic hazards. However, along with the potential of lidar topography comes an increase in the volume and complexity of data that must be efficiently managed, archived, distributed, processed and integrated in order for them to be of use to the community. A single lidar data acquisition may generate terabytes of data in the form of point clouds, digital elevation models (DEMs), and derivative imagery. This massive volume of data is often difficult to manage and poses significant distribution challenges when trying to allow access to the data for a large scientific user community. Furthermore, the datasets can be technically challenging to work with and may require specific software and computing resources that are not readily available to many users. The U.S. National Science Foundation (NSF)-funded OpenTopography Facility (http://www.opentopography.org) is an online data access and processing system designed to address the challenges posed by lidar data, and to democratize access to these data for the scientific user community. OpenTopography provides free, online access to lidar data in a number of forms, including raw lidar point cloud data, standard DEMs, and easily accessible Google

Acquisition of an Underway CTD System for the Flow Encountering Abrupt Topography DRI

DTIC Science & Technology

2015-09-30

Acquisition of an Underway CTD System for the Flow Encountering Abrupt Topography DRI T. M. Shaun Johnston Scripps Institution of Oceanography...westward flow in the North Equatorial Current (NEC) encounters tall, steep, submarine topography and islands. During the Flow Encountering Abrupt... Topography (FLEAT) DRI, investigators will determine: • Whether appreciable energy/momentum is lost from the large-scale NEC flow to smaller scales and

Head growth and neurocognitive outcomes.

PubMed

Wright, Charlotte M; Emond, Alan

2015-06-01

There is a lack of evidence on the value of head circumference (HC) as a screening measure. We aimed to describe the incidence of head centile shifting and the relationship between extremes of head size and later neurodevelopmental problems in the Avon Longitudinal Study of Parents and Children. HC was measured routinely at 2, 9, and 18 or 24 months and by researchers at ages 4, 8, 12, and 18 months. IQ according to the Wechsler Intelligence Scale for Children was measured in research clinics at age 8 for all. Neurocognitive disorders (NCDs) were identified from chart review. There were 10 851 children with ≥2 head measurements. At each age, 2% to 3% of children had scores that were < -2 or >2 SDs below or above the mean, but for most children this was only found at 1 age. More than 15% of children showed centile shifts, but less than one-third of these were sustained at subsequent measurements. Only 0.5% showed a sustained shift beyond the normal range. Children with consistently small heads were up to 7 times more likely to have an NCD, but 85% of children with small heads had no NCDs, and 93% of children with NCDs had head SD scores within the normal range. Centile shifts within the normal range occur commonly and seem mainly to reflect measurement error. This finding makes robust assessment of the head trajectory difficult and may result in many children being investigated unnecessarily. Extreme head size is neither specific nor sensitive for detecting NCDs, suggesting that routine measurement of HC is unhelpful. Copyright © 2015 by the American Academy of Pediatrics.

Measurement of Angle Kappa Using Ultrasound Biomicroscopy and Corneal Topography

PubMed Central

Yeo, Joon Hyung; Moon, Nam Ju

2017-01-01

Purpose To introduce a new convenient and accurate method to measure the angle kappa using ultrasound biomicroscopy (UBM) and corneal topography. Methods Data from 42 eyes (13 males and 29 females) were analyzed in this study. The angle kappa was measured using Orbscan II and calculated with UBM and corneal topography. The angle kappa of the dominant eye was compared with measurements by Orbscan II. Results The mean patient age was 36.4 ± 13.8 years. The average angle kappa measured by Orbscan II was 3.98° ± 1.12°, while the average angle kappa calculated with UBM and corneal topography was 3.19° ± 1.15°. The difference in angle kappa measured by the two methods was statistically significant (p < 0.001). The two methods showed good reliability (intraclass correlation coefficient, 0.671; p < 0.001). Bland-Altman plots were used to demonstrate the agreement between the two methods. Conclusions We designed a new method using UBM and corneal topography to calculate the angle kappa. This method is convenient to use and allows for measurement of the angle kappa without an expensive device. PMID:28471103

Measurement of Angle Kappa Using Ultrasound Biomicroscopy and Corneal Topography.

PubMed

Yeo, Joon Hyung; Moon, Nam Ju; Lee, Jeong Kyu

2017-06-01

To introduce a new convenient and accurate method to measure the angle kappa using ultrasound biomicroscopy (UBM) and corneal topography. Data from 42 eyes (13 males and 29 females) were analyzed in this study. The angle kappa was measured using Orbscan II and calculated with UBM and corneal topography. The angle kappa of the dominant eye was compared with measurements by Orbscan II. The mean patient age was 36.4 ± 13.8 years. The average angle kappa measured by Orbscan II was 3.98° ± 1.12°, while the average angle kappa calculated with UBM and corneal topography was 3.19° ± 1.15°. The difference in angle kappa measured by the two methods was statistically significant (p < 0.001). The two methods showed good reliability (intraclass correlation coefficient, 0.671; p < 0.001). Bland-Altman plots were used to demonstrate the agreement between the two methods. We designed a new method using UBM and corneal topography to calculate the angle kappa. This method is convenient to use and allows for measurement of the angle kappa without an expensive device. © 2017 The Korean Ophthalmological Society

Topographies of Power: A Critical Historical Geography of Schooling in Tanzania

ERIC Educational Resources Information Center

Vavrus, Frances

2016-01-01

This article builds a case for critical historical geography in comparative education to examine how, over time, the social production of space contributes to educational disparity. It draws on Gupta and Ferguson's contrasting concepts of the "power of topography" and the "topography of power" and Lefebvre's tripartite theory…

Mediterranean summer climate and the importance of Middle-East Topography

NASA Astrophysics Data System (ADS)

Simpson, Isla; Seager, Richard; Shaw, Tiffany; Ting, Mingfang

2015-04-01

In summer, the atmospheric circulation over the Mediterranean is characterized by localized intense subsidence and low level northerlies over the central- to eastern portion of the basin. Here, simulations with the Community Atmosphere Model, version 5 are used to investigate the influence of the elevated terrain of North Africa and the Middle East on this summertime circulation. This builds on previous work that recognized a role for North African topography in localizing the Mediterranean subsidence. By flattening the two regions of elevated terrain in the model it is demonstrated that, while they both conspire to produce about 30% of the summertime subsidence, contrary to previous work, the mountains of the Middle-East dominate in this topographic contribution by far. This topography, consisting primarily of the Zagros Mountain range, alters the circulation throughout the depth of the troposphere over the Mediterranean, and further East. The model results suggest that about 20% of the Mediterranean summertime moisture deficit can be attributed to this mountain induced circulation. This topography, therefore, plays an important role in the climate of the Mediterranean and the large scale circulation over the rest of Eurasia during the summer. Further stationary wave modelling reveals that the mountain influence is produced via mechanical forcing of the flow. The greatest influence of the topography occurs when the low level incident flow is easterly, as happens during the summer, primarily due to the presence of condensational heating over Asia. During other seasons, when the low level incident flow is westerly, the influence of Middle-East topography on the Mediterranean is negligible.

Evaluating the effectiveness of low cost UAV generated topography for geomorphic change detection

NASA Astrophysics Data System (ADS)

Cook, K. L.

2014-12-01

With the recent explosion in the use and availability of unmanned aerial vehicle platforms and development of easy to use structure from motion software, UAV based photogrammetry is increasingly being adopted to produce high resolution topography for the study of surface processes. UAV systems can vary substantially in price and complexity, but the tradeoffs between these and the quality of the resulting data are not well constrained. We look at one end of this spectrum and evaluate the effectiveness of a simple low cost UAV setup for obtaining high resolution topography in a challenging field setting. Our study site is the Daan River gorge in western Taiwan, a rapidly eroding bedrock gorge that we have monitored with terrestrial Lidar since 2009. The site presents challenges for the generation and analysis of high resolution topography, including vertical gorge walls, vegetation, wide variation in surface roughness, and a complicated 3D morphology. In order to evaluate the accuracy of the UAV-derived topography, we compare it with terrestrial Lidar data collected during the same survey period. Our UAV setup combines a DJI Phantom 2 quadcopter with a 16 megapixel Canon Powershot camera for a total platform cost of less than $850. The quadcopter is flown manually, and the camera is programmed to take a photograph every 5 seconds, yielding 200-250 pictures per flight. We measured ground control points and targets for both the Lidar scans and the aerial surveys using a Leica RTK GPS with 1-2 cm accuracy. UAV derived point clouds were obtained using Agisoft Photoscan software. We conducted both Lidar and UAV surveys before and after a summer typhoon season, allowing us to evaluate the reliability of the UAV survey to detect geomorphic changes in the range of one to several meters. We find that this simple UAV setup can yield point clouds with an average accuracy on the order of 10 cm compared to the Lidar point clouds. Well-distributed and accurately located ground

Surface topography of two trematodes parasites infecting grey heron Ardea cinerea Jouyi (Aves, Ciconiiformes) in Qena, Egypt.

PubMed

Ammar, Khalaf Nour Abd El-Wahed

2015-04-01

Apharyngostrigea ardeolina and Echinoparyphium recurvatum are two important digenean parasites that were recovered from small intestine of grey heron with an infection rate (16.2%) and (8.8%) respectively. The surface topography of two species was redescribed by both light and scanning electron microscopy. Using SEM studies showed that the body surface of two trematodes were covered by contact receptors, several types of sensory tegumental papillae which may have useful function in orientation and feeding through increasing the surface area of absorption, could also play a role in sensation or in selection of the materials for ingestion by the fluke. The head collar of E. recurvatum is reniform in shape, bearing uninterrupted double row of 41 collar finger-like spines, a total including 4 end group ones on both ventral corners., tegumental spines were tongue-shaped without a terminal tip.

Nanomedicines for Inflammatory Arthritis: Head-To-Head Comparison of Glucocorticoid-Containing Polymers, Micelles and Liposomes

PubMed Central

Crielaard, Bart J.; Dusad, Anand; Lele, Subodh M.; Rijcken, Cristianne J. F.; Metselaar, Josbert M; Kostková, Hana; Etrych, Tomáš; Ulbrich, Karel; Kiessling, Fabian; Mikuls, Ted R.; Hennink, Wim E.; Storm, Gert; Lammers, Twan; Wang, Dong

2014-01-01

As an emerging research direction, nanomedicine has been increasingly utilized to treat inflammatory diseases. In this head-to-head comparison study, four established nanomedicine formulations of dexamethasone, including liposomes (L-Dex), core-crosslinked micelles (M-Dex), slow releasing polymeric prodrugs (P-Dex-slow) and fast releasing polymeric prodrugs (P-Dex-fast), were evaluated in an adjuvant-induced arthritis rat model with an equivalent dose treatment design. It was found that after a single i.v. injection, the formulations with the slower drug release kinetics (i.e. M-Dex and P-Dex-slow) maintained longer duration of therapeutic activity than those with relatively faster drug release kinetics, resulting in better joint protection. This finding will be instructional in the future development and optimization of nanomedicines for the clinical management of rheumatoid arthritis. The outcome of this study also illustrates the value of such head-to-head comparison studies in translational nanomedicine research. PMID:24341611

Fluorescence Imaging Topography Scanning System for intraoperative multimodal imaging

PubMed Central

Quang, Tri T.; Kim, Hye-Yeong; Bao, Forrest Sheng; Papay, Francis A.; Edwards, W. Barry; Liu, Yang

2017-01-01

Fluorescence imaging is a powerful technique with diverse applications in intraoperative settings. Visualization of three dimensional (3D) structures and depth assessment of lesions, however, are oftentimes limited in planar fluorescence imaging systems. In this study, a novel Fluorescence Imaging Topography Scanning (FITS) system has been developed, which offers color reflectance imaging, fluorescence imaging and surface topography scanning capabilities. The system is compact and portable, and thus suitable for deployment in the operating room without disturbing the surgical flow. For system performance, parameters including near infrared fluorescence detection limit, contrast transfer functions and topography depth resolution were characterized. The developed system was tested in chicken tissues ex vivo with simulated tumors for intraoperative imaging. We subsequently conducted in vivo multimodal imaging of sentinel lymph nodes in mice using FITS and PET/CT. The PET/CT/optical multimodal images were co-registered and conveniently presented to users to guide surgeries. Our results show that the developed system can facilitate multimodal intraoperative imaging. PMID:28437441

Anomalous topography on the continental shelf around Hudson Canyon

USGS Publications Warehouse

Knebel, H.J.

1979-01-01

Recent seismic-reflection data show that the topography on the Continental Shelf around Hudson Canyon is composed of a series of depressions having variable spacings (< 100 m to 2 km), depths (1-10 m), outlines, and bottom configurations that give the sea floor an anomalous "jagged" appearance in profile. The acoustic and sedimentary characteristics, the proximity to relict shores, and the areal distribution indicate that this rough topography is an erosional surface formed on Upper Pleistocene silty sands about 13,000 to 15,000 years ago by processes related to Hudson Canyon. The pronounced southward extension of the surface, in particular, may reflect a former increase in the longshore-current erosion capacity caused by the loss of sediments over the canyon. Modern erosion or nondeposition of sediments has prevented the ubiquitous sand sheet on the Middle Atlantic shelf from covering the surface. The "anomalous" topography may, in fact, be characteristic of areas near other submarine canyons that interrupt or have interrupted the longshore drift of sediments. ?? 1979.

Age and Prematurity of the Alps Derived from Topography

NASA Astrophysics Data System (ADS)

Hergarten, S.; Wagner, T.; Stüwe, K.

2010-09-01

The European Alps are one of the best studied mountain ranges on Earth, but yet the age of their topography is almost unknown. Even their relative stage of evolution is unclear: Are the Alps still growing, in a steady state or already decaying, and is there a significant difference between Western and Eastern Alps? Using a new geomorphic parameter we analyze the topography of the Alps and provide one of the first quantitative constraints demonstrating that the range is still in its infancy: In contrast to several other mountain ranges, the Alps have still more than half of their evolution to a geomorphic steady state to go. Combining our results with sediment budget data from the surrounding basins we infer that the formation of the present topography began only 5-6 million years ago. Our results question the apparent consensus that the topographic evolution is distributed over much of the Miocene and might give new impulses to the reconstruction of paleoclimate in Central Europe.

Spatial interpolation of river channel topography using the shortest temporal distance

NASA Astrophysics Data System (ADS)

Zhang, Yanjun; Xian, Cuiling; Chen, Huajin; Grieneisen, Michael L.; Liu, Jiaming; Zhang, Minghua

2016-11-01

It is difficult to interpolate river channel topography due to complex anisotropy. As the anisotropy is often caused by river flow, especially the hydrodynamic and transport mechanisms, it is reasonable to incorporate flow velocity into topography interpolator for decreasing the effect of anisotropy. In this study, two new distance metrics defined as the time taken by water flow to travel between two locations are developed, and replace the spatial distance metric or Euclidean distance that is currently used to interpolate topography. One is a shortest temporal distance (STD) metric. The temporal distance (TD) of a path between two nodes is calculated by spatial distance divided by the tangent component of flow velocity along the path, and the STD is searched using the Dijkstra algorithm in all possible paths between two nodes. The other is a modified shortest temporal distance (MSTD) metric in which both the tangent and normal components of flow velocity were combined. They are used to construct the methods for the interpolation of river channel topography. The proposed methods are used to generate the topography of Wuhan Section of Changjiang River and compared with Universal Kriging (UK) and Inverse Distance Weighting (IDW). The results clearly showed that the STD and MSTD based on flow velocity were reliable spatial interpolators. The MSTD, followed by the STD, presents improvement in prediction accuracy relative to both UK and IDW.

Influence of nanophase titania topography on bacterial attachment and metabolism

PubMed Central

Park, Margaret R; Banks, Michelle K; Applegate, Bruce; Webster, Thomas J

2008-01-01

Surfaces with nanophase compared to conventional (or nanometer smooth) topographies are known to have different properties of area, charge, and reactivity. Previously published research indicates that the attachment of certain bacteria (such as Pseudomonas fluorescens 5RL) is higher on surfaces with nanophase compared to conventional topographies, however, their effect on bacterial metabolism is unclear. Results presented here show that the adhesion of Pseudomonas fluorescens 5RL and Pseudomonas putida TVA8 was higher on nanophase than conventional titania. Importantly, in terms of metabolism, bacteria attached to the nanophase surfaces had higher bioluminescence rates than on the conventional surfaces under all nutrient conditions. Thus, the results from this study show greater select bacterial metabolism on nanometer than conventional topographies, critical results with strong consequences for the design of improved biosensors for bacteria detection. PMID:19337418

Earth's structure and evolution inferred from topography, gravity, and seismicity.

NASA Astrophysics Data System (ADS)

Watkinson, A. J.; Menard, J.; Patton, R. L.

2016-12-01

Earth's wavelength-dependent response to loading, reflected in observed topography, gravity, and seismicity, can be interpreted in terms of a stack of layers under the assumption of transverse isotropy. The theory of plate tectonics holds that the outermost layers of this stack are mobile, produced at oceanic ridges, and consumed at subduction zones. Their toroidal motions are generally consistent with those of several rigid bodies, except in the world's active mountain belts where strains are partitioned and preserved in tectonite fabrics. Even portions of the oceanic lithosphere exhibit non-rigid behavior. Earth's gravity-topography cross-spectrum exhibits notable variations in signal amplitude and character at spherical harmonic degrees l=13, 116, 416, and 1389. Corresponding Cartesian wavelengths are approximately equal to the respective thicknesses of Earth's mantle, continental mantle lithosphere, oceanic thermal lithosphere, and continental crust, all known from seismology. Regional variations in seismic moment release with depth, derived from the global Centroid Moment Tensor catalog, are also evident in the crust and mantle lithosphere. Combined, these observations provide powerful constraints for the structure and evolution of the crust, mantle lithosphere, and mantle as a whole. All that is required is a dynamically consistent mechanism relating wavelength to layer thickness and shear-strain localization. A statistically-invariant 'diharmonic' relation exhibiting these properties appears as the leading order approximation to toroidal motions on a self-gravitating body of differential grade-2 material. We use this relation, specifically its predictions of weakness and rigidity, and of folding and shear banding response as a function of wavelength-to-thickness ratio, to interpret Earth's gravity, topography, and seismicity in four-dimensions. We find the mantle lithosphere to be about 255-km thick beneath the Himalaya and the Andes, and the long

The topography of the environment alters the optimal search strategy for active particles

PubMed Central

Volpe, Giovanni

2017-01-01

In environments with scarce resources, adopting the right search strategy can make the difference between succeeding and failing, even between life and death. At different scales, this applies to molecular encounters in the cell cytoplasm, to animals looking for food or mates in natural landscapes, to rescuers during search and rescue operations in disaster zones, and to genetic computer algorithms exploring parameter spaces. When looking for sparse targets in a homogeneous environment, a combination of ballistic and diffusive steps is considered optimal; in particular, more ballistic Lévy flights with exponent α≤1 are generally believed to optimize the search process. However, most search spaces present complex topographies. What is the best search strategy in these more realistic scenarios? Here, we show that the topography of the environment significantly alters the optimal search strategy toward less ballistic and more Brownian strategies. We consider an active particle performing a blind cruise search for nonregenerating sparse targets in a 2D space with steps drawn from a Lévy distribution with the exponent varying from α=1 to α=2 (Brownian). We show that, when boundaries, barriers, and obstacles are present, the optimal search strategy depends on the topography of the environment, with α assuming intermediate values in the whole range under consideration. We interpret these findings using simple scaling arguments and discuss their robustness to varying searcher’s size. Our results are relevant for search problems at different length scales from animal and human foraging to microswimmers’ taxis to biochemical rates of reaction. PMID:29073055

The topography of the environment alters the optimal search strategy for active particles

NASA Astrophysics Data System (ADS)

Volpe, Giorgio; Volpe, Giovanni

2017-10-01

In environments with scarce resources, adopting the right search strategy can make the difference between succeeding and failing, even between life and death. At different scales, this applies to molecular encounters in the cell cytoplasm, to animals looking for food or mates in natural landscapes, to rescuers during search and rescue operations in disaster zones, and to genetic computer algorithms exploring parameter spaces. When looking for sparse targets in a homogeneous environment, a combination of ballistic and diffusive steps is considered optimal; in particular, more ballistic Lévy flights with exponent α≤1 are generally believed to optimize the search process. However, most search spaces present complex topographies. What is the best search strategy in these more realistic scenarios? Here, we show that the topography of the environment significantly alters the optimal search strategy toward less ballistic and more Brownian strategies. We consider an active particle performing a blind cruise search for nonregenerating sparse targets in a 2D space with steps drawn from a Lévy distribution with the exponent varying from α=1 to α=2 (Brownian). We show that, when boundaries, barriers, and obstacles are present, the optimal search strategy depends on the topography of the environment, with α assuming intermediate values in the whole range under consideration. We interpret these findings using simple scaling arguments and discuss their robustness to varying searcher's size. Our results are relevant for search problems at different length scales from animal and human foraging to microswimmers' taxis to biochemical rates of reaction.

Cyclic steps due to the surge-type turbidity currents in flume experiments: effect of surge duration on the topography of steps

NASA Astrophysics Data System (ADS)

Yokokawa, Miwa; Yamano, Junpei; Miyai, Masatomo; Hughes Clarke, John; Izumi, Norihiro

2017-04-01

Field observations of turbidity currents and seabed topography on the Squamish delta in British Columbia, Canada revealed that cyclic steps formed by the surge-type turbidity currents (e.g., Hughes Clarke et al., 2014). The high-density portion of the flow, which affects the sea floor morphology, lasted only 30-60 seconds. We are doing flume experiments aiming to investigate the relationship between the condition of surges and topography of resultant steps. In this presentation, we are going to discuss about the effect of surge duration on the topography of steps. The experiments have been performed at Osaka Institute of Technology. A flume, which is 7.0 m long, 0.3 m deep and 2 cm wide, was suspended in a larger tank, which is 7.6 m long, 1.2 m deep and 0.3 m wide, filled with water. The inner flume tilted at 7 degrees. As a source of turbidity currents, mixture of salt water (1.17 g/cm^3) and plastic particles (1.3 g/cm^3, 0.1-0.18 mm in diameter) was prepared. The concentration of the sediments was 6.1 weight % (5.5 volume %) in the head tank. This mixture of salt water and plastic particles poured into the upstream end of the inner flume from head tank for 3 seconds or 7 seconds. 140 surges were made respectively. Discharge of the currents were fluctuated but range from 306 to 870 mL for 3s-surge, and from 1134 to 2030 mL for 7s-surge. As a result, five or six steps were formed respectively. At the case of 3s-surge, steps located at upstream portion of the flume moved vigorously toward upstream direction, whereas steps at downstream portion of the flume moved toward upstream direction at the case of 7s-surge. The wavelengths and wave heights of the steps by 3s-surge are larger than those of 7s-surge at the upstream portion of the flume, but the size of steps of 3s-surge are smaller than those of 7s-surge at the downstream portion of the flume. In this condition of slope and concentration, the longer surge duration, i.e. larger discharge of the current

Tx/Rx Head Coil Induces Less RF Transmit-Related Heating than Body Coil in Conductive Metallic Objects Outside the Active Area of the Head Coil

PubMed Central

Nagy, Zoltan; Oliver-Taylor, Aaron; Kuehne, Andre; Goluch, Sigrun; Weiskopf, Nikolaus

2017-01-01

The transmit–receive (Tx/Rx) birdcage head coil is often used for excitation instead of the body coil because of the presumably lower risk of heating in and around conductive implants. However, this common practice has not been systematically tested. To investigate whether the Tx/Rx birdcage head coil produces less heating than the body coil when scanning individuals with implants, we used a 3T clinical scanner and made temperature measurements around a straight 15 cm conductor using either the Tx/Rx body or the head coil for excitation. Additionally, the transmitted fields of a Tx/Rx head coil were measured both in air and in gel using a resonant and a non-resonant B field probes as well as a non-resonant E field probe. Simulations using a finite-difference time domain solver were compared with the experimental findings. When the body coil was used for excitation, we observed heating around the 15 cm wire at various anatomical locations (both within and outside of the active volume of the head coil). Outside its active area, no such heating was observed while using the Tx/Rx head coil for excitation. The E and B fields of the Tx/Rx birdcage head coil extended well-beyond the physical dimensions of the coil. In air, the fields were monotonically decreasing, while in gel they were more complex with local maxima at the end of the ASTM phantom. These experimental findings were line with the simulations. While caution must always be exercised when scanning individuals with metallic implants, these findings support the use of the Tx/Rx birdcage head coil in place of the body coil at 3T in order to reduce the risk of heating in and around conductive implants that are remote from the head coil. PMID:28184184

X-Ray Topography of Tetragonal Lysozyme Grown by the Temperature-Controlled Technique

NASA Technical Reports Server (NTRS)

Stojanoff, V.; Siddons, D. P.; Monaco, Lisa A.; Vekilov, Peter; Rosenberger, Franz

1997-01-01

Growth-induced defects in lysozyme crystals were observed by white-beam and monochromatic X-ray topography at the National Synchrotron Light Source (NSLS) at the Brookhaven National Laboratory (BNL). The topographic methods were non-destructive to the extent that traditional diffraction data collection could be performed to high resolution after topography. It was found that changes in growth parameters, defect concentration as detected by X-ray topography, and the diffraction quality obtainable from the crystals were all strongly correlated. In addition, crystals with fewer defects showed lower mosaicity and higher diffraction resolution as expected.

Heading Tuning in Macaque Area V6.

PubMed

Fan, Reuben H; Liu, Sheng; DeAngelis, Gregory C; Angelaki, Dora E

2015-12-16

Cortical areas, such as the dorsal subdivision of the medial superior temporal area (MSTd) and the ventral intraparietal area (VIP), have been shown to integrate visual and vestibular self-motion signals. Area V6 is interconnected with areas MSTd and VIP, allowing for the possibility that V6 also integrates visual and vestibular self-motion cues. An alternative hypothesis in the literature is that V6 does not use these sensory signals to compute heading but instead discounts self-motion signals to represent object motion. However, the responses of V6 neurons to visual and vestibular self-motion cues have never been studied, thus leaving the functional roles of V6 unclear. We used a virtual reality system to examine the 3D heading tuning of macaque V6 neurons in response to optic flow and inertial motion stimuli. We found that the majority of V6 neurons are selective for heading defined by optic flow. However, unlike areas MSTd and VIP, V6 neurons are almost universally unresponsive to inertial motion in the absence of optic flow. We also explored the spatial reference frames of heading signals in V6 by measuring heading tuning for different eye positions, and we found that the visual heading tuning of most V6 cells was eye-centered. Similar to areas MSTd and VIP, the population of V6 neurons was best able to discriminate small variations in heading around forward and backward headings. Our findings support the idea that V6 is involved primarily in processing visual motion signals and does not appear to play a role in visual-vestibular integration for self-motion perception. To understand how we successfully navigate our world, it is important to understand which parts of the brain process cues used to perceive our direction of self-motion (i.e., heading). Cortical area V6 has been implicated in heading computations based on human neuroimaging data, but direct measurements of heading selectivity in individual V6 neurons have been lacking. We provide the first

Quantitative characterization of surface topography using spectral analysis

NASA Astrophysics Data System (ADS)

Jacobs, Tevis D. B.; Junge, Till; Pastewka, Lars

2017-03-01

Roughness determines many functional properties of surfaces, such as adhesion, friction, and (thermal and electrical) contact conductance. Recent analytical models and simulations enable quantitative prediction of these properties from knowledge of the power spectral density (PSD) of the surface topography. The utility of the PSD is that it contains statistical information that is unbiased by the particular scan size and pixel resolution chosen by the researcher. In this article, we first review the mathematical definition of the PSD, including the one- and two-dimensional cases, and common variations of each. We then discuss strategies for reconstructing an accurate PSD of a surface using topography measurements at different size scales. Finally, we discuss detecting and mitigating artifacts at the smallest scales, and computing upper/lower bounds on functional properties obtained from models. We accompany our discussion with virtual measurements on computer-generated surfaces. This discussion summarizes how to analyze topography measurements to reconstruct a reliable PSD. Analytical models demonstrate the potential for tuning functional properties by rationally tailoring surface topography—however, this potential can only be achieved through the accurate, quantitative reconstruction of the PSDs of real-world surfaces.

EAARL Topography-Colonial National Historical Park

USGS Publications Warehouse

Brock, John C.; Wright, C. Wayne; Nayegandhi, Amar; Stevens, Sara; Travers, Laurinda J.

2008-01-01

These Lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, Florida Integrated Science Center (FISC) St. Petersburg, the National Park Service (NPS) Inventory and Monitoring Program, Northeast Coastal and Barrier Network, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs, barrier islands, and various nearshore coastal environments for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to coastal resource managers.

The effect of topography of upper mantle discontinuities on SS precursors

NASA Astrophysics Data System (ADS)

Koroni, M.; Trampert, J.

2015-12-01

We assessed the reliability of methods used to infer the topography of the mantle transition zone discontinuities. In particular, using the spectral-element method,we explored the effect of topography of the '410' and '660' mantle discontinuities on the travel times of SS precursors recorded on transverse component seismograms.The latter are routinely used to infer the topography of mantle transition zone discontinuities. The step from precursorytravel times to topographic changes is mainly done using linearised ray theory, or sometimes using finite frequency kernels.We simulated exact seismograms in 1-D and 3-D elastic models of the mantle. In a second simulation, we added topography to the discontinuities. We compared the waveforms obtained with and without topography by cross-correlation of the SS precursors. Since we did not add noise, the precursors are visible in individual seismograms without the need of stacking. The resultingtime anomalies were then converted into topographic variations and compared to the original models of topography. We found that linearised ray theory gives a relatively good idea on the location of the uplifts and depressions of the discontinuities, provided that the ray coverage is good, although it seriously underestimates the amplitude of the topography. The amplitude of the topographic variation is underestimated in average by a factor of 2.8 for the '660' and of 4.5 for the '410'. Additionally, we found a strong non-linearity in the measured data which cannot be modelled without a fully non-linear inversion for elastic structure and discontinuities simultaneously.

Mapping the Topography of Europa: The Galileo-Clipper Story

NASA Astrophysics Data System (ADS)

Schenk, Paul M.

2014-11-01

The renewed effort to return to Europa for global mapping and landing site selection raises the question: What do we know about Europa topography and how do we know it? The question relates to geologic questions of feature formation, to the issue of ice shell thickness, mechanical strength, and internal activity, and to landing hazards. Our topographic data base for Europa is sparse indeed (no global map is possible), but we are not without hope. Two prime methods have been employed in our mapping program are stereo image and shape-from-shading (PC) slope analyses. On Europa, we are fortunate that many PC-DEM areas are also controlled by stereo-DEMs, mitigating the long-wavelength uncertainties in the PC data. Due to the Galileo antenna malfunction, mapping is limited to no more than 20% of the surface, far less than for any of the inner planets. Thirty-seven individual mapping sites have been identified, scattered across the globe, and all have now been mapped. Excellent stereo mapping is possible at all Sun angles, if resolution is below ~350 m. PC mapping is possible at Sun angles greater than ~60 degrees, if emission angles are less than ~40 degrees. The only extended contiguous areas of topographic mapping larger than 150 km across are the two narrow REGMAP mapping mosaics extending pole-to-pole along longitudes 85 and 240 W. These are PC-only and subject to long-wavelength uncertainties and errors, especially in the north/south where oblique imaging produces layover. Key findings include the mean slopes of individual terrain types (Schenk, 2009), topography across chaos (Schenk and Pappalardo, 2004), topography of craters and inferences for ice shell thickness (Schenk, 2002; Schenk and Turtle, 2009), among others. A key discovery, despite the limited data, is that Europan terrains rarely have topographic amplitude greater than 250 meters, but that regionally Europa has imprinted on it topographic amplitudes of +/- 1 km, in the form of raised plateaus and

Experimental support that ocular tremor in Parkinson's disease does not originate from head movement.

PubMed

Gitchel, George T; Wetzel, Paul A; Qutubuddin, Abu; Baron, Mark S

2014-07-01

Our recent report of ocular tremor in Parkinson's disease (PD) has raised considerable controversy as to the origin of the tremor. Using an infrared based eye tracker and a magnetic head tracker, we reported that ocular tremor was recordable in PD subjects with no apparent head tremor. However, other investigators suggest that the ocular tremor may represent either transmitted appendicular tremor or subclinical head tremor inducing the vestibulo-ocular reflex (VOR). The present study aimed to further investigate the origin of ocular tremor in PD. Eye movements were recorded in 8 PD subjects both head free, and with full head restraint by means of a head holding device and a dental impression bite plate. Head movements were recorded independently using both a high sensitivity tri-axial accelerometer and a magnetic tracking system, each synchronized to the eye tracker. Ocular tremor was observed in all 8 PD subjects and was not influenced by head free and head fixed conditions. Both magnetic tracking and accelerometer recordings supported that the ocular tremor was fully independent of head position. The present study findings support our initial findings that ocular tremor is a fundamental feature of PD unrelated to head movements. Although the utility of ocular tremor for diagnostic purposes requires validation, current findings in large cohorts of PD subjects suggest its potential as a reliable clinical biomarker. Published by Elsevier Ltd.

[Influence of different surface treatments on porcelain surface topography].

PubMed

Tai, Yinxia; Zhu, Xianchun; Sen, Yan; Liu, Chang; Zhang, Xian; Shi, Xueming

2013-02-01

To evaluate the influence of different surface treatments on porcelain surface topography. Metal ceramic prostheses in 6 groups were treated according to the different surface treatment methods, and the surface topography was observed through scanning electron microscope (SEM). Group A was the control one (untreated), group B was etched by 9.6% hydrofluoric acid(HF), group C was deglazed by grinding and then etched by 9.6% HF, group D was treated with Nd: YAG laser irradiation(0.75 W) and HF etching, group E was treated with Nd: YAG laser irradiation (1.05 W) and HF etching, and group F was treated with laser irradiation (1.45 W) and HF etching. Surface topography was different in different groups. A lot of inerratic cracks with the shapes of rhombuses and grid, and crater with a shape of circle were observed on the ceramic surface after treatment with energy parameters of 1.05 W Nd: YAG laser irradiation and 9.6% HF etching (group E). Surface topography showed a lot of concaves on the inner wall of the cracks, and the concaves with diameter of 1-5 microm could be observed on the inner wall of the holes, which had a diameter of 20 microm under SEM. The use of Nd: YAG laser irradiation with the energy parameters of 1.05 W and the HF with a concentration of 9.6% can evenly coarsen the porcelain surface, that is an effective surface treatment method.

Role of Cigarette Sensory Cues in Modifying Puffing Topography

PubMed Central

Rees, Vaughan W.; Kreslake, Jennifer M.; Wayne, Geoffrey Ferris; O Connor, Richard J.; Cummings, K. Michael; Connolly, Gregory N.

2012-01-01

Background Human puffing topography promotes tobacco dependence by ensuring nicotine delivery, but the factors that determine puffing behavior are not well explained by existing models. Chemosensory cues generated by variations in cigarette product design features may serve as conditioned cues to allow the smoker to optimize nicotine delivery by adjusting puffing topography. Internal tobacco industry research documents were reviewed to understand the influence of sensory cues on puffing topography, and to examine how the tobacco industry has designed cigarettes, including modified risk tobacco products (MRTPs), to enhance puffing behavior to optimize nicotine delivery and product acceptability. Methods Relevant internal tobacco industry documents were identified using systematic searching with key search terms and phrases, and then snowball sampling method was applied to establish further search terms. Results Modern cigarettes are designed by cigarette manufacturers to provide sensory characteristics that not only maintain appeal, but provide cues which inform puffing intensity. Alterations in the chemosensory cues provided in tobacco smoke play an important role in modifying smoking behavior independently of the central effects of nicotine. Conclusions An associative learning model is proposed to explain the influence of chemosensory cues on variation in puffing topography. These cues are delivered via tobacco smoke and are moderated by design features and additives used in cigarettes. The implications for regulation of design features of modified risk tobacco products, which may act to promote intensive puffing while lowering risk perceptions, are discussed. PMID:22365895

Promoting Children's Social-Emotional Skills in Preschool Can Enhance Academic and Behavioral Functioning in Kindergarten: Findings from Head Start REDI

PubMed Central

Nix, Robert L.; Bierman, Karen L.; Domitrovich, Celene E.; Gill, Sukhdeep

2013-01-01

This study examined processes of change associated with the positive preschool and kindergarten outcomes of children who received the Head Start REDI intervention, compared to “usual practice” Head Start. In a large-scale randomized-controlled trial (N = 356 children, 42% African American or Latino, all from low-income families), this study tests the logic model that improving preschool social-emotional skills (e.g., emotion understanding, social problem solving, and positive social behavior) as well as language/emergent literacy skills will promote cross-domain academic and behavioral adjustment after children transition into kindergarten. Validating this logic model, the present study finds that intervention effects on three important kindergarten outcomes (e.g., reading achievement, learning engagement, and positive social behavior) were mediated by preschool gains in the proximal social-emotional and language/emergent literacy skills targeted by the REDI intervention. Importantly, preschool gains in social-emotional skills made unique contributions to kindergarten outcomes in reading achievement and learning engagement, even after accounting for the concurrent preschool gains in vocabulary and emergent literacy skills. These findings highlight the importance of fostering at-risk children's social-emotional skills during preschool as a means of promoting school readiness. The REDI (Research-Based, Developmentally-Informed) enrichment intervention was designed to complement and strengthen the impact of existing Head Start programs in the dual domains of language/emergent literacy skills and social-emotional competencies. REDI was one of several projects funded by the Interagency School Readiness Consortium, a partnership of four federal agencies (the National Institute of Child Health and Human Development, the Administration for Children and Families, the Assistant Secretary for Planning and Evaluation in the Department of Health and Human Services, and the

Spatial distribution of erosion in the Hangay Mountains of Mongolia and implications for the development of epeirogenic topography

NASA Astrophysics Data System (ADS)

West, A.; Fox, M.; Walker, R. T.; Carter, A.; Watts, A. B.; Gantulga, B.

2012-12-01

Potential feedbacks between climate-driven erosion and the development of intra-continental topography have received relatively little attention, particularly compared to the significant efforts to understand the interplay of climate, erosion, and uplift in orogenic settings. But such links may be vital for understanding the topographic evolution of epeirogenic topography and for making inferences about geodynamic processes based on associated sedimentary and geomorphic signals. In this study, we consider the role of orographically-driven climate variability in shaping continental topography by focusing on the Hangay mountain range, a uplifted dome in central Mongolia. The work presented here is based on results from a topographic analysis of the Hangay, making use of the flat-topped peaks that effectively represent preserved remnants of a pre-erosional surface. We have determined the scale and distribution of erosion by recreating this pre-erosional surface and subtracting the present-day, dissected topography. Our results show that the extent of erosion correlates with spatial variation in mean annual precipitation, but not with the extent of total surface uplift. The morphology of the range reflects the higher, climate-driven fluvial erosion rates by northern rivers that receive higher precipitation when compared to the southern rivers, which have steeper relief as a result of the asymmetric main drainage divide. Overall asymmetry in inferred isostatic response to erosional unloading is not mirrored in asymmetry of total surface uplift, hinting at interaction between surface erosion and the forces sustaining topography. This has important implications for understanding the geodynamics of epeirogenic uplift. In addition to these main outcomes from our topographic analysis, we will also present preliminary findings from detrital thermochronology and cosmogenic analyses that help to pinpoint the location of erosion and provide a basis for quantifying rates.

Terrain Classification on Venus from Maximum-Likelihood Inversion of Parameterized Models of Topography, Gravity, and their Relation

NASA Astrophysics Data System (ADS)

Eggers, G. L.; Lewis, K. W.; Simons, F. J.; Olhede, S.

2013-12-01

Venus does not possess a plate-tectonic system like that observed on Earth, and many surface features--such as tesserae and coronae--lack terrestrial equivalents. To understand Venus' tectonics is to understand its lithosphere, requiring a study of topography and gravity, and how they relate. Past studies of topography dealt with mapping and classification of visually observed features, and studies of gravity dealt with inverting the relation between topography and gravity anomalies to recover surface density and elastic thickness in either the space (correlation) or the spectral (admittance, coherence) domain. In the former case, geological features could be delineated but not classified quantitatively. In the latter case, rectangular or circular data windows were used, lacking geological definition. While the estimates of lithospheric strength on this basis were quantitative, they lacked robust error estimates. Here, we remapped the surface into 77 regions visually and qualitatively defined from a combination of Magellan topography, gravity, and radar images. We parameterize the spectral covariance of the observed topography, treating it as a Gaussian process assumed to be stationary over the mapped regions, using a three-parameter isotropic Matern model, and perform maximum-likelihood based inversions for the parameters. We discuss the parameter distribution across the Venusian surface and across terrain types such as coronoae, dorsae, tesserae, and their relation with mean elevation and latitudinal position. We find that the three-parameter model, while mathematically established and applicable to Venus topography, is overparameterized, and thus reduce the results to a two-parameter description of the peak spectral variance and the range-to-half-peak variance (in function of the wavenumber). With the reduction the clustering of geological region types in two-parameter space becomes promising. Finally, we perform inversions for the JOINT spectral variance of

Bearing-Foreign Material Deposition on Retrieved Co-Cr Femoral Heads: Composition and Morphology

PubMed Central

Tikekar, Nishant M.; Heiner, Anneliese D.; Baer, Thomas E.; Kruger, Karen M.; Callaghan, John J.; Brown, Thomas D.; Lannutti, John J.

2015-01-01

Bearing-foreign material deposition onto a femoral head can occur from contact with an acetabular shell due to dislocation, reduction, or subluxation. The purpose of this study was to comprehensively characterize deposit regions on retrieved cobalt-chrome femoral heads from metal-on-polyethylene total hip arthroplasties that had experienced such adverse events. The morphology, topography, and composition of deposition regions were characterized using macrophotography, optical profilometry, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. The deposit areas were relatively large, they were much rougher than the surrounding undamaged clean areas, and they displayed several distinct morphologies. Titanium alloy elements were the predominant constituents. Calcium and phosphorous were also detected within the deposit areas, in a composition that could nucleate abrasive hydroxyapatite. In addition, tungsten-rich particles, likely present as tungsten carbide, were observed on top of the titanium deposits. The increased roughness associated with these deposition features would be expected to accelerate damage and wear of the opposing liner and hence accelerate the development of osteolysis. PMID:26236744

An anatomical and functional topography of human auditory cortical areas

PubMed Central

Moerel, Michelle; De Martino, Federico; Formisano, Elia

2014-01-01

While advances in magnetic resonance imaging (MRI) throughout the last decades have enabled the detailed anatomical and functional inspection of the human brain non-invasively, to date there is no consensus regarding the precise subdivision and topography of the areas forming the human auditory cortex. Here, we propose a topography of the human auditory areas based on insights on the anatomical and functional properties of human auditory areas as revealed by studies of cyto- and myelo-architecture and fMRI investigations at ultra-high magnetic field (7 Tesla). Importantly, we illustrate that—whereas a group-based approach to analyze functional (tonotopic) maps is appropriate to highlight the main tonotopic axis—the examination of tonotopic maps at single subject level is required to detail the topography of primary and non-primary areas that may be more variable across subjects. Furthermore, we show that considering multiple maps indicative of anatomical (i.e., myelination) as well as of functional properties (e.g., broadness of frequency tuning) is helpful in identifying auditory cortical areas in individual human brains. We propose and discuss a topography of areas that is consistent with old and recent anatomical post-mortem characterizations of the human auditory cortex and that may serve as a working model for neuroscience studies of auditory functions. PMID:25120426

Numerical modeling and analysis of the effect of complex Greek topography on tornadogenesis

NASA Astrophysics Data System (ADS)

Matsangouras, I. T.; Pytharoulis, I.; Nastos, P. T.

2014-07-01

Tornadoes have been reported in Greece over recent decades in specific sub-geographical areas and have been associated with strong synoptic forcing. While it has been established that meteorological conditions over Greece are affected at various scales by the significant variability of topography, the Ionian Sea to the west and the Aegean Sea to the east, there is still uncertainty regarding topography's importance on tornadic generation and development. The aim of this study is to investigate the role of topography in significant tornadogenesis events that were triggered under strong synoptic scale forcing over Greece. Three tornado events that occurred over the last years in Thebes (Boeotia, 17 November 2007), Vrastema (Chalkidiki, 12 February 2010) and Vlychos (Lefkada, 20 September 2011) were selected for numerical experiments. These events were associated with synoptic scale forcing, while their intensities were T4-T5 (on the TORRO scale), causing significant damage. The simulations were performed using the non-hydrostatic weather research and forecasting model (WRF), initialized by European Centre for Medium-Range Weather Forecasts (ECMWF) gridded analyses, with telescoping nested grids that allow for the representation of atmospheric circulations ranging from the synoptic scale down to the mesoscale. In the experiments, the topography of the inner grid was modified by: (a) 0% (actual topography) and (b) -100% (without topography), making an effort to determine whether the occurrence of tornadoes - mainly identified by various severe weather instability indices - could be indicated by modifying topography. The principal instability variables employed consisted of the bulk Richardson number (BRN) shear, the energy helicity index (EHI), the storm-relative environmental helicity (SRH), and the maximum convective available potential energy (MCAPE, for parcels with maximum θe). Additionally, a model verification was conducted for every sensitivity experiment

Reconstructed Paleo-topography of the Columbia Hills, Mars

NASA Astrophysics Data System (ADS)

Cole, S. B.; Watters, W. A.; Aron, F.; Squyres, S. W.

2013-12-01

From June 2004 through March 2010, the Mars Exploration Rover Spirit conducted a detailed campaign examining the Columbia Hills of Gusev Crater. In addition to mineralogical and chemical investigations, Spirit's stereo panoramic (Pancam) and navigation (Navcam) cameras obtained over 7,000 images of geologic targets along the West Spur of the Columbia Hills and Husband Hill, the highest peak. We have analyzed the entirety of this dataset, which includes stereo coverage of several outcrop exposures with apparent bedding. We have measured the bedding plane orientations of hundreds of fine-scale (~1-100cm) features on all of the potentially in-place outcrops using Digital Terrain Models (DTMs) derived from the rover's Pancam stereo image data, and mapped these orientations on a regional HiRISE image and DTM. Assuming that the bedding material was deposited conformably on the topography at the time of emplacement, we reconstruct the paleo-topography of the Columbia Hills. Our reconstructed paleo-topography is similar to the modern shape of Husband Hill, but with steeper slopes, consistent with a substantial amount of erosion since deposition. The Columbia Hills are an irregular, nearly-triangular edifice of uncertain origin, situated near the center of the 160km-diameter crater and hypothesized to be either the remnant of a central peak structure, or overlapping crater rims. They span ~6.6 km in the northerly direction by ~3.6 km in the easterly direction, and rise 90m above the basaltic plains that fill the floor of Gusev Crater and embay the Hills. The topography is as irregular as the perimeter, and is cut by numerous valleys of varying lengths, widths, and directional trends. Along the traverse, Spirit examined several rock classes as defined by elemental abundances from the Alpha Particle X-ray Spectrometer (APXS) and identified remotely by the Miniature Thermal Emission Spectrometer (Mini-TES). Unlike the Gusev Plains, the rocks of the Columbia Hills show

Topography of Responses in Conditional Discrimination Influences Formation of Equivalence Classes

ERIC Educational Resources Information Center

Kato, Olivia M.; de Rose, Julio C.; Faleiros, Pedro B.

2008-01-01

The effects of response topography on stimulus class formation were studied in two experiments. In Experiment 1, 32 college students were assigned to 2 response topographies and 2 stimulus sets, in a 2 x 2 design. Students selected stimuli by either moving a mouse to lace an arrow-shaped cursor on the stimulus or pressing a key corresponding to…

Topography may mitigate drought effects on vegetation along a hillslope gradient

Treesearch

Sandra Hawthorne; Chelcy Ford Miniat

2017-01-01

Topography may mitigate drought effects on vegetation along a hillslope gradient through redistribution of soil moisture. We examined the interaction of topography, climate, soil moisture, and transpiration in a low‐elevation, mixed‐hardwood forest in the southern Appalachian Mountains. The effects of meteorological variation (wet and dry years) and topographic...

Users' Manual for Research: Translating Head Start Findings Into Action (Expanded Notebook Version).

ERIC Educational Resources Information Center

Grotberg, Edith H.; Fowler, Austine

This users' manual, intended for use with a Project Head Start teacher training notebook, describes the purpose, development and field testing of the training materials and suggests procedures for using the notebook as a resource in teacher training sessions. The training notebook to which the users' manual refers is based on 11 questions in the…

Puffing Topography and Nicotine Intake of Electronic Cigarette Users

PubMed Central

Behar, Rachel Z.; Hua, My; Talbot, Prue

2015-01-01

Background Prior electronic cigarette (EC) topography data are based on two video analyses with limited parameters. Alternate methods for measuring topography are needed to understand EC use and nicotine intake. Objectives This study evaluated EC topography with a CReSS Pocket device and quantified nicotine intake. Methods Validation tests on pressure drop, flow rate, and volume confirmed reliable performance of the CReSS Pocket device. Twenty participants used Blu Cigs and V2 Cigs for 10 minute intervals with a 10–15 minute break between brands. Brand order was reversed and repeated within 7 days Data were analyzed to determine puff duration, puff count, volume, flow rate, peak flow, and inter-puff interval. Nicotine intake was estimated from cartomizer fluid consumption and topography data. Results Nine patterns of EC use were identified. The average puff count and inter-puff interval were 32 puffs and 17.9 seconds. All participants, except one, took more than 20 puffs/10 minutes. The averages for puff duration (2.65 seconds/puff), volume/puff (51ml/puff), total puff volume (1,579 ml), EC fluid consumption (79.6 mg), flow rate (20 ml/s), and peak flow rate (27 ml/s) were determined for 10-minute sessions. All parameters except total puff count were significantly different for Blu versus V2 EC. Total volume for Blu versus V2 was four-times higher than for conventional cigarettes. Average nicotine intake for Blu and V2 across both sessions was 1.2 ± 0.5 mg and 1.4 ± 0.7 mg, respectively, which is similar to conventional smokers. Conclusions EC puffing topography was variable among participants in the study, but often similar within an individual between brands or days. Puff duration, inter-puff interval, and puff volume varied from conventional cigarette standards. Data on total puff volume and nicotine intake are consistent with compensatory usage of EC. These data can contribute to the development of a standard protocol for laboratory testing of EC products

Estimating Antarctica land topography from GRACE gravity and ICESat altimetry data

NASA Astrophysics Data System (ADS)

Wu, I.; Chao, B. F.; Chen, Y.

2009-12-01

We propose a new method combining GRACE (Gravity Recovery and Climate Experiment) gravity and ICESat (Ice, Cloud, and land Elevation Satellite) altimetry data to estimate the land topography for Antarctica. Antarctica is the fifth-largest continent in the world and about 98% of Antarctica is covered by ice, where in-situ measurements are difficult. Some experimental airborne radar and ground-based radar data have revealed very limited land topography beneath heavy ice sheet. To estimate the land topography for the full coverage of Antarctica, we combine GRACE data that indicate the mass distribution, with data of ICESat laser altimetry that provide high-resolution mapping of ice topography. Our approach is actually based on some geological constraints: assuming uniform densities of the land and ice considering the Airy-type isostasy. In the beginning we construct an initial model for the ice thickness and land topography based on the BEDMAP ice thickness and ICESat data. Thereafter we forward compute the model’s gravity field and compare with the GRACE observed data. Our initial model undergoes the adjustments to improve the fit between modeled results and the observed data. Final examination is done by comparing our results with previous but sparse observations of ice thickness to reconfirm the reliability of our results. As the gravitational inversion problem is non-unique, our estimating result is just one of all possibilities constrained by available data in optimal way.

EAARL Coastal Topography - Sandy Hook 2007

USGS Publications Warehouse

Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Stevens, Sara; Yates, Xan; Bonisteel, Jamie M.

2008-01-01

These remotely sensed, geographically referenced elevation measurements of Lidar-derived topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), Northeast Coastal and Barrier Network, Kingston, RI; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of Gateway National Recreation Area's Sandy Hook Unit in New Jersey, acquired on May 16, 2007. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL) was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then

Probing Tectonic Topography in the Aftermath of Continental Convergence in Central Europe

NASA Astrophysics Data System (ADS)

Cloetingh, S.; Horváth, F.; Dinu, C.; Stephenson, R. A.; Bertotti, G.; Bada, G.; Matenco, L.; Garcia-Castellanos, D.

Continental topography is at the interface of processes taking place at depth in the Earth, at its surface, and above it. Topography influences society, not only in terms of slow processes of landscape change and earthquakes but also in terms of how it affects climate. The Pannonian Basin - Carpathian Orogen System in Central and Eastern Europe represents a key natural laboratory for the development of a new generation of models for ongoing orogeny and its effect on continental topography development (Figure 1). This system comprises some of the best documented sedimentary basins in the world, located within the Alpine orogenic belt, at the transition between the western European lithosphere and the East European Craton. It includes one of the most active seismic zones in Europe, with intermediate depth (50-220km) mantle earthquakes of significant magnitude occurring in a geographically restricted area in the Vrancea zone of southeastern Romania. The objective of TECTOP (TECtonic TOPography) is to quantify the links between neotectonics and continental topography in the aftermath of continental convergence. TECTOP was initiated in fall 2001 by the Netherlands Research Centre for Integrated Solid Earth Science (ISES), the University of Bucharest, Romania and the Eötvös University in Budapest,Hungary. This paper highlights the generic concept and the first results of TECTOP.

Visualization of High-Resolution LiDAR Topography in Google Earth

NASA Astrophysics Data System (ADS)

Crosby, C. J.; Nandigam, V.; Arrowsmith, R.; Blair, J. L.

2009-12-01

The growing availability of high-resolution LiDAR (Light Detection And Ranging) topographic data has proven to be revolutionary for Earth science research. These data allow scientists to study the processes acting on the Earth’s surfaces at resolutions not previously possible yet essential for their appropriate representation. In addition to their utility for research, the data have also been recognized as powerful tools for communicating earth science concepts for education and outreach purposes. Unfortunately, the massive volume of data produced by LiDAR mapping technology can be a barrier to their use. To facilitate access to these powerful data for research and educational purposes, we have been exploring the use of Keyhole Markup Language (KML) and Google Earth to deliver LiDAR-derived visualizations. The OpenTopography Portal (http://www.opentopography.org/) is a National Science Foundation-funded facility designed to provide access to Earth science-oriented LiDAR data. OpenTopography hosts a growing collection of LiDAR data for a variety of geologic domains, including many of the active faults in the western United States. We have found that the wide spectrum of LiDAR users have variable scientific applications, computing resources, and technical experience and thus require a data distribution system that provides various levels of access to the data. For users seeking a synoptic view of the data, and for education and outreach purposes, delivering full-resolution images derived from LiDAR topography into the Google Earth virtual globe is powerful. The virtual globe environment provides a freely available and easily navigated viewer and enables quick integration of the LiDAR visualizations with imagery, geographic layers, and other relevant data available in KML format. Through region-dependant network linked KML, OpenTopography currently delivers over 20 GB of LiDAR-derived imagery to users via simple, easily downloaded KMZ files hosted at the Portal

ATM Coastal Topography-Texas, 2001: UTM Zone 14

USGS Publications Warehouse

Klipp, Emily S.; Nayegandhi, Amar; Brock, John C.; Sallenger, A.H.; Bonisteel, Jamie M.; Yates, Xan; Wright, C. Wayne

2009-01-01

These remotely sensed, geographically referenced elevation measurements of lidar-derived first-surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Texas coastline within UTM zone 14, acquired October 12-13, 2001. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative scanning lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of lidar data in an interactive or batch mode. Modules for presurvey flight-line definition, flight-path plotting, lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used

Elastic Reverse Time Migration (RTM) From Surface Topography

NASA Astrophysics Data System (ADS)

Akram, Naveed; Chen, Xiaofei

2017-04-01

Seismic Migration is a promising data processing technique to construct subsurface images by projecting the recorded seismic data at surface back to their origins. There are numerous Migration methods. Among them, Reverse Time Migration (RTM) is considered a robust and standard imaging technology in present day exploration industry as well as in academic research field because of its superior performance compared to traditional migration methods. Although RTM is extensive computing and time consuming but it can efficiently handle the complex geology, highly dipping reflectors and strong lateral velocity variation all together. RTM takes data recorded at the surface as a boundary condition and propagates the data backwards in time until the imaging condition is met. It can use the same modeling algorithm that we use for forward modeling. The classical seismic exploration theory assumes flat surface which is almost impossible in practice for land data. So irregular surface topography has to be considered in simulation of seismic wave propagation, which is not always a straightforward undertaking. In this study, Curved grid finite difference method (CG-FDM) is adapted to model elastic seismic wave propagation to investigate the effect of surface topography on RTM results and explore its advantages and limitations with synthetic data experiments by using Foothill model with topography as the true model. We focus on elastic wave propagation rather than acoustic wave because earth actually behaves as an elastic body. Our results strongly emphasize on the fact that irregular surface topography must be considered for modeling of seismic wave propagation to get better subsurface images specially in mountainous scenario and suggest practitioners to properly handled the geometry of data acquired on irregular topographic surface in their imaging algorithms.

Elastic Reverse Time Migration (RTM) From Surface Topography

NASA Astrophysics Data System (ADS)

Naveed, A.; Chen, X.

2016-12-01

Seismic Migration is a promising data processing technique to construct subsurface images by projecting the recorded seismic data at surface back to their origins. There are numerous Migration methods. Among them, Reverse Time Migration (RTM) is considered a robust and standard imaging technology in present day exploration industry as well as in academic research field because of its superior performance compared to traditional migration methods. Although RTM is extensive computing and time consuming but it can efficiently handle the complex geology, highly dipping reflectors and strong lateral velocity variation all together. RTM takes data recorded at the surface as a boundary condition and propagates the data backwards in time until the imaging condition is met. It can use the same modeling algorithm that we use for forward modeling. The classical seismic exploration theory assumes flat surface which is almost impossible in practice for land data. So irregular surface topography has to be considered in simulation of seismic wave propagation, which is not always a straightforward undertaking. In this study, Curved grid finite difference method (CG-FDM) is adapted to model elastic seismic wave propagation to investigate the effect of surface topography on RTM results and explore its advantages and limitations with synthetic data experiments by using Foothill model with topography as the true model. We focus on elastic wave propagation rather than acoustic wave because earth actually behaves as an elastic body. Our results strongly emphasize on the fact that irregular surface topography must be considered for modeling of seismic wave propagation to get better subsurface images specially in mountainous scenario and suggest practitioners to properly handled the geometry of data acquired on irregular topographic surface in their imaging algorithms.

Determining Relative Contributions of Vegetation and Topography to Burn Severity from LANDSAT Imagery

NASA Astrophysics Data System (ADS)

Wu, Zhiwei; He, Hong S.; Liang, Yu; Cai, Longyan; Lewis, Bernard J.

2013-10-01

Fire is a dominant process in boreal forest landscapes and creates a spatial patch mosaic with different burn severities and age classes. Quantifying effects of vegetation and topography on burn severity provides a scientific basis on which forest fire management plans are developed to reduce catastrophic fires. However, the relative contribution of vegetation and topography to burn severity is highly debated especially under extreme weather conditions. In this study, we hypothesized that relationships of vegetation and topography to burn severity vary with fire size. We examined this hypothesis in a boreal forest landscape of northeastern China by computing the burn severity of 24 fire patches as the difference between the pre- and post-fire Normalized Difference Vegetation Index obtained from two Landsat TM images. The vegetation and topography to burn severity relationships were evaluated at three fire-size levels of small (<100 ha, n = 12), moderate (100-1,000 ha, n = 9), and large (>1,000 ha, n = 3). Our results showed that vegetation and topography to burn severity relationships were fire-size-dependent. The burn severity of small fires was primary controlled by vegetation conditions (e.g., understory cover), and the burn severity of large fires was strongly influenced by topographic conditions (e.g., elevation). For moderate fires, the relationships were complex and indistinguishable. Our results also indicated that the pattern trends of relative importance for both vegetation and topography factors were not dependent on fire size. Our study can help managers to design fire management plans according to vegetation characteristics that are found important in controlling burn severity and prioritize management locations based on the relative importance of vegetation and topography.

Promoting scientific collaboration and research through integrated social networking capabilities within the OpenTopography Portal

NASA Astrophysics Data System (ADS)

Nandigam, V.; Crosby, C. J.; Baru, C.

2009-04-01

software technologies and platforms. These include the Expression Engine Content Management System (CMS) that comes with pre-packaged collaboration tools like blogs and wikis, the Gridsphere portal framework that contains the primary GEON LiDAR System portlet with user job monitoring capabilities and a java web based discussion forum (Jforums) application all seamlessly integrated under one portal. The OpenTopography Portal also provides integrated authentication mechanism between the various CMS collaboration tools and the core gridsphere based portlets. The integration of these various technologies allows for enhanced user interaction capabilities within the portal. By integrating popular collaboration tools like discussion forums and blogs we can promote conversation and openness among users. The ability to ask question and share expertise in forum discussions allows users to easily find information and interact with users facing similar challenges. The OpenTopography Blog enables our domain experts to post ideas, news items, commentary, and other resources in order to foster discussion and information sharing. The content management capabilities of the portal allow for easy updates to information in the form of publications, documents, and news articles. Access to the most current information fosters better decision-making. As has become the standard for web 2.0 technologies, the OpenTopography Portal is fully RSS enabled to allow users of the portal to keep track of news items, forum discussions, blog updates, and system outages. We are currently exploring how the information captured by user and job monitoring components of the Gridsphere based GEON LiDAR System can be harnessed to provide a recommender system that will help users to identify appropriate processing parameters and to locate related documents and data. By seamlessly integrating the various platforms and technologies under one single portal, we can take advantage of popular online collaboration tools

Topography on a subcellular scale modulates cellular adhesions and actin stress fiber dynamics in tumor associated fibroblasts

NASA Astrophysics Data System (ADS)

Azatov, Mikheil; Sun, Xiaoyu; Suberi, Alexandra; Fourkas, John T.; Upadhyaya, Arpita

2017-12-01

Cells can sense and adapt to mechanical properties of their environment. The local geometry of the extracellular matrix, such as its topography, has been shown to modulate cell morphology, migration, and proliferation. Here we investigate the effect of micro/nanotopography on the morphology and cytoskeletal dynamics of human pancreatic tumor-associated fibroblast cells (TAFs). We use arrays of parallel nanoridges with variable spacings on a subcellular scale to investigate the response of TAFs to the topography of their environment. We find that cell shape and stress fiber organization both align along the direction of the nanoridges. Our analysis reveals a strong bimodal relationship between the degree of alignment and the spacing of the nanoridges. Furthermore, focal adhesions align along ridges and form preferentially on top of the ridges. Tracking actin stress fiber movement reveals enhanced dynamics of stress fibers on topographically patterned surfaces. We find that components of the actin cytoskeleton move preferentially along the ridges with a significantly higher velocity along the ridges than on a flat surface. Our results suggest that a complex interplay between the actin cytoskeleton and focal adhesions coordinates the cellular response to micro/nanotopography.

Flow- topography Interactions in the Vicinity of a Deep Ocean Island and a Ridge

DTIC Science & Technology

2015-09-30

1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Flow- topography Interactions in the Vicinity of a Deep...flow around abrupt topography in operational Navy models. RELATED PROJECTS NRL FY17 6.2 New Start proposal (pending proposal), titled...Predictability of Flow Interacting with Abrupt Topography (FIAT)”; lead PI: Ana Rice, NRL-SSC. The objective of FIAT is to use observations to develop Navy

Numerical modeling and analysis of the effect of Greek complex topography on tornado genesis

NASA Astrophysics Data System (ADS)

Matsangouras, I. T.; Pytharoulis, I.; Nastos, P. T.

2014-02-01

Tornadoes have been reported in Greece over the last decades in specific sub-geographical areas and have been associated with strong synoptic forcing. It is well known that meteorological conditions over Greece are affected at various scales by the significant variability of topography, the Ionian Sea at the west and the Aegean Sea at the east. However, there is still uncertainty regarding topography's importance on tornadic generation and development. The aim of this study is to investigate the role of topography in significant tornado genesis events that were triggered under strong synoptic scale forcing over Greece. Three tornado events that occurred over the last years in Thiva (Boeotia, 17 November 2007), Vrastema (Chalkidiki, 12 February 2010) and Vlychos (Lefkada, 20 September 2011) have been selected for numerical experiments. These events were associated with synoptic scale forcing, while their intensity was T4-T5 (Torro scale) and caused significant damage. The simulations were performed using the non-hydrostatic Weather Research and Forecasting model (WRF), initialized with ECMWF gridded analyses, with telescoping nested grids that allow the representation of atmospheric circulations ranging from the synoptic scale down to the meso scale. In the experiments the topography of the inner grid was modified by: (a) 0% (actual topography) and (b) -100% (without topography). The aim was to determine whether the occurrence of tornadoes - mainly identified by various severe weather instability indices - could be indicated by modifying topography. The main utilized instability variables concerned the Bulk Richardson number shear (BRN), the energy helicity index (EHI), the storm-relative environmental helicity (SRH) and the maximum convective available potential energy (MCAPE, for parcel with maximum theta-e). Additional a verification of model was conducted for every sensitivity experiment accompanied with analysis absolute vorticity budget. Numerical simulations

Recovery of Neonatal Head Turning to Decreased Sound Pressure Level.

ERIC Educational Resources Information Center

Tarquinio, Nancy; And Others

1990-01-01

Investigated newborns' responses to decreased sound pressure level (SPL) by means of a localized head turning habituation procedure. Findings, which demonstrated recovery of neonatal head turning to decreased SPL, were inconsistent with the selective receptor adaptation model. (RH)

Detection of a dynamic topography signal in last interglacial sea-level records

PubMed Central

Austermann, Jacqueline; Mitrovica, Jerry X.; Huybers, Peter; Rovere, Alessio

2017-01-01

Estimating minimum ice volume during the last interglacial based on local sea-level indicators requires that these indicators are corrected for processes that alter local sea level relative to the global average. Although glacial isostatic adjustment is generally accounted for, global scale dynamic changes in topography driven by convective mantle flow are generally not considered. We use numerical models of mantle flow to quantify vertical deflections caused by dynamic topography and compare predictions at passive margins to a globally distributed set of last interglacial sea-level markers. The deflections predicted as a result of dynamic topography are significantly correlated with marker elevations (>95% probability) and are consistent with construction and preservation attributes across marker types. We conclude that a dynamic topography signal is present in the elevation of last interglacial sea-level records and that the signal must be accounted for in any effort to determine peak global mean sea level during the last interglacial to within an accuracy of several meters. PMID:28695210

Scanning-slit topography in patients with keratoconus.

PubMed

Módis, László; Németh, Gábor; Szalai, Eszter; Flaskó, Zsuzsa; Seitz, Berthold

2017-01-01

To evaluate the anterior and posterior corneal surfaces using scanning-slit topography and to determine the diagnostic ability of the measured corneal parameters in keratoconus. Orbscan II measurements were taken in 39 keratoconic corneas previously diagnosed by corneal topography and in 39 healthy eyes. The central minimum, maximum, and astigmatic simulated keratometry (K) and anterior axial power values were determined. Spherical and cylindrical mean power diopters were obtained at the central and at the steepest point of the cornea both on anterior and on posterior mean power maps. Pachymetry evaluations were taken at the center and paracentrally in the 3 mm zone from the center at a location of every 45 degrees. Receiver operating characteristic (ROC) analysis was used to determine the best cut-off values and to evaluate the utility of the measured parameters in identifying patients with keratoconus. The minimum, maximum and astigmatic simulated K readings were 44.80±3.06 D, 47.17±3.67 D and 2.42±1.84 D respectively in keratoconus patients and these values differed significantly ( P <0.0001 for all comparisons) from healthy subjects. For all pachymetry measurements and for anterior and posterior mean power values significant differences were found between the two groups. Moreover, anterior central cylindrical power had the best discrimination ability (area under the ROC curve=0.948). The results suggest that scanning-slit topography and pachymetry are accurate methods both for keratoconus screening and for confirmation of the diagnosis.

Development of a surface topography instrument for automotive textured steel plate

NASA Astrophysics Data System (ADS)

Wang, Zhen; Wang, Shenghuai; Chen, Yurong; Xie, Tiebang

2010-08-01

The surface topography of automotive steel plate is decisive to its stamping, painting and image clarity performances. For measuring this kind of surface topography, an instrument has been developed based on the principle of vertical scanning white light microscopy interference principle. The microscopy interference system of this instrument is designed based on the structure of Linnik interference microscopy. The 1D worktable of Z direction is designed and introduced in details. The work principle of this instrument is analyzed. In measuring process, the interference microscopy is derived as a whole and the measured surface is scanned in vertical direction. The measurement accuracy and validity is verified by templates. Surface topography of textured steel plate is also measured by this instrument.

Linking Observations of Dynamic Topography from Oceanic and Continental Realms around Australia

NASA Astrophysics Data System (ADS)

Czarnota, K.; Hoggard, M. J.; White, N.; Winterbourne, J.

2012-04-01

In the last decade, there has been growing interest in predicting the spatial and temporal evolution of dynamic topography (i.e. the surface manifestation of mantle convection). By directly measuring Neogene and Quaternary dynamic topography around Australia's passive margins we assess the veracity of these predictions and the interplay between mantle convection and plate motion. We mapped the present dynamic topography by carefully measuring residual topography of oceanic lithosphere adjacent to passive margins. This map provides a reference with respect to which the relative record of vertical motions, preserved within the stratigraphic architecture of the margins, can be interpreted. We carefully constrained the temporal record of vertical motions along Australia's Northwest Shelf by backstripping Neogene carbonate clinoform rollover trajectories in order to minimise paleobathymetric errors. Elsewhere, we compile temporal constraints from published literature. Three principal insights emerge from our analysis. First, the present-day drawn-down residual topography of Australia, cannot be approximated by a regional tilt down towards the northeast, as previously hypothesised. The south-western and south-eastern corners of Australia are at negligible to slightly positive residual topography which slopes down towards Australia's northern margin and the Great Australian Bight. Secondly, the record of passive margin subsidence suggests drawdown across northern Australia commenced synchronously at 8±2 Ma. The amplitude of this synchronous drawdown corresponds to the amplitude of oceanic residual topography, indicating northern Australia was at an unperturbed dynamic elevation until drawdown commenced. The synchronicity of this subsidence suggests that the Australian plate has not been affected by a southward propagating wave of drawdown, despite Australia's rapid northward motion towards the subduction realm in south-east Asia. In contrast, it appears the mantle

Sintered silver joints via controlled topography of electronic packaging subcomponents

DOEpatents

Wereszczak, Andrew A.

2014-09-02

Disclosed are sintered silver bonded electronic package subcomponents and methods for making the same. Embodiments of the sintered silver bonded EPSs include topography modification of one or more metal surfaces of semiconductor devices bonded together by the sintered silver joint. The sintered silver bonded EPSs include a first semiconductor device having a first metal surface, the first metal surface having a modified topography that has been chemically etched, grit blasted, uniaxial ground and/or grid sliced connected to a second semiconductor device which may also include a first metal surface with a modified topography, a silver plating layer on the first metal surface of the first semiconductor device and a silver plating layer on the first metal surface of the second semiconductor device and a sintered silver joint between the silver plating layers of the first and second semiconductor devices which bonds the first semiconductor device to the second semiconductor device.

EAARL topography-Potato Creek watershed, Georgia, 2010

USGS Publications Warehouse

Bonisteel-Cormier, J.M.; Nayegandhi, Amar; Fredericks, Xan; Jones, J.W.; Wright, C.W.; Brock, J.C.; Nagle, D.B.

2011-01-01

This DVD contains lidar-derived first-surface (FS) and bare-earth (BE) topography GIS datasets of a portion of the Potato Creek watershed in the Apalachicola-Chattahoochee-Flint River basin, Georgia. These datasets were acquired on February 27, 2010.

Oceanic residual depth measurements, the plate cooling model, and global dynamic topography

NASA Astrophysics Data System (ADS)

Hoggard, Mark J.; Winterbourne, Jeff; Czarnota, Karol; White, Nicky

2017-03-01

Convective circulation of the mantle causes deflections of the Earth's surface that vary as a function of space and time. Accurate measurements of this dynamic topography are complicated by the need to isolate and remove other sources of elevation, arising from flexure and lithospheric isostasy. The complex architecture of continental lithosphere means that measurement of present-day dynamic topography is more straightforward in the oceanic realm. Here we present an updated methodology for calculating oceanic residual bathymetry, which is a proxy for dynamic topography. Corrections are applied that account for the effects of sedimentary loading and compaction, for anomalous crustal thickness variations, for subsidence of oceanic lithosphere as a function of age and for non-hydrostatic geoid height variations. Errors are formally propagated to estimate measurement uncertainties. We apply this methodology to a global database of 1936 seismic surveys located on oceanic crust and generate 2297 spot measurements of residual topography, including 1161 with crustal corrections. The resultant anomalies have amplitudes of ±1 km and wavelengths of ˜1000 km. Spectral analysis of our database using cross-validation demonstrates that spherical harmonics up to and including degree 30 (i.e., wavelengths down to 1300 km) are required to accurately represent these observations. Truncation of the expansion at a lower maximum degree erroneously increases the amplitude of inferred long-wavelength dynamic topography. There is a strong correlation between our observations and free-air gravity anomalies, magmatism, ridge seismicity, vertical motions of adjacent rifted margins, and global tomographic models. We infer that shorter wavelength components of the observed pattern of dynamic topography may be attributable to the presence of thermal anomalies within the shallow asthenospheric mantle.

A Global Study of Inner Core Boundary Topography and its Temporal Variations

NASA Astrophysics Data System (ADS)

Ibourichene, A.; Romanowicz, B. A.

2015-12-01

The inner core boundary (ICB) separates the solid inner core from the surrounding liquid outer core. Its detailed properties, such as its shape, the density jump across it or its topography are key for understanding the dynamics of the core and, ultimately, the generation and sustained character of the Earth's magnetic field. The determination of the ICB topography and its variation with time could also enhance our understanding of the inner core growth and its past history.Seismology makes use of two phases to study the shallow inner core : the PKiKP, reflected at the ICB and the PKIKP, refracted into the inner core. The PKiKP/PKIKP amplitude ratio and the travel time residual of these phases characterize the vicinity of the ICB and may help constrain ICB topography. Different studies propose various wavelengths for this topography: from hundreds of meters to tens of kilometers. Several parameters can affect PKiKP/PKIKP amplitude ratios and the corresponding differential travel time, such as the quality factor of the shallow inner core, the density jump at the ICB, the geometry of the ray paths or even the reflection coefficient at the ICB. We present a global map of PKiKP/PKIKP amplitude ratios and differential travel times filtered in different pass-bands, with regional densification based, in particular, on the relatively short wavelength sampling afforded by large aperture broadband arrays, such as USArray, and discuss their spatial variability and interpretation in terms of ICB topography, as appropriate.We also have assembled a catalog of high quality doublets which provide a reference for the stability of the measurements, and point to possible time variability of the topography.

What Makes a Difference: Early Head Start Evaluation Findings in a Developmental Context

ERIC Educational Resources Information Center

Love, John M.; Chazan-Cohen, Rachel; Raikes, Helen; Brooks-Gunn, Jeanne

2013-01-01

The federal Early Head Start (EHS) program began in 1995, and a randomized trial was conducted to evaluate the efficacy of 17 EHS programs. In all, 3,001 low-income families (35% African American, 24% Hispanic, and 37% White) with a pregnant women or an infant under the age of 12 months were randomly assigned to a treatment or control group (with…

Estimating the Effects of Head Start on Parenting and Child Maltreatment

PubMed Central

Waldfogel, Jane; Brooks-Gunn, Jeanne

2011-01-01

We examine the effects of Head Start participation on parenting and child maltreatment in a large and diverse sample of low-income families in large U.S. cities (N = 2,807), using rich data from the Fragile Families and Child Wellbeing Study (FFCWS). To address the issue of selection bias, we employ several analytic approaches, including logistic regressions with a rich set of pretreatment controls as well as propensity score matching models, comparing the effects of Head Start to any other arrangements as well as specific types of other arrangements. We find that compared to children who did not attend Head Start, children who did attend Head Start are less likely to have low access to learning materials and less likely to experience spanking by their parents at age five. Moreover, we find that the effects of Head Start vary depending on the specific type of other child care arrangements to which they are compared, with the most consistently beneficial protective effects seen when Head Start is compared to being home in exclusively parental care. PMID:23788823

Role of percent tissue altered on ectasia after LASIK in eyes with suspicious topography.

PubMed

Santhiago, Marcony R; Smadja, David; Wilson, Steven E; Krueger, Ronald R; Monteiro, Mario L R; Randleman, J Bradley

2015-04-01

To investigate the association of the percent tissue altered (PTA) with the occurrence of ectasia after LASIK in eyes with suspicious preoperative corneal topography. This retrospective comparative case-control study compared associations of reported ectasia risk factors in 129 eyes, including 57 eyes with suspicious preoperative Placido-based corneal topography that developed ectasia after LASIK (suspect ectasia group), 32 eyes with suspicious topography that remained stable for at least 3 years after LASIK (suspect control group), and 30 eyes that developed ectasia with bilateral normal topography (normal topography ectasia group). Groups were subdivided based on topographic asymmetry into high- or low-suspect groups. The PTA, preoperative central corneal thickness (CCT), residual stromal bed (RSB), and age (years) were evaluated in univariate and multivariate analyses. Average PTA values for normal topography ectasia (45), low-suspect ectasia (39), high-suspect ectasia (36), low-suspect control (32), and high-suspect control (29) were significantly different from one another in all comparisons (P < .003) except high- and low-suspect ectasia groups (P = .033), and presented the highest discriminative capability of all variables evaluated. Age was only significantly different between the high-suspect ectasia and normal topography ectasia groups, and CCT was not significantly different between any groups. Stepwise logistic regression revealed the PTA as the most significant independent variable (P < .0001), with RSB the next most significant parameter. There remains a significant correlation between PTA values and ectasia risk after LASIK, even in eyes with suspicious corneal topography. Less tissue alteration, or a lower PTA value, was necessary to induce ectasia in eyes with more remarkable signs of topographic abnormality, and PTA provided better discriminative capabilities than RSB for all study populations. Copyright 2015, SLACK Incorporated.

Modelling low-frequency volcanic earthquakes in a viscoelastic medium with topography

NASA Astrophysics Data System (ADS)

Jousset, Philippe; Neuberg, Jürgen; Jolly, Arthur

2004-11-01

Magma properties are fundamental to explain the volcanic eruption style as well as the generation and propagation of seismic waves. This study focusses on magma properties and rheology and their impact on low-frequency volcanic earthquakes. We investigate the effects of anelasticity and topography on the amplitudes and spectra of synthetic low-frequency earthquakes. Using a 2-D finite-difference scheme, we model the propagation of seismic energy initiated in a fluid-filled conduit embedded in a homogeneous viscoelastic medium with topography. We model intrinsic attenuation by linear viscoelastic theory and we show that volcanic media can be approximated by a standard linear solid (SLS) for seismic frequencies above 2 Hz. Results demonstrate that attenuation modifies both amplitudes and dispersive characteristics of low-frequency earthquakes. Low frequency volcanic earthquakes are dispersive by nature; however, if attenuation is introduced, their dispersion characteristics will be altered. The topography modifies the amplitudes, depending on the position of the seismographs at the surface. This study shows that we need to take into account attenuation and topography to interpret correctly observed low-frequency volcanic earthquakes. It also suggests that the rheological properties of magmas may be constrained by the analysis of low-frequency seismograms.

Central Topography of Cranial Motor Nuclei Controlled by Differential Cadherin Expression

PubMed Central

Astick, Marc; Tubby, Kristina; Mubarak, Waleed M.; Guthrie, Sarah; Price, Stephen R.

2014-01-01

Summary Neuronal nuclei are prominent, evolutionarily conserved features of vertebrate central nervous system (CNS) organization [1]. Nuclei are clusters of soma of functionally related neurons and are located in highly stereotyped positions. Establishment of this CNS topography is critical to neural circuit assembly. However, little is known of either the cellular or molecular mechanisms that drive nucleus formation during development, a process termed nucleogenesis [2–5]. Brainstem motor neurons, which contribute axons to distinct cranial nerves and whose functions are essential to vertebrate survival, are organized exclusively as nuclei. Cranial motor nuclei are composed of two main classes, termed branchiomotor/visceromotor and somatomotor [6]. Each of these classes innervates evolutionarily distinct structures, for example, the branchial arches and eyes, respectively. Additionally, each class is generated by distinct progenitor cell populations and is defined by differential transcription factor expression [7, 8]; for example, Hb9 distinguishes somatomotor from branchiomotor neurons. We characterized the time course of cranial motornucleogenesis, finding that despite differences in cellular origin, segregation of branchiomotor and somatomotor nuclei occurs actively, passing through a phase of each being intermingled. We also found that differential expression of cadherin cell adhesion family members uniquely defines each motor nucleus. We show that cadherin expression is critical to nucleogenesis as its perturbation degrades nucleus topography predictably. PMID:25308074

The Ohio State 1991 geopotential and sea surface topography harmonic coefficient models

NASA Technical Reports Server (NTRS)

Rapp, Richard H.; Wang, Yan Ming; Pavlis, Nikolaos K.

1991-01-01

The computation is described of a geopotential model to deg 360, a sea surface topography model to deg 10/15, and adjusted Geosat orbits for the first year of the exact repeat mission (ERM). This study started from the GEM-T2 potential coefficient model and it's error covariance matrix and Geosat orbits (for 22 ERMs) computed by Haines et al. using the GEM-T2 model. The first step followed the general procedures which use a radial orbit error theory originally developed by English. The Geosat data was processed to find corrections to the a priori geopotential model, corrections to a radial orbit error model for 76 Geosat arcs, and coefficients of a harmonic representation of the sea surface topography. The second stage of the analysis took place by doing a combination of the GEM-T2 coefficients with 30 deg gravity data derived from surface gravity data and anomalies obtained from altimeter data. The analysis has shown how a high degree spherical harmonic model can be determined combining the best aspects of two different analysis techniques. The error analysis was described that has led to the accuracy estimates for all the coefficients to deg 360. Significant work is needed to improve the modeling effort.

Assessing the Performance of LVIS Waveform Lidar Topography and Canopy Structure Measurements in Gabon

NASA Astrophysics Data System (ADS)

Hofton, M. A.; Blair, J. B.; Rabine, D.; Brooks, C.; Cornejo, H.; Story, S.

2016-12-01

In February-March 2016, NASA's Land, Vegetation and Ice Sensor (LVIS) was used to image sub-canopy topography, canopy topography and structure at several sites in Gabon. Data were collected as part of the NASA and ESA Afrisar Campaign, a joint remote sensing mission involving multiple airborne and ground-based data collection activities that support the calibration and validation of future spaceborne missions, particularly GEDI, NISAR and BIOMASS, as well as other investigations. LVIS is a wide-swath, medium-footprint, waveform recording laser altimeter (lidar) sensor that can collect contiguous data within a 2 km-wide swath using 20m wide footprints from 10km altitude. For the Gabon deployment, the sensor was mounted in the NASA Langley King Air aircraft and flown at 8 km altitude over five, 70x15km-wide areas and along multiple country-wide transects. Data products include footprint-level canopy height, ground topography and canopy metrics, as well as vertically and horizontally-geolocated lidar return waveforms that enable end users to produce additional georeferenced data products as needed. We present a summary of the data products from the campaign, as well as a performance assessment of the ground and canopy structure data using available airborne and ground based data. Uses of the data include the simulation of GEDI-like data and the derivation of canopy height and profile metric algorithms for implementation in GEDI level2 products, as well as to improve our understanding of ground-finding errors in dense vegetation environments from waveform lidar.

Geoid, topography, and convection-driven crustal deformation on Venus

NASA Technical Reports Server (NTRS)

Simons, Mark; Hager, Bradford H.; Solomon, Sean C.

1992-01-01

High-resolution Magellan images and altimetry of Venus reveal a wide range of styles and scales of surface deformation that cannot readily be explained within the classical terrestrial plate tectonic paradigm. The high correlation of long-wavelength topography and gravity and the large apparent depths of compensation suggest that Venus lacks an upper-mantle low-viscosity zone. A key difference between Earth and Venus may be the degree of coupling between the convecting mantle and the overlying lithosphere. Mantle flow should then have recognizable signatures in the relationships between surface topography, crustal deformation, and the observed gravity field.

Determining relative contributions of vegetation and topography to burn severity from LANDSAT imagery.

PubMed

Wu, Zhiwei; He, Hong S; Liang, Yu; Cai, Longyan; Lewis, Bernard J

2013-10-01

Fire is a dominant process in boreal forest landscapes and creates a spatial patch mosaic with different burn severities and age classes. Quantifying effects of vegetation and topography on burn severity provides a scientific basis on which forest fire management plans are developed to reduce catastrophic fires. However, the relative contribution of vegetation and topography to burn severity is highly debated especially under extreme weather conditions. In this study, we hypothesized that relationships of vegetation and topography to burn severity vary with fire size. We examined this hypothesis in a boreal forest landscape of northeastern China by computing the burn severity of 24 fire patches as the difference between the pre- and post-fire Normalized Difference Vegetation Index obtained from two Landsat TM images. The vegetation and topography to burn severity relationships were evaluated at three fire-size levels of small (<100 ha, n = 12), moderate (100-1,000 ha, n = 9), and large (>1,000 ha, n = 3). Our results showed that vegetation and topography to burn severity relationships were fire-size-dependent. The burn severity of small fires was primary controlled by vegetation conditions (e.g., understory cover), and the burn severity of large fires was strongly influenced by topographic conditions (e.g., elevation). For moderate fires, the relationships were complex and indistinguishable. Our results also indicated that the pattern trends of relative importance for both vegetation and topography factors were not dependent on fire size. Our study can help managers to design fire management plans according to vegetation characteristics that are found important in controlling burn severity and prioritize management locations based on the relative importance of vegetation and topography.

The effect of topography of upper-mantle discontinuities on SS precursors

NASA Astrophysics Data System (ADS)

Koroni, Maria; Trampert, Jeannot

2016-01-01

Using the spectral-element method, we explored the effect of topography of upper-mantle discontinuities on the traveltimes of SS precursors recorded on transverse component seismograms. The latter are routinely used to infer the topography of mantle transition zone discontinuities. The step from precursory traveltimes to topographic changes is mainly done using linearised ray theory, or sometimes using finite-frequency kernels. We simulated exact seismograms in 1-D and 3-D elastic models of the mantle. In a second simulation, we added topography to the discontinuities. We compared the waveforms obtained with and without topography by cross correlation of the SS precursors. Since we did not add noise, the precursors are visible in individual seismograms without the need of stacking. The resulting time anomalies were then converted into topographic variations and compared to the original topographic models. Based on the correlation between initial and inferred models, and provided that ray coverage is good, we found that linearised ray theory gives a relatively good idea on the location of the uplifts and depressions of the discontinuities. It seriously underestimates the amplitude of the topographic variations by a factor ranging between 2 and 7. Real data depend on the 3-D elastic structure and the topography. All studies to date correct for the 3-D elastic effects assuming that the traveltimes can be linearly decomposed into a structure and a discontinuity part. We found a strong non-linearity in this decomposition which cannot be modelled without a fully non-linear inversion for elastic structure and discontinuities simultaneously.

Spatial Topography of Individual-Specific Cortical Networks Predicts Human Cognition, Personality, and Emotion.

PubMed

Kong, Ru; Li, Jingwei; Orban, Csaba; Sabuncu, Mert R; Liu, Hesheng; Schaefer, Alexander; Sun, Nanbo; Zuo, Xi-Nian; Holmes, Avram J; Eickhoff, Simon B; Yeo, B T Thomas

2018-06-06

Resting-state functional magnetic resonance imaging (rs-fMRI) offers the opportunity to delineate individual-specific brain networks. A major question is whether individual-specific network topography (i.e., location and spatial arrangement) is behaviorally relevant. Here, we propose a multi-session hierarchical Bayesian model (MS-HBM) for estimating individual-specific cortical networks and investigate whether individual-specific network topography can predict human behavior. The multiple layers of the MS-HBM explicitly differentiate intra-subject (within-subject) from inter-subject (between-subject) network variability. By ignoring intra-subject variability, previous network mappings might confuse intra-subject variability for inter-subject differences. Compared with other approaches, MS-HBM parcellations generalized better to new rs-fMRI and task-fMRI data from the same subjects. More specifically, MS-HBM parcellations estimated from a single rs-fMRI session (10 min) showed comparable generalizability as parcellations estimated by 2 state-of-the-art methods using 5 sessions (50 min). We also showed that behavioral phenotypes across cognition, personality, and emotion could be predicted by individual-specific network topography with modest accuracy, comparable to previous reports predicting phenotypes based on connectivity strength. Network topography estimated by MS-HBM was more effective for behavioral prediction than network size, as well as network topography estimated by other parcellation approaches. Thus, similar to connectivity strength, individual-specific network topography might also serve as a fingerprint of human behavior.

Surface topography during neural stem cell differentiation regulates cell migration and cell morphology.

PubMed

Czeisler, Catherine; Short, Aaron; Nelson, Tyler; Gygli, Patrick; Ortiz, Cristina; Catacutan, Fay Patsy; Stocker, Ben; Cronin, James; Lannutti, John; Winter, Jessica; Otero, José Javier

2016-12-01

We sought to determine the contribution of scaffold topography to the migration and morphology of neural stem cells by mimicking anatomical features of scaffolds found in vivo. We mimicked two types of central nervous system scaffolds encountered by neural stem cells during development in vitro by constructing different diameter electrospun polycaprolactone (PCL) fiber mats, a substrate that we have shown to be topographically similar to brain scaffolds. We compared the effects of large fibers (made to mimic blood vessel topography) with those of small-diameter fibers (made to mimic radial glial process topography) on the migration and differentiation of neural stem cells. Neural stem cells showed differential migratory and morphological reactions with laminin in different topographical contexts. We demonstrate, for the first time, that neural stem cell biological responses to laminin are dependent on topographical context. Large-fiber topography without laminin prevented cell migration, which was partially reversed by treatment with rock inhibitor. Cell morphology complexity assayed by fractal dimension was inhibited in nocodazole- and cytochalasin-D-treated neural precursor cells in large-fiber topography, but was not changed in small-fiber topography with these inhibitors. These data indicate that cell morphology has different requirements on cytoskeletal proteins dependent on the topographical environment encountered by the cell. We propose that the physical structure of distinct scaffolds induces unique signaling cascades that regulate migration and morphology in embryonic neural precursor cells. J. Comp. Neurol. 524:3485-3502, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Tuning cell adhesion on polymeric and nanocomposite surfaces: Role of topography versus superhydrophobicity.

PubMed

Zangi, Sepideh; Hejazi, Iman; Seyfi, Javad; Hejazi, Ehsan; Khonakdar, Hossein Ali; Davachi, Seyed Mohammad

2016-06-01

Development of surface modification procedures which allow tuning the cell adhesion on the surface of biomaterials and devices is of great importance. In this study, the effects of different topographies and wettabilities on cell adhesion behavior of polymeric surfaces are investigated. To this end, an improved phase separation method was proposed to impart various wettabilities (hydrophobic and superhydrophobic) on polypropylene surfaces. Surface morphologies and compositions were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Cell culture was conducted to evaluate the adhesion of 4T1 mouse mammary tumor cells. It was found that processing conditions such as drying temperature is highly influential in cell adhesion behavior due to the formation of an utterly different surface topography. It was concluded that surface topography plays a more significant role in cell adhesion behavior rather than superhydrophobicity since the nano-scale topography highly inhibited the cell adhesion as compared to the micro-scale topography. Such cell repellent behavior could be very useful in many biomedical devices such as those in drug delivery and blood contacting applications as well as biosensors. Copyright © 2016 Elsevier B.V. All rights reserved.

The differential regulation of osteoblast and osteoclast activity by surface topography of hydroxyapatite coatings.

PubMed

Costa, Daniel O; Prowse, Paul D H; Chrones, Tom; Sims, Stephen M; Hamilton, Douglas W; Rizkalla, Amin S; Dixon, S Jeffrey

2013-10-01

The behavior of bone cells is influenced by the surface chemistry and topography of implants and scaffolds. Our purpose was to investigate how the topography of biomimetic hydroxyapatite (HA) coatings influences the attachment and differentiation of osteoblasts, and the resorptive activity of osteoclasts. Using strategies reported previously, we directly controlled the surface topography of HA coatings on polycaprolactone discs. Osteoblasts and osteoclasts were incubated on HA coatings having distinct isotropic topographies with submicrometer and micro-scale features. Osteoblast attachment and differentiation were greater on more complex, micro-rough HA surfaces (Ra ~2 μm) than on smoother topographies (Ra ~1 μm). In contrast, activity of the osteoclast marker tartrate-resistant acid phosphatase was greater on smoother than on micro-rough surfaces. Furthermore, scanning electron microscopy revealed the presence of resorption lacunae exclusively on smoother HA coatings. Inhibition of resorption on micro-rough surfaces was associated with disruption of filamentous actin sealing zones. In conclusion, HA coatings can be prepared with distinct topographies, which differentially regulate responses of osteoblasts, as well as osteoclastic activity and hence susceptibility to resorption. Thus, it may be possible to design HA coatings that induce optimal rates of bone formation and degradation specifically tailored for different applications in orthopedics and dentistry. Copyright © 2013 Elsevier Ltd. All rights reserved.

Altered Global Signal Topography in Schizophrenia.

PubMed

Yang, Genevieve J; Murray, John D; Glasser, Matthew; Pearlson, Godfrey D; Krystal, John H; Schleifer, Charlie; Repovs, Grega; Anticevic, Alan

2017-11-01

Schizophrenia (SCZ) is a disabling neuropsychiatric disease associated with disruptions across distributed neural systems. Resting-state functional magnetic resonance imaging has identified extensive abnormalities in the blood-oxygen level-dependent signal in SCZ patients, including alterations in the average signal over the brain-i.e. the "global" signal (GS). It remains unknown, however, if these "global" alterations occur pervasively or follow a spatially preferential pattern. This study presents the first network-by-network quantification of GS topography in healthy subjects and SCZ patients. We observed a nonuniform GS contribution in healthy comparison subjects, whereby sensory areas exhibited the largest GS component. In SCZ patients, we identified preferential GS representation increases across association regions, while sensory regions showed preferential reductions. GS representation in sensory versus association cortices was strongly anti-correlated in healthy subjects. This anti-correlated relationship was markedly reduced in SCZ. Such shifts in GS topography may underlie profound alterations in neural information flow in SCZ, informing development of pharmacotherapies. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

A steep peripheral ring in irregular cornea topography, real or an instrument error?

PubMed

Galindo-Ferreiro, Alicia; Galvez-Ruiz, Alberto; Schellini, Silvana A; Galindo-Alonso, Julio

2016-01-01

To demonstrate that the steep peripheral ring (red zone) on corneal topography after myopic laser in situ keratomileusis (LASIK) could possibly due to instrument error and not always to a real increase in corneal curvature. A spherical model for the corneal surface and modifying topography software was used to analyze the cause of an error due to instrument design. This study involved modification of the software of a commercially available topographer. A small modification of the topography image results in a red zone on the corneal topography color map. Corneal modeling indicates that the red zone could be an artifact due to an instrument-induced error. The steep curvature changes after LASIK, signified by the red zone, could be also an error due to the plotting algorithms of the corneal topographer, besides a steep curvature change.

Venus gravity and topography: 60th degree and order model

NASA Technical Reports Server (NTRS)

Konopliv, A. S.; Borderies, N. J.; Chodas, P. W.; Christensen, E. J.; Sjogren, W. L.; Williams, B. G.; Balmino, G.; Barriot, J. P.

1993-01-01

We have combined the most recent Pioneer Venus Orbiter (PVO) and Magellan (MGN) data with the earlier 1978-1982 PVO data set to obtain a new 60th degree and order spherical harmonic gravity model and a 120th degree and order spherical harmonic topography model. Free-air gravity maps are shown over regions where the most marked improvement has been obtained (Ishtar-Terra, Alpha, Bell and Artemis). Gravity versus topography relationships are presented as correlations per degree and axes orientation.

Head Start: Undercover Testing Finds Fraud and Abuse at Selected Head Start Centers. Testimony before the Committee on Education and Labor, House of Representatives. GAO-10-733T

ERIC Educational Resources Information Center

Kutz, Gregory D.

2010-01-01

The Head Start program, overseen by the Department of Health and Human Services and administered by the Office of Head Start, provides child development services primarily to low-income families and their children. Federal law allows up to 10 percent of enrolled families to have incomes above 130 percent of the poverty line--GAO (Government…

Histopathology of femoral head donations: a retrospective review of 6161 cases.

PubMed

Mackie, Katherine E; Zhou, Ziqiang; Robbins, Peter; Bulsara, Max; Zheng, Ming H

2011-08-17

Although total hip arthroplasty is one of the most common orthopaedic surgical procedures, it remains unclear whether histopathological examination of the excised femoral head adds to the quality of patient care. We propose that assessment of femoral heads resected during total hip arthroplasty and donated for allograft use may provide a profile of femoral head pathology that benefits total hip arthroplasty patients and bone donors. We retrospectively analyzed the histological findings reported for 6161 femoral heads donated for allograft use between 1993 and 2006. Specimens obtained during total hip arthroplasty and specimens donated at death were reviewed. Follow-up investigations that resulted from abnormal histopathological findings were also reviewed. The Western Australian Cancer Registry was used to determine whether patients with a suspected neoplasm were subsequently diagnosed with such a disease. A retrospective review of the histopathological findings was conducted to evaluate and reclassify all previous observations of abnormalities. One hundred and five femoral heads demonstrated abnormal or reactive histopathological features not reported prior to surgery and were rejected for allograft use. A reactive lymphocytic infiltrate, most likely due to osteoarthritis, was the most commonly identified feature (forty-five cases). Other features observed in twenty-seven cases were also most likely due to the presence of severe osteoarthritis. Ten femoral heads demonstrated plasmacytosis, which may have been related to osteoarthritis. Two patients were diagnosed with Paget's disease, and two, with rheumatoid arthritis. Nineteen patients had a suspected neoplasm. Of these nineteen, eight cases of non-Hodgkin's lymphoma or chronic lymphocytic leukemia and one case of myelodysplastic syndrome were confirmed on further investigation. One subsequently confirmed malignancy was detected per 770 femoral heads examined. Our findings indicate that, even with a detailed

"Head up and eyes out" advances in head mounted displays capabilities

NASA Astrophysics Data System (ADS)

Cameron, Alex

2013-06-01

There are a host of helmet and head mounted displays, flooding the market place with displays which provide what is essentially a mobile computer display. What sets aviators HMDs apart is that they provide the user with accurate conformal information embedded in the pilots real world view (see through display) where the information presented is intuitive and easy to use because it overlays the real world (mix of sensor imagery, symbolic information and synthetic imagery) and enables them to stay head up, eyes out, - improving their effectiveness, reducing workload and improving safety. Such systems are an enabling technology in the provision of enhanced Situation Awareness (SA) and reducing user workload in high intensity situations. Safety Is Key; so the addition of these HMD functions cannot detract from the aircrew protection functions of conventional aircrew helmets which also include life support and audio communications. These capabilities are finding much wider application in new types of compact man mounted audio/visual products enabled by the emergence of new families of micro displays, novel optical concepts and ultra-compact low power processing solutions. This papers attempts to capture the key drivers and needs for future head mounted systems for aviation applications.

Implications for anomalous mantle pressure and dynamic topography from lithospheric stress patterns in the North Atlantic Realm

NASA Astrophysics Data System (ADS)

Schiffer, Christian; Nielsen, Søren Bom

2016-08-01

With convergent plate boundaries at some distance, the sources of the lithospheric stress field of the North Atlantic Realm are mainly mantle tractions at the base of the lithosphere, lithospheric density structure and topography. Given this, we estimate horizontal deviatoric stresses using a well-established thin sheet model in a global finite element representation. We adjust the lithospheric thickness and the sub-lithospheric pressure iteratively, comparing modelled in plane stress with the observations of the World Stress Map. We find that an anomalous mantle pressure associated with the Iceland and Azores melt anomalies, as well as topography are able to explain the general pattern of the principle horizontal stress directions. The Iceland melt anomaly overprints the classic ridge push perpendicular to the Mid Atlantic ridge and affects the conjugate passive margins in East Greenland more than in western Scandinavia. The dynamic support of topography shows a distinct maximum of c. 1000 m in Iceland and amounts <150 m along the coast of south-western Norway and 250-350 m along the coast of East Greenland. Considering that large areas of the North Atlantic Realm have been estimated to be sub-aerial during the time of break-up, two components of dynamic topography seem to have affected the area: a short-lived, which affected a wider area along the rift system and quickly dissipated after break-up, and a more durable in the close vicinity of Iceland. This is consistent with the appearance of a buoyancy anomaly at the base of the North Atlantic lithosphere at or slightly before continental breakup, relatively fast dissipation of the fringes of this, and continued melt generation below Iceland.

A Study of the Effects of Seafloor Topography on Tsunami Propagation

NASA Astrophysics Data System (ADS)

Ohata, T.; Mikada, H.; Goto, T.; Takekawa, J.

2011-12-01

For tsunami disaster mitigation, we consider the phenomena related to tsunami in terms of the generation, propagation, and run-up to the coast. With consideration for these three phenomena, we have to consider tsunami propagation to predict the arrival time and the run-up height of tsunami. Numerical simulations of tsunami that propagates from the source location to the coast have been widely used to estimate these important parameters. When a tsunami propagates, however, reflected and scattered waves arrive as later phases of tsunami. These waves are generated by the changes of water depth, and could influence the height estimation, especially in later phases. The maximum height of tsunami could be observed not as the first arrivals but as the later phases, therefore it is necessary to consider the effects of the seafloor topography on tsunami propagation. Since many simulations, however, mainly focus on the prediction of the first arrival times and the initial height of tsunami, it is difficult to simulate the later phases that are important for the tsunami disaster mitigation in the conventional methods. In this study, we investigate the effects of the seafloor topography on tsunami propagation after accommodating a tsunami simulation to the superposition of reflected and refracted waves caused by the smooth changes of water depths. Developing the new numerical code, we consider how the effects of the sea floor topography affect on the tsunami propagation, comparing with the tsunami simulated by the conventional method based on the liner long wave theory. Our simulation employs the three dimensional in-equally spaced grids in finite difference method (FDM) to introduce the real seafloor topography. In the simulation, we import the seafloor topography from the real bathymetry data near the Sendai-Bay, off the northeast Tohoku region, Japan, and simulate the tsunami propagation over the varying seafloor topography there. Comparing with the tsunami simulated by the

The Geoid: Effect of compensated topography and uncompensated oceanic trenches

USGS Publications Warehouse

Chase, C.G.; McNutt, Marcia K.

1982-01-01

The geoid is becoming increasingly important in interpretation of global tectonics. Most of the topography of the earth is isostatically compensated, so removal of its effect from the geoid is appropriate before tectonic modeling. The oceanic trenches, however, are dynamically depressed features and cannot be isostatically compensated in the classical way. Continental topography compensated at 35 km gives intracontinental geoidal undulations of up to 15 m over mountain ranges in a spherical harmonic expansion to order and degree 22. Oceanic topography compensated at 40 km, reasonable for the thermally supported long wavelengths, matches the +10 m difference between old continents and old oceans in a detailed NASA/GSFC geoid. Removing the assumed compensation for the oceanic trenches leaves negative anomalies of up to 9 m amplitude caused by their uncompensated mass deficit. This mass deficit acts as a partial "regional compensation" for the excess mass of the subducting slabs, and partly explains why geoidal (and gravity) anomalies over the cold slabs are less than thermal models predict.

Active head rotations and eye-head coordination

NASA Technical Reports Server (NTRS)

Zangemeister, W. H.; Stark, L.

1981-01-01

It is pointed out that head movements play an important role in gaze. The interaction between eye and head movements involves both their shared role in directing gaze and the compensatory vestibular ocular reflex. The dynamics of head trajectories are discussed, taking into account the use of parameterization to obtain the peak velocity, peak accelerations, the times of these extrema, and the duration of the movement. Attention is given to the main sequence, neck muscle EMG and details of the head-movement trajectory, types of head model accelerations, the latency of eye and head movement in coordinated gaze, gaze latency as a function of various factors, and coordinated gaze types. Clinical examples of gaze-plane analysis are considered along with the instantaneous change of compensatory eye movement (CEM) gain, and aspects of variability.

Smoking Topography Characteristics of Very Low Nicotine Content Cigarettes, With and Without Nicotine Replacement, in Smokers With Schizophrenia and Controls

PubMed Central

Cassidy, Rachel N.; Miller, Mollie E.

2016-01-01

Introduction: Reducing the nicotine content of cigarettes to a minimally addictive level has been proposed as a regulatory strategy for reducing tobacco dependence. However, smokers with schizophrenia (SS) may be prone to changing their smoking topography in efforts to compensate for the reduction in nicotine content. The aims of this study were to compare smoking topography characteristics of usual-brand and very low nicotine content (VLNC) cigarettes in SS and control smokers without psychiatric illness (CS), and to determine whether nicotine replacement reversed any changes in topography produced by VLNC cigarettes. Methods: Using a within-subjects, counter-balanced design, SS (n = 27) and CS (n = 23) smoked usual brand cigarettes, VLNC cigarettes while wearing placebo patches (VLNC + PLA), or VLNC cigarettes while wearing transdermal nicotine patches totaling 42mg (VLNC + NIC) during 5-hour ad libitum smoking sessions. Cigarettes were smoked through topography measurement devices. Results: Across conditions, SS smoked more puffs per session and per cigarette, had higher cigarette volumes, and had shorter inter-puff intervals than CS (Ps < .01). During VLNC cigarette sessions, puff duration increased and time between puffs decreased, but participants smoked fewer puffs, resulting in a net decrease in cigarette and total session volume (Ps < .001). There were no significant interactions between group and condition. Conclusions: These findings indicate that acute use of VLNC cigarettes does not increase intensity of smoking in SS, and support the feasibility of a nicotine reduction policy. Implications: Reducing the nicotine in cigarettes to a minimally addictive level has been proposed as a means of reducing tobacco dependence. However, smokers, particularly those with schizophrenia (SS) may alter their puffing in an attempt to extract more nicotine from VLNC cigarettes. This study compared smoking topography of usual brand versus VLNC cigarettes, combined with

Airborne Instrument Simulator for the Lidar Surface Topography (LIST) Mission

NASA Technical Reports Server (NTRS)

Yu, Anthony W.; Krainak, Michael A.; Harding, David J.; Abshire, James B.; Sun, Xiaoli; Cavanaugh, John; Valett, Susan; Ramos-Izquierdo, Luis

2010-01-01

In 2007, the National Research Council (NRC) completed its first decadal survey for Earth science at the request of NASA, NOAA, and USGS. The Lidar Surface Topography (LIST) mission is one of fifteen missions recommended by NRC, whose primary objectives are to map global topography and vegetation structure at 5 m spatial resolution, and to acquire global coverage with a few years. NASA Goddard conducted an initial mission concept study for the LIST mission 2007, and developed the initial measurement requirements for the mission.

Airborne Lidar Simulator for the Lidar Surface Topography (LIST) Mission

NASA Technical Reports Server (NTRS)

Yu, Anthony W.; Krainak, Michael A.; Abshire, James B.; Cavanaugh, John; Valett, Susan; Ramos-Izquierdo, Luis

2010-01-01

In 2007, the National Research Council (NRC) completed its first decadal survey for Earth science at the request of NASA, NOAA, and USGS. The Lidar Surface Topography (LIST) mission is one of fifteen missions recommended by NRC, whose primary objectives are to map global topography and vegetation structure at 5 m spatial resolution, and to acquire global surface height mapping within a few years. NASA Goddard conducted an initial mission concept study for the LIST mission in 2007, and developed the initial measurement requirements for the mission.

Outcomes of photorefractive keratectomy in patients with atypical topography.

PubMed

Movahedan, Hossein; Namvar, Ehsan; Farvardin, Mohsen

2017-11-01

Photorefractive keratectomy (PRK) is at risk of serious complications such as corneal ectasia, which can reduce corrected distance visual acuity. The rate of complications of PRK is higher in patients with atypical topography. To determine the outcomes of photorefractive keratectomy in patients with atypical topography. This cross-sectional study was done in 2015 in Shiraz in Iran. We included 85 eyes in this study. The samples were selected using a simple random sampling method. All patients were under evaluation for uncorrected distance visual acuity, corrected distance visual acuity, manifest refraction, corneal topography, central corneal thickness using pentacam, slit-lamp microscopy, and detailed fondus evaluation. The postoperative examination was done 1-7 years after surgery. Data were analyzed using IBM SPSS 21.0 version. To analyze the data, descriptive statistics (frequency, percentage, mean, and standard deviation), chi-square, and independent samples t-test were used. We studied 85 eyes. Among the patients, 23 (27.1%) were male and 62 (72.9%) were female. Mean age of the participants was 28.25±5.55 years. Mean postoperative refraction was - 0.37±0.55 diopters. Keratoconus or corneal ectasia was not reported in any patient in this study. There was no statistically significant difference between SI index before and after operation (p=0.736). Mean preoperative refraction was -3.84 ± 1.46 diopters in males and -4.20±1.96 diopters in females; thus there was not statistically significant difference (p = 0.435). PRK is a safe and efficient photorefractive surgery and is associated with low complication rate in patients with atypical topography.

Flexural isostasy: Constraints from gravity and topography power spectra

NASA Astrophysics Data System (ADS)

Watts, Tony; Moore, James

2017-04-01

We have used the spherical harmonic coefficients that describe the EGM2008 gravity and topography model (Pavlis et al. 2010) to quantify the role of flexural isostasy in contributing to Earth's gravity and topography. Power spectra show that the gravity effect of the topography and its flexural compensation contributes significantly to the observed free-air gravity anomaly field for degree 33-180, which corresponds approximately to wavelengths of 220-1200 km. The best fit is for an elastic thickness of the lithosphere, Te, of 34.0±4.0 km. Smaller values of Te, under-predict while high values of Te, over-predict the observed gravity spectra. The best fit value is a global average and so it is reasonable to speculate that regions exist where Te is both lower and higher. This is confirmed in studies of selected regions such as the Hawaiian-Emperor seamount chain and the Ganges-Himalaya foreland fold and thrust belt where we show that flexural isostatic anomalies are near zero in regions where Te approaches 34 km (e.g. Hawaiian ridge) and of large amplitude in regions of lower (e.g. Emperor) and higher Te (e.g. Ganges-Himalaya). Plate flexure may be significant at higher (180-441) and lower (12-33) degrees, but topography appears either uncompensated or fully compensated at these degrees, irrespective of the actual Te. Nevertheless, all isostatic models under-predict the observed gravity spectra at degree <12 and so we interpret the low order Earth's gravity field as caused by non-isostatic processes due to dynamic motions such as those associated with mantle convection.

Quantifying Variation in Head Start Effects on Young Children's Cognitive and Socio-Emotional Skills Using Data from the National Head Start Impact Study

ERIC Educational Resources Information Center

Bloom, Howard S.; Weiland, Christina

2015-01-01

This paper uses data from the Head Start Impact Study (HSIS), a nationally representative multisite randomized trial, to quantify variation in effects of Head Start during 2002-2003 on children's cognitive and socio-emotional outcomes relative to the effects of other local alternatives, including parent care. We find that (1) treatment and control…

Roles of Fog and Topography in Redwood Forest Hydrology

NASA Astrophysics Data System (ADS)

Francis, E. J.; Asner, G. P.

2017-12-01

Spatial variability of water in forests is a function of both climatic gradients that control water inputs and topo-edaphic variation that determines the flows of water belowground, as well as interactions of climate with topography. Coastal redwood forests are hydrologically unique because they are influenced by coastal low clouds, or fog, that is advected onto land by a strong coastal-to-inland temperature difference. Where fog intersects the land surface, annual water inputs from summer fog drip can be greater than that of winter rainfall. In this study, we take advantage of mapped spatial gradients in forest canopy water storage, topography, and fog cover in California to better understand the roles and interactions of fog and topography in the hydrology of redwood forests. We test a conceptual model of redwood forest hydrology with measurements of canopy water content derived from high-resolution airborne imaging spectroscopy, topographic variables derived from high-resolution LiDAR data, and fog cover maps derived from NASA MODIS data. Landscape-level results provide insight into hydrological processes within redwood forests, and cross-site analyses shed light on their generality.

Week Long Topography Study of Young Adults Using Electronic Cigarettes in Their Natural Environment.

PubMed

Robinson, R J; Hensel, E C; Roundtree, K A; Difrancesco, A G; Nonnemaker, J M; Lee, Y O

2016-01-01

Results of an observational, descriptive study quantifying topography characteristics of twenty first generation electronic nicotine delivery system users in their natural environment for a one week observation period are presented. The study quantifies inter-participant variation in puffing topography between users and the intra-participant variation for each user observed during one week of use in their natural environment. Puff topography characteristics presented for each user include mean puff duration, flow rate and volume for each participant, along with descriptive statistics of each quantity. Exposure characteristics including the number of vaping sessions, total number of puffs and cumulative volume of aerosol generated from ENDS use (e-liquid aerosol) are reported for each participant for a one week exposure period and an effective daily average exposure. Significant inter-participant and intra-participant variation in puff topography was observed. The observed range of natural use environment characteristics is used to propose a set of topography protocols for use as command inputs to drive machine-puffed electronic nicotine delivery systems in a controlled laboratory environment.

Week Long Topography Study of Young Adults Using Electronic Cigarettes in Their Natural Environment

PubMed Central

Roundtree, K. A.; Difrancesco, A. G.; Nonnemaker, J. M.; Lee, Y. O.

2016-01-01

Results of an observational, descriptive study quantifying topography characteristics of twenty first generation electronic nicotine delivery system users in their natural environment for a one week observation period are presented. The study quantifies inter-participant variation in puffing topography between users and the intra-participant variation for each user observed during one week of use in their natural environment. Puff topography characteristics presented for each user include mean puff duration, flow rate and volume for each participant, along with descriptive statistics of each quantity. Exposure characteristics including the number of vaping sessions, total number of puffs and cumulative volume of aerosol generated from ENDS use (e-liquid aerosol) are reported for each participant for a one week exposure period and an effective daily average exposure. Significant inter-participant and intra-participant variation in puff topography was observed. The observed range of natural use environment characteristics is used to propose a set of topography protocols for use as command inputs to drive machine-puffed electronic nicotine delivery systems in a controlled laboratory environment. PMID:27736944

A Link between Adolescent Nicotine Metabolism and Smoking Topography

PubMed Central

Moolchan, Eric T.; Parzynski, Craig S.; Jaszyna-Gasior, Maria; Collins, Charles C.; Leff, Michelle K.; Zimmerman, Debra L.

2009-01-01

Adult slow nicotine metabolizers have lower smoke exposure, carbon monoxide levels, and plasma nicotine levels than normal and fast metabolizers. Emerging evidence suggests nicotine metabolism influences smoking topography. This study investigated the association of nicotine metabolism (the ratio of plasma 3-hydroxycotinine to cotinine; 3OHCOT/COT) with smoking topography in adolescent smokers (N=85, 65% female, 68% European American, mean age 15.3 ± 1.2, mean cigarettes per day (CPD) 18.5 ± 8.5, mean Fagerström Test for Nicotine Dependence (FTND) 7.0 ± 1.2) presenting for a nicotine replacement therapy trial. Measures obtained included puff volume, inter-puff interval, number of puffs, puff duration, and puff velocity. Linear regression analysis controlling for hormonal contraception use showed that 3OHCOT/COT ratios predicted mean puff volume in the overall sample (t = 2.126, p = .037, adjusted R2 = .067). After gender stratification, faster metabolism predicted higher mean puff volume (t = 2.81, p = .009, adjusted R2 = .192) but fewer puffs (t = −3.160, p=0.004, adjusted R2 = .237) and lower mean puff duration (t = −2.06, p = .048, adjusted R2 = .101) among boys only, suggesting that as nicotine metabolism increases, puff volume increases but puffing frequency decreases. No significant relationships were found between nicotine metabolism and total puff volume, mean puff duration, inter-puff interval, or puff velocity. If confirmed in a broader sample of adolescent smokers, these findings suggest that, as among dependent adult smokers, rate of metabolism among adolescent boys is linked to select parameters of puffing behavior that may impact cessation ability. PMID:19423535

Risk assessment and driving factors for artificial topography on element heterogeneity: Case study at Jiangsu, China.

PubMed

Hong, Hualong; Dai, Minyue; Lu, Haoliang; Liu, Jingchun; Zhang, Jie; Yan, Chongling

2018-02-01

The rapid expansion of construction related to coastal development evokes great concern about environmental risks. Recent attention has been focused mainly on factors related to the effects of waterlogging, but there is urgent need to address the potential hazard caused by artificial topography: derived changes in the elemental composition of the sediments. To reveal possible mechanisms and to assess the environmental risks of artificial topography on transition of elemental composition in the sediment at adjoining zones, a nest-random effects-combined investigation was carried out around a semi-open seawall. The results implied great changes induced by artificial topography. Not only did artificial topography alter the sediment elemental composition at sites under the effect of artificial topography, but also caused a coupling pattern transition of elements S and Cd. The biogeochemical processes associated with S were also important, as suggested by cluster analysis. The geo-accumulation index shows that artificial topography triggered the accumulation of C, N, S, Cu, Fe, Mn, Zn, Ni, Cr, Pb, As and Cd, and increased the pollution risk of C, N, S, Cu, As and Cd. Enrichment factors reveal that artificial topography is a new type of human-activity-derived Cu contamination. The heavy metal Cu was notably promoted on both the geo-accumulation index and the enrichment factor under the influence of artificial topography. Further analysis showed that the Cu content in the sediment could be fitted using equations for Al and organic carbon, which represented clay mineral sedimentation and organic matter accumulation, respectively. Copper could be a reliable indicator of environmental degradation caused by artificial topography. Copyright © 2017 Elsevier Ltd. All rights reserved.

Power laws for gravity and topography of Solar System bodies

NASA Astrophysics Data System (ADS)

Ermakov, A.; Park, R. S.; Bills, B. G.

2017-12-01

When a spacecraft visits a planetary body, it is useful to be able to predict its gravitational and topographic properties. This knowledge is important for determining the level of perturbations in spacecraft's motion as well as for planning the observation campaign. It has been known for the Earth that the power spectrum of gravity follows a power law, also known as the Kaula rule (Kaula, 1963; Rapp, 1989). A similar rule was derived for topography (Vening-Meinesz, 1951). The goal of this paper is to generalize the power law that can characterize the gravity and topography power spectra for bodies across a wide range of size. We have analyzed shape power spectra of the bodies that have either global shape and gravity field measured. These bodies span across five orders of magnitude in their radii and surface gravities and include terrestrial planets, icy moons and minor bodies. We have found that despite having different internal structure, composition and mechanical properties, the topography power spectrum of these bodies' shapes can be modeled with a similar power law rescaled by the surface gravity. Having empirically found a power law for topography, we can map it to a gravity power law. Special care should be taken for low-degree harmonic coefficients due to potential isostatic compensation. For minor bodies, uniform density can be assumed. The gravity coefficients are a linear function of the shape coefficients for close-to-spherical bodoes. In this case, the power law for gravity will be steeper than the power law of topography due to the factor (2n+1) in the gravity expansion (e.g. Eq. 10 in Wieczorek & Phillips, 1998). Higher powers of topography must be retained for irregularly shaped bodies, which breaks the linearity. Therefore, we propose the following procedure to derive an a priori constraint for gravity. First, a surface gravity needs to be determined assuming typical density for the relevant class of bodies. Second, the scaling coefficient of the

Topography of sensory symptoms in patients with drug-naïve restless legs syndrome.

PubMed

Koo, Yong Seo; Lee, Gwan-Taek; Lee, Seo Young; Cho, Yong Won; Jung, Ki-Young

2013-12-01

We aimed to describe the sensory topography of restless legs syndrome (RLS) sensory symptoms and to identify the relationship between topography and clinical variables. Eighty adult patients with drug-naïve RLS who had symptoms for more than 1year were consecutively recruited. During face-to-face interviews using a structured paper and pencil questionnaire with all participants, we obtained clinical information and also marked the topography of RLS sensory symptoms on a specified body template, all of which were subsequently inputted into our in-house software. The RLS sensory topography patterns were classified according to localization, lateralization, and symmetry. We investigated if these sensory topography patterns differed according to various clinical variables. The lower extremities only (LE) were the most common location (72.5%), and 76.3% of participants exhibited symmetric sensory topography. Late-onset RLS showed more asymmetric sensory distribution compared with early-onset RLS (P=.024). Patients whose sensory symptoms involved the lower extremities in addition to other body parts (LE-PLUS) showed more severe RLS compared with those involving the LE (P=.037). RLS sensory symptoms typically were symmetrically located in the lower extremities. LE-PLUS or an asymmetric distribution more often occurred in patients with more severe RLS symptoms or late-onset RLS. Copyright © 2013 Elsevier B.V. All rights reserved.

Surface topography of hydroxyapatite promotes osteogenic differentiation of human bone marrow mesenchymal stem cells.

PubMed

Yang, Wanlei; Han, Weiqi; He, Wei; Li, Jianlei; Wang, Jirong; Feng, Haotian; Qian, Yu

2016-03-01

Effective and safe induction of osteogenic differentiation is one of the key elements of bone tissue engineering. Surface topography of scaffold materials was recently found to promote osteogenic differentiation. Utilization of this topography may be a safer approach than traditional induction by growth factors or chemicals. The aim of this study is to investigate the enhancement of osteogenic differentiation by surface topography and its mechanism of action. Hydroxyapatite (HA) discs with average roughness (Ra) of surface topography ranging from 0.2 to 1.65 μm and mean distance between peaks (RSm) ranging from 89.7 to 18.6 μm were prepared, and human bone-marrow mesenchymal stem cells (hBMSCs) were cultured on these discs. Optimal osteogenic differentiation was observed on discs with surface topography characterized by Ra ranging from 0.77 to 1.09 μm and RSm ranging from 53.9 to 39.3 μm. On this surface configuration of HA, hBMSCs showed oriented attachment, F-actin arrangement, and a peak in the expression of Yes-associated protein (YAP) and PDZ binding motif (TAZ) (YAP/TAZ). These results indicated that the surface topography of HA promoted osteogenic differentiation of hBMSCs, possibly by increasing cell attachment and promoting the YAP/TAZ signaling pathway. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous topography imaging and broadband nanomechanical mapping on atomic force microscope

NASA Astrophysics Data System (ADS)

Li, Tianwei; Zou, Qingze

2017-12-01

In this paper, an approach is proposed to achieve simultaneous imaging and broadband nanomechanical mapping of soft materials in air by using an atomic force microscope. Simultaneous imaging and nanomechanical mapping are needed, for example, to correlate the morphological and mechanical evolutions of the sample during dynamic phenomena such as the cell endocytosis process. Current techniques for nanomechanical mapping, however, are only capable of capturing static elasticity of the material, or the material viscoelasticity in a narrow frequency band around the resonant frequency(ies) of the cantilever used, not competent for broadband nanomechanical mapping, nor acquiring topography image of the sample simultaneously. These limitations are addressed in this work by enabling the augmentation of an excitation force stimuli of rich frequency spectrum for nanomechanical mapping in the imaging process. Kalman-filtering technique is exploited to decouple and split the mixed signals for imaging and mapping, respectively. Then the sample indentation generated is quantified online via a system-inversion method, and the effects of the indentation generated and the topography tracking error on the topography quantification are taken into account. Moreover, a data-driven feedforward-feedback control is utilized to track the sample topography. The proposed approach is illustrated through experimental implementation on a polydimethylsiloxane sample with a pre-fabricated pattern.

School scoliosis screening by Moiré topography - Overview for 33 years in Miyazaki Japan.

PubMed

Kuroki, Hiroshi; Nagai, Takuya; Chosa, Etsuo; Tajima, Naoya

2018-04-05

Since 1981, we have performed school scoliosis screening (SSS) using Moiré topography in Miyazaki, Japan and attained a certain result in detecting scoliosis. However, this screening system was discontinued due to cessation of repair and production of Moiré topographic equipment. The purpose of this study was to make clear both the results and the problems of SSS by Moiré topography on the basis of our past 33 years' experiences. The subjects were 689,293 students (5th grade boys in 200,329, 5th grade girls in 191,919, 8th grade boys in 151,351, and 8th grade girls in 145,694) who were screened by Moiré topography between 1981 and 2013. The number of students received SSS, the positive rate of Moiré topography, the discovery rate of scoliosis greater than 20°, the reference rate to the second screening, and the positive predictive value of Moiré topography to detect scoliosis greater than 20° were investigated. The number of students received SSS achieved a peak in 1992. The positive rate of Moiré topography and the discovery rate of scoliosis were highest in 8th grade girls. The reference rates to the second screening were 49.8% in 5th grade students and 41.4% in 8th grade students. The positive predictive values were 2.1% in 5th grade students and 7.6% in 8th grade students. SSS by Moiré topography seemed to be effective in detecting scoliosis although both the positive predictive value and the reference rate to the second screening were low. Copyright © 2018. Published by Elsevier B.V.

Topography compensation for haptization of a mesh object and its stiffness distribution.

PubMed

Yim, Sunghoon; Jeon, Seokhee; Choi, Seungmoon

2015-01-01

This work was motivated by the need for perceptualizing nano-scale scientific data, e.g., those acquired by a scanning probe microscope, where collocated topography and stiffness distribution of a surface can be measured. Previous research showed that when the topography of a surface with spatially varying stiffness is rendered using the conventional penalty-based haptic rendering method, the topography perceived by the user could be significantly distorted from its original model. In the worst case, a higher region with a smaller stiffness value can be perceived to be lower than a lower region with a larger stiffness value. This problem was explained by the theory of force constancy: the user tends to maintain an invariant contact force when s/he strokes the surface to perceive its topography. In this paper, we present a haptization algorithm that can render the shape of a mesh surface and its stiffness distribution with high perceptual accuracy. Our algorithm adaptively changes the surface topography on the basis of the force constancy theory to deliver adequate shape information to the user while preserving the stiffness perception. We also evaluated the performance of the proposed haptization algorithm in comparison to the constraint-based algorithm by examining relevant proximal stimuli and carrying out a user experiment. Results demonstrated that our algorithm could improve the perceptual accuracy of shape and reduce the exploration time, thereby leading to more accurate and efficient haptization.

Smoking Through a Topography Device Diminishes Some of the Acute Rewarding Effects of Smoking

PubMed Central

Juliano, Laura M.

2016-01-01

Abstract Background: Smoking topography (ST) devices are an important methodological tool for quantifying puffing behavior (eg, puff volume, puff velocity) as well as identifying puffing differences across individuals and situations. Available ST devices are designed such that the smoker’s mouth and hands have direct contact with the device rather than the cigarette itself. Given the importance of the sensorimotor aspects of cigarette smoking in smoking reward, it is possible that ST devices may interfere with the acute rewarding effects of smoking. Despite the methodological importance of this issue, few studies have directly compared subjective reactions to smoking through a topography device to naturalistic smoking. Methods: Smokers ( N = 58; 38% female) smoked their preferred brand of cigarettes one time through a portable topography device and one time naturalistically, in counterbalanced order across two laboratory sessions. Smoking behavior (eg, number of puffs) and subjective effects (eg, urge reduction, affect, smoking satisfaction) were assessed. Results: Negative affect reduction was greater in the natural smoking condition relative to the topography condition, but differences were not significant on measures of urge, withdrawal, or positive affect. Self-reported smoking satisfaction, enjoyment of respiratory tract sensations, psychological reward, craving reduction, and other rewarding effects of smoking were also significantly greater in the naturalistic smoking condition. Conclusions: The effects of using a ST device on the smoking experience should be considered when it is used in research as it may diminish some of the rewarding effects of smoking. Implications: When considering the inclusion of a smoking topography device in one’s research, it is important to know if use of that device will alter the smoker’s experience. This study assessed affective and subjective reactions to smoking through a topography device compared to naturalistic

ATM Coastal Topography-Texas, 2001: UTM Zone 15

USGS Publications Warehouse

Klipp, Emily S.; Nayegandhi, Amar; Brock, John C.; Sallenger, A.H.; Bonisteel, Jamie M.; Yates, Xan; Wright, C. Wayne

2009-01-01

These remotely sensed, geographically referenced elevation measurements of lidar-derived first-surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Texas coastline within UTM zone 15, from Matagorda Peninsula to Galveston Island, acquired October 12-13, 2001. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative scanning lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of lidar data in an interactive or batch mode. Modules for presurvey flight-line definition, flight-path plotting, lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant

Non-invasive primate head restraint using thermoplastic masks.

PubMed

Drucker, Caroline B; Carlson, Monica L; Toda, Koji; DeWind, Nicholas K; Platt, Michael L

2015-09-30

The success of many neuroscientific studies depends upon adequate head fixation of awake, behaving animals. Typically, this is achieved by surgically affixing a head-restraint prosthesis to the skull. Here we report the use of thermoplastic masks to non-invasively restrain monkeys' heads. Mesh thermoplastic sheets become pliable when heated and can then be molded to an individual monkey's head. After cooling, the custom mask retains this shape indefinitely for day-to-day use. We successfully trained rhesus macaques (Macaca mulatta) to perform cognitive tasks while wearing thermoplastic masks. Using these masks, we achieved a level of head stability sufficient for high-resolution eye-tracking and intracranial electrophysiology. Compared with traditional head-posts, we find that thermoplastic masks perform at least as well during infrared eye-tracking and single-neuron recordings, allow for clearer magnetic resonance image acquisition, enable freer placement of a transcranial magnetic stimulation coil, and impose lower financial and time costs on the lab. We conclude that thermoplastic masks are a viable non-invasive form of primate head restraint that enable a wide range of neuroscientific experiments. Copyright © 2015 Elsevier B.V. All rights reserved.

Non-invasive primate head restraint using thermoplastic masks

PubMed Central

Drucker, Caroline B.; Carlson, Monica L.; Toda, Koji; DeWind, Nicholas K.; Platt, Michael L.

2015-01-01

Background The success of many neuroscientific studies depends upon adequate head fixation of awake, behaving animals. Typically, this is achieved by surgically affixing a head-restraint prosthesis to the skull. New Method Here we report the use of thermoplastic masks to non-invasively restrain monkeys’ heads. Mesh thermoplastic sheets become pliable when heated and can then be molded to an individual monkey’s head. After cooling, the custom mask retains this shape indefinitely for day-to-day use. Results We successfully trained rhesus macaques (Macaca mulatta) to perform cognitive tasks while wearing thermoplastic masks. Using these masks, we achieved a level of head stability sufficient for high-resolution eye-tracking and intracranial electrophysiology. Comparison with Existing Method Compared with traditional head-posts, we find that thermoplastic masks perform at least as well during infrared eye-tracking and single-neuron recordings, allow for clearer magnetic resonance image acquisition, enable freer placement of a transcranial magnetic stimulation coil, and impose lower financial and time costs on the lab. Conclusions We conclude that thermoplastic masks are a viable non-invasive form of primate head restraint that enable a wide range of neuroscientific experiments. PMID:26112334

Detection of Bartonella quintana in African Body and Head Lice

PubMed Central

Sangaré, Abdoul Karim; Boutellis, Amina; Drali, Rezak; Socolovschi, Cristina; Barker, Stephen C.; Diatta, Georges; Rogier, Christophe; Olive, Marie-Marie; Doumbo, Ogobara K.; Raoult, Didier

2014-01-01

Currently, the body louse is the only recognized vector of Bartonella quintana, an organism that causes trench fever. In this work, we investigated the prevalence of this bacterium in human lice in different African countries. We tested 616 head lice and 424 body lice from nine African countries using real-time polymerase chain reaction targeting intergenic spacer region 2 and specific B. quintana genes. Overall, B. quintana DNA was found in 54% and 2% of body and head lice, respectively. Our results also show that there are more body lice positive for B. quintana in poor countries, which was determined by the gross domestic product, than in wealthy areas (228/403 versus 0/21, P < 0.001). A similar finding was obtained for head lice (8/226 versus 2/390, P = 0.007). Our findings suggest that head lice in Africa may be infected by B. quintana when patients live in poor economic conditions and are also exposed to body lice. PMID:24935950

Urban topography for flood modeling by fusion of OpenStreetMap, SRTM and local knowledge

NASA Astrophysics Data System (ADS)

Winsemius, Hessel; Donchyts, Gennadii; Eilander, Dirk; Chen, Jorik; Leskens, Anne; Coughlan, Erin; Mawanda, Shaban; Ward, Philip; Diaz Loaiza, Andres; Luo, Tianyi; Iceland, Charles

2016-04-01

Topography data is essential for understanding and modeling of urban flood hazard. Within urban areas, much of the topography is defined by highly localized man-made features such as roads, channels, ditches, culverts and buildings. This results in the requirement that urban flood models require high resolution topography, and water conveying connections within the topography are considered. In recent years, more and more topography information is collected through LIDAR surveys however there are still many cities in the world where high resolution topography data is not available. Furthermore, information on connectivity is required for flood modelling, even when LIDAR data are used. In this contribution, we demonstrate how high resolution terrain data can be synthesized using a fusion between features in OpenStreetMap (OSM) data (including roads, culverts, channels and buildings) and existing low resolution and noisy SRTM elevation data using the Google Earth Engine platform. Our method uses typical existing OSM properties to estimate heights and topology associated with the features, and uses these to correct noise and burn features on top of the existing low resolution SRTM elevation data. The method has been setup in the Google Earth Engine platform so that local stakeholders and mapping teams can on-the-fly propose, include and visualize the effect of additional features and properties of features, which are deemed important for topography and water conveyance. These features can be included in a workshop environment. We pilot our tool over Dar Es Salaam.

Snap evaporation of droplets on smooth topographies.

PubMed

Wells, Gary G; Ruiz-Gutiérrez, Élfego; Le Lirzin, Youen; Nourry, Anthony; Orme, Bethany V; Pradas, Marc; Ledesma-Aguilar, Rodrigo

2018-04-11

Droplet evaporation on solid surfaces is important in many applications including printing, micro-patterning and cooling. While seemingly simple, the configuration of evaporating droplets on solids is difficult to predict and control. This is because evaporation typically proceeds as a "stick-slip" sequence-a combination of pinning and de-pinning events dominated by static friction or "pinning", caused by microscopic surface roughness. Here we show how smooth, pinning-free, solid surfaces of non-planar topography promote a different process called snap evaporation. During snap evaporation a droplet follows a reproducible sequence of configurations, consisting of a quasi-static phase-change controlled by mass diffusion interrupted by out-of-equilibrium snaps. Snaps are triggered by bifurcations of the equilibrium droplet shape mediated by the underlying non-planar solid. Because the evolution of droplets during snap evaporation is controlled by a smooth topography, and not by surface roughness, our ideas can inspire programmable surfaces that manage liquids in heat- and mass-transfer applications.

Synchrotron X-ray topography of electronic materials.

PubMed

Tuomi, T

2002-05-01

Large-area transmission, transmission section, large-area back-reflection, back-reflection section and grazing-incidence topography are the geometries used when recording high-resolution X-ray diffraction images with synchrotron radiation from a bending magnet, a wiggler or an undulator of an electron or a positron storage ring. Defect contrast can be kinematical, dynamical or orientational even in the topographs recorded on the same film at the same time. In this review article limited to static topography experiments, examples of defect studies on electronic materials cover the range from voids and precipitates in almost perfect float-zone and Czochralski silicon, dislocations in gallium arsenide grown by the liquid-encapsulated Czochralski technique, the vapour-pressure controlled Czochralski technique and the vertical-gradient freeze technique, stacking faults and micropipes in silicon carbide to misfit dislocations in epitaxic heterostructures. It is shown how synchrotron X-ray topographs of epitaxic laterally overgrown gallium arsenide layer structures are successfully explained by orientational contrast.

Counter-intuitive features of the dynamic topography unveiled by tectonically realistic 3D numerical models of mantle-lithosphere interactions

NASA Astrophysics Data System (ADS)

Burov, Evgueni; Gerya, Taras

2013-04-01

It has been long assumed that the dynamic topography associated with mantle-lithosphere interactions should be characterized by long-wavelength features (> 1000 km) correlating with morphology of mantle flow and expanding beyond the scale of tectonic processes. For example, debates on the existence of mantle plumes largely originate from interpretations of expected signatures of plume-induced topography that are compared to the predictions of analytical and numerical models of plume- or mantle-lithosphere interactions (MLI). Yet, most of the large-scale models treat the lithosphere as a homogeneous stagnant layer. We show that in continents, the dynamic topography is strongly affected by rheological properties and layered structure of the lithosphere. For that we reconcile mantle- and tectonic-scale models by introducing a tectonically realistic continental plate model in 3D large-scale plume-mantle-lithosphere interaction context. This model accounts for stratified structure of continental lithosphere, ductile and frictional (Mohr-Coulomb) plastic properties and thermodynamically consistent density variations. The experiments reveal a number of important differences from the predictions of the conventional models. In particular, plate bending, mechanical decoupling of crustal and mantle layers and intra-plate tension-compression instabilities result in transient topographic signatures such as alternating small-scale surface features that could be misinterpreted in terms of regional tectonics. Actually thick ductile lower crustal layer absorbs most of the "direct" dynamic topography and the features produced at surface are mostly controlled by the mechanical instabilities in the upper and intermediate crustal layers produced by MLI-induced shear and bending at Moho and LAB. Moreover, the 3D models predict anisotropic response of the lithosphere even in case of isotropic solicitations by axisymmetric mantle upwellings such as plumes. In particular, in presence of

Head-to-head randomized trials are mostly industry sponsored and almost always favor the industry sponsor.

PubMed

Flacco, Maria Elena; Manzoli, Lamberto; Boccia, Stefania; Capasso, Lorenzo; Aleksovska, Katina; Rosso, Annalisa; Scaioli, Giacomo; De Vito, Corrado; Siliquini, Roberta; Villari, Paolo; Ioannidis, John P A

2015-07-01

To map the current status of head-to-head comparative randomized evidence and to assess whether funding may impact on trial design and results. From a 50% random sample of the randomized controlled trials (RCTs) published in journals indexed in PubMed during 2011, we selected the trials with ≥ 100 participants, evaluating the efficacy and safety of drugs, biologics, and medical devices through a head-to-head comparison. We analyzed 319 trials. Overall, 238,386 of the 289,718 randomized subjects (82.3%) were included in the 182 trials funded by companies. Of the 182 industry-sponsored trials, only 23 had two industry sponsors and only three involved truly antagonistic comparisons. Industry-sponsored trials were larger, more commonly registered, used more frequently noninferiority/equivalence designs, had higher citation impact, and were more likely to have "favorable" results (superiority or noninferiority/equivalence for the experimental treatment) than nonindustry-sponsored trials. Industry funding [odds ratio (OR) 2.8; 95% confidence interval (CI): 1.6, 4.7] and noninferiority/equivalence designs (OR 3.2; 95% CI: 1.5, 6.6), but not sample size, were strongly associated with "favorable" findings. Fifty-five of the 57 (96.5%) industry-funded noninferiority/equivalence trials got desirable "favorable" results. The literature of head-to-head RCTs is dominated by the industry. Industry-sponsored comparative assessments systematically yield favorable results for the sponsors, even more so when noninferiority designs are involved. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Open questions in surface topography measurement: a roadmap

NASA Astrophysics Data System (ADS)

Leach, Richard; Evans, Christopher; He, Liangyu; Davies, Angela; Duparré, Angela; Henning, Andrew; Jones, Christopher W.; O'Connor, Daniel

2015-03-01

Control of surface topography has always been of vital importance for manufacturing and many other engineering and scientific disciplines. However, despite over one hundred years of quantitative surface topography measurement, there are still many open questions. At the top of the list of questions is ‘Are we getting the right answer?’ This begs the obvious question ‘How would we know?’ There are many other questions relating to applications, the appropriateness of a technique for a given scenario, or the relationship between a particular analysis and the function of the surface. In this first ‘open questions’ article we have gathered together some experts in surface topography measurement and asked them to address timely, unresolved questions about the subject. We hope that their responses will go some way to answer these questions, address areas where further research is required, and look at the future of the subject. The first section ‘Spatial content characterization for precision surfaces’ addresses the need to characterise the spatial content of precision surfaces. Whilst we have been manufacturing optics for centuries, there still isn’t a consensus on how to specify the surface for manufacture. The most common three methods for spatial characterisation are reviewed and compared, and the need for further work on quantifying measurement uncertainties is highlighted. The article is focussed on optical surfaces, but the ideas are more pervasive. Different communities refer to ‘figure, mid-spatial frequencies, and finish’ and ‘form, waviness, and roughness’, but the mathematics are identical. The second section ‘Light scattering methods’ is focussed on light scattering techniques; an important topic with in-line metrology becoming essential in many manufacturing scenarios. The potential of scattering methods has long been recognized; in the ‘smooth surface limit’ functionally significant relationships can be derived from first

Head lice

MedlinePlus

Pediculosis capitis - head lice ... Head lice infect hair on the head. Tiny eggs on the hair look like flakes of dandruff . However, ... flaking off the scalp, they stay in place. Head lice can live up to 30 days on a ...

The Role of Membrane Curvature in Nanoscale Topography-Induced Intracellular Signaling.

PubMed

Lou, Hsin-Ya; Zhao, Wenting; Zeng, Yongpeng; Cui, Bianxiao

2018-05-15

Over the past decade, there has been growing interest in developing biosensors and devices with nanoscale and vertical topography. Vertical nanostructures induce spontaneous cell engulfment, which enhances the cell-probe coupling efficiency and the sensitivity of biosensors. Although local membranes in contact with the nanostructures are found to be fully fluidic for lipid and membrane protein diffusions, cells appear to actively sense and respond to the surface topography presented by vertical nanostructures. For future development of biodevices, it is important to understand how cells interact with these nanostructures and how their presence modulates cellular function and activities. How cells recognize nanoscale surface topography has been an area of active research for two decades before the recent biosensor works. Extensive studies show that surface topographies in the range of tens to hundreds of nanometers can significantly affect cell functions, behaviors, and ultimately the cell fate. For example, titanium implants having rough surfaces are better for osteoblast attachment and host-implant integration than those with smooth surfaces. At the cellular level, nanoscale surface topography has been shown by a large number of studies to modulate cell attachment, activity, and differentiation. However, a mechanistic understanding of how cells interact and respond to nanoscale topographic features is still lacking. In this Account, we focus on some recent studies that support a new mechanism that local membrane curvature induced by nanoscale topography directly acts as a biochemical signal to induce intracellular signaling, which we refer to as the curvature hypothesis. The curvature hypothesis proposes that some intracellular proteins can recognize membrane curvatures of a certain range at the cell-to-material interface. These proteins then recruit and activate downstream components to modulate cell signaling and behavior. We discuss current technologies

Minimizing Head Acceleration in Soccer: A Review of the Literature.

PubMed

Caccese, Jaclyn B; Kaminski, Thomas W

2016-11-01

Physicians and healthcare professionals are often asked for recommendations on how to keep athletes safe during contact sports such as soccer. With an increase in concussion awareness and concern about repetitive subconcussion, many parents and athletes are interested in mitigating head acceleration in soccer, so we conducted a literature review on factors that affect head acceleration in soccer. We searched electronic databases and reference lists to find studies using the keywords 'soccer' OR 'football' AND 'head acceleration'. Because of a lack of current research in soccer heading biomechanics, this review was limited to 18 original research studies. Low head-neck segment mass predisposes athletes to high head acceleration, but head-neck-torso alignment during heading and follow-through after contact can be used to decrease head acceleration. Additionally, improvements in symmetric neck flexor and extensor strength and neuromuscular neck stiffness can decrease head acceleration. Head-to-head impacts and unanticipated ball contacts result in the highest head acceleration. Ball contacts at high velocity may also be dangerous. The risk of concussive impacts may be lessened through the use of headgear, but headgear may also cause athletes to play more recklessly because they feel a sense of increased security. Young, but physically capable, athletes should be taught proper heading technique in a controlled setting, using a carefully planned progression of the skill.

Macromolecular Topography Leaps into the Digital Age

NASA Technical Reports Server (NTRS)

Lovelace, J.; Bellamy, H.; Snell, E. H.; Borgstahl, G.

2003-01-01

A low-cost, real-time digital topography system is under development which will replace x-ray film and nuclear emulsion plates. The imaging system is based on an inexpensive surveillance camera that offers a 1000x1000 array of 8 im square pixels, anti-blooming circuitry, and very quick read out. Currently, the system directly converts x-rays to an image with no phosphor. The system is small and light and can be easily adapted to work with other crystallographic equipment. Preliminary images have been acquired of cubic insulin at the NSLS x26c beam line. NSLS x26c was configured for unfocused monochromatic radiation. Six reflections were collected with stills spaced from 0.002 to 0.001 degrees apart across the entire oscillation range that the reflections were in diffracting condition. All of the reflections were rotated to the vertical to reduce Lorentz and beam related effects. This particular CCD is designed for short exposure applications (much less than 1 sec) and so has a relatively high dark current leading to noisy raw images. The images are processed to remove background and other system noise with a multi-step approach including the use of wavelets, histogram, and mean window filtering. After processing, animations were constructed with the corresponding reflection profile to show the diffraction of the crystal volume vs. the oscillation angle as well as composite images showing the parts of the crystal with the strongest diffraction for each reflection. The final goal is to correlate features seen in reflection profiles captured with fine phi slicing to those seen in the topography images. With this development macromolecular topography finally comes into the digital age.

Integrated approach to estimate the ocean's time variable dynamic topography including its covariance matrix

NASA Astrophysics Data System (ADS)

Müller, Silvia; Brockmann, Jan Martin; Schuh, Wolf-Dieter

2015-04-01

The ocean's dynamic topography as the difference between the sea surface and the geoid reflects many characteristics of the general ocean circulation. Consequently, it provides valuable information for evaluating or tuning ocean circulation models. The sea surface is directly observed by satellite radar altimetry while the geoid cannot be observed directly. The satellite-based gravity field determination requires different measurement principles (satellite-to-satellite tracking (e.g. GRACE), satellite-gravity-gradiometry (GOCE)). In addition, hydrographic measurements (salinity, temperature and pressure; near-surface velocities) provide information on the dynamic topography. The observation types have different representations and spatial as well as temporal resolutions. Therefore, the determination of the dynamic topography is not straightforward. Furthermore, the integration of the dynamic topography into ocean circulation models requires not only the dynamic topography itself but also its inverse covariance matrix on the ocean model grid. We developed a rigorous combination method in which the dynamic topography is parameterized in space as well as in time. The altimetric sea surface heights are expressed as a sum of geoid heights represented in terms of spherical harmonics and the dynamic topography parameterized by a finite element method which can be directly related to the particular ocean model grid. Besides the difficult task of combining altimetry data with a gravity field model, a major aspect is the consistent combination of satellite data and in-situ observations. The particular characteristics and the signal content of the different observations must be adequately considered requiring the introduction of auxiliary parameters. Within our model the individual observation groups are combined in terms of normal equations considering their full covariance information; i.e. a rigorous variance/covariance propagation from the original measurements to the

Calculation of Seismic Waves from Explosions with Tectonic Stresses and Topography

NASA Astrophysics Data System (ADS)

Stevens, J. L.; O'Brien, M.

2017-12-01

We investigate the effects of explosion depth, tectonic stresses and topography on seismic waves from underground nuclear explosions. We perform three-dimensional nonlinear calculations of an explosion at several depths in the topography of the North Korean test site. We also perform a large number of two-dimensional axisymmetric calculations of explosions at depths from 150 to 1000 meters in four earth structures, with compressive and tensile tectonic stresses and with no tectonic stresses. We use the representation theorem to propagate the results of these calculations and calculate seismic waves at regional and teleseismic distances. We find that P-waves are not strongly affected by any of these effects because the initial downgoing P-wave is unaffected by interaction with the free surface. Surface waves, however, are strongly affected by all of these effects. There is an optimal depth at which surface waves are maximized at the base of a mountain and at or slightly below normal containment depth. At deeper depths, increasing overburden pressure reduces the surface waves. At shallower depths, interaction with the free surface reduces the surface waves. For explosions inside a mountain, displacement of the sides of the mountain reduces surface waves. Compressive prestress reduces surface waves substantially, while tensile prestress increases surface waves. The North Korean explosions appear to be at an optimal depth, in a region of extension, and beneath a mountain, all of which increase surface wave amplitudes.

[Mentoring newly appointed department heads--a new project review and initial findings].

PubMed

Fishbain, Dana; Bartor, Orit; Aviram, Lilach; Golik, Ahuva; Ashkenazi, Shai; Eidelman, Leonid

2015-01-01

In Israel, the training of a department head is based mostly on clinical and professional aspects and often does not include any training in other facets of management he or she will encounter. The newly appointed department head is expected from the start to deal with many diverse tasks, and is exposed to great physical and emotional stress. The Israeli Medical Association, taking note of this situation, initiated a mentoring program for newly appointed heads of medical departments, clinics and units. This article seeks to present a preliminary description of our experience with this mentoring project, in which senior managers mentor novices in the position. An announcement of the new project was sent to both senior and beginning managers, detailing the project's goal. The project's content and structure were determined together with the participants, mentors and mentees. The values attending the project were delineated as full and genuine partnership, attention to needs, and personal choice of the mentee. Basic guidelines, adaptive to modification according to personal preferences, were developed based on these values. Though not readily assumed, our decision to allow mentees to choose their mentors was found to be suitable for this project. All participants, mentors and mentees, were asked to complete feedback forms in preparation for the final gathering of the group. The first session of the project included 8 mentor and mentee couples. Feedback indicated a high suitability rate between mentor and mentee, which resulted in high levels of satisfaction among the mentees. Responses to feedback questionnaires depicted that the relationships between the mentors and mentees included trust, openness and a non-judgmental approach, which allowed mentees to share personal difficulties and develop plans to overcome them. Most mentees described the mentorship as providing leverage to personal growth. Mentors expressed satisfaction for the opportunity to contribute of their

Effects of titanium surface topography on bone integration: a systematic review.

PubMed

Wennerberg, Ann; Albrektsson, Tomas

2009-09-01

To analyse possible effects of titanium surface topography on bone integration. Our analyses were centred on a PubMed search that identified 1184 publications of assumed relevance; of those, 1064 had to be disregarded because they did not accurately present in vivo data on bone response to surface topography. The remaining 120 papers were read and analysed, after removal of an additional 20 papers that mainly dealt with CaP-coated and Zr implants; 100 papers remained and formed the basis for this paper. The bone response to differently configurated surfaces was mainly evaluated by histomorphometry (bone-to-implant contact), removal torque and pushout/pullout tests. A huge number of the experimental investigations have demonstrated that the bone response was influenced by the implant surface topography; smooth (S(a)<0.5 microm) and minimally rough (S(a) 0.5-1 mum) surfaces showed less strong bone responses than rougher surfaces. Moderately rough (S(a)>1-2 microm) surfaces showed stronger bone responses than rough (S(a)>2 microm) in some studies. One limitation was that it was difficult to compare many studies because of the varying quality of surface evaluations; a surface termed 'rough' in one study was not uncommonly referred to as 'smooth' in another; many investigators falsely assumed that surface preparation per se identified the roughness of the implant; and many other studies used only qualitative techniques such as SEM. Furthermore, filtering techniques differed or only height parameters (S(a), R(a)) were reported. * Surface topography influences bone response at the micrometre level. * Some indications exist that surface topography influences bone response at the nanometre level. * The majority of published papers present an inadequate surface characterization. * Measurement and evaluation techniques need to be standardized. * Not only height descriptive parameters but also spatial and hybrid ones should be used.

Head Lice

MedlinePlus

What are head lice? Head lice are tiny insects that live on people's heads. Adult lice are about the size of sesame seeds. The eggs, called ... often at the neckline and behind the ears. Head lice are parasites, and they need to feed on ...

A nonlinear self-similar solution to barotropic flow over rapidly varying topography

NASA Astrophysics Data System (ADS)

Ibanez, Ruy; Kuehl, Joseph

2016-11-01

Beginning from the Shallow Water Equations (SWE), a nonlinear self-similar analytic solution is derived for barotropic flow over rapidly varying topography. We study conditions relevant to the ocean slope where the flow is dominated by Earth's rotation and topography. Attention is paid to the northern Gulf of Mexico slope with application to pollutant dispersion and the Norwegian Coastal Current which sheds eddies into the Lofoten Basin that are believe to influence deep water formation. The solution is found to extend the topographic β-plume solution (Kuehl 2014, GRL) in two ways: 1) The solution is valid for intensifying jets. 2) The influence of nonlinear advection is included. The SWE are scaled to the case of a topographically controlled jet, then solved by introducing a similarity variable η = Cxy . The nonlinear solution, valid for topographies h =h0 - αxy3 , takes the form of the Lambert W Function for velocity. The linear solution, valid for topographies h =h0 - αxyγ , takes the form of the Error Function for transport. Kuehl's results considered the case - 1 <= γ < 1 which admits expanding jets, while the new result consider the case γ < - 1 which admits intensifying jets.

The Influence of a Mouthpiece-Based Topography Measurement Device on Electronic Cigarette User's Plasma Nicotine Concentration, Heart Rate, and Subjective Effects Under Directed and Ad Libitum Use Conditions.

PubMed

Spindle, Tory R; Hiler, Marzena M; Breland, Alison B; Karaoghlanian, Nareg V; Shihadeh, Alan L; Eissenberg, Thomas

2017-04-01

libitum puff topography in experienced individuals using their preferred e-cigarette battery and liquid with a mouthpiece-based computerized device. E-cigarette use significantly increased plasma nicotine concentration and heart rate while suppressing abstinence symptoms. These effects did not differ when a topography mouthpiece was present. Ad libitum puff topography differed from puff topography recorded during directed puffing. These findings suggest that future studies using ad libitum use bouts would facilitate better understanding of e-cigarette toxicant yield. © The Author 2016. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Topography of Io (color)

NASA Technical Reports Server (NTRS)

1997-01-01

The images used to create this color composite of Io were acquired by Galileo during its ninth orbit (C9) of Jupiter and are part of a sequence of images designed to map the topography or relief on Io and to monitor changes in the surface color due to volcanic activity. Obtaining images at low illumination angles is like taking a picture from a high altitude around sunrise or sunset. Such lighting conditions emphasize the topography of the volcanic satellite. Several mountains up to a few miles high can be seen in this view, especially near the upper right. Some of these mountains appear to be tilted crustal blocks. Most of the dark spots correspond to active volcanic centers.

North is to the top of the picture which merges images obtained with the clear, red, green, and violet filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. . The resolution is 8.3 kilometers per picture element. The image was taken on June 27, 1997 at a range of 817,000 kilometers by the solid state imaging (CCD) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

Clinical manifestations of neuroblastoma with head and neck involvement in children.

PubMed

Alvi, Sameer; Karadaghy, Omar; Manalang, Michelle; Weatherly, Robert

2017-06-01

The purpose of our study is to review our 15-year experience with pediatric patients who have been diagnosed with neuroblastoma, and to determine their most frequent head and neck manifestations and symptoms. Retrospective chart review of electronic medical record. An academic, tertiary care pediatric hospital. IRB approval from the Office of Research Integrity at Children's Mercy Hospital was obtained. The hospital tumor database was analyzed to identify patients with neuroblastoma, ganglioneuroblastoma, and esthesioneuroblastoma diagnosed between 1997 and 2012. We recorded the various clinical signs and symptoms these patients displayed at their initial presentation, focusing on patients with head and neck involvement. We then determined the relative incidence of these various findings. Our review yielded 118 patients diagnosed with neuroblastoma, ganglioneuroblastoma, or esthesioneuroblastoma over our 15 year study period. 7 of the 118 patients were diagnosed with primary tumors of the head and neck. Another 19 patients had metastatic head and neck involvement. For those with primary disease, presence of a neck mass and signs of Horner's syndrome were the most common findings. For metastatic disease, craniofacial bony metastasis was the most frequent finding in our study. Based on our data, there are a handful of findings that occur frequently in pediatric head and neck neuroblastoma. Any persistent neck mass, unexplained Horner's syndrome, or periorbital ecchymosis should be carefully evaluated. This study should serve as an aid for the otolaryngologist to be aware of the possible manifestations of this malignancy in children. Copyright © 2017 Elsevier B.V. All rights reserved.

Cellular Scale Anisotropic Topography Guides Schwann Cell Motility

PubMed Central

Mitchel, Jennifer A.; Hoffman-Kim, Diane

2011-01-01

Directed migration of Schwann cells (SC) is critical for development and repair of the peripheral nervous system. Understanding aspects of motility specific to SC, along with SC response to engineered biomaterials, may inform strategies to enhance nerve regeneration. Rat SC were cultured on laminin-coated microgrooved poly(dimethyl siloxane) platforms that were flat or presented repeating cellular scale anisotropic topographical cues, 30 or 60 µm in width, and observed with timelapse microscopy. SC motion was directed parallel to the long axis of the topography on both the groove floor and the plateau, with accompanying differences in velocity and directional persistence in comparison to SC motion on flat substrates. In addition, feature dimension affected SC morphology, alignment, and directional persistence. Plateaus and groove floors presented distinct cues which promoted differential motility and variable interaction with the topographical features. SC on the plateau surfaces tended to have persistent interactions with the edge topography, while SC on the groove floors tended to have infrequent contact with the corners and walls. Our observations suggest the capacity of SC to be guided without continuous contact with a topographical cue. SC exhibited a range of distinct motile morphologies, characterized by their symmetry and number of extensions. Across all conditions, SC with a single extension traveled significantly faster than cells with more or no extensions. We conclude that SC motility is complex, where persistent motion requires cellular asymmetry, and that anisotropic topography with cellular scale features can direct SC motility. PMID:21949703

Influence of local topography on precision irrigation management

USDA-ARS?s Scientific Manuscript database

Precision irrigation management is currently accomplished using spatial information about soil properties through soil series maps or electrical conductivity (EC measurements. Crop yield, however, is consistently influenced by local topography, both in rain-fed and irrigated environments. Utilizing ...

Sensory Topography of Oral Structures.

PubMed

Bearelly, Shethal; Cheung, Steven W

2017-01-01

Sensory function in the oral cavity and oropharynx is integral to effective deglutition and speech production. The main hurdle to evaluation of tactile consequences of upper aerodigestive tract diseases and treatments is access to a reliable clinical tool. We propose a rapid and reliable procedure to determine tactile thresholds using buckling monofilaments to advance care. To develop novel sensory testing monofilaments and map tactile thresholds of oral cavity and oropharyngeal structures. A prospective cross-sectional study of 37 healthy adults (12 men, 25 women), specifically without a medical history of head and neck surgery, radiation, or chemotherapy, was carried out in an academic tertiary medical center to capture normative data on tactile sensory function in oral structures. Cheung-Bearelly monofilaments were constructed by securing nylon monofilament sutures (2-0 through 9-0) in the lumen of 5-French ureteral catheters, exposing 20 mm for tapping action. Buckling force consistency was evaluated for 3 lots of each suture size. Sensory thresholds of 4 oral cavity and 2 oropharyngeal subsites in healthy participants (n = 37) were determined by classical signal detection methodology (d-prime ≥1). In 21 participants, test-retest reliability of sensory thresholds was evaluated. Separately in 16 participants, sensory thresholds determined by a modified staircase method were cross-validated with those obtained by classical signal detection. Buckling forces of successive suture sizes were distinct (P < .001), consistent (Cronbach α, 0.99), and logarithmically related (r = 0.99, P < .001). Test-retest reliability of sensory threshold determination was high (Cronbach α, >0.7). The lower lip, anterior tongue, and buccal mucosa were more sensitive than the soft palate, posterior tongue, and posterior pharyngeal wall (P < .001). Threshold determination by classical signal detection and modified staircase methods were highly correlated (r = 0

Suicide by blunt head trauma - Two cases with striking similarities.

PubMed

Park, Hyejin; Lee, Bongwoo; Yoon, Connie

2015-10-01

There have been several forensic pathological studies on the distinction between falls from height and homicidal blows in blunt head trauma, but few studies have focused on suicidal blows. Self-inflicted blunt head trauma is usually a part of a complex suicide with more than one suicidal method applied. Actually, no reports on suicide indicate blunt head trauma to be the singular cause of death in recent publications. Cases with self-inflicted blunt trauma are often challenging for those involved in the investigation because they are confronted with findings that are also found in homicides. A refined guideline to differentiate suicidal blows from homicidal blows in blunt head trauma allows for a more accurate representation of the events surrounding death. This paper presents two cases of suicide by self-inflicted blunt head trauma in which blunt head trauma from repeatedly hitting the decedent's head with a hammer was considered to be the only cause of death. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Spatiotopic coding during dynamic head tilt

PubMed Central

Turi, Marco; Burr, David C.

2016-01-01

Humans maintain a stable representation of the visual world effortlessly, despite constant movements of the eyes, head, and body, across multiple planes. Whereas visual stability in the face of saccadic eye movements has been intensely researched, fewer studies have investigated retinal image transformations induced by head movements, especially in the frontal plane. Unlike head rotations in the horizontal and sagittal planes, tilting the head in the frontal plane is only partially counteracted by torsional eye movements and consequently induces a distortion of the retinal image to which we seem to be completely oblivious. One possible mechanism aiding perceptual stability is an active reconstruction of a spatiotopic map of the visual world, anchored in allocentric coordinates. To explore this possibility, we measured the positional motion aftereffect (PMAE; the apparent change in position after adaptation to motion) with head tilts of ∼42° between adaptation and test (to dissociate retinal from allocentric coordinates). The aftereffect was shown to have both a retinotopic and spatiotopic component. When tested with unpatterned Gaussian blobs rather than sinusoidal grating stimuli, the retinotopic component was greatly reduced, whereas the spatiotopic component remained. The results suggest that perceptual stability may be maintained at least partially through mechanisms involving spatiotopic coding. NEW & NOTEWORTHY Given that spatiotopic coding could play a key role in maintaining visual stability, we look for evidence of spatiotopic coding after retinal image transformations caused by head tilt. To this end, we measure the strength of the positional motion aftereffect (PMAE; previously shown to be largely spatiotopic after saccades) after large head tilts. We find that, as with eye movements, the spatial selectivity of the PMAE has a large spatiotopic component after head rotation. PMID:27903636

Apparent Brightness and Topography Images of Vibidia Crater

NASA Image and Video Library

2012-03-09

The left-hand image from NASA Dawn spacecraft shows the apparent brightness of asteroid Vesta surface. The right-hand image is based on this apparent brightness image, with a color-coded height representation of the topography overlain onto it.

Smoking Through a Topography Device Diminishes Some of the Acute Rewarding Effects of Smoking.

PubMed

Ross, Kathryn C; Juliano, Laura M

2016-05-01

Smoking topography (ST) devices are an important methodological tool for quantifying puffing behavior (eg, puff volume, puff velocity) as well as identifying puffing differences across individuals and situations. Available ST devices are designed such that the smoker's mouth and hands have direct contact with the device rather than the cigarette itself. Given the importance of the sensorimotor aspects of cigarette smoking in smoking reward, it is possible that ST devices may interfere with the acute rewarding effects of smoking. Despite the methodological importance of this issue, few studies have directly compared subjective reactions to smoking through a topography device to naturalistic smoking. Smokers (N = 58; 38% female) smoked their preferred brand of cigarettes one time through a portable topography device and one time naturalistically, in counterbalanced order across two laboratory sessions. Smoking behavior (eg, number of puffs) and subjective effects (eg, urge reduction, affect, smoking satisfaction) were assessed. Negative affect reduction was greater in the natural smoking condition relative to the topography condition, but differences were not significant on measures of urge, withdrawal, or positive affect. Self-reported smoking satisfaction, enjoyment of respiratory tract sensations, psychological reward, craving reduction, and other rewarding effects of smoking were also significantly greater in the naturalistic smoking condition. The effects of using a ST device on the smoking experience should be considered when it is used in research as it may diminish some of the rewarding effects of smoking. When considering the inclusion of a smoking topography device in one's research, it is important to know if use of that device will alter the smoker's experience. This study assessed affective and subjective reactions to smoking through a topography device compared to naturalistic smoking. We found that smoking satisfaction, psychological reward, enjoyment

Firing properties of rat lateral mammillary single units: head direction, head pitch, and angular head velocity.

PubMed

Stackman, R W; Taube, J S

1998-11-01

Many neurons in the rat anterodorsal thalamus (ADN) and postsubiculum (PoS) fire selectively when the rat points its head in a specific direction in the horizontal plane, independent of the animal's location and ongoing behavior. The lateral mammillary nuclei (LMN) are interconnected with both the ADN and PoS and, therefore, are in a pivotal position to influence ADN/PoS neurophysiology. To further understand how the head direction (HD) cell signal is generated, we recorded single neurons from the LMN of freely moving rats. The majority of cells discharged as a function of one of three types of spatial correlates: (1) directional heading, (2) head pitch, or (3) angular head velocity (AHV). LMN HD cells exhibited higher peak firing rates and greater range of directional firing than that of ADN and PoS HD cells. LMN HD cells were modulated by angular head velocity, turning direction, and anticipated the rat's future HD by a greater amount of time (approximately 95 msec) than that previously reported for ADN HD cells (approximately 25 msec). Most head pitch cells discharged when the rostrocaudal axis of the rat's head was orthogonal to the horizontal plane. Head pitch cell firing was independent of the rat's location, directional heading, and its body orientation (i.e., the cell discharged whenever the rat pointed its head up, whether standing on all four limbs or rearing). AHV cells were categorized as fast or slow AHV cells depending on whether their firing rate increased or decreased in proportion to angular head velocity. These data demonstrate that LMN neurons code direction and angular motion of the head in both horizontal and vertical planes and support the hypothesis that the LMN play an important role in processing both egocentric and allocentric spatial information.

Time-domain full-waveform inversion of Rayleigh and Love waves in presence of free-surface topography

NASA Astrophysics Data System (ADS)

Pan, Yudi; Gao, Lingli; Bohlen, Thomas

2018-05-01

Correct estimation of near-surface seismic-wave velocity when encountering lateral heterogeneity and free surface topography is one of the challenges to current shallow seismic. We propose to use time-domain full-waveform inversion (FWI) of surface waves, including both Rayleigh and Love waves, to solve this problem. We adopt a 2D time-domain finite-difference method with an improved vacuum formulation (IVF) to simulate shallow-seismic Rayleigh wave in presence of free-surface topography. We modify the IVF for SH-wave equation for the simulation of Love wave in presence of topographic free surface and prove its accuracy by benchmark tests. Checkboard model tests are performed in both cases when free-surface topography is included or neglected in FWI. Synthetic model containing a dipping planar free surface and lateral heterogeneity was then tested, in both cases of considering and neglecting free-surface topography. Both checkerboard and synthetic models show that Rayleigh- and Love-wave FWI have similar ability of reconstructing near-surface structures when free-surface topography is considered, while Love-wave FWI could reconstruct near-surface structures better than Rayleigh-wave when free-surface topography is neglected.

Coordinates of Human Visual and Inertial Heading Perception.

PubMed

Crane, Benjamin Thomas

2015-01-01

Heading estimation involves both inertial and visual cues. Inertial motion is sensed by the labyrinth, somatic sensation by the body, and optic flow by the retina. Because the eye and head are mobile these stimuli are sensed relative to different reference frames and it remains unclear if a perception occurs in a common reference frame. Recent neurophysiologic evidence has suggested the reference frames remain separate even at higher levels of processing but has not addressed the resulting perception. Seven human subjects experienced a 2s, 16 cm/s translation and/or a visual stimulus corresponding with this translation. For each condition 72 stimuli (360° in 5° increments) were delivered in random order. After each stimulus the subject identified the perceived heading using a mechanical dial. Some trial blocks included interleaved conditions in which the influence of ±28° of gaze and/or head position were examined. The observations were fit using a two degree-of-freedom population vector decoder (PVD) model which considered the relative sensitivity to lateral motion and coordinate system offset. For visual stimuli gaze shifts caused shifts in perceived head estimates in the direction opposite the gaze shift in all subjects. These perceptual shifts averaged 13 ± 2° for eye only gaze shifts and 17 ± 2° for eye-head gaze shifts. This finding indicates visual headings are biased towards retina coordinates. Similar gaze and head direction shifts prior to inertial headings had no significant influence on heading direction. Thus inertial headings are perceived in body-centered coordinates. Combined visual and inertial stimuli yielded intermediate results.

Coordinates of Human Visual and Inertial Heading Perception

PubMed Central

Crane, Benjamin Thomas

2015-01-01

Heading estimation involves both inertial and visual cues. Inertial motion is sensed by the labyrinth, somatic sensation by the body, and optic flow by the retina. Because the eye and head are mobile these stimuli are sensed relative to different reference frames and it remains unclear if a perception occurs in a common reference frame. Recent neurophysiologic evidence has suggested the reference frames remain separate even at higher levels of processing but has not addressed the resulting perception. Seven human subjects experienced a 2s, 16 cm/s translation and/or a visual stimulus corresponding with this translation. For each condition 72 stimuli (360° in 5° increments) were delivered in random order. After each stimulus the subject identified the perceived heading using a mechanical dial. Some trial blocks included interleaved conditions in which the influence of ±28° of gaze and/or head position were examined. The observations were fit using a two degree-of-freedom population vector decoder (PVD) model which considered the relative sensitivity to lateral motion and coordinate system offset. For visual stimuli gaze shifts caused shifts in perceived head estimates in the direction opposite the gaze shift in all subjects. These perceptual shifts averaged 13 ± 2° for eye only gaze shifts and 17 ± 2° for eye-head gaze shifts. This finding indicates visual headings are biased towards retina coordinates. Similar gaze and head direction shifts prior to inertial headings had no significant influence on heading direction. Thus inertial headings are perceived in body-centered coordinates. Combined visual and inertial stimuli yielded intermediate results. PMID:26267865

A Generalized Subsurface Flow Parameterization Considering Subgrid Spatial Variability of Recharge and Topography

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

Huang, Maoyi; Liang, Xu; Leung, Lai R.

2008-12-05

Subsurface flow is an important hydrologic process and a key component of the water budget, especially in humid regions. In this study, a new subsurface flow formulation is developed that incorporates spatial variability of both topography and recharge. It is shown through theoretical derivation and case studies that the power law and exponential subsurface flow parameterizations and the parameterization proposed by Woods et al.[1997] are all special cases of the new formulation. The subsurface flows calculated using the new formulation compare well with values derived from observations at the Tulpehocken Creek and Walnut Creek watersheds. Sensitivity studies show that whenmore » the spatial variability of topography or recharge, or both is increased, the subsurface flows increase at the two aforementioned sites and the Maimai hillslope. This is likely due to enhancement of interactions between the groundwater table and the land surface that reduce the flow path. An important conclusion of this study is that the spatial variability of recharge alone, and/or in combination with the spatial variability of topography can substantially alter the behaviors of subsurface flows. This suggests that in macroscale hydrologic models or land surface models, subgrid variations of recharge and topography can make significant contributions to the grid mean subsurface flow and must be accounted for in regions with large surface heterogeneity. This is particularly true for regions with humid climate and relatively shallow groundwater table where the combined impacts of spatial variability of recharge and topography are shown to be more important. For regions with arid climate and relatively deep groundwater table, simpler formulations, especially the power law, for subsurface flow can work well, and the impacts of subgrid variations of recharge and topography may be ignored.« less

Characterizing Arctic sea ice topography and atmospheric form drag using high-resolution IceBridge data

NASA Astrophysics Data System (ADS)

Petty, A.; Tsamados, M.; Kurtz, N. T.; Farrell, S. L.; Newman, T.; Harbeck, J.; Feltham, D. L.; Richter-Menge, J.

2015-12-01

Here we present a detailed analysis of Arctic sea ice topography using high resolution, three-dimensional surface elevation data from the NASA Operation IceBridge Airborne Topographic Mapper (ATM) laser altimeter. We derive novel ice topography statistics from 2009-2014 across both first-year and multiyear ice regimes - including the height, area coverage, orientation and spacing of distinct surface features. The sea ice topography exhibits strong spatial variability, including increased surface feature (e.g. pressure ridge) height and area coverage within the multi-year ice regions. The ice topography also shows a strong coastal dependency, with the feature height and area coverage increasing as a function of proximity to the nearest coastline, especially north of Greenland and the Canadian Archipelago. The ice topography data have also been used to explicitly calculate atmospheric drag coefficients over Arctic sea ice; utilizing existing relationships regarding ridge geometry and their impact on form drag. The results are being used to calibrate the recent drag parameterization scheme included in the sea ice model CICE.

Comparison of eye morphology and retinal topography in two species of New World vultures (Aves: Cathartidae).

PubMed

Lisney, Thomas J; Stecyk, Karyn; Kolominsky, Jeffrey; Graves, Gary R; Wylie, Douglas R; Iwaniuk, Andrew N

2013-12-01

Vultures are highly reliant on their sensory systems for the rapid detection and localization of carrion before other scavengers can exploit the resource. In this study, we compared eye morphology and retinal topography in two species of New World vultures (Cathartidae), turkey vultures (Cathartes aura), with a highly developed olfactory sense, and black vultures (Coragyps atratus), with a less developed sense of olfaction. We found that eye size relative to body mass was the same in both species, but that black vultures have larger corneas relative to eye size than turkey vultures. However, the overall retinal topography, the total number of cells in the retinal ganglion cell layer, peak and average cell densities, cell soma area frequency distributions, and the theoretical peak anatomical spatial resolving power were the same in both species. This suggests that the visual systems of these two species are similar and that vision plays an equally important role in the biology of both species, despite the apparently greater reliance on olfaction for finding carrion in turkey vultures. Copyright © 2013 Wiley Periodicals, Inc.

The Relationship of the MOLA Topography of Mars to the Mean Atmospheric Pressure

NASA Technical Reports Server (NTRS)

Smith, David E.; Zuber, Maria T.

1999-01-01

The MOLA topography of Mars is based on a new mean radius of the planet and new equipotential surface for the areoid. The mean atmospheric pressure surface of 6.1mbars that has been used in the past as a reference level for topography does not apply to the zero level of MOLA elevations. The MOLA mean radius of the planet is 3389508 meters and the mean equatorial radius is 339600 meters. The areoid of the zero level of the MOLA altimetry is defined to be the potential surface with the same potential as the mean equatorial radius. The MOLA topography differs from the USGS digital elevation data by approximately 1.6 km, with MOLA higher. The average pressure on the MOLA reference surface for Ls =0 is approximately 5.1 mbars and has been derived from occultation data obtained from the tracking of Viking, Mariner, and MGS spacecraft and interpolated with the aid of the Ames Mars GCM. The new topography and the new occultation data are providing a more reliable relationship between elevation and surface pressure.

Fatal pediatric head injury due to toppled television: does the injury pattern overlap with abusive head trauma?

PubMed

Kodikara, Sarathchandra; Pollanen, Michael

2012-07-01

Pediatric head injuries can occur from abusive head trauma (AHT) or accidents. Accidental pediatric head injuries caused by cathode-ray tube televisions (CRTT) toppling have become a 'silent epidemic'. Differentiation between a fatal case of AHT and CRTT toppling could be vexing when the historical and scene evidence are subtle. A 2-year-old girl was found unresponsive in her house and could not be resuscitated. A 27" CRTT was found fallen from its stand onto the floor at the scene. The siblings report that the deceased was climbing on the television stand when it toppled. Autopsy revealed a spectrum of head injuries including, contusions, fractures, bilateral acute subdural hemorrhages, subarachnoid hemorrhages, brain contusion-lacerations and corpus callosal hemorrhages. Microscopy of the eyes revealed bilateral acute retinal hemorrhages. The cause of death was given as crushing injuries of head and brain. The skull fracture pattern is compatible with an accident causing crush injury due to the toppled CRTT rather than AHT. The injury pattern reconfirms that the head is the most vulnerable site in case of CRTT tipover. Although there may be an overlap between the injury pattern in AHT and in CRTT tipover cases, a careful evaluation of the history and scene and autopsy findings such as the crushing nature of the skull fractures and distribution of injury, can solve this problem. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Guidance of dorsal root ganglion neurites and Schwann cells by isolated Schwann cell topography on poly(dimethyl siloxane) conduits and films

NASA Astrophysics Data System (ADS)

Richardson, J. A.; Rementer, C. W.; Bruder, Jan M.; Hoffman-Kim, D.

2011-08-01

Biomimetic replicas of cellular topography have been utilized to direct neurite outgrowth. Here, we cultured postnatal rat dorsal root ganglion (DRG) explants in the presence of Schwann cell (SC) topography to determine the influence of SC topography on neurite outgrowth. Four distinct poly(dimethyl siloxane) conduits were fabricated within which DRG explants were cultured. To determine the contribution of SC topographical features to neurite guidance, the extent of neurite outgrowth into unpatterned conduits, conduits with randomly oriented SC replicas, and conduits with SC replicas parallel or perpendicular to the conduit long axis was measured. Neurite directionality and outgrowth from DRG were also quantified on two-dimensional SC replicas with orientations corresponding to the four conduit conditions. Additionally, live SC migration and neurite extension from DRG on SC replicas were examined as a first step toward quantification of the interactions between live SC and navigating neurites on SC replicas. DRG neurite outgrowth and morphology within conduits and on two-dimensional SC replicas were directed by the underlying SC topographical features. Maximal neurite outgrowth and alignment to the underlying features were observed into parallel conduits and on parallel two-dimensional substrates, whereas the least extent of outgrowth was observed into perpendicular conduits and on perpendicular two-dimensional replica conditions. Additionally, neurites on perpendicular conditions turned to extend along the direction of underlying SC topography. Neurite outgrowth exceeded SC migration in the direction of the underlying anisotropic SC replica after two days in culture. This finding confirms the critical role that SC have in guiding neurite outgrowth and suggests that the mechanism of neurite alignment to SC replicas depends on direct contact with cellular topography. These results suggest that SC topographical replicas may be used to direct and optimize neurite

The Mystery of the Mars North Polar Gravity-Topography Correlation(Or Lack Thereof)

NASA Technical Reports Server (NTRS)

Phillips, R. J.; Sjogren, W. L.; Johnson, C. L.

1999-01-01

Maps of moderately high resolution gravity data obtained from the Mars Global Surveyor (MGS) gravity calibration orbit campaign and high precision topography obtained from the Mars Orbiter Laser Altimeter (MOLA) experiment reveal relationships between gravity and topography in high northern latitudes of Mars. Figure 1 shows the results of a JPL spherical harmonic gravity model bandpass filtered between degrees 6 and 50 contoured over a MOLA topographic image. A positive gravity anomaly exists over the main North Polar cap, but there are at least six additional positive gravity anomalies, as well as a number of smaller negative anomalies, with no obvious correlation to topography. Additional information is contained in the original extended abstract.

A Scalable Infrastructure for Lidar Topography Data Distribution, Processing, and Discovery

NASA Astrophysics Data System (ADS)

Crosby, C. J.; Nandigam, V.; Krishnan, S.; Phan, M.; Cowart, C. A.; Arrowsmith, R.; Baru, C.

2010-12-01

High-resolution topography data acquired with lidar (light detection and ranging) technology have emerged as a fundamental tool in the Earth sciences, and are also being widely utilized for ecological, planning, engineering, and environmental applications. Collected from airborne, terrestrial, and space-based platforms, these data are revolutionary because they permit analysis of geologic and biologic processes at resolutions essential for their appropriate representation. Public domain lidar data collection by federal, state, and local agencies are a valuable resource to the scientific community, however the data pose significant distribution challenges because of the volume and complexity of data that must be stored, managed, and processed. Lidar data acquisition may generate terabytes of data in the form of point clouds, digital elevation models (DEMs), and derivative products. This massive volume of data is often challenging to host for resource-limited agencies. Furthermore, these data can be technically challenging for users who lack appropriate software, computing resources, and expertise. The National Science Foundation-funded OpenTopography Facility (www.opentopography.org) has developed a cyberinfrastructure-based solution to enable online access to Earth science-oriented high-resolution lidar topography data, online processing tools, and derivative products. OpenTopography provides access to terabytes of point cloud data, standard DEMs, and Google Earth image data, all co-located with computational resources for on-demand data processing. The OpenTopography portal is built upon a cyberinfrastructure platform that utilizes a Services Oriented Architecture (SOA) to provide a modular system that is highly scalable and flexible enough to support the growing needs of the Earth science lidar community. OpenTopography strives to host and provide access to datasets as soon as they become available, and also to expose greater application level functionalities to

EAARL Coastal Topography - Northern Gulf of Mexico

USGS Publications Warehouse

Nayegandhi, Amar; Brock, John C.; Sallenger, Abby; Wright, C. Wayne; Travers, Laurinda J.; Lebonitte, James

2008-01-01

These remotely sensed, geographically referenced elevation measurements of Lidar-derived coastal topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. One objective of this research is to create techniques to survey areas for the purposes of geomorphic change studies following major storm events. The USGS Coastal and Marine Geology Program's National Assessment of Coastal Change Hazards project is a multi-year undertaking to identify and quantify the vulnerability of U.S. shorelines to coastal change hazards such as effects of severe storms, sea-level rise, and shoreline erosion and retreat. Airborne Lidar surveys conducted during periods of calm weather are compared to surveys collected following extreme storms in order to quantify the resulting coastal change. Other applications of high-resolution topography include habitat mapping, ecological monitoring, volumetric change detection, and event assessment. The purpose of this project is to provide highly detailed and accurate datasets of the northern Gulf of Mexico coastal areas, acquired on September 19, 2004, immediately following Hurricane Ivan. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Airborne Advanced Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532 nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking RGB (red-green-blue) digital camera, a high-resolution multi

Exact Riemann solutions of the Ripa model for flat and non-flat bottom topographies

NASA Astrophysics Data System (ADS)

Rehman, Asad; Ali, Ishtiaq; Qamar, Shamsul

2018-03-01

This article is concerned with the derivation of exact Riemann solutions for Ripa model considering flat and non-flat bottom topographies. The Ripa model is a system of shallow water equations accounting for horizontal temperature gradients. In the case of non-flat bottom topography, the mass, momentum and energy conservation principles are utilized to relate the left and right states across the step-type bottom topography. The resulting system of algebraic equations is solved iteratively. Different numerical case studies of physical interest are considered. The solutions obtained from developed exact Riemann solvers are compared with the approximate solutions of central upwind scheme.

Smoking Topography Characteristics of Very Low Nicotine Content Cigarettes, With and Without Nicotine Replacement, in Smokers With Schizophrenia and Controls.

PubMed

Tidey, Jennifer W; Cassidy, Rachel N; Miller, Mollie E

2016-09-01

Reducing the nicotine content of cigarettes to a minimally addictive level has been proposed as a regulatory strategy for reducing tobacco dependence. However, smokers with schizophrenia (SS) may be prone to changing their smoking topography in efforts to compensate for the reduction in nicotine content. The aims of this study were to compare smoking topography characteristics of usual-brand and very low nicotine content (VLNC) cigarettes in SS and control smokers without psychiatric illness (CS), and to determine whether nicotine replacement reversed any changes in topography produced by VLNC cigarettes. Using a within-subjects, counter-balanced design, SS (n = 27) and CS (n = 23) smoked usual brand cigarettes, VLNC cigarettes while wearing placebo patches (VLNC + PLA), or VLNC cigarettes while wearing transdermal nicotine patches totaling 42mg (VLNC + NIC) during 5-hour ad libitum smoking sessions. Cigarettes were smoked through topography measurement devices. Across conditions, SS smoked more puffs per session and per cigarette, had higher cigarette volumes, and had shorter inter-puff intervals than CS (Ps < .01). During VLNC cigarette sessions, puff duration increased and time between puffs decreased, but participants smoked fewer puffs, resulting in a net decrease in cigarette and total session volume (Ps < .001). There were no significant interactions between group and condition. These findings indicate that acute use of VLNC cigarettes does not increase intensity of smoking in SS, and support the feasibility of a nicotine reduction policy. Reducing the nicotine in cigarettes to a minimally addictive level has been proposed as a means of reducing tobacco dependence. However, smokers, particularly those with schizophrenia (SS) may alter their puffing in an attempt to extract more nicotine from VLNC cigarettes. This study compared smoking topography of usual brand versus VLNC cigarettes, combined with placebo or transdermal nicotine patches, in SS and controls

Detection of Bartonella quintana in African body and head lice.

PubMed

Sangaré, Abdoul Karim; Boutellis, Amina; Drali, Rezak; Socolovschi, Cristina; Barker, Stephen C; Diatta, Georges; Rogier, Christophe; Olive, Marie-Marie; Doumbo, Ogobara K; Raoult, Didier

2014-08-01

Currently, the body louse is the only recognized vector of Bartonella quintana, an organism that causes trench fever. In this work, we investigated the prevalence of this bacterium in human lice in different African countries. We tested 616 head lice and 424 body lice from nine African countries using real-time polymerase chain reaction targeting intergenic spacer region 2 and specific B. quintana genes. Overall, B. quintana DNA was found in 54% and 2% of body and head lice, respectively. Our results also show that there are more body lice positive for B. quintana in poor countries, which was determined by the gross domestic product, than in wealthy areas (228/403 versus 0/21, P < 0.001). A similar finding was obtained for head lice (8/226 versus 2/390, P = 0.007). Our findings suggest that head lice in Africa may be infected by B. quintana when patients live in poor economic conditions and are also exposed to body lice. © The American Society of Tropical Medicine and Hygiene.

Seismic waveform sensitivity to global boundary topography

NASA Astrophysics Data System (ADS)

Colombi, Andrea; Nissen-Meyer, Tarje; Boschi, Lapo; Giardini, Domenico

2012-09-01

We investigate the implications of lateral variations in the topography of global seismic discontinuities, in the framework of high-resolution forward modelling and seismic imaging. We run 3-D wave-propagation simulations accurate at periods of 10 s and longer, with Earth models including core-mantle boundary topography anomalies of ˜1000 km spatial wavelength and up to 10 km height. We obtain very different waveform signatures for PcP (reflected) and Pdiff (diffracted) phases, supporting the theoretical expectation that the latter are sensitive primarily to large-scale structure, whereas the former only to small scale, where large and small are relative to the frequency. PcP at 10 s seems to be well suited to map such a small-scale perturbation, whereas Pdiff at the same frequency carries faint signatures that do not allow any tomographic reconstruction. Only at higher frequency, the signature becomes stronger. We present a new algorithm to compute sensitivity kernels relating seismic traveltimes (measured by cross-correlation of observed and theoretical seismograms) to the topography of seismic discontinuities at any depth in the Earth using full 3-D wave propagation. Calculation of accurate finite-frequency sensitivity kernels is notoriously expensive, but we reduce computational costs drastically by limiting ourselves to spherically symmetric reference models, and exploiting the axial symmetry of the resulting propagating wavefield that collapses to a 2-D numerical domain. We compute and analyse a suite of kernels for upper and lower mantle discontinuities that can be used for finite-frequency waveform inversion. The PcP and Pdiff sensitivity footprints are in good agreement with the result obtained cross-correlating perturbed and unperturbed seismogram, validating our approach against full 3-D modelling to invert for such structures.

Cooperative control of blood compatibility and re-endothelialization by immobilized heparin and substrate topography.

PubMed

Ding, Yonghui; Yang, Meng; Yang, Zhilu; Luo, Rifang; Lu, Xiong; Huang, Nan; Huang, Pingbo; Leng, Yang

2015-03-01

A wide variety of environmental cues provided by the extracellular matrix, including biophysical and biochemical cues, are responsible for vascular cell behavior and function. In particular, substrate topography and surface chemistry have been shown to regulate blood and vascular compatibility individually. The combined impact of chemical and topographic cues on blood and vascular compatibility, and the interplay between these two types of cues, are subjects that are currently being explored. In the present study, a facile polydopamine-mediated approach is introduced for immobilization of heparin on topographically patterned substrates, and the combined effects of these cues on blood compatibility and re-endothelialization are systematically investigated. The results show that immobilized heparin and substrate topography cooperatively modulate anti-coagulation activity, endothelial cell (EC) attachment, proliferation, focal adhesion formation and endothelial marker expression. Meanwhile, the substrate topography is the primary determinant of cell alignment and elongation, driving in vivo-like endothelial organization. Importantly, combining immobilized heparin with substrate topography empowers substantially greater competitive ability of ECs over smooth muscle cells than each cue individually. Moreover, a model is proposed to elucidate the cooperative interplay between immobilized heparin and substrate topography in regulating cell behavior. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

High resolution, monochromatic x-ray topography capability at CHESS

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

Finkelstein, K. D., E-mail: kdf1@cornell.edu; Pauling, A.; Brown, Z.

2016-07-27

CHESS has a monochromatic x-ray topography capability serving continually expanding user interest. The setup consists of a beam expanding monochromator, 6-circle diffactometer, and CHESS designed CMOS camera with real time sample-alignment capability. This provides rocking curve mapping with angle resolution as small as 2 µradians, spatial resolution to 3 microns, and field of view up to 7mm. Thus far the capability has been applied for: improving CVD-diamond growth, evaluating perfection of ultra-thin diamond membranes, correlating performance of diamond-based electronics with crystal defect structure, and defect analysis of single crystal silicon carbide. This paper describes our topography system, explains its capabilities,more » and presents experimental results from several applications.« less

Topography of the Moon from the Clementine Lidar

NASA Technical Reports Server (NTRS)

Smith, David E.; Zuber, Maria T.; Neumann, Gregory A.; Lemoine, Frank G.

1997-01-01

Range measurements from the lidar instrument carried aboard the Clementine spacecraft have been used to produce an accurate global topographic model of the Moon. This paper discusses the function of the lidar; the acquisition, processing, and filtering of observations to produce a global topographic model; and the determination of parameters that define the fundamental shape of the Moon. Our topographic model: a 72nd degree and order spherical harmonic expansion of lunar radii, is designated Goddard Lunar Topography Model 2 (GLTM 2). This topographic field has an absolute vertical accuracy of approximately 100 m and a spatial resolution of 2.5 deg. The field shows that the Moon can be described as a sphere with maximum positive and negative deviations of approx. 8 km, both occurring on the farside, in the areas of the Korolev and South Pole-Aitken (S.P.-Aitken) basins. The amplitude spectrum of the topography shows more power at longer wavelengths as compared to previous models, owing to more complete sampling of the surface, particularly the farside. A comparison of elevations derived from the Clementine lidar to control point elevations from the Apollo laser altimeters indicates that measured relative topographic heights generally agree to within approx. 200 in over the maria. While the major axis of the lunar gravity field is aligned in the Earth-Moon direction, the major axis of topography is displaced from this line by approximately 10 deg to the cast and intersects the farside 24 deg north of the equator. The magnitude of impact basin topography is greater than the lunar flattening (approx. 2 km) and equatorial ellipticity (approx. 800 m), which imposes a significant challenge to interpreting the lunar figure. The floors of mare basins are shown to lie close to an equipotential surface, while the floors of unflooded large basins, except for S.P.-Aitken, lie above this equipotential. The radii of basin floors are thus consistent with a hydrostatic mechanism

Head-Neck Biomechanics in Simulated Rear Impact

PubMed Central

Yoganandan, Narayan; Pintar, Frank A.; Cusick, Joseph F.; Kleinberger, Michael

1998-01-01

The first objective of this study is to present an overview of the human cadaver studies aimed to determine the biomechanics of the head-neck in a simulated rear crash. The need for kinematic studies to better understand the mechanisms of load transfer to the human head-neck complex is emphasized. Based on this need, a methodology is developed to delineate the dynamic kinematics of the human head-neck complex. Intact human cadaver head-neck complexes were subjected to postero-anterior impact using a mini-sled pendulum device. The integrity of the soft tissues including the musculature and skin were maintained. The kinematic data were recorded using high-speed photography coupled with retroreflective targets placed at various regions of the human head-neck complex. The overall and segmental kinematics of the entire head-neck complex, and the localized facet joint motions were determined. During the initial stages of loading, a transient decoupling of the head occurred with respect to the neck exhibiting a lag of the cranium. The upper cervical spine-head undergoes local flexion concomitant with a lag of the head while the lower cervical spinal column is in local extension. This establishes a reverse curvature to the cervical head-neck complex. With continued loading, head motion ensues and approximately at the end of the loading phase, the entire head-neck complex is under the extension mode with a single curvature. In contrast, the lower cervical spine facet joint kinematics show varying compression and sliding. While both the anterior and posterior-most regions of the facet joint slide, the posterior-most region (mean: 2.84 mm) of the joint compresses more than the anterior-most (mean: 2.02 mm) region. These varying kinematics at the ends of the facet joint result in a pinching mechanism. These biomechanical kinematic findings may be correlated to the presence of headaches and neck pain (Lord, Bogduk et al. 1992; Barnsley, Lord et al. 1995), based on the unique

Soil resources and topography shape local tree community structure in tropical forests

PubMed Central

Baldeck, Claire A.; Harms, Kyle E.; Yavitt, Joseph B.; John, Robert; Turner, Benjamin L.; Valencia, Renato; Navarrete, Hugo; Davies, Stuart J.; Chuyong, George B.; Kenfack, David; Thomas, Duncan W.; Madawala, Sumedha; Gunatilleke, Nimal; Gunatilleke, Savitri; Bunyavejchewin, Sarayudh; Kiratiprayoon, Somboon; Yaacob, Adzmi; Supardi, Mohd N. Nur; Dalling, James W.

2013-01-01

Both habitat filtering and dispersal limitation influence the compositional structure of forest communities, but previous studies examining the relative contributions of these processes with variation partitioning have primarily used topography to represent the influence of the environment. Here, we bring together data on both topography and soil resource variation within eight large (24–50 ha) tropical forest plots, and use variation partitioning to decompose community compositional variation into fractions explained by spatial, soil resource and topographic variables. Both soil resources and topography account for significant and approximately equal variation in tree community composition (9–34% and 5–29%, respectively), and all environmental variables together explain 13–39% of compositional variation within a plot. A large fraction of variation (19–37%) was spatially structured, yet unexplained by the environment, suggesting an important role for dispersal processes and unmeasured environmental variables. For the majority of sites, adding soil resource variables to topography nearly doubled the inferred role of habitat filtering, accounting for variation in compositional structure that would previously have been attributable to dispersal. Our results, illustrated using a new graphical depiction of community structure within these plots, demonstrate the importance of small-scale environmental variation in shaping local community structure in diverse tropical forests around the globe. PMID:23256196

RhoA-Mediated Functions in C3H10T1/2 Osteoprogenitors Are Substrate Topography Dependent.

PubMed

Ogino, Yoichiro; Liang, Ruiwei; Mendonça, Daniela B S; Mendonça, Gustavo; Nagasawa, Masako; Koyano, Kiyoshi; Cooper, Lyndon F

2016-03-01

Surface topography broadly influences cellular responses. Adherent cell activities are regulated, in part, by RhoA, a member of the Rho-family of GTPases. In this study, we evaluated the influence of surface topography on RhoA activity and associated cellular functions. The murine mesenchymal stem cell line C3H10T1/2 cells (osteoprogenitor cells) were cultured on titanium substrates with smooth topography (S), microtopography (M), and nanotopography (N) to evaluate the effect of surface topography on RhoA-mediated functions (cell spreading, adhesion, migration, and osteogenic differentiation). The influence of RhoA activity in the context of surface topography was also elucidated using RhoA pharmacologic inhibitor. Following adhesion, M and N adherent cells developed multiple projections, while S adherent cells had flattened and widespread morphology. RhoA inhibitor induced remarkable longer and thinner cytoplasmic projections on all surfaces. Cell adhesion and osteogenic differentiation was topography dependent with S < M and N surfaces. RhoA inhibition increased adhesion on S and M surfaces, but not N surfaces. Cell migration in a wound healing assay was greater on S versus M versus N surfaces and RhoA inhibitor increased S adherent cell migration, but not N adherent cell migration. RhoA inhibitor enhanced osteogenic differentiation in S adherent cells, but not M or N adherent cells. RhoA activity was surface topography roughness dependent (S < M, N). RhoA activity and -mediated functions are influenced by surface topography. Smooth surface adherent cells appear highly sensitive to RhoA function, while nano-scale topography adherent cell may utilize alternative cellular signaling pathway(s) to influence adherent cellular functions regardless of RhoA activity. © 2015 Wiley Periodicals, Inc.

Cosmic ray topography

NASA Astrophysics Data System (ADS)

Bressler, Matthew; Goodwin, Lydia; Kryemadhi, Abaz

2017-11-01

Cosmic ray muons are produced when high energy particles interact with nuclei in Earth's atmosphere. Muons make up the majority of charged particles that reach sea level and are the only particles (apart from neutrinos) that can penetrate to significant depths underground. The muon flux underground decreases approximately exponentially as a function of depth. We use a cosmic ray detector developed by the QuarkNet Program at Fermi National Laboratory to map the topography of the mountain above an abandoned Pennsylvania Turnpike tunnel by analyzing muon flux at different rock overburdens. Cosmic ray muons have been used in this capacity before to search for hidden chambers in pyramids and for mapping volcanoes. This study provides a unique field experience to learn about particle physics and particle detectors, which could be of interest to students and teachers in physics.

[Topography and mechanical property of goat temporomandibular joint disc cells].

PubMed

Bao, Guangjie; Kong, Nannan; Guo, Manli; Su, Xuelian; Kang, Hong

2015-08-01

This study is performed to investigate the cell topographies and biomechanical properties of two different types of temporomandibular joint (TMJ) discs from goats by using JPK Nano Wizard 3 biological atomic force microscopy (AFM). This process provides a guideline for selecting seed cells for TMJ disc tissue engineering. TMJ disc cells from primary goats were cultured by monolayer culture method. AFM was used to contact scan the topographies of the two types of TMJ disc cells under physiological environment. Approximately 20 chondrocyte-like and fibroblast-like cells were selected randomly to plot the force-versus-distance curves of the cytoplasm and nucleus. Young's modulus and adhesion were analyzed by JPK Data Processing. The triangle-shapednucleus of the chondrocyte-like cell occupied a large portion of the cell. Cytoskeleton was arranged dendritically on the surface. Pseudopodia were extended from cell edges. The spindle-shaped nucleus of the fibroblast-like cell occupied a significantly larger region compared with the cytoplasmic region. Cytoskeleton was arranged regularly. Cell edges were smooth with less pseudopodia extended. No difference was found in the surface roughness between the two types of cells. According to the force-versus-distance curves, the Young's moduli of the two types of cells were not statistically different (P>0.05), but differences were found in the cytoplasmic regions (P=0.047). No statistical difference was found in the adhesions between the two types of cells (P>0.05). The AFM topography and curves were compared and analyzed. The two types of TMJ disc cells exhibited significantly different topographies, but only slight difference in their mechanical abilities.

Investigating the Relationship Between Dynamic Topography and Sediment Flux in Africa

NASA Astrophysics Data System (ADS)

Walford, H. L.; White, N. J.

2002-12-01

It is generally accepted that the `basin and swell' topography of Africa is maintained by circulation within the mantle. Many swells are volcano-capped, and their topographic expression shows a close correlation with the long wavelength (>1000 km) free-air gravity anomaly, which can be regarded as a proxy for the convective pattern. Tomographic studies have revealed a region of slow seismic velocities in the lower mantle beneath the `African Superswell', a region of anomalously high elevation that stretches from the South Atlantic Ocean across southern Africa to the volcanic hot spot beneath Afar. Models based on gravity or seismology offer little constraint on the timing and development of dynamic topography since these observations are restricted to the present day. Recently, tomographic data has been combined with geomorphologically derived uplift rates from southern Africa, providing useful temporal constraints for dynamical modelling. Another way to investigate the history of dynamic topography is to interrogate the stratigraphic record. Africa is almost entirely surrounded by passive continental margins, formed during the break-up of Gondwana in the Mesozoic. Sediment has been accumulating on these margins throughout the Cenozoic, providing an indirect record of onshore vertical motions. The development of `basin and swell' topography together with epeirogenic uplift caused by the African Superswell would have had a profound effect on the drainage systems of the entire continent. 40% of the African continent is drained by just 6 rivers, which have formed large deltas on the continental shelf (i.e. Nile, Congo, Niger, Zambezi, Orange and Ogooue). Elevation of a catchment area is a primary control on the amount of sediment supplied to a major delta. Hence, by calculating the sediment flux to the deltas of Africa as a function of time, the history of vertical motions can be indirectly constrained. Analysis of several deltas reveals a widespread modification of

Pluto Topography and Composition Map

NASA Image and Video Library

2017-09-28

These maps are from New Horizons' data on the topography (top) and composition (bottom) of Pluto's surface. In the high-resolution topographical map, the highlighted red region is high in elevation. The map below, showing the composition, indicates the same section also contains methane, color-coded in orange. One can see the orange features spread into the fuzzier, lower-resolution data that covers the rest of the globe, meaning those areas, too, are high in methane, and therefore likely to be high in elevation. https://photojournal.jpl.nasa.gov/catalog/PIA22036

Higher order statistics of planetary gravities and topographies

NASA Technical Reports Server (NTRS)

Kaula, William M.

1993-01-01

The statistical properties of Earth, Venus, Mars, Moon, and a 3-D mantle convection model are compared. The higher order properties are expressed by third and fourth moments: i.e., as mean products over equilateral triangles (defined as coskewance) and equilateral quadrangles (defined as coexance). For point values, all the fields of real planets have positive skewness, ranging from slightly above zero for Lunar gravity to 2.6 sigma(exp 3) for Martian gravity (sigma is rms magnitude). Six of the eight excesses are greater than Gaussian (3 sigma(exp 4)), ranging from 2.0 sigma(exp 4) for Earth topography to 18.6 sigma(exp 4), for Martian topography. The coskewances and coexances drop off to zero within 20 deg arc in most cases. The mantle convective model has zero skewness and excess slightly less than Gaussian, probably arising from viscosity variations being only radial.

Self-Powered Active Sensor with Concentric Topography of Piezoelectric Fibers

NASA Astrophysics Data System (ADS)

Fuh, Yiin Kuen; Huang, Zih Ming; Wang, Bo Sheng; Li, Shan Chien

2017-01-01

In this study, we demonstrated a flexible and self-powered sensor based on piezoelectric fibers in the diameter range of nano- and micro-scales. Our work is distinctively different from previous electrospinning research; we fabricated this apparatus precisely via near-field electrospinning which has a spectacular performance to harvest mechanical deformation in arbitrary direction and a novel concentrically circular topography. There are many piezoelectric devices based on electrospinning polymeric fibers. However, the fibers were mostly patterned in parallel lines and they could be actuated in limited direction only. To overcome this predicament, we re-arranged the parallel alignment into concentric circle pattern which made it possible to collect the mechanical energy whenever the deformation is along same axis or not. Despite the change of topography, the output voltage and current could still reach to 5 V and 400 nA, respectively, despite the mechanical deformation was from different direction. This new arbitrarily directional piezoelectric generator with concentrically circular topography (PGCT) allowed the piezoelectric device to harvest more mechanical energy than the one-directional alignment fiber-based devices, and this PGCT could perform even better output which promised more versatile and efficient using as a wearable electronics or sensor.

Density interface topography recovered by inversion of satellite gravity gradiometry observations

NASA Astrophysics Data System (ADS)

Ramillien, G. L.

2017-08-01

A radial integration of spherical mass elements (i.e. tesseroids) is presented for evaluating the six components of the second-order gravity gradient (i.e. second derivatives of the Newtonian mass integral for the gravitational potential) created by an uneven spherical topography consisting of juxtaposed vertical prisms. The method uses Legendre polynomial series and takes elastic compensation of the topography by the Earth's surface into account. The speed of computation of the polynomial series increases logically with the observing altitude from the source of anomaly. Such a forward modelling can be easily applied for reduction of observed gravity gradient anomalies by the effects of any spherical interface of density. An iterative least-squares inversion of measured gravity gradient coefficients is also proposed to estimate a regional set of juxtaposed topographic heights. Several tests of recovery have been made by considering simulated gradients created by idealistic conical and irregular Great Meteor seamount topographies, and for varying satellite altitudes and testing different levels of uncertainty. In the case of gravity gradients measured at a GOCE-type altitude of ˜ 300 km, the search converges down to a stable but smooth topography after 10-15 iterations, while the final root-mean-square error is ˜ 100 m that represents only 2 % of the seamount amplitude. This recovery error decreases with the altitude of the gravity gradient observations by revealing more topographic details in the region of survey.

Three-dimensional optical topography of brain activity in infants watching videos of human movement

NASA Astrophysics Data System (ADS)

Correia, Teresa; Lloyd-Fox, Sarah; Everdell, Nick; Blasi, Anna; Elwell, Clare; Hebden, Jeremy C.; Gibson, Adam

2012-03-01

We present 3D optical topography images reconstructed from data obtained previously while infants observed videos of adults making natural movements of their eyes and hands. The optical topography probe was placed over the temporal cortex, which in adults is responsible for cognitive processing of similar stimuli. Increases in oxyhaemoglobin were measured and reconstructed using a multispectral imaging algorithm with spatially variant regularization to optimize depth discrimination. The 3D optical topography images suggest that similar brain regions are activated in infants and adults. Images were presented showing the distribution of activation in a plane parallel to the surface, as well as changes in activation with depth. The time-course of activation was followed in the pixel which demonstrated the largest change, showing that changes could be measured with high temporal resolution. These results suggest that infants a few months old have regions which are specialized for reacting to human activity, and that these subtle changes can be effectively analysed using 3D optical topography.

Who Drops out of Early Head Start Home Visiting Programs?

ERIC Educational Resources Information Center

Roggman, Lori A.; Cook, Gina A.; Peterson, Carla A.; Raikes, Helen H.

2008-01-01

Research Findings: Early Head Start home-based programs provide services through weekly home visits to families with children up to age 3, but families vary in how long they remain enrolled. In this study of 564 families in home-based Early Head Start programs, "dropping out" was predicted by specific variations in home visits and certain family…

Influence of Extracellular Matrix Proteins and Substratum Topography on Corneal Epithelial Cell Alignment and Migration

PubMed Central

Raghunathan, VijayKrishna; McKee, Clayton; Cheung, Wai; Naik, Rachel; Nealey, Paul F.; Russell, Paul

2013-01-01

The basement membrane (BM) of the corneal epithelium presents biophysical cues in the form of topography and compliance that can impact the phenotype and behaviors of cells and their nuclei through modulation of cytoskeletal dynamics. In addition, it is also well known that the intrinsic biochemical attributes of BMs can modulate cell behaviors. In this study, the influence of the combination of exogenous coating of extracellular matrix proteins (ECM) (fibronectin-collagen [FNC]) with substratum topography was investigated on cytoskeletal architecture as well as alignment and migration of immortalized corneal epithelial cells. In the absence of FNC coating, a significantly greater percentage of cells aligned parallel with the long axis of the underlying anisotropically ordered topographic features; however, their ability to migrate was impaired. Additionally, changes in the surface area, elongation, and orientation of cytoskeletal elements were differentially influenced by the presence or absence of FNC. These results suggest that the effects of topographic cues on cells are modulated by the presence of surface-associated ECM proteins. These findings have relevance to experiments using cell cultureware with biomimetic biophysical attributes as well as the integration of biophysical cues in tissue-engineering strategies and the development of improved prosthetics. PMID:23488816

New Global Bathymetry and Topography Model Grids

NASA Astrophysics Data System (ADS)

Smith, W. H.; Sandwell, D. T.; Marks, K. M.

2008-12-01

A new version of the "Smith and Sandwell" global marine topography model is available in two formats. A one-arc-minute Mercator projected grid covering latitudes to +/- 80.738 degrees is available in the "img" file format. Also available is a 30-arc-second version in latitude and longitude coordinates from pole to pole, supplied as tiles covering the same areas as the SRTM30 land topography data set. The new effort follows the Smith and Sandwell recipe, using publicly available and quality controlled single- and multi-beam echo soundings where possible and filling the gaps in the oceans with estimates derived from marine gravity anomalies observed by satellite altimetry. The altimeter data have been reprocessed to reduce the noise level and improve the spatial resolution [see Sandwell and Smith, this meeting]. The echo soundings database has grown enormously with new infusions of data from the U.S. Naval Oceanographic Office (NAVO), the National Geospatial-intelligence Agency (NGA), hydrographic offices around the world volunteering through the International Hydrographic Organization (IHO), and many other agencies and academic sources worldwide. These new data contributions have filled many holes: 50% of ocean grid points are within 8 km of a sounding point, 75% are within 24 km, and 90% are within 57 km. However, in the remote ocean basins some gaps still remain: 5% of the ocean grid points are more than 85 km from the nearest sounding control, and 1% are more than 173 km away. Both versions of the grid include a companion grid of source file numbers, so that control points may be mapped and traced to sources. We have compared the new model to multi-beam data not used in the compilation and find that 50% of differences are less than 25 m, 95% of differences are less than 130 m, but a few large differences remain in areas of poor sounding control and large-amplitude gravity anomalies. Land values in the solution are taken from SRTM30v2, GTOPO30 and ICESAT data

Topography measurements and applications in ballistics and tool mark identifications*

PubMed Central

Vorburger, T V; Song, J; Petraco, N

2016-01-01

The application of surface topography measurement methods to the field of firearm and toolmark analysis is fairly new. The field has been boosted by the development of a number of competing optical methods, which has improved the speed and accuracy of surface topography acquisitions. We describe here some of these measurement methods as well as several analytical methods for assessing similarities and differences among pairs of surfaces. We also provide a few examples of research results to identify cartridge cases originating from the same firearm or tool marks produced by the same tool. Physical standards and issues of traceability are also discussed. PMID:27182440

The Space-Time Topography of English Speakers

ERIC Educational Resources Information Center

Duman, Steve

2016-01-01

English speakers talk and think about Time in terms of physical space. The past is behind us, and the future is in front of us. In this way, we "map" space onto Time. This dissertation addresses the specificity of this physical space, or its topography. Inspired by languages like Yupno (Nunez, et al., 2012) and Bamileke-Dschang (Hyman,…

Evaluation of emergency medicine discharge instructions in pediatric head injury.

PubMed

Sarsfield, Matthew J; Morley, Eric J; Callahan, James M; Grant, William D; Wojcik, Susan M

2013-08-01

Pediatric head trauma is a common occurrence. There is mounting evidence that even patients with minor head injury require limits on school activities and/or removal from sports and play to help speed recovery and limit morbidity. The objective of this study was to determine whether discharge instructions given to children who had sustained head injuries included information regarding activity restrictions, activity time constraints, and/or specifics of follow-up care. This was a retrospective chart review of patients aged 2 to 18 years evaluated and treated for head injury during a 4-month period at a level I trauma center (volume ∼23,000 pediatric patients per year). Included were those children seen, evaluated, and diagnosed with any of the following: mild head injury, concussion, minor head trauma, or mild traumatic brain injury (mTBI). Subjects were excluded if there was a positive acute head injury computed tomography finding (other than findings of a simple linear skull fracture) or if the subject required admission. Among the 204 patients meeting eligibility, 95.1% received instruction to follow up with a physician, 82.8% received anticipatory guidance regarding expected symptoms, 15.2% received specific restriction time from sports, and 21.5% were removed from sports. Of these patients, 113 patients were determined "likely" to have sustained an mTBI. Patients with sports-related mTBI received return-to-sports restrictions (χ2 = 11.225, P < 0.008) and to remove the child from play (χ2 = 9.781, P < 0.004) as discharge instructions significantly more than did patients with motor vehicle accident or other mechanisms of injury. Children sustaining head injury were inadequately instructed to restrict athletic activities upon discharge. This is particularly true for patients who sustain an mTBI from non-sports-related activity.

Fever in pregnancy and offspring head circumference.

PubMed

Dreier, Julie Werenberg; Strandberg-Larsen, Katrine; Uldall, Peter Vilhelm; Nybo Andersen, Anne-Marie

2018-02-01

To examine whether maternal fever during pregnancy is associated with reduced head circumference and risk of microcephaly at birth. A prospective study of 86,980 live-born singletons within the Danish National Birth Cohort was carried out. Self-reported maternal fever exposure was ascertained in two interviews during pregnancy and information on head circumference at birth was extracted from the Danish Medical Birth Registry. Fever in pregnancy was reported by 27% of the mothers, and we identified 3370 cases of microcephaly (head circumference less than or equal to third percentile for sex and gestational age) and 1140 cases of severe microcephaly (head circumference less than or equal to first percentile for sex and gestational age). In this study, maternal fever exposure was not associated with reduced head circumference (adjusted β = 0.03, 95% confidence intervals [CI]: 0.01-0.05), increased risk of microcephaly (odds ratio: 0.95, 95% CI: 0.88-1.03) nor severe microcephaly (odds ratio: 1.01, 95% CI: 0.88-1.15) in the offspring. These findings were consistent for increasing numbers of fever episodes, for increasing fever severity, and for exposure in both early pregnancy and midpregnancy. In this most comprehensive study to date, we found no indication that maternal fever in pregnancy is associated with small head size in the offspring. Copyright © 2017 Elsevier Inc. All rights reserved.

Examining Daily Electronic Cigarette Puff Topography Among Established and Non-established Cigarette Smokers in their Natural Environment.

PubMed

Lee, Youn Ok; Nonnemaker, James M; Bradfield, Brian; Hensel, Edward C; Robinson, Risa J

2017-10-04

Understanding exposures and potential health effects of ecigarettes is complex. Users' puffing behavior, or topography, affects function of ecigarette devices (e.g., coil temperature) and composition of their emissions. Users with different topographies are likely exposed to different amounts of any harmful or potentially harmful constituents (HPHCs). In this study, we compare ecigarette topographies of established cigarette smokers and non-established cigarette smokers. Data measuring e-cigarette topography were collected using a wireless hand-held monitoring device in users' everyday lives over 1 week. Young adult (aged 18-25) participants (N=20) used disposable e-cigarettes with the monitor as they normally would and responded to online surveys. Topography characteristics of established versus non-established cigarette smokers were compared. On average, established cigarette smokers in the sample had larger first puff volume (130.9ml vs. 56.0ml, p<.05) and larger puff volume per session (1,509.3ml vs. 651.7ml, p<.05) compared with non-established smokers. At marginal significance, they had longer sessions (566.3s vs. 279.7s, p=.06) and used e-cigarettes more sessions per day (5.3s vs. 3.5s, p=.14). Established cigarette smokers also used ecigarettes for longer puff durations (3.3s vs. 1.8s, p<.01) and had larger puff volume (110.3ml vs. 54.7ml, p<.05) compared with non-established smokers. At marginal significance, they had longer puff interval (38.1s vs. 21.7s, p=.05). Our results demonstrate that topography characteristics differ by level of current cigarette smoking. This suggests that exposures to constituents of e-cigarettes depends on user characteristics and that specific topography parameters may be needed for different user populations when assessing ecigarette health effects. A user's topography affects his or her exposure to HPHCs. As this study demonstrates, user characteristics, such as level of smoking, can influence topography. Thus, it is crucial

Localized Gravity/Topography Admittance and Correlation Spectra on Mars: Implications for Regional and Global Evolution

NASA Technical Reports Server (NTRS)

McGovern, Patrick J.; Solomon, Sean C.; Smith, David E.; Zuber, Maria T.; Simons, Mark; Wieczorek, Mark A.; Phillips, Roger J.; Neumann, Gregory A.; Aharonson, Oded; Head, James W.

2002-01-01

[i] From gravity and topography data collected by the Mars Global Surveyor spacecraft we calculate gravity/topography admittances and correlations in the spectral domain and compare them to those predicted from models of lithospheric flexure. On the basis of these comparisons we estimate the thickness of the Martian elastic lithosphere (T(sub e)) required to support the observed topographic load since the time of loading. We convert T(sub e) to estimates of heat flux and thermal gradient in the lithosphere through a consideration of the response of an elastic/plastic shell. In regions of high topography on Mars (e.g., the Tharsis rise and associated shield volcanoes), the mass-sheet (small-amplitude) approximation for the calculation of gravity from topography is inadequate. A correction that accounts for finite-amplitude topography tends to increase the amplitude of the predicted gravity signal at spacecraft altitudes. Proper implementation of this correction requires the use of radii from the center of mass (collectively known as the planetary shape ) in lieu of topography referenced to a gravitational equipotential. Anomalously dense surface layers or buried excess masses are not required to explain the observed admittances for the Tharsis Montes or Olympus Mons volcanoes when this correction is applied. Derived T, values generally decrease with increasing age of the lithospheric load, in a manner consistent with a rapid decline of mantle heat flux during the Noachian and more modest rates of decline during subsequent epochs.

Less head motion during MRI under task than resting-state conditions.

PubMed

Huijbers, Willem; Van Dijk, Koene R A; Boenniger, Meta M; Stirnberg, Rüdiger; Breteler, Monique M B

2017-02-15

Head motion reduces data quality of neuroimaging data. In three functional magnetic resonance imaging (MRI) experiments we demonstrate that people make less head movements under task than resting-state conditions. In Experiment 1, we observed less head motion during a memory encoding task than during the resting-state condition. In Experiment 2, using publicly shared data from the UCLA Consortium for Neuropsychiatric Phenomics LA5c Study, we again found less head motion during several active task conditions than during a resting-state condition, although some task conditions also showed comparable motion. In the healthy controls, we found more head motion in men than in women and more motion with increasing age. When comparing clinical groups, we found that patients with a clinical diagnosis of bipolar disorder, or schizophrenia, move more compared to healthy controls or patients with ADHD. Both these experiments had a fixed acquisition order across participants, and we could not rule out that a first or last scan during a session might be particularly prone to more head motion. Therefore, we conducted Experiment 3, in which we collected several task and resting-state fMRI runs with an acquisition order counter-balanced. The results of Experiment 3 show again less head motion during several task conditions than during rest. Together these experiments demonstrate that small head motions occur during MRI even with careful instruction to remain still and fixation with foam pillows, but that head motion is lower when participants are engaged in a cognitive task. These finding may inform the choice of functional runs when studying difficult-to-scan populations, such as children or certain patient populations. Our findings also indicate that differences in head motion complicate direct comparisons of measures of functional neuronal networks between task and resting-state fMRI because of potential differences in data quality. In practice, a task to reduce head motion

Continental collision slowing due to viscous mantle lithosphere rather than topography.

PubMed

Clark, Marin Kristen

2012-02-29

Because the inertia of tectonic plates is negligible, plate velocities result from the balance of forces acting at plate margins and along their base. Observations of past plate motion derived from marine magnetic anomalies provide evidence of how continental deformation may contribute to plate driving forces. A decrease in convergence rate at the inception of continental collision is expected because of the greater buoyancy of continental than oceanic lithosphere, but post-collisional rates are less well understood. Slowing of convergence has generally been attributed to the development of high topography that further resists convergent motion; however, the role of deforming continental mantle lithosphere on plate motions has not previously been considered. Here I show that the rate of India's penetration into Eurasia has decreased exponentially since their collision. The exponential decrease in convergence rate suggests that contractional strain across Tibet has been constant throughout the collision at a rate of 7.03 × 10(-16) s(-1), which matches the current rate. A constant bulk strain rate of the orogen suggests that convergent motion is resisted by constant average stress (constant force) applied to a relatively uniform layer or interface at depth. This finding follows new evidence that the mantle lithosphere beneath Tibet is intact, which supports the interpretation that the long-term strain history of Tibet reflects deformation of the mantle lithosphere. Under conditions of constant stress and strength, the deforming continental lithosphere creates a type of viscous resistance that affects plate motion irrespective of how topography evolved.

CT-detected intracranial hemorrhage among patients with head injury in Lagos, Nigeria.

PubMed

Eze, Cletus Uche; Abonyi, Livinus Chibuzo; Olowoyeye, Omodele; Njoku, Jerome; Ohagwu, Christopher; Babalola, Sherifat

2013-01-01

To evaluate the computed tomography (CT) findings of intracranial hemorrhage among patients with head trauma in Lagos, Nigeria. In this retrospective, cross-sectional study, a convenience sample of 500 patients with head trauma who had diagnostic cranial CT scans was selected. All the radiological reports and CT scans of patients with head trauma were retrieved in the hospitals selected as study sites. The reports were sorted into 2 groups - normal findings and intracranial bleeding. The reports of intracranial bleeding were sorted again into different classes of intracranial bleeding as identified by the radiologist who reported it. All data were analyzed using the Epi Info public domain software package. The chi-square test was used to measure the statistical significance of study results at P < .05. Most of the study subjects (68%) were men. Traffic accidents accounted for 44% of all the head traumas found in the study, and 58% of the head traumas resulted in intracranial bleeding. Among the hemorrhages found, 37% were intracerebral, 25% were subdural, 16% were intraventricular, 15% were subarachnoid, and 7% were epidural. Intracranial hemorrhage was a common consequence of acute head trauma sustained from traffic accidents in the population studied, with intracerebral hemorrhage being the most prevalent type. Traffic accidents are the main cause of acute head trauma in Lagos, Nigeria. The use of CT for early diagnosis of intracranial hemorrhage appears justifiable.

Head circumference

MedlinePlus

... a child's head circumference. Normal ranges for a child's sex and age (weeks, months), based on values that experts have obtained for normal growth rates of infants' and children's heads. Measurement of the head circumference is an ...

Reforestation and topography affect montane soil properties, nitrogen pools, and nitrogen transformations in Hawaii

Treesearch

Paul G. Scowcroft; Janis E. Haraguchi; Nguyen V. Hue

2004-01-01

Land use changes, such as deforestation and reforestation, modify not only the organisms inhabiting affected areas, but also above-and belowground environments. Topography further influences local vegetation and environment. Effects of topography and re-establishment of N-fixing koa (Acacia koa A. Gray) trees in +100-yr-old montane grassland on...

Computed tomography of the head for adult patients with minor head injury: are clinical decision rules a necessary evil?

PubMed Central

Tan, Desmond Wei; Lim, Annabelle Mei En; Ong, Daniel Yuxuan; Peng, Li Lee; Chan, Yiong Huak; Ibrahim, Irwani; Kuan, Win Sen

2018-01-01

INTRODUCTION This study aimed to evaluate compliance with and performance of the Canadian Computed Tomography Head Rule (CCHR), and its applicability to the Singapore adult population with minor head injury. METHODS We conducted a retrospective study over six months of consecutive patients who presented to the adult emergency department (ED) with minor head injury. Data on predictor variables indicated in the CCHR was collected and compliance with the CCHR was assessed by comparing the recommendations for head computed tomography (CT) to its actual usage. RESULTS In total, 349 patients satisfied the inclusion criteria. Common mechanisms of injury were falls (59.3%), motor vehicle crashes (16.9%) and assault (12.0%). 249 (71.3%) patients underwent head CT, yielding 42 (12.0%) clinically significant findings. 1 (0.3%) patient required neurosurgical intervention. According to the CCHR, head CT was recommended for 209 (59.9%) patients. Compliance with the CCHR was 71.3%. Among the noncompliant group, head CT was overperformed for 20.1% and underperformed for 8.6% of patients. Multivariate logistic regression analysis revealed that absence of retrograde amnesia (odds ratio [OR] 4.1, 95% confidence interval [CI] 1.8–9.7) was associated with noncompliance to the CCHR. Factors associated with underperformance were absence of motor vehicle crashes as a mechanism of injury (OR 6.6, 95% CI 1.2–36.3) and absence of headache (OR 10.8, 95% CI 1.3–87.4). CONCLUSION Compliance with the CCHR for adult patients with minor head injury remains low in the ED. A qualitative review of physicians’ practices and patients’ preferences may be carried out to evaluate reasons for noncompliance. PMID:28540393

Sensitivity to cutaneous warm stimuli varies greatly in the human head.

PubMed

Kim, Yung-Bin; Jung, Dahee; Park, Joonhee; Lee, Joo-Young

2017-10-01

The head has been known as the most sensitive area to temperature changes but the values are limited to the face. The purpose of this study was to examine cutaneous warm thresholds on the scalp and face of young males. Eight males participated in this study (24 ± 3 yrs in age, 178.2 ± 5.3cm in height, and 90.0 ± 15.4kg in body mass). All measurements were conducted in an environmental chamber (27 ± 1°C air temperature and 53 ± 1% relative humidity). Cutaneous warm thresholds were measured on nine areas of the following regions: the frontal (two points on the right), parietal (a point on the right and the vertex, respectively), temporal (two points on the right), and occipital region (on the right) along with the forehead using a thermal stimulator (rate of temperature increase 0.1°Cs -1 ). Skin temperatures on the nine head regions were monitored during the threshold test. The results showed that 1) no significant differences were found in initial skin temperatures among the nine head regions; 2) cutaneous warm detecting temperatures were significantly greater on the vertex (38.2 ± 3.5°C) than on the forehead (34.8 ± 1.4°C) and the other seven scalp regions (P < 0.05); 3) subjects detected the increase of 1.2 ± 1.0°C on the forehead and 1.5 ± 1.2°C on the occipital region as the first warmth while the vertex was the most insensitive to the increase of temperature (4.0 ± 3.2°C) (P < 0.05). In summary, the scalp region of young males was less sensitive to the temperature change when compared to the forehead, and the vertex was the most insensitive among the eight scalp regions to the temperature increase. We conclude that the entire head should be considered as a binary topography with the face and the scalp in terms of cutaneous thermal sensitivity. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Density of the North Polar Layered Deposit from Gravity and Topography

NASA Astrophysics Data System (ADS)

Ojha, L.; Lewis, K. W.

2017-12-01

The North Polar Layered Deposit (NPLD) of Mars is a vast reservoir of water ice with a volume of 1.14 million km3. Radar data indicates that the ice in the NPLD is extremely pure with dust content between 5 % to 10 %, however the radar data has not been able to put a direct constraint on the density of the NPLD. Here, we localize the gravity and topography signature of the NPLD and place a direct constraint on its density. We performed a grid search by generating admittance spectrum at each latitude and longitude between 75° N to 90° N and 0° E to 360° E, using a spherical cap of angular radius () of 7°, and a harmonic-bandwidth of the localization window Lwin of 37°. A region between Gemina Lingula and Planum Boreum was found to possesss an adequate correlation between gravity and topography. The estimated admittance spectra were compared with synthetic admittance spectra to constrain the load-density and the elastic thickness of the lithosphere. We constructed forward models by assuming that the lithosphere is a thin shell that deforms elastically in response to surface loads. We find that the bulk density of the NPLD ranges between 1000 to 1100 kg.m-3. Assuming a grain density of 3000 kg.m-3 for dust, the NPLD region within our localized window can contain dust content between 3 - 8 %, which is in an excellent agreement with the radar data.

Reconciling Long-Wavelength Dynamic Topography, Geoid Anomalies and Mass Distribution on Earth

NASA Astrophysics Data System (ADS)

Hoggard, M.; Richards, F. D.; Ghelichkhan, S.; Austermann, J.; White, N.

2017-12-01

Since the first satellite observations in the late 1950s, we have known that that the Earth's non-hydrostatic geoid is dominated by spherical harmonic degree 2 (wavelengths of 16,000 km). Peak amplitudes are approximately ± 100 m, with highs centred on the Pacific Ocean and Africa, encircled by lows in the vicinity of the Pacific Ring of Fire and at the poles. Initial seismic tomography models revealed that the shear-wave velocity, and therefore presumably the density structure, of the lower mantle is also dominated by degree 2. Anti-correlation of slow, probably low density regions beneath geoid highs indicates that the mantle is affected by large-scale flow. Thus, buoyant features are rising and exert viscous normal stresses that act to deflect the surface and core-mantle boundary (CMB). Pioneering studies in the 1980s showed that a viscosity jump between the upper and lower mantle is required to reconcile these geoid and tomographically inferred density anomalies. These studies also predict 1-2 km of dynamic topography at the surface, dominated by degree 2. In contrast to this prediction, a global observational database of oceanic residual depth measurements indicates that degree 2 dynamic topography has peak amplitudes of only 500 m. Here, we attempt to reconcile observations of dynamic topography, geoid, gravity anomalies and CMB topography using instantaneous flow kernels. We exploit a density structure constructed from blended seismic tomography models, combining deep mantle imaging with higher resolution upper mantle features. Radial viscosity structure is discretised, and we invert for the best-fitting viscosity profile using a conjugate gradient search algorithm, subject to damping. Our results suggest that, due to strong sensitivity to radial viscosity structure, the Earth's geoid seems to be compatible with only ± 500 m of degree 2 dynamic topography.

Glacial Inception in north-east Canada: The Role of Topography and Clouds

NASA Astrophysics Data System (ADS)

Birch, Leah; Tziperman, Eli; Cronin, Timothy

2016-04-01

Over the past 0.8 million years, ice ages have dominated Earth's climate on a 100 thousand year cycle. Interglacials were brief, sometimes lasting only a few thousand years, leading to the next inception. Currently, state-of-the-art global climate models (GCMs) are incapable of simulating the transition of Earth's climate from interglacial to glaciated. We hypothesize that this failure may be related to their coarse spatial resolution, which does not allow resolving the topography of inception areas, and their parameterized representation of clouds and atmospheric convection. To better understand the small scale topographic and cloud processes mis-represented by GCMs, we run the Weather Research and Forecasting model (WRF), which is a regional, cloud-resolving atmospheric model capable of a realistic simulation of the regional mountain climate and therefore of surface ice and snow mass balance. We focus our study on the mountain glaciers of Canada's Baffin Island, where geologic evidence indicates the last inception occurred at 115kya. We examine the sensitivity of mountain glaciers to Milankovitch Forcing, topography, and meteorology, while observing impacts of a cloud resolving model. We first verify WRF's ability to simulate present day climate in the region surrounding the Penny Ice Cap, and then investigate how a GCM-like biased representation of topography affects sensitivity of this mountain glacier to Milankovitch forcing. Our results show the possibility of ice cap growth on an initially snow-free landscape with realistic topography and insolation values from the last glacial inception. Whereas, smoothed topography as seen in GCMs has a negative surface mass balance, even with the relevant orbital parameter configuration. We also explore the surface mass balance feedbacks from an initially ice-covered Baffin Island and discuss the role of clouds and convection.

Development, validation and application of a device to measure e-cigarette users’ puffing topography

PubMed Central

Cunningham, Anthony; Slayford, Sandra; Vas, Carl; Gee, Jodie; Costigan, Sandra; Prasad, Krishna

2016-01-01

With the rapidly rising popularity and substantial evolution of electronic cigarettes (e-cigarettes) in the past 5–6 years, how these devices are used by vapers and consumers’ exposure to aerosol emissions need to be understood. We used puffing topography to measure directly product use. We adapted a cigarette puffing topography device for use with e-cigarettes. We performed validation using air and e-cigarette aerosol under multiple regimes. Consumer puffing topography was measured for 60 vapers provided with rechargeable “cig-a-like” or larger button-activated e-cigarettes, to use ad-libitum in two sessions. Under all regimes, air puff volumes were within 1 mL of the target and aerosol volumes within 5 mL for all device types, serving to validate the device. Vapers’ mean puff durations (2.0 s and 2.2 s) were similar with both types of e-cigarette, but mean puff volumes (52.2 mL and 83.0 mL) and mean inter-puff intervals (23.2 s and 29.3 s) differed significantly. The differing data show that product characteristics influence puffing topography and, therefore, the results obtained from a given e-cigarette might not read across to other products. Understanding the factors that affect puffing topography will be important for standardising testing protocols for e-cigarette emissions. PMID:27721496

Development, validation and application of a device to measure e-cigarette users' puffing topography.

PubMed

Cunningham, Anthony; Slayford, Sandra; Vas, Carl; Gee, Jodie; Costigan, Sandra; Prasad, Krishna

2016-10-10

With the rapidly rising popularity and substantial evolution of electronic cigarettes (e-cigarettes) in the past 5-6 years, how these devices are used by vapers and consumers' exposure to aerosol emissions need to be understood. We used puffing topography to measure directly product use. We adapted a cigarette puffing topography device for use with e-cigarettes. We performed validation using air and e-cigarette aerosol under multiple regimes. Consumer puffing topography was measured for 60 vapers provided with rechargeable "cig-a-like" or larger button-activated e-cigarettes, to use ad-libitum in two sessions. Under all regimes, air puff volumes were within 1 mL of the target and aerosol volumes within 5 mL for all device types, serving to validate the device. Vapers' mean puff durations (2.0 s and 2.2 s) were similar with both types of e-cigarette, but mean puff volumes (52.2 mL and 83.0 mL) and mean inter-puff intervals (23.2 s and 29.3 s) differed significantly. The differing data show that product characteristics influence puffing topography and, therefore, the results obtained from a given e-cigarette might not read across to other products. Understanding the factors that affect puffing topography will be important for standardising testing protocols for e-cigarette emissions.

Moire Topography For The Detection Of Orthopaedic Defects

NASA Astrophysics Data System (ADS)

Kamal, Syed A.; Lindseth, Richard E.

1981-02-01

Moire topography is applied for the follow-up of scoliosis patients. The results are then compared with the X-rays. A special lamp and scale arrangement is utilized for patient alignment. It is suggested that this technique will be used for the detection of all orthopaedic defects.

Possible Juventae Chasma subice volcanic eruptions and Maja Valles ice outburst floods on Mars: Implications of Mars Global surveyor crater densities, geomorphology, and topography

USGS Publications Warehouse

Chapman, M.G.; Gudmundsson, M.T.; Russell, A.J.; Hare, T.M.

2003-01-01

This article discusses image, topographic, and spectral data from the Mars Global Surveyor (MGS) mission that provide new information concerning the surface age, geomorphology, and topography of the Juventae Chasma/Maja Valles system. Our study utilizes data from two instruments on board MGS: images from the Mars Orbiter Camera (MOC) and topography from the Mars Orbiter Laser Altimeter (MOLA). Within Maja Valles we can now observe depositional bars with megaripples that unequivocally show catastrophic floods occurred in the channel. Viking impact crater densities indicated the chasma and channel floor areas were all one age (late Hesperian to Amazonian); however, MOC data indicate a marked difference in densities of small craters between Juventae Chasma, Maja Valles, and the channel debouchment area in Chryse Planitia basin. Although other processes may contribute to crater variability, young resurfacing events in the chasma and episodes of recent erosion at Maja Valles channel head may possibly account for the disparate crater densities along the chasma/channel system. Relatively young volcanic eruptions may have contributed to resurfacing; as in Juventae Chasma, a small possible volcanic cone of young dark material is observed. MOC data also indicate previously unknown interior layered deposit mounds in the chasma that indicate at least two periods of mound formation. Finally, MOLA topography shows that the entire floor of the chasma lies at the same elevation as the channel debouchment area in Chryse basin, resulting in a 3-km-high barrier to water flow out of the chasma. Blocked ponded water would rapidly freeze in the current (and likely past) climate of Mars. For catastrophic flow to occur in Maja Valles, some process is required to melt ice and induce floods out of the chasma. We suggest subice volcanic eruption and calculate estimates of water discharges and volumes that these eruptions might have produced.

Simultaneous generation and scattering of internal tides by ocean floor topography

NASA Astrophysics Data System (ADS)

Mathur, Manikandan

2015-11-01

Internal waves play a significant role in the global energy budget of the ocean, with internal tides potentially contributing to the conversion of a large amount of mechanical energy into heat in the deep ocean. Several studies in the past decade have investigated internal tide generation and internal tide scattering by ocean floor topography, but by treating them as two separate, independent processes. In this talk, we use the recently developed Green function model (Mathur et al., J. Geophys. Res. Oceans, 119, 2165-2182, 2014), sans the WKB approximation, to quantify the extent to which internal tide generation (scattering) that results from barotropic (baroclinic) forcing on small- and large-scale topography in uniform and nonuniform stratifications is modified by the presence of a background baroclinic (barotropic) tide. Results on idealized topography, stratification and forcing will first be presented, followed by a discussion on the relevance of our studies in the real ocean scenario. The author thanks the Ministry of Earth Sciences, Government of India for financial support under the Monsoon Mission Grant MM/2014/IND-002.

Reconstruction of Laser-Induced Surface Topography from Electron Backscatter Diffraction Patterns.

PubMed

Callahan, Patrick G; Echlin, McLean P; Pollock, Tresa M; De Graef, Marc

2017-08-01

We demonstrate that the surface topography of a sample can be reconstructed from electron backscatter diffraction (EBSD) patterns collected with a commercial EBSD system. This technique combines the location of the maximum background intensity with a correction from Monte Carlo simulations to determine the local surface normals at each point in an EBSD scan. A surface height map is then reconstructed from the local surface normals. In this study, a Ni sample was machined with a femtosecond laser, which causes the formation of a laser-induced periodic surface structure (LIPSS). The topography of the LIPSS was analyzed using atomic force microscopy (AFM) and reconstructions from EBSD patterns collected at 5 and 20 kV. The LIPSS consisted of a combination of low frequency waviness due to curtaining and high frequency ridges. The morphology of the reconstructed low frequency waviness and high frequency ridges matched the AFM data. The reconstruction technique does not require any modification to existing EBSD systems and so can be particularly useful for measuring topography and its evolution during in situ experiments.

Irregular topography at the Earth's inner core boundary.

PubMed

Dai, Zhiyang; Wang, Wei; Wen, Lianxing

2012-05-15

Compressional seismic wave reflected off the Earth's inner core boundary (ICB) from earthquakes occurring in the Banda Sea and recorded at the Hi-net stations in Japan exhibits significant variations in travel time (from -2 to 2.5 s) and amplitude (with a factor of more than 4) across the seismic array. Such variations indicate that Earth's ICB is irregular, with a combination of at least two scales of topography: a height variation of 14 km changing within a lateral distance of no more than 6 km, and a height variation of 4-8 km with a lateral length scale of 2-4 km. The characteristics of the ICB topography indicate that small-scale variations of temperature and/or core composition exist near the ICB, and/or the ICB topographic surface is being deformed by small-scale forces out of its thermocompositional equilibrium position and is metastable.

Resolving Discrepancies Between Observed and Predicted Dynamic Topography on Earth

NASA Astrophysics Data System (ADS)

Richards, F. D.; Hoggard, M.; White, N. J.

2017-12-01

Compilations of well-resolved oceanic residual depth measurements suggest that present-day dynamic topography differs from that predicted by geodynamic simulations in two significant respects. At short wavelengths (λ ≤ 5,000 km), much larger amplitude variations are observed, whereas at long wavelengths (λ > 5,000 km), observed dynamic topography is substantially smaller. Explaining the cause of this discrepancy with a view to reconciling these different approaches is central to constraining the structure and dynamics of the deep Earth. Here, we first convert shear wave velocity to temperature using an experimentally-derived anelasticity model. This relationship is calibrated using a pressure and temperature-dependent plate model that satisfies age-depth subsidence, heat flow measurements, and seismological constraints on the depth to the lithosphere-asthenosphere boundary. In this way, we show that, at short-wavelengths, observed dynamic topography is consistent with ±150 ºC asthenospheric temperature anomalies. These inferred thermal buoyancy variations are independently verified by temperature measurements derived from geochemical analyses of mid-ocean ridge basalts. Viscosity profiles derived from the anelasticity model suggest that the asthenosphere has an average viscosity that is two orders of magnitude lower than that of the underlying upper mantle. The base of this low-viscosity layer coincides with a peak in azimuthal anisotropy observed in recent seismic experiments. This agreement implies that lateral asthenospheric flow is rapid with respect to the underlying upper mantle. We conclude that improved density and viscosity models of the uppermost mantle, which combine a more comprehensive physical description of the lithosphere-asthenosphere system with recent seismic tomographic models, can help to resolve spectral discrepancies between observed and predicted dynamic topography. Finally, we explore possible solutions to the long

A systematic analysis of directional site effects at stations of the Italian Seismic Network to test the role of local topography

NASA Astrophysics Data System (ADS)

Pischiutta, Marta; Cianfarra, Paola; Salvini, Francesco; Cara, Fabrizio; Vannoli, Paola

2018-03-01

Directional site effects observed at seismological stations on pronounced relief are analyzed. We investigate the ground motion properties calculating horizontal-to-vertical spectral ratios and horizontal polarization of both ambient vibrations and earthquake records using broadband seismograms of the Italian Seismic Network. We find that a subset of 47 stations with pronounced relief, results in a significant (>2) directional amplification of the horizontal component, with a well defined, site-specific direction of motion. However, the horizontal spectral response of sites is not uniform, varying from an isolated (resonant) frequency peak to a broadband amplification, interesting frequency bands as large as 1-10 Hz in many cases. Using the 47 selected stations, we have tried to establish a relation between directional amplification and topography geometry in a 2D-vision, when applicable, through a morphological analysis of the Digital Elevation Model using Geographic Information Systems. The procedure computes the parameters that characterize the geometry of topographic irregularities (size and slope), in combination with a principal component analysis that automatically yields the orientation of the elongated ridges. In seeking a relation between directional amplification and the surface morphology, we have found that it is impossible to fit the variety of observations with a resonant topography model as well as to identify common features in the ground motion behavior for stations with similar topography typologies. We conclude that, rather than the shape of the topography, local structural complexities and details of the near-surface structure must play a predominant role in controlling ground motion properties at sites with pronounced relief.

A systematic analysis of directional site effects at stations of the Italian seismic network to test the role of local topography

NASA Astrophysics Data System (ADS)

Pischiutta, Marta; Cianfarra, Paola; Salvini, Francesco; Cara, Fabrizio; Vannoli, Paola

2018-07-01

Directional site effects observed at seismological stations on pronounced relief are analysed. We investigate the ground motion properties calculating horizontal-to-vertical spectral ratios and horizontal polarization of both ambient vibrations and earthquake records using broad-band seismograms of the Italian seismic network. We find that a subset of 47 stations with pronounced relief results in a significant (>2) directional amplification of the horizontal component, with a well-defined, site-specific direction of motion. However, the horizontal spectral response of sites is not uniform, varying from an isolated (resonant) frequency peak to a broad-band amplification, interesting frequency bands as large as 1-10 Hz in many cases. Using 47 selected stations, we have tried to establish a relation between directional amplification and topography geometry in a 2-D vision, when applicable, through a morphological analysis of the digital elevation model using geographic information systems. The procedure computes the parameters that characterize the geometry of topographic irregularities (size and slope), in combination with a principal component analysis that automatically yields the orientation of the elongated ridges. In seeking a relation between directional amplification and the surface morphology, we have found that it is impossible to fit the variety of observations with a resonant topography model as well as to identify common features in the ground motion behaviour for stations with similar topography typologies. We conclude that, rather than the shape of the topography, local structural complexities and details of the near-surface structure must play a predominant role in controlling ground motion properties at sites with pronounced relief.

Time-dependent effects of heat advection and topography on cooling histories during erosion

NASA Astrophysics Data System (ADS)

Mancktelow, Neil S.; Grasemann, Bernhard

1997-03-01

Both erosion and surface topography cause a time-dependent variation in isotherm geometry that can result in significant errors in estimating natural exhumation rates from geochronologic data. Analytical solutions and two-dimensional numerical modelling are used to investigate the magnitude of these inaccuracies for conditions appropriate to many rapidly exhumed mountain chains of rugged relief. It is readily demonstrated that uplift of the topographic surface has a negligible effect on the cooling history of an exhumed rock sample and cannot be quantified by current geochronologic methods. The topography itself perturbs the isotherms to a depth that depends on both the vertical and horizontal scale of the surface relief. Estimations employing different isotopic systems in the same sample with higher closure temperatures (> 200°C) are not generally influenced by topography. However, direct conversion of cooling rates to exhumation rates assuming a simple constant linear geotherm markedly underestimates peak rates, due to variation of the geothermal gradient in time and space and to the time lag between exhumation and cooling. Estimations based on the altitude variation in apatite fission-track ages are less prone to such inaccuracies in geothermal gradient but are affected by near-surface time-dependent variation in isotherm depth due to advection and topography. In tectonically active mountain belts, high exhumation rates are coupled with rugged topography, and exhumation rates may be markedly overestimated, by factors of 2 or more. Even at lower exhumation rates on the order of 1 mm/a, the shape of the cooling curve is modified by advection and topography. A convex-concave shape to the cooling curve does not necessarily imply a change of exhumation rate; it may also be attained by a more complicated geothermal gradient induced by topographic relief. Very fast cooling below 100°C, often interpreted as reflecting faster exhumation, can be more simply explained by

A critical assessment of viscous models of trench topography and corner flow

NASA Technical Reports Server (NTRS)

Zhang, J.; Hager, B. H.; Raefsky, A.

1984-01-01

Stresses for Newtonian viscous flow in a simple geometry (e.g., corner flow, bending flow) are obtained in order to study the effect of imposed velocity boundary conditions. Stress for a delta function velocity boundary condition decays as 1/R(2); for a step function velocity, stress goes as 1/R; for a discontinuity in curvature, the stress singularity is logarithmic. For corner flow, which has a discontinuity of velocity at a certain point, the corresponding stress has a 1/R singularity. However, for a more realistic circular-slab model, the stress singularity becomes logarithmic. Thus the stress distribution is very sensitive to the boundary conditions, and in evaluating the applicability of viscous models of trench topography it is essential to use realistic geometries. Topography and seismicity data from northern Hoshu, Japan, were used to construct a finite element model, with flow assumed tangent to the top of the grid, for both Newtonian and non-Newtonian flow (power law 3 rheology). Normal stresses at the top of the grid are compared to the observed trench topography and gravity anomalies. There is poor agreement. Purely viscous models of subducting slables with specified velocity boundary conditions do not predict normal stress patterns compatible with observed topography and gravity. Elasticity and plasticity appear to be important for the subduction process.

Localized Gravity/Topography Correlation and Admittance Spectra one the Moon

NASA Astrophysics Data System (ADS)

Ishihara, Y.; Namiki, N.; Sugita, S.; Matsumoto, K.; Goossens, S.; Araki, H.; Noda, H.; Sasaki, S.; Iwata, T.; Hanada, H.

2009-04-01

Lunar surface and structure can be separate into two parts. The lunar near side crust and far side crust differ remarkably in thickness. This difference probably caused by difference of thermal evolution and state (elastic thickness) and catering history on both side. The correlations and admittance between the topography and gravity anomalies provide important information on the level of isostatic compensation of the lithosphere at the geological timescale, and reflect its thermo-mechanical state. Therefore, localized correlation and admittance analysis is one of the most important studies of selenodesy. A global correlation between topography and gravity of the Moon obtained by Clementine and Lunar Prospector missions, respectively, reveals high value at long wavelength and low value at short wavelength. Such characteristics are distinguished from those of the Earth and other terrestrial planets, whose global correlation between topography and gravity is low at long wavelength. The distinct correlation between topography and gravity of the Moon may indicate that the lunar topography is supported by multiple compensation mechanism. Further, an incomplete coverage of Doppler tracking data prior to Kaguya (SELENE) gravity experiment probably contributed to the correlation. Because the Moon is synchronously rotating with its revolution around the Earth, a spacecraft orbiting over the far side is not visible from ground stations. In either case, it is significant to decompose local correlation from global ones in order to investigate internal structure of the Moon from spherical harmonic model of gravity (LP75G [1]) and topography (GLTM-2 [2]). Japanese lunar exploration Kaguya (SELENE) has two kinds of selenodesical experiments. One is RSAT/VRAD (gravity mapping with direct tracking over far-side) experiment and another is Laser ALTimeter (LALT; topography mapping) experiment. These two experiments enable us to conduct localized analysis for the Moon. Therefore we

23. SPILLWAY NO. 1 LOWER END TOPOGRAPHY AND SECTIONS. ...

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

23. SPILLWAY NO. 1 - LOWER END TOPOGRAPHY AND SECTIONS. February 1934. Reference BS-150. - Cushman No. 1 Hydroelectric Power Plant, Spillway, North Fork of Skokomish River, 5 miles West of Hood Canal, Hoodsport, Mason County, WA

Calibration of z-axis linearity for arbitrary optical topography measuring instruments

NASA Astrophysics Data System (ADS)

Eifler, Matthias; Seewig, Jörg; Hering, Julian; von Freymann, Georg

2015-05-01

The calibration of the height axis of optical topography measurement instruments is essential for reliable topography measurements. A state of the art technology for the calibration of the linearity and amplification of the z-axis is the use of step height artefacts. However, a proper calibration requires numerous step heights at different positions within the measurement range. The procedure is extensive and uses artificial surface structures that are not related to real measurement tasks. Concerning these limitations, approaches should to be developed that work for arbitrary topography measurement devices and require little effort. Hence, we propose calibration artefacts which are based on the 3D-Abbott-Curve and image desired surface characteristics. Further, real geometric structures are used as an initial point of the calibration artefact. Based on these considerations, an algorithm is introduced which transforms an arbitrary measured surface into a measurement artefact for the z-axis linearity. The method works both for profiles and topographies. For considering effects of manufacturing, measuring, and evaluation an iterative approach is chosen. The mathematical impact of these processes can be calculated with morphological signal processing. The artefact is manufactured with 3D laser lithography and characterized with different optical measurement devices. An introduced calibration routine can calibrate the entire z-axis-range within one measurement and minimizes the required effort. With the results it is possible to locate potential linearity deviations and to adjust the z-axis. Results of different optical measurement principles are compared in order to evaluate the capabilities of the new artefact.

Topography and refractometry of nanostructures using spatial light interference microscopy.

PubMed

Wang, Zhuo; Chun, Ik Su; Li, Xiuling; Ong, Zhun-Yong; Pop, Eric; Millet, Larry; Gillette, Martha; Popescu, Gabriel

2010-01-15

Spatial light interference microscopy (SLIM) is a novel method developed in our laboratory that provides quantitative phase images of transparent structures with a 0.3 nm spatial and 0.03 nm temporal accuracy owing to the white light illumination and its common path interferometric geometry. We exploit these features and demonstrate SLIM's ability to perform topography at a single atomic layer in graphene. Further, using a decoupling procedure that we developed for cylindrical structures, we extract the axially averaged refractive index of semiconductor nanotubes and a neurite of a live hippocampal neuron in culture. We believe that this study will set the basis for novel high-throughput topography and refractometry of man-made and biological nanostructures.

Geomorphic Transport Laws and the Statistics of Topography and Stratigraphy

NASA Astrophysics Data System (ADS)

Schumer, R.; Taloni, A.; Furbish, D. J.

2016-12-01

Geomorphic transport laws take the form of partial differential equations in which sediment motion is a deterministic function of slope. The addition of a noise term, representing unmeasurable, or subgrid scale autogenic forcing, reproduces scaling properties similar to those observed in topography, landforms, and stratigraphy. Here we describe a transport law that generalizes previous equations by permitting transport that is local or non-local in addition to different types of noise. More importantly, we use this transport law to link the character of sediment transport to the statistics of topography and stratigraphy. In particular, we link the origin of the Sadler effect to the evolution of the earth surface via a transport law.

Significance of Thermal Fluvial Incision and Bedrock Transfer due to Ice Advection on Greenland Ice Sheet Topography

NASA Astrophysics Data System (ADS)

Crozier, J. A.; Karlstrom, L.; Yang, K.

2017-12-01

Ice sheet surface topography reflects a complicated combination of processes that act directly upon the surface and that are products of ice advection. Using recently-available high resolution ice velocity, imagery, ice surface elevation, and bedrock elevation data sets, we seek to determine the domain of significance of two important processes - thermal fluvial incision and transfer of bedrock topography through the ice sheet - on controlling surface topography in the ablation zone. Evaluating such controls is important for understanding how melting of the GIS surface during the melt season may be directly imprinted in topography through supraglacial drainage networks, and indirectly imprinted through its contribution to basal sliding that affects bedrock transfer. We use methods developed by (Karlstrom and Yang, 2016) to identify supraglacial stream networks on the GIS, and use high resolution surface digital elevation models as well as gridded ice velocity and melt rate models to quantify surface processes. We implement a numerically efficient Fourier domain bedrock transfer function (Gudmundsson, 2003) to predict surface topography due to ice advection over bedrock topography obtained from radar. Despite a number of simplifying assumptions, the bedrock transfer function predicts the observed ice sheet surface in most regions of the GIS with ˜90% accuracy, regardless of the presence or absence of supraglacial drainage networks. This supports the hypothesis that bedrock is the most significant driver of ice surface topography on wavelengths similar to ice thickness. Ice surface topographic asymmetry on the GIS is common, with slopes in the direction of ice flow steeper than those faced opposite to ice flow, consistent with bedrock transfer theory. At smaller wavelengths, topography consistent with fluvial erosion by surface hydrologic features is evident. We quantify the effect of ice advection versus fluvial thermal erosion on supraglacial longitudinal stream