Application of the inner solar system cratering record to the Earth

NASA Technical Reports Server (NTRS)

Barlow, Nadine G.

1990-01-01

The cratering records on the Moon, Mercury, and Mars are studied to provide constraints on: (1) terrestrial conditions prior to about 3.8 Ga, (2) why biology was not extensively established prior to 3.5 Ga, (3) whether impact-induced volcanism can explain some feature of the Cretaceous/Tertiary boundary event, and (4) how common large single-impact events are in the inner solar system. Earth underwent a period of high impact rates and large basin-forming events early in its history, based on the cratering record retained in the Lunar, Mercurian, and Martian highlands. The widespread occurrence of life around 3.5 Ga is linked to the cessation of high impact rates. Impact of a 10-km-diam object into terrestrial oceans could excavate through crustal material and into mantle reservoirs, creating extended basaltic volcanic activity. Scaling laws, coupled with the record retained on Lunar and Martian plains, indicate that between one and seven craters of 90 km diam or greater could have formed on Earth in the past 65 million years.

Population trends of the redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae): does utilization of small diameter redbay trees allow populations to persist?

Treesearch

M. Lake Maner; James Hanula; Scott Horn

2014-01-01

The redbay ambrosia beetle, Xyleborus glabratus Eichhoff, vectors laurel wilt, Raffaelea lauricola T.C. Harr., Fraedrich & Aghayeva, that quickly kills all large diam (> 2.5cm) redbay trees [Persea borbonia (L.) Sprengel] in an area but smaller diam trees (

Non-Stationarity and Power Spectral Shifts in EMG Activity Reflect Motor Unit Recruitment in Rat Diaphragm Muscle

PubMed Central

Seven, Yasin B.; Mantilla, Carlos B.; Zhan, Wen-Zhi; Sieck, Gary C.

2012-01-01

We hypothesized that diaphragm muscle (DIAm) by a shift in the EMG power spectral density (PSD) to higher frequencies reflects recruitment of more fatigable fast-twitch motor units and motor unit recruitment is reflected by EMG non-stationarity. DIAm EMG was recorded in anesthetized rats during eupnea, hypoxia-hypercapnia (10% O2-5% CO2), airway occlusion, and sneezing (maximal DIAm force). Although power in all frequency bands increased progressively across motor behaviors, PSD centroid frequency increased only during sneezing (p<0.05). The non-stationary period at the onset of EMG activity ranged from ~70 ms during airway occlusion to ~150 ms during eupnea. Within the initial non-stationary period of EMG activity 80–95% of motor units were recruited during different motor behaviors. Motor units augmented their discharge frequencies progressively beyond the non-stationary period; yet, EMG signal became stationary. In conclusion, non-stationarity of DIAm EMG reflects the period of motor unit recruitment, while a shift in the PSD towards higher frequencies reflects recruitment of more fatigable fast-twitch motor units. PMID:22986086

Pupillography as a sensitive, noninvasive biomarker in healthy volunteers: first-in-man study of BAY 63-9044, a new 5-HT1A-receptor agonist with dopamine agonistic properties.

PubMed

Wensing, Georg; Haase, Claus; Brendel, Erich; Böttcher, Michael Friedrich

2007-12-01

BAY 63-9044 is a new full 5-HT(1A)-agonist with functional dopamine agonist properties aimed for the treatment of Parkinson's disease. This first-in-man study investigated the pharmacodynamics, safety and tolerability as well as the pharmacokinetics of BAY 63-9044 in a randomized, single-blind, placebo-controlled group-comparison dose escalation study. 45 healthy men received BAY 63-9044 as an oral solution in single doses of 0.25 mg, 0.5 mg, 1.2 mg, 2.5 mg and 5.0 mg. Pupil reaction (baseline pupil diameter (DIAM), constriction amplitude (CA)), body temperature, electroencephalography (EEG) and prolactin, cortisol and adrenocorticotrophic hormone (ACTH) served as pharmacodynamic measures and were monitored up to 24 h after drug intake. Safety, tolerability and plasma samples for determination of BAY 63-9044 were followed up to 72 h. Up to a dose of 2.5 mg, BAY 63-9044 was safe and well tolerated. Dose-limiting adverse events (nausea, vomiting, and dizziness) occurred in 5 out of 6 volunteers at the 5 mg dose. Adverse events resolved spontaneously in all but one volunteers who was treated with an antihistaminergic for vomiting. Dose-dependent changes of DIAM and CA were observed at doses higher than 0.5 mg and 1.2 mg, respectively. Body temperature showed a trend for reduction starting at C(max) in the highest two doses only. No clear effect was found on prolactin, cortisol and ACTH levels. The pharmacokinetics of BAY 63-9044 showed a dose-dependent increase with maximum plasma concentrations reached within 1 h. Plasma concentrations declined in a bi-phased manner with an apparent terminal half-life of 5.2-8.1 h. Up to the maximum tolerated dose (MTD) of 2.5 mg BAY 63-9044 was safe and well tolerated and showed predictable linear pharmacokinetics. Pupil reaction may serve as a non-invasive biomarker for pharmacodynamic effects of 5-HT(1A)-compounds with DIAM being the most sensitive parameter.

Software for Sharing and Management of Information

NASA Technical Reports Server (NTRS)

Chen, James R.; Wolfe, Shawn R.; Wragg, Stephen D.

2003-01-01

DIAMS is a set of computer programs that implements a system of collaborative agents that serve multiple, geographically distributed users communicating via the Internet. DIAMS provides a user interface as a Java applet that runs on each user s computer and that works within the context of the user s Internet-browser software. DIAMS helps all its users to manage, gain access to, share, and exchange information in databases that they maintain on their computers. One of the DIAMS agents is a personal agent that helps its owner find information most relevant to current needs. It provides software tools and utilities for users to manage their information repositories with dynamic organization and virtual views. Capabilities for generating flexible hierarchical displays are integrated with capabilities for indexed- query searching to support effective access to information. Automatic indexing methods are employed to support users queries and communication between agents. The catalog of a repository is kept in object-oriented storage to facilitate sharing of information. Collaboration between users is aided by matchmaker agents and by automated exchange of information. The matchmaker agents are designed to establish connections between users who have similar interests and expertise.

Non-stationarity and power spectral shifts in EMG activity reflect motor unit recruitment in rat diaphragm muscle.

PubMed

Seven, Yasin B; Mantilla, Carlos B; Zhan, Wen-Zhi; Sieck, Gary C

2013-01-15

We hypothesized that a shift in diaphragm muscle (DIAm) EMG power spectral density (PSD) to higher frequencies reflects recruitment of more fatigable fast-twitch motor units and motor unit recruitment is reflected by EMG non-stationarity. DIAm EMG was recorded in anesthetized rats during eupnea, hypoxia-hypercapnia (10% O(2)-5% CO(2)), airway occlusion, and sneezing (maximal DIAm force). Although power in all frequency bands increased progressively across motor behaviors, PSD centroid frequency increased only during sneezing (p<0.05). The non-stationary period at the onset of EMG activity ranged from ∼80 ms during airway occlusion to ∼150 ms during eupnea. Within the initial non-stationary period of EMG activity 80-95% of motor units were recruited during different motor behaviors. Motor units augmented their discharge frequencies progressively beyond the non-stationary period; yet, EMG signal became stationary. In conclusion, non-stationarity of DIAm EMG reflects the period of motor unit recruitment, while a shift in the PSD towards higher frequencies reflects recruitment of more fatigable fast-twitch motor units. Copyright © 2012 Elsevier B.V. All rights reserved.

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

Bradonjic, Milan; Elsasser, Robert; Friedrich, Tobias

In this work, we consider the random broadcast time on random geometric graphs (RGGs). The classic random broadcast model, also known as push algorithm, is defined as: starting with one informed node, in each succeeding round every informed node chooses one of its neighbors uniformly at random and informs it. We consider the random broadcast time on RGGs, when with high probability: (i) RGG is connected, (ii) when there exists the giant component in RGG. We show that the random broadcast time is bounded by {Omicron}({radical} n + diam(component)), where diam(component) is a diameter of the entire graph, or themore » giant component, for the regimes (i), or (ii), respectively. In other words, for both regimes, we derive the broadcast time to be {Theta}(diam(G)), which is asymptotically optimal.« less

Analysis and sizing of Mars aerobrake structure

NASA Technical Reports Server (NTRS)

Raju, I. S.; Craft, W. J.

1993-01-01

A cone-sphere aeroshell structure for aerobraking into Martian atmosphere is studied. Using this structural configuration, a space frame load-bearing structure is proposed. To generate this structure efficiently and to perform a variety of studies of several configurations, a mesh generator that utilizes only a few configurational parameters is developed. A finite element analysis program that analyzes space frame structures was developed. A sizing algorithm that arrives at a minimum mass configuration was developed and integrated into the finite element analysis program. A typical 135-ft-diam aerobrake configuration was analyzed and sized. The minimum mass obtained in this study using high modulus graphite/epoxy composite material members is compared with the masses obtained from two other aerobrake structures using lightweight erectable tetrahedral truss and part-spherical truss configurations. Excellent agreement for the minimum mass was obtained with the three different aerobrake structures. Also, the minimum mass using the present structure was obtained when the supports were not at the base but at about 75 percent of the base diameter.

Clinical outcome following DIAM implantation for symptomatic lumbar internal disk disruption: a 3-year retrospective analysis

PubMed Central

Lu, Kang; Liliang, Po-Chou; Wang, Hao-Kuang; Chen, Jui-Sheng; Chen, Te-Yuan; Huang, Ruyi; Chen, Han-Jung

2016-01-01

Background/objective Internal disk disruption (IDD), an early event of lumbar disk degeneration, is the most common cause of low back pain. Since increased intradiskal pressure (IDP) is associated with symptoms and progression of disk degeneration, unloading a painful disk with an interspinous process device (IPD) is a rational treatment option. The goal of this study was to evaluate the effectiveness of dynamic stabilization with an IPD in the treatment of symptomatic IDD of the lumbar spine. Patients and methods Patients with symptomatic IDD were treated with implantation of an IPD, the device for intervertebral assisted motion (DIAM). Diagnosis of IDD was based on typical MRI finding of posterior annular high-intensity zone and positive provocative test on discography. IDP was analyzed intraoperatively. Axial back and leg pain was evaluated with visual analog scale, functional status with Oswestry Disability Index, and final clinical outcomes with Odom criteria. Data from 34 patients followed up for at least 3 years were collected. Results DIAM implantation significantly reduced IDP (n=11, P<0.0001). All 34 patients reported symptom relief. Thirty-one patients (91%) remained symptom free until the last followups. Three patients (9%) experienced recurrence of pain, of which the causes were unrelated to the IDD or surgery. Disk status at the DIAM-implanted segments remained stable. Segmental flexion/extension mobility was preserved in 27 of 30 patients with preoperative mobility. No proximal or distal adjacent segment degeneration was observed. The final clinical outcomes were excellent/good in 31 and fair/poor in three patients. Conclusion For patients with symptomatic IDD, dynamic stabilization with DIAM provides pain relief and functional improvement. The implantation maintains disk status and prevents progression of disk degeneration, without compromising segmental flexion/extension mobility or causing adjacent segment degeneration. PMID:27826214

Correlation of Respiratory Activity of Contralateral Diaphragm Muscles for Evaluation of Recovery Following Hemiparesis

PubMed Central

Dow, Douglas E.; Zhan, Wen-Zhi; Sieck, Gary C.; Mantilla, Carlos B.

2014-01-01

Respiration is impaired by disruption of the central drive for inspiration to the diaphragm muscle (DIAm). Some function may recover involving nerve regeneration, reinnervation or neuroplasticity. A research animal model involves inducing hemiparesis of the DIAm and monitoring any recovery under different conditions. Methods to accurately track the level of functional recovery are needed. In this study, an algorithm was developed and tested to quantify the relative amount of electromyogram (EMG) activity that temporally correlated for an experimental (EXP) hemi-DIAm with its intact contralateral hemi-DIAm. An average rectified value (ARV) trace was calculated. A template was formed of the ARV trace of the intact hemi-DIAm, with higher positive values corresponding with periods of inspirations and lower negative values corresponding with quiet periods. This template was multiplied by the EXP ARV trace to reward (more positive) periods of correlating activity, and punish (more negative) periods of high activity on the EXP side that corresponded with quiet periods on the intact side. The average integrated value was the index of correlating contralateral activity (ICCA). A negative ICCA value indicated no net correlation of activity, and a positive value indicated a net correlation of activity. The algorithm was tested on rats having the conditions of control or hemi-paresis induced by denervatation (DNV), tetrodotoxin administration (TTX) or cervical spinal hemi-section (SH). Control had high positive ICCA values, and DNV had negative values. TTX maintained negative ICCA values at 3, 7 and 14 days, indicating a lack of functional recovery. SH maintained negative values at 3 and 7 days, but a subset had positive values at 14 days indicating some functional recovery. PMID:19965125

A Distributed Multi-Agent System for Collaborative Information Management and Learning

NASA Technical Reports Server (NTRS)

Chen, James R.; Wolfe, Shawn R.; Wragg, Stephen D.; Koga, Dennis (Technical Monitor)

2000-01-01

In this paper, we present DIAMS, a system of distributed, collaborative agents to help users access, manage, share and exchange information. A DIAMS personal agent helps its owner find information most relevant to current needs. It provides tools and utilities for users to manage their information repositories with dynamic organization and virtual views. Flexible hierarchical display is integrated with indexed query search-to support effective information access. Automatic indexing methods are employed to support user queries and communication between agents. Contents of a repository are kept in object-oriented storage to facilitate information sharing. Collaboration between users is aided by easy sharing utilities as well as automated information exchange. Matchmaker agents are designed to establish connections between users with similar interests and expertise. DIAMS agents provide needed services for users to share and learn information from one another on the World Wide Web.

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

Rosch, R.; Boutin, J. Y.; Le Breton, J. P.

This article describes x-ray imaging with grazing-incidence microscopes, developed for the experimental program carried out on the Ligne d'Integration Laser (LIL) facility [J. P. Le Breton et al., Inertial Fusion Sciences and Applications 2001 (Elsevier, Paris, 2002), pp. 856-862] (24 kJ, UV--0.35 nm). The design includes a large target-to-microscope (400-700 mm) distance required by the x-ray ablation issues anticipated on the Laser MegaJoule facility [P. A. Holstein et al., Laser Part. Beams 17, 403 (1999)] (1.8 MJ) which is under construction. Two eight-image Kirkpatrick-Baez microscopes [P. Kirkpatrick and A. V. Baez J. Opt. Soc. Am. 38, 766 (1948)] with differentmore » spectral wavelength ranges and with a 400 mm source-to-mirror distance image the target on a custom-built framing camera (time resolution of {approx}80 ps). The soft x-ray version microscope is sensitive below 1 keV and its spatial resolution is better than 30 {mu}m over a 2-mm-diam region. The hard x-ray version microscope has a 10 {mu}m resolution over an 800-{mu}m-diam region and is sensitive in the 1-5 keV energy range. Two other x-ray microscopes based on an association of toroidal/spherical surfaces (T/S microscopes) produce an image on a streak camera with a spatial resolution better than 30 {mu}m over a 3 mm field of view in the direction of the camera slit. Both microscopes have been designed to have, respectively, a maximum sensitivity in the 0.1-1 and 1-5 keV energy range. We present the original design of these four microscopes and their test on a dc x-ray tube in the laboratory. The diagnostics were successfully used on LIL first experiments early in 2005. Results of soft x-ray imaging of a radiative jet during conical shaped laser interaction are shown.« less

The operation of a single-sided linear induction motor with squirrel-cage and solid-steel reaction rails

NASA Astrophysics Data System (ADS)

Eastham, A. R.; Katz, R. M.

1980-09-01

Two test programs have been conducted to evaluate the performance of a single-sided linear induction motor with a squirrel-cage reaction rail and with a solid steel reaction rail. A 1.73-m-long six-pole stator interacted with the rails mounted on the rim of a 7.6-m-diam wheel. A 64-channel data acquisition system allowed tests to be performed over a wide range of operating conditions at speeds up to 20 m/sec. Typical test results which compare and contrast the mechanical, electrical and magnetic behavior of the SLIMs are presented. The test data are being used to assess the SLIM as an integrated suspension/propulsion system and for other transportation applications.

Superplasticity - A Fundamental Investigation on Deformation Mechanism and Cavitation Phenomena.

DTIC Science & Technology

1988-02-15

NI-MODIFIED SUPERPLASTIC Ti- 6Al - 4V ALLOY, B. Hidalgo-Prada and A.K. Mukherjee, Proc. of Intnl. Conf. of Strength of Metals and AlloyS-7, Montreal...features, e.g., initial porosity (15 to 500 pm diam.), stringers (of Fe-rich particles, 5-30 pm diam.), and small (0.3-3 pm) copper- rich particles...500% or greater, porosity between grains was observed. Some grains as well as grain clusters are visible in Fig. 6. The grain clusters are believed to

Site Investigations with the Site Characterization and Analysis Penetrator System at Fort Dix, New Jersey

DTIC Science & Technology

1993-07-01

rod system or through a tremie tube ; both procedures were used interchangeably at Fort Dix to demon- strate the efficiency and effectiveness of each...allows delivery through either a l/4-in.-diam grout tube or a 3/8-in.-diam rout tube . The grout used at Fort Dix consisted of a mixture of water and... microfine , blended Portland cement (Lehigh Geocem’, Leeds, Alabama). The grout is a suspension of a uniformly produced cement clinker interground with

Transverse injection of a particle-laden liquid jet in supersonic flow: A three-phase flow

NASA Technical Reports Server (NTRS)

Schetz, J. A.; Ogg, J. C.

1980-01-01

The results of a two part study of the behavior of particle laden liquid jets injected into air are presented. Water was used as the liquid carrier and either 1-37 or 13-44 microns diam. spherical glass beads with a specific gravity of 2.8-3.0 as the particles. The observations were mainly photographic. The breakup of jets injected into still air was investigated as a function of particle loading, and the results were compared to the pure liquid jet case. The jets were found to be more stable with particles present. The length to breakup was increased, and the formation of satellite droplets was suppressed. The penetration and breakup of transverse jets in a Mach 3.0 air stream was studied. The general breakup mechanism of wave formation was found to be the same as for the all liquid case. Significant separation of the phases was observed, and the penetration of the liquid phase was reduced compared to all liquid cases at the same value of the jet to free stream momentum flux ratio.

Drug-indiced aseptic meningitis: development of subacute sclerosing panencephalitis following repeated intraventricular infusion therapy with interferon alpha/beta.

PubMed

Imataka, George; Nakagawa, Eiji; Yamanouchi, Hideo; Arisaka, Osamu

2011-12-01

Interferon (IFN)-α was reported to be effective in longterm intrathecal treatment of subacute sclerosing panencephalitis (SSPE). However, the side effects related with longterm use of IFN-α/β are unclear. We evaluated the therapeutic effects of IFN-α/β in a 13-years-old patient with SSPE. The cerebrospinal fluid (CSF) measles antibody titer was 64 × NT/128×HI, IgG-index was 4.5, and the SSPE diagnosis was based on electroencephalography (Jabbour-stage II on admission). With Inosiplex (INP) given orally, IFN-α (3 × 10(6) units) was infused intraventricularly twice-a-week for 1-year. Resultantly, CSF cell count was elevated (2502/3), total protein and glucose levels were normal; however, DIAM occurred repeatedly. Consequently, reduced IFN-α (5 × 10(5) units) with hydrocorton was administered at 2-months interval for 19 months, during which, DIAM occurred four times. Therefore, IFN-β (3 × 10(6) units; twice-a-week) therapy was started and continued for 3 years. Although the symptoms were improved considerably, DIAM recurred after 15-months therapy and CSF cell counts were also elevated (2121/3). Since SSPE progressed to Jabbour-stage IV, indicated by irreversible consciousness disorder, IFN therapy was discontinued and INP monotherapy was followed for another 3 years. We, therefore, concluded that the longterm intraventricular IFN-α/β infusion therapy of SSPE involved the potential risk of DIAM with serious irreversible neurological sequelae and should be monitored carefully.

Biomechanical analysis of a new lumbar interspinous device with optimized topology.

PubMed

Chen, Chen-Sheng; Shih, Shih-Liang

2018-01-06

Interspinous spacers used stand-alone preserve joint movement but provide little protection for diseased segments of the spine. Used as adjuncts with fusion, interspinous spacers offer rigid stability but may accelerate degeneration on adjacent levels. Our new device is intended to balance the stability and preserves motion provided by the implant. A new interspinous spacer was devised according to the results of topology optimization studies. Four finite element (FE) spine models were created that consisted of an intact spine without an implant, implantation of the novel, the device for intervertebral assisted motion (DIAM system), and the Dynesys system. All models were loaded with moments, and their range of motions (ROMs), peak disc stresses, and facet contact forces were analyzed. The limited motion segment ROMs, shielded disc stresses, and unloaded facet contact forces of the new devices were greater than those of the DIAM and Dynesys system at L3-L4 in almost all directions of movements. The ROMs, disc stresses, and facet contact forces of the new devices at L2-L3 were slightly greater than those in the DIAM system, but much lower than those in the Dynesys system in most directions. This study demonstrated that the new device provided more stability at the instrumented level than the DIAM system did, especially in lateral rotation and the bending direction. The device caused fewer adjacent ROMs, lower disc stresses, and lower facet contact forces than the Dynesys system did. Additionally, this study conducted topology optimization to design the new device and created a smaller implant for minimal invasive surgery.

The design, construction and testing of the optics for a 147-cm-aperture telescope

NASA Technical Reports Server (NTRS)

Buchroeder, R. A.; Elmore, L. H.; Shack, R. V.; Slater, P. N.

1972-01-01

Geodetic optics research for the Air Force Cambridge Research Laboratories (AFCRL) is described. The work consisted mainly of the fabrication of the optical components for a telescope with a 152-cm-diam (60-in.) primary mirror masked down to 147-cm-diam for use by the AFCRL for a lunar ranging experiment. Among the achievements of this contract were the following: completion of the primary and secondary mirrors for a high-quality 147-cm-diam telescope system in eight months from the start of edging the primary; manufacture and testing of a unique center mount for the primary according to an AFCRL design that allowed for a thin-edged and therefore less-massive mirror; and development of a quantitative analysis of the wire test for calculating the departure of the mirror figure from the design figure quickly and accurately after each polishing step. This analysis method in conjunction with a knowledge of polishing rates for given weights and diameters of tools, mirror, and polishing materials should considerably reduce the polishing time required for future large mirrors.

Dynamics of a Z-pinch x-ray source for heating inertial-confinement-fusion relevant hohlraums to 120-160 eV

NASA Astrophysics Data System (ADS)

Sanford, T. W. L.; Olson, R. E.; Mock, R. C.; Chandler, G. A.; Leeper, R. J.; Nash, T. J.; Ruggles, L. E.; Simpson, W. W.; Struve, K. W.; Peterson, D. L.; Bowers, R. L.; Matuska, W.

2000-11-01

A Z-pinch radiation source has been developed that generates 60±20 kJ of x rays with a peak power of 13±4 TW through a 4-mm-diam axial aperture on the Z facility. The source has heated National Ignition Facility-scale (6-mm-diam by 7-mm-high) hohlraums to 122±6 eV and reduced-scale (4-mm-diam by 4-mm-high) hohlraums to 155±8 eV—providing environments suitable for indirect-drive inertial confinement fusion studies. Eulerian-RMHC (radiation-magnetohydrodynamics code) simulations that take into account the development of the Rayleigh-Taylor instability in the r-z plane provide integrated calculations of the implosion, x-ray generation, and hohlraum heating, as well as estimates of wall motion and plasma fill within the hohlraums. Lagrangian-RMHC simulations suggest that the addition of a 6 mg/cm3 CH2 fill in the reduced-scale hohlraum decreases hohlraum inner-wall velocity by ˜40% with only a 3%-5% decrease in peak temperature, in agreement with measurements.

Modified Diet Recipes for Army Medical Facilities

DTIC Science & Technology

1983-10-20

Mashed 1/2 cup 100 Whole .1-2" diam. 100 Dried Beans 1/2 cup 100 Kidney Corn 1/3 cup 80 Macaroni 1/2 cup 70 Noodles 1/2 cup 80 Peas, green 1/2...5 mg sodium Na/R Bread or Toast Cereal, Cooked Na/R Potato, Sweet Na/R Mashed Na/R Whole Dried Beans Kidney Corn Macaroni Noodles Peas...cup Mashed - no milk 1/3 cup Baked-1/3 of 2-1/4 diam. Diced 1/3 cup Mashed - no milk 1/3 cup Beans, Kidney 1/3 cup Corn Macaroni Noodles

Variable temperature superconducting microscope

NASA Astrophysics Data System (ADS)

Cheng, Bo; Yeh, W. J.

2000-03-01

We have developed and tested a promising type of superconducting quantum interference device (SQUID) microscope, which can be used to detect vortex motion and can operate in magnetic fields over a large temperature range. The system utilizes a single-loop coupling transformer, consisting of a patterned high Tc superconducting thin film. At one end of the transformer, a 20 μm diam detecting loop is placed close to the sample. At the other end, a large loop is coupled to a NbTi coil, which is connected to a low Tc SQUID sensor. Transformers in a variety of sizes have been tested and calibrated. The results show that the system is capable of detecting the motion of a single vortex. We have used the microscope to study the behavior of moving vortices at various positions in a YBa2Cu3O7 thin film bridge.

Molecular theory for self assembling mixtures of patchy colloids and colloids with spherically symmetric attractions: The single patch case

NASA Astrophysics Data System (ADS)

Marshall, Bennett D.; Chapman, Walter G.

2013-09-01

In this work we develop a new theory to model self assembling mixtures of single patch colloids and colloids with spherically symmetric attractions. In the development of the theory we restrict the interactions such that there are short ranged attractions between patchy and spherically symmetric colloids, but patchy colloids do not attract patchy colloids and spherically symmetric colloids do not attract spherically symmetric colloids. This results in the temperature, density, and composition dependent reversible self assembly of the mixture into colloidal star molecules. This type of mixture has been recently synthesized by grafting of complimentary single stranded DNA [L. Feng, R. Dreyfus, R. Sha, N. C. Seeman, and P. M. Chaikin, Adv. Mater. 25(20), 2779-2783 (2013)], 10.1002/adma.201204864. As a quantitative test of the theory, we perform new monte carlo simulations to study the self assembly of these mixtures; theory and simulation are found to be in excellent agreement.

Managing Personal and Group Collections of Information

NASA Technical Reports Server (NTRS)

Wolfe, Shawn R.; Wragg, Stephen D.; Chen, James R.; Koga, Dennis (Technical Monitor)

1999-01-01

The internet revolution has dramatically increased the amount of information available to users. Various tools such as search engines have been developed to help users find the information they need from this vast repository. Users often also need tools to help manipulate the growing amount of useful information they have discovered. Current tools available for this purpose are typically local components of web browsers designed to manage URL bookmarks. They provide limited functionalities to handle high information complexities. To tackle this have created DIAMS, an agent-based tool to help users or groups manage their information collections and share their collections with other. the main features of DIAMS are described here.

Replacement of Chromium Electroplating on Gas Turbine Engine Components Using Thermal Spray Coatings

DTIC Science & Technology

2005-07-20

Composition, Wgt % Powder Composition, Wgt % Powder WC/17Co Diamalloy 2005 WC/17Co Metco 73F-NS-1 Cr3C2-20 (Ni,Cr) Amdry 5260/Diam 3007 Co-28 Mo - 8 Cr-2...Si** Metco 66F-NS Co-28 Mo -17 Cr-3 Si* Diamalloy 3001 Co-28 Mo - 8 Cr-2 Si** Diamalloy 3002 * Tribaloy 800 ** Tribaloy 400 20 4.4. Coating...Work WC/17Co Diamalloy 2005 Yes -- Cr3C2-20 (Ni,Cr) Amdry 5260/Diam 3007 -- Yes Co-28 Mo -17 Cr-3 Si* Diamalloy 3001 -- Yes Co-28 Mo - 8 Cr-2 Si

Stratigraphy of the Descartes region /Apollo 16/ - Implications for the origin of samples

NASA Technical Reports Server (NTRS)

Head, J. W.

1974-01-01

Analysis of terrain in the Apollo 16 Descartes landing region shows a series of features that form a stratigraphic sequence which dominates the history and petrogenesis at the site. An ancient 150-km diam crater centered on the Apollo 16 site is one of the earliest recognizable major structures. Nectaris ejecta was concentrated in a regional low at the base of the back slope of the Nectaris basin to form the Descartes Mountains. Subsequently, a 60-km diam crater formed in the Descartes Mountains centered about 25 km to the west of the site. This crater dominates the geology and petrogenetic history of the site. Stone and Smoky Mountains represent the degraded terraced crater walls, and the dark matrix breccias and metaclastic rocks derived from North and South Ray craters represent floor fallback breccias from this cratering event. The interpretation is developed that the stratigraphy of the Cayley and Descartes, and thus the historical record of the Apollo 16 region, documents the complex interaction of deposits and morphology of local and regional impact cratering events. Large local 60- to 150-km diam craters have had a dramatic and previously unrecognized effect on the history and petrology of the Apollo 16 site.

Performance Characteristics of a DME Propellant Arcjet Thruster

NASA Astrophysics Data System (ADS)

Kakami, Akira; Beeppu, Shinji; Maiguma, Muneyuki; Tachibana, Takeshi

This paper describes the influence of cathode configuration on performance of an arcjet thruster using dimethyl ether (DME) propellant. DME, an ether compound, has suitable characteristics for a space propulsion system; DME is storable in a liquid state without being kept under a high pressure, and requires no sophisticated temperature management such as a cryogenic device. DME can be gasified and liquefied simply by adjusting temperature whereas hydrazine, a conventional propellant, requires an iridium-based particulate catalyst for its gasification. In this study, thrust of a 1-kW class DME arcjet thruster is measured at a discharge current of 13 A, DME mass flow rates ranging 15 to 60 mg/s under three cathode configurations: flat-tip rods of 2 and 4 mm in diam. and 4-mm-diam. rod having a cavity of 2 mm in diameter. Thrust measurements show that thrust is increased with propellant mass flow rate. Among the tested cathodes, the flat-tip rod of 4 mm in diam. with 55 mg/s DME flow rate yielded the highest performance: specific impulse of 330 s, thrust of 0.18 N, discharge power of 1400 W and specific power of 25 MJ/kg.

Are Nanoparticles Spherical or Quasi-Spherical?

PubMed

Sokolov, Stanislav V; Batchelor-McAuley, Christopher; Tschulik, Kristina; Fletcher, Stephen; Compton, Richard G

2015-07-20

The geometry of quasi-spherical nanoparticles is investigated. The combination of SEM imaging and electrochemical nano-impact experiments is demonstrated to allow sizing and characterization of the geometry of single silver nanoparticles. © 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

The Manicouagan impact structure - An analysis of its original dimensions and form

NASA Technical Reports Server (NTRS)

Grieve, R. A. F.; Head, J. W., III

1983-01-01

A reanalysis of the preerosional geology of the Canadian impact crater, Manicouagan, is presented. Although most of the current features of the annular moat are primarily a result of erosional processes, the original dimensions of the cavity have been determined to include a transient cavity 60 km in diam. The final floor of the crater was studied and found to be an impact melt-covered inner plateau 55 km in diam. Comparisons with similar crater bottoms on the moon are used to estimate a final crater rim diameter of 85-95 km. The inner plateau and relatively smooth deposits on the crater floor are noted to be most similar to the lunar crater Copernicus.

Overall and blade element performance of a 1.20-pressure-ratio fan stage with rotor blades reset -5 deg

NASA Technical Reports Server (NTRS)

Lewis, G. W., Jr.; Osborn, W. M.; Moore, R. D.

1976-01-01

A 51-cm-diam model of a fan stage for a short haul aircraft was tested in a single stage-compressor research facility. The rotor blades were set 5 deg toward the axial direction (opened) from design setting angle. Surveys of the air flow conditions ahead of the rotor, between the rotor and stator, and behind the stator were made over the stable operating range of the stage. At the design speed of 213.3 m/sec and a weight flow of 31.5 kg/sec, the stage pressure ratio and efficiency were 1.195 and 0.88, respectively. The design speed rotor peak efficiency of 0.91 occurred at the same flow rate.

Overall and blade element performance of a 1.20 pressure ratio fan stage with rotor blades reset -7 deg

NASA Technical Reports Server (NTRS)

Lewis, G. W., Jr.; Kovich, G.

1976-01-01

A 51-cm-diam model of a fan stage for short haul aircraft was tested in a single stage compressor research facility. The rotor blades were set 7 deg toward the axial direction (opened) from the design setting angle. Surveys of the air flow conditions ahead of the rotor, between the rotor and stator, and behind the stator were made over the stable operating range of the stage. At the design speed and a weight flow of 30.9 kg/sec, the stage pressure ratio and efficiency were 1.205 and 0.85, respectively. The design speed rotor peak efficiency of 0.90 occurred at a flow rate of 32.5 kg/sec.

The realuminizing of the 7-meter-diameter solar simulator collimating mirror

NASA Technical Reports Server (NTRS)

Noller, E. W.

1994-01-01

This paper describes the modification of a three-electron-beam (EB) gun system for vacuum depositing a highly reflective aluminum coating on a 7.01-m (23-ft) -diam nickel-plated aluminum collimating mirror. The mirror is part of the JPL 7.62-m space simulator that was recently modernized with a new high vacuum pumping system, solar lamp power supplies, solar optic lens system, and refurbished collimating mirror. The 7.01-m 12,700-kg (14-ton) spherical collimating mirror was removed from this facility for replating with 381 micron (0.015 in.) of electroless nickel and polished to a specular finish for realuminizing. The space chamber served as the vacuum coating vessel for the realuminizing coating process. The mirror is the primary reflector for the solar simulation system and the aluminized reflective surface is its most critical performance element. The uniformity of thickness and high reflectivity of the coating in visible and near-ultraviolet (UV) light governs the accuracy of the beam for solar testing. The uniformity of the thin-film thickness also controls the durability of the mirror over time. The mirror was polished to a 64-percent reflectivity with a uniformity of 1.5 percent. The performance goal for the aluminizing was 89 percent with +/- 0.5-percent variation over the mirror.

A Simple Method to Measure the Trajectory of a Spherical Pendulum

ERIC Educational Resources Information Center

Yang, Hujiang; Xiao, Jinghua; Yang, Tianyu; Qiu, Chen

2011-01-01

Compared with a single gravity pendulum, the spherical pendulum behaves more complicatedly in experiments, which makes it difficult to measure. In this paper, we present a method to visualize the trajectories of a spherical pendulum by employing a gravity ball with a lit LED and a digital camera. This new measurement is inexpensive and easy to…

Exploring novel paths towards protein signatures of chronic pain.

PubMed

Gomez-Varela, David; Schmidt, Manuela

2016-01-01

Pain is a major symptom of many medical conditions and the worldwide number one reason for people to seek medical assistance. It affects the quality of life of patients and poses a heavy financial burden on society with high costs of treatment and lost productivity. Furthermore, the treatment of chronic pain presents a big challenge as pain therapeutics often lack efficacy and exhibit minimal safety profiles. The latter can be largely attributed to the fact that current therapies target molecules with key physiological functions throughout the body. In light of these difficulties, the identification of proteins specifically involved in chronic pain states is of paramount importance for designing selective interventions. Several profiling efforts have been employed with the aim to dissect the molecular underpinnings of chronic pain, both on the level of the transcriptome and proteome. However, generated results are often inconsistent and non-overlapping, which is largely due to inherent technical constraints. A potential solution may be offered by emerging strategies capable of performing standardized and reproducible proteome analysis, such as data-independent acquisition-mass spectrometry (DIA-MS). We have recently demonstrated the applicability of DIA-MS to interrogate chronic pain-related proteome alterations in mice. Based on our results, we aim to provide an overview on DIA-MS and its potential to contribute to the comprehensive characterization of molecular signatures underlying pain pathologies. © The Author(s) 2016.

Sound pressure distribution and power flow within the gerbil ear canal from 100 Hz to 80 kHz

PubMed Central

Ravicz, Michael E.; Olson, Elizabeth S.; Rosowski, John J.

2008-01-01

Sound pressure was mapped in the bony ear canal of gerbils during closed-field sound stimulation at frequencies from 0.1 to 80 kHz. A 1.27-mm-diam probe-tube microphone or a 0.17-mm-diam fiber-optic miniature microphone was positioned along approximately longitudinal trajectories within the 2.3-mm-diam ear canal. Substantial spatial variations in sound pressure, sharp minima in magnitude, and half-cycle phase changes occurred at frequencies >30 kHz. The sound frequencies of these transitions increased with decreasing distance from the tympanic membrane (TM). Sound pressure measured orthogonally across the surface of the TM showed only small variations at frequencies below 60 kHz. Hence, the ear canal sound field can be described fairly well as a one-dimensional standing wave pattern. Ear-canal power reflectance estimated from longitudinal spatial variations was roughly constant at 0.2–0.5 at frequencies between 30 and 45 kHz. In contrast, reflectance increased at higher frequencies to at least 0.8 above 60 kHz. Sound pressure was also mapped in a microphone-terminated uniform tube—an “artificial ear.” Comparison with ear canal sound fields suggests that an artificial ear or “artificial cavity calibration” technique may underestimate the in situ sound pressure by 5–15 dB between 40 and 60 kHz. PMID:17902852

Orientale multi-ringed basin interior and implications for the petrogenesis of lunar highland samples

NASA Technical Reports Server (NTRS)

Head, J. W.

1974-01-01

The lunar Orientale basin is a 900 km diam circular topographic depression covering an area of over 700,000 sq km on the western limb of the moon. Three major rings surround the central Mare Orientale. Orientale basin structures are considered along with Orientale basin deposits and the sequence of formation of structures and deposits. It is found that the structures and facies are related in time and mode of origin to the formation of a major impact crater approximately 620 km in diam. The study suggests that the Orientale basin configuration is very nearly the same as its geometry at its time of formation. The formation of multiringed basins such as Orientale provides a mechanism for an instantaneous production of tremendous volumes of melted lunar crystal material.

Biocompatibility and mechanical properties of diamond-like coatings on cobalt-chromium-molybdenum steel and titanium-aluminum-vanadium biomedical alloys.

PubMed

Hinüber, C; Kleemann, C; Friederichs, R J; Haubold, L; Scheibe, H J; Schuelke, T; Boehlert, C; Baumann, M J

2010-11-01

Diamond-like carbon (DLC) films are favored for wear components because of diamond-like hardness, low friction, low wear, and high corrosion resistance (Schultz et al., Mat-wiss u Werkstofftech 2004;35:924-928; Lappalainen et al., J Biomed Mater Res B Appl Biomater 2003;66B:410-413; Tiainen, Diam Relat Mater 2001;10:153-160). Several studies have demonstrated their inertness, nontoxicity, and the biocompatibility, which has led to interest among manufacturers of surgical implants (Allen et al., J Biomed Mater Res B Appl Biomater 2001;58:319-328; Uzumaki et al., Diam Relat Mater 2006;15:982-988; Hauert, Diam Relat Mater 2003;12:583-589; Grill, Diam Relat Mater 2003;12:166-170). In this study, hydrogen-free amorphous, tetrahedrally bonded DLC films (ta-C) were deposited at low temperatures by physical vapor deposition on medical grade Co28Cr6Mo steel and the titanium alloy Ti6Al4V (Scheibe et al., Surf Coat Tech 1996;85:209-214). The mechanical performance of the ta-C was characterized by measuring its surface roughness, contact angle, adhesion, and wear behavior, whereas the biocompatibility was assessed by osteoblast (OB) attachment and cell viability via Live/Dead assay. There was no statistical difference found in the wettability as measured by contact angle measurements for the ta-C coated and the uncoated samples of either Co28Cr6Mo or Ti6Al4V. Rockwell C indentation and dynamic scratch testing on 2-10 μm thick ta-C films on Co28Cr6Mo substrates showed excellent adhesion with HF1 grade and up to 48 N for the critical load L(C2) during scratch testing. The ta-C coating reduced the wear from 3.5 × 10(-5) mm(3)/Nm for an uncoated control sample (uncoated Co28Cr6Mo against uncoated stainless steel) to 1.1 × 10(-7) mm(3)/Nm (coated Co28Cr6Mo against uncoated stainless steel) in reciprocating pin-on-disk testing. The lowest wear factor of 3.9 × 10(-10) mm(3)/Nm was measured using a ta-C coated steel ball running against a ta-C coated and polished Co28Cr6Mo disk. Student's t-test found that the ta-C coating had no statistically significant (p < 0.05) effect on OB attachment, when compared with the uncoated control samples. There was no significant difference (p < 0.05) in the Live/Dead assay results in cell death between the ta-C coated Co28Cr6Mo and Ti6Al4V samples and the uncoated controls. Therefore, these ta-C coatings show improved wear and corrosion (Dorner-Reisel et al., Diam Relat Mater 2003;11:823-827; Affato et al., J Biomed Mater Res B Appl Biomater 2000;53:221-226; Dorner-Reisel et al., Surf Coat Tech 2004;177-178:830-837; Kim et al., Diam Relat Mater 2004;14:35-41) performance and excellent in vitro cyto-compatibility, when compared with currently used uncoated Co28Cr6Mo and Ti6Al4V implant materials.

Airborne UV photon-counting radiometer

NASA Astrophysics Data System (ADS)

Bauer, Marc C.; Wilcher, George; Banks, Calvin R.; Wood, Ronald L.

2000-11-01

The radiometric measurements group at the Arnold Engineering Development Center (AEDC) has developed new solar-blind radiometers for the SENSOR TALON flight test. These radiometers will be flown in an instrument pod by the 46th Test Wing at Eglin AFB. The radiometers are required to fit into a single quadrant of a 22-in.-diam sphere turret of the instrument pod. Because of minimal space requirements and photon-counting sensitivity needs, the radiometric measurements group used image intensifiers instead of the standard photomultiplier tubes (PMTs). The new design concept improved the photon-counting sensitivity, dynamic range, and uniformity of the field of view as compared to standard PMTs. A custom data acquisition system was required to miniaturize the electronics and generate a pulse code-modulated (PCM) data stream to the standard tape recording system.

Dual spherical single-mode-multimode-single-mode optical fiber temperature sensor based on a Mach–Zehnder interferometer

NASA Astrophysics Data System (ADS)

Tan, Jianchang; Feng, Guoying; Zhang, Shulin; Liang, Jingchuan; Li, Wei; Luo, Yun

2018-07-01

A dual spherical single-mode-multimode-single-mode (DSSMS) optical fiber temperature sensor based on a Mach–Zehnder interferometer (MZI) was designed and implemented in this paper. Theoretical and experimental results indicated that the LP01 mode in the core and the LP09 mode excited by the spherical structure were maintained and transmitted via multimode fiber and interfered at the second spherical structure, resulting in the interference spectrum. An increase or decrease in temperature can cause significant red-shift or blue-shift of the spectrum, respectively. The linearity of the spectral shift due to the temperature change is ~0.999, the sensitivity at 30 °C–540 °C is ~37.372 pm °C‑3, and at  ‑25 °C–25 °C is ~37.28 pm °C‑1. The reproducibility error of this all-fiber temperature sensor at 30 °C–540 °C is less than 0.15%. Compared with the optical fiber sensor with a tapered structure and fiber core offset structure, this MZI-based DSSMS optical fiber temperature sensor has higher mechanical strength. Moreover, benefiting from low-cost and environmentally friendly materials, it is expected to be a novel micro-nano all-fiber sensor.

Characteristics of laser beam focusing with single spherical mirrors during laser treatment

NASA Astrophysics Data System (ADS)

Borkin, A. G.; Drobyazko, S. V.; Kosheleva, G. A.; Pavlovich, Yu. V.; Senatorov, Yu. M.; Fromm, V. A.; Kurchatov, I. V.

1988-04-01

Focusing of a laser beam with a single spherical mirror is analyzed, such a mirror being combined with a rotatable annular plane mirror in a coaxial configuration. Its focal length must be sufficiently large to ensure adequately high power density and to avoid shielding. When the distance from mirror to laser cavity is too large, then the laser beam may degenerate into a nonannular one and its focusing without loss may become unattainable. Tilting the spherical mirror will make this possible, even when the laser beam is not annular, if astigmatism as well as spherical aberration are minimized. Such a focusing mirror made of metal is theoretically shown to be much more effective than a focusing lens made of KC1 crystal; this has been confirmed experimentally in a CO sub 2 laser facility for perforation of tubular seperator meshes.

A multiball read-out for the spherical proportional counter

NASA Astrophysics Data System (ADS)

Giganon, A.; Giomataris, I.; Gros, M.; Katsioulas, I.; Navick, X. F.; Tsiledakis, G.; Savvidis, I.; Dastgheibi-Fard, A.; Brossard, A.

2017-12-01

We present a novel concept of proportional gas amplification for the read-out of the spherical proportional counter. The standard single-ball read-out presents limitations for large diameter spherical detectors and high-pressure operations. We have developed a multi-ball read-out system which consists of several balls placed at a fixed distance from the center of the spherical vessel. Such a module can tune the volume electric field at the desired value and can also provide detector segmentation with individual ball read-out. In the latter case, the large volume of the vessel becomes a spherical time projection chamber with 3D capabilities.

Drainage information analysis and mapping system.

DOT National Transportation Integrated Search

2012-10-01

The primary objective of this research is to develop a Drainage Information Analysis and Mapping System (DIAMS), with online inspection : data submission, which will comply with the necessary requirements, mandated by both the Governmental Accounting...

Drainage identification analysis and mapping, phase 2.

DOT National Transportation Integrated Search

2017-01-01

Drainage Identification, Analysis and Mapping System (DIAMS) is a computerized database that captures and : stores relevant information associated with all aboveground and underground hydraulic structures belonging to : the New Jersey Department of T...

Flowering phenology and its implications for management of big-leaf mahogany Swietenia macrophylla in Brazilian Amazonia.

PubMed

Grogan, James; Loveless, Marilyn D

2013-11-01

Flowering phenology is a crucial determinant of reproductive success and offspring genetic diversity in plants. We measure the flowering phenology of big-leaf mahogany (Swietenia macrophylla, Meliaceae), a widely distributed neotropical tree, and explore how disturbance from logging impacts its reproductive biology. We use a crown scoring system to estimate the timing and duration of population-level flowering at three forest sites in the Brazilian Amazon over a five-year period. We combine this information with data on population structure and spatial distribution to consider the implications of logging for population flowering patterns and reproductive success. Mahogany trees as small as 14 cm diam flowered, but only trees > 30 cm diam flowered annually or supra-annually. Mean observed flowering periods by focal trees ranged from 18-34 d, and trees flowered sequentially during 3-4 mo beginning in the dry season. Focal trees demonstrated significant interannual correlation in flowering order. Estimated population-level flowering schedules resembled that of the focal trees, with temporal isolation between early and late flowering trees. At the principal study site, conventional logging practices eliminated 87% of mahogany trees > 30 cm diam and an estimated 94% of annual pre-logging floral effort. Consistent interannual patterns of sequential flowering among trees create incompletely isolated subpopulations, constraining pollen flow. After harvests, surviving subcommercial trees will have fewer, more distant, and smaller potential partners, with probable consequences for post-logging regeneration. These results have important implications for the sustainability of harvesting systems for tropical timber species.

Note: Evaluation of microfracture strength of diamond materials using nano-polycrystalline diamond spherical indenter

NASA Astrophysics Data System (ADS)

Sumiya, H.; Hamaki, K.; Harano, K.

2018-05-01

Ultra-hard and high-strength spherical indenters with high precision and sphericity were successfully prepared from nanopolycrystalline diamond (NPD) synthesized by direct conversion sintering from graphite under high pressure and high temperature. It was shown that highly accurate and stable microfracture strength tests can be performed on various super-hard diamond materials by using the NPD spherical indenters. It was also verified that this technique enables quantitative evaluation of the strength characteristics of single crystal diamonds and NPDs which have been quite difficult to evaluate.

New spherical optical cavities with non-degenerated whispering gallery modes

NASA Astrophysics Data System (ADS)

Kumagai, Tsutaru; Palma, Giuseppe; Prudenzano, Francesco; Kishi, Tetsuo; Yano, Tetsuji

2017-02-01

New spherical resonators with internal defects are introduced to show anomalous whispering gallery modes (WGMs). The defect induces a symmetry breaking spherical cavity and splits the WGMs. A couple of defects, a hollow sphere (bubble), and a hollow ring, have been studied. The hollow sphere was fabricated and the splitting of WGM was observed. In this paper, this "non-degenerated WGMs (non-DWGMs) resonance" in a microsphere with hollow defect structure is reviewed based on our research. The resonance of WGMs in a sphere is identified by three integer parameters: the angular mode number, l, azimuthal mode number m, and radial mode number, n. The placement of the defect such as a hollow ring or single bubble is shown to break symmetry and resolve the degeneracy concerning m. This induces a variety of resonant wavelengths of the spherical cavity. A couple of simulations using the eigenmode and transient analyses propose how the placed defects affect the WGM resonance in the spherical cavity. For the sphere with a single bubble defect, the experimentally observed resonances in Nd-doped tellurite glass microsphere with a single bubble are clarified to be due to the splitting of resonance modes, i.e., the existence of "non-DWGMs" in the sphere. The defect bubble plays a role of opening the optically wide gate to introduce excitation light for Nd3+ pumping using non-DWGMs in the sphere efficiently.

Large-Angle Magnetic Suspension (LAMS)

NASA Technical Reports Server (NTRS)

Oglevie, Ronald E.; Eisenhaure, David B.; Downer, James R.

1988-01-01

Spherical LAMS is magnetic syspension that provides dual functions of magnetic bearing and rotorgimbal system. Provides two degrees of angular freedom within single magnetic suspension system. Approach employs spherically-shaped magnetic-gap surfaces to achieve much-larger angular freedom than available from previous suspensions.

Recent high-speed ballistics experiments at ORNL

NASA Astrophysics Data System (ADS)

Combs, S. K.; Gouge, M. J.; Baylor, L. R.; Fisher, P. W.; Foster, C. A.; Foust, C. R.; Milora, S. L.; Qualls, A. L.

Oak Ridge National Laboratory (ORNL) has been developing pellet injectors for plasma fueling experiments on magnetic confinement devices for almost 20 years. With these devices, pellets (1 to 8 mm in diameter) composed of hydrogen isotopes are formed (at temperatures less than 20 K) and typically accelerated to speeds of (approximately) 1.0 to 2.0 km/s for injection into plasmas of experimental fusion devices. A variety of pellet injector designs have been developed at ORNL, including repeating pneumatic injectors (single- and multiple-barrel light gas guns) that can inject up to hundreds of pellets for long-pulse plasma operation. The repeating pneumatic injectors are of particular importance because long-pulse fueling is required for present large experimental fusion devices, with steady-state operation the objective for future fusion reactors. In this paper, recent advancements in the development of repeating pneumatic injectors are described, including (1) a small-bore (1.8-mm), high-firing-rate (10-Hz) version of a single-stage light gas gun; (2) a repeating single-stage light gas gun for 8-mm-diam tritium pellets; (3) a repeating two-stage light gas gun for operation at higher pellet velocities; and (4) a steady-state hydrogen extruder feed system.

Recent high-speed ballistics experiments at ORNL

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

Combs, S.K.; Gouge, M.J.; Baylor, L.R.

1994-12-31

Oak Ridge National Laboratory (ORNL) has been developing pellet injectors for plasma fueling experiments on magnetic confinement devices for almost 20 years. With these devices, pellets (1 to 8 mm in diameter) composed of hydrogen isotopes are formed (at temperatures <20 K) and typically accelerated to speeds of {approximately} 1.0 to 2.0 km/s for injection into plasmas of experimental fusion devices. A variety of pellet injector designs have been developed at ORNL, including repeating pneumatic injectors (single- and multiple-barrel light gas guns) that can inject up to hundreds of pellets for long-pulse plasma operation. The repeating pneumatic injectors are ofmore » particular importance because long-pulse fueling is required for present large experimental fusion devices, with steady-state operation the objective for future fusion reactors. In this paper, recent advancements in the development of repeating pneumatic injectors are described, including (1) a small-bore (1.8-mm), high-firing-rate (10-Hz) version of a single-stage light gas gun; (2) a repeating single-stage light gas gun for 8-mm-diam tritium pellets; (3) a repeating two-stage light gas gun for operation at higher pellet velocities; and (4) a steady-state hydrogen extruder feed system.« less

Rotation of single live mammalian cells using dynamic holographic optical tweezers

NASA Astrophysics Data System (ADS)

Bin Cao; Kelbauskas, Laimonas; Chan, Samantha; Shetty, Rishabh M.; Smith, Dean; Meldrum, Deirdre R.

2017-05-01

We report on a method for rotating single mammalian cells about an axis perpendicular to the optical system axis through the imaging plane using dynamic holographic optical tweezers (HOTs). Two optical traps are created on the opposite edges of a mammalian cell and are continuously transitioned through the imaging plane along the circumference of the cell in opposite directions, thus providing the torque to rotate the cell in a controlled fashion. The method enables a complete 360° rotation of live single mammalian cells with spherical or near-to spherical shape in 3D space, and represents a useful tool suitable for the single cell analysis field, including tomographic imaging.

Wide scanning spherical antenna

NASA Technical Reports Server (NTRS)

Shen, Bing (Inventor); Stutzman, Warren L. (Inventor)

1995-01-01

A novel method for calculating the surface shapes for subreflectors in a suboptic assembly of a tri-reflector spherical antenna system is introduced, modeled from a generalization of Galindo-Israel's method of solving partial differential equations to correct for spherical aberration and provide uniform feed to aperture mapping. In a first embodiment, the suboptic assembly moves as a single unit to achieve scan while the main reflector remains stationary. A feed horn is tilted during scan to maintain the illuminated area on the main spherical reflector fixed throughout the scan thereby eliminating the need to oversize the main spherical reflector. In an alternate embodiment, both the main spherical reflector and the suboptic assembly are fixed. A flat mirror is used to create a virtual image of the suboptic assembly. Scan is achieved by rotating the mirror about the spherical center of the main reflector. The feed horn is tilted during scan to maintain the illuminated area on the main spherical reflector fixed throughout the scan.

Drainage identification analysis and mapping, phase 2 : technical brief.

DOT National Transportation Integrated Search

2017-01-01

This research studied, tested and rectified the compatibility issue related to the recent upgrades of : NJDOT vendor inspection software, and uploaded all collected data to make Drainage Identification : Analysis and Mapping System (DIAMS) current an...

[Evaluating the maturity of IT-supported clinical imaging and diagnosis using the Digital Imaging Adoption Model : Are your clinical imaging processes ready for the digital era?

PubMed

Studzinski, J

2017-06-01

The Digital Imaging Adoption Model (DIAM) has been jointly developed by HIMSS Analytics and the European Society of Radiology (ESR). It helps evaluate the maturity of IT-supported processes in medical imaging, particularly in radiology. This eight-stage maturity model drives your organisational, strategic and tactical alignment towards imaging-IT planning. The key audience for the model comprises hospitals with imaging centers, as well as external imaging centers that collaborate with hospitals. The assessment focuses on different dimensions relevant to digital imaging, such as software infrastructure and usage, workflow security, clinical documentation and decision support, data exchange and analytical capabilities. With its standardised approach, it enables regional, national and international benchmarking. All DIAM participants receive a structured report that can be used as a basis for presenting, e.g. budget planning and investment decisions at management level.

Measurement of the velocity of neutral fragments by the "correlated ion and neutral time of flight" method combined with "velocity-map imaging"

NASA Astrophysics Data System (ADS)

Berthias, F.; Feketeová, L.; Della Negra, R.; Dupasquier, T.; Fillol, R.; Abdoul-Carime, H.; Farizon, B.; Farizon, M.; Märk, T. D.

2017-08-01

In the challenging field of imaging molecular dynamics, a novel method has been developed and implemented that allows the measurement of the velocity of neutral fragments produced in collision induced dissociation experiments on an event-by-event basis. This has been made possible by combining a correlated ion and neutral time of flight method with a velocity map imaging technique. This new method relies on a multiparametric correlated detection of the neutral and charged fragments from collision induced dissociation on one single detector. Its implementation on the DIAM device (Device for irradiation of biomolecular clusters) (Dispositif d'Irradiation d'Agrégats bioMoléculaires) allowed us to measure the velocity distribution of water molecules evaporated from collision induced dissociation of mass- and energy-selected protonated water clusters.

Analysis of scattering by a linear chain of spherical inclusions in an optical fiber

NASA Astrophysics Data System (ADS)

Chremmos, Ioannis D.; Uzunoglu, Nikolaos K.

2006-12-01

The scattering by a linear chain of spherical dielectric inclusions, embedded along the axis of an optical fiber, is analyzed using a rigorous integral equation formulation, based on the dyadic Green's function theory. The coupled electric field integral equations are solved by applying the Galerkin technique with Mie-type expansion of the field inside the spheres in terms of spherical waves. The analysis extends the previously studied case of a single spherical inhomogeneity inside a fiber to the multisphere-scattering case, by utilizing the classic translational addition theorems for spherical waves in order to analytically extract the direct-intersphere-coupling coefficients. Results for the transmitted and reflected power, on incidence of the fundamental HE11 mode, are presented for several cases.

VizieR Online Data Catalog: Pulsation model data for delta Cep and eta Aql (Merand+, 2015)

NASA Astrophysics Data System (ADS)

Merand, A.; Kervella, P.; Breitfelder, J.; Gallenne, A.; Coude du Foresto, V.; ten Brummelaar, T. A.; McAlister, H. A.; Ridgway, S.; Sturmann, L.; Sturmann, J.; Turner, N. H.

2015-09-01

FITS files containing the stars' (delta Cep and eta Aql) data and model presented in the paper. Each fits file has 3 HDU: 1- primary HDU: contains no data apart from the header. The header has the parameters of the model (keywords 'HIERARCH PARAM') as well as some other quantities derived from the modeling (keywords 'HIERARCH MODEL'). These quantities are aimed at people who would like to reproduce or compare their results with us. 2- 'DATA' HDU: this contains the data used for the fit. Each line is a scalar measurement described as follow: col1='MJD' (E) modified Julian date of the observations col2='OBS' (A50) description of the data point: the string before ";" defines the type, after ";" is the source. after | are anciliary data: for diam, UDdiam: [wavelengthum, interfbaseline_m] for mag: photometric band for color: photometric band1 - photometric band2 col3='MEAS' (E) the actual measurements. units are km/s for Vpuls or Vrad (which includes the p-factor correction), and mas (milli-arcseconds) for diameters (diam of UDdiam). col4='ERR' (E) the uncertainty on the measurement. col5='MODEL' (E) corresponding value predicted by the model col6='PHASE' (E) pulsation phase computed from the model ranges from 0 to 1. col7='PERIOD' (E) pulsation period computed from the model in days 3- 'MODEL' HDU: a tabulation of the pulsation model, as a function of pulsation phase. col1='PHASE' (E) phase from 0 to 1. col2='Vpuls' (E) pulsation velocity, in km/s. col3='Vrad' (E) radial velocity, in km/s. It is Vpuls/p-factor + Vgamma. col4='diam' (E) Rosseland angular diameter, in milliarcseconds (mas). col5='Teff' (E) effective temperature, in Kelvin. col6='Lum' (E) Luminosity in solar luminosities. col7='logg' (E) surface gravity, in log_10(cm/s2). col8,9,10='diamK xxxm' (E) biased angular diameters measured by an interferometer at baselines xxx (in m), for xxx=[100, 200, 300]. In milliarcseconds col>=11= 'MAG ...' or 'COLOR ...' (E) reddenned magnitudes or colors in various bands, depending on the data entry. '...' is the name of band for magnitudes, and pair of bands for colors. (6 data files).

Effect of zone size on the convergence of exact solutions for diffusion in single phase systems with planar, cylindrical or spherical geometry

NASA Technical Reports Server (NTRS)

Unnam, J.; Tenney, D. R.

1981-01-01

Exact solutions for diffusion in single phase binary alloy systems with constant diffusion coefficient and zero-flux boundary condition have been evaluated to establish the optimum zone size of applicability. Planar, cylindrical and spherical interface geometry, and finite, singly infinite, and doubly infinite systems are treated. Two solutions are presented for each geometry, one well suited to short diffusion times, and one to long times. The effect of zone-size on the convergence of these solutions is discussed. A generalized form of the diffusion solution for doubly infinite systems is proposed.

In situ observation of melting and crystallization of Si on porous Si3N4 substrate that repels Si melt

NASA Astrophysics Data System (ADS)

Itoh, Hironori; Okamura, Hideyuki; Asanoma, Susumu; Ikemura, Kouhei; Nakayama, Masaharu; Komatsu, Ryuichi

2014-09-01

High temperature in situ observation of melting and crystallization of spherical Si droplets on a substrate with a porous surface was carried out for the first time using an original in situ observation apparatus. The contact angle between the Si melt and the substrate was measured to be 160°, with the Si melt forming spherical droplets on the substrate. During crystallization, a ring-like pattern was observed on the surface of the spherical Si melt droplets due to crystal growth at low levels of supercooling. The solidified spherical Si crystals consisted of single or twin grains. This demonstrates that high-quality spherical Si crystals can be prepared easily and stably by using a Si melt-repelling substrate.

Numerical aperture limits on efficient ball lens coupling of laser diodes to single-mode fibers with defocus to balance spherical aberration

NASA Technical Reports Server (NTRS)

Wilson, R. Gale

1994-01-01

The potential capabilities and limitations of single ball lenses for coupling laser diode radiation to single-mode optical fibers have been analyzed; parameters important to optical communications were specifically considered. These parameters included coupling efficiency, effective numerical apertures, lens radius, lens refractive index, wavelength, magnification in imaging the laser diode on the fiber, and defocus to counterbalance spherical aberration of the lens. Limiting numerical apertures in object and image space were determined under the constraint that the lens perform to the Rayleigh criterion of 0.25-wavelength (Strehl ratio = 0.80). The spherical aberration-defocus balance to provide an optical path difference of 0.25 wavelength units was shown to define a constant coupling efficiency (i.e., 0.56). The relative numerical aperture capabilities of the ball lens were determined for a set of wavelengths and associated fiber-core diameters of particular interest for single-mode fiber-optic communication. The results support general continuing efforts in the optical fiber communications industry to improve coupling links within such systems with emphasis on manufacturing simplicity, system packaging flexibility, relaxation of assembly alignment tolerances, cost reduction of opto-electronic components and long term reliability and stability.

Paecilomyces tabacinus

USDA-ARS?s Scientific Manuscript database

Culture characteristics - (in the dark, 25 °C after 7 d): Colonies on MEA 30–31 mm diam, velutinous to slightly floccose, mycelium white, sporulation abundant, cream-buff [R30; Ridgway (1912)], exudate clear, small droplets dominate, soluble pigments not observed, reverse cream-buff to chamois (R30)...

Rasamsonia columbiensis

USDA-ARS?s Scientific Manuscript database

Culture characteristics - (in the dark, 25 °C after 7 d): Colonies on MEA 30–31 mm diam, velutinous to slightly floccose, mycelium white, sporulation abundant, cream-buff [R30; Ridgway (1912)], exudate clear, small droplets dominate, soluble pigments not observed, reverse cream-buff to chamois (R30)...

Computer program for analysis of high speed, single row, angular contact, spherical roller bearing, SASHBEAN. Volume 2: Mathematical formulation and analysis

NASA Technical Reports Server (NTRS)

Aggarwal, Arun K.

1993-01-01

Spherical roller bearings have typically been used in applications with speeds limited to about 5000 rpm and loads limited for operation at less than about 0.25 million DN. However, spherical roller bearings are now being designed for high load and high speed applications including aerospace applications. A computer program, SASHBEAN, was developed to provide an analytical tool to design, analyze, and predict the performance of high speed, single row, angular contact (including zero contact angle), spherical roller bearings. The material presented is the mathematical formulation and analytical methods used to develop computer program SASHBEAN. For a given set of operating conditions, the program calculates the bearings ring deflections (axial and radial), roller deflections, contact areas stresses, depth and magnitude of maximum shear stresses, axial thrust, rolling element and cage rotational speeds, lubrication parameters, fatigue lives, and rates of heat generation. Centrifugal forces and gyroscopic moments are fully considered. The program is also capable of performing steady-state and time-transient thermal analyses of the bearing system.

A petrologic and ion microprobe study of a Vigarano Type B refractory inclusion - Evolution by multiple stages of alteration and melting

NASA Technical Reports Server (NTRS)

Macpherson, Glenn J.; Davis, Andrew M.

1993-01-01

A Type B Ca-, Al-rich 6-m-diam inclusion (CAI) found in the Vigarano C3V chondrite was inspected using optical and scanning electron microscopies and ion microprobe analyses. It was found that the primary constituents of the CAI inclusion are (in percent), melilite (52), fassaite, (20), anorthite (18), spinel (10), and trace Fe-Ni metal. It is noted that, while many of the properties of the inclusion indicate solidification from a melt droplet, the Al-26/Mg-26 isotopic systematics and some textural relationships are incompatible with single-stage closed system crystallization of a homogeneous molten droplet, indicating that the history of this inclusion must have been more complex than melt solidification alone. Moreover, there was unusually high content of Na in melilite, suggesting that the droplet did not form by melting of pristine high-temperature nebular condensates.

Orbit on demand - Will cost determine best design?

NASA Technical Reports Server (NTRS)

Macconochie, J. O.; Mackley, E. A.; Morris, S. J.; Phillips, W. P.; Breiner, C. A.; Scotti, S. J.

1985-01-01

Eleven design concepts for vertical (V) and horizontal (H) take-off launch-on-demand manned orbital vehicles are discussed. Attention is given to up to three stages, Mach numbers (sub-, 2, or 3), expendable boosters, drop tanks (DT), and storable (S) or cryogenic fuels. All the concepts feature lifting bodies with circular cross-section and most have a 7 ft diam, 15 ft long payload bay as well as a crew compartment. Expendable elements impose higher costs and in some cases reduce all-azimuth launch capabilities. Single-stage vehicles simplify the logistics whether in H or V configuration. A two-stage H vehicle offers launch offset for the desired orbital plane before firing the rocket engines after take-off and subsonic acceleration. A two-stage fully reusable V form has the second lowest weight of the vehicles studied and an all-azimuth launch capability. Better definition of the prospective mission requirements is needed before choosing among the alternatives.

Pentzien lays diagonal cross of Potomac for Columbia gas

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

Klinger, O.

1976-05-01

One of the most unusual pipeline river crossings was completed last fall by Pentzien, Inc., for Columbia LNG Corp. on the Potomac River at Bryans Road, MD, 22 miles south of Washington, DC. Part of a line delivering regasified Algerian LNG to Virginia and Pennsylvania, this crossing would have been only 7896 ft straight across the river; however, to obtaining necessary country authorization without excessively delaying the project, the line was laid diagonally 19,500 ft across the river at a cost about two-thirds more than for a straight-line crossing. The concrete-coated 36-in.-diam pipe for the project was so heavy thatmore » each transport truck could handle only a single 40-ft length at a time. Laser beams on each side of the river were used to guide both the dredging and pipelaying operations.« less

Power profiles of single vision and multifocal soft contact lenses.

PubMed

Wagner, Sandra; Conrad, Fabian; Bakaraju, Ravi C; Fedtke, Cathleen; Ehrmann, Klaus; Holden, Brien A

2015-02-01

The purpose of this study was to investigate the optical zone power profile of the most commonly prescribed soft contact lenses to assess their potential impact on peripheral refractive error and hence myopia progression. The optical power profiles of six single vision and ten multifocal contact lenses of five manufacturers in the powers -1.00 D, -3.00 D, and -6.00 D were measured using the SHSOphthalmic (Optocraft GmbH, Erlangen, Germany). Instrument repeatability was also investigated. Instrument repeatability was dependent on the distance from the optical centre, manifesting unreliable data for the central 1mm of the optic zone. Single vision contact lens measurements of -6.00 D lenses revealed omafilcon A having the most negative spherical aberration, lotrafilcon A having the least. Somofilcon A had the highest minus power and lotrafilcon A the biggest deviation in positive direction, relative to their respective labelled powers. Negative spherical aberration occurred for almost all of the multifocal contact lenses, including the centre-distance designs etafilcon A bifocal and omafilcon A multifocal. Lotrafilcon B and balafilcon A seem to rely predominantly on the spherical aberration component to provide multifocality. Power profiles of single vision soft contact lenses varied greatly, many having a negative spherical aberration profile that would exacerbate myopia. Some lens types and powers are affected by large intra-batch variability or power offsets of more than 0.25 dioptres. Evaluation of power profiles of multifocal lenses was derived that provides helpful information for prescribing lenses for presbyopes and progressing myopes. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Preliminary experimental results of tungsten wire-array Z-pinches on primary test stand

NASA Astrophysics Data System (ADS)

Huang, Xian-Bin; Zhou, Shao-Tong; Dan, Jia-Kun; Ren, Xiao-Dong; Wang, Kun-Lun; Zhang, Si-Qun; Li, Jing; Xu, Qiang; Cai, Hong-Chun; Duan, Shu-Chao; Ouyang, Kai; Chen, Guang-Hua; Ji, Ce; Wei, Bing; Feng, Shu-Ping; Wang, Meng; Xie, Wei-Ping; Deng, Jian-Jun; Zhou, Xiu-Wen; Yang, Yi

2015-07-01

The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a 20 TW pulsed power driver, which can deliver a ˜10 MA, 70 ns rise-time (10%-90%) current to a short-circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. Preliminary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 13 mm to 30 mm, consisting of 132-300 tungsten wires with 5-10 μm in diameter. Multiple diagnostics were fielded to characterize the x-ray radiation from wire-array Z pinches. The x-ray peak power (˜50 TW) and total radiated energy (˜500 kJ) were obtained from a single 20-mm-diam array with 80-ns stagnation time. The highest x-ray peak power up to 80 TW with 2.4 ns FWHM was achieved by using a nested array with 20-mm outer diameter, and the total x-ray energy from the nested array is comparable to that of single array. Implosion velocity estimated from the time-resolved image measurement exceeds 30 cm/μs. The detailed experimental results and other findings are presented and discussed.

Active sources in the cutoff of centrifugal fans to reduce the blade tones at higher-order duct mode frequencies

NASA Astrophysics Data System (ADS)

Neise, W.; Koopmann, G. H.

1991-01-01

A previously developed (e.g., Neise and Koopmann, 1984; Koopmann et al., 1988) active noise control technique in which the unwanted acoustic signals from centrifugal fans are suppressed by placing two externally driven sources near the cutoff of the casing was applied to the frequency region where not only plane sound waves are propagational in the fan ducts but also higher-order acoustic modes. Using a specially designed fan noise testing facility, the performance of two fans (280-mm impeller diam and 508 mm diam) was monitored with static pressure taps mounted peripherally around the inlet nozzle. Experimental results show that the aerodynamically generated source pressure field around the cutoff is too complex to be successfully counterimaged by only two active sources introduced in this region. It is suggested that, for an efficient application of this noise control technique in the higher-order mode frequency regime, it is neccessary to use an active source involving larger number of individually driven loudspeakers.

A new freshwater amoeba: Cochliopodium pentatrifurcatum n. sp. (Amoebozoa, Amorphea).

PubMed

Tekle, Yonas I; Roger, Anderson O; Lecky, Ariel F; Kelly, Samantha D

2013-01-01

Cochliopodium pentatrifurcatum n. sp. (ATCC(©) 30935(TM) ) is described based on light microscopic morphology, fine structure, and molecular genetic evidence. Cochliopodium pentatrifurcatum n. sp. (length ~ 25 μm) is characterized by surface microscales (0.3 μm tall) containing a circular porous base (~ 0.6 μm diam.) with a thin peripheral rim. Five radially arranged feet, emanating from the base, support a short central column terminating apically as a funnel-shaped collar (~ 0.5 μm diam.) composed of five radial, trifurcate rays extending from the center toward a thin peripheral rim. The central spine is 0.5-0.6 μm long. The comparative morphologies and combined molecular genetic evidence, SSU-rDNA and COI, indicate that the new species falls in a clade sufficiently different from other species to suggest that it is a valid new species. © 2013 The Author(s) Journal of Eukaryotic Microbiology © 2013 International Society of Protistologists.

Estimating macroporosity in a forest watershed by use of a tension infiltrometer

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

Watson, K.W.; Luxmoore, R.J.

The ability to obtain sufficient field hydrologic data at reasonable cost can be an important limiting factor in applying transport models. A procedure is described for using ponded-flow- and tension-infiltration measurements to calculate transport parameters in a forest watershed. Thirty infiltration measurements were taken under ponded-flow conditions and at 3, 6, and 15 cm (H/sub 2/O) tension. It was assumed from capillarity theory that pores > 0.1-, 0.05-, and 0.02-cm diam, respectively, were excluded from the transport process during the tension infiltration measurements. Under ponded flow, 73% of the flux was conducted through macropores (i.e., pores > 0.1-cm diam.). Anmore » estimated 96% of the water flux was transmitted through only 0.32% of the soil volume. In general the larger the total water flux the larger the macropore contribution to total water flux. The Shapiro-Wilk normality test indicated that water flux through both matrix pore space and macropores was log-normally distributed in space.« less

Achievement of ultrahigh solar concentration with potential for efficient laser pumping.

PubMed

Gleckman, P

1988-11-01

Measurements are reported of the irradiance produced by a two-stage solar concentrator designed to approach the thermodynamic limit. Sunlight is collected by a 40.6-cm diam parabolic primary which forms a 0.98-cm diam image. The image is reconcentrated by a nonimaging refracting secondary with index n = 1.53 to a final aperture 1.27 mm in diameter. Thus the geometrical concentration ratio is 102, 000. The highest irradiance value achieved was 4.4 +/- 0.2 kW cm(-2), or 56,000 +/- 5000 suns, relative to a solar disk insolation of 800 W m(-2). This is greater than the previous peak solar irradiance record by nearly a factor of 3, and it is 68% of that existing at the solar surface itself. The efficiency with which we concentrated 55 W of sunlight to a small spot suggests that our two-stage system would be an excellent candidate for solar pumping of solid state lasers.

The Apollo 14 regolith - Chemistry of cores 14210/14211 and 14220 and soils 14141, 14148, and 14149

NASA Technical Reports Server (NTRS)

Laul, J. C.; Papike, J. J.; Simon, S. B.

1982-01-01

Neutron activation analysis was performed on bulk and size fractions from drive tube specimens from 39 cm and 16.5 cm depths, and soil samples taken at the Apollo 14 landing site. Chemical data were obtained for 31 major, minor, and trace elements in the KREEPy soils. The cores were homogeneous in chemical composition, containing 20% LKFM, 15% mare basalt, 6% ANT, and 59% high-K KREEP, according to the classifications of Laul and Papike (1980). The meteoritic fraction was 3-7% for both cores, while the chemical compositions of both cores and soils were similar. Differences were detected in the fractions finer than 10 microns, which were more feldspathic than the coarser samples. The similarities between the grains 1000-90 micron in diam and less than 10 micron in diam, in terms of chemical contents, indicates that the observed agglutinates were derived from fusion of the finest grained fraction. The dominant soil-forming processes were comminution and vertical mixing of the regolith.

Stopped-flow kinetic studies of sphere-to-rod transitions of sodium alkyl sulfate micelles induced by hydrotropic salt.

PubMed

Zhang, Jingyan; Ge, Zhishen; Jiang, Xiaoze; Hassan, P A; Liu, Shiyong

2007-12-15

The kinetics and mechanism of sphere-to-rod transitions of sodium alkyl sulfate micelles induced by hydrotropic salt, p-toluidine hydrochloride (PTHC), were investigated by stopped-flow with light scattering detection. Spherical sodium dodecyl sulfate (SDS) micelles transform into short ellipsoidal shapes at low salt concentrations ([PTHC]/[SDS], chi(PTHC)=0.3 and 0.4). Upon stopped-flow mixing aqueous solutions of spherical SDS micelles with PTHC, the scattered light intensity gradually increases with time. Single exponential fitting of the dynamic traces leads to characteristic relaxation time, tau(g), for the growth process from spherical to ellipsoidal micelles, and it increases with increasing SDS concentrations. This suggests that ellipsoidal micelles might be produced by successive insertion of unimers into spherical micelles, similar to the case of formation of spherical micelles as suggested by Aniansson-Wall (A-W) theory. At chi(PTHC) > or = 0.5, rod-like micelles with much higher axial ratio form. The scattered light intensity exhibits an initially abrupt increase and then levels off. The dynamic curves can be well fitted with single exponential functions, and the obtained tau(g) decreases with increasing SDS concentration. Thus, the growth from spherical to rod-like micelles might proceed via fusion of spherical micelles, in agreement with mechanism proposed by Ikeda et al. At chi(PTHC)=0.3 and 0.6, the apparent activation energies obtained from temperature dependent kinetic studies for the micellar growth are 40.4 and 3.6 kJ/mol, respectively. The large differences between activation energies for the growth from spherical to ellipsoidal micelles at low chi(PTHC) and the sphere-to-rod transition at high chi(PTHC) further indicate that they should follow different mechanisms. Moreover, the sphere-to-rod transition kinetics of sodium alkyl sulfate with varying hydrophobic chain lengths (n=10, 12, 14, and 16) are also studied. The longer the carbon chain lengths, the slower the sphere-to-rod transition.

Division Planes Alternate in Spherical Cells of Escherichia coli

PubMed Central

Begg, K. J.; Donachie, W. D.

1998-01-01

In the spherical cells of Escherichia coli rodA mutants, division is initiated at a single point, from which a furrow extends progressively around the cell. Using “giant” rodA ftsA cells, we confirmed that each new division furrow is initiated at the midpoint of the previous division plane and runs perpendicular to it. PMID:9573213

Tactile detection of slip: surface microgeometry and peripheral neural codes.

PubMed

Srinivasan, M A; Whitehouse, J M; LaMotte, R H

1990-06-01

1. The role of the microgeometry of planar surfaces in the detection of sliding of the surfaces on human and monkey fingerpads was investigated. By the use of a servo-controlled tactile stimulator to press and stroke glass plates on passive fingerpads of human subjects, the ability of humans to discriminate the direction of skin stretch caused by friction and to detect the sliding motion (slip) of the plates with or without micrometer-sized surface features was determined. To identify the associated peripheral neural codes, evoked responses to the same stimuli were recorded from single, low-threshold mechanoreceptive afferent fibers innervating the fingerpads of anesthetized macaque monkeys. 2. Humans could not detect the slip of a smooth glass plate on the fingerpad. However, the direction of skin stretch was perceived based on the information conveyed by the slowly adapting afferents that respond differentially to the stretch directions. Whereas the direction of skin stretch signaled the direction of impending slip, the perception of relative motion between the plate and the finger required the existence of detectable surface features. 3. Barely detectable micrometer-sized protrusions on smooth surfaces led to the detection of slip of these surfaces, because of the exclusive activation of rapidly adapting fibers of either the Meissner (RA) or the Pacinian (PC) type to specific geometries of the microfeatures. The motion of a smooth plate with a very small single raised dot (4 microns high, 550 microns diam) caused the sequential activation of neighboring RAs along the dot path, thus providing a reliable spatiotemporal code. The stroking of the plate with a fine homogeneous texture composed of a matrix of dots (1 microns high, 50 microns diam, and spaced at 100 microns center-to-center) induced vibrations in the fingerpad that activated only the PCs and resulted in an intensive code. 4. The results show that surprisingly small features on smooth surfaces are detected by humans and lead to the detection of slip of these surfaces, with the geometry of the microfeatures governing the associated neural codes. When the surface features are of sizes greater than the response thresholds of all the receptors, redundant spatiotemporal and intensive information is available for the detection of slip.

Spherical nanoindentation stress-strain curves of commercially pure titanium and Ti-6Al-4V

DOE Data Explorer

Weaver, Jordan S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Priddy, Matthew W. [Georgia Inst. of Technology, Atlanta, GA (United States); McDowell, David L. [Georgia Inst. of Technology, Atlanta, GA (United States); Kalidindi, Surya R. [Georgia Inst. of Technology, Atlanta, GA (United States)

2016-07-27

Spherical nanoindentation combined with electron back-scattered diffraction was employed to characterize the grain-scale elastic and plastic anisotropy of single crystal alpha-Ti for commercially pure (CP-Ti) and alloyed (Ti-64) titanium. In addition, alpha-beta Ti (single colony) grains were characterized. The data set includes the nanoindentation force, displacement, and contact stiffness, the nanoindentation stress-strain analysis, and the alpha-Ti crystal orientations. Details of the samples and experimental protocols can be found in Weaver et al. (2016) Acta Materialia doi:10.1016/j.actamat.2016.06.053.

Euler potentials of current-free fields expressed in spherical harmonics

NASA Technical Reports Server (NTRS)

Stern, David P.

1994-01-01

Given a magnetic field B = -del(vector differential operator)(sub gamma) with gamma expanded in spherical harmonics, it is shown that analytic Euler potentials may be derived for B if gamma is asymmetrical but contains only the contribution of a single index n. This work generalizes a result for sectorial harmonics with n = m, derived by Willis and Gardiner (1988).

Data Visualization for ESM and ELINT: Visualizing 3D and Hyper Dimensional Data

DTIC Science & Technology

2011-06-01

technique to present multiple 2D views was devised by D. Asimov . He assembled multiple two dimensional scatter plot views of the hyper dimensional...Viewing Multidimensional Data”, D. Asimov , DIAM Journal on Scientific and Statistical Computing, vol.61, pp.128-143, 1985. [2] “High-Dimensional

DEVELOPMENT OF A SCALABLE, LOW-COST, ULTRANANOCRYSTALLINE DIAMOND ELECTROCHEMICAL PROCESS FOR THE DESTRUCTION OF CONTAMINANTS OF EMERGING CONCERN (CECS) - PHASE I

EPA Science Inventory

This Small Business Innovative Research (SBIR) project will develop and ready for commercialization a scalable, low-cost process for purification of water containing Contaminants of Emerging Concern (CECs) using anodic oxidation with boron-doped ultrananocrystalline diam...

Singing Corrugated Pipes

ERIC Educational Resources Information Center

Crawford, Frank S.

1974-01-01

Presents theoretical and experimental observations made with a musical toy called Hummer consisting of a corrugated flexible plastic tube about three-feet long and one-inch diam open at both ends. Included are descriptions of three new instruments: the Water Pipe, the Gas-Pipe Corrugahorn Bugle, and the Gas-Pipe Blues Corrugahorn. (CC)

Lattice Rotation Patterns and Strain Gradient Effects in Face-Centered-Cubic Single Crystals Under Spherical Indentation

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

Gao, Y. F.; Larson, B. C.; Lee, J. H.

Strain gradient effects are commonly modeled as the origin of the size dependence of material strength, such as the dependence of indentation hardness on contact depth and spherical indenter radius. However, studies on the microstructural comparisons of experiments and theories are limited. First, we have extended a strain gradient Mises-plasticity model to its crystal plasticity version and implemented a finite element method to simulate the load-displacement response and the lattice rotation field of Cu single crystals under spherical indentation. The strain gradient simulations demonstrate that the forming of distinct sectors of positive and negative angles in the lattice rotation fieldmore » is governed primarily by the slip geometry and crystallographic orientations, depending only weakly on strain gradient effects, although hardness depends strongly on strain gradients. Second, the lattice rotation simulations are compared quantitatively with micron resolution, three-dimensional X-ray microscopy (3DXM) measurements of the lattice rotation fields under 100mN force, 100 mu m radius spherical indentations in < 111 >, < 110 >, and < 001 > oriented Cu single crystals. Third, noting the limitation of continuum strain gradient crystal plasticity models, two-dimensional discrete dislocation simulation results suggest that the hardness in the nanocontact regime is governed synergistically by a combination of strain gradients and source-limited plasticity. However, the lattice rotation field in the discrete dislocation simulations is found to be insensitive to these two factors but to depend critically on dislocation obstacle densities and strengths.« less

Glomus perpusillum, a new arbuscular mycorrhizal fungus.

PubMed

Błaszkowski, Janusz; Kovács, Gábor M; Balázs, Tímea

2009-01-01

A new arbuscular mycorrhizal fungal species of genus Glomus, G. perpusillum (Glomeromycota), forming small, hyaline spores is described and illustrated. Spores of G. perpusillum were formed in hypogeous aggregates and occasionally inside roots. They are globose to subglobose, (10-)24(-30) microm diam, rarely egg-shaped, oblong to irregular, 18-25 x 25-63 microm. The single spore wall of G. perpusillum consists of two permanent layers: a finely laminate, semiflexible to rigid outer layer and a flexible to semiflexible inner layer. The inner layer becomes plastic and frequently contracts in spores crushed in PVLG-based mountants and stains reddish white to grayish red in Melzer's reagent. Glomus perpusillum was associated with roots of Ammophila arenaria colonizing sand dunes of the Mediterranean Sea adjacent to Calambrone, Italy, and this is the only site of its occurrence known to date. In single-species cultures with Plantago lanceolata as host plant, G. perpusillum formed vesicular-arbuscular mycorrhiza. Phylogenetic analyses of partial SSU sequences of nrDNA placed the species in Glomus group A with no affinity to its subgroups. The sequences of G. perpusillum unambiguously separated from the sequences of described Glomus species and formed a distinct clade together with in planta arbuscular mycorrhizal fungal sequences found in alpine plants.

Decomposition of Atmospheric Aerosol Phase Function by Particle Size and Morphology via Single Particle Scattering Measurements

NASA Astrophysics Data System (ADS)

Aptowicz, K. B.; Pan, Y.; Martin, S.; Fernandez, E.; Chang, R.; Pinnick, R. G.

2013-12-01

We report upon an experimental approach that provides insight into how particle size and shape affect the scattering phase function of atmospheric aerosol particles. Central to our approach is the design of an apparatus that measures the forward and backward scattering hemispheres (scattering patterns) of individual atmospheric aerosol particles in the coarse mode range. The size and shape of each particle is discerned from the corresponding scattering pattern. In particular, autocorrelation analysis is used to differentiate between spherical and non-spherical particles, the calculated asphericity factor is used to characterize the morphology of non-spherical particles, and the integrated irradiance is used for particle sizing. We found the fraction of spherical particles decays exponentially with particle size, decreasing from 11% for particles on the order of 1 micrometer to less than 1% for particles over 5 micrometer. The average phase functions of subpopulations of particles, grouped by size and morphology, are determined by averaging their corresponding scattering patterns. The phase functions of spherical and non-spherical atmospheric particles are shown to diverge with increasing size. In addition, the phase function of non-spherical particles is found to vary little as a function of the asphericity factor.

Single-camera three-dimensional tracking of natural particulate and zooplankton

NASA Astrophysics Data System (ADS)

Troutman, Valerie A.; Dabiri, John O.

2018-07-01

We develop and characterize an image processing algorithm to adapt single-camera defocusing digital particle image velocimetry (DDPIV) for three-dimensional (3D) particle tracking velocimetry (PTV) of natural particulates, such as those present in the ocean. The conventional DDPIV technique is extended to facilitate tracking of non-uniform, non-spherical particles within a volume depth an order of magnitude larger than current single-camera applications (i.e. 10 cm  ×  10 cm  ×  24 cm depth) by a dynamic template matching method. This 2D cross-correlation method does not rely on precise determination of the centroid of the tracked objects. To accommodate the broad range of particle number densities found in natural marine environments, the performance of the measurement technique at higher particle densities has been improved by utilizing the time-history of tracked objects to inform 3D reconstruction. The developed processing algorithms were analyzed using synthetically generated images of flow induced by Hill’s spherical vortex, and the capabilities of the measurement technique were demonstrated empirically through volumetric reconstructions of the 3D trajectories of particles and highly non-spherical, 5 mm zooplankton.

Preparation of single-crystal spherical γ-Mo2N by temperature-programmed reaction between β-MoO3 and NH3

NASA Astrophysics Data System (ADS)

Wang, Lu; Zhang, Guo-Hua; Chou, Kuo-Chih

2017-10-01

In the present wok, single-crystalline spherical γ-Mo2N powders was successfully prepared by the temperature-programmed reaction of single-crystal spherical β-MoO3 with NH3 in the temperature ranges of 1013-1073 K. Herein, the Mo source used was monoclinic system, β-MoO3, a metastable phase of MoO3. It is found that the characterizations of the as-prepared γ-Mo2N powders are strongly depended on the selection of the MoO3 precursor. In other words, the as-prepared γ-Mo2N powders inherited the shape, size and structure of the used β-MoO3 precursors upon reaction with NH3. In order to make a comparison, β-MoO3 was also reduced by the mixed gases of N2 and H2 with the flow rate ratio of 1:3 at the identical conditions. It was found that pure β-Mo2N polycrystalline can be obtained when the temperature was 1013 K; while further increasing the reaction temperature, metal Mo powder will be turned up.

Resource Letter NSM-1: New insights into the nuclear shell model

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

Dean, David Jarvis; Hamilton, J. H.

2011-01-01

This Resource Letter provides a guide to the literature on the spherical shell model as applied to nuclei. The nuclear shell model describes the structure of nuclei starting with a nuclear core developed by the classical neutron and proton magic numbers N,Z=2,8,20,28,50,82, 126, where gaps occur in the single-particle energies as a shell is filled, and the interactions of valence nucleons that reside beyond that core. Various modern extensions of this model for spherical nuclei are likewise described. Significant extensions of the nuclear shell model include new magic numbers for spherical nuclei and now for deformed nuclei as well. Whenmore » both protons and neutrons have shell gaps at the same spherical or deformed shapes, they can reinforce each other to give added stability to that shape and lead to new magic numbers. The vanishings of the classical spherical shell model energy gaps and magic numbers in new neutron-rich nuclei are described. Spherical and deformed shell gaps are seen to be critical for the existence of elements with Z > 100.« less

OWL: A code for the two-center shell model with spherical Woods-Saxon potentials

NASA Astrophysics Data System (ADS)

Diaz-Torres, Alexis

2018-03-01

A Fortran-90 code for solving the two-center nuclear shell model problem is presented. The model is based on two spherical Woods-Saxon potentials and the potential separable expansion method. It describes the single-particle motion in low-energy nuclear collisions, and is useful for characterizing a broad range of phenomena from fusion to nuclear molecular structures.

Associations of ozone and PM2.5 concentrations with Parkinson’s disease among participants in the Agricultural Health Study

EPA Science Inventory

Background: Evidence from experimental studies suggests that exposure to air pollution may be associated with risk of Parkinson’s disease (PD). Objective: To evaluate associations of ambient ozone and fine particulate matter (PM2.5 – particulate matter with an aerodynamic diam...

Engineering Design Handbook. Discontinuous Fiberglass Reinforced Thermoplastics

DTIC Science & Technology

1981-04-01

Fiberglass Type and Form Glass fibers are...Hall, Ltd. Figure 2-11. Stress vs Volume of Glass Fiber for Nylon and Polypropylene Glass Fiber E glass 12 Mm diam. Fibreglass Ltd Size ref...good dispersion of fiberglass in the end product with pelletized feed stocks. Glass fiber attrition is minimized with the dry blend technique,

Golovinomyces spadaceus causing powdery mildew on Coreopsis hybrid 'Full Moon' (Heliantheae, Asteraceae) in Washington State

USDA-ARS?s Scientific Manuscript database

Symptoms of powdery mildew were observed on a Coreopsis cultivar in the Horticulture and Landscape Architecture Garden on the Washington State University campus, Pullman, Whitman County, Washington. White to off-white sporulating mycelial areas were ~5mm in diam to confluent and confined to adaxial...

Implantable Microsystems for Anatomical Rewiring of Cortical Circuitry: A New Approach for Brain Repair

DTIC Science & Technology

2009-03-01

dopamine or serotonin, provide outputs to large regions of the brain that affect mood, learning, and cognition [4]. Hence, understanding brain function on a...Sutton, B. T. Higashikubo, C. A. Chestek, H. J. Chiel, and H. B. Martin, “Diamond electrodes for neurodynamic studies in Aplysia californica,” Diam

Heteroptera attracted to butterfly traps baited with fish or shrimp carrion

USDA-ARS?s Scientific Manuscript database

Records of Heteroptera collected at butterfly traps baited with fish or shrimp carrion during collecting trips to Bolivia, Brazil, Colombia, Ecuador, and Peru are presented. Traps consisted of a cylinder of net fabric (about 35 cm diam, 75 cm length) attached on the top and bottom to square pieces ...

Power collection reduction by mirror surface nonflatness and tracking error for a central receiver solar power system.

PubMed

McFee, R H

1975-07-01

The effects of random waviness, curvature, and tracking error of plane-mirror heliostats in a rectangular array around a central-receiver solar power system are determined by subdividing each mirror into 484 elements, assuming the slope of each element to be representative of the surface slope average at its location, and summing the contributions of all elements and then of all mirrors in the array. Total received power and flux density distribution are computed for a given sun location and set of array parameter values. Effects of shading and blocking by adjacent mirrors are included in the calculation. Alt-azimuth mounting of the heliostats is assumed. Representative curves for two receiver diameters and two sun locations indicate a power loss of 20% for random waviness, curvature, and tracking error of 0.1 degrees rms, 0.002 m(-1), and 0.5 degrees , 3sigma, respectively, for an 18.2-m diam receiver and 0.3 degrees rms, 0.005 m(-1), and greater than 1 degrees , respectively, for a 30.4-m diam receiver.

Quantification of the dielectric constant of single non-spherical nanoparticles from polarization forces: eccentricity effects.

PubMed

Gomila, G; Esteban-Ferrer, D; Fumagalli, L

2013-12-20

We analyze by means of finite-element numerical calculations the polarization force between a sharp conducting tip and a non-spherical uncharged dielectric nanoparticle with the objective of quantifying its dielectric constant from electrostatic force microscopy (EFM) measurements. We show that for an oblate spheroid nanoparticle of given height the strength of the polarization force acting on the tip depends linearly on the eccentricity, e, of the nanoparticle in the small eccentricity and low dielectric constant regimes (1 < e < 2 and 1 < ε(r) < 10), while for higher eccentricities (e > 2) the dependence is sub-linear and finally becomes independent of e for very large eccentricities (e > 30). These results imply that a precise account of the nanoparticle shape is required to quantify EFM data and obtain the dielectric constants of non-spherical dielectric nanoparticles. Experimental results obtained on polystyrene, silicon dioxide and aluminum oxide nanoparticles and on single viruses are used to illustrate the main findings.

Harmony: EEG/MEG Linear Inverse Source Reconstruction in the Anatomical Basis of Spherical Harmonics

PubMed Central

Petrov, Yury

2012-01-01

EEG/MEG source localization based on a “distributed solution” is severely underdetermined, because the number of sources is much larger than the number of measurements. In particular, this makes the solution strongly affected by sensor noise. A new way to constrain the problem is presented. By using the anatomical basis of spherical harmonics (or spherical splines) instead of single dipoles the dimensionality of the inverse solution is greatly reduced without sacrificing the quality of the data fit. The smoothness of the resulting solution reduces the surface bias and scatter of the sources (incoherency) compared to the popular minimum-norm algorithms where single-dipole basis is used (MNE, depth-weighted MNE, dSPM, sLORETA, LORETA, IBF) and allows to efficiently reduce the effect of sensor noise. This approach, termed Harmony, performed well when applied to experimental data (two exemplars of early evoked potentials) and showed better localization precision and solution coherence than the other tested algorithms when applied to realistically simulated data. PMID:23071497

Mechanical characterization of Ti-6Al-4V titanium alloy at multiple length scales using spherical indentation stress-strain measurements

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

Weaver, Jordan S.; Kalidindi, Surya R.

Recent advances in spherical indentation stress-strain protocols and analyses have demonstrated the capability for measuring reliably the local mechanical responses in polycrystalline metal samples at different length scales, ranging from sub-micron (regions within individual grains) to several hundreds of microns (regions covering several grains). These recent advances have now made it possible to study systematically the mechanical behavior of a single material system at different length scales, with tremendous potential to obtain new insights into the role of individual phases, interfaces, and other microscale constituents on the macroscale mechanical response of the material. In this paper, we report spherical indentationmore » stress-strain measurements with different indenter sizes (microns to millimeters) on Ti-6Al-4V (Ti-64) which capture the mechanical response of single phase alpha-Ti-64, single colony (alpha-beta), few colonies, and many colonies of Ti-64. The results show that the average mechanical response (indentation modulus and yield strength) from multiple indentations remains relatively unchanged from single phase alpha to many colonies of Ti-64, while the variance in the response decreases with indenter size. In conclusion, the work-hardening response in indentation tests follows a similar behavior up to indentation zones of many colonies, which shows significantly higher work hardening rates.« less

Mechanical characterization of Ti-6Al-4V titanium alloy at multiple length scales using spherical indentation stress-strain measurements

DOE PAGES

Weaver, Jordan S.; Kalidindi, Surya R.

2016-12-01

Recent advances in spherical indentation stress-strain protocols and analyses have demonstrated the capability for measuring reliably the local mechanical responses in polycrystalline metal samples at different length scales, ranging from sub-micron (regions within individual grains) to several hundreds of microns (regions covering several grains). These recent advances have now made it possible to study systematically the mechanical behavior of a single material system at different length scales, with tremendous potential to obtain new insights into the role of individual phases, interfaces, and other microscale constituents on the macroscale mechanical response of the material. In this paper, we report spherical indentationmore » stress-strain measurements with different indenter sizes (microns to millimeters) on Ti-6Al-4V (Ti-64) which capture the mechanical response of single phase alpha-Ti-64, single colony (alpha-beta), few colonies, and many colonies of Ti-64. The results show that the average mechanical response (indentation modulus and yield strength) from multiple indentations remains relatively unchanged from single phase alpha to many colonies of Ti-64, while the variance in the response decreases with indenter size. In conclusion, the work-hardening response in indentation tests follows a similar behavior up to indentation zones of many colonies, which shows significantly higher work hardening rates.« less

Near-UV laser treatment of extrinsic dental enamel stains.

PubMed

Schoenly, J E; Seka, W; Featherstone, J D B; Rechmann, P

2012-04-01

The selective ablation of extrinsic dental enamel stains using a 400-nm laser is evaluated at several fluences for completely removing stains with minimal damage to the underlying enamel. A frequency-doubled Ti:sapphire laser (400-nm wavelength, 60-nanosecond pulse duration, 10-Hz repetition rate) was used to treat 10 extracted human teeth with extrinsic enamel staining. Each tooth was irradiated perpendicular to the surface in a back-and-forth motion over a 1-mm length using an ∼300-µm-diam 10th-order super-Gaussian beam with fluences ranging from 0.8 to 6.4 J/cm(2) . Laser triangulation determined stain depth and volume removed by measuring 3D surface images before and after irradiation. Scanning electron microscopy evaluated the surface roughness of enamel following stain removal. Fluorescence spectroscopy measured spectra of unbleached and photobleached stains in the spectral range of 600-800 nm. Extrinsic enamel stains are removed with laser fluences between 0.8 and 6.4 J/cm(2) . Stains removed on sound enamel leave behind a smooth enamel surface. Stain removal in areas with signs of earlier cariogenic acid attacks resulted in isolated and randomly located laser-induced, 50-µm-diam enamel pits. These pits contain 0.5-µm diam, smooth craters indicative of heat transfer from the stain to the enamel and subsequent melting and water droplet ejection. Ablation stalling of enamel stains is typically observed at low fluences (<3 J/cm(2) ) and is accompanied by a drastic reduction in porphyrin fluorescence from the Soret band. Laser ablation of extrinsic enamel stains at 400 nm is observed to be most efficient above 3 J/cm(2) with minimal damage to the underlying enamel. Unsound underlying enamel is also observed to be selectively removed after irradiation. Copyright © 2012 Wiley Periodicals, Inc.

Background reduction of a spherical gaseous detector

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

Fard, Ali Dastgheibi; Loaiza, Pia; Piquemal, Fabrice

The Spherical gaseous detector (or Spherical Proportional Counter, SPC) is a novel type of detector. It consists of a large spherical volume filled with gas, using a single detection readout channel. The detector allows 100 % detection efficiency. SEDINE is a low background version of SPC installed at the Laboratoire Souterrain de Modane (LSM) underground laboratory (4800 m.w.e) looking for rare events at very low energy threshold, below 100 eV. This work presents the details on the chemical cleaning to reduce internal {sup 210}Pb surface contamination on the copper vessel and the external radon reduction achieved via circulation of pure airmore » inside anti-radon tent. It will be also show the radon measurement of pure gases (Ar, N, Ne, etc) which are used in the underground laboratory for the low background experiments.« less

A concept for global crop forecasting. [using microwave radiometer satellites

NASA Technical Reports Server (NTRS)

Lovelace, U. M.; Wright, R. L.

1983-01-01

The mission, instrumentation, and design concepts for microwave radiometer satellites for continuous crop condition forecasting and monitoring on a global basis are described. Soil moisture affects both crop growth and the dielectric properties of the soil, and can be quantified by analysis of reflected radiance passively received by orbiting spacecraft. A dedicated satellite reading a swath 200 km across, with 1 km and 1 K temperature resolution, could track the time-varying changes of solid moisture, sea ice, and water surface temperature. Launched by the Shuttle into an interim orbit, a boost would place the satellite in a 400 or 700 km orbit. Resolution requirements indicate a 45-725 m diam antenna, with 70 dB gain, operating at frequencies of 1.08, 2.03, and 4.95 GHz to ensure atmospheric transparency. Alternative structural concepts include either double-layer tetrahedral or single-layer geodesic trusses as the basic structural members. An analysis of the electrostatic positioning of the parabolic antenna membrane is outlined.

Analytical study of the effects of clouds on the light produced by lightning

NASA Technical Reports Server (NTRS)

Phanord, Dieudonne D.

1990-01-01

Researchers consider the scattering of visible and infrared light due to lightning by cubic, cylindrical and spherical clouds. The researchers extend to cloud physics the work by Twersky for single and multiple scattering of electromagnetic waves. They solve the interior problem separately to obtain the bulk parameters for the scatterer equivalent to the ensemble of spherical droplets. With the interior solution or the equivalent medium approach, the multiple scattering problem is reduced to that of a single scatterer in isolation. Hence, the computing methods of Wiscombe or Bohren specialized to Mie scattering with the possibility for absorption were used to generate numerical results in short computer time.

Changes in accommodation and ocular aberration with simultaneous vision multifocal contact lenses.

PubMed

Ruiz-Alcocer, Javier; Madrid-Costa, David; Radhakrishnan, Hema; Ferrer-Blasco, Teresa; Montés-Micó, Robert

2012-09-01

The aim of this study was to evaluate ocular aberration changes through different simultaneous vision multifocal contact lenses (CLs). Eighteen young-adult subjects with a mean age of 29.8±2.11 years took part. Changes in accommodative response, spherical aberration (C(4)(0)), horizontal coma (C(3)(1)), vertical coma (C(3)(-1)), and root mean square (RMS) of higher-order aberrations (HOAs, third to sixth orders) were evaluated. Measurements were obtained with a distance-single vision CL and 2 aspheric multifocal CLs of simultaneous focus center-near design (PureVision Low Add and PureVision High Add) for 2 accommodative stimuli (-2.50 and -4.00 D). All measurements were performed monocularly with a Hartmann-Shack aberrometer (IRX-3; Imagine Eyes, Orsay, France). No statistically significant differences were found in accommodative responses to -2.50- and -4.00-D stimuli between the single vision CL and the 2 multifocal CLs. Spherical aberration was found to decrease and become more negative with accommodation for both stimuli with all three CLs. Horizontal coma decreased significantly with accommodation (-2.5- and -4.00-D stimuli) for the distance-single vision CLs (P=0.002 and P=0.003). No differences were found in vertical coma Zernike coefficients. The RMS of HOAs was found to decrease only with the single vision CLs for both stimuli (P<0.01). Data obtained in this study suggest that in young subjects, the multifocal CLs studied do not induce large changes in accommodative response compared with the distance-single vision CLs. Spherical aberration reduced significantly with accommodation.

Spherical demons: fast diffeomorphic landmark-free surface registration.

PubMed

Yeo, B T Thomas; Sabuncu, Mert R; Vercauteren, Tom; Ayache, Nicholas; Fischl, Bruce; Golland, Polina

2010-03-01

We present the Spherical Demons algorithm for registering two spherical images. By exploiting spherical vector spline interpolation theory, we show that a large class of regularizors for the modified Demons objective function can be efficiently approximated on the sphere using iterative smoothing. Based on one parameter subgroups of diffeomorphisms, the resulting registration is diffeomorphic and fast. The Spherical Demons algorithm can also be modified to register a given spherical image to a probabilistic atlas. We demonstrate two variants of the algorithm corresponding to warping the atlas or warping the subject. Registration of a cortical surface mesh to an atlas mesh, both with more than 160 k nodes requires less than 5 min when warping the atlas and less than 3 min when warping the subject on a Xeon 3.2 GHz single processor machine. This is comparable to the fastest nondiffeomorphic landmark-free surface registration algorithms. Furthermore, the accuracy of our method compares favorably to the popular FreeSurfer registration algorithm. We validate the technique in two different applications that use registration to transfer segmentation labels onto a new image 1) parcellation of in vivo cortical surfaces and 2) Brodmann area localization in ex vivo cortical surfaces.

Spherical Demons: Fast Diffeomorphic Landmark-Free Surface Registration

PubMed Central

Yeo, B.T. Thomas; Sabuncu, Mert R.; Vercauteren, Tom; Ayache, Nicholas; Fischl, Bruce; Golland, Polina

2010-01-01

We present the Spherical Demons algorithm for registering two spherical images. By exploiting spherical vector spline interpolation theory, we show that a large class of regularizors for the modified Demons objective function can be efficiently approximated on the sphere using iterative smoothing. Based on one parameter subgroups of diffeomorphisms, the resulting registration is diffeomorphic and fast. The Spherical Demons algorithm can also be modified to register a given spherical image to a probabilistic atlas. We demonstrate two variants of the algorithm corresponding to warping the atlas or warping the subject. Registration of a cortical surface mesh to an atlas mesh, both with more than 160k nodes requires less than 5 minutes when warping the atlas and less than 3 minutes when warping the subject on a Xeon 3.2GHz single processor machine. This is comparable to the fastest non-diffeomorphic landmark-free surface registration algorithms. Furthermore, the accuracy of our method compares favorably to the popular FreeSurfer registration algorithm. We validate the technique in two different applications that use registration to transfer segmentation labels onto a new image: (1) parcellation of in-vivo cortical surfaces and (2) Brodmann area localization in ex-vivo cortical surfaces. PMID:19709963

Influence of gravity on foams

NASA Astrophysics Data System (ADS)

Monnereau, C.; Vignes-Adler, M.; Kronberg, B.

1999-06-01

The feasibility of experiments on the physics of foams in microgravity environment was investigated during a parabolic flight campaign. Transient foams from surfactant-free organic liquids and stable foams from a soapy solution of a Sodium Dodecyl Sulfate + Dodecanol mixture were investigated. In 0g, the transient foam is stabilized; whatever the liquid the foam bubbles are spherical and their diameter does not change during the flight. When the gravity constant is equal to 1.8 g, the bubbles of the stable foam become polyhedral and numerous topological transformations could be observed. La faisabilité d'expériences permettant d'étudier la physique de la mousse en microgravité a été démontrée au cours de vols paraboliques. Nous avons testé des mousses de liquides organiques sans tensioactif qui sont éphémères dans le champ terrestre, et des mousses à base d'une solution aqueuse d'un mélange de Dodécyl Sulfate de Sodium et de Dodécanol qui sont au contraire très stables. En microgravité, les mousses éphémères sont stabilisées; quel que soit le liquide, les bulles sont sphériques et leur diamètre reste égal à leur valeur initiale. Lorsqu'au cours de la parabole, la gravité devient égale à 1,8 g, les bulles de la mousse stable dont les films sont très rigides prennent une forme polyédrique ; de très nombreuses transformations topologiques de type T1 ont pu alors être observées.

Ground Fluidization Promotes Rapid Running of a Lightweight Robot

DTIC Science & Technology

2013-01-01

SCMs ) (Wood et al., 2008) have enabled the development of small, lightweight robots (∼ 10 cm, ∼ 20 g) (Hoover et al., 2010; Birkmeyer et al., 2009) such...communicated to the controller through a Bluetooth wireless interface. 2.1.2. Model granular media We used 3.0±0.2 mm diam- eter glass particles (density

Efficacy of three insecticides applied to bark to control Agrilus planipennis (Coleoptera: Buprestidae)

Treesearch

Toby R. Petrice; Robert A. Haack

2006-01-01

Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a serious exotic pest of ash (Fraxinus) trees in North America. In 2003 and 2004, we tested the efficacy of different insecticides sprayed on the bark of cut ash logs for killing emerging EAB adults. Logs (means: length = 30 cm; diam. = 16 cm) were...

Behavioral Effects of Low Doses of Cholinesterase Inhibitors in Robot- Tested Marmosets

DTIC Science & Technology

1989-10-01

animals, which had been reared at the PC- TNO. Two were rejected soon; one because it did not like the marshmallow -like reward, the other because it...wells, each containing a little (diam. approx. 5 mm) marshmallow -like reward, sucks one reward onto the end of the tube and moves the reward into the

High Peak Power Ka-Band Gyrotron Oscillator Experiment.

DTIC Science & Technology

1987-09-21

edge of a 3.44-cm- diam. cylindrical carbon cathode by means of explosive plasma formation. The diode is immersed in the field of the main solenoidal... Prosnitz Dr. T.J. Orzechowski C ’ ’ Dr. J. Thase 56 ’V Los Alamos Scientific Laboratory P.O. Box 1663, AT5-827 Los Alamos, New Mexico 87545 Attn

Generating high-quality single droplets for optical particle characterization with an easy setup

NASA Astrophysics Data System (ADS)

Xu, Jie; Ge, Baozhen; Meng, Rui

2018-06-01

The high-performance and micro-sized single droplet is significant for optical particle characterization. We develop a single-droplet generator (SDG) based on a piezoelectric inkjet technique with advantages of low cost and easy setup. By optimizing the pulse parameters, we achieve various size single droplets. Further investigations reveal that SDG generates single droplets of high quality, demonstrating good sphericity, monodispersity and a stable length of several millimeters.

Surface Structure Spread Single Crystals (S4C): Preparation and characterization

NASA Astrophysics Data System (ADS)

de Alwis, A.; Holsclaw, B.; Pushkarev, V. V.; Reinicker, A.; Lawton, T. J.; Blecher, M. E.; Sykes, E. C. H.; Gellman, A. J.

2013-02-01

A set of six spherically curved Cu single crystals referred to as Surface Structure Spread Single Crystals (S4Cs) has been prepared in such a way that their exposed surfaces collectively span all possible crystallographic surface orientations that can be cleaved from the face centered cubic Cu lattice. The method for preparing these S4Cs and for finding the high symmetry pole point is described. Optical profilometry has been used to determine the true shapes of the S4Cs and show that over the majority of the surface, the shape is extremely close to that of a perfect sphere. The local orientations of the surfaces lie within ± 1° of the orientation expected on the basis of the spherical shape; their orientation is as good as that of many commercially prepared single crystals. STM imaging has been used to characterize the atomic level structure of the Cu(111) ± 11°-S4C. This has shown that the average step densities and the average step orientations match those expected based on the spherical shape. In other words, although there is some distribution of step-step spacing and step orientations, there is no evidence of large scale reconstruction or faceting. The Cu S4Cs have local structures based on the ideal termination of the face centered cubic Cu lattice in the direction of termination. The set of Cu S4Cs will serve as the basis for high throughput investigations of structure sensitive surface chemistry on Cu.

A high excitation magnetic quadrupole lens quadruplet incorporating a single octupole lens for a low spherical aberration probe forming lens system

NASA Astrophysics Data System (ADS)

Dou, Yanxin; Jamieson, David N.; Liu, Jianli; Li, Liyi

2018-03-01

This paper describes the design of a new probe forming lens system consisting of a high excitation magnetic quadrupole lens quadruplet that incorporates a single magnetic octupole lens. This system achieves both a high demagnification and a low spherical aberration compared to conventional high excitation systems and is intended for deployment for the Harbin 300 MeV proton microprobe for applications in space science and ion beam therapy. This relative simplicity of the ion optical design to include a single octupole lens minimizes the risks associated with the constructional and operational precision usually needed for the probe forming lens system and this system could also be deployed in microprobe systems that operate with less magnetically rigid ions. The design of the new system is validated with reference to two independent ion optical computer codes.

Single-mode Rayleigh-Taylor growth-rate measurements with the OMEGA laser system

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

Knauer, J. P.; Verdon, C. P.; Meyerhofer, D. D.

1997-04-15

The results from a series of single-mode Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five to six 351-nm laser beams overlapped with total intensities up to 2.5x10{sup 14} W/cm{sup 2}. Experiments were performed with both 3-ns ramp and 3-ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600-{mu}m-diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measuredmore » using through-foil radiography and was detected with an x-ray framing camera for CH targets with and without a foam buffer. The growth of both 31-{mu}m and 60-{mu}m wavelength perturbations was found to be in good agreement with ORCHID simulations when the experimental details, including noise, were included. The addition of a 30-mg/cc, 100-{mu}m-thick polystyrene foam buffer layer resulted in reduced growth of the 31-{mu}m perturbation and essentially unchanged growth for the 60-{mu}m case when compared to targets without foam.« less

Underwater auditory localization by a swimming harbor seal (Phoca vitulina).

PubMed

Bodson, Anais; Miersch, Lars; Mauck, Bjoern; Dehnhardt, Guido

2006-09-01

The underwater sound localization acuity of a swimming harbor seal (Phoca vitulina) was measured in the horizontal plane at 13 different positions. The stimulus was either a double sound (two 6-kHz pure tones lasting 0.5 s separated by an interval of 0.2 s) or a single continuous sound of 1.2 s. Testing was conducted in a 10-m-diam underwater half circle arena with hidden loudspeakers installed at the exterior perimeter. The animal was trained to swim along the diameter of the half circle and to change its course towards the sound source as soon as the signal was given. The seal indicated the sound source by touching its assumed position at the board of the half circle. The deviation of the seals choice from the actual sound source was measured by means of video analysis. In trials with the double sound the seal localized the sound sources with a mean deviation of 2.8 degrees and in trials with the single sound with a mean deviation of 4.5 degrees. In a second experiment minimum audible angles of the stationary animal were found to be 9.8 degrees in front and 9.7 degrees in the back of the seal's head.

Acoustical tweezers using single spherically focused piston, X-cut, and Gaussian beams.

PubMed

Mitri, Farid G

2015-10-01

Partial-wave series expansions (PWSEs) satisfying the Helmholtz equation in spherical coordinates are derived for circular spherically focused piston (i.e., apodized by a uniform velocity amplitude normal to its surface), X-cut (i.e., apodized by a velocity amplitude parallel to the axis of wave propagation), and Gaussian (i.e., apodized by a Gaussian distribution of the velocity amplitude) beams. The Rayleigh-Sommerfeld diffraction integral and the addition theorems for the Legendre and spherical wave functions are used to obtain the PWSEs assuming weakly focused beams (with focusing angle α ⩽ 20°) in the Fresnel-Kirchhoff (parabolic) approximation. In contrast with previous analytical models, the derived expressions allow computing the scattering and acoustic radiation force from a sphere of radius a without restriction to either the Rayleigh (a ≪ λ, where λ is the wavelength of the incident radiation) or the ray acoustics (a ≫λ) regimes. The analytical formulations are valid for wavelengths largely exceeding the radius of the focused acoustic radiator, when the viscosity of the surrounding fluid can be neglected, and when the sphere is translated along the axis of wave propagation. Computational results illustrate the analysis with particular emphasis on the sphere's elastic properties and the axial distance to the center of the concave surface, with close connection of the emergence of negative trapping forces. Potential applications are in single-beam acoustical tweezers, acoustic levitation, and particle manipulation.

Notes and Discussion

ERIC Educational Resources Information Center

American Journal of Physics, 1978

1978-01-01

Describes experiments demonstrating the Josephson effect, single-file diffusion in biological membranes, refractive index of beer, lines of magnetic fields, indexing diffraction patterns, Maxwell's equations, and spherical aberration. (SL)

Nucleic Acid-Based Nanoconstructs

Cancer.gov

Focuses on the design, synthesis, characterization, and development of spherical nucleic acid constructs as effective nanotherapeutic, single-entity agents for the treatment of glioblastoma multiforme and prostate cancers.

Functionalized patchy particles using colloidal lenses

NASA Astrophysics Data System (ADS)

Middleton, Christine

2014-03-01

Colloidal assembly had been limited by the isotropic, nonspecific nature of interactions between spherical colloidal particles. By giving particles patches functionalized with single stranded DNA, these interactions can be made both directional and specific. We create patchy particles by adding patches to spherical emulsion droplets using the depletion interaction. First we make polystyrene particles in the shape of contact lenses to be the patches. The lenses are functionalized with single stranded DNA on their convex side. Then we put the lenses on the surface of oil emulsion droplets using the depletion interaction, creating a patch (or multiple patches) on the surface of each emulsion droplet. The emulsion droplets can now interact with each other in a specific, directional way through DNA functionalized patches.

Circular dichroism in photo-single-ionization of unoriented atoms.

PubMed

Feagin, James M

2002-01-28

We predict circular dichroism in photo-single-ionization angular distributions from spherically symmetric atomic states if the ionized electron is detected using two-slit interferometry. We demonstrate that the resulting electron interference pattern captures phase information on quadrupole corrections to the photoionization amplitude lost in conventional angular distributions.

Diurnal roosts of male evening bats (Nycticeius humeralis) in diversely managed pine-hardwood forests

Treesearch

Roger W. Perry; Ronald E. Thill

2008-01-01

We examined attributes of 45 roost sites used by 17 adult male evening bats (Nycticeius humeralis) in a diverse forested landscape within the Ouachita Mountains, Arkansas. Bats roosted in a diverse array of substrates, including live or dead Pinus echinata $15 cm diam at breast height (29% of roosts) and small (,10 cm) understory or midstory...

Wind energy converter GROWIAN 2

NASA Astrophysics Data System (ADS)

Braun, D.; Kloeppel, V.; Marsch, G.; Meggle, R.; Mehlhose, R.; Schoebe, B.; Wennekers, R.

1984-04-01

Multi MW wind energy conversion systems in the rotor class of 135 m diam are described. A variable-speed horizontal-axis downwind machine with a one-bladed teetering rotor and a guyed soft steel tower was investigated and a 1 to 3 scaled demonstrator with a rotor diameter of 48 m was built. The demonstrator will undergo a 2 year verification test program.

Improving Understanding of the Fate and Transport of Munitions Constituents to Enhance Sustainability of Operational Ranges

DTIC Science & Technology

2015-05-01

with a 0.45 µm Millipore Durapore PVDF (polyvinylidene fluoride) filter (13 mm diam.) in a Luer filter holder attached to a stainless steel Luer...were recorded. All extractions were performed in a fume hood. DI water (5 mL) was added to each of the test tubes containing supernatant and the new

Low Threshold Voltage Continuous Wave Vertical-Cavity Surface-Emitting Lasers

DTIC Science & Technology

1993-04-26

Data are presented demonstrating a design and fabrication process for the realization of low- threshold , high-output vertical-cavity surface-emitting...layers), the low series resistance of the design results in a bias voltage on o 1.8 V at a threshold current of 1.9 mA for 10-micrometer-diam devices.... Vertical-cavity surface-emitting lasers.

Spherically Actuated Motor

NASA Technical Reports Server (NTRS)

Peeples, Steven

2015-01-01

A three degree of freedom (DOF) spherical actuator is proposed that will replace functions requiring three single DOF actuators in robotic manipulators providing space and weight savings while reducing the overall failure rate. Exploration satellites, Space Station payload manipulators, and rovers requiring pan, tilt, and rotate movements need an actuator for each function. Not only does each actuator introduce additional failure modes and require bulky mechanical gimbals, each contains many moving parts, decreasing mean time to failure. A conventional robotic manipulator is shown in figure 1. Spherical motors perform all three actuation functions, i.e., three DOF, with only one moving part. Given a standard three actuator system whose actuators have a given failure rate compared to a spherical motor with an equal failure rate, the three actuator system is three times as likely to fail over the latter. The Jet Propulsion Laboratory reliability studies of NASA robotic spacecraft have shown that mechanical hardware/mechanism failures are more frequent and more likely to significantly affect mission success than are electronic failures. Unfortunately, previously designed spherical motors have been unable to provide the performance needed by space missions. This inadequacy is also why they are unavailable commercially. An improved patentable spherically actuated motor (SAM) is proposed to provide the performance and versatility required by NASA missions.

Energy gain calculations in spherical IEC fusion systems using the BAFP code

NASA Astrophysics Data System (ADS)

Chacón, L.; Miley, G. H.; Barnes, D. C.; Knoll, D. A.

1999-11-01

The spherical IEC fusion concept takes advantage of the potential well generated by an inner spherical cathode (physical or virtual), biased negatively to several kV with respect to a concentric outer grounded boundary, to focus ions inwards and form a dense central core where fusion may occur. However, defocusing of the ion beams due to ion-ion collisions may prevent a satisfactory energy balance in the system. This research concentrates of spherically symmetric virtual cathode IEC devices, in which a spherical cloud of electrons, confined á la Penning trap, creates the ion-confining electrostatic well. A bounce-averaged Fokker-Planck model has been constructed to analyze the ion physics in ideal conditions (i.e., spherically uniform electrostatic well, no collisional interaction between ions and electrons, single ion species).(L. Chacon, D. C. Barnes, D. A. Knoll, 40^th) Annual Meeting of the APS Division of Plasma Physics, New Orleans, LA, Nov. 1998 Results will reproduce the phenomenology of previously published( W. Nevins, Phys. Plasmas), 2(10), 3804-3819 (1995) theoretical limits, and will show that, under some conditions, steady-state solutions with relatively high gains and small ion recirculation powers exist for the bounce-averaged Fokker-Planck transport equation. Variations in gain with parameter space will be presented.

Numerical relativity in spherical coordinates with the Einstein Toolkit

NASA Astrophysics Data System (ADS)

Mewes, Vassilios; Zlochower, Yosef; Campanelli, Manuela; Ruchlin, Ian; Etienne, Zachariah B.; Baumgarte, Thomas W.

2018-04-01

Numerical relativity codes that do not make assumptions on spatial symmetries most commonly adopt Cartesian coordinates. While these coordinates have many attractive features, spherical coordinates are much better suited to take advantage of approximate symmetries in a number of astrophysical objects, including single stars, black holes, and accretion disks. While the appearance of coordinate singularities often spoils numerical relativity simulations in spherical coordinates, especially in the absence of any symmetry assumptions, it has recently been demonstrated that these problems can be avoided if the coordinate singularities are handled analytically. This is possible with the help of a reference-metric version of the Baumgarte-Shapiro-Shibata-Nakamura formulation together with a proper rescaling of tensorial quantities. In this paper we report on an implementation of this formalism in the Einstein Toolkit. We adapt the Einstein Toolkit infrastructure, originally designed for Cartesian coordinates, to handle spherical coordinates, by providing appropriate boundary conditions at both inner and outer boundaries. We perform numerical simulations for a disturbed Kerr black hole, extract the gravitational wave signal, and demonstrate that the noise in these signals is orders of magnitude smaller when computed on spherical grids rather than Cartesian grids. With the public release of our new Einstein Toolkit thorns, our methods for numerical relativity in spherical coordinates will become available to the entire numerical relativity community.

Diamond Smoothing Tools

NASA Technical Reports Server (NTRS)

Voronov, Oleg

2007-01-01

Diamond smoothing tools have been proposed for use in conjunction with diamond cutting tools that are used in many finish-machining operations. Diamond machining (including finishing) is often used, for example, in fabrication of precise metal mirrors. A diamond smoothing tool according to the proposal would have a smooth spherical surface. For a given finish machining operation, the smoothing tool would be mounted next to the cutting tool. The smoothing tool would slide on the machined surface left behind by the cutting tool, plastically deforming the surface material and thereby reducing the roughness of the surface, closing microcracks and otherwise generally reducing or eliminating microscopic surface and subsurface defects, and increasing the microhardness of the surface layer. It has been estimated that if smoothing tools of this type were used in conjunction with cutting tools on sufficiently precise lathes, it would be possible to reduce the roughness of machined surfaces to as little as 3 nm. A tool according to the proposal would consist of a smoothing insert in a metal holder. The smoothing insert would be made from a diamond/metal functionally graded composite rod preform, which, in turn, would be made by sintering together a bulk single-crystal or polycrystalline diamond, a diamond powder, and a metallic alloy at high pressure. To form the spherical smoothing tip, the diamond end of the preform would be subjected to flat grinding, conical grinding, spherical grinding using diamond wheels, and finally spherical polishing and/or buffing using diamond powders. If the diamond were a single crystal, then it would be crystallographically oriented, relative to the machining motion, to minimize its wear and maximize its hardness. Spherically polished diamonds could also be useful for purposes other than smoothing in finish machining: They would likely also be suitable for use as heat-resistant, wear-resistant, unlubricated sliding-fit bearing inserts.

Evaluation of Motor Gasoline Stability

DTIC Science & Technology

1990-12-01

CAMPINNE AIR POLLUTION CONTROL I LABORATOIRE MECANIQUE TRANSPORT 2565 PLYMOUTH ROAD AVENUE DE LA RENAISSANCE, 3D ANN ARBOR MI 48105 B-1040 BRUSSELS 5...CUARTEL GENERAL DEL EJERCITO ATTN: MR K LAURINSEN ATTN: MAJ M ENGO NOGUES GADHOLTVEJ 11 DIVISION DE LOGISTICA (DIAM/LABCAMVE) DK-9900 FREDERIKSHAVN...Gum for Typical Civilian Gasolines Transported by CEPS and F-46 Gasolines Stored by CEPS ...................................... 47 B. Potential Gum

Endocytosis of wheat germ agglutinin binding sites from the cell surface into a tubular endosomal network.

PubMed

Raub, T J; Koroly, M J; Roberts, R M

1990-04-01

By using fluorescence and electron microscopy, the endocytic pathway encountered by cell surface components after they had bound wheat germ agglutinin (WGA) was visualized. The majority of these components are thought to consist of sialylated glycoproteins (HMWAG) that represent a subpopulation of the total cell surface proteins but most of the externally disposed plasma membrane proteins of the cell. Examination of semi-thin sections by medium- and high-voltage electron microscopy revealed the three-dimensional organization of vesicular and tubular endosomes. Binding of either fluorescein isothiocyanate-, horseradish peroxidase-, or ferritin-conjugated WGA to cells at 4 degrees C showed that the HMWAG were distributed uniformly over the cell surface. Warming of surface-labeled cells to 37 degrees C resulted in the endocytosis of WGA into peripheral endosomes via invagination of regions of both coated and uncoated membrane. The peripheral endosome appeared as isolated complexes comprising a vesicular element (300-400 nm diam.) surrounded by and continuous with tubular cisternae (45-60 nm diam.), which did not interconnect the endosomes. After 30 min or more label also became localized in a network of anastomosing tubules (45-60 nm diam.) that were located in the centrosomal region of the cell. Endocytosed WGA-HMWAG complexes did not become associated with cisternae of the Golgi apparatus, although tubular and vesicular endosomes were noted in the vicinity of the trans-Golgi region. The accumulation of WGA-HMWAG in the endosomes within the centrosomal region was inhibited when cells were incubated at 18 degrees C. None of these compartments contained acid phosphatase activity, a result that is consistent with other data that the HMWAG do not pass through lysosomes initially. The kinetics of labeling were consistent with the interpretation that recycling of most of the WGA binding surface glycoproteins occurred rapidly from early peripheral endosomes followed by the late trans-Golgi compartment. In conclusion, a portion of cell surface glycoproteins are routed to a complex arrangement of tubular and vesicular compartments following endocytosis that includes a putative post-endosomal, tubular reticulum that appears to be separate from the trans-most Golgi saccule.

Convolutional Neural Network-Based Robot Navigation Using Uncalibrated Spherical Images †

PubMed Central

Ran, Lingyan; Zhang, Yanning; Zhang, Qilin; Yang, Tao

2017-01-01

Vision-based mobile robot navigation is a vibrant area of research with numerous algorithms having been developed, the vast majority of which either belong to the scene-oriented simultaneous localization and mapping (SLAM) or fall into the category of robot-oriented lane-detection/trajectory tracking. These methods suffer from high computational cost and require stringent labelling and calibration efforts. To address these challenges, this paper proposes a lightweight robot navigation framework based purely on uncalibrated spherical images. To simplify the orientation estimation, path prediction and improve computational efficiency, the navigation problem is decomposed into a series of classification tasks. To mitigate the adverse effects of insufficient negative samples in the “navigation via classification” task, we introduce the spherical camera for scene capturing, which enables 360° fisheye panorama as training samples and generation of sufficient positive and negative heading directions. The classification is implemented as an end-to-end Convolutional Neural Network (CNN), trained on our proposed Spherical-Navi image dataset, whose category labels can be efficiently collected. This CNN is capable of predicting potential path directions with high confidence levels based on a single, uncalibrated spherical image. Experimental results demonstrate that the proposed framework outperforms competing ones in realistic applications. PMID:28604624

Convolutional Neural Network-Based Robot Navigation Using Uncalibrated Spherical Images.

PubMed

Ran, Lingyan; Zhang, Yanning; Zhang, Qilin; Yang, Tao

2017-06-12

Vision-based mobile robot navigation is a vibrant area of research with numerous algorithms having been developed, the vast majority of which either belong to the scene-oriented simultaneous localization and mapping (SLAM) or fall into the category of robot-oriented lane-detection/trajectory tracking. These methods suffer from high computational cost and require stringent labelling and calibration efforts. To address these challenges, this paper proposes a lightweight robot navigation framework based purely on uncalibrated spherical images. To simplify the orientation estimation, path prediction and improve computational efficiency, the navigation problem is decomposed into a series of classification tasks. To mitigate the adverse effects of insufficient negative samples in the "navigation via classification" task, we introduce the spherical camera for scene capturing, which enables 360° fisheye panorama as training samples and generation of sufficient positive and negative heading directions. The classification is implemented as an end-to-end Convolutional Neural Network (CNN), trained on our proposed Spherical-Navi image dataset, whose category labels can be efficiently collected. This CNN is capable of predicting potential path directions with high confidence levels based on a single, uncalibrated spherical image. Experimental results demonstrate that the proposed framework outperforms competing ones in realistic applications.

Automated semi-spherical irradiance meter

NASA Astrophysics Data System (ADS)

Tecpoyotl-Torres, M.; Vera-Dimas, J. G.; Escobedo-Alatorre, J.; Cabello-Ruiz, R.; Varona, J.

2011-09-01

In this semi-spherical meter, a single detector is used to realize all measurements, which is located on the extreme of a rectangular ring (assumed as joined two mobile branches in order to compensate the weights), describing half-meridians from 0° up to 170°. The illumination source under test is located at the center of the mobile support, which can rotate 360° horizontally. The two combined movements allow us to obtain a semi-spherical geometry. The number of measurement points is determined by the two step-motors located under the mobile support of the luminary and on one of the two fixed arms, which support the mobile rectangular ring, respectively. The mechanical arrangement has the enough rigidity to support the precision required for the acquisition stage, based on a dsPIC. The main advantages of this arrange are: Its low costs (using recyclable materials only such as "electronic waste"), a reliable detection based on a single photo-detector, with an integrated amplification stage, and the mechanical design. The received power by the detector is useful to obtain the irradiance profile of the lighting sources under test. The semi-spherical geometry of the meter makes it useful for the analysis of directive and non directive sources, in accordance with the angle described by the mobile ring. In this work, special attention is given to LED lamps due to its impact in several sceneries of the daily life. A comparison between the irradiance patterns of two LED lamps is also given.

Temperature dependence of magnetoresistance in copper single crystals

NASA Astrophysics Data System (ADS)

Bian, Q.; Niewczas, M.

2018-03-01

Transverse magnetoresistance of copper single crystals has been measured in the orientation of open-orbit from 2 K to 20 K for fields up to 9 T. The experimental Kohler's plots display deviation between individual curves below 16 K and overlap in the range of 16 K-20 K. The violation of the Kohler's rule below 16 K indicates that the magnetotransport can not be described by the classical theory of electron transport on spherical Fermi surface with a single relaxation time. A theoretical model incorporating two energy bands, spherical and cylindrical, with different relaxation times has been developed to describe the magnetoresistance data. The calculations show that the electron-phonon scattering rates at belly and neck regions of the Fermi surface have different temperature dependencies, and in general, they do not follow T3 law. The ratio of the relaxation times in belly and neck regions decreases parabolically with temperature as A - CT2 , with A and C being constants.

On capturing the grain-scale elastic and plastic anisotropy of alpha-Ti with spherical nanoindentation and electron back-scattered diffraction

DOE PAGES

Weaver, Jordan S.; Priddy, Matthew W.; McDowell, David L.; ...

2016-09-01

Here, spherical nanoindentation combined with electron back-scattered diffraction has been employed to characterize the grain-scale elastic and plastic anisotropy of single crystal alpha-Ti of two different compositions (in two different titanium alloys). Data analyses protocols needed to reliably extract the desired properties of interest are extended and demonstrated in this paper. Specifically, the grain-scale mechanical response is extracted in the form of indentation stress-strain curves for commercially pure (CP-Ti) alpha-Ti and alloyed (Ti-64) titanium from measurements on polycrystalline samples. The results are compared with responses of single crystals and nanoindentation tests (hardness and modulus) from the literature, and the measuredmore » indentation moduli are validated using crystal-elastic finite element simulations. The results obtained in this study show that (i) it is possible to characterize reliably the elastic and plastic anisotropy of alpha-Ti (hcp) of varying alloying contents with spherical nanoindentation stress-strain curves, (ii) the indentation modulus of alpha-Ti-64 is 5–10% less than CP-Ti, and (iii) the indentation yield strength of alpha-Ti-64 is 50–80% higher than CP-Ti.« less

Weakly nonlinear incompressible Rayleigh-Taylor instability in spherical geometry

NASA Astrophysics Data System (ADS)

Zhang, J.; Wang, L. F.; Ye, W. H.; Wu, J. F.; Guo, H. Y.; Zhang, W. Y.; He, X. T.

2017-06-01

In this research, a weakly nonlinear (WN) model for the incompressible Rayleigh-Taylor instability in cylindrical geometry [Wang et al., Phys. Plasmas 20, 042708 (2013)] is generalized to spherical geometry. The evolution of the interface with an initial small-amplitude single-mode perturbation in the form of Legendre mode (Pn) is analysed with the third-order WN solutions. The transition of the small-amplitude perturbed spherical interface to the bubble-and-spike structure can be observed by our model. For single-mode perturbation Pn, besides the generation of P 2 n and P 3 n , which are similar to the second and third harmonics in planar and cylindrical geometries, many other modes in the range of P0- P 3 n are generated by mode-coupling effects up to the third order. With the same initial amplitude, the bubbles at the pole grow faster than those at the equator in the WN regime. Furthermore, it is found that the behavior of the bubbles at the pole is similar to that of three-dimensional axisymmetric bubbles, while the behavior of the bubbles at the equator is similar to that of two-dimensional bubbles.

Variation in PTCHD2, CRISP3, NAP1L4, FSCB, and AP3B2 associated with spherical equivalent.

PubMed

Chen, Fei; Duggal, Priya; Klein, Barbara E K; Lee, Kristine E; Truitt, Barbara; Klein, Ronald; Iyengar, Sudha K; Klein, Alison P

2016-01-01

Ocular refraction is measured in spherical equivalent as the power of the external lens required to focus images on the retina. Myopia (nearsightedness) and hyperopia (farsightedness) are the most common refractive errors, and the leading causes of visual impairment and blindness in the world. The goal of this study is to identify rare and low-frequency variants that influence spherical equivalent. We conducted variant-level and gene-level quantitative trait association analyses for mean spherical equivalent, using data from 1,560 individuals in the Beaver Dam Eye Study. Genotyping was conducted using the Illumina exome array. We analyzed 34,976 single nucleotide variants and 11,571 autosomal genes across the genome, using single-variant tests as well as gene-based tests. Spherical equivalent was significantly associated with five genes in gene-based analysis: PTCHD2 at 1p36.22 (p = 3.6 × 10(-7)), CRISP3 at 6p12.3 (p = 4.3 × 10(-6)), NAP1L4 at 11p15.5 (p = 3.6 × 10(-6)), FSCB at 14q21.2 (p = 1.5 × 10(-7)), and AP3B2 at 15q25.2 (p = 1.6 × 10(-7)). The variant-based tests identified evidence suggestive of association with two novel variants in linkage disequilibrium (pairwise r(2) = 0.80) in the TCTE1 gene region at 6p21.1 (rs2297336, minor allele frequency (MAF) = 14.1%, β = -0.62 p = 3.7 × 10(-6); rs324146, MAF = 16.9%, β = -0.55, p = 1.4 × 10(-5)). In addition to these novel findings, we successfully replicated a previously reported association with rs634990 near GJD2 at 15q14 (MAF = 47%, β = -0.29, p=1.8 × 10(-3)). We also found evidence of association with spherical equivalent on 2q37.1 in PRSS56 at rs1550094 (MAF = 31%, β = -0.33, p = 1.7 × 10(-3)), a region previously associated with myopia. We identified several novel candidate genes that may play a role in the control of spherical equivalent. However, further studies are needed to replicate these findings. In addition, our results contribute to the increasing evidence that variation in the GJD2 and PRSS56 genes influence the development of refractive errors. Identifying that variation in these genes is associated with spherical equivalent may provide further insight into the etiology of myopia and consequent vision loss.

A new species of Myxozoa, Henneguya rondoni n. sp. (Myxozoa), from the peripheral nervous system of the Amazonian fish, Gymnorhamphichthys rondoni (Teleostei).

PubMed

Azevedo, Carlos; Casal, Graça; Matos, Patricia; Matos, Edilson

2008-01-01

Henneguya rondoni n. sp. found in the peripheral lateral nerves located below the two lateral lines of the fish Gymnorhamphichthys rondoni (Teleostei, Rhamphichthyidae) from the Amazon river is described using light and electron microscopy. Spherical to ellipsoid cysts measuring up to 110 microm in length contained only immature and mature spores located in close contact with the myelin sheaths of the nervous fibres. Ellipsoidal spores measured 17.7 (16.9-18.1)-microm long, 3.6 (3.0-3.9)-microm wide, and 2.5 (2.2-2.8)-microm (n=25) thick. The spore body measuring 7.0 (6.8-7.3)-microm long was formed by two equal symmetric valves, each with an equal tapering tail 10.7 (10.3-11.0) microm in length. The tails were composed of an internal dense material surrounded by an external homogeneous sheath of hyaline substance. The valves surrounded two equal pyriform polar capsules measuring 2.5 (2.2-2.8)-microm long and 0.85 (0.79-0.88)-microm (n=25) wide and a binucleated sporoplasm cell containing globular sporoplasmosomes 0.38 (0.33-0.42) microm (n=25) in diam. with an internal eccentric dense structure with half-crescent section. Each polar capsule contains an anisofilar polar filament with 6-7 turns obliquely to the long axis. The matrix of the polar capsule was dense and the wall filled with a hyaline substance. The spores differed from those of previously described species. Based on the ultrastructural morphology of the spore and specificity to the host species, we propose a new species name H. rondoni n. sp.

Fabrication of a glancing-angle-deposited distributed polarization rotator for ultraviolet applications

DOE PAGES

Oliver, James B.; Smith, Chris; Spaulding, John; ...

2018-06-05

Glancing-angle–deposited thin films are used to fabricate half-wave plates in a 1-D striped geometry, forming alternating regions of linearly polarized light on a single 100-mm-diam substrate. MgO is selected for fabricating the birefringent films for use in vacuum, based on its formation of isolated columns that avoid potential tensile-stress failure of the porous film. While large-area tests have shown high defect densities for fluences <10 J/cm 2, small-spot laser-damage testing has shown resistance to fluences up to 30 J/cm 2 (351-nm, 5-ns pulse). Here, an amorphous silica film is investigated to match the optical thickness in the intermediate regions inmore » an effort to fabricate a polarization-control device to reduce focal-point modulation (“beam smoothing”) in high-intensity laser systems. Ongoing efforts to improve the laser-damage threshold and minimize optical losses caused by scatter are essential to realizing a practical device. Scalability of the process to meter-scale substrates is also explored.« less

Design and implementation of fiber-based multiphoton endoscopy with microelectromechanical systems scanning

PubMed Central

Tang, Shuo; Jung, Woonggyu; McCormick, Daniel; Xie, Tuqiang; Su, Jiangping; Ahn, Yeh-Chan; Tromberg, Bruce J.; Chen, Zhongping

2010-01-01

A multiphoton endoscopy system has been developed using a two-axis microelectromechanical systems (MEMS) mirror and double-cladding photonic crystal fiber (DCPCF). The MEMS mirror has a 2-mm-diam, 20-deg optical scanning angle, and 1.26-kHz and 780-Hz resonance frequencies on the x and y axes. The maximum number of resolvable focal spots of the MEMS scanner is 720×720 on the x and y axes, which indicates that the MEMS scanner can potentially support high-resolution multiphoton imaging. The DCPCF is compared with standard single-mode fiber and hollow-core photonic bandgap fiber on the basis of dispersion, attenuation, and coupling efficiency properties. The DCPCF has high collection efficiency, and its dispersion can be compensated by grating pairs. Three configurations of probe design are investigated, and their imaging quality and field of view are compared. A two-lens configuration with a collimation and a focusing lens provides the optimum imaging performance and packaging flexibility. The endoscope is applied to image fluorescent microspheres and bovine knee joint cartilage. PMID:19566298

Nonaerodynamic sabot stripper for research gas gun

NASA Astrophysics Data System (ADS)

Mock, W., Jr.; Holt, W. H.

1994-07-01

A nonaerodynamic sabot stripper has been designed and implemented for use with a 40.00-mm smooth bore research gas gun. The stripper consists of several metal parts to stop and contain the sabot while allowing the carried object to pass unhindered through it. The single-piece sabot is stopped by impacting replaceable layers of 19-mm-thick aluminum and steel plates and 3.2-mm-thick rubber sheets. The metal plates and rubber sheets have 25.4- and 31.8-mm diam holes, respectively, for passage of the carried object. The sabot stripper is located 230 mm from the muzzle of the gas gun and is aligned before each shot using a special metal fixture that is inserted into the gun muzzle. Cubes measuring 12.7 mm have been launched in a flat-faced orientation. Targets consisting of 76.2 mm×76.2 mm plates of various thicknesses are positioned in an assembly that attaches to the sabot stripper and is located 57 mm behind it. The velocity range for the experiments was from 0.61 to 0.94 km/s.

Fabrication of a glancing-angle-deposited distributed polarization rotator for ultraviolet applications

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

Oliver, James B.; Smith, Chris; Spaulding, John

Glancing-angle–deposited thin films are used to fabricate half-wave plates in a 1-D striped geometry, forming alternating regions of linearly polarized light on a single 100-mm-diam substrate. MgO is selected for fabricating the birefringent films for use in vacuum, based on its formation of isolated columns that avoid potential tensile-stress failure of the porous film. While large-area tests have shown high defect densities for fluences <10 J/cm 2, small-spot laser-damage testing has shown resistance to fluences up to 30 J/cm 2 (351-nm, 5-ns pulse). Here, an amorphous silica film is investigated to match the optical thickness in the intermediate regions inmore » an effort to fabricate a polarization-control device to reduce focal-point modulation (“beam smoothing”) in high-intensity laser systems. Ongoing efforts to improve the laser-damage threshold and minimize optical losses caused by scatter are essential to realizing a practical device. Scalability of the process to meter-scale substrates is also explored.« less

SIRTF primary mirror design, analysis, and testing

NASA Technical Reports Server (NTRS)

Sarver, George L., III; Maa, Scott; Chang, LI

1990-01-01

The primary mirror assembly (PMA) requirements and concepts for the Space Infrared Telescope Facility (SIRTF) program are discussed. The PMA studies at NASA/ARC resulted in the design of two engineering test articles, the development of a mirror mount cryogenic static load testing system, and the procurement and partial testing of a full scale spherical mirror mounting system. Preliminary analysis and testing of the single arch mirror with conical mount design and the structured mirror with the spherical mount design indicate that the designs will meet all figure and environmental requirements of the SIRTF program.

Computer Program for Analysis of High Speed, Single Row, Angular Contact, Spherical Roller Bearing, SASHBEAN. Volume 2: Mathematical Formulation and Analysis

DTIC Science & Technology

1993-09-01

conformity of roller and raceway spherical crowns, while lending the bearing its self -aligning and high load capacity, also results in relative sliding...thus in the negative direction. A positive axial load, acting along the X-axis is also shown in Figure 1. Due to the self -aligning ability of a...34Pubdic irevmln bude tI thui cftlction of mntorniaton e =-mtmiaed to =,..iage 1 hour per respose . incuding the tme for rewiwng Insruc.tions

Magnetic rotational hysteresis study on spherical 85-160 nm Fe3O4 particles

NASA Astrophysics Data System (ADS)

Schmidbauer, E.

1988-05-01

Rotational hysteresis losses Wr were determined as a function of magnetic field H for dispensed spherical Fe3O4 particles of mean grain sizes 85 nm, 127 nm and 162 nm between 78 K and 294 K. The observed Wr-H curves are compared with theoretical curves for single domain particles. The analysed particles reveal centers of high magnetic anisotropy. Such centers can be of importance during the generation of a thermoremanent magnetization, as they may be the origin of enhanced magnetic stability.

Space Chambers Contamination Diagnostics and Analysis

DTIC Science & Technology

1990-12-01

been used to detect organic gases surrounding the fibers via molecular absorption of the IR evanescent wave that penetrates the region near the...necessary to make measurements on multiple sample plates simultaneously, and for this reason fiber optics would have to be used to deliver laser radiation...tm-diam fused silica fiber with approximately 200-/an core diameter . Assuming a practical operating length of 30 m for the fibers , a transmission of

A Study into Advanced Guidance Laws Using Computational Methods

DTIC Science & Technology

2011-12-01

0; for ii = 2:index integral = integral+(t(ii)-t(ii-1))*u2(ii-1); end J = 20*min(range)^2+integral/1000; 73 outtxt = [’Time (s...0.67*LN; % nose CP XCPW = LN+XW+0.7*CRW-0.2*CTW; % wing CP AN = 0.67*LN*DIAM...0.5*(LENGTH-LN)))/(AN+AB); % body CP %--- Area computations ------------------------------------- SW = 0.5*HW*(CTW+CRW)+CRW*WXT; % wing

Center for Development of Security Excellence (CDSE) 2013 Year End Report

DTIC Science & Technology

2013-01-01

Humphrey Deputy Director, CDSE CDSE STATEMENT Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc bibendum dapibus dui, at porta nunc. In eget...accumsan odio. Donec rutrum varius purus, vitae venenatis urna porttitor eget. Mauris lorem dolor , facilisis eget purus quis, adipiscing tincidunt...ac quam at gravida. Cras a ligula suscipit, lobortis dolor vel, feugiat diam. Proin mattis lectus sit amet pellentesque interdum. Cras porttitor

Porcine skin visible lesion thresholds for near-infrared lasers including modeling at two pulse durations and spot sizes.

PubMed

Cain, C P; Polhamus, G D; Roach, W P; Stolarski, D J; Schuster, K J; Stockton, K L; Rockwell, B A; Chen, Bo; Welch, A J

2006-01-01

With the advent of such systems as the airborne laser and advanced tactical laser, high-energy lasers that use 1315-nm wavelengths in the near-infrared band will soon present a new laser safety challenge to armed forces and civilian populations. Experiments in nonhuman primates using this wavelength have demonstrated a range of ocular injuries, including corneal, lenticular, and retinal lesions as a function of pulse duration. American National Standards Institute (ANSI) laser safety standards have traditionally been based on experimental data, and there is scant data for this wavelength. We are reporting minimum visible lesion (MVL) threshold measurements using a porcine skin model for two different pulse durations and spot sizes for this wavelength. We also compare our measurements to results from our model based on the heat transfer equation and rate process equation, together with actual temperature measurements on the skin surface using a high-speed infrared camera. Our MVL-ED50 thresholds for long pulses (350 micros) at 24-h postexposure are measured to be 99 and 83 J cm(-2) for spot sizes of 0.7 and 1.3 mm diam, respectively. Q-switched laser pulses of 50 ns have a lower threshold of 11 J cm(-2) for a 5-mm-diam top-hat laser pulse.

Parameterization of single-scattering properties of snow

NASA Astrophysics Data System (ADS)

Räisänen, P.; Kokhanovsky, A.; Guyot, G.; Jourdan, O.; Nousiainen, T.

2015-02-01

Snow consists of non-spherical grains of various shapes and sizes. Still, in many radiative transfer applications, single-scattering properties of snow have been based on the assumption of spherical grains. More recently, second-generation Koch fractals have been employed. While they produce a relatively flat phase function typical of deformed non-spherical particles, this is still a rather ad-hoc choice. Here, angular scattering measurements for blowing snow conducted during the CLimate IMpacts of Short-Lived pollutants In the Polar region (CLIMSLIP) campaign at Ny Ålesund, Svalbard, are used to construct a reference phase function for snow. Based on this phase function, an optimized habit combination (OHC) consisting of severely rough (SR) droxtals, aggregates of SR plates and strongly distorted Koch fractals is selected. The single-scattering properties of snow are then computed for the OHC as a function of wavelength λ and snow grain volume-to-projected area equivalent radius rvp. Parameterization equations are developed for λ = 0.199-2.7 μm and rvp = 10-2000 μm, which express the single-scattering co-albedo β, the asymmetry parameter g and the phase function P11 as functions of the size parameter and the real and imaginary parts of the refractive index. The parameterizations are analytic and simple to use in radiative transfer models. Compared to the reference values computed for the OHC, the accuracy of the parameterization is very high for β and g. This is also true for the phase function parameterization, except for strongly absorbing cases (β > 0.3). Finally, we consider snow albedo and reflected radiances for the suggested snow optics parameterization, making comparisons to spheres and distorted Koch fractals.

Parameterization of single-scattering properties of snow

NASA Astrophysics Data System (ADS)

Räisänen, P.; Kokhanovsky, A.; Guyot, G.; Jourdan, O.; Nousiainen, T.

2015-06-01

Snow consists of non-spherical grains of various shapes and sizes. Still, in many radiative transfer applications, single-scattering properties of snow have been based on the assumption of spherical grains. More recently, second-generation Koch fractals have been employed. While they produce a relatively flat phase function typical of deformed non-spherical particles, this is still a rather ad hoc choice. Here, angular scattering measurements for blowing snow conducted during the CLimate IMpacts of Short-Lived pollutants In the Polar region (CLIMSLIP) campaign at Ny Ålesund, Svalbard, are used to construct a reference phase function for snow. Based on this phase function, an optimized habit combination (OHC) consisting of severely rough (SR) droxtals, aggregates of SR plates and strongly distorted Koch fractals is selected. The single-scattering properties of snow are then computed for the OHC as a function of wavelength λ and snow grain volume-to-projected area equivalent radius rvp. Parameterization equations are developed for λ = 0.199-2.7 μm and rvp = 10-2000 μm, which express the single-scattering co-albedo β, the asymmetry parameter g and the phase function P11 as functions of the size parameter and the real and imaginary parts of the refractive index. The parameterizations are analytic and simple to use in radiative transfer models. Compared to the reference values computed for the OHC, the accuracy of the parameterization is very high for β and g. This is also true for the phase function parameterization, except for strongly absorbing cases (β > 0.3). Finally, we consider snow albedo and reflected radiances for the suggested snow optics parameterization, making comparisons to spheres and distorted Koch fractals.

The Five-Hundred Aperture Spherical Radio Telescope (fast) Project

NASA Astrophysics Data System (ADS)

Nan, Rendong; Li, Di; Jin, Chengjin; Wang, Qiming; Zhu, Lichun; Zhu, Wenbai; Zhang, Haiyan; Yue, Youling; Qian, Lei

Five-hundred-meter Aperture Spherical radio Telescope (FAST) is a Chinese mega-science project to build the largest single dish radio telescope in the world. Its innovative engineering concept and design pave a new road to realize a huge single dish in the most effective way. FAST also represents Chinese contribution in the international efforts to build the square kilometer array (SKA). Being the most sensitive single dish radio telescope, FAST will enable astronomers to jump-start many science goals, such as surveying the neutral hydrogen in the Milky Way and other galaxies, detecting faint pulsars, looking for the first shining stars, hearing the possible signals from other civilizations, etc. The idea of sitting a large spherical dish in a karst depression is rooted in Arecibo telescope. FAST is an Arecibo-type antenna with three outstanding aspects: the karst depression used as the site, which is large to host the 500-meter telescope and deep to allow a zenith angle of 40 degrees; the active main reflector correcting for spherical aberration on the ground to achieve a full polarization and a wide band without involving complex feed systems; and the light-weight feed cabin driven by cables and servomechanism plus a parallel robot as a secondary adjustable system to move with high precision. The feasibility studies for FAST have been carried out for 14 years, supported by Chinese and world astronomical communities. Funding for FAST has been approved by the National Development and Reform Commission in July of 2007 with a capital budget ~ 700 million RMB. The project time is 5.5 years from the commencement of work in March of 2011 and the first light is expected to be in 2016. This review intends to introduce the project of FAST with emphasis on the recent progress since 2006. In this paper, the subsystems of FAST are described in modest details followed by discussions of the fundamental science goals and examples of early science projects.

Single-mode Rayleigh-Taylor growth-rate measurements with the OMEGA laser system

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

Knauer, J.P.; Verdon, C.P.; Meyerhofer, D.D.

1997-04-01

The results from a series of single-mode Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five to six 351-nm laser beams overlapped with total intensities up to 2.5{times}10{sup 14}W/cm{sup 2}. Experiments were performed with both 3-ns ramp and 3-ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4{percent}{endash}7{percent} over a 600-{mu}m-diam region defined by the 90{percent} intensity contour. The temporal growth of the modulation in optical depth was measured usingmore » through-foil radiography and was detected with an x-ray framing camera for CH targets with and without a foam buffer. The growth of both 31-{mu}m and 60-{mu}m wavelength perturbations was found to be in good agreement with {ital ORCHID} simulations when the experimental details, including noise, were included. The addition of a 30-mg/cc, 100-{mu}m-thick polystyrene foam buffer layer resulted in reduced growth of the 31-{mu}m perturbation and essentially unchanged growth for the 60-{mu}m case when compared to targets without foam. {copyright} {ital 1997 American Institute of Physics.}« less

Electro-optic spatial decoding on the spherical-wavefront Coulomb fields of plasma electron sources.

PubMed

Huang, K; Esirkepov, T; Koga, J K; Kotaki, H; Mori, M; Hayashi, Y; Nakanii, N; Bulanov, S V; Kando, M

2018-02-13

Detections of the pulse durations and arrival timings of relativistic electron beams are important issues in accelerator physics. Electro-optic diagnostics on the Coulomb fields of electron beams have the advantages of single shot and non-destructive characteristics. We present a study of introducing the electro-optic spatial decoding technique to laser wakefield acceleration. By placing an electro-optic crystal very close to a gas target, we discovered that the Coulomb field of the electron beam possessed a spherical wavefront and was inconsistent with the previously widely used model. The field structure was demonstrated by experimental measurement, analytic calculations and simulations. A temporal mapping relationship with generality was derived in a geometry where the signals had spherical wavefronts. This study could be helpful for the applications of electro-optic diagnostics in laser plasma acceleration experiments.

Spherical space Bessel-Legendre-Fourier localized modes solver for electromagnetic waves.

PubMed

Alzahrani, Mohammed A; Gauthier, Robert C

2015-10-05

Maxwell's vector wave equations are solved for dielectric configurations that match the symmetry of a spherical computational domain. The electric or magnetic field components and the inverse of the dielectric profile are series expansion defined using basis functions composed of the lowest order spherical Bessel function, polar angle single index dependant Legendre polynomials and azimuthal complex exponential (BLF). The series expressions and non-traditional form of the basis functions result in an eigenvalue matrix formulation of Maxwell's equations that are relatively compact and accurately solvable on a desktop PC. The BLF matrix returns the frequencies and field profiles for steady states modes. The key steps leading to the matrix populating expressions are provided. The validity of the numerical technique is confirmed by comparing the results of computations to those published using complementary techniques.

Coherent backscattering of light by complex random media of spherical scatterers: numerical solution

NASA Astrophysics Data System (ADS)

Muinonen, Karri

2004-07-01

Novel Monte Carlo techniques are described for the computation of reflection coefficient matrices for multiple scattering of light in plane-parallel random media of spherical scatterers. The present multiple scattering theory is composed of coherent backscattering and radiative transfer. In the radiative transfer part, the Stokes parameters of light escaping from the medium are updated at each scattering process in predefined angles of emergence. The scattering directions at each process are randomized using probability densities for the polar and azimuthal scattering angles: the former angle is generated using the single-scattering phase function, whereafter the latter follows from Kepler's equation. For spherical scatterers in the Rayleigh regime, randomization proceeds semi-analytically whereas, beyond that regime, cubic spline presentation of the scattering matrix is used for numerical computations. In the coherent backscattering part, the reciprocity of electromagnetic waves in the backscattering direction allows the renormalization of the reversely propagating waves, whereafter the scattering characteristics are computed in other directions. High orders of scattering (~10 000) can be treated because of the peculiar polarization characteristics of the reverse wave: after a number of scatterings, the polarization state of the reverse wave becomes independent of that of the incident wave, that is, it becomes fully dictated by the scatterings at the end of the reverse path. The coherent backscattering part depends on the single-scattering albedo in a non-monotonous way, the most pronounced signatures showing up for absorbing scatterers. The numerical results compare favourably to the literature results for nonabsorbing spherical scatterers both in and beyond the Rayleigh regime.

Optical properties of non-spherical desert dust particles in the terrestrial infrared - An asymptotic approximation approach

NASA Astrophysics Data System (ADS)

Klüser, Lars; Di Biagio, Claudia; Kleiber, Paul D.; Formenti, Paola; Grassian, Vicki H.

2016-07-01

Optical properties (extinction efficiency, single scattering albedo, asymmetry parameter and scattering phase function) of five different desert dust minerals have been calculated with an asymptotic approximation approach (AAA) for non-spherical particles. The AAA method combines Rayleigh-limit approximations with an asymptotic geometric optics solution in a simple and straightforward formulation. The simulated extinction spectra have been compared with classical Lorenz-Mie calculations as well as with laboratory measurements of dust extinction. This comparison has been done for single minerals and with bulk dust samples collected from desert environments. It is shown that the non-spherical asymptotic approximation improves the spectral extinction pattern, including position of the extinction peaks, compared to the Lorenz-Mie calculations for spherical particles. Squared correlation coefficients from the asymptotic approach range from 0.84 to 0.96 for the mineral components whereas the corresponding numbers for Lorenz-Mie simulations range from 0.54 to 0.85. Moreover the blue shift typically found in Lorenz-Mie results is not present in the AAA simulations. The comparison of spectra simulated with the AAA for different shape assumptions suggests that the differences mainly stem from the assumption of the particle shape and not from the formulation of the method itself. It has been shown that the choice of particle shape strongly impacts the quality of the simulations. Additionally, the comparison of simulated extinction spectra with bulk dust measurements indicates that within airborne dust the composition may be inhomogeneous over the range of dust particle sizes, making the calculation of reliable radiative properties of desert dust even more complex.

Single neural adaptive controller and neural network identifier based on PSO algorithm for spherical actuators with 3D magnet array

NASA Astrophysics Data System (ADS)

Yan, Liang; Zhang, Lu; Zhu, Bo; Zhang, Jingying; Jiao, Zongxia

2017-10-01

Permanent magnet spherical actuator (PMSA) is a multi-variable featured and inter-axis coupled nonlinear system, which unavoidably compromises its motion control implementation. Uncertainties such as external load and friction torque of ball bearing and manufacturing errors also influence motion performance significantly. Therefore, the objective of this paper is to propose a controller based on a single neural adaptive (SNA) algorithm and a neural network (NN) identifier optimized with a particle swarm optimization (PSO) algorithm to improve the motion stability of PMSA with three-dimensional magnet arrays. The dynamic model and computed torque model are formulated for the spherical actuator, and a dynamic decoupling control algorithm is developed. By utilizing the global-optimization property of the PSO algorithm, the NN identifier is trained to avoid locally optimal solution and achieve high-precision compensations to uncertainties. The employment of the SNA controller helps to reduce the effect of compensation errors and convert the system to a stable one, even if there is difference between the compensations and uncertainties due to external disturbances. A simulation model is established, and experiments are conducted on the research prototype to validate the proposed control algorithm. The amplitude of the parameter perturbation is set to 5%, 10%, and 15%, respectively. The strong robustness of the proposed hybrid algorithm is validated by the abundant simulation data. It shows that the proposed algorithm can effectively compensate the influence of uncertainties and eliminate the effect of inter-axis couplings of the spherical actuator.

Axial acoustic radiation force on a sphere in Gaussian field

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

Wu, Rongrong; Liu, Xiaozhou, E-mail: xzliu@nju.edu.cn; Gong, Xiufen

2015-10-28

Based on the finite series method, the acoustical radiation force resulting from a Gaussian beam incident on a spherical object is investigated analytically. When the position of the particles deviating from the center of the beam, the Gaussian beam is expanded as a spherical function at the center of the particles and the expanded coefficients of the Gaussian beam is calculated. The analytical expression of the acoustic radiation force on spherical particles deviating from the Gaussian beam center is deduced. The acoustic radiation force affected by the acoustic frequency and the offset distance from the Gaussian beam center is investigated.more » Results have been presented for Gaussian beams with different wavelengths and it has been shown that the interaction of a Gaussian beam with a sphere can result in attractive axial force under specific operational conditions. Results indicate the capability of manipulating and separating spherical spheres based on their mechanical and acoustical properties, the results provided here may provide a theoretical basis for development of single-beam acoustical tweezers.« less

European Science Notes. Volume 39, Number 11.

DTIC Science & Technology

1985-11-01

bacteria is factory by means of a mixed culture of being studied under continuous flow con- bacteria. ditions, especially as it depends on solar radiation...of 300 million operations per contraction chromium layers are plated second and occupying less than a cubic from aqueous solutions by an automated...small as 10 a in diame- tics of additives is needed to determine ter, allowing measurement in layers as their effects on microbial growth. thin as 20

High-Power Pinched-Beam Diode Development for Radiographic Applications

DTIC Science & Technology

2007-06-01

reentrant rods. II. X-RAY DIAGNOSTICS The x-ray dose is measured using CaF2 thermoluminescent dosimeters ( TLDs ) enclosed in 1-cm- diam...1.5-mm spot size. This paper reports on studies of the rod-pinch (RP) diode [3], comprising a small anode rod and an annular cathode. Electrons ...because the electrons impact the rod primarily in the backwards direction. As the voltage increases, the x- radiation becomes more forward-peaked

Collaborative Information Agents on the World Wide Web

NASA Technical Reports Server (NTRS)

Chen, James R.; Mathe, Nathalie; Wolfe, Shawn; Koga, Dennis J. (Technical Monitor)

1998-01-01

In this paper, we present DIAMS, a system of distributed, collaborative information agents which help users access, collect, organize, and exchange information on the World Wide Web. Personal agents provide their owners dynamic displays of well organized information collections, as well as friendly information management utilities. Personal agents exchange information with one another. They also work with other types of information agents such as matchmakers and knowledge experts to facilitate collaboration and communication.

Binocular adaptive optics visual simulator.

PubMed

Fernández, Enrique J; Prieto, Pedro M; Artal, Pablo

2009-09-01

A binocular adaptive optics visual simulator is presented. The instrument allows for measuring and manipulating ocular aberrations of the two eyes simultaneously, while the subject performs visual testing under binocular vision. An important feature of the apparatus consists on the use of a single correcting device and wavefront sensor. Aberrations are controlled by means of a liquid-crystal-on-silicon spatial light modulator, where the two pupils of the subject are projected. Aberrations from the two eyes are measured with a single Hartmann-Shack sensor. As an example of the potential of the apparatus for the study of the impact of the eye's aberrations on binocular vision, results of contrast sensitivity after addition of spherical aberration are presented for one subject. Different binocular combinations of spherical aberration were explored. Results suggest complex binocular interactions in the presence of monochromatic aberrations. The technique and the instrument might contribute to the better understanding of binocular vision and to the search for optimized ophthalmic corrections.

Ternary mixed crystal effects on interface optical phonon and electron-phonon coupling in zinc-blende GaN/AlxGa1-xN spherical quantum dots

NASA Astrophysics Data System (ADS)

Huang, Wen Deng; Chen, Guang De; Yuan, Zhao Lin; Yang, Chuang Hua; Ye, Hong Gang; Wu, Ye Long

2016-02-01

The theoretical investigations of the interface optical phonons, electron-phonon couplings and its ternary mixed effects in zinc-blende spherical quantum dots are obtained by using the dielectric continuum model and modified random-element isodisplacement model. The features of dispersion curves, electron-phonon coupling strengths, and its ternary mixed effects for interface optical phonons in a single zinc-blende GaN/AlxGa1-xN spherical quantum dot are calculated and discussed in detail. The numerical results show that there are three branches of interface optical phonons. One branch exists in low frequency region; another two branches exist in high frequency region. The interface optical phonons with small quantum number l have more important contributions to the electron-phonon interactions. It is also found that ternary mixed effects have important influences on the interface optical phonon properties in a single zinc-blende GaN/AlxGa1-xN quantum dot. With the increase of Al component, the interface optical phonon frequencies appear linear changes, and the electron-phonon coupling strengths appear non-linear changes in high frequency region. But in low frequency region, the frequencies appear non-linear changes, and the electron-phonon coupling strengths appear linear changes.

Preliminary Evaluation of a Commercial 360 Multi-Camera Rig for Photogrammetric Purposes

NASA Astrophysics Data System (ADS)

Teppati Losè, L.; Chiabrando, F.; Spanò, A.

2018-05-01

The research presented in this paper is focused on a preliminary evaluation of a 360 multi-camera rig: the possibilities to use the images acquired by the system in a photogrammetric workflow and for the creation of spherical images are investigated and different tests and analyses are reported. Particular attention is dedicated to different operative approaches for the estimation of the interior orientation parameters of the cameras, both from an operative and theoretical point of view. The consistency of the six cameras that compose the 360 system was in depth analysed adopting a self-calibration approach in a commercial photogrammetric software solution. A 3D calibration field was projected and created, and several topographic measurements were performed in order to have a set of control points to enhance and control the photogrammetric process. The influence of the interior parameters of the six cameras were analyse both in the different phases of the photogrammetric workflow (reprojection errors on the single tie point, dense cloud generation, geometrical description of the surveyed object, etc.), both in the stitching of the different images into a single spherical panorama (some consideration on the influence of the camera parameters on the overall quality of the spherical image are reported also in these section).

A spherical harmonic approach for the determination of HCP texture from ultrasound: A solution to the inverse problem

NASA Astrophysics Data System (ADS)

Lan, Bo; Lowe, Michael J. S.; Dunne, Fionn P. E.

2015-10-01

A new spherical convolution approach has been presented which couples HCP single crystal wave speed (the kernel function) with polycrystal c-axis pole distribution function to give the resultant polycrystal wave speed response. The three functions have been expressed as spherical harmonic expansions thus enabling application of the de-convolution technique to enable any one of the three to be determined from knowledge of the other two. Hence, the forward problem of determination of polycrystal wave speed from knowledge of single crystal wave speed response and the polycrystal pole distribution has been solved for a broad range of experimentally representative HCP polycrystal textures. The technique provides near-perfect representation of the sensitivity of wave speed to polycrystal texture as well as quantitative prediction of polycrystal wave speed. More importantly, a solution to the inverse problem is presented in which texture, as a c-axis distribution function, is determined from knowledge of the kernel function and the polycrystal wave speed response. It has also been explained why it has been widely reported in the literature that only texture coefficients up to 4th degree may be obtained from ultrasonic measurements. Finally, the de-convolution approach presented provides the potential for the measurement of polycrystal texture from ultrasonic wave speed measurements.

Variation in PTCHD2, CRISP3, NAP1L4, FSCB, and AP3B2 associated with spherical equivalent

PubMed Central

Chen, Fei; Duggal, Priya; Klein, Barbara E.K.; Lee, Kristine E.; Truitt, Barbara; Klein, Ronald; Iyengar, Sudha K.

2016-01-01

Purpose Ocular refraction is measured in spherical equivalent as the power of the external lens required to focus images on the retina. Myopia (nearsightedness) and hyperopia (farsightedness) are the most common refractive errors, and the leading causes of visual impairment and blindness in the world. The goal of this study is to identify rare and low-frequency variants that influence spherical equivalent. Methods We conducted variant-level and gene-level quantitative trait association analyses for mean spherical equivalent, using data from 1,560 individuals in the Beaver Dam Eye Study. Genotyping was conducted using the Illumina exome array. We analyzed 34,976 single nucleotide variants and 11,571 autosomal genes across the genome, using single-variant tests as well as gene-based tests. Results Spherical equivalent was significantly associated with five genes in gene-based analysis: PTCHD2 at 1p36.22 (p = 3.6 × 10−7), CRISP3 at 6p12.3 (p = 4.3 × 10−6), NAP1L4 at 11p15.5 (p = 3.6 × 10−6), FSCB at 14q21.2 (p = 1.5 × 10−7), and AP3B2 at 15q25.2 (p = 1.6 × 10−7). The variant-based tests identified evidence suggestive of association with two novel variants in linkage disequilibrium (pairwise r2 = 0.80) in the TCTE1 gene region at 6p21.1 (rs2297336, minor allele frequency (MAF) = 14.1%, β = –0.62 p = 3.7 × 10−6; rs324146, MAF = 16.9%, β = –0.55, p = 1.4 × 10−5). In addition to these novel findings, we successfully replicated a previously reported association with rs634990 near GJD2 at 15q14 (MAF = 47%, β = –0.29, p=1.8 × 10−3). We also found evidence of association with spherical equivalent on 2q37.1 in PRSS56 at rs1550094 (MAF = 31%, β = –0.33, p = 1.7 × 10−3), a region previously associated with myopia. Conclusions We identified several novel candidate genes that may play a role in the control of spherical equivalent. However, further studies are needed to replicate these findings. In addition, our results contribute to the increasing evidence that variation in the GJD2 and PRSS56 genes influence the development of refractive errors. Identifying that variation in these genes is associated with spherical equivalent may provide further insight into the etiology of myopia and consequent vision loss. PMID:27440996

Light scattering and random lasing in aqueous suspensions of hexagonal boron nitride nanoflakes

NASA Astrophysics Data System (ADS)

O'Brien, S. A.; Harvey, A.; Griffin, A.; Donnelly, T.; Mulcahy, D.; Coleman, J. N.; Donegan, J. F.; McCloskey, D.

2017-11-01

Liquid phase exfoliation allows large scale production of 2D materials in solution. The particles are highly anisotropic and strongly scatter light. While spherical particles can be accurately and precisely described by a single parameter—the radius, 2D nanoflakes, however, cannot be so easily described. We investigate light scattering in aqueous solutions of 2D hexagonal boron nitride nanoflakes in the single and multiple scattering regimes. In the single scattering regime, the anisotropic 2D materials show a much stronger depolarization of light when compared to spherical particles of similar size. In the multiple scattering regime, the scattering as a function of optical path for hexagonal boron nitride nanoflakes of a given lateral length was found to be qualitatively equivalent to scattering from spheres with the same diameter. We also report the presence of random lasing in high concentration suspensions of aqueous h-BN mixed with Rhodamine B dye. The h-BN works as a scattering agent and Rhodamine B as a gain medium for the process. We observed random lasing at 587 nm with a threshold energy of 0.8 mJ.

Light scattering and random lasing in aqueous suspensions of hexagonal boron nitride nanoflakes.

PubMed

O'Brien, S A; Harvey, A; Griffin, A; Donnelly, T; Mulcahy, D; Coleman, J N; Donegan, J F; McCloskey, D

2017-11-24

Liquid phase exfoliation allows large scale production of 2D materials in solution. The particles are highly anisotropic and strongly scatter light. While spherical particles can be accurately and precisely described by a single parameter-the radius, 2D nanoflakes, however, cannot be so easily described. We investigate light scattering in aqueous solutions of 2D hexagonal boron nitride nanoflakes in the single and multiple scattering regimes. In the single scattering regime, the anisotropic 2D materials show a much stronger depolarization of light when compared to spherical particles of similar size. In the multiple scattering regime, the scattering as a function of optical path for hexagonal boron nitride nanoflakes of a given lateral length was found to be qualitatively equivalent to scattering from spheres with the same diameter. We also report the presence of random lasing in high concentration suspensions of aqueous h-BN mixed with Rhodamine B dye. The h-BN works as a scattering agent and Rhodamine B as a gain medium for the process. We observed random lasing at 587 nm with a threshold energy of 0.8 mJ.

Whispering gallery modes in photoluminescence and Raman spectra of a spherical microcavity with CdTe quantum dots: anti-Stokes emission and interference effects

PubMed Central

Gaponik, Nikolai; Gerlach, Matthias; Donegan, John F; Savateeva, Diana; Rogach, Andrey L

2006-01-01

We have studied the photoluminescence and Raman spectra of a system consisting of a polystyrene latex microsphere coated by CdTe colloidal quantum dots. The cavity-induced enhancement of the Raman scattering allows the observation of Raman spectra from only a monolayer of CdTe quantum dots. Periodic structure with very narrow peaks in the photoluminescence spectra of a single microsphere was detected both in the Stokes and anti-Stokes spectral regions, arising from the coupling between the emission of quantum dots and spherical cavity modes.

An atlas of Rapp's 180-th order geopotential.

NASA Astrophysics Data System (ADS)

Melvin, P. J.

1986-08-01

Deprit's 1979 approach to the summation of the spherical harmonic expansion of the geopotential has been modified to spherical components and normalized Legendre polynomials. An algorithm has been developed which produces ten fields at the users option: the undulations of the geoid, three anomalous components of the gravity vector, or six components of the Hessian of the geopotential (gravity gradient). The algorithm is stable to high orders in single precision and does not treat the polar regions as a special case. Eleven contour maps of components of the anomalous geopotential on the surface of the ellipsoid are presented to validate the algorithm.

Jetting from impact of a spherical drop with a deep layer

NASA Astrophysics Data System (ADS)

Zhang, Li; Toole, Jameson; Fazzaa, Kamel; Deegan, Robert; Deegan Group Team; X-Ray Science Division, Advanced Photon Source Collaboration

2011-11-01

We performed an experimental study of jets during the impact of a spherical drop with a deep layer of same liquid. Using high speed optical and X-ray imaging, we observe two types of jets: the so-called ejecta sheet which emerges almost immediately after impact and the lamella which emerges later. For high Reynolds number the two jets are distinct, while for low Reynolds number the two jets combine into a single continuous jet. We also measured the emergence time, speed, and position of the ejecta sheet and found simple scaling relations for these quantities.

Wear particles of single-crystal silicon carbide in vacuum

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.

1980-01-01

Sliding friction experiments, conducted in vacuum with silicon carbide /000/ surface in contact with iron based binary alloys are described. Multiangular and spherical wear particles of silicon carbide are observed as a result of multipass sliding. The multiangular particles are produced by primary and secondary cracking of cleavage planes /000/, /10(-1)0/, and /11(-2)0/ under the Hertzian stress field or local inelastic deformation zone. The spherical particles may be produced by two mechanisms: (1) a penny shaped fracture along the circular stress trajectories under the local inelastic deformation zone, and (2) attrition of wear particles.

Combined approach to the Hubble Space Telescope wave-front distortion analysis

NASA Astrophysics Data System (ADS)

Roddier, Claude; Roddier, Francois

1993-06-01

Stellar images taken by the HST at various focus positions have been analyzed to estimate wave-front distortion. Rather than using a single algorithm, we found that better results were obtained by combining the advantages of various algorithms. For the planetary camera, the most accurate algorithms consistently gave a spherical aberration of -0.290-micron rms with a maximum deviation of 0.005 micron. Evidence was found that the spherical aberration is essentially produced by the primary mirror. The illumination in the telescope pupil plane was reconstructed and evidence was found for a slight camera misalignment.

Magnetic field effect on the Coulomb interaction of acceptors in semimagnetic quantum dot

NASA Astrophysics Data System (ADS)

Kalpana, P.; Merwyn, A.; Reuben, Jasper D.; Nithiananthi, P.; Jayakumar, K.

2015-06-01

The Coulomb interaction of holes in a Semimagnetic Cd1-xMnxTe / CdTe Spherical and Cubical Quantum Dot (SMQD) in a magnetic field is studied using variational approach in the effective mass approximation. Since these holes in QD show a pronounced collective behavior, while distinct single particle phenomena is suppressed, their interaction in confined potential becomes very significant. It has been observed that acceptor-acceptor interaction is more in cubical QD than in spherical QD which can be controlled by the magnetic field. The results are presented and discussed.

Ion beam-induced shaping of Ni nanoparticles embedded in a silica matrix: from spherical to prolate shape

PubMed Central

2011-01-01

Present work reports the elongation of spherical Ni nanoparticles (NPs) parallel to each other, due to bombardment with 120 MeV Au+9 ions at a fluence of 5 × 1013 ions/cm2. The Ni NPs embedded in silica matrix have been prepared by atom beam sputtering technique and subsequent annealing. The elongation of Ni NPs due to interaction with Au+9 ions as investigated by cross-sectional transmission electron microscopy (TEM) shows a strong dependence on initial Ni particle size and is explained on the basis of thermal spike model. Irradiation induces a change from single crystalline nature of spherical particles to polycrystalline nature of elongated particles. Magnetization measurements indicate that changes in coercivity (Hc) and remanence ratio (Mr/Ms) are stronger in the ion beam direction due to the preferential easy axis of elongated particles in the beam direction. PMID:21711659

The influence of ozone and aerosols on the brightness and color of the twilight sky

NASA Technical Reports Server (NTRS)

Adams, C. N.; Plass, G. N.; Kattawar, G. W.

1974-01-01

The radiance and color of the twilight sky are calculated for single scattered radiation with the use of spherically symmetric models of the earth's atmosphere. Spherical geometry is used throughout the calculations with no plane-parallel approximations. Refraction effects are taken into account through fine subdivision of the atmosphere into spherical shells of fixed index of refraction. Snell's law of refraction is used to calculate a new direction of travel each time that a photon traverses the interface between layers. Five different models of the atmosphere were used: a pure molecular scattering atmosphere; molecular atmosphere plus ozone absorption; and three models with aerosol concentrations of one, three, and ten times normal together with molecular scattering and ozone absorption. The results of the calculations are shown for various observation positions and local viewing angles in the solar plane for wavelengths in the range from 0.40 to 0.75 micron.

The influence of ozone and aerosols on the brightness and color of the twilight zone

NASA Technical Reports Server (NTRS)

Adams, C. N.; Plass, G. N.; Kattawar, G. W.

1973-01-01

The radiance and color of the twilight sky are calculated for single scattered radiation with the use of spherically symmetric models of the earth's atmosphere. Spherical geometry is used throughout the calculations with no plane parallel approximations. Refraction effects are taken into account through fine subdivision of the atmosphere into spherical shells of fixed index of refraction. Shell's law of refraction is used to calculate a direction of travel each time that a photon traverses the interface between layers. Five different models of the atmosphere were used: a pure molecular scattering atmosphere; molecular atmosphere plus ozone absorption; and three models with aerosol concentrations of 1, 3, and 10 times normal together with molecular scattering and ozone absorption. The results of the calculations are shown for various observation positions and local viewing angles in the solar plane for wavelengths in the range of 0.40 microns to 0.75 microns.

22 CFR 121.1 - General. The United States Munitions List.

Code of Federal Regulations, 2014 CFR

2014-04-01

... standard conditions (as measured in the form of an inhibited single strand) of 6.89 Mpa (68.9 bar) pressure... of 99% or more; (6) Metal fuels in particle form whether spherical, atomized, spheroidal, flaked or...

Retrieval of Aerosol Optical Properties from Ground-Based Remote Sensing Measurements: Aerosol Asymmetry Factor and Single Scattering Albedo

NASA Astrophysics Data System (ADS)

Qie, L.; Li, Z.; Li, L.; Li, K.; Li, D.; Xu, H.

2018-04-01

The Devaux-Vermeulen-Li method (DVL method) is a simple approach to retrieve aerosol optical parameters from the Sun-sky radiance measurements. This study inherited the previous works of retrieving aerosol single scattering albedo (SSA) and scattering phase function, the DVL method was modified to derive aerosol asymmetric factor (g). To assess the algorithm performance at various atmospheric aerosol conditions, retrievals from AERONET observations were implemented, and the results are compared with AERONET official products. The comparison shows that both the DVL SSA and g were well correlated with those of AERONET. The RMSD and the absolute value of MBD deviations between the SSAs are 0.025 and 0.015 respectively, well below the AERONET declared SSA uncertainty of 0.03 for all wavelengths. For asymmetry factor g, the RMSD deviations are smaller than 0.02 and the absolute values of MBDs smaller than 0.01 at 675, 870 and 1020 nm bands. Then, considering several factors probably affecting retrieval quality (i.e. the aerosol optical depth (AOD), the solar zenith angle, and the sky residual error, sphericity proportion and Ångström exponent), the deviations for SSA and g of these two algorithms were calculated at varying value intervals. Both the SSA and g deviations were found decrease with the AOD and the solar zenith angle, and increase with sky residual error. However, the deviations do not show clear sensitivity to the sphericity proportion and Ångström exponent. This indicated that the DVL algorithm is available for both large, non-spherical particles and spherical particles. The DVL results are suitable for the evaluation of aerosol direct radiative effects of different aerosol types.

Application of the Wavy Mechanical Face Seal to Submarine Seal Design.

DTIC Science & Technology

1982-07-01

to Stainless Steel Bond Strength Tests. . . 31 3-1 Seal Design ...... .................... ... 54 3-2 Offset and Tilt Results...primer, Loctite Superbonder 420 with the addi- tion of two stainless steel rings for the inner and outer diam- eter of the carbon insert to give a...near zero clearance fit, and the use of the 3M 1838 B/A epoxy also with the same stainless steel rings. Static and dynamic tests on the seal under water

Environmental Impact Research Program. Osprey Nest Platforms. Section 5.1.6, US Army Corps of Engineers Wildlife Resources Management Manual.

DTIC Science & Technology

1986-07-01

34"x 0treated pole, with 101, olts5" min. top diam. 518"x 7" hardwood dowel,6’O set 1- 112" deep, glued TOP VIEW I r 2’-,9 Some as dinam . of pole usedI I...added strength ; these are described in the section entitled Tripod Support. Pole supports. Two designs are suggested for attaching the solid base

Target Track and Stabilization for Manportable Direct Fire Missiles.

DTIC Science & Technology

1981-11-01

appeared to achieve resonable results, since there is always the possibility that summing weighted scores can be misleading, as was the case with the 1-3...coelostat and variable prism compensation approaches (Appendix, Reference 6) but both suffered from even greater size and complexity problems than approach...8 mm Thick 2 an. Al., Glass, etc. ( ( )Rotating Prisms (Rilley) -30 mm diam x 6 mm Thick 2 ea Germanium. Silicon. Zu On Searn motion ± max requires

Determination de l'échelle dans un micromètre à fils.

NASA Astrophysics Data System (ADS)

Angelo, O. S.

1987-09-01

L'auteur analyse le procédé employé pour déterminer l'échelle du micromètre appliqué au réfracteur, diamètre 150 mm, longueur focale 3000 mm, de l'Observatoire privé E. Dembowski de Polpenazze (Brescia)-Italie. Il pense que cette expérience peut être utile à tous ceux qui voudront se mesurer avec l'observation des étoiles doubles visuelles.

Surface figure changes due to thermal cycling hysteresis.

PubMed

Jacobs, S F; Johnston, S C; Sasian, J M; Watson, M; Targove, J D; Bass, D

1987-10-15

How does thermal cycling hysteresis affect surface figure in low expansivity mirror substrates? Zerodur, ULE, and Cer-Vit 20.3-cm (8-in.) diam mirrors and dilatometer samples were thermally cycled at 6 and 60 K/h with uniform and nonuniform heating. Figure distortions as large as lambda/10 were observed only with nonuniform heating of standard Zerodur, which was the only material exhibiting thermal hysteresis. A new experimental Zerodur appears to be free of this problem.

Rapid portal imaging with a high-efficiency, large field-of-view detector.

PubMed

Mosleh-Shirazi, M A; Evans, P M; Swindell, W; Symonds-Tayler, J R; Webb, S; Partridge, M

1998-12-01

The design, construction, and performance evaluation of an electronic portal imaging device (EPID) are described. The EPID has the same imaging geometry as the current mirror-based systems except for the x-ray detection stage, where a two-dimensional (2D) array of 1 cm thick CsI(Tl) detector elements are utilized. The approximately 18% x-ray quantum efficiency of the scintillation detector and its 30 x 40 cm2 field-of-view at the isocenter are greater than other area-imaging EPIDs. The imaging issues addressed are theoretical and measured signal-to-noise ratio, linearity of the imaging chain, influence of frame-summing on image quality and image calibration. Portal images of test objects and a humanoid phantom are used to measure the performance of the system. An image quality similar to the current devices is achieved but with a lower dose. With approximately 1 cGy dose delivered by a 6 MV beam, a 2 mm diam structure of 1.3% contrast and an 18 mm diam object of 0.125% contrast can be resolved without using image-enhancement methods. A spatial resolution of about 2 mm at the isocenter is demonstrated. The capability of the system to perform fast sequential imaging, synchronized with the radiation pulses, makes it suitable for patient motion studies and verification of intensity-modulated beams as well as its application in cone-beam megavoltage computed tomography.

Effect of particle shape and slip mechanism on buoyancy induced convective heat transport with nanofluids

NASA Astrophysics Data System (ADS)

Joshi, Pranit Satish; Mahapatra, Pallab Sinha; Pattamatta, Arvind

2017-12-01

Experiments and numerical simulation of natural convection heat transfer with nanosuspensions are presented in this work. The investigations are carried out for three different types of nanosuspensions: namely, spherical-based (alumina/water), tubular-based (multi-walled carbon nanotube/water), and flake-based (graphene/water). A comparison with in-house experiments is made for all the three nanosuspensions at different volume fractions and for the Rayleigh numbers in the range of 7 × 105-1 × 107. Different models such as single component homogeneous, single component non-homogeneous, and multicomponent non-homogeneous are used in the present study. From the present numerical investigation, it is observed that for lower volume fractions (˜0.1%) of nanosuspensions considered, single component models are in close agreement with the experimental results. Single component models which are based on the effective properties of the nanosuspensions alone can predict heat transfer characteristics very well within the experimental uncertainty. Whereas for higher volume fractions (˜0.5%), the multi-component model predicts closer results to the experimental observation as it incorporates drag-based slip force which becomes prominent. The enhancement observed at lower volume fractions for non-spherical particles is attributed to the percolation chain formation, which perturbs the boundary layer and thereby increases the local Nusselt number values.

Effects of snow grain shape on climate simulations: sensitivity tests with the Norwegian Earth System Model

NASA Astrophysics Data System (ADS)

Räisänen, Petri; Makkonen, Risto; Kirkevåg, Alf; Debernard, Jens B.

2017-12-01

Snow consists of non-spherical grains of various shapes and sizes. Still, in radiative transfer calculations, snow grains are often treated as spherical. This also applies to the computation of snow albedo in the Snow, Ice, and Aerosol Radiation (SNICAR) model and in the Los Alamos sea ice model, version 4 (CICE4), both of which are employed in the Community Earth System Model and in the Norwegian Earth System Model (NorESM). In this study, we evaluate the effect of snow grain shape on climate simulated by NorESM in a slab ocean configuration of the model. An experiment with spherical snow grains (SPH) is compared with another (NONSPH) in which the snow shortwave single-scattering properties are based on a combination of three non-spherical snow grain shapes optimized using measurements of angular scattering by blowing snow. The key difference between these treatments is that the asymmetry parameter is smaller in the non-spherical case (0.77-0.78 in the visible region) than in the spherical case ( ≈ 0.89). Therefore, for the same effective snow grain size (or equivalently, the same specific projected area), the snow broadband albedo is higher when assuming non-spherical rather than spherical snow grains, typically by 0.02-0.03. Considering the spherical case as the baseline, this results in an instantaneous negative change in net shortwave radiation with a global-mean top-of-the-model value of ca. -0.22 W m-2. Although this global-mean radiative effect is rather modest, the impacts on the climate simulated by NorESM are substantial. The global annual-mean 2 m air temperature in NONSPH is 1.17 K lower than in SPH, with substantially larger differences at high latitudes. The climatic response is amplified by strong snow and sea ice feedbacks. It is further demonstrated that the effect of snow grain shape could be largely offset by adjusting the snow grain size. When assuming non-spherical snow grains with the parameterized grain size increased by ca. 70 %, the climatic differences to the SPH experiment become very small. Finally, the impact of assumed snow grain shape on the radiative effects of absorbing aerosols in snow is discussed.

Half-Lives of Proton Emitters With a Deformed Density-Dependent Model

NASA Astrophysics Data System (ADS)

Qian, Yi-Bin; Ren, Zhong-Zhou; Ni, Dong-Dong; Sheng, Zong-Qiang

2010-11-01

Half-lives of proton radioactivity are investigated with a deformed density-dependent model. The single folding potential which is dependent on deformation and orientation is employed to calculate the proton decay width through the deformed potential barrier. In addition, the spectroscopic factor is taken into account in the calculation, which is obtained in the relativistic mean field theory with NL3. The calculated results of semi-spherical nuclei are found to be in good agreement with the experimental data, and the results of well-deformed nuclei are also satisfactory. Moreover, a formula for the spherical proton emission half-life based on the Gamow quantum tunneling theory is presented.

Crystallization of Deformable Spherical Colloids

NASA Astrophysics Data System (ADS)

Batista, Vera M. O.; Miller, Mark A.

2010-08-01

We introduce and characterize a first-order model for a generic class of colloidal particles that have a preferred spherical shape but can undergo deformations while always maintaining hard-body interactions. The model consists of hard spheres that can continuously change shape at fixed volume into prolate or oblate ellipsoids of revolution, subject to an energetic penalty. The severity of this penalty is specified by a single parameter that determines the flexibility of the particles. The deformable hard spheres crystallize at higher packing fractions than rigid hard spheres, have a narrower solid-fluid coexistence region and can reach high densities by a second transition to an orientationally ordered crystal.

Radiative transfer in spherical shell atmospheres. I - Rayleigh scattering

NASA Technical Reports Server (NTRS)

Adams, C. N.; Kattawar, G. W.

1978-01-01

The plane-parallel approximation and the more realistic spherical shell approximation for the radiance reflected from a planetary atmosphere are compared and are applied to the study of a planet the size of the earth with a homogeneous conservative Rayleigh scattering atmosphere extending to a height of 100 km. Inadequacies of the approximations are considered. Radiance versus height distributions for both single and multiple scattering are presented, as are results for the fractional radiance from altitudes in the atmosphere which contribute to the total unidirectional reflected radiance at the top of the atmosphere. The data can be used for remote sensing applications and planetary spectroscopy.

Curvature-induced capillary interaction of spherical particles at a liquid interface.

PubMed

Würger, Alois

2006-10-01

We consider a liquid interface with different principal curvatures +/-c and find that the mere presence of a spherical particle leads to a deformation field of quadrupolar symmetry; the corresponding "capillary quadrupole moment" is given by the ratio of the particle size and the curvature radius. The resulting pair interaction of nearby particles is anisotropic and favors the formation of aggregates of cubic symmetry. Since the single-particle trapping energy depends quadratically on curvature with a negative prefactor, a curvature gradient induces a lateral force that pushes the particles towards strongly curved regions of the interface. As an illustration we discuss the effects occurring on a catenoid.

Cavity enhanced atomic magnetometry

PubMed Central

Crepaz, Herbert; Ley, Li Yuan; Dumke, Rainer

2015-01-01

Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations. PMID:26481853

Dynamics of an optically confined nanoparticle diffusing normal to a surface.

PubMed

Schein, Perry; O'Dell, Dakota; Erickson, David

2016-06-01

Here we measure the hindered diffusion of an optically confined nanoparticle in the direction normal to a surface, and we use this to determine the particle-surface interaction profile in terms of the absolute height. These studies are performed using the evanescent field of an optically excited single-mode silicon nitride waveguide, where the particle is confined in a height-dependent potential energy well generated from the balance of optical gradient and surface forces. Using a high-speed cmos camera, we demonstrate the ability to capture the short time-scale diffusion dominated motion for 800-nm-diam polystyrene particles, with measurement times of only a few seconds per particle. Using established theory, we show how this information can be used to estimate the equilibrium separation of the particle from the surface. As this measurement can be made simultaneously with equilibrium statistical mechanical measurements of the particle-surface interaction energy landscape, we demonstrate the ability to determine these in terms of the absolute rather than relative separation height. This enables the comparison of potential energy landscapes of particle-surface interactions measured under different experimental conditions, enhancing the utility of this technique.

Scattering (stochastic) recoupling of a coupled ten-stripe AlGaAs-GaAs-InGaAs quantum-well heterostructure laser

NASA Astrophysics Data System (ADS)

Kellogg, D. A.; Holonyak, N.

2001-04-01

Data are presented on coupled ten-stripe AlGaAs-GaAs-InGaAs quantum well heterostructure (QWH) lasers recoupled stochastically at the cleaved end mirrors. Recoupling of neighboring elements of a ten-stripe laser is accomplished by the scattering (random feedback) afforded by applying ˜10-μm-diam Al powder or 0.3 μm α-Al2O3 polishing compound in microscopy immersion oil or in epoxy at the cleaved ends (mirrors). Data on QWH samples with the end mirrors coated with the scatterer (Al or Al2O3 powder in "liquid") exhibit spectral and far-field broadening, as well as increased laser threshold because of the reduced cavity Q. Single mode operation is possible with the conventional evanescent wave coupling of the ten-stripe QWH and is destroyed, even the laser operation itself, with the scattering recoupling (dephasing) at the end mirrors, which is reversible (removable). The narrow ten-stripe QWH laser with strong end-mirror scattering, a long amplifier with random feedback, indicates that a photopumped III-V or II-VI powder (a random "wall" cavity) has little or no merit.

Experimental and theoretical study of Rayleigh-Lamb wave propagation

NASA Technical Reports Server (NTRS)

Rogers, Wayne P.; Datta, Subhendu K.; Ju, T. H.

1990-01-01

Many space structures, such as the Space Station Freedom, contain critical thin-walled components. The structural integrity of thin-walled plates and shells can be monitored effectively using acoustic emission and ultrasonic testing in the Rayleigh-Lamb wave frequency range. A new PVDF piezoelectric sensor has been developed that is well suited to remote, inservice nondestructive evaluation of space structures. In the present study the new sensor was used to investigate Rayleigh-Lamb wave propagation in a plate. The experimental apparatus consisted of a glass plate (2.3 m x 25.4 mm x 5.6 mm) with PVDF sensor (3 mm diam.) mounted at various positions along its length. A steel ball impact served as a simulated acoustic emission source, producing surface waves, shear waves and longitudinal waves with dominant frequencies between 1 kHz and 200 kHz. The experimental time domain wave-forms were compared with theoretical predictions of the wave propagation in the plate. The model uses an analytical solution for the Green's function and the measured response at a single position to predict response at any other position in the plate. Close agreement was found between the experimental and theoretical results.

Electrical and magnetic properties of spherical SmFeO{sub 3} synthesized by aspartic acid assisted combustion method

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

Yuvaraj, Subramanian; Layek, Samar; Vidyavathy, S. Manisha

2015-12-15

Highlights: • SmFeO{sub 3} is synthesized by simple combustion method using aspartic acid as the fuel. • The particles are spherical in shape with the size ranges between 150 and 300 nm. • Cole–Cole plot infers the bulk conduction mechanism. • Room temperature VSM analysis reveal the weak ferromagnetic behaviour of SmFeO{sub 3}. • Mössbauer analysis elucidates the +3 oxidation state of Fe atoms. - Abstract: Samarium orthoferrite (SmFeO{sub 3}) is synthesized by a simple combustion method using aspartic acid as fuel. Phase purity and functional groups are analyzed via X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) analysis, whichmore » confirms the single phase formation of orthorhombic SmFeO{sub 3}. Approximately spherical particles with size range 150–300 nm is revealed by scanning electron microscope (SEM). The conductivity of the material is identified by the single semicircle obtained in the solid state impedance spectra at elevated temperatures. The calculated electrical conductivity increases with increasing temperature, inferring the semiconducting nature of SmFeO{sub 3}. A magnetic study at room temperature revealed weak ferromagnetic behaviour in SmFeO{sub 3} due to Dzyaloshinsky–Moriya antisymmetric exchange interaction mechanism. Mössbauer analysis confirmed the +3 oxidation state of iron and magnetic ordering of the sample at room temperature.« less

Single particle dynamics in a radio-frequency produced plasma sheath

NASA Astrophysics Data System (ADS)

Rubin-Zuzic, M.; Nosenko, V.; Zhdanov, S.; Ivlev, A.; Thomas, H.; Khrapak, S.; Couedel, L.

2018-01-01

Recently different research groups have investigated the motion of a single dust particle levitated in a rf plasma. Here we describe a highly resolved experiment where a single spherical melamine formaldehyde microparticle is suspended in the plasma sheath above the lower electrode of a capacitively coupled radio-frequency discharge at controlled pressure, power and neutral gas flow rate. The particle's horizontal oscillation is investigated, from which its neutral gas damping rate, kinetic temperature and eigenfrequency of the potential trap are measured. Compared to prior experiments we report about inhomogeneous and anisotropic velocity variations.

Too attractive: the growing problem of magnet ingestions in children.

PubMed

Brown, Julie C; Otjen, Jeffrey P; Drugas, George T

2013-11-01

Small, powerful magnets are increasingly available in toys and other products and pose a health risk. Small spherical neodymium magnets marketed since 2008 are of particular concern. The objective of this study was to determine the incidence, characteristics, and management of single and multiple-magnet ingestions over time. Magnet ingestion cases at a tertiary children's hospital were identified using radiology reports from June 2002 to December 2012. Cases were verified by chart and imaging review. Relative risk regressions were used to determine changes in the incidence of ingestions and interventions over time. Of 56 cases of magnet ingestion, 98% occurred in 2006 or later, and 57% involved multiple magnets. Median age was 8 years (range, 0-18 years). Overall, 21% of single and 88% of multiple ingestions had 2 or more imaging series obtained, whereas no single and 56.3% of multiple ingestions required intervention (25.0% endoscopy, 18.8% surgery, 12.5% both). Magnet ingestions increased in 2010 to 2012 compared with 2007 to 2009 (relative risk, 1.9; 95% confidence interval, 1.2-3.0). Small, spherical magnets likely from magnet sets comprised 27% of ingestions, all ingested 2010 or later: 86% involved multiple magnets, 50% of which required intervention. Excluding these cases, ingestions of other magnets did not increase in 2010 to 2012 compared with 2007 to 2009 (relative risk, 0.94; 95% confidence interval, 0.6-1.4). The incidence of pediatric magnet ingestions and subsequent interventions has increased over time. Multiple-magnet ingestions result in high utilization of radiological imaging and surgical interventions. Recent increases parallel the increased availability of small, spherical magnet sets. Young and at-risk children should not have access to these and other small magnets. Improved regulation and magnet safety standards are needed.

Ignition and Combustion Characteristics of Nanoscale Al/AgIO3: A Potential Energetic Biocidal System

DTIC Science & Technology

2011-01-01

the actual particle morphology consists of thin platelets , roughly 1 mm in diam- eter. Silver iodide was purchased from Sigma Aldrich, and the size was...2008), and shows that mixing is limited by clumping of both ingredients. The AgIO3 has a platelet -like morphology, and could potentially mix...in this study is 80 nm from NanoTechnologies. The CuO in this study is 45 nm from Technanogy. Each sample was fuel rich in this study with equivalency

Applicability of Firecracker Welding to Ship Production

DTIC Science & Technology

1975-07-31

minor arc-outages seemed to coincide with defects in-the weld. For example, careful study of the film permitted orientation of such phenomena with the...Sample Electrode Electrode Voltage Current Frames Length weld covered No. Type diam. in. v A per sec. of film ft. in. Polarity 50 7024 1/4 35 240 128...to snuff out the arc. This was especially evident with the E7016 and E7018 electrodes which have a very fluid slag. The molten metal often caused a

Calculation of Containment Concentrations While Coating the Interior of a Bulk Storage Fuel Tank

DTIC Science & Technology

1990-05-01

connection plate Thief-hatch cutout-/ L7J * . Pipe -line connection 22’ B.C. Plan 28 1,15z holes(in top flange 20’ only) 234 1-20-diam dome Vent-line...inside tanks throughout course of work as required to maintain a vapor-free condition. Use exhaust fans, either explosion-proof electrically operated or...provide suction ductwork extending to areas of heaviest concentrations including lowest levels of tank. In no case shall exhaust fan capacity be less than

Cost of Water Distribution System Infrastructure Rehabilitation, Repair, and Replacement.

DTIC Science & Technology

1985-03-01

terms of the Hazen-Williams C-factor. New pipes have C-factors on the order of 140. Severely tuberculated pipes can have C-factors as low as 40. The C... tuberculation , and significantly higher pressures being required to push a pig through a small opening. Unit costs level off above the 10-in. diam and...additional costs of lining. Lining the pipe will: (a) prevent reoccurrence of tuberculation , (b) seal small leaks, and (c) eliminate "red - water" problems

Optical Super-Resolution by High-Index Liquid-Immersed Microspheres

DTIC Science & Technology

2012-01-01

the BD without liquid can be achieved using microspheres with small-to-moderate index of refraction such as borosilicate glass (n 1.47), soda lime ...titanate glass microspheres with diameters (D) in the range 2–220 lm and with high refractive index (n 1.9–2.1) can be used for super-resolution...achieving optical super-resolution. It has been demonstrated10 that silica spheres with refractive index (n) about 1.46 and with diame- ters (D) in the

Fluorescence Spectra of Individual Flowing Airborne Biological Particles Measured in Real Time

DTIC Science & Technology

2001-02-01

and fungal spores ( Aspergillus versicolor, ATCC 9577). B. subtilis var. niger (lyophilized cells) and E. herbicola were grown by streak- ing onto...Excitation Figure 7 shows fluorescence spectra of B. subtilis var. niger vegetative cells and fungal spores ( Aspergillus versicolor), both 5 µm in diameter...µm-diam clusters of B. subtilis var. niger spores, and B. subtilis var. niger vegetative cells ……………………………………… 10 5. Fluorescence spectra of starved

USSR and Eastern Europe Scientific Abstracts Biomedical and Behavioral Sciences No. 61

DTIC Science & Technology

1977-01-05

the bacteria-inhibiting circle was only 10 mm in diam and its activity lasted for only 36-48 hr. In the case of lactic acid treatment , the circle...5.00). Table 1. 1/2 UDC 576.8:636.086.6 USSR SIVERS, V. S. and SPRAVTSEV, M. Kh. MICROBIOLOGICAL TREATMENT OF STRAW BY CELLULOSE-AND LIGNIN... treatment of ponds will lead to annihilation of copepoda-filtrates, the fodder objects for valuable commercial fish fry. Action of 0.05-5.0 mg/1

Dust devils on Mars

NASA Astrophysics Data System (ADS)

Thomas, P.; Gierasch, P. J.

1985-10-01

Viking Orbiter photographic imagery has confirmed the occurrence of dust devils on Mars. The images were of small bright clouds with long, tapered shadows viewed from a nearly-nadir angle. Spectra of the features were consistent with dust and not condensates. A maximum height of 6.8 km and width of 1 km were measured. The dust devils appeared on smooth planes, and had average dimensions of 2 km height and 200 m diam, carrying 3000 kg of dust. The data may be of use in interpreting convective processes on earth.

The Bandini-Cota Adobe, Prado Dam, Riverside County, California.

DTIC Science & Technology

1983-11-01

the South American tree tobacco (Nicotiana glauca) and hummingbirds attracted to the yellow flowers . Previous Studies The most comprehensive...84.2. Diam. approx. 27.0 cm (10.6 in). Scalloped edge with border of baskets of flowers and vines in a "Bar- oque" style on a background of parallel...lines in pale blue (5PB3/4-5/6). Figure 12a. c. Rim sherds, oval platter, 629, 969. Corded edge design, flowers in very fine stippling (5PB4/6-7/6

Developing Systems Engineering Graduate Programs Aligned to the Body of Knowledge and Curriculum to Advance Systems Engineering (BKCASE (trademark)) Guidelines

DTIC Science & Technology

2011-06-01

2011 6 Topic 2 (Article Title) Lorem ipsum dolor sit amet[1], consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore ...consequat. Duis autem vel eum iriure dolor [2] in hendrerit in vulputate velit esse molestie consequat, vel illum dolor eu feugiat nulla facilisis at...vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. Lorem

Non-Negative Spherical Deconvolution (NNSD) for estimation of fiber Orientation Distribution Function in single-/multi-shell diffusion MRI.

PubMed

Cheng, Jian; Deriche, Rachid; Jiang, Tianzi; Shen, Dinggang; Yap, Pew-Thian

2014-11-01

Spherical Deconvolution (SD) is commonly used for estimating fiber Orientation Distribution Functions (fODFs) from diffusion-weighted signals. Existing SD methods can be classified into two categories: 1) Continuous Representation based SD (CR-SD), where typically Spherical Harmonic (SH) representation is used for convenient analytical solutions, and 2) Discrete Representation based SD (DR-SD), where the signal profile is represented by a discrete set of basis functions uniformly oriented on the unit sphere. A feasible fODF should be non-negative and should integrate to unity throughout the unit sphere S(2). However, to our knowledge, most existing SH-based SD methods enforce non-negativity only on discretized points and not the whole continuum of S(2). Maximum Entropy SD (MESD) and Cartesian Tensor Fiber Orientation Distributions (CT-FOD) are the only SD methods that ensure non-negativity throughout the unit sphere. They are however computational intensive and are susceptible to errors caused by numerical spherical integration. Existing SD methods are also known to overestimate the number of fiber directions, especially in regions with low anisotropy. DR-SD introduces additional error in peak detection owing to the angular discretization of the unit sphere. This paper proposes a SD framework, called Non-Negative SD (NNSD), to overcome all the limitations above. NNSD is significantly less susceptible to the false-positive peaks, uses SH representation for efficient analytical spherical deconvolution, and allows accurate peak detection throughout the whole unit sphere. We further show that NNSD and most existing SD methods can be extended to work on multi-shell data by introducing a three-dimensional fiber response function. We evaluated NNSD in comparison with Constrained SD (CSD), a quadratic programming variant of CSD, MESD, and an L1-norm regularized non-negative least-squares DR-SD. Experiments on synthetic and real single-/multi-shell data indicate that NNSD improves estimation performance in terms of mean difference of angles, peak detection consistency, and anisotropy contrast between isotropic and anisotropic regions. Copyright © 2014 Elsevier Inc. All rights reserved.

Geometric relationships for homogenization in single-phase binary alloy systems

NASA Technical Reports Server (NTRS)

Unnam, J.; Tenney, D. R.; Stein, B. A.

1978-01-01

A semiempirical relationship is presented which describes the extent of interaction between constituents in single-phase binary alloy systems having planar, cylindrical, or spherical interfaces. This relationship makes possible a quick estimate of the extent of interaction without lengthy numerical calculations. It includes two parameters which are functions of mean concentration and interface geometry. Experimental data for the copper-nickel system are included to demonstrate the usefulness of this relationship.

Single molecule diffusion and the solution of the spherically symmetric residence time equation.

PubMed

Agmon, Noam

2011-06-16

The residence time of a single dye molecule diffusing within a laser spot is propotional to the total number of photons emitted by it. With this application in mind, we solve the spherically symmetric "residence time equation" (RTE) to obtain the solution for the Laplace transform of the mean residence time (MRT) within a d-dimensional ball, as a function of the initial location of the particle and the observation time. The solutions for initial conditions of potential experimental interest, starting in the center, on the surface or uniformly within the ball, are explicitly presented. Special cases for dimensions 1, 2, and 3 are obtained, which can be Laplace inverted analytically for d = 1 and 3. In addition, the analytic short- and long-time asymptotic behaviors of the MRT are derived and compared with the exact solutions for d = 1, 2, and 3. As a demonstration of the simplification afforded by the RTE, the Appendix obtains the residence time distribution by solving the Feynman-Kac equation, from which the MRT is obtained by differentiation. Single-molecule diffusion experiments could be devised to test the results for the MRT presented in this work. © 2011 American Chemical Society

Theoretical study of symmetry of flux onto a capsule

NASA Astrophysics Data System (ADS)

Duan, Hao; Wu, Changshu; Pei, Wenbing; Zou, Shiyang

2015-09-01

An analytic model to describe the flux asymmetry onto a capsule based on the viewfactor approximation is developed and verified with numerical simulations. By using a nested spheres technique to represent the various sources of flux asymmetry, the model can treat spherically and cylindrically symmetric hohlraums, e.g., cylinder, elliptic, and rugby. This approach includes the more realistic case of frequency-dependent flux asymmetry compared with the more standard frequency-integrated or single-frequency approaches [D. W. Phillion and S. M. Pollaine, Phys. Plasmas 1, 2963 (1994)]. Correspondingly, the approach can be used to assess x-ray preheat asymmetry generated from localized laser absorption in the high-Z hohlraum wall. For spherical hohlraums with 4, 6, or 8 laser entrance holes (LEHs), an optimal configuration of LEHs, laser spot placement, and angle-of-incidence of the single-ringed laser beams is defined. An analogy between minimizing the flux asymmetry onto a capsule and the Thomson problem of point charge placement on a sphere for minimized energy is shown.

Theoretical study of symmetry of flux onto a capsule

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

Duan, Hao; Wu, Changshu; Zou, Shiyang, E-mail: duan-hao@iapcm.ac.cn

2015-09-15

An analytic model to describe the flux asymmetry onto a capsule based on the viewfactor approximation is developed and verified with numerical simulations. By using a nested spheres technique to represent the various sources of flux asymmetry, the model can treat spherically and cylindrically symmetric hohlraums, e.g., cylinder, elliptic, and rugby. This approach includes the more realistic case of frequency-dependent flux asymmetry compared with the more standard frequency-integrated or single-frequency approaches [D. W. Phillion and S. M. Pollaine, Phys. Plasmas 1, 2963 (1994)]. Correspondingly, the approach can be used to assess x-ray preheat asymmetry generated from localized laser absorption inmore » the high-Z hohlraum wall. For spherical hohlraums with 4, 6, or 8 laser entrance holes (LEHs), an optimal configuration of LEHs, laser spot placement, and angle-of-incidence of the single-ringed laser beams is defined. An analogy between minimizing the flux asymmetry onto a capsule and the Thomson problem of point charge placement on a sphere for minimized energy is shown.« less

Formation of a new archetypal Metal-Organic Framework from a simple monatomic liquid

NASA Astrophysics Data System (ADS)

Metere, Alfredo; Oleynikov, Peter; Dzugutov, Mikhail; O'Keeffe, Michael

2014-12-01

We report a molecular-dynamics simulation of a single-component system of particles interacting via a spherically symmetric potential that is found to form, upon cooling from a liquid state, a low-density porous crystalline phase. Its structure analysis demonstrates that the crystal can be described by a net with a topology that belongs to the class of topologies characteristic of the Metal-Organic Frameworks (MOFs). The observed net is new, and it is now included in the Reticular Chemistry Structure Resource database. The observation that a net topology characteristic of MOF crystals, which are known to be formed by a coordination-driven self-assembly process, can be reproduced by a thermodynamically stable configuration of a simple single-component system of particles opens a possibility of using these models in studies of MOF nets. It also indicates that structures with MOF topology, as well as other low-density porous crystalline structures can possibly be produced in colloidal systems of spherical particles, with an appropriate tuning of interparticle interaction.

Does correcting astigmatism with toric lenses improve driving performance?

PubMed

Cox, Daniel J; Banton, Thomas; Record, Steven; Grabman, Jesse H; Hawkins, Ronald J

2015-04-01

Driving is a vision-based activity of daily living that impacts safety. Because visual disruption can compromise driving safety, contact lens wearers with astigmatism may pose a driving safety risk if they experience residual blur from spherical lenses that do not correct their astigmatism or if they experience blur from toric lenses that rotate excessively. Given that toric lens stabilization systems are continually improving, this preliminary study tested the hypothesis that astigmats wearing toric contact lenses, compared with spherical lenses, would exhibit better overall driving performance and driving-specific visual abilities. A within-subject, single-blind, crossover, randomized design was used to evaluate driving performance in 11 young adults with astigmatism (-0.75 to -1.75 diopters cylinder). Each participant drove a highly immersive, virtual reality driving simulator (210 degrees field of view) with (1) no correction, (2) spherical contact lens correction (ACUVUE MOIST), and (3) toric contact lens correction (ACUVUE MOIST for Astigmatism). Tactical driving skills such as steering, speed management, and braking, as well as operational driving abilities such as visual acuity, contrast sensitivity, and foot and arm reaction time, were quantified. There was a main effect for type of correction on driving performance (p = 0.05). Correction with toric lenses resulted in significantly safer tactical driving performance than no correction (p < 0.05), whereas correction with spherical lenses did not differ in driving safety from no correction (p = 0.118). Operational tests differentiated corrected from uncorrected performance for both spherical (p = 0.008) and toric (p = 0.011) lenses, but they were not sensitive enough to differentiate toric from spherical lens conditions. Given previous research showing that deficits in these tactical skills are predictive of future real-world collisions, these preliminary data suggest that correcting low to moderate astigmatism with toric lenses may be important to driving safety. Their merits relative to spherical lens correction require further investigation.

Cavitation studies in microgravity

NASA Astrophysics Data System (ADS)

Kobel, Philippe; Obreschkow, Danail; Farhat, Mohamed; Dorsaz, Nicolas; de Bosset, Aurele

The hydrodynamic cavitation phenomenon is a major source of erosion for many industrial systems such as cryogenic pumps for rocket propulsion, fast ship propellers, hydraulic pipelines and turbines. Erosive processes are associated with liquid jets and shockwaves emission fol-lowing the cavity collapse. Yet, fundamental understanding of these processes requires further cavitation studies inside various geometries of liquid volumes, as the bubble dynamics strongly depends the surrounding pressure field. To this end, microgravity represents a unique platform to produce spherical fluid geometries and remove the hydrostatic pressure gradient induced by gravity. The goal of our first experiment (flown on ESA's parabolic flight campaigns 2005 and 2006) was to study single bubble dynamics inside large spherical water drops (having a radius between 8 and 13 mm) produced in microgravity. The water drops were created by a micro-pump that smoothly expelled the liquid through a custom-designed injector tube. Then, the cavitation bubble was generated through a fast electrical discharge between two electrodes immersed in the liquid from above. High-speed imaging allowed to analyze the implications of isolated finite volumes and spherical free surfaces on bubble evolution, liquid jets formation and shock wave dynamics. Of particular interest are the following results: (A) Bubble lifetimes are shorter than in extended liquid volumes, which could be explain by deriving novel corrective terms to the Rayleigh-Plesset equation. (B) Transient crowds of micro-bubbles (smaller than 1mm) appeared at the instants of shockwaves emission. A comparison between high-speed visualizations and 3D N-particle simulations of a shock front inside a liquid sphere reveals that focus zones within the drop lead to a significantly increased density of induced cavitation. Considering shock wave crossing and focusing may hence prove crucially useful to understand the important process of cavitation erosion. The aim of our future microgravity experiment is to assess the direct effects of gravity on cavitation bubble collapse through a comparison of single cavitation bubbles collapsing in mi-crogravity, normal gravity, and hypergravity. In particular, we shall investigate the shape of the bubble in its final collapse stage and the amount of energy dissipated in the dominant collapse channels, such as liquid jet, shock wave, and rebound bubble. The highly spherical bubbles will be produced via a point-like plasma generated by a high power laser beam. One major hypothesis that we will test is an increase in shock wave energy with decreasing gravity as a consequence of the higher final sphericity and suppression of liquid jets. To support this, we introduce an analytical model for the gravity-perturbed asymmetric collapse of spherical bubbles, and demonstrate that all initially spherical bubbles develop a gravity-related vertical jet along their collapse.

Effects of snow grain non-sphericity on climate simulations: Sensitivity tests with the NorESM model

NASA Astrophysics Data System (ADS)

Räisänen, Petri; Makkonen, Risto; Kirkevåg, Alf

2017-04-01

Snow grains are non-spherical and generally irregular in shape. Still, in radiative transfer calculations, they are often treated as spheres. This also applies to the computation of snow albedo in the Snow, Ice, and Aerosol Radiation (SNICAR) model and in the Los Alamos sea ice model, version 4 (CICE4), both of which are employed in the Community Earth System Model and in the Norwegian Earth System Model (NorESM). In this work, we evaluate the effect of snow grain shape on climate simulated by NorESM in a slab ocean configuration of the model. An experiment with spherical snow grains (SPH) is compared with another (NONSPH) in which the snow shortwave single-scattering properties are based on a combination of non-spherical snow grain shapes optimized using measurements of angular scattering by blowing snow. The key difference between these treatments is that the asymmetry parameter is smaller in the non-spherical case (≈ 0.78 in the visible region) than in the spherical case (≈ 0.89). Therefore, for a given snow grain size, the use of non-spherical snow grains yields a higher snow broadband albedo, typically by ≈0.03. Consequently, considering the spherical case as the baseline, the use of non-spherical snow grains results in a negative radiative forcing (RF), with a global-mean top-of-the-model value of ≈ -0.22 W m-2. Although this global-mean RF is modest, it has a rather substantial impact on the climate simulated by NoRESM. In particular, the global annual-mean 2-m air temperature in NONSPH is 1.17 K lower than in SPH, with substantially larger differences at high latitudes. The climatic response is amplified by strong snow and sea ice feedbacks. It is further found that the difference between NONSPH and SPH could be largely "tuned away" by adjusting the snow grain size in the NONSPH experiment by ≈ 70%. The impact of snow grain shape on the radiative effect (RE) of absorbing aerosols in snow (black carbon and mineral dust) is also discussed. For an optically thick snowpack with a given snow grain effective size, the absorbing aerosol RE is smaller for non-spherical than for spherical snow grains. The reason for this is that due to the lower asymmetry parameter of the non-spherical snow grains, solar radiation does not penetrate as deep in snow as in the case of spherical snow grains. However, in a climate model simulation, the RE is sensitive to patterns of aerosol deposition and simulated snow cover. In fact, the global land-area mean absorbing aerosol RE is larger in the NONSPH than SPH experiment (0.193 vs. 0.168 W m-2), owing to later snowmelt in spring.

Spherical crystallization: A technique use to reform solubility and flow property of active pharmaceutical ingredients.

PubMed

Chatterjee, Arindam; Gupta, Madan Mohan; Srivastava, Birendra

2017-01-01

Tablets have been choice of manufacturers over the years due to their comparatively low cost of manufacturing, packaging, shipping, and ease of administration; also have better stability and can be considered virtually tamper proof. A major challenge in formulation development of the tablets extends from lower solubility of the active agent to the elaborated manufacturing procedures for obtaining a compressible granular material. Moreover, the validation and documentation increases, as the numbers of steps increases for an industrially acceptable granulation process. Spherical crystallization (SC) is a promising technique, which encompass the crystallization, agglomeration, and spheronization phenomenon in a single step. Initially, two methods, spherical agglomeration, and emulsion solvent diffusion, were suggested to get a desired result. Later on, the introduction of modified methods such as crystallo-co-agglomeration, ammonia diffusion system, and neutralization techniques overcame the limitations of the older techniques. Under controlled conditions such as solvent composition, mixing rate and temperature, spherical dense agglomerates cluster from particles. Application of the SC technique includes production of compacted spherical particles of drug having improved uniformity in shape and size of particles, good bulk density, better flow properties as well as better solubility so SC when used on commercial scale will bring down the production costs of pharmaceutical tablet and will increase revenue for the pharmaceutical industries in the competitive market. This review summarizes the technologies available for SC and also suggests the parameters for evaluation of a viable product.

Inversion of the Earth spherical albedo from radiation-pressure

NASA Astrophysics Data System (ADS)

Wilkman, Olli; Herranen, Joonas; Näränen, Jyri; Virtanen, Jenni; Koivula, Hannu; Poutanen, Markku; Penttilä, Antti; Gritsevich, Maria; Muinonen, Karri

2017-04-01

We are studying the retrieval of the spherical albedo and net radiation of the Earth from the perturbations caused by the planet's radiation on the dynamics of its satellites. The spherical or Bond albedo gives the ratio of the fluxes incident on and scattered by the planet. The net radiation represents the net heat input into the planet's climate system and drives changes in its atmospheric, surface, and ocean temperatures. The ultimate aim of the study is inverting the problem and estimating the Earth albedo based on observations of satellites, simultaneously improving the space-geodetic positioning accuracy. Here we investigate the effect of the spherical albedo on satellite orbits with the help of a simplified model. We simulate the propagation of satellite orbits using a new simulation software. The simulation contains the main perturbing forces on medium and high Earth orbits, used by, e.g., navigation satellites, including the radiation pressure of reflected sunlight from the Earth. An arbitrary satellite shape model can be used, and the rotation of the satellite is modeled. In this first study, we use a box-wing satellite model with a simple surface BRDF. We also assume a diffusely reflecting Earth with a single global albedo value. We vary the Earth albedo and search for systematic effects on different orbits. Thereafter, we estimate the dependence of the albedo accuracy on the satellite positioning and timing data available. We show that the inversion of the spherical albedo with reasonable accuracy is feasible from the current space-geodetic measurements.

Single-particle studies of band alignment effects on electron transfer dynamics from semiconductor hetero-nanostructures to single-walled carbon nanotubes.

PubMed

Yuan, Chi-Tsu; Wang, Yong-Gang; Huang, Kuo-Yen; Chen, Ting-Yu; Yu, Pyng; Tang, Jau; Sitt, Amit; Banin, Uri; Millo, Oded

2012-01-24

We utilize single-molecule spectroscopy combined with time-correlated single-photon counting to probe the electron transfer (ET) rates from various types of semiconductor hetero-nanocrystals, having either type-I or type-II band alignment, to single-walled carbon nanotubes. A significantly larger ET rate was observed for type-II ZnSe/CdS dot-in-rod nanostructures as compared to type-I spherical CdSe/ZnS core/shell quantum dots and to CdSe/CdS dot-in-rod structures. Furthermore, such rapid ET dynamics can compete with both Auger and radiative recombination processes, with significance for effective photovoltaic operation. © 2011 American Chemical Society

Ariel 6 measurements of ultra-heavy cosmic ray fluxes in the region 34 or = Z or = 48

NASA Technical Reports Server (NTRS)

Fowler, P. H.; Masheder, M. R. W.; Moses, R. T.; Walker, R. N. F.; Worley, A.; Gay, A. M.

1985-01-01

The Ariel VI satellite was launched by NASA on a Scout rocket on 3rd June 1979 from Wallops Island, Virginia, USA, into a near circular 625 km orbit inclined at 55 deg. It carried a spherical cosmic ray detector designed by a group from Bristol University. A spherical aluminum vessel of diameter 75 cm contains a gas scintillation mixture and a thin spherical shell of Pilot 425 plastic, and forms a single optical cavity viewed by 16 photomultipliers. Particle tracks through the detector may be characterized by their impact parameter p and by whether or not they pass through the cup of plastic scintillator placed between the sphere and the spacecraft body (referred to below as the Anti-Coincidence Detector or ACD). Individual particle charges are determined by separately measuring the gas scintillation and the Cerenkov emission from the plastic shell. This is possible because of the quite different distribution in time of these emissions.

Equivalent source modeling of the core magnetic field using magsat data

NASA Technical Reports Server (NTRS)

Mayhew, M. A.; Estes, R. H.

1983-01-01

Experiments are carried out on fitting the main field using different numbers of equivalent sources arranged in equal area at fixed radii at and inside the core-mantle boundary. In fixing the radius for a given series of runs, the convergence problems that result from the extreme nonlinearity of the problem when dipole positions are allowed to vary are avoided. Results are presented from a comparison between this approach and the standard spherical harmonic approach for modeling the main field in terms of accuracy and computational efficiency. The modeling of the main field with an equivalent dipole representation is found to be comparable to the standard spherical harmonic approach in accuracy. The 32 deg dipole density (42 dipoles) corresponds approximately to an eleventh degree/order spherical harmonic expansion (143 parameters), whereas the 21 dipole density (92 dipoles) corresponds to approximately a seventeenth degree and order expansion (323 parameters). It is pointed out that fixing the dipole positions results in rapid convergence of the dipole solutions for single-epoch models.

Energy gain calculations in Penning fusion systems using a bounce-averaged Fokker-Planck model

NASA Astrophysics Data System (ADS)

Chacón, L.; Miley, G. H.; Barnes, D. C.; Knoll, D. A.

2000-11-01

In spherical Penning fusion devices, a spherical cloud of electrons, confined in a Penning-like trap, creates the ion-confining electrostatic well. Fusion energy gains for these systems have been calculated in optimistic conditions (i.e., spherically uniform electrostatic well, no collisional ion-electron interactions, single ion species) using a bounce-averaged Fokker-Planck (BAFP) model. Results show that steady-state distributions in which the Maxwellian ion population is dominant correspond to lowest ion recirculation powers (and hence highest fusion energy gains). It is also shown that realistic parabolic-like wells result in better energy gains than square wells, particularly at large well depths (>100 kV). Operating regimes with fusion power to ion input power ratios (Q-value) >100 have been identified. The effect of electron losses on the Q-value has been addressed heuristically using a semianalytic model, indicating that large Q-values are still possible provided that electron particle losses are kept small and well depths are large.

Magnetic Inertial Confinement Fusion (MICF)

NASA Astrophysics Data System (ADS)

Miao, Feng; Zheng, Xianjun; Deng, Baiquan; Liu, Wei; Ou, Wei; Huang, Yi

2016-11-01

Based on the similarity in models of the early Sun and the 3-D common focal region of the micro-pinch in X-pinch experiments, a novel hybrid fusion configuration by continuous focusing of multiple Z-pinched plasma beams on spatially symmetric plasma is proposed. By replacing gravity with Lorentz force with subsequent centripetal spherical pinch, the beam-target fusion reactivity is enhanced in a quasi-spherical converging region, thus achieving MICF. An assessment, presented here, suggests that a practical fusion power source could be achieved using deuterium alone. Plasma instabilities can be suppressed by fast rotation resulting from an asymmetric tangential torsion in the spherical focal region of this configuration. Mathematical equivalence with the Sun allows the development of appropriate equations for the focal region of MICF, which are solved numerically to provide density, temperature and pressure distributions that produce net fusion energy output. An analysis of MICF physics and a preliminary experimental demonstration of a single beam are also carried out. supported by National Natural Science Foundation of China (Nos. 11374217 and 11176020)

Tokamak blanket design study, final report

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

Not Available

1980-08-01

A cylindrical module concept was developed, analyzed, and incorporated in a tokamak blanket system that includes piping systems, vacuum boundary sealing, and support structures. The design is based on the use of state-of-the-art structural materials (20% cold-worked type 316 stainless steel), lithium as the breeding material, and pressurized helium as the coolant. The module design consists of nested concentric cylinders (with an outer diameter of 10 cm) and features direct wall cooling by helium flowing between the outer (first-wall) cylinder and the inner (lithium-containing) cylinder. Each cylinder can withstand full coolant pressure, thus enhancing reliability. Results show that stainless steelmore » is a viable material for a first wall subjected to a neutron wall loading of 4 MW/m/sup 2/ and a particle heat flux of 1 MW/m/sup 2/. Lifetime analysis shows that the first-wall design meets the goal of operating at 20-min cycles with 95% duty for 100,000 cycles. To reduce system complexity, a larger 20-cm-diam module also was analyzed for incorporation in the blanket assembly. Reliability assessment indicates that it may be possible to double the module in size from 10 to 20 cm in diameter. With a modest increase in coolant pumping power, a blanket assembly comprising 20-cm-diam modules can still achieve 100,000 operating cycles - equivalent to a 3.6-year design lifetime - with only one or two helium coolant leaks into the plasma.« less

Matter distribution and spin-orbit force in spherical nuclei

NASA Astrophysics Data System (ADS)

Co', G.; Anguiano, M.; De Donno, V.; Lallena, A. M.

2018-03-01

We investigate the possibility that some nuclei show density distributions with a depletion in the center, a semibubble structure, by using a Hartree-Fock plus Bardeen-Cooper-Schrieffer approach. We separately study the proton, neutron, and matter distributions in 37 spherical nuclei mainly in the s -d shell region. We found a relation between the semibubble structure and the energy splitting of spin-orbit partner single particle levels. The presence of semibubble structure reduces this splitting, and we study its consequences on the excitation spectrum of the nuclei under investigation by using a quasiparticle random-phase-approximation approach. The excitation energies of the low-lying 4+ states can be related to the presence of semibubble structure in nuclei.

Deficiency of Starch Synthase IIIa and IVb Alters Starch Granule Morphology from Polyhedral to Spherical in Rice Endosperm1

PubMed Central

Toyosawa, Yoshiko; Kawagoe, Yasushi; Matsushima, Ryo; Ogawa, Masahiro; Fukuda, Masako; Kumamaru, Toshihiro; Okazaki, Yozo; Kusano, Miyako; Saito, Kazuki; Toyooka, Kiminori; Sato, Mayuko; Ai, Yongfeng; Fujita, Naoko

2016-01-01

Starch granule morphology differs markedly among plant species. However, the mechanisms controlling starch granule morphology have not been elucidated. Rice (Oryza sativa) endosperm produces characteristic compound-type granules containing dozens of polyhedral starch granules within an amyloplast. Some other cereal species produce simple-type granules, in which only one starch granule is present per amyloplast. A double mutant rice deficient in the starch synthase (SS) genes SSIIIa and SSIVb (ss3a ss4b) produced spherical starch granules, whereas the parental single mutants produced polyhedral starch granules similar to the wild type. The ss3a ss4b amyloplasts contained compound-type starch granules during early developmental stages, and spherical granules were separated from each other during subsequent amyloplast development and seed dehydration. Analysis of glucan chain length distribution identified overlapping roles for SSIIIa and SSIVb in amylopectin chain synthesis, with a degree of polymerization of 42 or greater. Confocal fluorescence microscopy and immunoelectron microscopy of wild-type developing rice seeds revealed that the majority of SSIVb was localized between starch granules. Therefore, we propose that SSIIIa and SSIVb have crucial roles in determining starch granule morphology and in maintaining the amyloplast envelope structure. We present a model of spherical starch granule production. PMID:26747287

Optical aberrations measurement with a low cost optometric instrument

NASA Astrophysics Data System (ADS)

Furlan, Walter D.; Muñoz-Escrivá, L.; Pons, A.; Martínez-Corral, M.

2002-08-01

A simple experimental method for measuring optical aberrations of a single lens is proposed. The technique is based on the use of an optometric instrument employed for the assessment of the refractive state of the eye: the retinoscope. Experimental results for spherical aberration and astigmatism are obtained.

Controlling the angular radiation of single emitters using dielectric patch nanoantennas

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

Yang, Yuanqing; Li, Qiang; Qiu, Min, E-mail: minqiu@zju.edu.cn

2015-07-20

Dielectric nanoantennas have generated much interest in recent years owing to their low loss and optically induced electric and magnetic resonances. In this paper, we investigate the coupling between a single emitter and dielectric patch nanoantennas. For the coupled system involving non-spherical structures, analytical Mie theory is no longer applicable. A semi-analytical model is proposed instead to interpret the coupling mechanism and the radiation characteristics of the system. Based on the presented model, we demonstrate that the angular emission of the single emitter can be not only enhanced but also rotated using the dielectric patch nanoantennas.

Probing the magnetic behavior of single nanodots.

PubMed

Neumann, Alexander; Thönnissen, Carsten; Frauen, Axel; Hesse, Simon; Meyer, Andreas; Oepen, Hans Peter

2013-05-08

In this paper, a method is presented that has the sensitivity to measure magnetization behavior of single nanostructures. It is demonstrated that the technique gives the ability to separate different signals of single nanodots from a small ensemble of structures. Our method is based on the anomalous Hall-Effect and allows for resolving signals from spherical nanoparticles with diameter down to 3.5 nm. The method gives access to magnetic properties of particles in a wide thermal and dynamical range. The potential of the technique is demonstrated utilizing particles that are created from Co films sandwiched by Pt layers.

Monte Carlo Simulations Comparing the Response of a Novel Hemispherical Tepc to Existing Spherical and Cylindrical Tepcs for Neutron Monitoring and Dosimetry.

PubMed

Broughton, David P; Waker, Anthony J

2017-05-01

Neutron dosimetry in reactor fields is currently mainly conducted with unwieldy flux monitors. Tissue Equivalent Proportional Counters (TEPCs) have been shown to have the potential to improve the accuracy of neutron dosimetry in these fields, and Multi-Element Tissue Equivalent Proportional Counters (METEPCs) could reduce the size of instrumentation required to do so. Complexity of current METEPC designs has inhibited their use beyond research. This work proposes a novel hemispherical counter with a wireless anode ball in place of the traditional anode wire as a possible solution for simplifying manufacturing. The hemispherical METEPC element was analyzed as a single TEPC to first demonstrate the potential of this new design by evaluating its performance relative to the reference spherical TEPC design and a single element from a cylindrical METEPC. Energy deposition simulations were conducted using the Monte Carlo code PHITS for both monoenergetic 2.5 MeV neutrons and the neutron energy spectrum of Cf-D2O moderated. In these neutron fields, the hemispherical counter appears to be a good alternative to the reference spherical geometry, performing slightly better than the cylindrical counter, which tends to underrespond to H*(10) for the lower neutron energies of the Cf-D2O moderated field. These computational results are promising, and if follow-up experimental work demonstrates the hemispherical counter works as anticipated, it will be ready to be incorporated into an METEPC design.

Refractive index measurements of single, spherical cells using digital holographic microscopy.

PubMed

Schürmann, Mirjam; Scholze, Jana; Müller, Paul; Chan, Chii J; Ekpenyong, Andrew E; Chalut, Kevin J; Guck, Jochen

2015-01-01

In this chapter, we introduce digital holographic microscopy (DHM) as a marker-free method to determine the refractive index of single, spherical cells in suspension. The refractive index is a conclusive measure in a biological context. Cell conditions, such as differentiation or infection, are known to yield significant changes in the refractive index. Furthermore, the refractive index of biological tissue determines the way it interacts with light. Besides the biological relevance of this interaction in the retina, a lot of methods used in biology, including microscopy, rely on light-tissue or light-cell interactions. Hence, determining the refractive index of cells using DHM is valuable in many biological applications. This chapter covers the main topics that are important for the implementation of DHM: setup, sample preparation, and analysis. First, the optical setup is described in detail including notes and suggestions for the implementation. Following that, a protocol for the sample and measurement preparation is explained. In the analysis section, an algorithm for the determination of quantitative phase maps is described. Subsequently, all intermediate steps for the calculation of the refractive index of suspended cells are presented, exploiting their spherical shape. In the last section, a discussion of possible extensions to the setup, further measurement configurations, and additional analysis methods are given. Throughout this chapter, we describe a simple, robust, and thus easily reproducible implementation of DHM. The different possibilities for extensions show the diverse fields of application for this technique. Copyright © 2015 Elsevier Inc. All rights reserved.

An empirical relationship for homogenization in single-phase binary alloy systems

NASA Technical Reports Server (NTRS)

Unnam, J.; Tenney, D. R.; Stein, B. A.

1979-01-01

A semiempirical formula is developed for describing the extent of interaction between constituents in single-phase binary alloy systems with planar, cylindrical, or spherical interfaces. The formula contains two parameters that are functions of mean concentration and interface geometry of the couple. The empirical solution is simple, easy to use, and does not involve sequential calculations, thereby allowing quick estimation of the extent of interactions without lengthy calculations. Results obtained with this formula are in good agreement with those from a finite-difference analysis.

Synthesis and characterization of nano-sized zirconia powder synthesized by single emulsion-assisted direct precipitation.

PubMed

Chandra, Navin; Singh, Deepesh Kumar; Sharma, Meenakshi; Upadhyay, Ravi Kant; Amritphale, S S; Sanghi, S K

2010-02-15

For the first time, single reverse microemulsion-assisted direct precipitation route has been successfully used to synthesize tetragonal zirconia nanoparticles in narrow size range. The synthesized powder was characterized using FT-IR, XRD and HRTEM techniques. The zirconia nanoparticles obtained were spherical in shape and has narrow particle size distribution in the range of 13-31nm and crystallite size in the range of 13-23nm. Copyright 2009 Elsevier Inc. All rights reserved.

IEEE Conference Record of 1978 Thirteenth Pulse Power Modulator Symposium, Buffalo, New York, 20-22 June 1978.

DTIC Science & Technology

1978-01-01

Advantagas possessed tage mast be high enough to effectively couple energy by water include the self - healing nature of the di- into the excimer gas mix, which...optimum input chosen aggregate of section self -inductances and mutual inductance between sections was module parameters and the Rayleigh module upset...6b0 cm in diam- eter and 6.86 cm long. A solid copper wire with the same number of circular mls has a diameter of 0.583 cm. The self -inductance o 60

An Experimental Apparatus to Study Enhanced Condensation Heat Transfer of Steam on Horizontal Tubes.

DTIC Science & Technology

1982-06-01

6-inches in diam- eter and 18-inches long and provides for condensing all excess steam. Two helically wound -oils of 3/8-inch copper tubing,- one 5 1...ml--13E lmoI EE EEEM NAVAL POSTGRADUATE SCHOOL Monterey, California SP27 1982 F THESIS AN EXPERIMENTAL APPARATUS TO STUDY ENHANCED CONDENSATION HEAT...Enhanced Condensation Heat Transfer June 1982 of Steam on Horizontal. Tubes & 081OWN ow,. NeWOormueT -. AUT@,a~4. CONTRACT ORt GOAMT NtUpMORA~e Raymond

High Voltage K sub a -Band Gyrotron Experiment.

DTIC Science & Technology

1985-11-20

3.8-cm-diam disk-shaped carbon cathode in a foilless diode configuration. Initially, as pointed out by Voronkov et al. (7], the tranverse velocity is...Xmn is the nth zero of dJm(x)/dx, R is the electron orbit guiding center radius, R.w is the cavity wall radius, and kmn=Xmn/Rw is the tranverse wave...possible competing mode. StartingC currents for the TE 6 ,2, TE1 0 ,1 and TE_3 ,3 modes for the experimentally observed e-beam radius of 1.16 cm are

Qualification Test of the Thiokol TE-M-364-19 Solid-Propellant Rocket Motor (S/N 19006)

DTIC Science & Technology

1977-05-01

cell by a steam ejector operating in series with the ETF exhaust gas compressors. During the motor firing, the motor exhaust gases were used as a...driving gas for the 42-in.-diam, water-cooled, ejector-diffuser system incorporating a 24-deg (half-angle) conical inlet to maintain test cell pressure...after Ignition, sec 0.5 0.6 0.7 Figure 4. Variation of thrust and chamber pressure during motor ignition. - CO Q_ OH LU CO TL cr x CJ 1400

Torquing preload in a lubricated bolt

NASA Technical Reports Server (NTRS)

Seegmiller, H. L.

1978-01-01

The tension preload obtained by torquing a 7/8 in. diam UNC high strength bolt was determined for lubricated and dry conditions. Consistent preload with a variation of + or - 3% was obtained when the bolt head area was lubricated prior to each torque application. Preload tensions nearly 70% greater than the value predicted with the commonly used formula occurred with the lubricated bolt. A reduction to 39% of the initial preload was observed during 50 torque applications without relubrication. Little evidence of wear was noted after 203 cycles of tightening.

Cathodic protection of a remote river pipeline

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

Martin, B.A.

1994-03-01

The 261-km long 500-mm diam Kutubu pipeline, which runs through dense jungle swamps in Papua, New Guinea, was built for Chevron Niugini to transport oil from the remote Kutubu oil production facility in the Southern Highlands to an offshore loading facility. The pipeline was laid with a section in the bed of a wide, fast-flowing river. This section was subject to substantial telluric effects and current density variations from changing water resistivities. The cathodic protection system's effectiveness was monitored by coupon off'' potentials and required an innovative approach.

Analysis of Space Shuttle Primary Reaction-Control Engine-Exhaust Transients

DTIC Science & Technology

2008-10-01

sensi- tivity in the spectral range of 0.4 to 0.9 /xm. The sensor gain was set to limit the size of the spot attributable to saturation by the solar...setting of the LAAT sensor . Table 1 lists the pertinent parameters for 22 attitude-control bums for which quality (30 frames per second) video footage was...intensity evolution of a narrow pulse of l-/im-diam droplets flying from the GLO sensor at the transient 2 representative speed of 1.6 km • s~’. The

Seed-Mediated Growth of Gold Nanocrystals: Changes to the Crystallinity or Morphology as Induced by the Treatment of Seeds with a Sulfur Species

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

Zheng, Yiqun; Luo, Ming; Tao, Jing

We report our observation of changes to the crystallinity or morphology during seed-mediated growth of Au nanocrystals. When single-crystal Au seeds with a spherical or rod-like shape were treated with a chemical species such as S₂O₃²⁻ ions, twin defects were developed during the growth process to generate multiply twinned nanostructures. X-ray photoelectron spectroscopy analysis indicated that the S₂O₃²⁻ ions were chemisorbed on the surfaces of the seeds during the treatment. The chemisorbed S₂O₃²⁻ ions somehow influenced the crystallization of Au atoms added onto the surface during a growth process, leading to the formation of twin defects. In contrast to themore » spherical and rod-like Au seeds, the single-crystal structure was retained to generate a concave morphology when single-crystal Au seeds with a cubic or octahedral shape were used for a similar treatment and then seed-mediated growth. The different outcomes are likely related to the difference in spatial distribution of S₂O₃²⁻ ions chemisorbed on the surface of a seed. This approach based on surface modification is potentially extendable to other noble metals for engineering the crystallinity and morphology of nanocrystals formed via seed-mediated growth.« less

Reflection-mode micro-spherical fiber-optic probes for in vitro real-time and single-cell level pH sensing.

PubMed

Yang, Qingbo; Wang, Hanzheng; Lan, Xinwei; Cheng, Baokai; Chen, Sisi; Shi, Honglan; Xiao, Hai; Ma, Yinfa

2015-02-01

pH sensing at the single-cell level without negatively affecting living cells is very important but still a remaining issue in the biomedical studies. A 70 μm reflection-mode fiber-optic micro-pH sensor was designed and fabricated by dip-coating thin layer of organically modified aerogel onto a tapered spherical probe head. A pH sensitive fluorescent dye 2', 7'-Bis (2-carbonylethyl)-5(6)-carboxyfluorescein (BCECF) was employed and covalently bonded within the aerogel networks. By tuning the alkoxide mixing ratio and adjusting hexamethyldisilazane (HMDS) priming procedure, the sensor can be optimized to have high stability and pH sensing ability. The in vitro real-time sensing capability was then demonstrated in a simple spectroscopic way, and showed linear measurement responses with a pH resolution up to an average of 0.049 pH unit within a narrow, but biological meaningful pH range of 6.12-7.81. Its novel characterizations of high spatial resolution, reflection mode operation, fast response and high stability, great linear response within biological meaningful pH range and high pH resolutions, make this novel pH probe a very cost-effective tool for chemical/biological sensing, especially within the single cell level research field.

Reflection-mode micro-spherical fiber-optic probes for in vitro real-time and single-cell level pH sensing

PubMed Central

Yang, Qingbo; Wang, Hanzheng; Lan, Xinwei; Cheng, Baokai; Chen, Sisi; Shi, Honglan; Xiao, Hai; Ma, Yinfa

2014-01-01

pH sensing at the single-cell level without negatively affecting living cells is very important but still a remaining issue in the biomedical studies. A 70 μm reflection-mode fiber-optic micro-pH sensor was designed and fabricated by dip-coating thin layer of organically modified aerogel onto a tapered spherical probe head. A pH sensitive fluorescent dye 2′, 7′-Bis (2-carbonylethyl)-5(6)-carboxyfluorescein (BCECF) was employed and covalently bonded within the aerogel networks. By tuning the alkoxide mixing ratio and adjusting hexamethyldisilazane (HMDS) priming procedure, the sensor can be optimized to have high stability and pH sensing ability. The in vitro real-time sensing capability was then demonstrated in a simple spectroscopic way, and showed linear measurement responses with a pH resolution up to an average of 0.049 pH unit within a narrow, but biological meaningful pH range of 6.12–7.81. Its novel characterizations of high spatial resolution, reflection mode operation, fast response and high stability, great linear response within biological meaningful pH range and high pH resolutions, make this novel pH probe a very cost-effective tool for chemical/biological sensing, especially within the single cell level research field. PMID:25530670

Seed-Mediated Growth of Gold Nanocrystals: Changes to the Crystallinity or Morphology as Induced by the Treatment of Seeds with a Sulfur Species

DOE PAGES

Zheng, Yiqun; Luo, Ming; Tao, Jing; ...

2014-12-11

We report our observation of changes to the crystallinity or morphology during seed-mediated growth of Au nanocrystals. When single-crystal Au seeds with a spherical or rod-like shape were treated with a chemical species such as S₂O₃²⁻ ions, twin defects were developed during the growth process to generate multiply twinned nanostructures. X-ray photoelectron spectroscopy analysis indicated that the S₂O₃²⁻ ions were chemisorbed on the surfaces of the seeds during the treatment. The chemisorbed S₂O₃²⁻ ions somehow influenced the crystallization of Au atoms added onto the surface during a growth process, leading to the formation of twin defects. In contrast to themore » spherical and rod-like Au seeds, the single-crystal structure was retained to generate a concave morphology when single-crystal Au seeds with a cubic or octahedral shape were used for a similar treatment and then seed-mediated growth. The different outcomes are likely related to the difference in spatial distribution of S₂O₃²⁻ ions chemisorbed on the surface of a seed. This approach based on surface modification is potentially extendable to other noble metals for engineering the crystallinity and morphology of nanocrystals formed via seed-mediated growth.« less

A mathematical model of single target site location by Brownian movement in subcellular compartments.

PubMed

Kuthan, Hartmut

2003-03-07

The location of distinct sites is mandatory for many cellular processes. In the subcompartments of the cell nucleus, only very small numbers of diffusing macromolecules and specific target sites of some types may be present. In this case, we are faced with the Brownian movement of individual macromolecules and their "random search" for single/few specific target sites, rather than bulk-averaged diffusion and multiple sites. In this article, I consider the location of a distant central target site, e.g. a globular protein, by individual macromolecules executing unbiased (i.e. drift-free) random walks in a spherical compartment. For this walk-and-capture model, the closed-form analytic solution of the first passage time probability density function (p.d.f.) has been obtained as well as the first and second moment. In the limit of a large ratio of the radii of the spherical diffusion space and central target, well-known relations for the variance and the first two moments for the exponential p.d.f. were found to hold with high accuracy. These calculations reinforce earlier numerical results and Monte Carlo simulations. A major implication derivable from the model is that non-directed random movement is an effective means for locating single sites in submicron-sized compartments, even when the diffusion coefficients are comparatively small and the diffusing species are present in one copy only. These theoretical conclusions are underscored numerically for effective diffusion constants ranging from 0.5 to 10.0 microm(2) s(-1), which have been reported for a couple of nuclear proteins in their physiological environment. Spherical compartments of submicron size are, for example, the Cajal bodies (size: 0.1-1.0 microm), which are present in 1-5 copies in the cell nucleus. Within a small Cajal body of radius 0.1 microm a single diffusing protein molecule (with D=0.5 microm(2) s(-1)) would encounter a medium-sized protein of radius 2.5 nm within 1 s with a probability near certainty (p=0.98).

Sticking properties of ice grains

NASA Astrophysics Data System (ADS)

Jongmanns, M.; Kumm, M.; Wurm, G.; Wolf, D. E.; Teiser, J.

2017-06-01

We study the size dependence of pull-off forces of water ice in laboratory experiments and numerical simulations. To determine the pull-off force in our laboratory experiments, we use a liquid nitrogen cooled centrifuge. Depending on its rotation frequency, spherical ice grains detach due to the centrifugal force which is related to the adhesive properties. Numerical simulations are conducted by means of molecular dynamics simulations of hexagonal ice using a standard coarse-grained water potential. The pull-off force of a single contact between two spherical ice grains is measured due to strain controlled simulations. Both, the experimental study and the simulations reveal a dependence between the pull-off force and the (reduced) particle radii, which differ significantly from the linear dependence of common contact theories.

Dynamics and interactions of particles in a thermophoretic trap

NASA Astrophysics Data System (ADS)

Foster, Benjamin; Fung, Frankie; Fieweger, Connor; Usatyuk, Mykhaylo; Gaj, Anita; DeSalvo, B. J.; Chin, Cheng

2017-08-01

We investigate dynamics and interactions of particles levitated and trapped by the thermophoretic force in a vacuum cell. Our analysis is based on footage taken by orthogonal cameras that are able to capture the three dimensional trajectories of the particles. In contrast to spherical particles, which remain stationary at the center of the cell, here we report new qualitative features of the motion of particles with non-spherical geometry. Singly levitated particles exhibit steady spinning around their body axis and rotation around the symmetry axis of the cell. When two levitated particles approach each other, repulsive or attractive interactions between the particles are observed. Our levitation system offers a wonderful platform to study interaction between particles in a microgravity environment.

Single-axis four-mirror system: large spherical primary and small fields

NASA Astrophysics Data System (ADS)

Baranne, Andre

1998-08-01

A catoptric corrector of modest size can be used for large spherical primaries, easily integrated at the prime focus, this corrector gives back to the system, aspect and properties of 2-mirrors classical telescopes. In the last few years, progress in active and adaptative optics makes possible a lot of things, progress in measuring distances, new ideas on optical coatings, new materials and so on in a near future, all that makes the instrumentalist dreamy It is said that nobody knows today if the size of 3rd millennium telescopes will be limited or not by a theoretical, physical or technical phenomenon, thus let us imagine but with thoughtfulness because our projects will be surely restricted by financial considerations

Nuclear mass formula with the shell energies obtained by a new method

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

Koura, H.; Tachibana, T.; Yamada, M.

1998-12-21

Nuclear shapes and masses are estimated by a new method. The main feature of this method lies in estimating shell energies of deformed nuclei from spherical shell energies by mixing them with appropriate weights. The spherical shell energies are calculated from single-particle potentials, and, till now, two mass formulas have been constructed from two different sets of potential parameters. The standard deviation of the calculated masses from all the experimental masses of the 1995 Mass Evaluation is about 760 keV. Contrary to the mass formula by Tachibana, Uno, Yamada and Yamada in the 1987-1988 Atomic Mass Predictions, the present formulasmore » can give nuclear shapes and predict on super-heavy elements.« less

Direct evidence on the existence of [Mo132]Keplerate-type species in aqueous solution.

PubMed

Roy, Soumyajit; Planken, Karel L; Kim, Robbert; Mandele, Dexx v d; Kegel, Willem K

2007-10-15

We demonstrate the existence of discrete single molecular [Mo(132)] Keplerate-type clusters in aqueous solution. Starting from a discrete spherical [Mo(132)] cluster, the formation of an open-basket-type [Mo(116)] defect structure is shown for the first time in solution using analytical ultracentrifugation sedimentation velocity experiments.

Scattering of plane transverse waves by spherical inclusions in a poroelastic medium

NASA Astrophysics Data System (ADS)

Liu, Xu; Greenhalgh, Stewart; Zhou, Bing

2009-03-01

The scattering of plane transverse waves by a spherical inclusion embedded in an infinite poroelastic medium is treated for the first time in this paper. The vector displacement wave equations of Biot's theory are solved as an infinite series of vector spherical harmonics for the case of a plane S-wave impinging from a porous medium onto a spherical inclusion which itself is assumed to be another porous medium. Based on the single spherical scattering theory and dynamic composite elastic medium theory, the non-self-consistent shear wavenumber is derived for a porous rock having numerous spherical inclusions of another medium. The frequency dependences of the shear wave velocity and the shear wave attenuation have been calculated for both the patchy saturation model (inclusions having the same solid frame as the host but with a different pore fluid from the host medium) and the double porosity model (inclusions having a different solid frame than the host but the same pore fluid as the host medium) with dilute concentrations of identical inclusions. Unlike the case of incident P-wave scattering, we show that although the fluid and the heterogeneity of the rock determine the shear wave velocity of the composite, the attenuation of the shear wave caused by scattering is actually contributed by the heterogeneity of the rock for spherical inclusions. The scattering of incident shear waves in the patchy saturation model is quite different from that of the double porosity model. For the patchy saturation model, the gas inclusions do not significantly affect the shear wave dispersion characteristic of the water-filled host medium. However, the softer inclusion with higher porosity in the double porosity model can cause significant shear wave scattering attenuation which occurs at a frequency at which the wavelength of the shear wave is approximately equal to the characteristic size of the inclusion and depends on the volume fraction. Compared with analytic formulae for the low frequency limit of the shear velocity, our scattering model yields discrepancies within 4.0 per cent. All calculated shear velocities of the composite medium with dilute inclusion concentrations approach the high frequency limit of the host material.

Telephoto axicon

NASA Astrophysics Data System (ADS)

Burvall, Anna; Goncharov, Alexander; Dainty, Chris

2005-09-01

The axicon is an optical element which creates a narrow focal line along the optical axis, unlike the single focal point produced by a lens. The long and precisely defined axicon focal line is used e.g. in alignment, or to extend the depth of focus of existing methods such as optical coherence tomography or light sectioning. Axicons are generally manufactured as refractive cones or diffractive circular gratings. They are also made as lens systems or doublet lenses, which are easier to produce. We present a design in the form of a reflective-refractive single-element device with annular aperture. This very compact system has only two surfaces, which can be spherical or aspheric depending on the quality required of the focal line. Both surfaces have reflective coatings at specific zones, providing an annular beam suitable for generating extended focal lines. One draw-back of a normal axicon is its sensitivity to the angle of illumination. Even for relatively small angles, astigmatism will broaden the focus and give it an asteroid shape. For our design, with spherical surfaces concentric about the center of the entrance pupil, the focal line remains unchanged in off-axis illumination.

Small and large particle limits of single scattering albedo for homogeneous, spherical particles

NASA Astrophysics Data System (ADS)

Moosmüller, H.; Sorensen, C. M.

2018-01-01

The aerosol single scattering albedo (SSA) is the dominant intensive particle parameter determining aerosols direct radiative forcing. For homogeneous spherical particles and a complex refractive index independent of wavelength, the SSA is solely dependent on size parameter (ratio of particle circumference and wavelength) and complex refractive index of the particle. Here, we explore this dependency for the small and large particle limits with size parameters much smaller and much larger than one. We show that in the small particle limit of Rayleigh scattering, a novel, generalized size parameter can be introduced that unifies the SSA dependence on particle size parameter independent of complex refractive index. In the large particle limit, SSA decreases with increasing product of imaginary part of the refractive index and size parameter, another generalized parameter, until this product becomes about one, then stays fairly constant until the imaginary part of the refractive index becomes comparable with the real part minus one. Beyond this point, particles start to acquire metallic character and SSA quickly increases with the imaginary part of the refractive index and approaches one.

A paper-based scaffold for enhanced osteogenic differentiation of equine adipose-derived stem cells.

PubMed

Petersen, Gayle F; Hilbert, Bryan J; Trope, Gareth D; Kalle, Wouter H J; Strappe, Padraig M

2015-11-01

We investigated the applicability of single layer paper-based scaffolds for the three-dimensional (3D) growth and osteogenic differentiation of equine adipose-derived stem cells (EADSC), with comparison against conventional two-dimensional (2D) culture on polystyrene tissue culture vessels. Viable culture of EADSC was achieved using paper-based scaffolds, with EADSC grown and differentiated in 3D culture retaining high cell viability (>94 %), similarly to EADSC in 2D culture. Osteogenic differentiation of EADSC was significantly enhanced in 3D culture, with Alizarin Red S staining and quantification demonstrating increased mineralisation (p < 0.0001), and an associated increase in expression of the osteogenic-specific markers alkaline phosphatase (p < 0.0001), osteopontin (p < 0.0001), and runx2 (p < 0.01). Furthermore, scanning electron microscopy revealed a spherical morphology of EADSC in 3D culture, compared to a flat morphology of EADSC in 2D culture. Single layer paper-based scaffolds provide an enhanced environment for the in vitro 3D growth and osteogenic differentiation of EADSC, with high cell viability, and a spherical morphology.

Electron-Beam-Lithographed Nanostructures as Reference Materials for Label-Free Scattered-Light Biosensing of Single Filoviruses.

PubMed

Agrawal, Anant; Majdi, Joseph; Clouse, Kathleen A; Stantchev, Tzanko

2018-05-23

Optical biosensors based on scattered-light measurements are being developed for rapid and label-free detection of single virions captured from body fluids. Highly controlled, stable, and non-biohazardous reference materials producing virus-like signals are valuable tools to calibrate, evaluate, and refine the performance of these new optical biosensing methods. To date, spherical polymer nanoparticles have been the only non-biological reference materials employed with scattered-light biosensing techniques. However, pathogens like filoviruses, including the Ebola virus, are far from spherical and their shape strongly affects scattered-light signals. Using electron beam lithography, we fabricated nanostructures resembling individual filamentous virions attached to a biosensing substrate (silicon wafer overlaid with silicon oxide film) and characterized their dimensions with scanning electron and atomic force microscopes. To assess the relevance of these nanostructures, we compared their signals across the visible spectrum to signals recorded from Ebola virus-like particles which exhibit characteristic filamentous morphology. We demonstrate the highly stable nature of our nanostructures and use them to obtain new insights into the relationship between virion dimensions and scattered-light signal.

Single macroscopic pillars as model system for bioinspired adhesives: influence of tip dimension, aspect ratio, and tilt angle.

PubMed

Micciché, Maurizio; Arzt, Eduard; Kroner, Elmar

2014-05-28

The goal of our study is to better understand the design parameters of bioinspired dry adhesives inspired by geckos. For this, we fabricated single macroscopic pillars of 400 μm diameter with different aspect ratios and different tip shapes (i.e., flat tips, spherical tips with different radii, and mushroom tips with different diameters). Tilt-angle-dependent adhesion measurements showed that although the tip shape of the pillars strongly influences the pull-off force, the pull-off strength is similar for flat and mushroom-shaped tips. We found no tilt-angle dependency of adhesion for spherical tip structures and, except for high tilt angle and low preload experiments, no tilt-angle effect for mushroom-tip pillars. For flat-tip pillars, we found a strong influence of tilt angle on adhesion, which decreased linearly with increasing aspect ratio. The experiments show that for the tested aspect ratios between 1 and 5, a linear decrease of tilt-angle dependency is found. The results of our studies will help to design bioinspired adhesives for application on smooth and rough surfaces.

Effect of spherical Au nanoparticles on nanofriction and wear reduction in dry and liquid environments

PubMed Central

Maharaj, Dave

2012-01-01

Summary Nano-object additives are used in tribological applications as well as in various applications in liquids requiring controlled manipulation and targeting. On the macroscale, nanoparticles in solids and liquids have been shown to reduce friction and wear. On the nanoscale, atomic force microscopy (AFM) studies have been performed in single- and multiple-nanoparticle contact, in dry environments, to characterize friction forces and wear. However, limited studies in submerged liquid environments have been performed and further studies are needed. In this paper, spherical Au nanoparticles were studied for their effect on friction and wear under dry conditions and submerged in water. In single-nanoparticle contact, individual nanoparticles, deposited on silicon, were manipulated with a sharp tip and the friction force was determined. Multiple-nanoparticle contact sliding experiments were performed on nanoparticle-coated silicon with a glass sphere. Wear tests were performed on the nanoscale with AFM as well as on the macroscale by using a ball-on-flat tribometer to relate friction and wear reduction on the nanoscale and macroscale. Results indicate that the addition of Au nanoparticles reduces friction and wear. PMID:23213639

Analytical study of the acoustic field in a spherical resonator for single bubble sonoluminescence.

PubMed

Dellavale, Damián; Urteaga, Raúl; Bonetto, Fabián J

2010-01-01

The acoustic field in the liquid within a spherical solid shell is calculated. The proposed model takes into account Stoke's wave equation in the viscous fluid, the membrane theory to describe the solid shell motion and the energy loss through the external couplings of the system. A point source at the resonator center is included to reproduce the acoustic emission of a sonoluminescence bubble. Particular calculations of the resulting acoustic field are performed for viscous liquids of interest in single bubble sonoluminescence. The model reveals that in case of radially symmetric modes of low frequency, the quality factor is mainly determined by the acoustic energy flowing through the mechanical coupling of the resonator. Alternatively, for high frequency modes the quality factor is mainly determined by the viscous dissipation in the liquid. Furthermore, the interaction between the bubble acoustic emission and the resonator modes is analyzed. It was found that the bubble acoustic emission produces local maxima in the resonator response. The calculated amplitudes and relative phases of the harmonics constituting the bubble acoustic environment can be used to improve multi-frequency driving in sonoluminescence.

Formation of a new archetypal Metal-Organic Framework from a simple monatomic liquid

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

Metere, Alfredo, E-mail: alfredo.metere@mmk.su.se; Oleynikov, Peter; Dzugutov, Mikhail

2014-12-21

We report a molecular-dynamics simulation of a single-component system of particles interacting via a spherically symmetric potential that is found to form, upon cooling from a liquid state, a low-density porous crystalline phase. Its structure analysis demonstrates that the crystal can be described by a net with a topology that belongs to the class of topologies characteristic of the Metal-Organic Frameworks (MOFs). The observed net is new, and it is now included in the Reticular Chemistry Structure Resource database. The observation that a net topology characteristic of MOF crystals, which are known to be formed by a coordination-driven self-assembly process,more » can be reproduced by a thermodynamically stable configuration of a simple single-component system of particles opens a possibility of using these models in studies of MOF nets. It also indicates that structures with MOF topology, as well as other low-density porous crystalline structures can possibly be produced in colloidal systems of spherical particles, with an appropriate tuning of interparticle interaction.« less

A curved ultrasonic actuator optimized for spherical motors: design and experiments.

PubMed

Leroy, Edouard; Lozada, José; Hafez, Moustapha

2014-08-01

Multi-degree-of-freedom angular actuators are commonly used in numerous mechatronic areas such as omnidirectional robots, robot articulations or inertially stabilized platforms. The conventional method to design these devices consists in placing multiple actuators in parallel or series using gimbals which are bulky and difficult to miniaturize. Motors using a spherical rotor are interesting for miniature multidegree-of-freedom actuators. In this paper, a new actuator is proposed. It is based on a curved piezoelectric element which has its inner contact surface adapted to the diameter of the rotor. This adaptation allows to build spherical motors with a fully constrained rotor and without a need for additional guiding system. The work presents a design methodology based on modal finite element analysis. A methodology for mode selection is proposed and a sensitivity analysis of the final geometry to uncertainties and added masses is discussed. Finally, experimental results that validate the actuator concept on a single degree-of-freedom ultrasonic motor set-up are presented. Copyright © 2014 Elsevier B.V. All rights reserved.

Design and Optimization of the SPOT Primary Mirror Segment

NASA Technical Reports Server (NTRS)

Budinoff, Jason G.; Michaels, Gregory J.

2005-01-01

The 3m Spherical Primary Optical Telescope (SPOT) will utilize a single ring of 0.86111 point-to-point hexagonal mirror segments. The f2.85 spherical mirror blanks will be fabricated by the same replication process used for mass-produced commercial telescope mirrors. Diffraction-limited phasing will require segment-to-segment radius of curvature (ROC) variation of approx.1 micron. Low-cost, replicated segment ROC variations are estimated to be almost 1 mm, necessitating a method for segment ROC adjustment & matching. A mechanical architecture has been designed that allows segment ROC to be adjusted up to 400 microns while introducing a minimum figure error, allowing segment-to-segment ROC matching. A key feature of the architecture is the unique back profile of the mirror segments. The back profile of the mirror was developed with shape optimization in MSC.Nastran(TradeMark) using optical performance response equations written with SigFit. A candidate back profile was generated which minimized ROC-adjustment-induced surface error while meeting the constraints imposed by the fabrication method. Keywords: optimization, radius of curvature, Pyrex spherical mirror, Sigfit

Thermally induced lamellar reorganization and thickening in spherical poly (L-lactic acid) crystalsome

NASA Astrophysics Data System (ADS)

Staub, Mark; Qi, Hao; Li, Christopher

Understanding fundamental aspects of spherical crystals is important for a variety of applications such as encapsulation and drug delivery. The curved nature of these crystals gives rise to differences in key crystallographic concepts such as grain boundaries and defect formation when compared to flat crystals. This curved crystallography is difficult to study experimentally, especially at the nanoscale. Our group has recently shown how an oil in water miniemulsion can be used to direct the crystallization of poly (L-lactic acid) (PLLA) at a curved liquid/liquid interface. This produces nanosized, polymer single-crystal-like capsules termed crystalsomes with increased stability and mechanical properties compared with non-crystalline counterparts. This system will serve as our model for examining spherical crystallography. In this work, combined wide angle X-ray diffraction, Atomic force microscopy, and differential scanning calorimetry is employed to examine how the curved interface effects crystal thickening and reorganization compared to flat PLLA crystals. The influence of degree of curvature on these processes is also studied by examining crystalsomes with differing diameters.

Ray propagation in oblate atmospheres. [for Jupiter

NASA Technical Reports Server (NTRS)

Hubbard, W. B.

1976-01-01

Phinney and Anderson's (1968) exact theory for the inversion of radio-occultation data for planetary atmospheres breaks down seriously when applied to occultations by oblate atmospheres because of departures from Bouguer's law. It has been proposed that this breakdown can be overcome by transforming the theory to a local spherical symmetry which osculates a ray's point of closest approach. The accuracy of this transformation procedure is assessed by evaluating the size of terms which are intrinsic to an oblate atmosphere and which are not eliminated by a local spherical approximation. The departures from Bouguer's law are analyzed, and it is shown that in the lowest-order deviation from that law, the plane of refraction is defined by the normal to the atmosphere at closest approach. In the next order, it is found that the oblateness of the atmosphere 'warps' the ray path out of a single plane, but the effect appears to be negligible for most purposes. It is concluded that there seems to be no source of serious error in making an approximation of local spherical symmetry with the refraction plane defined by the normal at closest approach.

Acoustic manipulation of oscillating spherical bodies: Emergence of axial negative acoustic radiation force

NASA Astrophysics Data System (ADS)

Rajabi, Majid; Mojahed, Alireza

2016-11-01

In this paper, emergence of negative axial acoustic radiation force on a rigid oscillating spherical body is investigated for acoustic manipulation purposes. The problem of plane acoustic wave scattering from an oscillating spherical body submerged in an ideal acoustic fluid medium is solved. For the case of oscillating direction collinear with the wave propagation wave number vector (desired path), it has been shown that the acoustic radiation force, as a result of nonlinear acoustic wave interaction with bodies can be expressed as a linear function of incident wave field and the oscillation properties of the oscillator (i.e., amplitude and phase of oscillation). The negative (i.e., pulling effects) and positive (i.e., pushing effects) radiation force situations are divided in oscillation complex plane with a specific frequency-dependant straight line. This characteristic line defines the radiation force cancellation state. In order to investigate the stability of the mentioned manipulation strategy, the case of misaligned oscillation of sphere with the wave propagation direction is studied. The proposed methodology may suggest a novel concept of single-beam acoustic handling techniques based on smart carriers.

Diffusion-mediated dephasing in the dipole field around a single spherical magnetic object.

PubMed

Buschle, Lukas R; Kurz, Felix T; Kampf, Thomas; Triphan, Simon M F; Schlemmer, Heinz-Peter; Ziener, Christian Herbert

2015-11-01

In this work, the time evolution of the free induction decay caused by the local dipole field of a spherical magnetic perturber is analyzed. The complicated treatment of the diffusion process is replaced by the strong-collision-approximation that allows a determination of the free induction decay in dependence of the underlying microscopic tissue parameters such as diffusion coefficient, sphere radius and susceptibility difference. The interplay between susceptibility- and diffusion-mediated effects yields several dephasing regimes of which, so far, only the classical regimes of motional narrowing and static dephasing for dominant and negligible diffusion, respectively, were extensively examined. Due to the asymmetric form of the dipole field for spherical objects, the free induction decay exhibits a complex component in contradiction to the cylindrical case, where the symmetric local dipole field only causes a purely real induction decay. Knowledge of the shape of the corresponding frequency distribution is necessary for the evaluation of more sophisticated pulse sequences and a detailed understanding of the off-resonance distribution allows improved quantification of transverse relaxation. Copyright © 2015 Elsevier Inc. All rights reserved.

Structured Laguerre-Gaussian beams for mitigation of spherical aberration in tightly focused regimes

NASA Astrophysics Data System (ADS)

Haddadi, S.; Bouzid, O.; Fromager, M.; Hasnaoui, A.; Harfouche, A.; Cagniot, E.; Forbes, A.; Aït-Ameur, K.

2018-04-01

Many laser applications utilise a focused laser beam having a single-lobed intensity profile in the focal plane, ideally with the highest possible on-axis intensity. Conventionally, this is achieved with the lowest-order Laguerre-Gaussian mode (LG00), the Gaussian beam, in a tight focusing configuration. However, tight focusing often involves significant spherical aberration due to the high numerical aperture of the systems involved, thus degrading the focal quality. Here, we demonstrate that a high-order radial LG p0 mode can be tailored to meet and in some instances exceed the performance of the Gaussian. We achieve this by phase rectification of the mode using a simple binary diffractive optic. By way of example, we show that the focusing of a rectified LG50 beam is almost insensitive to a spherical aberration coefficient of over three wavelengths, in contrast with the usual Gaussian beam for which the intensity of the focal spot is reduced by a factor of two. This work paves the way towards enhanced focal spots using structured light.

Development of a Compact Captive Balloon and Its Level Supporting

NASA Astrophysics Data System (ADS)

Nakao, Tatsuya; Fujiwara, Kazuhito; Furukawa, Motoyasu; Hiroe, Tetsuyuki

Many kinds of observation techniques have been developed to obtain the properties of atmospheric conditions. The advanced observation techniques of the flow in relatively large scale are remote sensing by satellite facilities, long range observations by radar or Doppler Sodar, etc., while data from conventional climometers set at fixed places are merely limited information about local scale flow. Captive balloons are also available and feasible for the observation of local flows if their standing mechanics are robust against the strong wind and the motion of balloon are stable for all wind direction and the change of wind direction. In this paper, a compact captive balloon (about 2m diam.) for flow measurement is proposed and the preservation of balloon height level and the stabilization of its motion are challenged by using a kite. The relation between force balances acted on the balloon and the balloon height or position was estimated and confirmed in experiments. Although the lift force of single kite worked successfully, it is found that the performance of plural kites is less in the traction of balloon since the interaction of their tensions. The compact balloon supported by the kite enabled the over 300m floating by virtue of the small size causing only low air resistance.

Fuel Areal-Density Measurements in Laser-Driven Magnetized Inertial Fusion from Secondary Neutrons

NASA Astrophysics Data System (ADS)

Davies, J. R.; Barnak, D. H.; Betti, R.; Glebov, V. Yu.; Knauer, J. P.; Peebles, J. L.

2017-10-01

Laser-driven magnetized liner inertial fusion is being developed on the OMEGA laser to provide the first data at a significantly smaller scale than the Z pulsed-power machine in order to test scaling and to provide more shots with better diagnostic access than Z. In OMEGA experiments, a 0.6-mm-outer-diam plastic cylinder filled with 11 atm of D2 is placed in an axial magnetic field of 10 T, the D2 is preheated by a single beam along the axis, and then the cylinder is compressed by 40 beams. Secondary DT neutron yields provide a measurement of the areal density of the compressed D2 because the compressed fuel is much smaller than the mean free path and the Larmor radius of the T produced in D-D fusion. Measured secondary yields confirm theoretical predictions that preheating and magnetization reduce fuel compression. Higher fuel compression is found to consistently lead to lower neutron yields, which is not predicted by simulations. The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000568 and the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

High-resolution digital dosimetric system for spatial characterization of radiation fields using a thermoluminescent CaF/sub 2/:Dy crystal

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

Atari, N.A.; Svensson, G.K.

1986-05-01

A high-resolution digital dosimetric system has been developed for the spatial characterization of radiation fields. The system comprises the following: 0.5-mm-thick, 25-mm-diam CaF/sub 2/:Dy thermoluminescent crystal; intensified charge coupled device video camera; video cassette recorder; and a computerized image processing subsystem. The optically flat single crystal is used as a radiation imaging device and the subsequent thermally stimulated phosphorescence is viewed by the intensified camera for further processing and analysis. Parameters governing the performance characteristics of the system were measured. A spatial resolution limit of 31 +- 2 ..mu..m (1sigma) corresponding to 16 +- 1 line pair/mm measured at themore » 4% level of the modulation transfer function has been achieved. The full width at half maximum of the line spread function measured independently by the slit method or derived from the edge response function was found to be 69 +- 4 ..mu..m (1sigma). The high resolving power, speed of readout, good precision, wide dynamic range, and the large image storage capacity make the system suitable for the digital mapping of the relative distribution of absorbed doses for various small radiation fields and the edges of larger fields.« less

High-resolution digital dosimetric system for spatial characterization of radiation fields using a thermoluminescent CaF2:Dy crystal

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

Atari, N.A.; Svensson, G.K.

1986-05-01

A high-resolution digital dosimetric system has been developed for the spatial characterization of radiation fields. The system comprises the following: 0.5-mm-thick, 25-mm-diam CaF2:Dy thermoluminescent crystal; intensified charge coupled device video camera; video cassette recorder; and a computerized image processing subsystem. The optically flat single crystal is used as a radiation imaging device and the subsequent thermally stimulated phosphorescence is viewed by the intensified camera for further processing and analysis. Parameters governing the performance characteristics of the system were measured. A spatial resolution limit of 31 +/- 2 microns (1 sigma) corresponding to 16 +/- 1 line pairs/mm measured at themore » 4% level of the modulation transfer function has been achieved. The full width at half maximum of the line spread function measured independently by the slit method or derived from the edge response function was found to be 69 +/- 4 microns (1 sigma). The high resolving power, speed of readout, good precision, wide dynamic range, and the large image storage capacity make the system suitable for the digital mapping of the relative distribution of absorbed doses for various small radiation fields and the edges of larger fields.« less

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

Al-Robaee, M.S.; Krishna, M.G.; Rao, K.N.

Single layer films of CeO{sub 2} have been deposited both by conventional electron beam evaporation and ion assisted deposition with oxygen and argon ions. A broad beam Kaufman ion source (3 cm diam) has been used to generate the ions. A systematic study has been made on optical properties such as refractive index, extinction coefficient and inhomogeneity of the films as a function of: (1) oxygen partial pressure in the range 1{times}10{sup {minus}4} to 1{times}10{sup {minus}5} mbar. (2) Incidence of oxygen ions with energy in the range 300--700 eV and current density in the range 50--220 {mu}A/cm{sup 2}. (3) Incidencemore » of mixed argon and oxygen ions of different ratios. The refractive index of the films deposited under the influence of ion bombardment showed higher indices than the conventionally evaporated films. The maximum index obtained with an oxygen ion bombardment was 2.3 at an ion energy of 600 eV and current density of 220 {mu}A/cm{sup 2}. The bombardment of the films with a mixed argon--oxygen (25% Ar) ion beam of the same energy and current density was found to further increase the refractive index. The extinction coefficient in both cases was negligible.« less

Experimental demonstration of low laser-plasma instabilities in gas-filled spherical hohlraums at laser injection angle designed for ignition target

NASA Astrophysics Data System (ADS)

Lan, Ke; Li, Zhichao; Xie, Xufei; Chen, Yao-Hua; Zheng, Chunyang; Zhai, Chuanlei; Hao, Liang; Yang, Dong; Huo, Wen Yi; Ren, Guoli; Peng, Xiaoshi; Xu, Tao; Li, Yulong; Li, Sanwei; Yang, Zhiwen; Guo, Liang; Hou, Lifei; Liu, Yonggang; Wei, Huiyue; Liu, Xiangming; Cha, Weiyi; Jiang, Xiaohua; Mei, Yu; Li, Yukun; Deng, Keli; Yuan, Zheng; Zhan, Xiayu; Zhang, Haijun; Jiang, Baibin; Zhang, Wei; Deng, Xuewei; Liu, Jie; Du, Kai; Ding, Yongkun; Wei, Xiaofeng; Zheng, Wanguo; Chen, Xiaodong; Campbell, E. M.; He, Xian-Tu

2017-03-01

Octahedral spherical hohlraums with a single laser ring at an injection angle of 55∘ are attractive concepts for laser indirect drive due to the potential for achieving the x-ray drive symmetry required for high convergence implosions. Laser-plasma instabilities, however, are a concern given the long laser propagation path in such hohlraums. Significant stimulated Raman scattering has been observed in cylindrical hohlraums with similar laser propagation paths during the ignition campaign on the National Ignition Facility (NIF). In this Rapid Communication, experiments demonstrating low levels of laser-driven plasma instability (LPI) in spherical hohlraums with a laser injection angle of 55∘ are reported and compared to that observed with cylindrical hohlraums with injection angles of 28 .5∘ and 55∘, similar to that of the NIF. Significant LPI is observed with the laser injection of 28 .5∘ in the cylindrical hohlraum where the propagation path is similar to the 55∘ injection angle for the spherical hohlraum. The experiments are performed on the SGIII laser facility with a total 0.35 -μ m incident energy of 93 kJ in a 3 nsec pulse. These experiments demonstrate the role of hohlraum geometry in LPI and demonstrate the need for systematic experiments for choosing the optimal configuration for ignition studies with indirect drive inertial confinement fusion.

Equilibium and Stability of Spherical Vlasov Systems

NASA Astrophysics Data System (ADS)

Barnes, D. C.; Chacon, L.; Finn, J. M.

2002-04-01

Collisionless systems with inverse square interaction potentials and possible background confining potentials are considered for the case of spherical symmetry and in the Vlasov limit. The equilibrium is the most general, with single-particle distribution function dependence on both total energy E and total angular momentum L. A new formulation of the full integral-equation stability problem is developed. For a general spherical harmonic perturbation potential, the 3D stability problem is reduced to a 2D problem in an arbitrary central plane of motion, then to a small number of coupled 1D problems involving only the radius. Normal modes depend only on the total mode number l, as is shown directly by this new formulation, with all m degenerate. This method has been used for the Coulomb (repulsive) case.[1] An equilibrium family with uniform central (electron) density is found, and the low-frequency response computed to show that these solutions may provide stable confinement of a massive second (ion) species. These methods may be applied to a particle bunch in the beam frame, and some stability results appropriate to this case are presented. Application to the gravitational (attractive) case is also described, and some initial analytic results are presented. [1] D. C. Barnes, L. Chacón, J. M. Finn, “Equilibrium and Low-frequency Stability of a Uniform Density, Collisionless, Spherical Vlasov System,” submitted to Phys. of Plasmas (2002).

Experimental demonstration of low laser-plasma instabilities in gas-filled spherical hohlraums at laser injection angle designed for ignition target.

PubMed

Lan, Ke; Li, Zhichao; Xie, Xufei; Chen, Yao-Hua; Zheng, Chunyang; Zhai, Chuanlei; Hao, Liang; Yang, Dong; Huo, Wen Yi; Ren, Guoli; Peng, Xiaoshi; Xu, Tao; Li, Yulong; Li, Sanwei; Yang, Zhiwen; Guo, Liang; Hou, Lifei; Liu, Yonggang; Wei, Huiyue; Liu, Xiangming; Cha, Weiyi; Jiang, Xiaohua; Mei, Yu; Li, Yukun; Deng, Keli; Yuan, Zheng; Zhan, Xiayu; Zhang, Haijun; Jiang, Baibin; Zhang, Wei; Deng, Xuewei; Liu, Jie; Du, Kai; Ding, Yongkun; Wei, Xiaofeng; Zheng, Wanguo; Chen, Xiaodong; Campbell, E M; He, Xian-Tu

2017-03-01

Octahedral spherical hohlraums with a single laser ring at an injection angle of 55^{∘} are attractive concepts for laser indirect drive due to the potential for achieving the x-ray drive symmetry required for high convergence implosions. Laser-plasma instabilities, however, are a concern given the long laser propagation path in such hohlraums. Significant stimulated Raman scattering has been observed in cylindrical hohlraums with similar laser propagation paths during the ignition campaign on the National Ignition Facility (NIF). In this Rapid Communication, experiments demonstrating low levels of laser-driven plasma instability (LPI) in spherical hohlraums with a laser injection angle of 55^{∘} are reported and compared to that observed with cylindrical hohlraums with injection angles of 28.5^{∘} and 55^{∘}, similar to that of the NIF. Significant LPI is observed with the laser injection of 28.5^{∘} in the cylindrical hohlraum where the propagation path is similar to the 55^{∘} injection angle for the spherical hohlraum. The experiments are performed on the SGIII laser facility with a total 0.35-μm incident energy of 93 kJ in a 3 nsec pulse. These experiments demonstrate the role of hohlraum geometry in LPI and demonstrate the need for systematic experiments for choosing the optimal configuration for ignition studies with indirect drive inertial confinement fusion.

Evaluation of immunohematologic routine methods using the new erythrocyte-magnetized technology on the QWALYS 2 system.

PubMed

Schoenfeld, Helge; Bulling, Katia; von Heymann, Christian; Neuner, Bruno; Kalus, Ulrich; Kiesewetter, Holger; Pruss, Axel

2009-07-01

QWALYS 2 is a fully automated system for ABO/D grouping, Rh phenotyping, K typing, and antibody screening (ABS). Its new erythrocyte-magnetized technology (EMT) is based on the use of magnetic nanoparticles and avoids centrifugation and washing steps. Overall 499 blood samples were tested with our routine blood bank methods for ABO/D grouping, 313 samples for Rh phenotyping and K typing (microtiter plates; Olympus PK 7200), and 478 samples for ABS (gel centrifugation technique, DiaMed). All samples were tested in parallel with the EMT. In 496 of 499 samples (99.4%), a complete concordance between the observed (QWALYS 2) and the expected results for ABO/D grouping was found. One sample with a weak A in an AB blood group and 2 samples with a weak D were not detected by the QWALYS system. Rh phenotyping and K tests revealed a 100% concordance. In the two ABS techniques, 427 samples were negative in both and 15 samples showed the same antibody specificity in both. Three immunoglobulin M antibodies were as expected negative in EMT and positive by DiaMed. In 32 cases (6.7%), false-positive reactions were observed by EMT due to 22 unspecific reactions (4.6%) and 10 lipemic or fibrinic plasmas (2.1%). One autoantibody was found by EMT only. The EMT is reliably suited to ABO/D grouping, Rh phenotyping, and K testing and is suitable to detect immunoglobulin G red blood cell alloantibodies as well. The rate of false-positive reactions in ABS due to lipemic and fibrinic samples needs to be reduced.

Standardized Profiling of The Membrane-Enriched Proteome of Mouse Dorsal Root Ganglia (DRG) Provides Novel Insights Into Chronic Pain.

PubMed

Rouwette, Tom; Sondermann, Julia; Avenali, Luca; Gomez-Varela, David; Schmidt, Manuela

2016-06-01

Chronic pain is a complex disease with limited treatment options. Several profiling efforts have been employed with the aim to dissect its molecular underpinnings. However, generated results are often inconsistent and nonoverlapping, which is largely because of inherent technical constraints. Emerging data-independent acquisition (DIA)-mass spectrometry (MS) has the potential to provide unbiased, reproducible and quantitative proteome maps - a prerequisite for standardization among experiments. Here, we designed a DIA-based proteomics workflow to profile changes in the abundance of dorsal root ganglia (DRG) proteins in two mouse models of chronic pain, inflammatory and neuropathic. We generated a DRG-specific spectral library containing 3067 DRG proteins, which enables their standardized quantification by means of DIA-MS in any laboratory. Using this resource, we profiled 2526 DRG proteins in each biological replicate of both chronic pain models and respective controls with unprecedented reproducibility. We detected numerous differentially regulated proteins, the majority of which exhibited pain model-specificity. Our approach recapitulates known biology and discovers dozens of proteins that have not been characterized in the somatosensory system before. Functional validation experiments and analysis of mouse pain behaviors demonstrate that indeed meaningful protein alterations were discovered. These results illustrate how the application of DIA-MS can open new avenues to achieve the long-awaited standardization in the molecular dissection of pathologies of the somatosensory system. Therefore, our findings provide a valuable framework to qualitatively extend our understanding of chronic pain and somatosensation. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Customized Consensus Spectral Library Building for Untargeted Quantitative Metabolomics Analysis with Data Independent Acquisition Mass Spectrometry and MetaboDIA Workflow.

PubMed

Chen, Gengbo; Walmsley, Scott; Cheung, Gemmy C M; Chen, Liyan; Cheng, Ching-Yu; Beuerman, Roger W; Wong, Tien Yin; Zhou, Lei; Choi, Hyungwon

2017-05-02

Data independent acquisition-mass spectrometry (DIA-MS) coupled with liquid chromatography is a promising approach for rapid, automatic sampling of MS/MS data in untargeted metabolomics. However, wide isolation windows in DIA-MS generate MS/MS spectra containing a mixed population of fragment ions together with their precursor ions. This precursor-fragment ion map in a comprehensive MS/MS spectral library is crucial for relative quantification of fragment ions uniquely representative of each precursor ion. However, existing reference libraries are not sufficient for this purpose since the fragmentation patterns of small molecules can vary in different instrument setups. Here we developed a bioinformatics workflow called MetaboDIA to build customized MS/MS spectral libraries using a user's own data dependent acquisition (DDA) data and to perform MS/MS-based quantification with DIA data, thus complementing conventional MS1-based quantification. MetaboDIA also allows users to build a spectral library directly from DIA data in studies of a large sample size. Using a marine algae data set, we show that quantification of fragment ions extracted with a customized MS/MS library can provide as reliable quantitative data as the direct quantification of precursor ions based on MS1 data. To test its applicability in complex samples, we applied MetaboDIA to a clinical serum metabolomics data set, where we built a DDA-based spectral library containing consensus spectra for 1829 compounds. We performed fragment ion quantification using DIA data using this library, yielding sensitive differential expression analysis.

Large gyres as a shallow-water asymptotic solution of Euler's equation in spherical coordinates

NASA Astrophysics Data System (ADS)

Constantin, A.; Johnson, R. S.

2017-04-01

Starting from the Euler equation expressed in a rotating frame in spherical coordinates, coupled with the equation of mass conservation and the appropriate boundary conditions, a thin-layer (i.e. shallow water) asymptotic approximation is developed. The analysis is driven by a single, overarching assumption based on the smallness of one parameter: the ratio of the average depth of the oceans to the radius of the Earth. Consistent with this, the magnitude of the vertical velocity component through the layer is necessarily much smaller than the horizontal components along the layer. A choice of the size of this speed ratio is made, which corresponds, roughly, to the observational data for gyres; thus the problem is characterized by, and reduced to an analysis based on, a single small parameter. The nonlinear leading-order problem retains all the rotational contributions of the moving frame, describing motion in a thin spherical shell. There are many solutions of this system, corresponding to different vorticities, all described by a novel vorticity equation: this couples the vorticity generated by the spin of the Earth with the underlying vorticity due to the movement of the oceans. Some explicit solutions are obtained, which exhibit gyre-like flows of any size; indeed, the technique developed here allows for many different choices of the flow field and of any suitable free-surface profile. We comment briefly on the next order problem, which provides the structure through the layer. Some observations about the new vorticity equation are given, and a brief indication of how these results can be extended is offered.

On the rate of black hole binary mergers in galactic nuclei due to dynamical hardening

NASA Astrophysics Data System (ADS)

Leigh, N. W. C.; Geller, A. M.; McKernan, B.; Ford, K. E. S.; Mac Low, M.-M.; Bellovary, J.; Haiman, Z.; Lyra, W.; Samsing, J.; O'Dowd, M.; Kocsis, B.; Endlich, S.

2018-03-01

We assess the contribution of dynamical hardening by direct three-body scattering interactions to the rate of stellar-mass black hole binary (BHB) mergers in galactic nuclei. We derive an analytic model for the single-binary encounter rate in a nucleus with spherical and disc components hosting a super-massive black hole (SMBH). We determine the total number of encounters NGW needed to harden a BHB to the point that inspiral due to gravitational wave emission occurs before the next three-body scattering event. This is done independently for both the spherical and disc components. Using a Monte Carlo approach, we refine our calculations for NGW to include gravitational wave emission between scattering events. For astrophysically plausible models, we find that typically NGW ≲ 10. We find two separate regimes for the efficient dynamical hardening of BHBs: (1) spherical star clusters with high central densities, low-velocity dispersions, and no significant Keplerian component and (2) migration traps in discs around SMBHs lacking any significant spherical stellar component in the vicinity of the migration trap, which is expected due to effective orbital inclination reduction of any spherical population by the disc. We also find a weak correlation between the ratio of the second-order velocity moment to velocity dispersion in galactic nuclei and the rate of BHB mergers, where this ratio is a proxy for the ratio between the rotation- and dispersion-supported components. Because discs enforce planar interactions that are efficient in hardening BHBs, particularly in migration traps, they have high merger rates that can contribute significantly to the rate of BHB mergers detected by the advanced Laser Interferometer Gravitational-Wave Observatory.

Performance of the rebuilt SUERC single-stage accelerator mass spectrometer

NASA Astrophysics Data System (ADS)

Shanks, Richard P.; Ascough, Philippa L.; Dougans, Andrew; Gallacher, Paul; Gulliver, Pauline; Rood, Dylan H.; Xu, Sheng; Freeman, Stewart P. H. T.

2015-10-01

The SUERC bipolar single-stage accelerator mass spectrometer (SSAMS) has been dismantled and rebuilt to accommodate an additional rotatable pre-accelerator electrostatic spherical analyser (ESA) and a second ion source injector. This is for the attachment of an experimental positive-ion electron cyclotron resonance (ECR) ion source in addition to a Cs-sputter source. The ESA significantly suppresses oxygen interference to radiocarbon detection, and remaining measurement interference is now thought to be from 13C injected as 13CH molecule scattering off the plates of a second original pre-detector ESA.

Solid Lubrication Fundamentals and Applications. Chapter 5; Abrasion: Plowing and Cutting

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

2001-01-01

Chapter 5 discusses abrasion, a common wear phenomenon of great economic importance. It has been estimated that 50% of the wear encountered in industry is due to abrasion. Also, it is the mechanism involved in the finishing of many surfaces. Experiments are described to help in understanding the complex abrasion process and in predicting friction and wear behavior in plowing and/or cutting. These experimental modelings and measurements used a single spherical pin (asperity) and a single wedge pin (asperity). Other two-body and three-body abrasion studies used hard abrasive particles.

Buoyancy-Driven Instabilities in Single-Bubble Sonoluminescence

NASA Technical Reports Server (NTRS)

Matula, Thomas J.

2003-01-01

The principal objectives of this study are to determine how gravity affects the emission of light from single-bubble sonoluminescence (SBSL), and whether or not the bubble extinction is directly related to gravity. Our experimental task involves designing glass or quartz spherical levitation cells that generate very stable SL bubbles. The cells must have minimized vibration, and some temperature control. The experimental system will reside in a light-tight enclosure. Aside from acceleration, the frequency, pressure amplitude, and light intensity must be measured. A computer program will be constructed to perform all aspects of the experiment.

Formation of quasi-single crystalline porous ZnO nanostructures with a single large cavity

NASA Astrophysics Data System (ADS)

Cho, Seungho; Kim, Semi; Jung, Dae-Won; Lee, Kun-Hong

2011-09-01

We report a method for synthesizing quasi-single crystalline porous ZnO nanostructures containing a single large cavity. The microwave-assisted route consists of a short (about 2 min) temperature ramping stage (from room temperature to 120 °C) and a stage in which the temperature is maintained at 120 °C for 2 h. The structures produced by this route were 200-480 nm in diameter. The morphological yields of this method were very high. The temperature- and time-dependent evolution of the synthesized powders and the effects of an additive, vitamin C, were studied. Spherical amorphous/polycrystalline structures (70-170 nm in diameter), which appeared transitorily, may play a key role in the formation of the single crystalline porous hollow ZnO nanostructures. Studies and characterization of the nanostructures suggested a possible mechanism for formation of the quasi-single crystalline porous ZnO nanostructures with an interior space.We report a method for synthesizing quasi-single crystalline porous ZnO nanostructures containing a single large cavity. The microwave-assisted route consists of a short (about 2 min) temperature ramping stage (from room temperature to 120 °C) and a stage in which the temperature is maintained at 120 °C for 2 h. The structures produced by this route were 200-480 nm in diameter. The morphological yields of this method were very high. The temperature- and time-dependent evolution of the synthesized powders and the effects of an additive, vitamin C, were studied. Spherical amorphous/polycrystalline structures (70-170 nm in diameter), which appeared transitorily, may play a key role in the formation of the single crystalline porous hollow ZnO nanostructures. Studies and characterization of the nanostructures suggested a possible mechanism for formation of the quasi-single crystalline porous ZnO nanostructures with an interior space. Electronic supplementary information (ESI) available: TEM images and the corresponding SAED image of a ZnO nanostructure synthesized from the reaction without l(+)-ascorbic acid at the 85 °C time point (Fig. S1). See DOI: 10.1039/c1nr10609k

Directional Bleb Formation in Spherical Cells under Temperature Gradient

PubMed Central

Oyama, Kotaro; Arai, Tomomi; Isaka, Akira; Sekiguchi, Taku; Itoh, Hideki; Seto, Yusuke; Miyazaki, Makito; Itabashi, Takeshi; Ohki, Takashi; Suzuki, Madoka; Ishiwata, Shin'ichi

2015-01-01

Living cells sense absolute temperature and temporal changes in temperature using biological thermosensors such as ion channels. Here, we reveal, to our knowledge, a novel mechanism of sensing spatial temperature gradients within single cells. Spherical mitotic cells form directional membrane extensions (polar blebs) under sharp temperature gradients (≥∼0.065°C μm−1; 1.3°C temperature difference within a cell), which are created by local heating with a focused 1455-nm laser beam under an optical microscope. On the other hand, multiple nondirectional blebs are formed under gradual temperature gradients or uniform heating. During heating, the distribution of actomyosin complexes becomes inhomogeneous due to a break in the symmetry of its contractile force, highlighting the role of the actomyosin complex as a sensor of local temperature gradients. PMID:26200871

Spectrally controlled interferometry for measurements of flat and spherical optics

NASA Astrophysics Data System (ADS)

Salsbury, Chase; Olszak, Artur G.

2017-10-01

Conventional interferometry is widely used to measure spherical and at surfaces with nanometer level precision but is plagued by back reflections. We describe a new method of isolating the measurement surface by controlling spectral properties of the source (Spectrally Controlled Interferometry - SCI). Using spectral modulation of the interferometer's source enables formation of localized fringes where the optical path difference is non-zero. As a consequence it becomes possible to form white-light like fringes in common path interferometers, such as the Fizeau. The proposed setup does not require mechanical phase shifting, resulting in simpler instruments and the ability to upgrade existing interferometers. Furthermore, it allows absolute measurement of distance, including radius of curvature of lenses in a single setup with possibility of improving the throughput and removing some modes of failure.

Steps Toward an EOS-Era Aerosol Air Mass Type Climatology

NASA Technical Reports Server (NTRS)

Kahn, Ralph A.

2012-01-01

We still have a way to go to develop a global climatology of aerosol type from the EOS-era satellite data record that currently spans more than 12 years of observations. We have demonstrated the ability to retrieve aerosol type regionally, providing a classification based on the combined constraints on particle size, shape, and single-scattering albedo (SSA) from the MISR instrument. Under good but not necessarily ideal conditions, the MISR data can distinguish three-to-five size bins, two-to-four bins in SSA, and spherical vs. non-spherical particles. However, retrieval sensitivity varies enormously with scene conditions. So, for example, there is less information about aerosol type when the mid-visible aerosol optical depth (AOD) is less that about 0.15 or 0.2.

X-ray imaging crystal spectrometer for extended X-ray sources

DOEpatents

Bitter, Manfred L.; Fraenkel, Ben; Gorman, James L.; Hill, Kenneth W.; Roquemore, A. Lane; Stodiek, Wolfgang; von Goeler, Schweickhard E.

2001-01-01

Spherically or toroidally curved, double focusing crystals are used in a spectrometer for X-ray diagnostics of an extended X-ray source such as a hot plasma produced in a tokomak fusion experiment to provide spatially and temporally resolved data on plasma parameters using the imaging properties for Bragg angles near 45. For a Bragg angle of 45.degree., the spherical crystal focuses a bundle of near parallel X-rays (the cross section of which is determined by the cross section of the crystal) from the plasma to a point on a detector, with parallel rays inclined to the main plain of diffraction focused to different points on the detector. Thus, it is possible to radially image the plasma X-ray emission in different wavelengths simultaneously with a single crystal.

Self-assembly of an amphiphilic macromolecule under spherical confinement: An efficient route to generate hollow nanospheres

NASA Astrophysics Data System (ADS)

Glagoleva, A. A.; Vasilevskaya, V. V.; Yoshikawa, K.; Khokhlov, A. R.

2013-12-01

In general, bio-macromolecules are composed of hydrophilic and hydrophobic moieties and are confined within small cavities, such as cell membranes and intracellular organelles. Here, we studied the self-organization of macromolecules having groups with different affinities to solvents under spherical nano-scale confinement by means of computer modeling. It is shown that depending on the interaction parameters of monomer units composed of side- and main-chain monomer groups along a single linear macromolecule and on cavity size, such amphiphilic polymers undergo the conformational transitions between hollow nanospheres, rod-like and folded cylindrical structures, and a necklace conformation with and without a particular ordering of beads. The diagram of the conformations in the variables the incompatibility parameter of monomer units and the cavity radius is constructed.

A space-based concept for a collision warning sensor

NASA Technical Reports Server (NTRS)

Talent, David L.; Vilas, Faith

1990-01-01

This paper describes a concept for a space-based collision warning sensor experiment, the Debris Collision Warning Sensor (DCWS) experiment, in which the sensor will rely on passive sensing of debris in optical and IR passband. The DCWS experiment will be carried out under various conditions of solar phase angle and pass geometry; debris from 1.5 m to 1 mm diam will be observable. The mission characteristics include inclination in the 55-60 deg range and an altitude of about 500 km. The results of the DCWS experiment will be used to generate collision warning scenarios for the Space Station Freedom.

Calculated shock pressures in the aquarium test

NASA Astrophysics Data System (ADS)

Johnson, J. N.

1982-04-01

A new method of analysis has been developed for determintion of shock pressures in aquarium tests on commercial explosives. This test consists of photographing the expanding cylindrical tube wall (which contains the detonation products) and the shock wave in water surrounding the explosive charge. By making a least-squares fit to the shock-front data, it is possible to determine the peak shock-front pressure as a function of distance from the cylinder wall. This has been done for 10-cm and 20-cm-diam ANFO (ammonium nitrate/fuel oil) and aluminized ANFO (7.5 wt% Al) aquarium test data.

Synthesis and characterization of Ru-Ti[sub 4]O[sub 7] microelectrode arrays

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

He, L.; Franzen, H.F.; Vitt, J.E.

1994-04-01

A synthesis is described for Ru microelectrode arrays within a conductive Ti[sub 4]O[sub 7] ceramic matrix. Data obtained by X-ray diffractometry and scanning electron microscopy are consistent with the existence of heterogeneous mixtures of Ru particles (ca. 0.8 [mu]m diam) within the Ti[sub 4]O[sub 7] matrices. No mixed metal oxides or other new compounds are detected. Rotated disk electrodes (RDEs) constructed from the Ru-Ti[sub 4]O[sub 7] materials are compared on the basis of their voltammetric response for the oxidations of I[sup [minus

Acoustic tests of a 15.2 centimeter-diameter potential flow convergent nozzle

NASA Technical Reports Server (NTRS)

Karchmer, A. M.; Dorsch, R. G.; Friedman, R.

1974-01-01

An experimental investigation of the jet noise radiated to the far field from a 15.2-cm-diam potential flow convergent nozzle has been conducted. Tests were made with unheated airflow over a range of subsonic nozzle exhaust velocities from 62 to 310m/sec. Mean and turbulent velocity measurements in the flow field of the nozzle exhaust indicated no apparent flow anomalies. Acoustic measurements yielded data uncontaminated by internal and/or background noise to velocities as low as 152m/sec. Finally, no significantly different acoustic characteristics between the potential flow nozzle and simple convergent nozzles were found.

Static-thrust Investigation of Full-scale PV-2 Helicopter Rotors Having NACA 0012.6 and 23012.6 Airfoil Sections

NASA Technical Reports Server (NTRS)

Lipson, Stanley

1946-01-01

An investigation was conducted to compare the performance of two 25-ft-diam rotors which had identical dimensions and were similar in construction but different in blade airfoil-sections. Tests were conducted at indicated blade pitch angles from 3 degrees to 11.5 degrees and rotor speeds of 200, 290, and 371 rpm. The 23012.6 rotor required 2 percent less power to hover than the 0012.6. At thrust coefficients above design, the performance of the 23012.6 became better than the 0012.6 rotor.

Systems Engineering Body of Knowledge and Its Integration with Software Engineering

DTIC Science & Technology

2011-05-01

e pro ess ona  soc e es  y  end of 2012. 801/27/2010 4/25/2011 9 Topic 2 (Article Title)Part 1 Related Topics Article Structure Lorem ipsum dolor  sit...amet[1], consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim...veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor [2] in

Single-shot imaging with higher-dimensional encoding using magnetic field monitoring and concomitant field correction.

PubMed

Testud, Frederik; Gallichan, Daniel; Layton, Kelvin J; Barmet, Christoph; Welz, Anna M; Dewdney, Andrew; Cocosco, Chris A; Pruessmann, Klaas P; Hennig, Jürgen; Zaitsev, Maxim

2015-03-01

PatLoc (Parallel Imaging Technique using Localized Gradients) accelerates imaging and introduces a resolution variation across the field-of-view. Higher-dimensional encoding employs more spatial encoding magnetic fields (SEMs) than the corresponding image dimensionality requires, e.g. by applying two quadratic and two linear spatial encoding magnetic fields to reconstruct a 2D image. Images acquired with higher-dimensional single-shot trajectories can exhibit strong artifacts and geometric distortions. In this work, the source of these artifacts is analyzed and a reliable correction strategy is derived. A dynamic field camera was built for encoding field calibration. Concomitant fields of linear and nonlinear spatial encoding magnetic fields were analyzed. A combined basis consisting of spherical harmonics and concomitant terms was proposed and used for encoding field calibration and image reconstruction. A good agreement between the analytical solution for the concomitant fields and the magnetic field simulations of the custom-built PatLoc SEM coil was observed. Substantial image quality improvements were obtained using a dynamic field camera for encoding field calibration combined with the proposed combined basis. The importance of trajectory calibration for single-shot higher-dimensional encoding is demonstrated using the combined basis including spherical harmonics and concomitant terms, which treats the concomitant fields as an integral part of the encoding. © 2014 Wiley Periodicals, Inc.

An Astrometric Facility For Planetary Detection On The Space Station

NASA Astrophysics Data System (ADS)

Nishioka, Kenji; Scargle, Jeffrey D.; Givens, John J.

1987-09-01

An Astrometric Telescope Facility (ATF) for planetary detection is being studied as a potential Space Station initial operating capability payload. The primary science objective of this mission is the detection and study of planetary systems around other stars. In addition, the facility will be capable of other astrometric measurements such as stellar motions of other galaxies and highly precise direct measurement of stellar distances within the Milky Way Galaxy. This paper summarizes the results of a recently completed ATF preliminary systems definition study. Results of this study indicate that the preliminary concept for the facility is fully capable of meeting the science objectives without the development of any new technologies. This preliminary systems study started with the following basic assumptions: 1) the facility will be placed in orbit by a single Shuttle launch, 2) the Space Station will provide a coarse pointing system , electrical power, communications, assembly and checkout, maintenance and refurbishment services, and 3) the facility will be operated from a ground facility. With these assumptions and the science performance requirements a preliminary "strawman" facility was designed. The strawman facility design with a prime-focus telescope of 1.25-m aperture, f-ratio of 13 and a single prime-focus instrument was chosen to minimize random and systemmatic errors. Total facility mass is 5100 kg and overall dimensions are 1.85-m diam by 21.5-m long. A simple straightforward operations approach has been developed for ATF. A real-time facility control is not normally required, but does maintain a near real-time ground monitoring capability for facility and science data stream on a full-time basis. Facility observational sequences are normally loaded once a week. In addition, the preliminary system is designed to be fail-safe and single-fault tolerant. Routine interactions by the Space Station crew with ATF will not be necessary, but onboard controls are provided for crew override as required for emergencies and maintenance.

Retinal response of Macaca mulatta to picosecond laser pulses of varying energy and spot size.

PubMed

Roach, William P; Cain, Clarence P; Narayan, Drew G; Noojin, Gary D; Boppart, Stephen A; Birngruber, Reginald; Fujimoto, James G; Toth, Cynthia A

2004-01-01

We investigate the relationship between the laser beam at the retina (spot size) and the extent of retinal injury from single ultrashort laser pulses. From previous studies it is believed that the retinal effect of single 3-ps laser pulses should vary in extent and location, depending on the occurrence of laser-induced breakdown (LIB) at the site of laser delivery. Single 3-ps pulses of 580-nm laser energy are delivered over a range of spot sizes to the retina of Macaca mulatta. The retinal response is captured sequentially with optical coherence tomography (OCT). The in vivo OCT images and the extent of pathology on final microscopic sections of the laser site are compared. With delivery of a laser pulse with peak irradiance greater than that required for LIB, OCT and light micrographs demonstrate inner retinal injury with many intraretinal and/or vitreous hemorrhages. In contrast, broad outer retinal injury with minimal to no choriocapillaris effect is seen after delivery of laser pulses to a larger retinal area (60 to 300 microm diam) when peak irradiance is less than that required for LIB. The broader lesions extend into the inner retina when higher energy delivery produces intraretinal injury. Microscopic examination of stained fixed tissues provide better resolution of retinal morphology than OCT. OCT provides less resolution but could be guided over an in vivo, visible retinal lesion for repeated sampling over time during the evolution of the lesion formation. For 3-ps visible wavelength laser pulses, varying the spot size and laser energy directly affects the extent of retinal injury. This again is believed to be partly due to the onset of LIB, as seen in previous studies. Spot-size dependence should be considered when comparing studies of retinal effects or when pursuing a specific retinal effect from ultrashort laser pulses. Copyright 2004 Society of Photo-Optical Instrumentation Engineers.

Not spreading in reverse: The dewetting of a liquid film into a single drop

PubMed Central

Edwards, Andrew M. J.; Ledesma-Aguilar, Rodrigo; Newton, Michael I.; Brown, Carl V.; McHale, Glen

2016-01-01

Wetting and dewetting are both fundamental modes of motion of liquids on solid surfaces. They are critically important for processes in biology, chemistry, and engineering, such as drying, coating, and lubrication. However, recent progress in wetting, which has led to new fields such as superhydrophobicity and liquid marbles, has not been matched by dewetting. A significant problem has been the inability to study the model system of a uniform film dewetting from a nonwetting surface to a single macroscopic droplet—a barrier that does not exist for the reverse wetting process of a droplet spreading into a film. We report the dewetting of a dielectrophoresis-induced film into a single equilibrium droplet. The emergent picture of the full dewetting dynamics is of an initial regime, where a liquid rim recedes at constant speed and constant dynamic contact angle, followed by a relatively short exponential relaxation of a spherical cap shape. This sharply contrasts with the reverse wetting process, where a spreading droplet follows a smooth sequence of spherical cap shapes. Complementary numerical simulations and a hydrodynamic model reveal a local dewetting mechanism driven by the equilibrium contact angle, where contact line slip dominates the dewetting dynamics. Our conclusions can be used to understand a wide variety of processes involving liquid dewetting, such as drop rebound, condensation, and evaporation. In overcoming the barrier to studying single film-to-droplet dewetting, our results provide new approaches to fluid manipulation and uses of dewetting, such as inducing films of prescribed initial shapes and slip-controlled liquid retraction. PMID:27704042

Not spreading in reverse: The dewetting of a liquid film into a single drop.

PubMed

Edwards, Andrew M J; Ledesma-Aguilar, Rodrigo; Newton, Michael I; Brown, Carl V; McHale, Glen

2016-09-01

Wetting and dewetting are both fundamental modes of motion of liquids on solid surfaces. They are critically important for processes in biology, chemistry, and engineering, such as drying, coating, and lubrication. However, recent progress in wetting, which has led to new fields such as superhydrophobicity and liquid marbles, has not been matched by dewetting. A significant problem has been the inability to study the model system of a uniform film dewetting from a nonwetting surface to a single macroscopic droplet-a barrier that does not exist for the reverse wetting process of a droplet spreading into a film. We report the dewetting of a dielectrophoresis-induced film into a single equilibrium droplet. The emergent picture of the full dewetting dynamics is of an initial regime, where a liquid rim recedes at constant speed and constant dynamic contact angle, followed by a relatively short exponential relaxation of a spherical cap shape. This sharply contrasts with the reverse wetting process, where a spreading droplet follows a smooth sequence of spherical cap shapes. Complementary numerical simulations and a hydrodynamic model reveal a local dewetting mechanism driven by the equilibrium contact angle, where contact line slip dominates the dewetting dynamics. Our conclusions can be used to understand a wide variety of processes involving liquid dewetting, such as drop rebound, condensation, and evaporation. In overcoming the barrier to studying single film-to-droplet dewetting, our results provide new approaches to fluid manipulation and uses of dewetting, such as inducing films of prescribed initial shapes and slip-controlled liquid retraction.

On Spectral Invariance of Single Scattering Albedo for Weakly Absorbing Wavelengths

NASA Technical Reports Server (NTRS)

Marshak, Alexander; Knyazikhin, Yuri; Chiu, J. Christine; Wiscombe, Warren J.

2011-01-01

This note shows that for water droplets at weakly absorbing wavelengths, the ratio omega(sub O lambda(r))/omega(sub O lambda(r(sub O)) of two single scattering albedo spectra, omega(sub O lambda(r) and omega(sub O lambda(r (sub O)), is a linear function of omega(sub O lambda(r). The slope and intercept of the linear function are wavelength independent and sum to unity. This relationship allows for a representation of any single scattering albedo omega(sub O lambda(r) via one known spectrum omega(sub O lambda(r(sub O)). The note provides a simple physical explanation of the discovered relationship. In addition to water droplets, similar linear relationships were found for the single scattering albedo of non-spherical ice crystals.

Quantum Entanglement in Optical Lattice Systems

DTIC Science & Technology

2015-02-18

Zitterbewegung oscillation was first predicted by Schroedinger in 1930 for relativistic Dirac electrons where it arises from the interference...magnetic gradient. The gradient affected the Rabi cycling rate, leading to a phase winding along the long axis of the cigar -shaped BEC. While the single...approach is applicable to spherically symmetric, strictly two- dimensional, strictly one-dimensional, cigar -shaped, and pancake-shaped traps and has

Constructing spherical panoramas of a bladder phantom from endoscopic video using bundle adjustment

NASA Astrophysics Data System (ADS)

Soper, Timothy D.; Chandler, John E.; Porter, Michael P.; Seibel, Eric J.

2011-03-01

The high recurrence rate of bladder cancer requires patients to undergo frequent surveillance screenings over their lifetime following initial diagnosis and resection. Our laboratory is developing panoramic stitching software that would compile several minutes of cystoscopic video into a single panoramic image, covering the entire bladder, for review by an urolgist at a later time or remote location. Global alignment of video frames is achieved by using a bundle adjuster that simultaneously recovers both the 3D structure of the bladder as well as the scope motion using only the video frames as input. The result of the algorithm is a complete 360° spherical panorama of the outer surface. The details of the software algorithms are presented here along with results from both a virtual cystoscopy as well from real endoscopic imaging of a bladder phantom. The software successfully stitched several hundred video frames into a single panoramic with subpixel accuracy and with no knowledge of the intrinsic camera properties, such as focal length and radial distortion. In the discussion, we outline future work in development of the software as well as identifying factors pertinent to clinical translation of this technology.

Rigid spherical particles in highly turbulent Taylor-Couette flow

NASA Astrophysics Data System (ADS)

Bakhuis, Dennis; Verschoof, Ruben A.; Mathai, Varghese; Huisman, Sander G.; Lohse, Detlef; Sun, Chao

2016-11-01

Many industrial and maritime processes are subject to enormous frictional losses. Reducing these losses even slightly will already lead to large financial and environmental benefits. The understanding of the underlying physical mechanism of frictional drag reduction is still limited, for example, in bubbly drag reduction there is an ongoing debate whether deformability and bubble size are the key parameters. In this experimental study we report high precision torque measurements using rigid non-deformable spherical particles in highly turbulent Taylor-Couette flow with Reynolds numbers up to 2 ×106 . The particles are made of polystyrene with an average density of 1.036 g cm-3 and three different diameters: 8mm, 4mm, and 1.5mm. Particle volume fractions of up to 6% were used. By varying the particle diameter, density ratio of the particles and the working fluid, and volume fraction of the particles, the effect on the torque is compared to the single phase case. These systematic measurements show that adding rigid spherical particles only results in very minor drag reduction. This work is financially supported by Netherlands Organisation for Scientific Research (NWO) by VIDI Grant Number 13477.

On the generation of horizontal shear waves by underground explosions in jointed rocks

DOE PAGES

Vorobiev, Oleg; Ezzedine, Souheil; Antoun, Tarabay; ...

2015-02-04

This paper describes computational studies of non-spherical ground motions generated by spherical explosions in a heavily jointed granite formation. Various factors affecting the shear wave generation are considered, including joint spacing, orientation, persistence and properties. Simulations are performed both in 2D for a single joint set to elucidate the basic response mechanisms, and in 3D for multiple joint sets to realistically represent in situ conditions in a realistic geologic setting. The joints are modeled explicitly using both contact elements and weakness planes in the material. Simulations are performed both deterministically and stochastically to quantify the effects of geologic uncertainties onmore » near field ground motions. The mechanical properties of the rock and the joints as well as the joint spacing and orientation are taken from experimental test data and geophysical logs corresponding to the Climax Stock granitic outcrop, which is the geologic setting of the Source Physics Experiment (SPE). Agreement between simulation results and near field wave motion data from SPE enables newfound understanding of the origin and extent of non-spherical motions associated with underground explosions in fractured geologic media.« less

Two-fluid and magnetohydrodynamic modelling of magnetic reconnection in the MAST spherical tokamak and the solar corona

NASA Astrophysics Data System (ADS)

Browning, P. K.; Cardnell, S.; Evans, M.; Arese Lucini, F.; Lukin, V. S.; McClements, K. G.; Stanier, A.

2016-01-01

Twisted magnetic flux ropes are ubiquitous in laboratory and astrophysical plasmas, and the merging of such flux ropes through magnetic reconnection is an important mechanism for restructuring magnetic fields and releasing free magnetic energy. The merging-compression scenario is one possible start-up scheme for spherical tokamaks, which has been used on the Mega Amp Spherical Tokamak (MAST). Two current-carrying plasma rings or flux ropes approach each due to mutual attraction, forming a current sheet and subsequently merge through magnetic reconnection into a single plasma torus, with substantial plasma heating. Two-dimensional resistive and Hall-magnetohydrodynamic simulations of this process are reported, including a strong guide field. A model of the merging based on helicity-conserving relaxation to a minimum energy state is also presented, extending previous work to tight-aspect-ratio toroidal geometry. This model leads to a prediction of the final state of the merging, in good agreement with simulations and experiment, as well as the average temperature rise. A relaxation model of reconnection between two or more flux ropes in the solar corona is also described, allowing for different senses of twist, and the implications for heating of the solar corona are discussed.

Down and Out at Pacaya Volcano: A Glimpse of Magma Storage and Diking as Interpreted From GPS Geodesy

NASA Astrophysics Data System (ADS)

Lechner, H. N.; Waite, G. P.; Wauthier, D. C.; Escobar-Wolf, R. P.; Lopez-Hetland, B.

2017-12-01

Geodetic data from an eight-station GPS network at Pacaya volcano Guatemala allows us to produce a simple analytical model of deformation sources associated with the 2010 eruption and the eruptive period in 2013-2014. Deformation signals for both eruptive time-periods indicate downward vertical and outward horizontal motion at several stations surrounding the volcano. The objective of this research was to better understand the magmatic plumbing system and sources of this deformation. Because this down-and-out displacement is difficult to explain with a single source, we chose a model that includes a combination of a dike and spherical source. Our modelling suggests that deformation is dominated the inflation of a shallow dike seated high within the volcanic edifice and deflation of a deeper, spherical source below the SW flank of the volcano. The source parameters for the dike feature are in good agreement with the observed orientation of recent vent emplacements on the edifice as well the horizontal displacement, while the parameters for a deeper spherical source accommodate the downward vertical motion. This study presents GPS observations at Pacaya dating back to 2009 and provides a glimpse of simple models of possible deformation sources.

Understanding pop-ins in spherical nanoindentation

DOE PAGES

Pathak, Siddhartha; Riesterer, Jessica L.; Kalidindi, Surya R.; ...

2014-10-24

In this study, pop-ins, or sudden displacement-bursts at constant load in a nanoindentation test, are typically attributed to the difficulty of setting up potent dislocation sources in the very small indentation zones in these experiments. Such displacement (and strain) bursts would intuitively indicate a sharp drop in stress during the pop-in event itself. However, spherical indentation stress-strain curves routinely exhibit a high and stable indentation stress value during the pop-in, and the indentation stresses decrease only after a further finite amount of additional indentation displacement has been applied. In order to understand this discrepancy, we utilize a combination of interruptedmore » spherical indentation tests along with depth profiling of the residual indentation surfaces using in-situ atomic force microscopy (AFM) to study pop-ins. The AFM surface profile maps show that there is an asymmetric profile change over a limited region around the indentation contact area for a single pop-in; the asymmetry disappears upon further loading beyond the pop-in. A plausible sequence of physical processes (related to metal plasticity) occurring underneath the indenter during and immediately after the occurrence of the pop-in is proposed to explain these observations.« less

Two space scatterer formalism calculation of bulk parameters of thunderclouds

NASA Technical Reports Server (NTRS)

Phanord, Dieudonne D.

1994-01-01

In a previous study, we used a modified two-space scatterer formalism of Twersky to establish for a cloud modeled as a statistically homogeneous distribution of spherical water droplets, the dispersion relations that determine its bulk propagation numbers and bulk indexes of refraction in terms of the vector equivalent scattering amplitude and the dyadic scattering amplitude of the single water droplet in isolation. The results were specialized to the forward direction of scattering while demanding that the scatterers preserve the incident polarization. We apply this approach to obtain specific numerical values for the macroscopic parameters of the cloud. We work with a cloud of density rho = 100 cm(exp -3), a wavelength lambda = 0.7774 microns, and with spherical water droplets of common radius alpha = 10 microns. In addition, the scattering medium is divided into three parts, the medium outside the cloud, moist air (the medium inside the cloud but outside the droplets), and the medium inside the spherical water droplets. The results of this report are applicable to a cloud of any geometry since the boundary does not interfere with the calculations. Also, it is important to notice the plane wave nature of the incidence wave in the moist atmosphere.

Understanding pop-ins in spherical nanoindentation

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

Pathak, Siddhartha, E-mail: pathak@lanl.gov, E-mail: siddharthapathak@gmail.com; Riesterer, Jessica L.; Michler, Johann

2014-10-20

Pop-ins, or sudden displacement-bursts at constant load in a nanoindentation test, are typically attributed to the difficulty of setting up potent dislocation sources in the very small indentation zones in these experiments. Such displacement (and strain) bursts would intuitively indicate a sharp drop in stress during the pop-in event itself. However, spherical indentation stress-strain curves routinely exhibit a high and stable indentation stress value during the pop-in, and the indentation stresses decrease only after a further finite amount of additional indentation displacement has been applied. In order to understand this discrepancy, we utilize a combination of interrupted spherical indentation testsmore » along with depth profiling of the residual indentation surfaces using in-situ atomic force microscopy (AFM) to study pop-ins. The AFM surface profile maps show that there is an asymmetric profile change over a limited region around the indentation contact area for a single pop-in; the asymmetry disappears upon further loading beyond the pop-in. A plausible sequence of physical processes (related to metal plasticity) occurring underneath the indenter during and immediately after the occurrence of the pop-in is proposed to explain these observations.« less

A theory of frequency domain invariants: spherical harmonic identities for BRDF/lighting transfer and image consistency.

PubMed

Mahajan, Dhruv; Ramamoorthi, Ravi; Curless, Brian

2008-02-01

This paper develops a theory of frequency domain invariants in computer vision. We derive novel identities using spherical harmonics, which are the angular frequency domain analog to common spatial domain invariants such as reflectance ratios. These invariants are derived from the spherical harmonic convolution framework for reflection from a curved surface. Our identities apply in a number of canonical cases, including single and multiple images of objects under the same and different lighting conditions. One important case we consider is two different glossy objects in two different lighting environments. For this case, we derive a novel identity, independent of the specific lighting configurations or BRDFs, that allows us to directly estimate the fourth image if the other three are available. The identity can also be used as an invariant to detecttampering in the images. While this paper is primarily theoretical, it has the potential to lay the mathematical foundations for two important practical applications. First, we can develop more general algorithms for inverse rendering problems, which can directly relight and change material properties by transferring the BRDF or lighting from another object or illumination. Second, we can check the consistency of an image, to detect tampering or image splicing.

On the possibility of detecting local refractive index changes in optically transparent objects by means of a point nanoantenna attached to a fibre microaxicon

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

Kulchin, Yu N; Vitrik, O B; Kuchmizhak, A A

2014-10-31

It is shown theoretically that the use of the spectral registration of the dipole local plasmon resonance (DLPR) displacement in a single spherical gold nanoantenna, placed near the surface of a homogeneous dielectric medium, allows the mapping of extremely small variations (to 5 × 10{sup -4}) of the refractive index (RI) of this medium. Using the quasi-static approximation, we have developed an analytic model that allows evaluation of the spectral displacement of the nanoantenna DLPR depending on the variation in the medium refractive index. The point probe based on a fibre microaxicon with a gold spherical nanoantenna attached to itsmore » top is proposed that allows practical implementation of the developed RI scanning method. Numerical calculations of the probe characteristics using the time-domain finite-difference method are presented, and it is shown that for the case of a gold spherical nanoantenna of small size, comparable with the skin layer thickness in gold, the relative spectral shift value is in good agreement with the results obtained by using the developed analytic model. (laser applications and other topics in quantum electronics)« less

Tailoring shape and size of biogenic silver nanoparticles to enhance antimicrobial efficacy against MDR bacteria.

PubMed

Kumari, Madhuree; Pandey, Shipra; Giri, Ved Prakash; Bhattacharya, Arpita; Shukla, Richa; Mishra, Aradhana; Nautiyal, C S

2017-04-01

Spherical, rectangular, penta, and hexagonal silver nanoparticles of different dimensions were biosynthesized in an eco-friendly manner by biocontrol agent, Trichoderma viride by manipulating physical parameters, pH, temperature, and reaction time. The particles were characterized by UV-vis spectroscopy; Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM) and Fourier Transform Infra-red Spectroscopy (FTIR). Shape and size dependent antimicrobial activity of nanoparticles against human pathogens was observed. Maximum inhibition was found with spherical nanoparticles (2-5 nm) showing 40, 51, 43, 53.9 and 55.8% against Shigella sonnei, Escherichia coli, Serratia marcescens, Staphylococcus. aureus and Pseudomonas aeruginosa respectively, where as pentagonal and hexagonal nanoparticles (50-100 nm) demonstrated 32, 41, 31, 42.84 and 42.80% of inhibition as compared to control. Nanoparticles of different geometry and dimension established enhanced antagonistic activity against pathogens with all the tested antibiotics. Excellent antimicrobial efficacy was obtained with spherical nanoparticles of 2-5 nm with ampicillin and penicillin. Shape and size played major role in enhancing antimicrobial potential of silver nanoparticles, both singly and synergistically with antibiotics which can be exploited to combat the spread of multidrug resistant pathogens. Copyright © 2016. Published by Elsevier Ltd.

Single-mode, Rayleigh-Taylor growth-rate measurements on the OMEGA laser system

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

Knauer, J. P.; Betti, R.; Bradley, D. K.

2000-01-01

The results from a series of single-mode, Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five or six 351 nm laser beams overlapped with total intensities up to 2.5x10{sup 14} W/cm{sup 2}. Experiments were performed with both 3 ns ramp and 3 ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600 {mu}m diam region defined bymore » the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using throughfoil radiography and was detected with an x-ray framing camera for CH targets. Two-dimensional (2-D) hydrodynamic simulations (ORCHID) [R. L. McCrory and C. P. Verdon, in Inertial Confinement Fusion (Editrice Compositori, Bologna, 1989), pp. 83-124] of the growth of 20, 31, and 60 {mu}m wavelength perturbations were in good agreement with the experimental data when the experimental details, including noise, were included. The amplitude of the simulation optical depth is in good agreement with the experimental optical depth; therefore, great care must be taken when the growth rates are compared to dispersion formulas. Since the foil's initial condition just before it is accelerated is not that of a uniformly compressed foil, the optical density measurement does not accurately reflect the amplitude of the ablation surface but is affected by the initial nonuniform density profile. (c) 2000 American Institute of Physics.« less

Absolute Hugoniot measurements from a spherically convergent shock using x-ray radiography

NASA Astrophysics Data System (ADS)

Swift, Damian C.; Kritcher, Andrea L.; Hawreliak, James A.; Lazicki, Amy; MacPhee, Andrew; Bachmann, Benjamin; Döppner, Tilo; Nilsen, Joseph; Collins, Gilbert W.; Glenzer, Siegfried; Rothman, Stephen D.; Kraus, Dominik; Falcone, Roger W.

2018-05-01

The canonical high pressure equation of state measurement is to induce a shock wave in the sample material and measure two mechanical properties of the shocked material or shock wave. For accurate measurements, the experiment is normally designed to generate a planar shock which is as steady as possible in space and time, and a single state is measured. A converging shock strengthens as it propagates, so a range of shock pressures is induced in a single experiment. However, equation of state measurements must then account for spatial and temporal gradients. We have used x-ray radiography of spherically converging shocks to determine states along the shock Hugoniot. The radius-time history of the shock, and thus its speed, was measured by radiographing the position of the shock front as a function of time using an x-ray streak camera. The density profile of the shock was then inferred from the x-ray transmission at each instant of time. Simultaneous measurement of the density at the shock front and the shock speed determines an absolute mechanical Hugoniot state. The density profile was reconstructed using the known, unshocked density which strongly constrains the density jump at the shock front. The radiographic configuration and streak camera behavior were treated in detail to reduce systematic errors. Measurements were performed on the Omega and National Ignition Facility lasers, using a hohlraum to induce a spatially uniform drive over the outside of a solid, spherical sample and a laser-heated thermal plasma as an x-ray source for radiography. Absolute shock Hugoniot measurements were demonstrated for carbon-containing samples of different composition and initial density, up to temperatures at which K-shell ionization reduced the opacity behind the shock. Here we present the experimental method using measurements of polystyrene as an example.

Aerosol Airmass Type Mapping Over the Urban Mexico City Region From Space-based Multi-angle Imaging

NASA Technical Reports Server (NTRS)

Patadia, F.; Kahn, R. A.; Limbacher, J. A.; Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.

2013-01-01

Using Multi-angle Imaging SpectroRadiometer (MISR) and sub-orbital measurements from the 2006 INTEX-B/MILAGRO field campaign, in this study we explore MISR's ability to map different aerosol air mass types over the Mexico City metropolitan area. The aerosol air mass distinctions are based on shape, size and single scattering albedo retrievals from the MISR Research Aerosol Retrieval algorithm. In this region, the research algorithm identifies dust-dominated aerosol mixtures based on non-spherical particle shape, whereas spherical biomass burning and urban pollution particles are distinguished by particle size. Two distinct aerosol air mass types based on retrieved particle microphysical properties, and four spatially distributed aerosol air masses, are identified in the MISR data on 6 March 2006. The aerosol air mass type identification results are supported by coincident, airborne high-spectral-resolution lidar (HSRL) measurements. Aerosol optical depth (AOD) gradients are also consistent between the MISR and sub-orbital measurements, but particles having single-scattering albedo of approx. 0.7 at 558 nm must be included in the retrieval algorithm to produce good absolute AOD comparisons over pollution-dominated aerosol air masses. The MISR standard V22 AOD product, at 17.6 km resolution, captures the observed AOD gradients qualitatively, but retrievals at this coarse spatial scale and with limited spherical absorbing particle options underestimate AOD and do not retrieve particle properties adequately over this complex urban region. However, we demonstrate how AOD and aerosol type mapping can be accomplished with MISR data over complex urban regions, provided the retrieval is performed at sufficiently high spatial resolution, and with a rich enough set of aerosol components and mixtures.

Pulmonary tumor measurements from x-ray computed tomography in one, two, and three dimensions.

PubMed

Villemaire, Lauren; Owrangi, Amir M; Etemad-Rezai, Roya; Wilson, Laura; O'Riordan, Elaine; Keller, Harry; Driscoll, Brandon; Bauman, Glenn; Fenster, Aaron; Parraga, Grace

2011-11-01

We evaluated the accuracy and reproducibility of three-dimensional (3D) measurements of lung phantoms and patient tumors from x-ray computed tomography (CT) and compared these to one-dimensional (1D) and two-dimensional (2D) measurements. CT images of three spherical and three irregularly shaped tumor phantoms were evaluated by three observers who performed five repeated measurements. Additionally, three observers manually segmented 29 patient lung tumors five times each. Follow-up imaging was performed for 23 tumors and response criteria were compared. For a single subject, imaging was performed on nine occasions over 2 years to evaluate multidimensional tumor response. To evaluate measurement accuracy, we compared imaging measurements to ground truth using analysis of variance. For estimates of precision, intraobserver and interobserver coefficients of variation and intraclass correlations (ICC) were used. Linear regression and Pearson correlations were used to evaluate agreement and tumor response was descriptively compared. For spherical shaped phantoms, all measurements were highly accurate, but for irregularly shaped phantoms, only 3D measurements were in high agreement with ground truth measurements. All phantom and patient measurements showed high intra- and interobserver reproducibility (ICC >0.900). Over a 2-year period for a single patient, there was disagreement between tumor response classifications based on 3D measurements and those generated using 1D and 2D measurements. Tumor volume measurements were highly reproducible and accurate for irregular, spherical phantoms and patient tumors with nonuniform dimensions. Response classifications obtained from multidimensional measurements suggest that 3D measurements provide higher sensitivity to tumor response. Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.

Gold surface supported spherical liposome-gold nano-particle nano-composite for label free DNA sensing.

PubMed

Bhuvana, M; Narayanan, J Shankara; Dharuman, V; Teng, W; Hahn, J H; Jayakumar, K

2013-03-15

Immobilization of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) liposome-gold nano-particle (DOPE-AuNP) nano-composite covalently on 3-mercaptopropionic acid (MPA) on gold surface is demonstrated for the first time for electrochemical label free DNA sensing. Spherical nature of the DOPE on the MPA monolayer is confirmed by the appearance of sigmoidal voltammetric profile, characteristic behavior of linear diffusion, for the MPA-DOPE in presence of [Fe(CN)(6)](3-/4-) and [Ru(NH(3))(6)](3+) redox probes. The DOPE liposome vesicle fusion is prevented by electroless deposition of AuNP on the hydrophilic amine head groups of the DOPE. Immobilization of single stranded DNA (ssDNA) is made via simple gold-thiol linkage for DNA hybridization sensing in the presence of [Fe(CN)(6)](3-/4-). The sensor discriminates the hybridized (complementary target hybridized), un-hybridized (non-complementary target hybridized) and single base mismatch target hybridized surfaces sensitively and selectively without signal amplification. The lowest target DNA concentration detected is 0.1×10(-12)M. Cyclic voltammetry (CV), electrochemical impedance (EIS), differential pulse voltammetry (DPV) and quartz crystal microbalance (QCM) techniques are used for DNA sensing on DOPE-AuNP nano-composite. Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS) and Ultraviolet-Visible (UV) spectroscopic techniques are used to understand the interactions between the DOPE, AuNP and ssDNA. The results indicate the presence of an intact and well defined spherical DOPE-AuNP nano-composite on the gold surface. The method could be applied for fabrication of the surface based liposome-AuNP-DNA composite for cell transfection studies at reduced reagents and costs. Copyright © 2012 Elsevier B.V. All rights reserved.

Parameterization of single-scattering properties of snow

NASA Astrophysics Data System (ADS)

Räisänen, Petri; Kokhanovsky, Alexander; Guyot, Gwennole; Jourdan, Olivier; Nousiainen, Timo

2015-04-01

Snow consists of non-spherical ice grains of various shapes and sizes, which are surrounded by air and sometimes covered by films of liquid water. Still, in many studies, homogeneous spherical snow grains have been assumed in radiative transfer calculations, due to the convenience of using Mie theory. More recently, second-generation Koch fractals have been employed. While they produce a relatively flat scattering phase function typical of deformed non-spherical particles, this is still a rather ad-hoc choice. Here, angular scattering measurements for blowing snow conducted during the CLimate IMpacts of Short-Lived pollutants In the Polar region (CLIMSLIP) campaign at Ny Ålesund, Svalbard, are used to construct a reference phase function for snow. Based on this phase function, an optimized habit combination (OHC) consisting of severely rough (SR) droxtals, aggregates of SR plates and strongly distorted Koch fractals is selected. The single-scattering properties of snow are then computed for the OHC as a function of wavelength λ and snow grain volume-to-projected area equivalent radius rvp. Parameterization equations are developed for λ=0.199-2.7 μm and rvp = 10-2000 μm, which express the single-scattering co-albedo β, the asymmetry parameter g and the phase function as functions of the size parameter and the real and imaginary parts of the refractive index. Compared to the reference values computed for the OHC, the accuracy of the parameterization is very high for β and g. This is also true for the phase function parameterization, except for strongly absorbing cases (β > 0.3). Finally, we consider snow albedo and reflected radiances for the suggested snow optics parameterization, making comparisons with spheres and distorted Koch fractals. Further evaluation and validation of the proposed approach against (e.g.) bidirectional reflectance and polarization measurements for snow is planned. At any rate, it seems safe to assume that the OHC selected here provides a substantially better basis for representing the single-scattering properties of snow than spheres do. Moreover, the parameterizations developed here are analytic and simple to use, and they can also be applied to the treatment of dirty snow following (e.g.) the approach of Kokhanovsky (The Cryosphere, 7, 1325-1331, doi:10.5194/tc-7-1325-2013, 2013). This should make them an attractive option for use in radiative transfer applications involving snow.

MiSight Assessment Study Spain (MASS). A 2-year randomized clinical trial.

PubMed

Ruiz-Pomeda, Alicia; Pérez-Sánchez, Belén; Valls, Isabel; Prieto-Garrido, Francisco Luis; Gutiérrez-Ortega, Ramón; Villa-Collar, César

2018-05-01

To compare myopia progression in children randomized to MiSight contact lenses (CLs) versus children corrected with single-vision spectacles (SV) over a 2-year period. Subjects aged 8 to 12 with myopia (-0.75 to -4.00 D sphere) and astigmatism (< -1.00 D cylinder) were assigned to the lens study group (MiSight) or the control group (single vision). Measurements of visual acuity and subjective refraction were taken at 6-month intervals, and axial length, anterior chamber, corneal power, and cycloplegic autorefraction were measured at the baseline, 12-month, and 24-month visits. Eighty-nine subjects were recruited. Forty-fix children were assigned to the MiSight group, and 33 to the single-vision spectacle group. In total, 74 children completed the clinical trial, with the following parameters at the beginning of the study: n =  41 in the MiSight group (age: 11.01 ± 1.23 years, spherical equivalent: -2.16 ± 0.94 D, gender: male: 21, female: 20) and n = 33 in the single-vision group (age: 10.12 ± 1.38 years, spherical equivalent: -1.75 ± 0.94 D, gender: male: 12, female: 21). After 2 years of follow-up, myopia progressed slowly in the MiSight group compared to the control group (0.45 D vs 0.74 D, p < 0.001) and there was less axial elongation in the MiSight group compared to the single-vision group (0.28 mm vs 0.44 mm, p < 0.001). Therefore, use of MiSight CLs produced lower myopia progression (39.32%) and lower axial growth of the eye (36.04%) at 2 years compared to spectacle use. MiSight contact lens wear reduces axial elongation and myopia progression in comparison to distance single-vision spectacles in children. ClinicalTrials.gov Identifier: NCT01917110.

Electron correlation by polarization of interacting densities

NASA Astrophysics Data System (ADS)

Whitten, Jerry L.

2017-02-01

Coulomb interactions that occur in electronic structure calculations are correlated by allowing basis function components of the interacting densities to polarize dynamically, thereby reducing the magnitude of the interaction. Exchange integrals of molecular orbitals are not correlated. The modified Coulomb interactions are used in single-determinant or configuration interaction calculations. The objective is to account for dynamical correlation effects without explicitly introducing higher spherical harmonic functions into the molecular orbital basis. Molecular orbital densities are decomposed into a distribution of spherical components that conserve the charge and each of the interacting components is considered as a two-electron wavefunction embedded in the system acted on by an average field Hamiltonian plus r12-1. A method of avoiding redundancy is described. Applications to atoms, negative ions, and molecules representing different types of bonding and spin states are discussed.

Acoustic levitation in the presence of gravity

NASA Technical Reports Server (NTRS)

Collas, P.; Barmatz, M.; Shipley, C.

1989-01-01

The method of Gor'kov (1961) has been applied to derive general expressions for the total potential and force on a small spherical object in a resonant chamber in the presence of both acoustic and gravitational force fields. The levitation position is also determined in rectangular resonators for the simultaneous excitation of up to three acoustic modes, and the results are applied to the triple-axis acoustic levitator. The analysis is applied to rectangular, spherical, and cylindrical single-mode levitators that are arbitrarily oriented relative to the gravitational force field. Criteria are determined for isotropic force fields in rectangular and cylindrical resonators. It is demonstrated that an object will be situated within a volume of possible levitation positions at a point determined by the relative strength of the acoustic and gravitational fields and the orientation of the chamber relative to gravity.

Spectral evolution of distributed feedback laser of gold nanoparticles doped solid-state dye laser medium

NASA Astrophysics Data System (ADS)

An, N. T. M.; Lien, N. T. H.; Hoang, N. D.; Nghia, N. T.; Hoa, D. Q.

2017-10-01

Characteristics of suppressed relaxation oscillation of a distributed feedback dye laser (DFDL) based on the energy transfer process in a mixture of spherical gold nanoparticles-doped solid-state polymethylmetacrylate dissolved 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye was theoretically and experimentally studied. Single pulse generation regime of the DFDL can be obtained with a suitable gold nanoparticle concentration and ratio of pump power over lasing threshold. Numerical analysis and experimental approach showed that in this regime, the first-pulse laser pulsewidth is rather unchanged while varying the gold nanoparticles concentration in the range of 2.0 × 109-2.0 × 1010 par cm-3. The enhancement of first pulse and the suppression of the secondary pulses by bi-direction energy transfer of spherical gold nanoparticles were experimentally observed.

Heating efficiency dependency on size and morphology of magnetite nanoparticles

NASA Astrophysics Data System (ADS)

Parekh, Kinnari; Parmar, Harshida; Sharma, Vinay; Ramanujan, R. V.

2018-04-01

Different size magnetite nanoparticles ranging from superparamagnetic (9 nm) to single domain (27 nm) and multi domain (53 nm) were synthesized using chemical route. Morphology of these particles as seen from TEM images indicates shape change from spherical to cubic with the growth of particles. The saturation magnetization (σs) and Specific Loss Power (SLP) showed maximum for single domain size, 72 emu/g and 102 W/g, respectively then those of multi domain size particles. These samples show higher SLP at relatively low concentration, low frequency and low amplitude compared to samples prepared by other routes.

Direct observation of resonance scattering patterns in single silicon nanoparticles

NASA Astrophysics Data System (ADS)

Valuckas, Vytautas; Paniagua-Domínguez, Ramón; Fu, Yuan Hsing; Luk'yanchuk, Boris; Kuznetsov, Arseniy I.

2017-02-01

We present the first direct observation of the scattering patterns of electric and magnetic dipole resonances excited in a single silicon nanosphere. Almost perfectly spherical silicon nanoparticles were fabricated and deposited on a 30 nm-thick silicon nitride membrane in an attempt to minimize particle—substrate interaction. Measurements were carried out at visible wavelengths by means of the Fourier microscopy in a dark-field illumination setup. The obtained back-focal plane images clearly reveal the characteristic scattering patterns associated with each resonance and are found to be in a good agreement with the simulated results.

Computer-generated formulas for three-center nuclear-attraction integrals (electrostatic potential) for Slater-type orbitals

NASA Technical Reports Server (NTRS)

Jones, H. W.

1984-01-01

The computer-assisted C-matrix, Loewdin-alpha-function, single-center expansion method in spherical harmonics has been applied to the three-center nuclear-attraction integral (potential due to the product of separated Slater-type orbitals). Exact formulas are produced for 13 terms of an infinite series that permits evaluation to ten decimal digits of an example using 1s orbitals.

An Ultrasound Image-Based Dynamic Fusion Modeling Method for Predicting the Quantitative Impact of In Vivo Liver Motion on Intraoperative HIFU Therapies: Investigations in a Porcine Model

PubMed Central

N'Djin, W. Apoutou; Chapelon, Jean-Yves; Melodelima, David

2015-01-01

Organ motion is a key component in the treatment of abdominal tumors by High Intensity Focused Ultrasound (HIFU), since it may influence the safety, efficacy and treatment time. Here we report the development in a porcine model of an Ultrasound (US) image-based dynamic fusion modeling method for predicting the effect of in vivo motion on intraoperative HIFU treatments performed in the liver in conjunction with surgery. A speckle tracking method was used on US images to quantify in vivo liver motions occurring intraoperatively during breathing and apnea. A fusion modeling of HIFU treatments was implemented by merging dynamic in vivo motion data in a numerical modeling of HIFU treatments. Two HIFU strategies were studied: a spherical focusing delivering 49 juxtapositions of 5-second HIFU exposures and a toroidal focusing using 1 single 40-second HIFU exposure. Liver motions during breathing were spatially homogenous and could be approximated to a rigid motion mainly encountered in the cranial-caudal direction (f = 0.20Hz, magnitude >13mm). Elastic liver motions due to cardiovascular activity, although negligible, were detectable near millimeter-wide sus-hepatic veins (f = 0.96Hz, magnitude <1mm). The fusion modeling quantified the deleterious effects of respiratory motions on the size and homogeneity of a standard “cigar-shaped” millimetric lesion usually predicted after a 5-second single spherical HIFU exposure in stationary tissues (Dice Similarity Coefficient: DSC<45%). This method assessed the ability to enlarge HIFU ablations during respiration, either by juxtaposing “cigar-shaped” lesions with spherical HIFU exposures, or by generating one large single lesion with toroidal HIFU exposures (DSC>75%). Fusion modeling predictions were preliminarily validated in vivo and showed the potential of using a long-duration toroidal HIFU exposure to accelerate the ablation process during breathing (from 0.5 to 6 cm3·min-1). To improve HIFU treatment control, dynamic fusion modeling may be interesting for assessing numerically focusing strategies and motion compensation techniques in more realistic conditions. PMID:26398366

Applicability of the single equivalent point dipole model to represent a spatially distributed bio-electrical source

NASA Technical Reports Server (NTRS)

Armoundas, A. A.; Feldman, A. B.; Sherman, D. A.; Cohen, R. J.

2001-01-01

Although the single equivalent point dipole model has been used to represent well-localised bio-electrical sources, in realistic situations the source is distributed. Consequently, position estimates of point dipoles determined by inverse algorithms suffer from systematic error due to the non-exact applicability of the inverse model. In realistic situations, this systematic error cannot be avoided, a limitation that is independent of the complexity of the torso model used. This study quantitatively investigates the intrinsic limitations in the assignment of a location to the equivalent dipole due to distributed electrical source. To simulate arrhythmic activity in the heart, a model of a wave of depolarisation spreading from a focal source over the surface of a spherical shell is used. The activity is represented by a sequence of concentric belt sources (obtained by slicing the shell with a sequence of parallel plane pairs), with constant dipole moment per unit length (circumferentially) directed parallel to the propagation direction. The distributed source is represented by N dipoles at equal arc lengths along the belt. The sum of the dipole potentials is calculated at predefined electrode locations. The inverse problem involves finding a single equivalent point dipole that best reproduces the electrode potentials due to the distributed source. The inverse problem is implemented by minimising the chi2 per degree of freedom. It is found that the trajectory traced by the equivalent dipole is sensitive to the location of the spherical shell relative to the fixed electrodes. It is shown that this trajectory does not coincide with the sequence of geometrical centres of the consecutive belt sources. For distributed sources within a bounded spherical medium, displaced from the sphere's centre by 40% of the sphere's radius, it is found that the error in the equivalent dipole location varies from 3 to 20% for sources with size between 5 and 50% of the sphere's radius. Finally, a method is devised to obtain the size of the distributed source during the cardiac cycle.

Rapid calculation of acoustic fields from arbitrary continuous-wave sources.

PubMed

Treeby, Bradley E; Budisky, Jakub; Wise, Elliott S; Jaros, Jiri; Cox, B T

2018-01-01

A Green's function solution is derived for calculating the acoustic field generated by phased array transducers of arbitrary shape when driven by a single frequency continuous wave excitation with spatially varying amplitude and phase. The solution is based on the Green's function for the homogeneous wave equation expressed in the spatial frequency domain or k-space. The temporal convolution integral is solved analytically, and the remaining integrals are expressed in the form of the spatial Fourier transform. This allows the acoustic pressure for all spatial positions to be calculated in a single step using two fast Fourier transforms. The model is demonstrated through several numerical examples, including single element rectangular and spherically focused bowl transducers, and multi-element linear and hemispherical arrays.

Low temperature magnetic structure of CeRhIn 5 by neutron diffraction on absorption-optimized samples

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

Fobes, David M.; Bauer, Eric Dietzgen; Thompson, Joe David

Here, two aspects of the ambient pressure magnetic structure of heavy fermion material CeRhIn 5 have remained under some debate since its discovery: whether the structure is indeed an incommensurate helix or a spin density wave, and what is the precise magnitude of the ordered magnetic moment. By using a single crystal sample optimized for hot neutrons to minimize neutron absorption by Rh and In, here we report an ordered moment ofmore » $$m=0.54(2)\\,{{\\mu}_{\\text{B}}}$$. In addition, by using spherical neutron polarimetry measurements on a similar single crystal sample, we have confirmed the helical nature of the magnetic structure, and identified a single chiral domain.« less

Low temperature magnetic structure of CeRhIn 5 by neutron diffraction on absorption-optimized samples

DOE PAGES

Fobes, David M.; Bauer, Eric Dietzgen; Thompson, Joe David; ...

2017-03-28

Here, two aspects of the ambient pressure magnetic structure of heavy fermion material CeRhIn 5 have remained under some debate since its discovery: whether the structure is indeed an incommensurate helix or a spin density wave, and what is the precise magnitude of the ordered magnetic moment. By using a single crystal sample optimized for hot neutrons to minimize neutron absorption by Rh and In, here we report an ordered moment ofmore » $$m=0.54(2)\\,{{\\mu}_{\\text{B}}}$$. In addition, by using spherical neutron polarimetry measurements on a similar single crystal sample, we have confirmed the helical nature of the magnetic structure, and identified a single chiral domain.« less

Enhanced kidney stone fragmentation by short delay tandem conventional and modified lithotriptor shock waves: a numerical analysis.

PubMed

Tham, Leung-Mun; Lee, Heow Pueh; Lu, Chun

2007-07-01

We evaluated the effectiveness of modified lithotriptor shock waves using computer models. Finite element models were used to simulate the propagation of lithotriptor shock waves in human renal calculi in vivo. Kidney stones were assumed to be spherical, homogeneous, isotropic and linearly elastic, and immersed in a continuum fluid. Single and tandem shock wave pulses modified to intensify the collapse of cavitation bubbles near the stone surface to increase fragmentation efficiency and suppress the expansion of intraluminal bubbles for decreased vascular injury were analyzed. The effectiveness of the modified shock waves was assessed by comparing the states of loading in the renal calculi induced by these shock waves to those produced by conventional shock waves. Our numerical simulations revealed that modified shock waves produced marginally lower stresses in spherical renal calculi than those produced by conventional shock waves. Tandem pulses of conventional or modified shock waves produced peak stresses in the front and back halves of the renal calculi. However, the single shock wave pulses generated significant peak stresses in only the back halves of the renal calculi. Our numerical simulations suggest that for direct stress wave induced fragmentation modified shock waves should be as effective as conventional shock waves for fragmenting kidney stones. Also, with a small interval of 20 microseconds between the pulses tandem pulse lithotripsy using modified or conventional shock waves could be considerably more effective than single pulse lithotripsy for fragmenting kidney stones.

Splitting Fermi Surfaces and Heavy Electronic States in Non-Centrosymmetric U3Ni3Sn4

NASA Astrophysics Data System (ADS)

Maurya, Arvind; Harima, Hisatomo; Nakamura, Ai; Shimizu, Yusei; Homma, Yoshiya; Li, DeXin; Honda, Fuminori; Sato, Yoshiki J.; Aoki, Dai

2018-04-01

We report the single-crystal growth of the non-centrosymmetric paramagnet U3Ni3Sn4 by the Bridgman method and the Fermi surface properties detected by de Haas-van Alphen (dHvA) experiments. We have also investigated single-crystal U3Ni3Sn4 by single-crystal X-ray diffraction, magnetization, electrical resistivity, and heat capacity measurements. The angular dependence of the dHvA frequencies reveals many closed Fermi surfaces, which are nearly spherical in topology. The experimental results are in good agreement with local density approximation (LDA) band structure calculations based on the 5f-itinerant model. The band structure calculation predicts many Fermi surfaces, mostly with spherical shape, derived from 12 bands crossing the Fermi energy. To our knowledge, the splitting of Fermi surfaces due to the non-centrosymmetric crystal in 5f-electron systems is experimentally detected for the first time. The temperature dependence of the dHvA amplitude reveals a large cyclotron effective mass of up to 35 m0, indicating the heavy electronic state of U3Ni3Sn4 due to the proximity of the quantum critical point. From the field dependence of the dHvA amplitude, a mean free path of conduction electrons of up to 1950 Å is detected, reflecting the good quality of the grown crystal. The small splitting energy related to the antisymmetric spin-orbit interaction is most likely due to the large cyclotron effective mass.

Synthetic Aperture Processing of Wideband Scattering Measurements Made in the DRDC Atlantic Acoustic Calibration Tank

DTIC Science & Technology

2008-09-01

as represented by the Minister of National Defence, 2008 © Sa Majesté la Reine (en droit du Canada), telle que représentée par le ministre de la...des mines ventouses d’entraînement réelles, sur un disque de un mètre de diamètre qui était suspendu dans le bassin d’étalonnage acoustique de RDDC...Atlantique à l’aide d’une perche rotative. Deux disques ont été examinés : un en aluminium et l’autre en fibre de verre . Ces disques ont été tournés

Towards an operational fault isolation expert system for French telecommunication satellite Telecom 2

NASA Astrophysics Data System (ADS)

Haziza, M.

1990-10-01

The DIAMS satellite fault isolation expert system shell concept is described. The project, initiated in 1985, has led to the development of a prototype Expert System (ES) dedicated to the Telecom 1 attitude and orbit control system. The prototype ES has been installed in the Telecom 1 satellite control center and evaluated by Telecom 1 operations. The development of a fault isolation ES covering a whole spacecraft (the French telecommunication satellite Telecom 2) is currently being undertaken. Full scale industrial applications raise stringent requirements in terms of knowledge management and software development methodology. The approach used by MATRA ESPACE to face this challenge is outlined.

Laser-induced stimulated Raman scattering in the forward direction of a droplet - Comparison of Mie theory with geometrical optics

NASA Technical Reports Server (NTRS)

Srivastava, Vandana; Jarzembski, Maurice A.

1991-01-01

This paper uses Mie theory to treat electromagnetic scattering and to evaluate field enhancement in the forward direction of a small droplet irradiated by a high-energy beam and compares the results of calculations with the field-enhancement evaluation obtained via geometrical optics treatment. Results of this comparison suggest that the field enhancement located at the critical ring region encircling the axis in the forward direction of the droplet can support laser-induced Raman scattering. The results are supported by experimental observations of the interaction of a 120-micron-diam water droplet with a high-energy Nd:YAG laser beam.

Parallel plate radiofrequency ion thruster

NASA Technical Reports Server (NTRS)

Nakanishi, S.

1982-01-01

An 8-cm-diam. argon ion thruster is described. It is operated by applying 100 to 160 Mhz rf power across a thin plasma volume in a strongly divergent static magnetic field. No cathode or electron emitter is required to sustain a continuous wave plasma discharge over a broad range of propellant gas flow. Preliminary results indicate that a large fraction of the incident power is being reflected by impedance mismatching in the coupling structure. Resonance effects due to plasma thickness, magnetic field strength, and distribution are presented. Typical discharge losses obtained to date are 500 to 600 W per beam ampere at extracted beam currents up to 60 mA.

Welded Titanium Case for Space-Probe Rocket Motor

NASA Technical Reports Server (NTRS)

Brothers, A. J.; Boundy, R. A.; Martens, H. E.; Jaffe, L. D.

1959-01-01

The high strength-to-weight ratio of titanium alloys suggests their use for solid-propellant rocket-motor cases for high-performance orbiting or space-probe vehicles. The paper describes the fabrication of a 6-in.-diam., 0.025-in.-wall rocket-motor from the 6A1-4V titanium alloy. The rocket-motor case, used in the fourth stage of a successful JPL-NASA lunar-probe flight, was constructed using a design previously proven satisfactory for Type 410 stainless steel. The nature and scope of the problems peculiar to the use of the titanium alloy, which effected an average weight saving of 34%, are described.

A subcutaneous channeling probe for implanting long leads

NASA Technical Reports Server (NTRS)

Lund, G. F.; Simmonds, R. C.; Williams, B. A.

1977-01-01

The channeling probe described in the present paper was designed to overcome surgical problems of the type that were encountered when a multichannel radio transmitter had to be implanted in a cow. The probe was made of a flexible but sufficiently stiff 9.5-mm-diam nylon rod, consisting of 46-cm sections for convenience in sterilization and surgical handling. Stainless steel sleaves reinforced the threaded connecting joints. At one end, arrowhead-shaped channeling heads could be attached to produce wide channels for large sensors. The other end was tapered for narrow channels. Postoperative problems were not encountered in the use of this probe in cows, sheep, and dogs.

Automatic analysis of stereoscopic satellite image pairs for determination of cloud-top height and structure

NASA Technical Reports Server (NTRS)

Hasler, A. F.; Strong, J.; Woodward, R. H.; Pierce, H.

1991-01-01

Results are presented on an automatic stereo analysis of cloud-top heights from nearly simultaneous satellite image pairs from the GOES and NOAA satellites, using a massively parallel processor computer. Comparisons of computer-derived height fields and manually analyzed fields show that the automatic analysis technique shows promise for performing routine stereo analysis in a real-time environment, providing a useful forecasting tool by augmenting observational data sets of severe thunderstorms and hurricanes. Simulations using synthetic stereo data show that it is possible to automatically resolve small-scale features such as 4000-m-diam clouds to about 1500 m in the vertical.

USSR and Eastern Europe Scientific Abstracts Engineering and Equipment No.29

DTIC Science & Technology

1977-02-08

Perlite (12CrlMoV and 12Cr2MoVSib), ferrite - martensite (lCrllW2MoV), and austentite (Crl8Nil2Ti) steels are discussed for use in the heat-transfer...620°C. Other austentite steels have been developed, including EI695R, EP184, EP17, 45Crl0Mnl4Al-2 (which has a 20-40% ferrite phase ), 0Crl3Mnl2Ni2NSi2...middle zone of 10 mm and at the corners -- up to 40 mm. The shell was reinforced with a grid having square meshes of low -carbon steel wire, 1 mm in diam

Acoustic levitation

NASA Astrophysics Data System (ADS)

Hansen, Uwe J.

2005-09-01

A speaker, driven by an amplified audio signal is used to set up a standing wave in a 3b-ft-long, 4-in.-diam transparent tube. Initially the tube is oriented horizontally, and Styrofoam packing peanuts accumulate near the pressure nodes. When the tube is turned to a position with the axis oriented vertically, the peanuts drop slightly, until the gravitational force on the peanuts is balanced by the force due to the sound pressure, at which point levitation is observed. Sound-pressure level measurements are used to map the air column normal mode pattern. Similarly, standing waves are established between an ultrasonic horn and a metal reflector and millimeter size Styrofoam balls are levitated.

Effect of ultraprecision polishing techniques on coherence times of shallow nitrogen-vacancy centers in diamond

NASA Astrophysics Data System (ADS)

Braunbeck, G.; Mandal, S.; Touge, M.; Williams, O. A.; Reinhard, F.

2018-05-01

We investigate the correlation between surface roughness and corresponding $T_2$ times of nearsurface nitrogen-vacancy centers (~7 nm/ 5 keV implantation energy) in diamond. For this purpose we compare five different polishing techniques, including both purely mechanical as well as chemical mechanical approaches, two different substrate sources (Diam2tec and Element Six) and two different surface terminations (O- and H-termination) during nitrogen-vacancy forming. All coherence times are measured and compared before and after an oxygen surface treatment at 520 {\\deg}C. We find that the coherence times of shallow nitrogen-vacancy centers are surprisingly independent of surface roughness.

Spatiotemporal image correlation-derived volumetric Doppler impedance indices from spherical samples of the placenta: intraobserver reliability and correlation with conventional umbilical artery Doppler indices.

PubMed

Welsh, A W; Hou, M; Meriki, N; Martins, W P

2012-10-01

Volumetric impedance indices derived from spatiotemporal image correlation (STIC) power Doppler ultrasound (PDU) might overcome the influence of machine settings and attenuation. We examined the feasibility of obtaining these indices from spherical samples of anterior placentas in healthy pregnancies, and assessed intraobserver reliability and correlation with conventional umbilical artery (UA) impedance indices. Uncomplicated singleton pregnancies with anterior placenta were included in the study. A single observer evaluated UA pulsatility index (PI), resistance index (RI) and systolic/diastolic ratio (S/D) and acquired three STIC-PDU datasets from the placenta just above the placental cord insertion. Another observer analyzed the STIC-PDU datasets using Virtual Organ Computer-aided AnaLysis (VOCAL) spherical samples from every frame to determine the vascularization index (VI) and vascularization flow index (VFI); maximum, minimum and average values were used to determine the three volumetric impedance indices (vPI, vRI, vS/D). Intraobserver reliability was examined by intraclass correlation coefficients (ICC) and association between volumetric indices from placenta, and UA Doppler indices were assessed by Pearson's correlation coefficient. A total of 25 pregnant women were evaluated but five were excluded because of artifacts observed during analysis. The reliability of measurement of volumetric indices of both VI and VFI from three STIC-PDU datasets was similar, with all ICCs ≥ 0.78. Pearson's r values showed a weak and non-significant correlation between UA pulsed-wave Doppler indices and their respective volumetric indices from spherical samples of placenta (all r ≥ 0.23). VOCAL indices from specific phases of the cardiac cycle showed good repeatability (ICC ≥ 0.92). Volumetric impedance indices determined from spherical samples of placenta are sufficiently reliable but do not correlate with UA Doppler indices in healthy pregnancies. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.

Modeling the Interaction of Mineral Dust with Solar Radiation: Spherical versus Non-spherical Particles

NASA Astrophysics Data System (ADS)

Hoshyaripour, A.; Vogel, B.; Vogel, H.

2017-12-01

Mineral dust, emitted from arid and semi-arid regions, is the most dominant atmospheric aerosol by mass. Beside detrimental effect on air quality, airborne dust also influences the atmospheric radiation by absorbing and scattering solar and terrestrial radiation. As a result, while the long-term radiative impacts of dust are important for climate, the short-term effects are significant for the photovoltaic energy production. Therefore, it is a vital requirement to accurately forecast the effects of dust on energy budget of the atmosphere and surface. To this end, a major issue is the fact that dust particles are non-spherical. Thus, the optical properties of such particles cannot be calculated precisely using the conventional methods like Mie theory that are often used in climate and numerical weather forecast models. In this study, T-Matrix method is employed, which is able to treat the non-sphericity of particles. Dust particles are assumed to be prolate spheroids with aspect ratio of 1.5 distributed in three lognormal modes. The wavelength-dependent refractive indices of dust are used in T-Matrix algorithm to calculate the extinction coefficient, single scattering albedo, asymmetry parameter and backscattering ratio at different wavelengths. These parameters are then implemented in ICON-ART model (ICOsahedral Nonhydrostatic model with Aerosols and Reactive Trace gases) to conduct a global simulation with 80 km horizontal resolution and 90 vertical levels. April 2014 is selected as the simulation period during which North African dust plumes reached central Europe and Germany. Results show that treatment of non-sphericity reduces the dust AOD in the range of 10 to 30%/. The impacts on diffuse and direct radiation at global, regional and local scales show strong dependency on the size distribution of the airborne dust. The implications for modeling and remote sensing the dust impacts on solar energy are also discussed.

Insight into the electrical properties and chain conformation of spherical polyelectrolyte brushes by dielectric spectroscopy

NASA Astrophysics Data System (ADS)

Guo, Xiaoxia; Zhao, Kongshuang

2017-02-01

We report here a dielectric study on three kinds of anionic spherical polyelectrolyte brush (SPBs, consisting of a polystyrene (PS) core and three different poly (acrylic acid) chains grafted onto the core) suspensions over a frequency ranging from 40 Hz to 110 MHz. The relaxation behavior of the SPB suspensions shows significant changes in the brush-layer properties when the mass fraction of SPBs and the pH of the suspensions change. Two definite relaxations related to the interfacial polarization are observed around 100 kHz and 10 MHz. A single-layer spherical-shell model is applied to describe the SPB suspensions wherein the suspended SPB is modeled as a spherical-shell composite particle in which an insulated PS sphere is surrounded by a conducting ion-permeable shell (the polyelectrolyte chain layer). We developed the curve-fitting procedure to analyze the dielectric spectrum in order to obtain the dielectric properties of the components of the SPBs, especially the properties of the polyelectrolyte brush. Based on this method and model, the permittivity and conductivity of the brush layer, ζ potential, etc are calculated. The ordered orientation of the water molecules in the layer leads to an additional electrical dipole moment; increasing pH causes the brush layer to swell. In addition, the repulsive force between the SPB particles are evaluated using the brush-layer thickness, which is obtained by fitting dielectric spectra, combined with relative theoretical formulas. Increasing PH values or SPB concentration would improve the stability of the SPBs dispersion.

Development and application of a ray-based model of light propagation through a spherical acousto-optic lens

PubMed Central

Evans, Geoffrey J.; Kirkby, Paul A.; Nadella, K. M. Naga Srinivas; Marin, Bóris; Silver, R. Angus

2016-01-01

A spherical acousto-optic lens (AOL) consists of four acousto-optic deflectors (AODs) that can rapidly and precisely control the focal position of an optical beam in 3D space. Development and application of AOLs has increased the speed at which 3D random access point measurements can be performed with a two-photon microscope. This has been particularly useful for measuring brain activity with fluorescent reporter dyes because neuronal signalling is rapid and sparsely distributed in 3D space. However, a theoretical description of light propagation through AOLs has lagged behind their development, resulting in only a handful of simplified principles to guide AOL design and optimization. To address this we have developed a ray-based computer model of an AOL incorporating acousto-optic diffraction and refraction by anisotropic media. We extended an existing model of a single AOD with constant drive frequency to model a spherical AOL: four AODs in series driven with linear chirps. AOL model predictions of the relationship between optical transmission efficiency and acoustic drive frequency including second order diffraction effects closely matched experimental measurements from a 3D two-photon AOL microscope. Moreover, exploration of different AOL drive configurations identified a new simple rule for maximizing the field of view of our compact AOL design. By providing a theoretical basis for understanding optical transmission through spherical AOLs, our open source model is likely to be useful for comparing and improving different AOL designs, as well as identifying the acoustic drive configurations that provide the best transmission performance over the 3D focal region. PMID:26368449

Development and application of a ray-based model of light propagation through a spherical acousto-optic lens.

PubMed

Evans, Geoffrey J; Kirkby, Paul A; Naga Srinivas Nadella, K M; Marin, Bóris; Angus Silver, R

2015-09-07

A spherical acousto-optic lens (AOL) consists of four acousto-optic deflectors (AODs) that can rapidly and precisely control the focal position of an optical beam in 3D space. Development and application of AOLs has increased the speed at which 3D random access point measurements can be performed with a two-photon microscope. This has been particularly useful for measuring brain activity with fluorescent reporter dyes because neuronal signalling is rapid and sparsely distributed in 3D space. However, a theoretical description of light propagation through AOLs has lagged behind their development, resulting in only a handful of simplified principles to guide AOL design and optimization. To address this we have developed a ray-based computer model of an AOL incorporating acousto-optic diffraction and refraction by anisotropic media. We extended an existing model of a single AOD with constant drive frequency to model a spherical AOL: four AODs in series driven with linear chirps. AOL model predictions of the relationship between optical transmission efficiency and acoustic drive frequency including second order diffraction effects closely matched experimental measurements from a 3D two-photon AOL microscope. Moreover, exploration of different AOL drive configurations identified a new simple rule for maximizing the field of view of our compact AOL design. By providing a theoretical basis for understanding optical transmission through spherical AOLs, our open source model is likely to be useful for comparing and improving different AOL designs, as well as identifying the acoustic drive configurations that provide the best transmission performance over the 3D focal region.

A Spherical Aerial Terrestrial Robot

NASA Astrophysics Data System (ADS)

Dudley, Christopher J.

This thesis focuses on the design of a novel, ultra-lightweight spherical aerial terrestrial robot (ATR). The ATR has the ability to fly through the air or roll on the ground, for applications that include search and rescue, mapping, surveillance, environmental sensing, and entertainment. The design centers around a micro-quadcopter encased in a lightweight spherical exoskeleton that can rotate about the quadcopter. The spherical exoskeleton offers agile ground locomotion while maintaining characteristics of a basic aerial robot in flying mode. A model of the system dynamics for both modes of locomotion is presented and utilized in simulations to generate potential trajectories for aerial and terrestrial locomotion. Details of the quadcopter and exoskeleton design and fabrication are discussed, including the robot's turning characteristic over ground and the spring-steel exoskeleton with carbon fiber axle. The capabilities of the ATR are experimentally tested and are in good agreement with model-simulated performance. An energy analysis is presented to validate the overall efficiency of the robot in both modes of locomotion. Experimentally-supported estimates show that the ATR can roll along the ground for over 12 minutes and cover the distance of 1.7 km, or it can fly for 4.82 minutes and travel 469 m, on a single 350 mAh battery. Compared to a traditional flying-only robot, the ATR traveling over the same distance in rolling mode is 2.63-times more efficient, and in flying mode the system is only 39 percent less efficient. Experimental results also demonstrate the ATR's transition from rolling to flying mode.

The Application of GIM in Precise Orbit Determination for LEO Satellites with Single-Frequency GPS Measurements

NASA Astrophysics Data System (ADS)

Peng, Dong-ju; Wu, Bin

2012-10-01

With the precise GPS ephemeris and clock error available, the iono- spheric delay is left as the dominant error source in the single-frequency GPS data. Thus, the removal of ionospheric effects is a ma jor prerequisite for an improved orbit reconstruction of LEO satellites based on the single-frequency GPS data. In this paper, the use of Global Ionospheric Maps (GIM) in kine- matic and dynamic orbit determinations for LEO satellites with single-frequency GPS pseudorange measurements is discussed first, and then, estimating the iono- spheric scale factor to remove the ionospheric effects from the C/A-code pseu- dorange measurements for both kinematic and dynamic orbit determinations is addressed. As it is known that the ionospheric delay of space-borne GPS sig- nals is strongly dependent on the orbit altitudes of LEO satellites, we select the real C/A-code pseudorange measurement data of the CHAMP, GRACE, TerraSAR-X and SAC-C satellites with altitudes between 300 km and 800 km as sample data in this paper. It is demonstrated that the approach to eliminating ionospheric effects in C/A-code pseudorange measurements by estimating the ionospheric scale factor is highly effective. Employing this approach, the accu- racy of both kinematic and dynamic orbits can be improved notably. Among those five LEO satellites, CHAMP with the lowest orbit altitude has the most remarkable improvements in orbit accuracy, which are 55.6% and 47.6% for kine- matic and dynamic orbits, respectively. SAC-C with the highest orbit altitude has the least improvements in orbit accuracy accordingly, which are 47.8% and 38.2%, respectively.

Designing single- and multiple-shell sampling schemes for diffusion MRI using spherical code.

PubMed

Cheng, Jian; Shen, Dinggang; Yap, Pew-Thian

2014-01-01

In diffusion MRI (dMRI), determining an appropriate sampling scheme is crucial for acquiring the maximal amount of information for data reconstruction and analysis using the minimal amount of time. For single-shell acquisition, uniform sampling without directional preference is usually favored. To achieve this, a commonly used approach is the Electrostatic Energy Minimization (EEM) method introduced in dMRI by Jones et al. However, the electrostatic energy formulation in EEM is not directly related to the goal of optimal sampling-scheme design, i.e., achieving large angular separation between sampling points. A mathematically more natural approach is to consider the Spherical Code (SC) formulation, which aims to achieve uniform sampling by maximizing the minimal angular difference between sampling points on the unit sphere. Although SC is well studied in the mathematical literature, its current formulation is limited to a single shell and is not applicable to multiple shells. Moreover, SC, or more precisely continuous SC (CSC), currently can only be applied on the continuous unit sphere and hence cannot be used in situations where one or several subsets of sampling points need to be determined from an existing sampling scheme. In this case, discrete SC (DSC) is required. In this paper, we propose novel DSC and CSC methods for designing uniform single-/multi-shell sampling schemes. The DSC and CSC formulations are solved respectively by Mixed Integer Linear Programming (MILP) and a gradient descent approach. A fast greedy incremental solution is also provided for both DSC and CSC. To our knowledge, this is the first work to use SC formulation for designing sampling schemes in dMRI. Experimental results indicate that our methods obtain larger angular separation and better rotational invariance than the generalized EEM (gEEM) method currently used in the Human Connectome Project (HCP).

On Spectral Invariance of Single Scattering Albedo for Water Droplets and Ice Crystals at Weakly Absorbing Wavelengths

NASA Technical Reports Server (NTRS)

Marshak, Alexander; Knyazikhin, Yuri; Chiu, J. Christine; Wiscombe, Warren J.

2012-01-01

The single scattering albedo omega(sub O lambda) in atmospheric radiative transfer is the ratio of the scattering coefficient to the extinction coefficient. For cloud water droplets both the scattering and absorption coefficients, thus the single scattering albedo, are functions of wavelength lambda and droplet size r. This note shows that for water droplets at weakly absorbing wavelengths, the ratio omega(sub O lambda)(r)/omega(sub O lambda)(r (sub O)) of two single scattering albedo spectra is a linear function of omega(sub O lambda)(r). The slope and intercept of the linear function are wavelength independent and sum to unity. This relationship allows for a representation of any single scattering albedo spectrum omega(sub O lambda)(r) via one known spectrum omega(sub O lambda)(r (sub O)). We provide a simple physical explanation of the discovered relationship. Similar linear relationships were found for the single scattering albedo spectra of non-spherical ice crystals.

Investigating tunneling process of atom exposed in circularly polarized strong-laser field

NASA Astrophysics Data System (ADS)

Yuan, MingHu; Xin, PeiPei; Chu, TianShu; Liu, HongPing

2017-03-01

We propose a method for studying the tunneling process by analyzing the instantaneous ionization rate of a circularly polarized laser. A numerical calculation shows that, for an atom exposed to a long laser pulse, if its initial electronic state wave function is non-spherical symmetric, the delayed phase shift of the ionization rate vs the laser cycle period in real time in the region close to the peak intensity of the laser pulse can be used to probe the tunneling time. In this region, an obvious time delay phase shift of more than 190 attoseconds is observed. Further study shows that the atom has a longer tunneling time in the ionization under a shorter wavelength laser pulse. In our method, a Wigner rotation technique is employed to numerically solve the time-dependent Schrödinger equation of a single-active electron in a three-dimensional spherical coordinate system.

Practical design and evaluation methods of omnidirectional vision sensors

NASA Astrophysics Data System (ADS)

Ohte, Akira; Tsuzuki, Osamu

2012-01-01

A practical omnidirectional vision sensor, consisting of a curved mirror, a mirror-supporting structure, and a megapixel digital imaging system, can view a field of 360 deg horizontally and 135 deg vertically. The authors theoretically analyzed and evaluated several curved mirrors, namely, a spherical mirror, an equidistant mirror, and a single viewpoint mirror (hyperboloidal mirror). The focus of their study was mainly on the image-forming characteristics, position of the virtual images, and size of blur spot images. The authors propose here a practical design method that satisfies the required characteristics. They developed image-processing software for converting circular images to images of the desired characteristics in real time. They also developed several prototype vision sensors using spherical mirrors. Reports dealing with virtual images and blur-spot size of curved mirrors are few; therefore, this paper will be very useful for the development of omnidirectional vision sensors.

Research on dual-parameter optical fiber sensor based on thin-core fiber and spherical structure

NASA Astrophysics Data System (ADS)

Tong, Zhengrong; Wang, Xue; Zhang, Weihua; Xue, Lifang

2018-04-01

A novel dual-parameter optical fiber sensor is proposed and experimentally demonstrated. The proposed sensor is based on a fiber in-line Mach-Zehnder interferometer, which is fabricated by sandwiching a section of thin-core fiber between two spherical structures made of single-mode fibers. The transmission spectrum exhibits the response of the interference between the core and the different cladding modes. Due to the different wavelength shifts of the two selected dips, the simultaneous measurement of temperature and the surrounding refractive index can be achieved. The measured temperature sensitivities are 0.067 nm/°C and 0.050 nm/°C, and the refractive index sensitivities are  -119.9 nm/RIU and  -69.71 nm/RIU, respectively. In addition, the compact size, simple fabrication and cost-effectiveness of the fiber sensor are also advantages.

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

Boreyko, Jonathan B; Mruetusatorn, Prachya; Sarles, Stephen A

Droplet interface bilayers (DIBs) are a robust platform for studying synthetic cellular membranes; however, to date no DIBs have been produced at cellular length scales. Here, we create microscale droplet interface bilayers ( DIBs) at the interface between aqueous femtoliter-volume droplets within an oil-filled microfluidic channel. The uniquely large area-to-volume ratio of the droplets results in strong evaporation effects, causing the system to transition through three distinct regimes. First, the two adjacent droplets shrink into the shape of a single spherical droplet, where an augmented lipid bilayer partitions two hemi-spherical volumes. In the second regime, the combined effects of themore » shrinking monolayers and growing bilayer force the confined bilayer to buckle to conserve its mass. Finally, at a bending moment corresponding to a critical shear stress, the buckling bilayer fissions a vesicle to regulate its shape and stress. The DIBs produced here enable evaporation-induced bilayer dynamics reminiscent of endo- and exocytosis in cells.« less

A study of nondiffracting Lommel beams propagating in a medium containing spherical scatterers

NASA Astrophysics Data System (ADS)

Belafhal, A.; Ez-zariy, L.; Hricha, Z.

2016-11-01

By means of the expansion of the nondiffracting beams on plane waves with help of the Whittaker integral, an exact analytical expression of the far-field form function of the scattering of the acoustic and optical nondiffracting Lommel beams propagating in a medium containing spherical particles, considered as rigid and single spheres, is investigated in this work. The form function of the scattering of the high order Bessel beam by a rigid and isolated sphere is deduced, from our finding, as a special case. The effects of the wave number-sphere radius product (ka) , the polar angle (φ) , the propagation half-cone angle (β) and the scattering angle (θ) on the far-field form function of the scattered wave have been analyzed and discussed numerically. The numerical results show that the illumination of a rigid sphere by Lommel beams produces asymmetrical scattering.

Ergodic model for the expansion of spherical nanoplasmas.

PubMed

Peano, F; Coppa, G; Peinetti, F; Mulas, R; Silva, L O

2007-06-01

Recently, the collisionless expansion of spherical nanoplasmas has been analyzed with a new ergodic model, clarifying the transition from hydrodynamiclike to Coulomb-explosion regimes, and providing accurate laws for the relevant features of the phenomenon. A complete derivation of the model is presented here. The important issue of the self-consistent initial conditions is addressed by analyzing the initial charging transient due to the electron expansion, in the approximation of immobile ions. A comparison among different kinetic models for the expansion is presented, showing that the ergodic model provides a simplified description, which retains the essential information on the electron distribution, in particular, the energy spectrum. Results are presented for a wide range of initial conditions (determined from a single dimensionless parameter), in excellent agreement with calculations from the exact Vlasov-Poisson theory, thus providing a complete and detailed characterization of all the stages of the expansion.

Contributions of microtubule rotation and dynamic instability to kinetochore capture

NASA Astrophysics Data System (ADS)

Sweezy-Schindler, Oliver; Edelmaier, Christopher; Blackwell, Robert; Glaser, Matt; Betterton, Meredith

2014-03-01

The capture of lost kinetochores (KCs) by microtubules (MTs) is a crucial part of prometaphase during mitosis. Microtubule dynamic instability has been considered the primary mechanism of KC capture, but recent work discovered that lateral KC attachment to pivoting MTs enabled rapid capture even with significantly reduced MT dynamics. We aim to understand the relative contributions of MT rotational diffusion and dynamic instability to KC capture, as well as KC capture through end-on and/or lateral attachment. Our model consists of rigid MTs and a spherical KC, which are allowed to diffuse inside a spherical nuclear envelope consistent with the geometry of fission yeast. For simplicity, we include a single spindle pole body, which is anchored to the nuclear membrane, and its associated polar MTs. Brownian dynamics treats the diffusion of the MTs and KC and kinetic Monte Carlo models stochastic processes such as dynamic instability. NSF 1546021.

The generation and morphology of single-crystal silicon carbide wear particles under adhesive conditions

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.

1981-01-01

Sliding friction experiments were performed in vacuum at room temperature on a plane-type SiC surface in contact with iron-based binary alloys. Multiangular and spherical wear particles were found to form as a result of multipass sliding. The multiangular particles were produced by primary and secondary cracking of the 0001, 10(-)10, and 11(-)20 plane-type cleavage planes under the Hertzian stress field or local inelastic deformation zone. When alloy surfaces are in contact with silicon carbide under a load of 0.2 N, the alloy around the contact area is subjected to stresses that are close to the elastic limit in the elastic deformation region and/or exceed it. It was also found that spherical wear particles may be produced by two mechanisms: a penny-shaped fracture along the circular stress trajectories under the local inelastic deformation zone, and the attrition and fatigue of wear particles.

Experimental, Numerical, and Analytical Slosh Dynamics of Water and Liquid Nitrogen in a Spherical Tank

NASA Technical Reports Server (NTRS)

Storey, Jedediah Morse

2016-01-01

Understanding, predicting, and controlling fluid slosh dynamics is critical to safety and improving performance of space missions when a significant percentage of the spacecraft's mass is a liquid. Computational fluid dynamics simulations can be used to predict the dynamics of slosh, but these programs require extensive validation. Many experimental and numerical studies of water slosh have been conducted. However, slosh data for cryogenic liquids is lacking. Water and cryogenic liquid nitrogen are used in various ground-based tests with a spherical tank to characterize damping, slosh mode frequencies, and slosh forces. A single ring baffle is installed in the tank for some of the tests. Analytical models for slosh modes, slosh forces, and baffle damping are constructed based on prior work. Select experiments are simulated using a commercial CFD software, and the numerical results are compared to the analytical and experimental results for the purposes of validation and methodology-improvement.

A Comparative Study of Production of Glass Microspheres by using Thermal Process

NASA Astrophysics Data System (ADS)

Lee, May Yan; Tan, Jully; Heng, Jerry YY; Cheeseman, Christopher

2017-06-01

Microspheres are spherical particles that can be distinguished into two categories; solid or hollow. Microspheres typical ranges from 1 to 200 μm in diameter. Microsphere are made from glass, ceramic, carbon or plastic depending on applications. Solid glass microsphere is manufactured by direct burning of glass powders while hollow glass microspheres is produced by adding blowing agent to glass powder. This paper presented the production of glass microspheres by using the vertical thermal flame (VTF) process. Pre-treated soda lime glass powder with particle sized range from 90 to 125μm was used in this work. The results showed that glass microspheres produced by two passes through the flame have a more spherical shape as compared with the single pass. Under the Scanning Electron Microscope (SEM), it is observed that there is a morphology changed from uneven surface of glass powders to smooth spherical surface particles. Qualitative analysis for density of the pre-burned and burned particles was performed. Burned particles floats in water while pre-burned particles sank indicated the change of density of the particles. Further improvements of the VTF process in terms of the VTF set-up are required to increase the transformation of glass powders to glass microspheres.

Pyrolysis of Large Black Liquor Droplets

NASA Technical Reports Server (NTRS)

Bartkus, Tadas P.; Dietrich, Daniel L.; T'ien, James S.; Wessel, Richard A.

2007-01-01

This paper presents the results of experiments involving the pyrolysis of large black liquor droplets in the NASA KC-135 reduced gravity aircraft. The reduced gravity environment facilitated the study of droplets up to 9 mm in diameter extending the results of previous studies to droplet sizes that are similar to those encountered in recovery boilers. Single black liquor droplets were rapidly inserted into a 923 K oven. The primary independent variables were the initial droplet diameter (0.5 mm to 9 mm), the black liquor solids content (66.12% - 72.9% by mass), and the ambient oxygen mole fraction (0.0 - 0.21). Video records of the experiments provided size and shape of the droplets as a function of time. The results show that the particle diameter at the end of the drying stage (D(sub DRY)) increases linearly with the initial particle diameter (D(sub O)). The results further show that the ratio of the maximum swollen diameter (D(sub MAX)) to D(sub O) decreases with increasing D(sub O) for droplets with D(sub O) less than 4 mm. This ratio was independent of D(sub O) for droplets with D(sub O) greater than 4 mm. The particle is most spherical at the end of drying, and least spherical at maximum swollen size, regardless of initial sphericity and droplet size.

Pyrolysis of Large Black Liquor Droplets

NASA Technical Reports Server (NTRS)

Bartkus, Tadas P.; T'ien, James S.; Dietrich, Daniel L.; Wessel, Richard A.

2007-01-01

This paper presents the results of experiments involving the pyrolysis of large black liquor droplets in the NASA KC-135 reduced gravity aircraft. The reduced gravity environment facilitated the study of droplets up to 9 mm in diameter extending the results of previous studies to droplet sizes that are similar to those encountered in recovery boilers. Single black liquor droplets were rapidly inserted into a 923 K oven. The primary independent variables were the initial droplet diameter (0.5 mm to 9 mm), the black liquor solids content (66.12% - 72.9% by mass), and the ambient oxygen mole fraction (0.0 - 0.21). Video records of the experiments provided size and shape of the droplets as a function of time. The results show that the particle diameter at the end of the drying stage (D(sub DRY) ) increases linearly with the initial particle diameter (D(sub O)). The results further show that the ratio of the maximum swollen diameter (D(sub MAX)) to D(sub O) decreases with increasing D(sub O) for droplets with D(sub O) less than 4 mm. This ratio was independent of D(sub O) for droplets with D(sub O) greater than 4 mm. The particle is most spherical at the end of drying, and least spherical at maximum swollen size, regardless of initial sphericity and droplet size.

Divertor heat flux mitigation in the National Spherical Torus Experimenta)

NASA Astrophysics Data System (ADS)

Soukhanovskii, V. A.; Maingi, R.; Gates, D. A.; Menard, J. E.; Paul, S. F.; Raman, R.; Roquemore, A. L.; Bell, M. G.; Bell, R. E.; Boedo, J. A.; Bush, C. E.; Kaita, R.; Kugel, H. W.; Leblanc, B. P.; Mueller, D.; NSTX Team

2009-02-01

Steady-state handling of divertor heat flux is a critical issue for both ITER and spherical torus-based devices with compact high power density divertors. Significant reduction of heat flux to the divertor plate has been achieved simultaneously with favorable core and pedestal confinement and stability properties in a highly shaped lower single null configuration in the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 2000] using high magnetic flux expansion at the divertor strike point and the radiative divertor technique. A partial detachment of the outer strike point was achieved with divertor deuterium injection leading to peak flux reduction from 4-6MWm-2to0.5-2MWm-2 in small-ELM 0.8-1.0MA, 4-6MW neutral beam injection-heated H-mode discharges. A self-consistent picture of the outer strike point partial detachment was evident from divertor heat flux profiles and recombination, particle flux and neutral pressure measurements. Analytic scrape-off layer parallel transport models were used for interpretation of NSTX detachment experiments. The modeling showed that the observed peak heat flux reduction and detachment are possible with high radiated power and momentum loss fractions, achievable with divertor gas injection, and nearly impossible to achieve with main electron density, divertor neutral density or recombination increases alone.

Resolving complex fibre architecture by means of sparse spherical deconvolution in the presence of isotropic diffusion

NASA Astrophysics Data System (ADS)

Zhou, Q.; Michailovich, O.; Rathi, Y.

2014-03-01

High angular resolution diffusion imaging (HARDI) improves upon more traditional diffusion tensor imaging (DTI) in its ability to resolve the orientations of crossing and branching neural fibre tracts. The HARDI signals are measured over a spherical shell in q-space, and are usually used as an input to q-ball imaging (QBI) which allows estimation of the diffusion orientation distribution functions (ODFs) associated with a given region-of interest. Unfortunately, the partial nature of single-shell sampling imposes limits on the estimation accuracy. As a result, the recovered ODFs may not possess sufficient resolution to reveal the orientations of fibre tracts which cross each other at acute angles. A possible solution to the problem of limited resolution of QBI is provided by means of spherical deconvolution, a particular instance of which is sparse deconvolution. However, while capable of yielding high-resolution reconstructions over spacial locations corresponding to white matter, such methods tend to become unstable when applied to anatomical regions with a substantial content of isotropic diffusion. To resolve this problem, a new deconvolution approach is proposed in this paper. Apart from being uniformly stable across the whole brain, the proposed method allows one to quantify the isotropic component of cerebral diffusion, which is known to be a useful diagnostic measure by itself.

Generalized image charge solvation model for electrostatic interactions in molecular dynamics simulations of aqueous solutions

PubMed Central

Deng, Shaozhong; Xue, Changfeng; Baumketner, Andriy; Jacobs, Donald; Cai, Wei

2013-01-01

This paper extends the image charge solvation model (ICSM) [J. Chem. Phys. 131, 154103 (2009)], a hybrid explicit/implicit method to treat electrostatic interactions in computer simulations of biomolecules formulated for spherical cavities, to prolate spheroidal and triaxial ellipsoidal cavities, designed to better accommodate non-spherical solutes in molecular dynamics (MD) simulations. In addition to the utilization of a general truncated octahedron as the MD simulation box, central to the proposed extension is an image approximation method to compute the reaction field for a point charge placed inside such a non-spherical cavity by using a single image charge located outside the cavity. The resulting generalized image charge solvation model (GICSM) is tested in simulations of liquid water, and the results are analyzed in comparison with those obtained from the ICSM simulations as a reference. We find that, for improved computational efficiency due to smaller simulation cells and consequently a less number of explicit solvent molecules, the generalized model can still faithfully reproduce known static and dynamic properties of liquid water at least for systems considered in the present paper, indicating its great potential to become an accurate but more efficient alternative to the ICSM when bio-macromolecules of irregular shapes are to be simulated. PMID:23913979

Characterization of the crystal structure, kinematics, stresses and rotations in angular granular quartz during compaction

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

Hurley, Ryan C.; Herbold, Eric B.; Pagan, Darren C.

Three-dimensional X-ray diffraction (3DXRD), a method for quantifying the position, orientation and elastic strain of large ensembles of single crystals, has recently emerged as an important tool for studying the mechanical response of granular materials during compaction. Applications have demonstrated the utility of 3DXRD and X-ray computed tomography (XRCT) for assessing strains, particle stresses and orientations, inter-particle contacts and forces, particle fracture mechanics, and porosity evolution in situ . Although past studies employing 3DXRD and XRCT have elucidated the mechanics of spherical particle packings and angular particle packings with a small number of particles, there has been limited effort tomore » date in studying angular particle packings with a large number of particles and in comparing the mechanics of these packings with those composed of a large number of spherical particles. Therefore, the focus of the present paper is on the mechanics of several hundred angular particles during compaction using in situ 3DXRD to study the crystal structure, kinematics, stresses and rotations of angular quartz grains. Comparisons are also made between the compaction response of angular grains and that of spherical grains, and stress-induced twinning within individual grains is discussed.« less

Forced sound transmission through a finite-sized single leaf panel subject to a point source excitation.

PubMed

Wang, Chong

2018-03-01

In the case of a point source in front of a panel, the wavefront of the incident wave is spherical. This paper discusses spherical sound waves transmitting through a finite sized panel. The forced sound transmission performance that predominates in the frequency range below the coincidence frequency is the focus. Given the point source located along the centerline of the panel, forced sound transmission coefficient is derived through introducing the sound radiation impedance for spherical incident waves. It is found that in addition to the panel mass, forced sound transmission loss also depends on the distance from the source to the panel as determined by the radiation impedance. Unlike the case of plane incident waves, sound transmission performance of a finite sized panel does not necessarily converge to that of an infinite panel, especially when the source is away from the panel. For practical applications, the normal incidence sound transmission loss expression of plane incident waves can be used if the distance between the source and panel d and the panel surface area S satisfy d/S>0.5. When d/S ≈0.1, the diffuse field sound transmission loss expression may be a good approximation. An empirical expression for d/S=0  is also given.

Micro-scale blood particulate dynamics using a non-uniform rational B-spline-based isogeometric analysis.

PubMed

Chivukula, V; Mousel, J; Lu, J; Vigmostad, S

2014-12-01

The current research presents a novel method in which blood particulates - biconcave red blood cells (RBCs) and spherical cells are modeled using isogeometric analysis, specifically Non-Uniform Rational B-Splines (NURBS) in 3-D. The use of NURBS ensures that even with a coarse representation, the geometry of the blood particulates maintains an accurate description when subjected to large deformations. The fundamental advantage of this method is the coupling of the geometrical description and the stress analysis of the cell membrane into a single, unified framework. Details on the modeling approach, implementation of boundary conditions and the membrane mechanics analysis using isogeometric modeling are presented, along with validation cases for spherical and biconcave cells. Using NURBS - based isogeometric analysis, the behavior of individual cells in fluid flow is presented and analyzed in different flow regimes using as few as 176 elements for a spherical cell and 220 elements for a biconcave RBC. This work provides a framework for modeling a large number of 3-D deformable biological cells, each with its own geometric description and membrane properties. To the best knowledge of the authors, this is the first application of the NURBS - based isogeometric analysis to model and simulate blood particulates in flow in 3D. Copyright © 2014 John Wiley & Sons, Ltd.

Characterization of the crystal structure, kinematics, stresses and rotations in angular granular quartz during compaction

DOE PAGES

Hurley, Ryan C.; Herbold, Eric B.; Pagan, Darren C.

2018-06-28

Three-dimensional X-ray diffraction (3DXRD), a method for quantifying the position, orientation and elastic strain of large ensembles of single crystals, has recently emerged as an important tool for studying the mechanical response of granular materials during compaction. Applications have demonstrated the utility of 3DXRD and X-ray computed tomography (XRCT) for assessing strains, particle stresses and orientations, inter-particle contacts and forces, particle fracture mechanics, and porosity evolution in situ . Although past studies employing 3DXRD and XRCT have elucidated the mechanics of spherical particle packings and angular particle packings with a small number of particles, there has been limited effort tomore » date in studying angular particle packings with a large number of particles and in comparing the mechanics of these packings with those composed of a large number of spherical particles. Therefore, the focus of the present paper is on the mechanics of several hundred angular particles during compaction using in situ 3DXRD to study the crystal structure, kinematics, stresses and rotations of angular quartz grains. Comparisons are also made between the compaction response of angular grains and that of spherical grains, and stress-induced twinning within individual grains is discussed.« less

Uncertainties of aerosol retrieval from neglecting non-sphericity of dust aerosols

NASA Astrophysics Data System (ADS)

Li, Chi; Xue, Yong; Yang, Leiku; Guang, Jie

2013-04-01

The Mie theory is conventionally applied to calculate aerosol optical properties in satellite remote sensing applications, while dust aerosols cannot be well modeled by the Mie calculation for their non-sphericity. It has been cited in Mishchenko et al. (1995; 1997) that neglecting non-sphericity can severely influence aerosol optical depth (AOD, ?) retrieval in case of dust aerosols because of large difference of phase functions under spherical and non-spherical assumptions, whereas this uncertainty has not been thoroughly studied. This paper aims at a better understanding of uncertainties on AOD retrieval caused by aerosol non-sphericity. A dust aerosol model with known refractive index and size distribution is generated from long-term AERONET observations since 1999 over China. Then aerosol optical properties, such as the extinction, phase function, single scattering albedo (SSA) are calculated respectively in the assumption of spherical and non-spherical aerosols. Mie calculation is carried out for spherical assumption, meanwhile for non-spherical aerosol modeling, we adopt the pre-calculated scattering kernels and software package presented by Dubovik et al. (2002; 2006), which describes dust as a shape mixture of randomly oriented polydisperse spheroids. Consequently we generate two lookup tables (LUTspheric and LUTspheroid) from simulated satellite received reflectance at top of atmosphere (TOA) under varieties of observing conditions and aerosol loadings using Second Simulation of a Satellite Signal in the Solar Spectrum - Vector (6SV) code. All the simulations are made at 550 nm, and for simplicity the Lambertian surface is assumed. Using the obtained LUTs we examine the differences of TOA reflectance (Δ?TOA = ?spheric - ?spheroid) under different surface reflectance and aerosol loadings. Afterwards AOD is retrieved using LUTspheric from the simulated TOA reflectance by LUTspheroid in order to detect the retrieval errors (Δ? = ?retreived -?input) induced by straightforwardly utilizing Mie theory in dust aerosol retrieval. As expected we find that the uncertainties mainly result from the obvious difference of phase functions (Pspheric and Pspheroid). Errors may be positive or negative, depending on the specific geometry. In scattering angle (θ) regions where Psphericis greater (30°~85° & 145°~180°), we generally get positive Δ?TOA and negative Δ?, and vice versa (85°~145°). For low aerosol loading (? ~0.25) and black surface, |Δ?TOA| could be greater than 0.004 and 0.012 around θ ~120° and θ ~170°, with |Δ?| of ~0.04 and ~0.12 respectively. In most back scattering cases (θ >100°), the magnitude of Δ? is about ten times that of Δ?TOA, while this ratio (|Δ?|/|Δ?TOA|) significantly reduces to as low as ~0.5 for forward scattering, and can reach ~20 at θ ~145°. Moreover, this errors and |Δ?|/|Δ?TOA| can increase more than ten times as aerosol loading gets higher and surface gets brighter. Therefore we conclude that the neglect of non-sphericity introduces substantial errors on radiative transfer simulation and AOD retrieval. As a result of this study, a representative aspheric aerosol model other than Mie calculation is recommended for inversion algorithms related with dust-like non-spherical aerosols. References Dubovik, O., Holben, B. N., Lapyonok, T., Sinyuk, A., Mishchenko, M. I., Yang, P., and Slutsker, I. (2002). Non-spherical aerosol retrieval method employing light scattering by spheroids. Geophyscal Research Letters, 29(10), 1415, doi:10.1029/2001GL014506. Dubovik, O., Sinyuk, A., Lapyonok, T., Holben, B. N., Mishchenko, M., Yang, P., Eck, T. F., Volten, H., Muñoz, O., Veihelmann, B., van der Zande, W. J., Leon, J.-F., Sorokin, M., and Slutsker, I. (2006). Application of spheroid models to account for aerosol particle nonsphericity in remote sensing of desert dust. Journal of Geophysical Research, 111, D11208, doi:10.1029/2005JD006619. Mishchenko, M. I., Lacis, A. A., Carlson, B. E., and Travis, L. D. (1995). Nonsphericity of dust-like aerosols: Implications for aerosol remote sensing and climate modeling, Geophyscal Research Letters, 22, 1077- 1080. Mishchenko, M. I., Travis, L. D., Kahn, R. A., and West, R. A. (1997). Modeling phase functions for dustlike tropospheric aerosols using a shape mixture of randomly oriented polydisperse spheroids, Journal of Geophysical Research, 102, 16831- 16847.

Electronic states and optical properties of single donor in GaN conical quantum dot with spherical edge

NASA Astrophysics Data System (ADS)

El Aouami, A.; Feddi, E.; El-Yadri, M.; Aghoutane, N.; Dujardin, F.; Duque, C. A.; Phuc, Huynh Vinh

2018-02-01

In this paper we present a theoretical investigation of quantum confinement effects on the electron and single donor states in GaN conical quantum dot with spherical edge. In the framework of the effective mass approximation, the Schrödinger equations of electron and donor have been solved analytically in an infinite potential barrier model. Our calculations show that the energies of electron and donor impurity are affected by the two characteristic parameters of the structure which are the angle Ω and the radial dimension R. We show that, despite the fact that the reduction of the two parameters Ω and R leads to the same confinement effects, the energy remains very sensitive to the variation of the radial part than the variation of the angular part. The analysis of the photoionization cross-section corresponding to optical transitions between the conduction band and the first donor energy level shows clearly that the reduction of the radius R causes a shift in resonance peaks towards the high energies. On the other hand, the optical transitions between 1 s - 1 p , 1 p - 1 d and 1 p - 2 s show that the increment of the conical aperture Ω (or reduction of R) implies a displacement of the excitation energy to higher energies.

Statistical representation of multiphase flow

NASA Astrophysics Data System (ADS)

Subramaniam

2000-11-01

The relationship between two common statistical representations of multiphase flow, namely, the single--point Eulerian statistical representation of two--phase flow (D. A. Drew, Ann. Rev. Fluid Mech. (15), 1983), and the Lagrangian statistical representation of a spray using the dropet distribution function (F. A. Williams, Phys. Fluids 1 (6), 1958) is established for spherical dispersed--phase elements. This relationship is based on recent work which relates the droplet distribution function to single--droplet pdfs starting from a Liouville description of a spray (Subramaniam, Phys. Fluids 10 (12), 2000). The Eulerian representation, which is based on a random--field model of the flow, is shown to contain different statistical information from the Lagrangian representation, which is based on a point--process model. The two descriptions are shown to be simply related for spherical, monodisperse elements in statistically homogeneous two--phase flow, whereas such a simple relationship is precluded by the inclusion of polydispersity and statistical inhomogeneity. The common origin of these two representations is traced to a more fundamental statistical representation of a multiphase flow, whose concepts derive from a theory for dense sprays recently proposed by Edwards (Atomization and Sprays 10 (3--5), 2000). The issue of what constitutes a minimally complete statistical representation of a multiphase flow is resolved.

Multivariate statistical characterization of charged and uncharged domain walls in multiferroic hexagonal YMnO3 single crystal visualized by a spherical aberration-corrected STEM.

PubMed

Matsumoto, Takao; Ishikawa, Ryo; Tohei, Tetsuya; Kimura, Hideo; Yao, Qiwen; Zhao, Hongyang; Wang, Xiaolin; Chen, Dapeng; Cheng, Zhenxiang; Shibata, Naoya; Ikuhara, Yuichi

2013-10-09

A state-of-the-art spherical aberration-corrected STEM was fully utilized to directly visualize the multiferroic domain structure in a hexagonal YMnO3 single crystal at atomic scale. With the aid of multivariate statistical analysis (MSA), we obtained unbiased and quantitative maps of ferroelectric domain structures with atomic resolution. Such a statistical image analysis of the transition region between opposite polarizations has confirmed atomically sharp transitions of ferroelectric polarization both in antiparallel (uncharged) and tail-to-tail 180° (charged) domain boundaries. Through the analysis, a correlated subatomic image shift of Mn-O layers with that of Y layers, exhibiting a double-arc shape of reversed curvatures, have been elucidated. The amount of image shift in Mn-O layers along the c-axis is statistically significant as small as 0.016 nm, roughly one-third of the evident image shift of 0.048 nm in Y layers. Interestingly, a careful analysis has shown that such a subatomic image shift in Mn-O layers vanishes at the tail-to-tail 180° domain boundaries. Furthermore, taking advantage of the annular bright field (ABF) imaging technique combined with MSA, the tilting of MnO5 bipyramids, the very core mechanism of multiferroicity of the material, is evaluated.

Containerless solidification of BiFeO3 oxide under microgravity

NASA Astrophysics Data System (ADS)

Yu, Jianding; Arai, Yasutomo; Koshikawa, Naokiyo; Ishikawa, Takehito; Yoda, Shinichi

1999-07-01

Containerless solidification of BiFeO3 oxide has been carried out under microgravity with Electrostatic Levitation Furnace (ELF) aboard on the sounding rocket (TR-IA). It is a first containerless experiment using ELF under microgravity for studying the solidification of oxide insulator material. Spherical BiFeO3 sample with diameter of 5mm was heated by two lasers in oxygen and nitrogen mixing atmosphere, and the sample position by electrostatic force under pinpoint model and free drift model. In order to compare the solidification behavior in microgravity with on ground, solidification experiments of BiFeO3 in crucible and drop tube were carried out. In crucible experiment, it was very difficult to get single BiFeO3 phase, because segregation of Fe2O3 occured very fast and easily. In drop tube experiment, fine homogeneous BiFeO3 microstructure was obtained in a droplet about 300 μm. It implies that containerless processing can promote the phase selection in solidification. In microgravity experiment, because the heating temperature was lower than that of estimated, the sample was heated into Fe2O3+liquid phase region. Fe2O3 single crystal grew on the surface of the spherical sample, whose sample was clearly different from that observed in ground experiments.

A NEW SPECIES OF CARYOSPORA (APICOMPLEXA: EIMERIIDAE) FROM THE FLATHEAD SNAKE, TANTILLA GRACILIS (OPHIDIA: COLUBRIDAE), IN SOUTHEASTERN OKLAHOMA

PubMed Central

McAllister, Chris T.; Roehrs, Zachary P.; Seville, R. Scott

2012-01-01

A single flathead snake, Tantilla gracilis, collected in early October 2010 from Choctaw County, Oklahoma, was found to harbor an undescribed species of Caryospora. Oocysts of Caryospora choctawensis n. sp. were spherical to subspherical, 15.8 × 15.0 (14–18 × 14–16) μm with a thick bilayered wall and a shape index (length/width) of 1.1. A micropyle and an oocyst residuum are absent but prominent Stieda and bubble-like sub-Stieda bodies were present as well as a bilobed polar granule near the oocyst wall. Sporocysts were ovoidal, 10.8 × 9.0 (10–12 × 8–9) μm with a shape index of 1.3. The sporocyst residuum was spherical and composed of a cluster of granules often membrane-bound. This is the second time a caryosporan species has been reported from T. gracilis, but the first coccidian ever described from a reptilian host in Oklahoma. Additional T. gracilis from Arkansas (n = 6), Oklahoma (n = 1), and Texas (n = 7) were examined and a single specimen from Newton County, Arkansas, harbored Caryospora gracilis Upton, McAllister, Trauth, and Bibb, 1992, previously reported from T. gracilis collected in Arkansas and Texas. PMID:22191621

Integration of neutron time-of-flight single-crystal Bragg peaks in reciprocal space

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

Schultz, Arthur J; Joergensen, Mads; Wang, Xiaoping

2014-01-01

The intensity of single crystal Bragg peaks obtained by mapping neutron time-of-flight event data into reciprocal space and integrating in various ways are compared. These include spherical integration with a fixed radius, ellipsoid fitting and integrating of the peak intensity and one-dimensional peak profile fitting. In comparison to intensities obtained by integrating in real detector histogram space, the data integrated in reciprocal space results in better agreement factors and more accurate atomic parameters. Furthermore, structure refinement using integrated intensities from one-dimensional profile fitting is demonstrated to be more accurate than simple peak-minus-background integration.

Preparation and characterization of biodegradable magnetic carriers by single emulsion-solvent evaporation

NASA Astrophysics Data System (ADS)

Liu, Xianqiao; Kaminski, Michael D.; Riffle, Judy S.; Chen, Haitao; Torno, Michael; Finck, Martha R.; Taylor, LaToyia; Rosengart, Axel J.

2007-04-01

This paper describes a single emulsion-solvent evaporation protocol to prepare PEGylated biodegradable/biocompatible magnetic carriers by utilizing hydrophobic magnetite and a mixture of poly( D,L lactide-co-glycolide) (PLGA) and poly(lactic acid-block-polyethylene glycol) (PLA-PEG) (26:1 by mass) polymers. We characterized the magnetic microspheres in terms of morphology, composite microstructure, size and size distribution, and magnetic properties. Results show that the preparation produces magnetic microspheres with a good spherical morphology, small size (mean diameter of 1.2-1.5 μm) by means of large size distributions, and magnetizations up to 20-30 emu/g of microspheres.

Granular Media-Based Tunable Passive Vibration Suppressor

NASA Technical Reports Server (NTRS)

Dillon, Robert P.; Davis, Gregory L.; Shapiro, Andrew A.; Borgonia, John Paul C.; Kahn, Daniel L.; Boechler, Nicholas; Boechler,, Chiara

2013-01-01

and vibration suppression device is composed of statically compressed chains of spherical particles. The device superimposes a combination of dissipative damping and dispersive effects. The dissipative damping resulting from the elastic wave attenuation properties of the bulk material selected for the granular media is independent of particle geometry and periodicity, and can be accordingly designed based on the dissipative (or viscoelastic) properties of the material. For instance, a viscoelastic polymer might be selected where broadband damping is desired. In contrast, the dispersive effects result from the periodic arrangement and geometry of particles composing a linear granular chain. A uniform (monatomic) chain of statically compressed spherical particles will have a low-pass filter effect, with a cutoff frequency tunable as a function of particle mass, elastic modulus, Poisson fs ratio, radius, and static compression. Elastic waves with frequency content above this cutoff frequency will exhibit an exponential decay in amplitude as a function of propagation distance. System design targeting a specific application is conducted using a combination of theoretical, computational, and experimental techniques to appropriately select the particle radii, material (and thus elastic modulus and Poisson fs ratio), and static compression to satisfy estimated requirements derived for shock and/or vibration protection needs under particular operational conditions. The selection of a chain of polymer spheres with an elastic modulus .3 provided the appropriate dispersive filtering effect for that exercise; however, different operational scenarios may require the use of other polymers, metals, ceramics, or a combination thereof, configured as an array of spherical particles. The device is a linear array of spherical particles compressed in a container with a mechanism for attachment to the shock and/or vibration source, and a mechanism for attachment to the article requiring isolation (Figure 1). This configuration is referred to as a single-axis vibration suppressor. This invention also includes further designs for the integration of the single-axis vibration suppressor into a six-degree-of-freedom hexapod "Stewart"mounting configuration (Figure 2). By integrating each singleaxis vibration suppressor into a hexapod formation, a payload will be protected in all six degrees of freedom from shock and/or vibration. Additionally, to further enable the application of this device to multiple operational scenarios, particularly in the case of high loads, the vibration suppressor devices can be used in parallel in any array configuration.

Light scattering microscopy measurements of single nuclei compared with GPU-accelerated FDTD simulations

NASA Astrophysics Data System (ADS)

Stark, Julian; Rothe, Thomas; Kieß, Steffen; Simon, Sven; Kienle, Alwin

2016-04-01

Single cell nuclei were investigated using two-dimensional angularly and spectrally resolved scattering microscopy. We show that even for a qualitative comparison of experimental and theoretical data, the standard Mie model of a homogeneous sphere proves to be insufficient. Hence, an accelerated finite-difference time-domain method using a graphics processor unit and domain decomposition was implemented to analyze the experimental scattering patterns. The measured cell nuclei were modeled as single spheres with randomly distributed spherical inclusions of different size and refractive index representing the nucleoli and clumps of chromatin. Taking into account the nuclear heterogeneity of a large number of inclusions yields a qualitative agreement between experimental and theoretical spectra and illustrates the impact of the nuclear micro- and nanostructure on the scattering patterns.

Single-wall nanohorn structure and distribution of incorporated materials

NASA Astrophysics Data System (ADS)

Maigne, Alan; Gloter, Alexandre; Ajima, Kumiko; Colliex, Christian; Iijima, Sumio

2005-03-01

Single-wall carbon nanohorns (SWNHs) are unique spherical-aggregates of single-wall carbon quasi-nanotubes. So far, the observable area has been limited to the aggregate surfaces. We studied core-region structure with TEM using thickness measurement method, EELS, and EDS, and found that carbon density was uniform over the whole aggregate. This result allows to modelize the core-region and to clarify previous models of SWNHs. We used same tools to investigate the incorporation of materials such as fullerenes or platinium compounds. We found that particles can even be incorporated in the core-region and that their distribution in the aggregate depends on their concentration. The information available with these models should be useful in the study of SWNH applications to, for example, drug delivery system.

Light scattering microscopy measurements of single nuclei compared with GPU-accelerated FDTD simulations.

PubMed

Stark, Julian; Rothe, Thomas; Kieß, Steffen; Simon, Sven; Kienle, Alwin

2016-04-07

Single cell nuclei were investigated using two-dimensional angularly and spectrally resolved scattering microscopy. We show that even for a qualitative comparison of experimental and theoretical data, the standard Mie model of a homogeneous sphere proves to be insufficient. Hence, an accelerated finite-difference time-domain method using a graphics processor unit and domain decomposition was implemented to analyze the experimental scattering patterns. The measured cell nuclei were modeled as single spheres with randomly distributed spherical inclusions of different size and refractive index representing the nucleoli and clumps of chromatin. Taking into account the nuclear heterogeneity of a large number of inclusions yields a qualitative agreement between experimental and theoretical spectra and illustrates the impact of the nuclear micro- and nanostructure on the scattering patterns.

Investigation of ice particle habits to be used for ice cloud remote sensing for the GCOM-C satellite mission

NASA Astrophysics Data System (ADS)

Letu, Husi; Ishimoto, Hiroshi; Riedi, Jerome; Nakajima, Takashi Y.; -Labonnote, Laurent C.; Baran, Anthony J.; Nagao, Takashi M.; Sekiguchi, Miho

2016-09-01

In this study, various ice particle habits are investigated in conjunction with inferring the optical properties of ice clouds for use in the Global Change Observation Mission-Climate (GCOM-C) satellite programme. We develop a database of the single-scattering properties of five ice habit models: plates, columns, droxtals, bullet rosettes, and Voronoi. The database is based on the specification of the Second Generation Global Imager (SGLI) sensor on board the GCOM-C satellite, which is scheduled to be launched in 2017 by the Japan Aerospace Exploration Agency. A combination of the finite-difference time-domain method, the geometric optics integral equation technique, and the geometric optics method is applied to compute the single-scattering properties of the selected ice particle habits at 36 wavelengths, from the visible to the infrared spectral regions. This covers the SGLI channels for the size parameter, which is defined as a single-particle radius of an equivalent volume sphere, ranging between 6 and 9000 µm. The database includes the extinction efficiency, absorption efficiency, average geometrical cross section, single-scattering albedo, asymmetry factor, size parameter of a volume-equivalent sphere, maximum distance from the centre of mass, particle volume, and six nonzero elements of the scattering phase matrix. The characteristics of calculated extinction efficiency, single-scattering albedo, and asymmetry factor of the five ice particle habits are compared. Furthermore, size-integrated bulk scattering properties for the five ice particle habit models are calculated from the single-scattering database and microphysical data. Using the five ice particle habit models, the optical thickness and spherical albedo of ice clouds are retrieved from the Polarization and Directionality of the Earth's Reflectances-3 (POLDER-3) measurements, recorded on board the Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar (PARASOL) satellite. The optimal ice particle habit for retrieving the SGLI ice cloud properties is investigated by adopting the spherical albedo difference (SAD) method. It is found that the SAD is distributed stably due to the scattering angle increases for bullet rosettes with an effective diameter (Deff) of 10 µm and Voronoi particles with Deff values of 10, 60, and 100 µm. It is confirmed that the SAD of small bullet-rosette particles and all sizes of Voronoi particles has a low angular dependence, indicating that a combination of the bullet-rosette and Voronoi models is sufficient for retrieval of the ice cloud's spherical albedo and optical thickness as effective habit models for the SGLI sensor. Finally, SAD analysis based on the Voronoi habit model with moderate particle size (Deff = 60 µm) is compared with the conventional general habit mixture model, inhomogeneous hexagonal monocrystal model, five-plate aggregate model, and ensemble ice particle model. The Voronoi habit model is found to have an effect similar to that found in some conventional models for the retrieval of ice cloud properties from space-borne radiometric observations.

Comparison of objective refraction in darkness to cycloplegic refraction: a pilot study.

PubMed

Vasudevan, Balamurali; Ciuffreda, Kenneth J; Meehan, Kelly; Grk, Dejana; Cox, Misty

2016-03-01

The aim was to assess non-cycloplegic objective refraction in darkness using an open-field auto-refractor, and furthermore to compare it with distance cycloplegic subjective refraction and distance cycloplegic retinoscopy in the light, in children and young adults. Twenty-three, visually-normal, young-adults (46 eyes) ages 23 to 31 years, and five children (10 eyes) ages five to 12 years, participated in the study. The spherical component of their refraction ranged from -2.25 D to +3.75 D with a mean of +1.80 D, and a mean cylinder of -0.70 D. Three techniques were used to assess refractive error. An objective measure of the non-cycloplegic refractive state was obtained using an open-field autorefractor (WAM-5500) after five minutes in the dark to allow for dissipation of accommodative transients and relaxation of accommodation. In addition, both distance retinoscopy and subjective distance refraction were performed following cycloplegia (Cyclopentolate, 1%) using conventional clinical procedures. All measurements were obtained on the same day within a single session. The spherical component of the refraction was compared among the three techniques in both the children and adults. There was no significant difference in spherical refraction among the three techniques: non-cycloplegic objective refraction in the dark, distance cycloplegic retinoscopy and distance cycloplegic subjective refraction, in either the adults [F(2, 137) = 0.79, p = 0.45] or the children [F(2, 27) = 0.47, p = 0.62]. Mean difference in the spherical component between refraction in the dark and the cycloplegic distance retinoscopy was -0.34 D (r = 0.89) in the adults and +0.14 D (r = 0.96) in the children. The mean difference in spherical component between refraction in the dark and the cycloplegic distance subjective refraction was -0.25 D (r = 0.92) in the adults and -0.05 D (r = 0.95) in the children. Comparison of the spherical refractive component between the three techniques was not significantly different and furthermore, they were highly correlated in both the children and adults in this pilot study. Non-cycloplegic refraction in the dark may provide a reliable adjunct or alternative to conventional cycloplegic refraction in both children and young adults. © 2016 Optometry Australia.

Refractive Changes Induced by Spherical Aberration in Laser Correction Procedures: An Adaptive Optics Study.

PubMed

Amigó, Alfredo; Martinez-Sorribes, Paula; Recuerda, Margarita

2017-07-01

To study the effect on vision of induced negative and positive spherical aberration within the range of laser vision correction procedures. In 10 eyes (mean age: 35.8 years) under cyclopegic conditions, spherical aberration values from -0.75 to +0.75 µm in 0.25-µm steps were induced by an adaptive optics system. Astigmatism and spherical refraction were corrected, whereas the other natural aberrations remained untouched. Visual acuity, depth of focus defined as the interval of vision for which the target was still perceived acceptable, contrast sensitivity, and change in spherical refraction associated with the variation in pupil diameter from 6 to 2.5 mm were measured. A refractive change of 1.60 D/µm of induced spherical aberration was obtained. Emmetropic eyes became myopic when positive spherical aberration was induced and hyperopic when negative spherical aberration was induced (R 2 = 81%). There were weak correlations between spherical aberration and visual acuity or depth of focus (R 2 = 2% and 3%, respectively). Contrast sensitivity worsened with the increment of spherical aberration (R 2 = 59%). When pupil size decreased, emmetropic eyes became hyperopic when preexisting spherical aberration was positive and myopic when spherical aberration was negative, with an average refractive change of 0.60 D/µm of spherical aberration (R 2 = 54%). An inverse linear correlation exists between the refractive state of the eye and spherical aberration induced within the range of laser vision correction. Small values of spherical aberration do not worsen visual acuity or depth of focus, but positive spherical aberration may induce night myopia. In addition, the changes in spherical refraction when the pupil constricts may worsen near vision when positive spherical aberration is induced or improve it when spherical aberration is negative. [J Refract Surg. 2017;33(7):470-474.]. Copyright 2017, SLACK Incorporated.

Elementary Theoretical Forms for the Spatial Power Spectrum of Earth's Crustal Magnetic Field

NASA Technical Reports Server (NTRS)

Voorhies, C.

1998-01-01

The magnetic field produced by magnetization in Earth's crust and lithosphere can be distinguished from the field produced by electric currents in Earth's core because the spatial magnetic power spectrum of the crustal field differs from that of the core field. Theoretical forms for the spectrum of the crustal field are derived by treating each magnetic domain in the crust as the point source of a dipole field. The geologic null-hypothesis that such moments are uncorrelated is used to obtain the magnetic spectrum expected from a randomly magnetized, or unstructured, spherical crust of negligible thickness. This simplest spectral form is modified to allow for uniform crustal thickness, ellipsoidality, and the polarization of domains by an periodically reversing, geocentric axial dipole field from Earth's core. Such spectra are intended to describe the background crustal field. Magnetic anomalies due to correlated magnetization within coherent geologic structures may well be superimposed upon this background; yet representing each such anomaly with a single point dipole may lead to similar spectral forms. Results from attempts to fit these forms to observational spectra, determined via spherical harmonic analysis of MAGSAT data, are summarized in terms of amplitude, source depth, and misfit. Each theoretical spectrum reduces to a source factor multiplied by the usual exponential function of spherical harmonic degree n due to geometric attenuation with attitude above the source layer. The source factors always vary with n and are approximately proportional to n(exp 3) for degrees 12 through 120. The theoretical spectra are therefore not directly proportional to an exponential function of spherical harmonic degree n. There is no radius at which these spectra are flat, level, or otherwise independent of n.

Low resolution brain electromagnetic tomography in a realistic geometry head model: a simulation study

NASA Astrophysics Data System (ADS)

Ding, Lei; Lai, Yuan; He, Bin

2005-01-01

It is of importance to localize neural sources from scalp recorded EEG. Low resolution brain electromagnetic tomography (LORETA) has received considerable attention for localizing brain electrical sources. However, most such efforts have used spherical head models in representing the head volume conductor. Investigation of the performance of LORETA in a realistic geometry head model, as compared with the spherical model, will provide useful information guiding interpretation of data obtained by using the spherical head model. The performance of LORETA was evaluated by means of computer simulations. The boundary element method was used to solve the forward problem. A three-shell realistic geometry (RG) head model was constructed from MRI scans of a human subject. Dipole source configurations of a single dipole located at different regions of the brain with varying depth were used to assess the performance of LORETA in different regions of the brain. A three-sphere head model was also used to approximate the RG head model, and similar simulations performed, and results compared with the RG-LORETA with reference to the locations of the simulated sources. Multi-source localizations were discussed and examples given in the RG head model. Localization errors employing the spherical LORETA, with reference to the source locations within the realistic geometry head, were about 20-30 mm, for four brain regions evaluated: frontal, parietal, temporal and occipital regions. Localization errors employing the RG head model were about 10 mm over the same four brain regions. The present simulation results suggest that the use of the RG head model reduces the localization error of LORETA, and that the RG head model based LORETA is desirable if high localization accuracy is needed.

Robotically Assisted Sonic Therapy as a Noninvasive Nonthermal Ablation Modality: Proof of Concept in a Porcine Liver Model.

PubMed

Smolock, Amanda R; Cristescu, Mircea M; Vlaisavljevich, Eli; Gendron-Fitzpatrick, Annette; Green, Chelsey; Cannata, Jonathan; Ziemlewicz, Timothy J; Lee, Fred T

2018-05-01

Purpose To determine the feasibility of creating a clinically relevant hepatic ablation (ie, an ablation zone capable of treating a 2-cm liver tumor) by using robotically assisted sonic therapy (RAST), a noninvasive and nonthermal focused ultrasound therapy based on histotripsy. Materials and Methods This study was approved by the institutional animal use and care committee. Ten female pigs were treated with RAST in a single session with a prescribed 3-cm spherical treatment region and immediately underwent abdominal magnetic resonance (MR) imaging. Three pigs (acute group) were sacrificed immediately following MR imaging. Seven pigs (chronic group) were survived for approximately 4 weeks and were reimaged with MR imaging immediately before sacrifice. Animals underwent necropsy and harvesting of the liver for histologic evaluation of the ablation zone. RAST ablations were performed with a 700-kHz therapy transducer. Student t tests were performed to compare prescribed versus achieved ablation diameter, difference of sphericity from 1, and change in ablation zone volume from acute to chronic imaging. Results Ablation zones had a sphericity index of 0.99 ± 0.01 (standard deviation) (P < .001 vs sphericity index of 1). Anteroposterior and transverse dimensions were not significantly different from prescribed (3.4 ± 0.7; P = .08 and 3.2 ± 0.8; P = .29, respectively). The craniocaudal dimension was significantly larger than prescribed (3.8 ± 1.1; P = .04), likely because of respiratory motion. The central ablation zone demonstrated complete cell destruction and a zone of partial necrosis. A fibrous capsule surrounded the ablation zone by 4 weeks. On 4-week follow-up images, ablation zone volumes decreased by 64% (P < .001). Conclusion RAST is capable of producing clinically relevant ablation zones in a noninvasive manner in a porcine model. © RSNA, 2018.

Director Field Analysis (DFA): Exploring Local White Matter Geometric Structure in Diffusion MRI.

PubMed

Cheng, Jian; Basser, Peter J

2018-01-01

In Diffusion Tensor Imaging (DTI) or High Angular Resolution Diffusion Imaging (HARDI), a tensor field or a spherical function field (e.g., an orientation distribution function field), can be estimated from measured diffusion weighted images. In this paper, inspired by the microscopic theoretical treatment of phases in liquid crystals, we introduce a novel mathematical framework, called Director Field Analysis (DFA), to study local geometric structural information of white matter based on the reconstructed tensor field or spherical function field: (1) We propose a set of mathematical tools to process general director data, which consists of dyadic tensors that have orientations but no direction. (2) We propose Orientational Order (OO) and Orientational Dispersion (OD) indices to describe the degree of alignment and dispersion of a spherical function in a single voxel or in a region, respectively; (3) We also show how to construct a local orthogonal coordinate frame in each voxel exhibiting anisotropic diffusion; (4) Finally, we define three indices to describe three types of orientational distortion (splay, bend, and twist) in a local spatial neighborhood, and a total distortion index to describe distortions of all three types. To our knowledge, this is the first work to quantitatively describe orientational distortion (splay, bend, and twist) in general spherical function fields from DTI or HARDI data. The proposed DFA and its related mathematical tools can be used to process not only diffusion MRI data but also general director field data, and the proposed scalar indices are useful for detecting local geometric changes of white matter for voxel-based or tract-based analysis in both DTI and HARDI acquisitions. The related codes and a tutorial for DFA will be released in DMRITool. Copyright © 2017 Elsevier B.V. All rights reserved.

A method for the prescription of inexpensive spectacles by non-specialist healthcare workers: S-Glasses

PubMed Central

Treacy, M P; Treacy, M G; Dimitrov, B D; Seager, F E; Stamp, M A; Murphy, C C

2013-01-01

Purpose Globally, 153 million people are visually impaired from uncorrected refractive error. The aim of this research was to verify a method whereby autorefractors could be used by non-specialist health-workers to prescribe spectacles, which used a small stock of preformed lenses that fit frames with standardised apertures. These spectacles were named S-Glasses (Smart Glasses). Patients and methods This prospective, single-cohort exploratory study enrolled 53 patients with 94 eligible eyes having uncorrected vision of 6/18 or worse. Eyes with best-corrected vision worse than 6/12 were excluded. An autorefractor was used to obtain refractions, which were adjusted so that eyes with astigmatism less than 2.00 dioptres (D) received spherical equivalent lenses, and eyes with more astigmatism received toric lenses with a 2.50 D cylindrical element set at one of four meridians. The primary outcome was to compare S-Glasses vision with the WHO definition of visual impairment (6/18). Where astigmatism was 2.00 D or greater, comparison with spherical equivalent was made. Mixed-model analysis with repeated effect was used to account for possible correlation between the vision of fellow eyes of the same individual. Results S-Glasses corrected 100% of eyes with astigmatism less than 3.00 D and 69% of eyes with astigmatism of 3.00 D or greater. Spherical equivalent lenses corrected 25% of eyes with astigmatism of 2.00−2.99 D and 11% with astigmatism of at least 3.00 D. Discussion S-Glasses could be beneficial to resource-poor populations without trained refractionists. This novel approach, using approximate toric lenses, results in superior vision for astigmatic patients compared with the practice of providing spherical equivalent alone. PMID:23306732

High-performance porous spherical or octapod-like single-crystalline BiVO4 photocatalysts for the removal of phenol and methylene blue under visible-light illumination.

PubMed

Jiang, Haiyan; Meng, Xue; Dai, Hongxing; Deng, Jiguang; Liu, Yuxi; Zhang, Lei; Zhao, Zhenxuan; Zhang, Ruzhen

2012-05-30

Monoclinic BiVO(4) single-crystallites with a polyhedral, spherical or porous octapod-like morphology were selectively prepared using the triblock copolymer P123 (HO(CH(2)CH(2)O)(20)(CH(2)CH(CH(3))O)(70)(CH(2)CH(2)O)(20)H)-assisted hydrothermal method with bismuth nitrate and ammonium metavanadate as metal source and various bases as pH adjustor. The BiVO(4) materials were well characterized and their photocatalytic activities were evaluated for the removal of methylene blue (MB) and phenol in the presence of a small amount of H(2)O(2) under visible-light illumination. It is shown that the pH value of the precursor solution, surfactant, and hydrothermal temperature had an important impact on particle architecture of the BiVO(4) product. The introduction of P123 favored the generation of BiVO(4) with porous structures. The BiVO(4) derived hydrothermally with P123 at pH 3 or 6 possessed good optical absorption performance both in UV- and visible-light regions and hence showed excellent photocatalytic activities for the degradation of MB and phenol. It is concluded that the high visible-light-driven catalytic performance of the porous octapod-like BiVO(4) single-crystallites is associated with the higher surface area, porous structure, lower band gap energy, and unique particle morphology. Such porous BiVO(4) materials are useful in the solar-light-driven photocatalytic treatment of organic-containing wastewater. Copyright © 2012 Elsevier B.V. All rights reserved.

Detection of macrophages in atherosclerotic tissue using magnetic nanoparticles and differential phase optical coherence tomography.

PubMed

Oh, Junghwan; Feldman, Marc D; Kim, Jihoon; Sanghi, Pramod; Do, Dat; Mancuso, J Jacob; Kemp, Nate; Cilingiroglu, Mehmet; Milner, Thomas E

2008-01-01

We demonstrate the detection of iron oxide nanoparticles taken up by macrophages in atherosclerotic plaque with differential phase optical coherence tomography (DP-OCT). Magneto mechanical detection of nanoparticles is demonstrated in hyperlipidemic Watanabe and balloon-injured fat-fed New Zealand white rabbits injected with monocrystalline iron oxide nanoparticles (MIONs) of < 40 nm diam. MIONs taken up by macrophages was excited by an oscillating magnetic flux density and resulting nanometer tissue surface displacement was detected by DP-OCT. Frequency response of tissue surface displacement in response to an externally applied magnetic flux density was twice the stimulus frequency as expected from the equations of motion for the nanoparticle cluster.

Ion optics for high power 50-cm-diam ion thrusters

NASA Technical Reports Server (NTRS)

Rawlin, Vincent K.; Millis, Marc G.

1989-01-01

The process used at the NASA-Lewis to fabricate 30 and 50-cm-diameter ion optics is described. The ion extraction capabilities of the 30 and 50-cm diameter ion optics were evaluated on divergent field and ring-cusp discharge chambers and compared. Perveance was found to be sensitive to the effects of the type and power of the discharge chamber and to the accelerator electrode hole diameter. Levels of up to 0.64 N and 20 kW for thrust and input power, respectively, were demonstrated with the divergent-field discharge chamber. Thruster efficiencies and specific impulse values up to 79 percent and 5000 sec., respectively, were achieved with the ring-cusp discharge chamber.

Noise generated by flow through large butterfly valves

NASA Technical Reports Server (NTRS)

Huff, Ronald G.

1987-01-01

A large butterfly valve (1.37 m diam) was acoustically tested to measure the noise generated and propagating in both the upstream and downstream directions. The experimental investigation used wall mounted pressure transducers to measure the fluctuating component of the pipe static pressure upstream and downstream of the valve. Microphones upstream of the pipe inlet and located in a plenum were used to measure the noise radiated from the valve in the upstream direction. Comparison of the wall pressure downstream of the valve to a prediction were made. Reasonable agreement was obtained with the valve operating at a choked condition. The noise upstream of the valve is 30 dB less than that measured downstream.

The formation of the solar system - Consensus, alternatives, and missing factors

NASA Technical Reports Server (NTRS)

Wetherill, George W.

1989-01-01

The current status on the theories of the solar-system formation is overviewed with emphasis placed on the principal concepts and processes involved. These processes include the formation of about 1 to 10 km diam planetesimals from the dust of the solar nebula; the physical processes that govern the interaction of these planetesimals with one another, which control their size and their velocity distribution; the circumstances that determine the way in which the planetesimals grow into planetary embryos; the processes that are likely to be important during the final stages of accumulation; and the possible origin of differences between the accumulation of the terrestrial planets, the giant planets, and the asteroids.

Control of the permeability loss-peak frequency of Ni81Fe19 thin films through laser ablation of triangular and square cluster geometries

NASA Technical Reports Server (NTRS)

Grimes, C. A.; Lumpp, J. K.

2000-01-01

Laser ablation arrays of triangular and square shaped clusters, comprised of 23 micrometers diam circular holes, are defined upon 100 nm thick Ni81Fe19 films used to control the rf permeability spectra. Cluster-to-cluster spacing is varied from 200 to 600 micrometers. For each geometry it is found that the loss peak frequency and permeability magnitude shift lower, in a step-wise fashion, at a cluster-to-cluster spacing between 275 and 300 micrometers. The nonlinear shift in the behavior of the permeability spectra correlates with a dramatic increase in domain wall density. c2000 American Institute of Physics.

Validation of the filament winding process model

NASA Technical Reports Server (NTRS)

Calius, Emilo P.; Springer, George S.; Wilson, Brian A.; Hanson, R. Scott

1987-01-01

Tests were performed toward validating the WIND model developed previously for simulating the filament winding of composite cylinders. In these tests two 24 in. long, 8 in. diam and 0.285 in. thick cylinders, made of IM-6G fibers and HBRF-55 resin, were wound at + or - 45 deg angle on steel mandrels. The temperatures on the inner and outer surfaces and inside the composite cylinders were recorded during oven cure. The temperatures inside the cylinders were also calculated by the WIND model. The measured and calculated temperatures were then compared. In addition, the degree of cure and resin viscosity distributions inside the cylinders were calculated for the conditions which existed in the tests.

Broadband, Achromatic Twyman-Green Interferometer

NASA Technical Reports Server (NTRS)

Steimle, Lawrence J.

1991-01-01

Improved Twyman-Green interferometer used in wave-front testing optical components at wavelengths from 200 to 1,100 nm, without having to readjust focus when changing wavelength. Built to measure aberrations of light passing through optical filters. Collimating and imaging lenses of classical Twyman-Green configuration replaced by single spherical mirror. Field lens replaced by field mirror. Mirrors exhibit no axial chromatic aberration and made to reflect light efficiently over desired broad range of wavelengths.

Localized Tissue Surrogate Deformation due to Controlled Single Bubble Cavitation

DTIC Science & Technology

2014-08-27

calculate liquid jet formation with collapse of an empty spherical bubble due to the high surrounding fluid pressure 18. Experimental evidence of...maximum collapse pressures over a wide range between 8 MPa 13 to 2.5 GPa 11 have also been calculated . 5 A fundamental problem in the study of...and a digital image correlation (DIC) technique was used to calculate strain fields during bubble growth and collapse. The subsequent response of the

Elastic-Plastic Behavior of Cyclotrimethylene Trinitramine Single Crystals Under Spherical Indentation: Modeling and Simulation

DTIC Science & Technology

2012-04-01

M. Winey and Y. M. Gupta, J. Appl. Phys. 107, 103505 (2010). 13R. Becker, Int. J. Plast. 20, 1983 (2004). 14B. Olinger, B. Roof, and H. H. Cady ...f011g, f021g (010), f011g, 021ð Þ 063512-8 J. D. Clayton and R. Becker J. Appl. Phys. 111, 063512 (2012) 18H. H. Cady , J. Chem. Eng. Data 17, 369

Creation of short microwave ablation zones: in vivo characterization of single and paired modified triaxial antennas.

PubMed

Lubner, Meghan G; Ziemlewicz, Tim J; Hinshaw, J Louis; Lee, Fred T; Sampson, Lisa A; Brace, Christopher L

2014-10-01

To characterize modified triaxial microwave antennas configured to produce short ablation zones. Fifty single-antenna and 27 paired-antenna hepatic ablations were performed in domestic swine (N = 11) with 17-gauge gas-cooled modified triaxial antennas powered at 65 W from a 2.45-GHz generator. Single-antenna ablations were performed at 2 (n = 16), 5 (n = 21), and 10 (n = 13) minutes. Paired-antenna ablations were performed at 1-cm and 2-cm spacing for 5 (n = 7 and n = 8, respectively) and 10 minutes (n = 7 and n = 5, respectively). Mean transverse width, length, and aspect ratio of sectioned ablation zones were measured and compared. For single antennas, mean ablation zone lengths were 2.9 cm ± 0.45, 3.5 cm ± 0.55, and 4.2 cm ± 0.40 at 2, 5, and 10 minutes, respectively. Mean widths were 1.8 cm ± 0.3, 2.0 cm ± 0.32, and 2.5 cm ± 0.25 at 2, 5, and 10 minutes, respectively. For paired antennas, mean length at 5 minutes with 1-cm and 2-cm spacing and 10 minutes with 1-cm and 2-cm spacing was 4.2 cm ± 0.9, 4.9 cm ± 1.0, 4.8 cm ± 0.5, and 4.8 cm ± 1.3, respectively. Mean width was 3.1 cm ± 1.0, 4.4 cm ± 0.7, 3.8 cm ± 0.4, and 4.5 cm ± 0.7, respectively. Paired-antenna ablations were more spherical (aspect ratios, 0.72-0.79 for 5-10 min) than single-antenna ablations (aspect ratios, 0.57-0.59). For paired-antenna ablations, 1-cm spacing appeared optimal, with improved circularity and decreased clefting compared with 2-cm spacing (circularity, 0.85 at 1 cm, 0.78 at 2 cm). Modified triaxial antennas can generate relatively short, spherical ablation zones. Paired-antenna ablations were rounder and larger in transverse dimension than single antenna ablations, with 1-cm spacing optimal for confluence of the ablation zone. Copyright © 2014 SIR. Published by Elsevier Inc. All rights reserved.

Creation of short microwave ablation zones: In Vivo Characterization of single and paired Modified Triaxial Antennas Laboratory Investigation

PubMed Central

Lubner, Meghan G.; Ziemlewicz, Tim J; Hinshaw, J. Louis; Lee, Fred T.; Sampson, Lisa J.; Brace, Chris L.

2014-01-01

Purpose To characterize modified triaxial microwave antennas configured to produce short ablation zones. Materials and Methods 50 single- and 27 paired-antenna hepatic ablations were performed in domestic swine (n=11) with 17-gauge, gas-cooled modified triaxial antennas powered at 65W from a 2.45 GHz generator. Single-antenna ablations were performed at 2 (n=16), 5 (n=21), and 10 (n=13) minutes. Paired-antenna ablations were performed at 1-cm and 2-cm spacing for 5 (n=7, n=8) and 10 minutes (n=7, n=5). Mean transverse width, length and aspect ratio of sectioned ablation zones were measured and compared. Results For single antennas, mean ablation zone length was 2.9±0.45, 3.5±0.55 and 4.2±0.40 cm at 2, 5, and 10 minutes respectively. Mean width was 1.8±0.3, 2.0±0.32, 2.5±0.25 cm at 2, 5, and 10 minutes. For paired antennas, mean length at 5 min 1 and 2 cm and 10 min 1 and 2 cm spacing was 4.2±0.9, 4.4±0.9, 4.8±0.5 and 4.3±0.9 cm respectively. Mean width was 3.1±1.0, 4.0±0.8 and 3.8±0.4, 4.2±0.6 cm respectively. Paired-antenna ablations were more spherical (aspect ratios 0.72-0.79 for 5-10 min) than single-antenna ablations (0.57-0.59). For paired-antenna ablations, 1 cm spacing appeared optimal, with improved circularity and decreased clefting compared to 2 cm spacing (circ 1 cm 0.85, 2 cm 0.78). Conclusion Modified triaxial antennas can generate relatively short, spherical ablation zones. Paired-antenna ablations were rounder and larger in transverse dimension compared to single antenna ablations, with 1 cm spacing optimal for confluence of the ablation zone. PMID:25156644

A New CV3 Chondrite Find

NASA Astrophysics Data System (ADS)

Treiman, A. H.; Dehart, J. M.

1992-07-01

A new meteorite find from West Texas, U.S.A., is a CV3 carbonaceous chondrite. The provisional name of Red Bluff has been proposed to the Nomenclature Committee by R. Farrell. Red Bluff consists of chondrules (56.4%), CAIs (8.3%), amoboid olivine aggregates (0.6%), mineral fragments (0.8%), and Ca-Al chondrules (0.4%) in a fine-grained, clay-rich matrix (33.1%). Chondrules in Red Bluff are spherical to irregular in shape, and from 0.25-3.5 mm diameter in thin section; the average diameter is 0.95 mm, with standard deviation of 0.6 mm (69 chondrules). Three of the chondrules are distinctly larger than the rest; without these three, the average diameter is 0.86 mm (s.d. 0.4 mm). The chondrules are almost all of type I (Fe-poor), as shown by cathodoluminescence and chemical analyses; most are also rich in opaques. Compositions of chondrule olivines average Fa1.9+-1.2 (s.d.); compositions of chondrule pyroxenes average Fs3.4+-3.3 (s.d.). Chondrule varieties include porphyritic olivine, microporphyritic olivine, granular olivine, macroporphyritic olivine, barred olivine, and rare extracentroradial pyroxene (0.25 mm diam.) [1,2]. Two calcium-aluminum chondrules were observed. The largest, 1.5 mm diam., contains spinel, plagioclase, and fassaite, and includes a circular spinel palisade [3]. The other Ca-Al chondrule is within a coarse-grained CAI, and could also be a well-developed spinel palisade [3]. Fine- and coarse-grained CAIs are present but have been studied little; most appear to be type B (melilite+pyroxene+plagioclase). Red Bluff's matrix is composed of fine-grained clay, with minor olivine, "limonite," troilite, and Fe metal. Alignment of grains and oxide-rich streaks in the matrix mark a planar fabric that wraps around chondrules and inclusions. Chondrules are commonly surrounded by shells of dark red alteration, darker than the bulk of matrix material. Red Bluff is weathered. It is stained red by oxidized iron minerals, which are most common as veinlets (after Fe metal or troilite?) and as rinds around Fe metal and troilite. The matrix clays may have formed during weathering of an olivine matrix similar to that of Allende. However, Fe metal and troilite remain common, both occluded within silicates and as discrete grains in the matrix. Cracks in Red Bluff are partially filled by minute, euhedral carbonate crystals. Red Bluff's exterior is coated with desert varnish (light-brown anisotropic film composed of many fine laminae); the varnish fills void space in one carbonate-rich veinlet. Classification Red Bluff's petrography, mineralogy, and mineral chemistry fall within the range of known CV3s [4]. Most characteristic are the proportion of matrix (33%) and the size of chondrules (avg ~1 mm), which are consistent with CV and inconsistent with known CI, CO, CM, CR, and CK chondrites. The proportions of CAIs, Ca-Al chondrules, and mineral fragments are also consistent with known CVs. The presence of type 1 and type 2 chondrules, and the variations in olivine compositions among type 1 chondrules implies that Red Bluff is of metamorphic grade 3. Compared to other CV3s, Red Bluff has rather little matrix and rather magnesian silicate minerals [4]. Red Bluff does not appear to be paired with known CV3s, and in fact none are known from West Texas [5]; the closest CV3 fall or find is Leoville (KS) [5]. This work was conducted under an NRC Fellowships to Treiman (senior) and DeHart (regular). We are grateful to R. Farrell for the meteorite sample, data on its source, and its proposed name. [1] Scott E. R. D. and Taylor G. J. (1983) Proc. 14 LPSC, B275. [2] Jones R. (1992) GCA 56, 467. [3] Wark D. A. and Lovering J. F. (1982) GCA 46, 2595. [4] McSween H. Y. Jr. (1977) GCA 71, 1777. [5] Graham et al. (1985) Catalog of Meteorites.

Single step synthesis of nanostructured boron nitride for boron neutron capture therapy

NASA Astrophysics Data System (ADS)

Singh, Bikramjeet; Singh, Paviter; Kumar, Manjeet; Thakur, Anup; Kumar, Akshay

2015-05-01

Nanostructured Boron Nitride (BN) has been successfully synthesized by carbo-thermic reduction of Boric Acid (H3BO3). This method is a relatively low temperature synthesis route and it can be used for large scale production of nanostructured BN. The synthesized nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analyzer (DTA). XRD analysis confirmed the formation of single phase nanostructured Boron Nitride. SEM analysis showed that the particles are spherical in shape. DTA analysis showed that the phase is stable upto 900 °C and the material can be used for high temperature applications as well boron neutron capture therapy (BNCT).

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

Takai, Yoshizo; Kawasaki, Tadahiro; Kimura, Yoshihide

A single-atom-sized gold wire was successfully observed in real time by a newly developed defocus-image modulation processing electron microscope. Because of phase retrieval processing with spherical aberration correction, the single-atom strand wire was observed with high contrast and without contrast blurring. By carefully looking at the atomic distance, the contrast, and the dynamic behavior of the wire, we recognized that there are two stages of the wire. In the first stage the wire maintained the atomic distance in the bulk crystal, but in the second stage the wire showed the atomic distance of the nearest-neighbor atoms with weaker contrast. Themore » gold wire was rather stable for a few seconds under strong electron beam illumination.« less

Impact of and correction for instrument sensitivity drift on nanoparticle size measurements by single-particle ICP-MS

PubMed Central

El Hadri, Hind; Petersen, Elijah J.; Winchester, Michael R.

2016-01-01

The effect of ICP-MS instrument sensitivity drift on the accuracy of NP size measurements using single particle (sp)ICP-MS is investigated. Theoretical modeling and experimental measurements of the impact of instrument sensitivity drift are in agreement and indicate that drift can impact the measured size of spherical NPs by up to 25 %. Given this substantial bias in the measured size, a method was developed using an internal standard to correct for the impact of drift and was shown to accurately correct for a decrease in instrument sensitivity of up to 50 % for 30 nm and 60 nm gold nanoparticles. PMID:26894759

Temperature mapping of laser-induced hyperthermia in an ocular phantom using magnetic resonance thermography.

PubMed

Maswadi, Saher M; Dodd, Stephen J; Gao, Jia-Hong; Glickman, Randolph D

2004-01-01

Laser-induced heating in an ocular phantom is measured with magnetic resonance thermography (MRT) using temperature-dependent phase changes in proton resonance frequency. The ocular phantom contains a layer of melanosomes isolated from bovine retinal pigment epithelium. The phantom is heated by the 806-nm output of a continuous wave diode laser with an irradiance of 2.4 to 21.6 W/cm2 in a beam radius of 0.8 or 2.4 mm, depending on the experiment. MRT is performed with a 2 T magnet, and a two-turn, 6-cm-diam, circular radio frequency coil. Two-dimensional temperature gradients are measured within the plane of the melanin layer, as well as normal to it, with a temperature resolution of 1 degrees C or better. The temperature gradients extending within the melanin layer are broader than those orthogonal to the layer, consistent with the higher optical absorption and consequent heating in the melanin. The temperature gradients in the phantom measured by MRT closely approximate the predictions of a classical heat diffusion model. Three-dimensional temperature maps with a spatial resolution of 0.25 mm in all directions are also made. Although the temporal resolution is limited in the prototype system (22.9 s for a single image "slice"), improvements in future implementations are likely. These results indicate that MRT has sufficient spatial and temperature resolution to monitor target tissue temperature during transpupillary thermotherapy in the human eye.

Generalized seniority on a deformed single-particle basis

NASA Astrophysics Data System (ADS)

Jia, L. Y.

2017-09-01

Recently, I proposed a fast computing scheme for generalized seniority on a spherical single-particle basis [J. Phys. G: Nucl. Part. Phys. 42, 115105 (2015), 10.1088/0954-3899/42/11/115105]. This work redesigns the scheme to make it applicable to deformed single-particle basis. The algorithm is applied to the rare-earth-metal nucleus 94 64 158Gd for intrinsic (body-fixed frame) neutron excitations under the low-momentum NN interaction Vlow -k. By allowing as many as four broken pairs, I compute the lowest 300 intrinsic states of several multipolarities. These states converge well to the exact ones, showing generalized seniority is very effective in truncating the deformed shell model. Under realistic interactions, the picture remains approximately valid: The ground state is a coherent pair condensate and the pairs gradually break up as excitation energy increases.

Comparison of SPHC Hydrocode Results with Penetration Equations and Results of Other Codes

NASA Technical Reports Server (NTRS)

Evans, Steven W.; Stallworth, Roderick; Stellingwerf, Robert F.

2004-01-01

The SPHC hydrodynamic code was used to simulate impacts of spherical aluminum projectiles on a single-wall aluminum plate and on a generic Whipple shield. Simulations were carried out in two and three dimensions. Projectile speeds ranged from 2 kilometers per second to 10 kilometers per second for the single-wall runs, and from 3 kilometers per second to 40 kilometers per second for the Whipple shield runs. Spallation limit results of the single-wall simulations are compared with predictions from five standard penetration equations, and are shown to fall comfortably within the envelope of these analytical relations. Ballistic limit results of the Whipple shield simulations are compared with results from the AUTODYN-2D and PAM-SHOCK-3D codes presented in a paper at the Hypervelocity Impact Symposium 2000 and the Christiansen formulation of 2003.

Clinical Long-Term Outcome and Reinterventional Rate After Uterine Fibroid Embolization with Nonspherical Versus Spherical Polyvinyl Alcohol Particles

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

Duvnjak, Stevo, E-mail: stevo.duvnjak@rsyd.dk; Ravn, Pernille; Green, Anders

PurposeThis study was designed to evaluate the long-term clinical outcome and frequency of reinterventions in patients with uterine fibroids treated with embolization at a single center using polyvinyl alcohol microparticles.MethodsThe study included all patients with symptomatic uterine fibroids treated with uterine fibroid embolization (UFE) with spherical (s-PVA) and nonspherical (ns-PVA) polyvinyl alcohol microparticles during the period January 2001 to January 2011. Clinical success and secondary interventions were examined. Hospital records were reviewed during follow-up, and symptom-specific questionnaires were sent to all patients.ResultsIn total, 515 patients were treated with UFE and 350 patients (67 %) were available for long-term clinical follow-up. Medianmore » time of follow-up was 93 (range 76–120.2) months. Eighty-five patients (72 %) had no reinterventions during follow-up in the group embolized with ns-PVA compared with 134 patients (58 %) treated with s-PVA. Thirty-three patients (28 %) underwent secondary interventions in the ns-PVA group compared with 98 patients (42 %) in s-PVA group (χ{sup 2} test, p < 0.01).ConclusionsSpherical PVA particles 500–700 µm showed high reintervention rate at long-term follow-up, and almost one quarter of the patients underwent secondary interventions, suggesting that this type of particle is inappropriate for UFE.« less

Tunability and stability of gold nanoparticles obtained from chloroauric acid and sodium thiosulfate reaction

PubMed Central

2012-01-01

In the quest for producing an effective, clinically relevant therapeutic agent, scalability, repeatability, and stability are paramount. In this paper, gold nanoparticles (GNPs) with precisely controlled near-infrared (NIR) absorption are synthesized by a single-step reaction of HAuCl4 and Na2S2O3 without assistance of additional templates, capping reagents, or seeds. The anisotropy in the shape of gold nanoparticles offers high NIR absorption, making it therapeutically relevant. The synthesized products consist of GNPs with different shapes and sizes, including small spherical colloid gold particles and non-spherical gold crystals. The NIR absorption wavelengths and particle size increase with increasing molar ratio of HAuCl4/Na2S2O3. Non-spherical gold particles can be further purified and separated by centrifugation to improve the NIR-absorbing fraction of particles. In-depth studies reveal that GNPs with good structural and optical stability only form in a certain range of the HAuCl4/Na2S2O3 molar ratio, whereas higher molar ratios result in unstable GNPs, which lose their NIR absorption peak due to decomposition and reassembly via Ostwald ripening. Tuning the optical absorption of the gold nanoparticles in the NIR regime via a robust and repeatable method will improve many applications requiring large quantities of desired NIR-absorbing nanoparticles. PMID:22726762

MISR Global Aerosol Product Assessment by Comparison with AERONET

NASA Technical Reports Server (NTRS)

Kahn, Ralph A.; Gaitley, Barbara J.; Garay, Michael J.; Diner, David J.; Eck, Thomas F.; Smirnov, Alexander; Holben, Brent N.

2010-01-01

A statistical approach is used to assess the quality of the MISR Version 22 (V22) aerosol products. Aerosol Optical Depth (AOD) retrieval results are improved relative to the early post- launch values reported by Kahn et al. [2005a], varying with particle type category. Overall, about 70% to 75% of MISR AOD retrievals fall within 0.05 or 20% AOD of the paired validation data, and about 50% to 55% are within 0.03 or 10% AOD, except at sites where dust, or mixed dust and smoke, are commonly found. Retrieved particle microphysical properties amount to categorical values, such as three groupings in size: "small," "medium," and "large." For particle size, ground-based AERONET sun photometer Angstrom Exponents are used to assess statistically the corresponding MISR values, which are interpreted in terms of retrieved size categories. Coincident Single-Scattering Albedo (SSA) and fraction AOD spherical data are too limited for statistical validation. V22 distinguishes two or three size bins, depending on aerosol type, and about two bins in SSA (absorbing vs. non-absorbing), as well as spherical vs. non-spherical particles, under good retrieval conditions. Particle type sensitivity varies considerably with conditions, and is diminished for mid-visible AOD below about 0.15 or 0.2. Based on these results, specific algorithm upgrades are proposed, and are being investigated by the MISR team for possible implementation in future versions of the product.

Image-based gradient non-linearity characterization to determine higher-order spherical harmonic coefficients for improved spatial position accuracy in magnetic resonance imaging.

PubMed

Weavers, Paul T; Tao, Shengzhen; Trzasko, Joshua D; Shu, Yunhong; Tryggestad, Erik J; Gunter, Jeffrey L; McGee, Kiaran P; Litwiller, Daniel V; Hwang, Ken-Pin; Bernstein, Matt A

2017-05-01

Spatial position accuracy in magnetic resonance imaging (MRI) is an important concern for a variety of applications, including radiation therapy planning, surgical planning, and longitudinal studies of morphologic changes to study neurodegenerative diseases. Spatial accuracy is strongly influenced by gradient linearity. This work presents a method for characterizing the gradient non-linearity fields on a per-system basis, and using this information to provide improved and higher-order (9th vs. 5th) spherical harmonic coefficients for better spatial accuracy in MRI. A large fiducial phantom containing 5229 water-filled spheres in a grid pattern is scanned with the MR system, and the positions all the fiducials are measured and compared to the corresponding ground truth fiducial positions as reported from a computed tomography (CT) scan of the object. Systematic errors from off-resonance (i.e., B0) effects are minimized with the use of increased receiver bandwidth (±125kHz) and two acquisitions with reversed readout gradient polarity. The spherical harmonic coefficients are estimated using an iterative process, and can be subsequently used to correct for gradient non-linearity. Test-retest stability was assessed with five repeated measurements on a single scanner, and cross-scanner variation on four different, identically-configured 3T wide-bore systems. A decrease in the root-mean-square error (RMSE) over a 50cm diameter spherical volume from 1.80mm to 0.77mm is reported here in the case of replacing the vendor's standard 5th order spherical harmonic coefficients with custom fitted 9th order coefficients, and from 1.5mm to 1mm by extending custom fitted 5th order correction to the 9th order. Minimum RMSE varied between scanners, but was stable with repeated measurements in the same scanner. The results suggest that the proposed methods may be used on a per-system basis to more accurately calibrate MR gradient non-linearity coefficients when compared to vendor standard corrections. Copyright © 2016 Elsevier Inc. All rights reserved.

SU-E-I-79: Source Geometry Dependence of Gamma Well-Counter Measurements

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

Park, M; Belanger, A; Kijewski, M

Purpose: To determine the effect of liquid sample volume and geometry on counting efficiency in a gamma well-counter, and to assess the relative contributions of sample geometry and self-attenuation. Gamma wellcounters are standard equipment in clinical and preclinical studies, for measuring patient blood radioactivity and quantifying animal tissue uptake for tracer development and other purposes. Accurate measurements are crucial. Methods: Count rates were measured for aqueous solutions of 99m- Tc at four liquid volume values in a 1-cm-diam tube and at six volume values in a 2.2-cm-diam vial. Total activity was constant for all volumes, and data were corrected formore » decay. Count rates from a point source in air, supported by a filter paper, were measured at seven heights between 1.3 and 5.7 cm from the bottom of a tube. Results: Sample volume effects were larger for the tube than for the vial. For the tube, count efficiency relative to a 1-cc volume ranged from 1.05 at 0.05 cc to 0.84 at 3 cc. For the vial, relative count efficiency ranged from 1.02 at 0.05 cc to 0.87 at 15 cc. For the point source, count efficiency relative to 1.3 cm from the tube bottom ranged from 0.98 at 1.8 cm to 0.34 at 5.7 cm. The relative efficiency of a 3-cc liquid sample in a tube compared to a 1-cc sample is 0.84; the average relative efficiency for the solid sample in air between heights in the tube corresponding to the surfaces of those volumes (1.3 and 4.8 cm) is 0.81, implying that the major contribution to efficiency loss is geometry, rather than attenuation. Conclusion: Volume-dependent correction factors should be used for accurate quantitation radioactive of liquid samples. Solid samples should be positioned at the bottom of the tube for maximum count efficiency.« less

Occurrence of spherical ceramic debris in indentation and sliding contact

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.

1982-01-01

Indenting experiments were conducted with the silicon carbide (0001) surface in contact with a spherical diamond indenter in air. Sliding friction experiments were also conducted with silicon carbide in contact with iron and iron-based binary alloys at room temperature and 800 C. Fracture pits with a spherical particle and spherical wear debris were observed as a result of indenting and sliding. Spherical debris may be produced by a mechanism that involves a spherical-shaped fracture along the circular or spherical stress trajectories under the inelastic deformation zone.

POWER AND THERMAL TECHNOLOGIES FOR AIR AND SPACE-SCIENTIFIC RESEARCH PROGRAM Delivery Order 0018: Single Ion Conducting Solid-State Lithium Electrochemical Technologies (Task 4)

DTIC Science & Technology

2010-08-01

a mathematical equation relates the cathode reaction reversible electric potential to the lithium content of the cathode electrode. Based on the...Transport of Lithium in the Cell Cathode Active Material The Nernst -Einstein relation linking the lithium-ion mass diffusivity and its ionic...transient, isothermal and isobaric conditions. The differential model equation describing the lithium diffusion and accumulation in a spherical, active

Laser Boron Fusion Reactor With Picosecond Petawatt Block Ignition

NASA Astrophysics Data System (ADS)

Hora, Heinrich; Eliezer, Shalom; Wang, Jiaxiang; Korn, Georg; Nissim, Noaz; Xu, Yan-Xia; Lalousis, Paraskevas; Kirchhoff, Gotz J.; Miley, George H.

2018-05-01

For developing a laser boron fusion reactor driven by picosecond laser pulses of more than 30 petawatts power, advances are reported about computations for the plasma block generation by the dielectric explosion of the interaction. Further results are about the direct drive ignition mechanism by a single laser pulse without the problems of spherical irradiation. For the sufficiently large stopping lengths of the generated alpha particles in the plasma results from other projects can be used.

Hydrophilic-impermeable modified polyethylene terephthalate for selective endothelialization

NASA Astrophysics Data System (ADS)

Chetouane, D.; Fafet, J. F.; Barbet, R.; Dieval, F.

2017-10-01

The aim of this study was to create a modified polyethylene terephthalate (PET) responding to vascular implants’ requirements, mainly with a surface promoting selective endothelialization. The surface alteration was carried out by hydrophilic functionalization in an alkaline solution with the presence of specific surfactant (TA). The carboxylic groups resulting from this reaction were quantified by colorimetric titration using bleu toluidine O dye (TBO). A single-sided coating process was then optimized to cover the PET surface by micro spherical structures’ polymeric layer. This coating provided to the PET surface high impermeability to the water under a pressure of 120 mmHg and enhanced its hydrophilic property. This spherical topography reduced the adhesion of Mesenchymal Stem Cells (MSC) by 37% and inhibited their proliferation after 3 days by 50%. The hydrophilic functionalized PET (PET-TA) surface decreased the MSC adhesion by 50% and promoted HUVEC attachment with a number twice more important than the number of HUVEC adhered onto non treated-PET.

Meteoroid rotation and fireball flickering: a case study of the Innisfree fireball

NASA Astrophysics Data System (ADS)

Beech, Martin

2001-09-01

Some 5 per cent of bright meteors show rapid, quasi-periodic brightness variations. It is argued that this effect, observationally known as flickering, is a manifestation of the rotational modulation of surface mass loss through ablation of a non-spherical meteoroid. We develop a set of time-dependent, single-body ablation equations that include the effect of cross-section area modulation. We present a discussion of the effects that the rotation of a non-spherical meteoroid has on the resultant meteor light curve, and we look in depth at the data related to the fireball associated with the fall of the Innisfree meteorite. We find that the parent object to the Innisfree meteorite was spinning at a rotation frequency of 2.5Hz when it encountered the Earth's upper atmosphere. We also find that the Innisfree parent body had an initial mass of about 20kg and that the ratio of its semiminor and semimajor axes was about 0.5.

An analytic-geometric model of the effect of spherically distributed injection errors for Galileo and Ulysses spacecraft - The multi-stage problem

NASA Technical Reports Server (NTRS)

Longuski, James M.; Mcronald, Angus D.

1988-01-01

In previous work the problem of injecting the Galileo and Ulysses spacecraft from low earth orbit into their respective interplanetary trajectories has been discussed for the single stage (Centaur) vehicle. The central issue, in the event of spherically distributed injection errors, is what happens to the vehicle? The difficulties addressed in this paper involve the multi-stage problem since both Galileo and Ulysses will be utilizing the two-stage IUS system. Ulysses will also include a third stage: the PAM-S. The solution is expressed in terms of probabilities for total percentage of escape, orbit decay and reentry trajectories. Analytic solutions are found for Hill's Equations of Relative Motion (more recently called Clohessy-Wiltshire Equations) for multi-stage injections. These solutions are interpreted geometrically on the injection sphere. The analytic-geometric models compare well with numerical solutions, provide insight into the behavior of trajectories mapped on the injection sphere and simplify the numerical two-dimensional search for trajectory families.

Numerical computation of spherical harmonics of arbitrary degree and order by extending exponent of floating point numbers

NASA Astrophysics Data System (ADS)

Fukushima, Toshio

2012-04-01

By extending the exponent of floating point numbers with an additional integer as the power index of a large radix, we compute fully normalized associated Legendre functions (ALF) by recursion without underflow problem. The new method enables us to evaluate ALFs of extremely high degree as 232 = 4,294,967,296, which corresponds to around 1 cm resolution on the Earth's surface. By limiting the application of exponent extension to a few working variables in the recursion, choosing a suitable large power of 2 as the radix, and embedding the contents of the basic arithmetic procedure of floating point numbers with the exponent extension directly in the program computing the recurrence formulas, we achieve the evaluation of ALFs in the double-precision environment at the cost of around 10% increase in computational time per single ALF. This formulation realizes meaningful execution of the spherical harmonic synthesis and/or analysis of arbitrary degree and order.

Space charge effects and aberrations on electron pulse compression in a spherical electrostatic capacitor.

PubMed

Yu, Lei; Li, Haibo; Wan, Weishi; Wei, Zheng; Grzelakowski, Krzysztof P; Tromp, Rudolf M; Tang, Wen-Xin

2017-12-01

The effects of space charge, aberrations and relativity on temporal compression are investigated for a compact spherical electrostatic capacitor (α-SDA). By employing the three-dimensional (3D) field simulation and the 3D space charge model based on numerical General Particle Tracer and SIMION, we map the compression efficiency for a wide range of initial beam size and single-pulse electron number and determine the optimum conditions of electron pulses for the most effective compression. The results demonstrate that both space charge effects and aberrations prevent the compression of electron pulses into the sub-ps region if the electron number and the beam size are not properly optimized. Our results suggest that α-SDA is an effective compression approach for electron pulses under the optimum conditions. It may serve as a potential key component in designing future time-resolved electron sources for electron diffraction and spectroscopy experiments. Copyright © 2017 Elsevier B.V. All rights reserved.

Far-Field Lorenz-Mie Scattering in an Absorbing Host Medium: Theoretical Formalism and FORTRAN Program

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Yang, Ping

2018-01-01

In this paper we make practical use of the recently developed first-principles approach to electromagnetic scattering by particles immersed in an unbounded absorbing host medium. Specifically, we introduce an actual computational tool for the calculation of pertinent far-field optical observables in the context of the classical Lorenzâ€"Mie theory. The paper summarizes the relevant theoretical formalism, explains various aspects of the corresponding numerical algorithm, specifies the input and output parameters of a FORTRAN program available at https://www.giss.nasa.gov/staff/mmishchenko/Lorenz-Mie.html, and tabulates benchmark results useful for testing purposes. This public-domain FORTRAN program enables one to solve the following two important problems: (i) simulate theoretically the reading of a remote well-collimated radiometer measuring electromagnetic scattering by an individual spherical particle or a small random group of spherical particles; and (ii) compute the single-scattering parameters that enter the vector radiative transfer equation derived directly from the Maxwell equations.

Histochemistry and ultrastructure of urocytes in the pupae of the stingless bee Melipona quadrifasciata (Hymenoptera: Meliponini).

PubMed

Furtado, Waléria C A; Azevedo, Dihego O; Martins, Gustavo F; Zanuncio, José C; Serrão, José Eduardo

2013-12-01

The main cell types of the adult bee fat body are trophocytes and oenocytes; however, in pupae of some newly emerged bees, trophocytes are modified into cells called urocytes, which possibly function as a substitute for Malpighian tubules during metamorphosis when larval tubules are not functional and/or storage of urate salts is required. This study evaluated the morphology of urocytes in the stingless bee Melipona quadrifasciata and the possibility of maintaining these cells in primary culture. The urocytes M. quadrifasciata are white spherical cells with an irregular surface as observed by stereomicroscopy. They may be found individually or in groups associated with tracheae. Urocytes have a single, small, and spherical nucleus and cytoplasm rich in neutral polysaccharides, lipid droplets, protein, and granules containing calcium and urate salts. Our findings suggest that urocytes play a role in storage of neutral polysaccharides and calcium in M. quadrifasciata pupae and that these cells can be cultured for 72 h.

Geopotential Field Anomaly Continuation with Multi-Altitude Observations

NASA Technical Reports Server (NTRS)

Kim, Jeong Woo; Kim, Hyung Rae; von Frese, Ralph; Taylor, Patrick; Rangelova, Elena

2012-01-01

Conventional gravity and magnetic anomaly continuation invokes the standard Poisson boundary condition of a zero anomaly at an infinite vertical distance from the observation surface. This simple continuation is limited, however, where multiple altitude slices of the anomaly field have been observed. Increasingly, areas are becoming available constrained by multiple boundary conditions from surface, airborne, and satellite surveys. This paper describes the implementation of continuation with multi-altitude boundary conditions in Cartesian and spherical coordinates and investigates the advantages and limitations of these applications. Continuations by EPS (Equivalent Point Source) inversion and the FT (Fourier Transform), as well as by SCHA (Spherical Cap Harmonic Analysis) are considered. These methods were selected because they are especially well suited for analyzing multi-altitude data over finite patches of the earth such as covered by the ADMAP database. In general, continuations constrained by multi-altitude data surfaces are invariably superior to those constrained by a single altitude data surface due to anomaly measurement errors and the non-uniqueness of continuation.

Geopotential Field Anomaly Continuation with Multi-Altitude Observations

NASA Technical Reports Server (NTRS)

Kim, Jeong Woo; Kim, Hyung Rae; vonFrese, Ralph; Taylor, Patrick; Rangelova, Elena

2011-01-01

Conventional gravity and magnetic anomaly continuation invokes the standard Poisson boundary condition of a zero anomaly at an infinite vertical distance from the observation surface. This simple continuation is limited, however, where multiple altitude slices of the anomaly field have been observed. Increasingly, areas are becoming available constrained by multiple boundary conditions from surface, airborne, and satellite surveys. This paper describes the implementation of continuation with multi-altitude boundary conditions in Cartesian and spherical coordinates and investigates the advantages and limitations of these applications. Continuations by EPS (Equivalent Point Source) inversion and the FT (Fourier Transform), as well as by SCHA (Spherical Cap Harmonic Analysis) are considered. These methods were selected because they are especially well suited for analyzing multi-altitude data over finite patches of the earth such as covered by the ADMAP database. In general, continuations constrained by multi-altitude data surfaces are invariably superior to those constrained by a single altitude data surface due to anomaly measurement errors and the non-uniqueness of continuation.

Analysis of the long and short-period terms due the nonsphericity of the central body: applications for Mercury

NASA Astrophysics Data System (ADS)

Carvalho, J. P. S.

2017-10-01

In this work, we present an approach taking into account the single-averaged equations and unaveraged equations to investigate the dynamics of artificial satellites on the effect due to the non-spherical shape of the planet Mercury. An analysis considering the long-period terms and another taking into account the short-period terms is presented. The numerical integrations of the equations developed are performed using the Maple software. We consider the numerical values of the most updated spherical harmonic coefficients in the literature. Emphasis is given to analyze the effect of the C22 term in the dynamics of the spacecraft. We show that the two techniques are in agreement (average or not average). We found orbits that librates around an equilibrium point with small variation of the orbital elements, in particular the eccentricity and argument of the pericenter. We also note that the C22 term contributes to reduce the growth of the orbital eccentricity.

Type II shell evolution in A = 70 isobars from the N ≥ 40 island of inversion

NASA Astrophysics Data System (ADS)

Morales, A. I.; Benzoni, G.; Watanabe, H.; Tsunoda, Y.; Otsuka, T.; Nishimura, S.; Browne, F.; Daido, R.; Doornenbal, P.; Fang, Y.; Lorusso, G.; Patel, Z.; Rice, S.; Sinclair, L.; Söderström, P.-A.; Sumikama, T.; Wu, J.; Xu, Z. Y.; Yagi, A.; Yokoyama, R.; Baba, H.; Avigo, R.; Bello Garrote, F. L.; Blasi, N.; Bracco, A.; Camera, F.; Ceruti, S.; Crespi, F. C. L.; de Angelis, G.; Delattre, M.-C.; Dombradi, Zs.; Gottardo, A.; Isobe, T.; Kojouharov, I.; Kurz, N.; Kuti, I.; Matsui, K.; Melon, B.; Mengoni, D.; Miyazaki, T.; Modamio-Hoybjor, V.; Momiyama, S.; Napoli, D. R.; Niikura, M.; Orlandi, R.; Sakurai, H.; Sahin, E.; Sohler, D.; Schaffner, H.; Taniuchi, R.; Taprogge, J.; Vajta, Zs.; Valiente-Dobón, J. J.; Wieland, O.; Yalcinkaya, M.

2017-02-01

The level structures of 70Co and 70Ni, populated from the β decay of 70Fe, have been investigated using β-delayed γ-ray spectroscopy following in-flight fission of a 238U beam. The experimental results are compared to Monte-Carlo Shell-Model calculations including the pf +g9/2 +d5/2 orbitals. The strong population of a (1+) state at 274 keV in 70Co is at variance with the expected excitation energy of ∼1 MeV from near spherical single-particle estimates. This observation indicates a dominance of prolate-deformed intruder configurations in the low-lying levels, which coexist with the normal near spherical states. It is shown that the β decay of the neutron-rich A = 70 isobars from the new island of inversion to the Z = 28 closed-shell regime progresses in accordance with a newly reported type of shell evolution, the so-called Type II, which involves many particle-hole excitations across energy gaps.

High-speed DNA-based rolling motors powered by RNase H

PubMed Central

Yehl, Kevin; Mugler, Andrew; Vivek, Skanda; Liu, Yang; Zhang, Yun; Fan, Mengzhen; Weeks, Eric R.

2016-01-01

DNA-based machines that walk by converting chemical energy into controlled motion could be of use in applications such as next generation sensors, drug delivery platforms, and biological computing. Despite their exquisite programmability, DNA-based walkers are, however, challenging to work with due to their low fidelity and slow rates (~1 nm/min). Here, we report DNA-based machines that roll rather than walk, and consequently have a maximum speed and processivity that is three-orders of magnitude greater than conventional DNA motors. The motors are made from DNA-coated spherical particles that hybridise to a surface modified with complementary RNA; motion is achieved through the addition of RNase H, which selectively hydrolyses hybridised RNA. Spherical motors move in a self-avoiding manner, whereas anisotropic particles, such as dimerised particles or rod-shaped particles travel linearly without a track or external force. Finally, we demonstrate detection of single nucleotide polymorphism by measuring particle displacement using a smartphone camera. PMID:26619152

Far-field Lorenz-Mie scattering in an absorbing host medium: Theoretical formalism and FORTRAN program

NASA Astrophysics Data System (ADS)

Mishchenko, Michael I.; Yang, Ping

2018-01-01

In this paper we make practical use of the recently developed first-principles approach to electromagnetic scattering by particles immersed in an unbounded absorbing host medium. Specifically, we introduce an actual computational tool for the calculation of pertinent far-field optical observables in the context of the classical Lorenz-Mie theory. The paper summarizes the relevant theoretical formalism, explains various aspects of the corresponding numerical algorithm, specifies the input and output parameters of a FORTRAN program available at https://www.giss.nasa.gov/staff/mmishchenko/Lorenz-Mie.html, and tabulates benchmark results useful for testing purposes. This public-domain FORTRAN program enables one to solve the following two important problems: (i) simulate theoretically the reading of a remote well-collimated radiometer measuring electromagnetic scattering by an individual spherical particle or a small random group of spherical particles; and (ii) compute the single-scattering parameters that enter the vector radiative transfer equation derived directly from the Maxwell equations.

A waveform diversity method for optimizing 3-d power depositions generated by ultrasound phased arrays.

PubMed

Zeng, Xiaozheng Jenny; Li, Jian; McGough, Robert J

2010-01-01

A waveform-diversity-based approach for 3-D tumor heating is compared to spot scanning for hyperthermia applications. The waveform diversity method determines the excitation signals applied to the phased array elements and produces a beam pattern that closely matches the desired power distribution. The optimization algorithm solves the covariance matrix of the excitation signals through semidefinite programming subject to a series of quadratic cost functions and constraints on the control points. A numerical example simulates a 1444-element spherical-section phased array that delivers heat to a 3-cm-diameter spherical tumor located 12 cm from the array aperture, and the results show that waveform diversity combined with mode scanning increases the heated volume within the tumor while simultaneously decreasing normal tissue heating. Whereas standard single focus and multiple focus methods are often associated with unwanted intervening tissue heating, the waveform diversity method combined with mode scanning shifts energy away from intervening tissues where hotspots otherwise accumulate to improve temperature localization in deep-seated tumors.

Investigation on the effects of temperature dependency of material parameters on a thermoelastic loading problem

NASA Astrophysics Data System (ADS)

Kumar, Anil; Mukhopadhyay, Santwana

2017-08-01

The present work is concerned with the investigation of thermoelastic interactions inside a spherical shell with temperature-dependent material parameters. We employ the heat conduction model with a single delay term. The problem is studied by considering three different kinds of time-dependent temperature and stress distributions applied at the inner and outer surfaces of the shell. The problem is formulated by considering that the thermal properties vary as linear function of temperature that yield nonlinear governing equations. The problem is solved by applying Kirchhoff transformation along with integral transform technique. The numerical results of the field variables are shown in the different graphs to study the influence of temperature-dependent thermal parameters in various cases. It has been shown that the temperature-dependent effect is more prominent in case of stress distribution as compared to other fields and also the effect is significant in case of thermal shock applied at the two boundary surfaces of the spherical shell.

A green chemical approach for synthesis of shape anisotropic gold nanoparticles

NASA Astrophysics Data System (ADS)

Kalyan Kamal, S. S.; Vimala, J.; Sahoo, P. K.; Ghosal, P.; Ram, S.; Durai, L.

2014-06-01

A complete green chemical reaction between aurochloric acid and tea polyphenols resulted in the reduction of Au3+ → Au0. The reaction was carried out in a Teflon-coated bomb digestion vessel at 200 °C. It was observed that with increasing the reaction time from 1 to 5 h, the shape of the nanoparticles changed from spherical- to rod-like structures. The reaction was followed with the help of UV-vis spectrometer, which showed a single absorption peak at 548 nm for 1-h reaction product and two peaks for a 5-h reaction product at 533 and 745 nm corresponding to the transverse and longitudinal surface plasmon resonance bands. Microstructures obtained from transmission electron microscope revealed that the samples obtained after 1-h reaction are predominantly spherical in shape with an average size of 15 nm. Whereas samples obtained after 5 h of reaction exhibited rod-like structures with an average size of 45 nm.

Spherical beamforming for spherical array with impedance surface

NASA Astrophysics Data System (ADS)

Tontiwattanakul, Khemapat

2018-01-01

Spherical microphone array beamforming has been a popular research topic for recent years. Due to their isotropic beam in three dimensional spaces as well as a certain frequency range, the arrays are widely used in many applications such as sound field recording, acoustic beamforming, and noise source localisation. The body of a spherical array is usually considered perfectly rigid. A sound field captured by the sensors on spherical array can be decomposed into a series of spherical harmonics. In noise source localisation, the amplitude density of sound sources is estimated and illustrated by mean of colour maps. In this work, a rigid spherical array covered by fibrous materials is studied via numerical simulation and the performance of the spherical beamforming is discussed.

Apparatus for irradiating a continuously flowing stream of fluid. [For neutron activation analysis

DOEpatents

Speir, L.G.; Adams, E.L.

1982-05-13

An apparatus for irradiating a continuously flowing stream of fluid is disclosed. The apparatus consists of a housing having a spherical cavity and a spherical moderator containing a radiation source positioned within the spherical cavity. The spherical moderator is of lesser diameter than the spherical cavity so as to define a spherical annular volume around the moderator. The housing includes fluid intake and output conduits which open onto the spherical cavity at diametrically opposite positions. Fluid flows through the cavity around the spherical moderator and is uniformly irradiated due to the 4..pi.. radiation geometry. The irradiation source, for example a /sup 252/Cf neutron source, is removable from the spherical moderator through a radial bore which extends outwardly to an opening on the outside of the housing. The radiation source may be routinely removed without interrupting the flow of fluid or breaching the containment of the fluid.

Apparatus for irradiating a continuously flowing stream of fluid

DOEpatents

Speir, Leslie G.; Adams, Edwin L.

1984-01-01

An apparatus for irradiating a continuously flowing stream of fluid is diosed. The apparatus consists of a housing having a spherical cavity and a spherical moderator containing a radiation source positioned within the spherical cavity. The spherical moderator is of lesser diameter than the spherical cavity so as to define a spherical annular volume around the moderator. The housing includes fluid intake and output conduits which open onto the spherical cavity at diametrically opposite positions. Fluid flows through the cavity around the spherical moderator and is uniformly irradiated due to the 4.pi. radiation geometry. The irradiation source, for example a .sup.252 CF neutron source, is removable from the spherical moderator through a radial bore which extends outwardly to an opening on the outside of the housing. The radiation source may be routinely removed without interrupting the flow of fluid or breaching the containment of the fluid.

Preparation and Optical Properties of Spherical Inverse Opals by Liquid Phase Deposition Using Spherical Colloidal Crystals

NASA Astrophysics Data System (ADS)

Aoi, Y.; Tominaga, T.

2013-03-01

Titanium dioxide (TiO2) inverse opals in spherical shape were prepared by liquid phase deposition (LPD) using spherical colloidal crystals as templates. Spherical colloidal crystals were produced by ink-jet drying technique. Aqueous emulsion droplets that contain polystyrene latex particles were ejected into air and dried. Closely packed colloidal crystals with spherical shape were obtained. The obtained spherical colloidal crystals were used as templates for the LPD. The templates were dispersed in the deposition solution of the LPD, i.e. a mixed solution of ammonium hexafluorotitanate and boric acid and reacted for 4 h at 30 °C. After the LPD process, the interstitial spaces of the spherical colloidal crystals were completely filled with titanium oxide. Subsequent heat treatment resulted in removal of templates and spherical titanium dioxide inverse opals. The spherical shape of the template was retained. SEM observations indicated that the periodic ordered voids were surrounded by titanium dioxide. The optical reflectance spectra indicated that the optical properties of the spherical titanium dioxide inverse opals were due to Bragg diffractions from the ordered structure. Filling in the voids of the inverse opals with different solvents caused remarkable changes in the reflectance peak.

Single Droplet Combustion of Decane in Microgravity: Experiments and Numerical Modeling

NASA Technical Reports Server (NTRS)

Dietrich, D. L.; Struk, P. M.; Ikegam, M.; Xu, G.

2004-01-01

This paper presents experimental data on single droplet combustion of decane in microgravity and compares the results to a numerical model. The primary independent experiment variables are the ambient pressure and oxygen mole fraction, pressure, droplet size (over a relatively small range) and ignition energy. The droplet history (D(sup 2) history) is non-linear with the burning rate constant increasing throughout the test. The average burning rate constant, consistent with classical theory, increased with increasing ambient oxygen mole fraction and was nearly independent of pressure, initial droplet size and ignition energy. The flame typically increased in size initially, and then decreased in size, in response to the shrinking droplet. The flame standoff increased linearly for the majority of the droplet lifetime. The flame surrounding the droplet extinguished at a finite droplet size at lower ambient pressures and an oxygen mole fraction of 0.15. The extinction droplet size increased with decreasing pressure. The model is transient and assumes spherical symmetry, constant thermo-physical properties (specific heat, thermal conductivity and species Lewis number) and single step chemistry. The model includes gas-phase radiative loss and a spherically symmetric, transient liquid phase. The model accurately predicts the droplet and flame histories of the experiments. Good agreement requires that the ignition in the experiment be reasonably approximated in the model and that the model accurately predict the pre-ignition vaporization of the droplet. The model does not accurately predict the dependence of extinction droplet diameter on pressure, a result of the simplified chemistry in the model. The transient flame behavior suggests the potential importance of fuel vapor accumulation. The model results, however, show that the fractional mass consumption rate of fuel in the flame relative to fuel vaporized is close to 1.0 for all but the lowest ambient oxygen mole fractions.

Novel Payload Architectures for LISA

NASA Astrophysics Data System (ADS)

Johann, Ulrich A.; Gath, Peter F.; Holota, Wolfgang; Schulte, Hans Reiner; Weise, Dennis

2006-11-01

As part of the current LISA Mission Formulation Study, and based on prior internal investigations, Astrium Germany has defined and preliminary assessed novel payload architectures, potentially reducing overall complexity and improving budgets and costs. A promising concept is characterized by a single active inertial sensor attached to a single optical bench and serving both adjacent interferometer arms via two rigidly connected off-axis telescopes. The in-plane triangular constellation ``breathing angle'' compensation is accomplished by common telescope in-field of view pointing actuation of the transmit/received beams line of sight. A dedicated actuation mechanism located on the optical bench is required in addition to the on bench actuators for differential pointing of the transmit and receive direction perpendicular to the constellation plane. Both actuators operate in a sinusoidal yearly period. A technical challenge is the actuation mechanism pointing jitter and the monitoring and calibration of the laser phase walk which occurs while changing the optical path inside the optical assembly during re-pointing. Calibration or monitoring of instrument internal phase effects e.g. by a laser metrology truss derived from the existing interferometry is required. The architecture exploits in full the two-step interferometry (strap down) concept, separating functionally inter spacecraft and intra-spacecraft interferometry (reference mass laser metrology degrees of freedom sensing). The single test mass is maintained as cubic, but in free-fall in the lateral degrees of freedom within the constellation plane. Also the option of a completely free spherical test mass with full laser interferometer readout has been conceptually investigated. The spherical test mass would rotate slowly, and would be allowed to tumble. Imperfections in roundness and density would be calibrated from differential wave front sensing in a tetrahedral arrangement, supported by added attitude information via a grid of tick marks etched onto the surface and monitored by the laser readout.

The efficiency of aspheric intraocular lens according to biometric measurements.

PubMed

Whang, Woong-Joo; Piao, Junjie; Yoo, Young-Sik; Joo, Choun-Ki; Yoon, Geunyoung

2017-01-01

To analyze internal spherical aberration in pseudophakic eyes that underwent aspheric intraocular lens (IOL) implantation, and to investigate the relationships between biometric data and the effectiveness of aspheric IOL implantation. This retrospective study included 40 eyes of 40 patients who underwent implantation of an IOL having a negative spherical aberration of -0.20 μm (CT ASPHINA 509M; Carl Zeiss Meditec Inc., Germany). The IOLMaster (version 5.0; Carl Zeiss AG, Germany) was used for preoperative biometric measurements (axial length, anterior chamber depth, central corneal power) and the measurement of postoperative anterior chamber depth. The spherical aberrations were measured preoperatively and 3 months postoperatively using the iTrace (Tracey Technologies, Houston, TX, USA) at a pupil diameter of 5.0 mm. We investigated the relationships between preoperative biometric data and postoperative internal spherical aberration, and compared biometric measurements between 2 subgroups stratified according to internal spherical aberration (spherical aberration ≤ -0.06 μm vs. spherical aberration > -0.06 μm). The mean postoperative internal spherical aberration was -0.087 ± 0.063 μm. Preoperative axial length and residual total spherical aberration showed statistically significant correlations with internal spherical aberration (p = 0.041, 0.002). Preoperative axial length, postoperative anterior chamber depth, IOL power, and residual spherical aberration showed significant differences between the 2 subgroups stratified according to internal spherical aberration (p = 0.020, 0.029, 0.048, 0.041 respectively). The corrective effect of an aspheric IOL is influenced by preoperative axial length and postoperative anterior chamber depth. Not only the amount of negative spherical aberration on the IOL surface but also the preoperative axial length should be considered to optimize spherical aberration after aspheric IOL implantation.

Design of an external-fueled thermionic diode for in-pile testing.

NASA Technical Reports Server (NTRS)

Ernst, D. M.; Peelgren, M. L.

1971-01-01

Description of an external-fueled thermionic diode suitable for in-pile testing in a research reactor. The active electrode area is 94 sq cm. The 10-in. long, 1.5-in.-OD emitter body is tungsten 2% thoria. The fuel is contained in six 0.4-in.-diam holes equally spaced about the 0.5-in. central emitter hole. The collector is niobium-1% zirconium. The expected diode performance is 6 W/sq cm at 2000 K. In addition to following the constraints imposed by the in-pile testing and the electrically heated performance mapping prior to insertion in-pile, the diode will have end configurations prototypical of those anticipated for a flow-through, NaK-cooled, external-fuel thermionic reactor.

Growth of fullerene-like carbon nitride thin solid films consisting of cross-linked nano-onions

NASA Astrophysics Data System (ADS)

Czigány, Zs.; Brunell, I. F.; Neidhardt, J.; Hultman, L.; Suenaga, K.

2001-10-01

Fullerene-like CNx (x≈0.12) thin solid films were deposited by reactive magnetron sputtering of graphite in a nitrogen and argon discharge on cleaved NaCl and Si(001) substrates at 450 °C. As-deposited films consist of 5 nm diam CNx nano-onions with shell sizes corresponding to Goldberg polyhedra determined by high-resolution transmission electron microscopy. Electron energy loss spectroscopy revealed that N incorporation is higher in the core of the onions than at the perimeter. N incorporation promotes pentagon formation and provides reactive sites for interlinks between shells of the onions. A model is proposed for the formation of CNx nano-onions by continuous surface nucleation and growth of hemispherical shells.

Laser ablation of dental calculus at 400 nm using a Ti:sapphire laser

NASA Astrophysics Data System (ADS)

Schoenly, Joshua E.; Seka, Wolf; Rechmann, Peter

2009-02-01

A Nd:YAG laser-pumped, frequency-doubled Ti:sapphire laser is used for selective ablation of calculus. The laser provides <=25 mJ at 400 nm (60-ns pulse width, 10-Hz repetition rate). The laser is coupled into an optical multimode fiber coiled around a 4-in.-diam drum to generate a top-hat output intensity profile. With coaxial water cooling, this is ideal for efficient, selective calculus removal. This is in stark contrast with tightly focused Gaussian beams that are energetically inefficient and lead to irreproducible results. Calculus is well ablated at high fluences >=2J/cm2 stalling occurs below this fluence because of photobleaching. Healthy hard tissue is not removed at fluences <=3 J/cm2.

Laser femtoseconde, filamentation, nuage et orage

NASA Astrophysics Data System (ADS)

Courvoisier, F.; Boutou, V.; Kasparian, J.; Salmon, E.; Méjean, G.; Yu, J.; Wolf, J.-P.

2005-06-01

Les applications telles que le contrôle de foudre grâce aux filaments autoguidés générés par un laser femtoseconde nécessitent de propager un tel filament à travers des aérosols de gouttes d'eau. Nous montrons qu'un filament survit à son interaction avec une goutte de diamètre comparable au sien (95 μ m), ainsi qu'à des nuages d'épaisseur optique 3,2, soit 5% de transmission. Cette transmission est permise par la présence d'un “bain de photons” autour du filament. Ce bain forme un réservoir contenant une part importante de l'énergie du faisceau, en équilibre avec le filament, et favorisant son alimentation.

Aerodynamic interactions between a 1/6 scale helicopter rotor and a body of revolution

NASA Technical Reports Server (NTRS)

Betzina, M. D.; Shinoda, P.

1982-01-01

A wind-tunnel investigation was conducted in which independent, steady state aerodynamic forces and moments were measured on a 2.24-m-diam, two bladed helicopter rotor and a body of revolution. The objective was to determine the interaction of the body on the rotor performance and the effect of the rotor on the body aerodynamics for variations in velocity, thrust, tip-path-plane angle of attack, body angle of attack, rotor/body position, and body nose geometry. Results show that a body of revolution near the rotor can produce significant favorable or unfavorable effects on rotor performance, depending on the operating condition. Body longitudinal aerodynamic characteristics are significantly modified by the presence of an operating rotor and hub.

Working group session report: Neutron beam line shielding.

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

Russell, G. J.; Ikedo, Y.

2001-01-01

We have examined the differences between a 2-D model and a 3-D model for designing the beam-line shield for the HIPPO instrument at the Lujan Center at the Los Alamos National Laboratory. We have calculated the total (neutron and gamma ray) dose equivalent rate coming out of the personal access ports from the HIPPO instrument experiment cave. In order to answer this question, we have investigated two possible worst-case scenarios: (a) failure of the T{sub 0}-chopper and no sample at the sample position; and (b) failure of the T{sub 0}-chopper with a thick sample (a piece of Inconel-718, 10 cmmore » diam by 30 cm long) at the sample position.« less

Fused silicon-rich coatings for superalloys

NASA Technical Reports Server (NTRS)

Smialek, J. L.

1974-01-01

Various compositions of nickel-silicon and aluminum-silicon slurries were sprayed on IN 100 specimens and fusion-sintered to form fully dense coatings. Cyclic furnace oxidation tests in 1 atm air at 1100 C showed all the coatings to be protective for at least 600 hours, and one slurry, Al-60Si, was protective for 1000 hours. This coating also protected NASA TAZ 8A and NASA-TRW VIA for 1000 hours in the same furnace test. Alloys B 1900, TD-NiCr, and Mar-M200 were protected for lesser times, while NX 188 and NASA WAZ 20 were scarcely protected at all. Limited stress-rupture testing on 0.64-cm-diam IN 100 specimens detected no degradation of mechanical properties due to silicon diffusion.

Jet-noise reduction through liquid-base foam injection.

NASA Technical Reports Server (NTRS)

Manson, L.; Burge, H. L.

1971-01-01

An experimental investigation has been made of the sound-absorbing properties of liquid-base foams and of their ability to reduce jet noise. Protein, detergent, and polymer foaming agents were used in water solutions. A method of foam generation was developed to permit systematic variation of the foam density. The investigation included measurements of sound-absorption coefficents for both plane normal incidence waves and diffuse sound fields. The intrinsic acoustic properties of foam, e.g., the characteristic impedance and the propagation constant, were also determined. The sound emitted by a 1-in.-diam cold nitrogen jet was measured for subsonic (300 m/sec) and supersonic (422 m/sec) jets, with and without foam injection. Noise reductions up to 10 PNdB were measured.

Heat Transfer and Cooling in Gas Turbines (Le Transfert Thermique et le Refroidissement dans les Turbines a Gaz)

DTIC Science & Technology

1993-02-01

the almost monotonic coolant to freestream temperature ratio ( Toc /To0 =0.62). increase of h/ho at low values of Toe/To1 compared to The non...Tol 0.769 0.4 es•e. 10 diem. 0.4 TocTol 0.889 &"a&’ 50 diam. 0.4 A Toc /TOI 0.817 A,’,’ Trailing edge 0Emisson S4 0.0 0.2 0.𔃾 o.8 06 1.0 0.25 0.60 01.5...for (M--0.98, Re2=5.5xlW0, Toc /To-ff0.4). The total impingement realized through a row of circular holes temperature boundary condition is the hot gas

Subjective depth of field in presence of 4th-order and 6th-order Zernike spherical aberration using adaptive optics technology.

PubMed

Benard, Yohann; Lopez-Gil, Norberto; Legras, Richard

2010-12-01

To study the impact on the subjective depth of field of 4th-order spherical aberration and its combination with 6th-order spherical aberration and analyze the accuracy of image-quality metrics in predicting the impact. Laboratoire Aimé Cotton, Centre National de la Recherche Scientifique, Université Paris-Sud, Orsay, France. Case series. Subjective depth of field was defined as the range of defocus at which the target (3 high-contrast letters at 20/50) was perceived acceptable. Depth of field was measured using 0.18 diopter (D) steps in young subjects with the addition of the following spherical aberration values: ±0.3 μm and ±0.6 μm 4th-order spherical aberration with 3.0 mm and 6.0 mm pupils and ±0.3 μm 4th-order spherical aberration with ±0.1 μm 6th-order spherical aberration for 6.0 mm pupils. The addition of ±0.3 and ±0.6 μm 4th-order spherical aberration increased depth of field by 30% and 45%, respectively. The combination of 4th-order spherical aberration and 6th-order spherical aberration of opposite signs increased depth of field more than 4th-order spherical aberration alone (ie, 63%), while the combination of 4th-order spherical aberration and 6th-order spherical aberration of the same signs did not (ie, 24%). Whereas the midpoint of the depth of field could be predicted by image-quality metrics, none was found a good predictor of objectionable depth of field. Subjective depth of field increased when 4th-order spherical aberration and 6th-order spherical aberration of opposite signs were added but could not be predicted with image-quality metrics. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Single-polymer dynamics under constraints: scaling theory and computer experiment.

PubMed

Milchev, Andrey

2011-03-16

The relaxation, diffusion and translocation dynamics of single linear polymer chains in confinement is briefly reviewed with emphasis on the comparison between theoretical scaling predictions and observations from experiment or, most frequently, from computer simulations. Besides cylindrical, spherical and slit-like constraints, related problems such as the chain dynamics in a random medium and the translocation dynamics through a nanopore are also considered. Another particular kind of confinement is imposed by polymer adsorption on attractive surfaces or selective interfaces--a short overview of single-chain dynamics is also contained in this survey. While both theory and numerical experiments consider predominantly coarse-grained models of self-avoiding linear chain molecules with typically Rouse dynamics, we also note some recent studies which examine the impact of hydrodynamic interactions on polymer dynamics in confinement. In all of the aforementioned cases we focus mainly on the consequences of imposed geometric restrictions on single-chain dynamics and try to check our degree of understanding by assessing the agreement between theoretical predictions and observations.

Real-Time Plasmonic Monitoring of Single Gold Amalgam Nanoalloy Electrochemical Formation and Stripping.

PubMed

Wang, Jun-Gang; Fossey, John S; Li, Meng; Xie, Tao; Long, Yi-Tao

2016-03-01

Direct electrodeposition of mercury onto gold nanorods on an ITO substrate, without reducing agents, is reported. The growth of single gold amalgam nanoalloy particles and subsequent stripping was monitored in real-time monitoring by plasmonic effects and single-nanoparticle dark-field spectroelectrochemistry techniques. Time-dependent scattering spectral information conferred insight into the growth and stripping mechanism of a single nanoalloy particle. Four critical stages were observed: First, rapid deposition of Hg atoms onto Au nanorods; second, slow diffusion of Hg atoms into Au nanorods; third, prompt stripping of Hg atoms from Au nanorods; fourth, moderate diffusion from the inner core of Au nanorods. Under high Hg(2+) concentrations, homogeneous spherical gold amalgam nanoalloys were obtained. These results demonstrate that the morphology and composition of individual gold amalgam nanoalloys can be precisely regulated electrochemically. Moreover, gold amalgam nanoalloys with intriguing optical properties, such as modulated plasmonic lifetimes and quality factor Q, could be obtained. This may offer opportunities to extend applications in photovoltaic energy conversion and chemical sensing.

Dynamic fracture behavior of single and contacting Poly(methyl methacrylate) particles

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

Parab, Niranjan D.; Guo, Zherui; Hudspeth, Matthew C.

Fracture behaviors of single, two, and multiple contacting spherical Poly (methyl methacrylate) (PMMA) particles were recorded using high speed synchrotron X-ray phase contrast imaging. A miniaturized Kolsky bar setup was used to apply dynamic compressive loading on the PMMA particles. In both single and two particle experiments, cracking initiated near the center of the particles and propagated towards the contacts. The crack bifurcated near the contact points for single particle experiments, thus forming conical fragments. The crack bifurcation and subsequent conical fragment formation was observed only at the particle-particle contact for two particle experiments. The particles were observed to fracturemore » in hemispherical fragments normal to the contact plane in the multiparticle experiments. The observed failure mechanisms strongly suggest that the maximum tensile stress near the center of the particle is the critical parameter governing fracture of the particles. Moreover, the compressive stress under the contact areas led to the bifurcation and subsequent conical fragment formation.« less

Dynamic fracture behavior of single and contacting Poly(methyl methacrylate) particles

DOE PAGES

Parab, Niranjan D.; Guo, Zherui; Hudspeth, Matthew C.; ...

2017-09-19

Fracture behaviors of single, two, and multiple contacting spherical Poly (methyl methacrylate) (PMMA) particles were recorded using high speed synchrotron X-ray phase contrast imaging. A miniaturized Kolsky bar setup was used to apply dynamic compressive loading on the PMMA particles. In both single and two particle experiments, cracking initiated near the center of the particles and propagated towards the contacts. The crack bifurcated near the contact points for single particle experiments, thus forming conical fragments. The crack bifurcation and subsequent conical fragment formation was observed only at the particle-particle contact for two particle experiments. The particles were observed to fracturemore » in hemispherical fragments normal to the contact plane in the multiparticle experiments. The observed failure mechanisms strongly suggest that the maximum tensile stress near the center of the particle is the critical parameter governing fracture of the particles. Moreover, the compressive stress under the contact areas led to the bifurcation and subsequent conical fragment formation.« less

A platonic solid templating Archimedean solid: an unprecedented nanometre-sized Ag37 cluster

NASA Astrophysics Data System (ADS)

Li, Xiao-Yu; Su, Hai-Feng; Yu, Kai; Tan, Yuan-Zhi; Wang, Xing-Po; Zhao, Ya-Qin; Sun, Di; Zheng, Lan-Sun

2015-04-01

The spontaneous formation of discrete spherical nanosized molecules is prevalent in nature, but the authentic structural mimicry of such highly symmetric polyhedra from edge sharing of regular polygons has remained elusive. Here we present a novel ball-shaped {(HNEt3)[Ag37S4(SC6H4tBu)24(CF3COO)6(H2O)12]} cluster (1) that is assembled via a one-pot process from polymeric {(HNEt3)2[Ag10(SC6H4tBu)12]}n and CF3COOAg. Single crystal X-ray analysis confirmed that 1 is a Td symmetric spherical molecule with a [Ag36(SC6H4tBu)24] anion shell enwrapping a AgS4 tetrahedron. The shell topology of 1 belongs to one of 13 Archimedean solids, a truncated tetrahedron with four edge-shared hexagons and trigons, which are supported by a AgS4 Platonic solid in the core. Interestingly, the cluster emits green luminescence centered at 515 nm at room temperature. Our investigations have provided a promising synthetic protocol for a high-nuclearity silver cluster based on underlying geometrical principles.The spontaneous formation of discrete spherical nanosized molecules is prevalent in nature, but the authentic structural mimicry of such highly symmetric polyhedra from edge sharing of regular polygons has remained elusive. Here we present a novel ball-shaped {(HNEt3)[Ag37S4(SC6H4tBu)24(CF3COO)6(H2O)12]} cluster (1) that is assembled via a one-pot process from polymeric {(HNEt3)2[Ag10(SC6H4tBu)12]}n and CF3COOAg. Single crystal X-ray analysis confirmed that 1 is a Td symmetric spherical molecule with a [Ag36(SC6H4tBu)24] anion shell enwrapping a AgS4 tetrahedron. The shell topology of 1 belongs to one of 13 Archimedean solids, a truncated tetrahedron with four edge-shared hexagons and trigons, which are supported by a AgS4 Platonic solid in the core. Interestingly, the cluster emits green luminescence centered at 515 nm at room temperature. Our investigations have provided a promising synthetic protocol for a high-nuclearity silver cluster based on underlying geometrical principles. Electronic supplementary information (ESI) available: detailed synthesis procedure, tables, crystal data in CIF files, IR data, TGA results and powder X-ray diffractogram for 1. CCDC 1042228. See DOI: 10.1039/c5nr01222h

Modelling incompressible flows and fluid-structure interaction problems with smoothed particle hydrodynamics: Briefing on the 2017 SPHERIC Beijing International Workshop

NASA Astrophysics Data System (ADS)

Liu, Mou-bin; Huang, Can; Zhang, A.-man

2018-02-01

The 2017 SPHERIC Beijing International Workshop (or SPHERIC Beijing 2017) was held at Peking University, in China, on October 17-20, 2017. This is the first time that the SPHERIC Workshop was held out of Europe. We are delighted to present nine contributions in this Special Column of the Journal of Hydrodynamics, and take this opportunity to announce that the 13th SPHERIC Workshop (or SPHERIC 2018) will be held in Galway, Ireland in 2018 by the National University of Ireland, and the SPHERIC International Workshop in Harbin, China in 2019 by the Harbin Engineering University.

100-watt sonoluminescence generated by 2.5-atmosphere-pressure pulses

NASA Astrophysics Data System (ADS)

Kappus, Brian; Khalid, Shahzad; Putterman, Seth

2011-05-01

A Xenon gas bubble introduced into a vertically suspended steel cylinder is driven to sonoluminescence by impacting the apparatus against a solid steel base. This produces a 150-ns flash of broadband light that exceeds 100-W peak intensity and has a spectral temperature of 10 200 K. This bubble system, which yields light with a single shot, emits very powerful sonoluminescence. A jet is visible following bubble collapse, which demonstrates that spherical symmetry is not necessary to produce sonoluminescence.

100-Watt sonoluminescence generated by 2.5-atmosphere-pressure pulses.

PubMed

Kappus, Brian; Khalid, Shahzad; Putterman, Seth

2011-05-01

A Xenon gas bubble introduced into a vertically suspended steel cylinder is driven to sonoluminescence by impacting the apparatus against a solid steel base. This produces a 150-ns flash of broadband light that exceeds 100-W peak intensity and has a spectral temperature of 10,200 K. This bubble system, which yields light with a single shot, emits very powerful sonoluminescence. A jet is visible following bubble collapse, which demonstrates that spherical symmetry is not necessary to produce sonoluminescence. © 2011 American Physical Society

Histological and molecular biology diagnosis of neurocysticercosis in a patient without history of travel to endemic areas: case report.

PubMed

L'Ollivier, C; González, L M; Gárate, T; Martin, L; Martha, B; Duong, M; Huerre, M; Cuisenier, B; Harrison, L J S; Dalle, F; Bonnin, A

2012-11-01

in endemic areas, neurocysticercosis appears mainly as a single, large, spherical and non-enhancing intracranial cyst. an atypical case of neurocysticercosis (NCC) in a French Caucasian, without history of travel to endemic areas, was confirmed by histology and molecular speciation. Imaging was atypical, showing several hook-bearing scolices visible in the cyst, while the serology employed was non-contributary. NCC should be considered when multiple taeniid scolices are observed within the same cystic lesion.

How To Improve Work In Planetarium?

NASA Astrophysics Data System (ADS)

Pavicic, G.

2009-09-01

Planetariums can provide an immersive environment for scientific education, virtual reality, and entertainment (Shaw 1998). Digital projection into domes, called "full dome projection", can be a technically challenging and expensive exercise, particularly for installation with a modest budget. Here we present an alternative full dome digital projection system, which consists of a single projector and a spherical mirror that scatter the light onto the dome surface. This approach offers many advantages over the fisheye lens alternatives, and results in a similar quality for just a fraction of costs.

Anisotropic solutions by gravitational decoupling

NASA Astrophysics Data System (ADS)

Ovalle, J.; Casadio, R.; da Rocha, R.; Sotomayor, A.

2018-02-01

We investigate the extension of isotropic interior solutions for static self-gravitating systems to include the effects of anisotropic spherically symmetric gravitational sources by means of the gravitational decoupling realised via the minimal geometric deformation approach. In particular, the matching conditions at the surface of the star with the outer Schwarzschild space-time are studied in great detail, and we describe how to generate, from a single physically acceptable isotropic solution, new families of anisotropic solutions whose physical acceptability is also inherited from their isotropic parent.

Correlation of new hypervelocity impact data by threshold penetration relations

NASA Technical Reports Server (NTRS)

Hayduk, R. J.; Gough, P. S.; Alfaro-Bou, E.

1973-01-01

Threshold penetration data are established by impacting spherical projectiles onto 2024 aluminum single-wall targets. Nylon and cadmium projectiles were used at impacting velocities from 3.0 to 6.8 km/s and 7.9 to 8.5 km/s respectively. These data are combined with existing data and compared with three threshold relations to assess their respective validities over a wide range of projectile densities. Two of these relations were validated over the extended range of projectile densities.

Experimental study of the form of "hot" steel particles on the ignition characteristics of liquid fuels

NASA Astrophysics Data System (ADS)

Zakharevich, Arkadiy V.

2015-01-01

The results of an experimental study of laws governing the ignition of liquid propellants (kerosene, diesel fuel and petroleum residue) by the single spherical steel particle heated to high temperatures are presented. Is carried out the comparison of the ignition delay times of the investigated flammable substances by the particles in the sphere and disk forms. It is established that the particle shape does not exert a substantial influence on the ignition process characteristics.

Effects of contact shape on the scaling of biological attachments

NASA Astrophysics Data System (ADS)

Spolenak, Ralph; Gorb, Stanislav; Gao, Huajian; Arzt, Eduard

2005-02-01

Adhesion of biological systems has recently received much research attention: the survival of organisms ranging from single cells and mussels to insects, spiders and geckos relies crucially on their mechanical interaction with their environments. For spiders, lizards and possible other 'dry' adhesive systems, explanations for adhesion are based on van der Waals interaction, and the adhesion of single-contact elements has been described by the classical Johnson-Kendall-Roberts (JKR) model derived for spherical contacts. However, real biological contacts display a variety of shapes and only rarely resemble a hemisphere. Here, we theoretically assess the influence of various contact shapes on the pull-off force for single contacts as well as their scaling potential in contact arrays. It is concluded that other shapes, such as a toroidal contact geometry, should lead to better attachment; such geometries are observed in our microscopic investigations of hair-tip shapes in beetles and flies.

Single microparticle launching method using two-stage light-gas gun for simulating hypervelocity impacts of micrometeoroids and space debris.

PubMed

Kawai, Nobuaki; Tsurui, Kenji; Hasegawa, Sunao; Sato, Eiichi

2010-11-01

A single microparticle launching method is described to simulate the hypervelocity impacts of micrometeoroids and microdebris on space structures at the Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency. A microparticle placed in a sabot with slits is accelerated using a rifled two-stage light-gas gun. The centrifugal force provided by the rifling in the launch tube separates the sabot. The sabot-separation distance and the impact-point deviation are strongly affected by the combination of the sabot diameter and the bore diameter, and by the projectile diameter. Using this method, spherical projectiles of 1.0-0.1 mm diameter were launched at up to 7 km/s.

Friction and wear of metals with a single-crystal abrasive grit of silicon carbide: Effect of shear strength of metal

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.

1978-01-01

Sliding friction experiments were conducted with spherical, single-crystal silicon carbide riders in contact with various metals and with metal riders in contact with silicon carbide flats. Results indicate that: (1) the friction force in the plowing of metal and (2) the groove height (corresponding to the volume of the groove) are related to the shear strength of the metal. That is, they decrease linearly as the shear strength of the bulk metal increases. Grooves are formed in metals primarily from plastic deformation, with occasional metal removal. The relation between the groove width D and the load W can be expressed by W = kD, superscript n which satisfies Meyer's law.

Calculation of Thermodynamic Parameters and Degree of Ionization of Nitrogen and Its Mixtures with Argon in Typical Single-Bubble Sonoluminescence Conditions

NASA Astrophysics Data System (ADS)

Borisenok, V. A.; Medvedev, A. B.

2017-12-01

The results of numerical simulation of the behavior of a system consisting of a spherical bubble filled with nitrogen or its mixtures with argon and surrounding water under external influence typical of experimental study of single-bubble sonoluminescence are presented. Comparison of the results of calculations and experiments shows that gas heated at the bubble compression stage cannot be regarded as the only source of radiation. This circumstance requires the presence of other, basic, sources. In the polarization model, this is the channel of electrical breakdown in a liquid. Possible electrical effects accompanying the liquid-solid phase transformation in water near the moment of the maximum compression of the bubble are assumed.

Hyperspherical von Mises-Fisher mixture (HvMF) modelling of high angular resolution diffusion MRI.

PubMed

Bhalerao, Abhir; Westin, Carl-Fredrik

2007-01-01

A mapping of unit vectors onto a 5D hypersphere is used to model and partition ODFs from HARDI data. This mapping has a number of useful and interesting properties and we make a link to interpretation of the second order spherical harmonic decompositions of HARDI data. The paper presents the working theory and experiments of using a von Mises-Fisher mixture model for directional samples. The MLE of the second moment of the HvMF pdf can also be related to fractional anisotropy. We perform error analysis of the estimation scheme in single and multi-fibre regions and then show how a penalised-likelihood model selection method can be employed to differentiate single and multiple fibre regions.

Single step synthesis of nanostructured boron nitride for boron neutron capture therapy

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

Singh, Bikramjeet; Singh, Paviter; Kumar, Akshay, E-mail: akshaykumar.tiet@gmail.com

2015-05-15

Nanostructured Boron Nitride (BN) has been successfully synthesized by carbo-thermic reduction of Boric Acid (H{sub 3}BO{sub 3}). This method is a relatively low temperature synthesis route and it can be used for large scale production of nanostructured BN. The synthesized nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analyzer (DTA). XRD analysis confirmed the formation of single phase nanostructured Boron Nitride. SEM analysis showed that the particles are spherical in shape. DTA analysis showed that the phase is stable upto 900 °C and the material can be used for high temperature applications asmore » well boron neutron capture therapy (BNCT)« less

Generalized quasitopological gravity

NASA Astrophysics Data System (ADS)

Hennigar, Robie A.; KubizÅák, David; Mann, Robert B.

2017-05-01

We construct the most general, to cubic order in curvature, theory of gravity whose (most general) static spherically symmetric vacuum solutions are fully described by a single field equation. The theory possesses the following remarkable properties: (i) It has a well-defined Einstein gravity limit, (ii) it admits "Schwarzschild-like" solutions characterized by a single metric function, (iii) on maximally symmetric backgrounds it propagates the same degrees of freedom as Einstein's gravity, and (iv) Lovelock and quasitopological gravities, as well as the recently developed Einsteinian cubic gravity [Bueno and Cano Phys. Rev. D 94, 104005 (2016)., 10.1103/PhysRevD.94.104005] in four dimensions, are recovered as special cases. We perform a brief analysis of asymptotically flat black holes in this theory and study their thermodynamics.

Single microparticle launching method using two-stage light-gas gun for simulating hypervelocity impacts of micrometeoroids and space debris

NASA Astrophysics Data System (ADS)

Kawai, Nobuaki; Tsurui, Kenji; Hasegawa, Sunao; Sato, Eiichi

2010-11-01

A single microparticle launching method is described to simulate the hypervelocity impacts of micrometeoroids and microdebris on space structures at the Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency. A microparticle placed in a sabot with slits is accelerated using a rifled two-stage light-gas gun. The centrifugal force provided by the rifling in the launch tube separates the sabot. The sabot-separation distance and the impact-point deviation are strongly affected by the combination of the sabot diameter and the bore diameter, and by the projectile diameter. Using this method, spherical projectiles of 1.0-0.1 mm diameter were launched at up to 7 km/s.

Sampling functions for geophysics

NASA Technical Reports Server (NTRS)

Giacaglia, G. E. O.; Lunquist, C. A.

1972-01-01

A set of spherical sampling functions is defined such that they are related to spherical-harmonic functions in the same way that the sampling functions of information theory are related to sine and cosine functions. An orderly distribution of (N + 1) squared sampling points on a sphere is given, for which the (N + 1) squared spherical sampling functions span the same linear manifold as do the spherical-harmonic functions through degree N. The transformations between the spherical sampling functions and the spherical-harmonic functions are given by recurrence relations. The spherical sampling functions of two arguments are extended to three arguments and to nonspherical reference surfaces. Typical applications of this formalism to geophysical topics are sketched.

Sound Source Localization Using Non-Conformal Surface Sound Field Transformation Based on Spherical Harmonic Wave Decomposition

PubMed Central

Zhang, Lanyue; Ding, Dandan; Yang, Desen; Wang, Jia; Shi, Jie

2017-01-01

Spherical microphone arrays have been paid increasing attention for their ability to locate a sound source with arbitrary incident angle in three-dimensional space. Low-frequency sound sources are usually located by using spherical near-field acoustic holography. The reconstruction surface and holography surface are conformal surfaces in the conventional sound field transformation based on generalized Fourier transform. When the sound source is on the cylindrical surface, it is difficult to locate by using spherical surface conformal transform. The non-conformal sound field transformation by making a transfer matrix based on spherical harmonic wave decomposition is proposed in this paper, which can achieve the transformation of a spherical surface into a cylindrical surface by using spherical array data. The theoretical expressions of the proposed method are deduced, and the performance of the method is simulated. Moreover, the experiment of sound source localization by using a spherical array with randomly and uniformly distributed elements is carried out. Results show that the non-conformal surface sound field transformation from a spherical surface to a cylindrical surface is realized by using the proposed method. The localization deviation is around 0.01 m, and the resolution is around 0.3 m. The application of the spherical array is extended, and the localization ability of the spherical array is improved. PMID:28489065

Laparoscopic microwave thermosphere ablation of malignant liver tumors: an initial clinical evaluation.

PubMed

Berber, Eren

2016-02-01

Microwave ablation (MWA) has been recently recognized as a technology to overcome the limitations of radiofrequency ablation. The aim of the current study was to evaluate the safety and efficacy of a new 2.45-GHz thermosphere MWA system in the treatment of malignant liver tumors. This was a prospective IRB-approved study of 18 patients with malignant liver tumors treated with MWA within a 3-month time period. Tumor sizes and response to MWA were obtained from triphasic liver CT scans done before and after MWA. The ablation zones were assessed for complete tumor response and spherical geometry. There were a total of 18 patients with an average of three tumors measuring 1.4 cm (range 0.2-4). Ablations were performed laparoscopically in all, but three patients who underwent combined liver resection. A single ablation was created in 72% and overlapping ablations in 28% of lesions. Total ablation time per patient was 15.6 ± 1.9 min. There was no morbidity or mortality. At 2-week CT scans, there was 100% tumor destruction, with no residual lesions. Roundness indices A, B and transverse were 1.1, 0.9 and 0.9, respectively, confirming the spherical nature of ablation zones. To the best of our knowledge, this is the first report of a new thermosphere MWA technology in the laparoscopic treatment of malignant liver tumors. The results demonstrate the safety of the technology, with satisfactory spherical ablation zones seen on post-procedural CT scans.

Seismic performance of spherical liquid storage tanks: a case study

NASA Astrophysics Data System (ADS)

Fiore, Alessandra; Demartino, Cristoforo; Greco, Rita; Rago, Carlo; Sulpizio, Concetta; Vanzi, Ivo

2018-02-01

Spherical storage tanks are widely used for various types of liquids, including hazardous contents, thus requiring suitable and careful design for seismic actions. On this topic, a significant case study is described in this paper, dealing with the dynamic analysis of a spherical storage tank containing butane. The analyses are based on a detailed finite element (FE) model; moreover, a simplified single-degree-of-freedom idealization is also set up and used for verification of the FE results. Particular attention is paid to the influence of sloshing effects and of the soil-structure interaction for which no special provisions are contained in technical codes for this reference case. Sloshing effects are investigated according to the current literature state of the art. An efficient methodology based on an "impulsive-convective" decomposition of the container-fluid motion is adopted for the calculation of the seismic force. With regard to the second point, considering that the tank is founded on piles, soil-structure interaction is taken into account by computing the dynamic impedances. Comparison between seismic action effects, obtained with and without consideration of sloshing and soil-structure interaction, shows a rather important influence of these parameters on the final results. Sloshing effects and soil-structure interaction can produce, for the case at hand, beneficial effects. For soil-structure interaction, this depends on the increase of the fundamental period and of the effective damping of the overall system, which leads to reduced design spectral values.

Comparison of subchronic immunotoxicity of four different types of aluminum-based nanoparticles.

PubMed

Park, Eun-Jung; Lee, Sang Jin; Lee, Gwang-Hee; Kim, Dong-Wan; Yoon, Cheolho; Lee, Byoung-Seok; Kim, Younghun; Chang, Jaerak; Lee, Kyuhong

2018-04-01

Nanoparticles (NPs) have recently emerged as an inhalable pollutant, owing to their applications, aluminum-based NPs (Al-NPs) have been prioritized for toxicity testing. In the current study, we compared the pulmonary biopersistence and subsequent toxicity of four different types of Al-NPs (two rod-type aluminum oxide NPs [AlONPs] with different aspect ratios [short (S)- and long (L)-AlONPs], spherical aluminum cerium oxide NPs [AlCeO 3 , AlCeONPs] and spherical γ-aluminum oxide hydroxide nanoparticles [AlOOHNPs]) 13weeks after a single intratracheal instillation, considering the importance of their properties in their toxicity. We found that the pulmonary biopersistence of Al-NPs was strengthened by a high aspect ratio in the rod-type AlONPs and by the presence of hydroxyl groups in the spherical-type Al-NPs. The highest toxicity was observed in the mice treated with AlOOHNPs, which showed low biostability. More importantly, we identified that the commercially available AlCeONPs were Al 2 O 3 -coated CeO 2 NPs, but not AlCeO 3 NPs, although they have been sold under the trade name of AlCeONPs. In conclusion, the aspect ratio and biostability may be important factors in the determination of the biopersistence of NPs and the subsequent biological response. In addition, the physicochemical properties of NPs should be examined in detail before their release into the market to prevent unexpected adverse health effects. Copyright © 2017 John Wiley & Sons, Ltd.

The study of optimization on process parameters of high-accuracy computerized numerical control polishing

NASA Astrophysics Data System (ADS)

Huang, Wei-Ren; Huang, Shih-Pu; Tsai, Tsung-Yueh; Lin, Yi-Jyun; Yu, Zong-Ru; Kuo, Ching-Hsiang; Hsu, Wei-Yao; Young, Hong-Tsu

2017-09-01

Spherical lenses lead to forming spherical aberration and reduced optical performance. Consequently, in practice optical system shall apply a combination of spherical lenses for aberration correction. Thus, the volume of the optical system increased. In modern optical systems, aspherical lenses have been widely used because of their high optical performance with less optical components. However, aspherical surfaces cannot be fabricated by traditional full aperture polishing process due to their varying curvature. Sub-aperture computer numerical control (CNC) polishing is adopted for aspherical surface fabrication in recent years. By using CNC polishing process, mid-spatial frequency (MSF) error is normally accompanied during this process. And the MSF surface texture of optics decreases the optical performance for high precision optical system, especially for short-wavelength applications. Based on a bonnet polishing CNC machine, this study focuses on the relationship between MSF surface texture and CNC polishing parameters, which include feed rate, head speed, track spacing and path direction. The power spectral density (PSD) analysis is used to judge the MSF level caused by those polishing parameters. The test results show that controlling the removal depth of single polishing path, through the feed rate, and without same direction polishing path for higher total removal depth can efficiently reduce the MSF error. To verify the optical polishing parameters, we divided a correction polishing process to several polishing runs with different direction polishing paths. Compare to one shot polishing run, multi-direction path polishing plan could produce better surface quality on the optics.

Volume determination of irregularly-shaped quasi-spherical nanoparticles.

PubMed

Attota, Ravi Kiran; Liu, Eileen Cherry

2016-11-01

Nanoparticles (NPs) are widely used in diverse application areas, such as medicine, engineering, and cosmetics. The size (or volume) of NPs is one of the most important parameters for their successful application. It is relatively straightforward to determine the volume of regular NPs such as spheres and cubes from a one-dimensional or two-dimensional measurement. However, due to the three-dimensional nature of NPs, it is challenging to determine the proper physical size of many types of regularly and irregularly-shaped quasi-spherical NPs at high-throughput using a single tool. Here, we present a relatively simple method that determines a better volume estimate of NPs by combining measurements from their top-down projection areas and peak heights using two tools. The proposed method is significantly faster and more economical than the electron tomography method. We demonstrate the improved accuracy of the combined method over scanning electron microscopy (SEM) or atomic force microscopy (AFM) alone by using modeling, simulations, and measurements. This study also exposes the existence of inherent measurement biases for both SEM and AFM, which usually produce larger measured diameters with SEM than with AFM. However, in some cases SEM measured diameters appear to have less error compared to AFM measured diameters, especially for widely used IS-NPs such as of gold, and silver. The method provides a much needed, proper high-throughput volumetric measurement method useful for many applications. Graphical Abstract The combined method for volume determination of irregularly-shaped quasi-spherical nanoparticles.

Magnetic spherical cores partly coated with periodic mesoporous organosilica single crystals.

PubMed

Li, Jing; Wei, Yong; Li, Wei; Deng, Yonghui; Zhao, Dongyuan

2012-03-07

Core-shell structured materials are of special significance in various applications. Until now, most reported core-shell structures have polycrystalline or amorphous coatings as their shell layers, with popular morphologies of microspheres or quasi-spheres. However, the single crystals, either mesoscale or atomic ones, are still rarely reported as shell layers. If single crystals can be coated on core materials, it would result in a range of new type core-shell structures with various morphologies, and probably more potential applications. In this work, we demonstrate that periodic mesoporous organosilica (PMO) single crystals can partly grow on magnetic microspheres to form incomplete Fe(3)O(4)@nSiO(2)@PMO core-shell materials in aqueous solution, which indeed is the first illustration that mesoporous single-crystal materials can be used as shell layers for preparation of core-shell materials. The achieved materials have advantages of high specific surface areas, good magnetic responses, embedded functional groups and cubic mesopore channels, which might provide them with various application conveniences. We suppose the partial growth is largely decided by the competition between growing tendency of single crystals and the resistances to this tendency. In principle, other single crystals, including a range of atomic single crystals, such as zeolites, are able to be developed into such core-shell structures.