Sample records for astar 811c

  1. Development of advanced high strength tantalum base alloys. Phase 3: Influence of metallurgical condition on the mechanical properties of ASTAR-811C sheet (United States)

    Ammon, R. L.; Buckman, R. W., Jr.; Harrod, D. L.


    Metallurgical condition was shown to have a significant effect on the creep properties of ASTAR-811C (Ta-8W-1Re-0.7Hf-0.025C) sheet. Cold worked material exhibited creep rates 30 times higher than solution annealed material and 10 times greater than for recrystallized material. Both grain size and the carbide morphology changes as the final annealing temperature was raised from 3000 F to 3600 F. However, the lowest creep rates were achieved for material which retained the high temperature form of the Ta2C precipitate. Samples with GTA weldments had essentially identical properties as recrystallized base metal. Cooling rates from 3600 F of 5, 50, and 800 F deg/min. had little effect on the 2000 and 2400 F creep behavior of ASTAR-811C.

  2. Process development of two high strength tantalum base alloys (ASTAR-1211C and ASTAR-1511C) (United States)

    Ammon, R. L.


    Two tantalum base alloys, Ta-12W-1.0Re-0.7Hf-0.025C(ASTAR-1211C) and Ta-15W-1.0Re-0.7Hf-0.025C(ASTAR-1511C), were cast as 12.5 cm (5 inch) diameter ingots and processed to swaged rod, sheet, forged plate, and tubing. Swaged rod was evaluated with respect to low temperature ductility, elevated temperature tensile properties, and elevated temperature creep behavior. A standard swaging process and final annealing schedule were determined. Elevated temperature tensile properties, low temperature impact properties, low temperature DBTT behavior, and extended elevated temperature creep properties were determined. A process for producing ASTAR-1211C and ASTAR-1511C sheet were developed. The DBTT properties of GTA and EB weld sheet given post-weld anneal and thermal aging treatments were determined using bend and tensile specimens. High and low temperature mechanical properties of forging ASTAR-1211C and ASTAR-1511C plate were determined as well as elevated temperature creep properties. Attempts to produce ASTAR-1211C tubing were partially successful while attempts to make ASTAR-1511C tubing were completely unsuccessful.

  3. CAF: Cluster algorithm and a-star with fuzzy approach for lifetime enhancement in wireless sensor networks

    KAUST Repository

    Yuan, Y.


    Energy is a major factor in designing wireless sensor networks (WSNs). In particular, in the real world, battery energy is limited; thus the effective improvement of the energy becomes the key of the routing protocols. Besides, the sensor nodes are always deployed far away from the base station and the transmission energy consumption is index times increasing with the increase of distance as well. This paper proposes a new routing method for WSNs to extend the network lifetime using a combination of a clustering algorithm, a fuzzy approach, and an A-star method. The proposal is divided into two steps. Firstly, WSNs are separated into clusters using the Stable Election Protocol (SEP) method. Secondly, the combined methods of fuzzy inference and A-star algorithm are adopted, taking into account the factors such as the remaining power, the minimum hops, and the traffic numbers of nodes. Simulation results demonstrate that the proposed method has significant effectiveness in terms of balancing energy consumption as well as maximizing the network lifetime by comparing the performance of the A-star and fuzzy (AF) approach, cluster and fuzzy (CF)method, cluster and A-star (CA)method, A-star method, and SEP algorithm under the same routing criteria. 2014 Yali Yuan et al.

  4. EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2014. Scientific Opinion on the safety of astaxanthin-rich ingredients (AstaREAL A1010 and AstaREAL L10) as novel food ingredients

    DEFF Research Database (Denmark)

    Tetens, Inge; Poulsen, Morten


    , specification, manufacture and stability of the NFIs. The NFIs are intended to be used in fermented liquid dairy products, non-fermented liquid dairy products, fermented soya products and fruit drinks for healthy adults. The applicant recommends a maximum consumption of astaxanthin from the NFIs of 4 mg......Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver a scientific opinion on the safety of astaxanthin-rich ingredients AstaREAL A1010 and AstaREAL L10 as novel food ingredients (NFIs) in the context of Regulation...

  5. Ground-based lidar measurements from Ny-Ålesund during ASTAR 2007

    Directory of Open Access Journals (Sweden)

    A. Herber


    Full Text Available During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR in March and April 2007, measurements obtained at the AWIPEV Arctic Research Base in Ny-Ålesund, Spitsbergen at 78.9° N, 11.9° E (operated by the Alfred Wegener Institute for Polar and Marine Research – AWI and the Institut polaire français Paul-Emile Victor – IPEV, supported the airborne campaign. This included lidar data from the Koldewey Aerosol Raman Lidar (KARL and the Micro Pulse Lidar (MPL, located in the atmospheric observatory as well as photometer data and the daily launched radiosonde. The MPL features nearly continuous measurements; the KARL was switched on whenever weather conditions allowed observations (145 h in 61 days. From 1 March to 30 April, 71 meteorological balloon soundings were performed and compared with the concurrent MPL measurements; photometer measurements are available from 18 March. For the KARL data, a statistical overview of particle detection based on their optical properties backscatter ratio and volume depolarization can be given. The altitudes of the occurrence of the named features (subvisible and visible ice and water as well as mixed-phase clouds, aerosol layers as well as their dependence on different air mass origins are analyzed. Although the spring 2007 was characterized by rather clean conditions, diverse case studies of cloud and aerosol occurrence during March and April 2007 are presented in more detail, including temporal development and main optical properties as depolarization, backscatter and extinction coefficients. Links between air mass origins and optical properties can be presumed but need further evidence.

  6. Spectral Evidence for an Inner Carbon-rich Circumstellar Belt in the Young HD 36546 A-star System

    Energy Technology Data Exchange (ETDEWEB)

    Lisse, C. M. [JHU-APL, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Sitko, M. L. [Department of Physics, University of Cincinnati, Cincinnati, OH 45221-0011 and Space Science Institute, Boulder, CO 80301 (United States); Russell, R. W. [The Aerospace Corporation, Los Angeles, CA 90009 (United States); Marengo, M. [Department of Physics and Astronomy, 12 Physics Hall, Iowa State University, Ames, IA 50010 (United States); Currie, T. [Subaru Telescope, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Hilo, HI 96720 (United States); Melis, C. [Center for Astrophysics and Space Sciences, University of California, San Diego, CA 92093-0424 (United States); Mittal, T. [Department of Earth and Planetary Sciences, McCone Hall, University of California at Berkeley, Berkeley, CA 94720 (United States); Song, I., E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail: [Department of Physics and Astronomy, University of Georgia, Athens, GA 30602-2451 (United States)


    Using the NASA/IRTF SpeX and BASS spectrometers we have obtained 0.7–13 μ m observations of the newly imaged 3–10 Myr old HD 36546 disk system. The SpeX spectrum is most consistent with the photospheric emission expected from an L {sub *} ∼ 20 L {sub ⊙}, solar abundance A1.5V star with little to no extinction, and excess emission from circumstellar dust detectable beyond 4.5 μ m. Non-detections of CO emission lines and accretion signatures point to the gas-poor circumstellar environment of a very old transition disk. Combining the SpeX + BASS spectra with archival WISE / AKARI / IRAS / Herschel photometry, we find an outer cold dust belt at ∼135 K and 20–40 au from the primary, likely coincident with the disk imaged by Subaru, and a new second inner belt with a temperature ∼570 K and an unusual, broad SED maximum in the 6–9 μ m region, tracing dust at 1.1–2.2 au. An SED maximum at 6–9 μ m has been reported in just two other A-star systems, HD 131488 and HD 121191, both of ∼10 Myr age. From Spitzer , we have also identified the ∼12 Myr old A7V HD 148657 system as having similar 5–35 μ m excess spectral features. The Spitzer data allows us to rule out water emission and rule in carbonaceous materials—organics, carbonates, SiC—as the source of the 6–9 μ m excess. Assuming a common origin for the four young A-star systems’ disks, we suggest they are experiencing an early era of carbon-rich planetesimal processing.

  7. Passive Infrared (PIR)-Based Indoor Position Tracking for Smart Homes Using Accessibility Maps and A-Star Algorithm. (United States)

    Yang, Dan; Xu, Bin; Rao, Kaiyou; Sheng, Weihua


    Indoor occupants' positions are significant for smart home service systems, which usually consist of robot service(s), appliance control and other intelligent applications. In this paper, an innovative localization method is proposed for tracking humans' position in indoor environments based on passive infrared (PIR) sensors using an accessibility map and an A-star algorithm, aiming at providing intelligent services. First the accessibility map reflecting the visiting habits of the occupants is established through the integral training with indoor environments and other prior knowledge. Then the PIR sensors, which placement depends on the training results in the accessibility map, get the rough location information. For more precise positioning, the A-start algorithm is used to refine the localization, fused with the accessibility map and the PIR sensor data. Experiments were conducted in a mock apartment testbed. The ground truth data was obtained from an Opti-track system. The results demonstrate that the proposed method is able to track persons in a smart home environment and provide a solution for home robot localization.

  8. NuSTAR Detection of High-Energy X-Ray Emission and Rapid Variability from Sagittarius A(star) Flares (United States)

    Barriere, Nicolas M.; Tomsick, John A.; Baganoff, Frederick K.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Dexter, Jason; Grefenstette, Brian; Hailey, Charles J.; Zhang, William W.


    Sagittarius A(star) harbors the supermassive black hole that lies at the dynamical center of our Galaxy. Sagittarius A(star) spends most of its time in a low luminosity emission state but flares frequently in the infrared and X-ray, increasing up to a few hundred fold in brightness for up to a few hours at a time. The physical processes giving rise to the X-ray flares are uncertain. Here we report the detection with the NuSTAR observatory in Summer and Fall 2012 of four low to medium amplitude X-ray flares to energies up to 79 keV. For the first time, we clearly see that the power-law spectrum of Sagittarius A(star) X-ray flares extends to high energy, with no evidence for a cut off. Although the photon index of the absorbed power-law fits are in agreement with past observations, we find a difference between the photon index of two of the flares (significant at the 95% confidence level). The spectra of the two brightest flares (approx. 55 times quiescence in the 2- 10 keV band) are compared to simple physical models in an attempt to identify the main X-ray emission mechanism, but the data do not allow us to significantly discriminate between them. However, we confirm the previous finding that the parameters obtained with synchrotron models are, for the X-ray emission, physically more reasonable than those obtained with inverse-Compton models. One flare exhibits large and rapid (less than 100 s) variability, which, considering the total energy radiated, constrains the location of the flaring region to be within approx. 10 Schwarzschild radii of the black hole.

  9. Lidar characterization of the Arctic atmosphere during ASTAR 2007: four cases studies of boundary layer, mixed-phase and multi-layer clouds

    Directory of Open Access Journals (Sweden)

    A. Lampert


    Full Text Available During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR, which was conducted in Svalbard in March and April 2007, tropospheric Arctic clouds were observed with two ground-based backscatter lidar systems (micro pulse lidar and Raman lidar and with an airborne elastic lidar. In the time period of the ASTAR 2007 campaign, an increase in low-level cloud cover (cloud tops below 2.5 km from 51% to 65% was observed above Ny-Ålesund. Four different case studies of lidar cloud observations are analyzed: With the ground-based Raman lidar, a layer of spherical particles was observed at an altitude of 2 km after the dissolution of a cloud. The layer probably consisted of small hydrated aerosol (radius of 280 nm with a high number concentration (around 300 cm−3 at low temperatures (−30 °C. Observations of a boundary layer mixed-phase cloud by airborne lidar and concurrent airborne in situ and spectral solar radiation sensors revealed the localized process of total glaciation at the boundary of different air masses. In the free troposphere, a cloud composed of various ice layers with very different optical properties was detected by the Raman lidar, suggesting large differences of ice crystal size, shape and habit. Further, a mixed-phase double layer cloud was observed by airborne lidar in the free troposphere. Local orography influenced the evolution of this cloud. The four case studies revealed relations of cloud properties and specific atmospheric conditions, which we plan to use as the base for numerical simulations of these clouds.

  10. Mass transfer in a 1370 C (2500 F) lithium thermal convection loop (United States)

    Scheuermann, C. M.


    Experimental results from a test to evaluate interstitial element mass transfer effects on T-111, ASTAR 811C, and ASTAR 1211C after 5000 hours in flowing lithium at 1370 C (2500 F) are presented. No gross corrosion effects were observed. However, hafnium and nitrogen transfer to cooler regions within the loop were noted. Oxygen was in general removed from test specimens, but there was no evidence to indicate that it was a major factor in the mass transfer process. Carbon and hydrogen transfer were not detected.

  11. Influence of creep damage on the low cycle thermal-mechanical fatigue behavior of two tantalum base alloys (United States)

    Sheffler, K. D.; Doble, G. S.


    Low cycle fatigue tests have been performed on the tantalum base alloys T-111 and ASTAR 811C with synchronized, independently programmed temperature and strain cycling. The thermal-mechanical cycles applied fell into three basic categories: these were isothermal cycling, in-phase thermal cycling, and out-of-phase thermal cycling. In-phase cycling was defined as tensile deformation associated with high temperature and compressive deformation with low temperature, while out-of-phase thermal cycling was defined as the reverse case. The in-phase thermal cycling had a pronounced detrimental influence on the fatigue life of both alloys, with the life reduction being greater in the solid solution strengthened T-111 alloy than in the carbide strengthened ASTAR 811C alloy. The out-of-phase tests also showed pronounced effects on the fatigue life of both alloys, although not as dramatic.

  12. Closeout of JOYO-1 Specimen Fabrication Efforts

    Energy Technology Data Exchange (ETDEWEB)

    ME Petrichek; JL Bump; RF Luther


    Fabrication was well under way for the JOYO biaxial creep and tensile specimens when the NR Space program was canceled. Tubes of FS-85, ASTAR-811C, and T-111 for biaxial creep specimens had been drawn at True Tube (Paso Robles, CA), while tubes of Mo-47.5 Re were being drawn at Rhenium Alloys (Cleveland, OH). The Mo-47.5 Re tubes are now approximately 95% complete. Their fabrication and the quantities produced will be documented at a later date. End cap material for FS-85, ASTAR-811C, and T-111 had been swaged at Pittsburgh Materials Technology, Inc. (PMTI) (Large, PA) and machined at Vangura (Clairton, PA). Cutting of tubes, pickling, annealing, and laser engraving were in process at PMTI. Several biaxial creep specimen sets of FS-85, ASTAR-811C, and T-111 had already been sent to Pacific Northwest National Laboratory (PNNL) for weld development. In addition, tensile specimens of FS-85, ASTAR-811C, T-111, and Mo-47.5 Re had been machined at Kin-Tech (North Huntington, PA). Actual machining of the other specimen types had not been initiated. Flowcharts 1-3 detail the major processing steps each piece of material has experienced. A more detailed description of processing will be provided in a separate document [B-MT(SRME)-51]. Table 1 lists the in-process materials and finished specimens. Also included are current metallurgical condition of these materials and specimens. The available chemical analyses for these alloys at various points in the process are provided in Table 2.

  13. Aircraft Route Optimization using the A-Star Algorithm (United States)


    provides analysis and results of the implementation of the algorithm, and compares it to other approaches to the routing problem. Chapter 5 provides a... multicriteria optimization approach to address this issue. The proposed obstacle avoidance model provides a proof of concept for the use of a grid based

  14. Cost Estimate for Molybdenum and Tantalum Refractory Metal Alloy Flow Circuit Concepts (United States)

    Hickman, Robert R.; Martin, James J.; Schmidt, George R.; Godfroy, Thomas J.; Bryhan, A.J.


    The Early Flight Fission-Test Facilities (EFF-TF) team at NASA Marshall Space Flight Center (MSFC) has been tasked by the Naval Reactors Prime Contract Team (NRPCT) to provide a cost and delivery rough order of magnitude estimate for a refractory metal-based lithium (Li) flow circuit. The design is based on the stainless steel Li flow circuit that is currently being assembled for an NRPCT task underway at the EFF-TF. While geometrically the flow circuit is not representative of a final flight prototype, knowledge has been gained to quantify (time and cost) the materials, manufacturing, fabrication, assembly, and operations to produce a testable configuration. This Technical Memorandum (TM) also identifies the following key issues that need to be addressed by the fabrication process: Alloy selection and forming, cost and availability, welding, bending, machining, assembly, and instrumentation. Several candidate materials were identified by NRPCT including molybdenum (Mo) alloy (Mo-47.5 %Re), tantalum (Ta) alloys (T-111, ASTAR-811C), and niobium (Nb) alloy (Nb-1 %Zr). This TM is focused only on the Mo and Ta alloys, since they are of higher concern to the ongoing effort. The initial estimate to complete a Mo-47%Re system ready for testing is =$9,000k over a period of 30 mo. The initial estimate to complete a T-111 or ASTAR-811C system ready for testing is =$12,000k over a period of 36 mo.

  15. US EPA - A*Star Partnership - Accelerating the Acceptance of Next-Generation Sciences and Their Application to Regulatory Risk Assessment (A*Star Symposium, Singapore) (United States)

    The path for incorporating new alternative methods and technologies into quantitative chemical risk assessment poses a diverse set of scientific challenges. Some of these challenges include development of relevant and predictive test systems and computational models to integrate...

  16. Algorithm for Surface of Translation Attached Radiators (A-STAR). Volume III. Computer Codes. (United States)


    CCX1 OUN1DP 20*Rt0 110-4** C01 EOR TILIC SRI URG6T T, E UT ,IUTPUT,TAPF5-INPUTPTAPE60OUTPUTP 405 OTZCC GENERATES THE CAP Z PIATRIX. 1S 88856 UNIT 5...6EQXt~l*AWD. Yt1I.E@.Y(NI) ZEDGE-0 1 9 YLuZ-DY/2.r22 a BLI:1 41?c L NE Kim LANK ( 411ii IFI VII: Ul81 TO 9 4 5 Ke Ill-XM N)I(XMAX-XMINl*INC-1)I1., 4...1,NC1 IfILIN(K) ) LANK 712 IF(MCD(Kp1C3.E0.1) LINE(Ke’lPIiF3 13 CONTINUE 140 WR iTEI 6#30621 LYpLX,(LINE( ,..’ElpC1) 17150 WRI Et 6s507) KNIN,(MEAO(I)o

  17. Algorithm for Surface of Translation Attached Radiators (A-STAR). Volume II. User’s Manual (United States)


    input daca for Problems 2a-2c ....................... 46 11. Pirtial output of BOTZSS for Problems 2a-2c:. Z ................ 47 12. PFrtial output specified points in the vicinity oi the BOT surface. User-oriented programa features - The programs are liberally interspersed with comment

  18. A Socially Inclusive A-Star Is Only Possible through the Understanding of Black Holes (United States)

    Draper, Ciara; Houghton, Jack; Read, Beth; Bird, Danny; Tatten, J. J.


    This article is written by young people who attend an open-access youth project in the city centre of Hull. Although they describe themselves as "educational failures" (the "black holes"), they argue that they have a significant contribution to make to discussions about how to develop socially just education in schools. In the…

  19. Polarized light from Sagittarius A(star) in the near-infrared K-s-band

    Czech Academy of Sciences Publication Activity Database

    Shahzamanian, B.; Eckart, A.; Valencia-S, M.; Witzel, G.; Zamaninasab, M.; Sabha, N.; García-Marín, M.; Karas, Vladimír; Karssen, G.; Borkar, A.; Dovčiak, Michal; Kunneriath, Devaky; Bursa, Michal; Buchholz, R. M.; Moultaka, J.; Straubmeier, C.


    Roč. 576, April (2015), A20/1-A20/18 ISSN 0004-6361 Grant - others:EU(XE) COST Action MP0905; EU(XE) COST action MP1104 Institutional support: RVO:67985815 Keywords : black hole physics * accretion disks * galaxy center Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

  20. ATM Technology Demonstration 1 (ATD-1): EcoDemonstrator ASTAR Guided Arrival Research (EAGAR) (United States)

    Roper, Roy


    In Spring 2013, high level NASA and Boeing management were seeking opportunities to collaborate on a flight test activity involving the ecoDemonstrator. The Airspace Systems Program Office identified FIM as a viable candidate. ATD-1 accepted the challenge. Work began in July for a December 2013 flight test.


    Directory of Open Access Journals (Sweden)

    Nuri Rahmawati


    Full Text Available Dalam perkembangan Sistem Informasi Geografis (SIG dapat dijadikan sebagai alat bantu dalam menentukan rute jalur jalan dari suatu lokasi menuju lokasi lain, seperti penentuan rute dengan menggunakan extension pgRouting. Extension pgRouting ini dapat memecahkan masalah dari kelemahan penggambaran, perhitungan, dan penganalisa kemiringan dan jarak jalur jalan kendaraan angkut tambang terbukayang digunakan pada seksi survei tambang (Mine Survey Section Distrik Anugerah Bara Kaltim Loa Janan (ABKL PT Pamapersada Nusantara (PAMA. Pada penelitian ini extension pgRouting akan diterapkan untuk menganalisa jalur jalan kendaraan angkut yang lebih otomatis. Metode yang digunakan pada extension pgRouting penelitian ini adalah algoritmaa-star (A*. Extension pgRouting dapat menampilkan kemiringan dan jarak jalur jalan kendaraan angkut secara otomatis yang memiliki kemiringan diatas 8% jalur jalan yang dilalui kendaraan angkut. Tetapi pgRouting memiliki kelemahan pada parameter yang digunakan koordinat X dan Y saja, sementara untuk mendapatkan nilai kemiringan jalur jalan kendaraan angkut dibutuhkan parameter koordinat Z. Memodifikasi pgRouting 2D menjadi pgRouting 3D adalah metode yang dapat digunakan untuk memecahkan kelemahan metode extension pgRouting tersebut untuk membantu membaca parameter koordinat Z. Hasil penelitian ini adalah profil melintang rute jalur jalan kendaraan angkut dan update kolom geometri rute jalur kendaraan angkut tiap-tiap jenis kendaraan.

  2. Technology status of tantalum alloys for space nuclear power applications (United States)

    Hoffman, E. E.


    Tantalum alloys have a variety of properties which make them attractive candidates for application in nuclear power systems required to operate in space at elevated temperatures (1200 to 1600 K) for extended time periods. Most of the technology development on this class of alloys which is pertinent to space system application occurred during the 1960 to 1972 time period under NASA sponsorship. The most extensive data bases resulting from this earlier work were obtained on the alloys T-111 (Ta-8W-2Hf) and ASTAR 811C (Ta-8W-1Re-0.7Hf-0.025C). Emphasis in this paper is directed at the following technical factors: producibility, creep strength, weldability and compatibility. These factors are considered to be the most important elements in the selection of alloys for this application. Review of the available information indicates that alloys of this type are appropriate for application in many systems, particularly those utilizing alkali metals as the working fluid.

  3. Biaxial Creep Specimen Fabrication

    Energy Technology Data Exchange (ETDEWEB)

    JL Bump; RF Luther


    This report documents the results of the weld development and abbreviated weld qualification efforts performed by Pacific Northwest National Laboratory (PNNL) for refractory metal and superalloy biaxial creep specimens. Biaxial creep specimens were to be assembled, electron beam welded, laser-seal welded, and pressurized at PNNL for both in-pile (JOYO reactor, O-arai, Japan) and out-of-pile creep testing. The objective of this test campaign was to evaluate the creep behavior of primary cladding and structural alloys under consideration for the Prometheus space reactor. PNNL successfully developed electron beam weld parameters for six of these materials prior to the termination of the Naval Reactors program effort to deliver a space reactor for Project Prometheus. These materials were FS-85, ASTAR-811C, T-111, Alloy 617, Haynes 230, and Nirnonic PE16. Early termination of the NR space program precluded the development of laser welding parameters for post-pressurization seal weldments.


    National Aeronautics and Space Administration — The Clementine EDR (Engineering Data Record) Image Archive contains 88 CD-ROM volumes with more than 1.9 million images. Each volume contains approximately 3 lunar...

  5. Interdiffusion behavior of tungsten or rhenium and group 5 and 6 elements and alloys of the periodic table, part 1. [at dissimilar metal joints (United States)

    Arcella, F. G.


    Arc cast W, CVD W, CVD Re, and powder metallurgy Re materials were hot isostatically pressure welded to ten different refractory metals and alloys (Cb, Cb-1Zr, Ta, Ta-10W, T-111, ASTAR-811C, W-25Re, Mo-50Re, W-30Re-20Mo, ect.) and thermally aged at 10 to the minus 8th power torr at 1200, 1500, 1630, 1800, and 2000 C for 100 to 2000 hours. Electron beam microprobe analysis was used to characterize the interdiffusion zone width of each couple system as a function of age time and temperature. Extrapolations of interdiffusion zone thickness to 10,000 hours were made. Classic interdiffusion analysis was performed for several of the systems by Boltzmann-Matano analysis. A method of inhibiting Kirkendall voids from forming during thermal ageing of dissimilar metal junctions was devised and experimentally demonstrated. An electron beam weld study of Cb-1Zr to Re and W-25Re demonstrated the limited acceptability of these welds.

  6. Technology for Bayton-cycle powerplants using solar and nuclear energy (United States)

    English, R. E.


    Brayton cycle gas turbines have the potential to use either solar heat or nuclear reactors for generating from tens of kilowatts to tens of megawatts of power in space, all this from a single technology for the power generating system. Their development for solar energy dynamic power generation for the space station could be the first step in an evolution of such powerplants for a very wide range of applications. At the low power level of only 10 kWe, a power generating system has already demonstrated overall efficiency of 0.29 and operated 38 000 hr. Tests of improved components show that these components would raise that efficiency to 0.32, a value twice that demonstrated by any alternate concept. Because of this high efficiency, solar Brayton cycle power generators offer the potential to increase power per unit of solar collector area to levels exceeding four times that from photovoltaic powerplants using present technology for silicon solar cells. The technologies for solar mirrors and heat receivers are reviewed and assessed. This Brayton technology for solar powerplants is equally suitable for use with the nuclear reactors. The available long time creep data on the tantalum alloy ASTAR-811C show that such Brayton cycles can evolve to cycle peak temperatures of 1500 K (2240 F). And this same technology can be extended to generate 10 to 100 MW in space by exploiting existing technology for terrestrial gas turbines in the fields of both aircraft propulsion and stationary power generation.

  7. Processing of Refractory Metal Alloys for JOYO Irradiations

    Energy Technology Data Exchange (ETDEWEB)

    RF Luther; ME Petrichek


    This is a summary of the refractory metal processing experienced by candidate Prometheus materiats as they were fabricated into specimens destined for testing within the JOYO test reactor, ex-reactor testing at Oak Ridge National Laboratory (ORNL), or testing within the NRPCT. The processing is described for each alloy from the point of inception to the point where processing was terminated due to the cancellation of Naval Reactor's involvement in the Prometheus Project. The alloys included three tantalum-base alloys (T-111, Ta-10W, and ASTAR-811C), a niobium-base alloy, (FS-85), and two molybdenum-rhenium alloys, one containing 44.5 w/o rhenium, and the other 47.5 w/o rhenium. Each of these alloys was either a primary candidate or back-up candidate for cladding and structural applications within the space reactor. Their production was intended to serve as a forerunner for large scale production ingots that were to be procured from commercial refractory metal vendors such as Wah Chang.

  8. MASCARA-1 b. A hot Jupiter transiting a bright mV = 8.3 A-star in a misaligned orbit (United States)

    Talens, G. J. J.; Albrecht, S.; Spronck, J. F. P.; Lesage, A.-L.; Otten, G. P. P. L.; Stuik, R.; Van Eylen, V.; Van Winckel, H.; Pollacco, D.; McCormac, J.; Grundahl, F.; Fredslund Andersen, M.; Antoci, V.; Snellen, I. A. G.


    We report the discovery of MASCARA-1 b, which is the first exoplanet discovered with the Multi-site All-Sky CAmeRA (MASCARA). This exoplanet is a hot Jupiter orbiting a bright mV = 8.3, rapidly rotating (vsini⋆ > 100 km s-1) A8 star with a period of 2.148780 ± 8 × 10-6 days. The planet has a mass and radius of 3.7 ± 0.9 MJup and 1.5 ± 0.3 RJup, respectively. As with most hot Jupiters transiting early-type stars, we find a misalignment between the planet orbital axis and the stellar spin axis, which may be a signature of the formation and migration histories of this family of planets. MASCARA-1 b has a mean density of 1.5 ± 0.9 g cm-3 and an equilibrium temperature of 2570+50-30K, that is one of the highest temperatures known for a hot Jupiter to date. The system is reminiscent of WASP-33, but the host star lacks apparent delta-scuti variations, making the planet an ideal target for atmospheric characterization. We expect this to be the first of a series of hot Jupiters transiting bright early-type stars that will be discovered by MASCARA. Tables of the photometry and the reduced spectra as FITS files are only available at the CDS via anonymous ftp to ( or via

  9. Novikov-Jordan algebras


    Dzhumadil'daev, A. S.


    Algebras with identity $(a\\star b)\\star (c\\star d) -(a\\star d)\\star(c\\star b)$ $=(a,b,c)\\star d-(a,d,c)\\star b$ are studied. Novikov algebras under Jordan multiplication and Leibniz dual algebras satisfy this identity. If algebra with such identity has unit, then it is associative and commutative.

  10. Experimental Design for Evaluation of Co-extruded Refractory Metal/Nickel Base Superalloy Joints

    Energy Technology Data Exchange (ETDEWEB)

    ME Petrichek


    Prior to the restructuring of the Prometheus Program, the NRPCT was tasked with delivering a nuclear space reactor. Potential NRPCT nuclear space reactor designs for the Prometheus Project required dissimilar materials to be in contact with each other while operating at extreme temperatures under irradiation. As a result of the high reactor core temperatures, refractory metals were the primary candidates for many of the reactor structural and cladding components. They included the tantalum-base alloys ASTAR-811C and Ta-10W, the niobium-base alloy FS-85, and the molybdenum base alloys Moly 41-47.5 Rhenium. The refractory metals were to be joined to candidate nickel base alloys such as Haynes 230, Alloy 617, or Nimonic PE 16 either within the core if the nickel-base alloys were ultimately selected to form the outer core barrel, or at a location exterior to the core if the nickel-base alloys were limited to components exterior to the core. To support the need for dissimilar metal joints in the Prometheus Project, a co-extrusion experiment was proposed. There are several potential methods for the formation of dissimilar metal joints, including explosive bonding, friction stir welding, plasma spray, inertia welding, HIP, and co-extrusion. Most of these joining methods are not viable options because they result in the immediate formation of brittle intermetallics. Upon cooling, intermetallics form in the weld fusion zone between the joined metals. Because brittle intermetallics do not form during the initial bonding process associated with HIP, co-extrusion, and explosive bonding, these three joining procedures are preferred for forming dissimilar metal joints. In reference to a Westinghouse Astronuclear Laboratory report done under a NASA sponsored program, joints that were fabricated between similar materials via explosive bonding had strengths that were directly affected by the width of the diffusion barrier. It was determined that the diffusion zone should not exceed

  11. Design and performance analysis of global path planning techniques for autonomous mobile robots in grid environments

    Directory of Open Access Journals (Sweden)

    Imen Chaari


    Full Text Available This article presents the results of the 2-year iroboapp research project that aims at devising path planning algorithms for large grid maps with much faster execution times while tolerating very small slacks with respect to the optimal path. We investigated both exact and heuristic methods. We contributed with the design, analysis, evaluation, implementation and experimentation of several algorithms for grid map path planning for both exact and heuristic methods. We also designed an innovative algorithm called relaxed A-star that has linear complexity with relaxed constraints, which provides near-optimal solutions with an extremely reduced execution time as compared to A-star. We evaluated the performance of the different algorithms and concluded that relaxed A-star is the best path planner as it provides a good trade-off among all the metrics, but we noticed that heuristic methods have good features that can be exploited to improve the solution of the relaxed exact method. This led us to design new hybrid algorithms that combine our relaxed A-star with heuristic methods which improve the solution quality of relaxed A-star at the cost of slightly higher execution time, while remaining much faster than A* for large-scale problems. Finally, we demonstrate how to integrate the relaxed A-star algorithm in the robot operating system as a global path planner and show that it outperforms its default path planner with an execution time 38% faster on average.

  12. Unravelling the Evolution of the Allatostatin-Type A, KISS and Galanin Peptide-Receptor Gene Families in Bilaterians: Insights from Anopheles Mosquitoes.

    Directory of Open Access Journals (Sweden)

    Rute C Felix

    Full Text Available Allatostatin type A receptors (AST-ARs are a group of G-protein coupled receptors activated by members of the FGL-amide (AST-A peptide family that inhibit food intake and development in arthropods. Despite their physiological importance the evolution of the AST-A system is poorly described and relatively few receptors have been isolated and functionally characterised in insects. The present study provides a comprehensive analysis of the origin and comparative evolution of the AST-A system. To determine how evolution and feeding modified the function of AST-AR the duplicate receptors in Anopheles mosquitoes, were characterised. Phylogeny and gene synteny suggested that invertebrate AST-A receptors and peptide genes shared a common evolutionary origin with KISS/GAL receptors and ligands. AST-ARs and KISSR emerged from a common gene ancestor after the divergence of GALRs in the bilaterian genome. In arthropods, the AST-A system evolved through lineage-specific events and the maintenance of two receptors in the flies and mosquitoes (Diptera was the result of a gene duplication event. Speciation of Anopheles mosquitoes affected receptor gene organisation and characterisation of AST-AR duplicates (GPRALS1 and 2 revealed that in common with other insects, the mosquito receptors were activated by insect AST-A peptides and the iCa2+-signalling pathway was stimulated. GPRALS1 and 2 were expressed mainly in mosquito midgut and ovaries and transcript abundance of both receptors was modified by feeding. A blood meal strongly up-regulated expression of both GPRALS in the midgut (p < 0.05 compared to glucose fed females. Based on the results we hypothesise that the AST-A system in insects shared a common origin with the vertebrate KISS system and may also share a common function as an integrator of metabolism and reproduction.AST-A and KISS/GAL receptors and ligands shared common ancestry prior to the protostome-deuterostome divergence. Phylogeny and gene



    BAYINDIR, Funda; Kul, Esra; AKTAŞ, Esin; BAŞTOPÇU, Ayşe


    NISTATIN VE TITANYUM DIOKSIT ILAVESININ YUMUŞAK ASTAR MATERYALINDEKI CANDIDA KOLONIZASYONU ÜZERINE ETKISININ KARŞILAŞTIRILMASIAmaç. Tam protez kullanan hastalarda, yumuşak astarmateryalleri, mukozayı irrite eden lezyon oluşumları ile sonuçlanan, Candida albicans’ ların adezyonunu vekolonizasyonunu destekleyebilir. Bu çalışmanın amacı, nistatin ve titanium dioksit[TiO2] antifungal ajanlarının,yumuşak astar maddelerindeki Candidaalbicans kolonizasyonunu önlemedeki etkisini değerlendirmektir.Mat...

  14. A propósito de la anastylosis infográfica del Carambolo. Diálogo teórico y metodológico sobre la Arqueología Virtual

    Directory of Open Access Journals (Sweden)

    Ángeles Hernández-Barahona


    Full Text Available The virtual reconstruction of the adobe building located in El Carambolo (Camas, Seville, a complex sanctuary devoted to the goddess Astaré, has meant a methodological and theoretical reflection about how to carry out the most suitable reconstruction proposal. This paper shows briefly this scientific experience, developed by experts on both infography and virtual reality, and Phoenician archaeology.

  15. Constraints on the gas content of the Fomalhaut debris belt. Can gas-dust interactions explain the belt's morphology?

    NARCIS (Netherlands)

    Cataldi, G.; Brandeker, A.; Olofsson, G.; Chen, C. H.; Dent, W. R. F.; Kamp, I.; Roberge, A.; Vandenbussche, B.

    Context. The 440 Myr old main-sequence A-star Fomalhaut is surrounded by an eccentric debris belt with sharp edges. This sort of a morphology is usually attributed to planetary perturbations, but the orbit of the only planetary candidate detected so far, Fomalhaut b, is too eccentric to efficiently

  16. SwissProt search result: AK242832 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242832 J090067L13 (Q811C2) Cysteine protease APG4C (EC 3.4.22.-) (Autophagy 4 homolog C) (Auto...phagin-3) (Autophagy-related cysteine endopeptidase 3) (AUT-like 3 cysteine endopeptidase) APG4C_MOUSE 4e-37 ...

  17. SwissProt search result: AK110731 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK110731 002-170-E10 (Q811C2) Cysteine protease APG4C (EC 3.4.22.-) (Autophagy 4 homolog C) (Autop...hagin-3) (Autophagy-related cysteine endopeptidase 3) (AUT-like 3 cysteine endopeptidase) APG4C_MOUSE 6e-27 ...

  18. dE/dx and range of α-radiations in Al, Ti and Ni metallic foils

    Energy Technology Data Exchange (ETDEWEB)

    Diwan, P.K., E-mail:; Kumar, Sunil


    Highlights: • dE/dx and range of 5.486 MeV α-particles in three metallic foils have been measured. • Measured dE/dx and range values have been compared with the predictions of most commonly used theoretical/semi-empirical formulations. • Predictions of Ziegler et al. (SRIM) and ICRU-49 report (ASTAR) provide good agreement with the measured values. - Abstract: dE/dx and range of α-radiations in Al, Ti and Ni metallic foils have been measured using silicon surface barrier detector. These measured values have been compared with corresponding predicted values based on most extensively used formulations viz. Grande and Schiwietz (CasP), Northcliffe and Schilling, Benton and Henke, ICRU-49 report (ASTAR) and Ziegler et al. (SRIM). The aim of this comparison is to identify the formulation that shows good agreement with the presently measured values.

  19. Issues Regarding the Current and Future Use of the Civil Reserve Air Fleet (United States)


    that currently rely on DoD for a large share of their business if those carriers could not recoup that loss by serving more commercial customers ...Reports. 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 0 10 20 30 40 50 60 ASTAR Air Cargo/ DHL Atlas Air/Polar Air Evergreen International...CRAF Carriers’ Revenues from Commercial Customers (Percentage of revenues) Source: Congressional Budget Office based on 2007 data from the United

  20. Stopping-Power and Range Tables for Electrons, Protons, and Helium Ions (United States)

    SRD 124 Stopping-Power and Range Tables for Electrons, Protons, and Helium Ions (Web, free access)   The databases ESTAR, PSTAR, and ASTAR calculate stopping-power and range tables for electrons, protons, or helium ions. Stopping-power and range tables can be calculated for electrons in any user-specified material and for protons and helium ions in 74 materials.

  1. Improvements in the stopping power library libdEdx and release of the web GUI

    DEFF Research Database (Denmark)

    Toftegaard, Jakob; Lühr, Armin; Sobolevsky, Nikolai


    Abstract. Purpose: In ion beam therapy electronic stopping power data enter in different disciplines, e.g., dose planning, dosimetry, and radiobiology. However, relevant stopping power data are only known within an accuracy of 2%-10%. We started the software library project libdEdx to unify data...... from several well-known stopping power sources into one ready-to-use package being 1) freely available and 2) easy accessible via a web-based front end. Methods: Currently, stopping power data from PSTAR, ASTAR, MSTAR and ICRU49+73 are implemented along with a version of the Bethe formula. The library...

  2. Complete intersections in certain affine and projective monomial curves


    Bermejo, I.; García-Marco, I.


    Let $k$ be an arbitrary field, the purpose of this work is to provide families of positive integers $\\mathcal{A} = \\{d_1,\\ldots,d_n\\}$ such that either the toric ideal $I_{\\mathcal A}$ of the affine monomial curve $\\mathcal C = \\{(t^{d_1},\\ldots,\\,t^{d_n}) \\ | \\ t \\in k\\} \\subset \\mathbb{A}_k^n$ or the toric ideal $I_{\\mathcal A^{\\star}}$ of its projective closure ${\\mathcal C^{\\star}} \\subset \\mathbb{P}_k^n$ is a complete intersection. More precisely, we characterize the complete intersectio...

  3. A Shear Strain Route Dependency of Martensite Formation in 316L Stainless Steel. (United States)

    Kang, Suk Hoon; Kim, Tae Kyu; Jang, Jinsung; Oh, Kyu Hwan


    In this study, the effect of simple shearing on microstructure evolution and mechanical properties of 316L austenitic stainless steel were investigated. Two different shear strain routes were obtained by twisting cylindrical specimens in the forward and backward directions. The strain-induced martensite phase was effectively obtained by alteration of the routes. Formation of the martensite phase clearly resulted in significant hardening of the steel. Grain-size reduction and strain-induced martensitic transformation within the deformed structures of the strained specimens were characterized by scanning electron microscopy - electron back-scattered diffraction, X-ray diffraction, and the TEM-ASTAR (transmission electron microscopy - analytical scanning transmission atomic resolution, automatic crystal orientation/phase mapping for TEM) system. Significant numbers of twin networks were formed by alteration of the shear strain routes, and the martensite phases were nucleated at the twin interfaces.

  4. Symmetric Pairs of Unbounded Operators in Hilbert Space, and Their Applications in Mathematical Physics (United States)

    Jorgensen, Palle E. T.; Pearse, Erin P. J.


    In a previous paper, the authors introduced the idea of a symmetric pair of operators as a way to compute self-adjoint extensions of symmetric operators. In brief, a symmetric pair consists of two densely defined linear operators A and B, with A \\subseteq B^{\\star } and B \\subseteq A^{\\star }. In this paper, we will show by example that symmetric pairs may be used to deduce closability of operators and sometimes even compute adjoints. In particular, we prove that the Malliavin derivative and Skorokhod integral of stochastic calculus are closable, and the closures are mutually adjoint. We also prove that the basic involutions of Tomita-Takesaki theory are closable and that their closures are mutually adjoint. Applications to functions of finite energy on infinite graphs are also discussed, wherein the Laplace operator and inclusion operator form a symmetric pair.

  5. Determine Neutron Yield From Beryllium Compounds Bombarding With Alpha Particles

    Directory of Open Access Journals (Sweden)

    Osamah Nawfal Oudah


    Full Text Available Abstract The chemical combination of Beryllium used in the amp945n reaction as a target materials. wherefore Beryllium has generally been the material of select when manufacturing a neutron source. Beryllium compounds has a significant impact on the scheme and manufacture of the 238Cm-9Be neutron source. In present work the Beryllium chemical combinations were considered as a producer of neutrons with different percentage of mass and the neutron yields were likewise determined using the outcomes of the ASTAR calculations per unit incident charge. The neutron yields of Beryllium Oxide Beryllium Carbide Beryllium Hydride Beryllium Hydroxide and Beryllium Nitride were calculated as 3.1006e-005 3.0365e-005 2.2866e-005 2.0464e-005 and 3.0386e-005respectively. The results show that the Beryllium Oxide is a suitable material to use in the 238Cm-9Be neutron source.

  6. Is the Binary Mass Ratio Distribution Separation-Dependent? (United States)

    Gullikson, Kevin; Kraus, Adam L.


    Recent discoveries of planets orbiting retired A-stars on close orbits and young A-stars on very wide orbits have renewed interest in the properties of nearby intermediate-mass stars. Especially interesting are the young stars because directly-imaged planets orbiting them may be bright enough for characterization (e.g. HR 8799, Beta Pictoris, etc). However, intermediate-mass stars and especially young intermediate mass stars are part of multiple systems more often than not. Close stellar companions may affect the formation and orbital evolution of any planets, and the properties of the companions can help constrain the binary formation mechanism. The mass ratio distribution of a population of binary stars, especially if the distribution for close companions is significantly different from that of wide companions, is helpful to distinguish companions that were born in or affected by the circumstellar disk from those which formed through fragmentation of the molecular core. Previous imaging surveys have found that binary systems with A-type primary stars tend to have cool companions with extreme mass ratios. There are hints at a much flatter mass ratio distribution for close companions, but strong completeness effects complicate the picture. We have conducted a spectroscopic survey of ~400 nearby main sequence A- and B-type stars, aimed at detecting stellar companions as late as M4 for all orbital separations <100 AU. We have searched for companions to the stars by cross-correlating the spectra against model templates for F-M type stars; a significant peak in the cross-correlation function indicates a detection. Our cross-correlation technique can detect low-mass companions with orbits that are too wide to detect with radial velocity monitoring and too small to detect with imaging techniques, making it complementary to work already done. We will present results from our survey and compare the mass ratio distribution we measure to the corresponding distribution for

  7. Low Mass Stellar Companions to Nearby A and B Stars (United States)

    Gullikson, Kevin; Kraus, Adam L.


    Recent discoveries of planets orbiting retired A-stars on close orbits and young A-stars on very wide orbits have renewed interest in the properties of nearby intermediate-mass stars. Especially interesting are the young stars, because directly-imaged planets orbiting them may be bright enough for characterization (e.g. HR 8799, Beta Pictoris, etc). However, intermediate-mass stars and especially young intermediate mass stars are part of multiple systems more often than not. Close stellar companions may affect the formation and orbital evolution of any planets, and the properties of the companions can help constrain the binary formation mechanism. The mass ratio distribution of a population of stars, especially if it is significantly different from the distribution for wide companions, is helpful to distinguish companions that were born in or affected by the circumprimary disk from those which formed through fragmentation of the molecular core. We have conducted a spectroscopic survey of 400 nearby A- and B-type stars, aimed at detecting stellar companions as late as M4 for all orbital separations <100 AU. We have searched for companions to the stars by cross-correlating the spectra against model templates for F-M type stars; a significant peak in the cross-correlation function indicates a detection. Our cross-correlation technique can detect low-mass companions with orbits that are too wide to detect with radial velocity monitoring and too small to detect with imaging techniques, making it complementary to work already done. We present initial results from our survey and present the distribution of mass ratios for inner companions.

  8. Activation-resistant homozygous protein C R229W mutation causing familial perinatal intracranial hemorrhage and delayed onset of thrombosis. (United States)

    Alsultan, Abdulrahman; Gale, Andrew J; Kurban, Kadijah; Khalifah, Mohammed; Albadr, Fahad B; Griffin, John H


    We describe a family with two first-degree cousins who presented with similar phenotypes characterized by neonatal intracranial hemorrhage and subsequent onset of thrombosis. We enrolled the two affected patients, five unaffected family members and fifty-five normal controls. Clinical, laboratory, and radiological characteristics of patients were obtained. Exome sequencing was performed for the older affected child. PROC c.811 C>T was genotyped by PCR in patients, family members, and controls. Protein C amidolytic activity and antigen were measured using the STACHROM® protein C kit and ELISAs. To define functional abnormalities caused by the patients' mutation, recombinant wildtype protein C and its mutants R229W, R229Q and R229A were studied. For the two cousins, protein C amidolytic activity was 61% and 59% and antigen was 57% and 73% (nl 70-140%), respectively. Exome sequencing revealed a homozygous variant in exon 9 of the protein C (PROC) gene c.811 C>T (R229W). The R229W mutation is located in the calcium binding loop of protein C's protease domain that mediates thrombomodulin interactions. Recombinant R229W-protein C mutant was strikingly defective in rate of activation by thrombin: thrombomodulin, suggesting an in vivo deficit in these children for generation of activated protein C. These cases emphasize that protein C and activated protein C are important in maintaining the integrity of the brain vascular endothelium in humans. Moreover, routine protein C assays utilizing snake venom protease fail to detect protein C mutants that are resistant to thrombin:thrombomodulin activation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Airborne DOAS limb measurements of tropospheric trace gas profiles: case studies on the profile retrieval of O4 and BrO

    Directory of Open Access Journals (Sweden)

    N. Theys


    Full Text Available A novel limb scanning mini-DOAS spectrometer for the detection of UV/vis absorbing radicals (e.g., O3, BrO, IO, HONO was deployed on the DLR-Falcon (Deutsches Zentrum für Luft- und Raumfahrt aircraft and tested during the ASTAR 2007 campaign (Arctic Study of Tropospheric Aerosol, Clouds and Radiation that took place at Svalbard (78° N in spring 2007. Our main objectives during this campaign were to test the instrument, and to perform spectral and profile retrievals of tropospheric trace gases, with particular interest on investigating the distribution of halogen compounds (e.g., BrO during the so-called ozone depletion events (ODEs. In the present work, a new method for the retrieval of vertical profiles of tropospheric trace gases from tropospheric DOAS limb observations is presented. Major challenges arise from modeling the radiative transfer in an aerosol and cloud particle loaded atmosphere, and from overcoming the lack of a priori knowledge of the targeted trace gas vertical distribution (e.g., unknown tropospheric BrO vertical distribution. Here, those challenges are tackled by a mathematical inversion of tropospheric trace gas profiles using a regularization approach constrained by a retrieved vertical profile of the aerosols extinction coefficient EM. The validity and limitations of the algorithm are tested with in situ measured EM, and with an absorber of known vertical profile (O4. The method is then used for retrieving vertical profiles of tropospheric BrO. Results indicate that, for aircraft ascent/descent observations, the limit for the BrO detection is roughly 1.5 pptv (pmol mol−1, and the BrO profiles inferred from the boundary layer up to the upper troposphere and lower stratosphere have around 10 degrees of freedom. For the ASTAR 2007 deployments during ODEs, the retrieved BrO vertical profiles consistently indicate high BrO mixing ratios (∼15 pptv within the boundary layer, low BrO mixing ratios (≤1.5 pptv in the free

  10. Obstruction detection comparison of small-footprint full-waveform and discrete return lidar (United States)

    Magruder, Lori A.; Neuenschwander, Amy L.; Marmillion, Scott P.; Tweddale, Scott A.


    Laser Radar, also referred to as lidar, has become widely available and is an established contributor to the military and intelligence community by providing precise elevation data using 3-dimensional measurements. The utilization of customized algorithms designed for lidar data exploitation provides the capability to determine corridors or gaps in areas of vegetation cover. These capabilities lend themselves as geospatial tools for mobility applications and tactical planning. This effort uses elevations derived from small-footprint (airborne) lidar surveys to create accurate surface models and corresponding canopy characterization maps. The canopy height models are based on elevation voxels above ground level and are used as input into a tree finding algorithm. Corridors under the canopy are then predicted using the obstruction identification technique and neighboring point characteristics. Path determination can also be performed using the obstruction maps and a modified A-star algorithm. A lidar survey over Camp Shelby, MS was chosen as the test case for the obstruction detection utilities as it provides fairly dense vegetation cover and interesting topographic features. The survey was completed using both a full-waveform lidar and a discrete return system which offers a coincident comparison of the obstruction methodology for differing data types. It is determined that the fullwaveform data provides a more complete and accurate assessment of the surface, the canopy and potential obstruction detection than the discrete return system.

  11. Snapshots in X-ray binary evolution: Using Hα Emitters and post-starburst galaxies to study the age-dependence of XRB populations (United States)

    Basu-Zych, Antara; Hornschemeier, Ann; Fragkos, Anastasios; Lehmer, Bret; Zezas, Andreas; Yukita, Mihoko; Tzanavaris, Panayiotis


    The X-ray emission in galaxies, due to X-ray binaries (XRBs), appears to depend on global galaxy properties such as stellar mass (M*), star formation rate (SFR), metallicity, and stellar age. This poster will present unique galaxy populations with well-defined stellar ages to test current relations and models. Specifically, Hα emitters (HAEs), which are nearby analogs of galaxies in the early universe, trace how XRBs form and evolve in young, metal-poor environments. We find that HAEs have lower X-ray luminosities per SFR and metallicity compared to other normal galaxies. At such young ages ( 500 Å), probe the XRB population related to stellar ages of 0.1-1 Gyr. At these ages, the donor star is expected to be an A-star whose mass is ~2 M⊙ and similar to that of the compact object, which may potentially lead to high mass transfer rates and high X-ray luminosities. Together, these samples offer important constraints for the evolution of XRBs with stellar age.

  12. Influence of cultivar on the content of selected minerals in red beet roots (Beta vulgaris L.

    Directory of Open Access Journals (Sweden)

    Nizioł-Łukaszewska Zofia


    Full Text Available Beetroot is a vegetable that accumulate heavy metals. This is largely dependent on the cultivar, methods and growing conditions. The aim of the study was to determine the composition of elements in the roots of 15 cultivars of red beet. The analysis assessed the content of macroelements (Na, P and heavy metals (Cd, Cr, Mn, Zn. Most soils of the Lesser Poland region are exposed to the impact of industrial and transportation pollution. The soils of this region are characterized by strong acidification as well as natural or increased heavy metal content. The experiment was set up at the experimental field of the Department of Vegetable and Medicinal Plants of the University of Agriculture in Krakow, in 2009-2010. On the basis of the performed analysis, ‘Opolski’ was chosen as the cultivar that was characterized by a high content of macroelements and lower ability to accumulate heavy metals than the other tested cultivars. The lowest ability to accumulate heavy metals (Cd and Cr was found in the cases of cultivars with cylindrical root shapes, such as Rywal or Opolski. One can indicate such cultivars as Astar F1 or Nabab F1 as cultivars recommended for cultivation in ecologically threatened areas.

  13. A DTM-based path planning method for planetary rovers (United States)

    Morlans, R.; Liegeois, A.


    Algorithms that automatically find the feasible routes for a mobile robot in a partially known three dimensional environment are proposed. The system is especially devised keeping in mind a planetary rover mission. Starting with a low resolution digital terrain model (DTM), relevant points (saddle points) of the relief are first automatically extracted and a connected network of traversable lines is constructed in a 'structuralist' way: the starting points for the algorithm are the saddle points; the criteria, taking into account the smoothness and the slope of the constructed line, are used to compute the network iteratively. Lines and points of this network are used as arcs and nodes to create a search graph on which an A(star) algorithm is applied to find the optimal route minimizing traveling time or energy while insuring safety. This edge constrained solution serves to initiate shortcut finding laws allowing the vehicle to cross the regions bounded by the lines of the network. The motion across each region is characterized by a cost function computed from the elevation data: mean slope roughness. Examples using a 1000 by 1000 pixel DTM are given.

  14. On an efficient and effective Intelligent Transportation System (ITS) using field and simulation data (United States)

    Ekedebe, Nnanna; Chen, Zhijiang; Xu, Guobin; Lu, Chao; Yu, Wei


    Intelligent transportation system (ITS) applications are expected to provide a more efficient, effective, reliable, and safe driving experience, which can minimize road traffic congestion resulting in a better traffic flow management. To efficiently manage traffic flows, in this paper, we compare the effectiveness of two well-known vehicle routing algorithms: the Dijkstra's shortest path algorithm and the A* (Astar) algorithm in terms of the total travel time and the travel distance. To this end, we built a generic ITS test-bed and created several real-world driving scenarios using field and simulation data to evaluate the performance of these two routing algorithms. The dataset used in our simulation is six weeks traffic volume data from 08/01/2012 to 09/27/2012 in the Maryland (MD)/Washington DC and Virginia (VA) area. Our simulation data shows that an increase in network size results in scalability problems as the efficiency and effectiveness of these algorithms diminishes in larger road networks with greater traffic volume densities, flow rates, and congested conditions. In addition, the imprecision of the road network increases as the network size and the traffic volume density increases. Our study shows that the ability of these vehicular routing algorithms to adaptively route traffic depends on the size and type of road networks, and the current roadway conditions.

  15. Twisting all the way: from algebras to morphisms and connections

    CERN Document Server

    Aschieri, Paolo


    Given a Hopf algebra H and an algebra A that is an H-module algebra we consider the category of left H-modules and A-bimodules, where morphisms are just right A-linear maps (not necessarily H-equivariant). Given a twist F of H we then quantize (deform) H to H^F, A to A_\\star and correspondingly the category of left H-modules and A-bimodules to the category of left H^F-modules and A_\\star-bimodules. If we consider a quasitriangular Hopf algebra H, a quasi-commutative algebra A and quasi-commutative A-bimodules, we can further construct and study tensor products over A of modules and of morphisms, and their twist quantization. This study leads to the definition of arbitrary (i.e., not necessarily H-equivariant) connections on quasi-commutative A-bimodules, to extend these connections to tensor product modules and to quantize them to A_\\star-bimodule connections. Their curvatures and those on tensor product modules are also determined.

  16. BEER Analysis of Kepler and CoRoT Light Curves. IV. Discovery of Four New Low-mass White-Dwarf Companions in the Kepler Data (United States)

    Faigler, S.; Kull, I.; Mazeh, T.; Kiefer, F.; Latham, D. W.; Bloemen, S.


    We report the discovery of four short-period eclipsing systems in the Kepler light curves, consisting of an A-star primary and a low-mass white dwarf (WD) secondary (dA+WD)—KIC 4169521, KOI-3818, KIC 2851474, and KIC 9285587. The systems show BEaming, Ellipsoidal and Reflection (BEER) phase modulations together with primary and secondary eclipses. These add to the 6 Kepler and 18 WASP short-period eclipsing dA+WD binaries that were previously known. The light curves, together with follow-up spectroscopic observations, allow us to derive the masses, radii, and effective temperatures of the two components of the four systems. The orbital periods, of 1.17-3.82 days, and WD masses, of 0.19-0.22 M⊙, are similar to those of the previously known systems. The WD radii of KOI-3818, KIC 2851474, and KIC 9285587 are 0.026, 0.035, and 0.026 R⊙, respectively, the smallest WD radii derived so far for short-period eclipsing dA+WD binaries. These three binaries extend the previously known population to older systems with cooler and smaller WD secondaries. KOI-3818 displays evidence for a fast-rotating primary and a minute but significant eccentricity, ˜1.5 × 10-3. These features are probably the outcome of the mass-transfer process.

  17. Combining High-Contrast Imaging with Doppler Radial Velocity: a Survey of Subgiant Stars that Exhibit Long-term Linear Trends (United States)

    Crepp, Justin R.; Johnson, J. A.


    We are commencing a high-contrast imaging survey at Keck that will target several dozen nearby subgiant stars that show evidence for the existence of a distant companion, as is indicated by a long-term, linear radial velocity (RV) trend. The goal of the survey is to place very tight constraints on the mass and orbit of the body responsible for accelerating each star. Our targets are massive, former A-stars and 28% have a known exoplanet. The typical time baseline for Doppler measurements is 3+ years and a number of targets have minimum periods of 12 years. By combining complementary detection techniques, we will be able to determine with high statistical confidence whether the (outer-most) companion is stellar or substellar in nature for most of the sample. This "inside-out" approach will provide a measure of the occurrence rate of multi-planet systems and brown dwarfs around massive stars. In this poster, we present further motivation on the topic, including several representative RV curves and the anticipated mass, inclination, and semi-major axis constraints imposed by imaging and RV.

  18. Integrated Flight Path Planning System and Flight Control System for Unmanned Helicopters

    Directory of Open Access Journals (Sweden)

    Yu-Hsiang Lin


    Full Text Available This paper focuses on the design of an integrated navigation and guidance system for unmanned helicopters. The integrated navigation system comprises two systems: the Flight Path Planning System (FPPS and the Flight Control System (FCS. The FPPS finds the shortest flight path by the A-Star (A* algorithm in an adaptive manner for different flight conditions, and the FPPS can add a forbidden zone to stop the unmanned helicopter from crossing over into dangerous areas. In this paper, the FPPS computation time is reduced by the multi-resolution scheme, and the flight path quality is improved by the path smoothing methods. Meanwhile, the FCS includes the fuzzy inference systems (FISs based on the fuzzy logic. By using expert knowledge and experience to train the FIS, the controller can operate the unmanned helicopter without dynamic models. The integrated system of the FPPS and the FCS is aimed at providing navigation and guidance to the mission destination and it is implemented by coupling the flight simulation software, X-Plane, and the computing software, MATLAB. Simulations are performed and shown in real time three-dimensional animations. Finally, the integrated system is demonstrated to work successfully in controlling the unmanned helicopter to operate in various terrains of a digital elevation model (DEM.

  19. Monte Carlo modeling of ion beam induced secondary electrons

    Energy Technology Data Exchange (ETDEWEB)

    Huh, U., E-mail: [Biochemistry & Cellular & Molecular Biology, University of Tennessee, Knoxville, TN 37996-0840 (United States); Cho, W. [Electrical and Computer Engineering, University of Tennessee, Knoxville, TN 37996-2100 (United States); Joy, D.C. [Biochemistry & Cellular & Molecular Biology, University of Tennessee, Knoxville, TN 37996-0840 (United States); Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)


    Ion induced secondary electrons (iSE) can produce high-resolution images ranging from a few eV to 100 keV over a wide range of materials. The interpretation of such images requires knowledge of the secondary electron yields (iSE δ) for each of the elements and materials present and as a function of the incident beam energy. Experimental data for helium ions are currently limited to 40 elements and six compounds while other ions are not well represented. To overcome this limitation, we propose a simple procedure based on the comprehensive work of Berger et al. Here we show that between the energy range of 10–100 keV the Berger et al. data for elements and compounds can be accurately represented by a single universal curve. The agreement between the limited experimental data that is available and the predictive model is good, and has been found to provide reliable yield data for a wide range of elements and compounds. - Highlights: • The Universal ASTAR Yield Curve was derived from data recently published by NIST. • IONiSE incorporated with the Curve will predict iSE yield for elements and compounds. • This approach can also handle other ion beams by changing basic scattering profile.

  20. The properties of thermostabilised G protein-coupled receptors (StaRs) and their use in drug discovery. (United States)

    Robertson, Nathan; Jazayeri, Ali; Errey, James; Baig, Asma; Hurrell, Edward; Zhukov, Andrei; Langmead, Christopher J; Weir, Malcolm; Marshall, Fiona H


    G protein-coupled receptors (GPCRs) are one of the most important target classes in the central nervous system (CNS) drug discovery, however the fact they are integral membrane proteins and are unstable when purified out of the cell precludes them from a wide range of structural and biophysical techniques that are used for soluble proteins. In this study we demonstrate how protein engineering methods can be used to identify mutations which can both increase the thermostability of receptors, when purified in detergent, as well as biasing the receptor towards a specific physiologically relevant conformational state. We demonstrate this method for the adenosine A(2A) receptor and muscarinic M(1) receptor. The resultant stabilised receptors (known as StaRs) have a pharmacological profile consistent with the inverse agonist conformation. The stabilised receptors can be purified in large quantities, whilst retaining correct folding, thus generating reagents suitable for a broad range of structural and biophysical studies. In the case of the A(2A)-StaR we demonstrate that surface plasmon resonance can be used to profile the association and dissociation rates of a range of antagonists, a technique that can be used to improve the in vivo efficacy of receptor antagonists. Copyright © 2010 Elsevier Ltd. All rights reserved.

  1. Cluster analysis of the impact of air back-trajectories on aerosol optical properties at Hornsund, Spitsbergen

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    A. Rozwadowska


    Full Text Available In this paper, spectra of aerosol optical thickness from the AERONET (AErosol RObotic NETwork station at Hornsund in the southern part of Spitsbergen were employed to study the impact of air mass history on aerosol optical thickness for wavelength λ=500 nm – AOT(500 – and the Ångström exponent. Backward trajectories computed, using the NOAA HYSPLIT model, were used to trace air history. It was found that in spring, the changes in AOT values over the Hornsund station were strongly influenced by air mass trajectories 8 days or longer in duration, arriving both in the free troposphere and at an altitude of 1 km above sea level. Nevertheless, free tropospheric advection was dominant. AOT variability in summer was best explained by the local direction and speed of advection (1-day trajectories and was dominated by the effectiveness of cleansing processes. During the ASTAR 2007 campaign, the aerosols near Hornsund displayed low AOT values ranging from 0.06 to 0.09, which is lower than the mean AOT(500 for spring seasons from 2005 to 2007 (0.110±0.007; mean ± standard deviation of mean. 9 April 2007 with AOT(500=0.147 was exceptional. The back-trajectories belonged to clusters with low and average cluster mean AOT. Apart from the maximum AOT of 9 April 2007, the observed AOT values were close to or lower than the means for the clusters to which they belonged.


    Energy Technology Data Exchange (ETDEWEB)

    Donaldson, J. K. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Lebreton, J.; Augereau, J.-C. [UJF - Grenoble 1/CNRS-INSU, Institut de Planetologie et d' Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041 (France); Roberge, A. [Exoplanets and Stellar Astrophysics Laboratory, NASA Goddard Space Flight Center, Code 667, Greenbelt, MD 20771 (United States); Krivov, A. V., E-mail: [Astrophysikalishes Institut, Friedrich-Schiller-Universitaet Jena, Schillergaesschen 2-3, D-07745 Jena (Germany)


    HD 32297 is a young A-star ({approx}30 Myr) 112 pc away with a bright edge-on debris disk that has been resolved in scattered light. We observed the HD 32297 debris disk in the far-infrared and sub-millimeter with the Herschel Space Observatory PACS and SPIRE instruments, populating the spectral energy distribution (SED) from 63 to 500 {mu}m. We aimed to determine the composition of dust grains in the HD 32297 disk through SED modeling, using geometrical constraints from the resolved imaging to break the degeneracies inherent in SED modeling. We found the best fitting SED model has two components: an outer ring centered around 110 AU, seen in the scattered light images, and an inner disk near the habitable zone of the star. The outer disk appears to be composed of grains >2 {mu}m consisting of silicates, carbonaceous material, and water ice with an abundance ratio of 1:2:3 respectively and 90% porosity. These grains appear consistent with cometary grains, implying the underlying planetesimal population is dominated by comet-like bodies. We also discuss the 3.7{sigma} detection of [C II] emission at 158 {mu}m with the Herschel PACS instrument, making HD 32297 one of only a handful of debris disks with circumstellar gas detected.

  3. Non-Bloom syndrome-associated partial and total loss-of-function variants of BLM helicase. (United States)

    Mirzaei, Hamed; Schmidt, Kristina H


    Bloom syndrome (BS) is an autosomal recessive disorder caused by mutations in the RecQ-like DNA helicase BLM, which functions in the maintenance of genome stability. Using a humanized model of Saccharomyces cerevisiae that expresses a chimera of the N terminus of yeast Sgs1 and the C terminus of human BLM from the chromosomal SGS1 locus, we have functionally evaluated 27 BLM alleles that are not currently known to be associated with BS. We identified nine alleles with impaired function when assessed for hypersensitivity to the DNA-damaging agent hydroxyurea (HU). Six of these alleles (P690L, R717T, W803R, Y811C, F857L, G972V) caused sensitivity to HU that was comparable to known BS-associated or helicase-dead alleles, suggesting that they may cause BS and, in the heterozygous state, act as risk factors for cancerogenesis. We also identified three alleles (R791C, P868L, G1120R) that caused intermediate sensitivity to HU; although unlikely to cause BS, these partial loss-of-function alleles may increase risk for cancers or other BS-associated complications if a person is homozygous or compound heterozygous for these alleles or if they carry a known BS-associated allele.

  4. A Hybrid of Modified PSO and Local Search on a Multi-Robot Search System

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    Mohammad Naim Rastgoo


    Full Text Available Particle swarm optimization (PSO, a new population-based algorithm, has recently been used on multi-robot systems. Although this algorithm is applied to solve many optimization problems as well as multi-robot systems, it has some drawbacks when it is applied on multi-robot search systems to find a target in a search space containing big static obstacles. One of these defects is premature convergence. This means that one of the properties of basic PSO is that when particles are spread in a search space, as time increases they tend to converge in a small area. This shortcoming is also evident on a multi-robot search system, particularly when there are big static obstacles in the search space that prevent the robots from finding the target easily; therefore, as time increases, based on this property they converge to a small area that may not contain the target and become entrapped in that area. Another shortcoming is that basic PSO cannot guarantee the global convergence of the algorithm. In other words, initially particles explore different areas, but in some cases they are not good at exploiting promising areas, which will increase the search time. This study proposes a method based on the particle swarm optimization (PSO technique on a multi-robot system to find a target in a search space containing big static obstacles. This method is not only able to overcome the premature convergence problem but also establishes an efficient balance between exploration and exploitation and guarantees global convergence, reducing the search time by combining with a local search method, such as A-star. To validate the effectiveness and usefulness of algorithms, a simulation environment has been developed for conducting simulation-based experiments in different scenarios and for reporting experimental results. These experimental results have demonstrated that the proposed method is able to overcome the premature convergence problem and guarantee global

  5. MOST Ultra-high Precision Photometry of delta Capricorni - the Nearest & Brightest Eclipsing Binary with a Pulsating Component: An Important Asteroseismic Laboratory for A-type Stars (United States)

    Guinan, Edward F.; Engle, S. G.; Prsa, A.; Wasatonic, R. P.; Fekel, F. C.; Williamson, M.; Matthews, J.; Kolenberg, K.; Breger, M.


    We report on over 3 weeks of continuous ultra-high precision photometry of the bright, nearby, detached (P= 1.02 day; A8m + dK7) eclipsing binary delta Cap. The observations were carried out with the Canadian Micro-satellite MOST during Aug/Sept. 2010. Extensive contemporaneous spectroscopy was secured with the 2-m TSU Automatic Spectroscopic Telescope (AST) and complementary BVR photometry was obtained with ground based telescopes. Delta Cap is an astrophysically important star because it is the nearest and brightest eclipsing binary with a bright pulsating component that can be used (with astereoseismic analyses) to test and calibrate stellar interior and pulsation models. When a pulsating star is a member of an eclipsing binary, the analyses of the it's light and radial velocity observations yield the precise determination of all fundamental orbital and physical properties for the component stars. Moreover the MOST observations during the primary eclipses are a powerful tool for mode identification as portions of the pulsating A-star are blocked from view. Also because delta Cap is nearby and has a reliable parallax (pi (Hipp) = 84.27+/- 0.19 mas), the component stars’ luminosities and temperatures are also directly determinable. In addition to its well behaved 1.02-d periodic light variations arising from the eclipses and tidal effects, the MOST light curves clearly show small ( 0.01-0.02 mag) complex light variations. We present the results of the analysis the eclipsing binary light and radial velocity curves using PHOEBE. Also presented are the initial asteroseismic analyses of the A8m component based on the MOST photometry and contemporaneous radial velocity observations. Preliminary models indicate this star is a hybrid gamma Dor-delta Scuti pulsator. We gratefully acknowledge the support from NASA/MOST Grant NNX10AI85G and NSF/RUI Grant AST-05-07542. We also wholeheartedly thank the MOST team for securing and reducing the photometry.

  6. Chemical evolution with rotating massive star yields I. The solar neighborhood and the s-process elements (United States)

    Prantzos, N.; Abia, C.; Limongi, M.; Chieffi, A.; Cristallo, S.


    We present a comprehensive study of the abundance evolution of the elements from H to U in the Milky Way halo and local disk. We use a consistent chemical evolution model, metallicity dependent isotopic yields from low and intermediate mass stars and yields from massive stars which include, for the first time, the combined effect of metallicity, mass loss and rotation for a large grid of stellar masses and for all stages of stellar evolution. The yields of massive stars are weighted by a metallicity dependent function of the rotational velocities, constrained by observations as to obtain a primary-like 14N behavior at low metallicity and to avoid overproduction of s-elements at intermediate metallicities. We show that the solar system isotopic composition can be reproduced to better than a factor of two for isotopes up to the Fe-peak, and at the 10% level for most pure s-isotopes, both light ones (resulting from the weak s-process in rotating massive stars) and the heavy ones (resulting from the main s-process in low and intermediate mass stars). We conclude that the light element primary process (LEPP), invoked to explain the apparent abundance deficiency of the s-elements with Astars - as a result of the contribution of rotating massive stars at sub-solar metallicities. We find that those stars produce primary F and dominate its solar abundance and we confirm their role in the observed primary behavior of N. In contrast, we show that their action is insufficient to explain the small observed values of ^{12}C/^{13}C in halo red giants, which is rather due to internal processes in those stars.

  7. What is Enhancing the Tidal Disruption Rate of Stars in Post-Starburst Galaxies? (United States)

    Arcavi, Iair


    The search for the tidal disruption of stars by supermassive black holes (tidal disruption events; TDEs) is now yielding exciting results. Recently, we tied several events together into a coherent class of outbursts. This picture offers a surprising new insight: TDEs show a strong (200x) preference for post-starburst galaxies. Why is this? As likely post-merger galaxies, they could harbor a binary black hole in their center, which is expected to increase the rate of TDEs, but only at certain ages after the merger and for certain merger mass ratios. Alternatively, a disturbed central potential or nuclear gas reservoirs may be affecting stellar orbits in the core of the galaxy. Finally, a nuclear over-abundance of A stars (which dominate ground-based galaxy-integrated spectra), evolving to giants, could increase the global cross section for tidal disruption. HST spatial resolution and low surface brightness sensitivity allows us to test each of these options for four post-starburst TDE host galaxies. We will measure post-merger tidal tails, age-date the starburst using individual star cluster colors, map the luminosity profile of the inner 100pc to test for asphericity or double nuclei, and localize the weak line emission and A-star population seen in our galaxy-integrated spectra. We will also perform bulge-disk decompositions to estimate the mass of the central black hole, a crucial test of TDE emission models. Our group has successfully carried out HST analyses of the star cluster populations, tidal tails, and core surface brightness profiles of (non-TDE-host) post-starburst galaxies, a sample which will serve as a control for the observations proposed here.

  8. Interlaboratory comparison of traceable atomic force microscope pitch measurements (United States)

    Dixson, Ronald; Chernoff, Donald A.; Wang, Shihua; Vorburger, Theodore V.; Tan, Siew Leng; Orji, Ndubuisi G.; Fu, Joseph


    The National Institute of Standards and Technology (NIST), Advanced Surface Microscopy (ASM), and the National Metrology Centre (NMC) of the Agency for Science, Technology, and Research (A*STAR) in Singapore have completed a three-way interlaboratory comparison of traceable pitch measurements using atomic force microscopy (AFM). The specimen being used for this comparison is provided by ASM and consists of SiO2 lines having a 70 nm pitch patterned on a silicon substrate. NIST has a multifaceted program in atomic force microscope (AFM) dimensional metrology. One component of this effort is a custom in-house metrology AFM, called the calibrated AFM (C-AFM). The NIST C-AFM has displacement metrology for all three axes traceable to the 633 nm wavelength of the iodine-stabilized He-Ne laser - a recommended wavelength for realization of the SI (Système International d'Unités, or International System of Units) meter. NIST used the C-AFM to participate in this comparison. ASM used a commercially available AFM with an open-loop scanner, calibrated by a 144 nm pitch transfer standard. In a prior collaboration with Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute, ASM's transfer standard was calibrated using PTB's traceable optical diffractometry instrument. Thus, ASM's measurements are also traceable to the SI meter. NMC/A*STAR used a large scanning range metrological atomic force microscope (LRM-AFM). The LRM-AFM integrates an AFM scanning head into a nano-stage equipped with three built-in He-Ne laser interferometers so that its measurement related to the motion on all three axes is directly traceable to the SI meter. The measurements for this interlaboratory comparison have been completed and the results are in agreement within their expanded uncertainties and at the level of a few parts in 104.

  9. Implementing the Mars Science Laboratory Terminal Descent Sensor Field Test Campaign (United States)

    Montgomery, James F.; Bodie, James H.; Brown, Joseph D.; Chen, Allen; Chen, Curtis W.; Essmiller, John C.; Fisher, Charles D.; Goldberg, Hannah R.; Lee, Steven W.; Shaffer, Scott J.


    The Mars Science Laboratory (MSL) will deliver a 900 kg rover to the surface of Mars in August 2012. MSL will utilize a new pulse-Doppler landing radar, the Terminal Descent Sensor (TDS). The TDS employs six narrow-beam antennas to provide unprecedented slant range and velocity performance at Mars to enable soft touchdown of the MSL rover using a unique sky crane Entry, De-scent, and Landing (EDL) technique. Prior to use on MSL, the TDS was put through a rigorous verification and validation (V&V) process. A key element of this V&V was operating the TDS over a series of field tests, using flight-like profiles expected during the descent and landing of MSL over Mars-like terrain on Earth. Limits of TDS performance were characterized with additional testing meant to stress operational modes outside of the expected EDL flight profiles. The flight envelope over which the TDS must operate on Mars encompasses such a large range of altitudes and velocities that a variety of venues were neces-sary to cover the test space. These venues included an F/A-18 high performance aircraft, a Eurocopter AS350 AStar helicopter and 100-meter tall Echo Towers at the China Lake Naval Air Warfare Center. Testing was carried out over a five year period from July 2006 to June 2011. TDS performance was shown, in gen-eral, to be excellent over all venues. This paper describes the planning, design, and implementation of the field test campaign plus results and lessons learned.

  10. Multimode Vibrational Wave Packet Dynamics of Strong-Field-Ionized Methyl Iodide Probed by Femtosecond XUV Absorption Spectroscopy (United States)

    Loh, Zhi-Heng; Wei, Zhengrong; Li, Jialin


    Studies of vibrational wave packets (VWPs) created on the neutral electronic ground-state by intense laser fields have identified R -selective depletion (RSD) as the dominant mechanism for their generation. Another mechanism that is proposed to give rise to VWPs, bond softening (BS), remains hitherto unobserved. Here, we employ femtosecond XUV absorption spectroscopy to investigate the VWP dynamics of CH3 I induced by intense laser fields. Analysis of the first-moment time traces computed about the neutral depletion region reveals both the fundamental and the hot bands of the C-I stretch mode. The initial oscillation phases of these vibrations distinguishes the contributions of RSD and BS to the generation of the VWP in the neutral species. The relative oscillation amplitudes that are associated with the two phases suggest that the C-I VWP is generated predominantly by BS. In the case of the CH3 I+ X 2E3 / 2 ion state, VWP motion along the C-I stretch mode is dominant over the CH3 umbrella mode. Moreover, the amplitudes of the VWPs are only 1 pm (C-I distance) and 1° (H-C-I bond angle). The ability to resolve such VWP dynamics points to the exquisite sensitivity of femtosecond XUV absorption spectroscopy to structural changes. This work is supported by a NTU start-up Grant, the A*Star SERC PSF (122-PSF-0011), the Ministry of Education AcRF (MOE2014-T2-2-052), and the award of a Nanyang Assistant Professorship to Z.-H.L.

  11. Microphysical and radiative characterization of a subvisible midlevel Arctic ice cloud by airborne observations – a case study

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    A. Lampert


    Full Text Available During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR campaign, which was conducted in March and April 2007, an optically thin ice cloud was observed south of Svalbard at around 3 km altitude. The microphysical and radiative properties of this particular subvisible midlevel cloud were investigated with complementary remote sensing and in situ instruments. Collocated airborne lidar remote sensing and spectral solar radiation measurements were performed at a flight altitude of 2300 m below the cloud base. Under almost stationary atmospheric conditions, the same subvisible midlevel cloud was probed with various in situ sensors roughly 30 min later.

    From individual ice crystal samples detected with the Cloud Particle Imager and the ensemble of particles measured with the Polar Nephelometer, microphysical properties were retrieved with a bi-modal inversion algorithm. The best agreement with the measurements was obtained for small ice spheres and deeply rough hexagonal ice crystals. Furthermore, the single-scattering albedo, the scattering phase function as well as the volume extinction coefficient and the effective diameter of the crystal population were determined. A lidar ratio of 21(±6 sr was deduced by three independent methods. These parameters in conjunction with the cloud optical thickness obtained from the lidar measurements were used to compute spectral and broadband radiances and irradiances with a radiative transfer code. The simulated results agreed with the observed spectral downwelling radiance within the range given by the measurement uncertainty. Furthermore, the broadband radiative simulations estimated a net (solar plus thermal infrared radiative forcing of the subvisible midlevel ice cloud of −0.4 W m−2 (−3.2 W m−2 in the solar and +2.8 W m−2 in the thermal infrared wavelength range.

  12. Analysis of Wilhelm Ostwald's "Colour Organ" with Raman microspectroscopy (United States)

    Bridarolli, Alexandra; Atak, Sefkan; Herm, Christoph


    The "Scientific Colour Organ" is a collection of 680 pigment powders, created by the chemist Wilhelm Ostwald in 1925 as a means to represent his colour system. Today, it remains a leading part of colour theory. Analysis of these materials was undertaken to understand how the colour system was realised and to gain indications for preservation of the collection to which it belongs. Dispersive Raman microspectroscopy was applied directly to the powders, as well as using alternative techniques to suppress fluorescence. Barium sulphate was detected in all of the samples with one exception. Portable X-ray fluorescence revealed that this compound was a constituent of lithopone pigment. Raman spectroscopy furthermore revealed synthetic ultramarine (C.I. PB 29) as well as six different synthetic organic pigments and dyes (C.I. PY3; C.I. PO5; C.I. PR81:1; C.I. PV2 and two different triarylmethane dyes). Thin-layer chromatography was applied to determine the exact combination of dyes causing the gradual change in colour of each powder compared to the adjacent samples. With the exception of triarylmethane, the synthetic organic dyes could be identified with Raman spectroscopy directly on the chromatographic plate. The efficiency of thin-layer chromatography combined with Raman spectroscopy for identification of organic pigments could thus be shown. X-ray fluorescence indicated the presence of tungsten-molybdenum lakes in some samples. Comparison of the analytical results to information published by Oswald in 1917 showed that he switched to more light-stable synthetic organic pigments used for his "Scientific Colour Organ".

  13. Infant sleep and its relation with cognition and growth: a narrative review

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    Tham EK


    Full Text Available Elaine KH Tham,1 Nora Schneider,2 Birit FP Broekman1 1Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR, Singapore, Singapore; 2Nestec Ltd., Nestlé Research Center, Lausanne, Switzerland Objective: Infant sleep development is a highly dynamic process occurring in parallel to and in interaction with cognitive and physical growth. This narrative review aims to summarize and discuss recent literature and provide an overview of the relation between infant sleep and cognitive development as well as physical growth.Methods: We conducted online literature search using MEDLINE, Embase, and Cochrane Library databases. We considered original research on humans published in the English language from January 2005 to December 2015. Search terms included “sleep” AND “infant” AND “cognition” OR “memory” OR “executive functioning”, OR “growth” OR “obesity” OR “growth hormone” OR “stunting”, and combinations thereof.Results: Ten studies on infant sleep and cognition were included in this review. Overall, findings indicated a positive association between sleep, memory, language, executive function, and overall cognitive development in typically developing infants and young children. An additional 20 studies support the positive role of infant sleep in physical growth, with the current literature focusing largely on weight gain and obesity rather than healthy growth. Existing evidence in both the domains is mainly based on cross-sectional designs, on association studies, and on parental reports. In contrast, there were limited studies on longitudinal sleep trajectories and intervention effects, or studies have not used more objective sleep measures such as actigraphy and polysomnography.Conclusion: The reviewed studies support a critical and positive role of infant sleep in cognition and physical growth. Future studies should consider key environmental and parental confounders

  14. The final fate of planetary systems (United States)

    Gaensicke, Boris


    The discovery of the first extra-solar planet around a main-sequence star in 1995 has changed the way we think about the Universe: our solar system is not unique. Twenty years later, we know that planetary systems are ubiquitous, orbit stars spanning a wide range in mass, and form in an astonishing variety of architectures. Yet, one fascinating aspect of planetary systems has received relatively little attention so far: their ultimate fate.Most planet hosts will eventually evolve into white dwarfs, Earth-sized stellar embers, and the outer parts of their planetary systems (in the solar system, Mars and beyond) can survive largely intact for billions of years. While scattered and tidally disrupted planetesimals are directly detected at a small number of white dwarfs in the form infrared excess, the most powerful probe for detecting evolved planetary systems is metal pollution of the otherwise pristine H/He atmospheres.I will present the results of a multi-cycle HST survey that has obtained COS observations of 136 white dwarfs. These ultraviolet spectra are exquisitely sensitive to the presence of metals contaminating the white atmosphere. Our sophisticated model atmosphere analysis demonstrates that at least 27% of all targets are currently accreting planetary debris, and an additional 29% have very likely done so in the past. These numbers suggest that planet formation around A-stars (the dominant progenitors of today's white dwarf population) is similarly efficient as around FGK stars.In addition to post-main sequence planetary system demographics, spectroscopy of the debris-polluted white dwarf atmospheres provides a direct window into the bulk composition of exo-planetesimals, analogous to the way we use of meteorites to determine solar-system abundances. Our ultraviolet spectroscopy is particularly sensitive to the detection of Si, a dominant rock-forming species, and we identify up to ten additional volatile and refractory elements in the most strongly

  15. beta Phase Growth and Precipitation in the 5xxx Series Aluminum Alloy System (United States)

    Scotto D'Antuono, Daniel

    The 5xxx series aluminum alloys are commonly used for structural applications due to their high strength to weight ratio, corrosion resistance, and weldability. This material system is a non-heat treatable aluminum and derives its strength from a super saturation of magnesium (3%>), and from cold rolling. While these materials have many admiral properties, they can undergo a process known as sensitization when exposed to elevated temperatures (50-280°C) for extended periods of time. During this process, magnesium segregates toward the grain boundaries and forms the secondary precipitate β phase (Al3Mg2). When exposed to harsh environments such as sea water, a galvanic couple is formed between the Al matrix and the β phase precipitates. The precipitates become anodic to the matrix and preferentially dissolve leaving gaps along the boundary network, ultimately leading to stress corrosion cracking. While this problem has been known to occur for some time now, questions relating to nucleation sites, misorientation dependence, effect of prior strain, and preferred temperature regimes remain unanswered. The work contained in this thesis attempted to better understand the kinetics, growth, and misorientation dependence, of β phase precipitation using in situ transmission electron microscopy experiments which allowed for direct visualization of the precipitation process. Orientation imaging using a Nanomegas/ASTAR system (OIM in TEM) coupled with the in situ experiments, along with elemental STEM EELs mapping were used to better understand the diffusion of Mg and found low angle boundaries as potential sites for nucleation. The resulting STEM EELs experiments also showed that Mg is much more stable at the grain boundaries than previously thought. Concurrent bulk ex-situ studies were used to compare various heat treatments, as well as to failed in service material showing that the low temperature treatments yield the metastable β’ phase more readily than the

  16. Novos sedativos hipnóticos The newer sedative-hypnotics

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    Lucia Sukys-Claudino


    Full Text Available Nas últimas décadas houve um esforço para o desenvolvimento de hipnóticos mais seguros e eficazes. Zolpidem, zaleplona, zopiclona, eszopiclona (drogas-z e indiplona são moduladores do receptor GABA-A, os quais agem de forma seletiva na subunidade α1, exibindo, desta forma, mecanismos similares de ação, embora evidências recentes sugiram que a eszopiclona não seja tão seletiva para a subunidade α1 quanto o zolpidem. Ramelteon e tasimelteon são novos agentes crono-hipnóticos seletivos para os receptores de melatonina MT1 e MT2. Por outro lado, nos últimos anos, o consumo de drogas antidepressivas sedativas tem aumentado significativamente no tratamento da insônia. Como droga experimental, a eplivanserina tem sido testada como um potente agonista inverso do subtipo 5-HT2A da serotonina, com um uso potencial na dificuldade da manutenção do sono. Outro agente farmacológico para o tratamento da insônia é o almorexant, o qual apresenta um novo mecanismo de ação envolvendo antagonismo do sistema hipocretinérgico, desta forma levando à indução do sono. Finalmente, também discutiremos o potencial papel de outras drogas gabaérgicas no tratamento da insônia.There has been a search for more effective and safe hypnotic drugs in the last decades. Zolpidem, zaleplon, zopiclone, eszopiclone (the z-drugs and indiplon are GABA-A modulators which bind selectively α1 subunits, thus, exhibiting similar mechanisms of action, although recent evidence suggests that eszopiclone is not as selective for α1 subunit as zolpidem is. Ramelteon and tasimelteon are new chrono-hypnotic agents, selective for melatonin MT1 and MT2 receptors. On the other hand, the consumption of sedative antidepressant drugs is significantly increasing for the treatment of insomnia, in the last years. As an experimental drug, eplivanserin is being tested as a potent antagonist of serotonin 2-A receptors (ASTAR with a potential use in sleep maintenance difficulty

  17. Advanced Silicon Photonic Device Architectures for Optical Communications: Proposals and Demonstrations (United States)

    Sacher, Wesley David

    Photonic integrated circuits implemented on silicon (Si) hold the potential for densely integrated electro-optic and passive devices manufactured by the high-volume fabrication and sophisticated assembly processes used for complementary metal-oxide-semiconductor (CMOS) electronics. However, high index contrast Si photonics has a number of functional limitations. In this thesis, several devices are proposed, designed, and experimentally demonstrated to overcome challenges in the areas of resonant modulation, waveguide loss, fiber-to-chip coupling, and polarization control. The devices were fabricated using foundry services at IBM and A*STAR Institute of Microelectronics (IME). First, we describe coupling modulated microrings, in which the coupler between a microring and the bus waveguide is modulated. The device circumvents the modulation bandwidth vs. resonator linewidth trade-off of conventional intracavity modulated microrings. We demonstrate a Si coupling modulated microring with a small-signal modulation response free of the parasitic resonator linewidth limitations at frequencies up to about 6x the linewidth. Comparisons of eye diagrams show that coupling modulation achieved data rates > 2x the rate attainable with intracavity modulation. Second, we demonstrate a silicon nitride (Si3N4)-on-Si photonic platform with independent Si3N4 and Si waveguides and taper transitions to couple light between the layers. The platform combines the excellent passive waveguide properties of Si3N4 and the compatibility of Si waveguides with electro-optic devices. Within the platform, we propose and demonstrate dual-level, Si3N 4-on-Si, fiber-to-chip grating couplers that simultaneously have wide bandwidths and high coupling efficiencies. Conventional Si and Si3N 4 grating couplers suffer from a trade-off between bandwidth and coupling efficiency. The dual-level grating coupler achieved a peak coupling efficiency of -1.3 dB and a 1-dB bandwidth of 80 nm, a record for the

  18. Characterization of common carp transcriptome: sequencing, de novo assembly, annotation and comparative genomics.

    Directory of Open Access Journals (Sweden)

    Peifeng Ji

    Full Text Available BACKGROUND: Common carp (Cyprinus carpio is one of the most important aquaculture species of Cyprinidae with an annual global production of 3.4 million tons, accounting for nearly 14% of the freshwater aquaculture production in the world. Due to the economical and ecological importance of common carp, genomic data are eagerly needed for genetic improvement purpose. However, there is still no sufficient transcriptome data available. The objective of the project is to sequence transcriptome deeply and provide well-assembled transcriptome sequences to common carp research community. RESULT: Transcriptome sequencing of common carp was performed using Roche 454 platform. A total of 1,418,591 clean ESTs were collected and assembled into 36,811 cDNA contigs, with average length of 888 bp and N50 length of 1,002 bp. Annotation was performed and a total of 19,165 unique proteins were identified from assembled contigs. Gene ontology and KEGG analysis were performed and classified all contigs into functional categories for understanding gene functions and regulation pathways. Open Reading Frames (ORFs were detected from 29,869 (81.1% contigs with an average ORF length of 763 bp. From these contigs, 9,625 full-length cDNAs were identified with sequence length from 201 bp to 9,956 bp. Comparative analysis revealed that 27,693(75.2% contigs have significant similarity to zebrafish Refseq proteins, and 24,371(66.2%, 24,501(66.5% and 25,025(70.0% to teraodon, medaka and three-spined stickleback refseq proteins. A total of 2,064 microsatellites were initially identified from 1,730 contigs, and 1,639 unique sequences had sufficient flanking sequences on both sides for primer design. CONCLUSION: The transcriptome of common carp had been deep sequenced, de novo assembled and characterized, providing the valuable resource for better understanding of common carp genome. The transcriptome data will facilitate future functional studies on common carp genome, and

  19. Outbreak of Zika virus infection in Singapore: an epidemiological, entomological, virological, and clinical analysis. (United States)


    . The lineage showed little diversity and was distinct from other Asian lineages. The estimated most recent common ancestor of the outbreak lineage was from May, 2016. With the deployment of vector control and community engagement measures, the estimated reproductive number fell from 3·62 (95% CI 3·48-3·77) for July 31 to Sept 1, 2016, to 1·22 (95% CI 1·19-1·24) 4 weeks later (Sept 1 to Nov 24, 2016). The outbreak shows the ease with which Zika virus can be introduced and spread despite good baseline vector control. Disease surveillance, enhanced vector control, and community awareness and engagement helped to quickly curb further spread of the virus. These intensive measures might be useful for other countries facing the same threat. National Medical Research Council Singapore, Centre for Infectious Disease Epidemiology and Research, and A*STAR Biomedical Research Council. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Air Traffic Management Technology Demostration Phase 1 (ATD) Interval Management for Near-Term Operations Validation of Acceptability (IM-NOVA) Experiment (United States)

    Kibler, Jennifer L.; Wilson, Sara R.; Hubbs, Clay E.; Smail, James W.


    The Interval Management for Near-term Operations Validation of Acceptability (IM-NOVA) experiment was conducted at the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) in support of the NASA Airspace Systems Program's Air Traffic Management Technology Demonstration-1 (ATD-1). ATD-1 is intended to showcase an integrated set of technologies that provide an efficient arrival solution for managing aircraft using Next Generation Air Transportation System (NextGen) surveillance, navigation, procedures, and automation for both airborne and ground-based systems. The goal of the IMNOVA experiment was to assess if procedures outlined by the ATD-1 Concept of Operations were acceptable to and feasible for use by flight crews in a voice communications environment when used with a minimum set of Flight Deck-based Interval Management (FIM) equipment and a prototype crew interface. To investigate an integrated arrival solution using ground-based air traffic control tools and aircraft Automatic Dependent Surveillance-Broadcast (ADS-B) tools, the LaRC FIM system and the Traffic Management Advisor with Terminal Metering and Controller Managed Spacing tools developed at the NASA Ames Research Center (ARC) were integrated into LaRC's Air Traffic Operations Laboratory (ATOL). Data were collected from 10 crews of current 757/767 pilots asked to fly a high-fidelity, fixed-based simulator during scenarios conducted within an airspace environment modeled on the Dallas-Fort Worth (DFW) Terminal Radar Approach Control area. The aircraft simulator was equipped with the Airborne Spacing for Terminal Area Routes (ASTAR) algorithm and a FIM crew interface consisting of electronic flight bags and ADS-B guidance displays. Researchers used "pseudo-pilot" stations to control 24 simulated aircraft that provided multiple air traffic flows into the DFW International Airport, and recently retired DFW air traffic controllers served as confederate Center, Feeder, Final

  1. Which of Kepler's Stars Flare? (United States)

    Kohler, Susanna


    The habitability of distant exoplanets is dependent upon many factors one of which is the activity of their host stars. To learn about which stars are most likely to flare, a recent study examines tens of thousands of stellar flares observed by Kepler.Need for a Broader SampleArtists rendering of a flaring dwarf star. [NASAs Goddard Space Flight Center/S. Wiessinger]Most of our understanding of what causes a star to flare is based on observations of the only star near enough to examine in detail the Sun. But in learning from a sample size of one, a challenge arises: we must determine which conclusions are unique to the Sun (or Sun-like stars), and which apply to other stellar types as well.Based on observations and modeling, astronomers think that stellar flares result from the reconnection of magnetic field lines in a stars outer atmosphere, the corona. The magnetic activity is thought to be driven by a dynamo caused by motions in the stars convective zone.HR diagram of the Kepler stars, with flaring main-sequence (yellow), giant (red) and A-star (green) stars in the authors sample indicated. [Van Doorsselaere et al. 2017]To test whether these ideas are true generally, we need to understand what types of stars exhibit flares, and what stellar properties correlate with flaring activity. A team of scientists led by Tom Van Doorsselaere (KU Leuven, Belgium) has now used an enormous sample of flares observed by Kepler to explore these statistics.Intriguing TrendsVan Doorsselaere and collaborators used a new automated flare detection and characterization algorithm to search through the raw light curves from Quarter 15 of the Kepler mission, building a sample of 16,850 flares on 6,662 stars. They then used these to study the dependence of the flare occurrence rate, duration, energy, and amplitude on the stellar spectral type and rotation period.This large statistical study led the authors to several interesting conclusions, including:Flare star incidence rate as a a

  2. Maternal hyperglycemia in singleton pregnancies conceived by IVF may be modified by first-trimester BMI. (United States)

    Cai, S; Natarajan, P; Chan, J K Y; Wong, P C; Tan, K H; Godfrey, K M; Gluckman, P D; Shek, L P C; Yap, F; Kramer, M S; Chan, S Y; Chong, Y S


    diagnostic criteria. Our cohort may not be representative of the general Singapore obstetric population, although participants were recruited from the two largest maternity hospitals in the country and include both private and subsidized patients. IVF appears to be an independent risk factor for GDM and elevated blood glucose levels in overweight women. Our findings reinforce the need to advise overweight or obese women contemplating IVF to lose weight before the procedure to reduce their risk of GDM and hyperglycemia-related adverse outcomes arising therefrom. In settings where universal GDM screening is not routine, overweight or obese women who conceive by IVF should be screened. This research was supported by the Singapore National Research Foundation under its Translational and Clinical Research (TCR) Flagship Program and administered by the Singapore Ministry of Health's National Medical Research Council (NMRC), Singapore (NMRC/TCR/004-NUS/2008; NMRC/TCR/012-NUHS/2014). Additional funding was provided by the Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR). K.M.G. and Y.S.C. have received lecture fees from Nestle Nutrition Institute and Danone, respectively. K.M.G., Y.S.C. and S.Y.C. are part of an academic consortium that has received research funding from Abbott Nutrition, Nestec and Danone. The other authors have nothing to disclose. The other authors have nothing to disclose. N/A.

  3. Debris Disks And The Search For Life In The Universe (United States)

    Cataldi, Gianni


    Circumstellar debris disks are the extrasolar analogues of the asteroid belt and the Kuiper belt. These disks consist of comets and leftover planetesimals that continuously collide to produce copious amounts of circumstellar dust that can be observed as infrared excess or in resolved imaging. As an obvious outcome of the planet formation process, debris disks can help us constrain planet formation theories and learn about the history of our own solar system. Structures in the disks such as gaps or warps can hint at the presence of planets. Thus, the study of debris disks is an important branch of exoplanetary science. In this thesis, some aspects of debris disks are considered in detail.A handful of debris disks show observable amounts of gas besides the dust. One such case is the edge-on debris disk around the young A-type star β Pictoris, where the gas is thought to be of secondary origin, i.e. derived from the dust itself. By observing this gas, we can thus learn something about the dust, and therefore about the building blocks of planets. In paper I, spectrally resolved observations of C II emission with Herschel/HIFI are presented. The line profile is used to constrain the spatial distribution of carbon gas in the disk, which helps understanding the gas producing mechanism. In paper II, we analyse C II and O I emission detected with Herschel/PACS and find that the oxygen must be located in a relatively dense region, possibly similar to the CO clump seen by ALMA. An upcoming analysis of our ALMA C I observations will give us a clearer picture of the system.Another famous debris disk is found around the nearby, 440 Myr old A-star Fomalhaut. Its morphology is that of an eccentric debris belt with sharp edges, suggesting shaping by a planet. However, gas-dust interactions may result in a similar morphology without the need to invoke planets. We test this possibility in paper III by analysing non-detections of C II and O I emission by Herschel/PACS. We find that

  4. PREFACE: Preface (United States)

    Luo, Qingming; Wang, Lihong V.; Tuchin, Valery V.


    Qingming LuoLihong V WangValery V TuchinConference Chairs 9th International Conference on Photonics and Imaging in Biology and Medicine (PIBM 2010)2-5 November 2010Wuhan, China EditorsQingming Luo, Huazhong University of Science and Technology (China)Lihong V Wang , Washington University in St. Louis (USA)Valery V Tuchin, Saratov State University (Russia) Sponsored and Organized byHuazhong University of Science and Technology (China)Wuhan National Laboratory for Optoelectronics (China)Britton Chance Center for Biomedical Photonics (China) Technical Co-sponsored byIBOS-International Biomedical Optics SocietyThe Chinese Optical SocietyThe Biophysical Society of China Co-organized byKey Laboratory of Biomedical Photonics, Ministry of Education (China)Virtual Research Center of Biomedical Photonics, Ministry of Education (China)Hubei Bioinformatics and Molecular Imaging Key Laboratory (China) CONFERENCE COMMITTEES Honorary ChairsBritton Chance, University of Pennsylvania (USA)Bingkun Zhou, Tsinghua University (China) Conference ChairsQingming Luo, Huazhong University of Science and Technology (China)Lihong V Wang , Washington University in St. Louis (USA)Valery V Tuchin, Saratov State University (Russia) Advisory CommitteeSydney Brenner, The Salk Institute in La Jolla, California (USA)Howard Chen, K&L Gates (USA)Jing Cheng, Tsinghua University (China)Shu Chien, University of California, San Diego (USA)Paul Ching-Wu Chu, University of Houston (USA)Aaron Ciechanover, Technion-Israel Institute of Technology, Haifa (Israel)A Stephen Dahms, Alfred E Mann Foundation for Biomedical Engineering (USA)Da Hsuan Feng, National Cheng Kung University (Taiwan, China)Steven R Goodman, SUNY Upstate Medical University (USA)Barry Halliwell, National University of Singapore (Singapore)John Hart, The University of Texas at Dallas (USA)George Radda, Agency for Science, Technology and Research (A*STAR) (Singapore)Zihe Rao, Nankai University (China)Brian M Salzberg, University of Pennsylvania (USA

  5. Origin of Enigmatic Galactic-center Filaments Revealed (United States)


    blown off from individual stars." The star-forming regions associated with the filaments may contain about 100 massive stars each. The center of the Milky Way Galaxy is shrouded from optical telescopes by dense clouds of dust and gas. Radio telescopes, however, are able to pierce through the optical veil and see the features within. Concealed at the very heart of our Galaxy is a supermassive black hole. Known as Sagittarius A* (pronounced A-star), this area is a very powerful source of radio waves and was first detected by Karl Jansky in 1932. While the VLA can image fine scale structures with great precision, it can not always detect extended radio emission. The GBT, however, can help fill in the gaps. Together, they create a more complete image than either instrument could produce separately. "The ability to combine the data from the two telescopes," said Cotton, "gives us a very powerful tool for understanding how the smallest features relate to the overall structure. This is particularly important when you want to study an area like the center of our Galaxy." In addition to Yusef-Zadeh, Hewitt, and Cotton, the GBT survey was conducted by Casey Law and Douglas Roberts of Northwestern University; and Ron Maddalena of the National Radio Astronomy Observatory. The VLA is a single radio telescope made up of 27 separate antennas located on the Plains of San Agustin near Socorro, New Mexico. The GBT is the world’s largest fully steerable radio telescope, and it is located in Green Bank, West Virginia. Both telescopes are operated by the NRAO. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.