Science.gov

Sample records for 0-15 cm horizons

  1. The inference of atmospheric ozone using satellite horizon measurements in the 1042 per cm band.

    NASA Technical Reports Server (NTRS)

    Russell, J. M., III; Drayson, S. R.

    1972-01-01

    Description of a method for inferring atmospheric ozone information using infrared horizon radiance measurements in the 1042 per cm band. An analysis based on this method proves the feasibility of the horizon experiment for determining ozone information and shows that the ozone partial pressure can be determined in the altitude range from 50 down to 25 km. A comprehensive error study is conducted which considers effects of individual errors as well as the effect of all error sources acting simultaneously. The results show that in the absence of a temperature profile bias error, it should be possible to determine the ozone partial pressure to within an rms value of 15 to 20%. It may be possible to reduce this rms error to 5% by smoothing the solution profile. These results would be seriously degraded by an atmospheric temperature bias error of only 3 K; thus, great care should be taken to minimize this source of error in an experiment. It is probable, in view of recent technological developments, that these errors will be much smaller in future flight experiments and the altitude range will widen to include from about 60 km down to the tropopause region.

  2. 47 CFR 0.15 - Functions of the Office.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Functions of the Office. 0.15 Section 0.15 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMISSION ORGANIZATION Organization Office of Media Relations § 0.15 Functions of the Office. (a) Enhance public understanding of and compliance with...

  3. HORIZON SENSING (PROPOSAL NO.51)

    SciTech Connect

    Larry G. Stolarczyk

    2003-07-30

    Real-time horizon sensing on continuous mining (CM) machines is becoming an industry tool. Installation and testing of production-grade Horizon Sensor (HS) systems has been ongoing this quarter at Monterey Coal Company (ExxonMobil), Mountain Coal Company West Elk Mine (Arch), Deserado Mining Company (Blue Mountain Energy), and The Ohio Valley Coal Company (TOVCC). Monitoring of system function, user experience, and mining benefits is ongoing. All horizon sensor components have finished MSHA (U.S.) and IEC (International) certification.

  4. HORIZON SENSING

    SciTech Connect

    Larry G. Stolarczyk

    2003-03-18

    With the aid of a DOE grant (No. DE-FC26-01NT41050), Stolar Research Corporation (Stolar) developed the Horizon Sensor (HS) to distinguish between the different layers of a coal seam. Mounted on mining machine cutter drums, HS units can detect or sense the horizon between the coal seam and the roof and floor rock, providing the opportunity to accurately mine the section of the seam most desired. HS also enables accurate cutting of minimum height if that is the operator's objective. Often when cutting is done out-of-seam, the head-positioning function facilitates a fixed mining height to minimize dilution. With this technology, miners can still be at a remote location, yet cut only the clean coal, resulting in a much more efficient overall process. The objectives of this project were to demonstrate the feasibility of horizon sensing on mining machines and demonstrate that Horizon Sensing can allow coal to be cut cleaner and more efficiently. Stolar's primary goal was to develop the Horizon Sensor (HS) into an enabling technology for full or partial automation or ''agile mining''. This technical innovation (R&D 100 Award Winner) is quickly demonstrating improvements in productivity and miner safety at several prominent coal mines in the United States. In addition, the HS system can enable the cutting of cleaner coal. Stolar has driven the HS program on the philosophy that cutting cleaner coal means burning cleaner coal. The sensor, located inches from the cutting bits, is based upon the physics principles of a Resonant Microstrip Patch Antenna (RMPA). When it is in proximity of the rock-coal interface, the RMPA impedance varies depending on the thickness of uncut coal. The impedance is measured by the computer-controlled electronics and then sent by radio waves to the mining machine. The worker at the machine can read the data via a Graphical User Interface, displaying a color-coded image of the coal being cut, and direct the machine appropriately. The Horizon Sensor

  5. Killing Horizons Kill Horizon Degrees

    NASA Astrophysics Data System (ADS)

    Bergamin, L.; Grumiller, D.

    Frequently, it is argued that the microstates responsible for the Bekenstein-Hawking entropy should arise from some physical degrees of freedom located near or on the black hole horizon. In this essay, we elucidate that instead entropy may emerge from the conversion of physical degrees of freedom, attached to a generic boundary, into unobservable gauge degrees of freedom attached to the horizon. By constructing the reduced phase space, it can be demonstrated that such a transmutation indeed takes place for a large class of black holes, including Schwarzschild.

  6. Peculiarities of ionic transport in Li1.3Al0.15Y0.15Ti1.7(PO4)3 ceramics

    NASA Astrophysics Data System (ADS)

    Šalkus, T.; Kazakevičius, E.; Kežionis, A.; Dindune, A.; Kanepe, Z.; Ronis, J.; Emery, J.; Boulant, A.; Bohnke, O.; Orliukas, A. F.

    2009-05-01

    A powder of Li1.3Al0.15Y0.15Ti1.7(PO4)3 has been synthesized by solid state reaction. The powder was a single phase material and had rhombohedral symmetry (space group R\\bar {3}c ) with six formula units in the unit cell. Impedance spectra of Li1.3Al0.15Y0.15Ti1.7(PO4)3 ceramics were recorded in the frequency range from 106 to 1.2 × 109 Hz and temperature range from 300 to 600 K. Two relaxation type dispersions of electrical quantities in the frequency range were found. The dispersion regions are presumably related to the ionic transport processes in bulk and grain boundaries of the ceramics. The activation energy of the conductivity of the bulk and the activation energy of the characteristic relaxation frequency, at which the dispersion sets in, has the same value of 0.25 eV. The only contribution of the mobility of Li+ ions defines the temperature dependence of the bulk conductivity in the investigated temperature range. The values of ɛ' may be related to the contributions of the polarization of the fast ionic migration, vibrations of the lattice and electronic polarization. Nuclear magnetic resonance (NMR) investigation shows that the T1 of 7Li and 6Li at room temperature are 6 ms and 2 s respectively. This result confirms that the relaxation of the 7Li nucleus occurs through quadrupolar fluctuations although the relaxation of the 6Li nucleus occurs via dipolar fluctuations. Furthermore, the T1 minimum allows us to evidence a motion with a characteristic frequency in the range of the Larmor frequency.

  7. Ganciclovir ophthalmic gel, 0.15%: a valuable tool for treating ocular herpes

    PubMed Central

    Colin, Joseph

    2007-01-01

    Ocular herpes simplex virus (HSV) infection remains a major cause of corneal blindness. Several topical and oral antiviral medications have been used to treat herpetic keratitis. Advances in topical ophthalmic antivirals have been made over the past several decades. The first antivirals that were discovered were cytotoxic, while the antivirals developed more recently, such as acyclovir and ganciclovir, have exceeded these drugs in both efficacy and tolerability. Commercially available outside of the US since 1996, ganciclovir ophthalmic gel, 0.15% (GCV 0.15%, European tradename: Virgan®) is sold in more than 30 countries and has become the standard of care in treating acute herpetic keratitis. GCV 0.15% has been studied in animal models of ocular herpes, in healthy volunteers, and in several clinical studies. It has been found to be safe and effective at treating acute superficial herpetic keratitis. Previous preclinical studies of ganciclovir have shown activity against several common adenovirus strains and one recent clinical study demonstrated clinical effect against adenoviral conjunctivitis. This review is intended to provide a comprehensive overview of the GCV 0.15%, including a brief summary of the etiology and available treatments for ocular HSV, an explanation of GCV 0.15% mechanism of action, a compendium of preclinical and clinical GCV 0.15% studies, and an introduction into new areas of interest involving this drug. PMID:19668521

  8. Two Horizons of Fusion

    ERIC Educational Resources Information Center

    Lo, Mun Ling; Chik, Pakey Pui Man

    2016-01-01

    In this paper, we aim to differentiate the internal and external horizons of "fusion." "Fusion" in the internal horizon relates to the structure and meaning of the object of learning as experienced by the learner. It clarifies the interrelationships among an object's critical features and aspects. It also illuminates the…

  9. The 2010 Horizon Report

    ERIC Educational Resources Information Center

    Johnson, L.; Levine, A.; Smith, R.; Stone, S.

    2010-01-01

    The annual "Horizon Report" describes the continuing work of the New Media Consortium's Horizon Project, a qualitative research project established in 2002 that identifies and describes emerging technologies likely to have a large impact on teaching, learning, or creative inquiry on college and university campuses within the next five years. The…

  10. Anomaly corrected heterotic horizons

    NASA Astrophysics Data System (ADS)

    Fontanella, A.; Gutowski, J. B.; Papadopoulos, G.

    2016-10-01

    We consider supersymmetric near-horizon geometries in heterotic supergravity up to two loop order in sigma model perturbation theory. We identify the conditions for the horizons to admit enhancement of supersymmetry. We show that solutions which undergo supersymmetry enhancement exhibit an {s}{l}(2,{R}) symmetry, and we describe the geometry of their horizon sections. We also prove a modified Lichnerowicz type theorem, incorporating α' corrections, which relates Killing spinors to zero modes of near-horizon Dirac operators. Furthermore, we demonstrate that there are no AdS2 solutions in heterotic supergravity up to second order in α' for which the fields are smooth and the internal space is smooth and compact without boundary. We investigate a class of nearly supersymmetric horizons, for which the gravitino Killing spinor equation is satisfied on the spatial cross sections but not the dilatino one, and present a description of their geometry.

  11. Parity horizons in shape dynamics

    NASA Astrophysics Data System (ADS)

    Herczeg, Gabriel

    2016-11-01

    I introduce the notion of a parity horizon, and show that many simple solutions of shape dynamics possess them. I show that the event horizons of the known asymptotically flat black hole solutions of shape dynamics are parity horizons and that this notion of parity implies that these horizons possess a notion of CPT invariance that can in some cases be extended to the solution as a whole. I present three new solutions of shape dynamics with parity horizons and find that not only do event horizons become parity horizons in shape dynamics, but observer-dependent horizons and Cauchy horizons do as well. The fact that Cauchy horizons become (singular) parity horizons suggests a general chronology protection mechanism in shape dynamics that prevents the formation of closed timelike curves.

  12. New Horizons at Pluto

    NASA Astrophysics Data System (ADS)

    Schenk, Paul; Nimmo, Francis

    2016-06-01

    The New Horizons mission has revealed Pluto and its moon Charon to be geologically active worlds. The familiar, yet exotic, landforms suggest that geologic processes operate similarly across the Solar System, even in its cold outer reaches.

  13. Ubiquitous CM and DM

    NASA Technical Reports Server (NTRS)

    Crowley, Sandra L.

    2000-01-01

    Ubiquitous is a real word. I thank a former Total Quality Coach for my first exposure some years ago to its existence. My version of Webster's dictionary defines ubiquitous as "present, or seeming to be present, everywhere at the same time; omnipresent." While I believe that God is omnipresent, I have come to discover that CM and DM are present everywhere. Oh, yes; I define CM as Configuration Management and DM as either Data or Document Management. Ten years ago, I had my first introduction to the CM world. I had an opportunity to do CM for the Space Station effort at the NASA Lewis Research Center. I learned that CM was a discipline that had four areas of focus: identification, control, status accounting, and verification. I was certified as a CMIl graduate and was indoctrinated about clear, concise, and valid. Off I went into a world of entirely new experiences. I was exposed to change requests and change boards first hand. I also learned about implementation of changes, and then of technical and CM requirements.

  14. Electronic structure of (Ca0.85La0.15)FeAs2

    NASA Astrophysics Data System (ADS)

    Liu, Z.-H.; Kim, T. K.; Sala, A.; Ogino, H.; Shimoyama, J.; Büchner, B.; Borisenko, S. V.

    2015-02-01

    We report a comprehensive study of orbital character and tridimensional nature of the electronic structure of (Ca0.85La0.15)FeAs2 from recently discovered "112" family of Iron-based superconductors (IBS), with angle-resolved photoemission spectroscopy. We observed that the band structure is similar to that of "122" family, namely, there are three hole-like bands at the Brillouin zone (BZ) center and two electron-like bands at the BZ corner. The bands near the Fermi level (EF) are mainly derived from the Fe t2g orbitals. On the basis of our present and earlier studies, we classify IBS into the three types according to their crystal structures. We show that although the bands near EF mainly originate from Fe 3d electrons, they are significantly modified by the interaction between the superconducting slabs and the intermediate atoms.

  15. High Curie temperature Bi(1.85)Mn(0.15)Te3 nanoplates.

    PubMed

    Cheng, Lina; Chen, Zhi-Gang; Ma, Song; Zhang, Zhi-dong; Wang, Yong; Xu, Hong-Yi; Yang, Lei; Han, Guang; Jack, Kevin; Lu, Gaoqing Max; Zou, Jin

    2012-11-21

    Bi(1.85)Mn(0.15)Te(3) hexagonal nanoplates with a width of ~200 nm and a thickness of ~20 nm were synthesized using a solvothermal method. According to the structural characterization and compositional analysis, the Mn(2+) and Mn(3+) ions were found to substitute Bi(3+) ions in the lattice. High-level Mn doping induces significant lattice distortion and decreases the crystal lattice by 1.07% in the a axis and 3.18% in the c axis. A high ferromagnetic state with a Curie temperature of ~45 K is observed in these nanoplates due to Mn(2+) and Mn(3+) ion doping, which is a significant progress in the field of electronics and spintronics.

  16. UNIFORM INFALL TOWARD THE COMETARY H II REGION IN THE G34.26+0.15 COMPLEX?

    SciTech Connect

    Liu, Tie; Wu, Yuefang; Zhang, Huawei E-mail: ywu@pku.edu.cn

    2013-10-10

    Gas accretion is a key process in star formation. However, gas infall detections in high-mass, star-forming regions with high spatial resolution observations are rare. Here, we report the detection of gas infall toward a cometary ultracompact H II region ({sup C)} in the G34.26+0.15 complex. The observations were made with the IRAM 30 m, the James Clerk Maxwell Telescope 15 m telescope, and the Submillimeter Array (SMA). The hot core associated with 'C' has a mass of ∼76 ± 11 M{sub ☉} and a volume density of (1.1 ± 0.2) × 10{sup 8} cm{sup –3}. The HCN (3-2) and HCO{sup +} (1-0) lines observed by single dishes and the CN (2-1) lines observed by the SMA show redshifted absorption features, indicating gas infall. We found a linear relationship between the line width and optical depth of the CN (2-1) lines. Those transitions with larger optical depths and line widths have larger absorption areas. However, the infall velocities measured from different lines seem to be constant, indicating that the gas infall is uniform. We also investigated the evolution of gas infall in high-mass, star-forming regions. A tight relationship was found between the infall velocity and the total dust/gas mass. At stages prior to the hot core phase, the typical infall velocity and mass infall rate are ∼1 km s{sup –1} and ∼10{sup –4} M{sub ☉} yr{sup –1}, respectively. While in more evolved regions, the infall velocity and mass infall rates can reach as high as several km s{sup –1} and ∼10{sup –3}-10{sup –2} M{sub ☉} yr{sup –1}, respectively. Accelerated infall has been detected toward some hypercompact H II and ultracompact H II regions. However, the acceleration phenomenon is not seen in more evolved ultracompact H II regions (e.g., G34.26+0.15)

  17. Investigation of horizon Beta.

    PubMed

    Windisch, C C; Leyden, R J; Worzel, J L; Saito, T; Ewing, J

    1968-12-27

    Horizon beta is a subbottom reflector in the North Atlantic deep ocean sediments that extends over a large portion of the North America basin. Cores from an outcrop of beta contained shallow-water Aptian-Albian sediments and deep-water Cenomanian sediments. A core near an outcrop of a deeper horizon, horizon B, contained shallow-water Lower Cretaceous (Barremian-Hauterivian) sediments. These cores can be interpreted to support extensive subsidence of the eastern portion of the basin in early Cretaceous time. It is equally likely that the shallow-water deposits are a result of sediments slumping into an already deep basin. A reconciliation of these interpretations depends upon the JOIDES project.

  18. Firewall or smooth horizon?

    NASA Astrophysics Data System (ADS)

    Ori, Amos

    2016-01-01

    Almheiri, Marolf, Polchinski, and Sully pointed out that for a sufficiently old black hole (BH), the set of assumptions known as the complementarity postulates appears to be inconsistent with the assumption of local regularity at the horizon. They concluded that the horizon of an old BH is likely to be the locus of local irregularity, a "firewall". Here I point out that if one adopts a different assumption, namely that semiclassical physics holds throughout its anticipated domain of validity, then the inconsistency is avoided, and the horizon retains its regularity. In this alternative view-point, the vast portion of the original BH information remains trapped inside the BH throughout the semiclassical domain of evaporation, and possibly leaks out later on. This appears to be an inevitable outcome of semiclassical gravity (if assumed to apply throughout its anticipated domain of validity).

  19. Anisotropy in SmFeAsO0.8F0.15 single crystal

    NASA Astrophysics Data System (ADS)

    Pattanaik, A.; Nayak, P.

    2013-06-01

    The high temperature superconductors in the mixed state rounding superconducting transition temperature have been explained by using anisotropic London theory as well as GL-equation. Due to strong overlapping of vortices at higher fields the super electron density varies in space and London theory fails to explain. For lower critical field with in London limit and temperature close to transition, GL-approach with phenomenological mass tensor can be approximated for studying mixed state behavior. Expressing bare penetration depth λ into effective penetration depth λeff such as λeff2=λ2/f2 = λ2/1-b;f = 1-b and b = ba/Bc2, the high field behavior can be observed using 3D-anisotropic London theory by incorporating vortex overlapping. FeAs superconductors have distinguishing macroscopic properties such as an enormous upper critical field with low superconducting anisotropy and that leads the investigation of topology in the microscopic length scale. Particularly, the variation of specific heat as well as entropy in SmFeAsO0.8F0.15 has been verified by the GL-theory in London limit with vortex overlapping correction and found satisfactory result with the experimental findings.

  20. Novel Cauchy-horizon instability

    SciTech Connect

    Maeda, Hideki; Torii, Takashi; Harada, Tomohiro

    2005-03-15

    The evolution of weak discontinuity is investigated on horizons in the n-dimensional static solutions in the Einstein-Maxwell-scalar-{lambda} system, including the Reissner-Nordstroem-(anti) de Sitter black hole. The analysis is essentially local and nonlinear. We find that the Cauchy horizon is unstable, whereas both the black hole event horizon and the cosmological event horizon are stable. This new instability, the so-called kink instability, of the Cauchy horizon is completely different from the well-known 'infinite-blueshift' instability. The kink instability makes the analytic continuation beyond the Cauchy horizon unstable.

  1. Pulsed Laser Deposition of BaCe(sub 0.85)Y(sub 0.15)0(sub 3) FILMS

    NASA Technical Reports Server (NTRS)

    Dynys, F. W.; Sayir, A.

    2006-01-01

    Pulsed laser deposition has been used to grow nanostructured BaCe(sub 0.85)Y(sub 0.15)0(sub 3) films. The objective is to enhance protonic conduction by reduction of membrane thickness. Sintered samples and laser targets were prepared by sintering BaCe(sub 0.85)Y(sub 0.15)O(sub 3) powders derived by solid state synthesis. Films 2 to 6 m thick were deposited by KrF excimer laser on Si and porous Al2O3 substrates. Nanocrystalline films were fabricated at deposition temperatures of 600-800 C deg at O2 pressure of 30 mTorr and laser fluence of 1.2 J/cm square. Films were characterized by x-ray diffraction, scanning electron microscopy and electrical impedance spectroscopy. Dense single phase BaCe(sub 0.85)Y((sub 0.15) 0(sub 3) films with a columnar growth morphology is observed, preferred crystal growth was found to be dependent upon deposition temperature and substrate type. Electrical conductivity of bulk samples produced by solid state sintering and thin film samples were measured over a temperature range of 100 C deg to 900 C deg in moist argon. Electrical conduction of the fabricated films was 1 to 4 orders of magnitude lower than the sintered bulk samples. With respect to the film growth direction, activation energy for electrical conduction is 3 times higher in the perpendicular direction than the parallel direction.

  2. Instability of enclosed horizons

    NASA Astrophysics Data System (ADS)

    Kay, Bernard S.

    2015-03-01

    We point out that there are solutions to the scalar wave equation on dimensional Minkowski space with finite energy tails which, if they reflect off a uniformly accelerated mirror due to (say) Dirichlet boundary conditions on it, develop an infinite stress-energy tensor on the mirror's Rindler horizon. We also show that, in the presence of an image mirror in the opposite Rindler wedge, suitable compactly supported arbitrarily small initial data on a suitable initial surface will develop an arbitrarily large stress-energy scalar near where the two horizons cross. Also, while there is a regular Hartle-Hawking-Israel-like state for the quantum theory between these two mirrors, there are coherent states built on it for which there are similar singularities in the expectation value of the renormalized stress-energy tensor. We conjecture that in other situations with analogous enclosed horizons such as a (maximally extended) Schwarzschild black hole in equilibrium in a (stationary spherical) box or the (maximally extended) Schwarzschild-AdS spacetime, there will be similar stress-energy singularities and almost-singularities—leading to instability of the horizons when gravity is switched on and matter and gravity perturbations are allowed for. All this suggests it is incorrect to picture a black hole in equilibrium in a box or a Schwarzschild-AdS black hole as extending beyond the past and future horizons of a single Schwarzschild (/Schwarzschild-AdS) wedge. It would thus provide new evidence for 't Hooft's brick wall model while seeming to invalidate the picture in Maldacena's ` Eternal black holes in AdS'. It would thereby also support the validity of the author's matter-gravity entanglement hypothesis and of the paper ` Brick walls and AdS/CFT' by the author and Ortíz.

  3. Horizon as critical phenomenon

    NASA Astrophysics Data System (ADS)

    Lee, Sung-Sik

    2016-09-01

    We show that renormalization group flow can be viewed as a gradual wave function collapse, where a quantum state associated with the action of field theory evolves toward a final state that describes an IR fixed point. The process of collapse is described by the radial evolution in the dual holographic theory. If the theory is in the same phase as the assumed IR fixed point, the initial state is smoothly projected to the final state. If in a different phase, the initial state undergoes a phase transition which in turn gives rise to a horizon in the bulk geometry. We demonstrate the connection between critical behavior and horizon in an example, by deriving the bulk metrics that emerge in various phases of the U( N ) vector model in the large N limit based on the holographic dual constructed from quantum renormalization group. The gapped phase exhibits a geometry that smoothly ends at a finite proper distance in the radial direction. The geometric distance in the radial direction measures a complexity: the depth of renormalization group transformation that is needed to project the generally entangled UV state to a direct product state in the IR. For gapless states, entanglement persistently spreads out to larger length scales, and the initial state can not be projected to the direct product state. The obstruction to smooth projection at charge neutral point manifests itself as the long throat in the anti-de Sitter space. The Poincare horizon at infinity marks the critical point which exhibits a divergent length scale in the spread of entanglement. For the gapless states with non-zero chemical potential, the bulk space becomes the Lifshitz geometry with the dynamical critical exponent two. The identification of horizon as critical point may provide an explanation for the universality of horizon. We also discuss the structure of the bulk tensor network that emerges from the quantum renormalization group.

  4. Perovskite Sr₁-xCexCoO₃-δ (0.05 ≤ x ≤ 0.15) as superior cathodes for intermediate temperature solid oxide fuel cells.

    PubMed

    Yang, Wei; Hong, Tao; Li, Shuai; Ma, Zhaohui; Sun, Chunwen; Xia, Changrong; Chen, Liquan

    2013-02-01

    Perovskite Sr(1-x)Ce(x)CoO(3-δ) (0.05 ≤ x ≤ 0.15) have been prepared by a sol-gel method and studied as cathodes for intermediate temperature solid oxide fuel cells. As SOFC cathodes, Sr(1-x)Ce(x)CoO(3-δ) materials have sufficiently high electronic conductivities and excellent chemical compatibility with SDC electrolyte. The peak power density of cells with Sr(0.95)Ce(0.05)CoO(3-δ) is 0.625 W cm(-2) at 700 °C. By forming a composite cathode with an oxygen ion conductor SDC, the peak power density of the cell with Sr(0.95)Ce(0.05)CoO(3-δ)-30 wt %SDC composite cathode, reaches 1.01 W cm(-2) at 700 °C, better than that of Sm(0.5)Sr(0.5)CoO(3)-based cathode. All these results demonstrates that Sr(1-x)Ce(x)CoO(3-δ) (0.05 ≤ x ≤ 0.15)-based materials are promising cathodes for an IT-SOFC.

  5. Behind the geon horizon

    NASA Astrophysics Data System (ADS)

    Guica, Monica; Ross, Simon F.

    2015-03-01

    We explore the Papadodimas-Raju prescription for reconstructing the region behind the horizon of one-sided black holes in AdS/CFT in the case of the {R}{{P}2} geon—a simple, analytic example of a single-sided, asymptotically AdS3 black hole, which corresponds to a pure CFT state that thermalizes at late times. We show that in this specific example, the mirror operators involved in the reconstruction of the interior have a particularly simple form: the mirror of a single trace operator at late times is just the corresponding single trace operator at early times. We use some explicit examples to explore how changes in the state modify the geometry inside the horizon.

  6. Horizons of cybernetical physics

    NASA Astrophysics Data System (ADS)

    Fradkov, Alexander L.

    2017-03-01

    The subject and main areas of a new research field-cybernetical physics-are discussed. A brief history of cybernetical physics is outlined. The main areas of activity in cybernetical physics are briefly surveyed, such as control of oscillatory and chaotic behaviour, control of resonance and synchronization, control in thermodynamics, control of distributed systems and networks, quantum control. This article is part of the themed issue 'Horizons of cybernetical physics'.

  7. Refraction near the horizon

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.; Liller, William

    1990-01-01

    Variations in astronomical refraction near the horizon are examined. Sunset timings, a sextant mounted on a tripod, and a temperature profile are utilized to derive the variations in refraction data, collected from 7 locations. It is determined that the refraction ranges from 0.234 to 1.678 deg with an rms deviation of 0.16, and it is observed that the variation is larger than previously supposed. Some applications for the variation of refraction value are discussed.

  8. Horizons of cybernetical physics

    PubMed Central

    2017-01-01

    The subject and main areas of a new research field—cybernetical physics—are discussed. A brief history of cybernetical physics is outlined. The main areas of activity in cybernetical physics are briefly surveyed, such as control of oscillatory and chaotic behaviour, control of resonance and synchronization, control in thermodynamics, control of distributed systems and networks, quantum control. This article is part of the themed issue ‘Horizons of cybernetical physics’. PMID:28115620

  9. Magnetic contribution of Bi0.85La0.15FeO3 in (1-x)Bi0.85La0.15FeO3-(x)CoFe2O4 nanocomposite powders

    NASA Astrophysics Data System (ADS)

    Han, Ru-shuai; Qi, Li-qian; Hou, Xue; Liu, Li-hu; Liu, Hui-yuan; Xian, Xiao-Ning; Guo, Ge-Xin; Sun, Hui-yuan

    2016-12-01

    In this work, a solid phase reaction method was used to fabricate (1-x)Bi0.85La0.15FeO3-xCoFe2O4 (x=0.1, 0.2, 0.3, 0.4) composite powders. X-ray diffraction patterns showed that no chemical reaction occurred between the separate Bi0.85La0.15FeO3 and CoFe2O4 phases and indicated that the powder samples had two distinct phases with a CoFe2O4 spinel phase and a Bi0.85La0.15FeO3 perovskite phase. The average crystallite sizes of the Bi0.85La0.15FeO3 in the composite powder were almost unchanged as the CoFe2O4 content was increased. By comparing the experimental and theoretical values for the magnetization, we found that the Bi0.85La0.15FeO3 phase contributed to the magnetization of the composite powders. In addition, it also provides a new way to prove the existence of magnetoelectric coupling in the sample.

  10. Hollow Sodium Tungsten Bronze (Na0.15WO3) Nanospheres: Preparation, Characterization, and Their Adsorption Properties

    PubMed Central

    2009-01-01

    We report herein a facile method for the preparation of sodium tungsten bronzes hollow nanospheres using hydrogen gas bubbles as reactant for chemical reduction of tungstate to tungsten and as template for the formation of hollow nanospheres at the same time. The chemical composition and the crystalline state of the as-prepared hollow Na0.15WO3nanospheres were characterized complementarily, and the hollow structure formation mechanism was proposed. The hollow Na0.15WO3nanospheres showed large Brunauer–Emment–Teller specific area (33.8 m2 g−1), strong resistance to acids, and excellent ability to remove organic molecules such as dye and proteins from aqueous solutions. These illustrate that the hollow nanospheres of Na0.15WO3should be a useful adsorbent. PMID:20596394

  11. Hollow Sodium Tungsten Bronze (Na0.15WO3) Nanospheres: Preparation, Characterization, and Their Adsorption Properties.

    PubMed

    Hou, Jing; Zuo, Guanke; Shen, Guangxia; Guo, He; Liu, Hui; Cheng, Ping; Zhang, Jingyan; Guo, Shouwu

    2009-07-17

    We report herein a facile method for the preparation of sodium tungsten bronzes hollow nanospheres using hydrogen gas bubbles as reactant for chemical reduction of tungstate to tungsten and as template for the formation of hollow nanospheres at the same time. The chemical composition and the crystalline state of the as-prepared hollow Na0.15WO3nanospheres were characterized complementarily, and the hollow structure formation mechanism was proposed. The hollow Na0.15WO3nanospheres showed large Brunauer-Emment-Teller specific area (33.8 m2 g-1), strong resistance to acids, and excellent ability to remove organic molecules such as dye and proteins from aqueous solutions. These illustrate that the hollow nanospheres of Na0.15WO3should be a useful adsorbent.

  12. New Horizons at Pluto

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Artist's concept of the New Horizons spacecraft as it approaches Pluto and its largest moon, Charon, in July 2015. The craft's miniature cameras, radio science experiment, ultraviolet and infrared spectrometers and space plasma experiments will characterize the global geology and geomorphology of Pluto and Charon, map their surface compositions and temperatures, and examine Pluto's atmosphere in detail. The spacecraft's most prominent design feature is a nearly 7-foot (2.1-meter) dish antenna, through which it will communicate with Earth from as far as 4.7 billion miles (7.5 billion kilometers) away.

  13. HORIZON SENSING (PROPOSAL NO.51)

    SciTech Connect

    Larry G. Stolarczyk

    2003-07-01

    Real-time horizon sensing on continuous mining machines is becoming an industry tool. Installation and testing of production-grade Horizon Sensor (HS) systems continued this quarter at Monterey Coal Company (ExxonMobil), Mountain Coal Company West Elk Mine (Arch), and Ohio Valley Coal Company (OVC). Monitoring of system function, user experience, and mining benefits is ongoing. All horizon sensor components have finished MSHA (U.S.) and IEC (International) certification.

  14. What Happens at the Horizon?

    NASA Astrophysics Data System (ADS)

    Mathur, Samir D.

    2013-07-01

    The Schwarzschild metric has an apparent singularity at the horizon r = 2M. What really happens there? If physics at the horizon is "normal" laboratory physics, then we run into Hawking's information paradox. If we want nontrivial structure at the horizon, then we need a mechanism to generate this structure that evades the "no hair" conjectures of the past. Further, if we have such structure, then what would be the role of the traditional black hole metric which continues smoothly past the horizon? Recent work has provided an answer to these questions, and in the process revealed a beautiful tie-up between gravity, string theory and thermodynamics.

  15. Transverse deformations of extreme horizons

    NASA Astrophysics Data System (ADS)

    Li, Carmen; Lucietti, James

    2016-04-01

    We consider the inverse problem of determining all extreme black hole solutions to the Einstein equations with a prescribed near-horizon geometry. We investigate this problem by considering infinitesimal deformations of the near-horizon geometry along transverse null geodesics. We show that, up to a gauge transformation, the linearised Einstein equations reduce to an elliptic PDE for the extrinsic curvature of a cross-section of the horizon. We deduce that for a given near-horizon geometry there exists a finite dimensional moduli space of infinitesimal transverse deformations. We then establish a uniqueness theorem for transverse deformations of the extreme Kerr horizon. In particular, we prove that the only smooth axisymmetric transverse deformation of the near-horizon geometry of extreme Kerr, such that cross-sections of the horizon are marginally trapped surfaces, corresponds to that of the extreme Kerr black hole. Furthermore, we determine all smooth and biaxisymmetric transverse deformations of the near-horizon geometry of the five-dimensional extreme Myers-Perry black hole with equal angular momenta. We find a three parameter family of solutions such that cross-sections of the horizon are marginally trapped, which is more general than the known black hole solutions. We discuss the possibility that they correspond to new five-dimensional vacuum black holes.

  16. Stringy horizons II

    NASA Astrophysics Data System (ADS)

    Giveon, Amit; Itzhaki, Nissan; Kutasov, David

    2016-10-01

    We show that the spectrum of normalizable states on a Euclidean SL(2, R)/U(1) black hole exhibits a duality between oscillator states and wound strings. This duality generalizes the identification between a normalizable mode of dilaton gravity on the cigar and a mode of the tachyon with winding number one around the Euclidean time circle, which plays an important role in the FZZ correspondence. It implies that normalizable states on a large Euclidean black hole have support at widely separated scales. In particular, localized states that are extended over the cap of the cigar (the Euclidian analog of the black hole atmosphere) have a component that is localized near the tip of the cigar (the analog of the stretched horizon). As a consequence of this duality, the states exhibit a transition as a function of radial excitation level. From the perspective of a low energy probe, low lying states are naturally thought of as oscillator states in the black hole atmosphere, while at large excitation level they are naturally described as wound strings. As the excitation level increases, the size of the states first decreases and then increases. This behavior is expected to be a general feature of black hole horizons in string theory.

  17. Logistics Company Carrier Partner 2.0.15 Tool: Technical Documentation 2015 Data Year - United States Version

    EPA Pesticide Factsheets

    This SmartWay Logistics 2.0.15 Tool is intended to help logistics companies estimate and assess their carbon, PM, and NOx emission performance levels as well as their total emissions associated with goods movement in the U.S. freight rail, barge, air and t

  18. Technologies on the Horizon: Teachers Respond to the Horizon Report

    ERIC Educational Resources Information Center

    Hodges, Charles B.; Prater, Alyssa H.

    2014-01-01

    The purpose of this study was to investigate teachers' beliefs regarding the integration of technologies from the 2011 K-12 edition of the "Horizon Report" into their local, public school contexts. Teachers read the "Horizon Report" and then participated in an asynchronous, threaded discussion focusing on technologies they…

  19. Magnetic field penetration depth of La(1.85)Sr(0.15)CuO4 measured by muon spin relaxation

    NASA Technical Reports Server (NTRS)

    Kossler, W. J.; Kempton, J. R.; Yu, X. H.; Schone, H. E.; Uemura, Y. J.

    1987-01-01

    Muon-spin-relaxation measurements have been performed on a high-Tc superconductor La(1.85)Sr(0.15)CuO4. In an external transverse magnetic field of 500 G, a magnetic field penetration depth of 2000 A at T = 10 K has been determined from the muon-spin-relaxation rate which increased with decreasing temperature below Tc. From this depth and the Pauli susceptibility, the superconducting carrier density is estimated at 3 x 10 to the 21st per cu cm. The zero-field relaxation rates above and below Tc were equal, which suggests that the superconducting state in this sample is not associated with detectable static magnetic ordering.

  20. Magnetotransport and thermal properties characterization of 55 K superconductor SmFeAsO0.85F0.15

    NASA Astrophysics Data System (ADS)

    Srivastava, Amit; Pal, Anand; Singh, Saurabh; Shekhar, C.; Singh, H. K.; Awana, V. P. S.; Srivastava, O. N.

    2013-09-01

    This report fairly underlines the magneto-transport, thermal properties characterization and bulk superconductivity in the FeAs-based SmFeAsO0.85F0.1. The phase formation and structure are confirmed by Rietveld analysis of room temperature powder X-ray diffraction (XRD) data. Electron microscopy was employed to unravel the micro structural details, such as perfection of the lattice and the grain morphology including size and boundaries. The electrical and magnetic measurements have been carried out to confirm the bulk superconductivity and understand the nature of electrical transport in the normal and superconducting state. The intra-grain critical current density (Jc) with applied magnetic field is calculated from isothermal DC magnetization (MH) plots using conventional Bean critical state model. Superconductivity is observed at transition temperature (Tc) above 55 K without HPHT (high pressure high temperature) synthesis route. The value of Jc is found to be around 5.26 × 104 A/cm2 at 5 K in zero field. The dependence of thermally activated flux flow energy (U/kB) on the applied magnetic field has been observed. AC susceptibility measurements were performed for 55 K superconducting SmFeAsO0.85F0.15 sample at various amplitude of applied AC drive field and its granular nature is confirmed. The parent compound SmFeAsO is found to be magnetic with Fe spin density wave (SDW) like order below 150 K, on the other hand the F doped SmFeAsO0.85F0.15 sample is bulk superconducting at below 55 K. Both Fe (SDW) at 150 K for SmFeAsO and 55 K superconductivity in case of SmFeAsO0.85F0.15 sample has confirmed by Specific heat [Cp(T)] measurement too. Further Sm orders anti-ferro-magnetically at 4.5 K for non-superconducting and at 3.5 K for superconducting samples, also the entropy change is reduced significantly for the later than the former. Summarily complete physical property characterization for both non-superconducting SmFeAsO and 55 K superconductor SmFeAsO0.85F0.15

  1. Disorder - driven phase transition in La{sub 0.37}Bi{sub 0.15}Sm{sub 0.15}Ca{sub 0.33}MnO{sub 3}

    SciTech Connect

    Ade, Ramesh; Singh, R.

    2015-06-24

    We report the effect of disorder on the properties of La{sub 0.37}Bi{sub 0.15}Sm{sub 0.15}Ca{sub 0.33}MnO{sub 3} manganite synthesized by sol – gel method. The critical properties were investigated through various techniques such as modified - Arrott plot, Kouvel - Fisher method and critical isotherm analysis. The sample show second- order phase transition near critical point. The decrease in magnetization (M), Curie temperature (T{sub C}), evolution of spin or cluster glass behavior and the nature of phase transition compared to first - order transition in La{sub 0.67}Ca{sub 0.33}MnO{sub 3} are ascribed to the disorder caused by the size mismatch of the A-site cations with Bi and Sm doping at La- site.

  2. Resolving Lifshitz Horizons

    SciTech Connect

    Harrison, Sarah; Kachru, Shamit; Wang, Huajia; /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC

    2012-04-24

    Via the AdS/CFT correspondence, ground states of field theories at finite charge density are mapped to extremal black brane solutions. Studies of simple gravity + matter systems in this context have uncovered wide new classes of extremal geometries. The Lifshitz metrics characterizing field theories with non-trivial dynamical critical exponent z {ne} 1 emerge as one common endpoint in doped holographic toy models. However, the Lifshitz horizon exhibits mildly singular behaviour - while curvature invariants are finite, there are diverging tidal forces. Here we show that in some of the simplest contexts where Lifshitz metrics emerge, Einstein-Maxwell-dilaton theories, generic corrections lead to a replacement of the Lifshitz metric, in the deep infrared, by a re-emergent AdS{sub 2} x R{sup 2} geometry. Thus, at least in these cases, the Lifshitz scaling characterizes the physics over a wide range of energy scales, but the mild singularity is cured by quantum or stringy effects.

  3. Telescopic horizon scanning.

    PubMed

    Koenderink, Jan

    2014-12-20

    The problem of "distortionless" viewing with terrestrial telescopic systems (mainly "binoculars") remains problematic. The so called "globe effect" is only partially counteracted in modern designs. Theories addressing the phenomenon have never reached definitive closure. In this paper, we show that exact distortionless viewing with terrestrial telescopic systems is not possible in general, but that it is in principle possible in-very frequent in battle field and marine applications-the case of horizon scanning. However, this involves cylindrical optical elements. For opto-electronic systems, a full solution is more readily feasible. The solution involves a novel interpretation of the relevant constraints and objectives. For final design decisions, it is not necessary to rely on a corpus of psychophysical (or ergonomic) data, although one has to decide whether the instrument is intended as an extension of the eye or as a "pictorial" device.

  4. The Horizon Report. 2006 Edition

    ERIC Educational Resources Information Center

    New Media Consortium, 2006

    2006-01-01

    This third edition of the New Media Consortium's (NMC) annual "Horizon Report" describes the continuing work of the Horizon Project, a research-oriented effort that seeks to identify and describe emerging technologies likely to have a large impact on teaching, learning, or creative expression within higher education. Drawing on ongoing discussions…

  5. The Horizon Report. 2005 Edition

    ERIC Educational Resources Information Center

    New Media Consortium, 2005

    2005-01-01

    This second edition of the New Media Consortium's (NMC) annual "Horizon Report" describes the continuing work of the Horizon Project, a research-oriented effort that seeks to identify and describe emerging technologies likely to have a large impact on teaching, learning, or creative expression within higher education. Drawing on an ongoing series…

  6. The Horizon Report. 2007 Edition

    ERIC Educational Resources Information Center

    New Media Consortium, 2007

    2007-01-01

    This fourth edition of the New Media Consortium's (NMC) annual "Horizon Report" describes the continuing work of the Horizon Project, a research-oriented effort that seeks to identify and describe emerging technologies likely to have a large impact on teaching, learning, or creative expression within higher education. Drawing on ongoing…

  7. The Horizon Report. 2004 Edition

    ERIC Educational Resources Information Center

    New Media Consortium, 2004

    2004-01-01

    This first edition of the New Media Consortium's (NMC) annual "Horizon Report" details findings of the Horizon Project, a research-oriented effort that seeks to identify and describe emerging technologies likely to have a large impact on teaching, learning, or creative expression within higher education. Drawing on an ongoing series of interviews…

  8. Thermal and electric properties of Nd(1.85)Ce(0.15)CuO(4-y) and Pr(1.85)Ce(0.15)CuO(4-y)

    NASA Technical Reports Server (NTRS)

    Lim, Z. S.; Han, K. H.; Lee, Sung-Ik; Jeong, Yoon H.; Song, Y. S.; Park, Y. W.

    1990-01-01

    Electric resistivity, magnetic susceptibility, thermoelectric power, and Hall coefficient of Nd(1.85)Ce(0.15)CuO(4-y) and Pr(1.85)Ce(0.15)CuO(4-y) whose onset temperature of the superconductivity are 24 K and 23 K were measured. Experimental results show many interesting features. In particular, the Hall coefficients are negative and relatively flat as a function of temperature. However, the temperature dependence of the thermoelectric power (TEP) for these two samples shows the positive sign for both samples in contrast to the previous results. Moreover TEP for both samples remains flat in the normal state below 250 K, but decreases rapidly above 250 K. TEP of only Pr(1.85)Ce(0.15)CuO(4-y) shows a peak near 50 K. Finally onset temperatures of sudden drop of TEP are higher than those of resistance drop. The physical properties of these samples produced at different conditions such as different heat treatment temperatures, atmospheres were also measured. TEP and resistance measurement show that oxygen deficiency is essential to produce better superconducting samples. Correlation between TEP and superconductivity for these different samples will be discussed.

  9. Thermal and electric properties of Nd(1.85)Ce(0.15)CuO(4-y) and Pr(1.85)Ce(0.15)CuO(4-y)

    NASA Technical Reports Server (NTRS)

    Lim, Z. S.; Han, K. H.; Lee, Sung-Ik; Jeong, Yoon H.; Song, Y. S.; Park, Y. W.

    1991-01-01

    Electric resistivity, magnetic susceptibility, thermoelectric power, and Hall coefficient of Nd(1.85)Ce(0.15)CuO(4-y) and Pr(1.85)Ce(0.15)CuO(4-y) whose onset temperature of the superconductivity are 24 and 23 K were measured. Experimental results show many interesting features. In particular, the Hall coefficients are negative and relatively flat as a function of temperature. However, the temperature dependence of the thermoelectric power (TEP) for these two samples shows the positive sign for both samples in contrast to the previous results. Moreover, TEP for both samples remains flat in the normal state below 250 K, but decreases rapidly above 250 K. TEP of only Pr(1.85)Ce(0.15)CuO(4-y) shows a peak near 50 K. Finally, onset temperatures of sudden drop of TEP are higher than those of resistance drop. The physical properties of these samples produced at different conditions such as different heat treatment temperatures, atmospheres were also measured. TEP and resistance measurement show that oxygen deficiency is essential to produce better superconducting samples. Correlation between TEP and superconductivity for these different samples are discussed.

  10. PHASE TRANSITION, DIELECTRIC AND PIEZOELECTRIC PROPERTIES OF NaNbO3-Ba0.85Ca0.15(Ti0.9Zr0.1)O3 LEAD-FREE CERAMICS

    NASA Astrophysics Data System (ADS)

    Lei, Yuqing; Wu, Hong; Lin, Dunmin; Zheng, Qiaoji; Wu, Xiaochun; Fan, Ximing

    2012-09-01

    A new lead-free solid solution of (1-x)NaNbO3-xBa0.85Ca0.15(Ti0.9Zr0.1)O3 was prepared by a traditional sintering method and its phase transition, dielectric and piezoelectric properties were studied. Ba0.85Ca0.15(Ti0.9Zr0.1)O3 diffuses into NaNbO3 lattices to form a new solid solution with perovskite structure. The addition of Ba0.85Ca0.15(Ti0.9Zr0.1)O3(x≥0.025) transforms NaNbO3 from antiferroelectric to ferroelectric. The diffusive ferroelectric-paraelectric phase transition is induced in the ceramics with high concentration of Ba0.85Ca0.15(Ti0.9Zr0.1)O3. The ceramics with x = 0.05-0.125 possess large Pr values of 18.6-25.5 μC/cm2. A morphotropic phase boundary between tetragonal and orthorhombic phases is formed at 0.05 < x < 0.15, leading to a significant enhancement of piezoelectric properties. The ceramic with x = 0.125 situated near the morphotropic phase boundary exhibits the optimum piezoelectric properties: d33 = 151 pC/N and kp = 31.6%.

  11. [Effects of Slope Position and Soil Horizon on Soil Microbial Biomass and Abundance in Karst Primary Forest of Southwest China].

    PubMed

    Feng, Shu-zhen; Su, Yi-rong; Zhang, Wei; Chen, Xiang-bi; He, Xun-yang

    2015-10-01

    To explore the effects of slope position and soil horizon on soil microbial biomass and abundance, chloroform fumigation extraction methods and real-time fluorescence-based quantitative PCR (Real-time PCR) were adopted to quantify the changes of soil microbial biomass C, N and abundance of bacteria and fungi, respectively. Soil samples were harvested from three horizons along profile, i. e., leaching horizon (A, 0-10 cm), transitional horizon (AB, 30-50 cm) and alluvial horizon (B, 70-100 cm), which were collected from the upper, middle and lower slope positions of a karst primary forest ecosystem. The results showed that slope position, soil horizon and their interaction significantly influenced the soil microbial biomass and abundance (P < 0.05). Different from A horizon, where SMBC was greater in lower than in upper slope position (P < 0.05), SMBC in AB and B horizons were highest in middle slope position. Similarly, SMBN was greater in lower than in upper slope position for A, AB and B horizons. Besides soil bacterial abundance in B horizon and fungal abundance in AB layer, the middle slope position had the highest value for all the three soil horizons (P < 0.05). Stepwise regression analysis showed that soil organic carbon, available nitrogen and pH were the key factors responsible for SMBC and SMBN variation, respectively, while the important factors responsible for the variation of bacteria abundance were available nitrogen and available phosphorus, and that for fungi abundance variation were available potassium.

  12. 78 FR 70976 - Horizons ETFs Management (USA) LLC and Horizons ETF Trust; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-27

    ... COMMISSION Horizons ETFs Management (USA) LLC and Horizons ETF Trust; Notice of Application November 21, 2013... Shares. Applicants: Horizons ETFs Management (USA) LLC (``Horizons'') and Horizons ETF Trust (``Trust... Commission, 100 F Street NE., Washington, DC 20549-1090; Applicants: Horizons ETFs Management (USA) LLC,...

  13. Unconventional superconductivity in CaFe0.85Co0.15AsF evidenced by torque measurements

    NASA Astrophysics Data System (ADS)

    Xiao, Hong; Li, X. J.; Mu, G.; Hu, T.

    Out-of-plane angular dependent torque measurements were performed on CaFe0.85Co0.15AsF single crystals. Abnormal superconducting fluctuation, featured by enhanced diamagnetism with magnetic field, is detected up to about 1.5 times superconducting transition temperature Tc. Compared to cuprate superconductors, the fluctuation effect in iron-based superconductor is less pronounced. Anisotropy parameter γ is obtained from the mixed state torque data and it is found that γ shows both magnetic field and temperature depenence, pointing to multiband superconductivity. The temperature dependence of penetration depth λ (T) suggests unconventional superconductivity in CaFe0.85Co0.15AsF.

  14. Asymptotic symmetries on Killing horizons

    NASA Astrophysics Data System (ADS)

    Koga, Jun-Ichirou

    2001-12-01

    We investigate asymptotic symmetries regularly defined on spherically symmetric Killing horizons in Einstein theory with or without the cosmological constant. These asymptotic symmetries are described by asymptotic Killing vectors, along which the Lie derivatives of perturbed metrics vanish on a Killing horizon. We derive the general form of the asymptotic Killing vectors and find that the group of asymptotic symmetries consists of rigid O(3) rotations of a horizon two-sphere and supertranslations along the null direction on the horizon, which depend arbitrarily on the null coordinate as well as the angular coordinates. By introducing the notion of asymptotic Killing horizons, we also show that local properties of Killing horizons are preserved not only under diffeomorphisms but also under nontrivial transformations generated by the asymptotic symmetry group. Although the asymptotic symmetry group contains the Diff(S1) subgroup, which results from supertranslations dependent only on the null coordinate, it is shown that the Poisson brackets algebra of the conserved charges conjugate to asymptotic Killing vectors does not acquire nontrivial central charges. Finally, by considering extended symmetries, we discuss the fact that unnatural reduction of the symmetry group is necessary in order to obtain the Virasoro algebra with nontrivial central charges, which is not justified when we respect the spherical symmetry of Killing horizons.

  15. Near-horizon Kerr magnetosphere

    NASA Astrophysics Data System (ADS)

    Gralla, Samuel E.; Lupsasca, Alexandru; Strominger, Andrew

    2016-05-01

    We exploit the near-horizon conformal symmetry of rapidly spinning black holes to determine universal properties of their magnetospheres. Analytic expressions are derived for the limiting form of the magnetosphere in the near-horizon region. The symmetry is shown to imply that the black hole Meissner effect holds for free Maxwell fields but is generically violated for force-free fields. We further show that in the extremal limit, near-horizon plasma particles are infinitely boosted relative to accretion flow. Active galactic nuclei powered by rapidly spinning black holes are therefore natural sites for high-energy particle collisions.

  16. Social Pharmacology: Expanding horizons

    PubMed Central

    Maiti, Rituparna; Alloza, José Luis

    2014-01-01

    In the current modern and global society, social changes are in constant evolution due to scientific progress (technology, culture, customs, and hygiene) and produce the freedom in individuals to take decisions by themselves or with their doctors toward drug consumption. In the arena of marketed drug products which includes society, individual, administration, and pharmaceutical industry, the young discipline emerged is social pharmacology or sociopharmacology. This science arises from clinical pharmacology, and deals with different parameters, which are important in creating knowledge on marketed drugs. However, the scope of “social pharmacology” is not covered by the so-called “Phase IV” alone, but it is the science that handles the postmarketing knowledge of drugs. The social pharmacology studies the “life cycle” of any marketed pharmaceutical product in the social terrain, and evaluates the effects of the real environment under circumstances totally different in the drug development process. Therefore, there are far-reaching horizons, plural, and shared predictions among health professionals and other, for beneficial use of a drug, toward maximizing the benefits of therapy, while minimizing negative social consequences. PMID:24987168

  17. Social pharmacology: expanding horizons.

    PubMed

    Maiti, Rituparna; Alloza, José Luis

    2014-01-01

    In the current modern and global society, social changes are in constant evolution due to scientific progress (technology, culture, customs, and hygiene) and produce the freedom in individuals to take decisions by themselves or with their doctors toward drug consumption. In the arena of marketed drug products which includes society, individual, administration, and pharmaceutical industry, the young discipline emerged is social pharmacology or sociopharmacology. This science arises from clinical pharmacology, and deals with different parameters, which are important in creating knowledge on marketed drugs. However, the scope of "social pharmacology" is not covered by the so-called "Phase IV" alone, but it is the science that handles the postmarketing knowledge of drugs. The social pharmacology studies the "life cycle" of any marketed pharmaceutical product in the social terrain, and evaluates the effects of the real environment under circumstances totally different in the drug development process. Therefore, there are far-reaching horizons, plural, and shared predictions among health professionals and other, for beneficial use of a drug, toward maximizing the benefits of therapy, while minimizing negative social consequences.

  18. Lithium-Rich Layered Oxide Li1.18 Ni0.15 Co0.15 Mn0.52 O2 as the Cathode Material for Hybrid Sodium-Ion Batteries.

    PubMed

    Wei, Zhixuan; Gao, Yu; Wang, Lei; Zhang, Chaoyang; Bian, Xiaofei; Fu, Qiang; Wang, Chunzhong; Wei, Yingjin; Du, Fei; Chen, Gang

    2016-08-08

    Li-rich layered oxide Li1.18 Ni0.15 Co0.15 Mn0.52 O2 (LNCM) is, for the first time, examined as the positive electrode for hybrid sodium-ion battery and its Na(+) storage properties are comprehensively studied in terms of galvanostatic charge-discharge curves, cyclic voltammetry and rate capability. LNCM in the proposed sodium-ion battery demonstrates good rate capability whose discharge capacity reaches about 90 mA h g(-1) at 10 C rate and excellent cycle stability with specific capacity of about 105 mA h g(-1) for 200 cycles at 5 C rate. Moreover, ex situ ICP-OES suggests interesting mixed-ions migration processes: In the initial two cycles, only Li(+) can intercalate into the LNCM cathode, whereas both Li(+) and Na(+) work together as the electrochemical cycles increase. Also the structural evolution of LNCM is examined in terms of ex situ XRD pattern at the end of various charge-discharge scans. The strong insight obtained from this study could be beneficial to the design of new layered cathode materials for future rechargeable sodium-ion batteries.

  19. A comprehensive investigation of structural, morphological, hydrogen absorption and magnetic properties of MmNi4.22Co0.48Mn0.15Al0.15 alloy

    NASA Astrophysics Data System (ADS)

    Zareii, Seyyed Mojtaba; Arabi, Hadi; Pourarian, Faiz

    2014-05-01

    A comprehensive study of structural, morphological, hydrogen absorption and magnetic properties of MmNi4.22 Co0.48Mn0.15Al0.15 alloy as a promising hydrogen storage media was investigated. The X-ray diffraction (XRD) profiles show that the alloy maintains its crystal structure (hexagonal LaNi5-type) even after 30 hydrogenation/dehydrogenation (H/D) cycles. However, the XRD peaks are found to be slightly broadened after cycling. SEM images reveal that particles size of the cycled sample decreases, with more uniform particle size distribution compared to noncycled ones. The pressure-composition (PC) isotherms and kinetics curves of hydrogen absorption reaction were obtained at different working temperatures by using a homemade Sievert apparatus. The enthalpy and entropy of hydride formation of the alloy were evaluated. Furthermore, the Jander diffusion and Johnson-Mehl-Avrami models as the fitting models were employed to study the kinetic mechanism of hydriding reaction and its activation energy. The room temperature magnetic measurements indicate that the milling and H/D cycling change the magnetic properties of the as-annealed alloy.

  20. Remarkable magnetostructural coupling around the magnetic transition in CeCo0.85Fe0.15Si.

    PubMed

    Correa, V F; Betancourth, D; Sereni, J G; Caroca Canales, N; Geibel, C

    2016-09-01

    We report a detailed study of the magnetic properties of CeCo0.85Fe0.15Si under high magnetic fields (up to 16 Tesla) measuring different physical properties such as specific heat, magnetization, electrical resistivity, thermal expansion and magnetostriction. CeCo0.85Fe0.15Si becomes antiferromagnetic at [Formula: see text] K. However, a broad tail (onset at [Formula: see text] K) in the specific heat precedes that second order transition. This tail is also observed in the temperature derivative of the resistivity. However, it is particularly noticeable in the thermal expansion coefficient where it takes the form of a large bump centered at T X . A high magnetic field practically washes out that tail in the resistivity. But surprisingly, the bump in the thermal expansion coefficient becomes a well pronounced peak fully split from the magnetic transition at T N . Concurrently, the magnetoresistance also switches from negative to positive above T N . The magnetostriction is considerable and irreversible at low temperature ([Formula: see text] at 2 K) when the magnetic interactions dominate. A broad jump in the field dependence of the magnetostriction observed at low T may be the signature of a weak ongoing metamagnetic transition. Taking altogether the results indicate the importance of the lattice effects on the development of the magnetic order in these alloys.

  1. A 0.15-scale study of configuration effects on the aerodynamic interaction between main rotor and fuselage

    NASA Technical Reports Server (NTRS)

    Trept, Ted

    1984-01-01

    Hover and forward flight tests were conducted to investigate the mutual aerodynamic interaction between the main motor and fuselage of a conventional helicopter configuration. A 0.15-scale Model 222 two-bladed teetering rotor was combined with a 0.15-scale model of the NASA Ames 40x80-foot wind tunnel 1500 horsepower test stand fairing. Configuration effects were studied by modifying the fairing to simulate a typical helicopter forebody. Separation distance between rotor and body were also investigated. Rotor and fuselage force and moment as well as pressure data are presented in graphical and tabular format. Data was taken over a range of thrust coefficients from 0.002 to 0.007. In forward flight speed ratio was varied from 0.1 to 0.3 with shaft angle varying from +4 to -12 deg. The data show that the rotors effect on the fuselage may be considerably more important to total aircraft performance than the effect of the fuselage on the rotor.

  2. Remarkable magnetostructural coupling around the magnetic transition in CeCo0.85Fe0.15Si

    NASA Astrophysics Data System (ADS)

    Correa, V. F.; Betancourth, D.; Sereni, J. G.; Caroca Canales, N.; Geibel, C.

    2016-09-01

    We report a detailed study of the magnetic properties of CeCo0.85Fe0.15Si under high magnetic fields (up to 16 Tesla) measuring different physical properties such as specific heat, magnetization, electrical resistivity, thermal expansion and magnetostriction. CeCo0.85Fe0.15Si becomes antiferromagnetic at {{T}N}≈ 6.7 K. However, a broad tail (onset at {{T}X}≈ 13 K) in the specific heat precedes that second order transition. This tail is also observed in the temperature derivative of the resistivity. However, it is particularly noticeable in the thermal expansion coefficient where it takes the form of a large bump centered at T X . A high magnetic field practically washes out that tail in the resistivity. But surprisingly, the bump in the thermal expansion coefficient becomes a well pronounced peak fully split from the magnetic transition at T N . Concurrently, the magnetoresistance also switches from negative to positive above T N . The magnetostriction is considerable and irreversible at low temperature (\\frac{Δ L}{L}(16~T)∼ 4× {{10}-4} at 2 K) when the magnetic interactions dominate. A broad jump in the field dependence of the magnetostriction observed at low T may be the signature of a weak ongoing metamagnetic transition. Taking altogether the results indicate the importance of the lattice effects on the development of the magnetic order in these alloys.

  3. An AlN/Al0.85Ga0.15N high electron mobility transistor

    DOE PAGES

    Baca, Albert G.; Armstrong, Andrew M.; Allerman, Andrew A.; ...

    2016-07-22

    An AlN barrier high electron mobility transistor (HEMT) based on the AlN/Al0.85Ga0.15N heterostructure was grown, fabricated, and electrically characterized, thereby extending the range of Al composition and bandgap for AlGaN channel HEMTs. An etch and regrowth procedure was implemented for source and drain contact formation. A breakdown voltage of 810 V was achieved without a gate insulator or field plate. Excellent gate leakage characteristics enabled a high Ion/Ioff current ratio greater than 107 and an excellent subthreshold slope of 75 mV/decade. A large Schottky barrier height of 1.74 eV contributed to these results. In conclusion, the room temperature voltage-dependent 3-terminalmore » off-state drain current was adequately modeled with Frenkel-Poole emission.« less

  4. An AlN/Al0.85Ga0.15N high electron mobility transistor

    NASA Astrophysics Data System (ADS)

    Baca, Albert G.; Armstrong, Andrew M.; Allerman, Andrew A.; Douglas, Erica A.; Sanchez, Carlos A.; King, Michael P.; Coltrin, Michael E.; Fortune, Torben R.; Kaplar, Robert J.

    2016-07-01

    An AlN barrier high electron mobility transistor (HEMT) based on the AlN/Al0.85Ga0.15N heterostructure was grown, fabricated, and electrically characterized, thereby extending the range of Al composition and bandgap for AlGaN channel HEMTs. An etch and regrowth procedure was implemented for source and drain contact formation. A breakdown voltage of 810 V was achieved without a gate insulator or field plate. Excellent gate leakage characteristics enabled a high Ion/Ioff current ratio greater than 107 and an excellent subthreshold slope of 75 mV/decade. A large Schottky barrier height of 1.74 eV contributed to these results. The room temperature voltage-dependent 3-terminal off-state drain current was adequately modeled with Frenkel-Poole emission.

  5. Nonlinear structure-composition relationships in the Ge1-ySny/Si(100) (y<0.15) system

    DOE PAGES

    Beeler, R.; Roucka, R.; Chizmeshya, A. V. G.; ...

    2011-07-26

    The compositional dependence of the cubic lattice parameter in Ge1-ySny alloys has been revisited. Large 1000-atom supercell ab initio simulations confirm earlier theoretical predictions that indicate a positive quadratic deviation from Vegard's law, albeit with a somewhat smaller bowing coefficient, θ = 0.047 Å, than found from 64-atom cell simulations (θ = 0.063 Å). On the other hand, measurements from an extensive set of alloy samples with compositions y < 0.15 reveal a negative deviation from Vegard's law. The discrepancy with earlier experimental data, which supported the theoretical results, is traced back to an unexpected compositional dependence of the residualmore » strain after growth on Si substrates. The experimental bowing parameter for the relaxed lattice constant of the alloys is found to be θ = -0.066 Å. Possible reasons for the disagreement between theory and experiment are discussed in detail.« less

  6. Scaling law and flux pinning in polycrystalline La1.85Sr0.15CuO4

    NASA Astrophysics Data System (ADS)

    Hampshire, D. P.; Ikeda, J. A. S.; Chiang, Y.-M.

    1989-11-01

    The transport critical current density (Jct) of two hot-pressed bulk polycrystalline La1.85Sr0.15CuO4 superconducting samples has been measured over the temperature range 2 K to Tc in magnetic fields up to 27 T. It is demonstrated that these data have a separable variable form Fp=JctB=α(D)B2.4c2 (T)b [where α(D) is a constant and b=B/Bc2(T)], in agreement with the Fietz-Webb scaling law. This is strong evidence that in high magnetic fields, flux pinning is the mechanism that determines the critical current density. The authors suggest that the dissipative state is described by flux flow along the regions of weak flux pinning at the grain boundaries.

  7. Unusual magnetoresistance in cubic B20 Fe0.85Co0.15Si chiral magnets

    DOE PAGES

    Huang, S. X.; Chen, Fei; Kang, Jian; ...

    2016-06-24

    The B20 chiral magnets with broken inversion symmetry and C4 rotation symmetry have attracted much attention. The broken inversion symmetry leads to the Dzyaloshinskii–Moriya that gives rise to the helical and Skyrmion states.Wereport the unusual magnetoresistance (MR) of B20 chiral magnet Fe0.85Co0.15Si that directly reveals the broken C4 rotation symmetry and shows the anisotropic scattering by Skyrmions with respect to the current directions. The intimacy between unusual MR and broken symmetry is well confirmed by theoretically studying an effective Hamiltonian with spin–orbit coupling. In conclusion, the unusual MR serves as a transport signature for the Skyrmion phase.

  8. Magneto-structural correlations in Pr 0.15Gd 0.85Mn 2Ge 2

    NASA Astrophysics Data System (ADS)

    Dincer, I.; Elerman, Y.; Elmali, A.; Ehrenberg, H.; Fuess, H.; Baehtz, C.

    2006-11-01

    Magneto-structural correlations in Pr 0.15Gd 0.85Mn 2Ge 2 have been studied by synchrotron diffraction in the temperature range between 11 and 300 K. This compound crystallizes in the ThCr 2Si 2-type structure (space group I4/mmm). The unit cell parameters a and c were determined by Rietveld refinements as a function of temperature. Anomalies in the temperature dependence of the unit cell parameters a and c, the c/a ratio and the unit cell volume V at about 240 and 140 K, which is close to the magnetic phase transition temperatures, indicate a pronounced magneto-structural correlation. Spontaneous volume change and linear magnetostrictions are derived as a function of temperature.

  9. Growth and characterization of the La3Ga4.85Fe0.15SiO14 piezoelectric single crystal

    NASA Astrophysics Data System (ADS)

    Dou, Renqin; Liu, Wenpeng; Zhang, Qi; Zhang, Qingli; Ding, Shoujun; Shi, Zibin; Sun, Dunlu; Wang, Jiyang

    2017-01-01

    A new piezoelectric single crystal La3Ga4.85Fe0.15SiO14 (LGFS) was grown by the Czochralski method firstly. Its structural parameters were obtained by Rietveld refinement to the X-ray diffraction. The effective segregation coefficient k eff of Fe in the LGFS was determined to be 0.6. The cost of LGFS is reduced due to the doping of cheap Fe. The crystal density was measured to be 5.7 g cm-3 by the buoyancy method. The defect structure of LGFS crystal was investigated by the chemical etching with 85% H2SO4 etchant. Dislocation etching pit patterns of LGFS crystal are consistent with the corresponding atomic arrangement schematics. Compared with LGS, LGN, LGT, and LGAS crystal, the LGFS crystal exhibits outstanding dielectric and piezoelectric properties, and ɛ 11, ɛ 33, d 11, and d 14 are 20.86, 51.99, 6.5 pC/N, and -5.10 pC/N, respectively. Therefore, LGFS may be a new potential piezoelectric crystal with high performance and low expense.

  10. Huge Critical Current Density and Tailored Superconducting Anisotropy in SmFeAsO(0.8)F(0.15) by Low Density Columnar-Defect Incorporation

    NASA Astrophysics Data System (ADS)

    Welp, U.; Fang, L.; Jia, Y.; Mishra, V.; Chaparro, C.; Vlasko-Vlasov, V. K.; Koshelev, A. E.; Crabtree, G. W.; Zhu, S. F.; Zhigadlo, N. D.; Katrych, S.; Karpinski, J.; Kwok, W. K.

    2014-03-01

    SmFeAsO(0.8)F(0.15) is of great interest because it has the highest transition temperature of all the iron-based superconductors. We find that the introduction of a low density of correlated nano-scale defects enhances the critical current density up to 2 × 107A/cm2 at 5 K without any suppression in the high superconducting transition temperature of 50 K and amounting to 20 % of the theoretical depairing current density. We also observed a surprising reduction in the thermodynamic superconducting anisotropy from 8 to 4 upon irradiation. A model based on anisotropic electron scattering predicts that the superconducting anisotropy can be tailored via correlated defects in semi-metallic, fully gapped type II superconductors. - We acknowledge support by the Center for Emergent Superconductivity, an EFRC funded by the US DOE, Office of Basic Energy Sciences (LF, YJ, VM, AEK, WKK, GWC), by the DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 (CC, VKV, UW), by the EC Research Council project SuperIron (JK, SK), and by the Swiss National Science Foundation and the National Center of Competence in Research MaNEP (NDZ).

  11. Serpentine Nanotubes in CM Chondrites

    NASA Technical Reports Server (NTRS)

    Zega, Thomas J.; Garvie, Laurence A. J.; Dodony, Istvan; Buseck, Peter R.

    2004-01-01

    The CM chondrites are primitive meteorites that formed during the early solar system. Although they retain much of their original physical character, their matrices and fine-grained rims (FGRs) sustained aqueous alteration early in their histories [1- 3]. Serpentine-group minerals are abundant products of such alteration, and information regarding their structures, compositions, and spatial relationships is important for determining the reactions that produced them and the conditions under which they formed. Our recent work on FGRs and matrices of the CM chondrites has revealed new information on the structures and compositions of serpentine-group minerals [4,5] and has provided insights into the evolution of these primitive meteorites. Here we report on serpentine nanotubes from the Mighei and Murchison CM chondrites [6].

  12. Deepwater Horizon Situation Report #5

    SciTech Connect

    2010-06-10

    At approximately 11:00 pm EDT April 20, 2010 an explosion occurred aboard the Deepwater Horizon mobile offshore drilling unit (MODU) located 52 miles Southeast of Venice, LA and 130 miles southeast of New Orleans, LA. The MODU was drilling an exploratory well and was not producing oil at the time of the incident. The Deepwater Horizon MODU sank 1,500 feet northwest of the well site. Detailed information on response and recovery operations can be found at: http://www.deepwaterhorizonresponse.com/go/site/2931/

  13. The Evolution of Star Formation Activity in Cluster Galaxies Over 0.15 < z < 1.5

    NASA Astrophysics Data System (ADS)

    Wagner, Cory R.

    In this thesis, we explore 7.5 billion years of evolution in cluster galaxy star formation activity using a sample of 11 high-redshift (1 < z < 1.5) clusters from the IRAC Shallow Cluster Survey, and 25 low-redshift (0.15 < z < 1) clusters from The Cluster Lensing And Supernova survey with Hubble. We compare cluster galaxy star formation to that of the field over 0.15 < z < 1.5 using 8000 galaxies from the UltraVISTA survey. Mid-infrared star formation rates are measured using Spitzer 24 mum data for isolated high-redshift galaxies. We calculate rest-frame ultraviolet star formation rates for low-redshift cluster members using Hubble Space Telescope observations. Using publically available mid-infrared and ultraviolet data for our field sample, we empirically derive scaling relations to adjust low-redshift cluster galaxy ultraviolet star formation rates to mid-infrared levels. We classify cluster galaxy morphology by visual inspection, and use quantitatively measured morphologies for field galaxies. Cluster late-type galaxies at z > 1 show enhanced star formation activity relative to the field, and account for nearly 90% of the overall star formation activity in high-redshift clusters. While high-redshift early-type galaxies are substantially quenched relative to cluster late-types, they still contribute 13% of the total cluster star formation activity. With early-type fractions increasing from 34 to 56% from z 1.5 → 1.16, we find that new cluster early-type galaxies are likely being formed around z 1.4. The fraction of early-type galaxies that are star-forming drops from 29 to 11% over this period, yet their specific star formation rates are roughly constant. These factors suggest that the events that created these new galaxies, possibly mergers, were both recent and gas-rich. With typical coverages of 50% of z < 1 cluster virial radii, we can only probe the cores of low-redshift clusters. We find that in this regime, the star formation activity of cluster

  14. 344 cm x 86 cm low mass vacuum window

    SciTech Connect

    Reimers, R.M.; Porter, J.; Meneghetti, J.; Wilde, S.; Miller, R.

    1983-08-01

    The LBL Heavy Ion Spectrometer System (HISS) superconducting magnet contains a 1 m x 3.45 m x 2 m vacuum tank in its gap. A full aperture thin window was needed to minimize background as the products of nuclear collisions move from upstream targets to downstream detectors. Six windows were built and tested in the development process. The final window's unsupported area is 3m/sup 2/ with a 25 cm inward deflection. The design consists of a .11 mm Nylon/aluminum/polypropylene laminate as a gas seal and .55 mm woven aramid fiber for strength. Total mass is 80 milligrams per cm/sup 2/. Development depended heavily on past experience and testing. Safety considerations are discussed.

  15. Electronic structure of (Ca{sub 0.85}La{sub 0.15})FeAs{sub 2}

    SciTech Connect

    Liu, Z.-H. Borisenko, S. V.; Kim, T. K.; Sala, A.; Ogino, H.; Shimoyama, J.; Büchner, B.

    2015-02-02

    We report a comprehensive study of orbital character and tridimensional nature of the electronic structure of (Ca{sub 0.85}La{sub 0.15})FeAs{sub 2} from recently discovered “112” family of Iron-based superconductors (IBS), with angle-resolved photoemission spectroscopy. We observed that the band structure is similar to that of “122” family, namely, there are three hole-like bands at the Brillouin zone (BZ) center and two electron-like bands at the BZ corner. The bands near the Fermi level (E{sub F}) are mainly derived from the Fe t{sub 2g} orbitals. On the basis of our present and earlier studies, we classify IBS into the three types according to their crystal structures. We show that although the bands near E{sub F} mainly originate from Fe 3d electrons, they are significantly modified by the interaction between the superconducting slabs and the intermediate atoms.

  16. NIF featured on BBC "Horizon"

    ScienceCinema

    Brian Cox

    2016-07-12

    The National Ignition Facility, the world's largest laser system, located at Lawrence Livermore National Laboratory, was featured in the BBC broadcast "Horizon" hosted by physicist Brian Cox. Here is the NIF portion of the program, which was entitled "Can We Make A Star On Earth?" This video is used with the express permission of the BBC.

  17. New Horizons Mission to Pluto

    NASA Technical Reports Server (NTRS)

    Delgado, Luis G.

    2011-01-01

    This slide presentation reviews the trajectory that will take the New Horizons Mission to Pluto. Included are photographs of the spacecraft, the launch vehicle, the assembled vehicle as it is being moved to the launch pad and the launch. Also shown are diagrams of the assembled parts with identifying part names.

  18. New Horizons in Education, 2000.

    ERIC Educational Resources Information Center

    Ho, Kwok Keung, Ed.

    2000-01-01

    This document contains the May and November 2000 issues of "New Horizons in Education," with articles in English and Chinese. The May issue includes the following articles: "A Key to Successful Environmental Education: Teacher Trainees' Attitude, Behaviour, and Knowledge" (Kevin Chung Wai Lui, Eric Po Keung Tsang, Sing Lai…

  19. A BCS-like gap in the superconductor SmFeAsO0.85F0.15.

    PubMed

    Chen, T Y; Tesanovic, Z; Liu, R H; Chen, X H; Chien, C L

    2008-06-26

    Since the discovery of superconductivity in the high-transition-temperature (high-T(c)) copper oxides two decades ago, it has been firmly established that the CuO(2) plane is essential for superconductivity and gives rise to a host of other very unusual properties. A new family of superconductors with the general composition of LaFeAsO(1-x)F(x) has recently been discovered and the conspicuous lack of the CuO(2) planes raises the tantalizing question of a different pairing mechanism in these oxypnictides. The superconducting gap (its magnitude, structure, and temperature dependence) is intimately related to pairing. Here we report the observation of a single gap in the superconductor SmFeAsO(0.85)F(0.15) with T(c) = 42 K as measured by Andreev spectroscopy. The gap value of 2Delta = 13.34 +/- 0.3 meV gives 2Delta/k(B)T(c) = 3.68 (where k(B) is the Boltzmann constant), close to the Bardeen-Cooper-Schrieffer (BCS) prediction of 3.53. The gap decreases with temperature and vanishes at T(c) in a manner consistent with the BCS prediction, but dramatically different from that of the pseudogap behaviour in the copper oxide superconductors. Our results clearly indicate a nodeless gap order parameter, which is nearly isotropic in size across different sections of the Fermi surface, and are not compatible with models involving antiferromagnetic fluctuations, strong correlations, the t-J model, and the like, originally designed for the high-T(c) copper oxides.

  20. Magnetization reversal behavior and magnetocaloric effect in SmCr0.85Mn0.15O3 chromites

    NASA Astrophysics Data System (ADS)

    Kumar, Surendra; Coondoo, Indrani; Vasundhara, M.; Patra, Ajit K.; Kholkin, Andrei L.; Panwar, Neeraj

    2017-01-01

    We have synthesized SmCr0.85Mn0.15O3 (SCMO) chromites through the ceramic route. The compound crystallized into a distorted orthorhombic structure with the Pnma space group, which was confirmed from the Rietveld refinement of x-ray powder diffraction patterns. Neel temperature, noticed at 168 K from the temperature variation of magnetisation, smaller than that reported for SmCrO3, indicated the influence of Mn3+ substitution on decreasing the antiferromagnetic ordering. A phenomenon of magnetization reversal was observed in the SCMO compound. At low magnetic fields, i.e., 500 Oe, a single compensation temperature (defined as the temperature where magnetization became zero) around 106 K was observed in the field cooled magnetization curve. However, with the application of higher magnetic fields, i.e., under an applied field of 1000 Oe, a second compensation temperature was noticed around 8 K. With a further increase in the magnetic field, the magnetization remained positive in both field cooled and zero field cooled protocols. A normal magnetocaloric effect was observed through an indirect method of field dependence of magnetisation measured in the temperature range of 2-152 K. The magnetic entropy change (-ΔS) of ˜11.36 J kg-1 K-1 along with the relative cooling power (RCP) of ˜175.89 J kg-1 was obtained in the temperature range of 10-20 K for an applied field of 90 kOe, and their values at 50 kOe applied field were, respectively, almost twenty and forty times larger in magnitude in comparison to those for the SmCrO3 compound. The relatively large values of ΔS and RCP make the studied compound a potential candidate for magnetic refrigeration applications at low temperatures.

  1. BACE0.85Y0.15O3-DELTA Based Materials for Inovative Monolithic Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Krezhov, Kiril; Vladikova, Daria

    2016-07-01

    Solid oxide fuel cells (SOFCs) offer a promising green technology of direct conversion of chemical energy of fuel into electricity. Among the families of metal oxides, which can be successfully used as electrodes (cathodes or anodes) in SOFC, certain members of the large family of transition-metal oxides with perovskite structure ABO _{3} were found very prospective to fulfil most of the features required for preparation of mixed ionic-electronic conductor (MIEC) oxide materials for SOFCs operated in the intermediate temperature range. In this regard Barium cerate with Y-substitution at the B-site (Ce site) is well known for excellent conduction capabilities in the temperature range 400-800 °C as a result from the proton motion in the crystal lattice. Doping with Y ^{3+} is very effective and the proton conductivity in BaCe _{1-x}Y _{x}O _{3-δ} increases with the increasing of the dopant concentration up to x =0.2. However, the phase behaviour of the composition BCY20 (x=0.20) is very complicated. Even at room temperature the crystalline structure remains contradictory because various structures of monoclinic, rhombohedral and orthorhombic symmetry are reported. The characterization of the chemical composition and stability, oxygen stoichiometry and cationic ratios of each synthesized phase is of great importance to understand the defect-chemistry that would govern the transport properties. We report on oxygen-deficient BaCe _{0.85}Y _{0.15}O _{3-δ} (BCY15) perovskites prepared by auto-combustion with following calcination at high temperature. The structural details of powder, dense and porous samples of materials based on BCY15 were investigated from full profile analysis of neutron and x-ray diffraction patterns. The materials were used recently as cathode, anode and central membrane in an innovative monolithic design of SOFC.

  2. The Malcolm horizon: History and future

    NASA Technical Reports Server (NTRS)

    Malcolm, R.

    1984-01-01

    The development of the Malcolm Horizon, a peripheral vision horizon used in flight simulation, is discussed. A history of the horizon display is presented as well as a brief overview of vision physiology, and the role balance plays is spatial orientation. Avenues of continued research in subconscious cockpit instrumentation are examined.

  3. Transparent magnetic state in single crystal Nd(1.85)Ce(0.15)CuO(4-y) superconductors

    NASA Technical Reports Server (NTRS)

    Zuo, F.

    1995-01-01

    Several experimental studies have been reported as evidence of Josephson coupling between the superconducting layers in the highly anisotropic oxide such as the Bi2Sr2CaCu2O8 and Tl2Ba2CuO6 systems. These include the large penetration depth of 100 mu m measured, ac and dc Josephson effects. Recently two critical temperatures corresponding to Josephson coupling in between the layers and the Berezinskii-Kosterlitz-Thouless transition in the ab-plane have been directly observed in the transport measurements. If the field is applied parallel to the superconducting layers, the magnetic excitation is not the conventional Abrikosov vortices, but the Josephson vortices which extend lambda(sub ab) in the c-axis direction and lambda(sub J) = gamma s in the plane (s is the interlayer distance, gamma is the anisotropy constant). Because of the weak screening effect associated with the Josephson vortices, there have been predictions of magnetic transparent states at magnetic field above a characteristic field H(sub J), a behavior distinctively different from that of the type-II superconductors. In this paper, we report an experimental result which illustrates a transition from the Meissner state to the magnetic transparent state in single crystal of Nd(1.85)Ce(0.15)CuO(4-y). Magnetization has been measured as a function of temperature and field in the magnetic field parallel or close to ab-plane geometry. For a fixed magnetic field, the magnetization shows a two-step transition in M(T); for a fixed temperature, the magnetization shows an abrupt change to almost zero value above a characteristic field H(sub J), an indication of magnetic transparent state. The data of magnetization as a function of field clearly deviates from the behavior predicted by the Abrikosov theory for type-II superconductors. Instead, the data fit well into the picture of Josephson decoupling between the CuO2 layers.

  4. Penrose inequality and apparent horizons

    SciTech Connect

    Ben-Dov, Ishai

    2004-12-15

    A spherically symmetric spacetime is presented with an initial data set that is asymptotically flat, satisfies the dominant energy condition, and such that on this initial data M<{radical}(A/16{pi}), where M is the total mass and A is the area of the apparent horizon. This provides a counterexample to a commonly stated version of the Penrose inequality, though it does not contradict the true Penrose inequality.

  5. Toroidal horizons in binary black hole mergers

    NASA Astrophysics Data System (ADS)

    Bohn, Andy; Kidder, Lawrence E.; Teukolsky, Saul A.

    2016-09-01

    We find the first binary black hole event horizon with a toroidal topology. It has been predicted that generically the event horizons of merging black holes should briefly have a toroidal topology. However, such a phase has never been seen in numerical simulations. Instead, in all previous simulations, the topology of the event horizon transitions directly from two spheres during the inspiral to a single sphere as the black holes merge. We find a coordinate transformation to a foliation of spacelike hypersurfaces that "cut a hole" through the event horizon surface, resulting in a toroidal event horizon, thus reconciling the numerical work with theoretical expectations. The demonstration requires extremely high numerical precision, which is made possible by a new event horizon code described in a companion paper. A torus could potentially provide a mechanism for violating topological censorship. However, these toroidal event horizons satisfy topological censorship by construction, because we can always trivially apply the inverse coordinate transformation to remove the topological feature.

  6. New Horizons Launch Contingency Effort

    NASA Astrophysics Data System (ADS)

    Chang, Yale; Lear, Matthew H.; McGrath, Brian E.; Heyler, Gene A.; Takashima, Naruhisa; Owings, W. Donald

    2007-01-01

    On 19 January 2006 at 2:00 PM EST, the NASA New Horizons spacecraft (SC) was launched from the Cape Canaveral Air Force Station (CCAFS), FL, onboard an Atlas V 551/Centaur/STAR™ 48B launch vehicle (LV) on a mission to explore the Pluto Charon planetary system and possibly other Kuiper Belt Objects. It carried a single Radioisotope Thermoelectric Generator (RTG). As part of the joint NASA/US Department of Energy (DOE) safety effort, contingency plans were prepared to address the unlikely events of launch accidents leading to a near-pad impact, a suborbital reentry, an orbital reentry, or a heliocentric orbit. As the implementing organization. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) had expanded roles in the New Horizons launch contingency effort over those for the Cassini mission and Mars Exploration Rovers missions. The expanded tasks included participation in the Radiological Control Center (RADCC) at the Kennedy Space Center (KSC), preparation of contingency plans, coordination of space tracking assets, improved aerodynamics characterization of the RTG's 18 General Purpose Heat Source (GPHS) modules, and development of spacecraft and RTG reentry breakup analysis tools. Other JHU/APL tasks were prediction of the Earth impact footprints (ElFs) for the GPHS modules released during the atmospheric reentry (for purposes of notification and recovery), prediction of the time of SC reentry from a potential orbital decay, pre-launch dissemination of ballistic coefficients of various possible reentry configurations, and launch support of an Emergency Operations Center (EOC) on the JHU/APL campus. For the New Horizons launch, JHU/APL personnel at the RADCC and at the EOC were ready to implement any real-time launch contingency activities. A successful New Horizons launch and interplanetary injection precluded any further contingency actions. The New Horizons launch contingency was an interagency effort by several organizations. This paper

  7. Optical Characterization and 2,525 micron Lasing of Cr(2+):Cd(0.85)Mn(0.15)Te

    NASA Technical Reports Server (NTRS)

    Davis, V. R.; Wu, X.; Hoemmerich, U.; Trivedi, S. B.; Grasza, K.; Yu, Z.

    1997-01-01

    static acentric electric crystal field or the coupling of asymmetric phonons can force electric-dipole transitions by the admixture of wave functions with opposite parity. Tetrahedral sites lack inversion symmetry which provides the odd-parity field necessary to relax the parity selection rule. Therefore, high absorption and emission cross sections are observed. An enhanced radiative emission rate is also expected to reduce the detrimental effect of non-radiative decay. Motivated by the initial results on Cr doped ZnS and ZnSe, we have started a comprehensive effort to study Cr(2+) doped II-VI semiconductors for solid-state laser applications. In this paper we present the optical properties and the demonstration of mid-infrared lasing from Cr doped Cd(0.85)Mn(0.15)Te.

  8. A Randomized Multicenter Study Comparing 0.1%, 0.15%, and 0.3% Sodium Hyaluronate with 0.05% Cyclosporine in the Treatment of Dry Eye

    PubMed Central

    Park, Yuli; Song, Jong Suk; Choi, Chul Young; Yoon, Kyung Chul; Lee, Hyung Keun

    2017-01-01

    Abstract Purpose: To investigate the efficacy of 0.1%, 0.15%, and 0.3% sodium hyaluronate (SH) artificial tears compared with 0.05% cyclosporine (CS) ophthalmic solution for the treatment of dry eye. Methods: One hundred seventy-six patients were recruited and randomized to receive of 0.1%, 0.15%, and 0.3% SH and 0.05% CS. There was a primary end point which is the changes in the fluorescein corneal staining (FCS) score to determine noninferiority of 0.1%, 0.15%, and 0.3% SH. Secondary objective end points were lissamine green conjunctival staining (LGCS) scores, Schirmer test, and tear film break-up time (TBUT). Secondary subjective end point was ocular surface disease index (OSDI) score. These were evaluated before treatment and 6 and 12 weeks after start of treatment. Results: In the primary analysis, the mean change from baseline in FCS scores verified noninferiority of 0.1% and 0.15% SH to 0.05% CS and also indicated significant improvement of all groups (P < 0.05). Values for TBUT, LGCS scores, and OSDI scores showed significant improvements in all groups (P < 0.05), although no significant intergroup difference was shown. However, Schirmer test scores in the 0.15% SH group showed a significant tendency for better improvement at week 12 compared with the other groups (P < 0.05). No serious adverse events were observed. Conclusions: Administration of 0.1%, 0.15%, and 0.3% SH was effective in improving both the objective signs and subjective symptoms of dry eye. Those findings, in addition to the well-tolerated profile of 0.1%, 0.15%, and 0.3% SH, show that it is effective therapeutic method for dry eye. PMID:27929721

  9. Horizon dynamics of distorted rotating black holes

    SciTech Connect

    Chu, Tony; Cohen, Michael I.; Pfeiffer, Harald P.

    2011-05-15

    We present numerical simulations of a rotating black hole distorted by a pulse of ingoing gravitational radiation. For strong pulses, we find up to five concentric marginally outer trapped surfaces. These trapped surfaces appear and disappear in pairs, so that the total number of such surfaces at any given time is odd. The world tubes traced out by the marginally outer trapped surfaces are found to be spacelike during the highly dynamical regime, approaching a null hypersurface at early and late times. We analyze the structure of these marginally trapped tubes in the context of the dynamical horizon formalism, computing the expansion of outgoing and incoming null geodesics, as well as evaluating the dynamical horizon flux law and the angular momentum flux law. Finally, we compute the event horizon. The event horizon is well-behaved and approaches the apparent horizon before and after the highly dynamical regime. No new generators enter the event horizon during the simulation.

  10. Variable horizon in a peridynamic medium

    DOE PAGES

    Silling, Stewart A.; Littlewood, David J.; Seleson, Pablo

    2015-12-10

    Here, a notion of material homogeneity is proposed for peridynamic bodies with variable horizon but constant bulk properties. A relation is derived that scales the force state according to the position-dependent horizon while keeping the bulk properties unchanged. Using this scaling relation, if the horizon depends on position, artifacts called ghost forces may arise in a body under a homogeneous deformation. These artifacts depend on the second derivative of the horizon and can be reduced by employing a modified equilibrium equation using a new quantity called the partial stress. Bodies with piecewise constant horizon can be modeled without ghost forcesmore » by using a simpler technique called a splice. As a limiting case of zero horizon, both the partial stress and splice techniques can be used to achieve local-nonlocal coupling. Computational examples, including dynamic fracture in a one-dimensional model with local-nonlocal coupling, illustrate the methods.« less

  11. Variable horizon in a peridynamic medium

    SciTech Connect

    Silling, Stewart A.; Littlewood, David J.; Seleson, Pablo

    2015-12-10

    Here, a notion of material homogeneity is proposed for peridynamic bodies with variable horizon but constant bulk properties. A relation is derived that scales the force state according to the position-dependent horizon while keeping the bulk properties unchanged. Using this scaling relation, if the horizon depends on position, artifacts called ghost forces may arise in a body under a homogeneous deformation. These artifacts depend on the second derivative of the horizon and can be reduced by employing a modified equilibrium equation using a new quantity called the partial stress. Bodies with piecewise constant horizon can be modeled without ghost forces by using a simpler technique called a splice. As a limiting case of zero horizon, both the partial stress and splice techniques can be used to achieve local-nonlocal coupling. Computational examples, including dynamic fracture in a one-dimensional model with local-nonlocal coupling, illustrate the methods.

  12. Variable horizon in a peridynamic medium.

    SciTech Connect

    Silling, Stewart Andrew; Littlewood, David John; Seleson, Pablo

    2014-10-01

    A notion of material homogeneity is proposed for peridynamic bodies with vari- able horizon but constant bulk properties. A relation is derived that scales the force state according to the position-dependent horizon while keeping the bulk properties un- changed. Using this scaling relation, if the horizon depends on position, artifacts called ghost forces may arise in a body under homogeneous deformation. These artifacts de- pend on the second derivative of horizon and can be reduced by use of a modified equilibrium equation using a new quantity called the partial stress . Bodies with piece- wise constant horizon can be modeled without ghost forces by using a technique called a splice between the regions. As a limiting case of zero horizon, both partial stress and splice techniques can be used to achieve local-nonlocal coupling. Computational examples, including dynamic fracture in a one-dimensional model with local-nonlocal coupling, illustrate the methods.

  13. The pedogeochemical segregation a few horizons in soils from glass houses

    NASA Astrophysics Data System (ADS)

    Bulgariu, Dumitru; Rusu, Constantin; Filipov, Feodor; Buzgar, Nicolae; Bulgariu, Laura

    2010-05-01

    Our studies have focused the apparition and manifestation conditions of pedogeochemical segregation phenomena in case of soils from Copou - Iaşi, Bacău and Bârlad (Romania) glass house, and the effects of this on the pedogeochemical and agrochemical characteristics of soils from glass houses cultivated with vegetables. The utilization of intensive cultivation technologies of vegetables in glass houses determined the degradation of morphological, physical and chemical characteristics of soils, by rapid evolution of salted processes (salinization and / or sodization), compaction, carbonatation, eluviation-illuviation, frangipane formation, stagnogleization, gleization etc. Under these conditions, at depth of 30-40 cm is formed a compact and impenetrable horizon - Ahok(x) horizon. In function of exploitation conditions and by the chemical-mineralogical characteristics of soils from glasshouses, the Ahok horizons can have frangipane properties, expressed more or less. These horizons determined a geochemical segregation of soils from glass houses: (i) superior horizons, above Ahok(x) horizon evolve in weak oxidative conditions, weak alkaline pH, higher salinity, humidity and temperature; (ii) inferior horizons, below Ahok(x) horizon evolve in weak reducing conditions weak acid pH, lower salinity, humidity and temperature. Concomitant with the development of Ahok(x) horizons, the rapid degradation of the properties of soils from glasshouses is observed. The aspects about the formation of frangipane horizon in soils from glasshouses are not yet sufficiently know. Whatever of the formation processes, the frangipane horizons determined a sever segregation in pedogeochemical evolution of soils from glass houses, with very important consequences on the agrochemical quality of these soils. The segregation effects are manifested in the differential dynamics of pedogeochemical processes from superior horizons (situated above the segregation horizon), in comparison with the

  14. Theory underlying the peripheral vision horizon device

    NASA Technical Reports Server (NTRS)

    Money, K. E.

    1984-01-01

    Peripheral Vision Horizon Device (PVHD) theory states that the likelihood of pilot disorientation in flight is reduced by providing an artificial horizon that provides orientation information to peripheral vision. In considering the validity of the theory, three areas are explored: the use of an artificial horizon device over some other flight instrument; the use of peripheral vision over foveal vision; and the evidence that peripheral vision is well suited to the processing of orientation information.

  15. Noncommutativity in near horizon symmetries in gravity

    NASA Astrophysics Data System (ADS)

    Majhi, Bibhas Ranjan

    2017-02-01

    We have a new observation that near horizon symmetry generators, corresponding to diffeomorphisms which leave the horizon structure invariant, satisfy noncommutative Heisenberg algebra. The results are valid for any null surfaces (which have Rindler structure in the near null surface limit) and in any spacetime dimensions. Using the Sugawara construction technique the central charge is identified. It is shown that the horizon entropy is consistent with the standard form of the Cardy formula. Therefore we feel that the noncommutative algebra might lead to quantum mechanics of horizon and also can probe into the microscopic description of entropy.

  16. Smooth horizons and quantum ripples

    NASA Astrophysics Data System (ADS)

    Golovnev, Alexey

    2015-05-01

    Black holes are unique objects which allow for meaningful theoretical studies of strong gravity and even quantum gravity effects. An infalling and a distant observer would have very different views on the structure of the world. However, a careful analysis has shown that it entails no genuine contradictions for physics, and the paradigm of observer complementarity has been coined. Recently this picture was put into doubt. In particular, it was argued that in old black holes a firewall must form in order to protect the basic principles of quantum mechanics. This AMPS paradox has already been discussed in a vast number of papers with different attitudes and conclusions. Here we want to argue that a possible source of confusion is the neglect of quantum gravity effects. Contrary to widespread perception, it does not necessarily mean that effective field theory is inapplicable in rather smooth neighbourhoods of large black hole horizons. The real offender might be an attempt to consistently use it over the huge distances from the near-horizon zone of old black holes to the early radiation. We give simple estimates to support this viewpoint and show how the Page time and (somewhat more speculative) scrambling time do appear.

  17. GaP ring-like nanostructures on GaAs (100) with In{sub 0.15}Ga{sub 0.85}As compensation layers

    SciTech Connect

    Prongjit, Patchareewan Pankaow, Naraporn Boonpeng, Poonyasiri Thainoi, Supachok Panyakeow, Somsak Ratanathammaphan, Somchai

    2013-12-04

    We present the fabrication of GaP ring-like nanostructures on GaAs (100) substrates with inserted In{sub 0.15}Ga{sub 0.85}As compensation layers. The samples are grown by droplet epitaxy using solid-source molecular beam epitaxy. The dependency of nanostructural and optical properties of GaP nanostructures on In{sub 0.15}Ga{sub 0.85}As layer thickness is investigated by ex-situ atomic force microscope (AFM) and photoluminescence (PL). It is found that the characteristics of GaP ring-like structures on GaAs strongly depend on the In{sub 0.15}Ga{sub 0.85}As layer thickness.

  18. Displacement waves in La2CuO(4-delta) and La(1.85)Sr(0.15)CuO(4-delta)

    NASA Astrophysics Data System (ADS)

    Kajitani, Tsuyoshi; Onozuka, Takashi; Yamaguchi, Yasuo; Hirabayashi, Makoto; Syono, Yasuhiko

    1987-11-01

    Structural investigation of orthorhombic La2CuO(4-delta) and La(1.85)Sr(0.15)CuO(4-delta) was carried out by means of X-ray and neutron diffraction on the basis of the space group Cmmm. The periodic expansion/contraction type distortion of CuO6 octahedra was found in both orthorhombic compounds. The distortion is nearly one-dimensional in La2CuO(4-delta) but is two-dimensional in La(1.85)Sr(0.15)CuO(4-delta). The existence of a charge-density wave is highly possible in the structures.

  19. Strain-relaxation and critical thickness of epitaxial La1.85Sr0.15CuO4 films

    DOE PAGES

    Meyer, Tricia L; Jiang, Lu; Park, Sungkyun; ...

    2015-12-08

    We report the thickness-dependent strain-relaxation behavior and the associated impacts upon the superconductivity in epitaxial La1.85Sr0.15CuO4 films grown on different substrates, which provide a range of strain. We have found that the critical thickness for the onset of superconductivity in La1.85Sr0.15CuO4 films is associated with the finite thickness effect and epitaxial strain. In particular, thin films with tensile strain greater than ~0.25% revealed no superconductivity. We attribute this phenomenon to the inherent formation of oxygen vacancies that can be minimized via strain relaxation.

  20. The nonlinear and saturable absorption characteristics of Ga0.90In0.10Se and Ga0.85In0.15Se semiconductor crystals and their amorphous thin films

    NASA Astrophysics Data System (ADS)

    Karatay, Ahmet; Aksoy, Çagla; Gul Yaglioglu, H.; Elmali, Ayhan; Kürüm, Ulaş; Ateş, Aytunç; Gasanly, Nizami

    2011-07-01

    We investigated the nonlinear and saturable absorption characteristics of Ga0.90In0.10Se and Ga0.85In0.15Se semiconductor crystals and their very thin amorphous films by open aperture (OA) Z-scan and pump-probe techniques. The linear absorption spectra indicated a blue shift in energy with increasing film thickness. This can be attributed to the quantum confinement effect. For both 4 ns and 65 ps pulse durations the two photon absorption coefficients of Ga0.90In0.10Se and Ga0.85In0.15Se crystals increased with increasing input intensities. The life time of the localized defect states was measured as 3 ns for both Ga0.90In0.10Se and Ga0.85In0.15Se films while it was around 10 ns for GaSe and InSe films. Open aperture Z-scan experiments with a 4 ns pulse duration did not exhibit any saturable absorption behavior for thin films since the life time of localized defect states was not long enough to saturate these films. Thinner films exhibited saturable absorption and thicker films exhibited nonlinear absorption for a 65 ps pulse duration. This behavior was attributed to increasing localized defect states with increasing film thickness. The experimental curves were fitted to the theory of the open aperture Gaussian-beam Z-scan based on the Adomian decomposition method incorporating one photon, two photon, and free carrier absorptions and their saturations. The lowest saturation intensity threshold for the Ga0.90In0.10Se film was found to be 1.38 × 102 MW cm - 2 for 43 nm film thickness.

  1. Clouds Move Across Mars Horizon

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This sequence combines 32 images of clouds moving eastward across a Martian horizon. The Surface Stereo Imager on NASA's Phoenix Mars Lander took this set of images on Sept. 18, 2008, during early afternoon hours of the 113th Martian day of the mission.

    The view is toward the north. The actual elapsed time between the first image and the last image is nearly half an hour. The numbers inset at lower left are the elapsed time, in seconds, after the first image of the sequence. The particles in the clouds are water-ice, as in cirrus clouds on Earth.

    Phoenix landed in the northern region of Mars on May 25, 2008. The mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is led by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development was by Lockheed Martin Space Systems, Denver.

  2. The NMC Horizon Report: 2014 Library Edition

    ERIC Educational Resources Information Center

    Johnson, L.; Adams Becker, S.; Estrada, V.; Freeman, A.

    2014-01-01

    The internationally recognized "NMC Horizon Report" series and regional "NMC Technology Outlooks" are part of the NMC Horizon Project, a 12-year effort established in 2002 that annually identifies and describes emerging technologies likely to have a large impact over the coming five years in every sector of education around the…

  3. Horizon Report: 2009 Economic Development Edition

    ERIC Educational Resources Information Center

    Johnson, L.; Levine, A.; Scott, C.; Smith, R.; Stone, S.

    2009-01-01

    The New Media Consortium's Horizon Project is an ongoing research project that seeks to identify and describe emerging technologies likely to have a large impact in education and other industries around the world over a five-year time period. The chief products of the project are the "Horizon Reports", an annual series of publications…

  4. The NMC Horizon Report: 2015 Museum Edition

    ERIC Educational Resources Information Center

    Johnson, L.; Adams Becker, S.; Estrada, V.; Freeman, A.

    2015-01-01

    The internationally recognized series of "Horizon Reports" is part of the New Media Consortium's Horizon Project, a comprehensive research venture established in 2002 that identifies and describes emerging technologies likely to have a large impact over the coming years on a variety of sectors around the globe. This "2015 Horizon…

  5. The Horizon Report: 2010 Museum Edition

    ERIC Educational Resources Information Center

    Johnson, L.; Witchey, H.; Smith, R.; Levine, A.; Haywood, K.

    2010-01-01

    The internationally recognized series of "Horizon Reports" is part of the New Media Consortium's Horizon Project, a comprehensive research venture established in 2002 that identifies and describes emerging technologies likely to have a large impact over the coming five years on a variety of sectors around the globe. This volume, the "2010 Horizon…

  6. Expanding your horizons in science and mathematics

    NASA Technical Reports Server (NTRS)

    Palmer, Cynthia E. A.

    1995-01-01

    The purpose of the 'Expanding Your Horizons in Science and Mathematics' program is to interest young women in grades six through twelve in a variety of careers where mathematics and science are important. Progress in encouraging young women to take courses in mathematics, science, and technological subjects is discussed. Also included are adult, student, and organizational information packets used for 'Expanding Your Horizons' conferences.

  7. Effects of NiO on the conductivity of Ce0.85Sm0.15O1.925 and on electrochemical properties of the cathode/electrolyte interface

    NASA Astrophysics Data System (ADS)

    Wang, Haopeng; Liu, Xiaomei; Bi, Hailin; Yu, Shenglong; Han, Fei; Sun, Jialing; Zhu, Lili; Yu, Huamin; Pei, Li

    2016-07-01

    Ce0.85Sm0.15O1.925 (SDC) and Ce0.85Sm0.15O1.925-0.5 at.% NiO (SDCN) are investigated as electrolytes for solid oxide fuel cells (SOFCs). Impedance spectroscopy measurements reveal that the grain boundary resistance can be significantly reduced by adding 0.5 at.% NiO to SDC. Symmetric cells of the BaCo0.7Fe0.2Nb0.1O3-δ (BCFN) electrode on SDC and SDCN electrolytes are fabricated and the electrochemical properties of the electrode/electrolyte interface are investigated. The polarization resistance of the BCFN electrode on the SDCN electrolyte is much lower than that of the BCFN electrode on the SDC electrolyte, mainly because of the increase in the electrolyte conductivity and the decrease in the Si content at the electrode/electrolyte interface. NiO is able to restrict the diffusion of the siliceous impurity from the electrolyte to the electrode/electrolyte interface. Single cells based on SDC and SDCN electrolytes are fabricated using Ni0.9Cu0.1Ox-SDC as the anode and BCFN as the cathode. At 800 °C, the maximum power density of the SDCN-based cell is 0.745 W cm-2, which is much higher than that of the SDC-based cell.

  8. Energy-storage properties and electrocaloric effect of Pb(1-3x/2)LaxZr0.85Ti0.15O3 antiferroelectric thick films.

    PubMed

    Zhao, Ye; Hao, Xihong; Zhang, Qi

    2014-07-23

    Antiferroelectric (AFE) thick (1 μm) films of Pb(1-3x/2)LaxZr0.85Ti0.15O3 (PLZT) with x = 0.08, 0.10, 0.12, and 0.14 were deposited on LaNiO3/Si (100) substrates by a sol-gel method. The dielectric properties, energy-storage performance, electrocaloric effect, and leakage current behavior were investigated in detail. With increasing La content, dielectric constant and saturated polarizations of the thick films were gradually decreased. A maximum recoverable energy-storage density of 38 J/cm(3) and efficiency of 71% were achieved in the thick films with x = 0.12 at room temperature. A large reversible adiabatic temperature change of ΔT = 25.0 °C was presented in the thick films with x = 0.08 at 127 °C at 990 kV/cm. Moreover, all the samples had a lower leakage current density below 10(-6) A/cm(2) at room temperature. These results indicated that the PLZT AFE thick films could be a potential candidate for applications in high energy-storage density capacitors and cooling devices.

  9. Huge critical current density and tailored superconducting anisotropy in SmFeAsO0.8F0.15 by low-density columnar-defect incorporation

    NASA Astrophysics Data System (ADS)

    Fang, L.; Jia, Y.; Mishra, V.; Chaparro, C.; Vlasko-Vlasov, V. K.; Koshelev, A. E.; Welp, U.; Crabtree, G. W.; Zhu, S.; Zhigadlo, N. D.; Katrych, S.; Karpinski, J.; Kwok, W. K.

    2013-11-01

    Iron-based superconductors could be useful for electricity distribution and superconducting magnet applications because of their relatively high critical current densities and upper critical fields. SmFeAsO0.8F0.15 is of particular interest as it has the highest transition temperature among these materials. Here we show that by introducing a low density of correlated nano-scale defects into this material by heavy-ion irradiation, we can increase its critical current density to up to 2 × 107 A cm-2 at 5 K—the highest ever reported for an iron-based superconductor—without reducing its critical temperature of 50 K. We also observe a notable reduction in the thermodynamic superconducting anisotropy, from 8 to 4 upon irradiation. We develop a model based on anisotropic electron scattering that predicts that the superconducting anisotropy can be tailored via correlated defects in semimetallic, fully gapped type II superconductors.

  10. Multiferroic and magnetoelectric properties of Ba0.85Ca0.15Zr0.1Ti0.9O3-CoFe2O4 core-shell nanocomposite

    NASA Astrophysics Data System (ADS)

    Kumar, Ajith S.; Lekha, C. S. Chitra; Vivek, S.; Saravanan, Venkata; Nandakumar, K.; Nair, Swapna S.

    2016-11-01

    Lead-free magnetoelectric (ME) composites with remarkable ME coupling are required for the realization of eco-friendly multifunctional devices. This work demonstrates the ME properties of Ba0.85Ca0.15Zr0.1Ti0.9O3-CoFe2O4 (BCZT-CFO) core-shell composites synthesized via co-sol-gel technique. Room temperature ferroelectric and ferromagnetic characterization have shown that the samples are magnetic and ferroelectric along with an adequate magnetoelectric coupling of 12.15 mV/(cm Oe). The strong dependence of electric parameters on applied magnetic DC bias fields demonstrated in ferroelectric and magnetoelectric measurements provide a framework for the development of potential magnetoelectric devices. Also, the high sensitivity of magnetoelectric coupling towards the applied AC magnetic field can be used for its application in magnetoelectric sensors.

  11. Microbial community composition shapes enzyme patterns in topsoil and subsoil horizons along a latitudinal transect in Western Siberia.

    PubMed

    Schnecker, Jörg; Wild, Birgit; Takriti, Mounir; Eloy Alves, Ricardo J; Gentsch, Norman; Gittel, Antje; Hofer, Angelika; Klaus, Karoline; Knoltsch, Anna; Lashchinskiy, Nikolay; Mikutta, Robert; Richter, Andreas

    2015-04-01

    Soil horizons below 30 cm depth contain about 60% of the organic carbon stored in soils. Although insight into the physical and chemical stabilization of soil organic matter (SOM) and into microbial community composition in these horizons is being gained, information on microbial functions of subsoil microbial communities and on associated microbially-mediated processes remains sparse. To identify possible controls on enzyme patterns, we correlated enzyme patterns with biotic and abiotic soil parameters, as well as with microbial community composition, estimated using phospholipid fatty acid profiles. Enzyme patterns (i.e. distance-matrixes calculated from these enzyme activities) were calculated from the activities of six extracellular enzymes (cellobiohydrolase, leucine-amino-peptidase, N-acetylglucosaminidase, chitotriosidase, phosphatase and phenoloxidase), which had been measured in soil samples from organic topsoil horizons, mineral topsoil horizons, and mineral subsoil horizons from seven ecosystems along a 1500 km latitudinal transect in Western Siberia. We found that hydrolytic enzyme activities decreased rapidly with depth, whereas oxidative enzyme activities in mineral horizons were as high as, or higher than in organic topsoil horizons. Enzyme patterns varied more strongly between ecosystems in mineral subsoil horizons than in organic topsoils. The enzyme patterns in topsoil horizons were correlated with SOM content (i.e., C and N content) and microbial community composition. In contrast, the enzyme patterns in mineral subsoil horizons were related to water content, soil pH and microbial community composition. The lack of correlation between enzyme patterns and SOM quantity in the mineral subsoils suggests that SOM chemistry, spatial separation or physical stabilization of SOM rather than SOM content might determine substrate availability for enzymatic breakdown. The correlation of microbial community composition and enzyme patterns in all horizons

  12. Multi-Bandwidth GPR Profiles of Granite in New Hampshire: Attributes of Fracture Horizons and Wavelets

    NASA Astrophysics Data System (ADS)

    Arcone, S. A.; Campbell, S. W.

    2012-12-01

    Sheet and tectonic fractures transport water and facilitate erosion on geologic time scales. We discuss ground-penetrating radar profiles of fractures recorded with 150, 350, 600 and 1000 MHz pulse dominant frequencies, and quantitative data obtained from their horizons and pulse wavelet attributes. We recorded the profiles along dirt roads and bare rock transects, beneath which include the mid Ordovician Oliverian granodiorite and binary granite of western New Hampshire and just north of the Presidential Range, respectively, and the late Devonian biotite granite just west of the Presidential Range. The overriding till is characterized by numerous diffractions, and from 0 to about 5 m thick. We use a known relative dielectric permittivity of 6.6 for granodiorite and assume the same for the other types to calibrate depth from the reflection time scale. Dielectric permittivity values for the till range from about 13-21. The sheet fracture responses are up to 25 m deep while the deepest tectonic fracture horizon extends to at least 35 m depth. Some horizons are associated with numerous diffractions originating along their length, while others have very few. The less clear horizons recorded in seasonal profiles of the binary granite suggest grusification, a possible factor to help explain the greater height of the more durable metamorphic Presidential Range. Sheet fracture spacing can be closer than one meter, with horizons comprised of thin layer responses because the wavelets, even at 1000 MHz, are similar to the transmitted wavelet. Therefore, the fractures are likely less than a few cm thick, as is apparent from quarry wall exposures, and from models that predict that even one mm fractures are detectable. The wavelet phase structure generally indicates a higher dielectric medium, which could mean calcite, and more likely water, but this structure is not consistent along individual horizons. The higher frequency profiles reveal a complex fracture network that

  13. Influences upon the lead isotopic composition of organic and mineral horizons in soil profiles from the National Soil Inventory of Scotland (2007-09).

    PubMed

    Farmer, John G; Graham, Margaret C; Eades, Lorna J; Lilly, Allan; Bacon, Jeffrey R

    2016-02-15

    Some 644 individual soil horizons from 169 sites in Scotland were analyzed for Pb concentration and isotopic composition. There were three scenarios: (i) 36 sites where both top and bottom (i.e. lowest sampled) soil horizons were classified as organic in nature, (ii) 67 with an organic top but mineral bottom soil horizon, and (iii) 66 where both top and bottom soil horizons were mineral. Lead concentrations were greater in the top horizon relative to the bottom horizon in all but a few cases. The top horizon (206)Pb/(207)Pb ratio was lesser (outside analytical error) than the corresponding bottom horizon (206)Pb/(207)Pb ratio at (i) 64%, (ii) 94% and (iii) 73% of sites, and greater at only (i) 8%, (ii) 3% and (iii) 8% of sites. A plot of (208)Pb/(207)Pb vs. (208)Pb/(206)Pb ratios showed that the Pb in organic top (i, ii) and bottom (i) horizons was consistent with atmospherically deposited Pb of anthropogenic origin. The (206)Pb/(207)Pb ratio of the organic top horizon in (ii) was unrelated to the (206)Pb/(207)Pb ratio of the mineral bottom horizon as demonstrated by the geographical variation in the negative shift in the ratio, a result of differences in the mineral horizon values arising from the greater influence of radiogenic Pb in the north. In (iii), the lesser values of the (206)Pb/(207)Pb ratio for the mineral top horizon relative to the mineral bottom horizon were consistent with the presence of anthropogenic Pb, in addition to indigenous Pb, in the former. Mean anthropogenic Pb inventories of 1.5 and 4.5 g m(-2) were obtained for the northern and southern halves of Scotland, respectively, consistent with long-range atmospheric transport of anthropogenic Pb (mean (206)Pb/(207)Pb ratio~1.16). For cultivated agricultural soils (Ap), this corresponded to about half of the total Pb inventory in the top 30 cm of the soil column.

  14. Quasilocal approach to general universal horizons

    NASA Astrophysics Data System (ADS)

    Maciel, Alan

    2016-05-01

    Theories of gravity with a preferred foliation usually display arbitrarily fast signal propagation, changing the black hole definition. A new inescapable barrier, the universal horizon, has been defined and many static and spherically symmetric examples have been studied in the literature. Here, we translate the usual definition of the universal horizon in terms of an optical scalar built with the preferred flow defined by the preferred spacetime foliation. The new expression has the advantages of being of quasilocal nature and independent of specific spacetime symmetries in order to be well defined. Therefore, we propose it as a definition for general quasilocal universal horizons. Using the new formalism, we show that there is no universal analog of cosmological horizons for Friedmann-Lemaître-Robertson-Walker models for any scale factor function, and we also state that quasilocal universal horizons are restricted to trapped regions of the spacetime. Using the evolution equation, we analyze the formation of universal horizons under a truncated Hořava-Lifshitz theory, in spherical symmetry, showing the existence of regions in parameter space where the universal horizon formation cannot be smooth from the center, under some physically reasonable assumptions. We conclude with our view on the next steps for the understanding of black holes in nonrelativistic gravity theories.

  15. Inner and outer horizons of time experience.

    PubMed

    Wackermann, Jirí

    2007-05-01

    Human experience of temporal durations exhibits a multi-regional structure, with more or less distinct boundaries, or horizons, on the scale of physical duration. The inner horizons are imposed by perceptual thresholds for simultaneity (approximately equal to 3 ms) and temporal order (approximatly equal to 30 ms), and are determined by the dynamical properties of the neural substrate integrating sensory information. Related to the inner horizon of experienced time are perceptual or cognitive "moments." Comparative data on autokinetic times suggest that these moments may be relatively invariant (approximately equal to 10(2) ms) across a wide range of species. Extension of the "sensible present" (approximately equal to 3 s) defines an intermediate horizon, beyond which the generic experience of duration develops. The domain of immediate duration experience is delimited by the ultimate outer horizon at about = 10(2) s, as evidenced by analysis of duration reproduction experiments (reproducibility horizon), probably determined by relaxation times of "neural accumulators." Beyond these phenomenal horizons, time is merely cognitively (re)constructed, not actually experienced or "perceived," a fact that is frequently ignored by contemporary time perception research. The nyocentric organization of time experience shows an interesting analogy with the egocentric organization of space, suggesting that structures of subjective space and time are derived from active motion as a common experiential basis.

  16. Long-Range Reconnaissance Imager on New Horizons

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.; Weaver, H. A.; Conard, S. J.; Morgan, M. F.; Barnouin-Jha, O.; Boldt, J. D.; Cooper, K. A.; Darlington, E. H.; Grey, M. P.; Hayes, J. R.; Kosakowski, K. E.; Magee, T.; Rossano, E.; Sampath, D.; Schlemm, C.; Taylor, H. W.

    2008-10-01

    The LOng-Range Reconnaissance Imager (LORRI) is the high-resolution imaging instrument for the New Horizons mission to Pluto, its giant satellite Charon, its small moons Nix and Hydra, and the Kuiper Belt, which is the vast region of icy bodies extending roughly from Neptune’s orbit out to 50 astronomical units (AU). New Horizons launched on January 19, 2006, as the inaugural mission in NASA’s New Frontiers program. LORRI is a narrow-angle (field of view=0.29°), high-resolution (4.95 μrad pixels), Ritchey-Chrétien telescope with a 20.8-cm diameter primary mirror, a focal length of 263 cm, and a three-lens, field-flattening assembly. A 1,024×1,024 pixel (optically active region), thinned, backside-illuminated charge-coupled device (CCD) detector is used in the focal plane unit and is operated in frame-transfer mode. LORRI provides panchromatic imaging over a bandpass that extends approximately from 350 nm to 850 nm. LORRI operates in an extreme thermal environment, situated inside the warm spacecraft with a large, open aperture viewing cold space. LORRI has a silicon carbide optical system, designed to maintain focus over the operating temperature range without a focus adjustment mechanism. Moreover, the spacecraft is thruster-stabilized without reaction wheels, placing stringent limits on the available exposure time and the optical throughput needed to satisfy the measurement requirements.

  17. Production and decay of evolving horizons

    NASA Astrophysics Data System (ADS)

    Nielsen, Alex B.; Visser, Matt

    2006-07-01

    We consider a simple physical model for an evolving horizon that is strongly interacting with its environment, exchanging arbitrarily large quantities of matter with its environment in the form of both infalling material and outgoing Hawking radiation. We permit fluxes of both lightlike and timelike particles to cross the horizon, and ask how the horizon grows and shrinks in response to such flows. We place a premium on providing a clear and straightforward exposition with simple formulae. To be able to handle such a highly dynamical situation in a simple manner we make one significant physical restriction—that of spherical symmetry—and two technical mathematical restrictions: (1) we choose to slice the spacetime in such a way that the spacetime foliations (and hence the horizons) are always spherically symmetric. (2) Furthermore, we adopt Painlevé Gullstrand coordinates (which are well suited to the problem because they are nonsingular at the horizon) in order to simplify the relevant calculations. Of course physics results are ultimately independent of the choice of coordinates, but this particular coordinate system yields a clean physical interpretation of the relevant physics. We find particularly simple forms for surface gravity, and for the first and second law of black hole thermodynamics, in this general evolving horizon situation. Furthermore, we relate our results to Hawking's apparent horizon, Ashtekar and co-worker's isolated and dynamical horizons, and Hayward's trapping horizon. The evolving black hole model discussed here will be of interest, both from an astrophysical viewpoint in terms of discussing growing black holes and from a purely theoretical viewpoint in discussing black hole evaporation via Hawking radiation.

  18. Friedmann equations and thermodynamics of apparent horizons.

    PubMed

    Gong, Yungui; Wang, Anzhong

    2007-11-23

    With the help of a masslike function which has a dimension of energy and is equal to the Misner-Sharp mass at the apparent horizon, we show that the first law of thermodynamics of the apparent horizon dE=T(A)dS(A) can be derived from the Friedmann equation in various theories of gravity, including the Einstein, Lovelock, nonlinear, and scalar-tensor theories. This result strongly suggests that the relationship between the first law of thermodynamics of the apparent horizon and the Friedmann equation is not just a simple coincidence, but rather a more profound physical connection.

  19. NEW HORIZONS IN SENSOR DEVELOPMENT

    PubMed Central

    Intille, Stephen S.; Lester, Jonathan; Sallis, James F.; Duncan, Glen

    2011-01-01

    Background Accelerometery and other sensing technologies are important tools for physical activity measurement. Engineering advances have allowed developers to transform clunky, uncomfortable, and conspicuous monitors into relatively small, ergonomic, and convenient research tools. New devices can be used to collect data on overall physical activity and in some cases posture, physiological state, and location, for many days or weeks from subjects during their everyday lives. In this review article, we identify emerging trends in several types of monitoring technologies and gaps in the current state of knowledge. Best practices The only certainty about the future of activity sensing technologies is that researchers must anticipate and plan for change. We propose a set of best practices that may accelerate adoption of new devices and increase the likelihood that data being collected and used today will be compatible with new datasets and methods likely to appear on the horizon. Future directions We describe several technology-driven trends, ranging from continued miniaturization of devices that provide gross summary information about activity levels and energy expenditure, to new devices that provide highly detailed information about the specific type, amount, and location of physical activity. Some devices will take advantage of consumer technologies, such as mobile phones, to detect and respond to physical activity in real time, creating new opportunities in measurement, remote compliance monitoring, data-driven discovery, and intervention. PMID:22157771

  20. Saturation of resistivity and Kohler's rule in Ni-doped La1.85Sr0.15CuO4 cuprate

    NASA Astrophysics Data System (ADS)

    Malinowski, A.; Bezusyy, V. L.; Nowicki, P.

    2017-01-01

    We present the results of electrical transport measurements of La1.85Sr0.15Cu1 -yNiyO4 thin single-crystal films at magnetic fields up to 9 T. Adding Ni impurity with strong Coulomb scattering potential to a slightly underdoped cuprate makes the signs of resistivity saturation at ρsat visible in the measurement temperature window up to 350 K. Employing the parallel-resistor formalism reveals that ρsat is consistent with the classical Ioffe-Regel-Mott limit and changes with carrier concentration n as ρsat∝1 /√{n } . Thermopower measurements show that Ni tends to localize mobile carriers, decreasing their effective concentration as n ≅0.15 -y . The classical unmodified Kohler's rule is fulfilled for magnetoresistance in the nonsuperconducting part of the phase diagram when applied to the ideal branch in the parallel-resistor model.

  1. Ferroelectric domain structures in <001>-oriented K{sub 0.15}Na{sub 0.85}NbO{sub 3} lead-free single crystal

    SciTech Connect

    Chen, Yan; Wong, Chi-Man; Yau, Hei-Man; Dai, Jiyan; Deng, Hao; Luo, Haosu; Wang, Danyang; Yan, Zhibo; Chan, Helen L. W.

    2015-03-15

    In this work, ferroelectric domain structures of <001 >-oriented K{sub 0.15}Na{sub 0.85}NbO{sub 3} single crystal are characterized. Transmission electron microscopy (TEM) observation revealed high-density of laminate domain structures in the crystal and the lattices of the neighboring domains are found to be twisted in a small angle. Superlattice diffraction spots of 1/2 (eeo) and 1/2 (ooe) in electron diffraction patterns are observed in the crystal, revealing the a{sup +}a{sup +}c{sup −} tilting of oxygen octahedral in the perovskite structure. The piezoresponse of domains and in-situ poling responses of K{sub 0.15}Na{sub 0.85}NbO{sub 3} crystal are observed by piezoresponse force microscopy (PFM), and the results assure its good ferroelectric properties.

  2. Synthesis method, control of cationic composition and superconducting behavior of Nd 1.85Ce 0.15Cu 1±δO y

    NASA Astrophysics Data System (ADS)

    Serquis, A.; Prado, F.; Caneiro, A.

    1995-02-01

    Samples of Nd 1.85Ce 0.15Cu 1 ± °O y (0.99 ⩽ ± δ ⩽ 1.02) were prepared by a solid-state reaction (SSR), nitrate-decomposition method (NDM) and liquid-mix method (LMM) and characterized by XRD, SEM, EPMA, DTA and DC magnetization. The control of Cu content, substitutional impurities and Ce homogeneity depends on the synthesis method, which modifies the microstructure and the superconducting behavior of these materials. Our results show that in Nd 1.85Ce 0.15Cu 1 ± δO y small variations of δ strongly affect the superconducting properties. For 1 + δ > 1.00 the Meissner fraction and the superconducting transition are substantially improved.

  3. Chemical Reduction of Nd 1.85 Ce 0.15 CuO 4− δ Powders in Supercritical Sodium Ammonia Solutions

    DOE PAGES

    Dias, Yasmin; Wang, Hui; Zhou, Haiqing; ...

    2015-01-01

    Nd 1.85 Ce 0.15 CuO 4− δ powders are chemically reduced in supercritical sodium ammonia solutions from room temperature to 350°C. The crystallographic structure of the reduced powders is investigated from Rietveld refinement of X-ray powder diffraction. The atomic positions are maintained constant within experimental errors while temperature factors of all atoms increase significantly after the chemical treatments, especially of Nd/Ce atoms. The ammonothermally reduced Nd 1.85 Ce 0.15 CuO 4− δ powders show diamagnetic below 24 K which is contributed to the lower oxygen content and higher temperature factors of atoms in the treated compound.more » The ammonothermal method paves a new way to reduce oxides in supercritical solutions near room temperature.« less

  4. Magnetic and magnetotransport properties of nanocrystalline Ag 0.85Fe 0.15 and Ag 0.70Fe 0.30 alloys prepared by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Gómez, J. A.; Xia, S. K.; Passamani, E. C.; Giordanengo, B.; Baggio-Saitovitch, E. M.

    2001-01-01

    The magnetic and magnetotransport properties of nanocrystalline Ag 0.85Fe 0.15 and Ag 0.70Fe 0.30 alloys have been studied by Mössbauer spectroscopy, magnetization and resistivity measurements. The samples were prepared by mechanical alloying of Fe and Ag powders in a high-energy ball mill. Mössbauer spectroscopy and magnetic measurements of the final milled samples indicate the presence of single-domain 'Fe' particles. The magnetoresistance values, at 4.2 K and for a magnetic field of 8 T, are 2.5% and 5.7% for samples Ag 0.85Fe 0.15 and Ag 0.70Fe 0.30, respectively. The magnetoresistance behavior indicates the cluster-glass-like features in both the final milled samples.

  5. Deformation Behavior and Microstructure Evolution of the Cu-2Ni-0.5Si-0.15Ag Alloy During Hot Compression

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Volinsky, Alex A.; Xu, Qian-Qian; Chai, Zhe; Tian, Baohong; Liu, Ping; Tran, Hai T.

    2015-12-01

    Hot deformation behavior of the Cu-2Ni-0.5Si-0.15Ag alloy was investigated by hot compression tests using the Gleeble-1500D thermo-simulator in the 873 K to 1073 K (600 °C to 800 °C) temperatures range with the 0.01 to 5 s-1 strain rate. The flow stress strongly depends on the deformation parameters, including temperature and strain rate. The flow stress decreases with the deformation temperature and increases with the strain rate. The constitutive relationship between the peak stress, the strain rate, and the deformation temperature can be described by the Zener-Hollomon Z parameter in the hyperbolic sine function with the hot deformation activation energy of 316 kJ/mol. The dynamic recrystallization (DRX) is one of the important softening mechanisms of the Cu-2Ni-0.5Si-0.15Ag alloy during hot deformation. The DRX behavior of the Cu-2Ni-0.5Si-0.15Ag alloy is strongly affected by the Z parameter. Lower Z parameter leads to more adequate DRX proceeding.

  6. Gas-Phase Oxidation of Cm+ and Cm2+ -- Thermodynamics of neutral and ionized CmO

    SciTech Connect

    Gibson, John K; Haire, Richard G.; Santos, Marta; Pires de Matos, Antonio; Marcalo, Joaquim

    2008-12-08

    Fourier transform ion cyclotron resonance mass spectrometry was employed to study the products and kinetics of gas-phase reactions of Cm+ and Cm2+; parallel studies were carried out with La+/2+, Gd+/2+ and Lu+/2+. Reactions with oxygen-donor molecules provided estimates for the bond dissociation energies, D[M+-O](M = Cm, Gd, Lu). The first ionization energy, IE[CmO], was obtained from the reactivity of CmO+ with dienes, and the second ionization energies, IE[MO+](M = Cm, La, Gd, Lu), from the rates of electron-transfer reactions from neutrals to the MO2+ ions. The following thermodynamic quantities for curium oxide molecules were obtained: IE[CmO]= 6.4+-0.2 eV; IE[CmO+]= 15.8+-0.4 eV; D[Cm-O]= 710+-45 kJ mol-1; D[Cm+-O]= 670+-40 kJ mol-1; and D[Cm2+-O]= 342+-55 kJ mol-1. Estimates for the M2+-O bond energies for M = Cm, La, Gd and Lu are all intermediate between D[N2-O]and D[OC-O]--i.e., 167 kJ mol-1< D[M2+-O]< 532 kJ mol-1 -- such that the four MO2+ ions fulfill the thermodynamic requirement for catalytic O-atom transport from N2O to CO. It was demonstrated that the kinetics are also favorable and that the CmO2+, LaO2+, GdO2+ and LuO2+ dipositive ions each catalyze the gas-phase oxidation of CO to CO2 by N2O. The CmO2+ ion appeared during the reaction of Cm+ with O2 when the intermediate, CmO+, was not collisionally cooled -- although its formation is kinetically and/or thermodynamically unfavorable, CmO2+ is a stable species.

  7. Nonlinear optics of fibre event horizons.

    PubMed

    Webb, Karen E; Erkintalo, Miro; Xu, Yiqing; Broderick, Neil G R; Dudley, John M; Genty, Goëry; Murdoch, Stuart G

    2014-09-17

    The nonlinear interaction of light in an optical fibre can mimic the physics at an event horizon. This analogue arises when a weak probe wave is unable to pass through an intense soliton, despite propagating at a different velocity. To date, these dynamics have been described in the time domain in terms of a soliton-induced refractive index barrier that modifies the velocity of the probe. Here we complete the physical description of fibre-optic event horizons by presenting a full frequency-domain description in terms of cascaded four-wave mixing between discrete single-frequency fields, and experimentally demonstrate signature frequency shifts using continuous wave lasers. Our description is confirmed by the remarkable agreement with experiments performed in the continuum limit, reached using ultrafast lasers. We anticipate that clarifying the description of fibre event horizons will significantly impact on the description of horizon dynamics and soliton interactions in photonics and other systems.

  8. Horizon Entropy from Quantum Gravity Condensates.

    PubMed

    Oriti, Daniele; Pranzetti, Daniele; Sindoni, Lorenzo

    2016-05-27

    We construct condensate states encoding the continuum spherically symmetric quantum geometry of a horizon in full quantum gravity, i.e., without any classical symmetry reduction, in the group field theory formalism. Tracing over the bulk degrees of freedom, we show how the resulting reduced density matrix manifestly exhibits a holographic behavior. We derive a complete orthonormal basis of eigenstates for the reduced density matrix of the horizon and use it to compute the horizon entanglement entropy. By imposing consistency with the horizon boundary conditions and semiclassical thermodynamical properties, we recover the Bekenstein-Hawking entropy formula for any value of the Immirzi parameter. Our analysis supports the equivalence between the von Neumann (entanglement) entropy interpretation and the Boltzmann (statistical) one.

  9. Optimization of the electrochemical performance of a Ni/Ce0.9Gd0.1O2-δ-impregnated La0.57Sr0.15TiO3 anode in hydrogen

    NASA Astrophysics Data System (ADS)

    Xia, Tian; Brüll, Annelise; Grimaud, Alexis; Fourcade, Sébastien; Mauvy, Fabrice; Zhao, Hui; Grenier, Jean-Claude; Bassat, Jean-Marc

    2014-09-01

    A-site deficient perovskite La0.57Sr0.15TiO3 (LSTO) materials are synthesized by a modified polyacrylamide gel route. X-ray diffraction pattern of LSTO indicates an orthorhombic structure. The thermal expansion coefficient of LSTO is 10.0 × 10-6 K-1 at 600 °C in 5%H2/Ar. LSTO shows an electrical conductivity of 2 S cm-1 at 600 °C in 3%H2O/H2. A new composite material, containing the porous LSTO backbone impregnated with small amounts of Ce0.9Gd0.1O2-δ (CGO) (3.4-8.3 wt.%) and Ni/Cu (2.0-6.3 wt.%), is investigated as an alternative anode for solid oxide fuel cells (SOFCs). Because of the substantial electro-catalytic activity of the fine and well-dispersed Ni particles on the surface of the ceramic framework, the polarization resistance of 6.3%Ni-8.3%CGO-LSTO anode reaches 0.73 Ω cm2 at 800 °C in 3%H2O/H2. In order to further improve the anodic performance, corn starch and carbon black are used as pore-formers to optimize the microstructure of anodes.

  10. A robust high performance cobalt-free oxygen electrode La0.5Sr0.5Fe0.8Cu0.15Nb0.05O3-δ for reversible solid oxide electrochemical cell

    NASA Astrophysics Data System (ADS)

    Zhou, Ning; Yin, Yi-Mei; Li, Jingcheng; Xu, Lei; Ma, Zi-Feng

    2017-02-01

    A novel cobalt-free perovskite oxide La0.5Sr0.5Fe0.8Cu0.15Nb0.05O3-δ (LSFCN) has been synthesized and evaluated as oxygen electrode for reversible solid oxide electrochemical cells (RSOCs). The performance and stability of the LSFCN based RSOCs have been characterized in fuel cell and electrolysis modes, and the reversibility of the cells has been proven. In FC mode, the cell exhibits the maximum power density of 1.10 Wcm-2 at 800 °C, and a stable output under 0.7 V at 700 °C during 108 h. The performance and stability of the cell in electrolysis mode are also remarkable. An electrolysis current of 0.85 A cm-2 is achieved at 750 °C with an applied voltage of 1.3 V, and no degradation as well as delamination are observed for the cell after 50 h electrolysis under voltage of 1.60 V (∼1.27 A cm-2) at 800 °C. The high performance of the LSFCN at both cathodic and anodic conditions may be attributed to the inherent high electrochemical activity of copper-iron based perovskites; and the incorporation of Nb5+ cations into perovskite lattice is responsible for the stability of LSFCN, which leads to the more stable crystal structure, lower thermal expansion coefficient and the reduced Sr segregation at surface.

  11. Transport of four pharmaceuticals in different horizons of three soil types

    NASA Astrophysics Data System (ADS)

    Kodesova, Radka; Svatkova, Paula; Klement, Ales; Jaksik, Ondrej; Golovko, Oksana; Fer, Miroslav; Kocarek, Martin; Nikodem, Antonin; Grabic, Roman

    2015-04-01

    Soil structure, which varies in different soil types and the horizons of these soil types, has a significant impact on water flow and contaminant transport in soils. Transport of many contaminants is in addition strongly influenced by their sorption on soil particles. Transport of four pharmaceuticals (sulfamethoxazole, trimethoprim, atenolol and carbamazepine) was studied in soil columns (a diameter of 10.5 cm and a height of 13 cm) taken from all diagnostic horizons of three different soil types (Haplic Luvisol, Greyic Phaeozem and Haplic Cambisol). The irrigation by water contaminated by a mixture of all four compounds followed by ponding infiltration of distilled water was simulated and water outflow and solute concentrations from the bottom of the soil sample was monitored in time. The highest infiltration rates were observed for soil samples from the Bt horizons of the Greyic Phaeozem that exhibited prismatic structure, followed by rates observed in the Ap horizons of the Haplic Luvisol, Greyic Phaeozem and Haplic Cambisol (due to their granular soil structure and presence of root channels). The lowest infiltration rate was measured for the Bw horizon of the Haplic Cambisol, which had a poorly developed soil structure and a low fraction of macropores. Compound discharge was however also highly affected by their sorption on solids. The highest mobility was observed for sulfamethoxazole followed by carbamazepine atenolol and trimethoprim, which corresponds to measured sorption isotherms. Mobility of ionizable compounds in different soil samples was influenced by pH (i.e. degree and form of their ionization) and sites available for absorption. Mobility of sulfamethoxazole decreased with decreasing pH (i.e. the largest sorption measured in horizons of the Haplic Cambisol). While mobility of atenolol and trimethoprim decreased with increasing base cation saturation, and with increasing organic matter content for carbamazepine. As result of both affects (i.e. soil

  12. Structural, magnetic and magnetoelectric properties of single phase La3+ and Er3+ co-doped Bi0.85-x La0.15Er x FeO3 (0 ≤ x ≤ 0.1) ceramics

    NASA Astrophysics Data System (ADS)

    Manjusha; Yadav, K. L.; Mall, Ashish Kumar

    2016-11-01

    A sol-gel reaction method is used to prepare La3+ and Er3+ co-doped ceramic Bi0.85-x La0.15Er x FeO3 (x = 0, 0.05, 0.07 and 0.10) equivalently denoted as BLEFO. Bi0.85-x La0.15Er x FeO3 exhibits the structural transition from rhombohedral to a triclinic structure with quite small triclinic distortion; as confirmed by the Rietveld refinement analysis. Field emission scanning electron micrographs reveal the presence of interconnected spherical grains. From transmission electron microscopy, the average crystal size was found to be 60-65 nm. Co-doping with La and Er enhanced the magnetic properties such as saturation magnetization and magnetic moment of BiFeO3 as confirmed by vibrating sample magnetometer at 300 K and as well as by superconducting quantum interference device (SQUID) analysis at 5 K. An unusual behavior has been observed in BLEFO at 300 K, because it shows the weak ferromagnetic behavior besides its antiferromagnetic nature at room temperature. An irreversibility effect and a large bifurcation have been observed below room temperature in BLEFO in SQUID measurement. The value of magnetoelectric (ME) coupling coefficient increases from 2.60 (x = 0) to 6.58 (x = 0.10) mV cm-1-Oe at 3500 Oe. A negative temperature coefficient of the resistance behavior analogous to a semiconductor is confirmed by the impedance analysis. The enhanced multiferroic properties are attributed to the enhanced ME interaction, which results from the La and Er substitution at A site of BiFeO3.

  13. Diel variation in the vertical distribution of particulate matter (>0.15 mm) in the NW Mediterranean Sea investigated with the Underwater Video Profiler

    NASA Astrophysics Data System (ADS)

    Stemmann, Lars; Picheral, Marc; Gorsky, Gabriel

    2000-03-01

    Day/night variations in the size distribution of the particulate matter >0.15 mm (PM) were studied in May 1995 during the DYNAPROC time-series cruise in the northwestern Mediterranean Sea. Data on vertical distributions of PM (>0.15 mm) and zooplankton were collected with the Underwater Video Profiler (UVP). The comparisons of the UVP data with plankton net data and POC data from water bottles indicated that more than 97% of the particles detected by the UVP were non-living particles (0.15 mm) and that the PM contributed 4-34% of the total dry weight measured on GF/F filters. Comparison of seven pairs of day and night vertical profiles performed during the cruise showed that in the upper 800 m, the mean size and the volume of particles was higher at night than during the day. During the night, the integrated volume of the PM increased on average by 32±20%. This increase corresponded to a shift of smaller size classes (<0.5 mm) towards the larger ones (>0.5 mm). During the day, the pattern was reversed, and the quantity of PM >0.5 mm decreased. During the study period, the standing stock of PM (60-800 m) decreased from 7.5 to less than 2 g m -2 but the diel variations persisted, except for two short periods in the superficial layer following a wind event. The cyclic feeding activity induced by the diel vertical migration of zooplankton could be the best candidate to explain the observed diel fluctuations in the size classes of PM in the water column. However, our results also suggest that in the upper layer additional driving forces such as the increase of the level of turbulence after a wind event or the modification of the zoo- and phytoplankton community can influence the PM temporal evolution.

  14. Giant low-field magnetocaloric effect in single-crystalline EuTi{sub 0.85}Nb{sub 0.15}O{sub 3}

    SciTech Connect

    Roy, S.; Khan, N.; Mandal, P.

    2016-02-01

    The magnetocaloric effect in ferromagnetic single crystal EuTi{sub 0.85}Nb{sub 0.15}O{sub 3} has been investigated using magnetization and heat capacity measurements. EuTi{sub 0.85}Nb{sub 0.15}O{sub 3} undergoes a continuous ferromagnetic phase transition at T{sub C} = 9.5 K due to the long range ordering of magnetic moments of Eu{sup 2+} (4f{sup 7}). With the application of magnetic field, the spin entropy is strongly suppressed and a giant magnetic entropy change is observed near T{sub C}. The values of entropy change ΔS{sub m} and adiabatic temperature change ΔT{sub ad} are as high as 51.3 J kg{sup −1} K{sup −1} and 22 K, respectively, for a field change of 0–9 T. The corresponding magnetic heating/cooling capacity is 700 J kg{sup −1}. This compound also shows large magnetocaloric effect even at low magnetic fields. In particular, the values of ΔS{sub m} reach 14.7 and 23.8 J kg{sup −1} K{sup −1} for field changes of 0–1 T and 0–2 T, respectively. The low-field giant magnetocaloric effect, together with the absence of thermal and field hysteresis makes EuTi{sub 0.85}Nb{sub 0.15}O{sub 3} a very promising candidate for low temperature magnetic refrigeration.

  15. Multiferroic properties of nanocrystalline BiFe1-xNixO3 (x=0.0-0.15) perovskite ceramics

    NASA Astrophysics Data System (ADS)

    Chaudhari, Yogesh; Mahajan, Chandrashekhar M.; Singh, Amrita; Jagtap, Prashant; Chatterjee, Ratnamala; Bendre, Subhash

    2015-12-01

    Ni doped BiFeO3 (x=0, 0.05, 0.1 and 0.15) nanocrystalline ceramics were synthesized by the solution combustion method (SCM) to obtain optimal multiferroic properties. The effect of Ni doping on structural, morphological, ferroelectric, magnetic and dielectric properties of BiFeO3 was studied. The structural investigations by using X-ray diffraction (XRD) pattern confirmed that BiFe1-xNixO3 ceramics have rhombhohedral perovskite structure. The ferroelectric hysteresis measurements for BiFe1-xNixO3 (x=0, 0.05, 0.1, 0.15) compound at room temperature found to exhibit unsaturated behavior and presents partial reversal of polarization. The magnetic measurements demonstrated an enhancement of ferromagnetic property due to Ni doping in BiFeO3 when compared with undoped BiFeO3. The variation of dielectric constant with temperature in BiFe0.9Ni0.1O3 and BiFe0.85Ni0.15O3 samples evidenced an apparent dielectric anomaly around 350 °C and 300 °C which corresponds to antiferromagnetic to paramagnetic phase transition of (TN) of BiFeO3. The dependence of room temperature dielectric properties on frequency signifies that both dielectric constant (ε) and dielectric loss (tan δ) are the strong function of frequency. The results show that solution combustion method leads to synthesis of an excellent and reproducible BiFe1-xNixO3 multiferroic ceramics.

  16. Sorption of acetochlor, S-metolachlor, and atrazine in surface and subsurface soil horizons of Argentina.

    PubMed

    Bedmar, Francisco; Daniel, Peter E; Costa, José L; Giménez, Daniel

    2011-09-01

    Understanding herbicide sorption within soil profiles is the first step to predicting their behavior and leaching potential. Laboratory studies were conducted to determine the influence of surface and subsurface soil properties on acetochlor, atrazine, and S-metolachlor sorption. Soil samples were taken from horizons A, B, and C of two loamy soils of the humid pampas of Argentina under no-till management; horizon A was divided into two layers, A(0) (0-5 cm) and A(1) (5 cm to the full thickness of an A horizon). Sorption isotherms were determined from each sampled horizon using the batch equilibrium method and seven concentrations (0, 0.1, 0.5, 2.0, 5.0, 10.0, and 20.0 mg L(-1)). Sorption affinity of herbicides was approximated by the Freundlich equation. The sorption strength K(f) (mg(1 - 1/n) kg(-1) L(1/n) ) over the soils and horizons studied followed the order S-metolachlor (16.51-29.19) > atrazine (4.85-12.34) ≥ acetochlor (5.17-11.97), which was closely related to the hydrophobicity of herbicides expressed as octanol-water partition coefficient (K(OW) ). The K(f) values of the three herbicides were positively correlated with soil organic carbon, with a significance of p < 0.01. Values of K(f) for the three herbicides decreased with depth in the two soils, indicating greater sorption onto surficial soil horizons and possibly a delayed transport toward subsurface soils and subsequent pollution of groundwater.

  17. Coexistence of long-ranged magnetic order and superconductivity in the pnictide superconductor SmFeAsO1-xFx (x=0,0.15)

    NASA Astrophysics Data System (ADS)

    Ryan, D. H.; Cadogan, J. M.; Ritter, C.; Canepa, F.; Palenzona, A.; Putti, M.

    2009-12-01

    Powder neutron-diffraction measurements on both SmFeAsO and the fluorine-doped superconductor, SmFeAsO0.85F0.15 , show that the Sm sublattice orders magnetically. In both cases we observe a simple layered antiferromagnetic arrangement of the ˜0.5μB Sm moments. This provides direct evidence that long-ranged magnetic order of the samarium moments coexists with superconductivity in the SmFeAsO1-xFx system.

  18. Sintering of BaCe(0.85)Y(0.15)O3-(Beta) With/Without SrTiO Dopant

    NASA Technical Reports Server (NTRS)

    Dynys, Fred; Sayir, Ali; Heimann, Paula J.

    2004-01-01

    The sintering behavior of BaCe(0.85)Y(0.15)O3-(Beta) doped with SrTiO is described. Complete reaction and crystallization of perovskite phase by solid state was achieved by calcining at 1200 degrees C for 24 hours.Smaples were sintered at 1450 degrees C, 1550 degrees C, and 1650 degrees C. SrTiOsub3 enhanced sintering, while optimal dopant level was different for powders synthesized by solid state and co-precipitation. Both powders exhibit similar grain growth behavior.

  19. Critical state and low-field electrodynamics in LaO{sub 0.85}F{sub 0.15}FeAs superconductor polycrystals

    SciTech Connect

    Gerashchenko, O. V.; Kholmetskii, A. L.; Mashlan, M.; Yarman, T.; Aldushchenkov, A. V.; Okunev, I. S.; Lomonosov, V. A.; Makhnach, L. V.

    2015-06-15

    The penetration of a weak magnetic field into LaO{sub 0.85}F{sub 0.15}FeAs polycrystalline superconductors is investigated using two mutually complementing techniques: measurement of the higher harmonics of nonlinear magnetization and the current-voltage characteristics. The dependences of the critical current density and resistivity on the temperature and magnetic field strength are determined. The results confirm the theory of the critical state in the low-field electrodynamics of a Josephson medium. The universality of this theoretical concept is demonstrated for a new class of ceramic superconductors.

  20. Wind-tunnel free-flight investigation of a 0.15-scale model of the F-106B airplane with vortex flaps

    NASA Technical Reports Server (NTRS)

    Yip, Long P.

    1987-01-01

    An investigation to determine the effects of vortex flaps on the flight dynamic characteristics of the F-106B in the area of low-speed, high-angle-of-attack flight was undertaken on a 0.15-scale model of the airplane in the Langley 30- by 60-Foot Tunnel. Static force tests, dynamic forced-oscillation tests, as well as free-flight tests were conducted to obtain a data base on the flight characteristics of the F-106B airplane with vortex flaps. Vortex flap configurations tested included a full-span gothic flap, a full-span constant-chord flap, and a part-span gothic flap.

  1. LIQUIDARMOR CM Flashing and Sealant, High Impact Technology Demonstration

    SciTech Connect

    Hun, Diana E.; Bhandari, Mahabir S.

    2016-12-01

    Air leakage is responsible for about 1.1 quads of energy or 6% of the total energy used by commercial buildings in the US. Consequently, infiltration and exfiltration are among the largest envelope-related contributors to the heating, ventilation, and air conditioning loads in commercial buildings. New air sealing technologies have recently emerged that aim to improve the performance of air barrier systems by simplifying their installation procedure. LIQUIDARMORTM CM Flashing and Sealant is an example of these new advanced material technologies. This technology is a spray-applied sealant and liquid flashing and can span gaps that are up to ¼ in. wide without a supporting material. ORNL verified the performance of LIQUIDARMORTM CM with field tests and energy simulations from a building in which LIQUIDARMORTM CM was one of components of the air barrier system. The Homeland Security Training Center (HTC) at the College of DuPage in Glen Ellyn, IL, served as the demonstration site. Blower door test results show the average air leakage rate in the demonstration site to be 0.15 cfm/ft2 at 1.57 psf, or 63% lower than the 0.4 cfm at 1.57 psf specified in the 2015 International Energy Conservation Code (IECC). According to simulation results, HTC lowered its annual heating and cooling cost by about $3,000 or 9% compared to a similar building that lacked an air barrier system. This demonstration project serves as an example of the level of building envelope airtightness that can be achieved by using air barrier materials that are properly installed, and illustrates the energy and financial savings that such an airtight envelope could attain.

  2. Parallel processing: The Cm/sup */ experience

    SciTech Connect

    Siewiorek, D.; Gehringer, E.; Segall, Z.

    1986-01-01

    This book describes the parallel-processing research with CM/sup */ at Carnegie-Mellon University. Cm/sup */ is a tightly coupled 50-processor multiprocessing system that has been in operation since 1977. Two complete operating systems-StarOS and Medusa-are part of its development along with a number of applications.

  3. Pedotransfer functions for Irish soils - estimation of bulk density (ρb) per horizon type

    NASA Astrophysics Data System (ADS)

    Reidy, B.; Simo, I.; Sills, P.; Creamer, R. E.

    2016-01-01

    Soil bulk density is a key property in defining soil characteristics. It describes the packing structure of the soil and is also essential for the measurement of soil carbon stock and nutrient assessment. In many older surveys this property was neglected and in many modern surveys this property is omitted due to cost both in laboratory and labour and in cases where the core method cannot be applied. To overcome these oversights pedotransfer functions are applied using other known soil properties to estimate bulk density. Pedotransfer functions have been derived from large international data sets across many studies, with their own inherent biases, many ignoring horizonation and depth variances. Initially pedotransfer functions from the literature were used to predict different horizon type bulk densities using local known bulk density data sets. Then the best performing of the pedotransfer functions were selected to recalibrate and then were validated again using the known data. The predicted co-efficient of determination was 0.5 or greater in 12 of the 17 horizon types studied. These new equations allowed gap filling where bulk density data were missing in part or whole soil profiles. This then allowed the development of an indicative soil bulk density map for Ireland at 0-30 and 30-50 cm horizon depths. In general the horizons with the largest known data sets had the best predictions, using the recalibrated and validated pedotransfer functions.

  4. Pedotransfer functions for Irish soils - estimation of bulk density (ρb) per horizon type

    NASA Astrophysics Data System (ADS)

    Reidy, B.; Simo, I.; Sills, P.; Creamer, R. E.

    2015-10-01

    Soil bulk density is a key property in defining soil characteristics. It describes the packing structure of the soil and is also essential for the measurement of soil carbon stock and nutrient assessment. In many older surveys this property was neglected and in many modern surveys this property is omitted due to cost both in laboratory and labour and in cases where the core method cannot be applied. To overcome these oversights pedotransfer functions are applied using other known soil properties to estimate bulk density. Pedotransfer functions have been derived from large international datasets across many studies, with their own inherent biases, many ignoring horizonation and depth variances. Initially pedotransfer functions from the literature were used to predict different horizon types using local known bulk density datasets. Then the best performing of the pedotransfer functions, were selected to recalibrate and then were validated again using the known data. The predicted co-efficient of determination was 0.5 or greater in 12 of the 17 horizon types studied. These new equations allowed gap filling where bulk density data was missing in part or whole soil profiles. This then allowed the development of an indicative soil bulk density map for Ireland at 0-30 and 30-50 cm horizon depths. In general the horizons with the largest known datasets had the best predictions, using the recalibrated and validated pedotransfer functions.

  5. Continuously tunable temperature coefficient of resistivity in antiperovskite AgN1-xCxMn3 (0 ≤ x ≤ 0.15)

    NASA Astrophysics Data System (ADS)

    Lin, J. C.; Tong, P.; Lin, S.; Wang, B. S.; Song, W. H.; Sun, Y. P.

    2014-12-01

    The antiperovskite intermetallic compounds AgN1-xCxMn3 (0 ≤ x ≤ 0.15) have been synthesized. As x increases, the temperature coefficient of resistivity (TCR) above room temperature decreases monotonically and finally changes the sign from positive to negative above x = 0.1. Meanwhile, the temperature range is gradually broadened. For x = 0.07, TCR is ˜3.1 ppm/K between 280 K and 375 K. Both the resistivity and its slope are insensitive to the external magnetic field, indicating an insignificant contribution from magnetic scattering or short-range magnetic ordering to the observed low-TCR. As manifested by the Hall effect, the charge carrier density in the paramagnetic state for x = 0.15 is reduced by an order of magnitude in comparison with that for x = 0. The reduction of carrier density and the enhancive disorders when x increases was proposed to be responsible for the decrease in TCR and its sign switch.

  6. Electron-Phonon Anomaly Related to Charge Stripes: Static Stripe Phase Versus Optimally Doped Superconducting La1.85Sr0.15CuO4

    NASA Astrophysics Data System (ADS)

    Reznik, D.; Pintschovius, L.; Fujita, M.; Yamada, K.; Gu, G. D.; Tranquada, J. M.

    2007-05-01

    Inelastic neutron scattering was used to study the Cu-O bond-stretching vibrations in optimally doped La1.85Sr0.15CuO4 (Tc = 35 K) and in two other cuprates showing static stripe order at low temperatures, i.e. La1.48Nd0.4Sr0.12CuO4 and La1.875Ba0.125CuO4. All three compounds exhibit a very similar phonon anomaly, which is not predicted by conventional band theory. It is argued that the phonon anomaly reflects a coupling to charge inhomogeneities in the form of stripes, which remain dynamic in superconducting La1.85Sr0.15CuO4 down to the lowest temperatures. These results show that the phonon effect indicating stripe formation is not restricted to a narrow region of the phase diagram around the so-called 1/8 anomaly but occurs in optimally doped samples as well.

  7. Interference effects of thrust reversing on horizontal tail effectiveness of twin-engine fighter aircraft at Mach numbers from 0.15 to 0.90

    NASA Technical Reports Server (NTRS)

    Capone, F. J.; Mason, M. L.

    1984-01-01

    An investigation was conducted in the Langley 16 foot Transonic Tunnel to determine the interference effects of thrust reversing on horizontal tail effectiveness of a twin engine, general research fighter model at approach and in-flight speeds. Twin vertical tails at three longitudinal locations were tested at a cant angle of 0 deg. One configuration was also tested at a cant angle of 20 deg. Two nonaxisymmetric nozzle reverser concepts were studied. Test data were obtained at Mach numbers of 0.15, 0.60, and 0.90 and at angles of attack from -3 to 9 deg. Nozzle pressure ratios varied from jet off to 7.0, depending upon Mach number. At landing approach speed (Mach number 0.15), thrust reverser operation usually resulted in large variations (up to 70% increase) in horizontal tail effectiveness as nozzle pressure ratio was varied at zero angle of attack or as angle of attack was varied at constant nozzle pressure ratio. There was always a decrease in effectiveness at Mach numbers of 0.60 and 0.90 as a result of reverser operation.

  8. Rounding of a first-order magnetic phase transition in La0.7Ca0.3Mn0.85Ni0.15O3

    NASA Astrophysics Data System (ADS)

    Phan, The-Long; Zhang, P.; Zhang, Y. D.; Grinting, D.; Thanh, T. D.; Yu, S. C.

    2013-05-01

    We prepared a polycrystalline sample of orthorhombic La0.7Ca0.3Mn0.85Ni0.15O3, and then studied its critical behavior. Based on the Landau phase-transition theory and Banerjee's criteria, we have found the sample undergoing a second-order magnetic phase transition. This continuous transition is characterized by critical parameters of TC = 170 K, β = 0.320 ± 0.009, γ = 0.990 ± 0.082, and δ = 4.09 ± 0.17 determined from modified Arrott plots. With these values, the magnetization-field-temperature (M-H-T) behaviors of La0.7Ca0.3Mn0.85Ni0.15O3 below and above TC are well described by an equation of state M(H ,ɛ)=ɛβf±(H /ɛβ +γ), where ɛ =(T -TC)/TC, f+ for T > TC and f- for T < TC. Having compared to the theoretical models, the critical-exponent values determined in our case are close to those expected for the 3D Ising model and mean-field theory. This indicates an existence of ferromagnetic short-range interactions in the system below TC. The nature of the transformation from first-order to second-order phase transitions related to the Ni doping is discussed in detail.

  9. The need for environmental horizon scanning.

    PubMed

    Sutherland, William J; Woodroof, Harry J

    2009-10-01

    Policymakers and practitioners in most fields, including conservation and the environment, often make decisions based on insufficient evidence. One reason for this is that issues appear unexpectedly, when with hindsight, many of them were foreseeable. A solution to the problem of being insufficiently prepared is routine horizon scanning, which we describe as the systematic search for potential threats and opportunities that are currently poorly recognized. Researchers can then decide which issues might be most worthwhile to study. Practitioners can also use horizon scanning to ensure timely policy development and research procurement. Here, we suggest that horizon scanning is an underused tool that should become a standard element of environmental and conservation practice. We make recommendations for its incorporation into research, policy and practice. We argue that, as an ecological and conservation community, we are failing to provide timely advice owing to a weakness in identifying forthcoming issues. We outline possible horizon-scanning methods, and also make recommendations as to how horizon scanning could have a more central role in environmental and conservation practice.

  10. Star-Paths, Stones and Horizon Astronomy

    NASA Astrophysics Data System (ADS)

    Brady, Bernadette

    2015-05-01

    Archaeoastronomers tend to approach ancient monuments focusing on the landscape and the horizon calendar events of sun and moon and, due to problems with precession, generally ignore the movement of the stars. However, locating the position of solar calendar points on the horizon can have other uses apart from calendar and/or cosmological purposes. This paper firstly suggests that the stars do not need to be ignored. By considering the evidence of the Phaenomena, a sky poem by Aratus of Soli, a third century BC Greek poet, and his use of second millennium BC star lore fragments, this paper argues that the stars were a part of the knowledge of horizon astronomy. Aratus' poem implied that the horizon astronomy of the late Neolithic and Bronze Age periods included knowledge of star-paths or 'linear constellations' that were defined by particular horizon calendar events and other azimuths. Knowledge of such star-paths would have enabled navigation and orientation, and by using permanent markers, constructed or natural, to define these paths, they were immune to precession as the stones could redefine a star-path for a future generation. Finally the paper presents other possible intentions behind the diverse orientation of passage tombs and some megalithic sites.

  11. Radio Occultation Measurements of Pluto's Atmosphere with New Horizons

    NASA Astrophysics Data System (ADS)

    Hinson, D. P.; Linscott, I.; Tyler, G. L.; Bird, M. K.; Paetzold, M.; Strobel, D. F.; Summers, M. E.; Woods, W. W.; Stern, A.; Weaver, H. A., Jr.; Olkin, C.; Young, L. A.; Ennico Smith, K.; Gladstone, R.; Greathouse, T.; Kammer, J.; Parker, A. H.; Parker, J. W.; Retherford, K. D.; Schindhelm, E.; Singer, K. N.; Steffl, A.; Tsang, C.; Versteeg, M.

    2015-12-01

    The reconnaissance of the Pluto System by New Horizons included radio occultations at both Pluto and Charon. This talk will present the latest results from the Pluto occultation. The REX instrument onboard New Horizons received and recorded uplink signals from two 70-m antennas and two 34-m antennas of the NASA Deep Space Network - each transmitting 20 kW at 4.2-cm wavelength - during a diametric occultation by Pluto. At the time this was written only a short segment of data at occultation entry (193°E, 17°S) was available for analysis. The REX measurements extend unequivocally to the surface, providing the first direct measure of the surface pressure and the temperature structure in Pluto's lower atmosphere. Preliminary analysis yields a surface pressure of about 10 microbars, smaller than expected. Data from occultation exit (16°E, 15°N) are scheduled to arrive on the ground in late August 2015. Those observations will yield an improved estimate of the surface pressure, a second temperature profile, and a measure of the diameter of Pluto with a precision of a few hundred meters.

  12. The photochemistry of Pluto's atmosphere as illuminated by New Horizons

    NASA Astrophysics Data System (ADS)

    Wong, Michael L.; Fan, Siteng; Gao, Peter; Liang, Mao-Chang; Shia, Run-Lie; Yung, Yuk; Kammer, Joshua A.; Summers, Michael; Gladstone, Randy; Young, Leslie; New Horizons Science Team

    2016-10-01

    New Horizons has granted us an unprecedented glimpse at the structure and composition of Pluto's atmosphere, which is comprised mostly of N2 with trace amounts of CH4, CO, and the photochemical products thereof. Through photochemistry, higher-order hydrocarbons are generated, coagulating into tholins and resulting in global haze layers. The photochemical processes on Pluto are analogous to those occurring in Titan's atmosphere, which have been constrained by comparison to Cassini measurements. The New Horizons dataset offers us a second glimpse at a natural hydrocarbon factory, which will teach us how these processes operate at lower pressures and temperatures. Here we present a state-of-the-art photochemical model for Pluto's atmosphere to explain the abundance profiles of CH4, C2H2, C2H4, and C2H6, the total column density of HCN, and to predict the abundance profiles of oxygen-bearing species. The CH4 profile can be best matched by taking a constant-with-altitude Kzz of 1 × 103 cm2 s-1 and a fixed CH4 surface mixing ratio of 4 × 10-3. Condensation is key to fitting the C2 hydrocarbon profiles. We find that C2H4 must have a much lower saturation vapor pressure than predicted by extrapolations of laboratory measurements to Pluto temperatures. We also find best-fit values for the sticking coefficients of C2H2, C2H4, C2H6, and HCN.

  13. Horizon thermodynamics in fourth-order gravity

    NASA Astrophysics Data System (ADS)

    Ma, Meng-Sen

    2017-03-01

    In the framework of horizon thermodynamics, the field equations of Einstein gravity and some other second-order gravities can be rewritten as the thermodynamic identity: dE = TdS - PdV. However, in order to construct the horizon thermodynamics in higher-order gravity, we have to simplify the field equations firstly. In this paper, we study the fourth-order gravity and convert it to second-order gravity via a so-called ;Legendre transformation; at the cost of introducing two other fields besides the metric field. With this simplified theory, we implement the conventional procedure in the construction of the horizon thermodynamics in 3 and 4 dimensional spacetime. We find that the field equations in the fourth-order gravity can also be written as the thermodynamic identity. Moreover, we can use this approach to derive the same black hole mass as that by other methods.

  14. Foregrounds in Wide-field Redshifted 21 cm Power Spectra

    NASA Astrophysics Data System (ADS)

    Thyagarajan, Nithyanandan; Jacobs, Daniel C.; Bowman, Judd D.; Barry, N.; Beardsley, A. P.; Bernardi, G.; Briggs, F.; Cappallo, R. J.; Carroll, P.; Corey, B. E.; de Oliveira-Costa, A.; Dillon, Joshua S.; Emrich, D.; Ewall-Wice, A.; Feng, L.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Hewitt, J. N.; Hurley-Walker, N.; Johnston-Hollitt, M.; Kaplan, D. L.; Kasper, J. C.; Kim, Han-Seek; Kittiwisit, P.; Kratzenberg, E.; Lenc, E.; Line, J.; Loeb, A.; Lonsdale, C. J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Neben, A. R.; Oberoi, D.; Offringa, A. R.; Ord, S. M.; Paul, Sourabh; Pindor, B.; Pober, J. C.; Prabu, T.; Procopio, P.; Riding, J.; Rogers, A. E. E.; Roshi, A.; Udaya Shankar, N.; Sethi, Shiv K.; Srivani, K. S.; Subrahmanyan, R.; Sullivan, I. S.; Tegmark, M.; Tingay, S. J.; Trott, C. M.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wu, C.; Wyithe, J. S. B.

    2015-05-01

    Detection of 21 cm emission of H i from the epoch of reionization, at redshifts z\\gt 6, is limited primarily by foreground emission. We investigate the signatures of wide-field measurements and an all-sky foreground model using the delay spectrum technique that maps the measurements to foreground object locations through signal delays between antenna pairs. We demonstrate interferometric measurements are inherently sensitive to all scales, including the largest angular scales, owing to the nature of wide-field measurements. These wide-field effects are generic to all observations but antenna shapes impact their amplitudes substantially. A dish-shaped antenna yields the most desirable features from a foreground contamination viewpoint, relative to a dipole or a phased array. Comparing data from recent Murchison Widefield Array observations, we demonstrate that the foreground signatures that have the largest impact on the H i signal arise from power received far away from the primary field of view. We identify diffuse emission near the horizon as a significant contributing factor, even on wide antenna spacings that usually represent structures on small scales. For signals entering through the primary field of view, compact emission dominates the foreground contamination. These two mechanisms imprint a characteristic pitchfork signature on the “foreground wedge” in Fourier delay space. Based on these results, we propose that selective down-weighting of data based on antenna spacing and time can mitigate foreground contamination substantially by a factor of ∼100 with negligible loss of sensitivity.

  15. Chilled Mirror Dew Point Hygrometer (CM) Handbook

    SciTech Connect

    Ritsche, MT

    2005-01-01

    The CM systems have been developed for the ARM Program to act as a moisture standard traceable to National Institute of Standards and Technology (NIST). There are three CM systems that are each fully portable, self-contained, and require only 110 V AC power. The systems include a CM sensor, air sampling and filtration system, a secondary reference (Rotronic HP043 temperature and relative humidity sensor) to detect system malfunctions, a data acquisition system, and data storage for more than one month of 1-minute data. The CM sensor directly measures dew point temperature at 1 m, air temperature at 2 m, and relative humidity at 2 m. These measurements are intended to represent self-standing data streams that can be used independently or in combinations.

  16. Conducting Retrospective Ontological Clinical Trials in ICD-9-CM in the Age of ICD-10-CM

    PubMed Central

    Venepalli, Neeta K; Shergill, Ardaman; Dorestani, Parvaneh; Boyd, Andrew D

    2014-01-01

    OBJECTIVE To quantify the impact of International Classification of Disease 10th Revision Clinical Modification (ICD-10-CM) transition in cancer clinical trials by comparing coding accuracy and data discontinuity in backward ICD-10-CM to ICD-9-CM mapping via two tools, and to develop a standard ICD-9-CM and ICD-10-CM bridging methodology for retrospective analyses. BACKGROUND While the transition to ICD-10-CM has been delayed until October 2015, its impact on cancer-related studies utilizing ICD-9-CM diagnoses has been inadequately explored. MATERIALS AND METHODS Three high impact journals with broad national and international readerships were reviewed for cancer-related studies utilizing ICD-9-CM diagnoses codes in study design, methods, or results. Forward ICD-9-CM to ICD-10-CM mapping was performing using a translational methodology with the Motif web portal ICD-9-CM conversion tool. Backward mapping from ICD-10-CM to ICD-9-CM was performed using both Centers for Medicare and Medicaid Services (CMS) general equivalence mappings (GEMs) files and the Motif web portal tool. Generated ICD-9-CM codes were compared with the original ICD-9-CM codes to assess data accuracy and discontinuity. RESULTS While both methods yielded additional ICD-9-CM codes, the CMS GEMs method provided incomplete coverage with 16 of the original ICD-9-CM codes missing, whereas the Motif web portal method provided complete coverage. Of these 16 codes, 12 ICD-9-CM codes were present in 2010 Illinois Medicaid data, and accounted for 0.52% of patient encounters and 0.35% of total Medicaid reimbursements. Extraneous ICD-9-CM codes from both methods (Centers for Medicare and Medicaid Services general equivalent mapping [CMS GEMs, n = 161; Motif web portal, n = 246]) in excess of original ICD-9-CM codes accounted for 2.1% and 2.3% of total patient encounters and 3.4% and 4.1% of total Medicaid reimbursements from the 2010 Illinois Medicare database. DISCUSSION Longitudinal data analyses post-ICD-10

  17. Aerosol physical properties from satellite horizon inversion

    NASA Technical Reports Server (NTRS)

    Gray, C. R.; Malchow, H. L.; Merritt, D. C.; Var, R. E.; Whitney, C. K.

    1973-01-01

    The feasibility is investigated of determining the physical properties of aerosols globally in the altitude region of 10 to 100 km from a satellite horizon scanning experiment. The investigation utilizes a horizon inversion technique previously developed and extended. Aerosol physical properties such as number density, size distribution, and the real and imaginary components of the index of refraction are demonstrated to be invertible in the aerosol size ranges (0.01-0.1 microns), (0.1-1.0 microns), (1.0-10 microns). Extensions of previously developed radiative transfer models and recursive inversion algorithms are displayed.

  18. Global and local horizon quantum mechanics

    NASA Astrophysics Data System (ADS)

    Casadio, Roberto; Giugno, Andrea; Giusti, Andrea

    2017-02-01

    Horizons are classical causal structures that arise in systems with sharply defined energy and corresponding gravitational radius. A global gravitational radius operator can be introduced for a static and spherically symmetric quantum mechanical matter state by lifting the classical "Hamiltonian" constraint that relates the gravitational radius to the ADM mass, thus giving rise to a "horizon wave-function". This minisuperspace-like formalism is shown here to be able to consistently describe also the local gravitational radius related to the Misner-Sharp mass function of the quantum source, provided its energy spectrum is determined by spatially localised modes.

  19. Horizon detection and higher dimensional black rings

    NASA Astrophysics Data System (ADS)

    Coley, A. A.; McNutt, D. D.

    2017-02-01

    In this paper we study the stationary horizons of the rotating black ring and the supersymmetric black ring spacetimes in five dimensions. In the case of the rotating black ring we use Weyl aligned null directions to algebraically classify the Weyl tensor, and utilize an adapted Cartan algorithm in order to produce Cartan invariants. For the supersymmetric black ring we employ the discriminant approach and repeat the adapted Cartan algorithm. For both of these metrics we are able to construct Cartan invariants that detect the horizon alone, and which are easier to compute and analyse than scalar polynomial curvature invariants.

  20. Expanding your horizons in science and mathematics

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Through the presentation of its Expanding Your Horizons in Science and Mathematics career education conferences for secondary school young women, the Math/Science Network continues its efforts to remove the educational, psychological, and cultural barriers which prevent women from entering math-and science-based careers. The Expanding Your Horizons conferences were presented on 77 college, university and high school campuses across the United States. This year, these unique one day conferences reached 15,500 students, 3,000 parents and educators, and involved 3,000 career women who volunteered their services as conference planners, workshop leaders, speakers, and role models.

  1. Classification of Near-Horizon Geometries of Extremal Black Holes.

    PubMed

    Kunduri, Hari K; Lucietti, James

    2013-01-01

    Any spacetime containing a degenerate Killing horizon, such as an extremal black hole, possesses a well-defined notion of a near-horizon geometry. We review such near-horizon geometry solutions in a variety of dimensions and theories in a unified manner. We discuss various general results including horizon topology and near-horizon symmetry enhancement. We also discuss the status of the classification of near-horizon geometries in theories ranging from vacuum gravity to Einstein-Maxwell theory and supergravity theories. Finally, we discuss applications to the classification of extremal black holes and various related topics. Several new results are presented and open problems are highlighted throughout.

  2. Flux creep and irreversibility in electron-doped Pr 1.85Th 0.15CuO 4- y

    NASA Astrophysics Data System (ADS)

    Peng, J. L.; Greene, R. L.

    1990-12-01

    High-quality crystallites of Pr 1.85Th 0.15CuO 4- y were prepared by a solid state reaction technique and aligned in epoxy by a magnetic field. Magnetic relaxation of the remanent moment was measured with field H parallel to the ab plane. We interpret our data with a thermally activated flux creep model, and show that effective pinning energy U0 increases with increasing T between 2 and 15 K. We find that U0 is not strongly dependent on applied field. The crossover from reversible to irreversible magnetization was found to follow the power law H= H(0)(1- T/ Tc) 1.7. The value of U0 for H parallel to the ab plane is found to vary from ≈8 to ≈40 meV between 2 and 15 K, respectively. Compared to YBCO, pinning in the electron-doped system is rather weak.

  3. An AlN/Al0.85Ga0.15N high electron mobility transistor

    SciTech Connect

    Baca, Albert G.; Armstrong, Andrew M.; Allerman, Andrew A.; Douglas, Erica A.; Sanchez, Carlos A.; King, Michael P.; Coltrin, Michael E.; Fortune, Torben R.; Kaplar, Robert J.

    2016-07-22

    An AlN barrier high electron mobility transistor (HEMT) based on the AlN/Al0.85Ga0.15N heterostructure was grown, fabricated, and electrically characterized, thereby extending the range of Al composition and bandgap for AlGaN channel HEMTs. An etch and regrowth procedure was implemented for source and drain contact formation. A breakdown voltage of 810 V was achieved without a gate insulator or field plate. Excellent gate leakage characteristics enabled a high Ion/Ioff current ratio greater than 107 and an excellent subthreshold slope of 75 mV/decade. A large Schottky barrier height of 1.74 eV contributed to these results. In conclusion, the room temperature voltage-dependent 3-terminal off-state drain current was adequately modeled with Frenkel-Poole emission.

  4. Elastic anomalies in a La 1.85Sr 0.15CuO 4 single crystal under high magnetic fields

    NASA Astrophysics Data System (ADS)

    Hanaguri, Tetsuo; Fukase, Tetsuo; Suzuki, Takao; Tanaka, Isao; Kojima, Hironao

    1994-02-01

    Temperature dependence of the sound velocity Vs in a La 1.85Sr 0.15CuO 4 single crystal has been measured in the ( c11 - c12)/2 mode and in the c33 mode under high magnetic fields up to 23T. In the field above 6T, Vs in the ( c11 - c12)/2 mode anomalously decreases with decreasing temperature, followed by the increase below about 10K. In the c33 mode, similar behavior of Vs can be observed above 20T. Such a temperature dependence of Vs may suggest the existence of a strain sensitive narrow band near the Fermi level or a phase transition related to the flux line lattice.

  5. Nonlinear structure-composition relationships in the Ge1-ySny/Si(100) (y<0.15) system

    SciTech Connect

    Beeler, R.; Roucka, R.; Chizmeshya, A. V. G.; Kouvetakis, J.; Menéndez, J.

    2011-07-26

    The compositional dependence of the cubic lattice parameter in Ge1-ySny alloys has been revisited. Large 1000-atom supercell ab initio simulations confirm earlier theoretical predictions that indicate a positive quadratic deviation from Vegard's law, albeit with a somewhat smaller bowing coefficient, θ = 0.047 Å, than found from 64-atom cell simulations (θ = 0.063 Å). On the other hand, measurements from an extensive set of alloy samples with compositions y < 0.15 reveal a negative deviation from Vegard's law. The discrepancy with earlier experimental data, which supported the theoretical results, is traced back to an unexpected compositional dependence of the residual strain after growth on Si substrates. The experimental bowing parameter for the relaxed lattice constant of the alloys is found to be θ = -0.066 Å. Possible reasons for the disagreement between theory and experiment are discussed in detail.

  6. Unusual magnetoresistance in cubic B20 Fe0.85Co0.15Si chiral magnets

    SciTech Connect

    Huang, S. X.; Chen, Fei; Kang, Jian; Zang, Jiadong; Shu, G. J.; Chou, F. C.; Chien, C. L.

    2016-06-24

    The B20 chiral magnets with broken inversion symmetry and C4 rotation symmetry have attracted much attention. The broken inversion symmetry leads to the Dzyaloshinskii–Moriya that gives rise to the helical and Skyrmion states.Wereport the unusual magnetoresistance (MR) of B20 chiral magnet Fe0.85Co0.15Si that directly reveals the broken C4 rotation symmetry and shows the anisotropic scattering by Skyrmions with respect to the current directions. The intimacy between unusual MR and broken symmetry is well confirmed by theoretically studying an effective Hamiltonian with spin–orbit coupling. In conclusion, the unusual MR serves as a transport signature for the Skyrmion phase.

  7. Noise performance at cryogenic temperatures at AlGaAs/InGaAs HEMT's with 0.15- mu m T-shaped WSi/sub x/ gates

    NASA Astrophysics Data System (ADS)

    Joshin, K.; Mimino, Y.; Ohmura, S.; Hirachi, Y.

    1992-03-01

    T-shaped 0.15-μm WSix gate HEMTs have been fabricated on AlGaAs/InGaAs MBE wafers. Their S-parameters, output noise spectral density Pno, and noise temperatures T e at cryogenic temperatures, were measured. The current gain cutoff frequency fT increases from 61 GHz at 295 K to 87 GHz at 90 K. Pno and Te measurements indicate that the hot-electron effect is noticeable at low temperatures at high drain current. At 30 GHz, the noise temperature is 19±3 K with an associated gain of 10.4 dB at the physical temperature of 20 K. The results demonstrate the great potential of AlGaAs/InGaAs HEMTs for low-temperature applications.

  8. Characterization of phase transformation during hot compressive deformation in a β-stabilized Ti–45Al–7Nb–0.4W–0.15B alloy

    SciTech Connect

    Liu, Bin; Liu, Yong Huang, Lan; Li, Huizhong; He, Yuehui

    2015-07-15

    A β-stabilized Ti–45Al–7Nb–0.4W–0.15B (at.%) alloy was hot deformed by uniaxial compression and the phase evolution during the compression was characterized with X-ray diffraction, scanning electron microscopy and electron probe microanalysis. The results show that modest deformation stress during hot compression restrains the γ → α transformation and the decomposition of β phase. The restrained γ → α transformation is a result of a modified equilibrium of the γ and α phases due to the applied stress, and the restrained β decomposition is a kinetic effect due to the decelerated diffusion of β-stabilizing elements caused by the compressive stress. - Highlights: • In β-stabilized TiAl alloys, hot deformation has great influence on the equilibrium of the γ, α, and β phases. • Deformation restrains the γ → α transformation. • Deformation inhibits the decomposition of the β phase.

  9. Inflow Measurements Made with a Laser Velocimeter on a Helicopter Model in Forward Flight. Volume 1: Rectangular Planform Blades at an Advance Ration of 0.15

    NASA Technical Reports Server (NTRS)

    Elliott, Joe W.; Althoff, Susan L.; Sailey, Richard H.

    1988-01-01

    An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at NASA Langley to measure the inflow into a scale model helicopter rotor in forward flight (microinf = 0.15). The measurements were made with a two component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip path plane). A conditional sampling technique was employed to determine the azimuthal position of the rotor at the time each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 147 separate locations in order to clearly define the inflow character. This data is presented without analysis. In order to increase the availability of the resulting data, both the mean and azimuthally dependent values are included as part of this report on two 5.25 inch floppy disks in Microsoft Corporation MS-DOS format.

  10. Correlation of electrical, magnetic, and thermal properties of the La0.85Ag0.15MnO3 manganite near the phase transition temperature

    NASA Astrophysics Data System (ADS)

    Gamzatov, A. G.; Batdalov, A. B.; Kaul', A. R.; Mel'nikov, O. V.

    2011-01-01

    The correlation between electrical, magnetic, and lattice properties of manganites has been studied by analyzing the temperature dependence of the electrical resistivity of the La0.85Ag0.15MnO3 manganite. The results have been discussed within the model of a phase-separated manganite in terms of the percolation theory. It has been shown that, from analyzing the temperature and magnetic field dependences of the electrical resistivity, it is possible to predict the behavior of the magnetization and specific heat, as well as the change of magnetic entropy near the phase transition temperature, and that the obtained agreement with experimental data for this analysis is quite reasonable.

  11. Fluctuation conductivity and possible pseudogap state in FeAs-based superconductor EuFeAsO0.85F0.15

    NASA Astrophysics Data System (ADS)

    Solovjov, A. L.; Omelchenko, L. V.; Terekhov, A. V.; Rogacki, K.; Vovk, R. V.; Khlybov, E. P.; Chroneos, A.

    2016-07-01

    The study of excess conductivity σ \\prime (T) in the textured polycrystalline FeAs-based superconductor EuFeAsO0.85F0.15 ({T}{{c}}=11 {{K}}) prepared by the solid state synthesis is reported for the first time. The σ \\prime (T) analysis has been performed within the local pair (LP) model based on the assumption of the LPs formation in cuprate high-T c superconductors (cuprates) below the pseudogap (PG) temperature {T}* \\gg {T}{{c}}. Similarly to the cuprates, near {T}{{c}} σ \\prime (T) is adequately described by the 3D term of the Aslamasov-Larkin (AL) theory but the range of the 3D-AL fluctuations, {{Δ }}{T}3{{D}}, is relatively short. Above the crossover temperature {T}0≈ 11.7 {{K}} σ \\prime (T) is described by the 2D Maki-Thompson (MT) fluctuation term of the Hikami-Larkin theory. But enhanced 2D-MT fluctuation contribution being typical for the magnetic superconductors is observed. Within the LP model the PG parameter, {{{Δ }}}* (T), was determined for the first time. It is shown that {{{Δ }}}* (T) demonstrates the narrow maximum at {T}s≈ 160 {{K}} followed by the descending linear length down to {T}{SDW}={T}{NFe}≈ 133 {{K}}. Observed small {{Δ }}{T}3{{D}}, enlarged 2D σ \\prime (T) and linear {{{Δ }}}* (T) are considered to be the evidence of the enhanced magnetic interaction in EuFeAsO0.85F0.15. Importantly, the slop of the linear {{{Δ }}}* (T) and its length are found to be the same as it is revealed for SmFeAsO0.85. The results suggest both the similarity of the magnetic interaction processes in different Fe-pnictides and applicability of the LP model to the σ \\prime (T) analysis even in magnetic superconductors.

  12. Evaluation of irradiation hardening of ion-irradiated V-4Cr-4Ti and V-4Cr-4Ti-0.15Y alloys by nanoindentation techniques

    NASA Astrophysics Data System (ADS)

    Miyazawa, Takeshi; Nagasaka, Takuya; Kasada, Ryuta; Hishinuma, Yoshimitsu; Muroga, Takeo; Watanabe, Hideo; Yamamoto, Takuya; Nogami, Shuhei; Hatakeyama, Masahiko

    2014-12-01

    Irradiation hardening behavior of V-4Cr-4Ti and V-4Cr-4Ti-0.15Y alloys after Cu-ion beam irradiation were investigated with a combination between nanoindentation techniques and finite element method (FEM) analysis. The ion-irradiation experiments were conducted at 473 K with 2.4 MeV Cu2+ ions up to 7.6 dpa. For the unirradiated materials, the increase in nanoindentation hardness with decreasing indentation depth, so-called indentation size effect (ISE), was clearly observed. After irradiation, irradiation hardening in the measured depth was identified. Hardening behavior of bulk-equivalent hardness for V-4Cr-4Ti-0.15Y alloy was similar to that for V-4Cr-4Ti alloy. Y addition has little effect on irradiation hardening at 473 K. Adding the concept of geometrically necessary dislocations (GNDs) to constitutive equation of V-4Cr-4Ti alloy, the ISE was simulated. A constant value of α = 0.5 was derived as an optimal value to simulate nanoindentation test for ion-irradiated V-4Cr-4Ti alloy. Adding the term of irradiation hardening Δσirrad. to constitutive equation with α = 0.5, FEM analyses for irradiated surface of V-4Cr-4Ti alloy were carried out. The analytic data of FEM analyses based on neutron-irradiation hardening equivalent to 3.0 dpa agreed with the experimental data to 0.76 dpa. The comparison indicates that irradiation hardening by heavy ion-irradiation is larger than that by neutron-irradiation at the same displacement damage level. Possible mechanisms for extra hardening by heavy ion-irradiation are the processes that the injected Cu ions could effectively produce irradiation defects such as interstitials compared with neutrons, and that higher damage rate of ion-irradiation enhanced nucleation of irradiation defects and hence increased the number density of the defects compared with neutron-irradiation.

  13. Detections of 2 cm formaldehyde emissions towards Galactic star-forming regions with 6 cm counterpart

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Shen, Zhi-Qiang; Li, Xiao-Qiong; Yang, Kai; Li, Juan; Wang, Jun-Zhi; Wu, Ya-Jun; Zhao, Rong-Bin; Wang, Jin-Qing; Dong, Jian; Jiang, Dong-Rong; Li, Bin

    2017-01-01

    We report the detections of H2CO emission at the 2 cm transition towards Galactic star-forming regions with known 6 cm counterpart using the Shanghai Tianma Radio Telescope (TMRT). One significant detection (in NGC7538) and two possible detections (in G23.01-0.41 and G29.96-0.02) were made. Comparing with previous observations, we found that there is a time lag of appearance of 2 cm and 6 cm emissions detected in NGC7538, contradicting with the prediction of radiative pumping via radio continuum radiation. Combinations of the variability of 6 cm masers in NGC7538 suggest that collisional pumping via high-velocity shocks could better explain the 6 cm H2CO maser emission. Under this scheme, excitation of the 2 cm maser may require a higher collision energy compared to the 6 cm transition.

  14. Magnetoelectric properties of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 - CoFe2O4 particulate composites

    NASA Astrophysics Data System (ADS)

    Paul Praveen, J.; Vinitha Reddy, M.; Das, Dibakar

    2016-05-01

    0.7[(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3)]-0.3[CoFe2O4] multiferroic particulate ceramic composite with (0-3) connectivity has been synthesized by wet chemical methods. BCZT-CFO composite showed both polarization-electric field and magnetic hysteresis loops simultaneously at room temperature. A high dielectric constant of 2160 and tangent loss factor of 0.6 has been obtained. Magnetoelectric (ME) voltage coefficient (αME =dE/dH) of the composite was measured as a function of applied d.c magnetic field at different frequencies. At resonance frequency (365kHz) the composite showed a maximum αME of 102mV/cm.Oe. It was observed that the transverse ME coefficient is 1.8 times higher than the longitudinal ME coefficient. The magnetoelectric properties of this composite has been studied in detail in this work and correlated with its structure.

  15. (Bi0.15La0.27Sr0.53)(Co0.25Fe0.75)O3-δ perovskite: A novel cathode material for intermediate temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Khaerudini, Deni S.; Guan, Guoqing; Zhang, Peng; Xiaoketi, Pairuzha; Hao, Xiaogang; Wang, Zhongde; Kasai, Yutaka; Abudula, Abuliti

    2016-12-01

    Perovskite oxides (Bi0.15La0.27Sr0.53)x(Co0.25Fe0.75)O3-δ (BiLSCFx, x = 0.8, 0.9, 1.0, 1.1) have been synthesized by solid state reaction and evaluated as a novel cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The effects of A-site variations on lattice structure, calcination temperature, oxygen desorption and electrochemical properties of BiLSCFx are investigated. This kind of material has perfectly cubic structure based on the Pm-3m space group whose lattice size increases with x, which is thermally stable after calcination and shows desirable chemical compatibility with La0.8Sr0.2Ga0.8Mg0.2O3-δ electrolyte at 1150 °C for 8 h under air atmosphere. Among those A-site variations, it is found that BiLSCF0.9 demonstrates the best cathode performance. It has the minimum polarization resistance value of 0.039 Ω cm2 at 700 °C and α-oxygen desorbed about 0.031 mmol g-1, indicating a good reactivity and strong adsorbate of O2. The single cell with BiLSCF0.9 cathode delivers a power density of 0.66 W cm-2 at 700 °C with humidified H2 (∼3% H2O) as the fuel and ambient air as the oxidant. In addition, the cell shows sufficient stability with ∼9% degradation over 75 h at 600 °C. It indicates that BiLSCF0.9 is a promising candidate for application as cathode material in IT-SOFCs.

  16. Detection of Thermal 2 cm and 1 cm Formaldehyde Emission in NGC 7538

    NASA Astrophysics Data System (ADS)

    Yuan, Liang; Araya, E. D.; Hofner, P.; Kurtz, S.; Pihlstrom, Y.

    2011-05-01

    Formaldehyde is a tracer of high density gas in massive star forming regions. The K-doublet lines from the three lowest rotational energy levels of ortho-formaldehyde correspond to wavelengths of 6, 2 and 1 cm. Thermal emission of these transitions is rare, and maser emission has only been detected in the 6 cm line. NGC 7538 is an active site of massive star formation in the Galaxy, and one of only a few regions known to harbor 6 cm formaldehyde (H2CO) masers. Using the NRAO 100 m Green Bank Telescope (GBT), we detected 2 cm H2CO emission toward NGC 7538 IRS1. The velocity of the 2 cm H2CO line is very similar to the velocity of one of the 6 cm H2CO masers but the linewidth is greater. To investigate the nature of the 2 cm emission, we conducted observations of the 1 cm H2CO transition, and obtained a cross-scan map of the 2 cm line. We detected 1 cm emission and found that the 2 cm emission is extended (greater than 30"), which implies brightness temperatures of ˜0.2 K. Assuming optically thin emission, LTE, and that the 1 cm and 2 cm lines originate from the same volume of gas, both these detections are consistent with thermal emission of gas at ˜30 K. We conclude that the 1 cm and 2 cm H2CO lines detected with the GBT are thermal, which implies molecular densities above ˜105 cm-3. LY acknowledges support from WIU. PH acknowledges partial support from NSF grant AST-0908901.

  17. Gateway's Horizon: A Center of Excellence

    ERIC Educational Resources Information Center

    Herring, Jayne; Colony, Lee

    2007-01-01

    This article describes Gateway Technical College's Horizon Center for Transportation Technology, located in Kenosha, Wisconsin, which was the product of collaboration with business and industry, community support and a U.S. Department of Labor (DOL) grant. The center, which opened this fall, is a prime example of a sustainable community…

  18. Senior Adult Bands: Music's New Horizon.

    ERIC Educational Resources Information Center

    Coffman, Don D.; Levy, Katherine M.

    1997-01-01

    Discusses the success of Iowa City's (Iowa) New Horizons Band that consists of 55 senior adult beginners and former instrumentalists. Describes the organization of the band program, the senior's performance skills and commitment, and the ongoing challenges. Gives a selected listing of the music the band plays at concerts and other events. (CMK)

  19. Teachers' Beliefs about Mathematical Horizon Content Knowledge

    ERIC Educational Resources Information Center

    Mosvold, Reidar; Fauskanger, Janne

    2014-01-01

    In this article, we present and discuss an example of how teachers' discussions of mathematical knowledge for teaching (MKT) items elicited their beliefs about the knowledge needed to teach mathematics. One category of MKT is "horizon content knowledge," and this can be described as mathematical knowledge not directly deployed in…

  20. HIGHER HORIZONS, A PROGRAM FOR YOUR CHILD.

    ERIC Educational Resources Information Center

    New York City Board of Education, Brooklyn, NY.

    PARENTS ARE TOLD THAT HIGHER HORIZONS WILL HELP DEVELOP THE CAPACITIES OF EVERY CHILD, INCREASE HIS SELF CONFIDENCE, AND HELP HIM COMPLETE HIGH SCHOOL. RESULTS OF TESTS AND INTERVIEWS TO DISCOVER A CHILD'S ABILITIES, INTERESTS, AND NEEDS ARE DISCUSSED IN PARENT-TEACHER CONFERENCES. INSTRUCTION IS AIMED AT DEVELOPING ABILITIES. THE CHILD IS…

  1. Space Launch Initiative: New Capabilities - New Horizons

    NASA Technical Reports Server (NTRS)

    Dumbacher, Daniel; Smith, Dennis E. (Technical Monitor)

    2002-01-01

    This paper presents NASA's Space Launch Initiative (SLI) with new capabilities and new horizons. The topics include: 1) Integrated Space Transportation Plan; 2) SLI: The Work of a Nation; 3) SLI Goals and Status; 4) Composites and Materials; and 5) SLI and DOD/USAF Collaboration. This paper is in viewgraph form.

  2. New Concepts on the Educational Horizon.

    ERIC Educational Resources Information Center

    Gilchrist, Robert S.; Mitchell, Edna

    Four dimensions in education provide a basis for discussing future horizons: (1) curriculum development, (2) teacher education, (3) administration and organization, and (4) research and development. These areas are interdependent, and one cannot be improved or changed without affecting the other areas. Within these areas, some of the broad changes…

  3. Finite Horizon H Infinity with Parameter Variations

    DTIC Science & Technology

    1992-05-01

    International Journal of Robust and Nonlinear Control, to appear. SUBRAHMANYAM, M. B., 1992d, Worst-case optimal control over a finite horizon, Journal of Mathematical Analysis and Applications , to...in linear systems, Journal of Mathematical Analysis and Applications , 164, 130-150. SUBRAHMANYAM, M. B., 1991, H, 0 optimal control theory over a

  4. Sighting Horizons of Teaching in Higher Education

    ERIC Educational Resources Information Center

    Barnett, Ronald; Guzmán-Valenzuela, Carolina

    2017-01-01

    This conceptual paper tackles the matter of teaching in higher education and proposes a concept of "horizons of teaching." It firstly offers an overview of the considerable empirical literature around teaching--especially conceptions of teaching, approaches to teaching and teaching practices--and goes on to pose some philosophical and…

  5. The NMC Horizon Report: 2013 Museum Edition

    ERIC Educational Resources Information Center

    Johnson, L.; Adams Becker, S.; Freeman, A.

    2013-01-01

    The "NMC Horizon Report: 2013 Museum Edition," is a co-production with the Marcus Institute for Digital Education in the Arts (MIDEA), and examines six emerging technologies for their potential impact on and use in education and interpretation within the museum environment: BYOD (Bring Your Own Device), crowdsourcing, electronic…

  6. Falling through the black hole horizon

    NASA Astrophysics Data System (ADS)

    Brustein, Ram; Medved, A. J. M.

    2015-06-01

    We consider the fate of a small classical object, a "stick", as it falls through the horizon of a large black hole (BH). Classically, the equivalence principle dictates that the stick is affected by small tidal forces, and Hawking's quantum-mechanical model of BH evaporation makes essentially the same prediction. If, on the other hand, the BH horizon is surrounded by a "firewall", the stick will be consumed as it falls through. We have recently extended Hawking's model by taking into account the quantum fluctuations of the geometry and the classical back-reaction of the emitted particles. Here, we calculate the train exerted on the falling stick for our model. The strain depends on the near-horizon state of the Hawking pairs. We find that, after the Page time when the state of the pairs deviates significantly from maximal entanglement (as required by unitarity), the induced strain in our semiclassical model is still parametrically small. This is because the number of the disentangled pairs is parametrically smaller than the BH entropy. A firewall does, however, appear if the number of disentangled pairs near the horizon is of order of the BH entropy, as implicitly assumed in previous discussions in the literature.

  7. Occurrence of perched saturation and interflow over an argillic horizon in a low relief hillslope.

    SciTech Connect

    Greco, James; Jackson, Rhett, C.

    2009-03-01

    Abstract. Many of the soils in the south-eastern US are characterized by an argillic, or clay horizon, that largely parallels the soil surface at depths ranging from a few centimeters to 100 cen-timeters. The degree to which these argillic horizons alter subsurface movement of infiltrated water is not well known. Interflow, or throughflow, is shallow lateral subsurface flow that moves over a horizon that restricts percolation. This research investigates how often and under what conditions a relatively deep (20-150+cm) argillic horizon on low slope (2-6%) hillsides causes interflow to oc-cur. Research is being conducted at the Savannah River Site, Aiken, South Carolina, on a small zero-order watershed. In the first phase of this research, a high resolution topographic map of the clay layer was developed. This map will be used to instrument designated “low” spots with max rise piezo-meters in order to determine if there is channelized subsurface flow. In situ conductivities of the clay layer and the surface horizons were measured using an Amoozegar meter, and bulk density samples were taken and measured. Along with soil topographic measurements, data-logging piezometers have been installed to measure the piezometric head above, in, and below the argillic horizon to further investigate interflow as a potential hydraulic routing mechanism. The stream that drains the catchment was instrumented with a 2’ H flume and data-logging pressure transducer to measure stream flow. Climate data including precipitation, barometric pressure and temperature, are being continuously collected in an open area approximately ¼ mile from the study site. Combining the shallow surface and subsurface piezometric heads with stream flow rates, we should be able to determine if and when the clay layer is contributing to inter-flow.

  8. Probing lepton asymmetry with 21 cm fluctuations

    SciTech Connect

    Kohri, Kazunori; Oyama, Yoshihiko; Sekiguchi, Toyokazu; Takahashi, Tomo E-mail: oyamayo@post.kek.jp E-mail: tomot@cc.saga-u.ac.jp

    2014-09-01

    We investigate the issue of how accurately we can constrain the lepton number asymmetry ξ{sub ν}=μ{sub ν}/T{sub ν} in the Universe by using future observations of 21 cm line fluctuations and cosmic microwave background (CMB). We find that combinations of the 21 cm line and the CMB observations can constrain the lepton asymmetry better than big-bang nucleosynthesis (BBN). Additionally, we also discuss constraints on ξ{sub ν} in the presence of some extra radiation, and show that the 21 cm line observations can substantially improve the constraints obtained by CMB alone, and allow us to distinguish the effects of the lepton asymmetry from the ones of extra radiation.

  9. The structure and temperature of Pluto's Sputnik Planum using 4.2 cm radiometry

    NASA Astrophysics Data System (ADS)

    Linscott, Ivan; Protopapa, Silvia; Hinson, David P.; Bird, Mike; Tyler, G. Leonard; Grundy, William M.; McKinnon, William B.; Olkin, Catherine B.; Stern, S. Alan; Stansberry, John A.; Weaver, Harold A.; Pluto Composition Team, Pluto Geophysics and Geology Team, Pluto Atmospheres Team

    2016-10-01

    New Horizons measured the radiometric brightness temperature of Pluto at 4.2 cm, during the encounter with two scans of the spacecraft's high gain antenna shortly after closest approach. The Pluto mid-section scan included the region informally known as Sputnik Planum, now understood to be filled with nitrogen ice. The mean radiometric brightness temperature at 4.2 cm, obtained in this region is 25 K, for both Right Circular Polarization (RCP) and Left Circular Polarization (LCP), well below the sublimation temperature for nitrogen ice. Sputnik Planum was near the limb and the termination of the radiometric scan. Consequently, the thermal emission was measured obliquely over a wide range of emission angles. This geometry affords detailed modeling of the angular dependence of the thermal radiation, incorporating surface and subsurface electromagnetic scattering models as well as emissivity models of the nitrogen ice. In addition, a bistatic radar measurement detected the scattering of a 4.2 cm uplink transmitted from Earth. The bistatic specular point was within Sputnik Planum and the measurements are useful for constraining the dielectric constant as well as the surface and subsurface scattering functions of the nitrogen ice. The combination of the thermal emission's angular dependence, RCP and LCP polarization dependence, and the bistatic scattering, yields estimates of the radiometric thermal emissivity, nitrogen ice temperature and spatial correlation scales.This work is supported by the NASA New Horizons Mission.

  10. 21 CM searches for DIM galaxies

    NASA Astrophysics Data System (ADS)

    Disney, Mike; Banks, Gareth

    1997-04-01

    We review very strong selection effects which operate against the detection of dim (i.e. low surface brightness) galaxies. The Parkes multibeam instrument offers a wonderful opportunity to turn up new populations of such galaxies. However, to explore the newly accessible parameter space, it will be necessary to survey both a very deep patch (105 s/pointing, limiting N hi ˜ 1018 cm-2) and a deep patch (104 s/pointing, limiting N hi ˜ 3 × 1018 cm-2) in carefully selected areas, and we outline the case to do this.

  11. A novel lead compound CM-118

    PubMed Central

    Meng, Lanfang; Shu, Mengjun; Chen, Yaqing; Yang, Dexiao; He, Qun; Zhao, Hui; Feng, Zhiyong; Liang, Chris; Yu, Ker

    2014-01-01

    The anaplastic lymphoma kinase (ALK) and the c-Met receptor tyrosine kinase play essential roles in the pathogenesis in multiple human cancers and present emerging targets for cancer treatment. Here, we describe CM-118, a novel lead compound displaying low nanomolar biochemical potency against both ALK and c-Met with selectivity over >90 human kinases. CM-118 potently abrogated hepatocyte growth factor (HGF)-induced c-Met phosphorylation and cell migration, phosphorylation of ALK, EML4-ALK, and ALK resistance mutants in transfected cells. CM-118 inhibited proliferation and/or induced apoptosis in multiple c-Met- and ALK-addicted cancer lines with dose response profile correlating target blockade. We show that the CM-118-induced apoptosis in c-Met-amplified H1993 NSCLC cells involved a rapid suppression of c-Met activity and c-Met-to-EGFR cross-talk, and was profoundly potentiated by EGFR inhibitors as shown by the increased levels of apoptotic proteins cleaved-PARP and Bim as well as reduction of the survival protein Mcl-1. Bim-knockdown or Mcl-1 overexpression each significantly attenuated apoptosis. We also revealed a key role by mTOR in mediating CM-118 action against the EML4-ALK-dependent NSCLC cells. Abrogation of EML4-ALK in H2228 cells profoundly reduced signaling capacity of the rapamycin-sensitive mTOR pathway leading to G1 cell cycle arrest and mitochondrial hyperpolarization, a metabolic perturbation linked to mTOR inhibition. Depletion of mTOR or mTORC1 inhibited H2228 cell growth, and mTOR inhibitors potentiated CM-118’s antitumor activity in vitro and in vivo. Oral administration of CM-118 at a wide range of well tolerated dosages diminished c-Met- and ALK phosphorylation in vivo, and caused tumor regression or growth inhibition in multiple c-Met- and ALK-dependent tumor xenografts in mice. CM-118 exhibits favorable pharmacokinetic and drug metabolism properties hence presents a candidate for clinical evaluation. PMID:24618813

  12. Soft hairs on isolated horizon implanted by electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Mao, Pujian; Wu, Xiaoning; Zhang, Hongbao

    2017-03-01

    Inspired by the recent proposal of soft hair on black holes in Hawking et al (2016 Phys. Rev. Lett. 116 231301), we have shown that an isolated horizon carries soft hairs implanted by electromagnetic fields. The solution space and the asymptotic symmetries of Einstein–Maxwell theory have been worked out explicitly near the isolated horizon. The conserved current has been computed and an infinite number of near horizon charges have been introduced from the electromagnetic fields associated with the asymptotic U(1) symmetry near the horizon, which indicates the fact that the isolated horizon carries a large amount of soft electric hairs. The soft electric hairs, i.e. asymptotic U(1) charges, are shown to be equivalent to the electric multipole moments of isolated horizons. It is further argued that the isolated horizon supertranslation is from the ambiguity of its foliation and an analogue of memory effect on horizon can be expected.

  13. The Pluto System As Seen By New Horizons Spacecraft

    NASA Video Gallery

    The Pluto system as NASA’s New Horizons spacecraft saw it in July 2015. This animation, made with real images taken by New Horizons, begins with Pluto flying in for its close-up on July 14; we then...

  14. SETAC launches global horizon scanning/research prioritization project

    EPA Science Inventory

    The SETAC World Council is pleased to announce the initiation of a Global Horizon Scanning and Prioritization Project aimed at identifying geographically specific research needs to address stressor impacts on environmental quality. In recent years, horizon scanning and research ...

  15. [Cutaneous Melanoma (CM): Current Diagnosis and Treatment].

    PubMed

    Gallegos Hernández, José Francisco; Nieweg, Omgo E

    2014-12-01

    Cutaneous melanoma (CM) is the third most common cancer of the skin, but it is the neoplasia with the greatest impact on mortality. Its etiology is multifactorial and it has been reported that its prevalence has increased in the last two decades. In Mexico, CM ranks seventh in frequency among all malignancies and 80% of cases are in locally advanced stages. The prognosis depends on the stage. The prognostic factors with greatest impact in survival are nodal status, tumor thickness or Breslow depth, ulceration, and in thin melanomas (< 1 mm thickness, without ulceration and Clarck level III), the mitotic index. The diagnostic approach is of great importance to achieve adequate treatment. Adherence to global guidelines of treatment allows us to obtain the best rates of locoregional control, which is the first target to be achieved in patients with CM. The goal of this manuscript is to provide a synthesis of the most important aspects in the diagnosis and treatment of CM, based on current evidence obtained in the literature.

  16. Neutron Resonance Parameters for Cm-242 (Curium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Cm-242 (Curium).

  17. Anomalous RR Lyrae stars(?): CM Leonis

    NASA Astrophysics Data System (ADS)

    Di Fabrizio, L.; Clementini, G.; Marconi, M.; Carretta, E.; Ivans, I. I.; Bragaglia, A.; Di Tomaso, S.; Merighi, R.; Smith, H. A.; Sneden, C.; Tosi, M.

    2002-11-01

    Time-series of B, V, I CCD photometry and radial velocity measurements from high-resolution spectroscopy (R= 30 000) covering the full pulsation cycle are presented for the field RR Lyrae star CM Leonis. The photometric data span a 6-yr interval from 1994 to 1999, and allow us to firmly establish the pulsation mode and periodicity of the variable. The derived period P= 0.361 699 d (+/-0.000001) is very close to the value published in the Fourth Edition of the General Catalogue of Variable Stars (P= 0.361 732 d). However, contrary to what was previously found, the amplitude and shape of the light curve qualify CM Leo as a very regular first overtone pulsator with a prominent hump on the rising branch of its multicolour light curves. According to an abundace analysis performed on three spectra taken near minimum light (0.42 < φ < 0.61), CM Leo is a metal-poor star with metal abundance [Fe/H]=-1.93 +/- 0.20. The photometric and radial velocity curves of CM Leo have been compared with the predictions of suitable pulsational models to infer tight constraints on the stellar mass, effective temperature, and distance modulus of the star. We derive a true distance modulus of CM Leo of μ0= 13.11 +/- 0.02 mag and a corresponding absolute magnitude of MV= 0.47 +/- 0.04. This absolute magnitude, once corrected for evolutionary and metallicity effects, leads to a true distance modulus of the Large Magellanic Cloud of μ0= 18.43 +/- 0.06 mag, in better agreement with the long astronomical distance scale.

  18. Towards the 1-cm SARAL orbit

    NASA Astrophysics Data System (ADS)

    Zelensky, Nikita P.; Lemoine, Frank G.; Chinn, Douglas S.; Beckley, Brian D.; Bordyugov, Oleg; Yang, Xu; Wimert, Jesse; Pavlis, Despina

    2016-12-01

    We have investigated the quality of precise orbits for the SARAL altimeter satellite using Satellite Laser Ranging (SLR) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) data from March 14, 2013 to August 10, 2014. We have identified a 4.31 ± 0.14 cm error in the Z (cross-track) direction that defines the center-of-mass of the SARAL satellite in the spacecraft coordinate system, and we have tuned the SLR and DORIS tracking point offsets. After these changes, we reduce the average RMS of the SLR residuals for seven-day arcs from 1.85 to 1.38 cm. We tuned the non-conservative force model for SARAL, reducing the amplitude of the daily adjusted empirical accelerations by eight percent. We find that the best dynamic orbits show altimeter crossover residuals of 5.524 cm over cycles 7-15. Our analysis offers a unique illustration that high-elevation SLR residuals will not necessarily provide an accurate estimate of radial error at the 1-cm level, and that other supporting orbit tests are necessary for a better estimate. Through the application of improved models for handling time-variable gravity, the use of reduced-dynamic orbits, and through an arc-by-arc estimation of the C22 and S22 coefficients, we find from analysis of independent SLR residuals and other tests that we achieve 1.1-1.2 cm radial orbit accuracies for SARAL. The limiting errors stem from the inadequacy of the DPOD2008 and SLRF2008 station complements, and inadequacies in radiation force modeling, especially with respect to spacecraft self-shadowing and modeling of thermal variations due to eclipses.

  19. Magneto-transport characteristics of electron-doped Ca0.85Sm0.15MnO3 manganite: Hopping and tunneling

    NASA Astrophysics Data System (ADS)

    Hossain Khan, Momin; Pal, Sudipta

    2015-11-01

    In this work we have reported the temperature and magnetic field dependence of resistivity and magnetoresistance in electron-doped polycrystalline Ca0.85Sm0.15MnO3 (CSMO). It shows a robust semiconducting behavior down to the lowest temperature (5 K) of investigation. High-T resistivity of the present sample follows small polaron hopping (SPH) conduction mechanism. The variable range hopping (VRH) model has been found to fit low-T resistivity data. Intermediate-temperature ρ(T) data has been explained using a parallel combination of SPH and 3D-VRH model. The resistivity shows strong dependence on the magnetic field-temperature history. Magnetoresistance (MR) of the sample shows strong irreversibility with respect to sweeping of the field between the highest positive and negative values. Low-ρ state of the envelope curve in MR indicates a manifestation of kinetic arrest of the electronic phase on application of magnetic field. We demonstrates that the sizable MR at low fields dominated by spin-polarized tunneling between the adjacent grains.

  20. Re-construction layer effect of LiNi0.8Co0.15Mn0.05O2 with solvent evaporation process.

    PubMed

    Park, Kwangjin; Park, Jun-Ho; Hong, Suk-Gi; Choi, Byungjin; Heo, Sung; Seo, Seung-Woo; Min, Kyoungmin; Park, Jin-Hwan

    2017-03-20

    The solvent evaporation method on the structural changes and surface chemistry of the cathode and the effect of electrochemical performance of Li1.0Ni0.8Co0.15Mn0.05O2 (NCM) has been investigated. After dissolving of Li residuals using minimum content of solvent in order to minimize the damage of pristine material and the evaporation time, the solvent was evaporated without filtering and remaining powder was re-heated at 700 °C in oxygen environment. Two kinds of solvent, de-ionized water and diluted nitric acid, were used as a solvent. The almost 40% of Li residuals were removed using solvent evaporation method. The NCM sample after solvent evaporation process exhibited an increase in the initial capacity (214.3 mAh/g) compared to the pristine sample (207.4 mAh/g) at 0.1C because of enhancement of electric conductivity caused by decline of Li residuals. The capacity retention of NCM sample after solvent evaporation process (96.0% at the 50th cycle) was also improved compared to that of the pristine NCM sample (90.6% at the 50th cycle). The uniform Li residual layer after solvent treated and heat treatment acted like a coating layer, leading to enhance the cycle performance. The NCM sample using diluted nitric acid showed better performance than that using de-ionized water.

  1. Characterization and improvement of field CD uniformity for implementation of 0.15-μm technology device using KrF stepper

    NASA Astrophysics Data System (ADS)

    Hyun, Yoon-Suk; Kim, Dong-Joo; Koh, Cha-Won; Park, Sung-Nam; Kwon, Won-Taik

    2003-06-01

    xAs the design rule of semiconductor device shrinks, the field CD uniformity gets more important. For mass production of 0.15 μm technology device using KrF stepper having 0.63NA, the improvement of field CD uniformity was one of key issues because field CD uniformity is directly related to device characteristics in some layers. We have experienced steppers that show poor illumination uniformity. With those steppers there was large CD difference of about 10nm between field center and field edges as shown in Figure 1. Although we were using verified reticles, we could not get an acceptable CD uniformity in a field with those steppers. The Field CD uniformity is dominantly dependent of the illumination uniformity of stepper and mask quality. With these optimization, we could control DICD difference between field center and edge to be less than 5nm. In this paper, we characterized the dependency of field CD uniformity according to illumination systems with stepper and scanner, annular illumination uniformity at various stigma, mask CD uniformity and the several types of novel gray filter specifically developed.

  2. Microstructures of La 1.85Sr 0.15CuO 4 doped with Ni at high doping level

    NASA Astrophysics Data System (ADS)

    Wu, X. S.; Jiang, S. S.; Pan, F. M.; Lin, J.; Xu, N.; Mao Zhiqiang; Xu Gaoji; Zhang Yuheng

    1996-02-01

    Ceramic superconductors of La 1.85Sr 0.15Cu 1- yNi yO 4 with 0.00 ≤ y ≤ 0.50 were synthesized. There is no impurity phase detected in the entire Ni doped region. The structure of these Ni-doped samples was characterized by X-ray diffraction studies. The atomic structural parameters were obtained by Rietveld refinements for the Ni-doped samples with y ≤ 0.50. Some meaningful bond distances were determined according to the refined results. According to the variations of some bond distances with y, the whole doping range could be divided into two regions: low doping level (LDL) and high doping level (HDL). The bond length between the two apical oxygen atoms in the CuO 6 octahedra for the Ni-doped samples increased with increasing content of Ni in the LDL, and decreased in the HDL. The average bond distance of LaO was not changed in the whole doping region. The metal-insulator transition was also observed in this Ni-doped system.

  3. Carrier leakage into the continuum in diagonal GaAs/Al{sub 0.15}GaAs terahertz quantum cascade lasers

    SciTech Connect

    Albo, Asaf Hu, Qing

    2015-12-14

    The maximum operating temperature reported so far for THz-QCLs is ∼200 K. With the well-known degradation mechanism of thermally activated LO-phonon scattering, one straightforward strategy to improve their temperature performances is the use of diagonal structures in which the upper-to-lower state scattering time is lengthened. However, the effectiveness of this method for achieving room temperature operation remains to be demonstrated. Here, we studied the temperature degradation of highly diagonal GaAs/Al{sub 0.15}GaAs THz-QCLs. By analyzing their output power dependence on temperature, we identified the physical mechanism that limits their performance to be thermally activated leakage into the continuum, as evidenced by the large activation energy of ∼80 meV extracted from the Arrhenius plot. This observation is further supported by a careful analysis of current-voltage characteristics, especially in regions of high biases. In order to significantly improve the temperature performances of diagonal THz-QCLs, this leakage should be eliminated.

  4. Microstructures of YBa1.85Eu0.15Cu3O7-δ superconducting films grown on SrTiO3 and YSZ substrates

    NASA Astrophysics Data System (ADS)

    Xie, Qiyun; Gu, Mingqiang; Qian, Bin; Wu, Xiaoshan; Jiang, Zhengsheng; Zou, Jin; Gao, Ju

    2011-03-01

    A detailed atomic scale microstructure analysis of Eu-doped YBa1.85Eu0.15Cu3O7-δ (YEBCO) thin films with 100 nm in thickness has been carried out by a combination of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Interesting regular-like arranged network of nanoscale undulations is observed on the surface of YEBCO film on (0 0 1) SrTiO3 substrate. TEM image clearly indicates that the film is always c-axis oriented, but lots of natural precipitates of Y2O3 are involved both at the interface and deep in the film. Desirable size and number density of Y2O3 are thought to be important for acting as efficient flux pinning centers. In the case of YEBCO film on (0 0 1) yttrium stabilized ZrO2 (YSZ) substrate, few cracks and outgrowths appear due to much larger lattice mismatch and dissimilar crystal structure between the film and substrate, but surface quality is still much better compared to the parent YBaCu3O7-δ film. Besides, highly textured BaZrO3 layer at the interface and a-axis grains with small dimensions in the film are formed. Interface stability of two kinds of films studied, namely YEBCO/STO and YEBCO/YSZ, is also assessed comprehensively by first principle calculations.

  5. Tuning the Activity of Oxygen in LiNi0.8Co0.15Al0.05O2 Battery Electrodes.

    PubMed

    Karki, Khim; Huang, Yiqing; Hwang, Sooyeon; Gamalski, Andrew D; Whittingham, M Stanley; Zhou, Guangwen; Stach, Eric A

    2016-10-06

    Layered transition metal oxides such as LiNi0.8Co 0.15Al0.05O2 (NCA) are highly desirable battery electrodes. However, these materials suffer from thermal runaway caused by deleterious oxygen loss and surface phase transitions when in highly overcharged and overheated conditions, prompting serious safety concerns. Using in situ environmental transmission electron microscopy techniques, we demonstrate that surface oxygen loss and structural changes in the highly overcharged NCA particles are suppressed by exposing them to an oxygen-rich environment. The onset temperature for the loss of oxygen from the electrode particle is delayed to 350 °C at oxygen gas overpressure of 400 mTorr. Similar heating of the particles in a reducing hydrogen gas demonstrated a quick onset of oxygen loss at 150 °C and rapid surface degradation of the particles. The results reported here illustrate the fundamental mechanism governing the failure processes of electrode particles and highlight possible strategies to circumvent such issues.

  6. Structural, magnetic and electrical transport properties in electron-doped La0.85Hf0.15MnO3 epitaxial film

    NASA Astrophysics Data System (ADS)

    Han, Li-an; Ma, Zi-wei; Zhu, Hua-ze; Chen, Chang-le; Zhang, Tao

    2017-03-01

    Using a pulsed laser deposition method, the electron-doped La0.85Hf0.15MnO3 (LHMO) film with the thickness of 90 nm was epitaxially grown on LaAlO3 (001) single crystal substrate. The structural, magnetic and electrical transport properties of the film have been studied comprehensively. The X-ray diffraction patterns confirm that LHMO film is of single phase, good quality and c axis orientation. The film undergoes a ferromagnetic-like ordering to paramagnetic states at T C =280 K. Moreover, a spin glass behavior observed in the film may be attributed to the strain effects. Using the percolation theory, we have analyzed the resistivity data ρ (T) of the film and given an excellent fit in the whole temperature range. Particularly, large temperature coefficient of resistance of 11.27% K- 1 has been discovered near sub-room-temperature, indicating that LHMO film could be useful for bolometric applications.

  7. A 50 MHz-1 GHz high linearity CATV amplifier with a 0.15 μm InGaAs PHEMT process

    NASA Astrophysics Data System (ADS)

    Jian, Xu; Zhigong, Wang; Ying, Zhang; Jing, Huang

    2011-07-01

    A 50 MHz-1 GHz low noise and high linearity amplifier monolithic-microwave integrated-circuit (MMIC) for cable TV is presented. A shunt AC voltage negative feedback combined with source current negative feedback is adopted to extend the bandwidth and linearity. A novel DC bias feedback is introduced to stabilize the operation point, which improved the linearity further. The circuit was fabricated with a 0.15 μm InGaAs PHEMT (pseudomorphic high electron mobility transistor) process. The test was carried out in 75 Ω systems from 50 MHz to 1 GHz. The measurement results showed that it gave a small signal gain of 16.5 dB with little gain ripples of less than ± 1 dB. An excellent noise figure of 1.7-2.9 dB is obtained in the designed band. The IIP3 is 16 dBm, which shows very good linearity. The CSO and CTB are high up to 68 dBc and 77 dBc, respectively. The chip area is 0.56 mm2 and the power dissipation is 110 mA with a 5 V supply. It is ideally suited to cable TV systems.

  8. Experimental investigation of a 0.15 scale model of a conformal variable-ramp inlet for the F-16 airplane

    NASA Technical Reports Server (NTRS)

    Hawkins, J. E.

    1980-01-01

    A 0.15 scale model of a proposed conformal variable-ramp inlet for the Multirole Fighter was tested from Mach 0.8 to 2.2 at a wide range of angles of attack and sideslip. Inlet ramp angle was varied to optimize ramp angle as a function of engine airflow, Mach number, angle of attack, and angle of sideslip. Several inlet configuration options were investigated to study their effects on inlet operation and to establish the final flight configuration. These variations were cowl sidewall cutback, cowl lip bluntness, boundary layer bleed, and first-ramp leading edge shape. Diagnostic and engine face instrumentation were used to evaluate inlet operation at various inlet stations and at the inlet/engine interface. Pressure recovery and stability of the inlet were satisfactory for the proposed application. On the basis of an engine stability audit of the worst-case instantaneous distortion patterns, no inlet/engine compatibility problems are expected for normal operations.

  9. Solvent-Based Synthesis of Nano-Bi0.85Sb0.15 for Low-Temperature Thermoelectric Applications

    NASA Astrophysics Data System (ADS)

    Kaspar, K.; Fritsch, K.; Habicht, K.; Willenberg, B.; Hillebrecht, H.

    2017-01-01

    In this study we show a preparation method for nanostructured Bi0.85Sb0.15 powders via a chemical reduction route in a polyol medium, yielding material with particle sizes of 20-150 nm in scalable amounts. The powders were consolidated by spark plasma sintering (SPS) in order to maintain the nanostructure. To investigate influence of the sinter process, the powders were characterized by x-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), and scanning electron microscopy (SEM) measurements before and after SPS. Transport properties, Seebeck effect, and thermal conductivity were determined in the low temperature range below 300 K. The samples showed excellent thermal conductivity of 2.3-2.6 W/m × K at 300 K and Seebeck coefficients from -97 μV/K to -107 μV/K at 300 K with a maximum of -141 μV/K at 110 K, thus leading to ZT values of up to 0.31 at room temperature. The results show that Bi-Sb-alloys are promising materials for low-temperature applications. Our wet chemical approach gives access to scalable amounts of nano-material with increased homogeneity and good thermoelectric properties after SPS.

  10. On the transport properties of the solid solution Sr 1- xLa xPbO 3- δ (0 ⩽ x ⩽ 0.15)

    NASA Astrophysics Data System (ADS)

    Hadjarab, B.; Bassaid, S.; Bouguelia, A.; Trari, M.

    2006-06-01

    Mixed valencies system Sr 1- xLa xPbO 3- δ (0 ⩽ x ⩽ 0.15) has been prepared by solid state reaction at 900 °C. All solutions crystallize in a distorted perovskite structure and were carefully examined by chemical analysis and X-ray diffraction. The La 3+-substitution was checked via the linear dependence of lattice constants on x-value, i.e. Vegard’s law. The expansion of the unit cell volume involves a simultaneous increase of all the parameters. The magnetic susceptibilities are slightly temperature dependent, dominated by core diamagnetism giving an effective mass m∗ of ∼9. The transport properties were investigated from 300 K down to liquid helium. The resistivity was found to change markedly with the rate substitution x and the oxides behave as degenerate semi-conductors with very weak activation energies. The insulating-metal transition can thus be considered of Anderson type attributed to random potential as lanthanum is substituted for strontium. The electric balance comes also from departure of oxygen and would imply a simultaneous reduction Pb 4+/2+. The electron mobility is thermally activated with a temperature independent carrier concentration.

  11. Anisotropy of the upper critical fields and the paramagnetic Meissner effect in La1.85Sr0.15CuO4 single crystals

    NASA Astrophysics Data System (ADS)

    Felner, I.; Tsindlekht, M. I.; Drachuck, G.; Keren, A.

    2013-02-01

    Optimally doped La1.85Sr0.15CuO4 single crystals have been investigated by dc and ac magnetic measurements. These crystals have rectangular needle-like shapes with the long needle axis parallel to the crystallographic c axis (c-crystal) or parallel to the basal planes (a-crystal). In both crystals, the temperature dependence of the upper critical fields (HC2) and the surface critical field (HC3) were measured. The H-T phase diagram is presented. Close to TC = 35 K, for the c-crystal, {\\boldsymbol{\\gamma}}^{c}={H}_{{C3}}^{c}/{H}_{{C2}}^{c}=1.8 0(2), whereas for the a-crystal the {\\boldsymbol{\\gamma}}^{a}={H}_{{C3}}^{a}/{H}_{{C2}}^{a}=4.0(2) obtained is much higher than 1.69, predicted by the ideal mathematical model. At low applied dc fields, positive field-cooled branches known as the ‘paramagnetic Meissner effect’ (PME) are observed; their magnitude is inversely proportional to H. The anisotropic PME is observed in both a- and c-crystals, only when the applied field is along the basal planes. It is speculated that the high γa and the PME are connected to each other.

  12. Re-construction layer effect of LiNi0.8Co0.15Mn0.05O2 with solvent evaporation process

    PubMed Central

    Park, Kwangjin; Park, Jun-Ho; Hong, Suk-Gi; Choi, Byungjin; Heo, Sung; Seo, Seung-Woo; Min, Kyoungmin; Park, Jin-Hwan

    2017-01-01

    The solvent evaporation method on the structural changes and surface chemistry of the cathode and the effect of electrochemical performance of Li1.0Ni0.8Co0.15Mn0.05O2 (NCM) has been investigated. After dissolving of Li residuals using minimum content of solvent in order to minimize the damage of pristine material and the evaporation time, the solvent was evaporated without filtering and remaining powder was re-heated at 700 °C in oxygen environment. Two kinds of solvent, de-ionized water and diluted nitric acid, were used as a solvent. The almost 40% of Li residuals were removed using solvent evaporation method. The NCM sample after solvent evaporation process exhibited an increase in the initial capacity (214.3 mAh/g) compared to the pristine sample (207.4 mAh/g) at 0.1C because of enhancement of electric conductivity caused by decline of Li residuals. The capacity retention of NCM sample after solvent evaporation process (96.0% at the 50th cycle) was also improved compared to that of the pristine NCM sample (90.6% at the 50th cycle). The uniform Li residual layer after solvent treated and heat treatment acted like a coating layer, leading to enhance the cycle performance. The NCM sample using diluted nitric acid showed better performance than that using de-ionized water. PMID:28317913

  13. Thermoelectric performance of n-type (PbTe)0.75(PbS)0.15(PbSe)0.1 composites.

    PubMed

    Yamini, Sima Aminorroaya; Wang, Heng; Ginting, Dianta; Mitchell, David R G; Dou, Shi Xue; Snyder, G Jeffrey

    2014-07-23

    Lead chalcogenides (PbQ, Q = Te, Se, S) have proved to possess high thermoelectric efficiency for both n-type and p-type compounds. Recent success in tuning of electronic band structure, including manipulating the band gap, multiple bands, or introducing resonant states, has led to a significant improvement in the thermoelectric performance of p-type lead chalcogenides compared to the n-type ones. Here, the n-type quaternary composites of (PbTe)0.75(PbS)0.15(PbSe)0.1 are studied to evaluate the effects of nanostructuring on lattice thermal conductivity, carrier mobility, and effective mass variation. The results are compared with the similar ternary systems of (PbTe)(1-x)(PbSe)x, (PbSe)(1-x)(PbS)x, and (PbS)(1-x)(PbTe)x. The reduction in the lattice thermal conductivity owing to phonon scattering at the defects and interfaces was found to be compensated by reduced carrier mobility. This results in a maximum figure of merit, zT, of ∼1.1 at 800 K similar to the performance of the single phase alloys of PbTe, PbSe, and (PbTe)(1-x)(PbSe)x.

  14. Measurement of the Proton Spin Function g1(x,Q2) for Q2 from 0.15 to 1.6 GeV with CLAS

    SciTech Connect

    Renee Fatemi; Alexander Skabelin; Volker Burkert; Donald Crabb; Raffaella De Vita; Sebastian Kuhn; Ralph Minehart

    2003-11-01

    Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH{sub 3} target in the CLAS detector. The polarized structure function g{sub 1}(x,Q{sup 2}) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q{sup 2} = 0.15-1.64 GeV{sup 2}. The contributions to the first moment {Gamma}{sub 1}(Q{sup 2}) = g{sub 1}(x,Q{sup 2})dx were determined up to Q{sup 2}=1.2 GeV{sup 2}. Using a parameterization for g{sub 1} in the unmeasured low x regions, the complete first moment was estimated over this Q{sup 2} region. A rapid change in {Gamma}{sub 1} is observed for Q{sup 2} < 1 GeV{sup 2}, with a sign change near Q{sup 2} = 0.3 GeV{sup 2}, indicating dominant contributions from the resonance region. At Q{sup 2}=1.2 GeV{sup 2} our data are below the pQCD evolved scaling value.

  15. Fatigue of LiNi0.8Co0.15Al0.05O2 in commercial Li ion batteries

    NASA Astrophysics Data System (ADS)

    Kleiner, Karin; Dixon, Ditty; Jakes, Peter; Melke, Julia; Yavuz, Murat; Roth, Christina; Nikolowski, Kristian; Liebau, Verena; Ehrenberg, Helmut

    2015-01-01

    The degradation of LiNi0.8Co0.15Al0.05O2 (LNCAO), a cathode material in lithium-ion-batteries, was studied using in situ powder diffraction and in situ Ni K edge X-ray absorption spectroscopy (XAS). The fatigued material was taken from a 7 Ah battery which was cycled for 34 weeks under defined durability conditions. Meanwhile, a cell was stored, as reference, under controlled conditions without electrochemical treatment. The fatigued LNCAO used in this study showed a capacity loss of 26% ± 9% compared to the non-cycled material. During charge and discharge the local and the overall structure of LNCAO was investigated by X-ray near edge structure (XANES) analysis, the extended X-ray absorption fine structure (EXAFS) analysis and by using Rietveld refinement of in situ powder diffraction patterns. Both powder diffraction and XAS revealed additional, rhombohedral phases which do not change with electrochemical cycling. Moreover, a phase with the lattice parameters of fully lithiated LNCAO was still present in the fatigued material at high potentials, while it was absent in the non-fatigued reference material. The coexistence of these phases is described by domains within the LNCAO particles, in correlation with the observed fatigue.

  16. A large Hα survey of star formation in relaxed and merging galaxy cluster environments at z ∼ 0.15-0.3

    NASA Astrophysics Data System (ADS)

    Stroe, Andra; Sobral, David; Paulino-Afonso, Ana; Alegre, Lara; Calhau, João; Santos, Sergio; van Weeren, Reinout

    2017-03-01

    We present the first results from the largest Hα survey of star formation and active galactic nucleus activity in galaxy clusters. Using nine different narrow-band filters, we select >3000 Hα emitters within 19 clusters and their larger scale environment over a total volume of 1.3 × 105 Mpc3. The sample includes both relaxed and merging clusters, covering the 0.15-0.31 redshift range and spanning from 5 × 1014 to 30 × 1014 M⊙. We find that the Hα luminosity function for merging clusters has a higher characteristic density ϕ* compared to relaxed clusters. ϕ* drops from cluster core to cluster outskirts for both merging and relaxed clusters, with the merging cluster values ∼0.3 dex higher at each projected radius. The characteristic luminosity L* drops over the 0.5-2.0 Mpc distance from the cluster centre for merging clusters and increases for relaxed objects. Among disturbed objects, clusters hosting large-scale shock waves (traced by radio relics) are overdense in Hα emitters compared to those with turbulence in their intracluster medium (traced by radio haloes). We speculate that the increase in star formation activity in disturbed, young, massive galaxy clusters can be triggered by interactions between gas-rich galaxies, shocks and/or the intracluster medium, as well as accretion of filaments and galaxy groups. Our results indicate that disturbed clusters represent vastly different environments for galaxy evolution compared to relaxed clusters or average field environments.

  17. Re-construction layer effect of LiNi0.8Co0.15Mn0.05O2 with solvent evaporation process

    NASA Astrophysics Data System (ADS)

    Park, Kwangjin; Park, Jun-Ho; Hong, Suk-Gi; Choi, Byungjin; Heo, Sung; Seo, Seung-Woo; Min, Kyoungmin; Park, Jin-Hwan

    2017-03-01

    The solvent evaporation method on the structural changes and surface chemistry of the cathode and the effect of electrochemical performance of Li1.0Ni0.8Co0.15Mn0.05O2 (NCM) has been investigated. After dissolving of Li residuals using minimum content of solvent in order to minimize the damage of pristine material and the evaporation time, the solvent was evaporated without filtering and remaining powder was re-heated at 700 °C in oxygen environment. Two kinds of solvent, de-ionized water and diluted nitric acid, were used as a solvent. The almost 40% of Li residuals were removed using solvent evaporation method. The NCM sample after solvent evaporation process exhibited an increase in the initial capacity (214.3 mAh/g) compared to the pristine sample (207.4 mAh/g) at 0.1C because of enhancement of electric conductivity caused by decline of Li residuals. The capacity retention of NCM sample after solvent evaporation process (96.0% at the 50th cycle) was also improved compared to that of the pristine NCM sample (90.6% at the 50th cycle). The uniform Li residual layer after solvent treated and heat treatment acted like a coating layer, leading to enhance the cycle performance. The NCM sample using diluted nitric acid showed better performance than that using de-ionized water.

  18. Status of the JPL Horizons Ephemeris System

    NASA Astrophysics Data System (ADS)

    Giorgini, Jon D.

    2015-08-01

    Since 1996, the NASA/Jet Propulsion Laboratory on-line Horizons system has provided open access to the latest JPL orbit solutions through customizable ephemeris generation and searches. Currently, high-precision ephemerides for more than 683,000 objects are available: all known solar system bodies, several dozen spacecraft, system barycenters, and some libration points.Since inception, Horizons has produced 150 million ephemeris products in response to 70.4 million connections by 800,000 unique IP addresses. Recent usage is typically 6000 unique users requesting 4,000,000 ephemeris products per month.Horizons is freely accessible without an account and may be used and automated through any of three interfaces: interactive telnet connection, web-browser form, or by sending e-mail command-files.Asteroid and comet ephemerides are numerically integrated on request using JPL's DASTCOM5 database of initial conditions which is kept current by a separate process; as new measurements and discoveries are reported by the Minor Planet Center, they are automatically processed into new JPL orbit solutions. Radar targets and other objects of high interest have their orbit solutions manually examined and updated into the database.For asteroids and comets, SPK files may be dynamically created using Horizons. This is effectively a recording of the integrator output. The binary files may then be efficiently interpolated by user software to exactly reproduce the trajectory without having to duplicate the numerically integrated n-body dynamical model or PPN equations of motion.Other Horizons output is numerical and in the form of plain-text observer, vector, osculating element, and close-approach tables. More than one hundred quantities can be requested in various time-scales and coordinate systems. For asteroids and comets, statistical uncertainties can be mapped to output times to assess position and motion uncertainties.Horizons is consistent with the DE431 solar system solution

  19. Measurements of Output Factors For Small Photon Fields Up to 10 cm x 10 cm

    NASA Astrophysics Data System (ADS)

    Bacala, Angelina

    Field output factors (OF) for photon beams from a 6 MV medical accelerator were measured using five different detectors in a scanning water phantom. The measurements were taken for square field sizes of integral widths ranging from 1 cm to 10 cm for two reference source-to-surface distances (SSD) and depths in water. For the diode detectors, square field widths as small as 2.5 mm were also studied. The photon beams were collimated by using either the jaws or the multileaf collimators. Measured OFs are found to depend upon the field size, SSD, depth and also upon the type of beam collimation, size and type of detector used. For field sizes larger than 3 cm x 3 cm, the OF measurements agree to within 1% or less. The largest variation in OF occurs for jawsshaped field of size 1 cm x 1cm, where a difference of more than 18% is observed.

  20. Controls and occurance of interflow over a restrictive argillic horizon in a low gradient hillslope.

    SciTech Connect

    Greco, James, L. III

    2008-02-01

    Interflow (throughflow or lateral flow), is shallow lateral subsurface flow that moves over a horizon that restricts percolation. Interflow is important for a number of reasons. First, rapid saturated interflow through macropores can travel to streams and alluvial aquifers with high celerity. Also, experimental studies have shown that interflow can be an important source of baseflow and stormflow. Because interflow travels through a biologically active region of soil with roots and relatively high OM content, the final outcome is the potential contamination of surface water bodies from subsurface water. Many of the soils in the southeastern US are characterized by an argillic, or clay horizon, that largely parallels the soil surface at depths ranging from a few centimeters to hundreds of centimeters. The degree to which these argillic horizons alter subsurface movement of infiltrated water is not well known. This research investigates how often and under what conditions a relatively deep (20-150+cm) argillic horizon on low slope (2-12%) hillsides causes interflow to occur.

  1. Interpreting Sky-Averaged 21-cm Measurements

    NASA Astrophysics Data System (ADS)

    Mirocha, Jordan

    2015-01-01

    Within the first ~billion years after the Big Bang, the intergalactic medium (IGM) underwent a remarkable transformation, from a uniform sea of cold neutral hydrogen gas to a fully ionized, metal-enriched plasma. Three milestones during this epoch of reionization -- the emergence of the first stars, black holes (BHs), and full-fledged galaxies -- are expected to manifest themselves as extrema in sky-averaged ("global") measurements of the redshifted 21-cm background. However, interpreting these measurements will be complicated by the presence of strong foregrounds and non-trivialities in the radiative transfer (RT) modeling required to make robust predictions.I have developed numerical models that efficiently solve the frequency-dependent radiative transfer equation, which has led to two advances in studies of the global 21-cm signal. First, frequency-dependent solutions facilitate studies of how the global 21-cm signal may be used to constrain the detailed spectral properties of the first stars, BHs, and galaxies, rather than just the timing of their formation. And second, the speed of these calculations allows one to search vast expanses of a currently unconstrained parameter space, while simultaneously characterizing the degeneracies between parameters of interest. I find principally that (1) physical properties of the IGM, such as its temperature and ionization state, can be constrained robustly from observations of the global 21-cm signal without invoking models for the astrophysical sources themselves, (2) translating IGM properties to galaxy properties is challenging, in large part due to frequency-dependent effects. For instance, evolution in the characteristic spectrum of accreting BHs can modify the 21-cm absorption signal at levels accessible to first generation instruments, but could easily be confused with evolution in the X-ray luminosity star-formation rate relation. Finally, (3) the independent constraints most likely to aide in the interpretation

  2. Data Simulation for 21 cm Cosmology Experiments

    NASA Astrophysics Data System (ADS)

    Pober, Jonathan

    2017-01-01

    21 cm cosmologists seek a measurement of the hyperfine line of neutral hydrogen from very high redshifts. While this signal has the potential to provide an unprecedented view into the early universe, it is also buried under exceedingly bright foreground emission. Over the last several years, 21 cm cosmology research has led to an improved understanding of how low frequency radio interferometers will affect the separation of cosmological signal from foregrounds. This talk will describe new efforts to incorporate this understanding into simulations of the most realistic data sets for the Precision Array for Probing the Epoch of Reionization (PAPER), the Murchison Widefield Array (MWA), and the Hydrogen Epoch of Reionization Array (HERA). These high fidelity simulations are essential for robust algorithm design and validation of early results from these experiments.

  3. Extended Performance 8-cm Mercury Ion Thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.

    1981-01-01

    A slightly modified 8-cm Hg ion thruster demonstrated significant increase in performance. Thrust was increased by almost a factor of five over that of the baseline thruster. Thruster operation with various three grid ion optics configurations; thruster performance as a function of accelerator grid open area, cathode baffle, and cathode orifice size; and a life test of 614 hours at a beam current of 250 mA (17.5 mN thrust) are discussed. Highest thruster efficiency was obtained with the smallest open area accelerator grid. The benefits in efficiency from the low neutral loss grids were mitigated, however, by the limitation such grids place on attainable ion beam current densities. The thruster components suffered negligible weight losses during a life test, which indicated that operation of the 8-cm thruster at extended levels of thrust and power is possible with no significant loss of lifetime.

  4. 15 cm multipole gas ion thruster

    NASA Technical Reports Server (NTRS)

    Isaacson, G. C.; Kaufman, H. R.

    1976-01-01

    A 15-cm multipole thruster was operated on argon and xenon. The multipole approach used has been shown capable of low discharge losses and flat ion beam profiles with a minimum of redesign. This approach employs low magnetic field strengths and flat or cylindrical sheet-metal parts, hence is suited to rapid optimization and scaling. Only refractory metal cathodes were used in this investigation.

  5. Fiber-optical analog of the event horizon.

    PubMed

    Philbin, Thomas G; Kuklewicz, Chris; Robertson, Scott; Hill, Stephen; König, Friedrich; Leonhardt, Ulf

    2008-03-07

    The physics at the event horizon resembles the behavior of waves in moving media. Horizons are formed where the local speed of the medium exceeds the wave velocity. We used ultrashort pulses in microstructured optical fibers to demonstrate the formation of an artificial event horizon in optics. We observed a classical optical effect: the blue-shifting of light at a white-hole horizon. We also showed by theoretical calculations that such a system is capable of probing the quantum effects of horizons, in particular Hawking radiation.

  6. Rogue events in the group velocity horizon

    PubMed Central

    Demircan, Ayhan; Amiranashvili, Shalva; Brée, Carsten; Mahnke, Christoph; Mitschke, Fedor; Steinmeyer, Günter

    2012-01-01

    The concept of rogue waves arises from a mysterious and potentially calamitous phenomenon of oceanic surfaces. There is mounting evidence that they are actually commonplace in a variety of different physical settings. A set of defining criteria has been advanced; this set is of great generality and therefore applicable to a wide class of systems. The question arises naturally whether there are generic mechanisms responsible for extreme events in different systems. Here we argue that under suitable circumstances nonlinear interaction between weak and strong waves results in intermittent giant waves with all the signatures of rogue waves. To obtain these circumstances only a few basic conditions must be met. Then reflection of waves at the so-called group-velocity horizon occurs. The connection between rogue waves and event horizons, seemingly unrelated physical phenomena, is identified as a feature common in many different physical systems. PMID:23152941

  7. Rogue events in the group velocity horizon.

    PubMed

    Demircan, Ayhan; Amiranashvili, Shalva; Brée, Carsten; Mahnke, Christoph; Mitschke, Fedor; Steinmeyer, Günter

    2012-01-01

    The concept of rogue waves arises from a mysterious and potentially calamitous phenomenon of oceanic surfaces. There is mounting evidence that they are actually commonplace in a variety of different physical settings. A set of defining criteria has been advanced; this set is of great generality and therefore applicable to a wide class of systems. The question arises naturally whether there are generic mechanisms responsible for extreme events in different systems. Here we argue that under suitable circumstances nonlinear interaction between weak and strong waves results in intermittent giant waves with all the signatures of rogue waves. To obtain these circumstances only a few basic conditions must be met. Then reflection of waves at the so-called group-velocity horizon occurs. The connection between rogue waves and event horizons, seemingly unrelated physical phenomena, is identified as a feature common in many different physical systems.

  8. Quantum correlations across the black hole horizon

    SciTech Connect

    Schuetzhold, Ralf; Unruh, William G.

    2010-06-15

    Inspired by the condensed-matter analogues of black holes, we study the quantum correlations across the event horizon reflecting the entanglement between the outgoing particles of the Hawking radiation and their in-falling partners. For a perfectly covariant theory, the total correlation is conserved in time and piles up arbitrary close to the horizon in the past, where it merges into the singularity of the vacuum two-point function at the light cone. After modifying the dispersion relation (i.e., breaking Lorentz invariance) for large k, on the other hand, the light cone is smeared out and the entanglement is not conserved but actually created in a given rate per unit time.

  9. Horizon Missions Technology Study. [for space exploration

    NASA Technical Reports Server (NTRS)

    Anderson, John L.

    1992-01-01

    The purpose of the HMT Study was to develop and demonstrate a systematic methodology for identifying and evaluating innovative technology concepts offering revolutionary, breadkthrough-type capabilities for advanced space missions and for assessing their potential mission impact. The methodology is based on identifying the new functional, operational and technology capabilities needed by hypothetical 'Horizon' space missions that have performance requirements that cannot be met, even by extrapolating known space technologies. Nineteen Horizon Missions were selected to represent a collective vision of advanced space missions of the mid-21st century. The missions typically would occur beyond the lifetime of current or planned space assets. The HM methodology and supporting data base may be used for advanced technology planning, advanced mission planning and multidisciplinary studies and analyses.

  10. Dynamical AdS strings across horizons

    SciTech Connect

    Ishii, Takaaki; Murata, Keiju

    2016-03-01

    We examine the nonlinear classical dynamics of a fundamental string in anti-deSitter spacetime. The string is dual to the flux tube between an external quark-antiquark pair in $N = 4$ super Yang-Mills theory. We perturb the string by shaking the endpoints and compute its time evolution numerically. We find that with sufficiently strong perturbations the string continues extending and plunges into the Poincare´ horizon. In the evolution, effective horizons are also dynamically created on the string worldsheet. The quark and antiquark are thus causally disconnected, and the string transitions to two straight strings. The forces acting on the endpoints vanish with a power law whose slope depends on the perturbations. Lastly, the condition for this transition to occur is that energy injection exceeds the static energy between the quark-antiquark pair.

  11. Dynamical AdS strings across horizons

    DOE PAGES

    Ishii, Takaaki; Murata, Keiju

    2016-03-01

    We examine the nonlinear classical dynamics of a fundamental string in anti-deSitter spacetime. The string is dual to the flux tube between an external quark-antiquark pair in $N = 4$ super Yang-Mills theory. We perturb the string by shaking the endpoints and compute its time evolution numerically. We find that with sufficiently strong perturbations the string continues extending and plunges into the Poincare´ horizon. In the evolution, effective horizons are also dynamically created on the string worldsheet. The quark and antiquark are thus causally disconnected, and the string transitions to two straight strings. The forces acting on the endpoints vanishmore » with a power law whose slope depends on the perturbations. Lastly, the condition for this transition to occur is that energy injection exceeds the static energy between the quark-antiquark pair.« less

  12. Polarimetry with the Event Horizon Telescope

    NASA Astrophysics Data System (ADS)

    Johnson, Michael; Doeleman, Sheperd; Fish, Vincent L.; Plambeck, Richard L.; Marrone, Daniel P.; Kosowsky, Michael; Wardle, John F. C.; Lu, Rusen

    2014-06-01

    The Event Horizon Telescope (EHT) is an effort to develop millimeter and submillimeter VLBI to image nearby black holes at resolutions comparable to their event horizons. Past work with the EHT has measured compact emission on such scales for Sgr A* and M87, and has also measured sub-parsec structure in more distant quasars. Polarimetry with the EHT enables a powerful extension of this work, mapping magnetic field structures via the highly polarized synchrotron emission. Polarization is also an excellent probe of rapid variability, especially for Sgr A*, and can convey rich astrometric information even with incomplete imaging. We report on results from our 2013 campaign, which demonstrate a sharp increase in the linear polarization fraction and variability with increasing baseline, and we demonstrate that current EHT data can potentially achieve microarcsecond relative astrometry of flaring regions on timescales of minutes.

  13. Mapmaking for precision 21 cm cosmology

    NASA Astrophysics Data System (ADS)

    Dillon, Joshua S.; Tegmark, Max; Liu, Adrian; Ewall-Wice, Aaron; Hewitt, Jacqueline N.; Morales, Miguel F.; Neben, Abraham R.; Parsons, Aaron R.; Zheng, Haoxuan

    2015-01-01

    In order to study the "Cosmic Dawn" and the Epoch of Reionization with 21 cm tomography, we need to statistically separate the cosmological signal from foregrounds known to be orders of magnitude brighter. Over the last few years, we have learned much about the role our telescopes play in creating a putatively foreground-free region called the "EoR window." In this work, we examine how an interferometer's effects can be taken into account in a way that allows for the rigorous estimation of 21 cm power spectra from interferometric maps while mitigating foreground contamination and thus increasing sensitivity. This requires a precise understanding of the statistical relationship between the maps we make and the underlying true sky. While some of these calculations would be computationally infeasible if performed exactly, we explore several well-controlled approximations that make mapmaking and the calculation of map statistics much faster, especially for compact and highly redundant interferometers designed specifically for 21 cm cosmology. We demonstrate the utility of these methods and the parametrized trade-offs between accuracy and speed using one such telescope, the upcoming Hydrogen Epoch of Reionization Array, as a case study.

  14. Polyhedral Serpentine Grains in CM Chondrites

    NASA Technical Reports Server (NTRS)

    Zega, Thomas J.; Garvie, Laurence A. J.; Dodony, Istvan; Stroud, Rhonda M.; Buseck, Peter R.

    2005-01-01

    CM chondrites are primitive rocks that experienced aqueous alteration in the early solar system. Their matrices and fine-grained rims (FGRs) sustained the effects of alteration, and the minerals within them hold clues to the aqueous reactions. Sheet silicates are an important product of alteration, and those of the serpentine group are abundant in the CM2 chondrites. Here we expand on our previous efforts to characterize the structure and chemistry of serpentines in CM chondrites and report results on a polyhedral form that is structurally similar to polygonal serpentine. Polygonal serpentine consists of tetrahedral (T) sheets joined to M(2+)-centered octahedral (O) sheets (where (M2+) is primarily Mg(2+) and Fe(2+)), which give rise to a 1:1 (TO) layered structure with a 0.7-nm layer periodicity. The structure is similar to chrysotile in that it consists of concentric lizardite layers wrapped around the fiber axis. However, unlike the rolled-up chrysotile, the tetrahedral sheets of the lizardite layers are periodically inverted and kinked, producing sectors. The relative angles between sectors result in 15- and 30-sided polygons in terrestrial samples.

  15. Radio Occultation Measurements of Pluto's Atmosphere with New Horizons

    NASA Astrophysics Data System (ADS)

    Hinson, David P.; Linscott, Ivan; Young, Leslie; Stern, S. Alan; Bird, Mike; Ennico, Kimberly; Gladstone, Randy; Olkin, Catherine B.; Pätzold, Martin; Strobel, Darrell F.; Summers, Michael; Tyler, G. Leonard; Weaver, Harold A.; Woods, Will; New Horizons Science Team

    2016-10-01

    The reconnaissance of the Pluto System by New Horizons in July 2015 included a radio occultation at Pluto. The observation was performed with signals transmitted simultaneously by four antennas of the NASA Deep Space Network, two at the Goldstone complex in California and two at the Canberra complex in Australia. Each antenna radiated 20 kW without modulation at a wavelength of 4.17 cm. New Horizons received the four signals with its 2.1-m high-gain antenna, where the signals were split into pairs and processed independently by two identical REX radio science instruments. Each REX relied on a different ultra-stable oscillator as its frequency reference. The signals were digitized and filtered, and the data samples were stored on the spacecraft for later transmission to Earth. Six months elapsed before all data had arrived on the ground, and the results reported here are the first to utilize the complete set of observations. Pluto's tenuous atmosphere is a significant challenge for radio occultation sounding, which led us to develop a specialized method of analysis. We began by calibrating each signal to remove effects not associated with Pluto's atmosphere, including the diffraction pattern from Pluto's surface. We reduced the noise and increased our sensitivity to the atmosphere by averaging the results from the four signals, while using other combinations of the signals to characterize the noise. We then retrieved profiles of number density, pressure, and temperature from the averaged phase profiles at both occultation entry and exit. Finally, we used a combination of analytical methods and Monte Carlo simulations to determine the accuracy of the measurements. The REX profiles provide the first direct measure of the surface pressure and temperature structure in Pluto's lower atmosphere. There are significant differences between the structure at entry (193.5°E, 17.0°S, sunset) and exit (15.7°E, 15.1°N, sunrise), which arise from spatial variations in surface

  16. Quantum amplification effect in a horizon fluctuation

    SciTech Connect

    Ansari, Mohammad H.

    2010-05-15

    The appearance of a few unevenly spaced bright flashes of light on top of Hawking radiation is the sign of the amplification effect in black hole horizon fluctuations. Previous studies on this problem suffer from the lack of considering all emitted photons in the theoretical spectroscopy of these fluctuations. In this paper, we include all of the physical transition weights and present a consistent intensity formula. This modifies a black hole radiation pattern.

  17. Gribov horizon beyond the Landau gauge

    NASA Astrophysics Data System (ADS)

    Lavrov, Peter M.; Lechtenfeld, Olaf

    2013-10-01

    Gribov and Zwanziger proposed a modification of Yang-Mills theory in order to cure the Gribov copy problem. We employ field-dependent BRST transformations to generalize the Gribov-Zwanziger model from the Landau gauge to general Rξ gauges. The Gribov horizon functional is presented in explicit form, in both the non-local and local variants. Finally, we show how to reach any given gauge from the Landau one.

  18. New Horizons Pluto Flyby Guest Operations

    NASA Astrophysics Data System (ADS)

    Simon, M.; Turney, D.; Fisher, S.; Carr, S. S.

    2015-12-01

    On July 14, 2015, after 9.5 years of cruise, NASA's New Horizons spacecraft flew past the Pluto system to gather first images humankind had ever seen on Pluto and its five moons. While much has been discovered about the Pluto system since New Horizons launch in 2006, the system has never been imaged at high resolution and anticipation of the "First Light" of the Pluto system had been anticipated by planetary enthusiasts for decades. The Johns Hopkins Applied Physics Laboratory (APL), which built and operates New Horizons, was the focal point for gathering three distinct groups: science and engineering team members; media and public affairs representatives; and invited public, including VIP's. Guest operations activities were focused on providing information primarily to the invited public and VIP's. High level objectives for the Guest Operations team was set to entertain and inform the general public, offer media reaction shots, and to deconflict activities for the guests from media activities wherever possible. Over 2000 people arrived at APL in the days surrounding closest approach for guest, science or media operations tracks. Reaction and coverage of the Guest Operations events was universally positive and global in impact: iconic pictures of the auditorium waving flags during the moment of closest approach were published in media outlets on every continent. Media relations activities ensured coverage in all key media publications targeted for release, such as the New York Times, Science, Le Monde, and Nature. Social and traditional media coverage of the events spanned the globe. Guest operations activities are designed to ensure that a guest has a memorable experience and leaves with a lifelong memory of the mission and their partnership in the activity. Results, lessons learned, and other data from the New Horizons guest operations activity will be presented and analyzed.

  19. Suppression of superconductivity of Dy0.6Y0.4Rh3.85Ru0.15B4 in inclined magnetic fields

    NASA Astrophysics Data System (ADS)

    Terekhov, A. V.; Zolochevskii, I. V.; Khristenko, E. V.; Ishchenko, L. A.; Bezuglyi, E. V.; Zaleski, A.; Khlybov, E. P.; Lachenkov, S. A.

    2015-04-01

    The electrical resistance of polycrystalline Dy0.6Y0.4Rh3.85Ru0.15B4 is measured for the first time near the superconducting transition temperature (Tc1/2 ≈ 6.66 K) in various inclined magnetic fields (φ = 0, 45, and 90°) and plots are made of R(T) and the upper critical field in dimensionless units h*(t). These dependences exhibit strong anisotropy with respect to the transport current through a sample when the orientation of the magnetic field is changed from φ = 0 to 90°. This appears to be related to texturing of the polycrystals. An analysis of the R(T) and h*(t) curves shows that the magnetic field suppresses the superconducting state more strongly at φ = 45° than at the other angles of inclination. The h*(t) dependences are analyzed in terms of the Werthamer-Helfand-Hohenberg theory and the Maki parameter α and the spin-orbital scattering parameter λSO are estimated. It is shown that for φ = 0 and 90°, α = 0 and λSO = 0 and only the orbital contribution is observed, while for φ = 45°, α = 4.2 and λSO = 0 and there is a substantial increase in the relative contribution of spin paramagnetic effects. It is suggested that the character of the R(T) and h*(t) curves in inclined magnetic fields is influenced by the effect on the superconducting state of the internal magnetism of the dysprosium atoms, which depends on the inclination of the field.

  20. Mn-doping induced ferromagnetism and enhanced superconductivity in Bi4 -xMnxO4S3 (0.075 ≤x ≤0.15 )

    NASA Astrophysics Data System (ADS)

    Feng, Zhenjie; Yin, Xunqing; Cao, Yiming; Peng, Xianglian; Gao, Tian; Yu, Chuan; Chen, Jingzhe; Kang, Baojuan; Lu, Bo; Guo, Juan; Li, Qing; Tseng, Wei-Shiuan; Ma, Zhongquan; Jing, Chao; Cao, Shixun; Zhang, Jincang; Yeh, N.-C.

    2016-08-01

    We demonstrate that Mn doping in the layered sulfides Bi4O4S3 leads to stable Bi4-xMnxO4S3 compounds that exhibit both long-range ferromagnetism and enhanced superconductivity for 0.075 ≤x ≤0.15 , with a possible record superconducting transition temperature (Tc) ˜15 K among all BiS2-based superconductors. We conjecture that the coexistence of superconductivity and ferromagnetism may be attributed to Mn doping in the spacer Bi2O2 layers away from the superconducting BiS2 layers, whereas the enhancement of Tc may be due to excess electron transfer to BiS2 from the Mn4 +/Mn3 + substitutions in Bi2O2 . This notion is empirically corroborated by the increased electron-carrier densities upon Mn doping, and by further studies of the Bi4-xAxO4S3 compounds (A = Co, Ni; x =0.1 , 0.125), where the Tc values remain comparable to that of the undoped Bi4O4S3 system (˜4.5 K) due to lack of 4+ valences in either Co or Ni ions for excess electron transfer to the BiS2 layers. These findings therefore shed new light on feasible pathways to enhance the Tc values of BiS2-based superconductors, although complete elucidation of the interplay between superconductivity and ferromagnetism in these anisotropic layered compounds awaits the development of single crystalline materials for further investigation.

  1. Gravitational memory charges of supertranslation and superrotation on Rindler horizons

    NASA Astrophysics Data System (ADS)

    Hotta, Masahiro; Trevison, Jose; Yamaguchi, Koji

    2016-10-01

    In a Rindler-type coordinate system spanned in a region outside of a black hole horizon, we have nonvanishing classical holographic charges as soft hairs on the horizon for stationary black holes. Taking a large black hole mass limit, the spacetimes with the charges are described by asymptotic Rindler metrics. We construct a general theory of gravitational holographic charges for a (1 +3 )-dimensional linearized gravity field in the Minkowski background with Rindler horizons. Although matter crossing a Rindler horizon causes horizon deformation and a time-dependent coordinate shift—that is, gravitational memory—the supertranslation and superrotation charges on the horizon can be defined during and after its passage through the horizon. It is generally proven that holographic states on the horizon cannot store any information about absorbed perturbative gravitational waves. However, matter crossing the horizon really excites holographic states. By using gravitational memory operators, which consist of the holographic charge operators, we suggest a resolution of the no-cloning paradox of quantum information between matter falling into the horizon and holographic charges on the horizon from the viewpoint of the contextuality of quantum measurement.

  2. Accurate, reliable prototype earth horizon sensor head

    NASA Technical Reports Server (NTRS)

    Schwarz, F.; Cohen, H.

    1973-01-01

    The design and performance is described of an accurate and reliable prototype earth sensor head (ARPESH). The ARPESH employs a detection logic 'locator' concept and horizon sensor mechanization which should lead to high accuracy horizon sensing that is minimally degraded by spatial or temporal variations in sensing attitude from a satellite in orbit around the earth at altitudes in the 500 km environ 1,2. An accuracy of horizon location to within 0.7 km has been predicted, independent of meteorological conditions. This corresponds to an error of 0.015 deg-at 500 km altitude. Laboratory evaluation of the sensor indicates that this accuracy is achieved. First, the basic operating principles of ARPESH are described; next, detailed design and construction data is presented and then performance of the sensor under laboratory conditions in which the sensor is installed in a simulator that permits it to scan over a blackbody source against background representing the earth space interface for various equivalent plant temperatures.

  3. Towards Assessing the Human Trajectory Planning Horizon

    PubMed Central

    Nitsch, Verena; Meinzer, Dominik; Wollherr, Dirk

    2016-01-01

    Mobile robots are envisioned to cooperate closely with humans and to integrate seamlessly into a shared environment. For locomotion, these environments resemble traversable areas which are shared between multiple agents like humans and robots. The seamless integration of mobile robots into these environments requires accurate predictions of human locomotion. This work considers optimal control and model predictive control approaches for accurate trajectory prediction and proposes to integrate aspects of human behavior to improve their performance. Recently developed models are not able to reproduce accurately trajectories that result from sudden avoidance maneuvers. Particularly, the human locomotion behavior when handling disturbances from other agents poses a problem. The goal of this work is to investigate whether humans alter their trajectory planning horizon, in order to resolve abruptly emerging collision situations. By modeling humans as model predictive controllers, the influence of the planning horizon is investigated in simulations. Based on these results, an experiment is designed to identify, whether humans initiate a change in their locomotion planning behavior while moving in a complex environment. The results support the hypothesis, that humans employ a shorter planning horizon to avoid collisions that are triggered by unexpected disturbances. Observations presented in this work are expected to further improve the generalizability and accuracy of prediction methods based on dynamic models. PMID:27936015

  4. New Horizons Imaging of Jupiter's Main Ring

    NASA Astrophysics Data System (ADS)

    Throop, Henry B.; Showalter, Mark Robert; Dones, Henry C. Luke; Hamilton, D. P.; Weaver, Harold A.; Cheng, Andrew F.; Stern, S. Alan; Young, Leslie; Olkin, Catherine B.; New Horizons Science Team

    2016-10-01

    New Horizons took roughly 520 visible-light images of Jupiter's ring system during its 2007 flyby, using the spacecraft's Long-Range Reconnaissance Imager (LORRI). These observations were taken over nine days surrounding Jupiter close-approach. They span a range in distance of 30 - 100 RJ, and a phase angle range of 20 - 174 degrees. The highest resolution images -- more than 200 frames -- were taken at a resolution approaching 20 km/pix.We will present an analysis of this dataset, much of which has not been studied in detail before. Our results include New Horizons' first quantitative measurements of the ring's intrinsic brightness and variability. We will also present results on the ring's azimuthal and radial structure. Our measurements of the ring's phase curve will be used to infer properties of the ring's dust grains.Our results build on the only previous analysis of the New Horizons Jupiter ring data set, presented in Showalter et al (2007, Science 318, 232-234), which detected ring clumps and placed a lower limit on the population of undetected ring-moons.This work was supported by NASA's OPR program.

  5. The Event Horizon of M87

    NASA Astrophysics Data System (ADS)

    Broderick, Avery E.; Narayan, Ramesh; Kormendy, John; Perlman, Eric S.; Rieke, Marcia J.; Doeleman, Sheperd S.

    2015-06-01

    The 6× {{10}9} {{M}⊙ } supermassive black hole at the center of the giant elliptical galaxy M87 powers a relativistic jet. Observations at millimeter wavelengths with the Event Horizon Telescope have localized the emission from the base of this jet to angular scales comparable to the putative black hole horizon. The jet might be powered directly by an accretion disk or by electromagnetic extraction of the rotational energy of the black hole. However, even the latter mechanism requires a confining thick accretion disk to maintain the required magnetic flux near the black hole. Therefore, regardless of the jet mechanism, the observed jet power in M87 implies a certain minimum mass accretion rate. If the central compact object in M87 were not a black hole but had a surface, this accretion would result in considerable thermal near-infrared and optical emission from the surface. Current flux limits on the nucleus of M87 strongly constrain any such surface emission. This rules out the presence of a surface and thereby provides indirect evidence for an event horizon.

  6. ICD-10-CM/PCS: Transferring Knowledge from ICD-9-CM

    PubMed Central

    Sand, Jaime N.; Elison-Bowers, Patt

    2013-01-01

    The transition to ICD-10-CM/PCS has expanded educational opportunities for educators and trainers who are taking on the responsibility of training coders on the new system. Coding education currently faces multiple challenges in the areas of how to train the new workforce, what might be the most efficient method of providing that training, how much retraining of the current workforce with ICD-9-CM training will be required, and how to meet the national implementation deadline of 2014 in the most efficacious manner. This research sought to identify if there was a difference between a group of participants with no knowledge of ICD-9-CM and those with some knowledge of ICD-9-CM in scores on an ICD-10-CM/PCS quiz. Results indicate a difference, supporting the idea of knowledge transfer between the systems and providing additional insight into coding education. PMID:23861677

  7. The late Barremian Halimedides horizon of the Dolomites (Southern Alps, Italy)

    PubMed Central

    Lukeneder, Alexander; Uchman, Alfred; Gaillard, Christian; Olivero, Davide

    2012-01-01

    A new trace fossil marker level, the Halimedides horizon, is proposed for the Lower Cretaceous pelagic to hemipelagic succession of the Puez area (Southern Alps, Italy). The horizon occurs in the middle part of the late Barremian Gerhardtia sartousiana Zone (Gerhardtia sartousiana Subzone). It is approximately 20 cm thick and restricted to the uppermost part of the Puez Limestone Member (marly limestones; Hauterivian–Barremian; Puez Formation). It is fixed to the top 20 cm of bed P1/204. The grey–whitish limestone bed of the G. sartousiana Zone is penetrated by Aptian red marls–siltstones of the Redbed Member. The horizon is documented for the first time from the Southern Alps, including the Dolomites, and can be correlated with other Mediterranean localities. The trace fossil assemblage of this marker bed with the co-occurrence of Halimedides, Spongeliomorpha and Zoophycos sheds light on the Lower Cretaceous sedimentological history and current system of the Puez area within the Dolomites. It also highlights the palaeoenvironmental evolution of basins and plateaus and provides insights into the late Barremian interval. PMID:27087717

  8. Detailed modelling of the 21-cm forest

    NASA Astrophysics Data System (ADS)

    Semelin, B.

    2016-01-01

    The 21-cm forest is a promising probe of the Epoch of Reionization. The local state of the intergalactic medium (IGM) is encoded in the spectrum of a background source (radio-loud quasars or gamma-ray burst afterglow) by absorption at the local 21-cm wavelength, resulting in a continuous and fluctuating absorption level. Small-scale structures (filaments and minihaloes) in the IGM are responsible for the strongest absorption features. The absorption can also be modulated on large scales by inhomogeneous heating and Wouthuysen-Field coupling. We present the results from a simulation that attempts to preserve the cosmological environment while resolving some of the small-scale structures (a few kpc resolution in a 50 h-1 Mpc box). The simulation couples the dynamics and the ionizing radiative transfer and includes X-ray and Lyman lines radiative transfer for a detailed physical modelling. As a result we find that soft X-ray self-shielding, Ly α self-shielding and shock heating all have an impact on the predicted values of the 21-cm optical depth of moderately overdense structures like filaments. A correct treatment of the peculiar velocities is also critical. Modelling these processes seems necessary for accurate predictions and can be done only at high enough resolution. As a result, based on our fiducial model, we estimate that LOFAR should be able to detect a few (strong) absorptions features in a frequency range of a few tens of MHz for a 20 mJy source located at z = 10, while the SKA would extract a large fraction of the absorption information for the same source.

  9. The formation of frangipane horizons and their influence on physical-chemical properties of soils from glass houses

    NASA Astrophysics Data System (ADS)

    Filipov, F.; Bulgariu, D.; Avarvarei, I.

    2009-04-01

    The pedological, mineralogical and geochemical studies performed by as on soils (s.s hortic antrosols) from Iasi (Copou glass house), Barlad and Bacau glass houses have show that, in most of cases, the profile of hortic antrosols have the following compositions: Aho-AC-C or Ck, and Aho-B/C or Ck, respectively. In function of parental material nature and specific exploitation technologies, can appear the diagnostic horizons of association (hiposalic-sc, hiponatric-ac etc.) and / or of transition (A/B, A/C, C/A, A+C, ABk etc.). Specific for soils from glass houses are intense modifications of soil profile, large variability of mineralogy and chemistry, salinization processes (by progressive accumulation of soluble salts) at superior horizons level and formation, at 50 cm depth, of a compact and impermeable horizon (frangipane horizon). From chemical point of view, the hortic antrosols are generally characterized by high values of saturation in bases, of accessible phosphorus and of ratio between humic and fulvic acids (organic matter is dominant in intense humified fraction). Regarding the formation conditions, the mineralogy and geochemistry of frangipane horizons, in this moment, in literature are not too many data. In case of studied soils, the frangipane horizons appear in specific forms, where their structure, morphology and chemistry varied in large limits. In hortic antrosols where are formed, the frangipane horizons determined a sever pedogeochemical segregation. Thus, the horizons situated above to the frangipane horizon evolutes in weak oxidant conditions, weak acid-neutral pH (5.87 - 6.95), high salinity and humidity, intense biological activity; while the horizons situated below to the frangipane horizon evolutes in weak reduction conditions, neutral - weak alkaline pH (7.61 - 8.04), reduced salinity and humidity, weak biological activity. This determined an important differentiation of micro-elements and organic compounds dynamic, evidenced by the

  10. Isotope shifts in methane near 6000/cm

    NASA Technical Reports Server (NTRS)

    Fox, K.; Halsey, G. W.; Jennings, D. E.

    1976-01-01

    Isotope shifts for cleanly resolved vibrational-rotational absorption lines of CH4-12 and CH4-13 were measured by a 5-m focal length Littrow spectrometer in the 6000/cm range. The methane isotopes were held in separate absorption cells: 20 torr of CH4-13 in a 1-m cell, and 5 torr of CH4-12 in a White cell of 4-m optical path length. Measured shifts for the cleanly resolved singlets R(0), R(1), Q(1) and P(1) are summarized in tabular form.

  11. An engineering model 30 cm ion thruster

    NASA Technical Reports Server (NTRS)

    Poeschel, R. L.; King, H. J.; Schnelker, D. E.

    1973-01-01

    Thruster development at Hughes Research Laboratories and NASA Lewis Research Center has brought the 30-cm mercury bombardment ion thruster to the state of an engineering model. This thruster has been designed to have sufficient internal strength for direct mounting on gimbals, to weigh 7.3 kg, to operate with a corrected overall efficiency of 71%, and to have 10,000 hours lifetime. Subassemblies, such as the ion optical system, isolators, etc., have been upgraded to meet launch qualification standards. This paper presents a summary of the design specifications and performance characteristics which define the interface between the thruster module and the remainder of the propulsion system.

  12. A 30-cm diameter argon ion source

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.

    1976-01-01

    A 30 cm diameter argon ion source was evaluated. Ion source beam currents up to 4a were extracted with ion energies ranging from 0.2 to 1.5 KeV. An ion optics scaling relation was developed for predicting ion beam extraction capability as a function of total extraction voltage, gas type, and screen grid open area. Ignition and emission characteristics of several hollow cathode geometries were assessed for purposes of defining discharge chamber and neutralizer cathodes. Also presented are ion beam profile characteristics which exhibit broad beam capability well suited for ion beam sputtering applications.

  13. The Evolution of Star formation Activity in Cluster Galaxies over 0.15 < z < 1.5

    NASA Astrophysics Data System (ADS)

    Wagner, Cory R.; Courteau, Stéphane; Brodwin, Mark; Stanford, S. A.; Snyder, Gregory F.; Stern, Daniel

    2017-01-01

    We explore 7.5 billion years of evolution in the star formation activity of massive ({M}\\star > {10}10.1 {M}ȯ ) cluster galaxies using a sample of 25 clusters over 0.15< z< 1 from the Cluster Lensing And Supernova survey with Hubble and 11 clusters over 1< z< 1.5 from the IRAC Shallow Cluster Survey. Galaxy morphologies are determined visually using high-resolution Hubble Space Telescope images. Using the spectral energy distribution fitting code Code Investigating GALaxy Emission, we measure star formation rates, stellar masses, and 4000 Å break strengths. The latter are used to separate quiescent and star-forming galaxies (SFGs). From z∼ 1.3 to z∼ 0.2, the specific star formation rate (sSFR) of cluster SFGs and quiescent galaxies decreases by factors of three and four, respectively. Over the same redshift range, the sSFR of the entire cluster population declines by a factor of 11, from 0.48+/- 0.06 {{Gyr}}-1 to 0.043+/- 0.009 {{Gyr}}-1. This strong overall sSFR evolution is driven by the growth of the quiescent population over time; the fraction of quiescent cluster galaxies increases from {28}-19+8 % to {88}-4+5 % over z ∼ 1.3 to 0.2. The majority of the growth occurs at z≳ 0.9, where the quiescent fraction increases by 0.41. While the sSFR of the majority of star-forming cluster galaxies is at the level of the field, a small subset of cluster SFGs have low field-relative star formation activity, suggestive of long-timescale quenching. The large increase in the fraction of quiescent galaxies above z∼ 0.9, coupled with the field-level sSFRs of cluster SFGs, suggests that higher-redshift cluster galaxies are likely being quenched quickly. Assessing those timescales will require more accurate stellar population ages and star formation histories.

  14. On the accretion process in a high-mass star forming region. A multitransitional THz Herschel-HIFI study of ammonia toward G34.26+0.15

    NASA Astrophysics Data System (ADS)

    Hajigholi, M.; Persson, C. M.; Wirström, E. S.; Black, J. H.; Bergman, P.; Olofsson, A. O. H.; Olberg, M.; Wyrowski, F.; Coutens, A.; Hjalmarson, Å.; Menten, K. M.

    2016-01-01

    Aims: Our aim is to explore the gas dynamics and the accretion process in the early phase of high-mass star formation. Methods: The inward motion of molecular gas in the massive star forming region G34.26+0.15 is investigated by using high-resolution profiles of seven transitions of ammonia at THz frequencies observed with Herschel-HIFI. The shapes and intensities of these lines are interpreted in terms of radiative transfer models of a spherical, collapsing molecular envelope. An accelerated Lambda Iteration (ALI) method is used to compute the models. Results: The seven ammonia lines show mixed absorption and emission with inverse P-Cygni-type profiles that suggest infall onto the central source. A trend toward absorption at increasingly higher velocities for higher excitation transitions is clearly seen in the line profiles. The J = 3 ← 2 lines show only very weak emission, so these absorption profiles can be used directly to analyze the inward motion of the gas. This is the first time a multitransitional study of spectrally resolved rotational ammonia lines has been used for this purpose. Broad emission is, in addition, mixed with the absorption in the 10-00 ortho-NH3 line, possibly tracing a molecular outflow from the star forming region. The best-fitting ALI model reproduces the continuum fluxes and line profiles, but slightly underpredicts the emission and absorption depth in the ground-state ortho line 10-00. An ammonia abundance on the order of 10-9 relative to H2 is needed to fit the profiles. The derived ortho-to-para ratio is approximately 0.5 throughout the infalling cloud core similar to recent findings for translucent clouds in sight lines toward W31C and W49N. We find evidence of two gas components moving inwards toward the central region with constant velocities: 2.7 and 5.3 km s-1, relative to the source systemic velocity. Attempts to model the inward motion with a single gas cloud in free-fall collapse did not succeed. Herschel is an ESA space

  15. Fuel elements of research reactor CM

    SciTech Connect

    Kozlov, A.V.; Morozov, A.V.; Vatulin, A.V.; Ershov, S.A.

    2013-07-01

    In 1961 the CM research reactor was commissioned at the Research Institute of Atomic Reactors (Dimitrovgrad, Russia), it was intended to carry on investigations and the production of transuranium nuclides. The reactor is of a tank type. Original fuel assembly contained plate fuels that were spaced with vanes and corrugated bands. Nickel was used as a cladding material, fuel meat was produced from UO{sub 2} + electrolytic nickel composition. Fuel plates have been replaced by self-spacing cross-shaped dispersion fuels clad in stainless steel. In 2005 the reactor was updated. The purpose of this updating was to increase the quantity of irradiation channels in the reactor core and to improve the neutron balance. The updating was implemented at the expense of 20 % reduction in the quantity of fuel elements in the core which released a space for extra channels and decreased the mass of structural materials in the core. The updated reactor is loaded with modified standard fuel elements with 20 % higher uranium masses. At the same time stainless steel in fuel assembly shrouds was substituted by zirconium alloy. Today in progress are investigations and work to promote the second stage of reactor updating that involve developments of cross-shaped fuel elements having low neutron absorption matrix materials. This article gives an historical account of the design and main technical changes that occurred for the CM reactor since its commissioning.

  16. Redundant Array Configurations for 21 cm Cosmology

    NASA Astrophysics Data System (ADS)

    Dillon, Joshua S.; Parsons, Aaron R.

    2016-08-01

    Realizing the potential of 21 cm tomography to statistically probe the intergalactic medium before and during the Epoch of Reionization requires large telescopes and precise control of systematics. Next-generation telescopes are now being designed and built to meet these challenges, drawing lessons from first-generation experiments that showed the benefits of densely packed, highly redundant arrays—in which the same mode on the sky is sampled by many antenna pairs—for achieving high sensitivity, precise calibration, and robust foreground mitigation. In this work, we focus on the Hydrogen Epoch of Reionization Array (HERA) as an interferometer with a dense, redundant core designed following these lessons to be optimized for 21 cm cosmology. We show how modestly supplementing or modifying a compact design like HERA’s can still deliver high sensitivity while enhancing strategies for calibration and foreground mitigation. In particular, we compare the imaging capability of several array configurations, both instantaneously (to address instrumental and ionospheric effects) and with rotation synthesis (for foreground removal). We also examine the effects that configuration has on calibratability using instantaneous redundancy. We find that improved imaging with sub-aperture sampling via “off-grid” antennas and increased angular resolution via far-flung “outrigger” antennas is possible with a redundantly calibratable array configuration.

  17. THE METALLICITY OF THE CM DRACONIS SYSTEM

    SciTech Connect

    Terrien, Ryan C.; Fleming, Scott W.; Mahadevan, Suvrath; Deshpande, Rohit; Bender, Chad F.; Ramsey, Lawrence W.; Feiden, Gregory A.

    2012-11-20

    The CM Draconis system comprises two eclipsing mid-M dwarfs of nearly equal mass in a 1.27 day orbit. This well-studied eclipsing binary has often been used for benchmark tests of stellar models, since its components are among the lowest mass stars with well-measured masses and radii ({approx}< 1% relative precision). However, as with many other low-mass stars, non-magnetic models have been unable to match the observed radii and effective temperatures for CM Dra at the 5%-10% level. To date, the uncertain metallicity of the system has complicated comparison of theoretical isochrones with observations. In this Letter, we use data from the SpeX instrument on the NASA Infrared Telescope Facility to measure the metallicity of the system during primary and secondary eclipses, as well as out of eclipse, based on an empirical metallicity calibration in the H and K near-infrared (NIR) bands. We derive an [Fe/H] = -0.30 {+-} 0.12 that is consistent across all orbital phases. The determination of [Fe/H] for this system constrains a key dimension of parameter space when attempting to reconcile model isochrone predictions and observations.

  18. Ferromanganese crusts from Necker Ridge, Horizon Guyot and S.P. Lee Guyot: Geological considerations

    USGS Publications Warehouse

    Hein, J.R.; Manheim, F. T.; Schwab, W.C.; Davis, A.S.

    1985-01-01

    Necker Ridge, Horizon Guyot and S.P. Lee Guyot in the Central Pacific were sampled, seismically surveyed, and photographed by bottom cameras in order to better understand the distribution, origin, and evolution of ferromanganese crusts. Necker Ridge is over 600 km long with a rugged crest, pods of sediment to 146 m thick, slopes that average 12?? to 20??, and debris aprons that cover some of the lower flanks. Substrate lithologies are mostly hyaloclastite, volcaniclastic breccia, and minor alkalic basalt. Horizon Guyot, 300 km long and 75 km wide, is capped by at least 160 m of sediment, which buries stepped terraces. Substrate lithologies are similar to those on Necker Ridge, although previous workers sampled much tholeiitic basalt on Horizon. S.P. Lee Guyot, 125 km long and 80 km wide, is capped by at least 300 m of sediment, and contains talus aprons along its lower flanks. Ferromanganese-encrusted rocks were recovered in every dredge and are thickest on Necker Ridge. Crust thicknesses average about 2.5, 1.5, and 0.8 cm for Necker, Horizon, and S.P. Lee, respectively. Crusts range from smooth or porous surfaces to knobby and botryoidal. The entire crust is laminated, however, two distinct layers commonly exist, separated by a paper-thin layer of phosphorite. The dominant mineral of all crusts is vernadite (??-MnO2), while quartz, feldspar, apatite, and, in three rocks todorokite, are minor phases. Quartz and feldspar decrease with decreasing latitude of occurrence, and is suggested to be related to eolian input. On the average, apatite also increases within the crusts with decreasing latitude of occurrence, which may be related to high biological productivity in the zone of equatorial upwelling. Phosphorite substrates are more abundant on Necker Ridge and S.P. Lee Guyot than they are on Horizon Guyot. Seamount ferromanganese nodules are distinct from abyssal nodules in their chemistry and internal structure. ?? 1985.

  19. Design study of large area 8 cm x 8 cm wrapthrough cells for space station

    NASA Technical Reports Server (NTRS)

    Garlick, George F. J.; Lillington, David R.

    1987-01-01

    The design of large area silicon solar cells for the projected NASA space station is discussed. It is based on the NASA specification for the cells which calls for an 8 cm by 8 cm cell of wrapthrough type with gridded back contacts. The beginning of life (BOL) power must be 1.039 watts per cell or larger and maximum end of life (EOL) after 10 years in the prescribed orbit under an equivalent 1MeV electron radiation damage fluence of 5 times 10 to the 13th power e/square cm. On orbit efficiency is to be optimized by a low thermal absorptance goal (thermal alpha) of .63.

  20. Aliphatic Amines in Antarctic CR2, CM2, and CM1/2 Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Aponte, Jose C.; McLain, Hannah L.; Dworkin, Jason P.; Elsila, Jamie E.

    2016-01-01

    Meteoritic water-soluble organic compounds provide a unique record of the processes that occurred during the formation of the solar system and the chemistry preceding the origins of life on Earth. We have investigated the molecular distribution, compound-specific delta13C isotopic ratios and enantiomeric compositions of aliphatic monoamines present in the hot acid-water extracts of the carbonaceous chondrites LAP 02342 (CR2), GRA 95229 (CR2), LON 94101 (CM2), LEW 90500 (CM2), and ALH 83100 (CM1/2). Analyses of the concentration of monoamines in these meteorites revealed: (a) the CR2 chondrites studied here contain higher concentrations of monoamines relative to the analyzed CM2 chondrites; (b) the concentration of monoamines decreases with increasing carbon number; and (c) isopropylamine is the most abundant monoamine in these CR2 chondrites, while methylamine is the most abundant amine species in these CM2 and CM1/2 chondrites. The delta13C values of monoamines in CR2 chondrite do not correlate with the number of carbon atoms; however, in CM2 and CM1/2 chondrites, the 13C enrichment decreases with increasing monoamine carbon number. The delta13C values of methylamine in CR2 chondrites ranged from -1 to +10per mille, while in CM2 and CM1/2 chondrites the delta13C values of methylamine ranged from +41 to +59per mille. We also observed racemic compositions of sec-butylamine, 3-methyl-2-butylamine, and sec-pentylamine in the studied carbonaceous chondrites. Additionally, we compared the abundance and delta13C isotopic composition of monoamines to those of their structurally related amino acids. We found that monoamines are less abundant than amino acids in CR2 chondrites, with the opposite being true in CM2 and CM1/2 chondrites. We used these collective data to evaluate different primordial synthetic pathways for monoamines in carbonaceous chondrites and to understand the potential common origins these molecules may share with meteoritic amino acids.

  1. Aliphatic amines in Antarctic CR2, CM2, and CM1/2 carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Aponte, José C.; McLain, Hannah L.; Dworkin, Jason P.; Elsila, Jamie E.

    2016-09-01

    Meteoritic water-soluble organic compounds provide a unique record of the processes that occurred during the formation of the solar system and the chemistry preceding the origins of life on Earth. We have investigated the molecular distribution, compound-specific δ13C isotopic ratios and enantiomeric compositions of aliphatic monoamines present in the hot acid-water extracts of the carbonaceous chondrites LAP 02342 (CR2), GRA 95229 (CR2), LON 94101 (CM2), LEW 90500 (CM2), and ALH 83100 (CM1/2). Analyses of the concentration of monoamines in these meteorites revealed: (a) the CR2 chondrites studied here contain higher concentrations of monoamines relative to the analyzed CM2 chondrites; (b) the concentration of monoamines decreases with increasing carbon number; and (c) isopropylamine is the most abundant monoamine in these CR2 chondrites, while methylamine is the most abundant amine species in these CM2 and CM1/2 chondrites. The δ13C values of monoamines in CR2 chondrite do not correlate with the number of carbon atoms; however, in CM2 and CM1/2 chondrites, the 13C enrichment decreases with increasing monoamine carbon number. The δ13C values of methylamine in CR2 chondrites ranged from -1 to +10‰, while in CM2 and CM1/2 chondrites the δ13C values of methylamine ranged from +41 to +59‰. We also observed racemic compositions of sec-butylamine, 3-methyl-2-butylamine, and sec-pentylamine in the studied carbonaceous chondrites. Additionally, we compared the abundance and δ13C isotopic composition of monoamines to those of their structurally related amino acids. We found that monoamines are less abundant than amino acids in CR2 chondrites, with the opposite being true in CM2 and CM1/2 chondrites. We used these collective data to evaluate different primordial synthetic pathways for monoamines in carbonaceous chondrites and to understand the potential common origins these molecules may share with meteoritic amino acids.

  2. The effect of soil horizon and mineral type on the distribution of siderophores in soil

    NASA Astrophysics Data System (ADS)

    Ahmed, Engy; Holmström, Sara J. M.

    2014-04-01

    Iron is a key component of the chemical architecture of the biosphere. Due to the low bioavailability of iron in the environment, microorganisms have developed specific uptake strategies like production of siderophores. Siderophores are operationally defined as low-molecular-mass biogenic Fe(III)-binding compounds, that can increase the bioavailability of iron by promoting the dissolution of iron-bearing minerals. In the present study, we investigated the composition of dissolved and adsorbed siderophores of the hydroxamate family in the soil horizons of podzol and the effect of specific mineral types on siderophores. Three polished mineral specimens of 3 cm × 4 cm × 3 mm (apatite, biotite and oligioclase) were inserted in the soil horizons (O (organic), E (eluvial) and B (upper illuvial)). After two years, soil samples were collected from both the bulk soil of the whole profile and from the soil attached to the mineral surfaces. The concentration of ten different fungal tri-hydroxamates within ferrichromes, fusigen and coprogens families, and five bacterial hydroxamates within the ferrioxamine family were detected. All hydroxamate types were determined in both soil water (dissolved) and soil methanol (adsorbed) extracts along the whole soil profile by high-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS); hence, the study is the most extensive of its kind. We found that coprogens and fusigen were present in much higher concentrations in bulk soil than were ferrioxamines and ferrichromes. On the other hand, the presence of the polished mineral completely altered the distribution of siderophores. In addition, each mineral had a unique interaction with the dissolved and adsorbed hydroxamates in the different soil horizons. Thus siderophore composition in the soil environment is controlled by the chemical, physical and biological characteristics of each soil horizon and also by the available mineral types.

  3. Mapping Cosmic Structure Using 21-cm Hydrogen Signal at Green Bank Telescope

    NASA Astrophysics Data System (ADS)

    Voytek, Tabitha; GBT 21-cm Intensity Mapping Group

    2011-05-01

    We are using the Green Bank Telescope to make 21-cm intensity maps of cosmic structure in a 0.15 Gpc^3 box at redshift of z 1. The intensity mapping technique combines the flux from many galaxies in each pixel, allowing much greater mapping speed than the traditional redshift survey. Measurement is being made at z 1 to take advantage of a window in frequency around 700 MHz where terrestrial radio frequency interference (RFI) is currently at a minimum. This minimum is due to a reallocation of this frequency band from analog television to wide area wireless internet and public service usage. We will report progress of our attempt to detect autocorrelation of the 21-cm signal. The ultimate goal of this mapping is to use Baryon Acoustic Oscillations to provide more precise constraints to dark energy models.

  4. The 30-cm ion thruster power processor

    NASA Technical Reports Server (NTRS)

    Herron, B. G.; Hopper, D. J.

    1978-01-01

    A power processor unit for powering and controlling the 30 cm Mercury Electron-Bombardment Ion Thruster was designed, fabricated, and tested. The unit uses a unique and highly efficient transistor bridge inverter power stage in its implementation. The system operated from a 200 to 400 V dc input power bus, provides 12 independently controllable and closely regulated dc power outputs, and has an overall power conditioning capacity of 3.5 kW. Protective circuitry was incorporated as an integral part of the design to assure failure-free operation during transient and steady-state load faults. The implemented unit demonstrated an electrical efficiency between 91.5 and 91.9 at its nominal rated load over the 200 to 400 V dc input bus range.

  5. Magnesium isotopic fractionation in chondrules from the Murchison and Murray CM2 carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Bouvier, Audrey; Wadhwa, Meenakshi; Simon, Steven B.; Grossman, Lawrence

    2013-03-01

    We present high-precision measurements of the Mg isotopic compositions of a suite of types I and II chondrules separated from the Murchison and Murray CM2 carbonaceous chondrites. These chondrules are olivine- and pyroxene-rich and have low 27Al/24Mg ratios (0.012-0.316). The Mg isotopic compositions of Murray chondrules are on average lighter (δ26Mg ranging from -0.95‰ to -0.15‰ relative to the DSM-3 standard) than those of Murchison (δ26Mg ranging from -1.27‰ to +0.77‰). Taken together, the CM2 chondrules exhibit a narrower range of Mg isotopic compositions than those from CV and CB chondrites studied previously. The least-altered CM2 chondrules are on average lighter (average δ26Mg = -0.39 ± 0.30‰, 2SE) than the moderately to heavily altered CM2 chondrules (average δ26Mg = -0.11 ± 0.21‰, 2SE). The compositions of CM2 chondrules are consistent with isotopic fractionation toward heavy Mg being associated with the formation of secondary silicate phases on the CM2 parent body, but were also probably affected by volatilization and recondensation processes involved in their original formation. The low-Al CM2 chondrules analyzed here do not exhibit any mass-independent variations in 26Mg from the decay of 26Al, with the exception of two chondrules that show only small variations just outside of the analytical error. In the case of the chondrule with the highest Al/Mg ratio (a type IAB chondrule from Murchison), the lack of resolvable 26Mg excess suggests that it either formed >1 Ma after calcium-aluminum-rich inclusions, or that its Al-Mg isotope systematics were reset by secondary alteration processes on the CM2 chondrite parent body after the decay of 26Al.

  6. Designing new biocompatible glass-forming Ti75-x Zr10 Nbx Si15 (x = 0, 15) alloys: corrosion, passivity, and apatite formation.

    PubMed

    Abdi, Somayeh; Oswald, Steffen; Gostin, Petre Flaviu; Helth, Arne; Sort, Jordi; Baró, Maria Dolors; Calin, Mariana; Schultz, Ludwig; Eckert, Jürgen; Gebert, Annett

    2016-01-01

    Glass-forming Ti-based alloys are considered as potential new materials for implant applications. Ti75 Zr10 Si15 and Ti60 Zr10 Nb15 Si15 alloys (free of cytotoxic elements) can be produced as melt-spun ribbons with glassy matrix and embedded single β-type nanocrystals. The corrosion and passivation behavior of these alloys in their homogenized melt-spun states have been investigated in Ringer solution at 37°C in comparison to their cast multiphase crystalline counterparts and to cp-Ti and β-type Ti-40Nb. All tested materials showed very low corrosion rates as expressed in corrosion current densities icorr  < 50 nA/cm(2). Electrochemical and surface analytical studies revealed a high stability of the new alloys passive states in a wide potential range. This corresponds to low passive current densities ipass  = 2 ± 1 µA/cm(2) based on the growth of oxide films with thickness d <10 nm. A homogeneous constituent distribution in the melt-spun alloys is beneficial for stable surface passivity. The addition of Nb does not only improve the glass-forming ability and the mechanical properties but also supports a high pitting resistance even at extreme anodic polarization up to 4V versus SCE were oxide thickness values of d ∼35 nm are reached. With regard to the corrosion properties, the Nb-containing nearly single-phase glassy alloy can compete with the β-type Ti-40Nb alloy. SBF tests confirmed the ability for formation of hydroxyapatite on the melt-spun alloy surfaces. All these properties recommend the new glass-forming alloys for application as wear- and corrosion-resistant coating materials for implants.

  7. Pair production close to black hole horizon

    NASA Astrophysics Data System (ADS)

    Laurent, Philippe; Titarchuk, Lev

    2012-07-01

    Accreting stellar-mass black holes in Galactic binaries exhibit a ``bi-modal" spectral behavior - namely the so called high-soft and low-hard spectral states. An increase in the soft blackbody luminosity component leads to the appearance of an extended power law. An important observational fact is that this effect is seen as a persistent phenomenon only in BH candidates, and thus it is apparently a unique black hole signature. Although similar power law components are detected in the intermediate stages in neutron star systems, they are of a transient nature, i.e. disappearing with increasing luminosity. It thus seems a reasonable assumption that the unique spectral signature of the soft state of BH binaries is directly tied to the black hole event horizon. This is the primary motivation for the Bulk Motion Comptonization Model, introduced in several previous papers, and recently applied with striking success to a substantial body of observational data. We argued that the BH X-ray spectrum in the high-soft state is formed in the relatively cold accretion flow with a subrelativistic bulk velocity close to c and a temperature of a few keV. In such a flow the effect of the bulk Comptonization is indeed much stronger than the effect of the thermal ones. Another property of these accreted flow, that we will explore during this talk, is that, very close to horizon, X-ray photons may be upscattered by bulk electrons to MeV energy. Most of these photons fall down then in the black hole, but some of them anyway have time to interact with another X-ray photon by the photon-photon process to make an electron-positron pairs. We will then explore in details the consequences of this pair creation process close to horizon and what can be the observational evidences of this effect.

  8. Art, the Urban Skyscraper, and Horizon Astronomy

    NASA Astrophysics Data System (ADS)

    Mooney, J. D.

    2016-01-01

    This presentation delineates the historiography and the iconography of my urban public sculptures which use skyscrapers as today's standing stones, markers for horizon astronomy. From 1977 to the present time, my work has engaged the public to “look up and see.” Through ephemeral works in the sky and over the water to large-scale rooftop sculptures in Los Angeles, Chicago, Atlanta, and Europe, viewers are oriented to the Milky Way, the summer triangle, and other celestial phenomena. This new urban scale art, transformative in context and gesture, has become part of the new cultural landscape.

  9. Prolate horizons and the Penrose inequality

    SciTech Connect

    Tippett, Benjamin K.

    2009-05-15

    The Penrose inequality has so far been proven in cases of spherical symmetry and in cases of zero extrinsic curvature. The next simplest case worth exploring would be nonspherical, nonrotating black holes with nonzero extrinsic curvature. Following Karkowski et al.'s construction of prolate black holes, we define initial data on an asymptotically flat spacelike 3-surface with nonzero extrinsic curvature that may be chosen freely. This gives us the freedom to define the location of the apparent horizon such that the Penrose inequality is violated. We show that the dominant energy condition is violated at the poles for all cases considered.

  10. Peripheral Vision Horizon Display (PVHD). Corrected Copy

    NASA Technical Reports Server (NTRS)

    1984-01-01

    A Canadian invention, the peripheral vision horizon display (PVHD), shows promise in alleviating vertigo or disorientation in pilots flying under instrument conditions and easing the piloting task when flying in weather or other conditions requiring close attention to aircraft attitude instruments. A diversity of research and applied work was being done to investigate and validate the benefits of the PVHD during the years immediately preceding this conference. Organizers of the conference were able to assemble a group of outstanding presenters representing academic, industrial, and military. The theoretical foundation and applied use of the PVHD are discussed, and results from operational tests are presented.

  11. Time Horizon and Social Scale in Communication

    NASA Astrophysics Data System (ADS)

    Krantz, D. H.

    2010-12-01

    In 2009 our center (CRED) published a first version of The Psychology of Climate Change Communication. In it, we attempted to summarize facts and concepts from psychological research that could help guide communication. While this work focused on climate change, most of the ideas are at least partly applicable for communication about a variety of natural hazards. Of the many examples in this guide, I mention three. Single-action bias is the human tendency to stop considering further actions that might be needed to deal with a given hazard, once a single action has been taken. Another example is the importance of group affiliation in motivating voluntary contributions to joint action. A third concerns the finding that group participation enhances understanding of probabilistic concepts and promotes action in the face of uncertainty. One current research direction, which goes beyond those included in the above publication, focuses on how time horizons arise in the thinking of individuals and groups, and how these time horizons might influence hazard preparedness. On the one hand, individuals sometimes appear impatient, organizations look for immediate results, and officials fail to look beyond the next election cycle. Yet under some laboratory conditions and in some subcultures, a longer time horizon is adopted. We are interested in how time horizon is influenced by group identity and by the very architecture of planning and decision making. Institutional changes, involving long-term contractual relationships among communities, developers, insurers, and governments, could greatly increase resilience in the face of natural hazards. Communication about hazards, in the context of such long-term contractual relationships might look very different from communication that is first initiated by immediate threat. Another new direction concerns the social scale of institutions and of communication about hazards. Traditionally, insurance contracts share risk among a large

  12. New horizons mapping of Europa and Ganymede.

    PubMed

    Grundy, W M; Buratti, B J; Cheng, A F; Emery, J P; Lunsford, A; McKinnon, W B; Moore, J M; Newman, S F; Olkin, C B; Reuter, D C; Schenk, P M; Spencer, J R; Stern, S A; Throop, H B; Weaver, H A

    2007-10-12

    The New Horizons spacecraft observed Jupiter's icy satellites Europa and Ganymede during its flyby in February and March 2007 at visible and infrared wavelengths. Infrared spectral images map H2O ice absorption and hydrated contaminants, bolstering the case for an exogenous source of Europa's "non-ice" surface material and filling large gaps in compositional maps of Ganymede's Jupiter-facing hemisphere. Visual wavelength images of Europa extend knowledge of its global pattern of arcuate troughs and show that its surface scatters light more isotropically than other icy satellites.

  13. An uneventful horizon in two dimensions

    NASA Astrophysics Data System (ADS)

    Almheiri, Ahmed; Sully, James

    2014-02-01

    We investigate the possibility of firewalls in the Einstein-dilaton gravity model of CGHS. We use the results of the numerical simulation carried out by Ashtekar et al. to demonstrate that firewalls are absent and the horizon is drama free. We show that the lack of a firewall is consistent because the model does not satisfy one of the postulates of black hole complementarity. In particular, we elaborate on previous work showing that the Hawking radiation is not pure, and is completely entangled with a long-lived remnant beyond the last ray.

  14. Evaluation of Argonne 9-cm and 10-cm Annular Centrifugal Contactors for SHINE Solution Processing

    SciTech Connect

    Wardle, Kent E.; Pereira, Candido; Vandegrift, George

    2015-02-01

    Work is in progress to evaluate the SHINE Medical Technologies process for producing Mo-99 for medical use from the fission of dissolved low-enriched uranium (LEU). This report addresses the use of Argonne annular centrifugal contactors for periodic treatment of the process solution. In a letter report from FY 2013, Pereira and Vandegrift compared the throughput and physical footprint for the two contactor options available from CINC Industries: the V-02 and V-05, which have rotor diameters of 5 cm and 12.7 cm, respectively. They suggested that an intermediately sized “Goldilocks” contactor might provide a better balance between throughput and footprint to meet the processing needs for the uranium extraction (UREX) processing of the SHINE solution to remove undesired fission products. Included with the submission of this letter report are the assembly drawings for two Argonne-design contactors that are in this intermediate range—9-cm and 10-cm rotors, respectively. The 9-cm contactor (drawing number CE-D6973A, stamped February 15, 1978) was designed as a single-stage unit and built and tested in the late 1970s along with other size units, both smaller and larger. In subsequent years, a significant effort to developed annular centrifugal contactors was undertaken to support work at Hanford implementing the transuranic extraction (TRUEX) process. These contactors had a 10-cm rotor diameter and were fully designed as multistage units with four stages per assembly (drawing number CMT-E1104, stamped March 14, 1990). From a technology readiness perspective, these 10-cm units are much farther ahead in the design progression and, therefore, would require significantly less re-working to make them ready for UREX deployment. Additionally, the overall maximum throughput of ~12 L/min is similar to that of the 9-cm unit (10 L/min), and the former could be efficiently operated over much of the same range of throughput. As a result, only the 10-cm units are considered here

  15. Redshift of a photon emitted along the black hole horizon

    NASA Astrophysics Data System (ADS)

    Toporensky, A. V.; Zaslavskii, O. B.

    2017-03-01

    In this work we derive some general features of the redshift measured by radially moving observers in the black hole background. Let observer 1 cross the black hole horizon emitting a photon, while observer 2 crossing the same horizon later receives it. We show that if (i) the horizon is the outer one (event horizon) and (ii) it is nonextremal, the received frequency is redshifted. This generalizes recent results in the literature. For the inner horizon (like in the Reissner-Nordström metric) the frequency is blueshifted. If the horizon is extremal, the frequency does not change. We derive explicit formulas describing the frequency shift in generalized Kruskal- and Lemaitre-like coordinates.

  16. New Horizons. A National Workplace Literacy Program. Final Report. "New Horizons" External Evaluation Impact Study.

    ERIC Educational Resources Information Center

    Hudson, Patt; Gretes, John A.

    The New Horizons project was a workplace literacy partnership during which 454 employees (53%) of Georgetown Steel attended classes provided by Horry-Georgetown Technical College in Conway, South Carolina. Of the 454 participants, 294 were white, 159 were black, 71 were female, 383 were male, 133 had been with the company for 5 years or less, and…

  17. Dynamical horizons: energy, angular momentum, fluxes, and balance laws.

    PubMed

    Ashtekar, Abhay; Krishnan, Badri

    2002-12-23

    Dynamical horizons are considered in full, nonlinear general relativity. Expressions of fluxes of energy and angular momentum carried by gravitational waves across these horizons are obtained. Fluxes are local, the energy flux is positive, and change in the horizon area is related to these fluxes. The flux formulas also give rise to balance laws analogous to the ones obtained by Bondi and Sachs at null infinity and provide generalizations of the first and second laws of black-hole mechanics.

  18. Radiation from quantum weakly dynamical horizons in loop quantum gravity.

    PubMed

    Pranzetti, Daniele

    2012-07-06

    We provide a statistical mechanical analysis of quantum horizons near equilibrium in the grand canonical ensemble. By matching the description of the nonequilibrium phase in terms of weakly dynamical horizons with a local statistical framework, we implement loop quantum gravity dynamics near the boundary. The resulting radiation process provides a quantum gravity description of the horizon evaporation. For large black holes, the spectrum we derive presents a discrete structure which could be potentially observable.

  19. Gravitational anomaly and Hawking radiation near a weakly isolated horizon

    SciTech Connect

    Wu Xiaoning; Huang Chaoguang; Sun Jiarui

    2008-06-15

    Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near a weakly isolated horizon. We find that there exists a universal choice of tortoise coordinate for any weakly isolated horizon. Under this coordinate, the leading behavior of a quite arbitrary scalar field near a horizon is a 2-dimensional chiral scalar field. This means we can extend the idea of Wilczek and his collaborators to more general cases and show the relation between gravitational anomaly and Hawking radiation is a universal property of a black hole horizon.

  20. Gravitational anomaly and Hawking radiation near a weakly isolated horizon

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoning; Huang, Chao-Guang; Sun, Jia-Rui

    2008-06-01

    Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near a weakly isolated horizon. We find that there exists a universal choice of tortoise coordinate for any weakly isolated horizon. Under this coordinate, the leading behavior of a quite arbitrary scalar field near a horizon is a 2-dimensional chiral scalar field. This means we can extend the idea of Wilczek and his collaborators to more general cases and show the relation between gravitational anomaly and Hawking radiation is a universal property of a black hole horizon.

  1. Into the Kuiper Belt: New Horizons Post-Pluto

    NASA Astrophysics Data System (ADS)

    Harrison Parker, Alex; Spencer, John; Benecchi, Susan; Binzel, Richard; Borncamp, David; Buie, Marc; Fuentes, Cesar; Gwyn, Stephen; Kavelaars, JJ; Noll, Keith; Petit, Jean-Marc; Porter, Simon; Showalter, Mark; Stern, S. Alan; Sterner, Ray; Tholen, David; Verbiscer, Anne; Weaver, Hal; Zangari, Amanda

    2015-11-01

    New Horizons is now beyond Pluto and flying deeper into the Kuiper Belt. In the summer of 2014, a Hubble Space Telescope Large Program identified two candidate Cold Classical Kuiper Belt Objects (KBOs) that were within reach of New Horizons' remaining fuel budget. Here we present the selection of the Kuiper Belt flyby target for New Horizons' post-Pluto mission, our state of knowledge regarding this target and the potential 2019 flyby, the status of New Horizons' targeting maneuver, and prospects for near-future long-range observations of other KBOs.

  2. Criticality and surface tension in rotating horizon thermodynamics

    NASA Astrophysics Data System (ADS)

    Hansen, Devin; Kubizňák, David; Mann, Robert B.

    2016-08-01

    We study a modified horizon thermodynamics and the associated criticality for rotating black hole spacetimes. Namely, we show that under a virtual displacement of the black hole horizon accompanied by an independent variation of the rotation parameter, the radial Einstein equation takes a form of a ‘cohomogeneity two’ horizon first law, δ E=Tδ S+{{Ω }}δ J-σ δ A, where E and J are the horizon energy (an analogue of the Misner-Sharp mass) and the horizon angular momentum, Ω is the horizon angular velocity, A is the horizon area, and σ is the surface tension induced by the matter fields. For fixed angular momentum, the above equation simplifies and the more familiar (cohomogeneity one) horizon first law δ E=Tδ S-Pδ V is obtained, where P is the pressure of matter fields and V is the horizon volume. A universal equation of state is obtained in each case and the corresponding critical behavior is studied.

  3. Numerical examination of an evolving black string horizon

    NASA Astrophysics Data System (ADS)

    Garfinkle, David; Lehner, Luis; Pretorius, Frans

    2005-03-01

    We use the numerical solution describing the evolution of a perturbed black string presented by M. Choptuik, L. Lehner, I. Olabarrieta, R. Petryk, F. Pretorius, and H. Villegas [Phys. Rev. D 68, 044001 (2003)] to elucidate the intrinsic behavior of the horizon. It is found that by the end of the simulation, the affine parameter on the horizon has become very large and the expansion and shear of the horizon in turn very small. This suggests the possibility that the horizon might pinch off in infinite affine parameter.

  4. Isolated and dynamical horizons from a common perspective

    SciTech Connect

    Korzynski, Mikolaj

    2006-11-15

    A framework is developed in which one can write down the constraint equations on a three-dimensional hypersurface of arbitrary signature. It is then applied to isolated and dynamical horizons. The derived equations can be used to extract physically relevant quantities describing the horizon irrespective to whether it is isolated (null) or dynamical at a given instant of time. Furthermore, a small perturbation of isolated horizons are considered, and finally a family of an axially symmetric exact solution of the constraint equations on a dynamical horizon is presented.

  5. Horizons versus singularities in spherically symmetric space-times

    SciTech Connect

    Bronnikov, K. A.; Elizalde, E.; Odintsov, S. D.; Zaslavskii, O. B.

    2008-09-15

    We discuss different kinds of Killing horizons possible in static, spherically symmetric configurations and recently classified as 'usual', 'naked', and 'truly naked' ones depending on the near-horizon behavior of transverse tidal forces acting on an extended body. We obtain the necessary conditions for the metric to be extensible beyond a horizon in terms of an arbitrary radial coordinate and show that all truly naked horizons, as well as many of those previously characterized as naked and even usual ones, do not admit an extension and therefore must be considered as singularities. Some examples are given, showing which kinds of matter are able to create specific space-times with different kinds of horizons, including truly naked ones. Among them are fluids with negative pressure and scalar fields with a particular behavior of the potential. We also discuss horizons and singularities in Kantowski-Sachs spherically symmetric cosmologies and present horizon regularity conditions in terms of an arbitrary time coordinate and proper (synchronous) time. It turns out that horizons of orders 2 and higher occur in infinite proper times in the past or future, but one-way communication with regions beyond such horizons is still possible.

  6. Energy and information near black hole horizons

    SciTech Connect

    Freivogel, Ben

    2014-07-01

    The central challenge in trying to resolve the firewall paradox is to identify excitations in the near-horizon zone of a black hole that can carry information without injuring a freely falling observer. By analyzing the problem from the point of view of a freely falling observer, I arrive at a simple proposal for the degrees of freedom that carry information out of the black hole. An infalling observer experiences the information-carrying modes as ingoing, negative energy excitations of the quantum fields. In these states, freely falling observers who fall in from infinity do not encounter a firewall, but freely falling observers who begin their free fall from a location close to the horizon are ''frozen'' by a flux of negative energy. When the black hole is ''mined,'' the number of information-carrying modes increases, increasing the negative energy flux in the infalling frame without violating the equivalence principle. Finally, I point out a loophole in recent arguments that an infalling observer must detect a violation of unitarity, effective field theory, or free infall.

  7. THE EVENT HORIZON OF SAGITTARIUS A*

    SciTech Connect

    Broderick, Avery E.; Loeb, Abraham; Narayan, Ramesh

    2009-08-20

    Black hole event horizons, causally separating the external universe from compact regions of spacetime, are one of the most exotic predictions of general relativity. Until recently, their compact size has prevented efforts to study them directly. Here we show that recent millimeter and infrared observations of Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, all but require the existence of a horizon. Specifically, we show that these observations limit the luminosity of any putative visible compact emitting region to below 0.4% of Sgr A*'s accretion luminosity. Equivalently, this requires the efficiency of converting the gravitational binding energy liberated during accretion into radiation and kinetic outflows to be greater than 99.6%, considerably larger than those implicated in Sgr A*, and therefore inconsistent with the existence of such a visible region. Finally, since we are able to frame this argument entirely in terms of observable quantities, our results apply to all geometric theories of gravity that admit stationary solutions, including the commonly discussed f(R) class of theories.

  8. Near-horizon brane-scan revived

    NASA Astrophysics Data System (ADS)

    Duff, M. J.

    2009-03-01

    In 1987 two versions of the brane-scan of D-dimensional super p-branes were put forward. The first pinpointed those (p,D) slots consistent with kappa-symmetric Green-Schwarz type actions; the second generalized the membrane at the end of the universe idea to all those superconformal groups describing p-branes on the boundary of AdS×S. Although the second version predicted D3- and M5-branes in addition to those of the first, it came unstuck because the 1/2 BPS solitonic branes failed to exhibit the required symmetry enhancement in the near-horizon limit, except in the non-dilatonic cases (p=2,D=11), (p=3,D=10) and (p=5,D=11). Just recently, however, it has been argued that the fundamental D=10 heterotic string does indeed display a near-horizon enhancement to OSp(8|2) as predicted by the brane-scan, provided α corrections are taken into account. If this logic could be extended to the other strings and branes, it would resolve this 21-year-old paradox and provide a wealth of new AdS/CFT dualities, which we tabulate.

  9. 50 Years of Soil Survey Horizons

    NASA Astrophysics Data System (ADS)

    Brevik, E. C.

    2012-04-01

    Soil Survey Horizons (SSH) started in 1960 as the newsletter of the North Central Soil Survey, United States, with an editorial board consisting of Francis D. Hole, O.C. Rogers, and Donald F. Post. SSH was started to provide an outlet for field observations of soils because the founders of SSH felt that other outlets for such communications were disappearing. Francis Hole's office at the University of Wisconsin served as the point of publication for SSH through its first 15 years, but in 1975 the Soil Science Society of America (SSSA) began handling its publication. Initially SSSA published SSH but did not assume ownership or editorial control of the publication until 2005. Over the years there has been a steady increase in the amount of material published in each volume of SSH. Significant improvements to Soil Survey Horizons over the years have included a move to full 8.5" x 11" pages and publication in color. Future improvements will include online publication and expansion to an international audience, including recruitement of international members for the editorial board.

  10. Status of the Event Horizon Telescope

    NASA Astrophysics Data System (ADS)

    Fish, Vincent L.; Doeleman, S. S.; Event Horizon Telescope Collaboration

    2011-05-01

    The goal of the Event Horizon Telescope (EHT) project is to understand the physical and astrophysical processes of supermassive black holes though extremely high angular resolution observations. The EHT consists of existing millimeter-wavelength telescopes that participate in very long baseline interferometry (VLBI) observations of Sagittarius A*, M87, and active galactic nuclei. For the nearest sources, the EHT is uniquely capable of providing a resolution of a few Schwarzschild radii. Prior EHT observations have demonstrated very compact structure in Sgr A* and have been used to constrain the orientation of the black hole spin vector, strengthen the case for the existence of an event horizon, and examine the spatial characteristics of the variable millimeter emission. The sensitivity and angular resolution of the array are increasing due to the inclusion of new telescopes and several technical developments currently underway. We will summarize the most recent observations as well as the outlook for further enhancements of the capabilities of the EHT in the near future. This work is funded by grants from the National Science Foundation.

  11. Oil sheen weathering post Deepwater Horizon

    NASA Astrophysics Data System (ADS)

    Kellermann, M. Y.; Redmond, M. C.; Reddy, C. M.; Aeppli, C.; Nelson, R. K.; Valentine, D. L.

    2013-12-01

    A recently published study identified the source of the reoccurred oil sheens close to the Deepwater Horizon (DWH) disaster site as a finite contamination most likely derived from tanks and pits on the DWH wreckage itself. Here we use geochemical fingerprinting and microbial community analysis to better understand the fate and weathering processes affecting these surface oils. Both, alkanes and polycyclic aromatic hydrocarbons (PAHs) are shown to reflect a linear decrease of hydrocarbon compounds with increasing distance to the DWH wreckage site (equivalent to exposure time on the sea surface). These results indicate that in the early stage of weathering the combined effects of dissolution and evaporation dominate the degradation of these surface oils. Sheen microbial communities were dominated by Cyanobacteria, Planctomycetes, Verrucomicrobia, Flavobacteria, Alphaproteobacteria, and Deltaproteobacteria, with low relative abundances of Gammaproteobacteria likely to be hydrocarbon degraders (no more than 15% of sequences in each sample). However, some of these Gammaproteobacteria were closely related to putative hydrocarbon degraders observed in abundance in deep water plumes during the primary Deepwater Horizon spill, suggesting that very low levels of biodegradation may be also occurring. This in situ weathering experiment provides new insights in hydrocarbon weathering dynamics and shows how chemical and biological changes can potentially be masked by large evaporative losses of compounds smaller than C18 n-alkanes.

  12. Cool horizons lead to information loss

    NASA Astrophysics Data System (ADS)

    Chowdhury, Borun D.

    2013-10-01

    There are two evidences for information loss during black hole evaporation: (i) a pure state evolves to a mixed state and (ii) the map from the initial state to final state is non-invertible. Any proposed resolution of the information paradox must address both these issues. The firewall argument focuses only on the first and this leads to order one deviations from the Unruh vacuum for maximally entangled black holes. The nature of the argument does not extend to black holes in pure states. It was shown by Avery, Puhm and the author that requiring the initial state to final state map to be invertible mandates structure at the horizon even for pure states. The proof works if black holes can be formed in generic states and in this paper we show that this is indeed the case. We also demonstrate how models proposed by Susskind, Papadodimas et al. and Maldacena et al. end up making the initial to final state map non-invertible and thus make the horizon "cool" at the cost of unitarity.

  13. Energy and information near black hole horizons

    NASA Astrophysics Data System (ADS)

    Freivogel, Ben

    2014-07-01

    The central challenge in trying to resolve the firewall paradox is to identify excitations in the near-horizon zone of a black hole that can carry information without injuring a freely falling observer. By analyzing the problem from the point of view of a freely falling observer, I arrive at a simple proposal for the degrees of freedom that carry information out of the black hole. An infalling observer experiences the information-carrying modes as ingoing, negative energy excitations of the quantum fields. In these states, freely falling observers who fall in from infinity do not encounter a firewall, but freely falling observers who begin their free fall from a location close to the horizon are ``frozen'' by a flux of negative energy. When the black hole is ``mined,'' the number of information-carrying modes increases, increasing the negative energy flux in the infalling frame without violating the equivalence principle. Finally, I point out a loophole in recent arguments that an infalling observer must detect a violation of unitarity, effective field theory, or free infall.

  14. Engineering model 8-cm thruster subsystem

    NASA Technical Reports Server (NTRS)

    Herron, B. G.; Hyman, J.; Hopper, D. J.; Williamson, W. S.; Dulgeroff, C. R.; Collett, C. R.

    1978-01-01

    An Engineering Model (EM) 8 cm Ion Thruster Propulsion Subsystem was developed for operation at a thrust level 5 mN (1.1 mlb) at a specific impulse 1 sub sp = 2667 sec with a total system input power P sub in = 165 W. The system dry mass is 15 kg with a mercury-propellant-reservoir capacity of 8.75 kg permitting uninterrupted operation for about 12,500 hr. The subsystem can be started from a dormant condition in a time less than or equal to 15 min. The thruster has a design lifetime of 20,000 hr with 10,000 startup cycles. A gimbal unit is included to provide a thrust vector deflection capability of + or - 10 degrees in any direction from the zero position. The EM subsystem development program included thruster optimization, power-supply circuit optimization and flight packaging, subsystem integration, and subsystem acceptance testing including a cyclic test of the total propulsion package.

  15. The 15 cm diameter ion thruster research

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1974-01-01

    The startup reliability of a 15 cm diameter mercury bombardment ion thruster which employs a pulsed high voltage tickler electrode on the main and neutralizer cathodes is examined. Startup of the thruster is achieved 100% of the time on the main cathode and 98.7% of the time on the neutralizer cathode over a 3640 cycle test. The thruster was started from a 20 C initial condition and operated for an hour at a 600 mA beam current. An energy efficiency of 75% and a propellant utilization efficiency of 77% was achieved over the complete cycle. The effect of a single cusp magnetic field thruster length on its performance is discussed. Guidelines are formulated for the shaping of magnetic field lines in thrusters. A model describing double ion production in mercury discharges is presented. The production route is shown to occur through the single ionic ground state. Photographs of the interior of an operating-hollow cathode are presented. A cathode spot is shown to be present if the cathode is free of low work-function surfaces. The spot is observed if a low work-function oxide coating is applied to the cathode insert. Results show that low work-function oxide coatings tend to migrate during thruster operation.

  16. Impacts of Deepwater Horizon Oil on Marsh Sediment Biogeochemistry in Barataria Bay, LA, USA

    NASA Astrophysics Data System (ADS)

    Mills, C. T.; Windham-Myers, L.; Waldrop, M. P.; Krabbenhoft, D. P.; Marvin-DiPasquale, M. C.; Orem, W. H.; Piazza, S.; Haw, M.; McFarland, J.; Varonka, M. S.

    2012-12-01

    Oil from the Deepwater Horizon spill came ashore on many salt marsh islands in Barataria Bay, LA in summer 2010, coating plants and settling on the sediment surface. In coordination with a plant community study of affected marshes, we investigated impacts of oiling on marsh sediment microbial biogeochemistry. Sediment samples (upmost 2 cm) were collected along transects perpendicular and parallel to the shore at three oiled and three non-oiled sites in both July and Oct. 2011. Samples from both collections were analyzed for sediment characteristics, total and methylmercury, and microbial membrane phospholipid fatty acids (PLFAs) which are a proxy for viable microbial cell numbers. Sediment DNA collected in Oct. 2011 was analyzed for bacterial, fungal, and archaeal community composition and abundance as well as various enzyme activities. Select Oct. 2011 samples were assayed to determine the rates of terminal electron accepting processes (oxygen demand, denitrification, iron reduction, sulfate reduction, methanogenesis). All sites had similar sediment characteristics. Impacts on sediment biogeochemistry were greatest at marsh edges, and reduced microbial abundance appeared to be more important than changes in microbial community structure. In July 2011, the mean PLFA concentration in oiled marsh edge sediments (0.15±0.03 μmol g-1; 95% CI; n=9) was substantially lower than for non-oiled sites (0.33±0.08 μmol g-1; n=9). Mean PLFA concentrations for interior marsh samples were more similar for oiled (0.30±0.08 μmol g-1; n=8) and non-oiled (0.37±0.04 μmol g-1; n=9) sites. This PLFA pattern was also observed in Oct. 2011 samples, and other measures of microbial abundance and activity showed similar trends. Cellulase, phosphatase, and chitinase mean activities were nearly twice as great in non-oiled versus oiled edge sites. Lower microbial activity in oiled sites was also inferred by somewhat lower denitrification and sulfate reduction potentials. Conversely, both

  17. Empirical correction for earth sensor horizon radiance variation

    NASA Technical Reports Server (NTRS)

    Hashmall, Joseph A.; Sedlak, Joseph; Andrews, Daniel; Luquette, Richard

    1998-01-01

    A major limitation on the use of infrared horizon sensors for attitude determination is the variability of the height of the infrared Earth horizon. This variation includes a climatological component and a stochastic component of approximately equal importance. The climatological component shows regular variation with season and latitude. Models based on historical measurements have been used to compensate for these systematic changes. The stochastic component is analogous to tropospheric weather. It can cause extreme, localized changes that for a period of days, overwhelm the climatological variation. An algorithm has been developed to compensate partially for the climatological variation of horizon height and at least to mitigate the stochastic variation. This method uses attitude and horizon sensor data from spacecraft to update a horizon height history as a function of latitude. For spacecraft that depend on horizon sensors for their attitudes (such as the Total Ozone Mapping Spectrometer-Earth Probe-TOMS-EP) a batch least squares attitude determination system is used. It is assumed that minimizing the average sensor residual throughout a full orbit of data results in attitudes that are nearly independent of local horizon height variations. The method depends on the additional assumption that the mean horizon height over all latitudes is approximately independent of season. Using these assumptions, the method yields the latitude dependent portion of local horizon height variations. This paper describes the algorithm used to generate an empirical horizon height. Ideally, an international horizon height database could be established that would rapidly merge data from various spacecraft to provide timely corrections that could be used by all.

  18. Accuracy of free energies of hydration using CM1 and CM3 atomic charges.

    PubMed

    Udier-Blagović, Marina; Morales De Tirado, Patricia; Pearlman, Shoshannah A; Jorgensen, William L

    2004-08-01

    Absolute free energies of hydration (DeltaGhyd) have been computed for 25 diverse organic molecules using partial atomic charges derived from AM1 and PM3 wave functions via the CM1 and CM3 procedures of Cramer, Truhlar, and coworkers. Comparisons are made with results using charges fit to the electrostatic potential surface (EPS) from ab initio 6-31G* wave functions and from the OPLS-AA force field. OPLS Lennard-Jones parameters for the organic molecules were used together with the TIP4P water model in Monte Carlo simulations with free energy perturbation theory. Absolute free energies of hydration were computed for OPLS united-atom and all-atom methane by annihilating the solutes in water and in the gas phase, and absolute DeltaGhyd values for all other molecules were computed via transformation to one of these references. Optimal charge scaling factors were determined by minimizing the unsigned average error between experimental and calculated hydration free energies. The PM3-based charge models do not lead to lower average errors than obtained with the EPS charges for the subset of 13 molecules in the original study. However, improvement is obtained by scaling the CM1A partial charges by 1.14 and the CM3A charges by 1.15, which leads to average errors of 1.0 and 1.1 kcal/mol for the full set of 25 molecules. The scaled CM1A charges also yield the best results for the hydration of amides including the E/Z free-energy difference for N-methylacetamide in water.

  19. Photodynamic therapy in dermatology: history and horizons.

    PubMed

    Taub, Amy Forman

    2004-01-01

    Photodynamic therapy (PDT) uses a photosensitizer, light, and molecular oxygen to selectively kill cells. When localized in the target tissue, the photosensitizer is activated by light to produce oxygen intermediates that destroy target tissue cells. The easy access of skin to light-based therapy has led dermatologists to apply PDT to cutaneous disorders. In dermatology, PDT has been most successful in treating actinic keratoses, basal cell carcinoma, and Bowen's disease. The introduction of aminolevulinic acid, which does not make patients susceptible to phototoxicity for extended periods, has reduced morbidity associated with PDT. This has led to new interest in PDT not only for nonmelanoma skin cancer and premalignant lesions but also in the treatment of acne and as an adjuvant to photorejuvenation procedures. This review examines the historical roots of PDT and the research evaluating different light and laser sources as well as reports on new horizons for PDT in dermatology.

  20. Horizon complementarity in elliptic de Sitter space

    NASA Astrophysics Data System (ADS)

    Hackl, Lucas; Neiman, Yasha

    2015-02-01

    We study a quantum field in elliptic de Sitter space dS4/Z2—the spacetime obtained from identifying antipodal points in dS4. We find that the operator algebra and Hilbert space cannot be defined for the entire space, but only for observable causal patches. This makes the system into an explicit realization of the horizon complementarity principle. In the absence of a global quantum theory, we propose a recipe for translating operators and states between observers. This translation involves information loss, in accordance with the fact that two observers see different patches of the spacetime. As a check, we recover the thermal state at the de Sitter temperature as a state that appears the same to all observers. This thermal state arises from the same functional that, in ordinary dS4, describes the Bunch-Davies vacuum.

  1. Black Hole Observations - Towards the Event Horizon

    NASA Astrophysics Data System (ADS)

    Britzen, Silke

    Black Holes are probably the most elusive solutions of Einstein's theory of General Relativity. Despite numerous observations of the direct galactic environment and indirect influence of astrophysical black holes (e.g. jets, variable emission across the wavelength spectrum, feedback processes, etc.) -- a direct proof of their existence is still lacking. This article highlights some aspects deduced from many observations and concentrates on the experimental results with regard to black holes with masses from millions to billions of solar masses. The focus will be on the challenges and remaining questions. The Event Horizon Telescopce (EHT) project to image the photon sphere of Sgr A* and its potential is briefly sketched. This instrumental approach shall lead to highest resolution observations of the supermassive black hole at the center of the Milky Way (Sgr A*).

  2. The NMC Horizon Report: 2014 K-12 Edition

    ERIC Educational Resources Information Center

    Johnson, L.; Adams Becker, S.; Estrada, V.; Freeman, A.

    2014-01-01

    "The NMC Horizon Report" series is the most visible outcome of the New Media Consortium (NMC) Horizon Project, an ongoing research effort established in 2002 that identifies and describes emerging technologies likely to have a large impact on teaching, learning, research, or creative expression within every sector of education in some 65…

  3. Submesoscale Dispersion in the Vicinity of the Deepwater Horizon Spill

    DTIC Science & Technology

    2014-09-02

    ecosystems, society, and the economy as evidenced by the Deepwater Horizon oil spill in the Gulf of Mexico in 2010 and the Fukushima nuclear plant...evidenced by the Deepwater Horizon oil spill in the Gulf of Mexico in 2010 and the Fukushima nuclear plant incident in the Pacific Ocean in 2011. Accurate

  4. NEW JERSEY APPROACH TO OUTERBRIDGE CROSSING BRIDGE, NOTE DISTANT HORIZON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    NEW JERSEY APPROACH TO OUTERBRIDGE CROSSING BRIDGE, NOTE DISTANT HORIZON NEW YORK SKYLINE AND ALMOST IN THE MIDDLE OF THE HORIZON THE TWIN TOWERS OF THE VERRAZANO-NARROWS BRIDGE - Outerbridge Crossing Bridge, Spanning Arthur Kill from New Jersey to Staten Island, Staten Island (subdivision), Richmond County, NY

  5. Near-horizon conformal symmetry and black hole entropy.

    PubMed

    Carlip, S

    2002-06-17

    Near an event horizon, the action of general relativity acquires a new asymptotic conformal symmetry. For two-dimensional dilaton gravity, this symmetry results in a chiral Virasoro algebra, and Cardy's formula for the density of states reproduces the Bekenstein-Hawking entropy. This lends support to the notion that black hole entropy is controlled universally by conformal symmetry near the horizon.

  6. The NMC Horizon Report: 2015 Higher Education Edition

    ERIC Educational Resources Information Center

    Johnson, L.; Adams Becker, S.; Estrada, V.; Freeman, A.

    2015-01-01

    The "NMC Horizon Report: 2015 Higher Education Edition" is a collaborative effort between the New Media Consortium (NMC) and the EDUCAUSE Learning Initiative (ELI). This 12th edition describes annual findings from the NMC Horizon Project, an ongoing research project designed to identify and describe emerging technologies likely to have…

  7. Comparing Three Jet Rates with and without Hadronic Rindler Horizon

    NASA Astrophysics Data System (ADS)

    Ghaffary, Tooraj

    2017-03-01

    Recently, some researchers, (Sepehri and Shoorvazi Chin. Phys. Lett. 30(2), 021301, [2013]), have considered the effect of Rindler horizon on three jet rate. This paper confirms their results and by comparing usual models with this new model for different energies, shows that regarding Rindler horizon gives us the results which more close to experimental data respect to usual models.

  8. New Horizons Risk Communication Strategy, Planning, Implementation, and Lessons Learned

    NASA Technical Reports Server (NTRS)

    Dawson, Sandra A.

    2006-01-01

    This paper discusses the risk communication goals, strategy, planning process and product development for the New Horizons mission, including lessons from the Cassini mission that were applied in that effort, and presents lessons learned from the New Horizons effort that could be applicable to future missions.

  9. The NMC Horizon Report: 2011 K-12 Edition

    ERIC Educational Resources Information Center

    Johnson, L.; Adams, S.; Haywood, K.

    2011-01-01

    "The NMC Horizon Report" series is the most visible outcome of the New Media Consortium. (NMC) Horizon Project, an ongoing research effort established in 2002 that identifies and describes emerging technologies likely to have a large impact on teaching, learning, research, or creative expression within education around the globe. This volume, "The…

  10. The NMC Horizon Report: 2013 K-12 Edition

    ERIC Educational Resources Information Center

    Johnson, L.; Adams Becker, S.; Cummins, M.; Estrada V.; Freeman, A.; Ludgate, H.

    2013-01-01

    "The NMC Horizon Report" series is the most visible outcome of the New Media Consortium (NMC) Horizon Project, an ongoing research effort established in 2002 that identifies and describes emerging technologies likely to have a large impact on teaching, learning, research, or creative expression within education around the globe. This…

  11. A Fusion of Horizons: Students' Encounters with "Will and Wave"

    ERIC Educational Resources Information Center

    Myers, James L.

    2006-01-01

    In a case study, I applied philosophical hermeneutic principles in an advanced level EFL writing class in Taiwan. A "fusion of horizons" occurs at the junction of two intertwined interpretations: one from our socio-historical tradition and the other from our experience of novel phenomena. I explored students' hermeneutic horizons in…

  12. The Horizon Report: 2009 Australia-New Zealand Edition

    ERIC Educational Resources Information Center

    Johnson, L.; Levine, A.; Smith, R.; Smythe, T.; Stone, S.

    2009-01-01

    The New Media Consortium's Horizon Project is an ongoing research project that aims to identify and describe emerging technologies likely to have a large impact on teaching, learning, or creative inquiry within education around the globe over a five-year time period. The project's central products are the "Horizon Reports", an annual…

  13. The NMC Horizon Report: 2012 Higher Education Edition

    ERIC Educational Resources Information Center

    Johnson, L.; Adams, S.; Cummins, M.

    2012-01-01

    The internationally recognized "NMC Horizon Report" series and regional "NMC Technology Outlooks" are part of the NMC Horizon Project, a comprehensive research venture established in 2002 that identifies and describes emerging technologies likely to have a large impact over the coming five years in education around the globe. This volume, the "NMC…

  14. THERMAL CONDUCTIVITY OF THE POTENTIAL REPOSITORY HORIZON

    SciTech Connect

    J.E. BEAN

    2004-09-27

    The primary purpose of this report is to assess the spatial variability and uncertainty of bulk thermal conductivity in the host horizon for the repository at Yucca Mountain. More specifically, the lithostratigraphic units studied are located within the Topopah Spring Tuff (Tpt) and consist of the upper lithophysal zone (Tptpul), the middle nonlithophysal zone (Tptpmn), the lower lithophysal zone (Tptpll), and the lower nonlithophysal zone (Tptpln). Design plans indicate that approximately 81 percent of the repository will be excavated in the Tptpll, approximately 12 percent in the Tptpmn, and the remainder in the Tptul and Tptpln (BSC 2004 [DIRS 168370]). This report provides three-dimensional geostatistical estimates of the bulk thermal conductivity for the four stratigraphic layers of the repository horizon. The three-dimensional geostatistical estimates of matrix and lithophysal porosity, dry bulk density, and matrix thermal conductivity are also provided. This report provides input to various models and calculations that simulate heat transport through the rock mass. These models include the ''Drift Degradation Analysis, Multiscale Thermohydrologic Model, Ventilation Model and Analysis Report, Igneous Intrusion Impacts on Waste Packages and Waste Forms, Drift-Scale Coupled Processes (DST and TH Seepage) Models'', and ''Drift Scale THM Model''. These models directly or indirectly provide input to the total system performance assessment (TSPA). The main distinguishing characteristic among the lithophysal and nonlithophysal units is the percentage of large-scale (centimeters-meters) voids within the rock. The Tptpul and Tptpll, as their names suggest, have a higher percentage of lithophysae than the Tptpmn and the Tptpln. Understanding the influence of the lithophysae is of great importance to understanding bulk thermal conductivity.

  15. Horizons of semiclassical black holes are cold

    NASA Astrophysics Data System (ADS)

    Brustein, Ram; Medved, A. J. M.

    2014-06-01

    We calculate, using our recently proposed semiclassical framework, the quantum state of the Hawking pairs that are produced during the evaporation of a black hole (BH). Our framework adheres to the standard rules of quantum mechanics and incorporates the quantum fluctuations of the collapsing shell spacetime in Hawking's original calculation, while accounting for back-reaction effects. We argue that the negative-energy Hawking modes need to be regularly integrated out; and so these are effectively subsumed by the BH and, as a result, the number of coherent negative-energy modes N coh at any given time is parametrically smaller than the total number of the Hawking particles N total emitted during the lifetime of the BH. We find that N coh is determined by the width of the BH wavefunction and scales as the square root of the BH entropy. We also find that the coherent negative-energy modes are strongly entangled with their positive-energy partners. Previously, we have found that N coh is also the number of coherent outgoing particles and that information can be continually transferred to the outgoing radiation at a rate set by N coh . Our current results show that, while the BH is semiclassical, information can be released without jeopardizing the nearly maximal inside-out entanglement and imply that the state of matter near the horizon is approximately the vacuum. The BH firewall proposal, on the other hand, is that the state of matter near the horizon deviates substantially from the vacuum, starting at the Page time. We find that, under the usual assumptions for justifying the formation of a firewall, one does indeed form at the Page time. However, the possible loophole lies in the implicit assumption that the number of strongly entangled pairs can be of the same order of N total .

  16. New λ6 cm and λ11 cm observations of the supernova remnant CTA 1

    NASA Astrophysics Data System (ADS)

    Sun, X. H.; Reich, W.; Wang, C.; Han, J. L.; Reich, P.

    2011-11-01

    Aims: We attempt to study spatial variations in the spectrum and rotation measures (RMs) of the large-diameter, high-latitude supernova remnant (SNR) CTA 1. Methods: We conducted new λ6 cm and λ11 cm observations of CTA 1 using the Urumqi 25-m and Effelsberg 100-m telescopes. Data at other wavelengths were included to investigate the spectrum and polarisation properties. Results: We obtained new total intensity and polarisation maps at λ6 cm and λ11 cm with angular resolutions of 9'.5and 4'.4, respectively. We derived a spectral index of α = -0.63 ± 0.05 (Sν ∝ να) based on the integrated flux densities at 408 MHz, 1420 MHz, 2639 MHz, and 4800 MHz. The spectral index map calculated from data at the four frequencies shows a clear steepening of the spectrum from the strong shell emission towards the north-western breakout region with weak diffuse emission. The decrease of the spectral index is up to about Δα = 0.3. The RM map derived from polarisation data at λ6 cm and λ11 cm shows a sharp transition between positive RMs in the north-eastern and negative RMs in the south-western part of the SNR. We note a corresponding RM pattern of extragalactic sources and propose the existence of a large-diameter Faraday screen in front of CTA 1, which covers the north-eastern part of the SNR. The RM of the Faraday screen is estimated to be about +45 rad m-2. A RM structure function of CTA 1 indicates a very regular magnetic field within the Faraday screen, which is stronger than about 2.7 μG for a distance of 500 pc. Conclusions: CTA 1 is a large-diameter shell-type SNR located out of the Galactic plane, which makes it an ideal object to study its properties without suffering confusion. The previous detection of the rare breakout phenomenon in CTA 1 is confirmed. We identify a Faraday screen partly covering CTA 1 with a regular magnetic field in the opposite direction to the interstellar magnetic field. The detection of Faraday screens in the Galactic plane is

  17. Observations of the Geometry of Horizon-Based Optical Navigation

    NASA Technical Reports Server (NTRS)

    Christian, John; Robinson, Shane

    2016-01-01

    NASA's Orion Project has sparked a renewed interest in horizon-based optical navigation(OPNAV) techniques for spacecraft in the Earth-Moon system. Some approaches have begun to explore the geometry of horizon-based OPNAV and exploit the fact that it is a conic section problem. Therefore, the present paper focuses more deeply on understanding and leveraging the various geometric interpretations of horizon-based OPNAV. These results provide valuable insight into the fundamental workings of OPNAV solution methods, their convergence properties, and associated estimate covariance. Most importantly, the geometry and transformations uncovered in this paper lead to a simple and non-iterative solution to the generic horizon-based OPNAV problem. This represents a significant theoretical advancement over existing methods. Thus, we find that a clear understanding of geometric relationships is central to the prudent design, use, and operation of horizon-based OPNAV techniques.

  18. A disconnect between O horizon and mineral soil carbon - Implications for soil C sequestration

    SciTech Connect

    Garten Jr, Charles T

    2009-01-01

    Changing inputs of carbon to soil is one means of potentially increasing carbon sequestration in soils for the purpose of mitigating projected increases in atmospheric CO{sub 2} concentrations. The effect of manipulations of aboveground carbon input on soil carbon storage was tested in a temperate, deciduous forest in east Tennessee, USA. A 4.5-year experiment included exclusion of aboveground litterfall and supplemental litter additions (three times ambient) in an upland and a valley that differed in soil nitrogen availability. The estimated decomposition rate of the carbon stock in the O horizon was greater in the valley than in the upland due to higher litter quality (i.e., lower C/N ratios). Short-term litter exclusion or addition had no effect on carbon stock in the mineral soil, measured to a depth of 30 cm, or the partitioning of carbon in the mineral soil between particulate- and mineral-associated organic matter. A two-compartment model was used to interpret results from the field experiments. Field data and a sensitivity analysis of the model were consistent with little carbon transfer between the O horizon and the mineral soil. Increasing aboveground carbon input does not appear to be an effective means of promoting carbon sequestration in forest soil at the location of the present study because a disconnect exists in carbon dynamics between O horizon and mineral soil. Factors that directly increase inputs to belowground soil carbon, via roots, or reduce decomposition rates of organic matter are more likely to benefit efforts to increase carbon sequestration in forests where carbon dynamics in the O horizon are uncoupled from the mineral soil.

  19. PROCESS OF PRODUCING Cm$sup 244$ AND Cm$sup 24$$sup 5$

    DOEpatents

    Manning, W.M.; Studier, M.H.; Diamond, H.; Fields, P.R.

    1958-11-01

    A process is presented for producing Cm and Cm/sup 245/. The first step of the process consists in subjecting Pu/sup 2339/ to a high neutron flux and subsequently dissolving the irradiated material in HCl. The plutonium is then oxidized to at least the tetravalent state and the solution is contacted with an anion exchange resin, causing the plutonium values to be absorbed while the fission products and transplutonium elements remain in the effluent solution. The effluent solution is then contacted with a cation exchange resin causing the transplutonium, values to be absorbed while the fission products remain in solution. The cation exchange resin is then contacted with an aqueous citrate solution and tbe transplutonium elements are thereby differentially eluted in order of decreasing atomic weight, allowing collection of the desired fractions.

  20. 76 FR 55427 - Horizon Technology Finance Corporation, et al.; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-07

    ... COMMISSION Horizon Technology Finance Corporation, et al.; Notice of Application August 31, 2011. AGENCY...(a) of the Act. Applicants: Horizon Technology Finance Corporation (the ``Company''), Horizon Technology Finance Management LLC (the ``Investment Adviser''), Longview SBIC GP LLC (the ``General...

  1. Spacetimes foliated by nonexpanding and Killing horizons: Higher dimension

    NASA Astrophysics Data System (ADS)

    Lewandowski, Jerzy; Szereszewski, Adam; Waluk, Piotr

    2016-09-01

    The theory of nonexpanding horizons (NEHs) geometry and the theory of near-horizon geometries (NHGs) are two mathematical relativity frameworks generalizing the black hole theory. From the point of view of the NEHs theory, a NHG is just a very special case of a spacetime containing a NEH of many extra symmetries. It can be obtained as the Horowitz limit of a neighborhood of an arbitrary extremal Killing horizon. An unexpected relation between the two of them was discovered in the study of spacetimes foliated by a family of NEHs. The class of four-dimensional NHG solutions (either vacuum or coupled to a Maxwell field) was found as a family of examples of spacetimes admitting a NEH foliation. In the current paper, we systematically investigate geometries of the NEHs foliating a spacetime for arbitrary matter content and in arbitrary spacetime dimensions. We find that each horizon belonging to the foliation satisfies a condition that may be interpreted as an invitation for a transversal NEH to exist and to admit the structure of an extremal isolated horizon. Assuming the existence of a transversal extremal isolated horizon, we derive all the spacetime metrics satisfying the vacuum Einstein's equations. In this case, the NEHs become bifurcated Killing horizons.

  2. Physical process first law for bifurcate Killing horizons

    SciTech Connect

    Amsel, Aaron J.; Marolf, Donald; Virmani, Amitabh

    2008-01-15

    The physical process version of the first law for black holes states that the passage of energy and angular momentum through the horizon results in a change in area ({kappa}/8{pi}){delta}A={delta}E-{omega}{delta}J, so long as this passage is quasistationary. A similar physical process first law can be derived for any bifurcate Killing horizon in any spacetime dimension d{>=}3 using much the same argument. However, to make this law nontrivial, one must show that sufficiently quasistationary processes do in fact occur. In particular, one must show that processes exist for which the shear and expansion remain small, and in which no new generators are added to the horizon. Thorne, MacDonald, and Price considered related issues when an object falls across a d=4 black hole horizon. By generalizing their argument to arbitrary d{>=}3 and to any bifurcate Killing horizon, we derive a condition under which these effects are controlled and the first law applies. In particular, by providing a nontrivial first law for Rindler horizons, our work completes the parallel between the mechanics of such horizons and those of black holes for d{>=}3. We also comment on the situation for d=2.

  3. Investigations on the electronic transport and piezoresistivity properties of Ni{sub 2−X}Mn{sub 1+X}Ga (X = 0 and 0.15) Heusler alloys under hydrostatic pressure

    SciTech Connect

    Devarajan, U.; Kalai Selvan, G.; Sivaprakash, P.; Arumugam, S.; Singh, Sanjay; Esakki Muthu, S.; Roy Barman, S.

    2014-12-22

    The resisitivity of Ni{sub 2−X}Mn{sub 1+X}Ga (X = 0 and 0.15) magnetic shape memory alloys has been investigated as a function of temperature (4–300 K) and hydrostatic pressure up to 30 kilobars. The resistivity is suppressed (X = 0) and enhanced (X = 0.15) with increasing pressure. A change in piezoresistivity with respect to pressure and temperature is observed. The negative and positive piezoresistivity increases with pressure for both the alloys. The residual resistivity and electron-electron scattering factor as a function of pressure reveal that for Ni{sub 2}MnGa the electron-electron scattering is predominant, while the X = 0.15 specimen is dominated by the electron-magnon scattering. The value of electron-electron scattering factor is positive for both the samples, and it is decreasing (negative trend) for Ni{sub 2}MnGa and increasing (positive trend) for X = 0.15 with pressure. The martensite transition temperature is found to be increased with the application of external pressure for both samples.

  4. Effect of the preparation method of support on the aqueous phase reforming of ethylene glycol over 2 wt% Pt/Ce0.15Zr0.85O2 catalysts.

    PubMed

    Kim, Jung-Hyun; Jeong, Kwang-Eun; Kim, Tae-Wan; Chae, Ho-Jeong; Jeong, Soon-Yong; Kim, Chul-Ung; Lee, Kwan-Young

    2013-08-01

    The effect of catalyst support on the aqueous phase reforming of ethylene glycol over supported 2 wt% Pt/Ce0.15Zr0.85O2 catalysts have been investigated. Various types of Ce0.15Zr0.85O2 mixed oxides were prepared by hydrothermal precipitation (CZH), modified precipitation (CZM), co-precipitation (CZC), sol-gel (CZS) methods, respectively. Catalysts were characterized by XRD, N2 sorption analysis, and cyclohexane dehydration for relative metal dispersion. The support effect on the activity of 2 wt% Pt/Ce0.15Zr0.85O2 catalysts with different preparation method was given as follows: CZH < CZM < CZC < CZS. Pt/Ce0.15Zr0.85O2 (CZS) catalyst showed good catalytic activity for APR reaction due to its high metal dispersion and reducibility. The effect of reaction conditions such as reaction temperature, weight hourly space velocity (WHSV) was also studied. The hydrogen production rate and hydrogen yield increased in proportion to the reaction temperature and corresponding system pressure, whereas WHSV did not affect.

  5. Ectomycorrhizal-Dominated Boreal and Tropical Forests Have Distinct Fungal Communities, but Analogous Spatial Patterns across Soil Horizons

    PubMed Central

    McGuire, Krista L.; Allison, Steven D.; Fierer, Noah; Treseder, Kathleen K.

    2013-01-01

    Fungi regulate key nutrient cycling processes in many forest ecosystems, but their diversity and distribution within and across ecosystems are poorly understood. Here, we examine the spatial distribution of fungi across a boreal and tropical ecosystem, focusing on ectomycorrhizal fungi. We analyzed fungal community composition across litter (organic horizons) and underlying soil horizons (0–20 cm) using 454 pyrosequencing and clone library sequencing. In both forests, we found significant clustering of fungal communities by site and soil horizons with analogous patterns detected by both sequencing technologies. Free-living saprotrophic fungi dominated the recently-shed leaf litter and ectomycorrhizal fungi dominated the underlying soil horizons. This vertical pattern of fungal segregation has also been found in temperate and European boreal forests, suggesting that these results apply broadly to ectomycorrhizal-dominated systems, including tropical rain forests. Since ectomycorrhizal and free-living saprotrophic fungi have different influences on soil carbon and nitrogen dynamics, information on the spatial distribution of these functional groups will improve our understanding of forest nutrient cycling. PMID:23874569

  6. Quantum correlations through event horizons: Fermionic versus bosonic entanglement

    SciTech Connect

    Martin-Martinez, Eduardo; Leon, Juan

    2010-03-15

    We disclose the behavior of quantum and classical correlations among all the different spatial-temporal regions of a space-time with an event horizon, comparing fermionic with bosonic fields. We show the emergence of conservation laws for entanglement and classical correlations, pointing out the crucial role that statistics plays in the information exchange (and more specifically, the entanglement tradeoff) across horizons. The results obtained here could shed new light on the problem of information behavior in noninertial frames and in the presence of horizons, giving better insight into the black-hole information paradox.

  7. Horizon scan of global conservation issues for 2011.

    PubMed

    Sutherland, William J; Bardsley, Sarah; Bennun, Leon; Clout, Mick; Côté, Isabelle M; Depledge, Michael H; Dicks, Lynn V; Dobson, Andrew P; Fellman, Liz; Fleishman, Erica; Gibbons, David W; Impey, Andrew J; Lawton, John H; Lickorish, Fiona; Lindenmayer, David B; Lovejoy, Thomas E; Nally, Ralph Mac; Madgwick, Jane; Peck, Lloyd S; Pretty, Jules; Prior, Stephanie V; Redford, Kent H; Scharlemann, Jörn P W; Spalding, Mark; Watkinson, Andrew R

    2011-01-01

    This review describes outcomes of a 2010 horizon-scanning exercise building upon the first exercise conducted in 2009. The aim of both horizon scans was to identify emerging issues that could have substantial impacts on the conservation of biological diversity, and to do so sufficiently early to encourage policy-relevant, practical research on those issues. Our group included professional horizon scanners and researchers affiliated with universities and non- and inter-governmental organizations, including specialists on topics such as invasive species, wildlife diseases and coral reefs. We identified 15 nascent issues, including new greenhouse gases, genetic techniques to eradicate mosquitoes, milk consumption in Asia and societal pessimism.

  8. VLA Images of Venus at 1.3 CM and 2 CM Wavelengths

    NASA Astrophysics Data System (ADS)

    Suleiman, S. H.; Kolodner, M. A.; Butler, B. J.; Steffes, P. G.

    1996-09-01

    On April 5, 1996, we performed an observation of Venus using the Very Large Array (VLA) at 15 GHz (2 cm) and 22 GHz (1.3 cm) simultaneously. High resolution continuum images for Venus were obtained at both frequencies. These images show significant polar darkening at latitudes above 60(deg) which is consistent with the results obtained by the Pioneer Venus Orbiter Infrared Radiometer (OIR) experiment (Taylor et al., J. Geophys. Res. 85, 7963-8006, 1980). These images are currently being used to detect potential spatial (longitudinal and latitudinal) variations in the abundances of gaseous sulfur dioxide (SO_2) and gaseous sulfuric acid (H_2SO_4) across the disk of Venus. Our new radiative transfer model (RTM) has shown that the emission spectrum is especially sensitive to the abundances of these constituents at these wavelengths. The detection of these constituents is being accomplished by matching the computed emission from our RTM to the measured emission of Venus by the VLA. Our RTM incorporates the newly developed Ben Reuven formalism which provides a more accurate characterization of the microwave absorption of gaseous SO_2 (Suleiman et al., J. Geophys. Res. 101, 4623-4635, 1996). A description of the observation, visibility data, and images are presented. This work was supported by the NASA Planetary Atmospheres Program under grant NAGW-533.

  9. LANDSAT-4 horizon scanner performance evaluation

    NASA Technical Reports Server (NTRS)

    Bilanow, S.; Chen, L. C.; Davis, W. M.; Stanley, J. P.

    1984-01-01

    Representative data spans covering a little more than a year since the LANDSAT-4 launch were analyzed to evaluate the flight performance of the satellite's horizon scanner. High frequency noise was filtered out by 128-point averaging. The effects of Earth oblateness and spacecraft altitude variations are modeled, and residual systematic errors are analyzed. A model for the predicted radiance effects is compared with the flight data and deficiencies in the radiance effects modeling are noted. Correction coefficients are provided for a finite Fourier series representation of the systematic errors in the data. Analysis of the seasonal dependence of the coefficients indicates the effects of some early mission problems with the reference attitudes which were computed by the onboard computer using star trackers and gyro data. The effects of sun and moon interference, unexplained anomalies in the data, and sensor noise characteristics and their power spectrum are described. The variability of full orbit data averages is shown. Plots of the sensor data for all the available data spans are included.

  10. New geometries for black hole horizons

    NASA Astrophysics Data System (ADS)

    Armas, Jay; Blau, Matthias

    2015-07-01

    We construct several classes of worldvolume effective actions for black holes by integrating out spatial sections of the worldvolume geometry of asymptotically flat black branes. This provides a generalisation of the blackfold approach for higher-dimensional black holes and yields a map between different effective theories, which we exploit by obtaining new hydrodynamic and elastic transport coefficients via simple integrations. Using Euclidean minimal surfaces in order to decouple the fluid dynamics on different sections of the worldvolume, we obtain local effective theories for ultraspinning Myers-Perry branes and helicoidal black branes, described in terms of a stress-energy tensor, particle currents and non-trivial boost vectors. We then study in detail and present novel compact and non-compact geometries for black hole horizons in higher-dimensional asymptotically flat space-time. These include doubly-spinning black rings, black helicoids and helicoidal p-branes as well as helicoidal black rings and helicoidal black tori in D ≥ 6.

  11. Polarimetric VLBI with the Event Horizon Telescope

    NASA Astrophysics Data System (ADS)

    Fish, Vincent L.; Doeleman, S.; Marrone, D. P.; Lu, R.; Wardle, J. F.; EHT Collaboration

    2013-01-01

    The Event Horizon Telescope is a collaboration to observe the innermost accretion and outflow regions around supermassive black holes with an array of millimeter-wavelength telescopes. EHT observations have detected emission on scales of tens of microarcseconds around the black holes in the center of the Milky Way and M87. Non-polarimetric measurements have successfully been used to identify and model the Schwarzschild-radius-scale emission around these sources as well as to identify previously unresolvable structures in more distant AGNs and blazars, but new polarimetric data can provide additional information on the magnetic field strength and geometry in the jet launch and collimation region. Recent full-polarization VLBI observations with the EHT have detected polarized 1.3 mm emission arising on extremely small angular scales in a variety of extragalactic sources. We report on the results of these detections and detail the prospects for precision polarimetry thanks to the substantial EHT sensitivity improvements that will be realized over the next few years.

  12. New Developments with the Event Horizon Telescope

    NASA Astrophysics Data System (ADS)

    Fish, Vincent L.; Doeleman, S.; Krichbaum, T.; Zensus, A.; Event Horizon Telescope Collaboration

    2014-01-01

    The Event Horizon Telescope is an international collaboration to observe nearby supermassive black holes with millimeter-wavelength very long baseline interferometry in order to probe the region of the black hole shadow. Previous observations have placed strong constraints on the morphology of the emitting region around Sagittarius A* and the supermassive black hole in the center of M87, resulting in greater insight into the processes of accretion and outflow around black holes. Substantial advances in data quality have been made in the most recent March 2013 observations. Linear polarization has been clearly detected toward a variety of sources on angular scales of tens to hundreds of microarcseconds. Interhemispheric fringes, both North-South and East-West, were obtained, providing the best EHT baseline coverage to date. Technical progress on other stations that may participate in the 1.3 mm VLBI array, including a successful 3 mm VLBI experiment with the Large Millimeter Telescope and continued development of the ALMA beamformer, will soon increase the array sensitivity and baseline coverage, permitting imaging of black holes for the first time.

  13. Possible New Horizons Fundamental Contribution to Cosmology

    NASA Astrophysics Data System (ADS)

    Conn Henry, Richard; Murthy, Jayant

    2016-01-01

    The New Horizons (NH) spacecraft (S. Alan Stern, PI) is now past Pluto, and in our poster we explore the possibility of making observations, using the NH P-Alice ultraviolet spectrometer, of the cosmic diffuse ultraviolet background radiation, particularily at high northern and southern Galactic latitudes. In the paper, "The Mystery of the Cosmic Diffuse Ultraviolet Background Radiation," by Richard Conn Henry, Jayant Murthy, James Overduin, Joshua Tyler, ApJ, 798:14 (25pp), 2015 January 1, we demonstrated the existence of a second component of the diffuse far ultraviolet background radiation beyond that provided by dust-scattered starlight. The critical question is, does that second component (of unknown origin) extend shortward of the Lyman limit of 912 Å? If it does, then it seems likely that we have discovered the source of the reionization of the Universe that occurred some time after recombination. As things stand at the moment, there is no known source that has been demonstrated to be capable of performing the reionization: reionization that clearly did occur. Our current understanding of P-Alice suggests that it may well be capable of demonstrating the presence (or absence) of such ionizing cosmic diffuse radiation. At low Galactic latitudes, all such radiation would be totally erased by the presence, in large quantities, of interstellar neutral hydrogen; this will allow us to test the reality of any such flux that we may discover at higher Galactic latitudes.

  14. Reverse bias voltage testing of 8 cm x 8cm silicon solar cells

    NASA Technical Reports Server (NTRS)

    Woike, T.; Stotlar, S.; Lungu, C.

    1991-01-01

    A study is described of the reverse I-V characteristics of the largest space qualified silicon solar cells currently available (8 x 8 cm) and of reverse bias voltage (RBV) testing performed on these cells. This study includes production grade cells, both with and without cover glass. These cells span the typical output range seen in production. Initial characteristics of these cells are measured at both 28 and 60 C. These measurements show weak correlation between cell output and reverse characteristics. Analysis is presented to determine the proper conditions for RBV stress to simulate shadowing effects on a particular array design. After performing the RBV stress the characteristics of the stressed cells are remeasured. The degradation in cell performance is highly variable which exacerbates cell mismatching over time. The effect of this degradation on array lifetime is also discussed. Generalization of these results to other array configurations is also presented.

  15. Chrysanthemum CmNAR2 interacts with CmNRT2 in the control of nitrate uptake

    PubMed Central

    Gu, Chunsun; Zhang, Xiaoxue; Jiang, Jiafu; Guan, Zhiyong; Zhao, Shuang; Fang, Weimin; Liao, Yuan; Chen, Sumei; Chen, Fadi

    2014-01-01

    Nitrate transporters are an important component of plant growth and development. Chrysanthemum morifolium is an important ornamental species, for which a sufficient supply of nitrogenous fertilizer is required to maintain economic yields. In this study, the full-length cDNA of the nitrate transporter genes CmNRT2 and CmNAR2 were isolated. CmNRT2 transcript accumulation was inducible by both nitrate and ammonium, but the latter ion down-regulated the transcript accumulation of CmNAR2. CmNRT2 might be a plasma membrane localized protein, while CmNAR2 was distributed throughout the cell. CmNAR2 was shown to interact with CmNRT2 by in vitro and in vivo assays. Arabidopsis thaliana plants heterologously expressing CmNRT2 showed an increased rate of nitrate influx, while this trait was unaltered in plants expressing CmNAR2. Double transformants (CmNRT2 plus CmNAR2) exhibited an enhanced rate of nitrate influx into the root. Our data indicated that the interaction of CmNAR2 with CmNRT2 contributed to the uptake of nitrate. PMID:25060485

  16. Beyond the event horizon or altogether without it?

    NASA Astrophysics Data System (ADS)

    Lobanov, Andrei

    2017-03-01

    Millimetre-wavelength interferometry and gravitational-wave detectors currently provide the most stringent tests for the existence of cosmic black holes. Complementary measurements of magnetic fields near their event horizon would be decisive.

  17. The absence of horizon in black-hole formation

    NASA Astrophysics Data System (ADS)

    Ho, Pei-Ming

    2016-08-01

    With the back-reaction of Hawking radiation taken into consideration, the work of Kawai, Matsuo and Yokokura [1] has shown that, under a few assumptions, the collapse of matter does not lead to event horizon nor apparent horizon. In this paper, we relax their assumptions and elaborate on the space-time geometry of a generic collapsing body with spherical symmetry. The geometry outside the collapsing sphere is found to be approximated by the geometry outside the white-hole horizon, hence the collapsing matter remains outside the Schwarzschild radius. As particles in Hawking radiation are created in the vicinity of the collapsing matter, the information loss paradox is alleviated. Assuming that the collapsing body evaporates within finite time, there is no event horizon.

  18. Complementary and Alternative Medicine (CAM): Expanding Horizons of Health Care

    MedlinePlus

    ... Past Issues Special Section CAM Expanding Horizons of Health Care Past Issues / Winter 2009 Table of Contents For ... and why it is important to tell your health care providers about your use of CAM. We hope ...

  19. Hints of quantum gravity from the horizon fluid

    NASA Astrophysics Data System (ADS)

    Cropp, Bethan; Bhattacharya, Swastik; Shankaranarayanan, S.

    2017-01-01

    For many years, researchers have tried to glean hints about quantum gravity from black hole thermodynamics. However, black hole thermodynamics suffers from the problem of universality—at leading order, several approaches with different microscopic degrees of freedom lead to Bekenstein-Hawking entropy. We attempt to bypass this issue by using a minimal statistical mechanical model for the horizon fluid based on the Damour-Navier-Stokes (DNS) equation. For stationary asymptotically flat black hole spacetimes in general relativity, we show explicitly that, at equilibrium, the entropy of the horizon fluid is the Bekenstein-Hawking entropy. Further, we show that, for the bulk viscosity of the fluctuations of the horizon fluid to be identical to Damour, a confinement scale exists for these fluctuations, implying quantization of the horizon area. The implications and possible mechanisms from the fluid point of view are discussed.

  20. Deepwater Horizon – BP Gulf of Mexico Oil Spill

    EPA Pesticide Factsheets

    This webpage provides information and materials on EPA’s enforcement response to the Deepwater Horizon Oil Spill, including settlements with some of the defendants, as well as links to other related websites for additional information.

  1. Einstein–Weyl spaces and near-horizon geometry

    NASA Astrophysics Data System (ADS)

    Dunajski, Maciej; Gutowski, Jan; Sabra, Wafic

    2017-02-01

    We show that a class of solutions of minimal supergravity in five dimensions is given by lifts of three-dimensional Einstein–Weyl structures of hyper-CR type. We characterise this class as most general near-horizon limits of supersymmetric solutions to the five-dimensional theory. In particular we deduce that a compact spatial section of a horizon can only be a Berger sphere, a product metric on {{S}1}× {{S}2} or a flat three-torus. We then consider the problem of reconstructing all supersymmetric solutions from a given near-horizon geometry. By exploiting the ellipticity of the linearised field equations we demonstrate that the moduli space of transverse infinitesimal deformations of a near-horizon geometry is finite-dimensional.

  2. Horizon Based Orientation Estimation for Planetary Surface Navigation

    NASA Technical Reports Server (NTRS)

    Bouyssounouse, X.; Nefian, A. V.; Deans, M.; Thomas, A.; Edwards, L.; Fong, T.

    2016-01-01

    Planetary rovers navigate in extreme environments for which a Global Positioning System (GPS) is unavailable, maps are restricted to relatively low resolution provided by orbital imagery, and compass information is often lacking due to weak or not existent magnetic fields. However, an accurate rover localization is particularly important to achieve the mission success by reaching the science targets, avoiding negative obstacles visible only in orbital maps, and maintaining good communication connections with ground. This paper describes a horizon solution for precise rover orientation estimation. The detected horizon in imagery provided by the on board navigation cameras is matched with the horizon rendered over the existing terrain model. The set of rotation parameters (roll, pitch yaw) that minimize the cost function between the two horizon curves corresponds to the rover estimated pose.

  3. Universal properties of the near-horizon optical geometry

    SciTech Connect

    Gibbons, G. W.; Warnick, C. M.

    2009-03-15

    Making use of the fact that the optical geometry near a static nondegenerate Killing horizon is asymptotically hyperbolic, we investigate some universal features of black-hole horizons. Applying the Gauss-Bonnet theorem allows us to establish some general properties of gravitational lensing, valid for all black holes. Hyperbolic geometry allows us to find rates for the loss of scalar, vector, and fermionic ''hair'' as objects fall quasistatically towards the horizon, extending previous results for Schwarzschild to all static Killing horizons. In the process we find the Lienard-Wiechert potential for hyperbolic space and calculate the force between electrons mediated by neutrinos, extending the flat space result of Feinberg and Sucher. We further demonstrate how these techniques allow us to derive the exact Copson-Linet potential due to a point charge in a Schwarzschild background in a simple fashion.

  4. Note on electrical and thermodynamic properties of isolated horizons

    NASA Astrophysics Data System (ADS)

    Chen, Gerui; Wu, Xiaoning; Gao, Sijie

    2015-03-01

    The electrical laws and Carnot cycle of isolated horizons (IH) are investigated in this paper. We establish Ohm's law and Joule's law of isolated horizons and find that the conceptual picture of black holes (membrane paradigm) can also apply to this kind of quasilocal black holes. We also investigate the geometrical properties near nonrotating IHs and find that under the first-order approximation of r , there exist a Killing vector ∂∂u/ and a Hamiltonian conjugate to it, so this vector can be thought to be a physical observer. We calculate the energy as measured at infinity of a particle at rest outside a nonrotating IH, and we use this result to construct a reversible Carnot cycle with the isolated horizon as a cold reservoir, which confirms the thermodynamic nature of isolated horizons.

  5. Supertranslations and Superrotations at the Black Hole Horizon.

    PubMed

    Donnay, Laura; Giribet, Gaston; González, Hernán A; Pino, Miguel

    2016-03-04

    We show that the asymptotic symmetries close to nonextremal black hole horizons are generated by an extension of supertranslations. This group is generated by a semidirect sum of Virasoro and Abelian currents. The charges associated with the asymptotic Killing symmetries satisfy the same algebra. When considering the special case of a stationary black hole, the zero mode charges correspond to the angular momentum and the entropy at the horizon.

  6. Evaporating dynamical horizon with the Hawking effect in Vaidya spacetime

    SciTech Connect

    Sawayama, Shintaro

    2006-03-15

    We consider how the mass of the black hole decreases due to the Hawking radiation in the Vaidya spacetime, using the concept of the dynamical horizon equation, proposed by Ashtekar and Krishnan. Using the formula for the change of the dynamical horizon, we derive an equation for the mass incorporating the Hawking radiation. It is shown that the final state is the Minkowski spacetime in our particular model.

  7. Waste Sampling Data for BP Spill/Deepwater Horizon

    EPA Pesticide Factsheets

    The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

  8. Air Sampling Data for BP Spill/Deepwater Horizon

    EPA Pesticide Factsheets

    The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

  9. Air Monitoring Data for BP Spill/Deepwater Horizon

    EPA Pesticide Factsheets

    The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

  10. Surface Water Sampling Data for BP Spill/Deepwater Horizon

    EPA Pesticide Factsheets

    The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

  11. Sediment Sampling Data for BP Spill/Deepwater Horizon

    EPA Pesticide Factsheets

    The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

  12. Water Sampling Data for BP Spill/Deepwater Horizon

    EPA Pesticide Factsheets

    The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

  13. A horizon scan of global conservation issues for 2010.

    PubMed

    Sutherland, William J; Clout, Mick; Côté, Isabelle M; Daszak, Peter; Depledge, Michael H; Fellman, Liz; Fleishman, Erica; Garthwaite, Rachel; Gibbons, David W; De Lurio, Jennifer; Impey, Andrew J; Lickorish, Fiona; Lindenmayer, David; Madgwick, Jane; Margerison, Ceri; Maynard, Trevor; Peck, Lloyd S; Pretty, Jules; Prior, Stephanie; Redford, Kent H; Scharlemann, Jörn P W; Spalding, Mark; Watkinson, Andrew R

    2010-01-01

    Horizon scanning identifies emerging issues in a given field sufficiently early to conduct research to inform policy and practice. Our group of horizon scanners, including academics and researchers, convened to identify fifteen nascent issues that could affect the conservation of biological diversity. These include the impacts of and potential human responses to climate change, novel biological and digital technologies, novel pollutants and invasive species. We expect to repeat this process and collation annually.

  14. A horizon scan of global conservation issues for 2015.

    PubMed

    Sutherland, William J; Clout, Mick; Depledge, Michael; Dicks, Lynn V; Dinsdale, Jason; Entwistle, Abigail C; Fleishman, Erica; Gibbons, David W; Keim, Brandon; Lickorish, Fiona A; Monk, Kathryn A; Ockendon, Nancy; Peck, Lloyd S; Pretty, Jules; Rockström, Johan; Spalding, Mark D; Tonneijck, Femke H; Wintle, Bonnie C

    2015-01-01

    This paper presents the results of our sixth annual horizon scan, which aims to identify phenomena that may have substantial effects on the global environment, but are not widely known or well understood. A group of professional horizon scanners, researchers, practitioners, and a journalist identified 15 topics via an iterative, Delphi-like process. The topics include a novel class of insecticide compounds, legalisation of recreational drugs, and the emergence of a new ecosystem associated with ice retreat in the Antarctic.

  15. Optical Navigation Preparations for New Horizons Pluto Flyby

    NASA Technical Reports Server (NTRS)

    Owen, William M., Jr.; Dumont, Philip J.; Jackman, Coralie D.

    2012-01-01

    The New Horizons spacecraft will encounter Pluto and its satellites in July 2015. As was the case for the Voyager encounters with Jupiter, Saturn, Uranus and Neptune, mission success will depend heavily on accurate spacecraft navigation, and accurate navigation will be impossible without the use of pictures of the Pluto system taken by the onboard cameras. We describe the preparations made by the New Horizons optical navigators: picture planning, image processing algorithms, software development and testing, and results from in-flight imaging.

  16. Constrained field theories on spherically symmetric spacetimes with horizons

    NASA Astrophysics Data System (ADS)

    Fernandes, Karan; Lahiri, Amitabha; Ghosh, Suman

    2017-02-01

    We apply the Dirac-Bergmann algorithm for the analysis of constraints to gauge theories defined on spherically symmetric black hole backgrounds. We find that the constraints for a given theory are modified on such spacetimes through the presence of additional contributions from the horizon. As a concrete example, we consider the Maxwell field on a black hole background, and determine the role of the horizon contributions on the dynamics of the theory.

  17. A horizon scan of global conservation issues for 2013.

    PubMed

    Sutherland, William J; Bardsley, Sarah; Clout, Mick; Depledge, Michael H; Dicks, Lynn V; Fellman, Liz; Fleishman, Erica; Gibbons, David W; Keim, Brandon; Lickorish, Fiona; Margerison, Ceri; Monk, Kathryn A; Norris, Kenneth; Peck, Lloyd S; Prior, Stephanie V; Scharlemann, Jörn P W; Spalding, Mark D; Watkinson, Andrew R

    2013-01-01

    This paper presents the findings of our fourth annual horizon-scanning exercise, which aims to identify topics that increasingly may affect conservation of biological diversity. The 15 issues were identified via an iterative, transferable process by a team of professional horizon scanners, researchers, practitioners, and a journalist. The 15 topics include the commercial use of antimicrobial peptides, thorium-fuelled nuclear power, and undersea oil production.

  18. Black hole entropy from conformal symmetry on the horizon

    NASA Astrophysics Data System (ADS)

    Carlip, Steven

    2017-01-01

    The idea that black hole entropy might be governed by a conformal symmetry is an old one, but until now most efforts have focused on either asymptotic symmetries or symmetries on a ``stretched horizon. For two-dimensional dilaton gravity, I show the existence of a well-behaved conformal symmetry that is on the horizon, with a central charge that correctly determines the black hole entropy. Supported by Department of Energy grant DE-FG02-91ER40674.

  19. Reflection and transmission at the apparent horizon during gravitational collapse

    SciTech Connect

    Vaz, Cenalo; Wijewardhana, L. C. R.

    2010-10-15

    We examine the wave functionals describing the collapse of a self-gravitating dustball in an exact quantization of the gravity-dust system. We show that ingoing (collapsing) dust shell modes outside the apparent horizon must necessarily be accompanied by outgoing modes inside the apparent horizon, whose amplitude is suppressed by the square root of the Boltzmann factor at the Hawking temperature. Likewise, ingoing modes in the interior must be accompanied by outgoing modes in the exterior, again with an amplitude suppressed by the same factor. A suitable superposition of the two solutions is necessary to conserve the dust probability flux across the apparent horizon; thus, each region contains both ingoing and outgoing dust modes. If one restricts oneself to considering only the modes outside the apparent horizon then one should think of the apparent horizon as a partial reflector, the probability for a shell to reflect being given by the Boltzmann factor at the Hawking temperature determined by the mass contained within it. However, if one considers the entire wave function, the outgoing wave in the exterior is seen to be the transmission through the horizon of the interior outgoing wave that accompanies the collapsing shells. This transmission could allow information from the interior to be transferred to the exterior.

  20. Null infinity and extremal horizons in AdS-CFT

    NASA Astrophysics Data System (ADS)

    Hickling, Andrew; Lucietti, James; Wiseman, Toby

    2015-02-01

    We consider AdS gravity duals to CFT on background spacetimes with a null infinity. Null infinity on the conformal boundary may extend to an extremal horizon in the bulk. For example it does so for Poincaré-AdS, although does not for planar Schwarzschild-AdS. If null infinity does extend into an extremal horizon in the bulk, we show that the bulk near-horizon geometry is determined by the geometry of the boundary null infinity. Hence the ‘infra-red’ geometry of the bulk is fixed by the large scale behaviour of the CFT spacetime. In addition the boundary stress tensor must have a particular decay at null infinity. As an application, we argue that for CFT on asymptotically flat backgrounds, any static bulk dual containing an extremal horizon extending from the boundary null infinity, must have the near-horizon geometry of Poincaré-AdS. We also discuss a class of boundary null infinity that cannot extend to a bulk extremal horizon, although we give evidence that they can extend to an analogous null surface in the bulk which possesses an associated scale-invariant ‘near-geometry’.

  1. Rotating Killing horizons in generic F( R) gravity theories

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Sourav

    2016-10-01

    We discuss various properties of rotating Killing horizons in generic F( R) theories of gravity in dimension four for spacetimes endowed with two commuting Killing vector fields. Assuming there is no curvature singularity anywhere on or outside the horizon, we construct a suitable (3+1)-foliation. We show that similar to Einstein's gravity, we must have T_{ab}k^ak^b=0 on the Killing horizon, where k^a is a null geodesic tangent to the horizon. For axisymmetric spacetimes, the effective gravitational coupling ˜ F'^{-1}(R) should usually depend upon the polar coordinate and hence need not necessarily be a constant on the Killing horizon. We prove that the surface gravity of such a Killing horizon must be a constant, irrespective of whether F'(R) is a constant there or not. We next apply these results to investigate some further basic features. In particular, we show that any hairy solution for the real massive vector field in such theories is clearly ruled out, as long as the potential of the scalar field generated in the corresponding Einstein's frame is a positive definite quantity.

  2. LARGE PIEZOELECTRIC EFFECT IN LOW-TEMPERATURE-SINTERED LEAD-FREE (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 THICK FILMS

    NASA Astrophysics Data System (ADS)

    Feng, Zuyong; Shi, Dongqi; Dou, Shixue; Hu, Yihua; Tang, Xingui

    2012-09-01

    High-quality piezoelectric (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 thick films with dense and homogenous microstructures were fabricated at a low sintering temperature (900°C) using a CuBi2O4 sintering aid. The 10 μm thick film exhibited a high longitudinal piezoelectric constant d33,eff of 210 pC/N with estimated unconstrained d33 value of 560 pC/N very close to that in the corresponding bulks. Such excellent piezoelectric effect in the low-temperature sintered (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 thick films is comparable to the case of lead-based PZT thick films, and may be a promising application in lead-free microdevices such as piezoelectric microelectromechanical systems (MEMS).

  3. Strain-relaxation and critical thickness of epitaxial La1.85Sr0.15CuO4 films

    SciTech Connect

    Meyer, Tricia L; Jiang, Lu; Park, Sungkyun; Egami, Takeshi; Lee, Ho Nyung

    2015-12-08

    We report the thickness-dependent strain-relaxation behavior and the associated impacts upon the superconductivity in epitaxial La1.85Sr0.15CuO4 films grown on different substrates, which provide a range of strain. We have found that the critical thickness for the onset of superconductivity in La1.85Sr0.15CuO4 films is associated with the finite thickness effect and epitaxial strain. In particular, thin films with tensile strain greater than ~0.25% revealed no superconductivity. We attribute this phenomenon to the inherent formation of oxygen vacancies that can be minimized via strain relaxation.

  4. Generalized Robertson-Walker Space-Time Admitting Evolving Null Horizons Related to a Black Hole Event Horizon.

    PubMed

    Duggal, K L

    2016-01-01

    A new technique is used to study a family of time-dependent null horizons, called "Evolving Null Horizons" (ENHs), of generalized Robertson-Walker (GRW) space-time [Formula: see text] such that the metric [Formula: see text] satisfies a kinematic condition. This work is different from our early papers on the same issue where we used (1 + n)-splitting space-time but only some special subcases of GRW space-time have this formalism. Also, in contrast to previous work, we have proved that each member of ENHs is totally umbilical in [Formula: see text]. Finally, we show that there exists an ENH which is always a null horizon evolving into a black hole event horizon and suggest some open problems.

  5. The clustering of the SDSS main galaxy sample - II. Mock galaxy catalogues and a measurement of the growth of structure from redshift space distortions at z = 0.15

    NASA Astrophysics Data System (ADS)

    Howlett, Cullan; Ross, Ashley J.; Samushia, Lado; Percival, Will J.; Manera, Marc

    2015-05-01

    We measure redshift space distortions in the two-point correlation function of a sample of 63 163 spectroscopically identified galaxies with z < 0.2, an epoch where there are currently only limited measurements, from the Sloan Digital Sky Survey Data Release 7 main galaxy sample (MGS). Our sample, which we denote MGS, covers 6813 deg2 with an effective redshift zeff = 0.15 and is described in our companion paper (Paper I), which concentrates on baryon acoustic oscillation (BAO) measurements. In order to validate the fitting methods used in both papers, and derive errors, we create and analyse 1000 mock catalogues using a new algorithm called PICOLA to generate accurate dark matter fields. Haloes are then selected using a friends-of-friends algorithm, and populated with galaxies using a halo-occupation distribution fitted to the data. Using errors derived from these mocks, we fit a model to the monopole and quadrupole moments of the MGS correlation function. If we assume no Alcock-Paczynski (AP) effect (valid at z = 0.15 for any smooth model of the expansion history), we measure the amplitude of the velocity field, fσ8, at z = 0.15 to be 0.49_{-0.14}^{+0.15}. We also measure fσ8 including the AP effect. This latter measurement can be freely combined with recent cosmic microwave background results to constrain the growth index of fluctuations, γ. Assuming a background Λ cold dark matter cosmology and combining with current BAO data, we find γ = 0.64 ± 0.09, which is consistent with the prediction of general relativity (γ ≈ 0.55), though with a slight preference for higher γ and hence models with weaker gravitational interactions.

  6. Fine-sized LiNi 0.8Co 0.15Mn 0.05O 2 cathode powders prepared by combined process of gas-phase reaction and solid-state reaction methods

    NASA Astrophysics Data System (ADS)

    Ju, Seo Hee; Kang, Yun Chan

    The Ni-rich precursor powders with spherical shape and filled morphologies were prepared by spray pyrolysis from the spray solution with citric acid, ethylene glycol and a drying control chemical additive. The precursor powders with controlled morphologies formed the LiNi 0.8Co 0.15Mn 0.05O 2 cathode powders with spherical shape and fine size by solid-state reaction with lithium hydroxide. However, the cathode powders prepared from the spray solution without additives had irregular morphologies and were large in size. The precursor powders with hollow and porous morphologies formed cathode powders with irregular and aggregated morphologies. The composition ratios of the nickel, cobalt and manganese components were maintained in the as-prepared, precursor and cathode powders. The initial discharge capacity of the LiNi 0.8Co 0.15Mn 0.05O 2 cathode powders with spherical shape and fine size tested at a temperature of 55 °C under a constant current density of 0.5 C was 215 mAh g -1. The discharge capacity of the LiNi 0.8Co 0.15Mn 0.05O 2 cathode powders decreased to 81% of the initial value after 30 cycles.

  7. Synthesis cathode material LiNi0.80Co0.15Al0.05O2 with two step solid-state method under air stream

    NASA Astrophysics Data System (ADS)

    Xia, Shubiao; Zhang, Yingjie; Dong, Peng; Zhang, Yannan

    2014-01-01

    A facile generic strategy of solid-state reaction under air atmosphere is employed to prepare LiNi0.8Co0.15Al0.05O2 layer structure micro-sphere as cathodes for Li-ion batteries. The impurity phase has been eliminated wholly without changing the R-3m space group of LiNi0.8Co0.15Al0.05O2. The electrochemical performance of LiNi0.8Co0.15Al0.05O2 cathodes depend on the sintering step, temperature, particle size and uniformity. The sample pre-sintered at 540 °C for 12 h and then sintered at 720 °C for 28 h exhibits the best electrochemical performance, which delivers a reversible capacity of 180.4, 165.8, 154.7 and 135.6 mAhg-1 at 0.2 C, 1 C, 2 C and 5 C, respectively. The capacity retention keeps over 87% after 76 cycles at 1 C. This method is simple, cheap and mass-productive, and thus suitable to large scale production of NCA cathodes directly used for lithium ion batteries.

  8. Anisotropy and Vortex Pinning of Heavy Ion irradiated SmFeAsO0.8F0.15 and BaFe2(As1-xPx)2 Crystals

    NASA Astrophysics Data System (ADS)

    Kwok, Wai-Kwong; Fang, Lei; Chaparro, Carlos; Jia, Ying; Welp, Ulrich; Koshelev, Alexei; Xu, Shaofei; Crabtree, George; Karpinski, Janusz

    2012-02-01

    We report specific heat and magnetization measurements on SmFeAsO0.8F0.15 and BaFe2(As1-xPx)2 single crystals irradiated with high energy heavy ions of 1.4GeV Pb to dose matching fields up to 4 Tesla. We find a nearly one half reduction in the superconducting anisotropy and doubling of the irreversibility field in SmFeAsO0.8F0.15 after irradiation and virtually no change in the zero-field superconducting transition temperature. In both SmFeAsO0.8F0.15 and BaFe2(As1-xPx)2 crystals, we find a substantial increase in the critical current determined from SQUID and micro-Hall probe magnetization measurements. Pinning force analysis on proton and heavy ion irradiated pristine overdoped BaFe2(As1-xPx)2 crystals indicates presence of induced δTc-type pinning defects in these samples.

  9. Influence of nickel doping on oxygen-ionic conductivity of the n = 1 Ruddlesden-Popper Phases La1.85Ca0.15(Cu1-xNix)O4-δ (δ = 0.0905)

    NASA Astrophysics Data System (ADS)

    Midouni, Adnene; Houchati, Mohamed Ikbal; Othman, Walid Belhaj; Chniba-Boudjada, Nassira; Ceretti, Monica; Paulus, Werner; Jaouadi, Mouna; Hamzaoui, Ahmed Hichem

    2016-08-01

    The results of the synthesis and characterization of the optimally doped La1.85Ca0.15(Cu1-xNix)O4-δ solid solution with x = 0, 0.1, 0.2 and 0.3 are reported. The versatility of these La1.85Ca0.15(Cu1-xNix)O4-δ materials is explained on the basis of structural features and the ability to accommodate oxygen nonstoichiometry. According to powder X-ray and neutron diffraction data, La1.85Ca0.15(Cu1-xNix)O4-δ adopts the tetragonal structure with oxygen vacancies occurring preferentially at the Oap sites within the {(La/Ca)O} layers of the perovskite blocks and the oxygen deviation from stoichiometry δ was found to be δ=0.0905(6). The bulk conductivity indicated an Arrhenius-type thermally activated process and oxygen vacancies are the possible ionic charge carriers at T=270 °C. An increase of the conductivity was detected when Ni was introduced. With nickel ratio variation, a strong correlation was observed between the Cu(Ni)-Oap apical bond length variation and the conductivity variation through controlling the O2- ion migration.

  10. Decoupled scenario between the conductive carriers and the ferromagnetism in epitaxial Zn{sub 0.85−x}Mg{sub x}Co{sub 0.15}O thin films

    SciTech Connect

    Zhu, Dapeng; Liu, Guolei; Tian, Yufeng E-mail: shishenyan@sdu.edu.cn; Yan, Shishen E-mail: shishenyan@sdu.edu.cn; Cai, Li; Fu, Maoxiang; Zhang, Jie; Zhang, Kun; Ye, Shengtao; Li, Huanhuan; Hu, Shujun; Chen, Yanxue; Kang, Shishou; Dai, Youyong; Mei, Liangmo; Cao, Qiang

    2014-08-18

    A series of Zn{sub 0.85−x}Mg{sub x}Co{sub 0.15}O (0 ≤ x ≤ 0.3) thin films were fabricated by plasma-assisted molecular-beam epitaxy to investigate the correlation between the electrical transport properties and the ferromagnetism. It is observed that the saturation magnetization remains almost unchanged even though the resistivity of the Zn{sub 0.85−x}Mg{sub x}Co{sub 0.15}O films dramatically increases more than 6 orders with increasing Mg concentration. Moreover, the absence of detectable anomalous Hall effects and very small magnetoresistance in the films reveal the absence of spin polarization of conductive carriers and very weak spin-dependent scattering or tunneling processes. All these results suggest that the conductive carriers are decoupled with the ferromagnetism in the Zn{sub 0.85−x}Mg{sub x}Co{sub 0.15}O films.

  11. Electronic structural studies on the improved thermal stability of Li(Ni0.8Co0.15Al0.05)O2 by ZrO2 coating for lithium ion batteries

    DOE PAGES

    Kim, Ji-Young; Kim, Sang Hoon; Kim, Dong Hyun; ...

    2017-03-21

    The electronic structures of bare and ZrO2-coated Li(Ni0.8Co0.15Al0.05)O2 electrode systems were investigated using a combination of time-resolved X-ray diffraction and soft X-ray absorption spectroscopy (XAS) techniques. The ZrO2 coating on the surface of Li(Ni0.8Co0.15Al0.05)O2 was effective in elevating the onset temperature of the dissociation of charged Li0.33(Ni0.8Co0.15Al0.05)O2, which will enhance the safety of Li-ion cells. Lastly, soft XAS spectra of the Ni LII,III-edge in the partial electron yield mode were obtained, which showed that the enhanced electrochemical properties and thermal stability of the cathode materials by ZrO2 coating can be attributed to the suppression of unwanted Ni oxidation state changesmore » at the surface.« less

  12. Black holes or firewalls: A theory of horizons

    NASA Astrophysics Data System (ADS)

    Nomura, Yasunori; Varela, Jaime; Weinberg, Sean J.

    2013-10-01

    We present a quantum theory of black hole (and other) horizons, in which the standard assumptions of complementarity are preserved without contradicting information theoretic considerations. After the scrambling time, the quantum mechanical structure of a black hole becomes that of an eternal black hole at the microscopic level. In particular, the stretched horizon degrees of freedom and the states entangled with them can be mapped into the near-horizon modes in the two exterior regions of an eternal black hole, whose mass is taken to be that of the evolving black hole at each moment. Salient features arising from this picture include (i) the number of degrees of freedom needed to describe a black hole is eA/2lP2, where A is the area of the horizon; (ii) black hole states having smooth horizons, however, span only an eA/4lP2-dimensional subspace of the relevant eA/2lP2-dimensional Hilbert space; (iii) internal dynamics of the horizon is such that an infalling observer finds a smooth horizon with a probability of 1 if a state stays in this subspace. We identify the structure of local operators responsible for describing semiclassical physics in the exterior and interior spacetime regions and show that this structure avoids the arguments for firewalls—the horizon can keep being smooth throughout the evolution. We discuss the fate of infalling observers under various circumstances, especially when the observers manipulate degrees of freedom before entering the horizon, and we find that an observer can never see a firewall by making a measurement on early Hawking radiation. We also consider the presented framework from the viewpoint of an infalling reference frame and argue that Minkowski-like vacua are not unique. In particular, the number of true Minkowski vacua is infinite, although the label discriminating these vacua cannot be accessed in usual nongravitational quantum field theory. An application of the framework to de Sitter horizons is also discussed.

  13. Io’s active volcanoes during the New Horizons era: Insights from New Horizons imaging

    NASA Astrophysics Data System (ADS)

    Rathbun, J. A.; Spencer, J. R.; Lopes, R. M.; Howell, R. R.

    2014-03-01

    In February 2007, the New Horizons spacecraft flew by the Jupiter system, obtaining images of Io, the most volcanically active body in the Solar System. The Multicolor Visible Imaging Camera (MVIC), a four-color (visible to near infrared) camera, obtained 17 sets of images. The Long-Range Reconnaissance Imager (LORRI), a high-resolution panchromatic camera, obtained 190 images, including many of Io eclipsed by Jupiter. We present a complete view of the discrete point-like emission sources in all images obtained by these two instruments. We located 54 emission sources and determined their brightnesses. These observations, the first that observed individual Ionian volcanoes on short timescales of seconds to minutes, demonstrate that the volcanoes have stable brightnesses on these timescales. The active volcanoes Tvashtar (63N, 124W) and E. Girru (22N, 245W) were observed by both LORRI and MVIC, both in the near-infrared (NIR) and methane (CH4) filters. Tvashtar was additionally observed in the red filter, which allowed us to calculate a color temperature of approximately 1200 K. We found that, with some exceptions, most of the volcanoes frequently active during the Galileo era continued to be active during the New Horizons flyby. We found that none of the seven volcanoes observed by New Horizons multiple times over short timescales showed substantial changes on the order of seconds and only one, E. Girru exhibited substantial variation over minutes to days, increasing by 25% in just over an hour and decreasing by a factor of 4 over 6 days. Observations of Tvashtar are consistent with a current eruption similar to previously observed eruptions and are more consistent with the thermal emission of a lava flow than the fire fountains inferred from the November 1999 observations. These data also present new puzzles regarding Ionian volcanism. Since there is no associated surface change or low albedo feature that could be identified nearby, the source of the emission from

  14. Porewater geochemistry of inland Acid sulfate soils with sulfuric horizons following postdrought reflooding with freshwater.

    PubMed

    Creeper, Nathan L; Shand, Paul; Hicks, Warren; Fitzpatrick, Rob W

    2015-05-01

    Following the break of a severe drought in the Murray-Darling Basin, rising water levels restored subaqueous conditions to dried inland acid sulfate soils with sulfuric horizons (pH <3.5). Equilibrium dialysis membrane samplers were used to investigate in situ changes to soil acidity and abundance of metals and metalloids following the first 24 mo of restored subaqueous conditions. The rewetted sulfuric horizons remained severely acidified (pH ∼4) or had retained acidity with jarosite visibly present after 5 mo of continuous subaqueous conditions. A further 19 mo of subaqueous conditions resulted in only small additional increases in pH (∼0.5-1 pH units), with the largest increases occurring within the uppermost 10 cm of the soil profile. Substantial decreases in concentrations of some metal(loid)s were observed with time most likely owing to lower solubility and sorption as a consequence of the increase in pH. In deeper parts of the profiles, porewater remained strongly buffered at low pH values (pH <4.5) and experienced little progression toward anoxic circumneutral pH conditions over the 24 mo of subaqueous conditions. It is proposed that low pH conditions inhibited the activity of SO-reducing bacteria and, in turn, the in situ generation of alkalinity through pyrite production. The limited supply of alkalinity in freshwater systems and the initial highly buffered low pH conditions were also thought to be slowing recovery. The timescales involved for a sulfuric horizon rewetted by a freshwater body to recover from acidic conditions could therefore be in the order of several years.

  15. RESOLVING THE INNER JET STRUCTURE OF 1924-292 WITH THE EVENT HORIZON TELESCOPE

    SciTech Connect

    Lu Rusen; Fish, Vincent L.; Doeleman, Sheperd S.; Weintroub, Jonathan; Moran, James M.; Primiani, Rurik; Young, Ken H.; Bower, Geoffrey C.; Plambeck, Richard; Wright, Melvyn; Freund, Robert; Marrone, Daniel P.; Friberg, Per; Tilanus, Remo P. J.; Ho, Paul T. P.; Inoue, Makoto; Honma, Mareki; Oyama, Tomoaki; Krichbaum, Thomas P.; Shen Zhiqiang; and others

    2012-09-20

    We present the first 1.3 mm (230 GHz) very long baseline interferometry model image of an active galactic nucleus (AGN) jet using closure phase techniques with a four-element array. The model image of the quasar 1924-292 was obtained with four telescopes at three observatories: the James Clerk Maxwell Telescope on Mauna Kea in Hawaii, the Arizona Radio Observatory's Submillimeter Telescope in Arizona, and two telescopes of the Combined Array for Research in Millimeter-wave Astronomy in California in 2009 April. With the greatly improved resolution compared with previous observations and robust closure phase measurement, the inner jet structure of 1924-292 was spatially resolved. The inner jet extends to the northwest along a position angle of -53 Degree-Sign at a distance of 0.38 mas from the tentatively identified core, in agreement with the inner jet structure inferred from lower frequencies, and making a position angle difference of {approx}80 Degree-Sign with respect to the centimeter jet. The size of the compact core is 0.15 pc with a brightness temperature of 1.2 Multiplication-Sign 10{sup 11} K. Compared with those measured at lower frequencies, the low brightness temperature may argue in favor of the decelerating jet model or particle-cascade models. The successful measurement of closure phase paves the way for imaging and time resolving Sgr A* and nearby AGNs with the Event Horizon Telescope.

  16. Genesis of petroduric and petrocalcic horizons in Latinamerica volcanic soils

    NASA Astrophysics Data System (ADS)

    Quantin, Paul

    2010-05-01

    Introduction. In Latinamerica, from Mexico to Chile, there are indurated volcanic soils horizons, named 'tepetate' in Mexico or cangahua in the Andes Mountains. Apart from original volcanic tuffs, these horizons were produced by pedogenesis: either through a former weathering of volcanic ash layers into fragic and later to petrocalcic horizons; or after a former soil formation through a second process of transformation from clayey volcanic soils to silicified petroduric horizons. This oral presentation will briefly deal with the formation of petroduric horizons in Mexico and petrocalcic horizon in Ecuador. Petroduric horizon genesis in Mexico. A soil climato-toposequence, near to Veracruz (Rossignol & Quantin, 1997), shows downwards an evolution from a ferralic Nitisol to a petroduric Durisol. A Durisol profile comports these successive horizons: at the top A and Eg, then columnar Btg-sim, laminar Bt-sim , prismatic Bsim, plinthite Cg, over andesite lava flow. Among its main features are especially recorded: clay mineralogy, microscopy and HRTEM. These data show: an increase in cristobalite at the expenses of 0.7 nm halloysite in Egsiltans, laminar Bt-sim, around or inside the columns or prisms of Btg-sim and Bsimhorizons. HRTEM (Elsass & al 2000) on ultra thin sections reveals an 'epigenesis' of clay sheets by amorphous silica, to form successively A-opal, Ct-opal and microcrystalline cristobalite. From these data and some groundwater chemical analyses, a scenario of duripan formation from a past clayey Nitisol is inferred: clay eluviation-illuviation process? alternate redoximorphy? clay degradation, Al leaching and Si accumulation, to form successively A-opal, Ct-opal and cristobalite. Petrocalcic horizon genesis in Ecuador. A soil climato-toposequence on pyroclastic flows, near to Bolivar in Ecuador (Quantin & Zebrowski, 1997), shows downwards the evolution from fragic-eutric-vitric Cambisols to petrocalcic-vitric Phaeozems, at the piedmont under semi

  17. Beyond the veil: Inner horizon instability and holography

    SciTech Connect

    Balasubramanian, Vijay; Levi, Thomas S.

    2004-11-15

    We show that scalar perturbations of the eternal, rotating Banados-Teitelboim-Zanelli (BTZ) black hole should lead to an instability of the inner (Cauchy) horizon, preserving strong cosmic censorship. Because of backscattering from the geometry, plane-wave modes have a divergent stress tensor at the event horizon, but suitable wave packets avoid this difficulty, and are dominated at late times by quasinormal behavior. The wave packets have cuts in the complexified coordinate plane that are controlled by requirements of continuity, single-valuedness, and positive energy. Due to a focusing effect, regular wave packets nevertheless have a divergent stress energy at the inner horizon, signaling an instability. We propose that this instability, which is localized behind the event horizon, is detected holographically as a breakdown in the semiclassical computation of dual conformal field theory (CFT) expectation values in which the analytic behavior of wave packets in the complexified coordinate plane plays an integral role. In the dual field theory, this is interpreted as an encoding of physics behind the horizon in the entanglement between otherwise independent CFTs.

  18. Dark energy in thermal equilibrium with the cosmological horizon?

    NASA Astrophysics Data System (ADS)

    Poitras, Vincent

    2014-03-01

    According to a generalization of black hole thermodynamics to a cosmological framework, it is possible to define a temperature for the cosmological horizon. The hypothesis of thermal equilibrium between the dark energy and the horizon has been considered by many authors. We find the restrictions imposed by this hypothesis on the energy transfer rate (Qi) between the cosmological fluids, assuming that the temperature of the horizon has the form T =b/2πR, where R is the radius of the horizon. We more specifically consider two types of dark energy: Chaplygin gas (CG) and dark energy with a constant equation of state parameter (wDE). In each case, we show that for a given radius R, there is a unique term Qde that is consistent with thermal equilibrium. We also consider the situation where, in addition to dark energy, other fluids (cold matter, radiation) are in thermal equilibrium with the horizon. We find that the interaction terms required for this will generally violate energy conservation (∑iQi=0).

  19. Universality of P - V criticality in horizon thermodynamics

    NASA Astrophysics Data System (ADS)

    Hansen, Devin; Kubizňák, David; Mann, Robert B.

    2017-01-01

    We study P - V criticality of black holes in Lovelock gravities in the context of horizon thermodynamics. The corresponding first law of horizon thermodynamics emerges as one of the Einstein-Lovelock equations and assumes the universal (independent of matter content) form δ E = T δ S - P δ V , where P is identified with the total pressure of all matter in the spacetime (including a cosmological constant Λ if present). We compare this approach to recent advances in extended phase space thermodynamics of asymptotically AdS black holes where the `standard' first law of black hole thermodynamics is extended to include a pressure-volume term, where the pressure is entirely due to the (variable) cosmological constant. We show that both approaches are quite different in interpretation. Provided there is sufficient non-linearity in the gravitational sector, we find that horizon thermodynamics admits the same interesting black hole phase behaviour seen in the extended case, such as a Hawking-Page transition, Van der Waals like behaviour, and the presence of a triple point. We also formulate the Smarr formula in horizon thermodynamics and discuss the interpretation of the quantity E appearing in the horizon first law.

  20. Fractal markets: Liquidity and investors on different time horizons

    NASA Astrophysics Data System (ADS)

    Li, Da-Ye; Nishimura, Yusaku; Men, Ming

    2014-08-01

    In this paper, we propose a new agent-based model to study the source of liquidity and the “emergent” phenomenon in financial market with fractal structure. The model rests on fractal market hypothesis and agents with different time horizons of investments. What is interesting is that though the agent-based model reveals that the interaction between these heterogeneous agents affects the stability and liquidity of the financial market the real world market lacks detailed data to bring it to light since it is difficult to identify and distinguish the investors with different time horizons in the empirical approach. results show that in a relatively short period of time fractal market provides liquidity from investors with different horizons and the market gains stability when the market structure changes from uniformity to diversification. In the real world the fractal structure with the finite of horizons can only stabilize the market within limits. With the finite maximum horizons, the greater diversity of the investors and the fractal structure will not necessarily bring more stability to the market which might come with greater fluctuation in large time scale.

  1. Beyond the veil: Inner horizon instability and holography

    NASA Astrophysics Data System (ADS)

    Balasubramanian, Vijay; Levi, Thomas S.

    2004-11-01

    We show that scalar perturbations of the eternal, rotating Banados-Teitelboim-Zanelli (BTZ) black hole should lead to an instability of the inner (Cauchy) horizon, preserving strong cosmic censorship. Because of backscattering from the geometry, plane-wave modes have a divergent stress tensor at the event horizon, but suitable wave packets avoid this difficulty, and are dominated at late times by quasinormal behavior. The wave packets have cuts in the complexified coordinate plane that are controlled by requirements of continuity, single-valuedness, and positive energy. Due to a focusing effect, regular wave packets nevertheless have a divergent stress energy at the inner horizon, signaling an instability. We propose that this instability, which is localized behind the event horizon, is detected holographically as a breakdown in the semiclassical computation of dual conformal field theory (CFT) expectation values in which the analytic behavior of wave packets in the complexified coordinate plane plays an integral role. In the dual field theory, this is interpreted as an encoding of physics behind the horizon in the entanglement between otherwise independent CFTs.

  2. Ferromanganese crusts from Necker Ridge, Horizon Guyot and S.P. Lee Guyot: geological considerations

    USGS Publications Warehouse

    Hein, James R.; Manheim, Frank T.; Schwab, William C.; Davis, Alice S.

    1985-01-01

    Ferromanganese-encrusted rocks were recovered in every dredge and are thickest on Necker Ridge. Crust thicknesses average about 2.5, 1.5, and 0.8 cm for Necker, Horizon, and S.P. Lee, respectively. Crusts range from smooth or porous surfaces to knobby and botryoidal. The entire crust is laminated, however, two distinct layers commonly exist, separated by a paper-thin layer of phosphorite. The dominant mineral of all crusts is vernadite (δ-MnO2), while quartz, feldspar, apatite, and, in three rocks todorokite, are minor phases. Quartz and feldspar decrease with decreasing latitude of occurrence, and is suggested to be related to eolian input. On the average, apatite also increases within the crusts with decreasing latitude of occurrence, which may be related to high biological productivity in the zone of equatorial upwelling. Phosphorite substrates are more abundant on Necker Ridge and S.P. Lee Guyot than they are on Horizon Guyot. Seamount ferromanganese nodules are distinct from abyssal nodules in their chemistry and internal structure.

  3. Effects of electron irradiation and temperature on 1 ohm-cm and 10 ohm-cm silicon solar cells

    NASA Technical Reports Server (NTRS)

    Nicoletta, C. A.

    1973-01-01

    One OHM-cm and 10 OHM-cm silicon solar cells were exposed to 1.0 MeV electrons at a fixed flux of 10 to the 11th power e/sq cm/sec and fluences of 10 to the 13th power, 10 to the 14th power and 10 to the 15th power e/sq.cm. 1-V curves of the cells were made at room temperature, - 63 C and + or - 143 C after each irradiation. A value of 139.5 mw/sq cm was used as AMO incident energy rate per unit area. The 10 OHM-cm cells appear more efficient than 1 OHM-cm cells after exposure to a fluence greater than 10 to the 14th power e/sq cm. The 1.0 MeV electron damage coefficients for both 1 OHM-cm and 10 OHM-cm cells are somewhat less than those for previously irradiated cells at room temperature. The values of the damage coefficients increase as the cell temperatures decrease. Efficiencies pertaining to maximum power output are about the same as those of n on p silicon cells evaluated previously.

  4. Bivalve Shell Horizons in Seafloor Pockmarks of the Last Glacial-interglacial Transition Suggest a Thousand Years of Methane Emissions in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Ambrose, W. G., Jr.; Panieri, G.; Schneider, A.; Plaza-Faverola, A. A.; Carroll, M.; Åström, E. K. L.; Locke, W. L.; Carroll, J.

    2015-12-01

    We studied discrete bivalve shell horizons, in two gravity cores from seafloor pockmarks on the Vestnesa Ridge (ca. 1200 m water depth), western Svalbard (79° 00' N, 06° 55' W) to provide insight into the temporal and spatial dynamics of seabed methane seeps. The shell beds, are dominated by two genera of the family Vesicomyidae: Phreagena s.l. and Isorropodon sp. were 20-30cm thick centered at 250-400cm depth in the cores. The carbon isotope composition of inorganic (δ13C from -13.02‰ to +2.364‰) and organic (δ13C from -29.283‰ to -21.33‰) shell material indicates that these taxa derived their energy primarily from endosymbiotic chemosynthetic bacteria feeding on methane. In addition, negative δ13C values for planktonic foraminifera (-6.7‰ to -3.1‰), micritic concretions identified as methane-derived authigenic carbonates and pyrite encrusted fossil worm tubes at the shell horizons indicate a sustained paleo-methane seep environment. Combining sedimentation rates with 14C ages for bivalve material from the shell horizons, we estimate the horizons persisted for about 1000 years between approximately 17,707 to 16,680 yrs. BP (corrected). The major seepage event over a 1000 -year time interval was most likely triggered by tectonic stress and the subsequent release of over-pressurized fluids.

  5. Bivalve shell horizons in seafloor pockmarks of the last glacial-interglacial transition: a thousand years of methane emissions in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Ambrose, William G.; Panieri, Giuliana; Schneider, Andrea; Plaza-Faverola, Andreia; Carroll, Michael L.; Åström, Emmelie K. L.; Locke, William L.; Carroll, JoLynn

    2015-12-01

    We studied discrete bivalve shell horizons in two gravity cores from seafloor pockmarks on the Vestnesa Ridge (˜1200 m water depth) and western Svalbard (79°00' N, 06°55' W) to provide insight into the temporal and spatial dynamics of seabed methane seeps. The shell beds, dominated by two genera of the family Vesicomyidae: Phreagena s.l. and Isorropodon sp., were 20-30 cm thick and centered at 250-400 cm deep in the cores. The carbon isotope composition of inorganic (δ13C from -13.02‰ to +2.36‰) and organic (δ13C from -29.28‰ to -21.33‰) shell material and a two-end member mixing model indicate that these taxa derived between 8% and 43% of their nutrition from chemosynthetic bacteria. In addition, negative δ13C values for planktonic foraminifera (-6.7‰ to -3.1‰), concretions identified as methane-derived authigenic carbonates, and pyrite-encrusted fossil worm tubes at the shell horizons indicate a sustained paleo-methane seep environment. Combining sedimentation rates with 14C ages for bivalve material from the shell horizons, we estimate the horizons persisted for about 1000 years between approximately 17,707 and 16,680 years B.P. (corrected). The seepage event over a 1000 year time interval was most likely associated with regional stress-related faulting and the subsequent release of overpressurized fluids.

  6. Charge transfer to the local singlet states as a function of Li content in La 2Cu 1- xLi xO 4 and La 1.85Sr 0.15Cu 1- xLi xO 4

    NASA Astrophysics Data System (ADS)

    Rykov, Alexandre I.; Yasuoka, Hiroshi; Ueda, Yutaka

    1995-02-01

    Magnetic susceptibility (χ) and NMR/NQR measurements were performed on La 2Cu 1- xLi xO 4 0≤ x≤0.5) and La 1.85Sr 0.15Cu 1- xLi xO 4 (0≤ x≤0.425). The narrow 63Cu NQR line at νQ = 46.3 MHz (1.3 K) is detected in La 2Cu 0.5Li 0.5O 4. This frequency is higher than all 63Cu-NQR frequencies found so far in all the cuprates. Moreover, a further increase of νQ is observed in the solid solutions La 2Cu 1- xLi xO 4 with decreasing x. Corresponding electric field gradients (EFG's) are considered in terms of ionic and cluster models. The 3d hole density nx2- y2 ≈ 1 and the radial average < r-3> ≈ 9.5 a.u. are derived from the EFG's, suggesting the d 9L state of the formally trivalent copper. The antiferromagnetic ordering is rapidly suppressed as a function of x in the La 2Cu 1- xLi xO 4, and for x ≥ 0.03 we find TN ≈ 0. The evolution of χ vs. x shows a gradual decrease of Cu spin susceptibility and its disappearance in the diamagnetic La 2Cu 0.5Li 0.5O 4, in which χ = -6.7 × 10 -5 cm 3/mole is composed of Van Vleck and core terms. The electronic state is implied to be a local singlet ( 1A 1g) of primarily d 9L character. The quadrupole signature of the local singlet in the range 46.3 ≤ 63ν Q ≤ 47.0 MHz is observed for x > 0.15 in both systems, La 2Cu 1- xLi xO 4 and La 1.85Sr 0.15Cu 1- xLi xO 4. The differentiation of charge between local singlet and conductivity band states is discussed.

  7. Structural and large magnetocaloric properties of La0.67-xYxBa0.23Ca0.1MnO3 perovskites (0≤x≤0.15)

    NASA Astrophysics Data System (ADS)

    Abassi, Mounira; Dhahri, N.; Dhahri, J.; HLIL, E. K.

    2014-09-01

    La0.67Ba0.23Ca0.1MnO3 doped with different amounts of yttrium (Y) result in the series La0.67-xYxBa0.23Ca0.1MnO3 (LYBCMO) (x=0.00, 0.05, 0.10 and 0.15) which was synthesized by conventional solid state ceramics route. All samples show a rhombohedral structure (space group R3 barc) at room temperature. A transition from a paramagnetic to a ferromagnetic phase is observed at Curie temperature, TC. It has been found that the substitution of Y on the La site causes a reduction in TC. Analyses of crystallographic data suggested a strong correlation between structural properties and magnetism. As an example, a relationship between the distortion of MnO6 octahedron and the reduction in Curie temperature. The magnetic entropy change (-ΔS)m was estimated from isothermal magnetization curves. It decreases from 4.91 J/kg K at 350 k (x=0.00) to 4.14 J/kg K at 289 K (x=0.15) with the increase of Y content under μ0H=5 T. The relative cooling power (RCP) is found to be 365 J/kg for La0.67Ba0.23Ca0.1MnO3 and 288 J/kg for La0.52Y0.15Ba0.23Ca0.1MnO3 in the magnetic field change of 5 T. From these results, La0.67-xYxBa0.23Ca0.1MnO3 materials are strongly suggested for use as active refrigerants in magnetic refrigeration technology at near room temperature.

  8. Phase equilibria in the Mo-Fe-P system at 800 °C and structure of ternary phosphide (Mo(1-x)Fe(x))3P (0.10 ≤ x ≤ 0.15).

    PubMed

    Oliynyk, Anton O; Lomnytska, Yaroslava F; Dzevenko, Mariya V; Stoyko, Stanislav S; Mar, Arthur

    2013-01-18

    Construction of the isothermal section in the metal-rich portion (<67 atom % P) of the Mo-Fe-P phase diagram at 800 °C has led to the identification of two new ternary phases: (Mo(1-x)Fe(x))(2)P (x = 0.30-0.82) and (Mo(1-x)Fe(x))(3)P (x = 0.10-0.15). The occurrence of a Co(2)Si-type ternary phase (Mo(1-x)Fe(x))(2)P, which straddles the equiatomic composition MoFeP, is common to other ternary transition-metal phosphide systems. However, the ternary phase (Mo(1-x)Fe(x))(3)P is unusual because it is distinct from the binary phase Mo(3)P, notwithstanding their similar compositions and structures. The relationship has been clarified through single-crystal X-ray diffraction studies on Mo(3)P (α-V(3)S-type, space group I42m, a = 9.7925(11) Å, c = 4.8246(6) Å) and (Mo(0.85)Fe(0.15))(3)P (Ni(3)P-type, space group I4, a = 9.6982(8) Å, c = 4.7590(4) Å) at -100 °C. Representation in terms of nets containing fused triangles provides a pathway to transform these closely related structures through twisting. Band structure calculations support the adoption of these structure types and the site preference of Fe atoms. Electrical resistivity measurements on (Mo(0.85)Fe(0.15))(3)P reveal metallic behavior but no superconducting transition.

  9. Ferroic phase transition of tetragonal Pb0.6-xCaxBi0.4(Ti0.75Zn0.15Fe0.1)O3 ceramics: Factors determining Curie temperature

    NASA Astrophysics Data System (ADS)

    Yu, Jian; An, Fei-fei; Cao, Fei

    2014-05-01

    In this paper, ferroelectric phase transitions of Pb0.6-xCaxBi0.4(Ti0.75Zn0.15Fe0.1)O3 with x ≤ 0.20 ceramics were experimentally measured and a change from first-order to relaxor was found at a critical composition x ˜ 0.19. With increasing Ca content of x ≤ 0.18, Curie temperature and tetragonality was found decrease but piezoelectric constant and dielectric constant increase in a quadratic polynomial relationship as a function of x, while the ferroic Curie temperature and ferroelastic ordering parameter of tetragonality are correlated in a quadratic polynomial relationship. Near the critical composition of ferroic phase transition from first-order to relaxor, the Pb0.42Ca0.18Bi0.4(Ti0.75Zn0.15Fe0.1)O3 and 1 mol % Nb + 0.5 mol % Mg co-doped Pb0.44Ca0.16Bi0.4(Ti0.75Zn0.15Fe0.1)O3 ceramics exhibit a better anisotropic piezoelectric properties than those commercial piezoceramics of modified-PbTiO3 and PbNb2O6. At last, those factors including reduced mass of unit cell, mismatch between cation size and anion cage size, which affect ferroic Curie temperature and ferroelastic ordering parameter (tetragonality) of tetragonal ABO3 perovskites, are analyzed on the basis of first principle effective Hamiltonian and the reduced mass of unit cell is argued a more universal variable than concentration to determine Curie temperature in a quadratic polynomial relationship over various perovskite-structured solid solutions.

  10. Sintering of BaCe(sub 0.85)Y(sub 0.15)O(sub 3-delta) with/without SrTiO3 Dopant

    NASA Technical Reports Server (NTRS)

    Dynys, F.; Sayir, A.; Heimann, P. J.

    2004-01-01

    The perovskite composition, BaCe(sub 0.85)Y(sub 0.15)O(sub 3-delta), displays excellent protonic conduction at high temperatures making it a desirable candidate for hydrogen separation membranes. This paper reports on the sintering behavior of BaCe(sub 0.85)Y(sub 0.15)O(sub 3-delta) powders doped with SrTiO3. Two methods were used to synthesize BaCe(sub 0.85)Y(sub 0.15)O(sub 3-delta) powders: (1) solid state reaction and (2) wet chemical co-precipitation. Co-precipitated powder crystallized into the perovskite phase at 1000 C for 4 hrs. Complete reaction and crystallization of the perovskite phase by solid state was achieved by calcining at 1200 C for 24 hrs. Solid state synthesis produced a coarser powder with an average particle size of 1.3 microns and surface area of 0.74 sq m/g. Co-precipitation produced a finer powder with a average particle size of 65 nm and surface area of 14.9 sq m/g. Powders were doped with 1, 2, 5, and 10 mole % SrTiO3. Samples were sintered at 1450 C, 1550 C and 1650 C. SrTiO3 enhances sintering, optimal dopant level is different for powders synthesized by solid state and co-precipitation. Both powders exhibit similar grain growth behavior. Dopant levels of 5 and 10 mole % SrTiO3 significantly enhances the grain size.

  11. The structure, magnetostriction, and hysteresis of (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys

    NASA Astrophysics Data System (ADS)

    Wang, Bowen; Lv, Yan; Li, Guolu; Huang, Wenmei; Weng, Ling; Cui, Baozhi

    2015-05-01

    The (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys were prepared in an arc furnace under high purity argon. The as-cast samples wrapped in Mo foil were sealed in a silica tube filled with high purity argon and were homogenized at 1000 °C for 1 day and at 950 °C for 5 days. Then, the homogenized specimens with 5 mm in diameter and 8 mm in length were annealed under the magnetic field of 320 kA/m. The static measurement of magnetostriction (λ//, λ⊥) was made by standard strain gauge, and the magnetization M was measured by a vibrating sample magnetometer. It is found that the main phase of annealed (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys is the (Tb,Dy,Ho)Fe2 phase with the MgCu2-type structure. The magnetostriction λ// and magnetization M of (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys increases with increasing x from x = 0.1 to x = 0.3 when H < 240 kA/m. The hysteresis becomes small with increasing x when x ≤ 0.3. For magnetically annealed rod alloys, the magnetostriction markedly increases and reaches 1080 × 10-6 for x = 0.3 when H = 240 kA/m.

  12. New Horizons at Pluto: Asking the right questions

    NASA Astrophysics Data System (ADS)

    Young, Leslie; Stern, S. Alan; Olkin, Catherine B.; Spencer, John R.; Cheng, Andrew F.; Weaver, Harold A.; Ennico, Kimberly; Moore, Jeffrey M.; Grundy, William M.; Bagenal, Fran; Gladstone, Randy; Lunine, Jonathan I.; New Horizons Science Team

    2016-10-01

    In the 1980's and 1990's, breakthroughs about Pluto and the outer solar system laid the groundwork for the Outer Planets Science Working Group (1992), the Pluto Kuiper Express mission Science Definition Team (1996), and the Announcement of Opportunity for the Pluto Kuiper-Belt mission in 2001. These included specific science goals that molded the mission design, instrument selection, and observing sequence. These goals held up amazingly well over the decades. This historical review of New Horizons will explain how ground-based and theoretical work prepared us for a successful investigation of Pluto, and speculate on some of the new questions raised by the New Horizons flyby of the Pluto system.This work was supported by NASA's New Horizons project.

  13. Optimal control of circular cylinder wakes using long control horizons

    NASA Astrophysics Data System (ADS)

    Flinois, Thibault L. B.; Colonius, Tim

    2015-08-01

    The classical problem of suppressing vortex shedding in the wake of a circular cylinder by using body rotation is revisited in an adjoint-based optimal control framework. The cylinder's unsteady and fully unconstrained rotation rate is optimized at Reynolds numbers between 75 and 200 and over horizons that are longer than in previous studies, where they are typically of the order of a vortex shedding period or shorter. In the best configuration, the drag is reduced by 19%, the vortex shedding is effectively suppressed, and this low drag state is maintained with minimal cylinder rotation after transients. Unlike open-loop control, the optimal control is shown to maintain a specific phase relationship between the actuation and the shedding in order to stabilize the wake. A comparison is also given between the performance of optimizations for different Reynolds numbers, cost functions, and horizon lengths. It is shown that the long horizons used are necessary in order to stabilize the vortex shedding efficiently.

  14. Asymptotically Lifshitz spacetimes with universal horizons in (1 +2 ) dimensions

    NASA Astrophysics Data System (ADS)

    Basu, Sayandeb; Bhattacharyya, Jishnu; Mattingly, David; Roberson, Matthew

    2016-03-01

    Hořava gravity theory possesses global Lifshitz space as a solution and has been conjectured to provide a natural framework for Lifshitz holography. We derive the conditions on the two-derivative Hořava gravity Lagrangian that are necessary for static, asymptotically Lifshitz spacetimes with flat transverse dimensions to contain a universal horizon, which plays a similar thermodynamic role as the Killing horizon in general relativity. Specializing to z =2 in 1 +2 dimensions, we then numerically construct such regular solutions over the whole spacetime. We calculate the mass for these solutions and show that, unlike the asymptotically anti-de Sitter case, the first law applied to the universal horizon is straightforwardly compatible with a thermodynamic interpretation.

  15. Universality in chaos of particle motion near black hole horizon

    NASA Astrophysics Data System (ADS)

    Hashimoto, Koji; Tanahashi, Norihiro

    2017-01-01

    The motion of a particle near a horizon of a spherically symmetric static black hole is shown to possess a universal Lyapunov exponent of chaos bounded by its surface gravity. To probe the horizon, we introduce an electromagnetic or scalar force to the particle so that it does not fall into the horizon. There appears an unstable maximum of the total potential where the evaluated maximal Lyapunov exponent is found to be to the surface gravity of the black hole. This value is independent of the external forces, the particle mass and background geometry, and in this sense this Lyapunov exponent is universal. Unless there are other sources of chaos, the Lyapunov exponent is subject to an inequality λ ≤2 π TBH/ℏ, which is identical to the bound recently discovered by Maldacena, Shenker, and Stanford.

  16. Black hole thermodynamics from near-horizon conformal quantum mechanics

    SciTech Connect

    Camblong, Horacio E.; Ordonez, Carlos R.

    2005-05-15

    The thermodynamics of black holes is shown to be directly induced by their near-horizon conformal invariance. This behavior is exhibited using a scalar field as a probe of the black hole gravitational background, for a general class of metrics in D spacetime dimensions (with D{>=}4). The ensuing analysis is based on conformal quantum mechanics, within a hierarchical near-horizon expansion. In particular, the leading conformal behavior provides the correct quantum statistical properties for the Bekenstein-Hawking entropy, with the near-horizon physics governing the thermodynamics from the outset. Most importantly: (i) this treatment reveals the emergence of holographic properties; (ii) the conformal coupling parameter is shown to be related to the Hawking temperature; and (iii) Schwarzschild-like coordinates, despite their 'coordinate singularity', can be used self-consistently to describe the thermodynamics of black holes.

  17. Design and Performance of 40 cm Ion Optics

    NASA Technical Reports Server (NTRS)

    Soulas, George C.

    2001-01-01

    A 40 cm ion thruster is being developed at the NASA Glenn Research Center to obtain input power and propellant throughput capabilities of 10 kW and 550 kg. respectively. The technical approach here is a continuation of the "derating" technique used for the NSTAR ion thruster. The 40 cm ion thruster presently utilizes the NSTAR ion optics aperture geometry to take advantage of the large database of lifetime and performance data already available. Dome-shaped grids were chosen for the design of the 40 cm ion optics because this design is naturally suited for large-area ion optics. Ion extraction capabilities and electron backstreaming limits for the 40 cm ion optics were estimated by utilizing NSTAR 30 cm ion optics data. A preliminary service life assessment showed that the propellant throughput goal of 550 kg of xenon may be possible with molybdenum 40 cm ion optics. One 40 cm ion optics' set has been successfully fabricated to date. Additional ion optics' sets are presently being fabricated. Preliminary performance tests were conducted on a laboratory model 40 cm ion thruster.

  18. Photofraction of a 5 cm x 2 cm BGO scintillator. [bismuth germanate crystal for use in cosmic gamma ray detector

    NASA Technical Reports Server (NTRS)

    Dunphy, P. P.; Forrest, D. J.

    1985-01-01

    The photofraction of a 5.1 cm x 2.0 cm bismuth germanate (BGO) scintillator was measured over a gamma-ray energy range of 0.2 to 6.1 MeV. Several methods, used to minimize the effect of room scattering on the measurement, are discussed. These include a gamma-gamma coincidence technique, a beta-gamma coincidence technique, and the use of sources calibrated with a standard 7.6 cm x 7.6 cm sodium iodide scintillator.

  19. Effects of proton irradiation and temperature on 1 ohm-cm and 10 ohm-cm silicon solar cells

    NASA Technical Reports Server (NTRS)

    Nicoletta, C. A.

    1973-01-01

    The 1 ohm-cm and 10 ohm-cm silicon solar cells were exposed to 1.0 MeV protons at a fixed flux of 10 to the 9th power P/sq cm-sec and fluences of 10 to the 10th power, 10 to the 11th power, 10 to the 12th power and 3 X 10 to the 12th power P/sq cm. I-V curves of the cells were made at room temperature, 65 C and 165 C after each irradiation. A value of 139.5 mw/sq cm was taken as AMO incident energy rate per unit area. Degradation occurred for both uncovered 1 ohm-cm and 10 ohm-cm cells. Efficiencies are generally higher than those of comparable U.S. cells tested earlier. Damage (loss in maximum power efficiency) with proton fluence is somewhat higher for 10 ohm-cm cells, measured at the three temperatures, for fluences above 2 X 10 to the 11th power P/sq cm. Cell efficiency, as expected, changes drastically with temperature.

  20. Fast neutron induced fission cross sections of {sup 242m}Am, {sup 245}Cm, {sup 247}Cm

    SciTech Connect

    Fursov, B.I.; Samylin, B.F.; Smirenkin, G.N.; Polynov, V.N.

    1994-12-31

    The experimental data on {sup 242m}Am, {sup 245}Cm and {sup 247}Cm fission cross sections in the 0.13-7.2 Mev neutron energy range are presented. The measurements were made at Van-de-Graaf accelerators with monoenergetic neutron sources. The total data errors are 3.8% for {sup 242m}Am, 3.5% for {sup 245}Cm and 4.5% for {sup 247}Cm. The results given in this paper are preliminary ones.

  1. Priority Questions and Horizon Scanning for Conservation: A Comparative Study

    PubMed Central

    Kark, Salit; Sutherland, William J.; Shanas, Uri; Klass, Keren; Achisar, Hila; Dayan, Tamar; Gavrieli, Yael; Justo-Hanani, Ronit; Mandelik, Yael; Orion, Nir; Pargament, David; Portman, Michelle; Reisman-Berman, Orna; Safriel, Uriel N.; Schaffer, Gad; Steiner, Noa; Tauber, Israel; Levin, Noam

    2016-01-01

    Several projects aimed at identifying priority issues for conservation with high relevance to policy have recently been completed in several countries. Two major types of projects have been undertaken, aimed at identifying (i) policy-relevant questions most imperative to conservation and (ii) horizon scanning topics, defined as emerging issues that are expected to have substantial implications for biodiversity conservation and policy in the future. Here, we provide the first overview of the outcomes of biodiversity and conservation-oriented projects recently completed around the world using this framework. We also include the results of the first questions and horizon scanning project completed for a Mediterranean country. Overall, the outcomes of the different projects undertaken (at the global scale, in the UK, US, Canada, Switzerland and in Israel) were strongly correlated in terms of the proportion of questions and/or horizon scanning topics selected when comparing different topic areas. However, some major differences were found across regions. There was large variation among regions in the percentage of proactive (i.e. action and response oriented) versus descriptive (non-response oriented) priority questions and in the emphasis given to socio-political issues. Substantial differences were also found when comparing outcomes of priority questions versus horizon scanning projects undertaken for the same region. For example, issues related to climate change, human demography and marine ecosystems received higher priority as horizon scanning topics, while ecosystem services were more emphasized as current priority questions. We suggest that future initiatives aimed at identifying priority conservation questions and horizon scanning topics should allow simultaneous identification of both current and future priority issues, as presented here for the first time. We propose that further emphasis on social-political issues should be explicitly integrated into future

  2. Priority Questions and Horizon Scanning for Conservation: A Comparative Study.

    PubMed

    Kark, Salit; Sutherland, William J; Shanas, Uri; Klass, Keren; Achisar, Hila; Dayan, Tamar; Gavrieli, Yael; Justo-Hanani, Ronit; Mandelik, Yael; Orion, Nir; Pargament, David; Portman, Michelle; Reisman-Berman, Orna; Safriel, Uriel N; Schaffer, Gad; Steiner, Noa; Tauber, Israel; Levin, Noam

    2016-01-01

    Several projects aimed at identifying priority issues for conservation with high relevance to policy have recently been completed in several countries. Two major types of projects have been undertaken, aimed at identifying (i) policy-relevant questions most imperative to conservation and (ii) horizon scanning topics, defined as emerging issues that are expected to have substantial implications for biodiversity conservation and policy in the future. Here, we provide the first overview of the outcomes of biodiversity and conservation-oriented projects recently completed around the world using this framework. We also include the results of the first questions and horizon scanning project completed for a Mediterranean country. Overall, the outcomes of the different projects undertaken (at the global scale, in the UK, US, Canada, Switzerland and in Israel) were strongly correlated in terms of the proportion of questions and/or horizon scanning topics selected when comparing different topic areas. However, some major differences were found across regions. There was large variation among regions in the percentage of proactive (i.e. action and response oriented) versus descriptive (non-response oriented) priority questions and in the emphasis given to socio-political issues. Substantial differences were also found when comparing outcomes of priority questions versus horizon scanning projects undertaken for the same region. For example, issues related to climate change, human demography and marine ecosystems received higher priority as horizon scanning topics, while ecosystem services were more emphasized as current priority questions. We suggest that future initiatives aimed at identifying priority conservation questions and horizon scanning topics should allow simultaneous identification of both current and future priority issues, as presented here for the first time. We propose that further emphasis on social-political issues should be explicitly integrated into future

  3. New Horizons: Gas and Plasma in the Pluto System

    NASA Astrophysics Data System (ADS)

    Young, Leslie; Gladstone, Randy; Summers, Michael; Bagenal, Fran; Stern, S. Alan; Weaver, Harold A.; Olkin, Catherine B.; Ennico, Kimberly; Moore, Jeffrey M.; Grundy, William M.; New Horizons Atmospheres Science Theme Team, New Horizons Particles and Plasma Science Theme Team

    2016-10-01

    NASA's New Horizons mission gave us information about gas and plasma in the Pluto system from Pluto's surface up to a distance of ~200,000 km beyond Pluto. This review will give an overview of our current theories and observations of the near-surface atmospheric structure; the properties, production and settling of Pluto's ubiquitous haze; the minor atmospheric species and atmospheric chemistry; the energetics and high-altitude thermal structure; the escape rate and the pickup of methane ions; the effect of methane impacting Charon; and Pluto's heavy-ion tail. Details are given in other presentations at this conference.This work was supported by NASA's New Horizons project.

  4. A Horizon Scan of Global Conservation Issues for 2016.

    PubMed

    Sutherland, William J; Broad, Steven; Caine, Jacqueline; Clout, Mick; Dicks, Lynn V; Doran, Helen; Entwistle, Abigail C; Fleishman, Erica; Gibbons, David W; Keim, Brandon; LeAnstey, Becky; Lickorish, Fiona A; Markillie, Paul; Monk, Kathryn A; Mortimer, Diana; Ockendon, Nancy; Pearce-Higgins, James W; Peck, Lloyd S; Pretty, Jules; Rockström, Johan; Spalding, Mark D; Tonneijck, Femke H; Wintle, Bonnie C; Wright, Katherine E

    2016-01-01

    This paper presents the results of our seventh annual horizon scan, in which we aimed to identify issues that could have substantial effects on global biological diversity in the future, but are not currently widely well known or understood within the conservation community. Fifteen issues were identified by a team that included researchers, practitioners, professional horizon scanners, and journalists. The topics include use of managed bees as transporters of biological control agents, artificial superintelligence, electric pulse trawling, testosterone in the aquatic environment, building artificial oceanic islands, and the incorporation of ecological civilization principles into government policies in China.

  5. Spores, pollen, and microplankton from the horizon Beta outcrop.

    PubMed

    Habib, D

    1968-12-27

    Palynology was used for dating a pre-Pleistocene deep-sea organic lutite layer situated stratigraphically near seismic horizon beta, below horizon A. The spores and pollen are closely identified, quantitatively, with nonmarine and marine Middle Cretaceous assemblages (Albian-Cenomanian) on the continents, an age designation that is confirmed by the occurrence of dinoflagellate cysts, acritarchs, foraminifers, and coccoliths in the investigated cores. The abundance of these well-preserved, land-derived assemblages in an area far removed from a source suggests some tectonic displacement since their deposition.

  6. Foliation dependence of black hole apparent horizons in spherical symmetry

    NASA Astrophysics Data System (ADS)

    Faraoni, Valerio; Ellis, George F. R.; Firouzjaee, Javad T.; Helou, Alexis; Musco, Ilia

    2017-01-01

    Numerical studies of gravitational collapse to black holes make use of apparent horizons, which are intrinsically foliation dependent. We expose the problem and discuss possible solutions using the Hawking-Hayward quasilocal mass. In spherical symmetry, we present a physically sensible approach to the problem by restricting to spherically symmetric spacetime slicings. In spherical symmetry, the apparent horizons enjoy a restricted gauge independence in any spherically symmetric foliation, but physical quantities associated with them, such as surface gravity and temperature, are fully gauge dependent. The widely used comoving and Kodama foliations, which are of particular interest, are discussed in detail as examples.

  7. A horizon scan of global conservation issues for 2014.

    PubMed

    Sutherland, William J; Aveling, Rosalind; Brooks, Thomas M; Clout, Mick; Dicks, Lynn V; Fellman, Liz; Fleishman, Erica; Gibbons, David W; Keim, Brandon; Lickorish, Fiona; Monk, Kathryn A; Mortimer, Diana; Peck, Lloyd S; Pretty, Jules; Rockström, Johan; Rodríguez, Jon Paul; Smith, Rebecca K; Spalding, Mark D; Tonneijck, Femke H; Watkinson, Andrew R

    2014-01-01

    This paper presents the output of our fifth annual horizon-scanning exercise, which aims to identify topics that increasingly may affect conservation of biological diversity, but have yet to be widely considered. A team of professional horizon scanners, researchers, practitioners, and a journalist identified 15 topics which were identified via an iterative, Delphi-like process. The 15 topics include a carbon market induced financial crash, rapid geographic expansion of macroalgal cultivation, genetic control of invasive species, probiotic therapy for amphibians, and an emerging snake fungal disease.

  8. A horizon scan of global conservation issues for 2014

    PubMed Central

    Sutherland, William J.; Aveling, Rosalind; Brooks, Thomas M.; Clout, Mick; Dicks, Lynn V.; Fellman, Liz; Fleishman, Erica; Gibbons, David W.; Keim, Brandon; Lickorish, Fiona; Monk, Kathryn A.; Mortimer, Diana; Peck, Lloyd S.; Pretty, Jules; Rockström, Johan; Rodríguez, Jon Paul; Smith, Rebecca K.; Spalding, Mark D.; Tonneijck, Femke H.; Watkinson, Andrew R.

    2014-01-01

    This paper presents the output of our fifth annual horizon-scanning exercise, which aims to identify topics that increasingly may affect conservation of biological diversity, but have yet to be widely considered. A team of professional horizon scanners, researchers, practitioners, and a journalist identified 15 topics which were identified via an iterative, Delphi-like process. The 15 topics include a carbon market induced financial crash, rapid geographic expansion of macroalgal cultivation, genetic control of invasive species, probiotic therapy for amphibians, and an emerging snake fungal disease. PMID:24332318

  9. Moving Toward Polarimetry with the Event Horizon Telescope

    NASA Astrophysics Data System (ADS)

    Kosowsky, Michael; Fish, V. L.; Doeleman, S.; Johnson, M.; Lu, R.; Marrone, D. P.; Moran, J. M.; Plambeck, R. L.; Wardle, J. F.; EHT Collaboration

    2014-01-01

    The Event Horizon Telescope (EHT) project aims to develop millimeter and submillimeter VLBI to achieve angular resolution of tens of microarcseconds, comparable to the event horizons of nearby supermassive black holes. A major challenge for polarimetry at these scales is instrumental cross-talk, which introduces spurious linear polarization that can easily overwhelm the intrinsic signal. We demonstrate a new method for correcting the instrumental response, based on Markov Chain Monte Carlo simulations and other non-linear fitting methods. We will present preliminary polarimetric results on several EHT targets. Future EHT observations will provide a new window into the rich magnetic structures of their innermost cores.

  10. Earth, Meet Pluto: The New Horizons Education and Communications Partnership

    NASA Astrophysics Data System (ADS)

    Buckley, M.

    2015-12-01

    The unique partnership between the NASA New Horizons education/communications and public affairs programs tapped into the excitement of visiting an unexplored planet in a new region of the solar system - resulting in unprecedented public participation in and coverage of a planetary mission. With a range of hands-on learning experiences, Web materials and online , the program provided opportunities for students, educators, museums, science centers, the media, Web surfers and other members of the public to ride along on the first mission to Pluto and the Kuiper Belt. The programs leveraged resources, materials and expertise to address a wide range of traditional and nontraditional audiences while providing consistent messages and information on this historic NASA endeavor. The E/C program included a variety of formal lesson plans and learning materials — based on New Horizons science and engineering goals, and aligned with National Research Council's National Science Education Standards — that continue to help students in grades K-12 learn more about science, technology, engineering and mathematics. College students designed and built an actual flight instrument on New Horizons and held internships with the spacecraft integration and test team. New Horizons E/C programs went well beyond the classroom, from a chance for people to send their names to Pluto on board the New Horizons spacecraft before launch, to opportunities for the public to access milestone events and the first-ever close-up views of Pluto in places such as museums, science centers and libraries, TV and the Web — as well as thousands who attended interactive "Plutopalooza" road shows across the country. Teamed with E/C was the public affairs strategy to communicate New Horizons news and messages to media, mission stakeholders, the scientific community and the public. These messages include various aspects of New Horizons, including the progress of the mission and key milestones and achievements

  11. Robust Consumption-Investment Problem on Infinite Horizon

    SciTech Connect

    Zawisza, Dariusz

    2015-12-15

    In our paper we consider an infinite horizon consumption-investment problem under a model misspecification in a general stochastic factor model. We formulate the problem as a stochastic game and finally characterize the saddle point and the value function of that game using an ODE of semilinear type, for which we provide a proof of an existence and uniqueness theorem for its solution. Such equation is interested on its own right, since it generalizes many other equations arising in various infinite horizon optimization problems.

  12. Design and fabrication of the New Horizons Long-Range Reconnaissance Imager

    NASA Astrophysics Data System (ADS)

    Conard, S. J.; Azad, F.; Boldt, J. D.; Cheng, A.; Cooper, K. A.; Darlington, E. H.; Grey, M. P.; Hayes, J. R.; Hogue, P.; Kosakowski, K. E.; Magee, T.; Morgan, M. F.; Rossano, E.; Sampath, D.; Schlemm, C.; Weaver, H. A.

    2005-09-01

    The LOng-Range Reconnaissance Imager (LORRI) is an instrument that was designed, fabricated, and qualified for the New Horizons mission to the outermost planet Pluto, its giant satellite Charon, and the Kuiper Belt, which is the vast belt of icy bodies extending roughly from Neptune's orbit out to 50 astronomical units (AU). New Horizons is being prepared for launch in January 2006 as the inaugural mission in NASA's New Frontiers program. This paper provides an overview of the efforts to produce LORRI. LORRI is a narrow angle (field of view=0.29°), high resolution (instantaneous field of view = 4.94 μrad), Ritchey-Chretien telescope with a 20.8 cm diameter primary mirror, a focal length of 263 cm, and a three lens field-flattening assembly. A 1024 x 1024 pixel (optically active region), back-thinned, backside-illuminated charge-coupled device (CCD) detector (model CCD 47-20 from E2V Technologies) is located at the telescope focal plane and is operated in standard frame-transfer mode. LORRI does not have any color filters; it provides panchromatic imaging over a wide bandpass that extends approximately from 350 nm to 850 nm. A unique aspect of LORRI is the extreme thermal environment, as the instrument is situated inside a near room temperature spacecraft, while pointing primarily at cold space. This environment forced the use of a silicon carbide optical system, which is designed to maintain focus over the operating temperature range without a focus adjustment mechanism. Another challenging aspect of the design is that the spacecraft will be thruster stabilized (no reaction wheels), which places stringent limits on the available exposure time and the optical throughput needed to accomplish the high-resolution observations required. LORRI was designed and fabricated by a combined effort of The Johns Hopkins University Applied Physics Laboratory (APL) and SSG Precision Optronics Incorporated (SSG).

  13. Sub-10 μm grain size, Ba1-xCaxTi0.9Zr0.1O3 (x = 0.10 and x = 0.15) piezoceramics processed using a reduced thermal treatment

    NASA Astrophysics Data System (ADS)

    Reyes-Montero, A.; Pardo, L.; López-Juárez, R.; González, A. M.; Rea-López, S. O.; Cruz, M. P.; Villafuerte-Castrejón, M. E.

    2015-06-01

    The solid-state synthesis of Ba1-xCaxTi0.9Zr0.1O3 (x = 0.10, 0.15) (BCTZ) powder and the processing method of ceramics, by the use of reduced synthesis time and temperature (1250 °C for 2 h), are reported. Homogeneous and dense (≥95%) ceramic microstructures with sub-10 μm grain size were obtained under all sintering conditions. A comparative study of their ferro-piezoelectric properties as a function of sintering temperatures is presented. The study shows the role of the grain size effect for improving both piezoelectric and ferroelectric properties of these materials. With an increase of the sintering temperature, grain growth was promoted; therefore, higher ferro-piezoelectric values were obtained (at 1400 °C, for x = 0.10: d33 = 300 pC/N, {{d}31}=-150 pC/N, kp = 48% for x = 0.15: d33 = 410 pC/N, d31 =-154 pC/N, kp = 50%). In addition, a diffuse phase transition is observed in these BCTZ ceramics with a Curie temperature near 100 °C at 1 kHz.

  14. Magneto-transport properties of La0.75Ca0.15Sr0.1MnO3 with YBa2Cu3O7-δ addition

    NASA Astrophysics Data System (ADS)

    Zghal, E.; Koubaa, M.; Berthet, P.; Sicard, L.; Cheikhrouhou-Koubaa, W.; Decorse-Pascanut, C.; Cheikhrouhou, A.; Ammar-Merah, S.

    2016-09-01

    We report the structural, magnetic, electrical and magentoresistance properties of (La0.75Ca0.15Sr0.1MnO3)1-x(YBa2Cu3O7-δ)x (with x=0, 0.025, 0.05, 0.075, 0.1, 0.2, and 0.3) composites synthesized through sol-gel method. The powder X-ray diffraction patterns indicate no evidence of reaction between La0.75Ca0.15Sr0.1MnO3 (LCSMO) and YBa2Cu3O7-δ (YBCO). The addition of YBCO induces a reduction of the total magnetization while the Curie temperature remains almost constant (∼312 K). The behavior of the electrical resistivity evolves differently depending on the doping level. Above the paramagnetic-insulating transition temperature the resistivity data were best-fitted by using the adiabatic small polaron and variable range hopping models. Ferromagnetic-metallic regime in the composites seems to emanate from the electron-phonon or/and electron-magnon scattering processes. With increasing the YBCO doping content (until x=0.1), the positive magnetoresistance (MR) of YBCO phase dominates the negative MR of LCSMO one, which gives rise to the decreasing of MR of the composites.

  15. Investigation of the effect of Ag addition on the critical current density of the high-temperature superconductor Nd1.85Ce0.15CuO4

    NASA Astrophysics Data System (ADS)

    Radhikesh Raveendran, N.; Vinod, K.; Amaladass, E. P.; Janaki, J.; Mani, Awadhesh

    2016-07-01

    We have synthesized a Nd1.85Ce0.15CuO4 + Ag composite system with the aim of studying the effect of Ag addition in the electron-doped system Nd1.85Ce0.15CuO4 on its superconducting and magnetic properties. Measurements of magnetization using a vibration sample magnetometer indicate a systematic increase in diamagnetic shielding upon Ag addition. A subsequent analysis of the critical current density using the Bean model indicates a small but significant increase in intra-grain critical current density upon Ag addition. From the study of the dependence of electrical resistivity on the temperature and electrical current, an increase in inter-granular critical current has also been evidenced upon Ag addition. These results correlate well with the earlier reports of a similar improvement in the properties on the hole-doped ceramic superconductor/Ag composites. Possible reasons for the enhancement of JC have been described and discussed. Magnetic characterization by AC susceptibility using a SQUID magnetometer has been presented for a representative composition, which enabled delineation of the inter- and intra-granular transitions.

  16. On the study of Structural properties and Cation distribution of Zn0.75-xNixMg0.15Cu0.1Fe2O4 nano ferrite: Effect of Ni addition

    NASA Astrophysics Data System (ADS)

    Satalkar, M.; Kane, S. N.

    2016-10-01

    Effect of Ni addition on structural properties and, cation distribution of Zn0.75-xNixMg0.15Cu0.1Fe2O4 (x = 0.0, 0.15, 0.30, 0.60, 0.75) ferrites, prepared using sol-gel autocombustion method was studied using X-ray diffraction (XRD) technique. XRD analysis reveals the formation of spinel phase even in dry gel form. The lattice constant (a exp.) decreases with Ni2+ substitution and follows Vegard's law. Scherrer's grain diameter (D) lies within the range of 17.33 - 26.47 nm. Due to difference in the ionic radii of Zn2+ and Ni2+ significant changes are observed in the structural parameters - unit cell volume (V), hopping length at A (La ) and B (Lb ) site, and x-ray density (ρXRD ). Linear increase in Neel magnetic moment (nB N) with oxygen positional parameter is observed in the studied samples, attributed to simultaneous weakening of A-B interaction and strengthening of the B-B interaction.

  17. A combined sol-gel and spark plasma sintering route to produce highly dense and fine-grained La0.65Ca0.20Na0.15MnO3 ceramics for magnetocaloric applications

    NASA Astrophysics Data System (ADS)

    Abdallah-Ben Ammar, Amal; Ayadi, Firas; Nowak, Sophie; Lecoq, Hélène; Cheikrouhou-Koubaa, Wissem; Cheikhrouhou, Abdelwaheb; Ammar, Souad; Sicard, Lorette

    2014-03-01

    Sol-gel chemistry and spark plasma sintering were coupled to produce fine-grained and dense La0.65Ca0.20Na0.15MnO3 ceramics and their magnetic properties were explored in order to evaluate their efficiency for domestic magnetocaloric applications. The obtained manganites crystallize in the rhombohedral symmetry (R-3c). They present grain size in the sub-micrometer range. Their density and their average grain size increase when the sintering temperature increases from 600 to 800 °C. This entails an increase of the Curie temperature (T C) and of the maximum of the magnetic entropy change, even if these values remain smaller than those measured on their bulk counterparts prepared by a conventional solid state route. However, the magnetic transition occurs on a broad temperature range, resulting in a relative cooling power reaching about 265 J Kg-1 for an applied magnetic field of 5 T. This value is very close to that previously measured on bulk La0.65Ca0.20Na0.15MnO3 ceramics and represents about 64% of that measured on the standard Gd. The ceramics produced here by a low-energy and time-consuming method can thus be considered as technically and economically valuable for the desired applications.

  18. Spectra of circular and linear photogalvanic effect at inter-band excitation in In0.15Ga0.85As/Al0.3Ga0.7As multiple quantum wells

    NASA Astrophysics Data System (ADS)

    Yu, Jinling; Chen, Yonghai; Cheng, Shuying; Lai, Yunfeng

    2013-03-01

    Spectra of circular photogalvanic effect (CPGE) and linear photogalvanic effect (LPGE) for inter-band transition have been experimentally investigated in In0.15Ga0.85As/Al0.3Ga0.7As multiple quantum wells (QWs) at room temperature. The CPGE and LPGE spectra are quite similar during the spectral region corresponding to the transitions 1e1hh (the first valence subband of heavy hole to the first conduction band) and 1e2hh, which is also similar to that of the photoconductivity. Comparing the photocurrent induced by LPGE and CPGE along [1 1 0] and [1 1bar 0] directions, we obtain the anisotropic ratio of the linear photogalvanic tensor χ and circular photogalvanic tensor γ to be χxxz/χyyz=3.6 and γxy/γyx=1.3 (x∥[1 1 0] and y∥[1 1bar 0]), which indicate that the symmetry of the structure belongs to C2v point group and the Rashba spin splitting is the dominant mechanism to induce the k-linear spin splitting of the subband in the In0.15Ga0.85As/Al0.3Ga0.7As QWs. The magnitude of the LPGE is nearly at the same order with that of the CPGE for the investigated spectral region at room temperature.

  19. Sub-cm Particles in Saturn's Rings from VIMS, UVIS, and RSS occultations

    NASA Astrophysics Data System (ADS)

    Jerousek, Richard Gregory; Colwell, Josh E.; Hedman, Matthew M.; Marouf, Essam A.; Esposito, Larry W.; Nicholson, Philip D.; French, Richard G.

    2016-10-01

    Particles sizes in Saturn's rings roughly follow a truncated power law. One way to determine the governing parameters of the size distribution is through the analysis of differential optical depths (Zebker et al. 1983). Non-axisymmetric self-gravity wakes complicate this approach when optical depth measurements at different wavelengths are not made at same viewing geometry. Using occultations spanning a wide range of viewing angles and from multiple instruments onboard Cassini (the Ultraviolet Imaging Spectrograph (UVIS), the Visual and Infrared Mapping Spectrometer (VIMS), and the Radio Science Subsystem (RSS)), we forward-model the properties of the self-gravity wakes in Saturn's A and B rings while simultaneously constraining the parameters of the cm - sub-cm particle size distribution. In the absence of wakes, and in regions where particles smaller than ~ 8.86 mm are present, VIMS stellar occultations measure larger optical depths than UVIS stellar occultations due to the diffraction of 2.9 μm light out of the small (0.25 × 0.5 mrad) VIMS field of view compared with UVIS which measures shorter wavelength (0.15 μm) light over a much larger (6.4 × 6.0 mrad) field of view. This excess optical depth combined with RSS X-band (λ = 3.6 cm) optical depths provides a way to probe both the power law slope and the minimum particle size. In the A and B rings where self-gravity wakes are prevalent, we use the wake model of Colwell et al. (2006, 2007) with an additional free parameter representing the excess optical depth which would be measured through the gaps between opaque wakes, by VIMS compared to UVIS. In the B ring and inner A ring we find and absence of sub-cm particles and power law slopes of q ~ 2.8. In the trans-Encke region, where there are a multitude of satellite driven resonances, we find an increasing abundance of sub-cm particles as the outer edge of the A ring is approached. In the C Ring and the Cassini Division, where self-gravity wakes are absent

  20. Generalized Robertson-Walker Space-Time Admitting Evolving Null Horizons Related to a Black Hole Event Horizon

    PubMed Central

    2016-01-01

    A new technique is used to study a family of time-dependent null horizons, called “Evolving Null Horizons” (ENHs), of generalized Robertson-Walker (GRW) space-time (M¯,g¯) such that the metric g¯ satisfies a kinematic condition. This work is different from our early papers on the same issue where we used (1 + n)-splitting space-time but only some special subcases of GRW space-time have this formalism. Also, in contrast to previous work, we have proved that each member of ENHs is totally umbilical in (M¯,g¯). Finally, we show that there exists an ENH which is always a null horizon evolving into a black hole event horizon and suggest some open problems. PMID:27722202

  1. Effects of antiresorptive therapies on glucose metabolism: results from the FIT, HORIZON-PFT, and FREEDOM trials.

    PubMed

    Schwartz, Ann V; Schafer, Anne L; Grey, Andrew; Vittinghoff, Eric; Palermo, Lisa; Lui, Li-Yung L; Wallace, Robert B; Cummings, Steven R; Black, Dennis M; Bauer, Douglas C; Reid, Ian R

    2013-06-01

    In rodent models, undercarboxylated osteocalcin (ucOC) acts as a hormone that promotes insulin sensitivity and secretion. If ucOC plays a similar role in humans, then antiresorptive therapies, which reduce ucOC levels, may increase the risk of insulin resistance and diabetes. We tested whether antiresorptive therapies result in higher fasting glucose, increased weight, or greater diabetes incidence in post hoc analyses of three randomized, placebo-controlled trials in postmenopausal women: Fracture Intervention Trial (FIT) (N = 6151) of alendronate (4 years), Health Outcomes and Reduced Incidence with Zoledronic Acid Once Yearly Pivotal Fracture Trial (HORIZON-PFT) (N = 7113) of zoledronic acid (3 years), and Fracture Reduction Evaluation of Denosumab in Osteoporosis Every 6 Months (FREEDOM) trial (N = 7076) of denosumab (3 years). Fasting glucose was measured annually in FIT and HORIZON in a subset of women, and every 6 months in FREEDOM in all participants. Weight was measured annually in all trials. Incident diabetes was identified from adverse event reports, initiation of diabetes medication, or elevated fasting glucose. Differences in fasting glucose changes from randomization to trial conclusion between treatment and placebo groups were not statistically significant: -0.47 mg/dL in FIT, 0.20 mg/dL in HORIZON-PFT, and 0.09 mg/dL in FREEDOM, all p > 0.6. Weight change differed between treatment and placebo groups in FIT (0.32 kg, p = 0.003) and FREEDOM (0.31 kg, p = 0.023) but not in HORIZON-PFT (0.15 kg, p = 0.132). In the three trials combined, diabetes occurred in 203 and 225 women assigned to treatment or placebo, respectively. Diabetes incidence was not increased in any of the treatment groups or in the pooled estimate (pooled relative risk [RR] = 0.90; 95% confidence interval [CI] 0.74-1.10). Antiresorptive therapy does not have a clinically important effect on fasting glucose, weight, or diabetes risk in

  2. Through the looking glass: why the `cosmic horizon' is not a horizon

    NASA Astrophysics Data System (ADS)

    van Oirschot, Pim; Kwan, Juliana; Lewis, Geraint F.

    2010-06-01

    The present standard model of cosmology, Λ cold dark matter (ΛCDM), contains some intriguing coincidences. Not only are the dominant contributions to the energy density approximately of the same order at the present epoch, but we also note that contrary to the emergence of cosmic acceleration as a recent phenomenon, the time-averaged value of the deceleration parameter over the age of the Universe is nearly zero. Curious features like these in ΛCDM give rise to a number of alternate cosmologies being proposed to remove them, including models with an equation of state w = -1/3. In this paper, we examine the validity of some of these alternate models and we also address some persistent misconceptions about the Hubble sphere and the event horizon that lead to erroneous conclusions about cosmology. Research undertaken as part of the Commonwealth Cosmology Initiative (CCI: http://www.thecci.org), an international collaboration supported by the Australian Research Council. E-mail: pimvanoirschot@gmail.com

  3. Eight-cm mercury ion thruster system technology

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The technology status of 8 cm diameter electron bombardment ion thrusters is presented. Much of the technology resulting from the 5 cm diameter thruster has been adapted and improved upon to increase the reliability, durability, and efficiency of the 8 cm thruster. Technology discussed includes: dependence of neutralizer tip erosion upon neutralizer flow rate; impregnated and rolled-foil insert cathode performance and life testing; neutralizer position studies; thruster ion beam profile measurements; high voltage pulse ignition; high utilization ion machined accelerator grids; deposition internal and external to the thruster; thruster vectoring systems; thruster cycling life testing and thruster system weights for typical mission applications.

  4. Ion accelerator systems for high power 30 cm thruster operation

    NASA Technical Reports Server (NTRS)

    Aston, G.

    1982-01-01

    Two and three-grid accelerator systems for high power ion thruster operation were investigated. Two-grid translation tests show that over compensation of the 30 cm thruster SHAG grid set spacing the 30 cm thruster radial plasma density variation and by incorporating grid compensation only sufficient to maintain grid hole axial alignment, it is shown that beam current gains as large as 50% can be realized. Three-grid translation tests performed with a simulated 30 cm thruster discharge chamber show that substantial beamlet steering can be reliably affected by decelerator grid translation only, at net-to-total voltage ratios as low as 0.05.

  5. Alteration and formation of rims on the CM parent body

    NASA Astrophysics Data System (ADS)

    Browning, Lauren B.; McSween, Harry Y., Jr.; Zolensky, Michael

    1994-03-01

    All types of coarse-grained components in CM chondrites are surrounded by fine-grained dust coatings, but the origin of these rims is not yet clear. Although a strictly nebular origin seems likely for rims in the relatively unaltered type 3 chondrites, the rims in CM chondrites are dominated by secondary alteration phases. It has been argued that either the coarse-grained cores accreted altered rim materials while still in the nebula or that alteration of primary rim phases occurred on the CM parent body. To constrain the origin of alteration phases in rim material, we have analyzed the textures and mineral associations from 10 CM chondritic falls by optical and scanning electron microscopy. Our results indicate that the secondary phases in CM chondritic rims were produced by parent body fluid-rock interactions which redefined some primary rim textures and may have produced, in some cases, both coarse-grained components and the rims that surround them. Textural features demonstrate the interactive exchange of alteration fluids between rims, matrix, and chondrules on the CM parent body. For example, most matrix-rim contacts are gradational, suggesting the synchronous alteration of both components. Several observations suggest the possibility of in situ rim production. For example, tochilinite and phyllosilicates commonly form rims around matrix carbonates, which are generally believed to have precipitated from alteration fluids on the CM parent body. This suggests that the rims surrounding matrix carbonates may also have been produced by alteration processes. Partially replaced chondrule olivines bear a striking resemblance to many rimmed olivines in the matrix which suggests, by analogy, that site-specific precipitation of S-bearing phases may also be responsible for the occurrence of many tochilinite-rich rims around isolated matrix olivines. Non-silicate rims precipitate around olivines of any composition, but the process is most effective for fayalitic olivines

  6. What happens to Petrov classification, on horizons of axisymmetric dirty black holes

    SciTech Connect

    Tanatarov, I. V.; Zaslavskii, O. B.

    2014-02-15

    We consider axisymmetric stationary dirty black holes with regular non-extremal or extremal horizons, and compute their on-horizon Petrov types. The Petrov type (PT) in the frame of the observer crossing the horizon can be different from that formally obtained in the usual (but singular in the horizon limit) frame of an observer on a circular orbit. We call this entity the boosted Petrov type (BPT), as the corresponding frame is obtained by a singular boost from the regular one. The PT off-horizon can be more general than PT on-horizon and that can be more general than the BPT on horizon. This is valid for all regular metrics, irrespective of the extremality of the horizon. We analyze and classify the possible relations between the three characteristics and discuss the nature and features of the underlying singular boost. The three Petrov types can be the same only for space-times of PT D and O off-horizon. The mutual alignment of principal null directions and the generator in the vicinity of the horizon is studied in detail. As an example, we also analyze a special class of metrics with utra-extremal horizons (for which the regularity conditions look different from the general case) and compare their off-horizon and on-horizon algebraic structure in both frames.

  7. Confirmation of Wide-field Signatures in Redshifted 21 cm Power Spectra

    NASA Astrophysics Data System (ADS)

    Thyagarajan, Nithyanandan; Jacobs, Daniel C.; Bowman, Judd D.; Barry, N.; Beardsley, A. P.; Bernardi, G.; Briggs, F.; Cappallo, R. J.; Carroll, P.; Deshpande, A. A.; de Oliveira-Costa, A.; Dillon, Joshua S.; Ewall-Wice, A.; Feng, L.; Greenhill, L. J.; Hazelton, B. J.; Hernquist, L.; Hewitt, J. N.; Hurley-Walker, N.; Johnston-Hollitt, M.; Kaplan, D. L.; Kim, Han-Seek; Kittiwisit, P.; Lenc, E.; Line, J.; Loeb, A.; Lonsdale, C. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Neben, A. R.; Oberoi, D.; Offringa, A. R.; Ord, S. M.; Paul, Sourabh; Pindor, B.; Pober, J. C.; Prabu, T.; Procopio, P.; Riding, J.; Udaya Shankar, N.; Sethi, Shiv K.; Srivani, K. S.; Subrahmanyan, R.; Sullivan, I. S.; Tegmark, M.; Tingay, S. J.; Trott, C. M.; Wayth, R. B.; Webster, R. L.; Williams, A.; Williams, C. L.; Wyithe, J. S. B.

    2015-07-01

    We confirm our recent prediction of the “pitchfork” foreground signature in power spectra of high-redshift 21 cm measurements where the interferometer is sensitive to large-scale structure on all baselines. This is due to the inherent response of a wide-field instrument and is characterized by enhanced power from foreground emission in Fourier modes adjacent to those considered to be the most sensitive to the cosmological H i signal. In our recent paper, many signatures from the simulation that predicted this feature were validated against Murchison Widefield Array (MWA) data, but this key pitchfork signature was close to the noise level. In this paper, we improve the data sensitivity through the coherent averaging of 12 independent snapshots with identical instrument settings and provide the first confirmation of the prediction with a signal-to-noise ratio \\gt 10. This wide-field effect can be mitigated by careful antenna designs that suppress sensitivity near the horizon. Simple models for antenna apertures that have been proposed for future instruments such as the Hydrogen Epoch of Reionization Array and the Square Kilometre Array indicate they should suppress foreground leakage from the pitchfork by ∼40 dB relative to the MWA and significantly increase the likelihood of cosmological signal detection in these critical Fourier modes in the three-dimensional power spectrum.

  8. Ecological Impacts during the Deepwater Horizon Oil Spill

    EPA Science Inventory

    The Deepwater Horizon (DWH) oil spill was the largest spill and response effort in United States history. Nearly 800 million L of oil was spilled in the Gulf of Mexico, and nearly 7 million L of chemical dispersants were applied in at the ocean surface and subsea1. The DWH spill ...

  9. New Horizons: An Empowerment Program for Egyptian Adolescent Girls.

    ERIC Educational Resources Information Center

    Swanson, Julie Hanson

    New Horizons is a nonschool program that demystifies and communicates essential information on basic life skills and reproductive health to Egyptian girls and young women aged 9-20. The program consists of 100 hour-long sessions, each including an introduction to a specific topic, review of group knowledge level, discussion around key points…

  10. Apparent horizons in D-dimensional Robinson-Trautman spacetime

    SciTech Connect

    Svitek, Otakar

    2009-05-01

    We derive the higher dimensional generalization of Penrose-Tod equation describing apparent horizons in Robinson-Trautman spacetimes. New results concerning the existence and uniqueness of its solutions in four dimensions are proven. Namely, previous results of Tod [1] are generalized to nonvanishing cosmological constant.

  11. Beyond Symbolic Processing: Expanding Horizons for Educational Psychology.

    ERIC Educational Resources Information Center

    Derry, Sharon J.

    1992-01-01

    The horizons are expanding for educational psychology as important questions are being raised about the extent and nature of the relationship between formal schooling and life experiences. A broadening of perspectives is required to incorporate cultural contexts and forces in which schooling takes part. (SLD)

  12. Broadening the Horizons: Organizational Communication in the Real World.

    ERIC Educational Resources Information Center

    Swanson, Georgia

    Working in the microcosm of an individual class, organizational communication instructors can broaden the student's horizon by starting with what are local types of diversity and then expanding the classroom understanding to include the larger world where that student is going to live and work. Speech communication teachers/scholars have seen…

  13. Ecological Impacts During the Deepwater Horizon Oil Spill Response

    EPA Science Inventory

    The Deepwater Horizon (DWH) oil spill was the largest environmental disaster and response effort in U.S. history, with nearly 800 million liters of crude oil spilled. Vast areas of the Gulf of Mexico were contaminated with oil, including deep-ocean communities and over 1,600 kilo...

  14. Ecological impacts of the Deepwater Horizon oil spill

    EPA Science Inventory

    The Deepwater Horizon oil spill (DWH) was the largest environmental disaster and response effort in United States history, with nearly 800 million liters of crude oil spilled. Vast areas of the Gulf of Mexico were contaminated with oil, including deep ocean communities and over 1...

  15. Breaking an Abelian gauge symmetry near a black hole horizon

    SciTech Connect

    Gubser, Steven S.

    2008-09-15

    I argue that coupling the Abelian Higgs model to gravity plus a negative cosmological constant leads to black holes which spontaneously break the gauge invariance via a charged scalar condensate slightly outside their horizon. This suggests that black holes can superconduct.

  16. Colorful Horizons with Charge in Anti-de Sitter Space

    SciTech Connect

    Gubser, Steven S.

    2008-11-07

    An Abelian gauge symmetry can be spontaneously broken near a black hole horizon in anti-de Sitter space using a condensate of non-Abelian gauge fields. A second order phase transition is shown to separate Reissner-Nordstroem-anti-de Sitter solutions from a family of symmetry-breaking solutions which preserve a diagonal combination of gauge invariance and spatial rotational invariance.

  17. Rethinking Classroom Management: A New Perspective, a New Horizon

    ERIC Educational Resources Information Center

    Toprakci, Erdal

    2012-01-01

    The purpose of this study is to suggest a new perspective and a new horizon by analyzing the concept of classroom management in the literature of traditional classroom management from a scientific and dictionary view. It may be said that there are serious problems regarding the settlement of the meaning of "classroom management" in the educational…

  18. CFT/gravity correspondence on the isolated horizon

    NASA Astrophysics Data System (ADS)

    Ghosh, Amit; Pranzetti, Daniele

    2014-12-01

    A quantum isolated horizon can be modelled by an SU (2) Chern-Simons theory on a punctured 2-sphere. We show how a local 2-dimensional conformal symmetry arises at each puncture inducing an infinite set of new observables localised at the horizon which satisfy a Kac-Moody algebra. By means of the isolated horizon boundary conditions, we represent the gravitational flux degrees of freedom in terms of the zero modes of the Kac-Moody algebra defined on the boundary of a punctured disk. In this way, our construction encodes a precise notion of CFT/gravity correspondence. The higher modes in the algebra represent new nongeometric charges which can be represented in terms of free matter field degrees of freedom. When computing the CFT partition function of the system, these new states induce an extra degeneracy factor, representing the density of horizon states at a given energy level, which reproduces the Bekenstein's holographic bound for an imaginary Immirzi parameter. This allows us to recover the Bekenstein-Hawking entropy formula without the large quantum gravity corrections associated with the number of punctures.

  19. New Horizons for Learning: An Interview with Dee Dickinson

    ERIC Educational Resources Information Center

    Windham, Scott; Dickinson, Dee

    2005-01-01

    This article presents an interview with Dee Dickinson, founder and chief learning officer of New Horizons for Learning, a nonprofit international education network whose mission is to identify, communicate, and help implement effective teaching and learning strategies. Founded in 1980 and now operating largely through its Web site, New Horizons…

  20. Planning horizon affects prophylactic decision-making and epidemic dynamics

    PubMed Central

    Ridenhour, Benjamin J.; Krone, Stephen M.

    2016-01-01

    The spread of infectious diseases can be impacted by human behavior, and behavioral decisions often depend implicitly on a planning horizon—the time in the future over which options are weighed. We investigate the effects of planning horizons on epidemic dynamics. We developed an epidemiological agent-based model (along with an ODE analog) to explore the decision-making of self-interested individuals on adopting prophylactic behavior. The decision-making process incorporates prophylaxis efficacy and disease prevalence with the individuals’ payoffs and planning horizon. Our results show that for short and long planning horizons individuals do not consider engaging in prophylactic behavior. In contrast, individuals adopt prophylactic behavior when considering intermediate planning horizons. Such adoption, however, is not always monotonically associated with the prevalence of the disease, depending on the perceived protection efficacy and the disease parameters. Adoption of prophylactic behavior reduces the epidemic peak size while prolonging the epidemic and potentially generates secondary waves of infection. These effects can be made stronger by increasing the behavioral decision frequency or distorting an individual’s perceived risk of infection. PMID:27843714

  1. Ecological Impacts of the Deepwater Horizon Oil Spill (Bogota, Columbia)

    EPA Science Inventory

    The Deepwater Horizon oil spill (DWH) was the largest environmental disaster and response effort in US History, with nearly 800 million liters spilled. Vast areas of the Gulf of Mexico were contaminated with oil, including deep ocean communities, protected species, over 1600 km o...

  2. How Big Is the Earth? A Calculation beyond Your Horizon

    ERIC Educational Resources Information Center

    Kibble, Bob

    2011-01-01

    A consequence of the curvature of the Earth is that distant ships apparently disappear over the horizon. This article shows how you can use a simple photograph to help students obtain a reasonable estimate of the size of the Earth using little more than the mathematics of Pythagoras. (Contains 5 figures.)

  3. Supporting Students' Pedagogical Working Life Horizon in Higher Education

    ERIC Educational Resources Information Center

    Penttinen, Leena; Skaniakos, Terhi; Lairio, Marjatta

    2013-01-01

    In this article, we introduce a model of a pedagogical working life horizon. It encompasses questions posed by individual students concerning their future and incorporates the idea of a working life orientation to the pedagogical possibilities within education. Working life orientation consists of three elements: individual relationship, knowledge…

  4. Survey of New Horizons International Music Association Musicians

    ERIC Educational Resources Information Center

    Coffman, Don

    2009-01-01

    This study analysed survey responses from 1652 New Horizons International Music Association (NHIMA) musicians in the United States and Canada to better understand older adults' experiences in making music. The purpose of this study was threefold: (a) ascertain the extent of NHIMA musicians' musical backgrounds and their current involvement in…

  5. Community Colleges Broadening Horizons through Service Learning, 2006-2009

    ERIC Educational Resources Information Center

    Robinson, Gail

    2007-01-01

    This brief introduces "Community Colleges Broadening Horizons through Service Learning," the American Association of Community Colleges' (AACC's) fifth national Learn and Serve America grant project and describes its grantee college programs. The goals of this grant project are to build on established foundations to integrate service…

  6. Black Hole Physics with the Event Horizon Telescope

    NASA Astrophysics Data System (ADS)

    Ozel, Feryal

    2016-01-01

    The Event Horizon Telescope is an experiment that is being performed on a large and ever-increasing array of radio telescopes that span the Earth from Hawaii to Chile and from the South Pole to Arizona. When data will be taken with the full array, it will image the event horizons of the supermassive black hole at the center of our Galaxy, Sagittarius A*, and the black hole at the center of M87, with an unprecedented 10 microarcssecond resolution. This will allow us to take the first ever pictures of black holes at 1.3 and 0.85 mm wavelengths and look for the shadow that is a direct evidence for a black hole predicted by the theory of General Relativity. In addition, the Event Horizon Telescope will also enable us to study the process by which black holes accrete matter and grow in mass. I will discuss the theoretical developments in simulating the properties of the black hole accretion flows and their expected images using state-of-the-art algorithms and high performance computing. Interpreting the upcoming observations within this theoretical framework will open new horizons in black hole astrophysics.

  7. A Summer Journey: The 1999 College Horizons Program.

    ERIC Educational Resources Information Center

    Sorensen, Barbara

    1999-01-01

    In 1999, College Horizons brought 50 American Indian high school students from 28 tribes to the Native American Preparatory School in Rowe, New Mexico, for a unique seminar. During the week-long summer seminar, college representatives presented intensive workshops and large-group sessions on the college application process, including essay…

  8. Solution to the cosmological horizon problem proposed by Zee

    SciTech Connect

    Pollock, M.D.

    1981-08-15

    Applying a theory of gravity with broken symmetry, Zee has suggested a solution to the cosmological horizon problem. His idea has been criticized on two independent grounds by Linde and by Sato. In this paper, we suggest answers to both these criticisms.

  9. Gravitational black hole hair from event horizon supertranslations

    NASA Astrophysics Data System (ADS)

    Averin, Artem; Dvali, Gia; Gomez, Cesar; Lüst, Dieter

    2016-06-01

    We discuss BMS supertranslations both at null-infinity BMS- and on the horizon {BMS}^{mathscr{H}} for the case of the Schwarzschild black hole. We show that both kinds of supertranslations lead to infinetly many gapless physical excitations. On this basis we construct a quotient algebra mathcal{A}equiv {BMS}^{mathscr{H}}/{BMS}- using suited superpositions of both kinds of transformations which cannot be compensated by an ordinary BMS-supertranslation and therefore are intrinsically due to the presence of an event horizon. We show that transformations in mathcal{A} are physical and generate gapless excitations on the horizon that can account for the gravitational hair as well as for the black hole entropy. We identify the physics of these modes as associated with Bogolioubov-Goldstone modes due to quantum criticality. Classically the number of these gapless modes is infinite. However, we show that due to quantum criticality the actual amount of information-carriers becomes finite and consistent with Bekenstein entropy. Although we only consider the case of Schwarzschild geometry, the arguments are extendable to arbitrary space-times containing event horizons.

  10. Anomalous Galactic Dynamics by Collusion of Rindler and Cosmological Horizons

    NASA Astrophysics Data System (ADS)

    van Putten, Maurice H. P. M.

    2017-03-01

    In holography, the dimensional reduction of phase space to two dimensions defines a dynamical dark energy of {{Λ }}=(1-q){H}2, associated with the cosmological horizon at a Hubble radius of {R}H=c/H, and inertia m of baryonic matter at acceleration α in terms of a thermodynamic potential U={{mc}}2 of Rindler horizons at ξ ={c}2/α . Here, H is the Hubble parameter with deceleration q and c is the velocity of light. In weak gravity, m drops below Newton’s value m 0 as α < {a}H, when Rindler horizons fall beyond the cosmological horizon. The onset to weak gravity across α ={a}H is sharp by causality. Striking evidence is found in galaxy rotation curves, whose asymptotic dynamics is parameterized by Milgrom’s scale of acceleration {a}0=({cH}/2π )\\sqrt{1-q}. This onset presents a new challenge for canonical dark matter distributions on galactic scales in ΛCDM. Instead, future galaxy surveys may determine {Q}0={{dq}(z)/{dz}| }z=0, to provide a direct test of dynamical dark energy ({Q}0> 2.5) versus ΛCDM ({Q}0< 1) and establish a bound of {10}-30 {{eV}} on the mass of the putative dark matter particle with clustering limited to galaxy clusters.

  11. 7. PHOTOGRAPHIC COPY OF ORIGINAL CONSTRUCTION DRAWING, DATED 1918, HORIZONAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. PHOTOGRAPHIC COPY OF ORIGINAL CONSTRUCTION DRAWING, DATED 1918, HORIZONAL SLIDING WINDOW DETAIL, WAR DEPARTMENT, MANUAL OF THE CONSTRUCTION DIVISION OF THE ARMY, WAR EMERGENCY CONSTRUCTION, SECTION C, ENGINEERING DIVISION, PLATE 5, CONSOLIDATED SUPPLY COMPANY PRINTERS, WASHINGTON - Fort Bliss, 7th Cavalry Buildings, U.S. Army Air Defence Artillery Center & Fort Bliss, El Paso, El Paso County, TX

  12. Benchmarking and performance analysis of the CM-2. [SIMD computer

    NASA Technical Reports Server (NTRS)

    Myers, David W.; Adams, George B., II

    1988-01-01

    A suite of benchmarking routines testing communication, basic arithmetic operations, and selected kernel algorithms written in LISP and PARIS was developed for the CM-2. Experiment runs are automated via a software framework that sequences individual tests, allowing for unattended overnight operation. Multiple measurements are made and treated statistically to generate well-characterized results from the noisy values given by cm:time. The results obtained provide a comparison with similar, but less extensive, testing done on a CM-1. Tests were chosen to aid the algorithmist in constructing fast, efficient, and correct code on the CM-2, as well as gain insight into what performance criteria are needed when evaluating parallel processing machines.

  13. The 21-cm Signal from the cosmological epoch of recombination

    SciTech Connect

    Fialkov, A.; Loeb, A. E-mail: aloeb@cfa.harvard.edu

    2013-11-01

    The redshifted 21-cm emission by neutral hydrogen offers a unique tool for mapping structure formation in the early universe in three dimensions. Here we provide the first detailed calculation of the 21-cm emission signal during and after the epoch of hydrogen recombination in the redshift range of z ∼ 500–1,100, corresponding to observed wavelengths of 100–230 meters. The 21-cm line deviates from thermal equilibrium with the cosmic microwave background (CMB) due to the excess Lyα radiation from hydrogen and helium recombinations. The resulting 21-cm signal reaches a brightness temperature of a milli-Kelvin, orders of magnitude larger than previously estimated. Its detection by a future lunar or space-based observatory could improve dramatically the statistical constraints on the cosmological initial conditions compared to existing two-dimensional maps of the CMB anisotropies.

  14. CM Process Improvement and the International Space Station Program (ISSP)

    NASA Technical Reports Server (NTRS)

    Stephenson, Ginny

    2007-01-01

    This viewgraph presentation reviews the Configuration Management (CM) process improvements planned and undertaken for the International Space Station Program (ISSP). It reviews the 2004 findings and recommendations and the progress towards their implementation.

  15. New Horizons: Bridge to the Beginning - to Pluto and Beyond

    NASA Astrophysics Data System (ADS)

    Weir, H. M.; Hallau, K. G.; Seaton, P.; Beisser, K.; New Horizons Education; Public Outreach Team

    2010-12-01

    Launched on Jan. 19, 2006, NASA’s New Horizons mission to Pluto and the Kuiper Belt will help us understand worlds at the edge of our solar system by making the first reconnaissance of Pluto and Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. However, New Horizons’ closest approach to Pluto will not occur until July 14, 2015, and the majority of the craft's time over the next 5 years will be spent in "hibernation." The Education and Public Outreach (EPO) team, however, will not be hibernating as we wait for New Horizons to reach its destination. With three distinct tools-- Educator Fellows, online learning modules and a planetarium program--the team seeks to excite and engage teachers, students and the public with information about the journey to Pluto and beyond. In the past year, the specially selected educators who participate as New Horizons Educator Fellows have trained more than 1,000 teachers across the U.S. on the New Horizons mission and the science behind it. Thousands more students, parents, educators, and citizens have learned about New Horizons from the mission's scientists, engineers and outreach professionals. New Horizons Fellows also distribute another EPO tool: online learning modules. These classroom-ready learning modules consist of educator guides, student handouts, detailed activities, and potential adaptations for students with special needs or disabilities. Some also offer online interactives to convey complex and dynamic concepts. The modules are web-accessible for both students and teachers, and are aligned with relevant national standards. The third tool is a highly visual way to engage the general public and supplement educational programs: a planetarium program that highlights the New Horizons mission from launch to destination Pluto. This program focuses on the engineering design of the spacecraft, with a focus on the concept of the electromagnetic spectrum. In the unique environment

  16. Risk of Malignancy in Thyroid Nodules 4 cm or Larger

    PubMed Central

    2017-01-01

    Background Several authors have questioned the accuracy of fine-needle aspiration cytology (FNAC) in large nodules. Some surgeons recommend thyroidectomy for nodules ≥4 cm even in the setting of benign FNAC, due to increased risk of malignancy and increased false negative rates in large thyroid nodules. The goal of our study was to evaluate if thyroid nodule size is associated with risk of malignancy, and to evaluate the false negative rate of FNAC for thyroid nodules ≥4 cm in our patient population. Methods This is a retrospective study of 85 patients with 101 thyroid nodules, who underwent thyroidectomy for thyroid nodules measuring ≥4 cm. Results The overall risk of malignancy in nodules ≥4 cm was 9.9%. Nodule size was not associated with risk of malignancy (odds ratio, 1.02) after adjusting for nodule consistency, age, and sex (P=0.6). The false negative rate for FNAC was 0%. Conclusion Nodule size was not associated with risk of malignancy in nodules ≥4 cm in our patient population. FNAC had a false negative rate of 0. Patients with thyroid nodules ≥4 cm and benign cytology should not automatically undergo thyroidectomy. PMID:28181427

  17. Neutron-Spin Resonance in the Optimally Electron-Doped Superconductor Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4-{delta}}

    SciTech Connect

    Zhao Jun; Li Shiliang; Dai Pengcheng; Freeman, Paul G.; Onose, Y.; Tokura, Y.

    2007-07-06

    We use inelastic neutron scattering to probe magnetic excitations of an optimally electron-doped superconductor Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4-{delta}} above and below its superconducting transition temperature T{sub c}=25 K. In addition to gradually opening a spin pseudogap at the antiferromagnetic ordering wave vector Q=(1/2,1/2,0), the effect of superconductivity is to form a resonance centered also at Q=(1/2,1/2,0) but at energies above the spin pseudogap. The intensity of the resonance develops like a superconducting order parameter, similar to those for hole-doped superconductors and electron-doped Pr{sub 0.88}LaCe{sub 0.12}CuO{sub 4}. The resonance is therefore a general phenomenon of cuprate superconductors, and must be fundamental to the mechanism of high-T{sub c} superconductivity.

  18. Resonance in Optimally Electron-Doped Superconductor Nd1.85Ce0.15CuO4−?

    SciTech Connect

    Zhao, Jun; Dai, Pengcheng; Li, Shiliang; Freeman, Paul G.; Onose, Y,.; Tokura, Y.

    2007-01-01

    We use inelastic neutron scattering to probe magnetic excitations of an optimally electron-doped superconductor Nd1.85Ce0.15CuO4− above and below its superconducting transition temperature Tc = 25 K. In addition to gradually opening a spin pseudo gap at the antiferromagnetic ordering wavevector Q = (1/2, 1/2, 0), the effect of superconductivity is to form a resonance centered also at Q = (1/2, 1/2, 0) but at energies above the spin pseudo gap. The intensity of the resonance develops like a superconducting order parameter, similar to those for hole-doped superconductors and electron-doped Pr0.88LaCe0.12CuO4. The resonance is therefore a general phenomenon of cuprate superconductors, and must be fundamental to the mechanism of high-Tc superconductivity.

  19. Structural and electrical transport properties of La{sub 0.8}Sm{sub 0.05}K{sub 0.15}MnO{sub 3} manganites

    SciTech Connect

    Shaikh, M. W.; Mansuri, I.; Varshney, Dinesh

    2014-04-24

    Polycrystalline sample of single-phase La{sub 0.8}Sm{sub 0.05}K{sub 0.15}MnO{sub 3} perovskite compound have been synthesized by solid-state reaction route. X-ray diffraction patterns accompanied by Rietveld–refined crystal structure parameters reveal the rhombohedral structure with space group R 3C. Electrical resistivity infers transition from metallic to insulator phase at 537 K. The application of magnetic field of 8 T, suppresses the resistivity. The metallic resistivity is retraced by considering electron–phonon, electron–electron and electron-spin-fluctuation interactions while insulating behaviour is analysed with small polaron conduction model.

  20. Superspin glassy behaviour of La{sub 0.7}Ca{sub 0.3}Mn{sub 0.85}Al{sub 0.15}O{sub 3} thin film

    SciTech Connect

    Kumar, Manish; Choudhary, R. J. Shukla, D. K.; Phase, D. M.

    2014-07-21

    Here, we present the low temperature magnetic behaviour of epitaxial La{sub 0.7}Ca{sub 0.3}Mn{sub 0.85}Al{sub 0.15}O{sub 3} (LCMAO) thin film through a series of DC magnetic measurements. Overall behaviour inferred from the magnetization measurements indicate that the magnetic phases created due to Al doping induced inhomogeneous distribution of Mn{sup 3+} and Mn{sup 4+} ions and oxygen vacancies present in the system act like superspins, and the strong interaction among themselves results in the superspin glassy behaviour. Interactions among the superspins are marked by the aging and zero filed memory effects. The glassy magnetic phase in LCMAO is found to follow the hierarchical model of spin glasses.

  1. Degradation of hydration kinetics of proton-conducting Ba(Zr0.84Y0.15Cu0.01)O3-δ during conductivity-relaxation experiment

    NASA Astrophysics Data System (ADS)

    Choi, Sung Min; Lee, Jong-Heun; Hong, Jongsup; Yoon, Kyung Joong; Son, Ji-Won; Kim, Byung-Kook; Lee, Hae-Weon; Lee, Jong-Ho

    2016-11-01

    The chemical-diffusion and surface-exchange coefficients of a proton-conducting oxide, i.e., Ba(Zr0.84Y0.15Cu0.01)O3-δ upon a sudden change of water-vapor pressure at a fixed oxygen partial pressure are investigated via a conductivity relaxation technique. Conductivity relaxation during the hydration/dehydration process follows typical two-fold non-monotonic behavior that can be explained by decoupled chemical diffusion of H and O. However, the temperature dependence of the measured chemical-diffusion and surface-exchange coefficients is significantly different depending on the direction of the temperature change. In this study, we attempt to identify the origin of these unusual behaviors during the conductivity relaxation experiment via thorough microstructural and compositional analyses on sample surface.

  2. 63Cu nuclear magnetic resonance study of Pr(1.85)Ce(0.15)Cu(1-x)Ni(x)O(4): Ni-induced spin density oscillation and modification of the low energy spin fluctuations.

    PubMed

    Williams, G V M; Jurkutat, M; Rybicki, D; Haase, J

    2011-02-23

    We report the results from a (63)Cu nuclear magnetic resonance (NMR) study of the electron-doped high temperature superconducting cuprate (HTSC) Pr(1.85)Ce(0.15)Cu(1-x)Ni(x)O(4). We find that Ni induces a magnetic broadening of the (63)Cu NMR spectra that can be interpreted in terms of an induced spin density oscillation about the Ni site, similar to that reported from (63)Cu NMR measurements on the hole-doped HTSCs when Zn is partially substituted for Cu. There is also an additional temperature-dependent contribution to the (63)Cu spin-lattice relaxation rate that can be interpreted in terms of an Ni-induced modification of the low energy spin fluctuations. Furthermore, the spin fluctuations are intrinsically spatially inhomogeneous and additional inhomogeneities are induced by Ni.

  3. F19 NMR study of the coupling between 4f and itinerant electrons in the pnictide superconductors SmFeAsO1-xFx (0.15≤x≤0.2)

    NASA Astrophysics Data System (ADS)

    Prando, G.; Carretta, P.; Rigamonti, A.; Sanna, S.; Palenzona, A.; Putti, M.; Tropeano, M.

    2010-03-01

    F19 NMR measurements in SmFeAsO1-xFx , for 0.15≤x≤0.2 , are presented. The nuclear spin-lattice relaxation rate 1/T1 increases upon cooling with a trend analogous to the one already observed in CeCu5.2Au0.8 , a quasi-two-dimensional heavy-fermion intermetallic compound with an antiferromagnetic ground state. In particular, the behavior of the relaxation rate either in SmFeAsO1-xFx or in CeCu5.2Au0.8 can be described in the framework of the self-consistent renormalization theory for weakly itinerant electron systems. Remarkably, no effect of the superconducting transition on F19 1/T1 is detected, a phenomenon which can hardly be explained within a single band model.

  4. The ageing and de-ageing behaviour of (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 lead-free piezoelectric ceramics

    NASA Astrophysics Data System (ADS)

    Zhang, Yichi; Glaum, Julia; Ehmke, Matthias C.; Bowman, Keith J.; Blendell, John E.; Hoffman, Mark J.

    2015-09-01

    Ageing behaviour usually occurs in acceptor-doped piezoelectric materials (e.g., hard lead zirconate titanate) and exhibits the development of a pinched or shifted hysteresis loop over time. Although no pinched hysteresis loop was observed for lead-free (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 material, this study showed that the piezoelectric properties change over time in the poled state. The shift of the hysteresis loop along the electric field axis and the development of asymmetry in strain and permittivity hysteresis loop were observed during the ageing process. The origin of this ageing behaviour is proposed to be local defect dipoles and the migration of the charged defects to the grain boundaries. The reorientation of the defect dipole contributes to a fast but unstable ageing mechanism in this material while the migration of the charged defects contributes to a slow but more stable mechanism.

  5. Evidence for Retarded Pr ƒ; Hybridization and Tc Suppression in Y 1- xPr xSr 2Cu 2.85Re 0.15O 7

    NASA Astrophysics Data System (ADS)

    Das, A.; Castro, L. F.; Zelenay, I.; Suryanarayanan, R.

    1995-08-01

    We report on the preparation, X-ray diffraction, ac susceptibility, resistivity, and thermopower of Y 1- xPr xSr 2Cu 2.85Re 0.15O 7. We find that superconductivity is sustained up to a Pr concentration of 70%, which is greater than the 55% normally found in the Y 1- xPr xBa 2Cu 3O 7 system. It is proposed that the presence of Sr retards the Pr ƒ hybridization and the Tc suppression. It is pointed out that a better knowledge of structural and defect chemistry of Pr-containing cuprates is essential before applying any definite model to account for the data, as was also proposed earlier by R. Fehrenbacher and T. M. Rice ( Phys. Rev. Lett. 70, 3471, 1993).

  6. Two regimes behavior in the resistivity of the La 1.85Sr 0.15Cu 1- xLi xO 4 system: A signature of different electronic states for holes

    NASA Astrophysics Data System (ADS)

    García, S.; Musa, J. E.; Giordanengo, B.; Baggio-Saitovitch, E. M.

    1998-01-01

    The variations of the normal-state resistivity and the superconducting transition temperature Tc of the La 1.85Sr 0.15(Cu 1- xLi x)O 4 system for 0 ≤ x ≤ 0.05 reveal a two regimes behavior, with x ≅ 0.03 being the critical concentration for a transition from a delocalized state, with a reduction of the resistivity values while Tc remains unchanged, to an early stage of a spin compensation process, characterized by Tc suppression without broadening. Disorder at the CuO 2 planes is proposed to be the source of localization and Tc depletion, as supported by fitting of the normal-state curves according to different conduction models.

  7. Normal-state magnetic properties and their correlation with Tc suppression and the resistivity anomalies in the (La1-xPrx)1.85Sr0.15CuO4 series

    NASA Astrophysics Data System (ADS)

    Musa, J. E.; García, S.; Rothier de Amaral, M.; Salim de Amorim, H.; Giordanengo, B.; Baggio-Saitovitch, E. M.; Pagliuso, P. J. G.; Rettori, C.; Yelon, W. B.; Malik, S. K.

    1999-04-01

    We have investigated the normal-state anomalies observed in the magnetic and transport properties of the (La1-xPrx)1.85Sr0.15CuO4 system with 0⩽x⩽0.5. The resistivity curves showed an increasing deviation from linearity below ˜100 K. This behavior is properly accounted by a logarithmic term, whose coefficient C linearly increases with x. The normal-state magnetic susceptibility measurements evidenced a departure from the Pr3+ Curie-Weiss dependence in the same temperature range for which the resistivity anomaly occurs. A comprehensive picture of the conduction mechanism is presented in terms of a Kondo-like scattering of the mobile holes by the spin fluctuations.

  8. Electrical transport and giant magnetoresistance in La0.75Sr0.25Mn1-xCrxO3 (0.15, 0.20 and 0.25) manganite oxide.

    PubMed

    Dhahri, Ah; Jemmali, M; Dhahri, E; Hlil, E K

    2015-03-28

    We have investigated the influence of chromium (Cr) doping on the magneto-electrical properties of polycrystalline samples La0.75Sr0.25Mn1-xCrxO3 (0.15 ≤ x ≤ 0.25), prepared by the sol-gel method. Comparison of experimental data with the theoretical models shows that in the metal-ferromagnetic region, the electrical behavior of the three samples is quite well described by a theory based on electron-electron, electron-phonon and electron-magnon scattering and Kondo-like spin dependent scattering. For the high temperature paramagnetic insulating regime, the adiabatic small polaron hopping (SPH) model is found to fit well the experimental curves.

  9. Magnetic susceptibility investigation of Bose-glass state in Ni0.85Cd0.15Cl2-4SC(NH2)2 at ultra-low temperatures

    NASA Astrophysics Data System (ADS)

    Yin, L.; Xia, J. S.; Sullivan, N. S.; Zapf, V. S.; Paduan-Filho, A.; Yu, R.; Roscilde, T.

    2012-12-01

    We report measurements of the AC susceptibility of a site-diluted quantum magnet Ni0.85Cd0.15Cl2-4SC(NH2)2 (15% Cd-doped dichloro-tetrakis-thiourea-Nickel, or Cd-DTN) down to 10 mK Below a crossover temperature Tcr ≍ 100 ~ 200mK, we find that the critical fields Hc for Bose-Einstein condensation obey the scaling relation |Hc(T)-Hc(0)| ~ Tα, with a novel and universal scaling exponent α ≍ 0.9, which is in agreement with numerical results from a theoretical model. Our findings provide strong evidence of the existence of a Bose glass phase in Cd-DTN, and they display a quantitative signature of the transition between a Bose glass and a Bose Einstein condensate.

  10. Evaluation on residual stress in Bi3.15(Eu0.7Nd0.15)Ti3O12 polycrystalline ferroelectric thin film by using the orientation average method

    NASA Astrophysics Data System (ADS)

    Wei, Y.; Cheng, H. B.; Wang, X. Y.; Zheng, X. J.

    2012-12-01

    We propose an orientation average method to evaluate residual stresses in polycrystalline thin films. Bi3.15(Eu0.7Nd0.15)Ti3O12 was used to verify our approach, with films prepared by metal organic decomposition at various annealing temperatures. The mechanical properties and microstructure were characterized by nanoindentation and X-ray diffraction. The thin film annealed at 600 °C has the largest residual compressive stress of 771 MPa among all thin films. The residual stresses are evaluated by the proposed method and traditional sin2ψ method, and the maximum distinction is less than 6.43%, demonstrating that the proposed method is reliable and convenient to evaluate residual stress in polycrystalline thin films.

  11. Highly CO2-Tolerant Cathode for Intermediate-Temperature Solid Oxide Fuel Cells: Samarium-Doped Ceria-Protected SrCo0.85Ta0.15O3-δ Hybrid.

    PubMed

    Li, Mengran; Zhou, Wei; Zhu, Zhonghua

    2017-01-25

    Susceptibility to CO2 is one of the major challenges for the long-term stability of the alkaline-earth-containing cathodes for intermediate-temperature solid oxide fuel cells. To alleviate the adverse effects from CO2, we incorporated samarium-stabilized ceria (SDC) into a SrCo0.85Ta0.15O3-δ (SCT15) cathode by either mechanical mixing or a wet impregnation method and evaluated their cathode performance stability in the presence of a gas mixture of 10% CO2, 21% O2, and 69% N2. We observed that the CO2 tolerance of the hybrid cathode outperforms the pure SCT15 cathode by over 5 times at 550 °C. This significant enhancement is likely attributable to the low CO2 adsorption and reactivity of the SDC protective layer, which are demonstrated through thermogravimetric analysis, energy-dispersive spectroscopy, and electrical conductivity study.

  12. Superconducting properties of single crystalline FeTe1-xSex (x = 0, 0.15, 0.25, 0.35, 0.40 and 0.50)

    NASA Astrophysics Data System (ADS)

    Sudesh; Kumar, R.; Varma, G. D.

    2015-06-01

    In this paper we have grown single crystalline samples of Se-doped FeTe compound using self-flux technique and studied the structural and electrical transport properties of the as-grown crystals. The samples have been grown with compositions FeTe1-xSex (x = 0, 0.15, 0.25, 0.35, 0.40 and 0.50). The as-grown samples are then investigated for their structural and superconducting properties by means of X-ray diffraction and physical property measurements. The XRD results of powdered samples reveal a single (tetragonal) phase with space group symmetry P4/nmm for all the samples. The lattice parameters are observed to reduce with increase of Se-doping at Te-site. Highest Hc2(0) (˜180 T) value has been observed for FeTe0.5Se0.5 sample.

  13. Li distribution characterization in Li-ion batteries positive electrodes containing LixNi0.8Co0.15Al0.05O2 secondary particles (0.75 ⩽ x ⩽ 1.0)

    NASA Astrophysics Data System (ADS)

    Mima, K.; Gonzalez-Arrabal, R.; Azuma, H.; Yamazaki, A.; Okuda, C.; Ukyo, Y.; Sawada, H.; Fujita, K.; Kato, Y.; Perlado, J. M.; Nakai, S.

    2012-11-01

    The elemental distribution of as-received (non-charged) and charged Li-ion battery positive electrodes containing LixNi0.8Co0.15Al0.05O2 (0.75 ⩽ x ⩽ 1.0) microparticles as active material is characterized by combining μ-PIXE and μ-PIGE techniques. PIGE measurements evidence that the Li distribution is inhomogeneous (existence of Li-rich and Li-depleted regions) in as-received electrodes corresponding with the distribution of secondary particles but it is homogeneous within the studied individual secondary micro-particles. The dependence of the Li distribution on electrode thickness and on charging conditions is characterized by measuring the Li distribution maps in specifically fabricated cross-sectional samples. These data show that decreasing the electrode thickness down to 35 μm and charging the batteries at slow rate give rise to more homogeneous Li depth profiles.

  14. Discussion on event horizon and quantum ergosphere of evaporating black holes in a tunnelling framework

    SciTech Connect

    Zhang Jingyi; Zhao Zheng

    2011-03-15

    In this paper, with the Parikh-Wilczek tunnelling framework the positions of the event horizon of the Vaidya black hole and the Vaidya-Bonner black hole are calculated, respectively. We find that the event horizon and the apparent horizon of these two black holes correspond, respectively, to the two turning points of the Hawking radiation tunnelling barrier. That is, the quantum ergosphere coincides with the tunnelling barrier. Our calculation also implies that the Hawking radiation comes from the apparent horizon.

  15. 76 FR 78016 - Deepwater Horizon Oil Spill; Draft Phase I Early Restoration Plan and Environmental Assessment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-15

    ....S. Fish and Wildlife Service, Interior Deepwater Horizon Oil Spill; Draft Phase I Early Restoration... from the Deepwater Horizon Oil Spill, the Federal and State natural resource trustee agencies (Trustees... resources and services injured or lost as a result of the Deepwater Horizon oil spill, which occurred on...

  16. 78 FR 33431 - Deepwater Horizon Oil Spill; Notice of Intent To Prepare a Programmatic Environmental Impact...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-04

    ... Deepwater Horizon Oil Spill; Notice of Intent To Prepare a Programmatic Environmental Impact Statement for a... state natural resource trustees for the Deepwater Horizon oil spill (Trustees) intend to prepare a PEIS... discharges from the rig and from the wellhead on the seabed. The Deepwater Horizon oil spill is the...

  17. 77 FR 23741 - DEEPWATER HORIZON Oil Spill; Final Phase I Early Restoration Plan and Environmental Assessment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-20

    ... Fish and Wildlife Service DEEPWATER HORIZON Oil Spill; Final Phase I Early Restoration Plan and... DEEPWATER HORIZON Oil Spill (Framework Agreement), notice is hereby given that ] the Federal and State... the DEEPWATER HORIZON oil spill, which occurred on or about April 20, 2010, in the Gulf of Mexico....

  18. On further generalization of the rigidity theorem for spacetimes with a stationary event horizon or a compact Cauchy horizon

    NASA Astrophysics Data System (ADS)

    Rácz, István

    2000-01-01

    A rigidity theorem that applies to smooth electrovacuum spacetimes which represent either (A) an asymptotically flat stationary black hole or (B) a cosmological spacetime with a compact Cauchy horizon ruled by closed null geodesics was given in a recent paper by Friedrich et al (1999 Commun. Math. Phys. 204 691-707). Here we enlarge the framework of the corresponding investigations by allowing the presence of other types of matter fields. In the first part the matter fields are involved merely implicitly via the assumption that the dominant energy condition is satisfied. In the second part Einstein-Klein-Gordon (EKG), Einstein-[non-Abelian]-Higgs (E[nA]H), Einstein-[Maxwell]-Yang-Mills-dilaton (E[M]YMd) and Einstein-Yang-Mills-Higgs (EYMH) systems are studied. The black hole event horizon or, respectively, the compact Cauchy horizon of the considered spacetimes is assumed to be a smooth non-degenerate null hypersurface. It is proved that there exists a Killing vector field in a one-sided neighbourhood of the horizon in EKG, E[nA]H, E[M]YMd and EYMH spacetimes. This Killing vector field is normal to the horizon, moreover, the associated matter fields are also shown to be invariant with respect to it. The presented results provide generalizations of the rigidity theorems of Hawking (for case A) and of Moncrief and Isenberg (for case B) and, in turn, they strengthen the validity of both the black hole rigidity scenario and the strong cosmic censor conjecture of classical general relativity.

  19. CM Carbonaceous Chondrite Lithologies and Their Space Exposure Ages

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Gregory, Timothy; Takenouchi, Atsushi; Nishiizumi, Kunihiko; Trieman, Alan; Berger, Eve; Le, Loan; Fagan, Amy; Velbel, Michael; Imae, Naoya; Yamaguchi, Akira

    2015-01-01

    The CMs are the most commonly falling C chondrites, and therefore may be a major component of C-class asteroids, the targets of several current and future space missions. Previous work [1] has concluded that CM chondrites fall into at least four distinct cosmic ray space exposure (CRE) age groups (0.1 million years, 0.2 million years, 0.6 million years and greater than 2.0 million years), an unusually large number, but the meaning of these groupings is unclear. It is possible that these meteorites came from different parent bodies which broke up at different times, or instead came from the same parent body which underwent multiple break-up events, or a combination of these scenarios, or something else entirely. The objective of this study is to investigate the diversity of lithologies which make up CM chondrites, in order to determine whether the different exposure ages correspond to specific, different CM lithologies, which permit us to constrain the history of the CM parent body(ies). We have already reported significant petrographic differences among CM chondrites [2-4]. We report here our new results.

  20. Weakly Isolated horizons: first order actions and gauge symmetries

    NASA Astrophysics Data System (ADS)

    Corichi, Alejandro; Reyes, Juan D.; Vukašinac, Tatjana

    2017-04-01

    The notion of Isolated Horizons has played an important role in gravitational physics, being useful from the characterization of the endpoint of black hole mergers to (quantum) black hole entropy. With an eye towards a canonical formulation we consider general relativity in terms of connection and vierbein variables and their corresponding first order actions. We focus on two main issues: (i) The role of the internal gauge freedom that exists, in the consistent formulations of the action principle, and (ii) the role that a 3  +  1 canonical decomposition has in the allowed internal gauge freedom. More concretely, we clarify in detail how the requirement of having well posed variational principles compatible with general weakly isolated horizons (WIHs) as internal boundaries does lead to a partial gauge fixing in the first order descriptions used previously in the literature. We consider the standard Hilbert–Palatini action together with the Holst extension (needed for a consistent 3  +  1 decomposition), with and without boundary terms at the horizon. We show in detail that, for the complete configuration space—with no gauge fixing—, while the Palatini action is differentiable without additional surface terms at the inner WIH boundary, the more general Holst action is not. The introduction of a surface term at the horizon—that renders the action for asymptotically flat configurations differentiable—does make the Holst action differentiable, but only if one restricts the configuration space and partially reduces the internal Lorentz gauge. For the second issue at hand, we show that upon performing a 3  +  1 decomposition and imposing the time gauge, there is a further gauge reduction of the Hamiltonian theory in terms of Ashtekar–Barbero variables to a U(1)-gauge theory on the horizon. We also extend our analysis to the more restricted boundary conditions of (strongly) isolated horizons as inner boundary. We show that even when

  1. A model for sunspot associated emission at 6 cm wavelength

    NASA Technical Reports Server (NTRS)

    Alissandrakis, C. E.; Kundu, M. R.; Lantos, P.

    1980-01-01

    Two-dimensional maps of total intensity and circular polarization of a sunspot region at 6 cm have been calculated using a simple model for the chromosphere-corona transition region and observations of the longitudinal component of the photospheric magnetic field. The calculations are in good agreement with the high resolution observations of the same sunspot region at 6 cm, obtained with the Westerbork Synthesis Radio Telescope. It is shown that the 6 cm radiation is predominantly due to gyroresonance absorption process at the second and third harmonics of the gyrofrequency (H = 900-600 G). Estimates of the conductive flux and the electron density in the transition region above the sunspot are also given.

  2. VLA observations of Uranus at 1. 3-20 cm

    SciTech Connect

    De Pater, I.; Gulkis, S.

    1988-08-01

    Observations of Uranus, obtained with resolution 0.5-1.2 arcsec at wavelengths 1.3, 2, 6, and 20 cm using the A and B configurations of the VLA in June-July 1982, October 1983, and February 1984, are reported. The disk-averaged brightness temperatures (DABTs) are determined by model fitting, and the results are presented in extensive graphs and contour maps and characterized in detail. Findings discussed include: (1) an overall spectrum which is relatively flat above 6 cm, (2) 1.3-6-cm brightness which is concentrated nearer to the pole than to the subsolar point, and (3) small changes in DABT from 1982 to 1983/1984 (consistent with an explanation based on a pole-equator temperature gradient). 16 references.

  3. Differentiating CDM and baryon isocurvature models with 21 cm fluctuations

    SciTech Connect

    Kawasaki, Masahiro; Sekiguchi, Toyokazu; Takahashi, Tomo E-mail: sekiguti@icrr.u-tokyo.ac.jp

    2011-10-01

    We discuss how one can discriminate models with cold dark matter (CDM) and baryon isocurvature fluctuations. Although current observations such as cosmic microwave background (CMB) can severely constrain the fraction of such isocurvature modes in the total density fluctuations, CMB cannot differentiate CDM and baryon ones by the shapes of their power spectra. However, the evolution of CDM and baryon density fluctuations are different for each model, thus it would be possible to discriminate those isocurvature modes by extracting information on the fluctuations of CDM/baryon itself. We discuss that observations of 21 cm fluctuations can in principle differentiate these modes and demonstrate to what extent we can distinguish them with future 21 cm surveys. We show that, when the isocurvature mode has a large blue-tilted initial spectrum, 21 cm surveys can clearly probe the difference.

  4. High-resolution comparative modeling with RosettaCM.

    PubMed

    Song, Yifan; DiMaio, Frank; Wang, Ray Yu-Ruei; Kim, David; Miles, Chris; Brunette, Tj; Thompson, James; Baker, David

    2013-10-08

    We describe an improved method for comparative modeling, RosettaCM, which optimizes a physically realistic all-atom energy function over the conformational space defined by homologous structures. Given a set of sequence alignments, RosettaCM assembles topologies by recombining aligned segments in Cartesian space and building unaligned regions de novo in torsion space. The junctions between segments are regularized using a loop closure method combining fragment superposition with gradient-based minimization. The energies of the resulting models are optimized by all-atom refinement, and the most representative low-energy model is selected. The CASP10 experiment suggests that RosettaCM yields models with more accurate side-chain and backbone conformations than other methods when the sequence identity to the templates is greater than ∼15%.

  5. Enhancement of critical current density in a Ca0.85La0.15Fe(As0.92Sb0.08)2 superconductor with T c = 47 K through 3 MeV proton irradiation

    NASA Astrophysics Data System (ADS)

    Park, Akiyoshi; Mine, Akinori; Yamada, Tatsuhiro; Ohtake, Fumiaki; Akiyama, Hiroki; Sun, Yue; Pyon, Sunseng; Tamegai, Tsuyoshi; Kitahama, Yutaka; Mizukami, Tasuku; Kudo, Kazutaka; Nohara, Minoru; Kitamura, Hisashi

    2016-05-01

    We examine the critical current density (J c) of Ca{}1-xLa x Fe(As{}1-ySb y )2, a 112-type iron-based superconductor (IBS) with {T}{{c}} = 47 K, via magneto-optical imaging and magnetization measurements. We assert that the large self-field J c of 2.2× {10}6 A cm- 2 at 2 K is a strong indication that it is a bulk superconductor with spatially homogeneous superconductivity. A 2.8-fold enhancement in J c to 6.2× {10}6 A cm- 2 was achieved through artificially engineering pinning centers by irradiating 3 MeV protons with a total dosage of 1.0× {10}16 {{cm}}-2. The results not only demonstrate the potential of 112-type IBSs for application but also enrich the current understanding of the role of artificial defects in IBSs.

  6. Cycle life testing of 8-cm mercury ion thruster cathodes

    NASA Technical Reports Server (NTRS)

    Wintucky, E. G.

    1976-01-01

    Two main cathodes have successfully completed 2800 and 1980 cycles and three neutralizers, 3928, 3050, and 2850 cycles in ongoing cycle life tests of flight-type cathode-isolator-vaporizer and neutralizer-isolator-vaporizer assemblies for the 4.45 mN 8-cm Hg ion thruster system. Each cycle included one hour of cathode operation. Starting and operating conditions simulated those expected in a typical auxiliary propulsion mission duty cycle. This paper presents the cycle life test results and also results of an insert comparison test which led to the selection of a rolled foil insert type for the 8-cm Engineering Model Thruster cathodes.

  7. Cycle life testing of 8-cm mercury ion thruster cathodes

    NASA Technical Reports Server (NTRS)

    Wintucky, E. G.

    1976-01-01

    Two main cathodes have successfully completed 2800 and 1980 cycles and three neutralizers, 3928, 3050, and 2850 cycles in ongoing cycle life tests of flight-type cathode-isolator-vaporizer and neutralizer-isolator-vaporizer assemblies for the 4.45 mN 8-cm Hg ion thruster system. Each cycle included one hour of cathode operation. Starting and operating conditions simulated those expected in a typical auxiliary propulsion mission duty cycle. The cycle life test results are presented along with results of an insert comparison test which led to the selection of a rolled foil insert type for the 8-cm Engineering Model Thruster cathodes.

  8. 21 cm radiation: A new probe of fundamental physics

    NASA Astrophysics Data System (ADS)

    Khatri, Rishi; Wandelt, Benjamin D.

    2010-11-01

    New low frequency radio telescopes currently being built open up the possibility of observing the 21 cm radiation from redshifts 200 > z > 30, also known as the dark ages, see Furlanetto, Oh, & Briggs(2006) for a review. At these high redshifts, Cosmic Microwave Background (CMB) radiation is absorbed by neutral hydrogen at its 21 cm hyperfine transition. This redshifted 21 cm signal thus carries information about the state of the early Universe and can be used to test fundamental physics. The 21 cm radiation probes a volume of the early Universe on kpc scales in contrast with CMB which probes a surface (of some finite thickness) on Mpc scales. Thus there is many orders of more information available, in principle, from the 21 cm observations of dark ages. We have studied the constraints these observations can put on the variation of fundamental constants (Khatri & Wandelt(2007)). Since the 21 cm signal depends on atomic physics it is very sensitive to the variations in the fine structure constant and can place constraints comparable to or better than the other astrophysical experiments (Δα/α= < 10-5) as shown in Figure 1. Making such observations will require radio telescopes of collecting area 10 - 106 km2 compared to ~ 1 km2 of current telescopes, for example LOFAR. We should also expect similar sensitivity to the electron to proton mass ratio. One of the challenges in observing this 21 cm cosmological signal is the presence of the synchrotron foregrounds which is many orders of magnitude larger than the cosmological signal but the two can be separated because of their different statistical nature (Zaldarriaga, Furlanetto, & Hernquist(2004)). Terrestrial EM interference from radio/TV etc. and Earth's ionosphere poses problems for telescopes on ground which may be solved by going to the Moon and there are proposals for doing so, one of which is the Dark Ages Lunar Interferometer (DALI). In conclusion 21 cm cosmology promises a large wealth of data and provides

  9. WSRC Am/Cm Stabilization Program - Cylindrical Induction Melter Studies

    SciTech Connect

    Henderson, W.A.

    1999-02-17

    1.1.1 Kilogram quantities of Americium and Curium isotopes (Am/Cm) have been produced at the U.S. Department of Energy (DOE), Savannah River Site (SRS), Aiken, South Carolina. These highly radioactive isotopes have both government and commercial value and are currently stored as a nitric acid solution at the Savannah River Site. The material represents the largest source term in the F canyon at SRS. It is proposed that the Am/Cm material be vitrified to stabilize the material for long term, recoverable storage. This paper reviews the progress made during the process development phase of this program using the Cylindrical Induction Melter.

  10. Evidence for live 247Cm in the early solar system

    USGS Publications Warehouse

    Tatsumoto, M.; Shimamura, T.

    1980-01-01

    Variations of the 238U/235U ratio in the Allende meteorite, ranging from -35% to + 19%, are interpreted as evidence of live 247Cm in the early Solar System. The amounts of these and other r-products in the Solar System indicate values of (9,000??3,000) Myr for the age of the Galaxy and ??? 8 Myr for the time between the end of nucleosynthesis and the formation of meteoritic grains. Three possible explanations are presented for the different values of the latter time period which are indicated by the decay products of 247Cm, 26Al, 244Pu and 129I. ?? 1980 Nature Publishing Group.

  11. Increased capabilities of the 30-cm diameter Hg ion thruster

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.; Hawkins, C. E.

    1979-01-01

    Some space flight missions require advanced ion thrusters which operate at conditions much different than those for which the baseline 30-cm Hg thruster was developed. Results of initial tests of a 30-cm Hg thruster with two and three grid ion accelerating systems, operated at higher values of both thrust and power and over a greater range of specific impulse than the baseline conditions are presented. Thruster lifetime at increased input power was evaluated both by extended tests and real time spectroscopic measurements.

  12. Inert gas test of two 12-cm magnetostatic thrusters

    NASA Technical Reports Server (NTRS)

    Ramsey, W. D.

    1982-01-01

    Comparative performance tests were conducted with 12 cm line and ring magnetic cusp thrusters. Shell anode and magnetoelectrostatic containment boundary anode configurations were evaluated with each magnet array. The best performance was achieved with the 12-cm ring cusp-shell anode configuration. Argon operation of this configuration produced 65-81 percent mass utilization efficiency at 170-208 watts/single-charged-equivalent (SCE) ampere beam. Xenon test results showed 75-95 percent utilization at 162-188 watts/SCE ampere beam.

  13. The Complexity and Challenges of the ICD-9-CM to ICD-10-CM Transition in Emergency Departments

    PubMed Central

    Krive, Jacob; Patel, Mahatkumar; Gehm, Lisa; Mackey, Mark; Kulstad, Erik; Li, Jianrong ‘John’; Lussier, Yves A.; Boyd, Andrew D.

    2015-01-01

    Beginning October 2015, the Center for Medicare and Medicaid Services (CMS) will require medical providers to utilize the vastly expanded ICD-10-CM system. Despite wide availability of information and mapping tools for the next generation of the ICD classification system, some of the challenges associated with transition from ICD-9-CM to ICD-10-CM are not well understood. To quantify the challenges faced by emergency physicians, we analyzed a subset of a 2010 Illinois Medicaid database of emergency department ICD-9-CM codes, seeking to determine the accuracy of existing mapping tools in order to better prepare emergency physicians for the change to the expanded ICD-10-CM system. We found that 27% of 1,830 codes represented convoluted multidirectional mappings. We then analyzed the convoluted transitions and found 8% of total visit encounters (23% of the convoluted transitions) were clinically incorrect. The ambiguity and inaccuracy of these mappings may impact the work flow associated with the translation process and affect the potential mapping between ICD codes and CPT (Current Procedural Codes) codes, which determine physician reimbursement. PMID:25863652

  14. New perspectives for European climate services: HORIZON2020

    NASA Astrophysics Data System (ADS)

    Bruning, Claus; Tilche, Andrea

    2014-05-01

    The developing of new end-to-end climate services was one of the core priorities of 7th Framework for Research and Technological Development of the European Commission and will become one of the key strategic priorities of Societal Challenge 5 of HORIZON2020 (the new EU Framework Programme for Research and Innovation 2014-2020). Results should increase the competitiveness of European businesses, and the ability of regional and national authorities to make effective decisions in climate-sensitive sectors. In parallel, the production of new tailored climate information should strengthen the resilience of the European society to climate change. In this perspective the strategy to support and foster the underpinning science for climate services in HORIZON2020 will be presented.

  15. The Exploration of the Pluto System by New Horizons

    NASA Astrophysics Data System (ADS)

    Stern, S. Alan; NASA New Horizons Team

    2016-01-01

    The Pluto system was recently explored by NASA's New Horizons spacecraft, making closest approach on 14 July 2015. Pluto's surface displays diverse landforms, terrain ages, albedos, colors, and composition gradients. Evidence is found for a water-ice crust, geologically young surface units, surface ice convection, wind streaks, volatile transport, and glacial flow. Pluto's atmosphere is highly extended, with trace hydrocarbons, a global haze layer, and a surface pressure near 10 microbars. Pluto's diverse surface geology and long term activity raise fundamental questions about how small planets remain active many billions of years (Gyr) after formation. Pluto's large moon Charon displays tectonics and evidence for a heterogeneous crustal composition; its North Pole displays puzzling dark terrain. Small satellites Hydra and Nix have higher albedos than expected. In this talk I will summarize the objectives of the New Horizons mission, its scientific payload, and survey key results obtained to date about Pluto and its system of moons.

  16. A horizon scan of global conservation issues for 2012.

    PubMed

    Sutherland, William J; Aveling, Ros; Bennun, Leon; Chapman, Eleanor; Clout, Mick; Côté, Isabelle M; Depledge, Michael H; Dicks, Lynn V; Dobson, Andrew P; Fellman, Liz; Fleishman, Erica; Gibbons, David W; Keim, Brandon; Lickorish, Fiona; Lindenmayer, David B; Monk, Kathryn A; Norris, Kenneth; Peck, Lloyd S; Prior, Stephanie V; Scharlemann, Jörn P W; Spalding, Mark; Watkinson, Andrew R

    2012-01-01

    Our aim in conducting annual horizon scans is to identify issues that, although currently receiving little attention, may be of increasing importance to the conservation of biological diversity in the future. The 15 issues presented here were identified by a diverse team of 22 experts in horizon scanning, and conservation science and its application. Methods for identifying and refining issues were the same as in two previous annual scans and are widely transferable to other disciplines. The issues highlight potential changes in climate, technology and human behaviour. Examples include warming of the deep sea, increased cultivation of perennial grains, burning of Arctic tundra, and the development of nuclear batteries and hydrokinetic in-stream turbines.

  17. Large superconformal near-horizons from M-theory

    NASA Astrophysics Data System (ADS)

    Kelekci, Ö.; Lozano, Y.; Montero, J.; O'Colgáin, E.; Park, M.

    2016-04-01

    We report on a classification of supersymmetric solutions to 11D supergravity with S O (2 ,2 )×S O (3 ) isometry, which are AdS /CFT dual to 2D CFTs with N =(0 ,4 ) supersymmetry. We recover the Maldacena, Strominger, Witten near-horizon with small superconformal symmetry and identify a class of AdS3×S2×S2×C Y2 geometries with emergent large superconformal symmetry. This exhausts known compact geometries. Compactification of M-theory on C Y2 results in a vacuum of 7D supergravity with large superconformal symmetry, providing a candidate near-horizon for an extremal black hole and a potential new setting to address microstates.

  18. Digital Signal Processing for the Event Horizon Telescope

    NASA Astrophysics Data System (ADS)

    Weintroub, Jonathan

    2015-08-01

    A broad international collaboration is building the Event Horizon Telescope (EHT). The aim is to test Einstein’s theory of General Relativity in one of the very few places it could break down: the strong gravity regime right at the edge of a black hole. The EHT is an earth-size VLBI array operating at the shortest radio wavelengths, that has achieved unprecedented angular resolution of a few tens of μarcseconds. For nearby super massive black holes (SMBH) this size scale is comparable to the Schwarzschild Radius, and emission in the immediate neighborhood of the event horizon can be directly observed. We give an introduction to the science behind the CASPER-enabled EHT, and outline technical developments, with emphasis on the secret sauce of high speed signal processing.

  19. A horizon scan for species conservation by zoos and aquariums.

    PubMed

    Gusset, Markus; Fa, John E; Sutherland, William J

    2014-01-01

    We conducted the first horizon scan for zoos and aquariums to identify the 10 most important emerging issues for species conservation. This involved input from more than 100 experts from both the wider conservation community and the world zoo and aquarium community. Some of the issues are globally important: diseases, zoonoses, and biosecurity issues; new (communication) technologies; global water shortage and food insecurity; developing economies and markets for wildlife consumption; changes in wildlife population dynamics; and political instability and conflicts. Other issues are more specific to zoos and aquariums: need for extractive reserves; space shortage in zoos and aquariums; need for metapopulation management; and demand for caring of more species in zoos and aquariums. We also identified some broad approaches to these issues. Addressing the emerging issues identified in our horizon scan will further increase the contribution of the world zoo and aquarium community to global biodiversity conservation.

  20. Direct Measurements of Black Holes with the Event Horizon Telescope

    NASA Astrophysics Data System (ADS)

    Fish, Vincent L.; Doeleman, S. S.

    2011-09-01

    The Event Horizon Telescope (EHT) is an array of existing (sub)millimeter telescopes that uses the technique of Very Long Baseline Interferometry (VLBI) to achieve angular resolutions measured in tens of microarcseconds. For the super massive black hole in the Galactic Center (Sgr A*) and in the elliptical galaxy M87, the EHT has detected emission on the scale of the event horizon. In this presentation we describe details of measurements already made with the EHT. We also describe future observations that will allow us to probe orbits of the accretion disk around the black hole in Sgr A* in a manner that is complementary to information obtained from X-ray observations. Emission models of Sgr A* that include the strong gravitational lensing near the black hole indicate that future high-frequency VLBI observations may lead to tests of the "no-hair" theorem, which states that a black hole may be completely characterized by its mass and spin.