47 CFR 15.221 - Operation in the band 525-1705 kHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation in the band 525-1705 kHz. 15.221... kHz. (a) Carrier current systems and transmitters employing a leaky coaxial cable as the radiating antenna may operate in the band 525-1705 kHz provided the field strength levels of the radiated emissions...

47 CFR 15.221 - Operation in the band 525-1705 kHz.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 1 2012-10-01 2012-10-01 false Operation in the band 525-1705 kHz. 15.221... kHz. (a) Carrier current systems and transmitters employing a leaky coaxial cable as the radiating antenna may operate in the band 525-1705 kHz provided the field strength levels of the radiated emissions...

47 CFR 15.221 - Operation in the band 525-1705 kHz.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 1 2014-10-01 2014-10-01 false Operation in the band 525-1705 kHz. 15.221... kHz. (a) Carrier current systems and transmitters employing a leaky coaxial cable as the radiating antenna may operate in the band 525-1705 kHz provided the field strength levels of the radiated emissions...

47 CFR 15.221 - Operation in the band 525-1705 kHz.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 1 2013-10-01 2013-10-01 false Operation in the band 525-1705 kHz. 15.221... kHz. (a) Carrier current systems and transmitters employing a leaky coaxial cable as the radiating antenna may operate in the band 525-1705 kHz provided the field strength levels of the radiated emissions...

V and K-band Mass-Luminosity Relations for M dwarf Stars

NASA Astrophysics Data System (ADS)

Benedict, G. Fritz; Henry, Todd J.; McArthur, Barbara; Franz, Otto G.; Wasserman, Lawrence H.; Dieterich, Sergio

2015-01-01

Applying Hubble Space Telescope Fine Guidance Sensor astrometric techniques developed to establish relative orbits for binary stars (Franz et al. 1998, AJ, 116, 1432), determine masses of binary components (Benedict et al. 2001, AJ, 121, 1607), and measure companion masses of exoplanet host stars (McArthur et al. 2010, ApJ, 715, 1203), we derive masses with an average 2.1% error for 24 components of 12 M dwarf binary star systems. Masses range 0.08 to 0.40 solar masses. With these we update the lower Main Sequence V-band Mass-Luminosity Relation first shown in Henry et al. (1999, ApJ, 512, 864). We demonstrate that a Mass-Luminosity Relation in the K-band has far less scatter than in the V-band. For the eight binary components for which we have component magnitude differences in the K-band the RMS residual drops from 0.5 magnitude in the V-band to 0.05 magnitude in the K-band. These relations can be used to estimate the masses of the ubiquitous red dwarfs that account for 75% of all stars, to an accuracy of 5%, which is much better than ever before.

The USNO-UKIRT K-band Hemisphere Survey

NASA Astrophysics Data System (ADS)

Dahm, Scott; Bruursema, Justice; Munn, Jeffrey A.; Vrba, Fred J.; Dorland, Bryan; Dye, Simon; Kerr, Tom; Varricatt, Watson; Irwin, Mike; Lawrence, Andy; McLaren, Robert; Hodapp, Klaus; Hasinger, Guenther

2018-01-01

We present initial results from the United States Naval Observatory (USNO) and UKIRT K-band Hemisphere Survey (U2HS), currently underway using the Wide Field Camera (WFCAM) installed on UKIRT on Maunakea. U2HS is a collaborative effort undertaken by USNO, the Institute for Astronomy, University of Hawaii, the Cambridge Astronomy Survey Unit (CASU) and the Wide Field Astronomy Unit (WFAU) in Edinburgh. The principal objective of the U2HS is to provide continuous northern hemisphere K-band coverage over a declination range of δ=0o – +60o by combining over 12,700 deg2 of new imaging with the existing UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS), Galactic Plane Survey (GPS) and Galactic Cluster Survey (GCS). U2HS will achieve a 5-σ point source sensitivity of K~18.4 mag (Vega), over three magnitudes deeper than the Two Micron All Sky Survey (2MASS). In this contribution we discuss survey design, execution, data acquisition and processing, photometric calibration and quality control. The data obtained by the U2HS will be made publicly available through the Wide Field Science Archive (WSA) maintained by the WFAU.

Coulomb excitation of the K π= 8⁻ isomeric band in 178Hf

DOE PAGES

Napiorkovsk, P. J.; Srebrny, J.; Czosnyka, T.; ...

2001-12-01

The Coulomb excitation experiment on the 178Hf was performed using 650 MeV beam of 136Xe. The first observation of discrete transitions in the K π = 8 - isomeric band. Coulomb excited from K π = 0+ ground state, is reported. The possible mechanisms of El coupling of the ground state band and the isomeric band is discussed.

Ku and K band GaN High Power Amplifier MMICs

DTIC Science & Technology

2017-03-20

end Ku-band HPA operates from 13 to 14.5 GHz and delivers 48 Watts of output power with 43% PAE. A high-end Ku-band HPA operates from 15.5 to 18 GHz and...delivers 25 Watts of output power with 45% PAE. A K-band HPA operates from 19.5 to 22 GHz and delivers 18 Watts of output power with 29% PAE...15.5 and 18 GHz. The circuit is a three-stage reactively-matched amplifier. A photograph of a fabricated high-end Ku-band GaN HPA is shown as an

NASA's K/Ka-Band Broadband Aeronautical Terminal for Duplex Satellite Video Communications

NASA Technical Reports Server (NTRS)

Densmore, A.; Agan, M.

1994-01-01

JPL has recently begun the development of a Broadband Aeronautical Terminal (BAT) for duplex video satellite communications on commercial or business class aircraft. The BAT is designed for use with NASA's K/Ka-band Advanced Communications Technology Satellite (ACTS). The BAT system will provide the systems and technology groundwork for an eventual commercial K/Ka-band aeronautical satellite communication system. With industry/government partnerships, three main goals will be addressed by the BAT task: 1) develop, characterize and demonstrate the performance of an ACTS based high data rate aeronautical communications system; 2) assess the performance of current video compression algorithms in an aeronautical satellite communication link; and 3) characterize the propagation effects of the K/Ka-band channel for aeronautical communications.

Interface band alignment in high-k gate stacks

NASA Astrophysics Data System (ADS)

Eric, Bersch; Hartlieb, P.

2005-03-01

In order to successfully implement alternate high-K dielectric materials into MOS structures, the interface properties of MOS gate stacks must be better understood. Dipoles that may form at the metal/dielectric and dielectric/semiconductor interfaces make the band offsets difficult to predict. We have measured the conduction and valence band densities of states for a variety MOS stacks using in situ using inverse photoemission (IPE) and photoemission spectroscopy (PES), respectively. Results obtained from clean and metallized (with Ru or Al) HfO2/Si, SiO2/Si and mixed silicate films will be presented. IPE indicates a shift of the conduction band minimum (CBM) to higher energy (i.e. away from EF) with increasing SiO2. The effect of metallization on the location of band edges depends upon the metal species. The addition of N to the dielectrics shifts the CBM in a way that is thickness dependent. Possible mechanisms for these observed effects will be discussed.

Adaptive mesh refinement and front-tracking for shear bands in an antiplane shear model

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

Garaizar, F.X.; Trangenstein, J.

1998-09-01

In this paper the authors describe a numerical algorithm for the study of hear-band formation and growth in a two-dimensional antiplane shear of granular materials. The algorithm combines front-tracking techniques and adaptive mesh refinement. Tracking provides a more careful evolution of the band when coupled with special techniques to advance the ends of the shear band in the presence of a loss of hyperbolicity. The adaptive mesh refinement allows the computational effort to be concentrated in important areas of the deformation, such as the shear band and the elastic relief wave. The main challenges are the problems related to shearmore » bands that extend across several grid patches and the effects that a nonhyperbolic growth rate of the shear bands has in the refinement process. They give examples of the success of the algorithm for various levels of refinement.« less

The K-Band Quasar Luminosity Function from an SDSS and UKIDSS Matched Catalog

NASA Astrophysics Data System (ADS)

Peth, Michael; Ross, N. P.; Schneider, D. P.

2010-01-01

We match the 1,015,082 quasars from the Sloan Digital Sky Survey (SDSS) DR6 Photometric Quasar catalog to the UKIRT Infrared Digital Sky Survey (UKIDSS) Large Area Survey (LAS) DR3 to produce a catalog of 130,827 objects with optical (ugriz) and infrared (YJHK) measurements over an area of 1,200 sq. deg. A matching radius of 1'’ is used; the positional standard deviations of SDSS DR6 quasars and UKIDSS LAS is δRA = 0.137'’ and δDec = 0.131''. The catalog contains 74,351 K-band detections and 42,133 objects have coverage in all four NIR bands. In addition to the catalog, we present optical and NIR color-redshift and color-color plots. The photometric vs. spectroscopic redshift plots demonstrate how unreliable high reported photometric redshifts can be. This forces us to focus on z4.6 quasars are compared to our highest redshift objects. The giK color-color plot demonstrates that stellar contamination only affects a small sample of the objects. Distributions for Y,J,H,K and i-bands reveal insights into the flux limits in each magnitude. We investigate the distribution of redshifts from different data sets and investigate the legitimacy of certain measured photometric redshift regions. For in-depth analysis, we focus on the 300 sq. deg area equatorial SDSS region designated as Stripe 82. We measure the observed K-band quasar luminosity function (QLF) for a subset of 9,872, z<2.2 objects. We find the shape of the K-band QLF is very similar to that of the optical QLF, over the considered redshift ranges. Our calculated K-Band QLFs broadly match previous optical QLFs calculated from the SDSS and 2SLAQ QSO surveys and should provide important constraints linking unobscured optical quasars to Mid-Infrared detected, dusty and obscured AGNs at high-redshift.

In-beam spectroscopy of the k π=0- bands in230 236U

NASA Astrophysics Data System (ADS)

Zeyen, P.; Ackermann, B.; Dämmrich, U.; Euler, K.; Grafen, V.; Günther, C.; Herzog, P.; Marten-Tölle, M.; Prillwitz, B.; Tölle, R.; Lauterbach, Ch.; Maier, H. J.

1987-12-01

The K π=0- bands in even uranium nuclei were studied in the compound reactions231Pa( p, 2 n)230U,230, 232Th( α,2 n)232, 234U and236U( d, pn)236U. In-beam γ-rays were measured in coincidence with conversion-electrons, which were detected with an iron-free orange spectrometer. The negative-parity levels are observed up to intermediate spins ( I<13-). In addition, the 1- and 3- levels in230U were confirmed by a decay study with an isotope separated230Pa source. For the heavier isotopes ( A≥232) the properties of the K π=0- bands (energies and γ-branchings) are consistent with a vibrational character of these bands. For230U the K π=0- band lies at rather low energy ( E(1-)=367 keV), and the level spacings within this band are very similar to those of the isotones228Th and226Ra, which might indicate the onset of a stable octupole deformation.

High-spatial-resolution K-band Imaging of Select K2 Campaign Fields

NASA Astrophysics Data System (ADS)

Colón, Knicole D.; Howell, Steve B.; Ciardi, David R.; Barclay, Thomas

2017-12-01

NASA's K2 mission began observing fields along the ecliptic plane in 2014. Each observing campaign lasts approximately 80 days, during which high-precision optical photometry of select astrophysical targets is collected by the Kepler spacecraft. Due to the 4 arcsec pixel scale of the Kepler photometer, significant blending between the observed targets can occur (especially in dense fields close to the Galactic plane). We undertook a program to use the Wide Field Camera (WFCAM) on the 3.8 m United Kingdom InfraRed Telescope (UKIRT) to collect high-spatial-resolution near-infrared images of targets in select K2 campaign fields, which we report here. These 0.4 arcsec resolution K-band images offer the opportunity to perform a variety of science, including vetting exoplanet candidates by identifying nearby stars blended with the target star and estimating the size, color, and type of galaxies observed by K2.

An adaptive band selection method for dimension reduction of hyper-spectral remote sensing image

NASA Astrophysics Data System (ADS)

Yu, Zhijie; Yu, Hui; Wang, Chen-sheng

2014-11-01

Hyper-spectral remote sensing data can be acquired by imaging the same area with multiple wavelengths, and it normally consists of hundreds of band-images. Hyper-spectral images can not only provide spatial information but also high resolution spectral information, and it has been widely used in environment monitoring, mineral investigation and military reconnaissance. However, because of the corresponding large data volume, it is very difficult to transmit and store Hyper-spectral images. Hyper-spectral image dimensional reduction technique is desired to resolve this problem. Because of the High relation and high redundancy of the hyper-spectral bands, it is very feasible that applying the dimensional reduction method to compress the data volume. This paper proposed a novel band selection-based dimension reduction method which can adaptively select the bands which contain more information and details. The proposed method is based on the principal component analysis (PCA), and then computes the index corresponding to every band. The indexes obtained are then ranked in order of magnitude from large to small. Based on the threshold, system can adaptively and reasonably select the bands. The proposed method can overcome the shortcomings induced by transform-based dimension reduction method and prevent the original spectral information from being lost. The performance of the proposed method has been validated by implementing several experiments. The experimental results show that the proposed algorithm can reduce the dimensions of hyper-spectral image with little information loss by adaptively selecting the band images.

Luminosity and surface brightness distribution of K-band galaxies from the UKIDSS Large Area Survey

NASA Astrophysics Data System (ADS)

Smith, Anthony J.; Loveday, Jon; Cross, Nicholas J. G.

2009-08-01

We present luminosity and surface-brightness distributions of 40111 galaxies with K-band photometry from the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS), Data Release 3 and optical photometry from Data Release 5 of the Sloan Digital Sky Survey (SDSS). Various features and limitations of the new UKIDSS data are examined, such as a problem affecting Petrosian magnitudes of extended sources. Selection limits in K- and r-band magnitude, K-band surface brightness and K-band radius are included explicitly in the 1/Vmax estimate of the space density and luminosity function. The bivariate brightness distribution in K-band absolute magnitude and surface brightness is presented and found to display a clear luminosity-surface brightness correlation that flattens at high luminosity and broadens at low luminosity, consistent with similar analyses at optical wavelengths. Best-fitting Schechter function parameters for the K-band luminosity function are found to be M* - 5 logh = -23.19 +/- 0.04,α = -0.81 +/- 0.04 and φ* = (0.0166 +/- 0.0008)h3Mpc-3, although the Schechter function provides a poor fit to the data at high and low luminosity, while the luminosity density in the K band is found to be j = (6.305 +/- 0.067) × 108LsolarhMpc-3. However, we caution that there are various known sources of incompleteness and uncertainty in our results. Using mass-to-light ratios determined from the optical colours, we estimate the stellar mass function, finding good agreement with previous results. Possible improvements are discussed that could be implemented when extending this analysis to the full LAS.

K/Ka-band Antenna for Broadband Aeronautical Mobile Application

NASA Technical Reports Server (NTRS)

Densmore, A.

1994-01-01

The Jet Propulsion Laboratory (JPL) has recently begun the development of a Broadband Aeronauical Terminal (BAT) for duplex video satellite communications on commercial or business class aircraft. The BAT is designed for use with NASA's K/Ka-band Advanced Communications Technology Satellite (ACTS).

Adaptable interaction between aquaporin-1 and band 3 reveals a potential role of water channel in blood CO2 transport.

PubMed

Hsu, Kate; Lee, Ting-Ying; Periasamy, Ammasi; Kao, Fu-Jen; Li, Li-Tzu; Lin, Chuang-Yu; Lin, Hui-Ju; Lin, Marie

2017-10-01

Human CO 2 respiration requires rapid conversion between CO 2 and HCO 3 - Carbonic anhydrase II facilitates this reversible reaction inside red blood cells, and band 3 [anion exchanger 1 (AE1)] provides a passage for HCO 3 - flux across the cell membrane. These 2 proteins are core components of the CO 2 transport metabolon. Intracellular H 2 O is necessary for CO 2 /HCO 3 - conversion. However, abundantly expressed aquaporin 1 (AQP1) in erythrocytes is thought not to be part of band 3 complexes or the CO 2 transport metabolon. To solve this conundrum, we used Förster resonance energy transfer (FRET) measured by fluorescence lifetime imaging (FLIM-FRET) and identified interaction between aquaporin-1 and band 3 at a distance of 8 nm, within the range of dipole-dipole interaction. Notably, their interaction was adaptable to membrane tonicity changes. This suggests that the function of AQP1 in tonicity response could be coupled or correlated to its function in band 3-mediated CO 2 /HCO 3 - exchange. By demonstrating AQP1 as a mobile component of the CO 2 transport metabolon, our results uncover a potential role of water channel in blood CO 2 transport and respiration.-Hsu, K., Lee, T.-Y., Periasamy, A., Kao, F.-J., Li, L.-T., Lin, C.-Y., Lin, H.-J., Lin, M. Adaptable interaction between aquaporin-1 and band 3 reveals a potential role of water channel in blood CO 2 transport. © FASEB.

47 CFR 73.30 - Petition for authorization of an allotment in the 1605-1705 kHz band.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the 1605-1705 kHz band. 73.30 Section 73.30 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... authorization of an allotment in the 1605-1705 kHz band. (a) Any party interested in operating an AM broadcast station on one of the ten channels in the 1605-1705 kHz band must file a petition for the establishment of...

47 CFR 15.219 - Operation in the band 510-1705 kHz.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 1 2014-10-01 2014-10-01 false Operation in the band 510-1705 kHz. 15.219... kHz. (a) The total input power to the final radio frequency stage (exclusive of filament or heater... ground lead (if used) shall not exceed 3 meters. (c) All emissions below 510 kHz or above 1705 kHz shall...

47 CFR 15.219 - Operation in the band 510-1705 kHz.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 1 2012-10-01 2012-10-01 false Operation in the band 510-1705 kHz. 15.219... kHz. (a) The total input power to the final radio frequency stage (exclusive of filament or heater... ground lead (if used) shall not exceed 3 meters. (c) All emissions below 510 kHz or above 1705 kHz shall...

47 CFR 15.219 - Operation in the band 510-1705 kHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation in the band 510-1705 kHz. 15.219... kHz. (a) The total input power to the final radio frequency stage (exclusive of filament or heater... ground lead (if used) shall not exceed 3 meters. (c) All emissions below 510 kHz or above 1705 kHz shall...

47 CFR 15.219 - Operation in the band 510-1705 kHz.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 1 2011-10-01 2011-10-01 false Operation in the band 510-1705 kHz. 15.219... kHz. (a) The total input power to the final radio frequency stage (exclusive of filament or heater... ground lead (if used) shall not exceed 3 meters. (c) All emissions below 510 kHz or above 1705 kHz shall...

47 CFR 15.219 - Operation in the band 510-1705 kHz.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 1 2013-10-01 2013-10-01 false Operation in the band 510-1705 kHz. 15.219... kHz. (a) The total input power to the final radio frequency stage (exclusive of filament or heater... ground lead (if used) shall not exceed 3 meters. (c) All emissions below 510 kHz or above 1705 kHz shall...

A Survey Study of U.S. Collegiate and K-12 Steel Band Directors' Attitudes Relating to Steel Band Curriculum and Pedagogy

ERIC Educational Resources Information Center

Haskett, Brandon L.

2016-01-01

Steel bands were introduced into U.S. schools and universities during the 1950s and 1960s. There are now more than 600 U.S. school and university steel bands. The range of teaching methods and repertoire choices must be examined to more fully understand the variety of steel band traditions present in K-12 schools and universities. U.S. steel band…

Dual-Band Operation of a Microstrip Patch Antenna on a Duroid 5870 Substrate for Ku- and K-Bands

PubMed Central

Islam, M. M.; Islam, M. T.; Faruque, M. R. I.

2013-01-01

The dual-band operation of a microstrip patch antenna on a Duroid 5870 substrate for Ku- and K-bands is presented. The fabrication of the proposed antenna is performed with slots and a Duroid 5870 dielectric substrate and is excited by a 50 Ω microstrip transmission line. A high-frequency structural simulator (HFSS) is used which is based on the finite element method (FEM) in this research. The measured impedance bandwidth (2 : 1 VSWR) achieved is 1.07 GHz (15.93 GHz–14.86 GHz) on the lower band and 0.94 GHz (20.67–19.73 GHz) on the upper band. A stable omnidirectional radiation pattern is observed in the operating frequency band. The proposed prototype antenna behavior is discussed in terms of the comparisons of the measured and simulated results. PMID:24385878

Dual-band operation of a microstrip patch antenna on a Duroid 5870 substrate for Ku- and K-bands.

PubMed

Islam, M M; Islam, M T; Faruque, M R I

2013-01-01

The dual-band operation of a microstrip patch antenna on a Duroid 5870 substrate for Ku- and K-bands is presented. The fabrication of the proposed antenna is performed with slots and a Duroid 5870 dielectric substrate and is excited by a 50 Ω microstrip transmission line. A high-frequency structural simulator (HFSS) is used which is based on the finite element method (FEM) in this research. The measured impedance bandwidth (2 : 1 VSWR) achieved is 1.07 GHz (15.93 GHz-14.86 GHz) on the lower band and 0.94 GHz (20.67-19.73 GHz) on the upper band. A stable omnidirectional radiation pattern is observed in the operating frequency band. The proposed prototype antenna behavior is discussed in terms of the comparisons of the measured and simulated results.

A multi-band environment-adaptive approach to noise suppression for cochlear implants.

PubMed

Saki, Fatemeh; Mirzahasanloo, Taher; Kehtarnavaz, Nasser

2014-01-01

This paper presents an improved environment-adaptive noise suppression solution for the cochlear implants speech processing pipeline. This improvement is achieved by using a multi-band data-driven approach in place of a previously developed single-band data-driven approach. Seven commonly encountered noisy environments of street, car, restaurant, mall, bus, pub and train are considered to quantify the improvement. The results obtained indicate about 10% improvement in speech quality measures.

Adaptive Fuzzy Hysteresis Band Current Controller for Four-Wire Shunt Active Filter

NASA Astrophysics Data System (ADS)

Hamoudi, F.; Chaghi, A.; Amimeur, H.; Merabet, E.

2008-06-01

This paper presents an adaptive fuzzy hysteresis band current controller for four-wire shunt active power filters to eliminate harmonics and to compensate reactive power in distribution systems in order to keep currents at the point of common coupling sinusoidal and in phase with the corresponding voltage and the cancel neutral current. The conventional hysteresis band known for its robustness and its advantage in current controlled applications is adapted with a fuzzy logic controller to change the bandwidth according to the operating point in order to keep the frequency modulation at tolerable limits. The algorithm used to identify the reference currents is based on the synchronous reference frame theory (dqγ). Finally, simulation results using Matlab/Simulink are given to validate the proposed control.

Multi-Band (K- Q- and E-Band) Multi-Tone Millimeter-Wave Frequency Synthesizer for Radio Wave Propagation Studies

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.

2014-01-01

This paper presents the design and test results of a multi-band multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). These studies would enable the design of robust multi-Gbps data rate space-to-ground satellite communication links. Lastly, the architecture for a compact multi-tone beacon transmitter, which includes a high frequency synthesizer, a polarizer, and a conical horn antenna, has been investigated for a notional CubeSat based space-to-ground radio wave propagation experiment.

Steerable K/Ka-Band Antenna For Land-Mobile Satellite Applications

NASA Technical Reports Server (NTRS)

Densmore, Arthur; Jamnejad, Vahraz; Woo, Kenneth

1994-01-01

Prototype steerable microwave antenna tracks and communicates with geostationary satellite. Designed to mount on roof of vehicle and only 10 cm tall. K/Ka-band antenna rugged and compact to suit rooftop mobile operating environment. More-delicate signal-processing and control equipment located inside vehicle.

Commissioning and first light results of an L'-band vortex coronagraph with the Keck II adaptive optics NIRC2 science instrument

NASA Astrophysics Data System (ADS)

Femenía Castellá, Bruno; Serabyn, Eugene; Mawet, Dimitri; Absil, Olivier; Wizinowich, Peter; Matthews, Keith; Huby, Elsa; Bottom, Michael; Campbell, Randy; Chan, Dwight; Carlomagno, Brunella; Cetre, Sylvain; Defrère, Denis; Delacroix, Christian; Gomez Gonzalez, Carlos; Jolivet, Aïssa; Karlsson, Mikael; Lanclos, Kyle; Lilley, Scott; Milner, Steven; Ngo, Henry; Reggiani, Maddalena; Simmons, Julia; Tran, Hien; Vargas Catalan, Ernesto; Wertz, Olivier

2016-07-01

On March 2015 an L'-band vortex coronagraph based on an Annular Groove Phase Mask made up of a diamond sub-wavelength grating was installed on NIRC2 as a demonstration project. This vortex coronagraph operates in the L' band not only in order to take advantage from the favorable star/planet contrast ratio when observing beyond the K band, but also to exploit the fact that the Keck II Adaptive Optics (AO) system delivers nearly extreme adaptive optics image quality (Strehl ratios values near 90%) at 3.7μm. We describe the hardware installation of the vortex phase mask during a routine NIRC2 service mission. The success of the project depends on extensive software development which has allowed the achievement of exquisite real-time pointing control as well as further contrast improvements by using speckle nulling to mitigate the effect of static speckles. First light of the new coronagraphic mode was on June 2015 with already very good initial results. Subsequent commissioning nights were interlaced with science nights by members of the VORTEX team with their respective scientific programs. The new capability and excellent results so far have motivated the VORTEX team and the Keck Science Steering Committee (KSSC) to offer the new mode in shared risk mode for 2016B.

Limitations to Dual Frequency Ionosphere Corrections for Frequency Switched K-Q-Band Observations with the VLBA

NASA Technical Reports Server (NTRS)

Lanyi, Gabor; Gordon, David; Sovers, Ojars J.

2004-01-01

A series of VLBA experiments were carried out at K and Q bands for astrometry and imaging within the KQ VLBI Survey Collaboration. The paired K and Q observations of each source are separated by approximately 3 minutes of time. We investigate the delay effect of the ionosphere between K and Q bands involving the interscan separation. This differential delay effect is intermixed with the differential fluctuation effect of the troposphere.

The Keck/OSIRIS Nearby AGN Survey (KONA). I. The Nuclear K-band Properties of Nearby AGN

NASA Astrophysics Data System (ADS)

Müller-Sánchez, F.; Hicks, E. K. S.; Malkan, M.; Davies, R.; Yu, P. C.; Shaver, S.; Davis, B.

2018-05-01

We introduce the Keck OSIRIS Nearby AGN survey (KONA), a new adaptive optics-assisted integral-field spectroscopic survey of Seyfert galaxies. KONA permits at ∼0.″1 resolution a detailed study of the nuclear kinematic structure of gas and stars in a representative sample of 40 local bona fide active galactic nucleus (AGN). KONA seeks to characterize the physical processes responsible for the coevolution of supermassive black holes and galaxies, principally inflows and outflows. With these IFU data of the nuclear regions of 40 Seyfert galaxies, the KONA survey will be able to study, for the first time, a number of key topics with meaningful statistics. In this paper we study the nuclear K-band properties of nearby AGN. We find that the K-band (2.1 μm) luminosities of the compact Seyfert 1 nuclei are correlated with the hard X-ray luminosities, implying a non-stellar origin for the majority of the continuum emission. The best-fit correlation is log L K = 0.9log L 2–10 keV + 4 over three orders of magnitude in both K-band and X-ray luminosities. We find no strong correlation between 2.1 μm luminosity and hard X-ray luminosity for the Seyfert 2 galaxies. The spatial extent and spectral slope of the Seyfert 2 galaxies indicate the presence of nuclear star formation and attenuating material (gas and dust), which in some cases is compact and in some galaxies extended. We detect coronal-line emission in 36 galaxies and for the first time in 5 galaxies. Finally, we find 4/20 galaxies that are usually classified as Seyfert 2 based on their optical spectra exhibit a broad component of Brγ emission, and one galaxy (NGC 7465) shows evidence of a double nucleus. Based on observations at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial support of the W. M

Broadband MMIC LNAs for ALMA Band 2+3 With Noise Temperature Below 28 K

NASA Astrophysics Data System (ADS)

Cuadrado-Calle, David; George, Danielle; Fuller, Gary A.; Cleary, Kieran; Samoska, Lorene; Kangaslahti, Pekka; Kooi, Jacob W.; Soria, Mary; Varonen, Mikko; Lai, Richard; Mei, Xiaobing

2017-05-01

Recent advancements in transistor technology, such as the 35 nm InP HEMT, allow for the development of monolithic microwave integrated circuit (MMIC) low noise amplifiers (LNAs) with performance properties that challenge the hegemony of SIS mixers as leading radio astronomy detectors at frequencies as high as 116 GHz. In particular, for the Atacama Large Millimeter and Submillimeter Array (ALMA), this technical advancement allows the combination of two previously defined bands, 2 (67-90 GHz) and 3 (84-116 GHz), into a single ultra-broadband 2+3 (67-116 GHz) receiver. With this purpose, we present the design, implementation, and characterization of LNAs suitable for operation in this new ALMA band 2+3, and also a different set of LNAs for ALMA band 2. The best LNAs reported here show a noise temperature less than 250 K from 72 to 104 GHz at room temperature, and less than 28 K from 70 to 110 GHz at cryogenic ambient temperature of 20 K. To the best knowledge of the authors, this is the lowest wideband noise ever published in the 70-110 GHz frequency range, typically designated as W-band.

The Properties of Outer Retinal Band Three Investigated With Adaptive-Optics Optical Coherence Tomography.

PubMed

Jonnal, Ravi S; Gorczynska, Iwona; Migacz, Justin V; Azimipour, Mehdi; Zawadzki, Robert J; Werner, John S

2017-09-01

Optical coherence tomography's (OCT) third outer retinal band has been attributed to the zone of interdigitation between RPE cells and cone outer segments. The purpose of this paper is to investigate the structure of this band with adaptive optics (AO)-OCT. Using AO-OCT, images were obtained from two subjects. Axial structure was characterized by measuring band 3 thickness and separation between bands 2 and 3 in segmented cones. Lateral structure was characterized by correlation of band 3 with band 2 and comparison of their power spectra. Band thickness and separation were also measured in a clinical OCT image of one subject. Band 3 thickness ranged from 4.3 to 6.4 μm. Band 2 correlations ranged between 0.35 and 0.41 and power spectra of both bands confirmed peak frequencies that agree with histologic density measurements. In clinical images, band 3 thickness was between 14 and 19 μm. Measurements of AO-OCT of interband distance were lower than our corresponding clinical OCT measurements. Band 3 originates from a structure with axial extent similar to a single surface. Correlation with band 2 suggests an origin within the cone photoreceptor. These two observations indicate that band 3 corresponds predominantly to cone outer segment tips (COST). Conventional OCT may overestimate both the thickness of band 3 and outer segment length.

The Properties of Outer Retinal Band Three Investigated With Adaptive-Optics Optical Coherence Tomography

PubMed Central

Jonnal, Ravi S.; Gorczynska, Iwona; Migacz, Justin V.; Azimipour, Mehdi; Zawadzki, Robert J.; Werner, John S.

2017-01-01

Purpose Optical coherence tomography's (OCT) third outer retinal band has been attributed to the zone of interdigitation between RPE cells and cone outer segments. The purpose of this paper is to investigate the structure of this band with adaptive optics (AO)-OCT. Methods Using AO-OCT, images were obtained from two subjects. Axial structure was characterized by measuring band 3 thickness and separation between bands 2 and 3 in segmented cones. Lateral structure was characterized by correlation of band 3 with band 2 and comparison of their power spectra. Band thickness and separation were also measured in a clinical OCT image of one subject. Results Band 3 thickness ranged from 4.3 to 6.4 μm. Band 2 correlations ranged between 0.35 and 0.41 and power spectra of both bands confirmed peak frequencies that agree with histologic density measurements. In clinical images, band 3 thickness was between 14 and 19 μm. Measurements of AO-OCT of interband distance were lower than our corresponding clinical OCT measurements. Conclusions Band 3 originates from a structure with axial extent similar to a single surface. Correlation with band 2 suggests an origin within the cone photoreceptor. These two observations indicate that band 3 corresponds predominantly to cone outer segment tips (COST). Conventional OCT may overestimate both the thickness of band 3 and outer segment length. PMID:28877320

On the role of covariance information for GRACE K-band observations in the Celestial Mechanics Approach

NASA Astrophysics Data System (ADS)

Bentel, Katrin; Meyer, Ulrich; Arnold, Daniel; Jean, Yoomin; Jäggi, Adrian

2017-04-01

The Astronomical Institute at the University of Bern (AIUB) derives static and time-variable gravity fields by means of the Celestial Mechanics Approach (CMA) from GRACE (level 1B) data. This approach makes use of the close link between orbit and gravity field determination. GPS-derived kinematic GRACE orbit positions, inter-satellite K-band observations, which are the core observations of GRACE, and accelerometer data are combined to rigorously estimate orbit and spherical harmonic gravity field coefficients in one adjustment step. Pseudo-stochastic orbit parameters are set up to absorb unmodeled noise. The K-band range measurements in along-track direction lead to a much higher correlation of the observations in this direction compared to the other directions and thus, to north-south stripes in the unconstrained gravity field solutions, so-called correlated errors. By using a full covariance matrix for the K-band observations the correlation can be taken into account. One possibility is to derive correlation information from post-processing K-band residuals. This is then used in a second iteration step to derive an improved gravity field solution. We study the effects of pre-defined covariance matrices and residual-derived covariance matrices on the final gravity field product with the CMA.

Free-end adaptive nudged elastic band method for locating transition states in minimum energy path calculation.

PubMed

Zhang, Jiayong; Zhang, Hongwu; Ye, Hongfei; Zheng, Yonggang

2016-09-07

A free-end adaptive nudged elastic band (FEA-NEB) method is presented for finding transition states on minimum energy paths, where the energy barrier is very narrow compared to the whole paths. The previously proposed free-end nudged elastic band method may suffer from convergence problems because of the kinks arising on the elastic band if the initial elastic band is far from the minimum energy path and weak springs are adopted. We analyze the origin of the formation of kinks and present an improved free-end algorithm to avoid the convergence problem. Moreover, by coupling the improved free-end algorithm and an adaptive strategy, we develop a FEA-NEB method to accurately locate the transition state with the elastic band cut off repeatedly and the density of images near the transition state increased. Several representative numerical examples, including the dislocation nucleation in a penta-twinned nanowire, the twin boundary migration under a shear stress, and the cross-slip of screw dislocation in face-centered cubic metals, are investigated by using the FEA-NEB method. Numerical results demonstrate both the stability and efficiency of the proposed method.

Adaptive phase k-means algorithm for waveform classification

NASA Astrophysics Data System (ADS)

Song, Chengyun; Liu, Zhining; Wang, Yaojun; Xu, Feng; Li, Xingming; Hu, Guangmin

2018-01-01

Waveform classification is a powerful technique for seismic facies analysis that describes the heterogeneity and compartments within a reservoir. Horizon interpretation is a critical step in waveform classification. However, the horizon often produces inconsistent waveform phase, and thus results in an unsatisfied classification. To alleviate this problem, an adaptive phase waveform classification method called the adaptive phase k-means is introduced in this paper. Our method improves the traditional k-means algorithm using an adaptive phase distance for waveform similarity measure. The proposed distance is a measure with variable phases as it moves from sample to sample along the traces. Model traces are also updated with the best phase interference in the iterative process. Therefore, our method is robust to phase variations caused by the interpretation horizon. We tested the effectiveness of our algorithm by applying it to synthetic and real data. The satisfactory results reveal that the proposed method tolerates certain waveform phase variation and is a good tool for seismic facies analysis.

An H-band Vector Vortex Coronagraph for the Subaru Coronagraphic Extreme-adaptive Optics System

NASA Astrophysics Data System (ADS)

Kühn, J.; Serabyn, E.; Lozi, J.; Jovanovic, N.; Currie, T.; Guyon, O.; Kudo, T.; Martinache, F.; Liewer, K.; Singh, G.; Tamura, M.; Mawet, D.; Hagelberg, J.; Defrere, D.

2018-03-01

The vector vortex is a coronagraphic imaging mode of the recently commissioned Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) platform on the 8 m Subaru Telescope. This multi-purpose high-contrast visible and near-infrared (R- to K-band) instrument is not only intended to serve as a VLT-class “planet-imager” instrument in the northern hemisphere, but also to operate as a technology demonstration testbed ahead of the ELTs-era, with a particular emphasis on small inner-working angle (IWA) coronagraphic capabilities. The given priority to small-IWA imaging led to the early design choice to incorporate focal-plane phase-mask coronagraphs. In this context, a test H-band vector vortex liquid crystal polymer waveplate was provided to SCExAO, to allow a one-to-one comparison of different small-IWA techniques on the same telescope instrument, before considering further steps. Here we present a detailed overview of the vector vortex coronagraph, from its installation and performances on the SCExAO optical bench, to the on-sky results in the extreme AO regime, as of late 2016/early 2017. To this purpose, we also provide a few recent on-sky imaging examples, notably high-contrast ADI detection of the planetary-mass companion κ Andromedae b, with a signal-to-noise ratio above 100 reached in less than 10 mn exposure time.

Adaptation of the By-Band randomized clinical trial to By-Band-Sleeve to include a new intervention and maintain relevance of the study to practice.

PubMed

Rogers, C A; Reeves, B C; Byrne, J; Donovan, J L; Mazza, G; Paramasivan, S; Andrews, R C; Wordsworth, S; Thompson, J; Blazeby, J M; Welbourn, R

2017-08-01

Recruitment into surgical RCTs can be threatened if new interventions available outside the trial compete with those being evaluated. Adapting the trial to include the new intervention may overcome this issue, yet this is not often done in surgery. This paper describes the challenges, rationale and methods for adapting an RCT to include a new intervention. The By-Band study was designed in the UK in 2009-2010 to compare the effectiveness of laparoscopic adjustable gastric band and Roux-en-Y gastric bypass for severe obesity. It contained a pilot phase to establish whether recruitment was possible, and the grant proposal specified that an adaptation to include sleeve gastrectomy would be considered if practice changed and recruitment was successful. Information on changing obesity surgery practice, updated evidence and expert opinion about trial design were used to inform the adaptation. The pilot phase recruited over 13 months in 2013-2014 and randomized 80 patients (79 anticipated). During this time, major changes in obesity practice in the UK were observed, with gastric band reducing from 32·6 to 15·8 per cent and sleeve gastrectomy increasing from 9·0 to 28·1 per cent. The evidence base had not changed markedly. The British Obesity and Metabolic Surgery Society and study oversight committees supported an adaptation to include sleeve gastrectomy, and a proposal to do so was approved by the funder. Adaptation of a two-group surgical RCT can allow evaluation of a third procedure and maintain relevance of the RCT to practice. It also optimizes the use of existing trial infrastructure to answer an additional important research question. Registration number: ISRCTN00786323 (http://www.isrctn.com/). © 2017 The Authors. BJS published by John Wiley & Sons Ltd on behalf of BJS Society Ltd.

The 64 meter antenna operation at K sub A band

NASA Technical Reports Server (NTRS)

Potter, P. D.

1980-01-01

The future potential of the 32 GHz K sub A band frequency region to planetary exploration, and the expected performance of the 64 m antenna network at 32 GHz is addressed. A modest level of noninterference upgrade work is assumed to achieve reasonable antenna aperture efficiency and alleviate antenna pointing difficulties. Electronic compensation of antenna aperture phasing errors is briefly considered as an alternative to the physical upgrade.

K-wire and tension band wire fixation in treating sternoclavicular joint dislocation.

PubMed

Chen, Qing-yu; Cheng, Shao-wen; Wang, Wei; Lin, Zhong-qin; Zhang, Wei; Kou, Dong-quan; Shen, Yue; Ying, Xiao-zhou; Cheng, Xiao-jie; Lv, Chuan-zhu; Peng, Lei

2011-02-01

To evaluate the feasibility and therapeutic effect of treating sternoclavicular joint dislocation by K-wire and tension band wire fixation, and to improve the safety and stability of this technique. This study consisted of 9 cases, 6 males and 3 females with the mean age of 25 years (range, 9-62 years). The causes were traffic accident in 7 cases, falling in 1 case and fight in 1 case. The duration from injury to operation was 2 hours to 7 days. There were 5 left dislocations and 4 right dislocations; 8 anterior dislocations and 1 posterior dislocation, including one combined with left scapular fracture and one with left olecranon fracture. Open reduction and internal fixation using K-wires and tension band wires were performed to treat dislocations. All patients were followed up for 6 to 24 months, 10 months on average. According to Rockwood's rating scale on postoperative sternoclavicular joint, 8 cases achieved excellent outcomes with an average score of 13.88, and the rest case achieved a good outcome with the score of 12. Anatomical reduction was obtained in all cases. There were no such postoperative complications as severe infection, injury to blood vessel and nerve, failure of fixation, etc. Patients were all satisfied with the anatomical reduction and functional recovery. The technique of K-wire and tension band wire fixation is safe, simple, effective, less invasive and has been successfully used in orthopedic surgery. It is effective in treating sternoclavicular joint dislocation though it has some disadvantages.

Deep galaxy counts in the K band with the Kech telescope

NASA Technical Reports Server (NTRS)

Djorgovski, S.; Soifer, B. T.; Pahre, M. A.; Larkin, J. E.; Smith, J. D.; Neugebauer, G.; Smail, I.; Matthews, K.; Hogg, D. W.; Blandford, R. D.

1995-01-01

We present deep galaxy counts in the K (lambda 2.2 micrometer) band, obtained at the W. M. Kech 10 m telescope. The data reach limiting magnitudes K approximately 24 mag, about 5 times deeper than the deepest published K-band images to date. The counts are performed in three small (approximately 1 min), widely separated high-latitude fields. Extensive Monte Carlo tests were used to derive the comleteness corrections and minimize photometric biases. The counts continue to rise, with no sign of a turnover, down to the limits of our data, with the logarithmic slope of d log N/dm = 0.315 +/- 0.02 between K = 20 and 24 mag. This implies a cumulative surface density of approximately 5 x 10(exp 5) galaxies/sq deg, or approximately 2 x 10(exp 10) over the entire sky, down to K = 24 mag. Our counts are in good agreement with, although slightly lower than, those from the Hawaii Deep Survey by Cowie and collaborators; the discrepancies may be due to the small differences in the aperture corrections. We compare our counts with some of the available theoretical predictions. The data do not require models with a high value of Omega(sub 0), but can be well fitted by models with no (or little) evolution, and cosmologies with a low value of Omega(sub 0). Given the uncertainties in the models, it may be premature to put useful constrains on the value of Omega(sub 0) from the counts alone. Optical-to-IR colors are computed, using CCD data obtaind previously at Palomar. We find a few red galaxies with (r-K) approximately greater than 5 mag, or (i-K) approximately greater than 5 mag; these may be ellipticals at z approximately 1. While the redshift distribution of galaxies in our counts is still unknown, the flux limits reached would allow us to detect unobscured L(sub *) galaxies out to substantial redshifts (z greater than 3?).

Lunar Reconnaissance Orbiter K-Band (26 GHz) Signal Analysis: Initial Study Results

NASA Astrophysics Data System (ADS)

Morabito, D. D.; Heckman, D.

2017-11-01

Lower frequency telemetry bands are becoming more limited in bandwidth due to increased competition between flight projects and other entities. Higher frequency bands offer significantly more bandwidth and hence the prospect of much higher data rates. Future or prospective flight projects considering higher frequency bands such as Ka-band (32 GHz) for deep-space and K-band (26 GHz) for near-Earth telemetry links are interested in past flight experience with available received data at these frequencies. Given that there is increased degradation due to the atmosphere at these higher frequencies, there is an effort to retrieve flight data of received signal strength to analyze performance under a variety of factors. Such factors include elevation angle, season, and atmospheric conditions. This article reports on the analysis findings of over 10 million observations of received signal strength of the Lunar Reconnaissance Orbiter (LRO) spacecraft collected between 2014 and 2017. We analyzed these data to characterize link performance over a wide range of weather conditions, season, and as a function of elevation angle. Based on this analysis, we have confirmed the safety of using a 3-dB margin for preflight planning purposes. These results suggest that a 3-dB margin with respect to adverse conditions will ensure a 98 to 99 percent data return under 95 percent weather conditions at 26 GHz (K-band), thus confirming expectations from link budget predictions. The results suggest that this margin should be applicable for all elevation angles above 10 deg. Thus, missions that have sufficient power for their desired data rates may opt to use 10 deg as their minimum elevation angle. Limitations of this study include climate variability and the fact that the observations require removal of hotbody noise in order to perform an adequate cumulative distribution function (CDF) analysis, which is planned for a future comprehensive study. Flight projects may use other link margins

Multi-MW K-Band Harmonic Multiplier: RF Source For High-Gradient Accelerator R & D

NASA Astrophysics Data System (ADS)

Solyak, N. A.; Yakovlev, V. P.; Kazakov, S. Yu.; Hirshfield, J. L.

2009-01-01

A preliminary design is presented for a two-cavity harmonic multiplier, intended as a high-power RF source for use in experiments aimed at developing high-gradient structures for a future collider. The harmonic multiplier is to produce power at selected frequencies in K-band (18-26.5 GHz) using as an RF driver an XK-5 S-band klystron (2.856 GHz). The device is to be built with a TE111 rotating mode input cavity and interchangeable output cavities running in the TEn11 rotating mode, with n = 7,8,9 at 19.992, 22.848, and 25.704 GHz. An example for a 7th harmonic multiplier is described, using a 250 kV, 20 A injected laminar electron beam; with 10 MW of S-band drive power, 4.7 MW of 20-GHz output power is predicted. Details are described of the magnetic circuit, cavities, and output coupler.

GPI Spectra of HR8799 C, D, and E in H-K Bands with KLIP Forward Modeling

NASA Technical Reports Server (NTRS)

Greenbaum, Alexandra Z.; Pueyo, Laurent; Ruffio, Jean-Baptiste; Wang, Jason J.; De Rosa, Robert J.; Aguilar, Jonathan; Rameau, Julien; Barman, Travis; Marois, Christian; Marley, Mark S.;

Sakurai's Object Continues to Brighten and Expand

NASA Astrophysics Data System (ADS)

Hinkle, Kenneth H.; Joyce, Richard R.; Matheson, Thomas

2017-01-01

Sakurai's Object (V4334 Sgr), the prototype final flash object discovered in the mid-1990s, was observed to undergo rapid cooling becoming as faint as 25th magnitude at K during the first decade of the 21st century. A review of imaging data suggests the minimum K magnitude occurred about 2006. Sakuarai's Object was re-acquired at K in 2010. Between 2010 Sep and 2013 Apr Sakurai's object brightened more than 2 magnitudes to K=14.2. Here we report on a Gemini-NIRI K band AO image obtained in 2016 July. The Ks magnitude was 13.35. The AO image also records the continuing expansion of the debris cloud. The central star remains obscured. Spectro-spatial NIFS images of the spectral region around He I 1.0830 micron and a GMOS optical spectrum, both observed in 2015, will also be displayed.

S-band low noise amplifier and 40 kW high power amplifier subsystems of Japanese Deep Space Earth Station

NASA Astrophysics Data System (ADS)

Honma, K.; Handa, K.; Akinaga, W.; Doi, M.; Matsuzaki, O.

This paper describes the design and the performance of the S-band low noise amplifier and the S-band high power amplifier that have been developed for the Usuda Deep Space Station of the Institute of Space and Astronautical Science (ISAS), Japan. The S-band low noise amplifier consists of a helium gas-cooled parametric amplifier followed by three-stage FET amplifiers and has a noise temperature of 8 K. The high power amplifier is composed of two 28 kW klystrons, capable of transmitting 40 kW continuously when two klystrons are combined. Both subsystems are operating quite satisfactorily in the tracking of Sakigake and Suisei, the Japanese interplanetary probes for Halley's comet exploration, launched by ISAS in 1985.

V and K-band Mass-Luminosity Relations for M Dwarf Stars

NASA Astrophysics Data System (ADS)

Benedict, George Frederick; Henry, Todd J.; McArthur, Barbara E.; Franz, Otto; Wasserman, Larry H.; Dieterich, Sergio

2015-08-01

Applying Hubble Space Telescope Fine Guidance Sensor astrometric techniques developed to establish relative orbits for binary stars (Franz et al. 1998, AJ, 116, 1432), determine masses of binary components (Benedict et al. 2001, AJ, 121, 1607), and measure companion masses of exoplanet host stars (McArthur et al. 2010, ApJ, 715, 1203), we derive masses with an average 2% error for 28 components of 14 M dwarf binary star systems. With these and other published masses we update the lower Main Sequence V-band Mass-Luminosity Relation first shown in Henry et al. 1999, ApJ, 512, 864. We demonstrate that a Mass-Luminosity Relation in the K-band has far less scatter. These relations can be used to estimate the masses of the ubiquitous red dwarfs (75% of all stars) to an accuracy of better than 5%.

"Off-the-Shelf" K2-EDTA for Calcific Band Keratopathy.

PubMed

Lee, Marco E; Ouano, Dean P; Shapiro, Brett; Fong, Andrew; Coroneo, Minas T

2018-07-01

To explore the effectiveness of "off-the-shelf" dipotassium-ethylenediaminetetraacetic acid (K2-EDTA) as an alternative to sodium EDTA as chelation therapy in removal of calcific band keratopathy (CBK). This study was a retrospective case series involving 4 patients with CBK who underwent superficial keratectomy and subsequent chelation therapy with K2-EDTA in a single center (Coastal Eye Clinic) by the same surgeon. Visual acuity and symptomatic relief were the main outcomes measured in our study. All 4 participants in this study were female with an average age of 80.3 years. Three of the patients with reasonable baseline visual acuity experienced improved visual acuity at 1 month. The other patient with multiple ocular comorbidities and severely reduced visual potential reported symptomatic pain relief at 1-month follow-up after the intervention. K2-EDTA seems to be an effective alternative to disodium EDTA in its ability to clear calcific plaques and restore visual function. Because of the logistical difficulties associated with acquiring disodium EDTA, and the relative abundance of K2-EDTA in health-care facilities, we believe that our findings warrant further investigation into its use as a more accessible and cost-effective chelating agent in CBK.

Korean VLBI Network Calibrator Survey (KVNCS). 1. Source Catalog of KVN Single-dish Flux Density Measurement in the K and Q Bands

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

Lee, Jeong Ae; Sohn, Bong Won; Jung, Taehyun

We present the catalog of the KVN Calibrator Survey (KVNCS). This first part of the KVNCS is a single-dish radio survey simultaneously conducted at 22 ( K band) and 43 GHz ( Q band) using the Korean VLBI Network (KVN) from 2009 to 2011. A total of 2045 sources are selected from the VLBA Calibrator Survey with an extrapolated flux density limit of 100 mJy at the K  band. The KVNCS contains 1533 sources in the K band with a flux density limit of 70 mJy and 553 sources in the Q band with a flux density limit of 120more » mJy; it covers the whole sky down to −32.°5 in decl. We detected 513 sources simultaneously in the K and Q bands; ∼76% of them are flat-spectrum sources (−0.5 ≤ α ≤ 0.5). From the flux–flux relationship, we anticipated that most of the radiation of many of the sources comes from the compact components. The sources listed in the KVNCS therefore are strong candidates for high-frequency VLBI calibrators.« less

The Hazard of Exposure to 2.075 kHz Center Frequency Narrow Band Impulses

DTIC Science & Technology

1991-09-01

i By r James H. Patterson, Jr. Kevin Bordwell Sensory Research Division and Roger P. Hamernik William A. Ahroon George Turrentine C. E. Hargett, Jr...The hazard of exposure to 2.075 kHz center frequency narrow band impulses 12. PERSONAL AUTHOR(S) James H. Patterson, Jr., Kevin Bordwell , Roger P...Patterson, J. H., Jr., Carrier, M., Jr., Bordwell , K., Lomba Gautier, I. M., Hamernik, R. P., Ahroon, W. A., Turrentine, G. A., and Hargett, C. E., Jr

Comparison of wavefront sensor models for simulation of adaptive optics.

PubMed

Wu, Zhiwen; Enmark, Anita; Owner-Petersen, Mette; Andersen, Torben

2009-10-26

The new generation of extremely large telescopes will have adaptive optics. Due to the complexity and cost of such systems, it is important to simulate their performance before construction. Most systems planned will have Shack-Hartmann wavefront sensors. Different mathematical models are available for simulation of such wavefront sensors. The choice of wavefront sensor model strongly influences computation time and simulation accuracy. We have studied the influence of three wavefront sensor models on performance calculations for a generic, adaptive optics (AO) system designed for K-band operation of a 42 m telescope. The performance of this AO system has been investigated both for reduced wavelengths and for reduced r(0) in the K band. The telescope AO system was designed for K-band operation, that is both the subaperture size and the actuator pitch were matched to a fixed value of r(0) in the K-band. We find that under certain conditions, such as investigating limiting guide star magnitude for large Strehl-ratios, a full model based on Fraunhofer propagation to the subimages is significantly more accurate. It does however require long computation times. The shortcomings of simpler models based on either direct use of average wavefront tilt over the subapertures for actuator control, or use of the average tilt to move a precalculated point spread function in the subimages are most pronounced for studies of system limitations to operating parameter variations. In the long run, efficient parallelization techniques may be developed to overcome the problem.

Retrospective cost adaptive Reynolds-averaged Navier-Stokes k-ω model for data-driven unsteady turbulent simulations

NASA Astrophysics Data System (ADS)

Li, Zhiyong; Hoagg, Jesse B.; Martin, Alexandre; Bailey, Sean C. C.

2018-03-01

This paper presents a data-driven computational model for simulating unsteady turbulent flows, where sparse measurement data is available. The model uses the retrospective cost adaptation (RCA) algorithm to automatically adjust the closure coefficients of the Reynolds-averaged Navier-Stokes (RANS) k- ω turbulence equations to improve agreement between the simulated flow and the measurements. The RCA-RANS k- ω model is verified for steady flow using a pipe-flow test case and for unsteady flow using a surface-mounted-cube test case. Measurements used for adaptation of the verification cases are obtained from baseline simulations with known closure coefficients. These verification test cases demonstrate that the RCA-RANS k- ω model can successfully adapt the closure coefficients to improve agreement between the simulated flow field and a set of sparse flow-field measurements. Furthermore, the RCA-RANS k- ω model improves agreement between the simulated flow and the baseline flow at locations at which measurements do not exist. The RCA-RANS k- ω model is also validated with experimental data from 2 test cases: steady pipe flow, and unsteady flow past a square cylinder. In both test cases, the adaptation improves agreement with experimental data in comparison to the results from a non-adaptive RANS k- ω model that uses the standard values of the k- ω closure coefficients. For the steady pipe flow, adaptation is driven by mean stream-wise velocity measurements at 24 locations along the pipe radius. The RCA-RANS k- ω model reduces the average velocity error at these locations by over 35%. For the unsteady flow over a square cylinder, adaptation is driven by time-varying surface pressure measurements at 2 locations on the square cylinder. The RCA-RANS k- ω model reduces the average surface-pressure error at these locations by 88.8%.

OER Quality and Adaptation in K-12: Comparing Teacher Evaluations of Copyright-Restricted, Open, and Open/Adapted Textbooks

ERIC Educational Resources Information Center

Kimmons, Royce

2015-01-01

Conducted in conjunction with an institute on open textbook adaptation, this study compares textbook evaluations from practicing K-12 classroom teachers (n = 30) on three different types of textbooks utilized in their contexts: copyright-restricted, open, and open/adapted. Copyright-restricted textbooks consisted of those textbooks already in use…

An antenna-pointing mechanism for the ETS-6 K-band Single Access (KSA) antenna

NASA Technical Reports Server (NTRS)

Takada, Noboru; Amano, Takahiro; Ohhashi, Toshiro; Wachi, Shigeo

1991-01-01

Both the design philosophy for the Antenna Pointing Mechanism (APM) to be used for the K-band Single Access (KSA) antenna system and experimental results of the APM Engineering Model (EM) tests are described. The KSA antenna system will be flown on the Engineering Test Satellite 6 (ETS-6).

Verification of band offsets and electron effective masses in GaAsN/GaAs quantum wells: Spectroscopic experiment versus 10-band k·p modeling

NASA Astrophysics Data System (ADS)

Ryczko, K.; Sek, G.; Sitarek, P.; Mika, A.; Misiewicz, J.; Langer, F.; Höfling, S.; Forchel, A.; Kamp, M.

2013-06-01

Optical transitions in GaAs1-xNx/GaAs quantum wells (QWs) have been probed by two complementary techniques, modulation spectroscopy in a form of photoreflectance and surface photovoltage spectroscopy. Transition energies in QWs of various widths and N contents have been compared with the results of band structure calculations based on the 10-band k.p Hamiltonian. Due to the observation of higher order transitions in the measured spectra, the band gap discontinuities at the GaAsN/GaAs interface and the electron effective masses could be determined, both treated as semi-free parameters to get the best matching between the theoretical and experimental energies. We have obtained the chemical conduction band offset values of 86% for x = 1.2% and 83% for x = 2.2%, respectively. For these determined band offsets, the electron effective masses equal to about 0.09 mo in QWs with 1.2% N and 0.15 mo for the case of larger N content of 2.2%.

GUIELOA: Adaptive Optics System for the 2.1-m SPM UNAM Telescope

NASA Astrophysics Data System (ADS)

Cuevas, S.; Iriarte, A.; Martínez, L. A.; Garfias, F.; Sánchez, L.; Chapa, O.; Ruelas, R. A.

2004-08-01

GUIELOA is the adaptive optics system project for the 2.1-m SPM telescope. This is a 19 sub-apertures curvature-type system. It corrects 8 Zernike terms. GUIELOA is very similar to PUEO, the CFHT adaptive optics system and compensates the atmospheric turbulence from the R band to the K band. Among the planned applications of GUIELOA are the study of OB binary systems, the detection of close binary stars, and the study of disks, jets and other phenomena associated with young stars.

Absolute band intensities in the nu19/nu23 (530 cm(-1)) and nu7 (777 cm(-1)) bands of acetone ((CH3)2CO) from 232 to 295 K

NASA Technical Reports Server (NTRS)

Wang, W. F.; Stevenson, A.; Reuter, D. C.; Sirota, J. M.

2000-01-01

Absolute band intensities of acetone ((CH3)2CO) in the nu19/nu23 and nu7 band systems near 530 and 777 cm(-1), respectively, were measured at temperatures of 232, 262 and 295 K, using a Fourier transform infrared (FTIR) spectrometer. No evident temperature dependence for the band intensities was observed. The dipole moments and the fundamental band intensities were derived in the harmonic oscillator approximation. The results are useful for the spectroscopic retrieval of acetone concentrations in the upper atmosphere.

Delayed-rectifier K channels contribute to contrast adaptation in mammalian retinal ganglion cells.

PubMed

Weick, Michael; Demb, Jonathan B

2011-07-14

Retinal ganglion cells adapt by reducing their sensitivity during periods of high contrast. Contrast adaptation in the firing response depends on both presynaptic and intrinsic mechanisms. Here, we investigated intrinsic mechanisms for contrast adaptation in OFF Alpha ganglion cells in the in vitro guinea pig retina. Using either visual stimulation or current injection, we show that brief depolarization evoked spiking and suppressed firing during subsequent depolarization. The suppression could be explained by Na channel inactivation, as shown in salamander cells. However, brief hyperpolarization in the physiological range (5-10 mV) also suppressed firing during subsequent depolarization. This suppression was selectively sensitive to blockers of delayed-rectifier K channels (K(DR)). In somatic membrane patches, we observed tetraethylammonium-sensitive K(DR) currents that activated near -25 mV. Recovery from inactivation occurred at potentials hyperpolarized to V(rest). Brief periods of hyperpolarization apparently remove K(DR) inactivation and thereby increase the channel pool available to suppress excitability during subsequent depolarization. Copyright © 2011 Elsevier Inc. All rights reserved.

76 FR 6493 - Notice of Intent to Prepare an Environmental Impact Statement for the Proposed K Road/Moapa Band...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-04

... Impact Statement for the Proposed K Road/Moapa Band of Paiute Indians Photovoltaic Solar Facility, Clark... and operate an up-to 350 MW solar photovoltaic electricity generating facility on approximately 2,000... preparing an environmental impact statement (EIS) for the proposed Moapa Band of Paiute Indians Solar...

Microwave absorption properties of flake-shaped Co particles composites at elevated temperature (293-673 K) in X band

NASA Astrophysics Data System (ADS)

Wang, Guowu; Li, Xiling; Wang, Peng; Zhang, Junming; Wang, Dian; Qiao, Liang; Wang, Tao; Li, Fashen

2018-06-01

The complex permeability and permittivity of the easy-plane anisotropic Co/polyimide composite at high temperature (293-673 K) in X band were measured. The results show that both the complex permeability and permittivity increase with the increase of temperature in the measured temperature range. The calculated absorption properties display that the intensity of the reflection loss (RL) peak first increases and then decreases with the increase of temperature, and reaches the maximum (-52 dB) at 523 K. At each temperature, the composite can achieve the RL exceeding -10 dB in the whole X band. The composite can even work stably for more than 20 min with the excellent absorption performance under 673 K. In addition, the RL performance of the composite at high temperature is better than that at room temperature.

SHARK-NIR: from K-band to a key instrument, a status update

NASA Astrophysics Data System (ADS)

Farinato, Jacopo; Bacciotti, Francesca; Baffa, Carlo; Baruffolo, Andrea; Bergomi, Maria; Bongiorno, Angela; Carbonaro, Luca; Carolo, Elena; Carlotti, Alexis; Centrone, Mauro; Close, Laird; De Pascale, Marco; Dima, Marco; D'Orazi, Valentina; Esposito, Simone; Fantinel, Daniela; Farisato, Giancarlo; Gaessler, Wolfgang; Giallongo, Emanuele; Greggio, Davide; Guyon, Olivier; Hinz, Philip; Lisi, Franco; Magrin, Demetrio; Marafatto, Luca; Mohr, Lars; Montoya, Manny; Pedichini, Fernando; Pinna, Enrico; Puglisi, Alfio; Ragazzoni, Roberto; Salasnich, Bernardo; Stangalini, Marco; Vassallo, Daniele; Verinaud, Christophe; Viotto, Valentina

2016-07-01

SHARK-NIR channel is one of the two coronagraphic instruments proposed for the Large Binocular Telescope, in the framework of the call for second generation instruments, issued in 2014. Together with the SHARK-VIS channel, it will offer a few observing modes (direct imaging, coronagraphic imaging and coronagraphic low resolution spectroscopy) covering a wide wavelength domain, going from 0.5μm to 1.7μm. Initially proposed as an instrument covering also the K-band, the current design foresees a camera working from Y to H bands, exploiting in this way the synergy with other LBT instruments such as LBTI, which is actually covering wavelengths greater than L' band, and it will be soon upgraded to work also in K band. SHARK-NIR has been undergoing the conceptual design review at the end of 2015 and it has been approved to proceed to the final design phase, receiving the green light for successive construction and installation at LBT. The current design is significantly more flexible than the previous one, having an additional intermediate pupil plane that will allow the usage of coronagraphic techniques very efficient in term of contrast and vicinity to the star, increasing the instrument coronagraphic performance. The latter is necessary to properly exploit the search of giant exo-planets, which is the main science case and the driver for the technical choices of SHARK-NIR. We also emphasize that the LBT AO SOUL upgrade will further improve the AO performance, making possible to extend the exo-planet search to target fainter than normally achieved by other 8-m class telescopes, and opening in this way to other very interesting scientific scenarios, such as the characterization of AGN and Quasars (normally too faint to be observed) and increasing considerably the sample of disks and jets to be studied. Finally, we emphasize that SHARK-NIR will offer XAO direct imaging capability on a FoV of about 15"x15", and a simple coronagraphic spectroscopic mode offering spectral

47 CFR 97.301 - Authorized frequency bands.

Code of Federal Regulations, 2013 CFR

2013-10-01

...: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements see § 97.303... Advanced Class: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements... General Class: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements...

47 CFR 97.301 - Authorized frequency bands.

Code of Federal Regulations, 2012 CFR

2012-10-01

...: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements see § 97.303... Advanced Class: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements... General Class: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements...

47 CFR 97.301 - Authorized frequency bands.

Code of Federal Regulations, 2011 CFR

2011-10-01

...: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements see § 97.303... Advanced Class: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements... General Class: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements...

47 CFR 97.301 - Authorized frequency bands.

Code of Federal Regulations, 2014 CFR

2014-10-01

...: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements see § 97.303... Advanced Class: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements... General Class: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements...

Band-pass filtering algorithms for adaptive control of compressor pre-stall modes in aircraft gas-turbine engine

NASA Astrophysics Data System (ADS)

Kuznetsova, T. A.

2018-05-01

The methods for increasing gas-turbine aircraft engines' (GTE) adaptive properties to interference based on empowerment of automatic control systems (ACS) are analyzed. The flow pulsation in suction and a discharge line of the compressor, which may cause the stall, are considered as the interference. The algorithmic solution to the problem of GTE pre-stall modes’ control adapted to stability boundary is proposed. The aim of the study is to develop the band-pass filtering algorithms to provide the detection functions of the compressor pre-stall modes for ACS GTE. The characteristic feature of pre-stall effect is the increase of pressure pulsation amplitude over the impeller at the multiples of the rotor’ frequencies. The used method is based on a band-pass filter combining low-pass and high-pass digital filters. The impulse response of the high-pass filter is determined through a known low-pass filter impulse response by spectral inversion. The resulting transfer function of the second order band-pass filter (BPF) corresponds to a stable system. The two circuit implementations of BPF are synthesized. Designed band-pass filtering algorithms were tested in MATLAB environment. Comparative analysis of amplitude-frequency response of proposed implementation allows choosing the BPF scheme providing the best quality of filtration. The BPF reaction to the periodic sinusoidal signal, simulating the experimentally obtained pressure pulsation function in the pre-stall mode, was considered. The results of model experiment demonstrated the effectiveness of applying band-pass filtering algorithms as part of ACS to identify the pre-stall mode of the compressor for detection of pressure fluctuations’ peaks, characterizing the compressor’s approach to the stability boundary.

A Novel Complex-Coefficient In-Band Interference Suppression Algorithm for Cognitive Ultra-Wide Band Wireless Sensors Networks.

PubMed

Xiong, Hailiang; Zhang, Wensheng; Xu, Hongji; Du, Zhengfeng; Tang, Huaibin; Li, Jing

2017-05-25

With the rapid development of wireless communication systems and electronic techniques, the limited frequency spectrum resources are shared with various wireless devices, leading to a crowded and challenging coexistence circumstance. Cognitive radio (CR) and ultra-wide band (UWB), as sophisticated wireless techniques, have been considered as significant solutions to solve the harmonious coexistence issues. UWB wireless sensors can share the spectrum with primary user (PU) systems without harmful interference. The in-band interference of UWB systems should be considered because such interference can severely affect the transmissions of UWB wireless systems. In order to solve the in-band interference issues for UWB wireless sensor networks (WSN), a novel in-band narrow band interferences (NBIs) elimination scheme is proposed in this paper. The proposed narrow band interferences suppression scheme is based on a novel complex-coefficient adaptive notch filter unit with a single constrained zero-pole pair. Moreover, in order to reduce the computation complexity of the proposed scheme, an adaptive complex-coefficient iterative method based on two-order Taylor series is designed. To cope with multiple narrow band interferences, a linear cascaded high order adaptive filter and a cyclic cascaded high order matrix adaptive filter (CCHOMAF) interference suppression algorithm based on the basic adaptive notch filter unit are also presented. The theoretical analysis and numerical simulation results indicate that the proposed CCHOMAF algorithm can achieve better performance in terms of average bit error rate for UWB WSNs. The proposed in-band NBIs elimination scheme can significantly improve the reception performance of low-cost and low-power UWB wireless systems.

A Novel Complex-Coefficient In-Band Interference Suppression Algorithm for Cognitive Ultra-Wide Band Wireless Sensors Networks

PubMed Central

Xiong, Hailiang; Zhang, Wensheng; Xu, Hongji; Du, Zhengfeng; Tang, Huaibin; Li, Jing

2017-01-01

With the rapid development of wireless communication systems and electronic techniques, the limited frequency spectrum resources are shared with various wireless devices, leading to a crowded and challenging coexistence circumstance. Cognitive radio (CR) and ultra-wide band (UWB), as sophisticated wireless techniques, have been considered as significant solutions to solve the harmonious coexistence issues. UWB wireless sensors can share the spectrum with primary user (PU) systems without harmful interference. The in-band interference of UWB systems should be considered because such interference can severely affect the transmissions of UWB wireless systems. In order to solve the in-band interference issues for UWB wireless sensor networks (WSN), a novel in-band narrow band interferences (NBIs) elimination scheme is proposed in this paper. The proposed narrow band interferences suppression scheme is based on a novel complex-coefficient adaptive notch filter unit with a single constrained zero-pole pair. Moreover, in order to reduce the computation complexity of the proposed scheme, an adaptive complex-coefficient iterative method based on two-order Taylor series is designed. To cope with multiple narrow band interferences, a linear cascaded high order adaptive filter and a cyclic cascaded high order matrix adaptive filter (CCHOMAF) interference suppression algorithm based on the basic adaptive notch filter unit are also presented. The theoretical analysis and numerical simulation results indicate that the proposed CCHOMAF algorithm can achieve better performance in terms of average bit error rate for UWB WSNs. The proposed in-band NBIs elimination scheme can significantly improve the reception performance of low-cost and low-power UWB wireless systems. PMID:28587085

Adaptive Enhancement of X-Band Marine Radar Imagery to Detect Oil Spill Segments

PubMed Central

Liu, Peng; Li, Ying; Xu, Jin; Zhu, Xueyuan

2017-01-01

Oil spills generate a large cost in environmental and economic terms. Their identification plays an important role in oil-spill response. We propose an oil spill detection method with improved adaptive enhancement on X-band marine radar systems. The radar images used in this paper were acquired on 21 July 2010, from the teaching-training ship “YUKUN” of the Dalian Maritime University. According to the shape characteristic of co-channel interference, two convolutional filters are used to detect the location of the interference, followed by a mean filter to erase the interference. Small objects, such as bright speckles, are taken as a mask in the radar image and improved by the Fields-of-Experts model. The region marked by strong reflected signals from the sea’s surface is selected to identify oil spills. The selected region is subject to improved adaptive enhancement designed based on features of radar images. With the proposed adaptive enhancement technique, calculated oil spill detection is comparable to visual interpretation in accuracy. PMID:29036892

Ultrabroadband Design for Linear Polarization Conversion and Asymmetric Transmission Crossing X- and K- Band

PubMed Central

Zhang, Linbo; Zhou, Peiheng; Chen, Haiyan; Lu, Haipeng; Xie, Haiyan; Zhang, Li; Li, En; Xie, Jianliang; Deng, Longjiang

2016-01-01

In this work, a high-efficiency and broadband reflective converter using ultrathin planar metamaterial (MM) composed of single-layered SRR is firstly realized. Numerical and experimental results demonstrate that the cross-polarization conversion reflectance above 0.84 is achieved from 8.6 to 18.6 GHz for linearly polarized (LP) incident waves under normal incidence. Subsequently, a multi-layered MM based on SRR enables a dramatic improvement of the recently demonstrated asymmetric transmission (AT) effect. Theoretical and measured results present that strong one-way transmission of two orthogonally polarized waves crossing C- and K- band has been observed. These two separated AT pass-bands have a function of selective polarization filter, which can be switched on/off by changing the polarization state of incident waves. The physical mechanisms are elucidated by taking advantage of electric fields and current distributions. Considering the broad bandwidth and the dual band, we believe that these two structures will be beneficial for designing polarization-controlled and selective transmission converter. PMID:27658929

Ultrabroadband Design for Linear Polarization Conversion and Asymmetric Transmission Crossing X- and K- Band.

PubMed

Zhang, Linbo; Zhou, Peiheng; Chen, Haiyan; Lu, Haipeng; Xie, Haiyan; Zhang, Li; Li, En; Xie, Jianliang; Deng, Longjiang

2016-09-23

In this work, a high-efficiency and broadband reflective converter using ultrathin planar metamaterial (MM) composed of single-layered SRR is firstly realized. Numerical and experimental results demonstrate that the cross-polarization conversion reflectance above 0.84 is achieved from 8.6 to 18.6 GHz for linearly polarized (LP) incident waves under normal incidence. Subsequently, a multi-layered MM based on SRR enables a dramatic improvement of the recently demonstrated asymmetric transmission (AT) effect. Theoretical and measured results present that strong one-way transmission of two orthogonally polarized waves crossing C- and K- band has been observed. These two separated AT pass-bands have a function of selective polarization filter, which can be switched on/off by changing the polarization state of incident waves. The physical mechanisms are elucidated by taking advantage of electric fields and current distributions. Considering the broad bandwidth and the dual band, we believe that these two structures will be beneficial for designing polarization-controlled and selective transmission converter.

High Power K Sub a -band Transmitter for Planetary Radar and Spacecraft Uplink

NASA Technical Reports Server (NTRS)

Bhanji, A. M.; Hoppe, D. J.; Hartop, R. W.; Stone, E. W.; Imbriale, W. A.; Stone, D.; Caplan, M.

1984-01-01

A proposed conceptual design of a 400 kW continuous wave (CW)K sub a band transmitter and associated microwave components to be used for planetary radar and serve as a prototype for future spacecraft uplinks is discussed. System requirements for such a transmitter are presented. Performance of the proposed high-power millimeter wave tube, the gyroklystron is discussed. Parameters of the proposed power amplifier, beam supply, and monitor and control devices are also presented. Microwave transmission line components consisting of signal monitoring devices, signal filtering devices, and an overmoded corrugated feed are discussed. Finally, an assessment of the state of the art technology to meet the system requirements is given and possible areas of difficulty are summarized.

Band gap tuning and optical absorption in type-II InAs/GaSb mid infrared short period superlattices: 14 bands K Dot-Operator p study

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

AbuEl-Rub, Khaled M.

2012-09-06

The MBE growth of short-period InAs/GaSb type-II superlattice structures, varied around 20.5 A InAs/24 A GaSb were [J. Applied physics, 96, 2580 (2004)] carried out by Haugan et al. These SLs were designed to produce devices with an optimum mid-infrared photoresponse and a sharpest photoresponse cutoff. We have used a realistic and reliable 14-band k.p formalism description of the superlattice electronic band structure to calculate the absorption coefficient in such short-period InAs/GaSb type-II superlattices. The parameters for this formalism are known from fitting to independent experiments for the bulk materials. The band-gap energies are obtained without any fitting parameters, andmore » are in good agreement with experimental data.« less

Improving GPU-accelerated adaptive IDW interpolation algorithm using fast kNN search.

PubMed

Mei, Gang; Xu, Nengxiong; Xu, Liangliang

2016-01-01

This paper presents an efficient parallel Adaptive Inverse Distance Weighting (AIDW) interpolation algorithm on modern Graphics Processing Unit (GPU). The presented algorithm is an improvement of our previous GPU-accelerated AIDW algorithm by adopting fast k-nearest neighbors (kNN) search. In AIDW, it needs to find several nearest neighboring data points for each interpolated point to adaptively determine the power parameter; and then the desired prediction value of the interpolated point is obtained by weighted interpolating using the power parameter. In this work, we develop a fast kNN search approach based on the space-partitioning data structure, even grid, to improve the previous GPU-accelerated AIDW algorithm. The improved algorithm is composed of the stages of kNN search and weighted interpolating. To evaluate the performance of the improved algorithm, we perform five groups of experimental tests. The experimental results indicate: (1) the improved algorithm can achieve a speedup of up to 1017 over the corresponding serial algorithm; (2) the improved algorithm is at least two times faster than our previous GPU-accelerated AIDW algorithm; and (3) the utilization of fast kNN search can significantly improve the computational efficiency of the entire GPU-accelerated AIDW algorithm.

Adaptive mitochondrial reprogramming and resistance to PI3K therapy.

PubMed

Ghosh, Jagadish C; Siegelin, Markus D; Vaira, Valentina; Faversani, Alice; Tavecchio, Michele; Chae, Young Chan; Lisanti, Sofia; Rampini, Paolo; Giroda, Massimo; Caino, M Cecilia; Seo, Jae Ho; Kossenkov, Andrew V; Michalek, Ryan D; Schultz, David C; Bosari, Silvano; Languino, Lucia R; Altieri, Dario C

2015-03-01

Small molecule inhibitors of phosphatidylinositol-3 kinase (PI3K) have been developed as molecular therapy for cancer, but their efficacy in the clinic is modest, hampered by resistance mechanisms. We studied the effect of PI3K therapy in patient-derived tumor organotypic cultures (from five patient samples), three glioblastoma (GBM) tumor cell lines, and an intracranial model of glioblastoma in immunocompromised mice (n = 4-5 mice per group). Mechanisms of therapy-induced tumor reprogramming were investigated in a global metabolomics screening, analysis of mitochondrial bioenergetics and cell death, and modulation of protein phosphorylation. A high-throughput drug screening was used to identify novel preclinical combination therapies with PI3K inhibitors, and combination synergy experiments were performed. All statistical methods were two-sided. PI3K therapy induces global metabolic reprogramming in tumors and promotes the recruitment of an active pool of the Ser/Thr kinase, Akt2 to mitochondria. In turn, mitochondrial Akt2 phosphorylates Ser31 in cyclophilin D (CypD), a regulator of organelle functions. Akt2-phosphorylated CypD supports mitochondrial bioenergetics and opposes tumor cell death, conferring resistance to PI3K therapy. The combination of a small-molecule antagonist of CypD protein folding currently in preclinical development, Gamitrinib, plus PI3K inhibitors (PI3Ki) reverses this adaptive response, produces synergistic anticancer activity by inducing mitochondrial apoptosis, and extends animal survival in a GBM model (vehicle: median survival = 28.5 days; Gamitrinib+PI3Ki: median survival = 40 days, P = .003), compared with single-agent treatment (PI3Ki: median survival = 32 days, P = .02; Gamitrinib: median survival = 35 days, P = .008 by two-sided unpaired t test). Small-molecule PI3K antagonists promote drug resistance by repurposing mitochondrial functions in bioenergetics and cell survival. Novel combination therapies that target mitochondrial

K-Band Phased Array Developed for Low- Earth-Orbit Satellite Communications

NASA Technical Reports Server (NTRS)

Anzic, Godfrey

1999-01-01

Future rapid deployment of low- and medium-Earth-orbit satellite constellations that will offer various narrow- to wide-band wireless communications services will require phased-array antennas that feature wide-angle and superagile electronic steering of one or more antenna beams. Antennas, which employ monolithic microwave integrated circuits (MMIC), are perfectly suited for this application. Under a cooperative agreement, an MMIC-based, K-band phased-array antenna is being developed with 50/50 cost sharing by the NASA Lewis Research Center and Raytheon Systems Company. The transmitting array, which will operate at 19 gigahertz (GHz), is a state-of-the-art design that features dual, independent, electronically steerable beam operation ( 42 ), a stand-alone thermal management, and a high-density tile architecture. This array can transmit 622 megabits per second (Mbps) in each beam from Earth orbit to small Earth terminals. The weight of the total array package is expected to be less than 8 lb. The tile integration technology (flip chip MMIC tile) chosen for this project represents a major advancement in phased-array engineering and holds much promise for reducing manufacturing costs.

VizieR Online Data Catalog: Spectroscopy of candidate members in Taurus (Luhman+, 2017)

NASA Astrophysics Data System (ADS)

Luhman, K. L.; Mamajek, E. E.; Shukla, S. J.; Loutrel, N. P.

2017-06-01

We have obtained optical and near-infrared spectra of candidate members of Taurus. The spectra were collected with the Gemini Near-Infrared Imager (NIRI) using the K-band grism and 0.47'' slit (1.9-2.5μm, R=700), the Gemini Multi-Object Spectrograph (GMOS) using the 400line/mm grating and 0.75'' slit (0.56-1μm, R=1500), the Marcario Low-Resolution Spectrograph (LRS) on the Hobby-Eberly Telescope (HET) using the G3 grism and 2'' slit (0.63-0.91μm, R=1100), and SpeX at the NASA Infrared Telescope Facility (IRTF) using either the prism or SXD mode (R=150/750) and 0.8'' slit (0.8-2.5μm). (7 data files).

Convex Banding of the Covariance Matrix.

PubMed

Bien, Jacob; Bunea, Florentina; Xiao, Luo

2016-01-01

We introduce a new sparse estimator of the covariance matrix for high-dimensional models in which the variables have a known ordering. Our estimator, which is the solution to a convex optimization problem, is equivalently expressed as an estimator which tapers the sample covariance matrix by a Toeplitz, sparsely-banded, data-adaptive matrix. As a result of this adaptivity, the convex banding estimator enjoys theoretical optimality properties not attained by previous banding or tapered estimators. In particular, our convex banding estimator is minimax rate adaptive in Frobenius and operator norms, up to log factors, over commonly-studied classes of covariance matrices, and over more general classes. Furthermore, it correctly recovers the bandwidth when the true covariance is exactly banded. Our convex formulation admits a simple and efficient algorithm. Empirical studies demonstrate its practical effectiveness and illustrate that our exactly-banded estimator works well even when the true covariance matrix is only close to a banded matrix, confirming our theoretical results. Our method compares favorably with all existing methods, in terms of accuracy and speed. We illustrate the practical merits of the convex banding estimator by showing that it can be used to improve the performance of discriminant analysis for classifying sound recordings.

Convex Banding of the Covariance Matrix

PubMed Central

Bien, Jacob; Bunea, Florentina; Xiao, Luo

2016-01-01

We introduce a new sparse estimator of the covariance matrix for high-dimensional models in which the variables have a known ordering. Our estimator, which is the solution to a convex optimization problem, is equivalently expressed as an estimator which tapers the sample covariance matrix by a Toeplitz, sparsely-banded, data-adaptive matrix. As a result of this adaptivity, the convex banding estimator enjoys theoretical optimality properties not attained by previous banding or tapered estimators. In particular, our convex banding estimator is minimax rate adaptive in Frobenius and operator norms, up to log factors, over commonly-studied classes of covariance matrices, and over more general classes. Furthermore, it correctly recovers the bandwidth when the true covariance is exactly banded. Our convex formulation admits a simple and efficient algorithm. Empirical studies demonstrate its practical effectiveness and illustrate that our exactly-banded estimator works well even when the true covariance matrix is only close to a banded matrix, confirming our theoretical results. Our method compares favorably with all existing methods, in terms of accuracy and speed. We illustrate the practical merits of the convex banding estimator by showing that it can be used to improve the performance of discriminant analysis for classifying sound recordings. PMID:28042189

Underwater hearing sensitivity of harbor seals (Phoca vitulina) for narrow noise bands between 0.2 and 80 kHz.

PubMed

Kastelein, Ronald A; Wensveen, Paul; Hoek, Lean; Terhune, John M

2009-07-01

The underwater hearing sensitivities of two 1.5-year-old female harbor seals were quantified in a quiet pool built specifically for acoustic research, by using a behavioral psychoacoustic technique. The animals were trained to respond when they detected an acoustic signal and not to respond when they did not ("go/no-go" response). Fourteen narrowband noise signals (1/3-octave bands but with some energy in adjacent bands), at 1/3-octave center frequencies of 0.2-80 kHz, and of 900 ms duration, were tested. Thresholds at each frequency were measured using the up-down staircase method and defined as the stimulus level resulting in a 50% detection rate. Between 0.5 and 40 kHz, the thresholds corresponded to a 1/3-octave band noise level of approximately 60 dB re 1 microPa (SD+/-3.0 dB). At lower frequencies, the thresholds increased to 66 dB re 1 microPa and at 80 kHz the thresholds rose to 114 dB re 1 microPa. The 1/3-octave noise band thresholds of the two seals did not differ from each other, or from the narrowband frequency-modulated tone thresholds at the same frequencies obtained a few months before for the same animals. These hearing threshold values can be used to calculate detection ranges of underwater calls and anthropogenic noises by harbor seals.

Adaptive sparsest narrow-band decomposition method and its applications to rolling element bearing fault diagnosis

NASA Astrophysics Data System (ADS)

Cheng, Junsheng; Peng, Yanfeng; Yang, Yu; Wu, Zhantao

2017-02-01

Enlightened by ASTFA method, adaptive sparsest narrow-band decomposition (ASNBD) method is proposed in this paper. In ASNBD method, an optimized filter must be established at first. The parameters of the filter are determined by solving a nonlinear optimization problem. A regulated differential operator is used as the objective function so that each component is constrained to be a local narrow-band signal. Afterwards, the signal is filtered by the optimized filter to generate an intrinsic narrow-band component (INBC). ASNBD is proposed aiming at solving the problems existed in ASTFA. Gauss-Newton type method, which is applied to solve the optimization problem in ASTFA, is irreplaceable and very sensitive to initial values. However, more appropriate optimization method such as genetic algorithm (GA) can be utilized to solve the optimization problem in ASNBD. Meanwhile, compared with ASTFA, the decomposition results generated by ASNBD have better physical meaning by constraining the components to be local narrow-band signals. Comparisons are made between ASNBD, ASTFA and EMD by analyzing simulation and experimental signals. The results indicate that ASNBD method is superior to the other two methods in generating more accurate components from noise signal, restraining the boundary effect, possessing better orthogonality and diagnosing rolling element bearing fault.

3D Target Localization of Modified 3D MUSIC for a Triple-Channel K-Band Radar.

PubMed

Li, Ying-Chun; Choi, Byunggil; Chong, Jong-Wha; Oh, Daegun

2018-05-20

In this paper, a modified 3D multiple signal classification (MUSIC) algorithm is proposed for joint estimation of range, azimuth, and elevation angles of K-band radar with a small 2 × 2 horn antenna array. Three channels of the 2 × 2 horn antenna array are utilized as receiving channels, and the other one is a transmitting antenna. The proposed modified 3D MUSIC is designed to make use of a stacked autocorrelation matrix, whose element matrices are related to each other in the spatial domain. An augmented 2D steering vector based on the stacked autocorrelation matrix is proposed for the modified 3D MUSIC, instead of the conventional 3D steering vector. The effectiveness of the proposed modified 3D MUSIC is verified through implementation with a K-band frequency-modulated continuous-wave (FMCW) radar with the 2 × 2 horn antenna array through a variety of experiments in a chamber.

A dual-band adaptor for infrared imaging.

PubMed

McLean, A G; Ahn, J-W; Maingi, R; Gray, T K; Roquemore, A L

2012-05-01

A novel imaging adaptor providing the capability to extend a standard single-band infrared (IR) camera into a two-color or dual-band device has been developed for application to high-speed IR thermography on the National Spherical Tokamak Experiment (NSTX). Temperature measurement with two-band infrared imaging has the advantage of being mostly independent of surface emissivity, which may vary significantly in the liquid lithium divertor installed on NSTX as compared to that of an all-carbon first wall. In order to take advantage of the high-speed capability of the existing IR camera at NSTX (1.6-6.2 kHz frame rate), a commercial visible-range optical splitter was extensively modified to operate in the medium wavelength and long wavelength IR. This two-band IR adapter utilizes a dichroic beamsplitter, which reflects 4-6 μm wavelengths and transmits 7-10 μm wavelength radiation, each with >95% efficiency and projects each IR channel image side-by-side on the camera's detector. Cutoff filters are used in each IR channel, and ZnSe imaging optics and mirrors optimized for broadband IR use are incorporated into the design. In-situ and ex-situ temperature calibration and preliminary data of the NSTX divertor during plasma discharges are presented, with contrasting results for dual-band vs. single-band IR operation.

An active K/Ka-band antenna array for the NASA ACTS mobile terminal

NASA Technical Reports Server (NTRS)

Tulintseff, A.; Crist, R.; Densmore, Art; Sukamto, L.

1993-01-01

An active K/Ka-band antenna array is currently under development for NASA's ACTS Mobile Terminal (AMT). The AMT task will demonstrate voice, data, and video communications to and from the AMT vehicle in Los Angeles, California, and a base station in Cleveland, Ohio, via the ACTS satellite at 30 and 20 GHz. Satellite tracking for the land-mobile vehicular antenna system involves 'mechanical dithering' of the antenna, where the antenna radiates a fixed beam 46 deg. above the horizon. The antenna is to transmit horizontal polarization and receive vertical polarization at 29.634 plus or minus 0.15 GHz and 19.914 plus or minus 0.15 GHz, respectively. The active array will provide a minimum of 22 dBW EIRP transmit power density and a -8 dB/K deg. receive sensitivity.

Design of a K/Q-band Beacon Receiver for the Alphasat TDP#5 Experiment

NASA Technical Reports Server (NTRS)

Nessel, James A.; Zemba, Michael J.; Morse, Jacquelynne R.

2014-01-01

This paper describes the design and performance of a coherent K/Q-band (20/40GHz) beacon receiver developed at NASA Glenn Research Center (GRC) that will be installed at the Politecnico di Milano (POLIMI) for use in the Alphasat Technology Demonstration Payload #5 (TDP#5) beacon experiment. The goal of this experiment is to characterize rain fade attenuation at 40GHz to improve the performance of existing statistical rain attenuation models in the Q-band. The ground terminal developed by NASA GRC utilizes an FFT-based frequency estimation receiver capable of characterizing total path attenuation effects due to gaseous absorption, clouds, rain, and scintillation. The receiver system has been characterized in the lab and demonstrates a system dynamic range performance of better than 58dB at 1Hz and better than 48dB at 10Hz rates.

Salinity fluctuation influencing biological adaptation: growth dynamics and Na+ /K+ -ATPase activity in a euryhaline bacterium.

PubMed

Yang, Hao; Meng, Yang; Song, Youxin; Tan, Yalin; Warren, Alan; Li, Jiqiu; Lin, Xiaofeng

2017-07-01

Although salinity fluctuation is a prominent characteristic of many coastal ecosystems, its effects on biological adaptation have not yet been fully recognized. To test the salinity fluctuations on biological adaptation, population growth dynamics and Na + /K + -ATPase activity were investigated in the euryhaline bacterium Idiomarina sp. DYB, which was acclimated at different salinity exposure levels, exposure times, and shifts in direction of salinity. Results showed: (1) bacterial population growth dynamics and Na + /K + -ATPase activity changed significantly in response to salinity fluctuation; (2) patterns of variation in bacterial growth dynamics were related to exposure times, levels of salinity, and shifts in direction of salinity change; (3) significant tradeoffs were detected between growth rate (r) and carrying capacity (K) on the one hand, and Na + /K + -ATPase activity on the other; and (4) beneficial acclimation was confirmed in Idiomarina sp. DYB. In brief, this study demonstrated that salinity fluctuation can change the population growth dynamics, Na + /K + -ATPase activity, and tradeoffs between r, K, and Na + /K + -ATPase activity, thus facilitating bacterial adaption in a changing environment. These findings provide constructive information for determining biological response patterns to environmental change. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ground-based K-band detection of thermal emission from the exoplanet TrES-3b

NASA Astrophysics Data System (ADS)

de Mooij, E. J. W.; Snellen, I. A. G.

2009-01-01

Context: Secondary eclipse measurements of transiting extrasolar planets with the Spitzer Space Telescope have yielded several direct detections of thermal exoplanet light. Since Spitzer operates at wavelengths longward of 3.6 μm, arguably one of the most interesting parts of the planet spectrum (from 1 to 3 μm) is inaccessible with this satellite. This region is at the peak of the planet's spectral energy distribution and is also the regime where molecular absorption bands can significantly influence the measured emission. Aims: So far, 2.2 μm K-band secondary eclipse measurements, which are possible from the ground, have not yet lead to secure detections. The aim of this paper is to measure the secondary eclipse of the very hot Jupiter TrES-3b in K-band, and in addition to observe its transit, to obtain an accurate planet radius in the near infrared. Methods: We have used the william herschell telescope (WHT) to observe the secondary eclipse, and the united kingdom infrared telescope (UKIRT) to observe the transit of TrES-3b. Both observations involved significant defocusing of the telescope, aimed to produce high-cadence time series of several thousand frames at high efficiency, with the starlight spread out over many pixels. Results: We detect the secondary eclipse of TrES-3b with a depth of -0.241 ± 0.043% (~6σ). This corresponds to a day-side brightness temperature of TB(2.2 μm) = 2040 ± 185 K, which is consistent with current models of the physical properties of this planet's upper atmosphere. The centre of the eclipse seems slightly offset from phase φ=0.5 by Δφ = -0.0042 ± 0.0027, which could indicate that the orbit of TrES-3b is non-circular. Analysis of the transit data shows that TrES-3b has a near-infrared radius of 1.338 ± 0.016 R_Jup, showing no significant deviation from optical measurements.

Short-term differential adaptation to anaerobic stress via genomic mutations by Escherichia coli strains K-12 and B lacking alcohol dehydrogenase

PubMed Central

Kim, Hyun Ju; Jeong, Haeyoung; Hwang, Seungwoo; Lee, Moo-Seung; Lee, Yong-Jik; Lee, Dong-Woo; Lee, Sang Jun

2014-01-01

Microbial adaptations often occur via genomic mutations under adverse environmental conditions. This study used Escherichia coli ΔadhE cells as a model system to investigate adaptation to anaerobic conditions, which we then compared with the adaptive mechanisms of two closely related E. coli strains, K-12 and B. In contrast to K-12 ΔadhE cells, the E. coli B ΔadhE cells exhibited significantly delayed adaptive growth under anaerobic conditions. Adaptation by the K-12 and B strains mainly employed anaerobic lactate fermentation to restore cellular growth. Several mutations were identified in the pta or pflB genes of adapted K-12 cells, but mostly in the pta gene of the B strains. However, the types of mutation in the adapted K-12 and B strains were similar. Cellular viability was affected directly by severe redox imbalance in B ΔadhE cells, which also impaired their ability to adapt to anaerobic conditions. This study demonstrates that closely related microorganisms may undergo different adaptations under the same set of adverse conditions, which might be associated with the specific metabolic characteristics of each strain. This study provides new insights into short-term microbial adaptation to stressful conditions, which may reflect dynamic microbial population changes in nature. PMID:25250024

Short-term differential adaptation to anaerobic stress via genomic mutations by Escherichia coli strains K-12 and B lacking alcohol dehydrogenase.

PubMed

Kim, Hyun Ju; Jeong, Haeyoung; Hwang, Seungwoo; Lee, Moo-Seung; Lee, Yong-Jik; Lee, Dong-Woo; Lee, Sang Jun

2014-01-01

Microbial adaptations often occur via genomic mutations under adverse environmental conditions. This study used Escherichia coli ΔadhE cells as a model system to investigate adaptation to anaerobic conditions, which we then compared with the adaptive mechanisms of two closely related E. coli strains, K-12 and B. In contrast to K-12 ΔadhE cells, the E. coli B ΔadhE cells exhibited significantly delayed adaptive growth under anaerobic conditions. Adaptation by the K-12 and B strains mainly employed anaerobic lactate fermentation to restore cellular growth. Several mutations were identified in the pta or pflB genes of adapted K-12 cells, but mostly in the pta gene of the B strains. However, the types of mutation in the adapted K-12 and B strains were similar. Cellular viability was affected directly by severe redox imbalance in B ΔadhE cells, which also impaired their ability to adapt to anaerobic conditions. This study demonstrates that closely related microorganisms may undergo different adaptations under the same set of adverse conditions, which might be associated with the specific metabolic characteristics of each strain. This study provides new insights into short-term microbial adaptation to stressful conditions, which may reflect dynamic microbial population changes in nature.

Measurement of the nighttime infrared luminosity of Spacelab 1 in the H- and K-bands

NASA Technical Reports Server (NTRS)

Witteborn, F. C.; Obrien, K.; Caroff, L.

1985-01-01

Infrared measurements of the Spacelab 1, Space Transportation System 9, were made from the Maui Optical Station tracking facility using a sensitive photometer n two infrared bands, the H-band centered at a wavelength of 1.6 microns and the K-band centered at 2.3 micrometers. The objective was to measure radiation from the vicinity of the Shuttle arising from interaction of Shuttle surfaces with atmospheric particles. It was necessary to include the Shuttle itself in the field of view of the photometer. The integrated brightness of the entire Shuttle at a distance of 400 km was found to be equivalent to that of a star of magnitude +6.6 or 1.6 microns; it was much fainter in the visible. Most of the emission at 1.6 microns appears to be attributable to the Shuttle glow phenomenon. It is hundreds of times brighter than the zodiacal background. The radiation at 2.3 microns can be accounted for primarily by diffusely scattered thermal radiation from Earth's surface.

K-Band Si/SiGe HBT MMIC Amplifiers Using Lumped Passive Components with a Micromachined Structure

NASA Technical Reports Server (NTRS)

Lu, Liang-Hung; Rieh, Jae-Sung; Bhattacharya, Pallab; Katechi, Linda P. B.; Croke, E. T.; Ponchak, George E.; Alterovitz, Samuel A.

2000-01-01

Using Si/SiGe heterojunction bipolar transistors with a maximum oscillation frequency of 52 GHz and a novel structure for passive components, a two-stage K-band lumped-element amplifier has been designed and fabricated on high-resistivity Si substrates. The chip size including biasing and RF chokes is 0.92 x 0.67 sq mm.

Flexibility and Stability Trade-Off in Active Site of Cold-Adapted Pseudomonas mandelii Esterase EstK.

PubMed

Truongvan, Ngoc; Jang, Sei-Heon; Lee, ChangWoo

2016-06-28

Cold-adapted enzymes exhibit enhanced conformational flexibility, especially in their active sites, as compared with their warmer-temperature counterparts. However, the mechanism by which cold-adapted enzymes maintain their active site stability is largely unknown. In this study, we investigated the role of conserved D308-Y309 residues located in the same loop as the catalytic H307 residue in the cold-adapted esterase EstK from Pseudomonas mandelii. Mutation of D308 and/or Y309 to Ala or deletion resulted in increased conformational flexibility. Particularly, the D308A or Y309A mutant showed enhanced substrate affinity and catalytic rate, as compared with wild-type EstK, via enlargement of the active site. However, all mutant EstK enzymes exhibited reduced thermal stability. The effect of mutation was greater for D308 than Y309. These results indicate that D308 is not preferable for substrate selection and catalytic activity, whereas hydrogen bond formation involving D308 is critical for active site stabilization. Taken together, conformation of the EstK active site is constrained via flexibility-stability trade-off for enzyme catalysis and thermal stability. Our study provides further insights into active site stabilization of cold-adapted enzymes.

The Core of NGC 6240 from Keck Adaptive Optics and HST NICMOS Observations

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

Max, C E; Canalizo, G; Macintosh, B A

2004-06-28

We present results of near infrared imaging of the disk-galaxy-merger NGC 6240 using adaptive optics on the Keck II Telescope and reprocessed archival data from NICMOS on the Hubble Space Telescope. Both the North and South nuclei of NGC 6240 are clearly elongated, with considerable sub-structure within each nucleus. In K' band there are at least two point-sources within the North nucleus; we tentatively identify the south-western point-source within the North nucleus as the position of one of the two AGNs. Within the South nucleus, the northern subnucleus is more highly reddened. Based upon the nuclear separation measured at 5more » GHz, we suggest that the AGN in the South nucleus is still enshrouded in dust at K' band, and is located slightly to the north of the brightest point in K' band. Within the South nucleus there is strong H{sub 2} 1-0 S(1) line emission from the northern sub-nucleus, contrary to the conclusions of previous seeing-limited observations. Narrowband H{sub 2} emission-line images show that a streamer or ribbon of excited molecular hydrogen connects the North and South nuclei. We suggest that this linear feature corresponds to a bridge of gas connecting the two nuclei, as seen in computer simulations of mergers. Many point-like regions are seen around the two nuclei. These are most prominent at 1.1 microns with NICMOS, and in K'-band with Keck adaptive optics. We suggest that these point-sources represent star clusters formed in the course of the merger.« less

The Core of NGC 6240 from Keck Adaptive Optics and HST NICMOS Observations

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

Max, C E; Canalizo, G; Macintosh, B A

2004-11-19

We present results of near infrared imaging of the disk-galaxy-merger NGC 6240 using adaptive optics on the Keck II Telescope and reprocessed archival data from NICMOS on the Hubble Space Telescope. Both the North and South nuclei of NGC 6240 are clearly elongated, with considerable sub-structure within each nucleus. In K' band there are at least two point-sources within the North nucleus; we tentatively identify the south-western point-source within the North nucleus as the position of one of the two AGNs. Within the South nucleus, the northern subnucleus is more highly reddened. Based upon the nuclear separation measured at 5more » GHz, we suggest that the AGN in the South nucleus is still enshrouded in dust at K' band, and is located slightly to the north of the brightest point in K' band. Within the South nucleus there is strong H{sub 2} 1-0 S(1) line emission from the northern sub-nucleus, contrary to the conclusions of previous seeing-limited observations. Narrowband H{sub 2} emission-line images show that a streamer or ribbon of excited molecular hydrogen connects the North and South nuclei. We suggest that this linear feature corresponds to a bridge of gas connecting the two nuclei, as seen in computer simulations of mergers. Many any point-like regions are seen around the two nuclei. These are most prominent at 1.1 microns with NICMOS, and in K'-band with Keck adaptive optics. We suggest that these point-sources represent young star clusters formed in the course of the merger.« less

Early tumor detection afforded by in vivo imaging of near-infrared II fluorescence.

PubMed

Tao, Zhimin; Dang, Xiangnan; Huang, Xing; Muzumdar, Mandar D; Xu, Eric S; Bardhan, Neelkanth Manoj; Song, Haiqin; Qi, Ruogu; Yu, Yingjie; Li, Ting; Wei, Wei; Wyckoff, Jeffrey; Birrer, Michael J; Belcher, Angela M; Ghoroghchian, P Peter

2017-07-01

Cell-intrinsic reporters such as luciferase (LUC) and red fluorescent protein (RFP) have been commonly utilized in preclinical studies to image tumor growth and to monitor therapeutic responses. While extrinsic reporters that emit near infrared I (NIR-I: 650-950 nm) or near-infrared II (NIR-II: 1000-1700 nm) optical signals have enabled minimization of tissue autofluorescence and light scattering, it has remained unclear as to whether their use has afforded more accurate tumor imaging in small animals. Here, we developed a novel optical imaging construct comprised of rare earth lanthanide nanoparticles coated with biodegradable diblock copolymers and doped with organic fluorophores, generating NIR-I and NIR-II emissive bands upon optical excitation. Simultaneous injection of multiple spectrally-unique nanoparticles into mice bearing tumor implants established via intraperitoneal dissemination of LUC + /RFP + OVCAR-8 ovarian cancer cells enabled direct comparisons of imaging with extrinsic vs. intrinsic reporters, NIR-II vs. NIR-I signals, as well as targeted vs. untargeted exogenous contrast agents in the same animal and over time. We discovered that in vivo optical imaging at NIR-II wavelengths facilitates more accurate detection of smaller and earlier tumor deposits, offering enhanced sensitivity, improved spatial contrast, and increased depths of tissue penetration as compared to imaging with visible or NIR-I fluorescent agents. Our work further highlights the hitherto underappreciated enhancements in tumor accumulation that may be achieved with intraperitoneal as opposed to intravenous administration of nanoparticles. Lastly, we found discrepancies in the fidelity of tumor uptake that could be obtained by utilizing small molecules for in vivo as opposed to in vitro targeting of nanoparticles to disseminated tumors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simultaneous dual-band radar development

NASA Technical Reports Server (NTRS)

Liskow, C. L.

1974-01-01

Efforts to design and construct an airborne imaging radar operating simultaneously at L band and X band with an all-inertial navigation system in order to form a dual-band radar system are described. The areas of development include duplex transmitters, receivers, and recorders, a control module, motion compensation for both bands, and adaptation of a commercial inertial navigation system. Installation of the system in the aircraft and flight tests are described. Circuit diagrams, performance figures, and some radar images are presented.

47 CFR 18.303 - Prohibited frequency bands.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 1 2011-10-01 2011-10-01 false Prohibited frequency bands. 18.303 Section 18.303 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL... following safety, search and rescue frequency bands is prohibited: 490-510 kHz, 2170-2194 kHz, 8354-8374 kHz...

47 CFR 18.303 - Prohibited frequency bands.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 1 2013-10-01 2013-10-01 false Prohibited frequency bands. 18.303 Section 18.303 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL... following safety, search and rescue frequency bands is prohibited: 490-510 kHz, 2170-2194 kHz, 8354-8374 kHz...

47 CFR 18.303 - Prohibited frequency bands.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 1 2012-10-01 2012-10-01 false Prohibited frequency bands. 18.303 Section 18.303 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL... following safety, search and rescue frequency bands is prohibited: 490-510 kHz, 2170-2194 kHz, 8354-8374 kHz...

47 CFR 18.303 - Prohibited frequency bands.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 1 2014-10-01 2014-10-01 false Prohibited frequency bands. 18.303 Section 18.303 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL... following safety, search and rescue frequency bands is prohibited: 490-510 kHz, 2170-2194 kHz, 8354-8374 kHz...

47 CFR 97.301 - Authorized frequency bands.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., or who holds a Class 1 IARP license: Wavelength band MF ITU region 1 kHz ITU region 2 kHz ITU region 3 kHz Sharing requirements see § 97.303(paragraph) 160 m 1810-1850 1800-2000 1800-2000 (a), (c), (g... who has been granted an operator license of Advanced Class: Wavelength band MF ITU region 1 kHz ITU...

Estimation of Spatiotemporal Sensitivity Using Band-limited Signals with No Additional Acquisitions for k-t Parallel Imaging.

PubMed

Takeshima, Hidenori; Saitoh, Kanako; Nitta, Shuhei; Shiodera, Taichiro; Takeguchi, Tomoyuki; Bannae, Shuhei; Kuhara, Shigehide

2018-03-13

Dynamic MR techniques, such as cardiac cine imaging, benefit from shorter acquisition times. The goal of the present study was to develop a method that achieves short acquisition times, while maintaining a cost-effective reconstruction, for dynamic MRI. k - t sensitivity encoding (SENSE) was identified as the base method to be enhanced meeting these two requirements. The proposed method achieves a reduction in acquisition time by estimating the spatiotemporal (x - f) sensitivity without requiring the acquisition of the alias-free signals, typical of the k - t SENSE technique. The cost-effective reconstruction, in turn, is achieved by a computationally efficient estimation of the x - f sensitivity from the band-limited signals of the aliased inputs. Such band-limited signals are suitable for sensitivity estimation because the strongly aliased signals have been removed. For the same reduction factor 4, the net reduction factor 4 for the proposed method was significantly higher than the factor 2.29 achieved by k - t SENSE. The processing time is reduced from 4.1 s for k - t SENSE to 1.7 s for the proposed method. The image quality obtained using the proposed method proved to be superior (mean squared error [MSE] ± standard deviation [SD] = 6.85 ± 2.73) compared to the k - t SENSE case (MSE ± SD = 12.73 ± 3.60) for the vertical long-axis (VLA) view, as well as other views. In the present study, k - t SENSE was identified as a suitable base method to be improved achieving both short acquisition times and a cost-effective reconstruction. To enhance these characteristics of base method, a novel implementation is proposed, estimating the x - f sensitivity without the need for an explicit scan of the reference signals. Experimental results showed that the acquisition, computational times and image quality for the proposed method were improved compared to the standard k - t SENSE method.

Phase noise measurements of the 400-kW, 2.115-GHz (S-band) transmitter

NASA Technical Reports Server (NTRS)

Boss, P.; Hoppe, D.; Bhanji, A.

1987-01-01

The measurement theory is described and a test method to perform phase noise verification using off-the-shelf components and instruments is presented. The measurement technique described consists of a double-balanced mixer used as phase detector, followed by a low noise amplifier. An FFT spectrum analyzer is then used to view the modulation components. A simple calibration procedure is outlined that ensures accurate measurements. A block diagram of the configuration is presented as well as actual phase noise data from the 400 kW, 2.115 GHz (S-band) klystron transmitter.

Unsupervised Cryo-EM Data Clustering through Adaptively Constrained K-Means Algorithm.

PubMed

Xu, Yaofang; Wu, Jiayi; Yin, Chang-Cheng; Mao, Youdong

2016-01-01

In single-particle cryo-electron microscopy (cryo-EM), K-means clustering algorithm is widely used in unsupervised 2D classification of projection images of biological macromolecules. 3D ab initio reconstruction requires accurate unsupervised classification in order to separate molecular projections of distinct orientations. Due to background noise in single-particle images and uncertainty of molecular orientations, traditional K-means clustering algorithm may classify images into wrong classes and produce classes with a large variation in membership. Overcoming these limitations requires further development on clustering algorithms for cryo-EM data analysis. We propose a novel unsupervised data clustering method building upon the traditional K-means algorithm. By introducing an adaptive constraint term in the objective function, our algorithm not only avoids a large variation in class sizes but also produces more accurate data clustering. Applications of this approach to both simulated and experimental cryo-EM data demonstrate that our algorithm is a significantly improved alterative to the traditional K-means algorithm in single-particle cryo-EM analysis.

K-Band Power Enbedded Transmission Line (ETL) MMIC Amplifiers for Satellite Communication Applications

NASA Technical Reports Server (NTRS)

Tserng, Hua-Quen; Ketterson, Andrew; Saunier, Paul; McCarty, Larry; Davis, Steve

1998-01-01

The design, fabrication, and performance of K-band high-efficiency, linear power pHEMT amplifiers implemented in Embedded Transmission Line (ETL) MMIC configuration with unthinned GaAs substrate and topside grounding are reported. A three-stage amplifier achieved a power-added efficiency of 40.5% with 264 mW output at 20.2 GHz. The linear gain is 28.5 dB with 1-dB gain compression output power of 200 mW and 31% power-added efficiency. The carrier-to-third-order intermodulation ratio is approx. 20 dBc at the 1-dB compression point. A RF functional yield of more than 90% has been achieved.

Giant K-doubling and in-plane/out-of-plane mixing in the asymmetric methyl-bending bands of CH3SH

NASA Astrophysics Data System (ADS)

Guislain, B. G.; Reid, E. M.; Lees, R. M.; Xu, Li-Hong; Twagirayezu, S.; Perry, D. S.; Thapaliya, B. P.; Dawadi, M. B.; Billinghurst, B. E.

2017-05-01

In analyzing high-resolution spectra of the methyl-deformation bands of methyl mercaptan recorded at the Canadian Light Source synchrotron, we have encountered interesting interactions between certain levels of the ν4 in-plane asymmetric CH3-bending mode and its ν10 out-of-plane bending partner below. The origin of the K = 0A ν4 substate is just 0.2 cm-1 higher than that of the K = 2A ν10 substate, while the K = 0E ν4 origin is only 0.035 cm-1 below the K = 2E ν10 origin. These very close accidental near-degeneracies lead to substantial perturbations in the spectrum. For the former, the A+/A- asymmetry K-doublet coupling rules are such that the A- component of the 2A ν10 doublet interacts and mixes strongly with the 0A+ ν4 levels whereas the 2A+ component is unaffected. The 2A- levels are pushed rapidly downwards by the coupling creating an extremely large apparent K = 2A asymmetry splitting. We call this "giant K-doubling" by analogy with a comparable phenomenon seen for methanol. The 0A+ ν4 state, in turn, is perturbed upward and passes through the descending K = 1A+ ν4 state between J = 22 and 23, leading to distinct local perturbations near the level-crossing. The 0E ν4 and 2E ν10 coupling produces a correspondingly strong repulsion and mixing between those two substates, and gives rise to a forbidden K = 0 ← 3E intermode sub-band in the spectrum via intensity borrowing.

Giant K-doubling and in-plane/out-of-plane mixing in the asymmetric methyl-bending bands of CH 3SH

DOE PAGES

Guislain, B. G.; Reid, E. M.; Lees, R. M.; ...

2017-03-02

In analyzing high-resolution spectra of the methyl-deformation bands of methyl mercaptan recorded at the Canadian Light Source synchrotron, we have encountered interesting interactions between certain levels of the ν 4 in-plane asymmetric CH 3-bending mode and its ν 10 out-of-plane bending partner below. The origin of the K = 0A ν 4 substate is just 0.2 cm -1 higher than that of the K = 2A ν 10 substate, while the K = 0E ν 4 origin is only 0.035 cm -1 below the K = 2E ν 10 origin. These very close accidental near-degeneracies lead to substantial perturbations inmore » the spectrum. For the former, the A +/A - asymmetry K-doublet coupling rules are such that the A - component of the 2A ν 10 doublet interacts and mixes strongly with the 0A + ν 4 levels whereas the 2A + component is unaffected. The 2A - levels are pushed rapidly downwards by the coupling creating an extremely large apparent K = 2A asymmetry splitting. We call this “giant K-doubling” by analogy with a comparable phenomenon seen for methanol. The 0A + ν 4 state, in turn, is perturbed upward and passes through the descending K = 1A + ν 4 state between J = 22 and 23, leading to distinct local perturbations near the level-crossing. The 0E ν 4 and 2E ν 10 coupling produces a correspondingly strong repulsion and mixing between those two substates, and gives rise to a forbidden K = 0 ← 3E intermode sub-band in the spectrum via intensity borrowing.« less

Giant K-doubling and in-plane/out-of-plane mixing in the asymmetric methyl-bending bands of CH 3SH

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

Guislain, B. G.; Reid, E. M.; Lees, R. M.

In analyzing high-resolution spectra of the methyl-deformation bands of methyl mercaptan recorded at the Canadian Light Source synchrotron, we have encountered interesting interactions between certain levels of the ν 4 in-plane asymmetric CH 3-bending mode and its ν 10 out-of-plane bending partner below. The origin of the K = 0A ν 4 substate is just 0.2 cm -1 higher than that of the K = 2A ν 10 substate, while the K = 0E ν 4 origin is only 0.035 cm -1 below the K = 2E ν 10 origin. These very close accidental near-degeneracies lead to substantial perturbations inmore » the spectrum. For the former, the A +/A - asymmetry K-doublet coupling rules are such that the A - component of the 2A ν 10 doublet interacts and mixes strongly with the 0A + ν 4 levels whereas the 2A + component is unaffected. The 2A - levels are pushed rapidly downwards by the coupling creating an extremely large apparent K = 2A asymmetry splitting. We call this “giant K-doubling” by analogy with a comparable phenomenon seen for methanol. The 0A + ν 4 state, in turn, is perturbed upward and passes through the descending K = 1A + ν 4 state between J = 22 and 23, leading to distinct local perturbations near the level-crossing. The 0E ν 4 and 2E ν 10 coupling produces a correspondingly strong repulsion and mixing between those two substates, and gives rise to a forbidden K = 0 ← 3E intermode sub-band in the spectrum via intensity borrowing.« less

Vascular Adaptations to Transverse Aortic Banding in Mice

DTIC Science & Technology

2001-10-25

hypertrophy (B-C) via pressure overload. A Doppler probe (D) was used to measure flow velocity at the aortic valve (1), the mitral valve (2), the...L) carotid artery (CA), aortic, and mitral blood velocity 1 day later. At 7 days the heart- weight/body-weight ratio (HW/BW) was measured. Mean...aortic, mitral , and carotid velocities were similar in sham and banded mice, but peak RCA/LCA velocities were much higher in banded mice and were highly

A new low-cost 10 ns pulsed K(a)-band radar.

PubMed

Eskelinen, Pekka; Ylinen, Juhana

2011-07-01

Two Gunn oscillators, conventional intermediate frequency building blocks, and a modified GaAs diode detector are combined to form a portable monostatic 10 ns instrumentation radar for outdoor K(a)-band radar cross section measurements. At 37.8 GHz the radar gives +20 dBm output power and its tangential sensitivity is -76 dBm. Processing bandwidth is 125 MHz, which also allows for some frequency drift in the Gunn devices. Intra-pulse frequency chirp is less than 15 MHz. All functions are steered by a microcontroller. First measurements convince that the construction has a reasonable ability to reduce close-to-ground surface clutter and gives an effective way of resolving target detail. This is beneficial especially when amplitude fluctuations disturb measurements with longer pulses. The new unit operates on 12 V dc, draws a current of less than 3 A, and weighs 5 kg.

A monolithic K-band phase-locked loop for microwave radar application

NASA Astrophysics Data System (ADS)

Zhou, Guangyao; Ma, Shunli; Li, Ning; Ye, Fan; Ren, Junyan

2017-02-01

A monolithic K-band phase-locked loop (PLL) for microwave radar application is proposed and implemented in this paper. By eliminating the tail transistor and using optimized high-Q LC-tank, the proposed voltage-controlled oscillator (VCO) achieves a tuning range of 18.4 to 23.3 GHz and reduced phase noise. Two cascaded current-mode logic (CML) divide-by-two frequency prescalers are implemented to bridge the frequency gap, in which inductor peaking technique is used in the first stage to further boost allowable input frequency. Six-stage TSPC divider chain is used to provide programmable division ratio from 64 to 127, and a second-order passive loop filter with 825 kHz bandwidth is also integrated on-chip to minimize required external components. The proposed PLL needs only approximately 18.2 μs settling time, and achieves a wide tuning range from 18.4 to 23.3 GHz, with a typical output power of ‑0.84 dBm and phase noise of ‑91.92 dBc/Hz @ 1 MHz. The chip is implemented in TSMC 65 nm CMOS process, and occupies an area of 0.56 mm2 without pads under a 1.2 V single voltage supply. Project supported by the National High-Tech Research and Development Program of China (No. 2013AA014101).

k - dependent Jeff=1/2 band splitting and the electron-hole asymmetry in SrIrO3

NASA Astrophysics Data System (ADS)

Singh, Vijeta; Pulikkotil, J. J.

2017-02-01

The Ir ion in Srn+1 IrnO 3 n + 1 series of compounds is octahedrally coordinated. However, unlike Sr2IrO4 (n=1) and Sr3Ir2O7 (n=2) which are insulating due to spin-orbit induced Jeff splitting of the t2g bands, SrIrO3 (n= ∞) is conducting. To explore whether such a splitting is relevant in SrIrO3, and if so to what extent, we investigate the electronic structure of orthorhombic SrIrO3 using density functional theory. Calculations reveal that the crystal field split Ir t2 g bands in SrIrO3 are indeed split into Jeff=3/2 and and Jeff=1/2 states. However, the splitting is found to be strongly k - dependent with its magnitude determined by the Ir - O orbital hybridization. Besides, we find that the spin-orbit induced pseudo-gap, into which the Fermi energy is positioned, is composed of both light electron-like and heavy hole-like bands. These features in the band structure of SrIrO3 suggest that variations in the carrier concentration control the electronic transport properties in SrIrO3, which is consistent with the experiments.

Unsupervised Cryo-EM Data Clustering through Adaptively Constrained K-Means Algorithm

PubMed Central

Xu, Yaofang; Wu, Jiayi; Yin, Chang-Cheng; Mao, Youdong

2016-01-01

In single-particle cryo-electron microscopy (cryo-EM), K-means clustering algorithm is widely used in unsupervised 2D classification of projection images of biological macromolecules. 3D ab initio reconstruction requires accurate unsupervised classification in order to separate molecular projections of distinct orientations. Due to background noise in single-particle images and uncertainty of molecular orientations, traditional K-means clustering algorithm may classify images into wrong classes and produce classes with a large variation in membership. Overcoming these limitations requires further development on clustering algorithms for cryo-EM data analysis. We propose a novel unsupervised data clustering method building upon the traditional K-means algorithm. By introducing an adaptive constraint term in the objective function, our algorithm not only avoids a large variation in class sizes but also produces more accurate data clustering. Applications of this approach to both simulated and experimental cryo-EM data demonstrate that our algorithm is a significantly improved alterative to the traditional K-means algorithm in single-particle cryo-EM analysis. PMID:27959895

The Least Mean Squares Adaptive FIR Filter for Narrow-Band RFI Suppression in Radio Detection of Cosmic Rays

NASA Astrophysics Data System (ADS)

Szadkowski, Zbigniew; Głas, Dariusz

2017-06-01

Radio emission from the extensive air showers (EASs), initiated by ultrahigh-energy cosmic rays, was theoretically suggested over 50 years ago. However, due to technical limitations, successful collection of sufficient statistics can take several years. Nowadays, this detection technique is used in many experiments consisting in studying EAS. One of them is the Auger Engineering Radio Array (AERA), located within the Pierre Auger Observatory. AERA focuses on the radio emission, generated by the electromagnetic part of the shower, mainly in geomagnetic and charge excess processes. The frequency band observed by AERA radio stations is 30-80 MHz. Thus, the frequency range is contaminated by human-made and narrow-band radio frequency interferences (RFIs). Suppression of contaminations is very important to lower the rate of spurious triggers. There are two kinds of digital filters used in AERA radio stations to suppress these contaminations: the fast Fourier transform median filter and four narrow-band IIR-notch filters. Both filters have worked successfully in the field for many years. An adaptive filter based on a least mean squares (LMS) algorithm is a relatively simple finite impulse response (FIR) filter, which can be an alternative for currently used filters. Simulations in MATLAB are very promising and show that the LMS filter can be very efficient in suppressing RFI and only slightly distorts radio signals. The LMS algorithm was implemented into a Cyclone V field programmable gate array for testing the stability, RFI suppression efficiency, and adaptation time to new conditions. First results show that the FIR filter based on the LMS algorithm can be successfully implemented and used in real AERA radio stations.

K- and Ka-band mobile-vehicular satellite-tracking reflector antenna system for the NASA ACTS mobile terminal

NASA Technical Reports Server (NTRS)

Densmore, Art; Jamnejad, Vahraz; Wu, T. K.; Woo, Ken

1993-01-01

This paper describes the development of the K- and Ka-band mobile-vehicular satellite-tracking reflector antenna system for NASA's ACTS Mobile Terminal (AMT) project. ACTS is NASA's Advanced Communications Technology Satellites. The AMT project will make the first experimental use of ACTS soon after the satellite is operational, to demonstrate mobile communications via the satellite from a van on the road. The AMT antenna system consists of a mechanically steered small reflector antenna, using a shared aperture for both frequency bands and fitting under a radome of 23 cm diameter and 10 cm height, and a microprocessor controlled antenna controller that tracks the satellite as the vehicle moves about. The RF and mechanical characteristics of the antenna and the antenna tracking control system are discussed. Measurements of the antenna performance are presented.

Substrate integrated waveguide (SIW) 3 dB coupler for K-Band applications

NASA Astrophysics Data System (ADS)

Khalid, Nurehansafwanah; Zuraidah Ibrahim, Siti; Wee, Fwen Hoon; Shazuani Mahmud, Farah

2017-11-01

This paper presented a designed coupler by using Rogers RO4003C with thickness (h) 0.508 mm and relative permittivity (ɛr) 3.55. The four port network coupler operates in K-band (18-27 GHz) and design by using substrate integrated waveguide (SIW) method. The reflection coefficient and isolation coefficient of propose Substrate Integrated Waveguide (SIW) coupler is below than -10 dB. Meanwhile the coupler requirements are phase shift 90° between coupled port and output. SIW are high performance broadband interconnects with excellent immunity to electromagnetic interference and suitable for use in microwave and communication electronics, as well as increase bandwidth systems. The designs of coupler are investigated using CST Microwave Studio simulation tool. This proposed couplers are varied from parameters that cover the frequency range (21 -24 GHz) and better performance of scattering (S-parameter).

Measurement of pressure-broadening and lineshift coefficients at 77 and 296 K of methane lines in the 727 nm band using intracavity laser spectroscopy

NASA Technical Reports Server (NTRS)

Singh, Kuldip; O'Brien, James J.

1994-01-01

Pressure-broadening coefficients and pressure-induced lineshifts of several rotational-vibrational lines have been measured in the 727 nm absorption band of methane at temperatures of 77 and 296 K, using nitrogen, hydrogen, and helium as the foreign-gas collision partners. A technique involving intracavity laser spectroscopy is used to record the methane spectra. Average values of the broadening coefficients (/cm/atm) at 77 K are: 0.199, 0.139, 0.055, and 0.29 for collision partners N2, H2, He, and CH4, respectively. Typical average values of the pressure-induced lineshifts (/cm/atm) at 77 K and for the range of foreign gas pressures between 10 and 200 torr are -0.052 for N2, -0.063 for H2, and +0.031 for He. All the values obtained at 296 K are considerably different from the corresponding values at 77 K. This represents the first report of pressure-broadening and shifting coefficients for the methane transitions in a region where the delta nu(sub C-H) = 5 band occurs.

Automatic video shot boundary detection using k-means clustering and improved adaptive dual threshold comparison

NASA Astrophysics Data System (ADS)

Sa, Qila; Wang, Zhihui

2018-03-01

At present, content-based video retrieval (CBVR) is the most mainstream video retrieval method, using the video features of its own to perform automatic identification and retrieval. This method involves a key technology, i.e. shot segmentation. In this paper, the method of automatic video shot boundary detection with K-means clustering and improved adaptive dual threshold comparison is proposed. First, extract the visual features of every frame and divide them into two categories using K-means clustering algorithm, namely, one with significant change and one with no significant change. Then, as to the classification results, utilize the improved adaptive dual threshold comparison method to determine the abrupt as well as gradual shot boundaries.Finally, achieve automatic video shot boundary detection system.

Fade Mitigation Techniques at Ka-Band

NASA Technical Reports Server (NTRS)

Dissanayake, Asoka (Editor)

1996-01-01

Rain fading is the dominant propagation impairment affecting Ka-band satellite links and rain fade mitigation is a key element in the design of Ka-band satellite networks. Some of the common fade mitigation techniques include: power control, diversity, adaptive coding, and resource sharing. The Advanced Communications Technology Satellite (ACTS) provides an excellent opportunity to develop and test Ka-band rain impairment amelioration techniques. Up-link power control and diversity are discussed in this paper.

Adaptive phenotypic response to climate enabled by epigenetics in a K-strategy species, the fish Leucoraja ocellata (Rajidae)

PubMed Central

Incarnato, Danny; Ward, Ben J.; van Oosterhout, Cock; Bradbury, Ian; Hanson, Mark; Bentzen, Paul

2016-01-01

The relative importance of genetic versus epigenetic changes in adaptive evolution is a hotly debated topic, with studies showing that some species appear to be able to adapt rapidly without significant genetic change. Epigenetic mechanisms may be particularly important for the evolutionary potential of species with long maturation times and low reproductive potential (‘K-strategists’), particularly when faced with rapidly changing environmental conditions. Here we study the transcriptome of two populations of the winter skate (Leucoraja ocellata), a typical ‘K-strategist’, in Atlantic Canada; an endemic population in the southern Gulf of St Lawrence and a large population on the Scotian Shelf. The endemic population has been able to adapt to a 10°C higher water temperature over short evolutionary time (7000 years), dramatically reducing its body size (by 45%) significantly below the minimum maturation size of Scotian Shelf and other populations of winter skate, as well as exhibiting other adaptations in life history and physiology. We demonstrate that the adaptive response to selection has an epigenetic basis, cataloguing 3653 changes in gene expression that may have enabled this species to rapidly respond to the novel environment. We argue that the epigenetic augmentation of species evolutionary potential (its regulation though gene expression) can enable K-strategists to survive and adapt to different environments, and this mechanism may be particularly important for the persistence of sharks, skates and rays in the light of future climate change. PMID:27853546

ISM band to U-NII band frequency transverter and method of frequency transversion

DOEpatents

Stepp, Jeffrey David [Grandview, MO; Hensley, Dale [Grandview, MO

2006-04-04

A frequency transverter (10) and method for enabling bi-frequency dual-directional transfer of digitally encoded data on an RF carrier by translating between a crowded or otherwise undesirable first frequency band, such as the 2.4 GHz ISM band, and a less-crowded or otherwise desirable second frequency band, such as the 5.0 GHz-6.0 GHz U-NII band. In a preferred embodiment, the transverter (10) connects between an existing data radio (11) and its existing antenna (30), and comprises a bandswitch (12); an input RF isolating device (14); a transmuter (16); a converter (18); a dual output local oscillator (20); an output RF isolating device (22); and an antenna (24) tuned to the second frequency band. The bandswitch (12) allows for bypassing the transverter (10), thereby facilitating its use with legacy systems. The transmuter (14) and converter (16) are adapted to convert to and from, respectively, the second frequency band.

ISM band to U-NII band frequency transverter and method of frequency transversion

DOEpatents

Stepp, Jeffrey David [Grandview, MO; Hensley, Dale [Grandview, MO

2006-09-12

A frequency transverter (10) and method for enabling bi-frequency dual-directional transfer of digitally encoded data on an RF carrier by translating between a crowded or otherwise undesirable first frequency band, such as the 2.4 GHz ISM band, and a less-crowded or otherwise desirable second frequency band, such as the 5.0 GHz 6.0 GHz U-NII band. In a preferred embodiment, the transverter (10) connects between an existing data radio (11) and its existing antenna (30), and comprises a bandswitch (12); an input RF isolating device (14); a transmuter (16); a converter (18); a dual output local oscillator (20); an output RF isolating device (22); and an antenna (24) tuned to the second frequency band. The bandswitch (12) allows for bypassing the transverter (10), thereby facilitating its use with legacy systems. The transmuter (14) and converter (16) are adapted to convert to and from, respectively, the second frequency band.

Adaptation and validation of short scales for assessment of psychological distress in Iran: The Persian K10 and K6.

PubMed

Hajebi, Ahmad; Motevalian, Abbas; Amin-Esmaeili, Masoumeh; Rahimi-Movaghar, Afarin; Sharifi, Vandad; Hoseini, Leila; Shadloo, Behrang; Mojtabai, Ramin

2018-06-11

The aims of the study were to translate into Persian and culturally adapt the Kessler Psychological Distress Scales, K10 and K6, and to assess their reliability and validity. The sample was recruited from primary health care (PHC) settings by quota nonprobability sampling, stratified by sex and age. Validity was assessed against the Composite International Diagnostic Interview (v2.1). The psychometric properties of K6 and K10 were also compared with the 12-item General Health Questionnaire (GHQ-12). A total of 818 participants completed the questionnaire. Cronbach's alpha were 0.92 and 0.87 for K6 and K10, respectively. Optimal cutoff scores for detecting any mood or anxiety disorder in the past 30 days were 15 for K10 and 10 for K6. At these cutoff points, the measures had sensitivities of 0.77 and 0.73, specificities of 0.74 and 0.78, and positive predictive values of 0.48 and 0.52, respectively. Psychometric properties of K10 and K6 were similar to GHQ-12. Persian K10 and K6 have acceptable psychometric properties as screening instruments for common mental health conditions. Given its brevity and similar psychometric properties to the longer instruments, the Persian K6 appears to be a suitable for use in PHC settings and, possibly, epidemiologic studies in Iran. Copyright © 2018 John Wiley & Sons, Ltd.

Relations between broad-band linear polarization and Ca II H and K emission in late-type dwarf stars

NASA Technical Reports Server (NTRS)

Huovelin, Juhani; Saar, Steven H.; Tuominen, Ilkka

1988-01-01

Broadband UBV linear polarization data acquired for a sample of late-type dwarfs are compared with contemporaneous measurements of Ca II H and K line core emission. A weighted average of the largest values of the polarization degree is shown to be the best parameter for chromospheric activity diagnosis. The average maximum polarization in the UV is found to increase from late-F to late-G stars. It is noted that polarization in the U band is considerably more sensitive to activity variations than that in the B or V bands. The results indicate that stellar magnetic fields and the resulting saturation in the Zeeman-sensitive absorption lines are the most probably source of linear polarization in late-type main-sequence stars.

Calculation of the X-Ray emission K and L 2,3 bands of metallic magnesium and aluminum with allowance for multielectron effects

NASA Astrophysics Data System (ADS)

Ovcharenko, R. E.; Tupitsyn, I. I.; Savinov, E. P.; Voloshina, E. N.; Dedkov, Yu. S.; Shulakov, A. S.

2014-01-01

A procedure is proposed to calculate the shape of the characteristic X-ray emission bands of metals with allowance for multielectron effects. The effects of the dynamic screening of a core vacancy by conduction electrons and the Auger effect in the valence band are taken into account. The dynamic screening of a core vacancy, which is known to be called the MND (Mahan-Nozeieres-De Dominics) effect, is taken into account by an ab initio band calculation of crystals using the PAW (projected augmented waves) method. The Auger effect is taken into account by a semiempirical method using the approximation of a quadratic dependence of the level width in the valence band on the difference between the level energy and the Fermi energy. The proposed calculation procedure is used to describe the X-ray emission K and L 2,3 bands of metallic magnesium and aluminum crystals. The calculated spectra agree well with the experimental bands both near the Fermi level and in the low-energy part of the spectra in all cases.

Low-loss negative index metamaterials for X, Ku, and K microwave bands

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

Lee, David A.; Vedral, L. James; Smith, David A.

2015-04-15

Low-loss, negative-index of refraction metamaterials were designed and tested for X, Ku, and K microwave frequency bands. An S-shaped, split-ring resonator was used as a unit cell to design homogeneous slabs of negative-index metamaterials. Then, the slabs of metamaterials were cut unto prisms to measure experimentally the negative index of refraction of a plane electromagnetic wave. Theoretical simulations using High-Frequency Structural Simulator, a finite element equation solver, were in good agreement with experimental measurements. The negative index of refraction was retrieved from the angle- and frequency-dependence of the transmitted intensity of the microwave beam through the metamaterial prism and comparedmore » well to simulations; in addition, near-field electromagnetic intensity mapping was conducted with an infrared camera, and there was also a good match with the simulations for expected frequency ranges for the negative index of refraction.« less

Adaptive coding of MSS imagery. [Multi Spectral band Scanners

NASA Technical Reports Server (NTRS)

Habibi, A.; Samulon, A. S.; Fultz, G. L.; Lumb, D.

1977-01-01

A number of adaptive data compression techniques are considered for reducing the bandwidth of multispectral data. They include adaptive transform coding, adaptive DPCM, adaptive cluster coding, and a hybrid method. The techniques are simulated and their performance in compressing the bandwidth of Landsat multispectral images is evaluated and compared using signal-to-noise ratio and classification consistency as fidelity criteria.

Numerical simulation studies for the first-light adaptive optics system of the Large Binocular Telescope

NASA Astrophysics Data System (ADS)

Carbillet, Marcel; Riccardi, Armando; Esposito, Simone

2004-10-01

We present our latest results concerning the simulation studies performed for the first-light adaptive optics (AO) system of the Large Binocular Telescope (LBT), namely WLBT. After a brief description of the "raw" performance evaluation results, in terms of Strehl ratios attained in the various considered bands (from V to K), we focus on the "scientific" performance that will be obtained when considering the subsequent instrumentation that will benefit from the correction given by the AO system WLBT and the adaptive secondary mirrors LBT 672. In particular, we discuss the performance of the coupling with the instrument LUCIFER, working at near-infrared bands, in terms of signal-to-noise values and limiting magnitudes, and in both the cases of spectroscopy and photometric detection. We also give the encircled energies that are expected in the visible bands, result relevant in one hand for the instrument PEPSI, and in other hand for the "technical viewer" that will be on board the WLBT system itself.

Novel band gap-tunable K-Na co-doped graphitic carbon nitride prepared by molten salt method

NASA Astrophysics Data System (ADS)

Zhao, Jiannan; Ma, Lin; Wang, Haoying; Zhao, Yanfeng; Zhang, Jian; Hu, Shaozheng

2015-03-01

Novel band gap-tunable K-Na co-doped graphitic carbon nitride was prepared by molten salt method using melamine, KCl, and NaCl as precursor. X-ray diffraction (XRD), N2 adsorption, Scanning electron microscope (SEM), UV-vis spectroscopy, Photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared catalysts. The CB and VB potentials of graphitic carbon nitride could be tuned from -1.09 and +1.55 eV to -0.29 and +2.25 eV by controlling the weight ratio of eutectic salts to melamine. Besides, ions doping inhibited the crystal growth of graphitic carbon nitride, enhanced the surface area, and increased the separation rate of photogenerated electrons and holes. The visible-light-driven Rhodamine B (RhB) photodegradation and mineralization performances were significantly improved after K-Na co-doping.

A Novel Center Star Multiple Sequence Alignment Algorithm Based on Affine Gap Penalty and K-Band

NASA Astrophysics Data System (ADS)

Zou, Quan; Shan, Xiao; Jiang, Yi

Multiple sequence alignment is one of the most important topics in computational biology, but it cannot deal with the large data so far. As the development of copy-number variant(CNV) and Single Nucleotide Polymorphisms(SNP) research, many researchers want to align numbers of similar sequences for detecting CNV and SNP. In this paper, we propose a novel multiple sequence alignment algorithm based on affine gap penalty and k-band. It can align more quickly and accurately, that will be helpful for mining CNV and SNP. Experiments prove the performance of our algorithm.

New rotational bands in sup 166 Ho

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

Sheline, R.K.; Sood, P.C.; Baluba Mutshil

1989-08-01

The {ital K}{sup {pi}}=1{sup {minus}} and 0{sup {minus}} bands from the (1/2{sup +}(411){plus minus}(1/2{sup {minus}}(521))) configuration, and the {ital K}{sup {pi}}=1{sup {minus}} and 2{sup {minus}} bands from the (3/2{sup +}(411){plus minus}(1/2{sup {minus}}(521))) configuration have been identified for the first time largely using known but previously unused gamma transitions from the {sup 165}Ho({ital n},{gamma}) reaction. A remarkable similarity is shown to exist between the level structures of the {ital K}{sup {pi}}=1{sup {minus}} and 0{sup {minus}} bands from the (1/2{sup +}(411){plus minus}(1/2{sup {minus}}(521))) configurations in {sup 170}Tm and {sup 166}Ho.

WISEP J061135.13-041024.0 AB: A J-band Flux Reversal Binary at the L/T Transition

NASA Astrophysics Data System (ADS)

Gelino, Christopher R.; Smart, R. L.; Marocco, Federico; Kirkpatrick, J. Davy; Cushing, Michael C.; Mace, Gregory; Mendez, Rene A.; Tinney, C. G.; Jones, Hugh R. A.

2014-07-01

We present Keck II laser guide star adaptive optics observations of the brown dwarf WISEP J061135.13-041024.0 showing it is a binary with a component separation of 0.''4. This system is one of the six known resolved binaries in which the magnitude differences between the components show a reversal in sign between the Y/J band and the H/K bands. Deconvolution of the composite spectrum results in a best-fit binary solution with L9 and T1.5 components. We also present a preliminary parallax placing the system at a distance of 21.2 ± 1.3 pc. Using the distance and resolved magnitudes we are able to place WISEP J061135.13-041024.0 AB on a color-absolute magnitude diagram, showing that this system contributes to the well-known "J-band bump" and the components' properties appear similar to other late-type L and early-type T dwarfs. Fitting our data to a set of cloudy atmosphere models suggests the system has an age >1 Gyr with WISE 0611-0410 A having an effective temperature (T eff) of 1275-1325 K and mass of 64-65 M Jup, and WISE 0611-0410 B having T eff = 1075-1115 K and mass 40-65 M Jup.

Improved spectral absorption coefficient grouping strategy of wide band k-distribution model used for calculation of infrared remote sensing signal of hot exhaust systems

NASA Astrophysics Data System (ADS)

Hu, Haiyang; Wang, Qiang

2018-07-01

A new strategy for grouping spectral absorption coefficients, considering the influences of both temperature and species mole ratio inhomogeneities on correlated-k characteristics of the spectra of gas mixtures, has been deduced to match the calculation method of spectral overlap parameter used in multiscale multigroup wide band k-distribution model. By comparison with current spectral absorption coefficient grouping strategies, for which only the influence of temperature inhomogeneity on the correlated-k characteristics of spectra of single species was considered, the improvements in calculation accuracies resulting from the new grouping strategy were evaluated using a series of 0D cases in which radiance under 3-5-μm wave band emitted by hot combustion gas of hydrocarbon fuel was attenuated by atmosphere with quite different temperature and mole ratios of water vapor and carbon monoxide to carbon dioxide. Finally, evaluations are presented on the calculation of remote sensing thermal images of transonic hot jet exhausted from a chevron ejecting nozzle with solid wall cooling system.

Ku band low noise parametric amplifier

NASA Technical Reports Server (NTRS)

1976-01-01

A low noise, K sub u-band, parametric amplifier (paramp) was developed. The unit is a spacecraft-qualifiable, prototype, parametric amplifier for eventual application in the shuttle orbiter. The amplifier was required to have a noise temperature of less than 150 K. A noise temperature of less than 120 K at a gain level of 17 db was achieved. A 3-db bandwidth in excess of 350 MHz was attained, while deviation from phase linearity of about + or - 1 degree over 50 MHz was achieved. The paramp operates within specification over an ambient temperature range of -5 C to +50 C. The performance requirements and the operation of the K sub u-band parametric amplifier system are described. The final test results are also given.

THE INFLUENCE OF RED SPIRAL GALAXIES ON THE SHAPE OF THE LOCAL K-BAND LUMINOSITY FUNCTION

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

Bonne, Nicolas J.; Brown, Michael J. I.; Jones, Heath

2015-02-01

We have determined K-band luminosity functions for 13,325 local universe galaxies as a function of morphology and color (for K {sub tot} ≤ 10.75). Our sample is drawn from the Two Micron All Sky Survey Extended Source Catalog, with all sample galaxies having measured morphologies and distances (including 4219 archival redshift-independent distances). The luminosity function for our total sample is in good agreement with previous works, but is relatively smooth at faint magnitudes (due to bulk flow distance corrections). We investigated the differences due to morphological and color selection using 5417 sample galaxies with NASA Sloan Atlas optical colors and find thatmore » red spirals comprise 20%-50% of all spirals with –25 ≤ M{sub K}  < –20. Fainter than M{sub K} = –24, red spirals are as common as early types, explaining the different faint end slopes (α = –0.87 and –1.00 for red and early-types, respectively). While we find red spirals comprise more than 50% of all M{sub K}  < –25 spiral galaxies, they do not dominate the bright end of the overall red galaxy luminosity function, which is dominated by early-type galaxies. The brightest red spirals have ongoing star formation and those without are frequently misclassified as early-types. The faintest ones have an appearance and Sérsic indices consistent with faded disks, rather than true bulge-dominated galaxies.« less

ALMA Band 5 receiver cartridge. Design, performance, and commissioning

NASA Astrophysics Data System (ADS)

Belitsky, V.; Bylund, M.; Desmaris, V.; Ermakov, A.; Ferm, S.-E.; Fredrixon, M.; Krause, S.; Lapkin, I.; Meledin, D.; Pavolotsky, A.; Rashid, H.; Shafiee, S.; Strandberg, M.; Sundin, E.; Aghdam, P. Yadranjee; Hesper, R.; Barkhof, J.; Bekema, M. E.; Adema, J.; Haan, R. de; Koops, A.; Boland, W.; Yagoubov, P.; Marconi, G.; Siringo, G.; Humphreys, E.; Tan, G. H.; Laing, R.; Testi, L.; Mroczkowski, T.; Wild, W.; Saini, K. S.; Bryerton, E.

2018-04-01

We describe the design, performance, and commissioning results for the new ALMA Band 5 receiver channel, 163-211 GHz, which is in the final stage of full deployment and expected to be available for observations in 2018. This manuscript provides the description of the new ALMA Band 5 receiver cartridge and serves as a reference for observers using the ALMA Band 5 receiver for observations. At the time of writing this paper, the ALMA Band 5 Production Consortium consisting of NOVA Instrumentation group, based in Groningen, NL, and GARD in Sweden have produced and delivered to ALMA Observatory over 60 receiver cartridges. All 60 cartridges fulfil the new more stringent specifications for Band 5 and demonstrate excellent noise temperatures, typically below 45 K single sideband (SSB) at 4 K detector physical temperature and below 35 K SSB at 3.5 K (typical for operation at the ALMA Frontend), providing the average sideband rejection better than 15 dB, and the integrated cross-polarization level better than -25 dB. The 70 warm cartridge assemblies, hosting Band 5 local oscillator and DC bias electronics, have been produced and delivered to ALMA by NRAO. The commissioning results confirm the excellent performance of the receivers.

Delayed rectifier K channels contribute to contrast adaptation in mammalian retinal ganglion cells

PubMed Central

Weick, Michael; Demb, Jonathan B.

2011-01-01

SUMMARY Retinal ganglion cells adapt by reducing their sensitivity during periods of high contrast. Contrast adaptation in the firing response depends on both presynaptic and intrinsic mechanisms. Here, we investigated intrinsic mechanisms for contrast adaptation in OFF Alpha ganglion cells in the in vitro guinea pig retina. Using either visual stimulation or current injection, we show that brief depolarization evoked spiking and suppressed firing during subsequent depolarization. The suppression could be explained by Na channel inactivation, as shown in salamander cells. However, brief hyperpolarization in the physiological range (5–10 mV) also suppressed firing during subsequent depolarization. This suppression was sensitive selectively to blockers of delayed-rectifier K channels (KDR). Somatic membrane patches showed TEA-sensitive KDR currents with activation near −25 mV and removal of inactivation at voltages negative to Vrest. Brief periods of hyperpolarization apparently remove KDR inactivation and thereby increase the channel pool available to suppress excitability during subsequent depolarization. PMID:21745646

Violations of K-Conservation in 178Hf

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

Hayes, A. B.; Cline, D.; Wu, C. Y.

2006-03-13

Coulomb excitation of K{pi}=6+(t1/2=77 ns), 8-(t1/2=4.0 s) and 16+(t1/2=31 y) 178Hf isomers has led to the measurement of a set of E{lambda} matrix elements, coupling the isomer bands to the {gamma}- and ground state bands. The resulting matrix elements, derived using a coupled-channel semiclassical Coulomb excitation search code, have been used to probe the K-components in the wave functions and revealed the onset and saturation of K-mixing in low-K bands, whereas K-mixing is negligible in the high-K bands. The implications can be applied to other quadrupole-deformed nuclei. An upper limit on the Coulomb depopulation yield of the 16+ isomer wasmore » calculated based on the present set of matrix elements.« less

Location of the valence band maximum in the band structure of anisotropic 1 T'-ReSe2

NASA Astrophysics Data System (ADS)

Eickholt, P.; Noky, J.; Schwier, E. F.; Shimada, K.; Miyamoto, K.; Okuda, T.; Datzer, C.; Drüppel, M.; Krüger, P.; Rohlfing, M.; Donath, M.

2018-04-01

Transition-metal dichalcogenides (TMDCs) are a focus of current research due to their fascinating optical and electronic properties with possible technical applications. ReSe2 is an interesting material of the TMDC family, with unique anisotropic properties originating from its distorted 1 T structure (1 T '). To develop a fundamental understanding of the optical and electric properties, we studied the underlying electronic structure with angle-resolved photoemission (ARPES) as well as band-structure calculations within the density functional theory (DFT)-local density approximation (LDA) and GdW approximations. We identified the Γ ¯M¯1 direction, which is perpendicular to the a axis, as a distinct direction in k space with the smallest bandwidth of the highest valence band. Using photon-energy-dependent ARPES, two valence band maxima are identified within experimental limits of about 50 meV: one at the high-symmetry point Z , and a second one at a non-high-symmetry point in the Brillouin zone. Thus, the position in k space of the global valence band maximum is undecided experimentally. Theoretically, an indirect band gap is predicted on a DFT-LDA level, while quasiparticle corrections lead to a direct band gap at the Z point.

NASA Rat Acoustic Tolerance Test 1994-1995: 8 kHz, 16 kHz, 32 kHz Experiments

NASA Technical Reports Server (NTRS)

Mele, Gary D.; Holley, Daniel C.; Naidu, Sujata

1996-01-01

Adult male Sprague-Dawley rats were exposed to chronic applied sound (74 to 79 dB, SPL) with octave band center frequencies of either 8, 16 or 32 kHz for up to 60 days. Control cages had ambient sound levels of about 62 dB (SPL). Groups of rats (test vs. control; N=9 per group) were euthanized after 0. 5. 14, 30, and 60 days. On each euthanasia day, objective evaluation of their physiology and behavior was performed using a Stress Assessment Battery (SAB) of measures. In addition, rat hearing was assessed using the brain stem auditory evoked potential (BAER) method after 60 days of exposure. No statistically significant differences in mean daily food use could be attributed to the presence of the applied test sound. Test rats used 5% more water than control rats. In the 8 kHz and 32 kHz tests this amount was statistically significant(P less than .05). This is a minor difference of questionable physiological significance. However, it may be an indication of a small reaction to the constant applied sound. Across all test frequencies, day 5 test rats had 6% larger spleens than control rats. No other body or organ weight differences were found to be statistically significant with respect to the application of sound. This spleen effect may be a transient adaptive process related to adaptation to the constant applied noise. No significant test effect on differential white blood cell counts could be demonstrated. One group demonstrated a low eosinophil count (16 kHz experiment, day 14 test group). However this was highly suspect. Across all test frequencies studied, day 5 test rats had 17% fewer total leukocytes than day 5 control rats. Sound exposed test rats exhibited 44% lower plasma corticosterone concentrations than did control rats. Note that the plasma corticosterone concentration was lower in the sound exposed test animals than the control animals in every instance (frequency exposure and number of days exposed).

Simulation of radar backscattering from snowpack at X-band and Ku-band

NASA Astrophysics Data System (ADS)

Gay, Michel; Phan, Xuan-Vu; Ferro-Famil, Laurent

2016-04-01

This paper presents a multilayer snowpack electromagnetic backscattering model, based on Dense Media Radiative Transfer (DMRT). This model is capable of simulating the interaction of electromagnetic wave (EMW) at X-band and Ku-band frequencies with multilayer snowpack. The air-snow interface and snow-ground backscattering components are calculated using the Integral Equation Model (IEM) by [1], whereas the volume backscattering component is calculated based on the solution of Vector Radiative Transfer (VRT) equation at order 1. Case study has been carried out using measurement data from NoSREx project [2], which include SnowScat data in X-band and Ku-band, TerraSAR-X acquisitions and snowpack stratigraphic in-situ measurements. The results of model simulations show good agreement with the radar observations, and therefore allow the DMRT model to be used in various applications, such as data assimilation [3]. [1] A.K. Fung and K.S. Chen, "An update on the iem surface backscattering model," Geoscience and Remote Sensing Letters, IEEE, vol. 1, no. 2, pp. 75 - 77, april 2004. [2] J. Lemmetyinen, A. Kontu, J. Pulliainen, A. Wiesmann, C. Werner, T. Nagler, H. Rott, and M. Heidinger, "Technical assistance for the deployment of an x- to ku-band scatterometer during the nosrex ii experiment," Final Report, ESA ESTEC Contract No. 22671/09/NL/JA., 2011. [3] X. V. Phan, L. Ferro-Famil, M. Gay, Y. Durand, M. Dumont, S. Morin, S. Allain, G. D'Urso, and A. Girard, "3d-var multilayer assimilation of x-band sar data into a detailed snowpack model," The Cryosphere Discussions, vol. 7, no. 5, pp. 4881-4912, 2013.

The Multiwavelength Survey by Yale-Chile (MUSYC): Wide K-Band Imaging, Photometric Catalogs, Clustering, and Physical Properties of Galaxies at z {approx} 2

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

Blanc, Guillermo A.; Lira, Paulina; Francke, Harold

2008-07-10

We present K-band imaging of two {approx}30{sup '} x 30{sup '} fields covered by the Multiwavelength Survey by Yale-Chile (MUSYC) Wide NIR Survey. The SDSS 1030+05 and Cast 1255 fields were imaged with the Infrared Side Port Imager (ISPI) on the 4 m Blanco telescope at the Cerro Tololo Inter-American Observatory (CTIO) to a 5 {sigma} point-source limiting depth of K {approx} 20 (Vega). Combining these data with the MUSYC optical UBVRIz imaging, we created multiband K-selected source catalogs for both fields. These catalogs, together with the MUSYC K-band catalog of the Extended Chandra Deep Field South (ECDF-S) field, weremore » used to select K < 20 BzK galaxies over an area of 0.71 deg{sup 2}. This is the largest area ever surveyed for BzK galaxies. We present number counts, redshift distributions, and stellar masses for our sample of 3261 BzK galaxies (2502 star-forming [sBzK] and 759 passively evolving [pBzK]), as well as reddening and star formation rate estimates for the star-forming BzK systems. We also present two-point angular correlation functions and spatial correlation lengths for both sBzK and pBzK galaxies and show that previous estimates of the correlation function of these galaxies were affected by cosmic variance due to the small areas surveyed. We have measured correlation lengths r{sub 0} of 8.89 {+-} 2.03 and 10.82 {+-} 1.72 Mpc for sBzK and pBzK galaxies, respectively. This is the first reported measurement of the spatial correlation function of passive BzK galaxies. In the {lambda}CDM scenario of galaxy formation, these correlation lengths at z {approx} 2 translate into minimum masses of {approx}4 x 10{sup 12} and {approx}9 x 10{sup 12} M{sub sun} for the dark matter halos hosting sBzK and pBzK galaxies, respectively. The clustering properties of the galaxies in our sample are consistent with their being the descendants of bright Lyman break galaxies at z {approx} 3, and the progenitors of present-day >1L{sup *} galaxies.« less

Tunable Narrow Band Emissions from Dye-Sensitized Core/Shell/Shell Nanocrystals in the Second Near-Infrared Biological Window

PubMed Central

Shao, Wei; Chen, Guanying; Kuzmin, Andrey; Kutscher, Hilliard L.; Pliss, Artem; Ohulchanskyy, Tymish Y.; Prasad, Paras N.

2017-01-01

We introduce a hybrid organic–inorganic system consisting of epitaxial NaYF4:Yb3+/X3+@NaYbF4@NaYF4:Nd3+ (X = null, Er, Ho, Tm, or Pr) core/shell/shell (CSS) nanocrystal with organic dye, indocyanine green (ICG) on the nanocrystal surface. This system is able to produce a set of narrow band emissions with a large Stokes-shift (>200 nm) in the second biological window of optical transparency (NIR-II, 1000–1700 nm), by directional energy transfer from light-harvesting surface ICG, via lanthanide ions in the shells, to the emitter X3+ in the core. Surface ICG not only increases the NIR-II emission intensity of inorganic CSS nanocrystals by ~4-fold but also provides a broadly excitable spectral range (700–860 nm) that facilitates their use in bioapplications. We show that the NIR-II emission from ICG-sensitized Er3+-doped CSS nanocrystals allows clear observation of a sharp image through 9 mm thick chicken breast tissue, and emission signal detection through 22 mm thick tissue yielding a better imaging profile than from typically used Yb/Tm-codoped upconverting nanocrystals imaged in the NIR-I region (700–950 nm). Our result on in vivo imaging suggests that these ICG-sensitized CSS nanocrystals are suitable for deep optical imaging in the NIR-II region. PMID:27935695

Valley-dependent band structure and valley polarization in periodically modulated graphene

NASA Astrophysics Data System (ADS)

Lu, Wei-Tao

2016-08-01

The valley-dependent energy band and transport property of graphene under a periodic magnetic-strained field are studied, where the time-reversal symmetry is broken and the valley degeneracy is lifted. The considered superlattice is composed of two different barriers, providing more degrees of freedom for engineering the electronic structure. The electrons near the K and K' valleys are dominated by different effective superlattices. It is found that the energy bands for both valleys are symmetric with respect to ky=-(AM+ξ AS) /4 under the symmetric superlattices. More finite-energy Dirac points, more prominent collimation behavior, and new crossing points are found for K' valley. The degenerate miniband near the K valley splits into two subminibands and produces a new band gap under the asymmetric superlattices. The velocity for the K' valley is greatly renormalized compared with the K valley, and so we can achieve a finite velocity for the K valley while the velocity for the K' valley is zero. Especially, the miniband and band gap could be manipulated independently, leading to an increase of the conductance. The characteristics of the band structure are reflected in the transmission spectra. The Dirac points and the crossing points appear as pronounced peaks in transmission. A remarkable valley polarization is obtained which is robust to the disorder and can be controlled by the strain, the period, and the voltage.

Thermal adaptation of the crucian carp (Carassius carassius) cardiac delayed rectifier current, IKs, by homomeric assembly of Kv7.1 subunits without MinK.

PubMed

Hassinen, Minna; Laulaja, Salla; Paajanen, Vesa; Haverinen, Jaakko; Vornanen, Matti

2011-07-01

Ectothermic vertebrates experience acute and chronic temperature changes which affect cardiac excitability and may threaten electrical stability of the heart. Nevertheless, ectothermic hearts function over wide range of temperatures without cardiac arrhythmias, probably due to special molecular adaptations. We examine function and molecular basis of the slow delayed rectifier K(+) current (I(Ks)) in cardiac myocytes of a eurythermic fish (Carassius carassius L.). I(Ks) is an important repolarizing current that prevents excessive prolongation of cardiac action potential, but it is extremely slowly activating when expressed in typical molecular composition of the endothermic animals. Comparison of the I(Ks) of the crucian carp atrial myocytes with the currents produced by homomeric K(v)7.1 and heteromeric K(v)7.1/MinK channels in Chinese hamster ovary cells indicates that activation kinetics and pharmacological properties of the I(Ks) are similar to those of the homomeric K(v)7.1 channels. Consistently with electrophysiological properties and homomeric K(v)7.1 channel composition, atrial transcript expression of the MinK subunit is only 1.6-1.9% of the expression level of the K(v)7.1 subunit. Since activation kinetics of the homomeric K(v)7.1 channels is much faster than activation of the heteromeric K(v)7.1/MinK channels, the homomeric K(v)7.1 composition of the crucian carp cardiac I(Ks) is thermally adaptive: the slow delayed rectifier channels can open despite low body temperatures and curtail the duration of cardiac action potential in ectothermic crucian carp. We suggest that the homomeric K(v)7.1 channel assembly is an evolutionary thermal adaptation of ectothermic hearts and the heteromeric K(v)7.1/MinK channels evolved later to adapt I(Ks) to high body temperature of endotherms.

Forskolin suppresses delayed-rectifier K+ currents and enhances spike frequency-dependent adaptation of sympathetic neurons.

PubMed

Angel-Chavez, Luis I; Acosta-Gómez, Eduardo I; Morales-Avalos, Mario; Castro, Elena; Cruzblanca, Humberto

2015-01-01

In signal transduction research natural or synthetic molecules are commonly used to target a great variety of signaling proteins. For instance, forskolin, a diterpene activator of adenylate cyclase, has been widely used in cellular preparations to increase the intracellular cAMP level. However, it has been shown that forskolin directly inhibits some cloned K+ channels, which in excitable cells set up the resting membrane potential, the shape of action potential and regulate repetitive firing. Despite the growing evidence indicating that K+ channels are blocked by forskolin, there are no studies yet assessing the impact of this mechanism of action on neuron excitability and firing patterns. In sympathetic neurons, we find that forskolin and its derivative 1,9-Dideoxyforskolin, reversibly suppress the delayed rectifier K+ current (IKV). Besides, forskolin reduced the spike afterhyperpolarization and enhanced the spike frequency-dependent adaptation. Given that IKV is mostly generated by Kv2.1 channels, HEK-293 cells were transfected with cDNA encoding for the Kv2.1 α subunit, to characterize the mechanism of forskolin action. Both drugs reversible suppressed the Kv2.1-mediated K+ currents. Forskolin inhibited Kv2.1 currents and IKV with an IC50 of ~32 μM and ~24 µM, respectively. Besides, the drug induced an apparent current inactivation and slowed-down current deactivation. We suggest that forskolin reduces the excitability of sympathetic neurons by enhancing the spike frequency-dependent adaptation, partially through a direct block of their native Kv2.1 channels.

The predictive roles of neural oscillations in speech motor adaptability.

PubMed

Sengupta, Ranit; Nasir, Sazzad M

2016-06-01

The human speech system exhibits a remarkable flexibility by adapting to alterations in speaking environments. While it is believed that speech motor adaptation under altered sensory feedback involves rapid reorganization of speech motor networks, the mechanisms by which different brain regions communicate and coordinate their activity to mediate adaptation remain unknown, and explanations of outcome differences in adaption remain largely elusive. In this study, under the paradigm of altered auditory feedback with continuous EEG recordings, the differential roles of oscillatory neural processes in motor speech adaptability were investigated. The predictive capacities of different EEG frequency bands were assessed, and it was found that theta-, beta-, and gamma-band activities during speech planning and production contained significant and reliable information about motor speech adaptability. It was further observed that these bands do not work independently but interact with each other suggesting an underlying brain network operating across hierarchically organized frequency bands to support motor speech adaptation. These results provide novel insights into both learning and disorders of speech using time frequency analysis of neural oscillations. Copyright © 2016 the American Physiological Society.

EMI survey for maritime satellite, L-band, shipboard terminal

NASA Technical Reports Server (NTRS)

Taylor, R. E.; Brandel, D. L.; Hill, J. S.

1975-01-01

The paper presents results of an onboard EMI survey of an L-band shipboard terminal for operation with two geostationary maritime satellites. Significant EMC results include: (1) antenna noise temperature measurements indicate a maximum of 70 K steady background component at 1.6 GHz at sea for elevation angles of 5 degrees and higher; (2) field intensity measurements from 1-10 GHz show that a L-band terminal can operate simultaneously with onboard S-band and X-band navigation radar; (3) radar transmitter case emissions, below deck, in-band from 1535-1660 MHz, at 1 m distance from the cabinet, are equivalent, or greater than above-deck emissions in the same frequency range; and (4) conducted-emission tests of a ship's power lines to both radars show both narrow band and broad band emissions are 15 dB to 50 dB higher than equivalent U.S. commercial power lines from 150 kHz to 32 MHz.

75 FR 17799 - AB Liquidating Corp. (f/k/a Adaptive Broadband Corp.), Globalnet Corp., Greenland Corp...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-07

... SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] AB Liquidating Corp. (f/k/a Adaptive Broadband Corp.), Globalnet Corp., Greenland Corp., KeraVision, Inc., Lifespan, Inc., STAR Telecommunications... concerning the securities of STAR Telecommunications, Inc. because it has not filed any periodic reports...

Molecular characterization of a Cryptosporidium isolate from a banded mongoose Mungos mungo.

PubMed

Abe, Niichiro; Takami, Kazutoshi; Kimata, Isao; Iseki, Motohiro

2004-02-01

Cryptosporidium spp. has been found in more than 150 species of mammals, but there has been no report in mongooses. In this study, we report the isolation of Cryptosporidium sp. in a banded mongoose Mungos mungo, which was brought from Tanzania to Japan; the isolate was analyzed genetically to validate the occurrence of a new, host-adapted genotype. Cryptosporidium diagnostic fragments of 18S ribosomal RNA and 70-kDa heat shock protein genes were amplified from this isolate and compared with the other Cryptosporidium species and genotypes reported previously. Analyses showed that the mongoose isolate represents a new genotype, closely related to that of bears.

Hazard banding in compliance with the new Globally Harmonised System (GHS) for use in control banding tools.

PubMed

Arnone, Mario; Koppisch, Dorothea; Smola, Thomas; Gabriel, Stefan; Verbist, Koen; Visser, Remco

2015-10-01

Many control banding tools use hazard banding in risk assessments for the occupational handling of hazardous substances. The outcome of these assessments can be combined with advice for the required risk management measures (RMMs). The Globally Harmonised System of Classification and Labelling of Chemicals (GHS) has resulted in a change in the hazard communication elements, i.e. Hazard (H) statements instead of Risk-phrases. Hazard banding schemes that depend on the old form of safety information have to be adapted to the new rules. The purpose of this publication is to outline the rationales for the assignment of hazard bands to H statements under the GHS. Based on this, this publication proposes a hazard banding scheme that uses the information from the safety data sheets as the basis for assignment. The assignment of hazard bands tiered according to the severity of the underlying hazards supports the important principle of substitution. Additionally, the set of assignment rules permits an exposure-route-specific assignment of hazard bands, which is necessary for the proposed route-specific RMMs. Ideally, all control banding tools should apply the same assignment rules. This GHS-compliant hazard banding scheme can hopefully help to establish a unified hazard banding strategy in the various control banding tools. Copyright © 2015 Elsevier Inc. All rights reserved.

Forskolin Suppresses Delayed-Rectifier K+ Currents and Enhances Spike Frequency-Dependent Adaptation of Sympathetic Neurons

PubMed Central

Castro, Elena; Cruzblanca, Humberto

2015-01-01

In signal transduction research natural or synthetic molecules are commonly used to target a great variety of signaling proteins. For instance, forskolin, a diterpene activator of adenylate cyclase, has been widely used in cellular preparations to increase the intracellular cAMP level. However, it has been shown that forskolin directly inhibits some cloned K+ channels, which in excitable cells set up the resting membrane potential, the shape of action potential and regulate repetitive firing. Despite the growing evidence indicating that K+ channels are blocked by forskolin, there are no studies yet assessing the impact of this mechanism of action on neuron excitability and firing patterns. In sympathetic neurons, we find that forskolin and its derivative 1,9-Dideoxyforskolin, reversibly suppress the delayed rectifier K+ current (IKV). Besides, forskolin reduced the spike afterhyperpolarization and enhanced the spike frequency-dependent adaptation. Given that IKV is mostly generated by Kv2.1 channels, HEK-293 cells were transfected with cDNA encoding for the Kv2.1 α subunit, to characterize the mechanism of forskolin action. Both drugs reversible suppressed the Kv2.1-mediated K+ currents. Forskolin inhibited Kv2.1 currents and IKV with an IC50 of ~32 μM and ~24 µM, respectively. Besides, the drug induced an apparent current inactivation and slowed-down current deactivation. We suggest that forskolin reduces the excitability of sympathetic neurons by enhancing the spike frequency-dependent adaptation, partially through a direct block of their native Kv2.1 channels. PMID:25962132

NASA's Evolution to K(sub a)- Band Space Communications for Near-Earth Spacecraft

NASA Technical Reports Server (NTRS)

McCarthy, Kevin P.; Stocklin, Frank J.; Geldzahler, Barry J.; Friedman, Daniel E.; Celeste, Peter B.

2010-01-01

Over the next several years, NASA plans to launch multiple earth-science missions which will send data from low-Earth orbits to ground stations at 1-3 Gbps, to achieve data throughputs of 5-40 terabits per day. These transmission rates exceed the capabilities of S-band and X-band frequency allocations used for science probe downlinks in the past. Accordingly, NASA is exploring enhancements to its space communication capabilities to provide the Agency's first Ka-band architecture solution for next generation missions in the near-earth regime. This paper describes the proposed Ka-band solution's drivers and concept, constraints and analyses which shaped that concept, and expansibility for future needs

Near-Infrared Spectroscopy of the Y0 WISEP J173835.52+273258.9 and the Y1 WISE J035000.32-565830.2: the Importance of Non-Equilibrium Chemistry

NASA Technical Reports Server (NTRS)

Leggett, S. K.; Tremblin, P.; Saumon, D.; Marley, M. S.; Morley, Caroline V.; Amundsen, D. S.; Baraffe, I.; Chabrier, G.

2016-01-01

We present new near-infrared spectra, obtained at Gemini Observatory, for two Y dwarfs: WISE J035000.32-565830.2 (W0350) and WISEP J173835.52+273258.9 (W1738). A FLAMINGOS-2 R = 540 spectrum was obtained for W0350, covering 1.0 < ? micrometer < 1.7, and a cross-dispersed GNIRS R = 2800 spectrum was obtained for W1738, covering 0.993 - 1.087 micrometer, 1.191 - 1.305 micrometer, 1.589 - 1.631 micrometer, and 1.985 - 2.175 micrometer, in four orders. We also present revised Y JH photometry for W1738, using new NIRI Y and J imaging, and a re-analysis of the previously published NIRI H band images. We compare these data, together with previously published data for late-T and Y dwarfs, to cloud-free models of solar metallicity, calculated both in chemical equilibrium and with disequilibrium driven by vertical transport. We find that for the Y dwarfs the non-equilibrium models reproduce the near-infrared data better than the equilibrium models. The remaining discrepancies suggest that fine-tuning the CH4/CO and NH3/N2 balance is needed. Improved trigonometric parallaxes would improve the analysis. Despite the uncertainties and discrepancies, the models reproduce the observed near-infrared spectra well. We find that for the Y0, W1738, T(sub eff) = 425 +/- 25K and log g = 4.0 +/- 0.25, and for the Y1, W0350, T(sub eff) = 350 +/- 25K and log g = 4.0 +/- 0.25. W1738 may be metal-rich. Based on evolutionary models, these temperatures and gravities correspond to a mass range for both Y dwarfs of 3 - 9 Jupiter masses, with W0350 being a cooler, slightly older, version of W1738; the age of W0350 is 0.3 - 3 Gyr, and the age of W1738 is 0.15 - 1 Gyr.

Simultaneous functional near-infrared brain imaging and event-related potential studies of Stroop effect

NASA Astrophysics Data System (ADS)

Zhai, Jiahuan; Li, Ting; Zhang, Zhongxing; Gong, Hui

2009-02-01

Functional near-infrared brain imaging (fNIRI) and event-related potential (ERP) were used simultaneous to detect the prefrontal cortex (PFC) which is considered to execute cognitive control of the subjects while performing the Chinese characters color-word matching Stroop task with event-related design. The fNIRI instrument is a portable system operating at three wavelengths (735nm & 805nm &850nm) with continuous-wave. The event-related potentials were acquired by Neuroscan system. The locations of optodes corresponding to the electrodes were defined four areas symmetrically. In nine native Chinese-speaking fit volunteers, fNIRI measured the hemodynamic parameters (involving oxy-/deoxy- hemoglobin) changes when the characteristic waveforms (N500/P600) were recorded by ERP. The interference effect was obvious as a longer reaction time for incongruent than congruent and neutral stimulus. The responses of hemodynamic and electrophysiology were also stronger during incongruent compared to congruent and neutral trials, and these results are similar to those obtained with fNIRI or ERP separately. There are high correlations, even linear relationship, in the two kinds of signals. In conclusion, the multi-modality approach combining of fNIRI and ERP is feasible and could obtain more cognitive function information with hemodynamic and electrophysiology signals. It also provides a perspective to prove the neurovascular coupling mechanism.

Design studies of the Ku-band, wide-band Gyro-TWT amplifier

NASA Astrophysics Data System (ADS)

Jung, Sang Wook; Lee, Han Seul; Jang, Kwong Ho; Choi, Jin Joo; Hong, Yong Jun; Shin, Jin Woo; So, Jun Ho; Won, Jong Hyo

2014-02-01

This paper reports a Ku-band, wide band Gyrotron-Traveling-wave-tube(Gyro-TWT) that is currently being developed at Kwangwoon University. The Gyro-TWT has a two stage linear tapered interaction circuit to obtain a wide operating bandwidth. The linearly-tapered interaction circuit and nonlinearly-tapered magnetic field gives the Gyro-TWT a wide operating bandwidth. The Gyro-TWT bandwidth is 23%. The 2d-Particle-in-cell(PIC) and MAGIC2d code simulation results are 17.3 dB and 24.34 kW, respectively for the maximum saturated output power. A double anode MIG was simulated with E-Gun code. The results were 0.7 for the transvers to the axial beam velocity ratio (=alpha) and a 2.3% axial velocity spread at 50 kV and 4 A. A magnetic field profile simulation was performed by using the Poisson code to obtain the grazing magnetic field of the entire interaction circuit with Poisson code.

Acousto-optic modulation of a photonic crystal nanocavity with Lamb waves in microwave K band

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

Tadesse, Semere A.; School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455; Li, Huan

2015-11-16

Integrating nanoscale electromechanical transducers and nanophotonic devices potentially can enable acousto-optic devices to reach unprecedented high frequencies and modulation efficiency. Here, we demonstrate acousto-optic modulation of a photonic crystal nanocavity using Lamb waves with frequency up to 19 GHz, reaching the microwave K band. The devices are fabricated in suspended aluminum nitride membrane. Excitation of acoustic waves is achieved with interdigital transducers with period as small as 300 nm. Confining both acoustic wave and optical wave within the thickness of the membrane leads to improved acousto-optic modulation efficiency in these devices than that obtained in previous surface acoustic wave devices. Ourmore » system demonstrates a scalable optomechanical platform where strong acousto-optic coupling between cavity-confined photons and high frequency traveling phonons can be explored.« less

Time-domain digital pre-equalization for band-limited signals based on receiver-side adaptive equalizers.

PubMed

Zhang, Junwen; Yu, Jianjun; Chi, Nan; Chien, Hung-Chang

2014-08-25

We theoretically and experimentally investigate a time-domain digital pre-equalization (DPEQ) scheme for bandwidth-limited optical coherent communication systems, which is based on feedback of channel characteristics from the receiver-side blind and adaptive equalizers, such as least-mean-squares (LMS) algorithm and constant or multi- modulus algorithms (CMA, MMA). Based on the proposed DPEQ scheme, we theoretically and experimentally study its performance in terms of various channel conditions as well as resolutions for channel estimation, such as filtering bandwidth, taps length, and OSNR. Using a high speed 64-GSa/s DAC in cooperation with the proposed DPEQ technique, we successfully synthesized band-limited 40-Gbaud signals in modulation formats of polarization-diversion multiplexed (PDM) quadrature phase shift keying (QPSK), 8-quadrature amplitude modulation (QAM) and 16-QAM, and significant improvement in both back-to-back and transmission BER performances are also demonstrated.

Adaptive optics system for Cassegrain focus of SUBARU 8.2-m telescope

NASA Astrophysics Data System (ADS)

Takami, Hideki; Takato, Naruhisa; Otsubo, Masashi; Kanzawa, Tomio; Kamata, Yukiko; Nakashima, Koji; Iye, Masanori

1998-09-01

The adaptive optics system for Subaru 8.2m telescope of the National Astronomical Observatory Japan has been developed for the Cassegrain ear-IR instruments, CIAO and IRCS. The system consists of a wavefront curvature sensor with 36 subaperture photon-counting avalanche photodiode modules and a bimorph deformable mirror with 36 electrodes. The expected Strehl ratio at K band exceeds 0.4 for objects that are located close enough to a bright guide star as faint as R equals 16 mag at the median seeing of 0.45 arcsec at Mauna Kea. The system will be in operation in 1999 as a natural guide star system, and will eventually be upgraded to a laser guide star system in cooperating an IR wavefront tilt sensor to provide nearly full sky. The construction of this common use system to Subaru telescope is now underway in our laboratory in Tokyo. Prior to starting the fabrication of this common use system, a full size prototype system was constructed and tested with the 1.6 m IR telescope at our observatory in Tokyo. This system has the identical optical design, deformable mirror, loop control computer to those for the Subaru system, while the wavefront sensing detectors were less-sensitive analog APDs. We succeeded in getting closed loop images of stars in K band with diffraction limited core. The Strehl ratio was around 0.5 and the factor of improvement was about 20 at K-band under the average seeing of 2 arcsec during the observation. The loop sped of the system was 2 K corrections per second.

First Principles Study of Band Structure and Band Gap Engineering in Graphene for Device Applications

DTIC Science & Technology

2015-03-20

In the bandstructure of graphene which is dominated by Dirac description, valence and conduction bands cross the Fermi level at a single point (K...of energy bands and appearance of Dirac cones near the ‘K’ point and Fermi level the electrons behave like massless Dirac fermions. For applications...results. Introduction Graphene, the super carbon , is now accepted as wonder material with new physics and it has caused major

Oral Rehabilitation for Amniotic Band Syndrome: An Unusual Presentation.

PubMed

Hotwani, Kavita; Sharma, Krishna

2015-01-01

Amniotic band syndrome (ABS) is a congenital disorder caused by entrapment of fetal parts in fibrous amniotic bands while in utero. The syndrome is underdiagnosed and its presentation is variable. The syndrome has been well described in the pediatric, orthopedic and obstetric literature; however, despite the discernable craniomaxillofacial involvement, ABS has not been reported in the dental literature very often. The present report describes a case of a patient with ABS and concomitant dental findings. How to cite this article: Hotwani K, Sharma K. Oral Rehabilitation for Amniotic Band Syndrome: An Unusual Presentation. Int J Clin Pediatr Dent 2015;8(1):55-57.

A narrow-band k-distribution model with single mixture gas assumption for radiative flows

NASA Astrophysics Data System (ADS)

Jo, Sung Min; Kim, Jae Won; Kwon, Oh Joon

2018-06-01

In the present study, the narrow-band k-distribution (NBK) model parameters for mixtures of H2O, CO2, and CO are proposed by utilizing the line-by-line (LBL) calculations with a single mixture gas assumption. For the application of the NBK model to radiative flows, a radiative transfer equation (RTE) solver based on a finite-volume method on unstructured meshes was developed. The NBK model and the RTE solver were verified by solving two benchmark problems including the spectral radiance distribution emitted from one-dimensional slabs and the radiative heat transfer in a truncated conical enclosure. It was shown that the results are accurate and physically reliable by comparing with available data. To examine the applicability of the methods to realistic multi-dimensional problems in non-isothermal and non-homogeneous conditions, radiation in an axisymmetric combustion chamber was analyzed, and then the infrared signature emitted from an aircraft exhaust plume was predicted. For modeling the plume flow involving radiative cooling, a flow-radiation coupled procedure was devised in a loosely coupled manner by adopting a Navier-Stokes flow solver based on unstructured meshes. It was shown that the predicted radiative cooling for the combustion chamber is physically more accurate than other predictions, and is as accurate as that by the LBL calculations. It was found that the infrared signature of aircraft exhaust plume can also be obtained accurately, equivalent to the LBL calculations, by using the present narrow-band approach with a much improved numerical efficiency.

The band systems of alkali vapors

NASA Technical Reports Server (NTRS)

Weizel, W.; Kulp, M.

1988-01-01

A number of band edges of the molecules, Na2, K2, NaK, NaCs, LiK, LiRb, LiCs, and NaRb are arranged in edge schemes. The vibrational quanta of the base terms and the upper terms can be approximately determined. Viewpoints are produced for interpreting electron terms. The terms Na2 are interpreted as terms of a photo-electron.

A K-band Frequency Agile Microstrip Bandpass Filter using a Thin Film HTS/Ferroelectric/dielectric Multilayer Configuration

NASA Technical Reports Server (NTRS)

Subramanyam, Guru; VanKeuls, Fred; Miranda, Felix A.

1998-01-01

We report on YBa2Cu3O(7-delta) (YBCO) thin film/SrTiO3 (STO) thin film K-band tunable bandpass filters on LaAlO3 (LAO) dielectric substrates. The 2 pole filter has a center frequency of 19 GHz and a 4% bandwidth. Tunability is achieved through the non-linear dc electric field dependence of the relative dielectric constant of STO(epsilon(sub rSTO). A large tunability ((Delta)f/f(sub 0) = (f(sub Vmax) - f(sub 0)/f(sub 0), where f(sub 0) is the center frequency of the filter at no bias and f(sub Vmax) is the center frequency of the filter at the maximum applied bias) of greater than 10% was obtained in YBCO/STO/LAO microstrip bandpass filters operating below 77 K. A center frequency shift of 2.3 GHz (i.e., a tunability factor of approximately 15%) was obtained at a 400 V bipolar dc bias, and 30 K, with minimal degradation in the insertion loss of the filter. This paper addresses design, fabrication and testing of tunable filters based on STO ferroelectric thin films. The performance of the YBCO/STO/LAO filters is compared to that of gold/STO/LAO counterparts.

Band connectivity for topological quantum chemistry: Band structures as a graph theory problem

NASA Astrophysics Data System (ADS)

Bradlyn, Barry; Elcoro, L.; Vergniory, M. G.; Cano, Jennifer; Wang, Zhijun; Felser, C.; Aroyo, M. I.; Bernevig, B. Andrei

2018-01-01

The conventional theory of solids is well suited to describing band structures locally near isolated points in momentum space, but struggles to capture the full, global picture necessary for understanding topological phenomena. In part of a recent paper [B. Bradlyn et al., Nature (London) 547, 298 (2017), 10.1038/nature23268], we have introduced the way to overcome this difficulty by formulating the problem of sewing together many disconnected local k .p band structures across the Brillouin zone in terms of graph theory. In this paper, we give the details of our full theoretical construction. We show that crystal symmetries strongly constrain the allowed connectivities of energy bands, and we employ graph theoretic techniques such as graph connectivity to enumerate all the solutions to these constraints. The tools of graph theory allow us to identify disconnected groups of bands in these solutions, and so identify topologically distinct insulating phases.

Nitrogen-Pressure Shifts in the v3 Band of Methane Measured at Several Temperatures between 300 and 90 K

NASA Technical Reports Server (NTRS)

Tumuhimbise, Anthony T.; Hurtmans, Daniel; Mantz, Arlan W.; Mondelain, Didier

2008-01-01

Remote sensing of the Earth's atmosphere requires accurate knowledge of spectroscopic line parameters for the molecules investigated. Knowledge of the temperature dependence of these parameters is also essential if agreement, at the noise level, between calculated and experimental data is to be achieved. The authors recently published results of nitrogen broadening measurements in the v3 band of 12CH4 using the 5.37 m long absorption path length all-copper Herriott cell. The temperature dependent line parameters determined in the laboratory were applied to fit a portion of the atmospheric spectrum recorded with a balloon-borne remote sensing FTIR instrument, called the Limb Profile Monitor of the Atmosphere, and operating in absorption against the sun. Since the authors had a relatively complete series of data for the P(9) transition in the v3 band of 12CH4, the A2 1 as well as the F2 1, F1 1 and A1 1 lines recorded at different pressures and at four temperatures between 300 and 90 K, we reanalyzed the data to derive pressure shift information at different temperatures. The temperatures for which data were collected and analyzed are 298, 140 and 90K. The high precision pressure shift data obtained here over a large range of temperature demonstrate the ability of our experimental arrangement to address specific questions on a given spectral window like in the balloon experiment or in a satellite project, for example.

Oral Rehabilitation for Amniotic Band Syndrome: An Unusual Presentation

PubMed Central

Sharma, Krishna

2015-01-01

ABSTRACT Amniotic band syndrome (ABS) is a congenital disorder caused by entrapment of fetal parts in fibrous amniotic bands while in utero. The syndrome is underdiagnosed and its presentation is variable. The syndrome has been well described in the pediatric, orthopedic and obstetric literature; however, despite the discernable craniomaxillofacial involvement, ABS has not been reported in the dental literature very often. The present report describes a case of a patient with ABS and concomitant dental findings. How to cite this article: Hotwani K, Sharma K. Oral Rehabilitation for Amniotic Band Syndrome: An Unusual Presentation. Int J Clin Pediatr Dent 2015;8(1):55-57. PMID:26124582

2D Raman band splitting in graphene: Charge screening and lifting of the K-point Kohn anomaly.

PubMed

Wang, Xuanye; Christopher, Jason W; Swan, Anna K

2017-10-19

Pristine graphene encapsulated in hexagonal boron nitride has transport properties rivalling suspended graphene, while being protected from contamination and mechanical damage. For high quality devices, it is important to avoid and monitor accidental doping and charge fluctuations. The 2D Raman double peak in intrinsic graphene can be used to optically determine charge density, with decreasing peak split corresponding to increasing charge density. We find strong correlations between the 2D 1 and 2D 2 split vs 2D line widths, intensities, and peak positions. Charge density fluctuations can be measured with orders of magnitude higher precision than previously accomplished using the G-band shift with charge. The two 2D intrinsic peaks can be associated with the "inner" and "outer" Raman scattering processes, with the counterintuitive assignment of the phonon closer to the K point in the KM direction (outer process) as the higher energy peak. Even low charge screening lifts the phonon Kohn anomaly near the K point for graphene encapsulated in hBN, and shifts the dominant intensity from the lower to the higher energy peak.

Does the chromatic Mach bands effect exist?

PubMed

Tsofe, Avital; Spitzer, Hedva; Einav, Shmuel

2009-06-30

The achromatic Mach bands effect is a well-known visual illusion, discovered over a hundred years ago. This effect has been investigated thoroughly, mainly for its brightness aspect. The existence of Chromatic Mach bands, however, has been disputed. In recent years it has been reported that Chromatic Mach bands are not perceived under controlled iso-luminance conditions. However, here we show that a variety of Chromatic Mach bands, consisting of chromatic and achromatic regions, separated by a saturation ramp, can be clearly perceived under iso-luminance and iso-brightness conditions. In this study, observers' eye movements were recorded under iso-brightness conditions. Several observers were tested for their ability to perceive the Chromatic Mach bands effect and its magnitude, across different cardinal and non-cardinal Chromatic Mach bands stimuli. A computational model of color adaptation, which predicted color induction and color constancy, successfully predicts this variation of Chromatic Mach bands. This has been tested by measuring the distance of the data points from the "achromatic point" and by calculating the shift of the data points from predicted complementary lines. The results suggest that the Chromatic Mach bands effect is a specific chromatic induction effect.

The Role of Na+ and K+ Transporters in Salt Stress Adaptation in Glycophytes

PubMed Central

Assaha, Dekoum V. M.; Ueda, Akihiro; Saneoka, Hirofumi; Al-Yahyai, Rashid; Yaish, Mahmoud W.

2017-01-01

Ionic stress is one of the most important components of salinity and is brought about by excess Na+ accumulation, especially in the aerial parts of plants. Since Na+ interferes with K+ homeostasis, and especially given its involvement in numerous metabolic processes, maintaining a balanced cytosolic Na+/K+ ratio has become a key salinity tolerance mechanism. Achieving this homeostatic balance requires the activity of Na+ and K+ transporters and/or channels. The mechanism of Na+ and K+ uptake and translocation in glycophytes and halophytes is essentially the same, but glycophytes are more susceptible to ionic stress than halophytes. The transport mechanisms involve Na+ and/or K+ transporters and channels as well as non-selective cation channels. Thus, the question arises of whether the difference in salt tolerance between glycophytes and halophytes could be the result of differences in the proteins or in the expression of genes coding the transporters. The aim of this review is to seek answers to this question by examining the role of major Na+ and K+ transporters and channels in Na+ and K+ uptake, translocation and intracellular homeostasis in glycophytes. It turns out that these transporters and channels are equally important for the adaptation of glycophytes as they are for halophytes, but differential gene expression, structural differences in the proteins (single nucleotide substitutions, impacting affinity) and post-translational modifications (phosphorylation) account for the differences in their activity and hence the differences in tolerance between the two groups. Furthermore, lack of the ability to maintain stable plasma membrane (PM) potentials following Na+-induced depolarization is also crucial for salt stress tolerance. This stable membrane potential is sustained by the activity of Na+/H+ antiporters such as SOS1 at the PM. Moreover, novel regulators of Na+ and K+ transport pathways including the Nax1 and Nax2 loci regulation of SOS1 expression and

Band gap scaling laws in group IV nanotubes.

PubMed

Wang, Chongze; Fu, Xiaonan; Guo, Yangyang; Guo, Zhengxiao; Xia, Congxin; Jia, Yu

2017-03-17

By using the first-principles calculations, the band gap properties of nanotubes formed by group IV elements have been investigated systemically. Our results reveal that for armchair nanotubes, the energy gaps at K points in the Brillouin zone decrease as 1/r scaling law with the radii (r) increasing, while they are scaled by -1/r 2  + C at Γ points, here, C is a constant. Further studies show that such scaling law of K points is independent of both the chiral vector and the type of elements. Therefore, the band gaps of nanotubes for a given radius can be determined by these scaling laws easily. Interestingly, we also predict the existence of indirect band gap for both germanium and tin nanotubes. Our new findings provide an efficient way to determine the band gaps of group IV element nanotubes by knowing the radii, as well as to facilitate the design of functional nanodevices.

Band excitation method applicable to scanning probe microscopy

DOEpatents

Jesse, Stephen [Knoxville, TN; Kalinin, Sergei V [Knoxville, TN

2010-08-17

Methods and apparatus are described for scanning probe microscopy. A method includes generating a band excitation (BE) signal having finite and predefined amplitude and phase spectrum in at least a first predefined frequency band; exciting a probe using the band excitation signal; obtaining data by measuring a response of the probe in at least a second predefined frequency band; and extracting at least one relevant dynamic parameter of the response of the probe in a predefined range including analyzing the obtained data. The BE signal can be synthesized prior to imaging (static band excitation), or adjusted at each pixel or spectroscopy step to accommodate changes in sample properties (adaptive band excitation). An apparatus includes a band excitation signal generator; a probe coupled to the band excitation signal generator; a detector coupled to the probe; and a relevant dynamic parameter extractor component coupled to the detector, the relevant dynamic parameter extractor including a processor that performs a mathematical transform selected from the group consisting of an integral transform and a discrete transform.

Band excitation method applicable to scanning probe microscopy

DOEpatents

Jesse, Stephen; Kalinin, Sergei V

2013-05-28

Methods and apparatus are described for scanning probe microscopy. A method includes generating a band excitation (BE) signal having finite and predefined amplitude and phase spectrum in at least a first predefined frequency band; exciting a probe using the band excitation signal; obtaining data by measuring a response of the probe in at least a second predefined frequency band; and extracting at least one relevant dynamic parameter of the response of the probe in a predefined range including analyzing the obtained data. The BE signal can be synthesized prior to imaging (static band excitation), or adjusted at each pixel or spectroscopy step to accommodate changes in sample properties (adaptive band excitation). An apparatus includes a band excitation signal generator; a probe coupled to the band excitation signal generator; a detector coupled to the probe; and a relevant dynamic parameter extractor component coupled to the detector, the relevant dynamic parameter extractor including a processor that performs a mathematical transform selected from the group consisting of an integral transform and a discrete transform.

Energy Metabolic Adaptation and Cardiometabolic Improvements One Year After Gastric Bypass, Sleeve Gastrectomy, and Gastric Band.

PubMed

Tam, Charmaine S; Redman, Leanne M; Greenway, Frank; LeBlanc, Karl A; Haussmann, Mark G; Ravussin, Eric

2016-10-01

It is not known whether the magnitude of metabolic adaptation, a greater than expected drop in energy expenditure, depends on the type of bariatric surgery and is associated with cardiometabolic improvements. To compare changes in energy expenditure (metabolic chamber) and circulating cardiometabolic markers 8 weeks and 1 year after Roux-en-y bypass (RYGB), sleeve gastrectomy (SG), laparoscopic adjustable gastric band (LAGB), or a low-calorie diet (LCD). Design, Setting, Participants, and Intervention: This was a parallel-arm, prospective observational study of 30 individuals (27 females; mean age, 46 ± 2 years; body mass index, 47.2 ± 1.5 kg/m 2 ) either self-selecting bariatric surgery (five RYGB, nine SG, seven LAGB) or on a LCD (n = 9) intervention (800 kcal/d for 8 weeks, followed by weight maintenance). After 1 year, the RYGB and SG groups had similar degrees of body weight loss (33-36%), whereas the LAGB and LCD groups had 16 and 4% weight loss, respectively. After adjusting for changes in body composition, 24-hour energy expenditure was significantly decreased in all treatment groups at 8 weeks (-254 to -82 kcal/d), a drop that only persisted in RYGB (-124 ± 42 kcal/d; P = .002) and SG (-155 ± 118 kcal/d; P = .02) groups at 1 year. The degree of metabolic adaptation (24-hour and sleeping energy expenditure) was not significantly different between the treatment groups at either time-point. Plasma high-density lipoprotein and total and high molecular weight adiponectin were increased, and triglycerides and high-sensitivity C-reactive protein levels were reduced 1 year after RYGB or SG. Metabolic adaptation of approximately 150 kcal/d occurs after RYGB and SG surgery. Future studies are required to examine whether these effects remain beyond 1 year.

Sub-band/transform compression of video sequences

NASA Technical Reports Server (NTRS)

Sauer, Ken; Bauer, Peter

1992-01-01

The progress on compression of video sequences is discussed. The overall goal of the research was the development of data compression algorithms for high-definition television (HDTV) sequences, but most of our research is general enough to be applicable to much more general problems. We have concentrated on coding algorithms based on both sub-band and transform approaches. Two very fundamental issues arise in designing a sub-band coder. First, the form of the signal decomposition must be chosen to yield band-pass images with characteristics favorable to efficient coding. A second basic consideration, whether coding is to be done in two or three dimensions, is the form of the coders to be applied to each sub-band. Computational simplicity is of essence. We review the first portion of the year, during which we improved and extended some of the previous grant period's results. The pyramid nonrectangular sub-band coder limited to intra-frame application is discussed. Perhaps the most critical component of the sub-band structure is the design of bandsplitting filters. We apply very simple recursive filters, which operate at alternating levels on rectangularly sampled, and quincunx sampled images. We will also cover the techniques we have studied for the coding of the resulting bandpass signals. We discuss adaptive three-dimensional coding which takes advantage of the detection algorithm developed last year. To this point, all the work on this project has been done without the benefit of motion compensation (MC). Motion compensation is included in many proposed codecs, but adds significant computational burden and hardware expense. We have sought to find a lower-cost alternative featuring a simple adaptation to motion in the form of the codec. In sequences of high spatial detail and zooming or panning, it appears that MC will likely be necessary for the proposed quality and bit rates.

Comparison of retention and demineralization inhibition potential of adhesive banding cements in primary teeth.

PubMed

Prabhakar, A R; Mahantesh, T; Ahuja, Vipin

2010-01-01

The purpose of this study was to evaluate the efficacy of banding cements in terms of retentive capability and demineralization inhibition potential. We included 48 non-carious primary mandibular second molar teeth. Preformed stainless steel bands were adapted onto the teeth. All teeth were randomly assigned to four groups: Group I (Adaptation of bands without cementation), Group II (Cementation of bands using conventional Glass Ionomer Cement), Group III (Cementation of bands using Resin-modified Glass Ionomer Cement), Group IV (Cementation of bands using Resin cement), and placed in artificial saliva. Each day, specimens were taken from artificial saliva and suspended in an artificial caries solution for 35 minutes, every 8 hours. At the end of 3 months, retention of bands was estimated using an Instron Universal Testing Machine. The mode of failure was recorded and specimens were sectioned and examined under polarized microscope for demineralized lesions. The mean retention value was highest with resin cement, followed by RMGIC, GIC, and Control group respectively. The RMGIC group showed more favorable modes of failures. All the experimental groups showed significant demineralization inhibition potential. RMGIC is the preferable banding cement and can be used effectively to cement bands in primary dentition.

Cultural adaptation of a peer-led lifestyle intervention program for diabetes prevention in India: the Kerala diabetes prevention program (K-DPP).

PubMed

Mathews, Elezebeth; Thomas, Emma; Absetz, Pilvikki; D'Esposito, Fabrizio; Aziz, Zahra; Balachandran, Sajitha; Daivadanam, Meena; Thankappan, Kavumpurathu Raman; Oldenburg, Brian

2018-01-04

Type 2 diabetes mellitus (T2DM) is now one of the leading causes of disease-related deaths globally. India has the world's second largest number of individuals living with diabetes. Lifestyle change has been proven to be an effective means by which to reduce risk of T2DM and a number of "real world" diabetes prevention trials have been undertaken in high income countries. However, systematic efforts to adapt such interventions for T2DM prevention in low- and middle-income countries have been very limited to date. This research-to-action gap is now widely recognised as a major challenge to the prevention and control of diabetes. Reducing the gap is associated with reductions in morbidity and mortality and reduced health care costs. The aim of this article is to describe the adaptation, development and refinement of diabetes prevention programs from the USA, Finland and Australia to the State of Kerala, India. The Kerala Diabetes Prevention Program (K-DPP) was adapted to Kerala, India from evidence-based lifestyle interventions implemented in high income countries, namely, Finland, United States and Australia. The adaptation process was undertaken in five phases: 1) needs assessment; 2) formulation of program objectives; 3) program adaptation and development; 4) piloting of the program and its delivery; and 5) program refinement and active implementation. The resulting program, K-DPP, includes four key components: 1) a group-based peer support program for participants; 2) a peer-leader training and support program for lay people to lead the groups; 3) resource materials; and 4) strategies to stimulate broader community engagement. The systematic approach to adaptation was underpinned by evidence-based behavior change techniques. K-DPP is the first well evaluated community-based, peer-led diabetes prevention program in India. Future refinement and utilization of this approach will promote translation of K-DPP to other contexts and population groups within India as

Na+/K+-ATPase resistance and cardenolide sequestration: basal adaptations to host plant toxins in the milkweed bugs (Hemiptera: Lygaeidae: Lygaeinae)

PubMed Central

Bramer, Christiane; Dobler, Susanne; Deckert, Jürgen; Stemmer, Michael; Petschenka, Georg

2015-01-01

Despite sequestration of toxins being a common coevolutionary response to plant defence in phytophagous insects, the macroevolution of the traits involved is largely unaddressed. Using a phylogenetic approach comprising species from four continents, we analysed the ability to sequester toxic cardenolides in the hemipteran subfamily Lygaeinae, which is widely associated with cardenolide-producing Apocynaceae. In addition, we analysed cardenolide resistance of their Na+/K+-ATPases, the molecular target of cardenolides. Our data indicate that cardenolide sequestration and cardenolide-resistant Na+/K+-ATPase are basal adaptations in the Lygaeinae. In two species that shifted to non-apocynaceous hosts, the ability to sequester was secondarily reduced, yet Na+/K+-ATPase resistance was maintained. We suggest that both traits evolved together and represent major coevolutionary adaptations responsible for the evolutionary success of lygaeine bugs. Moreover, specialization on cardenolides was not an evolutionary dead end, but enabled this insect lineage to host shift to cardenolide-producing plants from distantly related families. PMID:25808891

Investigations on GSK-3β/NF-kB signaling in stress and stress adaptive behavior in electric foot shock subjected mice.

PubMed

Bali, Anjana; Jaggi, Amteshwar Singh

2016-04-01

The present study was designed to explore the role of GSK-3β and NF-kB signaling in electric foot shock-induced stress and stress adaptation. Mice were subjected to foot shocks of 0.5mA intensity and 1s duration of 1h to produce acute stress. Animals were exposed to the same stressor for 5 days to induce stress adaptation. The behavioral alterations were assessed using the actophotometer, hole board, open field and social interaction tests. The serum corticosterone levels were assessed as a marker of the HPA axis. The levels of total GSK-3β, p-GSK-3β-S9 and p-NF-kB were determined in the hippocampus, frontal cortex and amygdala. Acute electric foot shock stress produced behavioral and biochemical changes; decreased the levels of p-GSK-3β-S9, produced no change in total GSK-3β levels and increased p-NF-kB levels in the brain. However, repeated exposure of foot shock stress restored the behavioral and biochemical changes along with normalization of p-GSK-3β-S9 and p-NF-kB levels. Administration of AR-A01, a selective GSK-3β inhibitor, or diethyldithiocarbamic acid (DDTC), a selective NF-kB inhibitor, diminished acute stress-induced behavioral and biochemical changes. Furthermore, AR-A014418 normalized acute stress-induced alterations in p-GSK-3β-S9 and p-NF-kB levels, however, DDTC selectively restored NF-kB levels without any change in p-GSK-3β-S9 levels. It probably suggests that NF-kB is a downstream mediator of the GSK-3 signaling cascade. It may conclude that acute stress associated decrease in p-GSK-3β-S9 and increase in p-NF-kB levels in the brain contribute in the development of behavioral and biochemical alterations and normalization of GSK-3β/NF-kB signaling may contribute in stress adaptive behavior in response to repeated electric foot shock-subjected mice. Copyright © 2016 Elsevier B.V. All rights reserved.

Modification of electronic properties of graphene by using low-energy K{sup +} ions

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

Kim, Jingul; Lee, Paengro; Ryu, Mintae

2016-05-02

Despite its superb electronic properties, the semi-metallic nature of graphene with no band gap (E{sub g}) at the Dirac point has been a stumbling block for its industrial application. We report an improved means of producing a tunable band gap over other schemes by doping low energy (10 eV) potassium ions (K{sup +}) on single layer graphene formed on 6H-SiC(0001) surface, where the noble Dirac nature of the π-band remains almost unaltered. The changes in the π-band induced by K{sup +} ions reveal that the band gap increases gradually with increasing dose (θ) of the ions up to E{sub g} = 0.65 eV atmore » θ = 1.10 monolayers, demonstrating the tunable character of the band gap. Our core level data for C 1s, Si 2p, and K 2p suggest that the K{sup +}-induced asymmetry in charge distribution among carbon atoms drives the opening of band gap, which is in sharp contrast with no band gap when neutral K atoms are adsorbed on graphene. This tunable K{sup +}-induced band gap in graphene illustrates its potential application in graphene-based nano-electronics.« less

RNA Editing Underlies Temperature Adaptation in K+ Channels from Polar Octopuses

PubMed Central

Garrett, Sandra; Rosenthal, Joshua J.C.

2014-01-01

To operate in the extreme cold, ion channels from psychrophiles must have evolved structural changes to compensate for their thermal environment. A reasonable assumption would be that the underlying adaptations lie within the encoding genes. Here we show that delayed rectifier K+ channel genes from an Antarctic and a tropical octopus encode channels that differ at only four positions and display very similar behavior when expressed in Xenopus oocytes. However, the transcribed mRNAs are extensively edited, creating functional diversity. One editing site, which recodes an isoleucine to a valine in the channel’s pore, greatly accelerates gating kinetics by destabilizing the open state. This site is extensively edited in both Antarctic and Arctic species, but mostly unedited in tropical species. Thus A-to-I RNA editing can respond to the physical environment. PMID:22223739

Analysis of Archival Low-Resolution Near-Infrared Spectra to Measure Pluto's Atmosphere.

NASA Astrophysics Data System (ADS)

Cook, Jason C.; Young, Leslie; Cruikshank, Dale P.

2017-10-01

First detected via occultation observations, Pluto's atmosphere has changed since its discovery in the 1980s (Brosch & Mendelson, 1985; Elliot et al., 1989). Between the occultations of 1988 and 2002, the surface pressure doubled (Elliot et al., 2003) as Pluto passed through perihelion in 1989. In the years following the 2002 occultation, only a slight increase in the surface pressure has been noted (Young et al. 2013; Olkin et al. 2015). High-resolution spectroscopy has also been used to determine the composition of Pluto's atmosphere. This was first successfully done in 1992 (Young et al., 1997), but no follow up detection was made until 2008 (Lellouch et al. 2009). With a gap in the occultation and spectroscopic records, we have little information on how and when Pluto's atmosphere changed. In order to fill in this gap, we are examining low spectral resolution, high signal-to-noise spectra of Pluto such as Cook et al (2014) presented previously. At this meeting, we will report on additional archive observations from Gemini. These data were taken between 2004 and 2008 using the NIRI+Altair (adaptive optics instrument) and GNIRS instruments. These have resolving powers (λ/Δλ) of ~600 and 6000, respectively. Both data sets cover the K-band spectral range (1.95 to 2.40 μm) where gaseous CH4 has several strong lines, such as the ν3+ν4 Q-branch near 2.317 μm.Funding for this work has been provided by NASA-PATM grant NNX12AK62G.

The brittle-viscous-plastic evolution of shear bands in the South Armorican Shear Zone

NASA Astrophysics Data System (ADS)

Bukovská, Zita; Jeřábek, Petr; Morales, Luiz F. G.; Lexa, Ondrej; Milke, Ralf

2014-05-01

Shear bands are microscale shear zones that obliquely crosscut an existing anisotropy such as a foliation. The resulting S-C fabrics are characterized by angles lower than 45° and the C plane parallel to shear zone boundaries. The S-C fabrics typically occur in granitoids deformed at greenschist facies conditions in the vicinity of major shear zones. Despite their long recognition, mechanical reasons for localization of deformation into shear bands and their evolution is still poorly understood. In this work we focus on microscale characterization of the shear bands in the South Armorican Shear Zone, where the S-C fabrics were first recognized by Berthé et al. (1979). The initiation of shear bands in the right-lateral South Armorican Shear Zone is associated with the occurrence of microcracks crosscutting the recrystallized quartz aggregates that define the S fabric. In more advanced stages of shear band evolution, newly formed dominant K-feldspar, together with plagioclase, muscovite and chlorite occur in the microcracks, and the shear bands start to widen. K-feldspar replaces quartz by progressively bulging into the grain boundaries of recrystallized quartz grains, leading to disintegration of quartz aggregates and formation of fine-grained multiphase matrix mixture. The late stages of shear band development are marked by interconnection of fine-grained white mica into a band that crosscuts the original shear band matrix. In its extremity, the shear band widening may lead to the formation of ultramylonites. With the increasing proportion of shear band matrix from ~1% to ~12%, the angular relationship between S and C fabrics increases from ~30° to ~40°. The matrix phases within shear bands show differences in chemical composition related to distinct evolutionary stages of shear band formation. The chemical evolution is well documented in K-feldspar, where the albite component is highest in porphyroclasts within S fabric, lower in the newly formed grains within

Performance interface document for the S-band diplexer for space users of NASA networks

NASA Technical Reports Server (NTRS)

Line, L. G.

1985-01-01

This report discusses the test results and interfacing information of the S-band diplexer development program supported by RTOP 310 funding. The program was implemented to reduce the S-band transponder noise figure by minimizing the receive channel insertion loss and to also provide Space Transportation System (STS) compatibility by providing 70-db rejection up to 16 GHz in the receive channel. This compatibility includes rejection of signals from the Shuttle S-band Data Link, the K-band Data Link, and the K-band Rendezvous Radar. The first of many projects to benefit from this accomplishment was the Earth Radiation Budget Satellite (ERBS).

An adaptive enhancement algorithm for infrared video based on modified k-means clustering

NASA Astrophysics Data System (ADS)

Zhang, Linze; Wang, Jingqi; Wu, Wen

2016-09-01

In this paper, we have proposed a video enhancement algorithm to improve the output video of the infrared camera. Sometimes the video obtained by infrared camera is very dark since there is no clear target. In this case, infrared video should be divided into frame images by frame extraction, in order to carry out the image enhancement. For the first frame image, which can be divided into k sub images by using K-means clustering according to the gray interval it occupies before k sub images' histogram equalization according to the amount of information per sub image, we used a method to solve a problem that final cluster centers close to each other in some cases; and for the other frame images, their initial cluster centers can be determined by the final clustering centers of the previous ones, and the histogram equalization of each sub image will be carried out after image segmentation based on K-means clustering. The histogram equalization can make the gray value of the image to the whole gray level, and the gray level of each sub image is determined by the ratio of pixels to a frame image. Experimental results show that this algorithm can improve the contrast of infrared video where night target is not obvious which lead to a dim scene, and reduce the negative effect given by the overexposed pixels adaptively in a certain range.

An adaptive metamaterial beam with hybrid shunting circuits for extremely broadband control of flexural wave (Conference Presentation)

NASA Astrophysics Data System (ADS)

Chen, Yangyang; Huang, Guoliang

2017-04-01

A great deal of research has been devoted to controlling the dynamic behaviors of phononic crystals and metamaterials by directly tuning the frequency regions and/or widths of their inherent band gaps. Here, we present a novel approach to achieve extremely broadband flexural wave/vibration attenuation based on tunable local resonators made of piezoelectric stacks shunted by hybrid negative capacitance and negative inductance circuits with proof masses attached on a host beam. First, wave dispersion relations of the adaptive metamaterial beam are calculated analytically by using the transfer matrix method. The unique modulus tuning properties induced by the hybrid shunting circuits are then characterized conceptually, from which the frequency dependent modulus tuning curves of the piezoelectric stack located within wave attenuation frequency regions are quantitatively identified. As an example, a flexural wave high-pass band filter with a wave attenuation region from 0 to 23.0 kHz is demonstrated analytically and numerically by using the hybrid shunting circuit, in which the two electric components are connected in series. By changing the connection pattern to be parallel, another super wide wave attenuation region from 13.5 to 73.0 kHz is demonstrated to function as a low-pass filter at a subwavelength scale. The proposed adaptive metamaterial possesses a super wide band gap created both naturally and artificially. Therefore, it can be used for the transient wave mitigation at extremely broadband frequencies such as blast or impact loadings. We envision that the proposed design and approach can open many possibilities in broadband vibration and wave control.

Birefringence and band structure of CdP2 crystals

NASA Astrophysics Data System (ADS)

Beril, S. I.; Stamov, I. G.; Syrbu, N. N.; Zalamai, V. V.

2013-08-01

The spatial dispersion in CdP2 crystals was investigated. The dispersion is positive (nk||с>nk||у) at λ>λ0 and negative (nk||сbands. Minimal direct energy intervals correspond to transitions Г1→Г1 for Е||с and Г2→Г1 for Е⊥с. The temperature coefficient of energy gap sifting in the case of temperature changing between 2 and 4.2 K equals to 10.6 meV/K and 3.2 mev/K for Г1→Г1 and Г2→Г1 band gap correspondingly. Reflectivity spectra were measured for energy interval 1.5-10 eV and optical functions (n, k, ε1, ε2,d2ε1/dE2 and d2ε2/dE2) were calculated by using Kramers-Kronig analyses. All features were interpreted as optical transitions on the basis of both theoretical calculations of band structure.

Voigt deconvolution method and its applications to pure oxygen absorption spectrum at 1270 nm band.

PubMed

Al-Jalali, Muhammad A; Aljghami, Issam F; Mahzia, Yahia M

2016-03-15

Experimental spectral lines of pure oxygen at 1270 nm band were analyzed by Voigt deconvolution method. The method gave a total Voigt profile, which arises from two overlapping bands. Deconvolution of total Voigt profile leads to two Voigt profiles, the first as a result of O2 dimol at 1264 nm band envelope, and the second from O2 monomer at 1268 nm band envelope. In addition, Voigt profile itself is the convolution of Lorentzian and Gaussian distributions. Competition between thermal and collisional effects was clearly observed through competition between Gaussian and Lorentzian width for each band envelope. Voigt full width at half-maximum height (Voigt FWHM) for each line, and the width ratio between Lorentzian and Gaussian width (ΓLΓG(-1)) have been investigated. The following applied pressures were at 1, 2, 3, 4, 5, and 8 bar, while the temperatures were at 298 K, 323 K, 348 K, and 373 K range. Copyright © 2015 Elsevier B.V. All rights reserved.

An Active K-Band Receive Slot Array for Mobile Satellite Communications

NASA Technical Reports Server (NTRS)

Tulintseff, A. N.; Lee, K. A.; Sukamto, L. M.; Chew, W.

1994-01-01

An active receive slot array has been developed for operation in the downlink frequency band, 19.914-20.064 GHz, of NASA's Advanced Communication Technology Satellite (ACTS) for the ACTS Mobile Terminal (AMT) project.

Demonstration of 1024x1024 pixel dual-band QWIP focal plane array

NASA Astrophysics Data System (ADS)

Gunapala, S. D.; Bandara, S. V.; Liu, J. K.; Mumolo, J. M.; Ting, D. Z.; Hill, C. J.; Nguyen, J.; Rafol, S. B.

2010-04-01

QWIPs are well known for their stability, high pixel-pixel uniformity and high pixel operability which are quintessential parameters for large area imaging arrays. In this paper we report the first demonstration of the megapixel-simultaneously-readable and pixel-co-registered dual-band QWIP focal plane array (FPA). The dual-band QWIP device was developed by stacking two multi-quantum-well stacks tuned to absorb two different infrared wavelengths. The full width at half maximum (FWHM) of the mid-wave infrared (MWIR) band extends from 4.4 - 5.1 μm and FWHM of the long-wave infrared (LWIR) band extends from 7.8 - 8.8 μm. Dual-band QWIP detector arrays were hybridized with direct injection 30 μm pixel pitch megapixel dual-band simultaneously readable CMOS read out integrated circuits using the indium bump hybridization technique. The initial dual-band megapixel QWIP FPAs were cooled to 68K operating temperature. The preliminary data taken from the first megapixel QWIP FPA has shown system NE▵T of 27 and 40 mK for MWIR and LWIR bands respectively.

Identification of yrast high-K intrinsic states in {sup 188}Os

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

Modamio, V.; Jungclaus, A.; Instituto de Estructura de la Materia, CSIC, Serrano 113bis, E-28006 Madrid

2009-02-15

The high-spin structure of the Z=76 nucleus {sup 188}Os has been studied using the incomplete fusion reaction {sup 7}Li+{sup 186}W. A K{sup {pi}}=10{sup +} band has been established up to spin (24{sup +}) and its crossing with the ground-state band has been studied. In addition, intrinsic high-K states have been identified and on top of two of them, K{sup {pi}}=7{sup -} and K{sup {pi}}=10{sup -}, regular bands have been observed. The K{sup {pi}}=16{sup +} and K{sup {pi}}=18{sup +} states are yrast whereas the K{sup {pi}}=14{sup +} level lies only 33 keV above the yrast line and decays with a lowmore » reduced hindrance of f{sub {nu}}<1.3 to the ground-state band ({delta}K=14). The results are discussed by means of a systematic comparison with the even-even neighboring nucleus {sup 186}Os. Configuration-constrained multiquasiparticle potential-energy-surface calculations have been performed to identify the configurations of multiquasiparticle states.« less

The K{sub a}-band 10-kW continuous wave gyrotron with wide-band fast frequency sweep

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

Glyavin, M.; Luchinin, A.; Morozkin, M.

2012-07-15

The dual-frequency gyrotron with fast 2% frequency sweep at about 28 GHz is designed to power an electron cyclotron resonance ion source (ECRIS). Operation with an output power of up to 10 kW in CW mode and efficiency of 20% was demonstrated at both frequencies. Frequency manipulation has a characteristic time of about 1 ms and is based on magnetic field variation with an additional low-power coil. Fast frequency sweep will supposedly increase the ion current and the average ion charge of ECRIS. The possibility of 100% power modulation is demonstrated using the same control method.

On the Determination of C0 (or A0), D0K, H0K, and Some Dark States for Symmetric-top Molecules from Infrared Spectra without the Need for Localized Perturbations

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

Maki, Arthur; Masiello, Tony; Blake, Thomas A

2009-05-01

For symmetric top molecules, the normal Δk = 0, Δl = 0 and Δk = ±1, Δl = ±1 selection rules for parallel and perpendicular bands, respectively, do not allow the determination of the K-dependent rotational constants, C 0 (or A 0), D 0 K, and H 0 K. However, we show here that several different combinations of allowed and apparently unperturbed rovibrational infrared transitions can give access to those constants. A necessary ingredient for the application of this technique is a band with selection rules Δk = ±1 (or Δk = 0), Δl = ∓2, such as an overtonemore » or difference band, and appropriate other bands. Bands with selection rules Δk = ±2, Δl = ∓1 are also useful but are seldom found. As a general rule, more than one vibrational transition is needed. Examples are given for boron trifluoride (BF 3), sulfur trioxide (SO 3), and cyclopropane (C 3H 6) for which there are microwave measurements that provide a check on the derived constants. The technique is also extended to a D 2d molecule, allene, even though we have no measurements to use as an example. Examples are also given for the determination of dark states from difference bands, and/or hot bands, and also whole forbidden bands that arise from mixing with distant energy levels.« less

Tunable metamaterial dual-band terahertz absorber

NASA Astrophysics Data System (ADS)

Luo, C. Y.; Li, Z. Z.; Guo, Z. H.; Yue, J.; Luo, Q.; Yao, G.; Ji, J.; Rao, Y. K.; Li, R. K.; Li, D.; Wang, H. X.; Yao, J. Q.; Ling, F. R.

2015-11-01

We report a design of a temperature controlled tunable dual band terahertz absorber. The compact single unit cell consists of two nested closed square ring resonators and a layer metallic separated by a substrate strontium titanate (STO) dielectric layer. It is found that the absorber has two distinctive absorption peaks at frequencies 0.096 THz and 0.137 THz, whose peaks are attained 97% and 75%. Cooling the absorber from 400 K to 250 K causes about 25% and 27% shift compared to the resonance frequency of room temperature, when we cooling the temperature to 150 K, we could attained both the two tunabilities exceeding 53%. The frequency tunability is owing to the variation of the dielectric constant of the low-temperature co-fired ceramic (LTCC) substrate. The mechanism of the dual band absorber is attributed to the overlapping of dual resonance frequencies, and could be demonstrated by the distributions of the electric field. The method opens up avenues for designing tunable terahertz devices in detection, imaging, and stealth technology.

Design and development of a 6 MW peak, 24 kW average power S-band klystron

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

Joshi, L.M.; Meena, Rakesh; Nangru, Subhash

2011-07-01

A 6 MW peak, 24 kW average power S-band Klystron is under development at CEERI, Pilani under an MoU between BARC and CEERI. The design of the klystron has been completed. The electron gun has been designed using TRAK and MAGIC codes. RF cavities have been designed using HFSS and CST Microwave Studio while the complete beam wave interaction simulation has been done using MAGIC code. The thermal design of collector and RF window has been done using ANSYS code. A Gun Collector Test Module (GCTM) was developed before making actual klystron to validate gun perveance and thermal design ofmore » collector. A high voltage solid state pulsed modulator has been installed for performance valuation of the tube. The paper will cover the design aspects of the tube and experimental test results of GCTM and klystron. (author)« less

Band-to-Band Tunneling-Dominated Thermo-Enhanced Field Electron Emission from p-Si/ZnO Nanoemitters.

PubMed

Huang, Zhizhen; Huang, Yifeng; Xu, Ningsheng; Chen, Jun; She, Juncong; Deng, Shaozhi

2018-06-13

Thermo-enhancement is an effective way to achieve high performance field electron emitters, and enables the individually tuning on the emission current by temperature and the electron energy by voltage. The field emission current from metal or n-doped semiconductor emitter at a relatively lower temperature (i.e., < 1000 K) is less temperature sensitive due to the weak dependence of free electron density on temperature, while that from p-doped semiconductor emitter is restricted by its limited free electron density. Here, we developed full array of uniform individual p-Si/ZnO nanoemitters and demonstrated the strong thermo-enhanced field emission. The mechanism of forming uniform nanoemitters with well Si/ZnO mechanical joint in the nanotemplates was elucidated. No current saturation was observed in the thermo-enhanced field emission measurements. The emission current density showed about ten-time enhancement (from 1.31 to 12.11 mA/cm 2 at 60.6 MV/m) by increasing the temperature from 323 to 623 K. The distinctive performance did not agree with the interband excitation mechanism but well-fit to the band-to-band tunneling model. The strong thermo-enhancement was proposed to be benefit from the increase of band-to-band tunneling probability at the surface portion of the p-Si/ZnO nanojunction. This work provides promising cathode for portable X-ray tubes/panel, ionization vacuum gauges and low energy electron beam lithography, in where electron-dose control at a fixed energy is needed.

Novel solution of power law for γ-bands

NASA Astrophysics Data System (ADS)

Gupta, J. B.

The power law expression E = aIb offers a single-term formula with just two parameters for expressing the level energies in the spectra of even-Z even-N nuclei. Its application to ground band spectra for a wide range of nuclei has been demonstrated in our earlier works. Here, we extend its application to the rotational bands built on an excited state of K = 2 γ-vibration band and Kπ = 0 2+ beta band. A novel assumption of a virtual level with spin zero for γ-bands is made and its validity and use is illustrated. Here, the constancy of the parameters “b” and “a” with spin, offers a more realistic view of the dependence of the nuclear core deformation on spin, in the excited bands. Also, it enables a spinwise view, not available in the other energy fit expressions.

Fireball Observations in Visible and Sodium Bands

NASA Astrophysics Data System (ADS)

Fletcher, Sandra

On November 17th at 1:32am MST, a large Leonid fireball was simultaneously imaged by two experiments, a visible band CCD camera and a 590nm filtered band equi-angle fisheye and telecentric lens assembly. The visible band camera, ROTSE (Robotic Optical Transient Search Experiment) is a two by two f/1.9 telephoto lens array with 2k x2k Thompson CCD and is located at 35.87 N, 106.25 W at an altitude of 2115m. One-minute exposures along the radiant were taken of the event for 30 minutes after the initial explosion. The sodium band experiment was located at 35.29 N,106.46 W at an altitude of 1860m. It took ninety second exposures and captured several events throughout the night. Triangulation from two New Mexico sites resulted in an altitude of 83km over Wagon Mound, NM. Two observers present at the ROTSE site saw a green flash and a persistent glow up to seven minutes after the explosion. Cataloging of all sodium trails for comparison with lidar and infrasonic measurements is in progress. The raw data from both experiments and the atmospheric chemistry interpretation of them will be presented.

Development of softcopy environment for primary color banding visibility assessment

NASA Astrophysics Data System (ADS)

Min, Byungseok; Pizlo, Zygmunt; Allebach, Jan P.

2008-01-01

, we perform haploscopic matching experiments that allow each eye to independently adapt to different viewing conditions; and we find an appearance mapping function in the adapted XYZ space. Finally, to validate the accuracy of the softcopy environment, we conduct a banding matching experiment at three different banding levels by the memory matching method, and confirm that our softcopy environment produces the same banding perception as the hardcopy. In addition, we perform two more separate psychophysical experiments to measure the differential threshold of the intrinsic banding in both the hardcopy and softcopy environments, and confirm that the two thresholds are statistically identical. The results show that with our target printer, human subjects can see a just noticeable difference with a 9% reduction in the banding magnitude for the cyan colorant.

An adaptive narrow band frequency modulation voice communication system

NASA Technical Reports Server (NTRS)

Wishna, S.

1972-01-01

A narrow band frequency modulation communication system is described which provides for the reception of good quality voice at low carrier-to-noise ratios. The high level of performance is obtained by designing a limiter and phase lock loop combination as a demodulator, so that the bandwidth of the phase lock loop decreases as the carrier level decreases. The system was built for the position location and aircraft communication equipment experiment of the ATS 6 program.

Multi-band analysis of temperature-dependent transport coefficients (conductivity, Hall, Seebeck, and Nernst) of Ni-doped CoSb3

NASA Astrophysics Data System (ADS)

Kajikawa, Y.

2016-02-01

The experimental data on the temperature dependence of the four transport coefficients, i.e., the electrical conductivity (σ), Hall coefficient (RH), Seebeck coefficient (S), and Nernst coefficient (Q), of n-type Co0.999Ni0.001Sb3 reported by Sun et al. [Nat. Commun. 6, 7475 (2015)] have been analyzed in a multi-band model, especially focusing on the low temperature data. The multi-band model includes not only the lowest valley of the conduction band at the Γ point but also satellite valleys at the second minima together with an impurity band. The lowest valley at the Γ point is assumed to split into the c1 band and the spin-orbit split-off (so) band. For the analysis, the general expression of the Nernst coefficient in the multi-band model is derived. At such low temperatures that the other bands than the c1 and the impurity band can be neglected, this expression is shown to be approximated as the sum of three terms: the intrinsic terms due to the Nernst coefficients in the two bands themselves and a cross term proportional to the difference of Seebeck coefficients between the two bands. As a result of the analysis, it is proved that the anomalous positive peak of S(T) observed around T = 20 K as well as the sharp rise of the Hall mobility observed from 15 K to 40 K are due to the transition from hopping conduction in the impurity band to conduction in the c1 band. On the other hand, the pronounced peak of Q(T) observed slightly below 40 K is proved to be due to the cross term between the impurity band and the c1 band. In addition, a shoulder of Q(T) appeared around T = 80 K lends clear evidence of the existence of the so band, while the increase in both of σ(T) and | S ( T ) | above 150 K suggests the existence of the satellite valleys.

The adaptive buffered force QM/MM method in the CP2K and AMBER software packages

PubMed Central

Mones, Letif; Jones, Andrew; Götz, Andreas W; Laino, Teodoro; Walker, Ross C; Leimkuhler, Ben; Csányi, Gábor; Bernstein, Noam

2015-01-01

The implementation and validation of the adaptive buffered force (AdBF) quantum-mechanics/molecular-mechanics (QM/MM) method in two popular packages, CP2K and AMBER are presented. The implementations build on the existing QM/MM functionality in each code, extending it to allow for redefinition of the QM and MM regions during the simulation and reducing QM-MM interface errors by discarding forces near the boundary according to the buffered force-mixing approach. New adaptive thermostats, needed by force-mixing methods, are also implemented. Different variants of the method are benchmarked by simulating the structure of bulk water, water autoprotolysis in the presence of zinc and dimethyl-phosphate hydrolysis using various semiempirical Hamiltonians and density functional theory as the QM model. It is shown that with suitable parameters, based on force convergence tests, the AdBF QM/MM scheme can provide an accurate approximation of the structure in the dynamical QM region matching the corresponding fully QM simulations, as well as reproducing the correct energetics in all cases. Adaptive unbuffered force-mixing and adaptive conventional QM/MM methods also provide reasonable results for some systems, but are more likely to suffer from instabilities and inaccuracies. © 2015 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc. PMID:25649827

The adaptive buffered force QM/MM method in the CP2K and AMBER software packages

DOE PAGES

Mones, Letif; Jones, Andrew; Götz, Andreas W.; ...

2015-02-03

We present the implementation and validation of the adaptive buffered force (AdBF) quantum-mechanics/molecular-mechanics (QM/MM) method in two popular packages, CP2K and AMBER. The implementations build on the existing QM/MM functionality in each code, extending it to allow for redefinition of the QM and MM regions during the simulation and reducing QM-MM interface errors by discarding forces near the boundary according to the buffered force-mixing approach. New adaptive thermostats, needed by force-mixing methods, are also implemented. Different variants of the method are benchmarked by simulating the structure of bulk water, water autoprotolysis in the presence of zinc and dimethyl-phosphate hydrolysis usingmore » various semiempirical Hamiltonians and density functional theory as the QM model. It is shown that with suitable parameters, based on force convergence tests, the AdBF QM/MM scheme can provide an accurate approximation of the structure in the dynamical QM region matching the corresponding fully QM simulations, as well as reproducing the correct energetics in all cases. Adaptive unbuffered force-mixing and adaptive conventional QM/MM methods also provide reasonable results for some systems, but are more likely to suffer from instabilities and inaccuracies.« less

The adaptive buffered force QM/MM method in the CP2K and AMBER software packages

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

Mones, Letif; Jones, Andrew; Götz, Andreas W.

We present the implementation and validation of the adaptive buffered force (AdBF) quantum-mechanics/molecular-mechanics (QM/MM) method in two popular packages, CP2K and AMBER. The implementations build on the existing QM/MM functionality in each code, extending it to allow for redefinition of the QM and MM regions during the simulation and reducing QM-MM interface errors by discarding forces near the boundary according to the buffered force-mixing approach. New adaptive thermostats, needed by force-mixing methods, are also implemented. Different variants of the method are benchmarked by simulating the structure of bulk water, water autoprotolysis in the presence of zinc and dimethyl-phosphate hydrolysis usingmore » various semiempirical Hamiltonians and density functional theory as the QM model. It is shown that with suitable parameters, based on force convergence tests, the AdBF QM/MM scheme can provide an accurate approximation of the structure in the dynamical QM region matching the corresponding fully QM simulations, as well as reproducing the correct energetics in all cases. Adaptive unbuffered force-mixing and adaptive conventional QM/MM methods also provide reasonable results for some systems, but are more likely to suffer from instabilities and inaccuracies.« less

Excitonic and band-band transitions of Cu2ZnSiS4 determined from reflectivity spectra

NASA Astrophysics Data System (ADS)

Guc, M.; Levcenko, S.; Dermenji, L.; Gurieva, G.; Schorr, S.; Syrbu, N. N.; Arushanov, E.

2014-07-01

Exciton spectra of Cu2ZnSiS4 single crystals are investigated by reflection spectroscopy at 10 and 300 K for light polarized perpendicular (E⊥c) and parallel (E∥c) to the optical axis. The parameters of the excitons and dielectric constant are determined. The free carriers effective masses have been estimated. The room temperature reflectivity spectra at photon energies higher than the fundamental band gap in the polarization Е⊥с and E∥с were measured and related to the electronic band structure of Cu2ZnSiS4.

Design and implementation of a hybrid sub-band acoustic echo canceller (AEC)

NASA Astrophysics Data System (ADS)

Bai, Mingsian R.; Yang, Cheng-Ken; Hur, Ker-Nan

2009-04-01

An efficient method is presented for implementing an acoustic echo canceller (AEC) that makes use of hybrid sub-band approach. The hybrid system is comprised of a fixed processor and an adaptive filter in each sub-band. The AEC aims at reducing the echo resulting from the acoustic feedback in loudspeaker-enclosure-microphone (LEM) systems such as teleconferencing and hands-free systems. In order to cancel the acoustical echo efficiently, various processing architectures including fixed filters, hybrid processors, and sub-band structure are investigated. A double-talk detector is incorporated into the proposed AEC to prevent the adaptive filter from diverging in double-talk situations. A de-correlation filter is also used alongside sub-band processing in order to enhance the performance and efficiency of AEC. All algorithms are implemented and verified on the platform of a fixed-point digital signal processor (DSP). The AECs are evaluated in terms of cancellation performance and computation complexity. In addition, listening tests are conducted to assess the subjective performance of the AECs. From the results, the proposed hybrid sub-band AEC was found to be the most effective among all methods in terms of echo reduction and timbral quality.

A New Transition in the Spectrum of YCl: Rotational Analysis of the K1Π- X1Σ +UV Band System

NASA Astrophysics Data System (ADS)

Xin, Ju; Klynning, Lennart

1996-02-01

The absorption spectrum of the yttrium monochloride molecule (YCl) produced in a King-type furnace has been recorded at high resolution using a 5-m Fastie spectrograph. A new band system in the UV region (centered at 3291 Å) has been found and rotationally analyzed. The transition has been assigned toK1Π-X1Σ+, in accordance with the labeling of the YCl electronic states by Langhoffet al.(J. Chem. Phys.89,396-407, 1988) in their theoretical work. Molecular constants for the new state are presented.

A novel analysis method for near infrared spectroscopy based on Hilbert-Huang transform

NASA Astrophysics Data System (ADS)

Zhou, Zhenyu; Yang, Hongyu; Liu, Yun; Ruan, Zongcai; Luo, Qingming; Gong, Hui; Lu, Zuhong

2007-05-01

Near Infrared Imager (NIRI) has been widely used to access the brain functional activity non-invasively. We use a portable, multi-channel and continuous-wave NIR topography instrument to measure the concentration changes of each hemoglobin species and map cerebral cortex functional activation. By extracting some essential features from the BOLD signals, optical tomography is able to be a new way of neuropsychological studies. Fourier spectral analysis provides a common framework for examining the distribution of global energy in the frequency domain. However, this method assumes that the signal should be stationary, which limits its application in non-stationary system. The hemoglobin species concentration changes are of such kind. In this work we develop a new signal processing method using Hilbert-Huang transform to perform spectral analysis of the functional NIRI signals. Compared with wavelet based multi-resolution analysis (MRA), we demonstrated the extraction of task related signal for observation of activation in the prefrontal cortex (PFC) in vision stimulation experiment. This method provides a new analysis tool for functional NIRI signals. Our experimental results show that the proposed approach provides the unique method for reconstructing target signal without losing original information and enables us to understand the episode of functional NIRI more precisely.

Nitrogen reduction pathways in estuarine sediments: Influences of organic carbon and sulfide

NASA Astrophysics Data System (ADS)

Plummer, Patrick; Tobias, Craig; Cady, David

2015-10-01

Potential rates of sediment denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were mapped across the entire Niantic River Estuary, CT, USA, at 100-200 m scale resolution consisting of 60 stations. On the estuary scale, denitrification accounted for ~ 90% of the nitrogen reduction, followed by DNRA and anammox. However, the relative importance of these reactions to each other was not evenly distributed through the estuary. A Nitrogen Retention Index (NIRI) was calculated from the rate data (DNRA/(denitrification + anammox)) as a metric to assess the relative amounts of reactive nitrogen being recycled versus retained in the sediments following reduction. The distribution of rates and accompanying sediment geochemical analytes suggested variable controls on specific reactions, and on the NIRI, depending on position in the estuary and that these controls were linked to organic carbon abundance, organic carbon source, and pore water sulfide concentration. The relationship between NIRI and organic carbon abundance was dependent on organic carbon source. Sulfide proved the single best predictor of NIRI, accounting for 44% of its observed variance throughout the whole estuary. We suggest that as a single metric, sulfide may have utility as a proxy for gauging the distribution of denitrification, anammox, and DNRA.

Quasiparticle band structure of rocksalt-CdO determined using maximally localized Wannier functions.

PubMed

Dixit, H; Lamoen, D; Partoens, B

2013-01-23

CdO in the rocksalt structure is an indirect band gap semiconductor. Thus, in order to determine its band gap one needs to calculate the complete band structure. However, in practice, the exact evaluation of the quasiparticle band structure for the large number of k-points which constitute the different symmetry lines in the Brillouin zone can be an extremely demanding task compared to the standard density functional theory (DFT) calculation. In this paper we report the full quasiparticle band structure of CdO using a plane-wave pseudopotential approach. In order to reduce the computational effort and time, we make use of maximally localized Wannier functions (MLWFs). The MLWFs offer a highly accurate method for interpolation of the DFT or GW band structure from a coarse k-point mesh in the irreducible Brillouin zone, resulting in a much reduced computational effort. The present paper discusses the technical details of the scheme along with the results obtained for the quasiparticle band gap and the electron effective mass.

Low-Profile Multiband and Flush-Mountable Wideband Antennas for HF/VHF and K/Ka Band Applications

NASA Astrophysics Data System (ADS)

Garrido Lopez, David

emissions are planned. Following the same trend of antenna system size reduction with extension of capabilities in a congested spectral environment, the millimeter wave spectrum is explored next. Specifically, antenna systems for wideband amplitude only (AO) direction finding (DF) are thoroughly considered. Theory and design considerations are developed to fill gaps in open literature. Typical sources of errors are theoretically analyzed, and a discussion on limitations and advantages of different AO DF architectures is given. Practical millimeter wave realizations of AO DF antenna front-ends in the K/Ka/Q bands (18-45 GHz) are developed using two different architectures: a passive phased-array and a squinted antenna system. For the former, a tightly coupled two-element tapered slot antenna (TSA) array with a stacked arrangement is developed. A novel enclosure of the array inside an absorbing cavity is proposed and improved system performance with flush mounted configuration is demonstrated. The squinted antenna system avoids the use of a beamformer, therefore reducing insertion loss and amplitude/phase imbalances to reduce DF errors. For design robustness, the same TSA element used in the phased-array configuration is used. A novel tapered cavity is also developed to stabilize H-plane radiation patterns and suppress sidelobes. It is seen that the squinted antenna AO DF front-end has better performance than the phased-array antenna system at the expense of larger size.

Highly Depleted Ethane and Mildly Depleted Methanol in Comet 21P/Giacobini-Zinner: Application of a New Empirical nu(sub 2) Band Model for CH30H Near 50 K

NASA Technical Reports Server (NTRS)

DiSanti, M. A.; Bonev, B. P.; Villanueva, G. L.; Mumma, M. J.

2012-01-01

Infrared spectra of Comet 2lP/Giacobini-Zinner (hereafter 2IP/GZ) were obtained using NIRSPEC at Keck II on UT 2005 June 03, approximately one month before perihelion, that simultaneously measured H2O, C2H6, and CH3OH. For H2O, the production rate of 3.8 x 10(exp 28) molecules / S was consistent with that measured during other apparitions of 21P/GZ retrieved from optical, infrared, and mm-wavelength observations. The water analysis also provided values for rotational temperature (T(sub rot) = 55(epx +3) /-.2 K) and the abundance ratio of ortho- and para-water (3.00 +/-0.15, implying a spin temperature exceeding 50 K). Six Q-branches in the V7 band of C2H6 provided a production rate (5.27 +/- 0.90 x 10(exp 25)/S) that corresponded to an abundance ratio of 0.139 +/- 0.024 % relative to H2O, confirming the previously reported strong depletion of C2H6 from IR observations during the 1998 apparition, and in qualitative agreement with the depletion in C2 known from optical studies. For CH30H, we applied our recently published ab initia model for the v3 band to obtain a rotational temperature (48(exp + 10) / -7 K) consistent with that obtained for H2O. In addition we applied a newly developed empirical model for the CH30H v2 band, and obtained a production rate consistent with that obtained from the v3 band. Combining results from both v2 and v3 bands provided a production rate (47.5 +/- 4.4 x 10(exp 25) / S) that corresponded to an abundance ratio of 1.25 +/- 0.12 % relative to H2O in 21P/GZ. Our study provides the first measure of primary volatile production rates for any Jupiter family comet over multiple apparitions using high resolution IR spectroscopy.

Multi-band Electronic Structure of Ferromagnetic CeRuPO

NASA Astrophysics Data System (ADS)

Takahashi, Masaya; Ootsuki, Daiki; Horio, Masafumi; Arita, Masashi; Namatame, Hirofumi; Taniguchi, Masaki; Saini, Naurang L.; Sugawara, Hitoshi; Mizokawa, Takashi

2018-04-01

We have studied the multi-band electronic structure of ferromagnetic CeRuPO (TC = 15 K) by means of angle-resolved photoemission spectroscopy (ARPES). The ARPES results show that three hole bands exist around the zone center and two of them cross the Fermi level (EF). Around the zone corner, two electron bands are observed and cross EF. These hole and electron bands, which can be assigned to the Ru 4d bands, are basically consistent with the band-structure calculation including their orbital characters. However, one of the electron bands with Ru 4d 3z2 - r2 character is strongly renormalized indicating correlation effect due to hybridization with the Ce 4f orbitals. The Ru 4d 3z2 - r2 band changes across TC suggesting that the out-of-plane 3z2 - r2 orbital channel plays essential roles in the ferromagnetism.

Acid-adapted strains of Escherichia coli K-12 obtained by experimental evolution.

PubMed

Harden, Mark M; He, Amanda; Creamer, Kaitlin; Clark, Michelle W; Hamdallah, Issam; Martinez, Keith A; Kresslein, Robert L; Bush, Sean P; Slonczewski, Joan L

2015-03-01

Enteric bacteria encounter a wide range of pHs throughout the human intestinal tract. We conducted experimental evolution of Escherichia coli K-12 to isolate clones with increased fitness during growth under acidic conditions (pH 4.5 to 4.8). Twenty-four independent populations of E. coli K-12 W3110 were evolved in LBK medium (10 g/liter tryptone, 5 g/liter yeast extract, 7.45 g/liter KCl) buffered with homopiperazine-N,N'-bis-2-(ethanosulfonic acid) and malate at pH 4.8. At generation 730, the pH was decreased to 4.6 with HCl. By 2,000 generations, all populations had achieved higher endpoint growth than the ancestor at pH 4.6 but not at pH 7.0. All evolving populations showed a progressive loss of activity of lysine decarboxylase (CadA), a major acid stress enzyme. This finding suggests a surprising association between acid adaptation and moderation of an acid stress response. At generation 2,000, eight clones were isolated from four populations, and their genomes were sequenced. Each clone showed between three and eight missense mutations, including one in a subunit of the RNA polymerase holoenzyme (rpoB, rpoC, or rpoD). Missense mutations were found in adiY, the activator of the acid-inducible arginine decarboxylase (adiA), and in gcvP (glycine decarboxylase), a possible acid stress component. For tests of fitness relative to that of the ancestor, lacZ::kan was transduced into each strain. All acid-evolved clones showed a high fitness advantage at pH 4.6. With the cytoplasmic pH depressed by benzoate (at external pH 6.5), acid-evolved clones showed decreased fitness; thus, there was no adaptation to cytoplasmic pH depression. At pH 9.0, acid-evolved clones showed no fitness advantage. Thus, our acid-evolved clones showed a fitness increase specific to low external pH. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Acid-Adapted Strains of Escherichia coli K-12 Obtained by Experimental Evolution

PubMed Central

Harden, Mark M.; He, Amanda; Creamer, Kaitlin; Clark, Michelle W.; Hamdallah, Issam; Martinez, Keith A.; Kresslein, Robert L.; Bush, Sean P.

2015-01-01

Enteric bacteria encounter a wide range of pHs throughout the human intestinal tract. We conducted experimental evolution of Escherichia coli K-12 to isolate clones with increased fitness during growth under acidic conditions (pH 4.5 to 4.8). Twenty-four independent populations of E. coli K-12 W3110 were evolved in LBK medium (10 g/liter tryptone, 5 g/liter yeast extract, 7.45 g/liter KCl) buffered with homopiperazine-N,N′-bis-2-(ethanosulfonic acid) and malate at pH 4.8. At generation 730, the pH was decreased to 4.6 with HCl. By 2,000 generations, all populations had achieved higher endpoint growth than the ancestor at pH 4.6 but not at pH 7.0. All evolving populations showed a progressive loss of activity of lysine decarboxylase (CadA), a major acid stress enzyme. This finding suggests a surprising association between acid adaptation and moderation of an acid stress response. At generation 2,000, eight clones were isolated from four populations, and their genomes were sequenced. Each clone showed between three and eight missense mutations, including one in a subunit of the RNA polymerase holoenzyme (rpoB, rpoC, or rpoD). Missense mutations were found in adiY, the activator of the acid-inducible arginine decarboxylase (adiA), and in gcvP (glycine decarboxylase), a possible acid stress component. For tests of fitness relative to that of the ancestor, lacZ::kan was transduced into each strain. All acid-evolved clones showed a high fitness advantage at pH 4.6. With the cytoplasmic pH depressed by benzoate (at external pH 6.5), acid-evolved clones showed decreased fitness; thus, there was no adaptation to cytoplasmic pH depression. At pH 9.0, acid-evolved clones showed no fitness advantage. Thus, our acid-evolved clones showed a fitness increase specific to low external pH. PMID:25556191

X-band preamplifier filter

NASA Technical Reports Server (NTRS)

Manshadi, F.

1986-01-01

A low-loss bandstop filter designed and developed for the Deep Space Network's 34-meter high-efficiency antennas is described. The filter is used for protection of the X-band traveling wave masers from the 20-kW transmitter signal. A combination of empirical and theoretical techniques was employed as well as computer simulation to verify the design before fabrication.

Near-infrared spectroscopy of the Y0 WISEP J173835.52+273258.9 and the Y1 WISE J035000.32–565830.2: The importance of non-equilibrium chemistry

DOE PAGES

Leggett, Sandy K.; Tremblin, Patrick; Saumon, Didier; ...

2016-06-03

Here, we present new near-infrared spectra, obtained at Gemini Observatory, for two Y dwarfs: WISE J035000.32–565830.2 (W0350) and WISEP J173835.52+273258.9 (W1738). A FLAMINGOS-2 R = 540 spectrum was obtained for W0350, coveringmore » $$1.0\\lt \\lambda \\;\\mu {\\rm{m}}$$ $$\\lt \\;1.7$$, and a cross-dispersed Gemini near-infrared spectrograph R = 2800 spectrum was obtained for W1738, covering 0.993–1.087 μm, 1.191–1.305 μm, 1.589–1.631 μm, and 1.985–2.175 μm, in four orders. We also present revised YJH photometry for W1738, using new NIRI Y and J imaging, and a re-analysis of the previously published NIRI H-band images. We compare these data, together with previously published data for late-T and Y dwarfs, to cloud-free models of solar metallicity, calculated both in chemical equilibrium and with disequilibrium driven by vertical transport. We find that for the Y dwarfs, the non-equilibrium models reproduce the near-infrared data better than the equilibrium models. The remaining discrepancies suggest that fine-tuning the CH 4/CO and NH 3/N 2 balance is needed. Improved trigonometric parallaxes would improve the analysis. Despite the uncertainties and discrepancies, the models reproduce the observed near-infrared spectra well. We find that for the Y0, W1738, $${T}_{{\\rm{eff}}}=425\\pm 25\\;{\\rm{K}}$$, and log $$g=4.0\\pm 0.25$$, and for the Y1, W0350, $${T}_{{\\rm{eff}}}=350\\pm 25\\;{\\rm{K}}$$, and log $$g=4.0\\pm 0.25$$. W1738 may be metal-rich. Based on evolutionary models, these temperatures and gravities correspond to a mass range for both Y dwarfs of 3–9 Jupiter masses, with W0350 being a cooler, slightly older, version of W1738; the age of W0350 is 0.3–3 Gyr, and the age of W1738 is 0.15–1 Gyr.« less

The profile of the bending mode band in solid CO2

NASA Astrophysics Data System (ADS)

Baratta, G. A.; Palumbo, M. E.

2017-12-01

Context. Solid carbon dioxide (CO2) is one of the most abundant species detected in icy grain mantles in dense molecular clouds. Its identification is based on the comparison between astronomical and laboratory spectra. In the past 30 yr the profile of solid CO2 infrared absorption bands has been extensively studied experimentally, however, the debate on the structure (amorphous versus crystalline) of CO2 samples obtained in laboratory by the thin-film technique is still open. Aims: The aim of this work is to investigate if the presence of the double peak feature in the profile of the CO2 bending mode band is related to the crystalline or amorphous structure of the sample. Methods: We performed new laboratory experiments depositing CO2 under ultra high vacuum (UHV) conditions at 17 K. We investigated, using infrared transmission spectroscopy, the influence of various experimental parameters on the profile of the CO2 bands, namely deposition rate, sample thickness, annealing, and presence of H2O, CH3OH or CO co-deposited with CO2. Results: We found that, within experimental uncertainties, under UHV conditions the profile of the CO2 bands in pure solid samples does not depend on the deposition rate or the sample thickness in the ranges investigated. In all cases the bending mode band profile shows a double peak (at 660 and 655 cm-1). The spectra also show the Fermi resonance features that cannot be active in crystalline samples. On the other hand, when a small fraction of H2O or CH3OH is co-deposited with CO2 the double peak is not observed while it is observed when a CO2:CO mixture is considered. Furthermore, we measured the density of solid CO2 and the refractive index (at 543.5 nm) at 17 K and at 70 K: ρ(17 K)= 1.17 g cm-3, ρ(70K)= 1.49 g cm-3, n(17K)= 1.285, and n(70K)= 1.372. Conclusions: Our experimental results indicate that the presence of the double peak in the profile of the bending mode band is not an indication of a crystalline structure of the sample

Retrieval of Lower Thermospheric Temperatures from O2 A Band Emission: The MIGHTI Experiment on ICON

NASA Astrophysics Data System (ADS)

Stevens, Michael H.; Englert, Christoph R.; Harlander, John M.; England, Scott L.; Marr, Kenneth D.; Brown, Charles M.; Immel, Thomas J.

2018-02-01

The Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) is a satellite experiment scheduled to launch on NASA's Ionospheric Connection Explorer (ICON) in 2018. MIGHTI is designed to measure horizontal neutral winds and neutral temperatures in the terrestrial thermosphere. Temperatures will be inferred by imaging the molecular oxygen Atmospheric band (A band) on the limb in the lower thermosphere. MIGHTI will measure the spectral shape of the A band using discrete wavelength channels to infer the ambient temperature from the rotational envelope of the band. Here we present simulated temperature retrievals based on the as-built characteristics of the instrument and the expected emission rate profile of the A band for typical daytime and nighttime conditions. We find that for a spherically symmetric atmosphere, the measurement precision is 1 K between 90-105 km during the daytime whereas during the nighttime it increases from 1 K at 90 km to 3 K at 105 km. We also find that the accuracy is 2 K to 11 K for the same altitudes. The expected MIGHTI temperature precision is within the measurement requirements for the ICON mission.

Analysis of the 3’ untranslated regions of α-tubulin and S-crystallin mRNA and the identification of CPEB in dark- and light-adapted octopus retinas

PubMed Central

Kelly, Shannan; Yamamoto, Hideki

2008-01-01

Purpose We previously reported the differential expression and translation of mRNA and protein in dark- and light-adapted octopus retinas, which may result from cytoplasmic polyadenylation element (CPE)–dependent mRNA masking and unmasking. Here we investigate the presence of CPEs in α-tubulin and S-crystallin mRNA and report the identification of cytoplasmic polyadenylation element binding protein (CPEB) in light- and dark-adapted octopus retinas. Methods 3’-RACE and sequencing were used to isolate and analyze the 3’-UTRs of α-tubulin and S-crystallin mRNA. Total retinal protein isolated from light- and dark-adapted octopus retinas was subjected to western blot analysis followed by CPEB antibody detection, PEP-171 inhibition of CPEB, and dephosphorylation of CPEB. Results The following CPE-like sequence was detected in the 3’-UTR of isolated long S-crystallin mRNA variants: UUUAACA. No CPE or CPE-like sequences were detected in the 3’-UTRs of α-tubulin mRNA or of the short S-crystallin mRNA variants. Western blot analysis detected CPEB as two putative bands migrating between 60-80 kDa, while a third band migrated below 30 kDa in dark- and light-adapted retinas. Conclusions The detection of CPEB and the identification of the putative CPE-like sequences in the S-crystallin 3’-UTR suggest that CPEB may be involved in the activation of masked S-crystallin mRNA, but not in the regulation of α-tubulin mRNA, resulting in increased S-crystallin protein synthesis in dark-adapted octopus retinas. PMID:18682811

Increased gamma band power during movement planning coincides with motor memory retrieval.

PubMed

Thürer, Benjamin; Stockinger, Christian; Focke, Anne; Putze, Felix; Schultz, Tanja; Stein, Thorsten

2016-01-15

The retrieval of motor memory requires a previous memory encoding and subsequent consolidation of the specific motor memory. Previous work showed that motor memory seems to rely on different memory components (e.g., implicit, explicit). However, it is still unknown if explicit components contribute to the retrieval of motor memories formed by dynamic adaptation tasks and which neural correlates are linked to memory retrieval. We investigated the lower and higher gamma bands of subjects' electroencephalography during encoding and retrieval of a dynamic adaptation task. A total of 24 subjects were randomly assigned to a treatment and control group. Both groups adapted to a force field A on day 1 and were re-exposed to the same force field A on day 3 of the experiment. On day 2, treatment group learned an interfering force field B whereas control group had a day rest. Kinematic analyses showed that control group improved their initial motor performance from day 1 to day 3 but treatment group did not. This behavioral result coincided with an increased higher gamma band power in the electrodes over prefrontal areas on the initial trials of day 3 for control but not treatment group. Intriguingly, this effect vanished with the subsequent re-adaptation on day 3. We suggest that improved re-test performance in a dynamic motor adaptation task is contributed by explicit memory and that gamma bands in the electrodes over the prefrontal cortex are linked to these explicit components. Furthermore, we suggest that the contribution of explicit memory vanishes with the subsequent re-adaptation while task automaticity increases. Copyright © 2015 Elsevier Inc. All rights reserved.

Cold-adapted organic solvent tolerant alkalophilic family I.3 lipase from an Antarctic Pseudomonas.

PubMed

Ganasen, Menega; Yaacob, Norhayati; Rahman, Raja Noor Zaliha Raja Abd; Leow, Adam Thean Chor; Basri, Mahiran; Salleh, Abu Bakar; Ali, Mohd Shukuri Mohamad

2016-11-01

Lipolytic enzymes with cold adaptation are gaining increasing interest due to their biotechnological prospective. Previously, a cold adapted family I.3 lipase (AMS8 lipase) was isolated from an Antarctic Pseudomonas. AMS8 lipase was largely expressed in insoluble form. The refolded His-tagged recombinant AMS8 lipase was purified with 23.0% total recovery and purification factor of 9.7. The purified AMS8 lipase migrated as a single band with a molecular weight approximately 65kDa via electrophoresis. AMS8 lipase was highly active at 30°C at pH 10. The half-life of AMS8 lipase was reported at 4 and 2h under the incubation of 30 and 40°C, respectively. The lipase was stable over a broad range of pH. It showed enhancement effect in its relative activity under the presence of Li + , Na + , K + , Rb + and Cs + after 30min treatment. Heavy metal ions such as Cu 2+ , Fe 3+ and Zn 2+ inhibited AMS8 activity. This cold adapted alkalophilic AMS lipase was also active in various organic solvent of different polarity. These unique properties of this biological macromolecule will provide considerable potential for many biotechnological applications and organic synthesis at low temperature. Copyright © 2016 Elsevier B.V. All rights reserved.

[Study on the fine structure of K-feldspar of Qichun granite].

PubMed

Du, Deng-Wen; Hong, Han-Lie; Fan, Kan; Wang, Chao-Wen; Yin, Ke

2013-03-01

Fine structure of K-feldspar from the Qichun granite was investigated using X-ray diffraction (XRD), Fourier infrared absorption spectroscopy (FTIR), and inductively coupled plasma mass spectrometry methods to understand the evolution of the granitic magmatism and its correlation to molybdenite mineralization. The XRD results showed that K-feldspar of the potassic alteration veins has higher ordering index and triclinicity and is namely microcline with triclinic symmetry. K-feldspar of the early cretaceous granite has relatively lower ordering index and has widening [131] peak and is locally triclinic ordering. K-feldspar of the late cretaceous granite has lowest ordering index and sharp [131] peak and is honiogeneously monoclinic. The FTIR results showed that the IR spectra of the Qichun K-feldspar are similar to that of orthoclase reported by Farmer (1974). The 640 cm-1 absorption band increases while the 540 cm-' absorption band decreases with increase in K-feldspar ordering index, also, the 1,010 cm-1 absorption band separates into 1,010 and 1,046 cm-1 absorption bands, with a change in the band shape from widening to sharp outline. The ICP-MS results suggested that K-feldspar of the early cretaceous granite has relatively higher metal elements and rare earth elements, and the granite exhibits better mineralization background, K-feldspar of the potassic alteration veins has markedly lower Sr and Ba, indicating that the alteration fluid originated from the granitic magmatism, and hence, potassic alteration is a good indicator for molybdenite exploration.

Chiral geometry in multiple chiral doublet bands

NASA Astrophysics Data System (ADS)

Zhang, Hao; Chen, Qibo

2016-02-01

The chiral geometry of multiple chiral doublet bands with identical configuration is discussed for different triaxial deformation parameters γ in the particle rotor model with . The energy spectra, electromagnetic transition probabilities B(M1) and B(E2), angular momenta, and K-distributions are studied. It is demonstrated that the chirality still remains not only in the yrast and yrare bands, but also in the two higher excited bands when γ deviates from 30°. The chiral geometry relies significantly on γ, and the chiral geometry of the two higher excited partner bands is not as good as that of the yrast and yrare doublet bands. Supported by Plan Project of Beijing College Students’ Scientific Research and Entrepreneurial Action, Major State 973 Program of China (2013CB834400), National Natural Science Foundation of China (11175002, 11335002, 11375015, 11461141002), National Fund for Fostering Talents of Basic Science (NFFTBS) (J1103206), Research Fund for Doctoral Program of Higher Education (20110001110087) and China Postdoctoral Science Foundation (2015M580007)

Confirming the nature of the knot near the pulsar B1951+32

NASA Astrophysics Data System (ADS)

Zyuzin, D. A.; Shibanov, Yu A.; Pavlov, G. G.; Danilenko, A. A.

2017-12-01

The energetic and fast-moving radio and γ-ray pulsar B1951+32 is associated with the supernova remnant CTB 80. It powers a complex pulsar wind nebula detected in the radio, Hα and X-rays (Moon et al 2004 ApJ 610 L33). A puzzling optical knot was detected about 0″.5 from the pulsar in the optical and near-IR (Moon et al 2004 ApJ 610 L33; Hester 2000 Bulletin of the AAS 32 1542). It is reminiscent of the unique “inner optical knot” located 0″.6 from the Crab pulsar. Until now there has been no evidence that B1951+32 knot is indeed associated with the pulsar. We observed the pulsar field with the Gemini-North telescope in 2016 to check the association. We performed first near-IR high spatial resolution imaging in the K s band using the NIRI+Altair instrument and deep optical imaging in the gr bands using the GMOS instrument. Our observations showed that the current knot position is shifted by ≈ 0″.6 from the position measured with the HST in 1997. This is consistent with the known pulsar proper motion and is direct evidence of the pulsar-knot connection. We compared the spectral energy distribution of the knot emission with that of the Crab knot. Possible implications of the results are discussed.

Bandwidth Extension of an S-band, Fundamental-Mode Eight-Beam Klystron

DTIC Science & Technology

2006-04-01

Extension of an S - band , Fundamental-Mode Eight-Beam Klystron Khanh T. Nguyen Beam-Wave Research, Inc. Bethesda, MD 20814 Dean E. Pershing ATK Mission...of a five-cavity, approximately 18 cm downstream from the center of the broadband, high - power multiple-beam klystron (MBK) first gap - the logical...the circuit generates >550 kW across the band with a peak power of more than 600 kW at -3.27 Keywords: Multiple-beam klystron ; MBK; bandwidth GHz. The 1

Relation between star formation and AGN activity in typical elliptical galaxies: Analysis of the 2MASS K-band galaxy images

NASA Astrophysics Data System (ADS)

Pierce, Katherine

2014-01-01

We are carrying out a program of aperture photometry on typical elliptical galaxies. While there are many ways to calculate the and magnitude, we are going to use the Aperture Photometry Tool (APT) GUI and the program IRAF (Image Reduction and Analysis Facility). By looking at a sample of 236 galaxies from the 2MASS survey k-band, it was determined that 68 of the galaxies needed some sort of a pixel blocking technique due to unwanted background stars or galaxies that may interfere with our readings. My job is to determine a way to block out these pixels while not compromising the true from the galaxy.

A measurement of the vibrational band strength for the v3 band of the HO2 radical

NASA Technical Reports Server (NTRS)

Zahniser, M. S.; Stanton, A. C.

1984-01-01

Laboratory measurements of the v(3) band strength of HO2 using a tunable diode laser to measure the absorption strength of a vibration-rotation line in the P branch near 1080/cm are reported. The HO2 is generated in a discharge-flow system by reaction of fluorine atoms with excess H2O2: F + H2O2 - HO2 + HF. The HO2 concentration is determined from measurements of F-atom concentrations using both chemical titration with Cl2 and tunable diode laser absorption by the F-atom spin-orbit transition near 404/cm. The experimental data are consistent with a value of k(3) = (1.6 + or - 0.3) x 10 to the 12th cu cm/s and a ratio k(4)/k(1) = 1.0 + or - 0.4. The line strength for the 6(15) - 7(16)F(1) transition is 2.9 x 10 to the -21 sq cm/molecule/cm, which corresponds to a v(3) band strength of 35 + or - 9/sq cm/(STP atm). This value is a factor of 1.6 to 6 lower than previous ab initio calculations.

Reconstruction of Band Structure Induced by Electronic Nematicity in an FeSe Superconductor

NASA Astrophysics Data System (ADS)

Nakayama, K.; Miyata, Y.; Phan, G. N.; Sato, T.; Tanabe, Y.; Urata, T.; Tanigaki, K.; Takahashi, T.

2014-12-01

We have performed high-resolution angle-resolved photoemission spectroscopy on an FeSe superconductor (Tc˜8 K ), which exhibits a tetragonal-to-orthorhombic structural transition at Ts˜90 K . At low temperature, we found splitting of the energy bands as large as 50 meV at the M point in the Brillouin zone, likely caused by the formation of electronically driven nematic states. This band splitting persists up to T ˜110 K , slightly above Ts, suggesting that the structural transition is triggered by the electronic nematicity. We have also revealed that at low temperature the band splitting gives rise to a van Hove singularity within 5 meV of the Fermi energy. The present result strongly suggests that this unusual electronic state is responsible for the unconventional superconductivity in FeSe.

Atypically small temperature-dependence of the direct band gap in the metastable semiconductor copper nitride Cu 3 N

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

Birkett, Max; Savory, Christopher N.; Fioretti, Angela N.

The temperature-dependence of the direct band gap and thermal expansion in the metastable anti-ReO 3 semiconductor Cu 3N are investigated between 4.2 and 300 K by Fourier-transform infrared spectroscopy and x-ray diffraction. Complementary refractive index spectra are determined by spectroscopic ellipsometry at 300K. A direct gap of 1.68eV is associated with the absorption onset at 300K, which strengthens continuously and reaches a magnitude of 3.5 x 10 5cm -1 at 2.7eV, suggesting potential for photovoltaic applications. Notably, the direct gap redshifts by just 24meV between 4.2 and 300K, giving an atypically small band-gap temperature coefficient dE g/dT of -0.082meV/K. Additionally,more » the band structure, dielectric function, phonon dispersion, linear expansion, and heat capacity are calculated using density functional theory; remarkable similarities between the experimental and calculated refractive index spectra support the accuracy of these calculations, which indicate beneficially low hole effective masses and potential negative thermal expansion below 50K. To assess the lattice expansion contribution to the band-gap temperature-dependence, a quasiharmonic model fit to the observed lattice contraction finds a monotonically decreasing linear expansion (descending past 10 -6K -1 below 80K), while estimating the Debye temperature, lattice heat capacity, and Gruneisen parameter. Accounting for lattice and electron-phonon contributions to the observed band-gap evolution suggests average phonon energies that are qualitatively consistent with predicted maxima in the phonon density of states. Furthermore, as band-edge temperature-dependence has significant consequences for device performance, copper nitride should be well suited for applications that require a largely temperature-invariant band gap.« less

Atypically small temperature-dependence of the direct band gap in the metastable semiconductor copper nitride Cu 3 N

DOE PAGES

Birkett, Max; Savory, Christopher N.; Fioretti, Angela N.; ...

2017-03-06

The temperature-dependence of the direct band gap and thermal expansion in the metastable anti-ReO 3 semiconductor Cu 3N are investigated between 4.2 and 300 K by Fourier-transform infrared spectroscopy and x-ray diffraction. Complementary refractive index spectra are determined by spectroscopic ellipsometry at 300K. A direct gap of 1.68eV is associated with the absorption onset at 300K, which strengthens continuously and reaches a magnitude of 3.5 x 10 5cm -1 at 2.7eV, suggesting potential for photovoltaic applications. Notably, the direct gap redshifts by just 24meV between 4.2 and 300K, giving an atypically small band-gap temperature coefficient dE g/dT of -0.082meV/K. Additionally,more » the band structure, dielectric function, phonon dispersion, linear expansion, and heat capacity are calculated using density functional theory; remarkable similarities between the experimental and calculated refractive index spectra support the accuracy of these calculations, which indicate beneficially low hole effective masses and potential negative thermal expansion below 50K. To assess the lattice expansion contribution to the band-gap temperature-dependence, a quasiharmonic model fit to the observed lattice contraction finds a monotonically decreasing linear expansion (descending past 10 -6K -1 below 80K), while estimating the Debye temperature, lattice heat capacity, and Gruneisen parameter. Accounting for lattice and electron-phonon contributions to the observed band-gap evolution suggests average phonon energies that are qualitatively consistent with predicted maxima in the phonon density of states. Furthermore, as band-edge temperature-dependence has significant consequences for device performance, copper nitride should be well suited for applications that require a largely temperature-invariant band gap.« less

Temperature-dependent internal photoemission probe for band parameters

NASA Astrophysics Data System (ADS)

Lao, Yan-Feng; Perera, A. G. Unil

2012-11-01

The temperature-dependent characteristic of band offsets at the heterojunction interface was studied by an internal photoemission (IPE) method. In contrast to the traditional Fowler method independent of the temperature (T), this method takes into account carrier thermalization and carrier/dopant-induced band-renormalization and band-tailing effects, and thus measures the band-offset parameter at different temperatures. Despite intensive studies in the past few decades, the T dependence of this key band parameter is still not well understood. Re-examining a p-type doped GaAs emitter/undoped AlxGa1-xAs barrier heterojunction system disclosed its previously ignored T dependency in the valence-band offset, with a variation up to ˜-10-4 eV/K in order to accommodate the difference in the T-dependent band gaps between GaAs and AlGaAs. Through determining the Fermi energy level (Ef), IPE is able to distinguish the impurity (IB) and valence bands (VB) of extrinsic semiconductors. One important example is to determine Ef of dilute magnetic semiconductors such as GaMnAs, and to understand whether it is in the IB or VB.

47 CFR 2.101 - Frequency and wavelength bands.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Metric abbreviations for the bands 4 VLF 3 to 30 kHz Myriametric waves B.Mam 5 LF 30 to 300 kHz Kilometric waves B.km 6 MF 300 to 3 000 kHz Hectometric waves B.hm 7 HF 3 to 30 MHz Decametric waves B.dam 8 VHF 30 to 300 MHz Metric waves B.m 9 UHF 300 to 3 000 MHz Decimetric waves B.dm 10 SHF 3 to 30 GHz...

Performance of a Block Structured, Hierarchical Adaptive MeshRefinement Code on the 64k Node IBM BlueGene/L Computer

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

Greenough, Jeffrey A.; de Supinski, Bronis R.; Yates, Robert K.

2005-04-25

We describe the performance of the block-structured Adaptive Mesh Refinement (AMR) code Raptor on the 32k node IBM BlueGene/L computer. This machine represents a significant step forward towards petascale computing. As such, it presents Raptor with many challenges for utilizing the hardware efficiently. In terms of performance, Raptor shows excellent weak and strong scaling when running in single level mode (no adaptivity). Hardware performance monitors show Raptor achieves an aggregate performance of 3:0 Tflops in the main integration kernel on the 32k system. Results from preliminary AMR runs on a prototype astrophysical problem demonstrate the efficiency of the current softwaremore » when running at large scale. The BG/L system is enabling a physics problem to be considered that represents a factor of 64 increase in overall size compared to the largest ones of this type computed to date. Finally, we provide a description of the development work currently underway to address our inefficiencies.« less

On the origin of the low-temperature band in depolarization current spectra of poled multicomponent silicate glasses

NASA Astrophysics Data System (ADS)

Brunkov, P. N.; Kaasik, V. P.; Lipovskii, A. A.; Tagantsev, D. K.

2018-04-01

Thermally stimulated depolarization current spectra of poled silicate multicomponent glasses in the vicinity of room temperature (220-320 K) have been recorded and two bands, typical for such glasses, have been observed. It was shown that the high-temperature band (at about 290 K) is related to the relaxation of poled glass structure in the bulk, while the low-temperature band (at about 230-270 K) should be attributed to the surface phenomenon—absorption/desorption of positive species of ambient atmosphere, supposedly, water cluster ions H+(H2O)n.

NiO: correlated band structure of a charge-transfer insulator.

PubMed

Kunes, J; Anisimov, V I; Skornyakov, S L; Lukoyanov, A V; Vollhardt, D

2007-10-12

The band structure of the prototypical charge-transfer insulator NiO is computed by using a combination of an ab initio band structure method and the dynamical mean-field theory with a quantum Monte-Carlo impurity solver. Employing a Hamiltonian which includes both Ni d and O p orbitals we find excellent agreement with the energy bands determined from angle-resolved photoemission spectroscopy. This brings an important progress in a long-standing problem of solid-state theory. Most notably we obtain the low-energy Zhang-Rice bands with strongly k-dependent orbital character discussed previously in the context of low-energy model theories.

Complex band structure and electronic transmission eigenchannels

NASA Astrophysics Data System (ADS)

Jensen, Anders; Strange, Mikkel; Smidstrup, Søren; Stokbro, Kurt; Solomon, Gemma C.; Reuter, Matthew G.

2017-12-01

It is natural to characterize materials in transport junctions by their conductance length dependence, β. Theoretical estimations of β are made employing two primary theories: complex band structure and density functional theory (DFT) Landauer transport. It has previously been shown that the β value derived from total Landauer transmission can be related to the β value from the smallest |ki| complex band; however, it is an open question whether there is a deeper relationship between the two. Here we probe the details of the relationship between transmission and complex band structure, in this case individual eigenchannel transmissions and different complex bands. We present calculations of decay constants for the two most conductive states as determined by complex band structure and standard DFT Landauer transport calculations for one semi-conductor and two molecular junctions. The molecular junctions show that both the length dependence of the total transmission and the individual transmission eigenvalues can be, almost always, found through the complex band structure. The complex band structure of the semi-conducting material, however, does not predict the length dependence of the total transmission but only of the individual channels, at some k-points, due to multiple channels contributing to transmission. We also observe instances of vertical bands, some of which are the smallest |ki| complex bands, that do not contribute to transport. By understanding the deeper relationship between complex bands and individual transmission eigenchannels, we can make a general statement about when the previously accepted wisdom linking transmission and complex band structure will fail, namely, when multiple channels contribute significantly to the transmission.

Band structure and orbital character of monolayer MoS2 with eleven-band tight-binding model

NASA Astrophysics Data System (ADS)

Shahriari, Majid; Ghalambor Dezfuli, Abdolmohammad; Sabaeian, Mohammad

2018-02-01

In this paper, based on a tight-binding (TB) model, first we present the calculations of eigenvalues as band structure and then present the eigenvectors as probability amplitude for finding electron in atomic orbitals for monolayer MoS2 in the first Brillouin zone. In these calculations we are considering hopping processes between the nearest-neighbor Mo-S, the next nearest-neighbor in-plan Mo-Mo, and the next nearest-neighbor in-plan and out-of-plan S-S atoms in a three-atom based unit cell of two-dimensional rhombic MoS2. The hopping integrals have been solved in terms of Slater-Koster and crystal field parameters. These parameters are calculated by comparing TB model with the density function theory (DFT) in the high-symmetry k-points (i.e. the K- and Γ-points). In our TB model all the 4d Mo orbitals and the 3p S orbitals are considered and detailed analysis of the orbital character of each energy level at the main high-symmetry points of the Brillouin zone is described. In comparison with DFT calculations, our results of TB model show a very good agreement for bands near the Fermi level. However for other bands which are far from the Fermi level, some discrepancies between our TB model and DFT calculations are observed. Upon the accuracy of Slater-Koster and crystal field parameters, on the contrary of DFT, our model provide enough accuracy to calculate all allowed transitions between energy bands that are very crucial for investigating the linear and nonlinear optical properties of monolayer MoS2.

On the Morphological Adaptations of the Thorax of Sphagniana sphagnorum (Ensifera, Tettigoniidae) that Enable Complex Stridulation via the Forewings

NASA Astrophysics Data System (ADS)

Gutierrez, Sara-Jane

Males of the flightless tettigoniid Sphagniana sphagnorum generate a complex two-spectrum signal via stridulation, using acoustically adapted forewings (tegmina). Complex-wave rapidly decaying pulses in trains, made upon the distal half of the file, have a broad-band (17-25 kHz) spectrum; short, spaced, ultrasonic and strongly sinusoidal 35 kHz pulses are emitted as trains over the file's proximal half. I studied how S. sphagnorum tegminal morphology enables the production of these two different spectra with the same forewings. The storage of elastic energy in the scraper is hypothesized to play a key role in driving the scraper over the file at a necessary tooth-contact rate. Scraper morphology indicates structural adaptations enabling storage of elastic energy. Wax loading tested the role of scraper-pit flexibility in scraper movement. Sound levels in resonant spectra were more substantially affected than those associated with broadband generation. Morphology and alignment of pteralia during tegmino-tegminal stridulation is also investigated.

High voltage breakdown phenomena in RF window, electron gun and RF cavities in 250 kW CW C band Klystron and their preventive measures

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

Lamba, O.S.; Badola, Richa; Baloda, Suman

The paper describes voltage break down phenomenon and preventive measures in components of 250 KW CW, C band Klystron under development at CEERI Pilani. The Klystron operates at a beam voltage of 50 kV and delivers 250 kW RF power at 5 GHz frequency. The Klystron consists of several key components and regions, which are subject to high electrical stress. The most important regions of electrical breakdown are electron gun, the RF ceramic window and output cavity gap area. In the critical components voltage breakdown considered at design stage by proper gap and other techniques. All these problems discussed, asmore » well as solution to alleviate this problem. The electron gun consists basically of cathode, BFE and anode. The cathode is operated at a voltage of 50 kV. In order to maintain the voltage standoff between cathode and anode a high voltage alumina seal and RF window have been designed developed and successfully used in the tube. (author)« less

Flow velocity profiling using acoustic time of flight flow metering based on wide band signals and adaptive beam-forming techniques

NASA Astrophysics Data System (ADS)

Murgan, I.; Candel, I.; Ioana, C.; Digulescu, A.; Bunea, F.; Ciocan, G. D.; Anghel, A.; Vasile, G.

2016-11-01

In this paper, we present a novel approach to non-intrusive flow velocity profiling technique using multi-element sensor array and wide-band signal's processing methods. Conventional techniques for the measurements of the flow velocity profiles are usually based on intrusive instruments (current meters, acoustic Doppler profilers, Pitot tubes, etc.) that take punctual velocity readings. Although very efficient, these choices are limited in terms of practical cases of applications especially when non-intrusive measurements techniques are required and/or a spatial accuracy of the velocity profiling is required This is due to factors related to hydraulic machinery down time, the often long time duration needed to explore the entire section area, the frequent cumbersome number of devices that needs to be handled simultaneously, or the impossibility to perform intrusive tests. In the case of non-intrusive flow profiling methods based on acoustic techniques, previous methods concentrated on using a large number of acoustic transducers placed around the measured section. Although feasible, this approach presents several major drawbacks such as a complicated signal timing, transmission, acquisition and recording system, resulting in a relative high cost of operation. In addition, because of the geometrical constraints, a desired number of sensors may not be installed. Recent results in acoustic flow metering based on wide band signals and adaptive beamforming proved that it is possible to achieve flow velocity profiles using less acoustic transducers. In a normal acoustic time of flight path the transducers are both emitters and receivers, sequentially changing their roles. In the new configuration, proposed in this paper, two new receivers are added on each side. Since the beam angles of each acoustic transducer are wide enough the newly added transducers can receive the transmitted signals and additional time of flight estimation can be done. Thus, several flow

A Ku-band magnetically insulated transmission line oscillator with overmoded slow-wave-structure

NASA Astrophysics Data System (ADS)

Jiang, Tao; He, Jun-Tao; Zhang, Jian-De; Li, Zhi-Qiang; Ling, Jun-Pu

2016-12-01

In order to enhance the power capacity, an improved Ku-band magnetically insulated transmission line oscillator (MILO) with overmoded slow-wave-structure (SWS) is proposed and investigated numerically and experimentally. The analysis of the dispersion relationship and the resonant curve of the cold test indicate that the device can operate at the near π mode of the TM01 mode, which is useful for mode selection and control. In the particle simulation, the improved Ku-band MILO generates a microwave with a power of 1.5 GW and a frequency of 12.3 GHz under an input voltage of 480 kV and input current of 42 kA. Finally, experimental investigation of the improved Ku-band MILO is carried out. A high-power microwave (HPM) with an average power of 800 MW, a frequency of 12.35 GHz, and pulse width of 35 ns is generated under a diode voltage of 500 kV and beam current of 43 kA. The consistency between the experimental and simulated far-field radiation pattern confirms that the operating mode of the improved Ku-band MILO is well controlled in π mode of the TM01 mode. Project supported partly by the National Natural Science Foundation of China (Grant No. 61171021).

Temperature-dependent optical band gap of the metastable zinc-blende structure [beta]-GaN

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

Ramirez-Flores, G.; Navarro-Contreras, H.; Lastras-Martinez, A.

1994-09-15

The temperature-dependent (10--300 K) optical band gap [ital E][sub 0]([ital T]) of the epitaxial metastable zinc-blende-structure [beta]-GaN(001)4[times]1 has been determined by modulated photoreflectance and used to interpret low-temperature photoluminescence spectra. [ital E][sub 0] in [beta]-GaN was found to vary from 3.302[plus minus]0.004 eV at 10 K to 3.231[plus minus]0.008 eV at 300 K with a temperature dependence given by [ital E][sub 0]([ital T]) =3.302--6.697[times]10[sup [minus]4][ital T][sup 2]/([ital T]+600) eV. The spin-orbit splitting [Delta][sub 0] in the valence band was determined to be 17[plus minus]1 meV. The oscillations in the photoreflectance spectra were very sharp with a broadening parameter [Gamma] ofmore » only 10 meV at 10 K. The dominant transition observed in temperature-dependent photoluminescence was attributed to radiative recombination between a shallow donor, at [congruent]11 meV below the conduction-band edge and the valence band.« less

Validation of endothelin B receptor antibodies reveals two distinct receptor-related bands on Western blot.

PubMed

Barr, Travis P; Kornberg, Daniel; Montmayeur, Jean-Pierre; Long, Melinda; Reichheld, Stephen; Strichartz, Gary R

2015-01-01

Antibodies are important tools for the study of protein expression but are often used without full validation. In this study, we used Western blots to characterize antibodies targeted to the N or C terminal (NT or CT, respectively) and the second or third intracellular loop (IL2 or IL3, respectively) of the endothelin B receptor (ETB). The IL2-targeted antibody accurately detected endogenous ETB expression in rat brain and cultured rat astrocytes by labeling a 50-kDa band, the expected weight of full-length ETB. However, this antibody failed to detect transfected ETB in HEK293 cultures. In contrast, the NT-targeted antibody accurately detected endogenous ETB in rat astrocyte cultures and transfected ETB in HEK293 cultures by labeling a 37-kDa band but failed to detect endogenous ETB in rat brain. Bands detected by the CT- or IL3-targeted antibody were found to be unrelated to ETB. Our findings show that functional ETB can be detected at 50 or 37kDa on Western blot, with drastic differences in antibody affinity for these bands. The 37-kDa band likely reflects ETB processing, which appears to be dependent on cell type and/or culture condition. Copyright © 2014 Elsevier Inc. All rights reserved.

A relevant IgE-reactive 28kDa protein identified from Salsola kali pollen extract by proteomics is a natural degradation product of an integral 47kDa polygalaturonase.

PubMed

Mas, Salvador; Oeo-Santos, Carmen; Cuesta-Herranz, Javier; Díaz-Perales, Araceli; Colás, Carlos; Fernández, Javier; Barber, Domingo; Rodríguez, Rosalía; de Los Ríos, Vivian; Barderas, Rodrigo; Villalba, Mayte

2017-08-01

A highly prevalent IgE-binding protein band of 28kDa is observed when Salsola kali pollen extract is incubated with individual sera from Amaranthaceae pollen sensitized patients. By an immunoproteomic analysis of S. kali pollen extract, we identified this protein band as an allergenic polygalacturonase enzyme. The allergen, named Sal k 6, exhibits a pI of 7.14 and a molecular mass of 39,554.2Da. It presents similarities to Platanaceae, Poaceae, and Cupressaceae allergenic polygalacturonases. cDNA-encoding sequence was subcloned into the pET41b vector and produced in bacteria as a His-tag fusion recombinant protein. The far-UV CD spectrum determined that rSal k 6 was folded. Immunostaining of the S. kali pollen protein extract with a rSal k 6-specific pAb and LC-MS/MS proteomic analyses confirmed the co-existence of the 28kDa band together with an allergenic band of about 47kDa in the pollen extract. Therefore, the 28kDa was assigned as a natural degradation product of the 47kDa integral polygalacturonase. The IgE-binding inhibition to S. kali pollen extract using rSal k 6 as inhibitor showed that signals directed to both protein bands of 28 and 47kDa were completely abrogated. The average prevalence of rSal k 6 among the three populations analyzed was 30%, with values correlating well with the levels of grains/m 3 of Amaranthaceae pollen. Sal k 6 shares IgE epitopes with Oleaceae members (Fraxinus excelsior, Olea europaea and Syringa vulgaris), with IgE-inhibition values ranging from 20% to 60%, respectively. No IgE-inhibition was observed with plant-derived food extracts. Copyright © 2017 Elsevier B.V. All rights reserved.

A Neural Network Model for K(λ) Retrieval and Application to Global K par Monitoring

PubMed Central

Chen, Jun; Zhu, Yuanli; Wu, Yongsheng; Cui, Tingwei; Ishizaka, Joji; Ju, Yongtao

2015-01-01

Accurate estimation of diffuse attenuation coefficients in the visible wavelengths K d(λ) from remotely sensed data is particularly challenging in global oceanic and coastal waters. The objectives of the present study are to evaluate the applicability of a semi-analytical K d(λ) retrieval model (SAKM) and Jamet’s neural network model (JNNM), and then develop a new neural network K d(λ) retrieval model (NNKM). Based on the comparison of K d(λ) predicted by these models with in situ measurements taken from the global oceanic and coastal waters, all of the NNKM, SAKM, and JNNM models work well in K d(λ) retrievals, but the NNKM model works more stable and accurate than both SAKM and JNNM models. The near-infrared band-based and shortwave infrared band-based combined model is used to remove the atmospheric effects on MODIS data. The K d(λ) data was determined from the atmospheric corrected MODIS data using the NNKM, JNNM, and SAKM models. The results show that the NNKM model produces <30% uncertainty in deriving K d(λ) from global oceanic and coastal waters, which is 4.88-17.18% more accurate than SAKM and JNNM models. Furthermore, we employ an empirical approach to calculate K par from the NNKM model-derived diffuse attenuation coefficient at visible bands (443, 488, 555, and 667 nm). The results show that our model presents a satisfactory performance in deriving K par from the global oceanic and coastal waters with 20.2% uncertainty. The K par are quantified from MODIS data atmospheric correction using our model. Comparing with field measurements, our model produces ~31.0% uncertainty in deriving K par from Bohai Sea. Finally, the applicability of our model for general oceanographic studies is briefly illuminated by applying it to climatological monthly mean remote sensing reflectance for time ranging from July, 2002- July 2014 at the global scale. The results indicate that the high K d(λ) and K par values are usually found around the coastal zones in the

Rubber band as external assist device to provide simple grip for quadriplegic patients.

PubMed

Pham, H N; Noble, C N; Hentz, V R

1988-08-01

The rubber band as an external assist device provides an effective grip for the hand of high spinal cord injury quadriplegic patients. This technique can also be useful for preoperative patients who are undergoing physical and occupational therapy or to assess patients' needs for surgery. The rubber band as an adaptive device is preferred because of its availability, low visibility, and ease of application. We attempt to provide a more standardized method of the rubber band technique and to popularize it.

How to detect and reduce movement artifacts in near-infrared imaging using moving standard deviation and spline interpolation.

PubMed

Scholkmann, F; Spichtig, S; Muehlemann, T; Wolf, M

2010-05-01

Near-infrared imaging (NIRI) is a neuroimaging technique which enables us to non-invasively measure hemodynamic changes in the human brain. Since the technique is very sensitive, the movement of a subject can cause movement artifacts (MAs), which affect the signal quality and results to a high degree. No general method is yet available to reduce these MAs effectively. The aim was to develop a new MA reduction method. A method based on moving standard deviation and spline interpolation was developed. It enables the semi-automatic detection and reduction of MAs in the data. It was validated using simulated and real NIRI signals. The results show that a significant reduction of MAs and an increase in signal quality are achieved. The effectiveness and usability of the method is demonstrated by the improved detection of evoked hemodynamic responses. The present method can not only be used in the postprocessing of NIRI signals but also for other kinds of data containing artifacts, for example ECG or EEG signals.

High-Efficiency K-Band Space Traveling-Wave Tube Amplifier for Near-Earth High Data Rate Communications

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Force, Dale A.; Spitsen, Paul C.; Menninger, William L.; Robbins, Neal R.; Dibb, Daniel R.; Todd, Phillip

2010-01-01

The RF performance of a new K-Band helix conduction cooled traveling-wave tube amplifier (TWTA) is presented in this paper. A total of three such units were manufactured, tested and delivered. The first unit is currently flying onboard NASA s Lunar Reconnaissance Orbiter (LRO) spacecraft and has flawlessly completed over 2000 orbits around the Moon. The second unit is a proto-flight model. The third unit will fly onboard NASA s International Space Station (ISS) as a very compact and lightweight transmitter package for the Communications, Navigation and Networking Reconfigurable Testbed (CoNNeCT), which is scheduled for launch in 2011. These TWTAs were characterized over the frequencies 25.5 to 25.8 GHz. The saturated RF output power is >40 W and the saturated RF gain is >46 dB. The saturated AM-to- PM conversion is 3.5 /dB and the small signal gain ripple is 0.46 dB peak-to-peak. The overall efficiency of the TWTA, including that of the electronic power conditioner (EPC) is as high as 45 percent.

High-Efficiency K-Band Space Traveling-Wave Tube Amplifier for Near-Earth High Data Rate Communications

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Force, Dale A.; Spitsen, Paul C.; Menninger, William L.; Robbins, Neal R.; Dibb, Daniel R.; Todd, Phillip C.

2010-01-01

The RF performance of a new K-Band helix conduction cooled traveling-wave tube amplifier (TWTA), is presented in this paper. A total of three such units were manufactured, tested and delivered. The first unit is currently flying onboard NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft and has flawlessly completed over 2000 orbits around the Moon. The second unit is a proto-flight model. The third unit will fly onboard NASA's International Space Station (ISS) as a very compact and lightweight transmitter package for the Communications, Navigation and Networking Reconfigurable Testbed (CoNNeCT), which is scheduled for launch in 2011. These TWTAs were characterized over the frequencies 25.5 to 25.8 GHz. The saturated RF output power is greater than 40 W and the saturated RF gain is greater than 46 dB. The saturated AM-to-PM conversion is 3.5 /dB and the small signal gain ripple is 0.46 dB peak-to-peak. The overall efficiency of the TWTA, including that of the electronic power conditioner (EPC) is as high as 45%.

Calibration of VIIRS F1 Sensor Fire Detection Band Using lunar Observations

NASA Technical Reports Server (NTRS)

McIntire, Jeff; Efremova, Boryana; Xiong, Xiaoxiong

2012-01-01

Visible Infrared Imager Radiometer Suite (VIIRS) Fight 1 (Fl) sensor includes a fire detection band at roughly 4 microns. This spectral band has two gain states; fire detection occurs in the low gain state above approximately 345 K. The thermal bands normally utilize an on-board blackbody to provide on-orbit calibration. However, as the maximum temperature of this blackbody is 315 K, the low gain state of the 4 micron band cannot be calibrated in the same manner as the rest of the thermal bands. Regular observations of the moon provide an alternative calibration source. The lunar surface temperature has been recently mapped by the DIVINER sensor on the LRO platform. The periodic on-board high gain calibration along with the DIVINER surface temperatures was used to determine the emissivity and solar reflectance of the lunar surface at 4 microns; these factors and the lunar data are then used to fit the low gain calibration coefficients of the 4 micron band. Furthermore, the emissivity of the lunar surface is well known near 8.5 microns due to the Christiansen feature (an emissivity maximum associated with Si-O stretching vibrations) and the solar reflectance is negligible. Thus, the 8.5 micron band is used for relative calibration with the 4 micron band to de-trend any temporal variations. In addition, the remaining thermal bands are analyzed in a similar fashion, with both calculated emissivities and solar reflectances produced.

Effective band structure of random III-V alloys

NASA Astrophysics Data System (ADS)

Popescu, Voicu; Zunger, Alex

2010-03-01

Random substitutional alloys have no long range order (LRO) or translational symmetry so rigorously speaking they have no E(k) band structure or manifestations thereof. Yet, many experiments on alloys are interpreted using the language of band theory, e.g. inferring Van Hove singularities, band dispersion and effective masses. Many standard alloy theories (VCA- or CPA-based) have the LRO imposed on the alloy Hamiltonian, assuming only on-site disorder, so they can not be used to judge the extent of LRO that really exists. We adopt the opposite way, by using large (thousand atom) randomly generated supercells in which chemically identical alloy atoms are allowed to have different local environments (a polymorphous representation). This then drives site-dependent atomic relaxation as well as potential fluctuations. The eigenstates from such supercells are then mapped onto the Brillouin zone (BZ) of the primitive cell, producing effective band dispersion. Results for (In,Ga)X show band-like behaviour only near the centre and faces of the BZ but rapidly lose such characteristics away from γ or for higher bands. We further analyse the effects of stoichiometry variation, internal relaxation, and short-range order on the alloy band structure.

47 CFR 15.239 - Operation in the band 88-108 MHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.239 Operation in the band 88-108 MHz. (a) Emissions from the intentional radiator shall be confined within a band 200 kHz wide centered... the general radiated emission limits in § 15.209. (d) A custom built telemetry intentional radiator...

Text grouping in patent analysis using adaptive K-means clustering algorithm

NASA Astrophysics Data System (ADS)

Shanie, Tiara; Suprijadi, Jadi; Zulhanif

2017-03-01

Patents are one of the Intellectual Property. Analyzing patent is one requirement in knowing well the development of technology in each country and in the world now. This study uses the patent document coming from the Espacenet server about Green Tea. Patent documents related to the technology in the field of tea is still widespread, so it will be difficult for users to information retrieval (IR). Therefore, it is necessary efforts to categorize documents in a specific group of related terms contained therein. This study uses titles patent text data with the proposed Green Tea in Statistical Text Mining methods consists of two phases: data preparation and data analysis stage. The data preparation phase uses Text Mining methods and data analysis stage is done by statistics. Statistical analysis in this study using a cluster analysis algorithm, the Adaptive K-Means Clustering Algorithm. Results from this study showed that based on the maximum value Silhouette, generate 87 clusters associated fifteen terms therein that can be utilized in the process of information retrieval needs.

Luminescence of 1,4-naphthoquinone and the vitamin K system in Shpolskii matrices at 4 K

NASA Astrophysics Data System (ADS)

Vo-Dinh, Tuan; Wild, Urs P.

This work investigates the high-resolution phosphorescence spectra of 1,4-naphthoquinone and the vitamin K system in Shpolskii solvents at 4 K. The quasi-linear vibronic bands are discussed with regard to spectral assignments and polarization data. The effect of non-totally symmetric vibrations is also discussed.

Structural, optical and electronic properties of K2Ba(NO3)4 crystal

NASA Astrophysics Data System (ADS)

Isaenko, L. I.; Korzhneva, K. E.; Goryainov, S. V.; Goloshumova, A. A.; Sheludyakova, L. A.; Bekenev, V. L.; Khyzhun, O. Y.

2018-02-01

Nitrate crystals reveal nonlinear optical properties and could be considered as converters of laser radiation in the short-wave region. The conditions for obtaining and basic properties of K2Ba(NO3)4 double nitrate crystals were investigated. Crystal growth was implemented by slow cooling in the temperature range of 72-49 °C and low rate evaporation. The structural analysis of K2Ba(NO3)4 formation on the basis of two mixed simple nitrate structures is discussed. The main groups of oscillations in K2Ba(NO3)4 crystal were revealed using Raman and IR spectroscopy, and the table of vibrations for this compound was compiled. The electronic structure of K2Ba(NO3)4 was elucidated in the present work from both experimental and theoretical viewpoints. In particular, X-ray photoelectron spectroscopy (XPS) was employed in the present work to measure binding energies of the atoms constituting the titled compound and its XPS valence-band spectrum for both pristine and Ar+ ion-bombarded surfaces. Further, total and partial densities of states of constituent atoms of K2Ba(NO3)4 have been calculated. The calculations reveal that the O 2p states dominate in the total valence-band region of K2Ba(NO3)4 except of its bottom, where K 3p and Ba 5p states are the principal contributors, while the bottom of the conduction band is composed mainly of the unoccupied O 2p states, with somewhat smaller contributions of the N 2p∗ states as well. With respect to the occupation of the valence band by the O 2p states, the present band-structure calculations are confirmed by comparison on a common energy scale of the XPS valence-band spectrum and the X-ray emission O Kα band for the K2Ba(NO3)4 crystal under study. Furthermore, the present calculations indicate that the K2Ba(NO3)4 compound is a direct-gap material.

Silicon micromachined broad band light source

NASA Technical Reports Server (NTRS)

George, Thomas (Inventor); Jones, Eric (Inventor); Tuma, Margaret L. (Inventor); Eastwood, Michael (Inventor); Hansler, Richard (Inventor)

2004-01-01

A micro electromechanical system (MEMS) broad band incandescent light source includes three layers: a top transmission window layer; a middle filament mount layer; and a bottom reflector layer. A tungsten filament with a spiral geometry is positioned over a hole in the middle layer. A portion of the broad band light from the heated filament is reflective off the bottom layer. Light from the filament and the reflected light of the filament are transmitted through the transmission window. The light source may operate at temperatures of 2500 K or above. The light source may be incorporated into an on board calibrator (OBC) for a spectrometer.

A study of frequency band structure in two-dimensional homogeneous anisotropic phononic K3-metamaterials

NASA Astrophysics Data System (ADS)

Gorshkov, V. N.; Navadeh, N.; Fallah, A. S.

2017-09-01

Phononic metamaterials are synthesised materials in which locally resonant units are arranged in a particular geometry of a substratum lattice and connected in a predefined topology. This study investigates dispersion surfaces in two-dimensional anisotropic acoustic metamaterials involving mass-in-mass units connected by massless springs in K3 topology. The reasons behind the particular choice of this topology are explained. Two sets of solutions for the eigenvalue problem | {\\boldsymbol{D}}({ω }2,{\\boldsymbol{k}})| =0 are obtained and the existence of absolutely different mechanisms of gap formation between acoustic and optical surface frequencies is shown as a bright display of quantum effects like strong coupling, energy splitting, and level crossings in classical mechanical systems. It has been concluded that a single dimensionless parameter i.e. relative mass controls the order of formation of gaps between different frequency surfaces. If the internal mass of the locally resonant mass-in-mass unit, m, increases relative to its external mass, M, then the coupling between the internal and external vibrations in the whole system rises sharply, and a threshold {μ }* is reached so that for m/M> {μ }* the optical vibrations break the continuous spectrum of ‘acoustic phonons’ creating the gap between them for any value of other system parameters. The methods to control gap parameters and polarisation properties of the optical vibrations created over these gaps were investigated. Dependencies of morphology and width of gaps for several anisotropic cases have been expounded and the physical meaning of singularity at the point of tangential contact between two adjacent frequency surfaces has been provided. Repulsion between different frequency band curves, as planar projections of surfaces, has been explained. The limiting case of isotropy has been discussed and it has been shown that, in the isotropic case, the lower gap always forms, irrespective of the value

Dendrometer bands made easy: using modified cable ties to measure incremental growth of trees

USGS Publications Warehouse

Anemaet, Evelyn R.; Middleton, Beth A.

2013-01-01

Dendrometer bands are a useful way to make sequential repeated measurements of tree growth, but traditional dendrometer bands can be expensive, time consuming, and difficult to construct in the field. An alternative to the traditional method of band construction is to adapt commercially available materials. This paper describes how to construct and install dendrometer bands using smooth-edged, stainless steel, cable tie banding and attachable rollerball heads. As a performance comparison, both traditional and cable tie dendrometer bands were installed on baldcypress trees at the National Wetlands Research Center in Lafayette, Louisiana, by both an experienced and a novice worker. Band installation times were recorded, and growth of the trees as estimated by the two band types was measured after approximately one year, demonstrating equivalence of the two methods. This efficient approach to dendrometer band construction can help advance the knowledge of long-term tree growth in ecological studies.

Single amino acid changes in the 6K1-CI region can promote the alternative adaptation of Prunus- and Nicotiana-propagated Plum pox virus C isolates to either host.

PubMed

Calvo, María; Malinowski, Tadeusz; García, Juan Antonio

2014-02-01

Plum pox virus (PPV) C is one of the less common PPV strains and specifically infects cherry trees in nature. Making use of two PPV-C isolates that display different pathogenicity features, i.e., SwCMp, which had been adapted to Nicotiana species, and BY101, which had been isolated from cherry rootstock L2 (Prunus lannesiana) and propagated only in cherry species, we have generated two infective full-length cDNA clones in order to determine which viral factors are involved in the adaptation to each host. According to our results, the C-P3(PIPO)/6K1/N-CI (cylindrical inclusion) region contains overlapping but not coincident viral determinants involved in symptoms development, local viral amplification, and systemic movement capacity. Amino acid changes in this region promoting the adaptation to N. benthamiana or P. avium have trade-off effects in the alternative host. In both cases, adaptation can be achieved through single amino acid changes in the NIapro protease recognition motif between 6K1 and CI or in nearby sequences. Thus, we hypothesize that the potyvirus polyprotein processing could depend on specific host factors and the adaptation of PPV-C isolates to particular hosts relies on a fine regulation of the proteolytic cleavage of the 6K1-CI junction.

Outstanding problems in the band structures of 152Sm

NASA Astrophysics Data System (ADS)

Gupta, J. B.; Hamilton, J. H.

2017-09-01

The recent data on B (E 2 ) values, deduced from the multi-Coulex excitation of the low spin states in the decay of 152Sm, and other experimental findings in the last two decades are compared with the predictions from the microscopic dynamic pairing plus quadrupole model of Kumar and Baranger. The 1292.8 keV 2+ state is assigned to the 03 + band, and the K =2 assignment of the 1769 keV 2+ state is confirmed. The anomaly of the shape coexistence of the assumed spherical β band versus the deformed ground band is resolved. The values from the critical point symmetry X(5) support the collective character of the β band. The problem with the two-term interacting boson model Hamiltonian in predicting β and γ bands in 152Sm leads to interesting consequences. The collective features of the second excited Kπ=03 + band are preferred over the "pairing isomer" view. Also the multiphonon nature of the higher lying Kπ=22 +β γ band and Kπ=4+ band are illustrated vis-à-vis the new data and the nuclear structure theory.

Band alignment and p -type doping of ZnSnN2

NASA Astrophysics Data System (ADS)

Wang, Tianshi; Ni, Chaoying; Janotti, Anderson

2017-05-01

Composed of earth-abundant elements, ZnSnN2 is a promising semiconductor for photovoltaic and photoelectrochemical applications. However, basic properties such as the precise value of the band gap and the band alignment to other semiconductors are still unresolved. For instance, reported values for the band gap vary from 1.4 to 2.0 eV. In addition, doping in ZnSnN2 remains largely unexplored. Using density functional theory with the Heyd-Scuseria-Ernzerhof hybrid functional, we investigate the electronic structure of ZnSnN2, its band alignment to GaN and ZnO, and the possibility of p -type doping. We find that the position of the valence-band maximum of ZnSnN2 is 0.39 eV higher than that in GaN, yet the conduction-band minimum is close to that in ZnO, which suggests that achieving p -type conductivity is likely as in GaN, yet it may be difficult to control unintentional n -type conductivity as in ZnO. Among possible p -type dopants, we explore Li, Na, and K substituting on the Zn site. We show that while LiZn is a shallow acceptor, NaZn and KZn are deep acceptors, which we trace back to large local relaxations around the Na and K impurities due to the atomic size mismatches.

Enhanced tunable narrow-band THz emission from laser-modulated electron beams

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

Xiang, D.; Stupakov, G.; /SLAC

2009-06-19

We propose and analyze a scheme to generate enhanced narrow-band terahertz (THz) radiation through down-conversion of the frequency of optical lasers using laser-modulated electron beams. In the scheme the electron beam is first energy modulated by two lasers with wave numbers k{sub 1} and k2, respectively. After passing through a dispersion section, the energy modulation is converted to density modulation. Due to the nonlinear conversion process, the beam will have density modulation at wave number k = nk{sub 1} + mk{sub 2}, where n and m are positive or negative integers. By properly choosing the parameters for the lasers andmore » dispersion section, one can generate density modulation at THz frequency in the beam using optical lasers. This density-modulated beam can be used to generate powerful narrow-band THz radiation. Since the THz radiation is in tight synchronization with the lasers, it should provide a high temporal resolution for the optical-pump THz-probe experiments. The central frequency of the THz radiation can be easily tuned by varying the wavelength of the two lasers and the energy chirp of the electron beam. The proposed scheme is in principle able to generate intense narrow-band THz radiation covering the whole THz range and offers a promising way towards the tunable intense narrow-band THz sources.« less

Optical study of the band structure of wurtzite GaP nanowires

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

Assali, S., E-mail: simone.assali@polymtl.ca; Greil, J.; Zardo, I.

2016-07-28

We investigated the optical properties of wurtzite (WZ) GaP nanowires by performing photoluminescence (PL) and time-resolved PL measurements in the temperature range from 4 K to 300 K, together with atom probe tomography to identify residual impurities in the nanowires. At low temperature, the WZ GaP luminescence shows donor-acceptor pair emission at 2.115 eV and 2.088 eV, and Burstein-Moss band-filling continuum between 2.180 and 2.253 eV, resulting in a direct band gap above 2.170 eV. Sharp exciton α-β-γ lines are observed at 2.140–2.164–2.252 eV, respectively, showing clear differences in lifetime, presence of phonon replicas, and temperature-dependence. The excitonic nature of those peaks is critically discussed, leading tomore » a direct band gap of ∼2.190 eV and to a resonant state associated with the γ-line ∼80 meV above the Γ{sub 8C} conduction band edge.« less

Status of the GTC adaptive optics: integration in laboratory

NASA Astrophysics Data System (ADS)

Reyes García-Talavera, M.; Béjar, V. J. S.; López, J. C.; López, R. L.; Martín, C.; Martín, Y.; Montilla, I.; Núñez, M.; Puga, M.; Rodríguez, L. F.; Tenegi, F.; Tubío, O.; Bello, D.; Cavaller, L.; Prieto, G.; Rosado, M.

2016-07-01

Since the beginning of the development of the Gran Telescopio Canarias (GTC), an Adaptive Optics (AO) system was considered necessary to exploit the full diffraction-limited potential of the telescope. The GTC AO system designed during the last years is based on a single deformable mirror conjugated to the telescope pupil, and a Shack-Hartmann wavefront sensor with 20 x 20 subapertures, using an OCAM2 camera. The GTCAO system will provide a corrected beam with a Strehl Ratio (SR) of 0.65 in K-band with bright natural guide stars. Most of the subsystems have been manufactured and delivered. The upgrade for the operation with a Laser Guide Star (LGS) system has been recently approved. The present status of the GTCAO system, currently in its laboratory integration phase, is summarized in this paper.

Advances in III-V based dual-band MWIR/LWIR FPAs at HRL

NASA Astrophysics Data System (ADS)

Delaunay, Pierre-Yves; Nosho, Brett Z.; Gurga, Alexander R.; Terterian, Sevag; Rajavel, Rajesh D.

2017-02-01

Recent advances in superlattice-based infrared detectors have rendered this material system a solid alternative to HgCdTe for dual-band sensing applications. In particular, superlattices are attractive from a manufacturing perspective as the epitaxial wafers can be grown with a high degree of lateral uniformity, low macroscopic defect densities (< 50 cm-2) and achieve dark current levels comparable to HgCdTe detectors. In this paper, we will describe our recent effort on the VISTA program towards producing HD-format (1280x720, 12 μm pitch) superlattice based, dual-band MWIR/LWIR FPAs. We will report results from several multi-wafer fabrication lots of 1280x720, 12 μm pitch FPAs processed over the last two years. To assess the FPA performance, noise equivalent temperature difference (NETD) measurements were conducted at 80K, f/4.21 and using a blackbody range of 22°C to 32°C. For the MWIR band, the NETD was 27.44 mK with a 3x median NETD operability of 99.40%. For the LWIR band, the median NETD was 27.62 mK with a 3x median operability of 99.09%. Over the course of the VISTA program, HRL fabricated over 30 FPAs with similar NETDs and operabilities in excess of 99% for both bands, demonstrating the manufacturability and high uniformity of III-V superlattices. We will also present additional characterization results including blinkers, spatial stability, modulation transfer function and thermal cycles reliability.

Phononic band gap and wave propagation on polyvinylidene fluoride-based acoustic metamaterials

NASA Astrophysics Data System (ADS)

Oltulu, Oral; Simsek, Sevket; Mamedov, Amirullah M.; Ozbay, Ekmel

2016-12-01

In the present work, the acoustic band structure of a two-dimensional phononic crystal (PC) containing an organic ferroelectric (PVDF-polyvinylidene fluoride) and topological insulator (SnTe) was investigated by the plane-wave-expansion (PWE) method. Two-dimensional PC with square lattices composed of SnTe cylindrical rods embedded in the PVDF matrix is studied to find the allowed and stop bands for the waves of certain energy. Phononic band diagram ω = ω(k) for a 2D PC, in which non-dimensional frequencies ωa/2πc (c-velocity of wave) were plotted vs. the wavevector k along the Г-X-M-Г path in the square Brillouin zone shows five stop bands in the frequency range between 10 and 110 kHz. The ferroelectric properties of PVDF and the unusual properties of SnTe as a topological material give us the ability to control the wave propagation through the PC over a wide frequency range of 103-106 Hz. SnTe is a discrete component that allows conducting electricity on its surface but shows insulator properties through its bulk volume. Tin telluride is considered as an acoustic topological insulator as the extension of topological insulators into the field of "topological phononics".

Is Bare Band Description of Carrier Transport Appropriate in Pentacene?

NASA Astrophysics Data System (ADS)

Andersen, John D.; Giuggioli, Luca; Kenkre, V. M.

2002-03-01

Experiments on injected charges in pentacene single crystals reveal mobilities typical of inorganic semiconductors and temperature dependence (for T<430K) suggesting bandlike behavior.(J. H. Schon, C. Kloc, and B. Batlogg, Phys. Rev. Lett. 86, 3843 (2001)) Polaronic bands, particularly their narrowing with increasing temperature, were invoked(V. M. Kenkre, John D. Andersen, D.H. Dunlap, and C.B. Duke, Phys. Rev. Lett. 62, 1165 (1989)) in the related naphthalene problem.(L. B. Schein, C. B. Duke, and A.R. McGhie, Phys. Rev. Lett. 40, 197 (1978); L. B. Schein, W. Warta, and N. Karl, Chem. Phys. Lett. 100, 34 (1983)) Because the low temperature mobility values in pentacene suggest moderately large bandwidths, we address two questions. Does a bare wide (effectively infinite) band description work for pentacene for T<400K? And, is a bare finite band description compatible with those data? These questions are answered by modifications of a theory originally constructed for inorganic materials and a newly developed mobility theory.

Superconducting magnet for a Ku-band maser.

NASA Technical Reports Server (NTRS)

Berwin, R.; Wiebe, E.; Dachel, P.

1972-01-01

A superconducting magnet to provide a uniform magnetic field of up to 8000 G in a 1.14-cm gap for the 15.3-GHz (Ku-band) traveling wave maser is described. The magnet operates in a persistent mode in the vacuum environment of a closed-cycle helium refrigerator (4.5 K). The features of a superconducting switch, which has both leads connected to 4.5 K heat stations and thereby does not receive heat generated by the magnet charging leads, are described.

Adaptive spatial filtering using photochromic glass

NASA Astrophysics Data System (ADS)

Potton, R. J.

1999-12-01

Commercially available photochromic glasses exhibit a wide range of spectral sensitivities and darkening response times. Short wavelengths are more effective than long ones for causing darkening but at least one type of glass is effectively darkened by red light (icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/> = 633 nm) with an intensity of about 1 kW m-2. Used as adaptive spatial filters, these glasses attenuate a wavefront by an amount that depends on their recent exposure to light. One type of optical processing that can be performed with such filters is drift nulling in an interferometer excited by light of a wavelength within the sensitivity spectrum of the photochrome. This form of processing has been demonstrated by dithering the speckle pattern in a single-fibre multimode interferometer. The dither allows phase-sensitive detection techniques to be used in the detection of signal-induced phase variations in a frequency band extending from the inverse response time of the photochrome to the dither frequency.

Fine structure of the red luminescence band in undoped GaN

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

Reshchikov, M. A., E-mail: mreshchi@vcu.edu; Usikov, A.; Saint-Petersburg National Research University of Information Technologies, Mechanics and Optics, 49 Kronverkskiy Ave., 197101 Saint Petersburg

2014-01-20

Many point defects in GaN responsible for broad photoluminescence (PL) bands remain unidentified. Their presence in thick GaN layers grown by hydride vapor phase epitaxy (HVPE) detrimentally affects the material quality and may hinder the use of GaN in high-power electronic devices. One of the main PL bands in HVPE-grown GaN is the red luminescence (RL) band with a maximum at 1.8 eV. We observed the fine structure of this band with a zero-phonon line (ZPL) at 2.36 eV, which may help to identify the related defect. The shift of the ZPL with excitation intensity and the temperature-related transformation of the RLmore » band fine structure indicate that the RL band is caused by transitions from a shallow donor (at low temperature) or from the conduction band (above 50 K) to an unknown deep acceptor having an energy level 1.130 eV above the valence band.« less

S-NPP VIIRS thermal band spectral radiance performance through 18 months of operation on-orbit

NASA Astrophysics Data System (ADS)

Moeller, Chris; Tobin, Dave; Quinn, Greg

2013-09-01

The Suomi National Polar-orbiting Partnership (S-NPP) satellite, carrying the first Visible Infrared Imager Radiometer Suite (VIIRS) was successfully launched on October 28, 2011 with first light on November 21, 2011. The passive cryo-radiator cooler doors were opened on January 18, 2012 allowing the cold focal planes (S/MWIR and LWIR) to cool to the nominal operating temperature of 80K. After an early on-orbit functional checkout period, an intensive Cal/Val (ICV) phase has been underway. During the ICV, the VIIRS SDR performance for thermal emissive bands (TEB) has been under evaluation using on-orbit comparisons between VIIRS and the CrIS instrument on S-NPP, as well as VIIRS and the IASI instrument on MetOp-A. CrIS has spectral coverage of VIIRS bands M13, M15, M16, and I5 while IASI covers all VIIRS TEB. These comparisons largely verify that VIIRS TEB SDR are performing within or nearly within pre-launch requirements across the full dynamic range of these VIIRS bands, with the possible exception of warm scenes (<280 K) in band M12 as suggested by VIIRS-IASI comparisons. The comparisons with CrIS also indicate that the VIIRS Half Angle Mirror (HAM) reflectance versus scan (RVS) is well-characterized by virtue that the VIIRS-CrIS differences show little or no dependence on scan angle. The VIIRS-IASI and VIIRS-CrIS findings closely agree for bands M13, M15, and M16 for warm scenes but small offsets exist at cold scenes for M15, M16, and particularly M13. IASI comparisons also show that spectral out-of-band influence on the VIIRS SDR is <0.05 K for all bands across the full dynamic range with the exception of very cold scenes in Band M13 where the OOB influence reaches 0.10 K. TEB performance, outside of small adjustments to the SDR algorithm and supporting look-up tables, has been very stable through 18 months on-orbit. Preliminary analysis from an S-NPP underflight using a NASA ER-2 aircraft with the SHIS instrument (NIST-traceable source) confirms TEB SDR

Adaptation of signature-tagged mutagenesis to Escherichia coli K1 and the infant-rat model of invasive disease.

PubMed

Gonzalez, M D; Lichtensteiger, C A; Vimr, E R

2001-05-01

With the exception of the polysialic acid capsule (K1 antigen), little is known about other virulence factors needed for systemic infection by Escherichia coli K1, the leading cause of Gram-negative neonatal meningitis in humans. In this work, the functional genomics method of signature-tagged mutagenesis (STM) was adapted to E. coli K1 and the infant-rat model to identify non-capsule virulence genes. Validation of the method was demonstrated by the failure to recover a reconstructed acapsular mutant from bacterial pools used to systemically infect 5-day-old rats. Three new genes required for systemic disease were identified from a total of 192 mutants screened by STM (1.56% hit rate). Gut colonization, Southern blot hybridization, mixed-challenge infection, and DNA sequence analyses showed that the attenuating defects in the mutants were associated with transposon insertions in rfaL (O antigen ligase), dsbA (thiol:disulfide oxidoreductase), and a new gene, puvA (previously unidentified virulence gene A), with no known homologues. The results indicate the ability of STM to identify novel systemic virulence factors in E. coli K1.

Regulation of membrane-cytoskeletal interactions by tyrosine phosphorylation of erythrocyte band 3

PubMed Central

Ferru, Emanuela; Giger, Katie; Pantaleo, Antonella; Campanella, Estela; Grey, Jesse; Ritchie, Ken; Vono, Rosa; Low, Philip S.

2011-01-01

The cytoplasmic domain of band 3 serves as a center of erythrocyte membrane organization and constitutes the major substrate of erythrocyte tyrosine kinases. Tyrosine phosphorylation of band 3 is induced by several physiologic stimuli, including malaria parasite invasion, cell shrinkage, normal cell aging, and oxidant stress (thalassemias, sickle cell disease, glucose-6-phosphate dehydrogenase deficiency, etc). In an effort to characterize the biologic sequelae of band 3 tyrosine phosphorylation, we looked for changes in the polypeptide's function that accompany its phosphorylation. We report that tyrosine phosphorylation promotes dissociation of band 3 from the spectrin-actin skeleton as evidenced by: (1) a decrease in ankyrin affinity in direct binding studies, (2) an increase in detergent extractability of band 3 from ghosts, (3) a rise in band 3 cross-linkability by bis-sulfosuccinimidyl-suberate, (4) significant changes in erythrocyte morphology, and (5) elevation of the rate of band 3 diffusion in intact cells. Because release of band 3 from its ankyrin and adducin linkages to the cytoskeleton can facilitate changes in multiple membrane properties, tyrosine phosphorylation of band 3 is argued to enable adaptive changes in erythrocyte biology that permit the cell to respond to the above stresses. PMID:21474668

Universality for 1d Random Band Matrices: Sigma-Model Approximation

NASA Astrophysics Data System (ADS)

Shcherbina, Mariya; Shcherbina, Tatyana

2018-02-01

The paper continues the development of the rigorous supersymmetric transfer matrix approach to the random band matrices started in (J Stat Phys 164:1233-1260, 2016; Commun Math Phys 351:1009-1044, 2017). We consider random Hermitian block band matrices consisting of W× W random Gaussian blocks (parametrized by j,k \\in Λ =[1,n]^d\\cap Z^d ) with a fixed entry's variance J_{jk}=δ _{j,k}W^{-1}+β Δ _{j,k}W^{-2} , β >0 in each block. Taking the limit W→ ∞ with fixed n and β , we derive the sigma-model approximation of the second correlation function similar to Efetov's one. Then, considering the limit β , n→ ∞, we prove that in the dimension d=1 the behaviour of the sigma-model approximation in the bulk of the spectrum, as β ≫ n , is determined by the classical Wigner-Dyson statistics.

Temperature dependence of the band gap of GaAsSb epilayers

NASA Astrophysics Data System (ADS)

Lukic-Zrnic, R.; Gorman, B. P.; Cottier, R. J.; Golding, T. D.; Littler, C. L.; Norman, A. G.

2002-12-01

We have optically characterized a series of GaAs1-xSbx epilayers (0.19KK) using Fourier transform infrared spectroscopy techniques. The band gap at each temperature was determined from the photon energy dependence of the absorption coefficient and compared with theoretical predictions. From our results we have obtained the Varshni coefficients, α=(4.2±0.1)×10-4 eV/K and β=(189±9) K, which describe well not only the temperature dependence of the band gap for the entire alloy range of our samples, but also for the past experimental work of others. These values differ significantly from what we believe are the only other reported values by K. G. Merkel et al. [K. G. Merkel et al., Appl. Phys. Lett. 65, 2442 (1994)].

Indocyanine green fluorescence in second near-infrared (NIR-II) window

PubMed Central

Bhavane, Rohan; Ghaghada, Ketan B.; Vasudevan, Sanjeev A.; Kaay, Alexander; Annapragada, Ananth

2017-01-01

Indocyanine green (ICG), a FDA approved near infrared (NIR) fluorescent agent, is used in the clinic for a variety of applications including lymphangiography, intra-operative lymph node identification, tumor imaging, superficial vascular imaging, and marking ischemic tissues. These applications operate in the so-called “NIR-I” window (700–900 nm). Recently, imaging in the “NIR-II” window (1000–1700 nm) has attracted attention since, at longer wavelengths, photon absorption, and scattering effects by tissue components are reduced, making it possible to image deeper into the underlying tissue. Agents for NIR-II imaging are, however, still in pre-clinical development. In this study, we investigated ICG as a NIR-II dye. The absorbance and NIR-II fluorescence emission of ICG were measured in different media (PBS, plasma and ethanol) for a range of ICG concentrations. In vitro and in vivo testing were performed using a custom-built spectral NIR assembly to facilitate simultaneous imaging in NIR-I and NIR-II window. In vitro studies using ICG were performed using capillary tubes (as a simulation of blood vessels) embedded in Intralipid solution and tissue phantoms to evaluate depth of tissue penetration in NIR-I and NIR-II window. In vivo imaging using ICG was performed in nude mice to evaluate vascular visualization in the hind limb in the NIR-I and II windows. Contrast-to-noise ratios (CNR) were calculated for comparison of image quality in NIR-I and NIR-II window. ICG exhibited significant fluorescence emission in the NIR-II window and this emission (similar to the absorption profile) is substantially affected by the environment of the ICG molecules. In vivo imaging further confirmed the utility of ICG as a fluorescent dye in the NIR-II domain, with the CNR values being ~2 times those in the NIR-I window. The availability of an FDA approved imaging agent could accelerate the clinical translation of NIR-II imaging technology. PMID:29121078

Rain Fade Compensation Alternatives for Ka Band Communication Satellites

NASA Technical Reports Server (NTRS)

Acosta, Roberto J.

1997-01-01

Future satellite communications systems operating in Ka-band frequency band are subject to degradation produced by the troposphere which is much more severe than those found at lower frequency bands. These impairments include signal absorption by rain, clouds and gases, and amplitude scintillation's arising from refractive index irregularities. For example, rain attenuation at 20 GHz is almost three times that at 11 GHz. Although some of these impairments can be overcome by oversizing the ground station antennas and high power amplifiers, the current trend is using small (less than 20 inches apertures), low-cost ground stations (less than $1000) that can be easily deployed at user premises. As a consequence, most Ka-band systems are expected to employ different forms of fade mitigation that can be implemented relatively easily and at modest cost. The rain fade mitigation approaches are defined by three types of Ka-band communications systems - a low service rate (less than 1.5 Mb/s), a moderate service rate (1.5 to 6 Mb/s) system and a high service rate (greater than 43 Mb/s) system. The ACTS VSAT network, which includes an adaptive rain fade technique, is an example of a moderate service rate.

Cross-cultural adaptation and clinical evaluation of a Korean version of the disabilities of arm, shoulder, and hand outcome questionnaire (K-DASH).

PubMed

Lee, Joo-Yup; Lim, Jae-Young; Oh, Joo Han; Ko, Young-Mi

2008-01-01

We developed a Korean version of the disabilities of arm, shoulder, and hand outcome questionnaire (K-DASH) by performing cross-cultural adaptation and evaluated the reliability and validity of the K-DASH. The K-DASH, SF-36, and Visual Analog Scale (VAS) for pain were administered to 161 patients with arm, shoulder, and hand problems. The internal consistency of the disability/symptom scores of the K-DASH was high (Cronbach's alpha 0.94). The retest assessed 131 of the 161 patients. The intraclass correlation coefficient was 0.91. The construct validity was evaluated using the correlations between the K-DASH and the SF-36 and VAS. The physical and mental component summary scales of the SF-36 and the VAS at rest and during activity were significantly correlated with the DASH disability/symptom scores. Despite the linguistic and cultural differences, the reliability and validity of the K-DASH were just as excellent as those of the original DASH.

Amino-termini isoforms of the Slack K+ channel, regulated by alternative promoters, differentially modulate rhythmic firing and adaptation.

PubMed

Brown, Maile R; Kronengold, Jack; Gazula, Valeswara-Rao; Spilianakis, Charalampos G; Flavell, Richard A; von Hehn, Christian A A; Bhattacharjee, Arin; Kaczmarek, Leonard K

2008-11-01

The rates of activation and unitary properties of Na+-activated K+ (K(Na)) currents have been found to vary substantially in different types of neurones. One class of K(Na) channels is encoded by the Slack gene. We have now determined that alternative RNA splicing gives rise to at least five different transcripts for Slack, which produce Slack channels that differ in their predicted cytoplasmic amino-termini and in their kinetic properties. Two of these, termed Slack-A channels, contain an amino-terminus domain closely resembling that of another class of K(Na) channels encoded by the Slick gene. Neuronal expression of Slack-A channels and of the previously described Slack isoform, now called Slack-B, are driven by independent promoters. Slack-A mRNAs were enriched in the brainstem and olfactory bulb and detected at significant levels in four different brain regions. When expressed in CHO cells, Slack-A channels activate rapidly upon depolarization and, in single channel recordings in Xenopus oocytes, are characterized by multiple subconductance states with only brief transient openings to the fully open state. In contrast, Slack-B channels activate slowly over hundreds of milliseconds, with openings to the fully open state that are approximately 6-fold longer than those for Slack-A channels. In numerical simulations, neurones in which outward currents are dominated by a Slack-A-like conductance adapt very rapidly to repeated or maintained stimulation over a wide range of stimulus strengths. In contrast, Slack-B currents promote rhythmic firing during maintained stimulation, and allow adaptation rate to vary with stimulus strength. Using an antibody that recognizes all amino-termini isoforms of Slack, Slack immunoreactivity is present at locations that have no Slack-B-specific staining, including olfactory bulb glomeruli and the dendrites of hippocampal neurones, suggesting that Slack channels with alternate amino-termini such as Slack-A channels are present at

Multi-Band Received Signal Strength Fingerprinting Based Indoor Location System

NASA Astrophysics Data System (ADS)

Sertthin, Chinnapat; Fujii, Takeo; Ohtsuki, Tomoaki; Nakagawa, Masao

This paper proposes a new multi-band received signal strength (MRSS) fingerprinting based indoor location system, which employs the frequency diversity on the conventional single-band received signal strength (RSS) fingerprinting based indoor location system. In the proposed system, the impacts of frequency diversity on the enhancements of positioning accuracy are analyzed. Effectiveness of the proposed system is proved by experimental approach, which was conducted in non line-of-sight (NLOS) environment under the area of 103m2 at Yagami Campus, Keio University. WLAN access points, which simultaneously transmit dual-band signal of 2.4 and 5.2GHz, are utilized as transmitters. Likewise, a dual-band WLAN receiver is utilized as a receiver. Signal distances calculated by both Manhattan and Euclidean were classified by K-Nearest Neighbor (KNN) classifier to illustrate the performance of the proposed system. The results confirmed that Frequency diversity attributions of multi-band signal provide accuracy improvement over 50% of the conventional single-band.

Ultrafast band-gap oscillations in iron pyrite

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

Kolb, B; Kolpak, AM

2013-12-20

With its combination of favorable band gap, high absorption coefficient, material abundance, and low cost, iron pyrite, FeS2, has received a great deal of attention over the past decades as a promising material for photovoltaic applications such as solar cells and photoelectrochemical cells. Devices made from pyrite, however, exhibit open circuit voltages significantly lower than predicted, and despite a recent resurgence of interest in the material, there currently exists no widely accepted explanation for this disappointing behavior. In this paper, we show that phonons, which have been largely overlooked in previous efforts, may play a significant role. Using fully self-consistentmore » GW calculations, we demonstrate that a phonon mode related to the oscillation of the sulfur-sulfur bond distance in the pyrite structure is strongly coupled to the energy of the conduction-band minimum, leading to an ultrafast (approximate to 100 fs) oscillation in the band gap. Depending on the coherency of the phonons, we predict that this effect can cause changes of up to +/- 0.3 eV relative to the accepted FeS2 band gap at room temperature. Harnessing this effect via temperature or irradiation with infrared light could open up numerous possibilities for novel devices such as ultrafast switches and adaptive solar absorbers.« less

Preliminary experimental investigation of a complex dual-band high power microwave source.

PubMed

Zhang, Xiaoping; Li, Yangmei; Li, Zhiqiang; Zhong, Huihuang; Qian, Baoliang

2015-10-01

In order to promote the power conversion efficiency of a magnetically insulated transmission line oscillator (MILO) and obtain microwaves in dual bands, an axially extracted C-band virtual cathode oscillator (VCO) with multiple resonant cavities is introduced to partially utilize the load current of an S-band MILO. The formed novel dual-band high power microwave source called MILO and VCO is investigated with simulation and experimentally. A dual-band radiation antenna is designed to effectively radiate microwaves generated by the MILO and the VCO, respectively, while avoiding them being influenced by the microwave reflection and diffraction. The preliminary experimental results measured by the dual-band diagnostic system show that both the MILO and the VCO operate normally under repeated shots. A microwave of 2.1 GHz, 1.70 GW is generated from the MILO and a 0.37 GW microwave at frequencies of 4.1 GHz and 3.8 GHz is generated from the VCO under the condition of about 440 kV and 35 kA. Compared with a single MILO (10.6%), a MILO and VCO achieves higher total power and efficiency (13.4%) in both S and C bands, indicating that the load current of the MILO partially couples into the beam-wave interaction in the VCO and then contributes to the output microwaves. However, more works are needed regarding the spectrum purification of the VCO and promotion of the output power of both the MILO and the VCO.

2D XANES-XEOL mapping: observation of enhanced band gap emission from ZnO nanowire arrays

NASA Astrophysics Data System (ADS)

Wang, Zhiqiang; Guo, Xiaoxuan; Sham, Tsun-Kong

2014-05-01

Using 2D XANES-XEOL spectroscopy, it is found that the band gap emission of ZnO nanowire arrays is substantially enhanced i.e. that the intensity ratio between the band gap and defect emissions increases by more than an order of magnitude when the excitation energy is scanned across the O K-edge. Possible mechanisms are discussed.Using 2D XANES-XEOL spectroscopy, it is found that the band gap emission of ZnO nanowire arrays is substantially enhanced i.e. that the intensity ratio between the band gap and defect emissions increases by more than an order of magnitude when the excitation energy is scanned across the O K-edge. Possible mechanisms are discussed. Electronic supplementary information (ESI) available: XEOL spectra with different excitation energies. X-ray attenuation length vs. photon energy. Details of surface defects in ZnO NWs. The second O K-edge and Zn L-edge 2D XANES-XEOL maps. Comparison of the first and second TEY at O K-edge and Zn L-edge scans, respectively. Raman spectra of the ZnO NWs with different IBGE/IDE ratios. See DOI: 10.1039/c4nr01049c

The empirical Gaia G-band extinction coefficient

NASA Astrophysics Data System (ADS)

Danielski, C.; Babusiaux, C.; Ruiz-Dern, L.; Sartoretti, P.; Arenou, F.

2018-06-01

Context. The first Gaia data release unlocked the access to photometric information for 1.1 billion sources in the G-band. Yet, given the high level of degeneracy between extinction and spectral energy distribution for large passbands such as the Gaia G-band, a correction for the interstellar reddening is needed in order to exploit Gaia data. Aims: The purpose of this manuscript is to provide the empirical estimation of the Gaia G-band extinction coefficient kG for both the red giants and main sequence stars in order to be able to exploit the first data release DR1. Methods: We selected two samples of single stars: one for the red giants and one for the main sequence. Both samples are the result of a cross-match between Gaia DR1 and 2MASS catalogues; they consist of high-quality photometry in the G-, J- and KS-bands. These samples were complemented by temperature and metallicity information retrieved from APOGEE DR13 and LAMOST DR2 surveys, respectively. We implemented a Markov chain Monte Carlo method where we used (G - KS)0 versus Teff and (J - KS)0 versus (G - KS)0, calibration relations to estimate the extinction coefficient kG and we quantify its corresponding confidence interval via bootstrap resampling. We tested our method on samples of red giants and main sequence stars, finding consistent solutions. Results: We present here the determination of the Gaia extinction coefficient through a completely empirical method. Furthermore we provide the scientific community with a formula for measuring the extinction coefficient as a function of stellar effective temperature, the intrinsic colour (G - KS)0, and absorption.

Band nesting, massive Dirac fermions, and valley Landé and Zeeman effects in transition metal dichalcogenides: A tight-binding model

NASA Astrophysics Data System (ADS)

Bieniek, Maciej; Korkusiński, Marek; Szulakowska, Ludmiła; Potasz, Paweł; Ozfidan, Isil; Hawrylak, Paweł

2018-02-01

We present here the minimal tight-binding model for a single layer of transition metal dichalcogenides (TMDCs) MX 2(M , metal; X , chalcogen) which illuminates the physics and captures band nesting, massive Dirac fermions, and valley Landé and Zeeman magnetic field effects. TMDCs share the hexagonal lattice with graphene but their electronic bands require much more complex atomic orbitals. Using symmetry arguments, a minimal basis consisting of three metal d orbitals and three chalcogen dimer p orbitals is constructed. The tunneling matrix elements between nearest-neighbor metal and chalcogen orbitals are explicitly derived at K ,-K , and Γ points of the Brillouin zone. The nearest-neighbor tunneling matrix elements connect specific metal and sulfur orbitals yielding an effective 6 ×6 Hamiltonian giving correct composition of metal and chalcogen orbitals but not the direct gap at K points. The direct gap at K , correct masses, and conduction band minima at Q points responsible for band nesting are obtained by inclusion of next-neighbor Mo-Mo tunneling. The parameters of the next-nearest-neighbor model are successfully fitted to MX 2(M =Mo ; X =S ) density functional ab initio calculations of the highest valence and lowest conduction band dispersion along K -Γ line in the Brillouin zone. The effective two-band massive Dirac Hamiltonian for MoS2, Landé g factors, and valley Zeeman splitting are obtained.

Studying NASA's Transition to Ka-Band Communications for Low Earth Orbit

NASA Technical Reports Server (NTRS)

Chelmins, David; Reinhart, Richard; Mortensen, Dale; Welch, Bryan; Downey, Joseph; Evans, Mike

2014-01-01

As the S-band spectrum becomes crowded, future space missions will need to consider moving command and telemetry services to Ka-band. NASAs Space Communications and Navigation (SCaN) Testbed provides a software-defined radio (SDR) platform that is capable of supporting investigation of this service transition. The testbed contains two S-band SDRs and one Ka-band SDR. Over the past year, SCaN Testbed has demonstrated Ka-band communications capabilities with NASAs Tracking and Data Relay Satellite System (TDRSS) using both open- and closed-loop antenna tracking profiles. A number of technical areas need to be addressed for successful transition to Ka-band. The smaller antenna beamwidth at Ka-band increases the criticality of antenna pointing, necessitating closed loop tracking algorithms and new techniques for received power estimation. Additionally, the antenna pointing routines require enhanced knowledge of spacecraft position and attitude for initial acquisition, versus an S-band antenna. Ka-band provides a number of technical advantages for bulk data transfer. Unlike at S-band, a larger bandwidth may be available for space missions, allowing increased data rates. The potential for high rate data transfer can also be extended for direct-to-ground links through use of variable or adaptive coding and modulation. Specific examples of Ka-band research from SCaN Testbeds first year of operation will be cited, such as communications link performance with TDRSS, and the effects of truss flexure on antenna pointing.

Studying NASA's Transition to Ka-Band Communications for Low Earth Orbit

NASA Technical Reports Server (NTRS)

Chelmins, David T.; Reinhart, Richard C.; Mortensen, Dale; Welch, Bryan; Downey, Joseph; Evans, Michael

2014-01-01

As the S-band spectrum becomes crowded, future space missions will need to consider moving command and telemetry services to Ka-band. NASA's Space Communications and Navigation (SCaN) Testbed provides a software-defined radio (SDR) platform that is capable of supporting investigation of this service transition. The testbed contains two S-band SDRs and one Ka-band SDR. Over the past year, SCaN Testbed has demonstrated Ka-band communications capabilities with NASAs Tracking and Data Relay Satellite System (TDRSS) using both open- and closed-loop antenna tracking profiles. A number of technical areas need to be addressed for successful transition to Ka-band. The smaller antenna beamwidth at Ka-band increases the criticality of antenna pointing, necessitating closed loop tracking algorithms and new techniques for received power estimation. Additionally, the antenna pointing routines require enhanced knowledge of spacecraft position and attitude for initial acquisition, versus an S-band antenna. Ka-band provides a number of technical advantages for bulk data transfer. Unlike at S-band, a larger bandwidth may be available for space missions, allowing increased data rates. The potential for high rate data transfer can also be extended for direct-to-ground links through use of variable or adaptive coding and modulation. Specific examples of Ka-band research from SCaN Testbeds first year of operation will be cited, such as communications link performance with TDRSS, and the effects of truss flexure on antenna pointing.

A W-band sixth-harmonic magnetron-type slotted peniotron

NASA Astrophysics Data System (ADS)

Hu, Biao; Li, Jiayin; Wu, Xinhui; Li, Tianming; Li, Hao; Wang, Haiyang; Zhao, Xiaoyun

2013-04-01

This paper has numerically investigated operating characteristics of a w-band six-harmonic magnetron-type slotted peniotron with 7 vanes. With the new structure design, a high efficiency of 40% w-band 30 kW medium power microwave source has been achieved and the mode competition can be somewhat suppressed. The main advantage of such a peniotron, based on a permanent magnet, is that it can have much more compact size and lower cost, and its operation gap can be greatly reduced.

The temperature-dependency of the optical band gap of ZnO measured by electron energy-loss spectroscopy in a scanning transmission electron microscope

NASA Astrophysics Data System (ADS)

Granerød, Cecilie S.; Galeckas, Augustinas; Johansen, Klaus Magnus; Vines, Lasse; Prytz, Øystein

2018-04-01

The optical band gap of ZnO has been measured as a function of temperature using Electron Energy-Loss Spectroscopy (EELS) in a (Scanning) Transmission Electron Microscope ((S)TEM) from approximately 100 K up towards 1000 K. The band gap narrowing shows a close to linear dependency for temperatures above 250 K and is accurately described by Varshni, Bose-Einstein, Pässler and Manoogian-Woolley models. Additionally, the measured band gap is compared with both optical absorption measurements and photoluminescence data. STEM-EELS is here shown to be a viable technique to measure optical band gaps at elevated temperatures, with an available temperature range up to 1500 K and the benefit of superior spatial resolution.

A novel theoretical model for the temperature dependence of band gap energy in semiconductors

NASA Astrophysics Data System (ADS)

Geng, Peiji; Li, Weiguo; Zhang, Xianhe; Zhang, Xuyao; Deng, Yong; Kou, Haibo

2017-10-01

We report a novel theoretical model without any fitting parameters for the temperature dependence of band gap energy in semiconductors. This model relates the band gap energy at the elevated temperature to that at the arbitrary reference temperature. As examples, the band gap energies of Si, Ge, AlN, GaN, InP, InAs, ZnO, ZnS, ZnSe and GaAs at temperatures below 400 K are calculated and are in good agreement with the experimental results. Meanwhile, the band gap energies at high temperatures (T  >  400 K) are predicted, which are greater than the experimental results, and the reasonable analysis is carried out as well. Under low temperatures, the effect of lattice expansion on the band gap energy is very small, but it has much influence on the band gap energy at high temperatures. Therefore, it is necessary to consider the effect of lattice expansion at high temperatures, and the method considering the effect of lattice expansion has also been given. The model has distinct advantages compared with the widely quoted Varshni’s semi-empirical equation from the aspect of modeling, physical meaning and application. The study provides a convenient method to determine the band gap energy under different temperatures.

Electronic band structure and Shubnikov-de Haas effect in two-dimensional semimetallic InAs/GaSb nanostructure superlattice

NASA Astrophysics Data System (ADS)

Boutramine, Abderrazak; Nafidi, Abdelhakim; Barkissy, Driss; El-Frikhe, Es-Said; Charifi, Hicham; Elanique, Abdellatif; Chaib, Hassan

2016-02-01

We have investigated the band structure E( d = d 1 + d 2), E( k z) and E( k p), respectively, as a function of the SL period, d, in the growth direction and in plan of InAs( d 1 = 160 Å)/GaSb( d 2 = 105 Å) type II superlattice, performed in the envelope function formalism with the valence band offset, Λ, of 510 meV at 4.2 K. For the ratio d 1/ d 2 = 1.52, d and Λ dependence of the SL energy band gap show that the semiconductor-to-semimetal transition takes place at d c = 173 Å and Λ c = 463 meV. Therefore, this sample is semimetallic. The position of the Fermi level, E F = 500.2 meV, indicates n type conductivity. The spectra of energy, E( k z, k p), show a negative band gap of -48.3 meV. The cutoff wavelength | λ c| = 25.7 µm indicates that this sample can be used as a far-infrared detector. Further, we have interpreted the minima of the magnetoresistance oscillations, Shubnikov-de Haas effect, observed by D. M. Symons et al.

Diluted magnetic semiconductors with narrow band gaps

NASA Astrophysics Data System (ADS)

Gu, Bo; Maekawa, Sadamichi

2016-10-01

We propose a method to realize diluted magnetic semiconductors (DMSs) with p - and n -type carriers by choosing host semiconductors with a narrow band gap. By employing a combination of the density function theory and quantum Monte Carlo simulation, we demonstrate such semiconductors using Mn-doped BaZn2As2 , which has a band gap of 0.2 eV. In addition, we found a nontoxic DMS Mn-doped BaZn2Sb2 , of which the Curie temperature Tc is predicted to be higher than that of Mn-doped BaZn2As2 , the Tc of which was up to 230 K in a recent experiment.

The hierarchically organized splitting of chromosome bands into sub-bands analyzed by multicolor banding (MCB).

PubMed

Lehrer, H; Weise, A; Michel, S; Starke, H; Mrasek, K; Heller, A; Kuechler, A; Claussen, U; Liehr, T

2004-01-01

To clarify the nature of chromosome sub-bands in more detail, the multicolor banding (MCB) probe-set for chromosome 5 was hybridized to normal metaphase spreads of GTG band levels at approximately 850, approximately 550, approximately 400 and approximately 300. It could be observed that as the chromosomes became shorter, more of the initial 39 MCB pseudo-colors disappeared, ending with 18 MCB pseudo-colored bands at the approximately 300-band level. The hierarchically organized splitting of bands into sub-bands was analyzed by comparing the disappearance or appearance of pseudo-color bands of the four different band levels. The regions to split first are telomere-near, centromere-near and in 5q23-->q31, followed by 5p15, 5p14, and all GTG dark bands in 5q apart from 5q12 and 5q32 and finalized by sub-band building in 5p15.2, 5q21.2-->q21.3, 5q23.1 and 5q34. The direction of band splitting towards the centromere or the telomere could be assigned to each band separately. Pseudo-colors assigned to GTG-light bands were resistant to band splitting. These observations are in concordance with the recently proposed concept of chromosome region-specific protein swelling. Copyright 2003 S. Karger AG, Basel

Dendrometer bands made easy: Using modified cable ties to measure incremental growth of trees1

PubMed Central

Anemaet, Evelyn R.; Middleton, Beth A.

2013-01-01

• Premise of the study: Dendrometer bands are a useful way to make sequential repeated measurements of tree growth, but traditional dendrometer bands can be expensive, time consuming, and difficult to construct in the field. An alternative to the traditional method of band construction is to adapt commercially available materials. This paper describes how to construct and install dendrometer bands using smooth-edged, stainless steel, cable tie banding and attachable rollerball heads. • Methods and Results: As a performance comparison, both traditional and cable tie dendrometer bands were installed on baldcypress trees at the National Wetlands Research Center in Lafayette, Louisiana, by both an experienced and a novice worker. Band installation times were recorded, and growth of the trees as estimated by the two band types was measured after approximately one year, demonstrating equivalence of the two methods. • Conclusions: This efficient approach to dendrometer band construction can help advance the knowledge of long-term tree growth in ecological studies. PMID:25202589

A K-Band Low-Power Phase Shifter Based on Injection Locked Oscillator in 0.13 μm CMOS Technology

NASA Astrophysics Data System (ADS)

Qiu, Qi-Lin; Yu, Xiao-Peng; Sui, Wen-Quan

2017-11-01

In this paper, the design challenges of the injection-locked oscillator (ILO)-based phase shifter are reviewed and analyzed. The key design considerations such as the operating frequency, locking range, and linearity of the phase shifters are analysed in detail. It is possible to optimize the phase shifter in certain parameters such as ultra-low power while meeting the requirements of a certain system. As a design example, a K-band phase shifter is implemented using a commercial 0.13 μm CMOS technology, where a conventional LC tank based topology is implemented but optimised with a good balance among power consumption, working range, sensitivity, and silicon area, etc. Measurement results show that the proposed phase shift is able to work at 22-23.4 GHz with a range of 180∘ while consuming 3.14 mW from a 1.2 V supply voltage.

37 NEW T-TYPE BROWN DWARFS IN THE CANADA-FRANCE BROWN DWARFS SURVEY

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

Albert, Loic; Artigau, Etienne; Delorme, Philippe

2011-06-15

The Canada-France Brown Dwarfs Survey is an i'- and z'-band survey realized with MegaCam at the Canada-France-Hawaii Telescope that covers a surface area of 780 deg{sup 2}. Image analysis is now completed while J-band follow-up campaigns are {approx}90% done. The survey identified about 70 T dwarf candidates, of which 43 now have near-infrared spectra obtained with NIRI and GNIRS at Gemini and ISAAC at the Very Large Telescope. Six of these were previously published and we present here the 37 new discoveries, all T dwarfs. They range from T0 to T8.5 with four being of type T7 or later. Bothmore » newly identified T8 dwarfs are possibly high log (g) massive brown dwarfs of thin disk age. One T4.5 dwarf shows signs of sub-metallicity. We present proper motions and near-infrared photometry, and discuss about the most peculiar/interesting objects in some details.« less

Microscopy mineral image enhancement based on improved adaptive threshold in nonsubsampled shearlet transform domain

NASA Astrophysics Data System (ADS)

Li, Liangliang; Si, Yujuan; Jia, Zhenhong

2018-03-01

In this paper, a novel microscopy mineral image enhancement method based on adaptive threshold in non-subsampled shearlet transform (NSST) domain is proposed. First, the image is decomposed into one low-frequency sub-band and several high-frequency sub-bands. Second, the gamma correction is applied to process the low-frequency sub-band coefficients, and the improved adaptive threshold is adopted to suppress the noise of the high-frequency sub-bands coefficients. Third, the processed coefficients are reconstructed with the inverse NSST. Finally, the unsharp filter is used to enhance the details of the reconstructed image. Experimental results on various microscopy mineral images demonstrated that the proposed approach has a better enhancement effect in terms of objective metric and subjective metric.

Landsat-7 ETM+: 12 years On-Orbit Reflective-Band Radiometric Performance

NASA Technical Reports Server (NTRS)

Markham, Brian L.; Haque, O.; Barsi, Julia A.; Micijevic, E.; Helder, Dennis H.; Thome, Kurtis J.; Aaron, David; Czapla-Myers, J.

2011-01-01

The Landsat-7 ETM+ sensor has been operating on orbit for more than 12 years and characterizations of its performance have been ongoing over this period. In general, the radiometric performance of the instrument has been remarkably stable: (1) Noise performance has degraded by 2% or less overall, with a few detectors displaying step changes in noise of 2% or less, (2) Coherent noise frequencies and magnitudes have generally been stable, though the within-scan amplitude variation of the 20kHz noise in bands 1 and 8 disappeared with the failure of the scan line corrector and a new similar frequency noise (now about 18kHz) has appeared in two detectors in band 5 and increased in magnitude with time, (3) Bias stability has been better than 0.25 DN out of a normal value of 15 DN in high gain, (4) Relative gains, the differences in response between the detectors in the band, have generally changed by 0.1% or less over the mission, with the exception of a few detectors with a step response change of 1% or less and (5) Gain stability averaged across all detectors in a band, which is related to the stability of the absolute calibration, has been more stable than the techniques used to measure it. Due to the inability to confirm changes in the gain (beyond a few detectors that have been corrected back to the band average), ETM+ reflective band data continues to be calibrated with the pre-launch measured gains. In the worst case some bands may have changed as much as 2% in uncompensated absolute calibration over the 12 years.

Landsat-7 ETM+: 12 years on-orbit reflective-band radiometric performance

USGS Publications Warehouse

Markham, B.L.; Haque, M.O.; Barsi, J.A.; Micijevic, E.; Helder, D.L.; Thome, K.J.; Aaron, David; Czapla-Myers, J. S.

2012-01-01

The Landsat-7 ETM+ sensor has been operating on orbit for more than 12 years, and characterizations of its performance have been ongoing over this period. In general, the radiometric performance of the instrument has been remarkably stable: 1) noise performance has degraded by 2% or less overall, with a few detectors displaying step changes in noise of 2% or less; 2) coherent noise frequencies and magnitudes have generally been stable, though the within-scan amplitude variation of the 20 kHz noise in bands 1 and 8 disappeared with the failure of the scan line corrector and a new similar frequency noise (now about 18 kHz) has appeared in two detectors in band 5 and increased in magnitude with time; 3) bias stability has been better than 0.25 DN out of a normal value of 15 DN in high gain; 4) relative gains, the differences in response between the detectors in the band, have generally changed by 0.1% or less over the mission, with the exception of a few detectors with a step response change of 1% or less; and 5) gain stability averaged across all detectors in a band, which is related to the stability of the absolute calibration, has been more stable than the techniques used to measure it. Due to the inability to confirm changes in the gain (beyond a few detectors that have been corrected back to the band average), ETM+ reflective band data continues to be calibrated with the prelaunch measured gains. In the worst case, some bands may have changed as much as 2% in uncompensated absolute calibration over the 12 years.

K-band single-chip electron spin resonance detector.

PubMed

Anders, Jens; Angerhofer, Alexander; Boero, Giovanni

2012-04-01

We report on the design, fabrication, and characterization of an integrated detector for electron spin resonance spectroscopy operating at 27 GHz. The microsystem, consisting of an LC-oscillator and a frequency division module, is integrated onto a single silicon chip using a conventional complementary metal-oxide-semiconductor technology. The achieved room temperature spin sensitivity is about 10(8)spins/G Hz(1/2), with a sensitive volume of about (100 μm)(3). Operation at 77K is also demonstrated. Copyright © 2012 Elsevier Inc. All rights reserved.

The demodulated band transform

PubMed Central

Kovach, Christopher K.; Gander, Phillip E.

2016-01-01

Background Windowed Fourier decompositions (WFD) are widely used in measuring stationary and non-stationary spectral phenomena and in describing pairwise relationships among multiple signals. Although a variety of WFDs see frequent application in electrophysiological research, including the short-time Fourier transform, continuous wavelets, band-pass filtering and multitaper-based approaches, each carries certain drawbacks related to computational efficiency and spectral leakage. This work surveys the advantages of a WFD not previously applied in electrophysiological settings. New Methods A computationally efficient form of complex demodulation, the demodulated band transform (DBT), is described. Results DBT is shown to provide an efficient approach to spectral estimation with minimal susceptibility to spectral leakage. In addition, it lends itself well to adaptive filtering of non-stationary narrowband noise. Comparison with existing methods A detailed comparison with alternative WFDs is offered, with an emphasis on the relationship between DBT and Thomson's multitaper. DBT is shown to perform favorably in combining computational efficiency with minimal introduction of spectral leakage. Conclusion DBT is ideally suited to efficient estimation of both stationary and non-stationary spectral and cross-spectral statistics with minimal susceptibility to spectral leakage. These qualities are broadly desirable in many settings. PMID:26711370

Preliminary experimental investigation of a complex dual-band high power microwave source

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

Zhang, Xiaoping, E-mail: zhangxiaoping@nudt.edu.cn; Li, Yangmei; Li, Zhiqiang

2015-10-15

In order to promote the power conversion efficiency of a magnetically insulated transmission line oscillator (MILO) and obtain microwaves in dual bands, an axially extracted C-band virtual cathode oscillator (VCO) with multiple resonant cavities is introduced to partially utilize the load current of an S-band MILO. The formed novel dual-band high power microwave source called MILO and VCO is investigated with simulation and experimentally. A dual-band radiation antenna is designed to effectively radiate microwaves generated by the MILO and the VCO, respectively, while avoiding them being influenced by the microwave reflection and diffraction. The preliminary experimental results measured by themore » dual-band diagnostic system show that both the MILO and the VCO operate normally under repeated shots. A microwave of 2.1 GHz, 1.70 GW is generated from the MILO and a 0.37 GW microwave at frequencies of 4.1 GHz and 3.8 GHz is generated from the VCO under the condition of about 440 kV and 35 kA. Compared with a single MILO (10.6%), a MILO and VCO achieves higher total power and efficiency (13.4%) in both S and C bands, indicating that the load current of the MILO partially couples into the beam-wave interaction in the VCO and then contributes to the output microwaves. However, more works are needed regarding the spectrum purification of the VCO and promotion of the output power of both the MILO and the VCO.« less

Evanescent waves and deaf bands in sonic crystals

NASA Astrophysics Data System (ADS)

Romero-García, V.; Garcia-Raffi, L. M.; Sánchez-Pérez, J. V.

2011-12-01

The properties of sonic crystals (SC) are theoretically investigated in this work by solving the inverse problem k(ω) using the extended plane wave expansion (EPWE). The solution of the resulting eigenvalue problem gives the complex band structure which takes into account both the propagating and the evanescent modes. In this work we show the complete mathematical formulation of the EPWE for SC and the supercell approximation for its use in both a complete SC and a SC with defects. As an example we show a novel interpretation of the deaf bands in a complete SC in good agreement with multiple scattering simulations.

Multi-band asymmetric acoustic transmission in a bended waveguide with multiple mechanisms

NASA Astrophysics Data System (ADS)

Huang, Yu-lei; Sun, Hong-xiang; Xia, Jian-ping; Yuan, Shou-qi; Ding, Xin-lei

2016-07-01

We report the realization of a multi-band device of the asymmetric acoustic transmission by placing a phononic crystal inside a bended waveguide immersed in water, as determined both experimentally and numerically. The asymmetric acoustic transmission exists in three frequency bands below 500 kHz induced by multiple mechanisms. Besides the band gap of the phononic crystal, we also introduce the deaf mode and interaction between the phononic crystal and waveguide. More importantly, this asymmetric transmission can be systematically controlled by mechanically rotating the square rods of the phononic crystal. The device has the advantages of multiple band, broader bandwidth, and adjustable property, showing promising applications in ultrasonic devices.

Effect of band filling on anomalous Hall conductivity and magneto-crystalline anisotropy in NiFe epitaxial thin films

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

Shi, Zhong; Jiang, Hang-Yu; Zhou, Shi-Ming, E-mail: shiming@tongji.edu.cn

2016-01-15

The anomalous Hall effect (AHE) and magneto-crystalline anisotropy (MCA) are investigated in epitaxial Ni{sub x}Fe{sub 1−x} thin films grown on MgO (001) substrates. The scattering independent term b of anomalous Hall conductivity shows obvious correlation with cubic magneto-crystalline anisotropy K{sub 1}. When nickel content x decreasing, both b and K{sub 1} vary continuously from negative to positive, changing sign at about x = 0.85. Ab initio calculations indicate Ni{sub x}Fe{sub 1−x} has more abundant band structures than pure Ni due to the tuning of valence electrons (band fillings), resulting in the increased b and K{sub 1}. This remarkable correlation betweenmore » b and K{sub 1} can be attributed to the effect of band filling near the Fermi surface.« less

Enhanced Ultra-Wideband (UWB) Circular Monopole Antenna with Electromagnetic Band Gap (EBG) Surface and Director

DTIC Science & Technology

2014-08-01

Enhanced Ultra-Wideband (UWB) Circular Monopole Antenna with Electromagnetic Band Gap (EBG) Surface and Director by Amir I Zaghloul, Youn M... Antenna with Electromagnetic Band Gap (EBG) Surface and Director Amir I Zaghloul, Youn M Lee, Gregory A Mitchell, and Theodore K Anthony...DATES COVERED (From - To) 4. TITLE AND SUBTITLE Enhanced Ultra-Wideband (UWB) Circular Monopole Antenna with Electromagnetic Band Gap (EBG

Laser-excited luminescence and absorption study of mixed valence for K 2Pt(CN) 4—K 2Pt(CN) 6 crystals

NASA Astrophysics Data System (ADS)

Kasi Viswanath, A.; Smith, Wayne L.; Patterson, H.

1982-04-01

Crystals of K 2Pt(CN) 6 doped with Pt(CN) 2-4 show an absorption band at 337 nm which is assigned as a mixed-valence (MV) transition from Pt (II) to Pt(IV). From a Hush model analysis, the absorption band is interpreted to be class II in the Day—Robin scheme. When the MV band is laser excited at 337 nm, emmision is observed from Pt(CN) 2-4 clusters.

High resolution FTIR spectroscopy of the ν7 band of CD3CCH

NASA Astrophysics Data System (ADS)

Pal, Ayan Kumar; Kshirsagar, R. J.

2018-03-01

The high-resolution Fourier transform spectrum of propyne-d3 (CD3CCH) at room temperature has been recorded in the region of the ν7 band (950-1200 cm-1) at an apodized resolution of 0.004 cm-1. About 2400 lines consisting of a total of 25 sub-bands ranging from KΔK = -13 to 12 have been assigned in the ν7 band of CD3CCH. In the fitting analysis, the ν4 = 1 state to which transitions have not been identified in the experimental spectrum included as a "shadow" state. The data have been analyzed taking into account of the strong x-y Coriolis interaction of the ν7 = 1 state with the ν4 = 1 state. l-type interactions between the ± l components of the ν7 = 1 state, and a weak k-type doubling interaction between ν7 = 1 and ν4 = 1 states have been included in the analysis. The vibration-rotation transitions for K ≥ 8 show fairly large amount of deviation and most likely interacted by other nearby states. The transitions upto K = 7 and Jmax = 61 could be fitted with a standard deviation of 0.0007 cm-1.

Cross-cultural adaptation and psychometric properties of the Korean Scale for Internet Addiction (K-Scale) in Japanese high school students.

PubMed

Mak, Kwok-Kei; Nam, JeeEun Karin; Kim, Dongil; Aum, Narae; Choi, Jung-Seok; Cheng, Cecilia; Ko, Huei-Chen; Watanabe, Hiroko

2017-03-01

The Korean Scale for Internet Addiction (K-Scale) was developed in Korea for assessing addictive internet behaviors. This study aims to adopt K-Scale and examine its psychometric properties in Japanese adolescents. In 2014, 589 (36.0% boys) high school students (Grade 10-12) from Japan completed a survey, including items of Japanese versions of K-Scale and Smartphone Scale for Smartphone Addiction (S-Scale). Model fit indices of the original four-factor structure, three-factor structure obtained from exploratory factor analysis, and improved two-factor structure of K-Scale were computed using confirmatory factor analysis, with internal reliability of included items reported. The convergent validity of K-Scale was tested against self-rated internet addiction, and S-Scale using multiple regression models. The results showed that a second-order two-factor 13-item structure was the most parsimonious model (NFI=0.919, NNFI=0.935, CFI=0.949, and RMSEA=0.05) with good internal reliability (Cronbach's alpha=0.87). The two factors revealed were "Disturbance of Adaptation and Life Orientation" and "Withdrawal and Tolerance". Moreover, the correlation between internet user classifications defined by K-Scale and self-rating was significant. K-Scale total score was significantly and positively associated with S-Scale total (adjusted R 2 =0.440) and subscale scores (adjusted R 2 =0.439). In conclusion, K-Scale is a valid and reliable assessment scale of internet addiction for Japanese high school students after modifications. Copyright © 2017. Published by Elsevier B.V.

Quasiparticle band gap in the topological insulator Bi2Te3

NASA Astrophysics Data System (ADS)

Nechaev, I. A.; Chulkov, E. V.

2013-10-01

We present a theoretical study of dispersion of states that form the bulk band-gap edges in the three-dimensional topological insulator Bi2Te3. Within density functional theory, we analyze the effect of atomic positions varied within the error range of the available experimental data and approximation chosen for the exchange-correlation functional on the bulk band gap and k-space location of valence- and conduction-band extrema. For each set of the positions with different exchange-correlation functionals, we show how many-body corrections calculated within a one-shot GW approach affect the mentioned characteristics of electronic structure of Bi2Te3. We thus also illustrate to what degree the one-shot GW results are sensitive to the reference one-particle band structure in the case of bismuth telluride. We found that for this topological insulator the GW corrections enlarge the fundamental band gap and for certain atomic positions and reference band structure bring its value in close agreement with experiment.

The broad band X-ray spectrum of SN 1978k and two other luminous X-ray sources in the spiral galaxy NGC 1313

NASA Technical Reports Server (NTRS)

Petre, Robert; Okada, Kyoko; Mihara, Tatehiro; Makishima, Kazuo; Colbert, Edward J. M.

1994-01-01

We present preliminary results of our analysis of the Advanced Satellite for Cosmology and Astrophysics (ASCA) PV phase observation of the nearby spiral galaxy NGC 1313. ASCA cleanly resolves the three previously known luminous sources, one of which is the very luminous supernova, SN 1978k. The spectrum of SN 1978k is described by either a power law with a photon index gamma approximately 2.2 or a thermal model with temperature kT approximately 3.0 keV and abundances Z approximately 0.2 Z(sun). There is no evidence for strong line emission from it or from the other two sources. The spectrum of SN 1978k arises either in shocked gas in extreme departure from ionization equilibrium or from synchrotron processes associated with a newborn pulsar. A second source, near the galactic center, is well-fit by a power-law with a photon index of approximately 1.8. It is possibly an active nucleus-like source, but physically displaced from the optical nucleus of the galaxy. The spectrum of the third source, located 8 kpc south of the nucleus, along with the absence of an optical counterpart, suggests that it is a low mass X-ray binary; but its high X-ray luminosity clouds this interpretation. This observation demonstrates the ability of ASCA to perform effective broad band spectroscopic measurements of sources at a 2-10 keV flux level of 5 x 10(exp -13) erg cm(exp -2) s(exp -1).

Temperature dependence of intensities of the 8-12 micron bands of CFCl3

NASA Technical Reports Server (NTRS)

Nanes, R.; Silvaggio, P. M.; Boese, R. W.

1980-01-01

The absolute intensities of the 8-12 micron bands from Freon 11 (CFCl3) were measured at temperatures of 294 and 216 K. Intensities of the bands centered at 798, 847, 934, and 1082 per cm are all observed to depend on temperature. The temperature dependence for the 847 and 1082 per cm fundamental regions is attributed to underlying hot bands; for the nu2 + nu5 combination band (934 per cm), the observed temperature dependence is in close agreement with theoretical prediction. The implication of these results on atmospheric IR remote-sensing is briefly discussed.

A Simple Band for Gastric Banding.

PubMed

Broadbent

1993-08-01

The author has noted that flexible gastric bands have occasionally stenosed the gastric stoma or allowed it to dilate. A band was developed using a soft outer silicone rubber tube over a holding mechanism made out of a nylon cable tie passed within the silicone tube. This simple, easily applied band is rigid, resisting scar contracture and dilatation.

Measurement accuracies in band-limited extrapolation

NASA Technical Reports Server (NTRS)

Kritikos, H. N.

1982-01-01

The problem of numerical instability associated with extrapolation algorithms is addressed. An attempt is made to estimate the bounds for the acceptable errors and to place a ceiling on the measurement accuracy and computational accuracy needed for the extrapolation. It is shown that in band limited (or visible angle limited) extrapolation the larger effective aperture L' that can be realized from a finite aperture L by over sampling is a function of the accuracy of measurements. It is shown that for sampling in the interval L/b absolute value of xL, b1 the signal must be known within an error e sub N given by e sub N squared approximately = 1/4(2kL') cubed (e/8b L/L')(2kL') where L is the physical aperture, L' is the extrapolated aperture, and k = 2pi lambda.

Designing an Algorithm for Cancerous Tissue Segmentation Using Adaptive K-means Cluttering and Discrete Wavelet Transform.

PubMed

Rezaee, Kh; Haddadnia, J

2013-09-01

Breast cancer is currently one of the leading causes of death among women worldwide. The diagnosis and separation of cancerous tumors in mammographic images require accuracy, experience and time, and it has always posed itself as a major challenge to the radiologists and physicians. This paper proposes a new algorithm which draws on discrete wavelet transform and adaptive K-means techniques to transmute the medical images implement the tumor estimation and detect breast cancer tumors in mammograms in early stages. It also allows the rapid processing of the input data. In the first step, after designing a filter, the discrete wavelet transform is applied to the input images and the approximate coefficients of scaling components are constructed. Then, the different parts of image are classified in continuous spectrum. In the next step, by using adaptive K-means algorithm for initializing and smart choice of clusters' number, the appropriate threshold is selected. Finally, the suspicious cancerous mass is separated by implementing the image processing techniques. We Received 120 mammographic images in LJPEG format, which had been scanned in Gray-Scale with 50 microns size, 3% noise and 20% INU from clinical data taken from two medical databases (mini-MIAS and DDSM). The proposed algorithm detected tumors at an acceptable level with an average accuracy of 92.32% and sensitivity of 90.24%. Also, the Kappa coefficient was approximately 0.85, which proved the suitable reliability of the system performance. The exact positioning of the cancerous tumors allows the radiologist to determine the stage of disease progression and suggest an appropriate treatment in accordance with the tumor growth. The low PPV and high NPV of the system is a warranty of the system and both clinical specialists and patients can trust its output.

Designing an Algorithm for Cancerous Tissue Segmentation Using Adaptive K-means Cluttering and Discrete Wavelet Transform

PubMed Central

Rezaee, Kh.; Haddadnia, J.

2013-01-01

Background: Breast cancer is currently one of the leading causes of death among women worldwide. The diagnosis and separation of cancerous tumors in mammographic images require accuracy, experience and time, and it has always posed itself as a major challenge to the radiologists and physicians. Objective: This paper proposes a new algorithm which draws on discrete wavelet transform and adaptive K-means techniques to transmute the medical images implement the tumor estimation and detect breast cancer tumors in mammograms in early stages. It also allows the rapid processing of the input data. Method: In the first step, after designing a filter, the discrete wavelet transform is applied to the input images and the approximate coefficients of scaling components are constructed. Then, the different parts of image are classified in continuous spectrum. In the next step, by using adaptive K-means algorithm for initializing and smart choice of clusters’ number, the appropriate threshold is selected. Finally, the suspicious cancerous mass is separated by implementing the image processing techniques. Results: We Received 120 mammographic images in LJPEG format, which had been scanned in Gray-Scale with 50 microns size, 3% noise and 20% INU from clinical data taken from two medical databases (mini-MIAS and DDSM). The proposed algorithm detected tumors at an acceptable level with an average accuracy of 92.32% and sensitivity of 90.24%. Also, the Kappa coefficient was approximately 0.85, which proved the suitable reliability of the system performance. Conclusion: The exact positioning of the cancerous tumors allows the radiologist to determine the stage of disease progression and suggest an appropriate treatment in accordance with the tumor growth. The low PPV and high NPV of the system is a warranty of the system and both clinical specialists and patients can trust its output. PMID:25505753

FPGA/NIOS Implementation of an Adaptive FIR Filter Using Linear Prediction to Reduce Narrow-Band RFI for Radio Detection of Cosmic Rays

NASA Astrophysics Data System (ADS)

Szadkowski, Zbigniew; Fraenkel, E. D.; van den Berg, Ad M.

2013-10-01

We present the FPGA/NIOS implementation of an adaptive finite impulse response (FIR) filter based on linear prediction to suppress radio frequency interference (RFI). This technique will be used for experiments that observe coherent radio emission from extensive air showers induced by ultra-high-energy cosmic rays. These experiments are designed to make a detailed study of the development of the electromagnetic part of air showers. Therefore, these radio signals provide information that is complementary to that obtained by water-Cherenkov detectors which are predominantly sensitive to the particle content of an air shower at ground. The radio signals from air showers are caused by the coherent emission due to geomagnetic and charge-excess processes. These emissions can be observed in the frequency band between 10-100 MHz. However, this frequency range is significantly contaminated by narrow-band RFI and other human-made distortions. A FIR filter implemented in the FPGA logic segment of the front-end electronics of a radio sensor significantly improves the signal-to-noise ratio. In this paper we discuss an adaptive filter which is based on linear prediction. The coefficients for the linear predictor (LP) are dynamically refreshed and calculated in the embedded NIOS processor, which is implemented in the same FPGA chip. The Levinson recursion, used to obtain the filter coefficients, is also implemented in the NIOS and is partially supported by direct multiplication in the DSP blocks of the logic FPGA segment. Tests confirm that the LP can be an alternative to other methods involving multiple time-to-frequency domain conversions using an FFT procedure. These multiple conversions draw heavily on the power consumption of the FPGA and are avoided by the linear prediction approach. Minimization of the power consumption is an important issue because the final system will be powered by solar panels. The FIR filter has been successfully tested in the Altera development kits

Reliability of flipper-banded penguins as indicators of climate change.

PubMed

Saraux, Claire; Le Bohec, Céline; Durant, Joël M; Viblanc, Vincent A; Gauthier-Clerc, Michel; Beaune, David; Park, Young-Hyang; Yoccoz, Nigel G; Stenseth, Nils C; Le Maho, Yvon

2011-01-13

In 2007, the Intergovernmental Panel on Climate Change highlighted an urgent need to assess the responses of marine ecosystems to climate change. Because they lie in a high-latitude region, the Southern Ocean ecosystems are expected to be strongly affected by global warming. Using top predators of this highly productive ocean (such as penguins) as integrative indicators may help us assess the impacts of climate change on marine ecosystems. Yet most available information on penguin population dynamics is based on the controversial use of flipper banding. Although some reports have found the effects of flipper bands to be deleterious, some short-term (one-year) studies have concluded otherwise, resulting in the continuation of extensive banding schemes and the use of data sets thus collected to predict climate impact on natural populations. Here we show that banding of free-ranging king penguins (Aptenodytes patagonicus) impairs both survival and reproduction, ultimately affecting population growth rate. Over the course of a 10-year longitudinal study, banded birds produced 41% [corrected] fewer chicks and had a survival rate 16 percentage points [corrected] lower than non-banded birds, demonstrating a massive long-term impact of banding and thus refuting the assumption that birds will ultimately adapt to being banded. Indeed, banded birds still arrived later for breeding at the study site and had longer foraging trips even after 10 years. One of our major findings is that responses of flipper-banded penguins to climate variability (that is, changes in sea surface temperature and in the Southern Oscillation index) differ from those of non-banded birds. We show that only long-term investigations may allow an evaluation of the impact of flipper bands and that every major life-history trait can be affected, calling into question the banding schemes still going on. In addition, our understanding of the effects of climate change on marine ecosystems based on flipper-band

Integrated amateur band and ultra-wide band monopole antenna with multiple band-notched

NASA Astrophysics Data System (ADS)

Srivastava, Kunal; Kumar, Ashwani; Kanaujia, B. K.; Dwari, Santanu

2018-05-01

This paper presents the integrated amateur band and ultra-wide band (UWB) monopole antenna with integrated multiple band-notched characteristics. It is designed for avoiding the potential interference of frequencies 3.99 GHz (3.83 GHz-4.34 GHz), 4.86 GHz (4.48 GHz-5.63 GHz), 7.20 GHz (6.10 GHz-7.55 GHz) and 8.0 GHz (7.62 GHz-8.47 GHz) with VSWR 4.9, 11.5, 6.4 and 5.3, respectively. Equivalent parallel resonant circuits have been presented for each band-notched frequencies of the antenna. Antenna operates in amateur band 1.2 GHz (1.05 GHz-1.3 GHz) and UWB band from 3.2 GHz-13.9 GHz. Different substrates are used to verify the working of the proposed antenna. Integrated GSM band from 0.6 GHz to 1.8 GHz can also be achieved by changing the radius of the radiating patch. Antenna gain varied from 1.4 dBi to 9.8 dBi. Measured results are presented to validate the antenna performances.

A Q-band two-beam cryogenic receiver for the Tianma Radio Telescope

NASA Astrophysics Data System (ADS)

Zhong, Wei-Ye; Dong, Jian; Gou, Wei; Yu, Lin-Feng; Wang, Jin-Qing; Xia, Bo; Jiang, Wu; Liu, Cong; Zhang, Hui; Shi, Jun; Yin, Xiao-Xing; Shi, Sheng-Cai; Liu, Qing-Hui; Shen, Zhi-Qiang

2018-04-01

A Q-band two-beam cryogenic receiver for the Tianma Radio Telescope (TMRT) has been developed, and it uses the independently-developed key microwave and millimeter-wave components operating from 35 to 50GHz with a fractional bandwidth of 35%. The Q-band receiver consists of three parts: optics, cold unit assembly and warm unit assembly, and it can receive simultaneously the left-handed and right-handed circularly polarized waves. The cold unit assembly of each beam is composed of a feed horn, a noise injection coupler, a differential phase shifter, an orthomode transducer and two low-noise amplifiers, and it works at a temperature range near 20 K to greatly improve the detection sensitivity of the receiving system. The warm unit assembly includes four radio-frequency amplifiers, four radio-frequency high-pass filters, four waveguide biased mixers, four 4–12 GHz intermediate-frequency amplifiers and one 31–38 GHz frequency synthesizer. The measured Q-band four-channel receiver noise temperatures are roughly 30–40 K. In addition, the single-dish spectral line and international very long baseline interferometry (VLBI) observations between the TMRT and East Asia VLBI Network at the Q-band have been successfully carried out, demonstrating the advantages of the TMRT equipped with the state-of-the-art Q-band receiver.

Implementation and on-sky results of an optimal wavefront controller for the MMT NGS adaptive optics system

NASA Astrophysics Data System (ADS)

Powell, Keith B.; Vaitheeswaran, Vidhya

2010-07-01

The MMT observatory has recently implemented and tested an optimal wavefront controller for the NGS adaptive optics system. Open loop atmospheric data collected at the telescope is used as the input to a MATLAB based analytical model. The model uses nonlinear constrained minimization to determine controller gains and optimize the system performance. The real-time controller performing the adaptive optics close loop operation is implemented on a dedicated high performance PC based quad core server. The controller algorithm is written in C and uses the GNU scientific library for linear algebra. Tests at the MMT confirmed the optimal controller significantly reduced the residual RMS wavefront compared with the previous controller. Significant reductions in image FWHM and increased peak intensities were obtained in J, H and K-bands. The optimal PID controller is now operating as the baseline wavefront controller for the MMT NGS-AO system.

ASSIGNMENT OF 5069 A DIFFUSE INTERSTELLAR BAND TO HC{sub 4}H{sup +}: DISAGREEMENT WITH LABORATORY ABSORPTION BAND

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

Maier, J. P.; Chakrabarty, S.; Mazzotti, F. J.

2011-03-10

Krelowski et al. have reported a weak, diffuse interstellar band (DIB) at 5069 A which appears to match in both mid-wavelength and width the A {sup 2}{Pi}{sub u}-X {sup 2}{Pi}{sub g} gas-phase origin absorption band of HC{sub 4}H{sup +}. Here, we present laboratory rotational profiles at low temperatures which are then compared with the 5069 A DIB using {approx}0.1 and 0.3 A line widths based on a realistic line-of-sight interstellar velocity dispersion. Neither the band shape nor the wavelength of the maximum absorption match, which makes the association of the 5069 A DIB with HC{sub 4}H{sup +} unlikely. The magneticmore » dipole transition X {sup 2}{Pi}{sub g} {Omega} = 1/2{yields}X {sup 2}{Pi}{sub g} {Omega} = 3/2 within the ground electronic state which competes with collisional excitation is also considered. In addition, we present the laboratory gas-phase spectrum of the A {sup 2}{Pi}{sub u}-X {sup 2}{Pi}{sub g} transition of HC{sub 4}H{sup +} measured at 25 K in an ion trap and identify further absorption bands at shorter wavelengths for comparison with future DIB data.« less

Shuttle Ku-band and S-band communications implementations study

NASA Technical Reports Server (NTRS)

Huth, G. K.; Nessibou, T.; Nilsen, P. W.; Simon, M. K.; Weber, C. L.

1979-01-01

The interfaces between the Ku-band system and the TDRSS, between the S-band system and the TDRSS, GSTDN and SGLS networks, and between the S-band payload communication equipment and the other Orbiter avionic equipment were investigated. The principal activities reported are: (1) performance analysis of the payload narrowband bent-pipe through the Ku-band communication system; (2) performance evaluation of the TDRSS user constraints placed on the S-band and Ku-band communication systems; (3) assessment of the shuttle-unique S-band TDRSS ground station false lock susceptibility; (4) development of procedure to make S-band antenna measurements during orbital flight; (5) development of procedure to make RFI measurements during orbital flight to assess the performance degradation to the TDRSS S-band communication link; and (6) analysis of the payload interface integration problem areas.

Dual S and Ku-band tracking feed for a TDRS reflector antenna

NASA Technical Reports Server (NTRS)

Pullara, J. C.; Bales, C. W.; Kefalas, G. P.; Uyehara, M.

1974-01-01

The results are presented of a trade study designed to identify a synchronous satellite antenna system suitable for receiving and transmitting data from lower orbiting satellites at both S- and K sub u-bands simultaneously as part of the Tracking and Data Relay Satellite System. All related problems associated with maintaining a data link between two satellites with a K sub u-band half-power beamwidth of 0.4 db are considered including data link maintenance techniques, beam pointing accuracies, gimbal and servo errors, solar heating, angle tracking schemes, acquisition problems and aids, tracking accuracies versus SNR, antenna feed designs, equipment designs, weight and power budgets, and detailed candidate antenna system designs.

Design of a K/Q-Band Beacon Receiver for the Alphasat TDP#5 Experiment

NASA Technical Reports Server (NTRS)

Morse, Jacquelynne R.

2014-01-01

This paper describes the design and performance of a coherent KQ-band (2040 GHz) beacon receiver developed at NASA Glenn Research Center (GRC) that will be installed at the Politecnico di Milano (POLIMI) for use in the Alphasat Technology Demonstration Payload 5 (TDP5) beacon experiment. The goal of this experiment is to characterize rain fade attenuation at 40 GHz to improve the performance of existing statistical rain attenuation models in the Q-band. The ground terminal developed by NASA GRC utilizes an FFT-based frequency estimation receiver capable of characterizing total path attenuation effects due to gaseous absorption, clouds, rain, and scintillation. The receiver system has been characterized in the lab and demonstrates a system dynamic range performance of better than 58 dB at 1 Hz and better than 48 dB at 10 Hz rates.

Density Measurements in Air by Optically Exciting the Cordes Bands of I2

NASA Technical Reports Server (NTRS)

Balla, R. Jeffrey; Exton, Reginald J.

2000-01-01

We describe an optical method based on laser-induced fluorescence for obtaining instantaneous measurements of density along a line in low-density air seeded with I2. The Cordes bands of I2 (D(sup 1)sigma(sup +, sub u)) left arrow X(sup 1)sigma(sup +, sub g)) are excited with a tunable ArF excimer laser. air densities in the range (0.1-6.5) x 10(exp 17) cm(exp -3) are measured over 295-583 K using the density-dependent emission ratio of two emission bands of I2; the 340 nm bands and the diffuse-structured McLennan bands near 320 nm.

On the Performance of Adaptive Data Rate over Deep Space Ka-Bank Link: Case Study Using Kepler Data

NASA Technical Reports Server (NTRS)

Gao, Jay L.

2016-01-01

Future missions envisioned for both human and robotic exploration demand increasing communication capacity through the use of Ka-band communications. The Ka-band channel, being more sensitive to weather impairments, presents a unique trade-offs between data storage, latency, data volume and reliability. While there are many possible techniques for optimizing Ka-band operations such as adaptive modulation and coding and site-diversity, this study focus exclusively on the use of adaptive data rate (ADR) to achieve significant improvement in the data volume-availability tradeoff over a wide range of link distances for near Earth and Mars exploration. Four years of Kepler Ka-band downlink symbol signal-to-noise (SNR) data reported by the Deep Space Network were utilized to characterize the Ka-band channel statistics at each site and conduct various what-if performance analysis for different link distances. We model a notional closed-loop adaptive data rate system in which an algorithm predicts the channel condition two-way light time (TWLT) into the future using symbol SNR reported in near-real time by the ground receiver and determines the best data rate to use. Fixed and adaptive margins were used to mitigate errors in channel prediction. The performance of this closed-loop adaptive data rate approach is quantified in terms of data volume and availability and compared to the actual mission configuration and a hypothetical, optimized single rate configuration assuming full a priori channel knowledge.

An Improved X-Band Maser System for Deep Space Network Applications

NASA Astrophysics Data System (ADS)

Britcliffe, M.; Hanson, T.; Fernandez, J.

2000-01-01

An 8450-MHz (X-band) maser system utilizing a commercial Gifford--McMahon (GM) closed-cycle cryocooler (CCR) was designed, fabricated, and demonstrated. The CCR system was used to cool a maser operating at 8450 MHz. The prototype GM CCR system meets or exceeds all Deep Space Network requirements for maser performance. The two-stage GM CCR operates at 4.2 K; for comparison, the DSN's current three-stage cryocooler, which uses a Joule--Thompson cooling stage in addition to GM cooling, operates at 4.5 K. The new CCR withstands heat loads of 1.5 W at 4.2 K as compared to 1 W at 4.5 K for the existing DSN cryocooler used for cooling masers. The measured noise temperature, T_e, of the maser used for these tests is defined at the ambient connection to the antenna feed system. The T_e measured 5.0 K at a CCR temperature of 4.5 K, about 1.5 K higher than the noise temperature of a typical DSN Block II-A X-band traveling-wave maser (TWM). Reducing the temperature of the CCR significantly lowers the maser noise temperature and increases maser gain and bandwidth. The new GM CCR gives future maser systems significant operational advantages, including reduced maintenance time and logistics requirements. The results of a demonstration of this new system are presented. Advantages of using a GM-cooled maser and the effects of the reduced CCR temperature on maser performance are discussed.

H3K27me3 forms BLOCs over silent genes and intergenic regions and specifies a histone banding pattern on a mouse autosomal chromosome

PubMed Central

Pauler, Florian M.; Sloane, Mathew A.; Huang, Ru; Regha, Kakkad; Koerner, Martha V.; Tamir, Ido; Sommer, Andreas; Aszodi, Andras; Jenuwein, Thomas; Barlow, Denise P.

2009-01-01

In mammals, genome-wide chromatin maps and immunofluorescence studies show that broad domains of repressive histone modifications are present on pericentromeric and telomeric repeats and on the inactive X chromosome. However, only a few autosomal loci such as silent Hox gene clusters have been shown to lie in broad domains of repressive histone modifications. Here we present a ChIP-chip analysis of the repressive H3K27me3 histone modification along chr 17 in mouse embryonic fibroblast cells using an algorithm named broad local enrichments (BLOCs), which allows the identification of broad regions of histone modifications. Our results, confirmed by BLOC analysis of a whole genome ChIP-seq data set, show that the majority of H3K27me3 modifications form BLOCs rather than focal peaks. H3K27me3 BLOCs modify silent genes of all types, plus flanking intergenic regions and their distribution indicates a negative correlation between H3K27me3 and transcription. However, we also found that some nontranscribed gene-poor regions lack H3K27me3. We therefore performed a low-resolution analysis of whole mouse chr 17, which revealed that H3K27me3 is enriched in mega-base-pair-sized domains that are also enriched for genes, short interspersed elements (SINEs) and active histone modifications. These genic H3K27me3 domains alternate with similar-sized gene-poor domains. These are deficient in active histone modifications, as well as H3K27me3, but are enriched for long interspersed elements (LINEs) and long-terminal repeat (LTR) transposons and H3K9me3 and H4K20me3. Thus, an autosome can be seen to contain alternating chromatin bands that predominantly separate genes from one retrotransposon class, which could offer unique domains for the specific regulation of genes or the silencing of autonomous retrotransposons. PMID:19047520

LANDSAT 4 band 6 data evaluation

NASA Technical Reports Server (NTRS)

1985-01-01

Comparison of underflight data with satellite estimates of temperature revealed significant gain calibration errors. The source of the LANDSAT 5 band 6 error and its reproducibility is not yet adequately defined. The error can be accounted for using underflight or ground truth data. When underflight data are used to correct the satellite data, the residual error for the scene studied was 1.3K when the predicted temperatures were compared to measured surface temperature.

Broad-Band Integrated Optical Electric Field Sensor Using Reflection Mach-Zehnder Waveguide Modulator

NASA Astrophysics Data System (ADS)

Zhang, Jiahong; Zhao, Zhengang; Li, Chuan; Li, Yingna

2017-09-01

A lithium niobate (LiNbO3) broad-band photonic sensor using reflection-type Mach-Zehnder optical waveguide modulator has been designed, fabricated, and experimentally demonstrated. The bare chip size of the sensor is microminiaturized as small as 20×5×0.5 mm3. The sensor has a wide band frequency response from 10 kHz to 20 GHz with variation less than ± 5 dB. The sensor system shows better linear characteristic from 100 mV/m to 700 V/m, and the sensitivity is 33 mV/m. Besides, the nanosecond EMP with intensity of 30 kV/m has been measured in the time domain.

High-K Isomers in Light Superheavy Nuclei by PNC-CSM method

NASA Astrophysics Data System (ADS)

He, Xiao-Tao

2018-05-01

The high-K isomeric states in light superheavy nuclei around A = 250 mass region are investigated by the Cranked Shell Model (CSM) with pairing treated by a Particle-Number Conserving (PNC) method. With including the higher-order deformation ɛ6, both of the high-K multi-particle state energies and the rotational bands in 254No and N = 150 isotone are reproduced well. The isomeric state energies and the microscopic mechanism of kinematic moment of inertia variations versus rotational frequency are discussed. The irregularity of the two-neutron Kπ = 8- state band at ħω ≈ 0:17 in 252No is caused by the configuration mixing with the two-proton Kπ = 8- band. .

SF_6: the Forbidden Band Unveiled

NASA Astrophysics Data System (ADS)

Boudon, V.; Manceron, L.; Kwabia-Tchana, F.; Roy, P.

2013-06-01

Sulfur hexafluoride (SF_6) is a greenhouse gas of anthropogenic origin, whose strong infrared absorption in the ν_3 S-F stretching region near 948 cm^{-1} induces a global warming potential 23900 times bigger than CO_2. This heavy species features many hot bands at room temperature (at which the ground state population is only 30 %), especially those originating from the v_6=1 state. Unfortunately, the ν_6 band itself (near 347 cm^{-1}) being, in first approximation, both infrared and Raman inactive, no reliable information could be obtained about it up to now. A long time ago, some authors suggested that this band may be slightly activated through Coriolis interaction and may appear as a very faint band, with an integrated intensity about 2 millionths of that of ν_3. Using a new cryogenic multipass cell with 93 m optical path length and regulated at 165± 2 K temperature, we recorded a spectrum of the ν_6 far-infrared region thanks to the performances of the AILES Beamline at the SOLEIL french synchrotron facility. Low temperature was used to avoid the presence of the 2ν_6-ν_6 hot band and to reduce the neighboring, stronger ν_4-ν_2 difference band. We are thus able to confirm that the small feature in this region, previously viewed at low-resolution is indeed ν_6. We present its fully resolved spectrum. It appears to be activated thanks to unidentified faint interactions resulting in the presence of a first-order dipole moment term that induces unusual selection rules. This spectrum was analyzed thanks to the XTDS software package, leading to accurate molecular spectroscopic parameters that should be useful to model the hot bands of SF_6. W. B. Person, B. J. Krohn, J. Mol. Spectrosc. {98}, 229-257 (1983), C. Chappados, G. Birnbaum, J. Mol. Spectrosc. {105}, 206-214 (1984). Ch. Wenger, V. Boudon, M. Rotger, M. Sanzharov and J.-P. Champion, J. Mol. Spectrosc., {251} 102-113 (2008).

Multi-band optical variability studies of Blazars

NASA Astrophysics Data System (ADS)

Agarwal, Aditi

2018-04-01

To search for optical variability on a wide range of timescales, we have carried out photometric monitoring of a dozen blazars. CCD magnitudes in B, V, R and I pass-bands were determined for > 10,000f new optical observations from 300 nights made during 2011 – 2016, with an average length of 4 h each, using seven optical telescopes: four in Bulgaria, one in Greece, and two in India. We measured multiband optical flux and colour variations on diverse timescales. Blazar variability studies helped us in understanding their nature and extreme conditions within the emission region. To explain possible physical causes of the observed spectral variability, we also investigated spectral energy distributions using B, V, R, I, J and K pass-band data.

Polycrystalline ZrTe 5 Parametrized as a Narrow-Band-Gap Semiconductor for Thermoelectric Performance

DOE PAGES

Miller, Samuel A.; Witting, Ian; Aydemir, Umut; ...

2018-01-24

The transition-metal pentatellurides HfTe 5 and ZrTe 5 have been studied for their exotic transport properties with much debate over the transport mechanism, band gap, and cause of the resistivity behavior, including a large low-temperature resistivity peak. Single crystals grown by the chemical-vapor-transport method have shown an n-p transition of the Seebeck coefficient at the same temperature as a peak in the resistivity. We show that behavior similar to that of single crystals can be observed in iodine-doped polycrystalline samples but that undoped polycrystalline samples exhibit drastically different properties: they are p type over the entire temperature range. Additionally, themore » thermal conductivity for polycrystalline samples is much lower, 1.5 Wm -1 K -1, than previously reported for single crystals. It is found that the polycrystalline ZrTe 5 system can be modeled as a simple semiconductor with conduction and valence bands both contributing to transport, separated by a band gap of 20 meV. This model demonstrates to first order that a simple two-band model can explain the transition from n- to p-type behavior and the cause of the anomalous resistivity peak. Combined with the experimental data, the two-band model shows that carrier concentration variation is responsible for differences in behavior between samples. Using the two-band model, the thermoelectric performance at different doping levels is predicted, finding zT=0.2 and 0.1 for p and n type, respectively, at 300 K, and zT=0.23 and 0.32 for p and n type at 600 K. Given the reasonably high zT that is comparable in magnitude for both n and p type, a thermoelectric device with a single compound used for both legs is feasible.« less

Performance and Uniformity of Mass-Produced SIS Mixers for ALMA Band 8 Receiver Cartridges

NASA Astrophysics Data System (ADS)

Tomura, Tomonuri; Noguchi, Takashi; Sekimoto, Yutaro; Shan, Wenlei; Sato, Naohisa; Iizuka, Yoshizo; Kumagai, Kazuyoshi; Niizeki, Yasuaki; Iwakuni, Mikio; Ito, Tetsuya

2015-05-01

The Atacama large millimeter/submillimeter array (ALMA), which was jointly built in Chile by Europe, North America and East Asia, has an observational band from 30 to 950 GHz [1], [2]. We developed receiver cartridges for ALMA Band 8 (385-500 GHz) [3]-[5] which is one of ALMA 10 frequency bands. The Band 8 receiver cartridges were produced as 73 cartridges, and 292 SIS mixers were installed in their cartridges. Also, their all cartridges were required to meet following ALMA specifications: 1. The noise temperature is less than 196 K over 80% of the frequency range and less than 292 K at any frequency from 385 to 500 GHz. 2. The image rejection ratio is larger than 10 dB over 90% of the frequency range. 3. The IF output power variation is less than 7.0 dB peak-to-peak in the 4-8 GHz band. 4. The gain compression to RF load temperatures between 77 and 373 K is less than 5%. 5. The Allan variance of the IF output power is less than 4.0×10-7 in the time scale of 0.05 s≤T≤100 s and 3.0×10-6 at 300 s. To meet these specifications, the performance and uniformity of the SIS mixers are crucial. The SIS mixers with Nb/Al-AlOx/Nb superconductor-insulator-superconductor (SIS) tunnel junctions were fabricated in a clean room of National Astronomical Observatory of Japan and over 1000 mixer chips were mass-produced. After screening these mixers, 73 Band 8 receivers were assembled and tested. We report the test results of the mass-produced mixers and the receiver cartridges in detail from a statistical point of view.

Polycrystalline ZrTe5 Parametrized as a Narrow-Band-Gap Semiconductor for Thermoelectric Performance

NASA Astrophysics Data System (ADS)

Miller, Samuel A.; Witting, Ian; Aydemir, Umut; Peng, Lintao; Rettie, Alexander J. E.; Gorai, Prashun; Chung, Duck Young; Kanatzidis, Mercouri G.; Grayson, Matthew; Stevanović, Vladan; Toberer, Eric S.; Snyder, G. Jeffrey

2018-01-01

The transition-metal pentatellurides HfTe5 and ZrTe5 have been studied for their exotic transport properties with much debate over the transport mechanism, band gap, and cause of the resistivity behavior, including a large low-temperature resistivity peak. Single crystals grown by the chemical-vapor-transport method have shown an n -p transition of the Seebeck coefficient at the same temperature as a peak in the resistivity. We show that behavior similar to that of single crystals can be observed in iodine-doped polycrystalline samples but that undoped polycrystalline samples exhibit drastically different properties: they are p type over the entire temperature range. Additionally, the thermal conductivity for polycrystalline samples is much lower, 1.5 Wm-1 K-1 , than previously reported for single crystals. It is found that the polycrystalline ZrTe5 system can be modeled as a simple semiconductor with conduction and valence bands both contributing to transport, separated by a band gap of 20 meV. This model demonstrates to first order that a simple two-band model can explain the transition from n - to p -type behavior and the cause of the anomalous resistivity peak. Combined with the experimental data, the two-band model shows that carrier concentration variation is responsible for differences in behavior between samples. Using the two-band model, the thermoelectric performance at different doping levels is predicted, finding z T =0.2 and 0.1 for p and n type, respectively, at 300 K, and z T =0.23 and 0.32 for p and n type at 600 K. Given the reasonably high z T that is comparable in magnitude for both n and p type, a thermoelectric device with a single compound used for both legs is feasible.

Polycrystalline ZrTe 5 Parametrized as a Narrow-Band-Gap Semiconductor for Thermoelectric Performance

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

Miller, Samuel A.; Witting, Ian; Aydemir, Umut

The transition-metal pentatellurides HfTe 5 and ZrTe 5 have been studied for their exotic transport properties with much debate over the transport mechanism, band gap, and cause of the resistivity behavior, including a large low-temperature resistivity peak. Single crystals grown by the chemical-vapor-transport method have shown an n-p transition of the Seebeck coefficient at the same temperature as a peak in the resistivity. We show that behavior similar to that of single crystals can be observed in iodine-doped polycrystalline samples but that undoped polycrystalline samples exhibit drastically different properties: they are p type over the entire temperature range. Additionally, themore » thermal conductivity for polycrystalline samples is much lower, 1.5 Wm -1 K -1, than previously reported for single crystals. It is found that the polycrystalline ZrTe 5 system can be modeled as a simple semiconductor with conduction and valence bands both contributing to transport, separated by a band gap of 20 meV. This model demonstrates to first order that a simple two-band model can explain the transition from n- to p-type behavior and the cause of the anomalous resistivity peak. Combined with the experimental data, the two-band model shows that carrier concentration variation is responsible for differences in behavior between samples. Using the two-band model, the thermoelectric performance at different doping levels is predicted, finding zT=0.2 and 0.1 for p and n type, respectively, at 300 K, and zT=0.23 and 0.32 for p and n type at 600 K. Given the reasonably high zT that is comparable in magnitude for both n and p type, a thermoelectric device with a single compound used for both legs is feasible.« less

Octave-Band Thresholds for Modeled Reverberant Fields

NASA Technical Reports Server (NTRS)

Begault, Durand R.; Wenzel, Elizabeth M.; Tran, Laura L.; Anderson, Mark R.; Trejo, Leonard J. (Technical Monitor)

1998-01-01

Auditory thresholds for 10 subjects were obtained for speech stimuli reverberation. The reverberation was produced and manipulated by 3-D audio modeling based on an actual room. The independent variables were octave-band-filtering (bypassed, 0.25 - 2.0 kHz Fc) and reverberation time (0.2- 1.1 sec). An ANOVA revealed significant effects (threshold range: -19 to -35 dB re 60 dB SRL).

W-band PELDOR with 1 kW microwave power: molecular geometry, flexibility and exchange coupling.

PubMed

Reginsson, Gunnar W; Hunter, Robert I; Cruickshank, Paul A S; Bolton, David R; Sigurdsson, Snorri Th; Smith, Graham M; Schiemann, Olav

2012-03-01

A technique that is increasingly being used to determine the structure and conformational flexibility of biomacromolecules is Pulsed Electron-Electron Double Resonance (PELDOR or DEER), an Electron Paramagnetic Resonance (EPR) based technique. At X-band frequencies (9.5 GHz), PELDOR is capable of precisely measuring distances in the range of 1.5-8 nm between paramagnetic centres but the orientation selectivity is weak. In contrast, working at higher frequencies increases the orientation selection but usually at the expense of decreased microwave power and PELDOR modulation depth. Here it is shown that a home-built high-power pulsed W-band EPR spectrometer (HiPER) with a large instantaneous bandwidth enables one to achieve PELDOR data with a high degree of orientation selectivity and large modulation depths. We demonstrate a measurement methodology that gives a set of PELDOR time traces that yield highly constrained data sets. Simulating the resulting time traces provides a deeper insight into the conformational flexibility and exchange coupling of three bisnitroxide model systems. These measurements provide strong evidence that W-band PELDOR may prove to be an accurate and quantitative tool in assessing the relative orientations of nitroxide spin labels and to correlate those orientations to the underlying biological structure and dynamics. Copyright © 2012 Elsevier Inc. All rights reserved.

Electronic structure investigation of MoS2 and MoSe2 using angle-resolved photoemission spectroscopy and ab initio band structure studies.

PubMed

Mahatha, S K; Patel, K D; Menon, Krishnakumar S R

2012-11-28

Angle-resolved photoemission spectroscopy (ARPES) and ab initio band structure calculations have been used to study the detailed valence band structure of molybdenite, MoS(2) and MoSe(2). The experimental band structure obtained from ARPES has been found to be in good agreement with the theoretical calculations performed using the linear augmented plane wave (LAPW) method. In going from MoS(2) to MoSe(2), the dispersion of the valence bands decreases along both k(parallel) and k(perpendicular), revealing the increased two-dimensional character which is attributed to the increasing interlayer distance or c/a ratio in these compounds. The width of the valence band and the band gap are also found to decrease, whereas the valence band maxima shift towards the higher binding energy from MoS(2) to MoSe(2).

Line Intensities in the ν 8Band of HNO 3

NASA Astrophysics Data System (ADS)

Wang, W. F.; Looi, E. C.; Tan, T. L.; Ong, P. P.

1996-07-01

Line intensity measurements have been made on the ν 8band of HNO 3using a high-resolution Fourier transform infrared spectrum in the region 739-800 cm -1. A least-squares fit of a total of 710 line intensities in the Pand Rbranches was performed, leading to accurate determination of five dipole moment operator constants. By utilizing these constants, the observed line intensities are well reproduced with an average random error of 6% and the integrated band intensity is found to be 15.7 ± 0.9 cm -2atm -1at 296 K.

Synchronous changes in coral chromatophore tissue density and skeletal banding as an adaptive response to environmental change

NASA Astrophysics Data System (ADS)

Ardisana, R. N.; Miller, C. A.; Sivaguru, M.; Fouke, B. W.

2013-12-01

Corals are a key reservoir of biodiversity in coastal, shallow water tropical marine environments, and density banding in their aragonite skeletons is used as a sensitive record of paleoclimate. Therefore, the cellular response of corals to environmental change and its expression in skeletal structure is of significant importance. Chromatophores, pigment-bearing cells within the ectoderm of hermatypic corals, serve to both enhance the photosynthetic activity of zooxanthellae symbionts, as well as protect the coral animal from harmful UV radiation. Yet connections have not previously been drawn between chromatophore tissue density and the development of skeletal density bands. A histological analysis of the coral Montastrea faveolata has therefore been conducted across a bathymetric gradient of 1-20 m on the southern Caribbean island of Curaçao. A combination of field and laboratory photography, serial block face imaging (SBFI), two-photon laser scanning microscopy (TPLSM), and 3D image analysis has been applied to test whether M. faveolata adapts to increasing water depth and decreasing photosynthetically active radiation by shifting toward a more heterotrophic lifestyle (decreasing zooxanthellae tissue density, increasing mucocyte tissue density, and decreasing chromatophores density). This study is among the first to collect and evaluate histological data in the spatial context of an entire unprocessed coral polyp. TPLSM was used to optically thin section unprocessed tissue biopsies with quantitative image analysis to yield a nanometer-scale three-dimensional map of the quantity and distribution of the symbionts (zooxanthellae) and a host fluorescent pigments (chromatophores), which is thought to have photoprotective properties, within the context of an entire coral polyp. Preliminary results have offered new insight regarding the three-dimensional distribution and abundance of chromatophores and have identified: (1) M. faveolata tissue collected from 8M SWD do

Q/V-band communications and propagation experiments using ALPHASAT

NASA Astrophysics Data System (ADS)

Koudelka, O.

2011-12-01

The lower satellite frequency bands become more and more congested; therefore it will be necessary to exploit higher frequencies for satellite communications. New broadband applications (e.g. 3D-TV, fast Internet access) will require additional spectrum in the future. The Ku-band is highly utilised nowadays and Ka-band systems, which have been extensively studied in the 1990s, are already in commercial use. The next frontier is the Q/V-band. At millimetre waves the propagation effects are significant. The traditional approach of implementing large fade margins is impractical, since this leads to high EIRP and G/ T figures for the ground stations, resulting in unacceptable costs. Fade mitigation techniques by adaptive coding and modulation (ACM) offer a cost-effective solution to this problem. ESA will launch the ALPHASAT satellite in 2012. It will carry experimental Ka- and Q/V-band propagation and communications payloads, enabling propagation measurements throughout Europe and communications experiments. Three communications spot beams will be covering Northern Italy, Southern Italy and Austria with some overlap. Joanneum Research and Graz University of Technology are preparing for communications and propagation experiments using these new payloads of ALPHASAT in close cooperation with ESA, the Italian Space Agency ASI, Politecnico di Milano and Università Tor Vergata. The main focus of the communications experiments is on ACM techniques. The paper describes the design of the planned Q/V-band ground station with the planned ACM tests and investigations as well as the architecture of the communications terminal, based on a versatile software-defined radio platform.

Analysis of 2ν3 Band of Hto

NASA Astrophysics Data System (ADS)

Kobayashi, Kaori; Maki, Hiroki; Yamamoto, Takuya; Hara, Masanori; Hatano, Yuji; Ozeki, Hiroyuki

2014-06-01

Tritium is a radioactive isotope of hydrogen. Tritium released into natural enviroment is said to be converted into mostly HTO. The detection of HTO is important from the viewpoint of basic science as well as its radioactivity. Spectroscopy is a good tool for detection, however, high-resolution spectroscopy studies are still limited. The microwave study were carried out and the molecular constants of the ground state were determined. All fundamental ν_1, ν_2 and the ν_3 bands of HTO were reported. At 1.38 micron region, overtone and combination bands are expected. In this study, we prepared a new double wall cell for safe handling of highly concentrated tritiated water and carried out the near-infrared measurement. More than 100 transitions were observed and most of them were assigned to belong to the 2ν_3 band based on the previous quantum chemical calculations. We will report the current status of the analysis. P. Helminger, F. C. De Lucia, W. Gordy, P. A. Staats and H. W. Morgan, Phys. Rev. A, 10, 1072 (1974). S. D. Cope, D. K. Russell, H. A. Fry, L. H. Jones, and J. E. Barefield, J. Mol. Spectrosc., 127, 464 (1988). P. P. Cherrier, P. H. Beckwith, and J. Reid, J. Mol. Spectrosc., 121, 69 (1987). M. Tine, D. Kobor, I. Sakho, and L. H. Coudert, J. Mod. Phys., 3, 1945 (2012). M. J. Down, J. Tennyson, M. Hara, Y. Hatano, and K. Kobayashi, J. Mol. Spectrosc., 289, 35 (2013).

Experimental research on Ku-band magnetically insulated transmission line oscillator

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

Jiang, Tao; Zhang, Jiande; He, Juntao

2015-10-15

An improved Ku-band magnetically insulated transmission line oscillator is proposed and investigated experimentally. In the particle-in-cell simulation, the Ku-band MILO generates the microwave with a power of 1.62 GW and a frequency of 13 GHz at the input voltage of 474 kV. The device is fabricated based on the simulation results, and an experiment system is designed. In the preliminary experiments, output microwave with frequency of 13.02 GHz, power of 150 MW, and pulse width of 17 ns is generated, under the diode voltage of 450 kV. Analysis on the experiment results shows that plasma produced due to the large current hitting to the outside of themore » collection tank is the essential cause for the low amplitude of the microwave power and short pulse width.« less

Fast growth phenotype of E. coli K-12 from adaptive laboratory evolution does not require intracellular flux rewiring

PubMed Central

Long, Christopher P.; Gonzalez, Jacqueline E.; Feist, Adam M.; Palsson, Bernhard O.; Antoniewicz, Maciek R.

2018-01-01

Adaptive laboratory evolution (ALE) is a widely-used method for improving the fitness of microorganisms in selected environmental conditions. It has been applied previously to Escherichia coli K-12 MG1655 during aerobic exponential growth on glucose minimal media, a frequently used model organism and growth condition, to probe the limits of E. coli growth rate and gain insights into fast growth phenotypes. Previous studies have described up to 1.6-fold increases in growth rate following ALE, and have identified key causal genetic mutations and changes in transcriptional patterns. Here, we report for the first time intracellular metabolic fluxes for six such adaptively evolved strains, as determined by high-resolution 13C-metabolic flux analysis. Interestingly, we found that intracellular metabolic pathway usage changed very little following adaptive evolution. Instead, at the level of central carbon metabolism the faster growth was facilitated by proportional increases in glucose uptake and all intracellular rates. Of the six evolved strains studied here, only one strain showed a small degree of flux rewiring, and this was also the strain with unique genetic mutations. A comparison of fluxes with two other wild-type (unevolved) E. coli strains, BW25113 and BL21, showed that inter-strain differences are greater than differences between the parental and evolved strains. Principal component analysis highlighted that nearly all flux differences (95%) between the nine strains were captured by only two principal components. The distance between measured and flux balance analysis predicted fluxes was also investigated. It suggested a relatively wide range of similar stoichiometric optima, which opens new questions about the path-dependency of adaptive evolution. PMID:28951266

High-K isomers and rotational structures in {sup 174}W

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

Tandel, S.K.; Chowdhury, P.; Seabury, E.H.

2006-04-15

High-spin states in {sup 174}W (Z = 74) have been populated using the reaction {sup 128}Te({sup 50}Ti, 4n){sup 174}W at beam energies of 215 and 225 MeV. The Gammasphere array was used to detect the {gamma} rays emitted by the evaporation residues. Four previously known collective band structures have been extended, and 16 new rotational sequences observed. Two are built upon isomeric states, one corresponding to a two-quasiparticle K = 8 isomer, the other to a four-quasiparticle K = 12 isomer, with the latter exhibiting strong K-violating {delta}K=12 decays to the ground state band. Nucleonic configurations for the two- andmore » four-quasiparticle excitations are proposed, and Woods-Saxon cranking calculations are presented to understand the rotational structures. Decay mechanisms of multi-quasiparticle K isomers are discussed in terms of the prevalent phenomenological models, with special emphasis on {gamma}-tunneling calculations. Surprisingly, the latter underpredict the decay hindrance for the K = 12 isomer by three orders of magnitude, unlike all other isomer decays in this mass region.« less

Tunable Microwave Components for Ku- and K-Band Satellite Communications

NASA Technical Reports Server (NTRS)

Miranada, F. A.; VanKeuls, F. W.; Romanofsky, R. R.; Subramanyam, G.

1998-01-01

The use of conductor/ferroelectric/dielectric thin film multilayer structures for frequency and phase agile components at frequencies at and above the Ku-band will be discussed. Among these components are edge coupled filters, microstripline ring resonators, and phase shifters. These structures were implemented using SrTiO3 (STO) ferroelectric thin films, with gold or YBa2Cu3O7-d (YBCO) high temperature superconducting (HTS) microstrip fines deposited by laser ablation on LaAlO3 (LAO) substrates. The performance of these structures in terms of tunability, operating temperature, frequency, and dc bias will be presented. Because of their small size, light weight, and low loss, these tunable microwave components are being studied very intensely at NASA as well as the commercial communication industry. An assessment of the progress made so far, and the issues yet to be solved for the successful integration of these components into the aforementioned communication systems will be presented.

Improved Band-to-Band Registration Characterization for VIIRS Reflective Solar Bands Based on Lunar Observations

NASA Technical Reports Server (NTRS)

Wang, Zhipeng; Xiong, Xiaoxiong; Li, Yonghong

2015-01-01

Spectral bands of the Visible Infrared Imaging Radiometer Suite (VIIRS) instrumentaboard the Suomi National Polar-orbiting Partnership (S-NPP) satellite are spatially co-registered.The accuracy of the band-to-band registration (BBR) is one of the key spatial parameters that must becharacterized. Unlike its predecessor, the Moderate Resolution Imaging Spectroradiometer (MODIS), VIIRS has no on-board calibrator specifically designed to perform on-orbit BBR characterization.To circumvent this problem, a BBR characterization method for VIIRS reflective solar bands (RSB) based on regularly-acquired lunar images has been developed. While its results can satisfactorily demonstrate that the long-term stability of the BBR is well within +/- 0.1 moderate resolution bandpixels, undesired seasonal oscillations have been observed in the trending. The oscillations are most obvious between the visiblenear-infrared bands and short-middle wave infrared bands. This paper investigates the oscillations and identifies their cause as the band spectral dependence of the centroid position and the seasonal rotation of the lunar images over calibration events. Accordingly, an improved algorithm is proposed to quantify the rotation and compensate for its impact. After the correction, the seasonal oscillation in the resulting BBR is reduced from up to 0.05 moderate resolution band pixels to around 0.01 moderate resolution band pixels. After removing this spurious seasonal oscillation, the BBR, as well as its long-term drift are well determined.

47 CFR 15.239 - Operation in the band 88-108 MHz.

Code of Federal Regulations, 2012 CFR

2012-10-01

... on the operating frequency. The 200 kHz band shall lie wholly within the frequency range of 88-108... employing an average detector. The provisions in § 15.35 for limiting peak emissions apply. (c) The field...

47 CFR 15.239 - Operation in the band 88-108 MHz.

Code of Federal Regulations, 2011 CFR

2011-10-01

... on the operating frequency. The 200 kHz band shall lie wholly within the frequency range of 88-108... employing an average detector. The provisions in § 15.35 for limiting peak emissions apply. (c) The field...

47 CFR 15.239 - Operation in the band 88-108 MHz.

Code of Federal Regulations, 2014 CFR

2014-10-01

... on the operating frequency. The 200 kHz band shall lie wholly within the frequency range of 88-108... employing an average detector. The provisions in § 15.35 for limiting peak emissions apply. (c) The field...

47 CFR 15.239 - Operation in the band 88-108 MHz.

Code of Federal Regulations, 2013 CFR

2013-10-01

... on the operating frequency. The 200 kHz band shall lie wholly within the frequency range of 88-108... employing an average detector. The provisions in § 15.35 for limiting peak emissions apply. (c) The field...

Multi-band, multi-epoch observations of the transiting warm Jupiter WASP-80b

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

Fukui, Akihiko; Kuroda, Daisuke; Kawashima, Yui

WASP-80b is a warm Jupiter transiting a bright late-K/early-M dwarf, providing a good opportunity to extend the atmospheric study of hot Jupiters toward the lower temperature regime. We report multi-band, multi-epoch transit observations of WASP-80b by using three ground-based telescopes covering from optical (g', R{sub c}, and I{sub c} bands) to near-infrared (NIR; J, H, and K{sub s} bands) wavelengths. We observe 5 primary transits, each in 3 or 4 different bands simultaneously, obtaining 17 independent transit light curves. Combining them with results from previous works, we find that the observed transmission spectrum is largely consistent with both a solarmore » abundance and thick cloud atmospheric models at a 1.7σ discrepancy level. On the other hand, we find a marginal spectral rise in the optical region compared to the NIR region at the 2.9σ level, which possibly indicates the existence of haze in the atmosphere. We simulate theoretical transmission spectra for a solar abundance but hazy atmosphere, finding that a model with equilibrium temperature of 600 K can explain the observed data well, having a discrepancy level of 1.0σ. We also search for transit timing variations, but find no timing excess larger than 50 s from a linear ephemeris. In addition, we conduct 43 day long photometric monitoring of the host star in the optical bands, finding no significant variation in the stellar brightness. Combined with the fact that no spot-crossing event is observed in the five transits, our results confirm previous findings that the host star appears quiet for spot activities, despite the indications of strong chromospheric activities.« less

Superconductivity in an electron band just above the Fermi level: possible route to BCS-BEC superconductivity.

PubMed

Okazaki, K; Ito, Y; Ota, Y; Kotani, Y; Shimojima, T; Kiss, T; Watanabe, S; Chen, C-T; Niitaka, S; Hanaguri, T; Takagi, H; Chainani, A; Shin, S

2014-02-28

Conventional superconductivity follows Bardeen-Cooper-Schrieffer(BCS) theory of electrons-pairing in momentum-space, while superfluidity is the Bose-Einstein condensation(BEC) of atoms paired in real-space. These properties of solid metals and ultra-cold gases, respectively, are connected by the BCS-BEC crossover. Here we investigate the band dispersions in FeTe(0.6)Se(0.4)(Tc = 14.5 K ~ 1.2 meV) in an accessible range below and above the Fermi level(EF) using ultra-high resolution laser angle-resolved photoemission spectroscopy. We uncover an electron band lying just 0.7 meV (~8 K) above EF at the Γ-point, which shows a sharp superconducting coherence peak with gap formation below Tc. The estimated superconducting gap Δ and Fermi energy [Symbol: see text]F indicate composite superconductivity in an iron-based superconductor, consisting of strong-coupling BEC in the electron band and weak-coupling BCS-like superconductivity in the hole band. The study identifies the possible route to BCS-BEC superconductivity.

Laparoscopic gastric banding

MedlinePlus

... adjustable gastric banding; Bariatric surgery - laparoscopic gastric banding; Obesity - gastric banding; Weight loss - gastric banding ... gastric banding is not a "quick fix" for obesity. It will greatly change your lifestyle. You must ...

Direct evidence for the participation of band-tails and excited-state tunnelling in the luminescence of irradiated feldspars

NASA Astrophysics Data System (ADS)

Poolton, N. R. J.; Kars, R. H.; Wallinga, J.; Bos, A. J. J.

2009-12-01

The significance and extent of band-tail states in the luminescence and dosimetry properties of natural aluminosilicates (feldspars) is investigated by means of studies using low temperature (10 K) irradiation and optically stimulated luminescence (OSL) stimulation spectroscopy, and thermoluminescence (TL) in the range 10-200 K, made in comparison with high temperature (300 K) irradiation and photo-transferred OSL and TL investigations undertaken at low temperature. These measurements allow mappings of the band-tails to be made; they are found to be ~0.4 eV in extent in the typical materials studied. Furthermore, by populating charge trapping centres at high temperature (300 K) and monitoring the OSL stimulation spectra at temperatures in the range 10-300 K, clear evidence is presented for the presence of both thermally activated and non-thermally activated OSL processes; it is argued that the former result from thermally activated hopping through the band-tail states, whilst the latter are due to tunnelling processes, either from the excited state of the OSL centres or through the tail states. The spectral measurements are supported by analysis of the temporal dependence of the OSL signals, which correspond to either tunnelling or general order kinetic decay processes.

W-Band InP Wideband MMIC LNA with 30K Noise Temperature

NASA Technical Reports Server (NTRS)

Weinreb, S.; Lai, R.; Erickson, N.; Gaier, T.; Wielgus, J.

2000-01-01

This paper describe a millimeter wave low noise amplifier with extraordinary low noise, low consumption, and wide frequency range. These results are achieved utilizing state-of-the-art InP HEMT transistors coupled with CPW circuit design. The paper describes the transistor models, modeled and measured on-wafer and in-module results at both 300K am 24K operating temperatures for many samples of the device.

A Novel Ku-Band/Ka-Band and Ka-Band/E-Band Multimode Waveguide Couplers for Power Measurement of Traveling-Wave Tube Amplifier Harmonic Frequencies

NASA Technical Reports Server (NTRS)

Wintucky, Edwin G.; Simons, Rainee N.

2015-01-01

This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler, fabricated from two dissimilar frequency band waveguides, is capable of isolating power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT) amplifier. Test results from proof-of-concept demonstrations are presented for a Ku-band/Ka-band MDC and a Ka-band/E-band MDC. In addition to power measurements at harmonic frequencies, a potential application of the MDC is in the design of a satellite borne beacon source for atmospheric propagation studies at millimeter-wave (mm-wave) frequencies (Ka-band and E-band).

Clicking in a killer whale habitat: narrow-band, high-frequency biosonar clicks of harbour porpoise (Phocoena phocoena) and Dall's porpoise (Phocoenoides dalli).

PubMed

Kyhn, Line A; Tougaard, Jakob; Beedholm, Kristian; Jensen, Frants H; Ashe, Erin; Williams, Rob; Madsen, Peter T

2013-01-01

Odontocetes produce a range of different echolocation clicks but four groups in different families have converged on producing the same stereotyped narrow band high frequency (NBHF) click. In microchiropteran bats, sympatric species have evolved the use of different acoustic niches and subtly different echolocation signals to avoid competition among species. In this study, we examined whether similar adaptations are at play among sympatric porpoise species that use NBHF echolocation clicks. We used a six-element hydrophone array to record harbour and Dall's porpoises in British Columbia (BC), Canada, and harbour porpoises in Denmark. The click source properties of all porpoise groups were remarkably similar and had an average directivity index of 25 dB. Yet there was a small, but consistent and significant 4 kHz difference in centroid frequency between sympatric Dall's (137±3 kHz) and Canadian harbour porpoises (141±2 kHz). Danish harbour porpoise clicks (136±3 kHz) were more similar to Dall's porpoise than to their conspecifics in Canada. We suggest that the spectral differences in echolocation clicks between the sympatric porpoises are consistent with evolution of a prezygotic isolating barrier (i.e., character displacement) to avoid hybridization of sympatric species. In practical terms, these spectral differences have immediate application to passive acoustic monitoring.

A Cross-Cultural Examination of University Students' Motivation toward Band and Academics in Singapore and the United States

ERIC Educational Resources Information Center

Tan, Leonard; Miksza, Peter

2018-01-01

The purpose of the study was to investigate how university band students' (non--music majors) motivational goal orientations toward band and academics differ across participants from Singapore (n = 200) and the United States (n = 227) and examine how they relate to a suite of adaptive dispositions (i.e., flow, grit, and commitment) relevant for…

METALLICITY AND TEMPERATURE INDICATORS IN M DWARF K-BAND SPECTRA: TESTING NEW AND UPDATED CALIBRATIONS WITH OBSERVATIONS OF 133 SOLAR NEIGHBORHOOD M DWARFS

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

Rojas-Ayala, Barbara; Covey, Kevin R.; Lloyd, James P.

2012-04-01

We present K-band spectra for 133 nearby (d < 33 ps) M dwarfs, including 18 M dwarfs with reliable metallicity estimates (as inferred from an FGK type companion), 11 M dwarf planet hosts, more than 2/3 of the M dwarfs in the northern 8 pc sample, and several M dwarfs from the LSPM catalog. From these spectra, we measure equivalent widths of the Ca and Na lines, and a spectral index quantifying the absorption due to H{sub 2}O opacity (the H{sub 2}O-K2 index). Using empirical spectral type standards and synthetic models, we calibrate the H{sub 2}O-K2 index as an indicatormore » of an M dwarf's spectral type and effective temperature. We also present a revised relationship that estimates the [Fe/H] and [M/H] metallicities of M dwarfs from their Na I, Ca I, and H{sub 2}O-K2 measurements. Comparisons to model atmosphere provide a qualitative validation of our approach, but also reveal an overall offset between the atomic line strengths predicted by models as compared to actual observations. Our metallicity estimates also reproduce expected correlations with Galactic space motions and H{alpha} emission line strengths, and return statistically identical metallicities for M dwarfs within a common multiple system. Finally, we find systematic residuals between our H{sub 2}O-based spectral types and those derived from optical spectral features with previously known sensitivity to stellar metallicity, such as TiO, and identify the CaH1 index as a promising optical index for diagnosing the metallicities of near-solar M dwarfs.« less

Multi-Quasiparticle Gamma-Band Structure in Neutron-Deficient Ce and Nd Isotopes

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

Sheikh, Javid; Bhat, G. H.; Palit, R.

2009-01-01

The newly developed multi-quasiparticle triaxial projected shell-model approach is employed to study the high-spin band structures in neutron-deficient even-even Ce and Nd isotopes. It is observed that gamma bands are built on each intrinsic configuration of the triaxial mean-field deformation. Due to the fact that a triaxial configuration is a superposition of several K states, the projection from these states results in several low-lying bands originating from the same intrinsic configuration. This generalizes the well-known concept of the surface gamma oscillation in deformed nuclei based on the ground state to gamma bands built on multi-quasiparticle configurations. This new feature providesmore » an alternative explanation on the observation of two I=10 aligning states in ^{134}Ce and both exhibiting a neutron character.« less

The neural oscillations of conflict adaptation in the human frontal region.

PubMed

Tang, Dandan; Hu, Li; Chen, Antao

2013-07-01

Incongruency between print color and the semantic meaning of a word in a classical Stroop task activates the human conflict monitoring system and triggers a behavioral conflict. Conflict adaptation has been suggested to mediate the cortical processing of neural oscillations in such a conflict situation. However, the basic mechanisms that underlie the influence of conflict adaptation on the changes of neural oscillations are not clear. In the present study, electroencephalography (EEG) data were recorded from sixteen healthy human participants while they were performing a color-word Stroop task within a novel look-to-do transition design that included two response modalities. In the 'look' condition, participants were informed to look at the color of presented words but no responses were required; in the 'do' condition, they were informed to make arranged responses to the color of presented words. Behaviorally, a reliable conflict adaptation was observed. Time-frequency analysis revealed that (1) in the 'look' condition, theta-band activity in the left- and right-frontal regions reflected a conflict-related process at a response inhibition level; and (2) in the 'do' condition, both theta-band activity in the left-frontal region and alpha-band activity in the left-, right-, and centro-frontal regions reflected a process of conflict control, which triggered neural and behavioral adaptation. Taken together, these results suggest that there are frontal mechanisms involving neural oscillations that can mediate response inhibition processes and control behavioral conflict. Copyright © 2013 Elsevier B.V. All rights reserved.

Optical model with multiple band couplings using soft rotator structure

NASA Astrophysics Data System (ADS)

Martyanov, Dmitry; Soukhovitskii, Efrem; Capote, Roberto; Quesada, Jose Manuel; Chiba, Satoshi

2017-09-01

A new dispersive coupled-channel optical model (DCCOM) is derived that describes nucleon scattering on 238U and 232Th targets using a soft-rotator-model (SRM) description of the collective levels of the target nucleus. SRM Hamiltonian parameters are adjusted to the observed collective levels of the target nucleus. SRM nuclear wave functions (mixed in K quantum number) have been used to calculate coupling matrix elements of the generalized optical model. Five rotational bands are coupled: the ground-state band, β-, γ-, non-axial- bands, and a negative parity band. Such coupling scheme includes almost all levels below 1.2 MeV of excitation energy of targets. The "effective" deformations that define inter-band couplings are derived from SRM Hamiltonian parameters. Conservation of nuclear volume is enforced by introducing a monopolar deformed potential leading to additional couplings between rotational bands. The present DCCOM describes the total cross section differences between 238U and 232Th targets within experimental uncertainty from 50 keV up to 200 MeV of neutron incident energy. SRM couplings and volume conservation allow a precise calculation of the compound-nucleus (CN) formation cross sections, which is significantly different from the one calculated with rigid-rotor potentials with any number of coupled levels.

System noise temperature investigation of the DSN S-band polarization diverse systems for the Galileo S-band Contingency Mission

NASA Technical Reports Server (NTRS)

Fernandez, J. E.; Trowbridge, D. L.

1995-01-01

This article describes measurements made at all three Deep Space Network 70-m S-band polarization diverse (SPD) systems to determine and eliminate the cause of the 1-K elevation in follow-up noise temperature in the listen-only mode of the SPD systems at DSS 43 and DSS 63. The system noise temperatures obtained after finding and correcting the cause of the elevated follow-up noise temperature are also reported.

Effects of K-Doping on Thermoelectric Properties of Bi1- x K x CuOTe

NASA Astrophysics Data System (ADS)

An, Tae-Ho; Lim, Young Soo; Seo, Won-Seon; Park, Cheol-Hee; Yoo, Mi Duk; Park, Chan; Lee, Chang Hoon; Shim, Ji Hoon

2017-05-01

The effects of K-doping on the thermoelectric properties of Bi1- x K x CuOTe ( x = 0 to 0.08) have been investigated. The compounds were synthesized by a one-step solid-state reaction method and consolidated by a spark plasma sintering process. As the amount of K-doping was increased, the electrical and thermal conductivities increased while the Seebeck coefficient decreased due to increasing hole concentration. A ZT value of 0.69 was obtained for the compound K0.01Bi0.99CuOTe at 700 K, to the best of our knowledge the highest value reported for this material system. The origin of this enhanced ZT is discussed in terms of the density of states effective mass estimated by a single parabolic band model and electronic structures calculated based on density functional theory.

Modelling and performance of Nb SIS mixers in the 1.3 mm and 0.8 mm bands

NASA Technical Reports Server (NTRS)

Karpov, A.; Carter, M.; Lazareff, B.; Billon-Pierron, D.; Gundlach, K. H.

1992-01-01

We describe the modeling and subsequent improvements of SIS waveguide mixers for the 200-270 and 330-370 GHz bands (Blundell, Carter, and Gundlach 1988, Carter et al 1991). These mixers are constructed for use in receivers on IRAM radiotelescopes on Pico Veleta (Spain, Sierra Nevada) and Plateau de Bure (French Alps), and must meet specific requirements. The standard reduced height waveguide structure with suspended stripline is first analyzed and a model is validated through comparison with scale model and working scale measurements. In the first step, the intrinsic limitations of the standard mixer structure are identified, and the parameters are optimized bearing in mind the radioastronomical applications. In the second step, inductive tuning of the junctions is introduced and optimized for minimum noise and maximum bandwidth. In the 1.3 mm band, a DSB receiver temperature of less than 110 K (minimum 80 K) is measured from 180 through 260 GHz. In the 0.8 mm band, a DSB receiver temperature of less than 250 K (minimum 175 K) is obtained between 325 and 355 GHz. All these results are obtained with room-temperature optics and a 4 GHz IF chain having a 500 MHz bandwidth and a noise temperature of 14 K.

Fourier transform synchrotron spectroscopy of the in-plane methyl-rocking band of CD3OH

NASA Astrophysics Data System (ADS)

Lees, R. M.; Xu, Li-Hong; Gao, Song; Billinghurst, B. E.

2015-09-01

Infrared Fourier transform spectra of the 12CD3OH isotopologue of methanol recorded at the Canadian Light Source synchrotron have been investigated in the 750-950 cm-1 region to explore the torsional energy pattern of the in-plane methyl-rocking mode. The in-plane CD3-rocking band is primarily of parallel a-type character with relatively widely spaced K-structure, and the central Q-branch region is well-resolved. Sub-bands have been assigned for the vt = 0 ground torsional state from K = 0 to 15 for both A and E torsional species, as well as a number of sub-bands in the vt = 1 excited torsional state. A variety of perturbations due to asymmetry-induced, anharmonic Fermi and level-crossing resonances is seen in the spectra. Mapping of K-reduced torsional energies determined from the upper-state term values shows that the K-dependence is severely distorted from the usual pattern of smoothly oscillating, near-sinusoidal interlocking τ-curves. Although the K = 0 levels are nominally inverted for vt = 0, the torsional splitting is very small with the A level higher than the E level by only 0.625 cm-1, and the anomalous behavior precludes a definite conclusion about torsional inversion. However, the range of variation with K of the vt = 0 CD3-rocking τ-curves is about half that of the ground vibrational state, similar to previous observations for CH3OH isotopologues, suggesting a comparable reduction of about 25% in the effective torsional barrier height for the in-plane rocking mode.

Bands selection and classification of hyperspectral images based on hybrid kernels SVM by evolutionary algorithm

NASA Astrophysics Data System (ADS)

Hu, Yan-Yan; Li, Dong-Sheng

2016-01-01

The hyperspectral images(HSI) consist of many closely spaced bands carrying the most object information. While due to its high dimensionality and high volume nature, it is hard to get satisfactory classification performance. In order to reduce HSI data dimensionality preparation for high classification accuracy, it is proposed to combine a band selection method of artificial immune systems (AIS) with a hybrid kernels support vector machine (SVM-HK) algorithm. In fact, after comparing different kernels for hyperspectral analysis, the approach mixed radial basis function kernel (RBF-K) with sigmoid kernel (Sig-K) and applied the optimized hybrid kernels in SVM classifiers. Then the SVM-HK algorithm used to induce the bands selection of an improved version of AIS. The AIS was composed of clonal selection and elite antibody mutation, including evaluation process with optional index factor (OIF). Experimental classification performance was on a San Diego Naval Base acquired by AVIRIS, the HRS dataset shows that the method is able to efficiently achieve bands redundancy removal while outperforming the traditional SVM classifier.

AgI alloying in SnTe boosts the thermoelectric performance via simultaneous valence band convergence and carrier concentration optimization

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

Banik, Ananya; Biswas, Kanishka, E-mail: kanishka@jncasr.ac.in

SnTe, a Pb-free analogue of PbTe, was earlier assumed to be a poor thermoelectric material due to excess p-type carrier concentration and large energy separation between light and heavy hole valence bands. Here, we report the enhancement of the thermoelectric performance of p-type SnTe by Ag and I co-doping. AgI (1–6 mol%) alloying in SnTe modulates its electronic structure by increasing the band gap of SnTe, which results in decrease in the energy separation between its light and heavy hole valence bands, thereby giving rise to valence band convergence. Additionally, iodine doping in the Te sublattice of SnTe decreases themore » excess p-type carrier concentration. Due to significant decrease in hole concentration and reduction of the energy separation between light and heavy hole valence bands, significant enhancement in Seebeck coefficient was achieved at the temperature range of 600–900 K for Sn{sub 1−x}Ag{sub x}Te{sub 1−x}I{sub x} samples. A maximum thermoelectric figure of merit, zT, of ~1.05 was achieved at 860 K in high quality crystalline ingot of p-type Sn{sub 0.95}Ag{sub 0.05}Te{sub 0.95}I{sub 0.05}. - Graphical abstract: Significant decrease in hole concentration and reduction of the energy separation between light and heavy hole valence bands resulted in a maximum thermoelectric figure of merit, zT, of ~1.05 at 860 K in high quality crystalline ingot of p-type Sn{sub 0.95}Ag{sub 0.05}Te{sub 0.95}I{sub 0.05}. - Highlights: • AgI alloying in SnTe increases the principle band gap. • Hole concentration reduction and valence band convergence enhances thermopower of SnTe-AgI. • A maximum zT of ~1.05 was achieved at 860 K in p-type Sn{sub 0.95}Ag{sub 0.05}Te{sub 0.95}I{sub 0.05}.« less

comK prophage junction fragments as markers for Listeria monocytogenes genotypes unique to individual meat and poultry processing plants and a model for rapid niche-specific adaptation, biofilm formation, and persistence.

PubMed

Verghese, Bindhu; Lok, Mei; Wen, Jia; Alessandria, Valentina; Chen, Yi; Kathariou, Sophia; Knabel, Stephen

2011-05-01

Different strains of Listeria monocytogenes are well known to persist in individual food processing plants and to contaminate foods for many years; however, the specific genotypic and phenotypic mechanisms responsible for persistence of these unique strains remain largely unknown. Based on sequences in comK prophage junction fragments, different strains of epidemic clones (ECs), which included ECII, ECIII, and ECV, were identified and shown to be specific to individual meat and poultry processing plants. The comK prophage-containing strains showed significantly higher cell densities after incubation at 30°C for 48 h on meat and poultry food-conditioning films than did strains lacking the comK prophage (P < 0.05). Overall, the type of strain, the type of conditioning film, and the interaction between the two were all highly significant (P < 0.001). Recombination analysis indicated that the comK prophage junction fragments in these strains had evolved due to extensive recombination. Based on the results of the present study, we propose a novel model in which the concept of defective comK prophage was replaced with the rapid adaptation island (RAI). Genes within the RAI were recharacterized as "adaptons," as these genes may allow L. monocytogenes to rapidly adapt to different food processing facilities and foods. If confirmed, the model presented would help explain Listeria's rapid niche adaptation, biofilm formation, persistence, and subsequent transmission to foods. Also, comK prophage junction fragment sequences may permit accurate tracking of persistent strains back to and within individual food processing operations and thus allow the design of more effective intervention strategies to reduce contamination and enhance food safety.

The Future of the Deep Space Network: Technology Development for K2-Band Deep Space Communications

NASA Technical Reports Server (NTRS)

Bhanji, Alaudin M.

1999-01-01

Projections indicate that in the future the number of NASA's robotic deep space missions is likely to increase significantly. A launch rate of up to 4-6 launches per year is projected with up to 25 simultaneous missions active [I]. Future high resolution mapping missions to other planetary bodies as well as other experiments are likely to require increased downlink capacity. These future deep space communications requirements will, according to baseline loading analysis, exceed the capacity of NASA's Deep Space Network in its present form. There are essentially two approaches for increasing the channel capacity of the Deep Space Network. Given the near-optimum performance of the network at the two deep space communications bands, S-Band (uplink 2.025-2.120 GHz, downlink 2.2-2.3 GHz), and X-Band (uplink 7.145-7.19 GHz, downlink 8.48.5 GHz), additional improvements bring only marginal return for the investment. Thus the only way to increase channel capacity is simply to construct more antennas, receivers, transmitters and other hardware. This approach is relatively low-risk but involves increasing both the number of assets in the network and operational costs.

Phosphorus K4 Crystal: A New Stable Allotrope

PubMed Central

Liu, Jie; Zhang, Shunhong; Guo, Yaguang; Wang, Qian

2016-01-01

The intriguing properties of phosphorene motivate scientists to further explore the structures and properties of phosphorus materials. Here, we report a new allotrope named K4 phosphorus composed of three-coordinated phosphorus atoms in non-layered structure which is not only dynamically and mechanically stable, but also possesses thermal stability comparable to that of the orthorhombic black phosphorus (A17). Due to its unique configuration, K4 phosphorus exhibits exceptional properties: it possesses a band gap of 1.54 eV which is much larger than that of black phosphorus (0.30 eV), and it is stiffer than black phosphorus. The band gap of the newly predicted phase can be effectively tuned by appling hydrostastic pressure. In addition, K4 phosphorus exibits a good light absorption in visible and near ultraviolet region. These findings add additional features to the phosphorus family with new potential applications in nanoelectronics and nanomechanics. PMID:27857232

Multi-Band Multi-Tone Tunable Millimeter-Wave Frequency Synthesizer For Satellite Beacon Transmitter

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.

2016-01-01

This paper presents the design and test results of a multi-band multi-tone tunable millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a satellite beacon transmitter for radio wave propagation studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). In addition, the architecture for a compact beacon transmitter, which includes the multi-tone synthesizer, polarizer, horn antenna, and power/control electronics, has been investigated for a notional space-to-ground radio wave propagation experiment payload on a small satellite. The above studies would enable the design of robust high throughput multi-Gbps data rate future space-to-ground satellite communication links.

High-resolution absorption cross section measurements of carbon monoxide at 20 K between 96.7 and 98.8 nanometers

NASA Technical Reports Server (NTRS)

Stark, G.; Yoshino, K.; Smith, P. L.; Esmond, J. R.; Ito, K.; Stevens, M. H.

1993-01-01

Photoabsorption cross sections for five CO bands, at wavelengths between 96.7 and 98.8 nm, have been measured at high-resolution in a supersonic jet-cooled source at the Photon Factory synchrotron facility. New integrated cross sections are reported for the K-X, L(prime)-X, and L-X bands. Low-temperature spectra of the J-X and W-X bands, which were used in the determination of the absorbing CO column densities, are also presented. The rotational structures of the K-X, L(prime)-X, and L-X bands do not overlap in the low-temperature spectra, allowing for the first unambiguous determination of these band oscillator strengths. We also report revised room temperature measurements of integrated cross sections for the K-X, L(prime)-X, and L-X bands, in which distortions in the measured spectra due to insufficient instrumental resolution have been minimized; the revised room temperature integrated cross sections are consistent with the low-temperature results.

Band structure of the quasi two-dimensional purple molybdenum bronze

NASA Astrophysics Data System (ADS)

Guyot, H.; Balaska, H.; Perrier, P.; Marcus, J.

2006-09-01

The molybdenum purple bronze KMo 6O 17 is quasi two-dimensional (2D) metallic oxide that shows a Peierls transition towards a metallic charge density wave state. Since this specific transition is directly related to the electron properties of the normal state, we have investigated the electronic structure of this bronze at room temperature. The shape of the Mo K1s absorption edge reveals the presence of distorted MoO 6 octahedra in the crystallographic structure. Photoemission experiments evidence a large conduction band, with a bandwidth of 800 meV and confirm the metallic character of this bronze. A wide depleted zone separates the conduction band from the valence band that exhibits a fourfold structure, directly connected to the octahedral symmetry of the Mo sites. The band structure is determined by ARUPS in two main directions of the (0 0 1) Brillouin zone. It exhibits some unpredicted features but corroborates the earlier theoretical band structure and Fermi surface. It confirms the hidden one-dimensionality of KMo 6O 17 that has been proposed to explain the origin of the Peierls transition in this 2D compound.

From lattice Hamiltonians to tunable band structures by lithographic design

NASA Astrophysics Data System (ADS)

Tadjine, Athmane; Allan, Guy; Delerue, Christophe

2016-08-01

Recently, new materials exhibiting exotic band structures characterized by Dirac cones, nontrivial flat bands, and band crossing points have been proposed on the basis of effective two-dimensional lattice Hamiltonians. Here, we show using atomistic tight-binding calculations that these theoretical predictions could be experimentally realized in the conduction band of superlattices nanolithographed in III-V and II-VI semiconductor ultrathin films. The lithographed patterns consist of periodic lattices of etched cylindrical holes that form potential barriers for the electrons in the quantum well. In the case of honeycomb lattices, the conduction minibands of the resulting artificial graphene host several Dirac cones and nontrivial flat bands. Similar features, but organized in different ways, in energy or in k -space are found in kagome, distorted honeycomb, and Lieb superlattices. Dirac cones extending over tens of meV could be obtained in superlattices with reasonable sizes of the lithographic patterns, for instance in InAs/AlSb heterostructures. Bilayer artificial graphene could be also realized by lithography of a double quantum-well heterostructure. These new materials should be interesting for the experimental exploration of Dirac-based quantum systems, for both fundamental and applied physics.

Prediction of settled water turbidity and optimal coagulant dosage in drinking water treatment plant using a hybrid model of k-means clustering and adaptive neuro-fuzzy inference system

NASA Astrophysics Data System (ADS)

Kim, Chan Moon; Parnichkun, Manukid

2017-11-01

Coagulation is an important process in drinking water treatment to attain acceptable treated water quality. However, the determination of coagulant dosage is still a challenging task for operators, because coagulation is nonlinear and complicated process. Feedback control to achieve the desired treated water quality is difficult due to lengthy process time. In this research, a hybrid of k-means clustering and adaptive neuro-fuzzy inference system ( k-means-ANFIS) is proposed for the settled water turbidity prediction and the optimal coagulant dosage determination using full-scale historical data. To build a well-adaptive model to different process states from influent water, raw water quality data are classified into four clusters according to its properties by a k-means clustering technique. The sub-models are developed individually on the basis of each clustered data set. Results reveal that the sub-models constructed by a hybrid k-means-ANFIS perform better than not only a single ANFIS model, but also seasonal models by artificial neural network (ANN). The finally completed model consisting of sub-models shows more accurate and consistent prediction ability than a single model of ANFIS and a single model of ANN based on all five evaluation indices. Therefore, the hybrid model of k-means-ANFIS can be employed as a robust tool for managing both treated water quality and production costs simultaneously.

Fast growth phenotype of E. coli K-12 from adaptive laboratory evolution does not require intracellular flux rewiring.

PubMed

Long, Christopher P; Gonzalez, Jacqueline E; Feist, Adam M; Palsson, Bernhard O; Antoniewicz, Maciek R

2017-11-01

Adaptive laboratory evolution (ALE) is a widely-used method for improving the fitness of microorganisms in selected environmental conditions. It has been applied previously to Escherichia coli K-12 MG1655 during aerobic exponential growth on glucose minimal media, a frequently used model organism and growth condition, to probe the limits of E. coli growth rate and gain insights into fast growth phenotypes. Previous studies have described up to 1.6-fold increases in growth rate following ALE, and have identified key causal genetic mutations and changes in transcriptional patterns. Here, we report for the first time intracellular metabolic fluxes for six such adaptively evolved strains, as determined by high-resolution 13 C-metabolic flux analysis. Interestingly, we found that intracellular metabolic pathway usage changed very little following adaptive evolution. Instead, at the level of central carbon metabolism the faster growth was facilitated by proportional increases in glucose uptake and all intracellular rates. Of the six evolved strains studied here, only one strain showed a small degree of flux rewiring, and this was also the strain with unique genetic mutations. A comparison of fluxes with two other wild-type (unevolved) E. coli strains, BW25113 and BL21, showed that inter-strain differences are greater than differences between the parental and evolved strains. Principal component analysis highlighted that nearly all flux differences (95%) between the nine strains were captured by only two principal components. The distance between measured and flux balance analysis predicted fluxes was also investigated. It suggested a relatively wide range of similar stoichiometric optima, which opens new questions about the path-dependency of adaptive evolution. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

High brightness photonic lantern kW-class amplifier

NASA Astrophysics Data System (ADS)

Montoya, Juan; Hwang, Chris; Aleshire, Chris; Reed, Patricia; Martz, Dale; Riley, Mike; Trainor, Michael; Belley, Catherine; Shaw, Scot; Fan, T. Y.; Ripin, Dan

2018-02-01

Pump-limited kW-class operation in a multimode fiber amplifier using adaptive mode control was achieved. A photonic lantern front end was used to inject an arbitrary superposition of modes on the input to a kW-class fiber amplifier to achieve a nearly diffraction-limited output. We report on the adaptive spatial mode control architecture which allows for compensating transverse-mode disturbances at high power. We also describe the advantages of adaptive spatial mode control for optical phased array systems. In particular, we show that the additional degrees of freedom allow for broader steering and improved atmospheric turbulence compensation relative to piston-only optical phased arrays.

Uniaxial strain on graphene: Raman spectroscopy study and band-gap opening.

PubMed

Ni, Zhen Hua; Yu, Ting; Lu, Yun Hao; Wang, Ying Ying; Feng, Yuan Ping; Shen, Ze Xiang

2008-11-25

Graphene was deposited on a transparent and flexible substrate, and tensile strain up to approximately 0.8% was loaded by stretching the substrate in one direction. Raman spectra of strained graphene show significant red shifts of 2D and G band (-27.8 and -14.2 cm(-1) per 1% strain, respectively) because of the elongation of the carbon-carbon bonds. This indicates that uniaxial strain has been successfully applied on graphene. We also proposed that, by applying uniaxial strain on graphene, tunable band gap at K point can be realized. First-principle calculations predicted a band-gap opening of approximately 300 meV for graphene under 1% uniaxial tensile strain. The strained graphene provides an alternative way to experimentally tune the band gap of graphene, which would be more efficient and more controllable than other methods that are used to open the band gap in graphene. Moreover, our results suggest that the flexible substrate is ready for such a strain process, and Raman spectroscopy can be used as an ultrasensitive method to determine the strain.

RED SUPERGIANT STARS AS COSMIC ABUNDANCE PROBES: NLTE EFFECTS IN J-BAND IRON AND TITANIUM LINES

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

Bergemann, Maria; Kudritzki, Rolf-Peter; Lind, Karin

2012-06-01

Detailed non-LTE (NLTE) calculations for red supergiant (RSG) stars are presented to investigate the influence of NLTE on the formation of atomic iron and titanium lines in the J band. With their enormous brightness at J band RSG stars are ideal probes of cosmic abundances. Recent LTE studies have found that metallicities accurate to 0.15 dex can be determined from medium-resolution spectroscopy of individual RSGs in galaxies as distant as 10 Mpc. The NLTE results obtained in this investigation support these findings. NLTE abundance corrections for iron are smaller than 0.05 dex for effective temperatures between 3400 K and 4200more » K and 0.1 dex at 4400 K. For titanium the NLTE abundance corrections vary smoothly between -0.4 dex and +0.2 dex as a function of effective temperature. For both elements, the corrections also depend on stellar gravity and metallicity. The physical reasons behind the NLTE corrections and the consequences for extragalactic J-band abundance studies are discussed.« less

Dual-Band Band-Pass Filter with Fixed Low Band and Fluidically-Tunable High Band

PubMed Central

Park, Eiyong; Lim, Daecheon

2017-01-01

In this work, we present a dual-band band-pass filter with fixed low-band resonant frequency and tunable high-band resonant frequency. The proposed filter consists of two split-ring resonators (SRRs) with a stub and microfluidic channels. The lower resonant frequency is determined by the length of the SRR alone, whereas the higher resonant frequency is determined by the lengths of the SRR and the stub. Using this characteristic, we fix the lower resonant frequency by fixing the SRR length and tune the higher resonant frequency by controlling the stub length by injecting liquid metal in the microfluidic channel. We fabricated the filter on a Duroid substrate. The microfluidic channel was made from polydimethylsiloxane (PDMS), and eutectic gallium–indium (EGaIn) was used as the liquid metal. This filter operates in two states—with, and without, the liquid metal. In the state without the liquid metal, the filter has resonant frequencies at 1.85 GHz and 3.06 GHz, with fractional bandwidths of 4.34% and 2.94%, respectively; and in the state with the liquid metal, it has resonant frequencies at 1.86 GHz and 2.98 GHz, with fractional bandwidths of 4.3% and 2.95%, respectively. PMID:28813001

Atmospheric absorption of high frequency noise and application to fractional-octave bands

NASA Technical Reports Server (NTRS)

Shields, F. D.; Bass, H. E.

1977-01-01

Pure tone sound absorption coefficients were measured at 1/12 octave intervals from 4 to 100 KHz at 5.5K temperature intervals between 255.4 and 310.9 K and at 10 percent relative humidity increments between 0 percent and saturation in a large cylindrical tube (i.d., 25.4 cm; length, 4.8 m). Special solid-dielectric capacitance transducers, one to generate bursts of sound waves and one to terminate the sound path and detect the tone bursts, were constructed to fit inside the tube. The absorption was measured by varying the transmitter receiver separation from 1 to 4 m and observing the decay of multiple reflections or change in amplitude of the first received burst. The resulting absorption was compared with that from a proposed procedure for computing sound absorption in still air. Absorption of bands of noise was numerically computed by using the pure tone results. The results depended on spectrum shape, on filter type, and nonlinearly on propagation distance. For some of the cases considered, comparison with the extrapolation of ARP-866A showed a difference as large as a factor of 2. However, for many cases, the absorption for a finite band was nearly equal to the pure tone absorption at the center frequency of the band. A recommended prediction procedure is described for 1/3 octave band absorption coefficients.

Nitrogen-broadened lines of ethane at 150 K

NASA Technical Reports Server (NTRS)

Chudamani, S.; Varanasi, P.; Giver, L. P.; Valero, F. P. J.

1985-01-01

Spectral transmittance has been measured in the nu9 fundamental band of C2H6 at 150 K using a Fourier transform spectrometer with apodized spectral resolution of 0.06/cm. Comparison of observed spectral transmittance with a line-by-line computation using the spectral catalog of Atakan et al. (1983) has yielded N2-broadened half-widths at 150 K.

Improved line parameters for the Chi 2Pi-Chi 2Pi (1-0) bands of (35)ClO and (37)ClO

NASA Technical Reports Server (NTRS)

Goldman, Aaron; Gillis, James R.; Rinsland, Curtis P.; Burkholder, James B.

1994-01-01

Improved line parameters at 296 K for the Chi 2Pi-Chi 2Pi (1-0) bands of (35)ClO and (37)ClO have been calculated with J up to 43.5. The integrated intensity for the 2048 lines in the main and satellite bands has been normalized to 9.68-sq cm/atm at 296K.

A Ka-band radial relativistic backward wave oscillator with GW-class output power

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

Zhu, Jiaxin; Zhang, Xiaoping, E-mail: zhangxiaoping@nudt.edu.cn; Dang, Fangchao

A novel radial relativistic backward wave oscillator with a reflector is proposed and designed to generate GW-level high power microwaves at Ka-band. The segmented radial slow wave structure and the reflector are matched to enhance interaction efficiency. We choose the volume wave TM{sub 01} mode as the working mode due to the volume wave characteristic. The main structural parameters of the novel device are optimized by particle-in-cell simulation. High power microwaves with power of 2 GW and a frequency of 29.4 GHz are generated with 30% efficiency when the electron beam voltage is 383 kV, the beam current is 17 kA, and themore » guiding magnetic field is only 0.6 T. Simultaneously, the highest electric field in the novel Ka-band device is just about 960 kV/cm in second slow wave structure.« less

Band Anticrossing in Highly Mismatched Compound Semiconductor Alloys

NASA Technical Reports Server (NTRS)

Yu, Kin Man; Wu, J.; Walukiewicz, W.; Ager, J. W.; Haller, E. E.; Miotkowski, I.; Ramdas, A.; Su, Ching-Hua; Whitaker, Ann F. (Technical Monitor)

2001-01-01

localized Se states and the conduction band. On the other hand we show that the large band gap reduction observed on the Se-rich side of the alloy system is a result of an interaction between the localized Te level and the valence bands. This interaction leads to the formation of a Te-like valence band edge that strongly interacts with the light hole valence band. Calculations based on a modified k p model account for the reduction of the band gap and the large increase of the spin-orbit splitting observed in Se-rich ZnSe(y)Te(l-y) alloys. We will also discuss the importance of these new results for understanding of the electronic structure and band offsets in other highly mismatched alloy systems.

Are the 'cave' minerals archerite (K,NH 4)H 2PO 4 and biphosphammite (K,NH 4)H 2PO 4 identical? A molecular structural study

NASA Astrophysics Data System (ADS)

Frost, Ray L.; Xi, Yunfei; Palmer, Sara J.

2011-08-01

The molecular structure of the mineral archerite ((K,NH 4)H 2PO 4) has been determined and compared with that of biphosphammite ((NH 4,K)H 2PO 4). Raman spectroscopy and infrared spectroscopy has been used to characterise these 'cave' minerals. Both minerals originated from the Murra-el-elevyn Cave, Eucla, Western Australia. The mineral is formed by the reaction of the chemicals in bat guano with calcite substrates. Raman and infrared bands are assigned to HPO4-, OH and NH stretching vibrations. The Raman band at 981 cm -1 is assigned to the HOP stretching vibration. Bands in the 1200-1800 cm -1 region are associated with NH4+ bending modes. The molecular structure of the two minerals appear to be very similar, and it is therefore concluded that the two minerals are identical.

Effective mass and Fermi surface complexity factor from ab initio band structure calculations

NASA Astrophysics Data System (ADS)

Gibbs, Zachary M.; Ricci, Francesco; Li, Guodong; Zhu, Hong; Persson, Kristin; Ceder, Gerbrand; Hautier, Geoffroy; Jain, Anubhav; Snyder, G. Jeffrey

2017-02-01

The effective mass is a convenient descriptor of the electronic band structure used to characterize the density of states and electron transport based on a free electron model. While effective mass is an excellent first-order descriptor in real systems, the exact value can have several definitions, each of which describe a different aspect of electron transport. Here we use Boltzmann transport calculations applied to ab initio band structures to extract a density-of-states effective mass from the Seebeck Coefficient and an inertial mass from the electrical conductivity to characterize the band structure irrespective of the exact scattering mechanism. We identify a Fermi Surface Complexity Factor: Nv*K* from the ratio of these two masses, which in simple cases depends on the number of Fermi surface pockets (Nv* ) and their anisotropy K*, both of which are beneficial to high thermoelectric performance as exemplified by the high values found in PbTe. The Fermi Surface Complexity factor can be used in high-throughput search of promising thermoelectric materials.

K-nearest neighbor imputation of forest inventory variables in New Hampshire

Treesearch

Andrew Lister; Michael Hoppus; Raymond L. Czaplewski

2005-01-01

The k-nearest neighbor (kNN) method was used to map stand volume for a mosaic of 4 Landsat scenes covering the state of New Hampshire. Data for gross cubic foot volume and trees per acre were summarized from USDA Forest Service Forest Inventory and Analysis (FIA) plots and used as training for kNN. Six bands of...

FTIR Synchrotron Spectroscopy of the Asymmetric C-H Stretching Bands of Methyl Mercaptan (CH3SH) - a Perplexity of Perturbations

NASA Astrophysics Data System (ADS)

Lees, Ronald M.; Xu, Li-Hong; Reid, Elias M.; Thapaliya, Bishnu P.; Dawadi, Mahesh B.; Perry, David S.; Twagirayezu, Sylvestre; Billinghurst, Brant E.

2016-06-01

The infrared Fourier transform spectrum of the asymmetric C-H stretching bands of CH3SH has been recorded in the 2950-3100 cm-1 region at Doppler limited resolution using synchrotron radiation at the FIR beamline of the Canadian Light Source in Saskatoon. Assignment of numerous torsion-rotation sub-bands for the asymmetric stretches has revealed a surprising pseudo-symmetric behavior, in which each band is seen in only one of the two possible ΔK selection rules. The upper states of the two asymmetric stretching vibrational bands thus appear to behave more like l = ± 1 components of a degenerate E state of a symmetric top rather than distinct vibrational states. The two components are separated by about 1.5 cm-1 at K = 0, and then diverge linearly at higher K with torsional oscillation amplitude similar to that of the ground state of about 1.3 cm-1. The divergence is consistent with an a-type Coriolis splitting picture with an effective Coriolis constant ζ ≈ 0.075.

A Ka-band chirped-pulse Fourier transform microwave spectrometer

NASA Astrophysics Data System (ADS)

Zaleski, Daniel P.; Neill, Justin L.; Muckle, Matt T.; Seifert, Nathan A.; Brandon Carroll, P.; Widicus Weaver, Susanna L.; Pate, Brooks H.

2012-10-01

The design and performance of a new chirped-pulse Fourier transform microwave (CP-FTMW) spectrometer operating from 25 to 40 GHz (Ka-band) is presented. This spectrometer is well-suited for the study of complex organic molecules of astronomical interest in the size range of 6-10 atoms that have strong rotational transitions in Ka-band under pulsed jet sample conditions (Trot = 1-10 K). The spectrometer permits acquisition of the full spectral band in a single data acquisition event. Sensitivity is enhanced by using two pulsed jet sources and acquiring 10 broadband measurements for each sample injection cycle. The spectrometer performance is benchmarked by measuring the pure rotational spectrum of several isotopologues of acetaldehyde in natural abundance. The rotational spectra of the singly substituted 13C and 18O isotopologues of the two lowest energy conformers of ethyl formate have been analyzed and the resulting substitution structures for these conformers are compared to electronic structure theory calculations.

Atmospheric solar heating rate in the water vapor bands

NASA Technical Reports Server (NTRS)

Chou, Ming-Dah

1986-01-01

The total absorption of solar radiation by water vapor in clear atmospheres is parameterized as a simple function of the scaled water vapor amount. For applications to cloudy and hazy atmospheres, the flux-weighted k-distribution functions are computed for individual absorption bands and for the total near-infrared region. The parameterization is based upon monochromatic calculations and follows essentially the scaling approximation of Chou and Arking, but the effect of temperature variation with height is taken into account in order to enhance the accuracy. Furthermore, the spectral range is extended to cover the two weak bands centered at 0.72 and 0.82 micron. Comparisons with monochromatic calculations show that the atmospheric heating rate and the surface radiation can be accurately computed from the parameterization. Comparisons are also made with other parameterizations. It is found that the absorption of solar radiation can be computed reasonably well using the Goody band model and the Curtis-Godson approximation.

Relaxation Matrix for Symmetric Tops with Inversion Symmetry: Line Coupling and Line Mixing Effects on NH3 Lines in the V4 Band

NASA Technical Reports Server (NTRS)

Ma, Q.; Boulet, C.; Tipping, R. H.

2017-01-01

Line shape parameters including the half-widths and the off-diagonal elements of the relaxation matrix have been calculated for self-broadened NH3 lines in the perpendicular v4 band. As in the pure rotational and the parallel v1 bands, the small inversion splitting in this band causes a complete failure of the isolated line approximation. As a result, one has to use formalisms not relying on this approximation. However, due to differences between parallel and perpendicular bands of NH3, the applicability of the formalism used in our previous studies of the v1 band and other parallel bands must be carefully verified. We have found that, as long as potential models only contain components with K1 equals K2 equals 0, whose matrix elements require the selection rule delta k equals 0, the formalism is applicable for the v4 band with some minor adjustments. Based on both theoretical considerations and results from numerical calculations, the non-diagonality of the relaxation matrices in all the PP, RP, PQ, RQ, PR, and RR branches is discussed. Theoretically calculated self-broadened half-widths are compared with measurements and the values listed in HITRAN 2012. With respect to line coupling effects, we have compared our calculated intra-doublet off-diagonal elements of the relaxation matrix with reliable measurements carried out in the PP branch where the spectral environment is favorable. The agreement is rather good since our results do well reproduce the observed k and j dependences of these elements, thus validating our formalism.

High-Performance Solid-State W-Band Power Amplifiers

NASA Technical Reports Server (NTRS)

Gaier, Todd; Samoska, Lorene; Wells, Mary; Ferber, Robert; Pearson, John; Campbell, April; Peralta, Alejandro; Swift, Gerald; Yocum, Paul; Chung, Yun

2003-01-01

The figure shows one of four solid-state power amplifiers, each capable of generating an output power greater than or equal to 240 mW over one of four overlapping frequency bands from 71 to 106 GHz. (The bands are 71 to 84, 80 to 92, 88 to 99, and 89 to 106 GHz.) The amplifiers are designed for optimum performance at a temperature of 130 K. These amplifiers were developed specifically for incorporation into frequency-multiplier chains in local oscillators in a low-noise, far-infrared receiving instrument to be launched into outer space to make astrophysical observations. The designs of these amplifiers may also be of interest to designers and manufacturers of terrestrial W-band communication and radar systems. Each amplifier includes a set of six high-electron-mobility transistor (HEMT) GaAs monolithic microwave integrated-circuit (MMIC) chips, microstrip cavities, and other components packaged in a housing made from A-40 silicon-aluminum alloy. This alloy was chosen because, for the original intended spacecraft application, it offers an acceptable compromise among the partially competing requirements for high thermal conductivity, low mass, and low thermal expansion. Problems that were solved in designing the amplifiers included designing connectors and packages to fit the available space; designing microstrip signal-power splitters and combiners; matching of impedances across the frequency bands; matching of the electrical characteristics of those chips installed in parallel power-combining arms; control and levelling of output power across the bands; and designing the MMICs, microstrips, and microstrip cavities to suppress tendencies toward oscillation in several modes, both inside and outside the desired frequency bands.

Strain-induced band-gap engineering of graphene monoxide and its effect on graphene

NASA Astrophysics Data System (ADS)

Pu, H. H.; Rhim, S. H.; Hirschmugl, C. J.; Gajdardziska-Josifovska, M.; Weinert, M.; Chen, J. H.

2013-02-01

Using first-principles calculations we demonstrate the feasibility of band-gap engineering in two-dimensional crystalline graphene monoxide (GMO), a recently reported graphene-based material with a 1:1 carbon/oxygen ratio. The band gap of GMO, which can be switched between direct and indirect, is tunable over a large range (0-1.35 eV) for accessible strains. Electron and hole transport occurs predominantly along the zigzag and armchair directions (armchair for both) when GMO is a direct- (indirect-) gap semiconductor. A band gap of ˜0.5 eV is also induced in graphene at the K' points for GMO/graphene hybrid systems.

Search for inversion splitting in the 3ν2 band of phosphine

NASA Astrophysics Data System (ADS)

Okuda, Shoko; Sasada, Hiroyuki

2018-04-01

Sub-Doppler resolution spectroscopy of the 3ν2 band of phosphine has been carried out using a difference-frequency-generation source referenced to an optical frequency comb and a cavity-enhanced absorption cell. Three Q-branch transitions are recorded with a linewidth of 150 kHz, but no inversion splitting is observed even though it was predicted 300 kHz in Journal of Chemical Physics, vol. 145, art. No. 091102 (2016). Transition frequencies of six Q-branch transitions have been determined with an uncertainty of 6-16 kHz.

Direct imaging of band profile in single layer MoS2 on graphite: quasiparticle energy gap, metallic edge states, and edge band bending.

PubMed

Zhang, Chendong; Johnson, Amber; Hsu, Chang-Lung; Li, Lain-Jong; Shih, Chih-Kang

2014-05-14

Using scanning tunneling microscopy and spectroscopy, we probe the electronic structures of single layer MoS2 on graphite. The apparent quasiparticle energy gap of single layer MoS2 is measured to be 2.15 ± 0.06 eV at 77 K, albeit a higher second conduction band threshold at 0.2 eV above the apparent conduction band minimum is also observed. Combining it with photoluminescence studies, we deduce an exciton binding energy of 0.22 ± 0.1 eV (or 0.42 eV if the second threshold is use), a value that is lower than current theoretical predictions. Consistent with theoretical predictions, we directly observe metallic edge states of single layer MoS2. In the bulk region of MoS2, the Fermi level is located at 1.8 eV above the valence band maximum, possibly due to the formation of a graphite/MoS2 heterojunction. At the edge, however, we observe an upward band bending of 0.6 eV within a short depletion length of about 5 nm, analogous to the phenomena of Fermi level pinning of a 3D semiconductor by metallic surface states.

Banding patterns and chromosomal evolution in five species of neotropical Teiinae lizards (Squamata: Teiidae).

PubMed

dos Santos, Rodrigo Marques Lima; Pellegrino, Katia Cristina Machado; Rodrigues, Miguel Trefaut; Yonenaga-Yassuda, Yatiyo

2007-11-01

Karyotypes of five species of South American teiid lizards from subfamily Teiinae: Ameiva ameiva, Kentropyx calcarata, K. paulensis, K. vanzoi (2n = 50, all acrocentric), and Cnemidophorus ocellifer (2n = 50, all biarmed), are herein described and compared on the basis of conventional and silver staining, and CBG and RBG banding patterns. Meiotic data are also included. Karyotypes of K. paulensis, K. vanzoi, and C. ocellifer are reported here for the first time. Inter-generic variability in Ag-NORs location was detected with NORs occurring at the end of long arm of pair 1 in K. calcarata, K. paulensis, and K. vanzoi; pair 5 in C. ocellifer and pair 7 in A. ameiva. The location of NORs, along with the karyological differences between A. ameiva and the Central American species (A. auberi), corroboretes the molecular-based hypothesis that the genus Ameiva is paraphyletic. Inter-populational heteromorphism in Ag-NORs size was detected between populations of C. ocellifer. RBG and CBG banding data demonstrated that the biarmed condition of the C. ocellifer chromosomes is due to multiple pericentric inversion events instead of addition of constitutive heterochromatin. Differential-staining techniques used here revealed valuable information about Teiinae karyotypic diversity and made it possible to compare these species, contributing to both the better comprehension of their chromosomal evolution and issues on taxa systematics.

Solar Data in the J and H Bands (Abstract)

NASA Astrophysics Data System (ADS)

Howe, R.

2017-06-01

(Abstract only) Early work of stellar astronomers established the nomenclature for the infrared wavelength bands in the 1,000 to 5,000 nm range known as J, H, K, L, and M. This study is using the AAVSO SSP-4 photometer to collect solar data in the J and H bands, where the central wavelengths of these bands are roughly 1,300 nm for the J, and 1,600 nm for the H band. The continuum radiation from the sun is formed at the deepest level in the sun around 40 km from the surface at 1,600 nm (H band), and then the spectral continuum begins as the height increases with increasing wavelength in the infrared spectrum. From data collected here the H band has slightly larger values than the J band, however, there are distinct cross-overs on different days of observing. The telescope being used is a 60-mm LUNT, a blocking factor of 12 with a tilt-etalon filter (https://luntsolarsystems.com/product/ls60tds/) which can be adjusted to look at "white light"; and in that configuration the SSP-4 photometer captures the sun's disc centered in the SSP-4 eyepiece (1 inch focal length 25.4 mm). The Orion equatorial mount has an Astro-view Right Accession motor, which tracks the sun, and for an average data capture session of about 10 minutes, it is quite stable. Capturing data in the early morning is best as the weight of the SSP-4 helps the little RA motor rather than in the afternoon when the balance would be against the direction of the earth's rotation.

Theoretical studies on band structure and optical gain of GaInAsN/GaAs /GaAs cylindrical quantum dot

NASA Astrophysics Data System (ADS)

Mal, Indranil; Samajdar, Dip Prakash; John Peter, A.

2018-07-01

Electronic band structure, effective masses, band offsets and optical gain of Ga0.661In0.339N0.0554As0.9446/GaAs quantum dot systems are investigated using 10 band k·p Hamiltonian for various nitrogen and indium concentrations. The calculations include the effects of strain generated due to the lattice mismatch and the effective band gap of GaInAsN/GaAs heterostructures. The variation of conduction band, light hole and heavy hole band offsets with indium and nitrogen compositions in the alloy are obtained. The band structure of Ga0.661In0.339N0.0554As0.9446/GaAs quantum dot is found in the crystal directions Δ (100) and Λ (111) using 10 band k·p Hamiltonian. The optical gain of the cylindrical quantum dot structures as functions of surface carrier concentration and the dot radius is investigated. Our results show that the tensile strain of 1.34% generates a band gap of 0.59 eV and the compressive strain of 2.2% produces a band gap of 1.28 eV and the introduction of N atoms has no effect on the spin orbit split off band. The variation of optical gain with the dot size and the carrier concentration indicates that the optical gain increases with the decrease in the radius of the quantum dot. The results may be useful for the potential applications in optical devices.

On-line, adaptive state estimator for active noise control