Relative properties of smooth terminating bands

NASA Astrophysics Data System (ADS)

Afanasjev, A. V.; Ragnarsson, I.

1998-01-01

The relative properties of smooth terminating bands observed in the A ∼ 110 mass region are studied within the effective alignment approach. Theoretical values of ietf are calculated using the configuration-dependent shell-correction model with the cranked Nilsson potential. Reasonable agreement with experiment shows that previous interpretations of these bands are consistent with the present study. Contrary to the case of superdeformed bands, the effective alignments of these bands deviate significantly from the pure single-particle alignments of the corresponding orbitals. This indicates that in the case of smooth terminating bands, the effects associated with changes in equilibrium deformations contribute significantly to the effective alignment.

High-spin terminating states in the N = 88 Ho 155 and Er 156 isotones

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

Rees, J. M.; Paul, E. S.; Simpson, J.

2015-05-01

The Sn-124(Cl-37, 6n gamma) fusion-evaporation reaction at a bombarding energy of 180 MeV has been used to significantly extend the excitation level scheme of Ho-155(67)88. The collective rotational behavior of this nucleus breaks down above spin I similar to 30 and a fully aligned noncollective (band terminating) state has been identified at I-pi = 79/2(-). Comparison with cranked Nilsson-Strutinsky calculations also provides evidence for core-excited noncollective states at I-pi = 87/2(-) and (89/2(+)) involving particle-hole excitations across the Z = 64 shell gap. A similar core-excited state in Er-156(68)88 at I-pi = (46(+)) is also presented.

Ka-band propagation studies using the ACTS propagation terminal and the CSU-CHILL multiparameter, Doppler radar

NASA Technical Reports Server (NTRS)

Beaver, J.; Turk, J.; Bringi, V. N.

1995-01-01

An increase in the demand for satellite communications has led to an overcrowding of the current spectrums being used - mainly at C and Ku bands. To alleviate this overcrowding, new technology is being developed to open up the Ka-band for communications use. One of the first experimental communications satellites using this technology is NASA's Advanced Communications Technology Satellite (ACTS). In Sept. 1993, ACTS was deployed into a geostationary orbit near 100 deg W longitude. The ACTS system employs two Ka-band beacons for propagation experiments, one at 20.185 GHz and another at 27.505 GHz. Attenuation due to rain and tropospheric scintillations will adversely affect new technologies proposed for this spectrum. Therefore, before being used commercially, propagation effects at Ka-band must be studied. Colorado State University is one of eight sites across the United States and Canada conducting propagations studies; each site is equipped with the ACTS propagation terminal (APT). With each site located in a different climatic zone, the main objective of the propagation experiment is to obtain monthly and yearly attenuation statistics. Each site also has secondary objectives that are site dependent. At CSU, the CSU-CHILL radar facility is being used to obtain polarimetric radar data along the ACTS propagation path. During the expected two to four year period of the project, it is hoped to study several significant weather events. The S-band radar will be used to obtain Ka-band attenuation estimates and to initialize propagation models that have been developed, to help classify propagation events measured by the APT. Preliminary attenuation estimates for two attenuation events will be shown here - a bright band case that occurred on 13 May 1994 and a convective case that occurred on 20 Jun. 1994. The computations used to obtain Ka-band attenuation estimates from S-band radar data are detailed. Results from the two events are shown.

Condition-dependent expression of melanin-based coloration in the Eurasian kestrel

NASA Astrophysics Data System (ADS)

Piault, Romain; van den Brink, Valentijn; Roulin, Alexandre

2012-05-01

Melanin is the most common pigment in animal integuments and is responsible for some of the most striking ornaments. A central tenet of sexual selection theory states that melanin-based traits can signal absolute individual quality in any environment only if their expression is condition-dependent. Significant costs imposed by an ornament would ensure that only the highest quality individuals display the most exaggerated forms of the signal. Firm evidence that melanin-based traits can be condition-dependent is still rare in birds. In an experimental test of this central assumption, we report condition-dependent expression of a melanin-based trait in the Eurasian kestrel ( Falco tinnunculus). We manipulated nestling body condition by reducing or increasing the number of nestlings soon after hatching. A few days before fledging, we measured the width of sub-terminal black bands on the tail feathers. Compared to nestlings from enlarged broods, individuals raised in reduced broods were in better condition and thereby developed larger sub-terminal bands. Furthermore, in 2 years, first-born nestlings also developed larger sub-terminal bands than their younger siblings that are in poorer condition. This demonstrates that expression of melanin-based traits can be condition-dependent.

Ligand Field Strength Mediates Electron Delocalization in Octahedral [((H)L)2Fe6(L')m](n+) Clusters.

PubMed

Hernández Sánchez, Raúl; Zheng, Shao-Liang; Betley, Theodore A

2015-09-02

To assess the impact of terminal ligand binding on a variety of cluster properties (redox delocalization, ground-state stabilization, and breadth of redox state accessibility), we prepared three electron-transfer series based on the hexanuclear iron cluster [((H)L)2Fe6(L')m](n+) in which the terminal ligand field strength was modulated from weak to strong (L' = DMF, MeCN, CN). The extent of intracore M-M interactions is gauged by M-M distances, spin ground state persistence, and preference for mixed-valence states as determined by electrochemical comproportionation constants. Coordination of DMF to the [((H)L)2Fe6] core leads to weaker Fe-Fe interactions, as manifested by the observation of ground states populated only at lower temperatures (<100 K) and by the greater evidence of valence trapping within the mixed-valence states. Comproportionation constants determined electrochemically (Kc = 10(4)-10(8)) indicate that the redox series exhibits electronic delocalization (class II-III), yet no intervalence charge transfer (IVCT) bands are observable in the near-IR spectra. Ligation of the stronger σ donor acetonitrile results in stabilization of spin ground states to higher temperatures (∼300 K) and a high degree of valence delocalization (Kc = 10(2)-10(8)) with observable IVCT bands. Finally, the anionic cyanide-bound series reveals the highest degree of valence delocalization with the most intense IVCT bands (Kc = 10(12)-10(20)) and spin ground state population beyond room temperature. Across the series, at a given formal oxidation level, the capping ligand on the hexairon cluster dictates the overall properties of the aggregate, modulating the redox delocalization and the persistence of the intracore coupling of the metal sites.

Electronic transport in disordered MoS2 nanoribbons

NASA Astrophysics Data System (ADS)

Ridolfi, Emilia; Lima, Leandro R. F.; Mucciolo, Eduardo R.; Lewenkopf, Caio H.

2017-01-01

We study the electronic structure and transport properties of zigzag and armchair monolayer molybdenum disulfide nanoribbons using an 11-band tight-binding model that accurately reproduces the material's bulk band structure near the band gap. We study the electronic properties of pristine zigzag and armchair nanoribbons, paying particular attention to the edges states that appear within the MoS2 bulk gap. By analyzing both their orbital composition and their local density of states, we find that in zigzag-terminated nanoribbons these states can be localized at a single edge for certain energies independent of the nanoribbon width. We also study the effects of disorder in these systems using the recursive Green's function technique. We show that for the zigzag nanoribbons, the conductance due to the edge states is strongly suppressed by short-range disorder such as vacancies. In contrast, the local density of states still shows edge localization. We also show that long-range disorder has a small effect on the transport properties of nanoribbons within the bulk gap energy window.

Trivalent cerium coped crystals as tunable laser systems: two bad apples

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

Hamilton, D.S.

1985-01-01

The 5d-4f transitions of trivalent doped crystals have broad emission bands with large oscillator strengths and near unity quantum efficiency. These characteristics make cerium systems strong candidates for tunable solid state lasers. However, two such cerium crystals will probably never lase. The first is Ce/sup 3 +/:YAG where a strong excited state absorption quenches the lasing transition. Our recent measurements have indicated that the excited state absorption terminates in the YAG conduction band with a peak cross section of 1.0 x 10/sup -17/ cm/sup 2/ at 700 nm. Some of the general features of impurity ion to band spectra aremore » discussed. The second system is Ce/sup 3 +/:CaF/sub 2/ where a uv pump induced photochromic center is produced following excitation of the cerium ions. The initial measurements of cerium related transient absorptions in Ce/sup 3 +/:YLF are also presented.« less

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.

First-principles calculations of different (001) surface terminations of three cubic perovskites CsCaBr3, CsGeBr3, and CsSnBr3

NASA Astrophysics Data System (ADS)

Ma, C.-G.; Krasnenko, V.; Brik, M. G.

2018-04-01

Three cubic bromide perovskites CsMBr3 (M = Ca, Ge, Sn) with two different surface terminations (CsBr and MBr2) were studied in this work using the first principles method. A wide range of physical properties, including electronic band structures, atom-projected density of states for each layer, surface relaxation effects, and surface energy, were evaluated for each considered surface termination. Differences between the properties of the bulk and slab models were highlighted. It was shown that surfaces with the CsBr termination have a lower energy and a more pronounced surface rumpling than those with the MBr2 termination. As a main result of this study, it was demonstrated that the CsBr-terminated surfaces appear to be energetically more stable in each of these three considered perovskites.

Influence of GaAs surface termination on GaSb/GaAs quantum dot structure and band offsets

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

Zech, E. S.; Chang, A. S.; Martin, A. J.

2013-08-19

We have investigated the influence of GaAs surface termination on the nanoscale structure and band offsets of GaSb/GaAs quantum dots (QDs) grown by molecular-beam epitaxy. Transmission electron microscopy reveals both coherent and semi-coherent clusters, as well as misfit dislocations, independent of surface termination. Cross-sectional scanning tunneling microscopy and spectroscopy reveal clustered GaSb QDs with type I band offsets at the GaSb/GaAs interfaces. We discuss the relative influences of strain and QD clustering on the band offsets at GaSb/GaAs interfaces.

Reactive Landing of Dendrimer Ions onto Activated Self-assembled Monolayer Surfaces

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

Hu, Qichi; Laskin, Julia

2014-02-06

The reactivity of gaseous, amine-terminated polyamidoamine (PAMAM) dendrimer ions with activated self-assembled monolayer (SAM) surfaces terminated with N-hydroxysuccinimidyl ester groups (NHS-SAM) is examined using mass-selected ion deposition combined with in situ infrared reflection absorption spectroscopy (IRRAS). The reaction extent is determined from depletion of the infrared band at 1753 cm-1, corresponding to the stretching vibration of the NHS carbonyl groups following ion deposition. For reaction yields below 10%, NHS band depletion follows a linear dependence on the ion dose. By comparing the kinetics plots obtained for 1,12-dodecanediamine and different generations of dendrimer ions (G0–G3) containing 4, 8, 16, and 32more » terminal amino group, we demonstrate that the relative reaction efficiency increases linearly with the number of NH2 groups in the molecule. This finding is rationalized assuming the formation of multiple amide bonds upon collision of higher-generation dendrimers with NHS-SAM. Furthermore, by comparing the NHS band depletion following deposition of [M+4H]4+ ions of the G2 dendrimer at 30, 80, and 120 eV, we demonstrate that the ion’s kinetic energy has no measurable effect on reaction efficiency. Similarly, the ion’s charge state only has a minor effect on the reactive landing efficiency of dendrimer ions. Our results indicate that reactive landing is an efficient approach for highly selective covalent immobilization of complex multifunctional molecules onto organic surfaces terminated with labile functional groups.« less

Experiments for Ka-band mobile applications: The ACTS mobile terminal

NASA Technical Reports Server (NTRS)

Estabrook, Polly; Dessouky, Khaled; Jedrey, Thomas

1990-01-01

To explore the potential of Ka-band to support mobile satellite services, the Jet Propulsion Laboratory (JPL) has initiated the design and development of a Ka-band land-mobile terminal to be used with the Advanced Communications Technology Satellite (ACTS). The planned experimental setup with ACTS is described. Brief functional descriptions of the mobile and fixed terminals are provided. The inputs required from the propagation community to support the design activities and the planned experiments are also discussed.

Elucidation of the electronic states in polyethylene glycol by attenuated Total reflectance spectroscopy in the far-ultraviolet region

NASA Astrophysics Data System (ADS)

Ueno, Nami; Wakabayashi, Tomonari; Morisawa, Yusuke

2018-05-01

We measured the attenuated total reflectance-far ultraviolet (ATR-FUV) spectra of poly(ethylene glycol) (PEG; average molecular weights of 200, 300, and 400) and related materials in the liquid state in the 145-200-nm wavelength region. For appropriately assigning the absorption bands, we also performed theoretical simulation of the unit-number dependent electronic spectra. The FUV spectra of PEGs contain three bands, which are assigned to the transitions between n(CH2OCH2)-3s Rydberg state (176 nm), n(CH2OCH2)-3p Rydberg state (163 nm), and n(OH)-3p Rydberg state (153 nm). Since the contribution of n(OH) decreases compared to n(CH2OCH2) with increase in the number of units, the ratios of the molar absorption coefficients, ε, at 153 nm relative to 163 nm, decrease. On the other hand, the ratio of ε at 176 nm to that at 163 nm increases with increase in the number of units, because of the difference in the number of unoccupied orbitals in the transitions. The calculated results suggest that n orbitals form two electronic bands. In the upper band, the electrons expand over the ether chain, whereas in the lower band, the electrons are localized in the terminal OH in the PEGs.

Accurate determination of the valence band edge in hard x-ray photoemission spectra using GW theory

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

Lischner, Johannes, E-mail: jlischner597@gmail.com; Department of Physics and Department of Materials and the Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, London SW7 2AZ; Nemšák, Slavomír

We introduce a new method for determining accurate values of the valence-band maximum in x-ray photoemission spectra. Specifically, we align the sharpest peak in the valence-band region of the experimental spectrum with the corresponding feature of a theoretical valence-band density of states curve from ab initio GW theory calculations. This method is particularly useful for soft and hard x-ray photoemission studies of materials with a mixture of valence-band characters, where strong matrix element effects can render standard methods for extracting the valence-band maximum unreliable. We apply our method to hydrogen-terminated boron-doped diamond, which is a promising substrate material for novelmore » solar cell devices. By carrying out photoemission experiments with variable light polarizations, we verify the accuracy of our analysis and the general validity of the method.« less

Quasiparticles and charge transfer at the two surfaces of the honeycomb iridate Na2IrO3

NASA Astrophysics Data System (ADS)

Moreschini, L.; Lo Vecchio, I.; Breznay, N. P.; Moser, S.; Ulstrup, S.; Koch, R.; Wirjo, J.; Jozwiak, C.; Kim, K. S.; Rotenberg, E.; Bostwick, A.; Analytis, J. G.; Lanzara, A.

2017-10-01

Direct experimental investigations of the low-energy electronic structure of the Na2IrO3 iridate insulator are sparse and draw two conflicting pictures. One relies on flat bands and a clear gap, the other involves dispersive states approaching the Fermi level, pointing to surface metallicity. Here, by a combination of angle-resolved photoemission, photoemission electron microscopy, and x-ray absorption, we show that the correct picture is more complex and involves an anomalous band, arising from charge transfer from Na atoms to Ir-derived states. Bulk quasiparticles do exist, but in one of the two possible surface terminations the charge transfer is smaller and they remain elusive.

Ka-band Technologies for Small Spacecraft Communications via Relays and Direct Data Downlink

NASA Technical Reports Server (NTRS)

Budinger, James M.; Niederhaus, Charles; Reinhart, Richard; Downey, Joe; Roberts, Anthony

2016-01-01

As the scientific capabilities and number of small spacecraft missions in the near Earth region increase, standard yet configurable user spacecraft terminals operating in Ka-band are needed to lower mission cost and risk and enable significantly higher data return than current UHF or S-band terminals. These compact Ka-band terminals are intended to operate with both the current and next generation of Ka-band relay satellites and via direct data communications with near Earth tracking terminals. This presentation provides an overview of emerging NASA-sponsored and commercially provided technologies in software defined radios (SDRs), transceivers, and electronically steered antennas that will enable data rates from hundreds of kbps to over 1 Gbps and operate in multiple frequency bands (such as S- and X-bands) and expand the use of NASA's common Ka-bands frequencies: 22.55-23.15 GHz for forward data or uplink; and 25.5-27.0 GHz for return data or downlink. Reductions in mass, power and volume come from integration of multiple radio functions, operations in Ka-band, high efficiency amplifiers and receivers, and compact, flat and vibration free electronically steered narrow beam antennas for up to + 60 degrees field of regard. The software defined near Earth space transceiver (SD-NEST) described in the presentation is intended to be compliant with NASA's space telecommunications radio system (STRS) standard for communications waveforms and hardware interoperability.

Surface thermodynamic stability, electronic and magnetic properties in various (001) surfaces of Zr2CoSn Heusler alloy

NASA Astrophysics Data System (ADS)

Yang, Yan; Feng, Zhong-Ying; Zhang, Jian-Min

2018-05-01

The spin-polarized first-principles are used to study the surface thermodynamic stability, electronic and magnetic properties in various (001) surfaces of Zr2CoSn Heusler alloy, and the bulk Zr2CoSn Heusler alloy are also discussed to make comparison. The conduction band minimum (CBM) of half-metallic (HM) bulk Zr2CoSn alloy is contributed by ZrA, ZrB and Co atoms, while the valence band maximum (VBM) is contributed by ZrB and Co atoms. The SnSn termination is the most stable surface with the highest spin polarizations P = 77.1% among the CoCo, ZrCo, ZrZr, ZrSn and SnSn terminations of the Zr2CoSn (001) surface. In the SnSn termination of the Zr2CoSn (001) surface, the atomic partial density of states (APDOS) of atoms in the surface, subsurface and third layers are much influenced by the surface effect and the total magnetic moment (TMM) is mainly contributed by the atomic magnetic moments of atoms in fourth to ninth layers.

The MSAT spacecraft of Telesat Mobile, Inc.

NASA Astrophysics Data System (ADS)

Bertenyi, E.

The Canadian MSAT system will offer a mobile telephone, radio, and data services. The last two will be offered via feederlink earth stations. The earth stations will use a 13 GHz Ku-band uplink and an L-band for downlink from the satellite to mobile earth terminals. User access will be controlled by a network control center. The basic service area of MSAT includes the part of Canada which is accessible from the geostationary orbit of 106.5 deg W as well as the continental USA. The satellite will have a minimum service life of ten years. The main elements of the communication subsystem are the antennas which include two large unfurlable L-band reflectors and their feed elements, the cross-polarized Ku-band antenna, the L-band and Ku-band receivers, the up-down converters each serving one antennal beam, and the Ku-band travelling wave tube amplifiers and L-band solid state power amplifiers. Voice and data services are expected to be available in 1994.

ATS-6 - Technical aspects of the Health/Education Telecommunications Experiment

NASA Technical Reports Server (NTRS)

Boor, J. L.; Braunstein, J.; Janky, J. M.; Ogden, D.; Potter, J. G.; Harper, E. L.; Volkmer, E.; Whalen, A. A.; Henderson, E.; Hupe, H. H.

1975-01-01

An overview is given of the HET experiment on ATS-6. The paper is divided into nine parts, including a technical overview, a preliminary evaluation of the HET demonstration, a review of operations at the Denver uplink terminal, a discussion of remote ground terminals, a review of C-band comprehensive terminals and of S-band comprehensive terminals, and parts devoted to general network operations, technical management and effectiveness of the network, and the site equipment operator.

47 CFR 25.134 - Licensing provisions for Very Small Aperture Terminal (VSAT) and C-band Small Aperture Terminal...

Code of Federal Regulations, 2014 CFR

2014-10-01

... Applications and Licenses Earth Stations § 25.134 Licensing provisions for Very Small Aperture Terminal (VSAT... affected adjacent satellite operators by the operation of the non-conforming earth station. (b) VSAT...) VSAT networks operating in the 12/14 GHz bands may use more than one hub earth station, and the hubs...

Small Bowel Obstruction due to Anomalous Congenital Bands in Children.

PubMed

Erginel, Basak; Soysal, Feryal Gun; Ozbey, Huseyin; Keskin, Erbug; Celik, Alaattin; Karadag, Aslı; Salman, Tansu

2016-01-01

Introduction. The aim of the study was to evaluate our children who are operated on for anomalous congenital band while increasing the awareness of this rare reason of intestinal obstruction in children which causes a diagnostic challenge. Patients and Methods. We retrospectively reviewed the records of fourteen children treated surgically for intestinal obstructions caused by anomalous congenital bands. Results. The bands were located between the following regions: the ascending colon and the mesentery of the terminal ileum in 4 patients, the jejunum and mesentery of the terminal ileum in 3 patients, the ileum and mesentery of the terminal ileum in 2 patients, the ligament of Treitz and mesentery of the jejunum in one patient, the ligament of Treitz and mesentery of the terminal ileum in one patient, duodenum and duodenum in one patient, the ileum and mesentery of the ileum in one patient, the jejunum and mesentery of the jejunum in one patient, and Meckel's diverticulum and its ileal mesentery in one patient. Band excision was adequate in all of the patients except the two who received resection anastomosis for intestinal necrosis. Conclusion. Although congenital anomalous bands are rare, they should be considered in the differential diagnosis of patients with an intestinal obstruction.

47 CFR 25.134 - Licensing provisions of Very Small Aperture Terminal (VSAT) and C-band Small Aperture Terminal...

Code of Federal Regulations, 2012 CFR

2012-10-01

... Applications and Licenses Earth Stations § 25.134 Licensing provisions of Very Small Aperture Terminal (VSAT... maximum outbound downlink EIRP density of +10.0 dBW/4 kHz per carrier and earth station antennas with... Order in the Matter of Routine Licensing of Earth Stations in the 6 GHz and 14 GHz Bands Using Antennas...

47 CFR 25.134 - Licensing provisions for Very Small Aperture Terminal (VSAT) and C-band Small Aperture Terminal...

Code of Federal Regulations, 2013 CFR

2013-10-01

... Applications and Licenses Earth Stations § 25.134 Licensing provisions for Very Small Aperture Terminal (VSAT... maximum outbound downlink EIRP density of +10.0 dBW/4 kHz per carrier and earth station antennas with... Order in the Matter of Routine Licensing of Earth Stations in the 6 GHz and 14 GHz Bands Using Antennas...

Electron Transport in Multi-Terminal Graphene Nanodevice with Inclined Cross Structures

NASA Astrophysics Data System (ADS)

Ye, En-Jia; Shi, Yi-Jian; Zhao, Xuean

2014-12-01

The DC and AC transport properties are investigated in multi-terminal graphene nanoribbon (GNR) devices. The devices are composed of three or four graphene ribbons connected with different angles. It is found that DC and AC conductances depend on the structural configurations and ribbon properties. In the vicinity of Dirac point, the intersection of graphene ribbons forms band mixing and results in resonant or anti-resonant states. The edge and width, as well as, the angles of the graphene ribbons influence the DC and AC transport properties drastically. These properties can be used to build future graphene-based nanoelectronics.

ACTS Ka-Band Earth Stations: Technology, Performance, and Lessons Learned

NASA Technical Reports Server (NTRS)

Reinhart, Richard C.; Struharik, Steven J.; Diamond, John J.; Stewart, David

2000-01-01

The Advanced Communications Technology Satellite (ACTS) Project invested heavily in prototype Ka-band satellite ground terminals to conduct an experiments program with ACTS. The ACTS experiments program proposed to validate Ka-band satellite and ground-station technology, demonstrate future telecommunication services, demonstrate commercial viability and market acceptability of these new services, evaluate system networking and processing technology, and characterize Ka-band propagation effects, including development of techniques to mitigate signal fading. This paper will present a summary of the fixed ground terminals developed by the NASA Glenn Research Center and its industry partners, emphasizing the technology and performance of the terminals and the lessons learned throughout their 6-year operation, including the inclined orbit phase-of-operations. The fixed ground stations used for experiments by government, academic, and commercial entities used reflector-based offset-fed antenna systems with antennas ranging in size from 0.35 to 3.4 in. in diameter. Gateway earth stations included two systems referred to as the NASA Ground Station (NGS) and the Link Evaluation Terminal (LET).

1D-TlInSe2: Band Structure, Dielectric Function and Nanorods

NASA Astrophysics Data System (ADS)

Mamedov, Nazim; Wakita, Kazuki; Akita, Seiji; Nakayama, Yoshikazu

2005-01-01

Linear combination of atomic orbitals (LCAO) analysis of the electronic band states has been completed for one-dimensional (1D) TlInSe2 having rod-like ground state shape of bulky crystal. The total scenario of the occurrence of the band states from the atomic states has been established. According to this scenario, in dipole approximation the optical transitions at band gap (point T of Brillouin zone) are either entirely forbidden or allowed for T2-T10 transitions in e\\perpc configuration provided that either initial or terminate state has T2 symmetry and both are Se-like. As a whole, the obtained results on the electronic spectrum, including dielectric function, are applicable to all obtained 1D-TlInSe2 nanorods which were as thin as 30--50 nm in cross-section, and apparently preserved tetragonal crystal structure of bulky material. The thermal instabilities developing already in bulky samples of 1D-TlInSe2 are considered to be an ultimate source of the nanoparticles emerging in plenty during nanorods preparation. The nanoplates of a chemically similar but 2D material, TlInS2, are demonstrated for comparison to show the absence of nanoparticles in that case. A possibility of nanoparticle preparation using laser excited coherent phonon trains in the nanorods of 1D-TlInSe2 is figured out.

Ab initio simulations of water splitting on hematite

NASA Astrophysics Data System (ADS)

Seriani, Nicola

2017-11-01

In recent years, hematite has attracted great interest as a photocatalyst for water splitting, but many questions remain unanswered about the mechanisms and the main limiting factors. For this reason, density functional theory has been used to understand the optical, electronic and chemical properties of this material at an atomistic level. Bulk doping can be used to reduce the band gap, and to increase photoabsorption and charge mobility. Charge transport takes place through adiabatic polaron hopping. The stable (0 0 0 1) surface has a stoichiometric termination when exposed to oxygen, it becomes hydroxylated in water, and it has an oxygen-rich termination under illumination in a photoelectrochemical setup. On the oxygen-rich termination, surface states are present that might act as recombination centres for electrons and holes. On the contrary, on the hydroxylated termination surface states appear only on reaction intermediates. The intrinsic surface states disappear in the presence of an overlayer of gallium oxide. The reaction of water oxidation is assumed to proceed by four proton-coupled electron transfers and it is shown to involve a nucleophilic attack with the formation of an OOH group. Calculated overpotentials are in the range of 0.5-0.6 V. Open questions and future research directions are briefly discussed.

Universal behavior of surface-dangling bonds in hydrogen-terminated Si, Ge, and Si/Ge nanowires.

NASA Astrophysics Data System (ADS)

Nunes, Ricardo; Kagimura, Ricardo; Chacham, Hélio

2007-03-01

We report an ab initio study of the electronic properties of surface dangling bond (SDB) states in hydrogen-terminated Si, Ge, and Si/Ge nanowires with diameters between 1 and 2 nm. We find that the charge transition levels ɛ(+/-) of SDB states are deep in the bandgap for Si wires, and shallow (near the valence band edge) for Ge wires. In both Si and Ge wires, the SDB states are localized. We also find that the SDB ɛ(+/-) levels behave as a ``universal" energy reference level among Si, Ge, and Si/Ge wires within a precision of 0.1 eV. By computing the average bewteen the electron affinity and ionization energy in the atomi limit of several atoms from the III, IV and V columns, we conjecture that the universality is a periodic-table atomic property.

The interface of SrTiO3 and H2O from density functional theory molecular dynamics

PubMed Central

Spijker, P.; Foster, A. S.

2016-01-01

We use dispersion-corrected density functional theory molecular dynamics simulations to predict the ionic, electronic and vibrational properties of the SrTiO3/H2O solid–liquid interface. Approximately 50% of surface oxygens on the planar SrO termination are hydroxylated at all studied levels of water coverage, the corresponding number being 15% for the planar TiO2 termination and 5% on the stepped TiO2-terminated surface. The lateral ordering of the hydration structure is largely controlled by covalent-like surface cation to H2O bonding and surface corrugation. We find a featureless electronic density of states in and around the band gap energy region at the solid–liquid interface. The vibrational spectrum indicates redshifting of the O–H stretching band due to surface-to-liquid hydrogen bonding and blueshifting due to high-frequency stretching vibrations of OH fragments within the liquid, as well as strong suppression of the OH stretching band on the stepped surface. We find highly varying rates of proton transfer above different SrTiO3 surfaces, owing to differences in hydrogen bond strength and the degree of dissociation of incident water. Trends in proton dynamics and the mode of H2O adsorption among studied surfaces can be explained by the differential ionicity of the Ti–O and Sr–O bonds in the SrTiO3 crystal. PMID:27713660

A geostationary satellite system for mobile multimedia applications using portable, aeronautical and mobile terminals

NASA Technical Reports Server (NTRS)

Losquadro, G.; Luglio, M.; Vatalaro, F.

1997-01-01

A geostationary satellite system for mobile multimedia services via portable, aeronautical and mobile terminals was developed within the framework of the Advanced Communications Technology Service (ACTS) programs. The architecture of the system developed under the 'satellite extremely high frequency communications for multimedia mobile services (SECOMS)/ACTS broadband aeronautical terminal experiment' (ABATE) project is presented. The system will be composed of a Ka band system component, and an extremely high frequency band component. The major characteristics of the space segment, the ground control station and the portable, aeronautical and mobile user terminals are outlined.

Mapping the Coulomb Environment in Interference-Quenched Ballistic Nanowires.

PubMed

Gutstein, D; Lynall, D; Nair, S V; Savelyev, I; Blumin, M; Ercolani, D; Ruda, H E

2018-01-10

The conductance of semiconductor nanowires is strongly dependent on their electrostatic history because of the overwhelming influence of charged surface and interface states on electron confinement and scattering. We show that InAs nanowire field-effect transistor devices can be conditioned to suppress resonances that obscure quantized conduction thereby revealing as many as six sub-bands in the conductance spectra as the Fermi-level is swept across the sub-band energies. The energy level spectra extracted from conductance, coupled with detailed modeling shows the significance of the interface state charge distribution revealing the Coulomb landscape of the nanowire device. Inclusion of self-consistent Coulomb potentials, the measured geometrical shape of the nanowire, the gate geometry and nonparabolicity of the conduction band provide a quantitative and accurate description of the confinement potential and resulting energy level structure. Surfaces of the nanowire terminated by HfO 2 are shown to have their interface donor density reduced by a factor of 30 signifying the passivating role played by HfO 2 .

Termination and the Eastern Band of Cherokees.

ERIC Educational Resources Information Center

Finger, John R.

1991-01-01

During the 1940s and 1950s, local factors helped the Eastern Cherokees to resist termination of tribal status and federal responsibilities in Indian affairs. Factors include the belief that area tourism depended on Cherokee tribal identity, reluctance of local public schools to accept Indian students, and the band's complex legal status and…

Perovskite-perovskite tandem photovoltaics with optimized band gaps

NASA Astrophysics Data System (ADS)

Eperon, Giles E.; Leijtens, Tomas; Bush, Kevin A.; Prasanna, Rohit; Green, Thomas; Wang, Jacob Tse-Wei; McMeekin, David P.; Volonakis, George; Milot, Rebecca L.; May, Richard; Palmstrom, Axel; Slotcavage, Daniel J.; Belisle, Rebecca A.; Patel, Jay B.; Parrott, Elizabeth S.; Sutton, Rebecca J.; Ma, Wen; Moghadam, Farhad; Conings, Bert; Babayigit, Aslihan; Boyen, Hans-Gerd; Bent, Stacey; Giustino, Feliciano; Herz, Laura M.; Johnston, Michael B.; McGehee, Michael D.; Snaith, Henry J.

2016-11-01

We demonstrate four- and two-terminal perovskite-perovskite tandem solar cells with ideally matched band gaps. We develop an infrared-absorbing 1.2-electron volt band-gap perovskite, FA0.75Cs0.25Sn0.5Pb0.5I3, that can deliver 14.8% efficiency. By combining this material with a wider-band gap FA0.83Cs0.17Pb(I0.5Br0.5)3 material, we achieve monolithic two-terminal tandem efficiencies of 17.0% with >1.65-volt open-circuit voltage. We also make mechanically stacked four-terminal tandem cells and obtain 20.3% efficiency. Notably, we find that our infrared-absorbing perovskite cells exhibit excellent thermal and atmospheric stability, not previously achieved for Sn-based perovskites. This device architecture and materials set will enable “all-perovskite” thin-film solar cells to reach the highest efficiencies in the long term at the lowest costs.

Afferent innervation of the utricular macula in pigeons

NASA Technical Reports Server (NTRS)

Si, Xiaohong; Zakir, Mridha Md; Dickman, J. David

2003-01-01

Biotinylated dextran amine (BDA) was used to retrogradely label afferents innervating the utricular macula in adult pigeons. The pigeon utriclar macula consists of a large rectangular-shaped neuroepithelium with a dorsally curved anterior edge and an extended medioposterior tail. The macula could be demarcated into several regions based on cytoarchitectural differences. The striola occupied 30% of the macula and contained a large density of type I hair cells with fewer type II hair cells. Medial and lateral extrastriola zones were located outside the striola and contained only type II hair cells. A six- to eight-cell-wide band of type II hair cells existed near the center of the striola. The reversal line marked by the morphological polarization of hair cells coursed throughout the epithelium, near the peripheral margin, and through the center of the type II band. Calyx afferents innervated type I hair cells with calyceal terminals that contained between 2 and 15 receptor cells. Calyx afferents were located only in the striola region, exclusive of the type II band, had small total fiber innervation areas and low innervation densities. Dimorph afferents innervated both type I and type II hair cells with calyceal and bouton terminals and were primarily located in the striola region. Dimorph afferents had smaller calyceal terminals with few type I hair cells, extended fiber branches with bouton terminals and larger innervation areas. Bouton afferents innervated only type II hair cells in the extrastriola and type II band regions. Bouton afferents innervating the type II band had smaller terminal fields with fewer bouton terminals and smaller innervation areas than fibers located in the extrastriolar zones. Bouton afferents had the most bouton terminals on the longest fibers, the largest innervation areas with the highest innervation densities of all afferents. Among all afferents, smaller terminal innervation fields were observed in the striola and large fields were located in the extrastriola. The cellular organization and innervation patterns of the utricular maculae in birds appear to represent an organ in adaptive evolution, different from that observed for amphibians or mammals.

Airborne Satcom Terminal Research at NASA Glenn

NASA Technical Reports Server (NTRS)

Hoder, Doug; Zakrajsek, Robert

2002-01-01

NASA Glenn has constructed an airborne Ku-band satellite terminal, which provides wideband full-duplex ground-aircraft communications. The terminal makes use of novel electronically-steered phased array antennas and provides IP connectivity to and from the ground. The satcom terminal communications equipment may be easily changed whenever a new configuration is required, enhancing the terminal's versatility.

EMI survey for maritime satellite 1535-1645-MHz shipboard terminal

NASA Technical Reports Server (NTRS)

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

1977-01-01

A 15,690-ton commercial container ship was selected as lead ship for an onboard electromagnetic-interference (EMI) survey prior to installation of 1535-1645-MHz (L-Band) shipboard terminals for communication via a maritime satellite. In general, the EMI survey revealed tolerable interference levels on board ship. Radiometer measurements indicate antenna-noise temperatures less than 70 K at elevation angles of 5 deg and greater at 1559 MHz at the output terminals of the 1.2-m diameter parabolic-dish antenna for the L-band shipboard terminal. Other EMI measurements include field intensity from 3-cm and 10-cm wavelength pulse radars, and conducted-emission tests of primary power lines to both onboard radars.

Dimensions and Measurements of Debuncher Band 1 and 2 Waveguide-Coax Launchers (Final Version)

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

Sun, Ding; /Fermilab

2000-02-15

This note is a document about dimensions and measurement results of waveguide-coax launchers (Band 1 and 2) installed on the arrays in debuncher cooling upgrade. Shown in Figure 1, 5, 8 and 12 are schematic drawings of launchers in the cross section along the longitudinal direction (beam direction) of the arrays. The unit in these drawings is inch. Note: although there are upper band and lower band for pickup arrays, the launchers are the same to avoid possible confusion during installation. RF Measurements were made on all launchers (port) and printed in hard copies for future reference. Since the measurementmore » results are similar to each other, only a few plots for each type of launcher/band are presented in this document. There are two types of measured S11 parameters. One is the measurement made at the end of design/tuning stage using a straight section of band 1 or 2 waveguide terminated with a cone of absorber. I use 'Original' to denote this kind of measurement. As shown in Figure 2, 6, 9 and 13, the original S11 of all launchers are below or around - 20 db over the full band 1 or 2. The other type of measurement is the one made after these launchers were installed onto the array including elbows and several type N feedthrough or connectors. The kicker arrays were terminated with wedges of absorber. During all measurements (pickup array or kicker array) when one launcher was being measured, all other launchers were terminated with 50 ohm terminator. As shown in Figure 3, 4, 7, 10, 11 and 14 these 'final' S11s are around -15 db.« less

Satellite Communications for Aeronautics Applications: Technology Development and Demonstration

NASA Technical Reports Server (NTRS)

Kerczewski, Robert J.; Hoder, Douglas J.; Zakrajsek, Robert J.

2001-01-01

The National Aeronautics and Space Administration (NASA) is performing research and development to improve the safety and increase the capacity of the National Airspace System (NAS). Improved communications, especially to and from the aircraft flight deck, has been identified as an essential enabling technology for future improvements to the air traffic management system and aviation safety. NASA's Glenn Research Center is engaged in research and development of satellite communications technologies for aeronautical applications. A mobile aero terminal has been developed for use with Ku band commercial communications satellites. This experimental terminal will be used in mobile ground and air-based tests and demonstrations during 2000-2004. This paper will describe the basic operational parameters of the Ku Band aero terminal, the communications architecture it is intended to demonstrate, and the key technology issues being addressed in the tests and demonstrations. The design of the Ku Band aero terminal and associated ground testbed, planned tests and demonstrations, and results to date will be presented.

Low cost Ku-band earth terminals for voice/data/facsimile

NASA Technical Reports Server (NTRS)

Kelley, R. L.

1977-01-01

A Ku-band satellite earth terminal capable of providing two way voice/facsimile teleconferencing, 128 Kbps data, telephone, and high-speed imagery services is proposed. Optimized terminal cost and configuration are presented as a function of FDMA and TDMA approaches to multiple access. The entire terminal from the antenna to microphones, speakers and facsimile equipment is considered. Component cost versus performance has been projected as a function of size of the procurement and predicted hardware innovations and production techniques through 1985. The lowest cost combinations of components has been determined in a computer optimization algorithm. The system requirements including terminal EIRP and G/T, satellite size, power per spacecraft transponder, satellite antenna characteristics, and link propagation outage were selected using a computerized system cost/performance optimization algorithm. System cost and terminal cost and performance requirements are presented as a function of the size of a nationwide U.S. network. Service costs are compared with typical conference travel costs to show the viability of the proposed terminal.

Optically Unraveling the Edge Chirality-Dependent Band Structure and Plasmon Damping in Graphene Edges.

PubMed

Duan, Jiahua; Chen, Runkun; Cheng, Yuan; Yang, Tianzhong; Zhai, Feng; Dai, Qing; Chen, Jianing

2018-05-01

The nontrivial topological origin and pseudospinorial character of electron wavefunctions make edge states possess unusual electronic properties. Twenty years ago, the tight-binding model calculation predicted that zigzag termination of 2D sheets of carbon atoms have peculiar edge states, which show potential application in spintronics and modern information technologies. Although scanning probe microscopy is employed to capture this phenomenon, the experimental demonstration of its optical response remains challenging. Here, the propagating graphene plasmon provides an edge-selective polaritonic probe to directly detect and control the electronic edge state at ambient condition. Compared with armchair, the edge-band structure in the bandgap gives rise to additional optical absorption and strongly absorbed rim at zigzag edge. Furthermore, the optical conductivity is reconstructed and the anisotropic plasmon damping in graphene systems is revealed. The reported approach paves the way for detecting edge-specific phenomena in other van der Waals materials and topological insulators. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface Coverage and Metallicity of ZnO Surfaces from First-Principles Calculations

NASA Astrophysics Data System (ADS)

Zhang, Xiao; Schleife, Andre; The Schleife research Group Team

Zinc oxide (ZnO) surfaces are widely used in different applications such as catalysis, biosensing, and solar cells. These surfaces are, in many cases, chemically terminated by hydroxyl groups. In experiment, a transition of the ZnO surface electronic properties from semiconducting to metallic was reported upon increasing the hydroxyl coverage to more than approximately 80 %. The reason for this transition is not well understood yet. We report on first-principles calculations based on density functional theory for the ZnO [ 10 1 0 ] surface, taking different amounts of hydroxyl coverage into account. We calculated band structures for fully relaxed configurations and verified the existence of this transition. However, we only find the fully covered surface to be metallic. We thus explore the possibility for clustering of the surface-terminating hydroxyl groups based on total-energy calculations. We also found that the valence band maximum consists of oxygen p states from both the surface hydroxyl groups and the surface oxygen atoms of the material. The main contribution to the metallicity is found to be from the hydroxyl groups.

Envisaging Structural Insight of a Terminally Protected Proline Dipeptide by Raman Spectroscopy and Density Functional Theory Analyses.

PubMed

Das, Supriya; Pal, Uttam; Chatterjee, Moumita; Pramanik, Sumit Kumar; Banerji, Biswadip; Maiti, Nakul C

2016-12-15

The proline residue in a protein sequence generates constraints to its secondary structure as the associated torsion angles become a part of the heterocyclic ring. It becomes more significant when two consecutive proline residues link via amide linkage and produce additional configurational constraint to a protein's folding and stability. In the current manuscript we have illustrated conformation preference of a novel dipeptide, (R)-tert-butyl 2-((S)-2-(methoxycarbonyl)pyrrolidine-1-carbonyl)pyrrolidine-1-carboxylate. The dipeptide crystallized in the orthorhombic crystalline state and produced rod-shaped macroscopic material. The analysis of the crystal coordinates showed dihedral angles (φ, ψ) of the interlinked amide groups as (+72°, -147°) and the dihedral angles (φ, ψ) produced with the next carbonyl were (-68°, +151°), indicating polyglycine II (PGII) and polyproline II (PPII)-like helix states at the N- and C-terminals, respectively. These two states, PGII and PPII, are mirror image configurations and are expected to produce similar vibration bands from the associated carbonyl groups. However, the unique atomic arrangement in the molecule produces three carbonyl groups and one of them was very specific, being part of the main peptide linkage that connects both the pyrrolidine rings. The carbonyl group in the peptide bond exhibited a Raman vibration frequency at ∼1642 cm -1 and is considered a signatory Raman marker band for the peptide bond linking two heterochiral proline residues. The carbonyl group (t-Boc) at the N-terminal of the peptide showed a characteristic vibration at ∼1685 cm -1 and the C-terminal carbonyl group as a part of the ester showed a vibration signature at a significantly high frequency (1746 cm -1 ). Conformation analyses performed with density functional theory (DFT) calculations depicted that the dipeptide was stabilized in vacuum with dihedral angles (+72°, -154°) and (-72°, +151°) at the N- and C-terminals, respectively. Molecular dynamics (MD) simulation also showed that the peptide conformation having dihedral angles around (+75°, -150°) and (-75°, +150°) at the N- and C-terminals, respectively, was reasonably stable in water. Due to unique absence of the amide N-H, the peptide was ineffective in forming any intramolecular hydrogen bonding. MD investigation, however, revealed an intermolecular hydrogen bonding interaction with the water molecules, leading to its stability in aqueous solution. Metadynamics simulation analysis of the dipeptide in water also supported the PGII-PPII-like conformation at the N- and C-terminals, respectively, as the energetically stable conformation among the other possible combinations of conformations. The possible electronic transitions along with the HOMO-LUMO analysis further depicted the stability of the dipeptide in water and their possible absorption pattern. Time-dependent density functional theory (TDDFT) analysis showed strong negative rotatory strength of the dipeptide around 210 nm in water and acetonitrile, and it could be the source of experimentally observed high-amplitude negative absorption in the circular dichroism (CD) spectra around 200-203 nm. The very weak positive band (signature) in the region at ∼228 nm in CD spectra could also be correlated to the positive rotatory strength at 228 nm observed in ECD. To test the effect of such a dipeptide on a living cell, an MTT assay was performed and the result indicated no cytotoxic effect toward human hepatocellular carcinoma Hep G2 cancer cell lines.

Observation of a nodal chain with Dirac surface states in Ti B2

NASA Astrophysics Data System (ADS)

Yi, C.-J.; Lv, B. Q.; Wu, Q. S.; Fu, B.-B.; Gao, X.; Yang, M.; Peng, X.-L.; Li, M.; Huang, Y.-B.; Richard, P.; Shi, M.; Li, G.; Yazyev, Oleg V.; Shi, Y.-G.; Qian, T.; Ding, H.

2018-05-01

Topological nodal-line semimetals (TNLSMs) are characterized by symmetry-protected band crossings extending along one-dimensional lines in momentum space. The nodal lines exhibit a variety of possible configurations, such as nodal ring, nodal link, nodal chain, and nodal knot. Here, using angle-resolved photoemission spectroscopy, we observe nodal rings on the orthogonal kz=0 and kx=0 planes of the Brillouin zone in Ti B2 . The nodal rings connect with each other on the intersecting line Γ-K of the orthogonal planes forming a remarkable nodal-chain structure. Furthermore, we observe surface states (SSs) on the (001) cleaved surface, which are consistent with the calculated SSs considering the contribution from both Ti and B terminations. The calculated SSs have novel Dirac-cone-like band structures, which are distinct from the usual drumhead SSs with a single flatband proposed in other TNLSMs.

TDRSS S-shuttle unique receiver equipment

NASA Astrophysics Data System (ADS)

Weinberg, A.; Schwartz, J. J.; Spearing, R.

1985-01-01

Beginning with STS-9, the Tracking and Date Relay Satellite system (TDRSS) will start providing S- and Ku-band communications and tracking support to the Space Shuttle and its payloads. The most significant element of this support takes place at the TDRSS White Sands Ground Terminal, which processes the Shuttle return link S- and Ku-band signals. While Ku-band hardware available to other TDRSS users is also applied to Ku-Shuttle, stringent S-Shuttle link margins have precluded the application of the standard TDRSS S-band processing equipment to S-Shuttle. It was therfore found necessary to develop a unique S-Shuttle Receiver that embodies state-of-the-art digital technology and processing techniques. This receiver, developed by Motorola, Inc., enhances link margins by 1.5 dB relative to the standard S-band equipment and its bit error rate performance is within a few tenths of a dB of theory. An overview description of the Space Shuttle Receiver Equipment (SSRE) is presented which includes the presentation of block diagrams and salient design features. Selected, measured performance results are also presented.

Probing topological Fermi-Arcs and bulk boundary correspondence in the Weyl semimetal TaAs

NASA Astrophysics Data System (ADS)

Batabyal, Rajib; Morali, Noam; Avraham, Nurit; Sun, Yan; Schmidt, Marcus; Felser, Claudia; Stern, Ady; Yan, Binghai; Beidenkopf, Haim

The relation between surface Fermi-arcs and bulk Weyl cones in a Weyl semimetal, uniquely allows to study the notion of bulk to surface correspondence. We visualize these topological Fermi arc states on the surface of the Weyl semi-metal tantalum arsenide using scanning tunneling spectroscopy. Its surface hosts 12 Fermi arcs amongst several other surface bands of non-topological origin. We detect the possible scattering processes of surface bands in which Fermi arcs are involved including intra- and inter arc scatterings and arc-trivial scatterings. Each of the measured scattering processes entails additional information on the unique nature of Fermi arcs in tantalum arsenide: their contour, their energy-momentum dispersion and its relation with the bulk Weyl nodes. We further identify a sharp distinction between the wave function's spatial distribution of topological versus trivial bands. The non-topological surface bands, which are derived from the arsenic dangling bonds, are tightly bound to the arsenic termination layer. In contrast, the Fermi-arc bands reside on the deeper tantalum layer, penetrating into the bulk, which is predominantly derived from tantalum orbitals.

Dimensions and Measurements of Debuncher Band 3 and 4 Waveguide-Coax Launchers

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

Sun, Ding; /Fermilab

2000-09-13

This note is a document about dimensions and measurement results of waveguide-coax launchers (Band 3 and 4) installed on the arrays in debuncher cooling upgrade. Shown in Figure 1 and 5 are schematic drawings of launchers (pick-up) in the cross section along the longitudinal direction (beam direction) of the arrays. The unit in these drawings is inch. Note: although there are upper band and lower band for pickup arrays, the launchers are the same to avoid possible confusion during installation. Launchers for band 3 and 4 kickers were made by Penn-engineering Inc., therefor no schematic drawings are presented in thismore » note. RF Measurements were made on all launchers (port) and printed in hard copies for future reference. Since the measurement results are similar to each other, only a few plots for each type of launcher/band are presented in this document. There are two types of measured S11 parameters. One is the measurement made at the end of design/tuning stage using a launcher and a straight section of band 3 or 4 waveguide terminated with a cone of absorber. I use 'Original' to denote this kind of measurement. As shown in Figure 2, 6, 9 and 12, the original S11 of all launchers are below or around -20 db over the full band 3 or 4. The other type of measurement is the one made after these launchers were installed onto the array including several type N feedthrough or connectors, elbows, waveguide bends (kicker) and magic Ts (kicker) etc. The kicker arrays were terminated with wedges of absorber. During all measurements (pickup array or kicker array) when one launcher was being measured, all other launchers were terminated with 50 ohm terminator. As shown in Figure 3, 4, 7, 8, 10, 11, 13 and 14 these 'final' S11s are around -15 db.« less

Microstructure and conductance-slope of InAs/GaSb tunnel diodes

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

Iutzi, Ryan M., E-mail: iutzi@mit.edu; Fitzgerald, Eugene A.

2014-06-21

InAs/GaSb and similar materials systems have generated great interest as a heterojunction for tunnel field effect transistors (TFETs) due to favorable band alignment. However, little is currently understood about how such TFETs are affected by materials defects and nonidealities. We present measurements of the conductance slope for various InAs/GaSb heterojunctions via two-terminal electrical measurements, which removes three-terminal parasitics and enables direct study on the effect of microstructure on tunnelling. Using this, we can predict how subthreshold swings in TFETs can depend on microstructure. We also demonstrate growth and electrical characterization for structures grown by metalorganic chemical vapor deposition (MOCVD)—a generallymore » more scalable process compared with molecular beam epitaxy (MBE). We determine that misfit dislocations and point defects near the interface can lead to energy states in the band-gap and local band bending that result in trap-assisted leakage routes and nonuniform band alignment across the junction area that lower the steepness of the conductance slope. Despite the small lattice mismatch, misfit dislocations still form in InAs on GaSb due to relaxation as a result of large strain from intermixed compositions. This can be circumvented by growing GaSb on InAs, straining the GaSb underlayer, or lowering the InAs growth temperature in the region of the interface. The conductance slope can also be improved by annealing the samples at higher temperatures, which we believe acts to annihilate point defects and average out major fluctuations in band alignment across the interface. Using a combination of these techniques, we can greatly improve the steepness of the conductance slope which could result in steeper subthreshold swings in TFETs in the future.« less

Effects of Edge on-Site Potential in a Honeycomb Topological Magnon Insulator

NASA Astrophysics Data System (ADS)

Pantaleón, Pierre A.; Xian, Yang

2018-06-01

While the deviation of the edge on-site potential from the bulk values in a magnonic topological honeycomb lattice leads to the formation of edge states in a bearded boundary, this is not the case for a zigzag termination, where no edge state is found. In a semi-infinite lattice, the intrinsic on-site interactions along the boundary sites generate an effective defect and this gives rise to Tamm-like edge states. If a nontrivial gap is induced, both Tamm-like and topologically protected edge states appear in the band structure. The effective defect can be strengthened by an external on-site potential, and the dispersion relation, velocity and magnon density of the edge states all become tunable.

Stability and band offsets between c-plane ZnO semiconductor and LaAlO3 gate dielectric

NASA Astrophysics Data System (ADS)

Wang, Jianli; Chen, Xinfeng; Wu, Shuyin; Tang, Gang; Zhang, Junting; Stampfl, C.

2018-03-01

Wurtzite-perovskite heterostructures composed of a high dielectric constant oxide and a wide bandgap semiconductor envision promising applications in field-effect transistors. In the present paper, the structural and electronic properties of LaAlO3/ZnO heterojunctions are investigated by first-principles calculations. We study the initial adsorption of La, Al, and oxygen atoms on ZnO (0001) and (000 1 ¯ ) surfaces and find that La atoms may occupy interstitial sites during the growth of stoichiometric ZnO (0001). The band gap of the stoichiometric ZnO (0001) surface is smaller than that of the stoichiometric ZnO (000 1 ¯ ) surface. The surface formation energy indicates that La or Al atoms may substitute Zn atoms at the nonstoichiometric ZnO (0001) surface. The atomic charges, electronic density of states, and band offsets are analyzed for the optimized LaAlO3/ZnO heterojunctions. There is a band gap for the LaAlO3/ZnO (000 1 ¯ ) heterostructures, and the largest variation in charge occurs at the surface or interface. Our results suggest that the Al-terminated LaAlO3/ZnO (000 1 ¯ ) interfaces are suitable for the design of metal oxide semiconductor devices because the valence and conduction band offsets are both larger than 1 eV and the interface does not produce any in-gap states.

Generation of a complete set of human telomeric band painting probes by chromosome microdissection.

PubMed

Hu, Liang; Sham, Jonathan S T; Tjia, Wai Mui; Tan, Yue-qiu; Lu, Guang-xiu; Guan, Xin-Yuan

2004-02-01

Chromosomal rearrangements involving telomeric bands have been frequently detected in many malignancies and congenital diseases. To develop a useful tool to study chromosomal rearrangements within the telomeric band effectively and accurately, a whole set of telomeric band painting probes (TBP) has been generated by chromosome microdissection. The intensity and specificity of these TBPs have been tested by fluorescence in situ hybridization and all TBPs showed strong and specific signals to target regions. TBPs of 6q and 17p were successfully used to detect the loss of the terminal band of 6q in a hepatocellular carcinoma cell line and a complex translocation involving the 17p terminal band in a melanoma cell line. Meanwhile, the TBP of 21q was used to detect a de novo translocation, t(12;21), and the breakpoint at 21q was located at 21q22.2. Further application of these TBPs should greatly facilitate the cytogenetic analysis of complex chromosome rearrangements involving telomeric bands.

A theoretical investigation of the (0001) covellite surfaces

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

Gaspari, Roberto, E-mail: roberto.gaspari@iit.it; Manna, Liberato; Cavalli, Andrea

2014-07-28

We report on the properties of the (0001) covellites surfaces, which we investigate by periodic slab density functional theory calculations. The absolute surface energies have been computed for all bulk terminations, showing that surfaces terminated by the flat CuS layer are associated with the lowest surface energy. Cleavage is predicted to occur across the [0001] interlayer Cu–S bond. The surfaces obtained by lowest energy cleavage are analyzed in terms of the atomic vertical relaxation, workfunction, and surface band structure. Our study predicts the presence of a shallow p{sub z}-derived surface state located 0.26 eV below the Fermi level, which ismore » set to play an important role in the surface reactivity of covellite.« less

Olympus propagation studies in the US: Propagation terminal hardware and experiments

NASA Technical Reports Server (NTRS)

Stutzmzn, Warren L.

1990-01-01

Virginia Tech is performing a comprehensive set of propagation measurements using the Olympus satellite beacons at 12.5, 20, and 30 GHz. These data will be used to characterize propagation conditions on small earth terminal (VSAT)-type networks for next generation small aperture Ka-band systems. The European Space Agency (ESA) satellite Olympus was launched July 12, 1989. The spacecraft contains a sophisticated package of propagation beacons operating at 12.5, 19.77, and 29.66 GHz (referred to as 12.5, 20, and 30 beacons). These beacons cover the east coast of the United States with sufficient power for attenuation measurements. The Virginia Satellite Communications Group is completing the hardware construction phase and will begin formal data collection in June.

The cytoskeletal binding domain of band 3 is required for multiprotein complex formation and retention during erythropoiesis.

PubMed

Satchwell, Timothy J; Hawley, Bethan R; Bell, Amanda J; Ribeiro, M Leticia; Toye, Ashley M

2015-01-01

Band 3 is the most abundant protein in the erythrocyte membrane and forms the core of a major multiprotein complex. The absence of band 3 in human erythrocytes has only been reported once, in the homozygous band 3 Coimbra patient. We used in vitro culture of erythroblasts derived from this patient, and separately short hairpin RNA-mediated depletion of band 3, to investigate the development of a band 3-deficient erythrocyte membrane and to specifically assess the stability and retention of band 3 dependent proteins in the absence of this core protein during terminal erythroid differentiation. Further, using lentiviral transduction of N-terminally green fluorescent protein-tagged band 3, we demonstrated the ability to restore expression of band 3 to normal levels and to rescue secondary deficiencies of key proteins including glycophorin A, protein 4.2, CD47 and Rh proteins arising from the absence of band 3 in this patient. By transducing band 3-deficient erythroblasts from this patient with band 3 mutants with absent or impaired ability to associate with the cytoskeleton we also demonstrated the importance of cytoskeletal connectivity for retention both of band 3 and of its associated dependent proteins within the reticulocyte membrane during the process of erythroblast enucleation. Copyright© Ferrata Storti Foundation.

The cytoskeletal binding domain of band 3 is required for multiprotein complex formation and retention during erythropoiesis

PubMed Central

Satchwell, Timothy J; Hawley, Bethan R; Bell, Amanda J; Ribeiro, M. Leticia; Toye, Ashley M

2015-01-01

Band 3 is the most abundant protein in the erythrocyte membrane and forms the core of a major multiprotein complex. The absence of band 3 in human erythrocytes has only been reported once, in the homozygous band 3 Coimbra patient. We used in vitro culture of erythroblasts derived from this patient, and separately short hairpin RNA-mediated depletion of band 3, to investigate the development of a band 3-deficient erythrocyte membrane and to specifically assess the stability and retention of band 3 dependent proteins in the absence of this core protein during terminal erythroid differentiation. Further, using lentiviral transduction of N-terminally green fluorescent protein-tagged band 3, we demonstrated the ability to restore expression of band 3 to normal levels and to rescue secondary deficiencies of key proteins including glycophorin A, protein 4.2, CD47 and Rh proteins arising from the absence of band 3 in this patient. By transducing band 3-deficient erythroblasts from this patient with band 3 mutants with absent or impaired ability to associate with the cytoskeleton we also demonstrated the importance of cytoskeletal connectivity for retention both of band 3 and of its associated dependent proteins within the reticulocyte membrane during the process of erythroblast enucleation. PMID:25344524

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.

Proton tunneling in low dimensional cesium silicate LDS-1

NASA Astrophysics Data System (ADS)

Matsui, Hiroshi; Iwamoto, Kei; Mochizuki, Dai; Osada, Shimon; Asakura, Yusuke; Kuroda, Kazuyuki

2015-07-01

In low dimensional cesium silicate LDS-1 (monoclinic phase of CsHSi2O5), anomalous infrared absorption bands observed at 93, 155, 1210, and 1220 cm-1 are assigned to the vibrational mode of protons, which contribute to the strong hydrogen bonding between terminal oxygen atoms of silicate chain (O-O distance = 2.45 Å). The integrated absorbance (oscillator strength) for those modes is drastically enhanced at low temperatures. The analysis of integrated absorbance employing two different anharmonic double-minimum potentials makes clear that proton tunneling through the potential barrier yields an energy splitting of the ground state. The absorption bands at 93 and 155 cm-1, which correspond to the different vibrational modes of protons, are attributed to the optical transition between the splitting levels (excitation from the ground state (n = 0) to the first excited state (n = 1)). Moreover, the absorption bands at 1210 and 1220 cm-1 are identified as the optical transition from the ground state (n = 0) to the third excited state (n = 3). Weak Coulomb interactions in between the adjacent protons generate two types of vibrational modes: symmetric mode (93 and 1210 cm-1) and asymmetric mode (155 and 1220 cm-1). The broad absorption at 100-600 cm-1 reveals an emergence of collective mode due to the vibration of silicate chain coupled not only with the local oscillation of Cs+ but also with the proton oscillation relevant to the second excited state (n = 2).

The direct exchange mechanism of induced spin polarization of low-dimensional π-conjugated carbon- and h-BN fragments at LSMO(001) MnO-terminated interfaces

NASA Astrophysics Data System (ADS)

Kuklin, Artem V.; Kuzubov, Alexander A.; Kovaleva, Evgenia A.; Lee, Hyosun; Sorokin, Pavel B.; Sakai, Seiji; Entani, Shiro; Naramoto, Hiroshi; Avramov, Paul

2017-10-01

Induced spin polarization of π-conjugated carbon and h-BN low dimensional fragments at the interfaces formed by deposition of pentacene molecule and narrow zigzag graphene and h-BN nanoribbons on MnO2-terminated LSMO(001) thin film was studied using GGA PBE+U PAW D3-corrected approach. Induced spin polarization of π-conjugated low-dimensional fragments is caused by direct exchange with Mn ions of LSMO(001) MnO-derived surface. Due to direct exchange, the pentacene molecule changes its diamagnetic narrow-band gap semiconducting nature to the ferromagnetic semiconducting state with 0.15 eV energy shift between spin-up and spin-down valence bands and total magnetic moment of 0.11 μB. Direct exchange converts graphene nanoribbon to 100% spin-polarized half-metal with large amplitude of spin-up electronic density at the Fermi level. The direct exchange narrows the h-BN nanoribbon band gap from 4.04 to 1.72 eV in spin-up channel and converts the h-BN ribbon semiconducting diamagnetic nature to a semiconducting magnetic one. The electronic structure calculations demonstrate a possibility to control the spin properties of low-dimensional π-conjugated carbon and h-BN fragments by direct exchange with MnO-derived LSMO(001) surface for spin-related applications.

Evaluation of Q-band instrumentation requirements for Strategic Satellite System (SSS) program

NASA Astrophysics Data System (ADS)

Raponi, D. J.

1981-12-01

Q-band instrumentation appropriate for testing the Strategic Satellite System (SSS) satellite terminal is evaluated in terms of current and projected availability; desired and practical measurement capabilities; required development; and schedule/cost impacts to the program. The Air Force is considering several approaches to increasing the strategic communications capability now provided by the recently deployed ultra high frequency (UHF) Air Force Satellite Communications (AFSATCOM) system. The Strategic Satellite System (SSS) was proposed to improve antijam (AJ) characteristics through the use of advanced modulation techniques and higher frequencies (8 and 44 GHz) on links between ground and airborne terminals and the satellites. This report is an assessment of Q-band (44 GHz) test instrumentation requirements, availability, and accuracy as these factors affect cost and schedule for the SSS satellite terminal development program. Though the SSS program has been cancelled, information presented in the report has applicability to the EHF MILSTAR program.

Level structure of 154Ho

NASA Astrophysics Data System (ADS)

Moon, Chang-Bum; Komatsubara, Tetsuro; Furuno, Kohei

2013-10-01

The excited states of the odd-odd 154Ho nucleus have been studied by using in-beam γ-ray spectroscopy with the 141Pr (16O, 3n) 154Ho reaction at Elab=75 MeV. The beam was provided by the 12UD Pelletron accelerator at the University of Tsukuba. In this work, the complicated decay pattern of low energy transitions just above the T1/2=3.10 min isomer have been established. In addition, a number of new states and γ-ray transitions, especially those associated with energetically favored band termination, have been observed for the first time in 154Ho. A negative collective band and its signature partner built on the 11- level are interpreted as being based on the πh11/2⊗νi13/2 configuration. A positive band built on the 10+ level is based on the πh11/2⊗νh9/2 configuration while another positive band built on the 9+ level is being associated with the πh11/2⊗νf7/2 configuration. An energetically favored level Jπ=19- can be interpreted as being attributed to the πh11/2⊗νi13/2 configuration coupled to the 8+ state in neighboring core 152Dy, namely, a four-quasiparticle alignment based on the [πh11/2νi13/2]11-⊗[ν(h9/2f7/2)]8- configuration. Another energetically favored state at Jπ=27- is assigned the six-quasiparticle [π(h11/2)3]27/2-⊗[ν(f7/2h9/2i13/2)]27/2- configuration.

Interfacial preparation and optical transmission surface plasmon resonance of Janus metamaterials membrane

NASA Astrophysics Data System (ADS)

Du, Yixuan; Zhang, Xiaowei; Li, Yunbo

2018-01-01

Janus metamaterials membrane had been fabricated using self-assembly strategy at the oil/water interface with thiol-terminated polymers. Janus metamaterials membrane exhibits a characteristic surface plasmon absorption band, in which the peak position is sensitive to the addition of polymer. The optical transmission surface plasmon resonance (T-SPR) peak has a blue shift at the visible region with addition of thiol-terminated polystyrene (PS-SH). With thiol-terminated poly (ethylene glycol) (PEG-SH) attachment onto the surface side of gold nanoparticles (AuNPs), the T-SPR band has a successive blue shift. One surprising thing is that it has a flat terrace on T-SPR band from 580 to 740 nm. In addition, The T-SPR of Janus metamaterials membrane dramatically changed with the addition PS-SH when the PEG-SH was capped on the opposite side. The morphologies of AuNPs membrane and Janus metamaterials membrane support the above mentioned result of SPR. In virtue of tunable SPR band, the Janus metamaterials membrane has great potential application in science-based design of optical sensing sensors and surface-enhanced optic sensitive detection.

Computational Investigation of the Photochemical Reaction Path of Some Synthesized and Experimentally Analyzed Small-Chain Conjugated Nitrones.

PubMed

Saini, Praveen; Banerjee, Mainak; Chattopadhyay, Anjan

2016-01-28

This combined theoretical and experimental study has revealed the photochemistry of two small open-chain conjugated N-methylnitrone systems with phenyl substitutions at the C-terminal positions. The UV spectra of these synthesized nitrones have shown intense peaks around 330 nm while the new bands formed near 260 nm after their photoirradiation are predicted to be arising from the photoproduct oxaziridine. Photoexcitation of α-styryl N-methylnitrone populates the first excited singlet state which relaxes by 8 kcal/mol from the vertically excited state and subsequently goes toward the lowest-energy conical intersection (CI) geometry (situated 27-30 kcal/mol below) with a terminal CNO-kink. Following the gradient difference vectors of this CI, we have located the oxaziridine structure with its characteristic geometry at roughly 14 kcal/mol above the ground state. This whole process is triggered by a transfer of electronic cloud from oxygen to the conjugated chain side. On the other hand, the photoexcitation of the nonplanar 3,3-diphenylethylene N-methylnitrone has two strong singlet-singlet absorptions with almost 5 D transition moment values. Here the initial S2-S1 relaxation is followed by oxaziridine formation through the terminally twisted CI. However, the initially photoexcited S1 state in this nitrone is found to head toward some other direction with transfer of huge amount of nonbonding electron cloud of oxygen to the π* orbital, creating a stable excited state geometry with an elongated N-O bond which gets involved in a sloped CI with the ground state.

ACTS Propagation Measurements in Maryland and Virginia

NASA Technical Reports Server (NTRS)

Dissanayake, Asoka; Lin, Kuan-Ting

1996-01-01

Rapid growth in new satellite services incorporating very small aperture terminals (VSAT) and ultra small aperture terminals (USAT) is expected in the coming years. Small size terminals allow for widespread use of satellite services in small business and domestic applications. Due to congestion of lower frequency bands such as C and Ku, most of these services will use Ka-band (2/20 GHz) frequencies. Propagation impairments produced by the troposphere is a limiting factor for the effective use of the 20/30 GHz band and the use of smaller Earth terminals makes it difficult to provide sufficient link margins for propagation related outages. In this context, reliable prediction of propagation impairments for low margin systems becomes important. Due to the complexity of propagation phenomena propagation modeling is mainly attempted on an empirical basis. As such, the availability of reliable measured data that extend to probability levels well in excess of the traditional limit of 1 percent is of great importance in the development, validation, and refinement of propagation models. The beacon payload on the Advanced Communications Technology Satellite (ACTS) together with the propagation measurement terminals developed under the NASA ACTS propagation program provide an excellent opportunity to collect such data on a long-term basis. This paper presents the results of ACTS propagation measurements conducted in the Washington, DC metropolitan area by COMSAT Laboratories.

Design of a Ka-Band Propagation Terminal for Atmospheric Measurements in Polar Regions

NASA Technical Reports Server (NTRS)

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

2016-01-01

This paper describes the design and performance of a Ka-Band beacon receiver developed at NASA Glenn Research Center (GRC) that will be installed alongside an existing Ka-Band Radiometer [2] located at the east end of the Svalbard Near Earth Network (NEN) complex. The goal of this experiment is to characterize rain fade attenuation to improve the performance of existing statistical rain attenuation models. The ground terminal developed by NASA GRC utilizes an FFT-based frequency estimation [3] receiver capable of characterizing total path attenuation effects due to gaseous absorption, clouds, rain, and scintillation by directly measuring the propagated signal from the satellite Thor 7.

Design of a Ka-band Propagation Terminal for Atmospheric Measurements in Polar Regions

NASA Technical Reports Server (NTRS)

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

2016-01-01

This paper describes the design and performance of a Ka-Band beacon receiver developed at NASA Glenn Research Center (GRC) that will be installed alongside an existing Ka-Band Radiometer located at the east end of the Svalbard Near Earth Network (NEN) complex. The goal of this experiment is to characterize rain fade attenuation to improve the performance of existing statistical rain attenuation models. 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 by directly measuring the propagated signal from the satellite Thor 7.

ACTS Ka-Band Earth Stations: Technology, Performance, and Lessons Learned

NASA Technical Reports Server (NTRS)

Reinhart, Richard C.; Struharik, Steven J.; Diamond, John J.; Stewart, David

2000-01-01

The Advanced Communications Technology Satellite (ACTS) Project invested heavily in prototype Ka-band satellite ground terminals to conduct an experiments program with the ACTS satellite. The ACTS experiment's program proposed to validate Ka-band satellite and ground station technology. demonstrate future telecommunication services. demonstrate commercial viability and market acceptability of these new services, evaluate system networking and processing technology, and characterize Ka-band propagation effects, including development of techniques to mitigate signal fading. This paper will present a summary of the fixed ground terminals developed by the NASA Glenn Research Center and its industry partners, emphasizing the technology and performance of the terminals (Part 1) and the lessons learned throughout their six year operation including the inclined orbit phase of operations (Full Report). An overview of the Ka-band technology and components developed for the ACTS ground stations is presented. Next. the performance of the ground station technology and its evolution during the ACTS campaign are discussed to illustrate the technical tradeoffs made during the program and highlight technical advances by industry to support the ACTS experiments program and terminal operations. Finally. lessons learned during development and operation of the user terminals are discussed for consideration of commercial adoption into future Ka-band systems. The fixed ground stations used for experiments by government, academic, and commercial entities used reflector based offset-fed antenna systems ranging in size from 0.35m to 3.4m antenna diameter. Gateway earth stations included two systems, referred to as the NASA Ground Station (NGS) and the Link Evaluation Terminal (LET). The NGS provides tracking, telemetry, and control (TT&C) and Time Division Multiple Access (TDMA) network control functions. The LET supports technology verification and high data rate experiments. The ground stations successfully demonstrated many services and applications at Ka-band in three different modes of operation: circuit switched TDMA using the satellite on-board processor, satellite switched SS-TDMA applications using the on-board Microwave Switch Matrix (MSM), and conventional transponder (bent-pipe) operation. Data rates ranged from 4.8 kbps up to 622 Mbps. Experiments included: 1) low rate (4.8- 1 00's kbps) remote data acquisition and control using small earth stations, 2) moderate rate (1-45 Mbps) experiments included full duplex voice and video conferencing and both full duplex and asymmetric data rate protocol and network evaluation using mid-size ground stations, and 3) link characterization experiments and high data rate (155-622 Mbps) terrestrial and satellite interoperability application experiments conducted by a consortium of experimenters using the large transportable ground stations.

Predicting the La Niña of 2020-21: Termination of Solar Cycles and Correlated Variance in Solar and Atmospheric Variability

NASA Astrophysics Data System (ADS)

Leamon, R. J.; McIntosh, S. W.

2017-12-01

Establishing a solid physical connection between solar and tropospheric variability has posed a considerable challenge across the spectrum of Earth-system science. Over the past few years a new picture to describe solar variability has developed, based on observing, understanding and tracing the progression, interaction and intrinsic variability of the magnetized activity bands that belong to the Sun's 22-year magnetic activity cycle. The intra- and extra-hemispheric interaction of these magnetic bands appear to explain the occurrence of decadal scale variability that primarily manifests itself in the sunspot cycle. However, on timescales of ten months or so, those bands posses their own internal variability with an amplitude of the same order of magnitude as the decadal scale. The latter have been tied to the existence of magnetized Rossby waves in the solar convection zone that result in surges of magnetic flux emergence that correspondingly modulate our star's radiative and particulate output. One of the most important events in the progression of these bands is their (apparent) termination at the solar equator that signals a global increase in magnetic flux emergence that becomes the new solar cycle. We look at the particulate and radiative implications of these termination points, their temporal recurrence and signature, from the Sun to the Earth, and show the correlated signature of solar cycle termination events and major oceanic oscillations that extend back many decades. A combined one-two punch of reduced particulate forcing and increased radiative forcing that result from the termination of one solar cycle and rapid blossoming of another correlates strongly with a shift from El Niño to La Niña conditions in the Pacific Ocean. This shift does not occur at solar minima, nor solar maxima, but at a particular, non-periodic, time in between. The failure to identify these termination points, and their relative irregularity, have inhibited a correlation to be observed and physical processes to be studied. This result potentially opens the door to a broader understanding of solar variability on our planet and its weather. Ongoing tracking of solar magnetic band migration indicates that Cycle 24 will terminate in the 2020 timeframe and thus we may expect to see an attendant shift to La Niña conditions at that time.

ATS-6 - A satellite for human needs. [Health, Education, Telecommunications Experiment

NASA Technical Reports Server (NTRS)

Whalen, A. A.; Johnston, W. A., Jr.

1975-01-01

On May 30, 1974, NASA launched the ATS-6 experimental communications satellite into a geosynchronous orbit at a station centered over the United States. The 1400 kg satellite was designed to be body-stabilized with a 3-axis control system capable of precision offset pointing. It deployed a 9.1 meter (30 foot) parabolic reflector antenna with a transponder that covered a frequency range from VHF through C-band. The high RF gains obtained with the antenna were to be used for many dramatic communications experiments, one of which was the Health/Education Telecommunications Experiment (HET), a demonstration of direct broadcast of color television to low cost terminals in remote regions of the United States. More than 120 terminals with 3-meter antennas were deployed in Alaska, Washington, the Rocky Mountains, and Appalachia to provide educational and health services to selected community centers. After 11 months of nearly continuous service, the performance of both the satellite and the experiment have exceeded all expectations.

Channel and terminal description of the ACTS mobile terminal

NASA Technical Reports Server (NTRS)

Abbe, B. S.; Agan, M. J.; Girardey, C. C.; Jedrey, T. C.

1994-01-01

The Advanced Communications Technology Satellite (ACTS) Mobile Terminal (AMT) is a proof-of-concept K/Ka-band mobile satellite communications terminal under development by NASA at JPL. Currently the AMT is undergoing systems integration and testing in preparation for a July 1993 ACTS launch and the subsequent commencement of mobile experiments in the fall of 1993. The AMT objectives are presented, followed by a discussion of the AMT communications channel and the mobile terminal's design and performance.

Channel and terminal description of the ACTS mobile terminal

NASA Technical Reports Server (NTRS)

Abbe, B. S.; Agan, M. J.; Girardey, C. C.; Jedrey, T. C.

1993-01-01

The Advanced Communications Technology Satellite (ACTS) Mobile Terminal (AMT) is a proof-of-concept K/Ka-band mobile satellite communications terminal under development by NASA at JPL. Currently the AMT is undergoing system integration and test in preparation for a July 1993 ACTS launch and the subsequent commencement of mobile experiments in the fall of 1993. The AMT objectives are presented followed by a discussion of the AMT communications channel and mobile terminal design and performance.

Analysis of Rotationally Resolved Spectra to Non-Degenerate (a''_1) Upper-State Vibronic Levels in the tilde{A} ^2E''-tilde{X}^2A^'_2 Electronic Transition of NO_3

NASA Astrophysics Data System (ADS)

Roudjane, Mourad; Codd, Terrance Joseph; Chen, Ming-Wei; Tran, Henry; Melnik, Dmitry G.; Miller, Terry A.; Stanton, John F.

2015-06-01

The vibronic structure of the tilde{A}-tilde{X} electronic spectrum of NO_3 has been observed using both room-temperature and jet-cooled samples. A recent analysis of this structure is consistent with the Jahn-Teller effect (JTE) in the e^' ν_3 vibrational mode (N-O stretch) being quite strong while the JTE in the e^' ν_4 mode (O-N-O) bend) is rather weak. Electronic structure calculations qualitatively predict these results but the calculated magnitude of the JTE is quantitatively inconsistent with the spectral analysis. Rotationally resolved spectra have been obtained for over a dozen vibronic bands of the tilde{A}-tilde{X} electronic transition in NO_3. An analysis of these spectra should provide considerably more experimental information about the JTE in the tilde{A} state of NO_3 as the rotational structure should be quite sensitive to the geometric distortion of the molecule due to the JTE. This talk will focus upon the parallel bands, which terminate on tilde{A} state levels of a''_1 vibronic symmetry, which were the subject of a preliminary analysis reported at this meeting in 2014. We have now recorded the rotational structure of over a half-dozen parallel bands and have completed analysis on the 3^1_0 and 3^1_0 4^1_0 transitions with several other bands being reasonably well understood. Two general conclusions emerge from this work. (i) All the spectral bands show evidence of perturbations which can reasonably be assumed to result from interactions of the observed tilde{A} state levels with high vibrational levels of the tilde{X} state. The perturbations range from severe in some bands to quite modest in others. (ii) Analyses of observed spectra, insofar as the perturbations permit, have all been performed with an oblate symmetric top model including only additional spin-rotation effects. This result is, of course, consistent with an effective, undistorted geometry for NO_3 of D3h symmetry on the rotational timescale.

Spectroscopy of selected metal-containing diatomic molecules

NASA Astrophysics Data System (ADS)

Gordon, Iouli E.

Fourier transform infrared emission spectra of MnH and MnD were observed in the ground X7Sigma+ electronic state. The vibration-rotation bands from v = 1 → 0 to v = 3 → 2 for MnH, and from v = 1 → 0 to v = 4 → 3 for MnD were recorded at an instrumental resolution of 0.0085 cm-1. Spectroscopic constants were determined for each vibrational level and equilibrium constants were found from a Dunham-type fit. The equilibrium vibrational constant oe for MnH was found to be 1546.84518(65) cm-1, the equilibrium rotational constant Be was found to be 5.6856789(103) cm-1 and the equilibrium bond distance re was determined to be 1.7308601(47) A. New high resolution emission spectra of CoH and CoD molecules have been recorded in the 640 nm to 3.5 mum region using a Fourier transform spectrometer. Many bands were observed for the A'3phi- X3phi electronic transition of CoH and CoD. In addition, a new [13.3]4 electronic state was found by observing the [13.3]4-X3phi3 and [13.3]4- X3phi4 transitions in the spectrum of CoD. Analysis of the transitions with DeltaO = 0, +/-1 provided more accurate values of spin-orbit splittings between O = 4 and O = 3 components. The ground state for both molecules was fitted both to band and Dunham-type constants. The estimated band constants of the perturbed upper states were also obtained. The emission spectrum of gas-phase YbO has been investigated using a Fourier transform spectrometer. A total of 8 red-degraded bands in the range 9 800--11 300 cm-1 were recorded at a resolution of 0.04 cm-1. Because of the multiple isotopomers present in the spectra, only 3 bands were rotationally analyzed. Perturbations were identified in two of these bands and all 3 transitions were found to terminate at the X1Sigma+ ground electronic state. The electronic configurations that give rise to the observed states are discussed and molecular parameters for all of the analyzed bands are reported. Electronic spectra of the previously unobserved EuH and EuD molecules were studied by means of Fourier transform spectroscopy and laser-induced fluorescence. The extreme complexity of these transitions made rotational assignments of EuH bands impossible. However, the spin-spin interaction constant, lambda, and Fermi contact parameter, bF, in the ground X9Sigma- electronic state were estimated for the 151EuH and 153EuH isotopologues. Electronic spectra of SmH, SmCl, TmH and ErF molecules were recorded for the first time using Fourier transform spectrometer. The poor signal to noise ratio of the observed bands coupled with their complexity prevented a rotational analysis. The electronic states that may be involved in the observed transitions are discussed.

Spectroscopy of selected metal-containing diatomic molecules

NASA Astrophysics Data System (ADS)

Gordon, Iouli

Fourier transform infrared emission spectra of MnH and MnD were observed in the ground X7[sigma]+ electronic state. The vibration-rotation bands from v = 1 to 0 to v = 3 to 2 for MnH, and from v = 1 to 0 to v = 4 to 3 for MnD were recorded at an instrumental resolution of 0. 0085 cm-1. Spectroscopic constants were determined for each vibrational level and equilibrium constants were found from a Dunham-type fit. The equilibrium vibrational constant [omega]e for MnH was found to be 1546. 84518(65) cm-1, the equilibrium rotational constant Be was found to be 5. 6856789(103) cm-1 and the equilibrium bond distance re was determined to be 1. 7308601(47) ?. New high resolution emission spectra of CoH and CoD molecules have been recorded in the 640 nm to 3. 5 _m region using a Fourier transform spectrometer. Many bands were observed for the A'3?-X3? electronic transition of CoH and CoD. In addition, a new [13. 3]4 electronic state was found by observing the [13. 3]4- X3?3 and [13. 3]4-X3?4 transitions in the spectrum of CoD. Analysis of the transitions with [delta][omega] = 0, ?1 provided more accurate values of spin-orbit splittings between [omega] = 4 and [omega] = 3 components. The ground state for both molecules was fitted both to band and Dunham-type constants. The estimated band constants of the perturbed upper states were also obtained. The emission spectrum of gas-phase YbO has been investigated using a Fourier transform spectrometer. A total of 8 red-degraded bands in the range 9 800 ? 11 300 cm-1 were recorded at a resolution of 0. 04 cm-1. Because of the multiple isotopomers present in the spectra, only 3 bands were rotationally analyzed. Perturbations were identified in two of these bands and all 3 transitions were found to terminate at the X1[sigma]+ ground electronic state. The electronic configurations that give rise to the observed states are discussed and molecular parameters for all of the analyzed bands are reported. Electronic spectra of the previously unobserved EuH and EuD molecules were studied by means of Fourier transform spectroscopy and laser-induced fluorescence. The extreme complexity of these transitions made rotational assignments of EuH bands impossible. However, the spin-spin interaction constant, [lambda], and Fermi contact parameter, bF, in the ground X9[sigma]- electronic state were estimated for the 151EuH and 153EuH isotopologues. Electronic spectra of SmH, SmCl, TmH and ErF molecules were recorded for the first time using Fourier transform spectrometer. The poor signal to noise ratio of the observed bands coupled with their complexity prevented a rotational analysis. The electronic states that may be involved in the observed transitions are discussed.

CPM Signals for Satellite Navigation in the S and C Bands.

PubMed

Xue, Rui; Sun, Yanbo; Zhao, Danfeng

2015-06-05

Frequency allocations in the L band suitable for global navigation satellite system (GNSS) services are getting crowded and system providers face an ever tougher job when they try to bring in new signals and services while maintaining radio frequency compatibility. With the successive opening of the S and C bands to GNSS service, the multi-band combined navigation is predicted to become a key technology for future high-precision positioning navigation systems, and a single modulation scheme satisfying the requirements in each band is a promising solution for reducing user terminal complexity. A universal modulation scheme based on the continuous phase modulation (CPM) family suitable for the above bands' demands is proposed. Moreover, this paper has put forward two specific CPM signals for the S and C bands, respectively. Then the proposed modulation schemes, together with existing candidates, are comprehensively evaluated. Simulation results show that the proposed CPM signals can not only satisfy the constraint condition of compatibility in different bands well and reduce user terminal complexity, but also provide superior performance in terms of tracking accuracy, multi-path mitigation and anti-jamming compared to other candidate modulation schemes.

Electrochemical and optical study of carotenoids in TX 100 micelles: Electron transfer and a large blue shift

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

He, Z.; Kispert, L.D.

1999-10-21

The first oxidation waves of 8{prime}-apo-{beta}-caroten-8{prime}-al (I) and 8{prime}-apo-{beta}-caroten-8{prime}nitrile (II) in TX100 micelles are clearly observed in their cyclic voltammograms (CVs). The CV of {beta}-carotene (III) in TX100 micelles shows that III is not oxidized. It is proposed that the hydrophobic barrier of the micelle is an important reason for the failure to oxidize III, which is totally located in the hydrophobic center of the micelle. The oxidation of I and II demonstrates that electrons can be transferred through the terminal groups over a distance of ca. 22 {angstrom}. An unusually large blue band shift (100 nm, relative to thatmore » in CH{sub 2}Cl{sub 2}) is observed in the optical absorption spectrum of 7{prime}-apo-7{prime},7{prime}-dicyano-{beta}-carotene (IV) in TX100 micelles. This phenomenon is not observed in the absorption spectra of other studied carotenoids. A change in the ground-state electronic structure of IV, due to the influence of water near the terminal dicyanomethylidene group, is proposed to be the major reason for this large band shift.« less

Comparison of the Optical Properties of Graphene and Alkyl-terminated Si and Ge Quantum Dots.

PubMed

de Weerd, Chris; Shin, Yonghun; Marino, Emanuele; Kim, Joosung; Lee, Hyoyoung; Saeed, Saba; Gregorkiewicz, Tom

2017-10-31

Semiconductor quantum dots are widely investigated due to their size dependent energy structure. In particular, colloidal quantum dots represent a promising nanomaterial for optoelectronic devices, such as photodetectors and solar cells, but also luminescent markers for biotechnology, among other applications. Ideal materials for these applications should feature efficient radiative recombination and absorption transitions, altogether with spectral tunability over a wide range. Group IV semiconductor quantum dots can fulfill these requirements and serve as an alternative to the commonly used direct bandgap materials containing toxic and/or rare elements. Here, we present optical properties of butyl-terminated Si and Ge quantum dots and compare them to those of graphene quantum dots, finding them remarkably similar. We investigate their time-resolved photoluminescence emission as well as the photoluminescence excitation and linear absorption spectra. We contemplate that their emission characteristics indicate a (semi-) resonant activation of the emitting channel; the photoluminescence excitation shows characteristics similar to those of a molecule. The optical density is consistent with band-to-band absorption processes originating from core-related states. Hence, these observations strongly indicate a different microscopic origin for absorption and radiative recombination in the three investigated quantum dot systems.

Solid-state image sensor with focal-plane digital photon-counting pixel array

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Pain, Bedabrata (Inventor)

1995-01-01

A photosensitive layer such as a-Si for a UV/visible wavelength band is provided for low light level imaging with at least a separate CMOS amplifier directly connected to each PIN photodetector diode to provide a focal-plane array of NxN pixels, and preferably a separate photon-counting CMOS circuit directly connected to each CMOS amplifier, although one row of counters may be time shared for reading out the photon flux rate of each diode in the array, together with a buffer memory for storing all rows of the NxN image frame before transfer to suitable storage. All CMOS circuitry is preferably fabricated in the same silicon layer as the PIN photodetector diode for a monolithic structure, but when the wavelength band of interest requires photosensitive material different from silicon, the focal-plane array may be fabricated separately on a different semiconductor layer bump-bonded or otherwise bonded for a virtually monolithic structure with one free terminal of each diode directly connected to the input terminal of its CMOS amplifier and digital counter for integration of the photon flux rate at each photodetector of the array.

Observation of a well-defined hybridization gap and in-gap states on the SmB6 (001) surface

NASA Astrophysics Data System (ADS)

Sun, Zhixiang; Maldonado, Ana; Paz, Wendel S.; Inosov, Dmytro S.; Schnyder, Andreas P.; Palacios, J. J.; Shitsevalova, Natalya Yu.; Filipov, Vladimir B.; Wahl, Peter

2018-06-01

The rise of topology in condensed-matter physics has generated strong interest in identifying novel quantum materials in which topological protection is driven by electronic correlations. Samarium hexaboride is a Kondo insulator for which it has been proposed that a band inversion between 5 d and 4 f bands gives rise to topologically protected surface states. However, unambiguous proof of the existence and topological nature of these surface states is still missing, and its low-energy electronic structure is still not fully established. Here we present a study of samarium hexaboride by ultralow-temperature scanning tunneling microscopy and spectroscopy. We obtain clear atomically resolved topographic images of the sample surface. Our tunneling spectra reveal signatures of a hybridization gap with a size of about 8 meV and with a reduction of the differential conductance inside the gap by almost half, and surprisingly, several strong resonances below the Fermi level. The spatial variations of the energy of the resonances point toward a microscopic variation of the electronic states by the different surface terminations. High-resolution tunneling spectra acquired at 100 mK reveal a splitting of the Kondo resonance, possibly due to the crystal electric field.

Magnetism, structures and stabilities of cluster assembled TM@Si nanotubes (TM = Cr, Mn and Fe): a density functional study.

PubMed

Dhaka, Kapil; Bandyopadhyay, Debashis

2016-08-02

The present study reports transition metal (TM = Cr, Mn and Fe) doped silicon nanotubes with tunable band structures and magnetic properties by careful selection of cluster assemblies as building blocks using the first-principles density functional theory. We found that the transition metal doping and in addition, the hydrogen termination process can stabilize the pure silicon nanoclusters or cluster assemblies and then it could be extended as magnetic nanotubes with finite magnetic moments. Study of the band structures and density of states (DOS) of different empty and TM doped nanotubes (Type 1 to Type 4) show that these nanotubes are useful as metals, semiconductors, semi-metals and half-metals. These designer magnetic materials could be useful in spintronics and magnetic devices of nanoscale order.

Surface Structure and Surface Electronic States Related to Plasma Cleaning of Silicon and Germanium

NASA Astrophysics Data System (ADS)

Cho, Jaewon

This thesis discusses the surface structure and the surface electronic states of Si and Ge(100) surfaces as well as the effects of oxidation process on the silicon oxide/Si(100) interface structure. The H-plasma exposure was performed in situ at low temperatures. The active species, produced in the H-plasma by the rf-excitation of H_2 gas, not only remove microcontaminants such as oxygen and carbon from the surface, but also passivate the surface with atomic hydrogen by satisfying the dangling bonds of the surface atoms. The surfaces were characterized by Angle Resolved UV-Photoemission Spectroscopy (ARUPS) and Low Energy Electron Diffraction (LEED). In the case of Si(100), H-plasma exposure produced ordered H-terminated crystallographic structures with either a 2 x 1 or 1 x 1 LEED pattern. The hydride phases, found on the surfaces of the cleaned Si(100), were shown to depend on the temperature of the surface during H-plasma cleaning. The electronic states for the monohydride and dihydride phases were identified by ARUPS. When the plasma cleaned surface was annealed, the phase transition from the dihydride to monohydride was observed. The monohydride Si-H surface bond was stable up to 460^circC, and the dangling bond surface states were identified after annealing at 500^circC which was accompanied by the spectral shift. The H-terminated surface were characterized to have a flat band structure. For the Ge(100) surface, an ordered 2 x 1 monohydride phase was obtained from the surface cleaned at 180 ^circC. After plasma exposure at <=170^circC a 1 x 1 surface was observed, but the ARUPS indicated that the surface was predominantly composed of disordered monohydride structures. After annealing above the H-dissociation temperatures, the shift in the spectrum was shown to occur with the dangling bond surface states. The H-terminated surfaces were identified to be unpinned. The interface structure of silicon oxide/Si(100) was studied using ARUPS. Spectral shifts were observed, which were dependent on the processes of surface preparation and oxidation. The shift was characterized in association with the band bending. The origins of the spectral shifts were discussed, including defects at interface and H-passivation in Si. The interface structure is considered to be dependent on the surface preparation and oxidation process.

Reactive Landing of Gramicidin S and Ubiquitin Ions onto Activated Self-Assembled Monolayer Surfaces

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

Laskin, Julia; Hu, Qichi

2017-03-13

Using mass-selected ion deposition combined with in situ infrared reflection absorption spectroscopy (IRRAS), we examined the reactive landing of gramicidin S and ubiquitin ions onto activated self-assembled monolayer (SAM) surfaces terminated with N-hydroxysuccinimidyl ester (NHS-SAM) and acyl fluoride (COF-SAM) groups. Doubly protonated gramicidin S, [GS+2H]2+, and two charge states of ubiquitin, [U+5H]5+ and [U+13H]13+, were used as model systems, allowing us to explore the effect of the number of free amino groups and the secondary structure on the efficiency of covalent bond formation between the projectile ion and the surface. For all projectile ions, ion deposition resulted in the depletionmore » of IRRAS bands corresponding to the terminal groups on the SAM and the appearance of several new bands not associated with the deposited species. These new bands were assigned to the C=O stretching vibrations of COOH and COO- groups formed on the surface as a result of ion deposition. The presence of these bands was attributed to an alternative reactive landing pathway that competes with covalent bond formation. This pathway with similar yields for both gramicidin S and ubiquitin ions is analogous to the hydrolysis of the NHS ester bond in solution. The covalent bond formation efficiency increased linearly with the number of free amino groups and was found to be lower for the more compact conformation of ubiquitin compared with the fully unfolded conformation. This observation was attributed to the limited availability of amino groups on the surface of the folded conformation. Our results have provided new insights on the efficiency and mechanism of reactive landing of peptides and proteins onto activated SAMs« less

Reactive Landing of Gramicidin S and Ubiquitin Ions onto Activated Self-Assembled Monolayer Surfaces

NASA Astrophysics Data System (ADS)

Laskin, Julia; Hu, Qichi

2017-07-01

Using mass-selected ion deposition combined with in situ infrared reflection absorption spectroscopy (IRRAS), we examined the reactive landing of gramicidin S and ubiquitin ions onto activated self-assembled monolayer (SAM) surfaces terminated with N-hydroxysuccinimidyl ester (NHS-SAM) and acyl fluoride (COF-SAM) groups. Doubly protonated gramicidin S, [GS + 2H]2+, and two charge states of ubiquitin, [U + 5H]5+ and [U + 13H]13+, were used as model systems, allowing us to explore the effect of the number of free amino groups and the secondary structure on the efficiency of covalent bond formation between the projectile ion and the surface. For all projectile ions, ion deposition resulted in the depletion of IRRAS bands corresponding to the terminal groups on the SAM and the appearance of several new bands not associated with the deposited species. These new bands were assigned to the C=O stretching vibrations of COOH and COO- groups formed on the surface as a result of ion deposition. The presence of these bands was attributed to an alternative reactive landing pathway that competes with covalent bond formation. This pathway with similar yields for both gramicidin S and ubiquitin ions is analogous to the hydrolysis of the NHS ester bond in solution. The covalent bond formation efficiency increased linearly with the number of free amino groups and was found to be lower for the more compact conformation of ubiquitin compared with the fully unfolded conformation. This observation was attributed to the limited availability of amino groups on the surface of the folded conformation. Our results have provided new insights on the efficiency and mechanism of reactive landing of peptides and proteins onto activated SAMs.

47 CFR 27.1174 - Termination of Cost-Sharing Obligations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... § 27.1174 Termination of Cost-Sharing Obligations. The cost-sharing plan will sunset for all AWS and... AWS band (i.e., 2110-2150 MHz, 2160-2175 MHz, or 2175-2180 MHz) in which the relocated FMS link was located terminates. AWS or MSS (including MSS/ATC) entrants that trigger a cost-sharing obligation prior...

47 CFR 27.1174 - Termination of Cost-Sharing Obligations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... § 27.1174 Termination of Cost-Sharing Obligations. The cost-sharing plan will sunset for all AWS and... AWS band (i.e., 2110-2150 MHz, 2160-2175 MHz, or 2175-2180 MHz) in which the relocated FMS link was located terminates. AWS or MSS (including MSS/ATC) entrants that trigger a cost-sharing obligation prior...

Channel characterisation for future Ka-band Mobile Satellite Systems and preliminary results

NASA Technical Reports Server (NTRS)

Sforza, Mario; Buonomo, Sergio; Arbesser-Rastburg, Bertram

1994-01-01

Mobile satellite systems (MSS) are presently designed or planned to operate, with the exception of OMNITRACKS, in the lower part of the frequency spectrum (UHF to S-bands). The decisions taken at the last World Administrative Radio Conference in 1992 to increase the allocated L- and S-bands for MSS services will only partly alleviate the problem of system capacity. In addition the use of L-and S-band frequencies generally requires large antenna apertures on board the satellite terminal side. The idea of exploiting the large spectrum resources available at higher frequencies (20-30 GHz) and the perspective of reducing user terminal size (and possibly price too) have spurred the interest of systems designers and planners. On the other hand, Ka-band frequencies suffer from increased slant path losses due to atmospheric attenuation phenomena. The European Space Agency (ESA) has recently embarked on a number of activities aimed at studying the effect of the typical mobile propagation impairments at Ka-band. This paper briefly summarizes ESA efforts in this field of research and presents preliminary experimental results.

UTa 2O(S 2) 3Cl 6: A ribbon structure containing a heterobimetallic 5 d-5 f M 3 cluster

NASA Astrophysics Data System (ADS)

Wells, Daniel M.; Chan, George H.; Ellis, Donald E.; Ibers, James A.

2010-02-01

A new solid-state compound containing a heterobimetallic cluster of U and Ta, UTa 2O(S 2) 3Cl 6, has been synthesized and its structure has been characterized by single-crystal X-ray diffraction methods. UTa 2O(S 2) 3Cl 6 was synthesized from UCl 4 and Ta 1.2S 2 at 883 K. The O is believed to have originated in the Ta 1.2S 2 reactant. The compound crystallizes in the space group P1¯ of the triclinic system. The structure comprises a UTa 2 unit bridged by μ 2-S 2 and μ 3-O groups. Each Ta atom bonds to two μ 2-S 2, the μ 3-O, and two terminal Cl atoms. Each U atom bonds to two μ 2-S 2, the μ 3-O, and four Cl atoms. The Cl atoms bridge in pairs to neighboring U atoms to form a ribbon structure. The bond distances are normal and are consistent with formal oxidation states of +IV/+V/-II/-I/-I for U/Ta/O/S/Cl, respectively. The optical absorbance spectrum displays characteristic transition peaks near the absorption edge. Density functional theory was used to assign these peaks to transitions between S 1- valence-band states and empty U 5 f-6 d hybrid bands. Density-of-states analysis shows overlap between Ta 5 d and U bands, consistent with metal-metal interactions.

Vibronic Structure of the tilde{X} ^2A_2' State of NO_3

NASA Astrophysics Data System (ADS)

Fukushima, Masaru

2015-06-01

We have measured dispersed fluorescence ( DF ) spectra from the single vibronic levels ( SVL's ) of the tilde{B} ^2E' state of jet cooled 14NO_3 and 15NO_3, and found a new vibronic band around the ν_1 fundamental This new band has two characteristics; (1) inverse isotope shift, and (2) unexpectedly strong intensity, i.e. comparable with that of the ν_1 fundamental. We concluded on the basis of the isotope effect that the terminated ( lower ) vibrational level of the new vibronic band should have vibrationally a_1' symmetry, and assigned to the third over-tone of the ν_4 asymmetric (e') mode, 3 ν_4 (a_1'). We also assigned a weaker band at about 160 cm-1 above the new band to one terminated to 3 ν_4 (a_2'). The 3 ν_4 (a_1') and (a_2') levels are ones with l = ±3. Hirota proposed new vibronic coupling mechanism which suggests that degenerate vibrational modes can induce electronic orbital angular momentum ( L ) even in non-degenerate electronic states. %It is thus thought the surprisingly wide splitting of 3 ν_4, a_1' and a_2', is resulted from vibronic coupling, and the explanation we proposed is as follows. We interpret this as a sort of break-down of the Born-Oppenheimer approximation, and think that ± l induces ∓barΛ, where barΛ expresses the pseudo-L; for the present system, one of the components of the third over-tone level, | Λ = 0; v_4 = 3, l = +3 rangle, can have contributions of | barΛ = -1; v_4 = 3, l = +2 rangle and | -2; 3, +1 rangle. Under this interpretation, it is expected that there is sixth-order vibronic coupling, (q_+^3Q_-^3 + q_-^3Q_+^3), between | 0; 3, +3 rangle and | 0; 3, -3 rangle. The sixth-order coupling is weaker than the Renner-Teller term ( the fourth-order term, (q_+^2Q_-^2 + q_-^2Q_+^2) ), but stronger than the eighth-order term, (q_+^4Q_-^4 + q_-^4Q_+^4). It is well known in linear molecules that the former shows huge separation, comparable with vibrational frequency, among the vibronic levels of Π electronic states, and the latter shows considerable splitting, ˜10 cm-1, at Δ electronic states. Consequently, the ˜160 cm-1 splitting at v_4 = 3 is attributed to the sixth-order interaction. The relatively strong intensity for the band to 3 ν_4 (a_1') can be interpreted as a part of the huge 0-0 band intensity, because the 3 ν_4 (a_1') level, | 0; 3, ±3 rangle, can connect with the vibrationless level, | 0; 0, 0 rangle. 3 ν_4 (a_1') has two-fold intensity because of the vibrational wavefunction, | 0; 3, +3 rangle + | 0; 3, -3 rangle, while negligible intensity is expected for 3 ν_4 (a_2') with | 0; 3, +3 rangle - | 0; 3, -3 rangle due to the cancellation. To confirm these interpretations, experiments on rotationally resolved spectra are underway. M. Fukushima and T. Ishiwata, paper WJ03, ISMS2013, and paper MI17, ISMS2014. E. Hirota, J. Mol. Spectrosc., in press.

Reversible binding of hemoglobin to band 3 constitutes the molecular switch that mediates O2 regulation of erythrocyte properties

PubMed Central

McKenna, Mary M.; Krump, Nathan A.; Zheng, Suilan; Mendelsohn, Laurel; Thein, Swee Lay; Garrett, Lisa J.; Bodine, David M.

2016-01-01

Functional studies have shown that the oxygenation state of the erythrocyte regulates many important pathways, including glucose metabolism, membrane mechanical stability, and cellular adenosine triphosphate (ATP) release. Deoxyhemoglobin (deoxyHb), but not oxyhemoglobin, binds avidly and reversibly to band 3, the major erythrocyte membrane protein. Because band 3 associates with multiple metabolic, solute transport, signal transduction, and structural proteins, the hypothesis naturally arises that the O2-dependent regulation of erythrocyte properties might be mediated by the reversible association of deoxyHb with band 3. To explore whether the band 3–deoxyHb interaction constitutes a “molecular switch” for regulating erythrocyte biology, we have generated transgenic mice with mutations in the deoxyHb-binding domain of band 3. One strain of mouse contains a “humanized” band 3 in which the N-terminal 45 residues of mouse band 3 are replaced by the homologous sequence from human band 3, including the normal human band 3 deoxyHb-binding site. The second mouse contains the same substitution as the first, except the deoxyHb site on band 3 (residues 12-23) has been deleted. Comparison of these animals with wild-type mice demonstrates that the following erythrocyte properties are controlled by the O2-dependent association of hemoglobin with band 3: (1) assembly of a glycolytic enzyme complex on the erythrocyte membrane which is associated with a shift in glucose metabolism between the pentose phosphate pathway and glycolysis, (2) interaction of ankyrin with band 3 and the concomitant regulation of erythrocyte membrane stability, and (3) release of ATP from the red cell which has been linked to vasodilation. PMID:27688804

FTIR and FT-Raman spectra and DFT vibrational analysis of phosphorus-containing dendrons

NASA Astrophysics Data System (ADS)

Furer, V. L.; Vandyukova, I. I.; Vandyukov, A. E.; Majoral, J. P.; Caminade, A. M.; Kovalenko, V. I.

2008-12-01

FTIR and FT-Raman spectra of four generations of phosphorus-containing dendrons with terminal aldehyde or P sbnd Cl groups have been recorded and analyzed. Their spectral patterns are determined by the ratio T/ R ( T, the number of terminal groups; R, the number of repeated units). Bands assigned to the core, repeated units and terminal groups were separated by the difference spectroscopy method. The optimized geometry, frequencies and intensity of IR bands of G1v generation dendron with terminal aldehyde groups were obtained by the density functional theory (DFT). It was found that the internal skeleton of molecules exists in a single stable conformation with planar sbnd O- C6H4- CHdbnd N- N( CH3)- P( dbnd S)< fragments, but terminal groups may adopt the t, g, g- and t,- g, g-rotational isomers. The t,- g, g-conformer is 0.74 kcal/mol less stable compared to the t, g, g-conformer. The bond length and bond angles obtained by DFT show the best agreement with experimental data. Relying on DFT calculations a complete assignment of vibrations is proposed for different parts of the studied dendrons. The calculated frequencies and intensity of IR bands of the t, g, g- and t,- g, g-conformers of G1v are found to be in reasonable agreement with the experimental results. The most reactive site in dendron is the core function and vinyl group is preferred for nucleophilic attack. In dendrimer the most reactive are the terminal groups.

Spectroscopic Visualization of Inversion and Time-Reversal Symmetry Breaking Weyl Semi-metals

NASA Astrophysics Data System (ADS)

Beidenkopf, Haim

A defining property of a topological material is the existence of surface bands that cannot be realized but as the termination of a topological bulk. In a Weyl semi-metal these surface states are in the form of Fermi-arcs. Their open-contour Fermi-surface curves between pairs of surface projections of bulk Weyl cones. Such Dirac-like bulk bands, as opposed to the gapped bulk of topological insulators, land a unique opportunity to examine the deep notion of bulk to surface correspondence. We study the intricate properties both of inversion symmetry broken and of time-reversal symmetry broken Weyl semimetals using scanning tunneling spectroscopy. We visualize the Fermi arc states on the surface of the non-centrosymmetric Weyl semi-metal TaAs. Using the distinct structure and spatial distribution of the wavefunctions associated with the different topological and trivial bands we detect the scattering processes that involve Fermi arcs. Each of these imaged scattering processes entails information on the unique nature of Fermi arcs and their correspondence to the topological bulk. We further visualize the magnetic response of the candidate magnetic Weyl semimetal GdPtBi in which the magnetic order parameter is coupled to the topological classification. European Research Council (ERC-StG no. 678702, TOPO-NW\\x9D), the Israel Science Foundation (ISF), and the United States-Israel Binational Science Foundation (BSF).

Porous silicon nanocrystals in a silica aerogel matrix

PubMed Central

2012-01-01

Silicon nanoparticles of three types (oxide-terminated silicon nanospheres, micron-sized hydrogen-terminated porous silicon grains and micron-size oxide-terminated porous silicon grains) were incorporated into silica aerogels at the gel preparation stage. Samples with a wide range of concentrations were prepared, resulting in aerogels that were translucent (but weakly coloured) through to completely opaque for visible light over sample thicknesses of several millimetres. The photoluminescence of these composite materials and of silica aerogel without silicon inclusions was studied in vacuum and in the presence of molecular oxygen in order to determine whether there is any evidence for non-radiative energy transfer from the silicon triplet exciton state to molecular oxygen adsorbed at the silicon surface. No sensitivity to oxygen was observed from the nanoparticles which had partially H-terminated surfaces before incorporation, and so we conclude that the silicon surface has become substantially oxidised. Finally, the FTIR and Raman scattering spectra of the composites were studied in order to establish the presence of crystalline silicon; by taking the ratio of intensities of the silicon and aerogel Raman bands, we were able to obtain a quantitative measure of the silicon nanoparticle concentration independent of the degree of optical attenuation. PMID:22805684

Porous silicon nanocrystals in a silica aerogel matrix.

PubMed

Amonkosolpan, Jamaree; Wolverson, Daniel; Goller, Bernhard; Polisski, Sergej; Kovalev, Dmitry; Rollings, Matthew; Grogan, Michael D W; Birks, Timothy A

2012-07-17

Silicon nanoparticles of three types (oxide-terminated silicon nanospheres, micron-sized hydrogen-terminated porous silicon grains and micron-size oxide-terminated porous silicon grains) were incorporated into silica aerogels at the gel preparation stage. Samples with a wide range of concentrations were prepared, resulting in aerogels that were translucent (but weakly coloured) through to completely opaque for visible light over sample thicknesses of several millimetres. The photoluminescence of these composite materials and of silica aerogel without silicon inclusions was studied in vacuum and in the presence of molecular oxygen in order to determine whether there is any evidence for non-radiative energy transfer from the silicon triplet exciton state to molecular oxygen adsorbed at the silicon surface. No sensitivity to oxygen was observed from the nanoparticles which had partially H-terminated surfaces before incorporation, and so we conclude that the silicon surface has become substantially oxidised. Finally, the FTIR and Raman scattering spectra of the composites were studied in order to establish the presence of crystalline silicon; by taking the ratio of intensities of the silicon and aerogel Raman bands, we were able to obtain a quantitative measure of the silicon nanoparticle concentration independent of the degree of optical attenuation.

Comparative Study of Optical and Radio-Frequency Communication Systems for a Deep-Space Mission

NASA Technical Reports Server (NTRS)

Hemmati, H.; Wilson, K.; Sue, M. K.; Harcke, L. J.; Wilhelm, M.; Chen, C.-C.; Lesh, J.; Feria, Y.; Rascoe, D.; Lansing, F.

1997-01-01

We have performed a study on telecommunication systems for a hypothetical mission to Mars. The objective of the study was to evaluate and compare the benefits that microwave-X-band (8.4 GHz) and Ka-band (32 GHz) - and optical communications technologies a afford to future missions. The telecommunication systems were required to return data after launch and in orbit at 2.7 AU with daily data volumes of 0.1, 1.0, or 10.0 Gbits (Gb). Spacecraft terminals capable of delivering each of the three data volumes were proposed and characterized in terms of mass, power consumption, size, and cost. The estimated parameters for X-band, Ka-band, and optical frequencies are compared and presented here. For all cases, the optical light terminal exhibits about 60 percent of the mass of the corresponding radio frequency (RF) subsystem. Power consumption is comparable for all three technologies at a 0.1 Gb/day data volume, but the power required at either Ka-band or optical is less than half of the X-band requirement at 10 Gb/day. These benefits can be obtained only with a suitable investment in reception facilities for Ka-band or optical frequencies.

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.

Proposal for a Joint NASA/KSAT Ka-band RF Propagation Terminal at Svalbard, Norway

NASA Technical Reports Server (NTRS)

Volosin, Jeffrey; Acosta, Roberto; Nessel, James; McCarthy, Kevin; Caroglanian, Armen

2010-01-01

This slide presentation discusses the placement of a Ka-band RF Propagation Terminal at Svalbard, Norway. The Near Earth Network (NEN) station would be managed by Kongsberg Satellite Services (KSAT) and would benefit NASA and KSAT. There are details of the proposed NASA/KSAT campaign, and the responsibilities each would agree to. There are several reasons for the placement, a primary reason is comparison with the Alaska site, Based on climatological similarities/differences with Alaska, Svalbard site expected to have good radiometer/beacon agreement approximately 99% of time.

The evolution of a Ku-Band satellite network

NASA Technical Reports Server (NTRS)

Bransford, L. A.; Diebler, M.; Dutka, S. C.; Gorton, D. W.

1982-01-01

The purpose of this study was to undertake the management and development of CTS terminals and time on appropriate Ku-Band satellites was procured. A community of public service users who have readily addressable needs and resources to pay for services on an ad hoc Ku-Band network was developed and a test network for selected users was managed.

Communication satellite technology: State of the art and development opportunities

NASA Technical Reports Server (NTRS)

Woodford, J. B. (Compiler)

1978-01-01

Opportunities in communication satellite technology are identified and defined. Factors that tend to limit the ready availability of satellite communication to an increasingly wide group of users are evaluated. Current primary limitations on this wide utilization are the availability of frequency and/or synchronous equatorial satellite positions and the cost of individual user Earth terminals. The former could be ameliorated through the reuse of frequencies, the use of higher frequency bands, and the reduction of antenna side lobes. The latter limitation requires innovative hardware, design, careful system design, and large scale production.

An integrated Ka/Ku-band payload for personal, mobile and private business communications

NASA Technical Reports Server (NTRS)

Hayes, Edward J.; Keelty, J. Malcolm

1991-01-01

The Canadian Department of Communications has been studying options for a government-sponsored demonstration payload to be launched before the end of the century. A summary of the proposed system concepts and network architectures for providing an advanced private business network service at Ku-band and personal and mobile communications at Ka-band is presented. The system aspects addressed include coverage patterns, traffic capacity, and grade of service, multiple access options as well as special problems, such as Doppler in mobile applications. Earth terminal types and the advanced payload concept proposed in a feasibility study for the demonstration mission are described. This concept is a combined Ka-band/Ku-band payload which incorporates a number of advanced satellite technologies including a group demodulator to convert single-channel-per-carrier frequency division multiple access uplink signals to a time division multiplex downlink, on-board signal regeneration, and baseband switching to support packet switched data operation. The on-board processing capability of the payload provides a hubless VSAT architecture which permits single-hop full mesh interconnectivity. The Ka-band and Ku-band portions of the payload are fully integrated through an on-board switch, thereby providing the capability for fully integrated services, such as using the Ku-band VSAT terminals as gateway stations for the Ka-band personal and mobile communications services.

Statistical and Prediction modeling of the Ka Band Using Experimental Results from ACTS Propagation Terminals at 20.185 and 27.505 GHZ

NASA Technical Reports Server (NTRS)

Ogunwuyi, Oluwatosin O.

2004-01-01

With the increase in demand for wireless communication services, most of the operating frequency bands have become very congested. The increase of wireless costumers is only fractional contribution to this phenomenon. The demand for more services such as video streams and internet explorer which require a lot of band width has been a more significant contributor to the congestion in a communication system. One way to increase the amount of information or data per unit of time transmitted with in a wireless communication system is to use a higher radio frequency. However in spite the advantage available in the using higher frequency bands such as, the Ka-band, higher frequencies also implies short wavelengths. And shorter wavelengths are more susceptible to rain attenuation. Until the Advanced Communication Technology Satellite (ACTS) was launched, the Ka- band frequency was virtually unused - the majority of communication satellites operated in lower frequency bands called the C- and Ku- bands. Ka-band is desirable because its higher frequency allows wide bandwidth applications, smaller spacecraft and ground terminal components, and stronger signal strength. Since the Ka-band is a high frequency band, the millimeter wavelengths of the signals are easily degraded by rain. This problem known as rain fade or rain attenuation The Advanced Communication Technology Satellite (ACTS) propagation experiment has collected 5 years of Radio Frequency (RF) attenuation data from December 1993 to November 1997. The objective of my summer work is to help develop the statistics and prediction techniques that will help to better characterize the Ka Frequency band. The statistical analysis consists of seasonal and cumulative five-year attenuation statistics for the 20.2 and 27.5 GHz. The cumulative five-year results give the link outage that occurs for a given link margin. The experiment has seven ground station terminals that can be attributed to a unique rain zone climate. The locations are White Sands, NM, Tampa, Fly Clarksburg, MD, Norman, OK, Ft. Collins, COY Vancouver, BC, and Fairbanks, AK. The analysis will help us to develop and define specific parameters that will help system engineers develop the appropriated instrumentation and structure for a Ka-band wireless communication systems and networks.

Interfacial Coupling Effect on Electron Transport in MoS2/SrTiO3 Heterostructure: An Ab-initio Study.

PubMed

Bano, Amreen; Gaur, N K

2018-01-15

A variety of theoretical and experimental works have reported several potential applications of MoS 2 monolayer based heterostructures (HSs) such as light emitting diodes, photodetectors and field effect transistors etc. In the present work, we have theoretically performed as a model case study, MoS 2 monolayer deposited over insulating SrTiO 3 (001) to study the band alignment at TiO 2 termination. The interfacial characteristics are found to be highly dependent on the interface termination. With an insulating oxide material, a significant band gap (0.85eV) is found in MoS 2 /TiO 2 interface heterostructure (HS). A unique electronic band profile with an indirect band gap (0.67eV) is observed in MoS 2 monolayer when confined in a cubic environment of SrTiO 3 (STO). Adsorption analysis showed the chemisorption of MoS 2 on the surface of STO substrate with TiO 2 termination which is justified by the charge density calculations that shows the existence of covalent bonding at the interface. The fabrication of HS of such materials paves the path for developing the unprecedented 2D materials with exciting properties such as semiconducting devices, thermoelectric and optoelectronic applications.

The investigation of Ag/ZnO interface system by first principle: The structural, electronic and optical properties

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

Cheng, Hai-Xia; Wang, Xiao-Xu; Beijing Computing Center, Beijing 100094

Ag/ZnO interfaces have been investigated for both of Zn-termination and O-termination by the first principle based on density functional theory. Our calculations demonstrate that the Ag atoms go inward from the Ag/ZnO interface, and the Zn and O atoms are all move outward bulk in the Zn-termination interface, and the changes are just opposite for O-termination. These behaviors are in agreement with the other studies in literatures. Furthermore, an expansion situation is observed in the first two Zn-O bilayer and first three Ag monolayers for both of Zn-termination and O-termination interfaces by comparing with the pure ZnO(0001) and Ag(111) surfaces.more » Moreover, the valence-band both of O-2p and Zn-3d states of Ag/ZnO interface gradual close to Femi level as the Zn, O atoms locate at the deeper layer for Zn-termination, but it is the other way round for O-termination. Calculated absorption spectrum indicates that the absorption intensity of Zn-termination interface is stronger than that of O-termination in the lower energy range (visible light region). These properties of ZnO surfaces are also evaluated for comparison with interfaces. - Graphical abstract: The structures of Ag/ZnO interface: Zn-termination (left) and O-termination (right). In this Ag/ZnO interface system, the ZnO (0001) surface is rotated 30°(R30), and Ag (111) surface is built (2×2) supercell, then a (2×√3) R30 Ag/ZnO interface is constructed using the supercell method (i.e. periodically repeated slabs). The lattice mismatch of (2×√3) R30 Ag/ZnO (2.6% mismatch) is smaller than that of (1×1) Ag/ZnO (11% mismatch).« less

ACTS Ka-band Propagation Research in a Spatially Diversified Network with Two USAT Ground Stations

NASA Technical Reports Server (NTRS)

Kalu, Alex; Acousta, R.; Durand, S.; Emrich, Carol; Ventre, G.; Wilson, W.

1999-01-01

Congestion in the radio spectrum below 18 GHz is stimulating greater interest in the Ka (20/30 GHz) frequency band. Transmission at these shorter wavelengths is greatly influenced by rain resulting in signal attenuation and decreased link availability. The size and projected cost of Ultra Small Aperture Terminals (USATS) make site diversity methodology attractive for rain fade compensation. Separation distances between terminals must be small to be of interest commercially. This study measures diversity gain at a separation distance <5 km and investigates utilization of S-band weather radar reflectivity in predicting diversity gain. Two USAT ground stations, separated by 2.43 km for spatial diversity, received a continuous Ka-band tone sent from NASA Glenn Research Center via the Advanced Communications Technology Satellite (ACTS) steerable antenna beam. Received signal power and rainfall were measured, and Weather Surveillance Radar-1998 Doppler (WSR-88D) data were obtained as a measure of precipitation along the USAT-to-ACTS slant path. Signal attenuation was compared for the two sites, and diversity gain was calculated for fades measured on eleven days. Correlation of WSR-88D S-band reflectivity with measured Ka-band attenuation consisted of locating radar volume elements along each slant path, converting reflectivity to Ka-band attenuation with rain rate calculation as an intermediate step. Specific attenuation for each associated path segment was summed, resulting in total attenuation along the slant path. Derived Ka-band attenuation did not correlate closely with empirical data (r = 0.239), but a measured signal fade could be matched with an increase in radar reflectivity in all fade events. Applying a low pass filter to radar reflectivity prior to deriving Ka-band attenuation improved the correlation between measured and derived signal attenuation (r = 0.733). Results indicate that site diversity at small separation distances is a viable means of rain fade compensation, and that existing models underestimate diversity gain for a subtropical climate such as Florida. Also, filtered WSR-88D reflectivity can be used for optimizing diversity terminal placement by comparing derived Ka- band attenuation between the diversity sites.

47 CFR 27.17 - Discontinuance of service in the 2000-2020 MHz and 2180-2200 MHz bands.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 2 2013-10-01 2013-10-01 false Discontinuance of service in the 2000-2020 MHz... § 27.17 Discontinuance of service in the 2000-2020 MHz and 2180-2200 MHz bands. (a) Termination of authorization. A licensee's AWS authorization in the 2000-2020 MHz and 2180-2200 MHz bands will automatically...

On the role of spatial position of bridged oxygen atoms as surface passivants on the ground-state gap and photo-absorption spectrum of silicon nano-crystals

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

Nazemi, Sanaz; Soleimani, Ebrahim Asl; Pourfath, Mahdi, E-mail: pourfath@ut.ac.ir, E-mail: pourfath@iue.tuwien.ac.at

2015-11-28

Silicon nano-crystals (NCs) are potential candidates for enhancing and tuning optical properties of silicon for optoelectronic and photo-voltaic applications. Due to the high surface-to-volume ratio, however, optical properties of NC result from the interplay of quantum confinement and surface effects. In this work, we show that both the spatial position of surface terminants and their relative positions have strong effects on NC properties as well. This is accomplished by investigating the ground-state HOMO-LUMO band-gap, the photo-absorption spectra, and the localization and overlap of HOMO and LUMO orbital densities for prototype ∼1.2 nm Si{sub 32–x}H{sub 42–2x}O{sub x} hydrogenated silicon NC with bridgedmore » oxygen atoms as surface terminations. It is demonstrated that the surface passivation geometry significantly alters the localization center and thus the overlap of frontier molecular orbitals, which correspondingly modifies the electronic and optical properties of NC.« less

Electronic, Magnetic, and Transport Properties of Polyacrylonitrile-Based Carbon Nanofibers of Various Widths: Density-Functional Theory Calculations

NASA Astrophysics Data System (ADS)

Partovi-Azar, P.; Panahian Jand, S.; Kaghazchi, P.

2018-01-01

Edge termination of graphene nanoribbons is a key factor in determination of their physical and chemical properties. Here, we focus on nitrogen-terminated zigzag graphene nanoribbons resembling polyacrylonitrile-based carbon nanofibers (CNFs) which are widely studied in energy research. In particular, we investigate magnetic, electronic, and transport properties of these CNFs as functions of their widths using density-functional theory calculations together with the nonequilibrium Green's function method. We report on metallic behavior of all the CNFs considered in this study and demonstrate that the narrow CNFs show finite magnetic moments. The spin-polarized electronic states in these fibers exhibit similar spin configurations on both edges and result in spin-dependent transport channels in the narrow CNFs. We show that the partially filled nitrogen dangling-bond bands are mainly responsible for the ferromagnetic spin ordering in the narrow samples. However, the magnetic moment becomes vanishingly small in the case of wide CNFs where the dangling-bond bands fall below the Fermi level and graphenelike transport properties arising from the π orbitals are recovered. The magnetic properties of the CNFs as well as their stability have also been discussed in the presence of water molecules and the hexagonal boron nitride substrate.

Development of a mobile satellite communication unit

NASA Technical Reports Server (NTRS)

Suzuki, Ryutaro; Ikegami, Tetsushi; Hamamoto, Naokazu; Taguchi, Tetsu; Endo, Nobuhiro; Yamamoto, Osamu; Ichiyoshi, Osamu

1988-01-01

A compact 210(W) x 280(H) x 330(D) mm mobile terminal capable of transmitting voice and data through L-band mobile satellites is described. The Voice Codec can convert an analog voice to or from digital codes at rates of 9.6, 8 and 4.8 kb/s by an MPC algorithm. The terminal functions with a single 12 V power supplied vehicle battery. The equipment can operate at any L-band frequency allocated for mobile uses in a full duplex mode and will soon be put into a field test via Japans's ETS-V satellite.

IR-Monitored Photolysis of CO-Inhibited Nitrogenase: A Major EPR-Silent Species with Coupled Terminal CO Ligands

PubMed Central

Yan, Lifen; Dapper, Christie H.; Scott, Aubrey D.; Newton, William E.

2015-01-01

We have used Fourier transform infrared spectroscopy (FT-IR) to observe the photolysis and recombination of a novel EPR-silent CO-inhibited form of α-H195Q nitrogenase from Azotobacter vinelandii. Photolysis at 4 K yields a strong negative IR difference band at 1938 cm−1, along with a weaker negative feature at 1911 cm−1. These bands and the associated chemical species have both been assigned the label ‘Hi-3’. A positive band at 1921 cm−1 is assigned to the ‘Lo-3’ photoproduct. By using an isotopic mixture of 12C16O and 13C18O, we show that the Hi-3 bands arise from coupling of two similar CO oscillators with one uncoupled frequency at ~1917 cm−1. Although in previous studies Lo-3 was not observed to recombine, by extending the observation range to 200–240 K we found that recombination to Hi-3 does indeed occur, with an activation energy of ~6.5 kJ mol−1. The frequencies of the Hi-3 bands suggest terminal CO ligation. We tested this hypothesis with DFT calculations on models with terminal CO ligands on Fe2 and Fe6 of the FeMo-cofactor. An S = 0 model with both CO ligands in exo positions predicts symmetric and asymmetric stretches at 1938 and 1909 cm−1 respectively, with relative band intensities of ~3.5:1, in good agreement with experiment. From the observed IR intensities, we find that Hi-3 is present at a concentration about equal to that of the EPR-active Hi-1 species. The relevance of Hi-3 to the nitrogenase catalytic mechanism and its recently discovered Fischer-Tropsch chemistry is discussed. PMID:23136072

Dual Band Deep Ultraviolet AlGaN Photodetectors

NASA Technical Reports Server (NTRS)

Aslam, S.; Miko, L.; Stahle, C.; Franz, D.; Pugel, D.; Guan, B.; Zhang, J. P.; Gaska, R.

2007-01-01

We report on the design, fabrication and characterization of a back-illuminated voltage bias selectable dual-band AlGaN UV photodetector. The photodetector can separate UVA and W-B band radiation by bias switching a two terminal n-p-n homojunction structure that is fabricated in the same pixel. When a forward bias is applied between the top and bottom electrodes, the detector can sense UV-A and reject W-B band radiation. Alternatively, under reverse bias, the photodetector can sense UV-B and reject UV-A band radiation.

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).

Advanced mobile satellite communications system using Ka and MM-wave bands in Japan's R and D satellite project

NASA Technical Reports Server (NTRS)

Isobe, Shunkichi; Ohmori, Shingo; Hamamoto, Naokazu; Yamamoto, Minoru

1991-01-01

Communications Research Laboratory (CRL) studied an advanced mobile satellite communications system using Ka and millimeter-wave bands in the R&D Satellite project. The project started in 1990 and the satellite will be launched in 1997. On-board multi-beam interconnecting is one of basic functions to realize one-hop connection among Very Small Aperture Terminals (VSATs), mobile, and hand-held terminals in future mobile satellite communications system. An Intermediate Frequency (IF) filter bank and regenerative transponder are suitable for this function. The transponder configuration of an advanced mobile communications mission of the R&D Satellite for experiment is shown. High power transmitters of Ka and millimeter-wave bands, a 3x3 IF filter band and Single Channel Per Carrier/Time Division Multiplexing (SCPC/TDM) regenerative MODEMS, which will be boarded on the R&D Satellite, are being developed for the purpose of studying the feasibility of advanced mobile communications system.

Atomically precise lateral modulation of a two-dimensional electron liquid in anatase TiO 2 thin films

DOE PAGES

Wang, Zhiming; Zhong, Z.; Walker, S. McKeown; ...

2017-03-10

Engineering the electronic band structure of two-dimensional electron liquids (2DELs) confined at the surface or interface of transition metal oxides is key to unlocking their full potential. Here we describe a new approach to tailoring the electronic structure of an oxide surface 2DEL demonstrating the lateral modulation of electronic states with atomic scale precision on an unprecedented length scale comparable to the Fermi wavelength. To this end, we use pulsed laser deposition to grow anatase TiO 2 films terminated by a (1 x 4) in-plane surface reconstruction. Employing photo-stimulated chemical surface doping we induce 2DELs with tunable carrier densities thatmore » are confined within a few TiO 2 layers below the surface. Subsequent in situ angle resolved photoemission experiments demonstrate that the (1 x 4) surface reconstruction provides a periodic lateral perturbation of the electron liquid. Furthermore, this causes strong backfolding of the electronic bands, opening of unidirectional gaps and a saddle point singularity in the density of states near the chemical potential.« less

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.

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.

Optimization in the design of a 12 gigahertz low cost ground receiving system for broadcast satellites. Volume 1: System design, performance, and cost analysis

NASA Technical Reports Server (NTRS)

Ohkubo, K.; Han, C. C.; Albernaz, J.; Janky, J. M.; Lusignan, B. B.

1972-01-01

The technical and economical feasibility of using the 12 GHz band for broadcasting from satellites were examined. Among the assigned frequency bands for broadcast satellites, the 12 GHz band system offers the most channels. It also has the least interference on and from the terrestrial communication links. The system design and analysis are carried out on the basis of a decision analysis model. Technical difficulties in achieving low-cost 12 GHz ground receivers are solved by making use of a die cast aluminum packaging, a hybrid integrated circuit mixer, a cavity stabilized Gunn oscillator and other state-of-the-art microwave technologies for the receiver front-end. A working model was designed and tested, which used frequency modulation. A final design for the 2.6 GHz system ground receiver is also presented. The cost of the ground-terminal was analyzed and minimized for a given figure-of-merit (a ratio of receiving antenna gain to receiver system noise temperature). The results were used to analyze the performance and cost of the whole satellite system.

Tunable graphene-based mid-infrared plasmonic multispectral and narrow band-stop filter

NASA Astrophysics Data System (ADS)

Wang, Xianjun; Meng, Hongyun; Liu, Shuai; Deng, Shuying; Jiao, Tao; Wei, Zhongchao; Wang, Faqiang; Tan, Chunhua; Huang, Xuguang

2018-04-01

In this paper, we numerically investigate the band-stop properties of single- or few-layers doped graphene ribbon arrays operating in the mid-infrared region by finite-difference time-domain method (FDTD). A perfect band-stop filter with extinction ratio (ER) ∼17 dB, 3 dB bandwidth ∼200 nm and the resonance notch located at 6.64 μm can be achieved. And desired working regions can be obtained by tuning the Fermi level (E f ) of the graphene ribbons and the geometrical parameters of the structure. Besides, by tuning the Fermi level of odd or even graphene ribbons with terminal gate voltage, we can achieve a dual-circuit switch with four states combinations of on-to-off. Furthermore, the multiple filter notches can be achieved by stacking few-layers structure, and the filter dips can be dynamically tuned to achieve the tunability and selective characteristics by tuning the Fermi-level of the graphene ribbons in the system. We believe that our proposal has the potential applications in selective filters and active plasmonic switching in the mid-infrared region.

Research of the Dispersity of the Functional Sericite/Methylphenyl- Silicone Resin

PubMed Central

Jiang, B.; Zhu, C. C.; Huang, Y. D.

2015-01-01

In order to improve the homogeneity and dispersity of the sericite in methylphenyl-silicone resin, the agglomerate state of the sericites was controlled effectively. The dispersive model of the sericite in methylphenyl-silicone resin was designed also. First, the modified sericite was prepared using hexadecyl trimethyl ammonium bromide as the intercalating agent. Then, functional sericite was incorporated into methylphenyl-silicone by terminal hydroxyl. The structure and dispersive performance of the hybrid polymers was charactered by analytical instruments. Scanning electron microscopy and Transmission electron microscope, Laser scanning confocal microscope and X-ray diffraction analysis showed that functional sericite was dispersed homogeneously in methylphenyl-silicone resin matrix. X-ray photoelectron spectroscopy analysis showed that the absorption peaks of the Si-OH band of methylphenyl-silicone resin were decreased and the Si-O-Si band was increased. This change evidently showed a significant role to enhance the reaction degree of the functional sericite in methylphenyl-silicone resin. PMID:26061002

Technical characteristics of the OmniTRACS: The first operation mobile Ku-band satellite communications system

NASA Technical Reports Server (NTRS)

Antonio, Franklin P.; Gilhousen, Klein S.; Jacobs, Irwin M.; Weaver, Linday A., Jr.

1988-01-01

The techinical characteristics of the OmniTRACS system are described. The system is the first operational mobile Ku-band satellite communications system and provides two-way message and position determination service to mobile terminals using existing Ku-band satellites. Interference to and from the system is minimized by the use of special spread-spectrum techniques, together with low power and low data rate transmissions.

Karyotype differentiation of four Cestrum species (Solanaceae) revealed by fluorescent chromosome banding and FISH

PubMed Central

2009-01-01

The karyotypes of four South American species of Cestrum (C. capsulare,C. corymbosum,C. laevigatum and C. megalophylum) were studied using conventional staining, C-CMA/DAPI chromosome banding and FISH with 45S and 5S rDNA probes. The karyotypes showed a chromosome number of 2n = 2x = 16, with metacentric chromosomes, except for the eighth submeta- to acrocentric pair. Several types of heterochromatin were detected, which varied in size, number, distribution and base composition. The C-CMA+ bands and 45S rDNA were located predominantly in terminal regions. The C-CMA + /DAPI + bands appeared in interstitial and terminal regions, and the C-DAPI + bands were found in all chromosome regions. The 5S rDNA sites were observed on the long arm of pair 8 in all species except C. capsulare, where they were found in the paracentromeric region of the long arm of pair 4. The differences in band patterns among the species studied here, along with data from other nine species reported in the literature, suggest that the bands are dispersed in an equilocal and non-equilocal manner and that structural rearrangements can be responsible for internal karyotype diversification. However, it is important to point out that the structural changes involving repetitive segments did not culminate in substantial changes in the general karyotype structure concerning chromosome size and morphology. PMID:21637687

Multi-band gap and new solar cell options workshop

NASA Technical Reports Server (NTRS)

Hutchby, J.; Timmons, M.; Olson, J. M.

1993-01-01

Discussions of the multi-band gap (MBG) and new solar cell options workshop are presented. Topics discussed include: greater than 2 terminal cells; radiation damage preventing development of MBG cells for space; lattice matching; measurement of true performance; future of II-VI materials in MBG devices; and quaternaries.

42 CFR 447.50 - Cost sharing: Basis and purpose.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) MEDICAL ASSISTANCE PROGRAMS PAYMENTS FOR SERVICES Payments: General Provisions Cost Sharing § 447... the following four criteria: (A) Is a member of a tribe, band, or other organized group of Indians, including those tribes, bands, or groups terminated since 1940 and those recognized now or in the future by...

Health Education Telecommunications Experiment

NASA Technical Reports Server (NTRS)

Whalen, A. A.

1975-01-01

The Health/Education Telecommunications Experiment carried out with Applications Technology Satellite-6 is described. The experiment tested the effectiveness of color television broadcasts to over 120 low-cost receivers in rural areas. Five types of earth stations were involved: receive-only terminals (ROT), an intensive terminal consisting of the ROT plus a VHF transmitter and receiver; comprehensive S and C-band terminals having the capability of transmitting the video signal plus four audio channels; and the main originating stations. Additional supporting elements comprise 120 video receive terminals, 51 telephony transceivers, and 8 video originating terminals of 3 different parts. Technical parameters were measured to within 1 dB of the calculated values.

Description and performance of a digital mobile satellite terminal

NASA Technical Reports Server (NTRS)

Lay, N.; Jedrey, T.; Parkyn, J.; Divsalar, D.

1990-01-01

A major goal of the Mobile Satellite Experiment (MSAT-X) program at the Jet Propulsion Lab (JPL) is the development of an advanced digital terminal for use in land mobile satellite communication. The terminal has been developed to minimize the risk of applying advanced technologies to future commercial mobile satellite systems (MSS). Testing with existing L band satellites was performed in fixed, land mobile and aeronautical mobile environments. JPL's development and tests of its mobile terminal have demonstrated the viability of narrowband digital voice communications in a land mobile environment through geostationary satellites. This paper provides a consolidated description of the terminal architecture and the performance of its individual elements.

Ka-Band Atmospheric Phase Stability Measurements in Goldstone, CA; White Sands, NM; and Guam

NASA Technical Reports Server (NTRS)

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

2014-01-01

As spacecraft communication links are driven to higher frequencies (e.g. Ka-band) both by spectrum congestion and the appeal of higher data rates, the propagation phenomena at these frequencies must be well characterized for effective system design. In particular, the phase stability of a site at a given frequency will govern whether or not the site is a practical location for an antenna array, particularly if uplink capabilities are desired. Propagation studies to characterize such phenomena must be done on a site-by-site basis due to the wide variety of climates and weather conditions at each ground terminal. Accordingly, in order to statistically characterize the atmospheric effects on Ka-Band links, site test interferometers (STIs) have been deployed at three of NASA's operational sites to directly measure each site's tropospheric phase stability. Using three years of results from these experiments, this paper will statistically characterize the simultaneous atmospheric phase noise measurements recorded by the STIs deployed at the following ground station sites: the Goldstone Deep Space Communications Complex near Barstow, CA; the White Sands Ground Terminal near Las Cruces, NM; and the Guam Remote Ground Terminal on the island of Guam.

Super-Eddington accretion on to the neutron star NGC 7793 P13: Broad-band X-ray spectroscopy and ultraluminous X-ray sources

NASA Astrophysics Data System (ADS)

Walton, D. J.; Fürst, F.; Harrison, F. A.; Stern, D.; Bachetti, M.; Barret, D.; Brightman, M.; Fabian, A. C.; Middleton, M. J.; Ptak, A.; Tao, L.

2018-02-01

We present a detailed, broad-band X-ray spectral analysis of the ultraluminous X-ray source (ULX) pulsar NGC 7793 P13, a known super-Eddington source, utilizing data from the XMM-Newton, NuSTAR and Chandra observatories. The broad-band XMM-Newton+NuSTAR spectrum of P13 is qualitatively similar to the rest of the ULX sample with broad-band coverage, suggesting that additional ULXs in the known population may host neutron star accretors. Through time-averaged, phase-resolved and multi-epoch studies, we find that two non-pulsed thermal blackbody components with temperatures ∼0.5 and 1.5 keV are required to fit the data below 10 keV, in addition to a third continuum component which extends to higher energies and is associated with the pulsed emission from the accretion column. The characteristic radii of the thermal components appear to be comparable, and are too large to be associated with the neutron star itself, so the need for two components likely indicates the accretion flow outside the magnetosphere is complex. We suggest a scenario in which the thick inner disc expected for super-Eddington accretion begins to form, but is terminated by the neutron star's magnetic field soon after its onset, implying a limit of B ≲ 6 × 1012 G for the dipolar component of the central neutron star's magnetic field. Evidence of similar termination of the disc in other sources may offer a further means of identifying additional neutron star ULXs. Finally, we examine the spectrum exhibited by P13 during one of its unusual 'off' states. These data require both a hard power-law component, suggesting residual accretion on to the neutron star, and emission from a thermal plasma, which we argue is likely associated with the P13 system.

Cell wall biogenesis in Oocystis: experimental alteration of microfibril assembly and orientation.

PubMed

Montezinos, D; Brown, R M

1978-01-01

Cell wall biogenesis in the unicellular green alga Oocystis apiculata has been studied. Under normal growth conditions, a cell wall with ordered microfibrils is synthesized. In each layer there are rows of parallel microfibrils. Layers are nearly perpendicular to each other. Terminal linear synthesizing complexes are located in the plasma membrane, and they are capable of bidirectional synthesis of cellulose microfibrils. Granule bands associated with the inner leaflet of the plasma membrane appear to control the orientation of newly synthesized microfibrils. Subcortical microtubules also are present during wall synthesis. Patterns of cell wall synthesis were studied after treatment with EDTA and EGTA as well as divalent cations (MgSO4, CaSO4, Cacl2). 0.1 M EDTA treatment for 15 min results in the disassociation of the terminal complexes from the ends of microfibrils. EDTA-treated cells followed by 15 min treatment with MgSO4 results in reaggregation of the linear complexes into a paired state, remote from the original ends to which they were associated. After 90 min treatment with MgSO4, normal synthesis resumes. EGTA and calcium salts do not affect the linear complexes or microfibril orientation. Treatments with colchicine and vinblastine sulphate do not depolymerize the microtubles, but the wall microfibril orientation is altered. With colchicine or vinblastine, the change in orientation from layer to layer is inhibited. The process is reversible upon removal of the drugs. Lumicolchicine has no effect upon microfibril orientation, but granule bands are disorganized. Treatment with coumarin, a known inhibitor of cellulose synthesis, causes the loss of visualization of subunits of the terminal complexes. The possibility of the existence of a membrane-associated colchicine-sensitive orientation protein for cellulose microfibrils is discussed. Transmembrane modulation of microfibril synthesis and orientation is presented.

Ka-Band Radar Terminal Descent Sensor

NASA Technical Reports Server (NTRS)

Pollard, Brian; Berkun, Andrew; Tope, Michael; Andricos, Constantine; Okonek, Joseph; Lou, Yunling

2007-01-01

The terminal descent sensor (TDS) is a radar altimeter/velocimeter that improves the accuracy of velocity sensing by more than an order of magnitude when compared to existing sensors. The TDS is designed for the safe planetary landing of payloads, and may be used in helicopters and fixed-wing aircraft requiring high-accuracy velocity sensing

Ab initio density functional theory study on the atomic and electronic structure of GaP/Si(001) heterointerfaces

NASA Astrophysics Data System (ADS)

Romanyuk, O.; Supplie, O.; Susi, T.; May, M. M.; Hannappel, T.

2016-10-01

The atomic and electronic band structures of GaP/Si(001) heterointerfaces were investigated by ab initio density functional theory calculations. Relative total energies of abrupt interfaces and mixed interfaces with Si substitutional sites within a few GaP layers were derived. It was found that Si diffusion into GaP layers above the first interface layer is energetically unfavorable. An interface with Si/Ga substitution sites in the first layer above the Si substrate is energetically the most stable one in thermodynamic equilibrium. The electronic band structure of the epitaxial GaP/Si(001) heterostructure terminated by the (2 ×2 ) surface reconstruction consists of surface and interface electronic states in the common band gap of two semiconductors. The dispersion of the states is anisotropic and differs for the abrupt Si-Ga, Si-P, and mixed interfaces. Ga 2 p , P 2 p , and Si 2 p core-level binding-energy shifts were computed for the abrupt and the lowest-energy heterointerface structures. Negative and positive core-level shifts due to heterovalent bonds at the interface are predicted for the abrupt Si-Ga and Si-P interfaces, respectively. The distinct features in the heterointerface electronic structure and in the core-level shifts open new perspectives in the experimental characterization of buried polar-on-nonpolar semiconductor heterointerfaces.

UTa{sub 2}O(S{sub 2}){sub 3}Cl{sub 6}: A ribbon structure containing a heterobimetallic 5d-5f M{sub 3} cluster

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

Wells, Daniel M.; Chan, George H.; Ellis, Donald E.

2010-02-15

A new solid-state compound containing a heterobimetallic cluster of U and Ta, UTa{sub 2}O(S{sub 2}){sub 3}Cl{sub 6}, has been synthesized and its structure has been characterized by single-crystal X-ray diffraction methods. UTa{sub 2}O(S{sub 2}){sub 3}Cl{sub 6} was synthesized from UCl{sub 4} and Ta{sub 1.2}S{sub 2} at 883 K. The O is believed to have originated in the Ta{sub 1.2}S{sub 2} reactant. The compound crystallizes in the space group P1-bar of the triclinic system. The structure comprises a UTa{sub 2} unit bridged by mu{sub 2}-S{sub 2} and mu{sub 3}-O groups. Each Ta atom bonds to two mu{sub 2}-S{sub 2}, the mu{submore » 3}-O, and two terminal Cl atoms. Each U atom bonds to two mu{sub 2}-S{sub 2}, the mu{sub 3}-O, and four Cl atoms. The Cl atoms bridge in pairs to neighboring U atoms to form a ribbon structure. The bond distances are normal and are consistent with formal oxidation states of +IV/+V/-II/-I/-I for U/Ta/O/S/Cl, respectively. The optical absorbance spectrum displays characteristic transition peaks near the absorption edge. Density functional theory was used to assign these peaks to transitions between S{sup 1-} valence-band states and empty U 5f-6d hybrid bands. Density-of-states analysis shows overlap between Ta 5d and U bands, consistent with metal-metal interactions. - The UTa2O(S2)3Cl6 cluster with completed coordination sphere around uranium« less

Communications availability: Estimation studies at AMSC

NASA Technical Reports Server (NTRS)

Sigler, C. Edward, Jr.

1994-01-01

The results of L-band communications availability work performed to date are presented. Results include a L-band communications availability estimate model and field propagation trials using an INMARSAT-M terminal. American Mobile Satellite Corporation's (AMSC's) primary concern centers on availability of voice communications intelligibility, with secondary concerns for circuit-switched data and fax. The model estimates for representative terrain/vegetation areas are applied to the contiguous U.S. for overall L-band communications availability estimates.

The significance of cytogenetics for the study of karyotype evolution and taxonomy of water bugs (Heteroptera, Belostomatidae) native to Argentina

PubMed Central

Gabriela, Chirino Mónica; Papeschi, Alba Graciela; Bressa, María José

2013-01-01

Abstract Male meiosis behaviour and heterochromatin characterization of three big water bug species were studied. Belostoma dentatum (Mayr, 1863), Belostoma elongatum Montandon, 1908 and Belostoma gestroi Montandon, 1903 possess 2n = 26 + X1X2Y (male). In these species, male meiosis is similar to that previously observed in Belostoma Latreille, 1807. In general, autosomal bivalents show a single chiasma terminally located and divide reductionally at anaphase I. On the other hand, sex chromosomes are achiasmatic, behave as univalents and segregate their chromatids equationally at anaphase I. The analysis of heterochromatin distribution and composition revealed a C-positive block at the terminal region of all autosomes in Belostoma dentatum, a C-positive block at the terminal region and C-positive interstitial dots on all autosomes in Belostoma elongatum, and a little C-positive band at the terminal region of autosomes in Belostoma gestroi. A C-positive band on one bivalent was DAPI negative/CMA3 positive in the three species. The CMA3-bright band, enriched in GC base pairs, was coincident with a NOR detected by FISH. The results obtained support the hypothesis that all species of Belostoma with multiple sex chromosome systems preserve NORs in autosomal bivalents. The karyotype analyses allow the cytogenetic characterization and identification of these species belonging to a difficult taxonomic group. Besides, the cytogenetic characterization will be useful in discussions about evolutionary trends of the genome organization and karyotype evolution in this genus. PMID:24260694

Dark Bands on Europa

NASA Technical Reports Server (NTRS)

1996-01-01

Dark crisscrossing bands on Jupiter's moon Europa represent widespread disruption from fracturing and the possible eruption of gases and rocky material from the moon's interior in this four-frame mosaic of images from NASA's Galileo spacecraft. These and other features suggest that soft ice or liquid water was present below the ice crust at the time of disruption. The data do not rule out the possibility that such conditions exist on Europa today. The pictures were taken from a distance of 156,000 kilometers (about 96,300 miles) on June 27, 1996. Many of the dark bands are more than 1,600 kilometers (1,000 miles) long, exceeding the length of the San Andreas fault of California. Some of the features seen on the mosaic resulted from meteoritic impact, including a 30- kilometer (18.5 mile) diameter crater visible as a bright scar in the lower third of the picture. In addition, dozens of shallow craters seen in some terrains along the sunset terminator zone (upper right shadowed area of the image) are probably impact craters. Other areas along the terminator lack craters, indicating relatively youthful surfaces, suggestive of recent eruptions of icy slush from the interior. The lower quarter of the mosaic includes highly fractured terrain where the icy crust has been broken into slabs as large as 30 kilometers (18.5 miles) across. The mosaic covers a large part of the northern hemisphere and includes the north pole at the top of the image. The sun illuminates the surface from the left. The area shown is centered on 20 degrees north latitude and 220 degrees west longitude and is about as wide as the United States west of the Mississippi River. The Galileo mission is managed by NASA's Jet Propulsion Laboratory.

High failure rate of the laparoscopic-adjustable gastric band as a primary bariatric procedure.

PubMed

Kindel, Tammy; Martin, Emily; Hungness, Eric; Nagle, Alex

2014-01-01

Determinants of success of a bariatric procedure are many but paramount is the ability to durably produce significant and reliable weight loss. We sought to determine the primary success of the laparoscopic adjustable gastric band (LAGB) by defining failure as clinical weight loss failure with an intact band (excess weight loss [EWL]<20%) or band removal (terminal removal or conversion to a secondary bariatric procedure). A retrospective chart review was performed on patients who underwent an LAGB as a primary bariatric procedure between January 2003 and December 2007. Data collected included body mass index (BMI), weight, postoperative follow-up length, EWL, and adjustment number, as well as complications of the LAGB. Sixteen of 120 patients had the band removed. Nine were terminally removed for unmanageable symptoms, and 7 were converted to an alternative bariatric procedure. The average follow-up for the 104 patients with an intact band was 4.8 years. The average EWL for successful intact bands was 44.9±19.4%; however, an additional 35.6% of patients had an EWL<20%. Patients with an EWL<20% had a significantly higher preoperative BMI and fewer band adjustments. In total, 44% of patients had band failure because of clinical weight loss failure (31%) or eventual band removal (13%). This study finds that the LAGB failed as a primary bariatric procedure for 44% of patients because of either inadequate weight loss or adequate weight loss with unmanageable symptoms. This suggests that the LAGB should be abandoned as a primary bariatric procedure for the majority of morbidly obese patients because of its high failure rate. Copyright © 2014 American Society for Bariatric Surgery. Published by Elsevier Inc. All rights reserved.

Microcephaly/lymphedema and terminal deletion of the long arm of chromosome 13

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

Fryns, J.P.

1995-07-03

Recently, we examined a 2-year-old boy with the association of microcephaly and significant pedal edema that extended to the distal parts of the legs. Prometaphase chromosome studies showed a small terminal deletion in the long arm of chromosome 13 of band 13q34, karyotype 46,XY,del(13)(q34{yields}qter). The present finding of a small terminal 13q34 deletion in this young boy with microcephaly/lymphedema is a first indication that the lymphedema/microcephaly association can be due to a small terminal 13q deletion. 2 refs.

2-Octyl thiophene based three ring mesogens: solid state (13)C NMR and XRD investigations.

PubMed

Veeraprakash, B; Lobo, Nitin P; Narasimhaswamy, T; Mandal, A B

2015-08-14

2-Octyl thiophene based three-ring mesogens namely 4-n-alkoxyphenyl 4-(5-n-octyl-2-thienyl)benzoates are synthesized by employing palladium acetate based direct arylation. The alkoxy terminal is varied with even carbons from C2 to C14 and enantiotropic polymesomorphism is noticed for all the homologs. Accordingly, phase sequence consisting of nematic, smectic A, smectic C and smectic B is seen for mesogens with terminal chains C6, C8, C10 and C12 on cooling the isotropic phase. For mesogens with C2, C4, C8 and C10 terminal alkoxy chains, the mesophase assignment from hot-stage optical microscopy and differential scanning calorimetry is further confirmed by variable temperature powder X-ray diffraction measurements. The appearance of smectic B phase is established by noticing sharp and intense peaks in both small-angle and wide-angle regions. For a representative mesogen, i.e. T10, high-resolution solid-state (13)C NMR investigations are carried out in all the phases, viz. nematic, smectic A, smectic C and smectic B phases. The orientational order parameters calculated from (13)C-(1)H dipolar couplings from 2D SAMPI-4 experiments are found to be 0.44, 0.67, 0.73 and 0.79 in nematic, smectic A, smectic C and smectic B mesophases for the center phenyl ring respectively. Remarkably, the thiophene order parameter in all mesophases is found to be higher than that of phenyl rings and is explained by considering the molecular shape, which has a terminal bend. Further, the mesogens are found to be photoemissive in chloroform solution with an emission band at ∼410 nm.

State Regulatory Enforcement and Nursing Home Termination from the Medicare and Medicaid Programs

PubMed Central

Li, Yue; Harrington, Charlene; Spector, William D; Mukamel, Dana B

2010-01-01

Objectives Nursing homes certified by the Medicare and/or Medicaid program are subject to federally mandated and state-enforced quality and safety standards. We examined the relationship between state quality enforcement and nursing home terminations from the two programs. Study Design Using data from a survey of state licensure and certification agencies and other secondary databases, we performed bivariate and multivariate analyses on the strength of state quality regulation in 2005, and nursing home voluntary terminations (decisions made by the facility) or involuntary terminations (imposed by the state) in 2006–2007. Principal Findings Involuntary terminations were rarely imposed by state regulators, while voluntary terminations were relatively more common (2.16 percent in 2006–2007) and varied considerably across states. After controlling for facility, market, and state covariates, nursing homes in states implementing stronger quality enforcement were more likely to voluntarily terminate from the Medicare and Medicaid programs (odds ratio=1.53, p=.018). Conclusions Although involuntary nursing home terminations occurred rarely in most states, nursing homes in states with stronger quality regulations tend to voluntarily exit the publicly financed market. Because of the consequences of voluntary terminations on patient care and access, state regulators need to consider the effects of increased enforcement on both enhanced quality and the costs of termination. PMID:20819106

Targeted mass spectrometric analysis of N-terminally truncated isoforms generated via alternative translation initiation.

PubMed

Kobayashi, Ryuji; Patenia, Rebecca; Ashizawa, Satoshi; Vykoukal, Jody

2009-07-21

Alternative translation initiation is a mechanism whereby functionally altered proteins are produced from a single mRNA. Internal initiation of translation generates N-terminally truncated protein isoforms, but such isoforms observed in immunoblot analysis are often overlooked or dismissed as degradation products. We identified an N-terminally truncated isoform of human Dok-1 with N-terminal acetylation as seen in the wild-type. This Dok-1 isoform exhibited distinct perinuclear localization whereas the wild-type protein was distributed throughout the cytoplasm. Targeted analysis of blocked N-terminal peptides provides rapid identification of protein isoforms and could be widely applied for the general evaluation of perplexing immunoblot bands.

Commercial applications of the ACTS mobile terminal millimeter-wave antennas

NASA Technical Reports Server (NTRS)

Densmore, Arthur C.; Crist, Rick A.; Jamnejad, Vahraz; Tulintseff, Ann N.

1991-01-01

NASA's Jet Propulsion Laboratory is currently developing the Advanced Communications Technology Satellite (ACTS) Mobile Terminal (AMT), which will provide voice, data, and video communications to and from a vehicle (van, truck, or car) via NASA's geostationary ACTS satellite using the K- and K(sub a)-band frequency bands. The AMT is already planned to demonstrate a variety of communications from within the mobile vehicular environment, and within this paper a summary of foreseen commercial application opportunities is given. A critical component of the AMT is its antenna system, which must establish and maintain the basic RF link with the satellite. Two versions of the antenna are under development, each incorporating different technologies and offering different commercial applications.

Long-range wireless mesh network for weather monitoring in unfriendly geographic conditions.

PubMed

Toledano-Ayala, Manuel; Herrera-Ruiz, Gilberto; Soto-Zarazúa, Genaro M; Rivas-Araiza, Edgar A; Bazán Trujillo, Rey D; Porrás-Trejo, Rafael E

2011-01-01

In this paper a long-range wireless mesh network system is presented. It consists of three main parts: Remote Terminal Units (RTUs), Base Terminal Units (BTUs) and a Central Server (CS). The RTUs share a wireless network transmitting in the industrial, scientific and medical applications ISM band, which reaches up to 64 Km in a single point-to-point communication. A BTU controls the traffic within the network and has as its main task interconnecting it to a Ku-band satellite link using an embedded microcontroller-based gateway. Collected data is stored in a CS and presented to the final user in a numerical and a graphical form in a web portal.

Ka-Band Propagation Studies using the ACTS Propagation Terminal and the CSU-CHILL Multiparameter Radar

NASA Technical Reports Server (NTRS)

Bringi, V. N.; Beaver, John

1996-01-01

One of the first experimental communications satellites using Ka-band technology is the NASA Advanced Communications Technology Satellite (ACTS). In September 1993, ACTS was deployed into a geostationary orbit near 100 degrees W longitude by the space shuttle Discovery. The ACTS system supports both communication and propagation experiments at the 20/30 GHz frequency bands. The propagation experiment involves multi-year attenuation measurements along the satellite-Earth slant path.

Two-iron rubredoxin of Pseudomonas oleovorans: production, stability and characterization of the individual iron-binding domains by optical, CD and NMR spectroscopies.

PubMed

Perry, A; Lian, L Y; Scrutton, N S

2001-02-15

A minigene encoding the C-terminal domain of the 2Fe rubredoxin of Pseudomonas oleovorans was created from the parental alk G gene contained in the expression plasmid pKK223-3. The vector directed the high-level production of the C-terminal domain of this rubredoxin; a simple procedure was used to purify the recombinant domain in the 1Fe form. The 1Fe form of the C-terminal domain was readily converted into the apoprotein and cadmium forms after precipitation with trichloroacetic acid and resolubilization in the presence or absence of cadmium chloride respectively. In steady-state assays, the recombinant 1Fe C-terminal domain is redox-active and able to transfer electrons from reduced rubredoxin reductase to cytochrome c. The absorption spectrum and dichroic features of the CD spectrum for the iron- and cadmium-substituted C-terminal domain are similar to those reported for the iron- and cadmium-substituted Desulfovibrio gigas rubredoxin [Henehen, Pountney, Zerbe and Vasak (1993) Protein Sci. 2, 1756-1764]. Difference absorption spectroscopy of the cadmium-substituted C-terminal domain revealed the presence of four Gaussian-resolved maxima at 202, 225, 240 and 276 nm; from Jørgensen's electronegativity theory, the 240 nm band is attributable to a CysS-Cd(II) charge-transfer excitation. Attempts to express the N-terminal domain of the 2Fe rubredoxin directly from a minigene were unsuccessful. However, the N-terminal domain was isolated through cleavage of an engineered 2Fe rubredoxin in which a factor Xa proteolysis site had been introduced into the putative interdomain linker. The N-terminal domain is characterized by absorption spectra typical of the 1Fe rubredoxins. The domain is folded as determined by CD and NMR spectroscopies and is redox-active. However, the N-terminal domain is less stable than the isolated C-terminal domain, a finding consistent with the known properties of the full-length 2Fe and cadmium-substituted Ps. oleovorans rubredoxin.

Transportable satellite voice terminals in Canada's north: Benefits from the users' perspectives

NASA Astrophysics Data System (ADS)

Sivertz, Christopher B.

Infosat Telecommunications has developed a series of Ku-band transportable terminals for toll-quality telecommunications applications. These terminals are designed to provide reliable telephone, Group III facsimile, and computer data to users needing communications on short notice. The terminals are capable of providing full duplex service interconnecting into the public switched network or operating as an off-premise extension of an office private branch exchange. The terminals use a 1.8 m antenna and can be deployed from the back of a pick-up truck, single axle trailer or surface-mounted metal base. They operate reliable in extreme conditions and are very satellite efficient. This paper describes the features and performance of these terminals. Highlights of a number of remote installations are also discussed.

Electronic structure and surface properties of MgB2(0001) upon oxygen adsorption

NASA Astrophysics Data System (ADS)

Kim, Chang-Eun; Ray, Keith G.; Bahr, David F.; Lordi, Vincenzo

2018-05-01

We use density-functional theory to investigate the bulk and surface properties of MgB2. The unique bonding structure of MgB2 is investigated by Bader's atoms-in-molecules, charge density difference, and occupancy projected band structure analyses. Oxygen adsorption on the charge-depleted surfaces of MgB2 is studied by a surface potential energy mapping method, reporting a complete map including low-symmetry binding sites. The B-terminated MgB2(0001) demonstrates reconstruction of the graphenelike B layer, and the reconstructed geometry exposes a threefold site of the subsurface Mg, making it accessible from the surface. Detailed reconstruction mechanisms are studied by simulated annealing method based on ab initio molecular dynamics and nudged elastic band calculations. The surface clustering of B atoms significantly modifies the B 2 p states to occupy low energy valence states. The present paper emphasizes that a thorough understanding of the surface phase may explain an apparent inconsistency in the experimental surface characterization of MgB2. Furthermore, these results suggest that the surface passivation can be an important technical challenge when it comes to development of a superconducting device using MgB2.

Synthesis and characterization of the ((CO)/sub 4/MoS/sub 2/MS/sub 2/)/sup 2 -/ and ((CO)/sub 4/MoS/sub 2/MS/sub 2/Mo(CO)/sub 4/)/sup 2 -/ ions (M = Mo, W): species containing group VI (6) metals in widely separated formal oxidation states

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

Rosenhein, L.D.; McDonald, J.W.

1987-10-07

Dinuclear and trinuclear sulfide-bridged complexes of the types (Et/sub 4/N)/sub 2/(MS/sub 4/(Mo(CO)/sub 4/)) and (Et/sub 4/N)/sub 2/(MS/sub 4/(Mo(CO)/sub 4/)/sub 2/) were prepared by the reaction of one or two equivalents of Mo(CO)/sub 4/(C/sub 7/H/sub 8/) (C/sub 7/H/sub 8/ = norbornadiene) with (Et/sub 4/N)/sub 2/(MS/sub 4/) (M = Mo, W) in methyl alcohol. Elemental analyses were consistent with the proposed formulae. Infrared spectra of all four compounds contain strong bands in the carbonyl region and low-energy bands characteristic of terminal and bridging M-S vibrations in linear, polynuclear, and sulfido-bridged species. Electrochemical experimental results support the hypothesis that the di- and trinuclearmore » species contain both M(IV) (M = Mo, W) and Mo(0) oxidation states in the same complex. 33 references, 2 tables.« less

On board processing for future satellite communications systems: Comparison of FDM, TDM and hybrid accessing schemes

NASA Technical Reports Server (NTRS)

Berk, G.; Jean, P. N.; Rotholz, E.

1982-01-01

Several satellite uplink and downlink accessing schemes for customer premises service are compared. Four conceptual system designs are presented: satellite-routed frequency division multiple access (FDMA), satellite-switched time division multiple access (TDMA), processor-routed TDMA, and frequency-routed TDMA, operating in the 30/20 GHz band. The designs are compared on the basis of estimated satellite weight, system capacity, power consumption, and cost. The systems are analyzed for fixed multibeam coverage of the continental United States. Analysis shows that the system capacity is limited by the available satellite resources and by the terminal size and cost.

Interfacial Effects on the Band Edges of Functionalized Si Surfaces in Liquid Water

DOE PAGES

Pham, Tuan Anh; Lee, Donghwa; Schwegler, Eric; ...

2014-11-17

By combining ab initio molecular dynamics simulations and many-body perturbation theory calculations of electronic energy levels, we determined the band edge positions of functionalized Si(111) surfaces in the presence of liquid water, with respect to vacuum and to water redox potentials. We considered surface terminations commonly used for Si photoelectrodes in water splitting experiments. We found that, when exposed to water, the semiconductor band edges were shifted by approximately 0.5 eV in the case of hydrophobic surfaces, irrespective of the termination. The effect of the liquid on band edge positions of hydrophilic surfaces was much more significant and determined bymore » a complex combination of structural and electronic effects. These include structural rearrangements of the semiconductor surfaces in the presence of water, changes in the orientation of interfacial water molecules with respect to the bulk liquid, and charge transfer at the interfaces, between the solid and the liquid. Our results showed that the use of many-body perturbation theory is key to obtain results in agreement with experiments; they also showed that the use of simple computational schemes that neglect the detailed microscopic structure of the solid–liquid interface may lead to substantial errors in predicting the alignment between the solid band edges and water redox potentials.« less

Tunneling magnetoresistance and electroresistance in Fe/PbTiO{sub 3}/Fe multiferroic tunnel junctions

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

Dai, Jian-Qing, E-mail: djqkust@sina.com

We perform first-principles electronic structure and spin-dependent transport calculations for a Fe/PbTiO{sub 3}/Fe multiferroic tunnel junction with asymmetric TiO{sub 2}- and PbO-terminated interfaces. We demonstrate that the interfacial electronic reconstruction driven by the in situ screening of ferroelectric polarization, in conjunction with the intricate complex band structure of barrier, play a decisive role in controlling the spin-dependent tunneling. Reversal of ferroelectric polarization results in a transition from insulating to half-metal-like conducting state for the interfacial Pb 6p{sub z} orbitals, which acts as an atomic-scale spin-valve by releasing the tunneling current in antiparallel magnetization configuration as the ferroelectric polarization pointing tomore » the PbO-terminated interface. This effect produces large change in tunneling conductance. Our results open an attractive avenue in designing multiferroic tunnel junctions with excellent performance by exploiting the interfacial electronic reconstruction originated from the in situ screening of ferroelectric polarization.« less

Graded junction termination extensions for electronic devices

NASA Technical Reports Server (NTRS)

Merrett, J. Neil (Inventor); Isaacs-Smith, Tamara (Inventor); Sheridan, David C. (Inventor); Williams, John R. (Inventor)

2006-01-01

A graded junction termination extension in a silicon carbide (SiC) semiconductor device and method of its fabrication using ion implementation techniques is provided for high power devices. The properties of silicon carbide (SiC) make this wide band gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc. These devices require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power handling capabilities. The graded junction termination extension disclosed is effective, self-aligned, and simplifies the implementation process.

Graded junction termination extensions for electronic devices

NASA Technical Reports Server (NTRS)

Merrett, J. Neil (Inventor); Isaacs-Smith, Tamara (Inventor); Sheridan, David C. (Inventor); Williams, John R. (Inventor)

2007-01-01

A graded junction termination extension in a silicon carbide (SiC) semiconductor device and method of its fabrication using ion implementation techniques is provided for high power devices. The properties of silicon carbide (SiC) make this wide band gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc. These devices require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power handling capabilities. The graded junction termination extension disclosed is effective, self-aligned, and simplifies the implementation process.

Concepts for 20/30 GHz satcom systems for direct-to-user applications

NASA Technical Reports Server (NTRS)

Jorasch, R.; Davies, R.; Baker, M.

1980-01-01

A baseline technique is described for implementing a direct-to-user (DTU) satcom communications system at 20/30 GHz transmission frequency. The purpose of this application is to utilize the high capacity frequency spectrum at K(A) band for communications among thousands of small terminals located at or close to a customer's facility. The baseline DTU system utilizes a TDMA method of communications with QPSK modulation. Twenty-five coverage beams from a geosynchronous orbit spacecraft provide full coverage of CONUS. Low cost terminals are limited to less than 4.5 meters diameter. The impact of rain attenuation on communications availability is examined. Other techniques including satellite switched antenna beams are outlined and critical K(A)-band technology developments are identified.

Structure, IR and Raman spectra of phosphotrihydrazide studied by DFT

NASA Astrophysics Data System (ADS)

Furer, V. L.; Vandyukov, A. E.; Majoral, J. P.; Caminade, A. M.; Kovalenko, V. I.

2016-09-01

The FTIR and FT Raman measurements of the phosphotrihydrazide (S)P[N(Me)-NH2]3 have been performed. This compound is a zero generation dendrimer G0 with terminal amine groups. Structural optimization and normal mode analysis were obtained for G0 by the density functional theory (DFT). Optimized geometric bond length and angles obtained by DFT show good agreement with experiment. The amine terminal groups are characterized by the well-defined bands at 3321, 3238, 1614 cm- 1 in the experimental IR spectrum and by bands at 3327, 3241 cm- 1 in the Raman spectrum of G0. The experimental frequencies of asymmetric and symmetric NH2 stretching vibrations of amine group are lower than theoretical values due to intramolecular Nsbnd H ⋯ S hydrogen bond. This hydrogen bond is also responsible for higher experimental infrared intensity of these bands as compared with theoretical values. Relying on DFT calculations a complete vibrational assignment is proposed for the studied dendrimer.

Realization of single terminated surface of perovskite oxide single crystals and their band profile: (LaAlO3)0.3(Sr2AlTaO6)0.7, SrTiO3 and KTaO3 case study

NASA Astrophysics Data System (ADS)

Tomar, Ruchi; Wadehra, Neha; Budhiraja, Vaishali; Prakash, Bhanu; Chakraverty, S.

2018-01-01

To characterize the physical properties of thin films without ambiguity and design interface with new functionalities, it is essential to have detailed knowledge of physical properties and appropriate estimation of the band profile of perovskite oxide substrates. We have developed and demonstrated a chemical free unified framework to realize single terminated surface of KTaO3, (LaAlO3)0.3 (Sr2AlTaO6)0.7 and SrTiO3 (001) oriented single crystals. The electronic band line-up of these single crystal substrates, using a combination of optical spectroscopy and Kelvin Probe Force Microscopy, has been constructed. A polar-polar interface of KTaO3 and LaBO3 (B-Transition metal ion) before and after the possible surface/electronic reconstruction has also been schematically presented.

AMT experiment results

NASA Technical Reports Server (NTRS)

Abbe, Brian S.; Pinck, Deborah S.

1995-01-01

The Advanced Communications Technology Satellite (ACTS) Mobile Terminal (AMT) experiments have provided a terminal technology testbed for the evaluation of K- and Ka-band mobile satellite communications (satcom). Such a system could prove to be highly beneficial for many different commercial and government mobile satcom users. Combining ACTS' highly concentrated spotbeams with the smaller, higher-gain Ka-band antenna technology, results in a system design that can support a much higher throughput capacity than today's commercial configurations. To date, experiments in such diverse areas as emergency medical applications, enhanced Personal Communication Services (PCS), disaster recovery assistance, military applications, and general voice and data services have already been evaluated. Other applications that will be evaluated over the next year include telemedicine, ISDN, and television network return feed. Baseline AMT performance results will be presented, including Bit Error Rate (BER) curves and mobile propagation data characterizing the K- and Ka-band mobile satcom channel. In addition, observations from many of the application-specific experiments will also be provided.

Photonic and phononic surface and edge modes in three-dimensional phoxonic crystals

NASA Astrophysics Data System (ADS)

Ma, Tian-Xue; Wang, Yue-Sheng; Zhang, Chuanzeng

2018-04-01

We investigate the photonic and phononic surface and edge modes in finite-size three-dimensional phoxonic crystals. By appropriately terminating the phoxonic crystals, the photons and phonons can be simultaneously guided at the two-dimensional surface and/or the one-dimensional edge of the terminated crystals. The Bloch surface and edge modes show that the electromagnetic and acoustic waves are highly localized near the surface and edge, respectively. The surface and edge geometries play important roles in tailoring the dispersion relations of the surface and edge modes, and dual band gaps for the surface or edge modes can be simultaneously achieved by changing the geometrical configurations. Furthermore, as the band gaps for the bulk modes are the essential prerequisites for the realization of dual surface and edge modes, the photonic and phononic bulk-mode band gap properties of three different types of phoxonic crystals with six-connected networks are revealed. It is found that the geometrical characteristic of the crystals with six-connected networks leads to dual large bulk-mode band gaps. Compared with the conventional bulk modes, the surface and edge modes provide a new approach for the photon and phonon manipulation and show great potential for phoxonic crystal devices and optomechanics.

Propagation-related AMT design aspects and supporting experiments

NASA Technical Reports Server (NTRS)

Dessouky, Khaled; Estabrook, Polly

1991-01-01

The ACTS Mobile Terminal (AMT) is presently being developed with the goal of significantly extending commercial satellite applications and their user base. A thorough knowledge of the Ka-band channel characteristics is essential to the proper design of a commercially viable system that efficiently utilizes the valuable resources. To date, only limited tests have been performed to characterize the Ka-band channel, and they have focused on the needs of fixed terminals. As part of the value of the AMT as a Ka-band test bed is its function as a vehicle through which tests specifically applicable to the mobile satellite communications can be performed. The exact propagation environment with the proper set of elevation angles, vehicle antenna gains and patterns, roadside shadowing, rain, and Doppler is encountered. The ability to measure all of the above, as well as correlate their effects with observed communication system performance, creates an invaluable opportunity to understand in depth Ka-band's potential in supporting mobile and personal communications. This paper discusses the propagation information required for system design, the setup with ACTS that will enable obtaining this information, and finally the types of experiments to be performed and data to be gathered by the AMT to meet this objective.

Alternative beam configuration for a Canadian Ka-band satellite system

NASA Technical Reports Server (NTRS)

Hindson, Daniel J.; Caron, Mario

1995-01-01

Satellite systems operating in the Ka-band have been proposed to offer wide band personal communications services to fixed earth terminals employing small aperture antennas as well as to mobile terminals. This requirement to service a small aperture antenna leads to a satellite system utilizing small spot beams. The traditional approach is to cover the service area with uniform spot beams which have been sized to provide a given grade of service at the worst location over the service area and to place them in a honeycomb pattern. In the lower frequency bands this approach leads to a fairly uniform grade of service over the service area due to the minimal effects of rain on the signals. At Ka-band, however, the effects of rain are quite significant. Using this approach over a large service area (e.g. Canada) where the geographic distribution of rain impairment varies significantly yields an inefficient use of satellite resources to provide a uniform grade of service. An alternative approach is to cover the service area using more than one spot beam size in effect linking the spot beam size to the severity of the rain effects in a region. This paper demonstrates how for a Canadian Ka-band satellite system, that the use of two spot beam sizes can provide a more uniform grade of service across the country as well as reduce the satellite payload complexity over a design utilizing a single spot beam size.

X-Band, 17-Watt Solid-State Power Amplifier

NASA Technical Reports Server (NTRS)

Mittskus, Anthony; Stone, Ernest; Boger, William; Burgess, David; Honda, Richard; Nuckolls, Carl

2005-01-01

An advanced solid-state power amplifier that can generate an output power of as much as 17 W at a design operating frequency of 8.4 GHz has been designed and constructed as a smaller, lighter, less expensive alternative to traveling-wave-tube X-band amplifiers and to prior solid-state X-band power amplifiers of equivalent output power. This amplifier comprises a monolithic microwave integrated circuit (MMIC) amplifier module and a power-converter module integrated into a compact package (see Figure 1). The amplifier module contains an input variable-gain amplifier (VGA), an intermediate driver stage, a final power stage, and input and output power monitors (see Figure 2). The VGA and the driver amplifier are 0.5-m GaAs-based metal semiconductor field-effect transistors (MESFETs). The final power stage contains four parallel high-efficiency, GaAs-based pseudomorphic high-electron-mobility transistors (PHEMTs). The gain of the VGA is voltage-variable over a range of 10 to 24 dB. To provide for temperature compensation of the overall amplifier gain, the gain-control voltage is generated by an operational-amplifier circuit that includes a resistor/thermistor temperature-sensing network. The driver amplifier provides a gain of 14 dB to an output power of 27 dBm to drive the four parallel output PHEMTs, each of which is nominally capable of putting out as much as 5 W. The driver output is sent to the input terminals of the four parallel PHEMTs through microstrip power dividers; the outputs of these PHEMTs are combined by microstrip power combiners (which are similar to the microstrip power dividers) to obtain the final output power of 17 W.

Laparoscopic management of terminal ileal volvulus caused by Meckel's diverticulum.

PubMed

Xanthis, A; Hakeem, A; Safranek, P

2015-04-01

Complications from a Meckel's diverticulum include diverticulitis, bleeding, intussusception, bowel obstruction, a volvulus, a vesicodiverticular fistula, perforation or very rarely as a tumour. We report a case where a Meckel's diverticulum presented with a terminal ileal volvulus in a 32-year-old man without the presence of a typical vitelline band or axial torsion of the diverticulum causing the volvulus. It was successfully managed laparoscopically.

An empirical basis for Mach bands

PubMed Central

Lotto, R. Beau; Williams, S. Mark; Purves, Dale

1999-01-01

Mach bands, the illusory brightness maxima and minima perceived at the initiation and termination of luminance gradients, respectively, are generally considered a direct perceptual manifestation of lateral inhibitory interactions among retinal or other lower order visual neurons. Here we examine an alternative explanation, namely that Mach bands arise as a consequence of real-world luminance gradients. In this first of two companion papers, we analyze the natural sources of luminance gradients, demonstrating that real-world gradients arising from curved surfaces are ordinarily adorned by photometric highlights and lowlights in the position of the illusory bands. The prevalence of such gradients provides an empirical basis for the generation of this perceptual phenomenon. PMID:10220450

Binding of transducin and transducin-derived peptides to rhodopsin studies by attenuated total reflection-Fourier transform infrared difference spectroscopy.

PubMed Central

Fahmy, K

1998-01-01

Fourier transform infrared difference spectroscopy combined with the attenuated total reflection technique allows the monitoring of the association of transducin with bovine photoreceptor membranes in the dark. Illumination causes infrared absorption changes linked to formation of the light-activated rhodopsin-transducin complex. In addition to the spectral changes normally associated with meta II formation, prominent absorption increases occur at 1735 cm-1, 1640 cm-1, 1550 cm-1, and 1517 cm-1. The D2O sensitivity of the broad carbonyl stretching band around 1735 cm-1 indicates that a carboxylic acid group becomes protonated upon formation of the activated complex. Reconstitution of rhodopsin into phosphatidylcholine vesicles has little influence on the spectral properties of the rhodopsin-transducin complex, whereas pH affects the intensity of the carbonyl stretching band. AC-terminal peptide comprising amino acids 340-350 of the transducin alpha-subunit reproduces the frequencies and isotope sensitivities of several of the transducin-induced bands between 1500 and 1800 cm-1, whereas an N-terminal peptide (aa 8-23) does not. Therefore, the transducin-induced absorption changes can be ascribed mainly to an interaction between the transducin-alpha C-terminus and rhodopsin. The 1735 cm-1 vibration is also seen in the complex with C-terminal peptides devoid of free carboxylic acid groups, indicating that the corresponding carbonyl group is located on rhodopsin. PMID:9726932

Terminal NiII-OH/-OH2 complexes in trigonal bipyramidal geometries derived from H2O.

PubMed

Lau, Nathanael; Sano, Yohei; Ziller, Joseph W; Borovik, A S

2017-03-29

The preparation and characterization of two Ni II complexes are described, a terminal Ni II -OH complex with the tripodal ligand tris[(N)-tertbutylureaylato)-N-ethyl)]aminato ([H 3 buea] 3- ) and a terminal Ni II -OH 2 complex with the tripodal ligand N , N ', N ″-[2,2',2″-nitrilotris(ethane-2,1-diyl)]tris(2,4,6-trimethylbenzenesulfonamido) ([MST] 3- ). For both complexes, the source of the -OH and -OH 2 ligand is water. The salts K 2 [Ni II H 3 buea(OH)] and NMe 4 [Ni II MST(OH 2 )] were characterized using perpendicular-mode X-band electronic paramagnetic resonance, Fourier transform infrared, UV-visible spectroscopies, and its electrochemical properties were evaluated using cyclic voltammetry. The solid state structures of these complexes determined by X-ray diffraction methods reveal that they adopt a distorted trigonal bipyramidal geometry, an unusual structure for 5-coordinate Ni II complexes. Moreover, the Ni II -OH and Ni II -OH 2 units form intramolecular hydrogen bonding networks with the [H 3 buea] 3- and [MST] 3- ligands. The oxidation chemistry of these complexes was explored by treating the high-spin Ni II compounds with one-electron oxidants. Species were formed with S = 1/2 spin ground states that are consistent with formation of monomeric Ni III species. While the formation of Ni III -OH complexes cannot be ruled out, the lack of observable O-H vibrations from the putative Ni-OH units suggest the possibility that other high valent Ni species are formed.

W-band six-port network analyzer for two-port characterization of millimeter wave transistors

NASA Technical Reports Server (NTRS)

Moeller, Karl J.; Schaffner, James H.; Fetterman, Harold R.

1989-01-01

A W-band (75-100 GHz) six-port junction network analyzer was constructed from commercially available descrete waveguide components and was used for the direct two-port S-parameter measurement of active three-terminal devices. A comparison between the six-port and a down-converter-type frequency extender for a conventional network analyzer revealed the superior performance of the six-port. The application of the six-port to characterize a 0.1-micron gate-length HEMT at W-band is described, and representative results are presented.

Beamed microwave power transmitting and receiving subsystems radiation characteristics

NASA Technical Reports Server (NTRS)

Dickinson, R. M.

1980-01-01

Measured characteristics of the spectrum of typical converters and the distribution of radiated Radio Frequency (RF) energy from the terminals (transmitting antenna and rectenna) of a beamed microwave power subsystem are presented for small transmitting and receiving S-band (2.45 GHz) subarrays. Noise and harmonic levels of tube and solid-state RF power amplifiers are shown. The RF patterns and envelope of a 64 element slotted waveguide antenna are given for the fundamental frequency and harmonics through the fifth. Reflected fundamental and harmonic patterns through the fourth for a 42 element rectenna subarray are presented for various dc load and illumination conditions. Bandwidth measurements for the waveguide antenna and rectenna are shown.

Symmetrical metallic and magnetic edge states of nanoribbon from semiconductive monolayer PtS2

NASA Astrophysics Data System (ADS)

Liu, Shan; Zhu, Heyu; Liu, Ziran; Zhou, Guanghui

2018-03-01

Transition metal dichalcogenides (TMD) MoS2 or graphene could be designed to metallic nanoribbons, which always have only one edge show metallic properties due to symmetric protection. In present work, a nanoribbon with two parallel metallic and magnetic edges was designed from a noble TMD PtS2 by employing first-principles calculations based on density functional theory (DFT). Edge energy, bonding charge density, band structure, density of states (DOS) and simulated scanning tunneling microscopy (STM) of four possible edge states of monolayer semiconductive PtS2 were systematically studied. Detailed calculations show that only Pt-terminated edge state among four edge states was relatively stable, metallic and magnetic. Those metallic and magnetic properties mainly contributed from 5d orbits of Pt atoms located at edges. What's more, two of those central symmetric edges coexist in one zigzag nanoribbon, which providing two atomic metallic wires thus may have promising application for the realization of quantum effects, such as Aharanov-Bohm effect and atomic power transmission lines in single nanoribbon.

Band positions of Rutile surfaces and the possibility of water splitting

NASA Astrophysics Data System (ADS)

Esch, Tobit R.; Bredow, Thomas

2017-11-01

It is well known that both the band gap and the band edge positions of oxide semiconductors are important for the photocatalytic water splitting. In this study, we show that different surface terminations of the same crystalline solid lead to considerable variations of the band gaps and band edges. As an example, we investigate the low-index surfaces of rutile TiO2. A series of hybrid methods based on the PBE exchange-correlation functional, PBE0, HSE06 and HISS, are employed to study the effect of long-range exchange on the electronic properties. In aqueous solution, the oxide particles employed in photocatalysis are fully covered with water molecules. We therefore study the influence of molecularly and dissociatively adsorbed water on the band positions. It is found that water adsorption leads to significant shifts of the band edge positions due to changes of the electrostatic potential at the surface atom positions.

Surface electrochemistry of CO on reconstructed gold single crystal surfaces studied by infrared reflection absorption spectroscopy and rotating disk electrode.

PubMed

Blizanac, Berislav B; Arenz, Matthias; Ross, Philip N; Marković, Nenad M

2004-08-18

The electrooxidation of CO has been studied on reconstructed gold single-crystal surfaces by a combination of electrochemical (EC) and infrared reflection absorption spectroscopy (IRAS) measurements. Emphasis is placed on relating the vibrational properties of the CO adlayer to the voltammetric and other macroscopic electrochemical responses, including rotating disk electrode measurements of the catalytic activity. The IRAS data show that the C-O stretching frequencies are strongly dependent on the surface orientation and can be observed in the range 1940-1990 cm(-1) for the 3-fold bridging, 2005-2070 cm(-1) for the 2-fold bridging, and 2115-2140 for the terminal position. The most complex CO spectra are found for the Au(110)-(1 x 2) surface, i.e., a band near 1965 cm(-1), with the second, weaker band shifted positively by about 45 cm(-1) and, finally, a weak band near 2115 cm(-1). While the C-O stretching frequencies for a CO adlayer adsorbed on Au(111)-(1 x 23) show nu(CO) bands at 2029-2069 cm(-1) and at 1944-1986 cm(-1), on the Au(100)-"hex" surface a single CO band is observed at 2004-2029 cm(-1). In the "argon-purged" solution, the terminal nu(CO) band on Au(110)-(1 x 2) and the 3-fold bridging band on the Au(111)-(1 x 23) disappear entirely. The IRAS/EC data show that the kinetics of CO oxidation are structure sensitive; i.e., the onset of CO oxidation increases in the order Au(110)-(1 x 2) > or = Au(100)-"hex" > Au(111)-(1 x 23). Possible explanations for the structure sensitivity are discussed.

Study of LEO-SAT microwave link for broad-band mobile satellite communication system

NASA Technical Reports Server (NTRS)

Fujise, Masayuki; Chujo, Wataru; Chiba, Isamu; Furuhama, Yoji; Kawabata, Kazuaki; Konishi, Yoshihiko

1993-01-01

In the field of mobile satellite communications, a system based on low-earth-orbit satellites (LEO-SAT's) such as the Iridium system has been proposed. The LEO-SAT system is able to offer mobile telecommunication services in high-latitude areas. Rain degradation, fading and shadowing are also expected to be decreased when the system is operated at a high elevation angle. Furthermore, the propagation delay generated in the LEO-SAT system is less pronounced than that in the geostationary orbit satellite (GEO-SAT) system and, in voice services, the effect of the delay is almost negligible. We proposed a concept of a broad-band mobile satellite communication system with LEO-SAT's and Optical ISL. In that system, a fixed L-band (1.6/1.5 GHz) multibeam is used to offer narrow band service to the mobile terminals in the entire area covered by a LEO-SAT and steerable Ka-band (30/20 GHz) spot beams are used for the wide band service. In this paper, we present results of a study of LEO-SAT microwave link between a satellite and a mobile terminal for a broad-band mobile satellite communication system. First, the results of link budget calculations are presented and the antennas mounted on satellites are shown. For a future mobile antenna technology, we also show digital beamforming (DBF) techniques. DBF, together with modulation and/or demodulation, is becoming a key technique for mobile antennas with advanced functions such as antenna pattern calibration, correction, and radio interference suppression. In this paper, efficient DBF techniques for transmitting and receiving are presented. Furthermore, an adaptive array antenna system suitable for this LEO-SAT is presented.

Low-Cost Tracking Ground Terminal Designed to Use Cryogenically Cooled Electronics

NASA Technical Reports Server (NTRS)

Wald, Lawrence W.; Romanofsky, Robert R.; Warner, Joseph D.

2000-01-01

A computer-controlled, tracking ground terminal will be assembled at the NASA Glenn Research Center at Lewis Field to receive signals transmitted by the Glenn's Direct Data Distribution (D3) payload planned for a shuttle flight in low Earth orbit. The terminal will enable direct data reception of up to two 622-megabits-per-second (Mbps) beams from the space-based, K-band (19.05-GHz) transmitting array at an end-user bit error rate of up to 10(exp -12). The ground terminal will include a 0.9-m-diameter receive-only Cassegrain reflector antenna with a corrugated feed horn incorporating a dual circularly polarized, K-band feed assembly mounted on a multiaxis, gimbaled tracking pedestal as well as electronics to receive the downlink signals. The tracking system will acquire and automatically track the shuttle through the sky for all elevations greater than 20 above the horizon. The receiving electronics for the ground terminal consist of a six-pole microstrip bandpass filter, a three-stage monolithic microwave integrated circuit (MMIC) amplifier, and a Stirling cycle cryocooler (1 W at 80 K). The Sterling cycle cryocooler cools the front end of the receiver, also known as the low-noise amplifier (LNA), to about 77 K. Cryocooling the LNA significantly increases receiver performance, which is necessary so that it can use the antenna, which has an aperture of only 0.9 m. The following drawing illustrates the cryoterminal.

Rapid change of chromomeric and pairing patterns of polytene chromosome tips in D. melanogaster: migration of polytene-nonpolytene transition zone?

PubMed

Roberts, P A

1979-07-01

The high variability of chromomeric patterns in near-terminal regions of polytene chromosome arms has been explored in a number of races, strains and hybrids of Drosophila melanogaster. Traditional explanations for tip differences between strains (differential compaction of chromatin, somatic or germinal deletion) are examined and, in the light of the reported observations, rejected. The range of polytene tip variability and rates of change in wild races are greater than has been supposed: strains formerly considered to be terminally deleted appear to gain terminal bands; others, formerly considered normal, appear to have lost them. Strains with high cell-to-cell tip variability are also described. Cell-to-cell variations, as well as much of the observed rapid changes in tip appearance, are probably due to heritable differences in the location of an abrupt transition zone between polytene and nonpolytene chromatin. A quantitative relationship between the amount of certain subterminal bands present and the frequency of tip association of nonhomologous chromosomes is shown and its possible significance for chromosome is shown and its possible for chromosome pairing discussed.

Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study.

PubMed

Hricovíni, Michal; Mazúr, Milan; Sîrbu, Angela; Palamarciuc, Oleg; Arion, Vladimir B; Brezová, Vlasta

2018-03-21

X- and Q-band electron paramagnetic resonance (EPR) spectroscopy was used to characterize polycrystalline Cu(II) complexes that contained sodium 5-sulfonate salicylaldehyde thiosemicarbazones possessing a hydrogen, methyl, ethyl, or phenyl substituent at the terminal nitrogen. The ability of thiosemicarbazone proligands to generate superoxide radical anions and hydroxyl radicals upon their exposure to UVA irradiation in aerated aqueous solutions was evidenced by the EPR spin trapping technique. The UVA irradiation of proligands in neutral or alkaline solutions and dimethylsulfoxide (DMSO) caused a significant decrease in the absorption bands of aldimine and phenolic chromophores. Mixing of proligand solutions with the equimolar amount of copper(II) ions resulted in the formation of 1:1 Cu(II)-to-ligand complex, with the EPR and UV-Vis spectra fully compatible with those obtained for the dissolved Cu(II) thiosemicarbazone complexes. The formation of the complexes fully inhibited the photoinduced generation of reactive oxygen species, and only subtle changes were found in the electronic absorption spectra of the complexes in aqueous and DMSO solutions upon UVA steady-state irradiation. The dark redox activity of copper(II) complexes and proligand/Cu(II) aqueous solutions towards hydrogen peroxide which resulted in the generation of hydroxyl radicals, was confirmed by spin trapping experiments.

Expression, purification, and functional analysis of the C-terminal domain of Herbaspirillum seropedicae NifA protein.

PubMed

Monteiro, Rose A; Souza, Emanuel M; Geoffrey Yates, M; Steffens, M Berenice R; Pedrosa, Fábio O; Chubatsu, Leda S

2003-02-01

The Herbaspirillum seropedicae NifA protein is responsible for nif gene expression. The C-terminal domain of the H. seropedicae NifA protein, fused to a His-Tag sequence (His-Tag-C-terminal), was over-expressed and purified by metal-affinity chromatography to yield a highly purified and active protein. Band-shift assays showed that the NifA His-Tag-C-terminal bound specifically to the H. seropedicae nifB promoter region in vitro. In vivo analysis showed that this protein inhibited the Central + C-terminal domains of NifA protein from activating the nifH promoter of K. pneumoniae in Escherichia coli, indicating that the protein must be bound to the NifA-binding site (UAS site) at the nifH promoter region to activate transcription. Copyright 2002 Elsevier Science (USA)

Self-Controlled Synthesis of Hyperbranched Poly(etherketone)s from A2 + B3 Approach in Poly(phosphoric acid)

DTIC Science & Technology

2009-01-01

aromatic keto -band arisen from carboxylic acids, which could be part of terminal groups of HPEKs, ranged from 1708 to 1719 cm1. The carbonyl bands from...1999, 143 , 1–34; (d) Inoue, K. Prog Polym Sci 2000, 25, 453–571; (e) Voit, B. J Polym Sci Part A: Polym Chem 2000, 36, 2505–2525; (f) Hult, A

Interaction of Huntingtin Exon-1 Peptides with Lipid-Based Micellar Nanoparticles Probed by Solution NMR and Q-Band Pulsed EPR.

PubMed

Ceccon, Alberto; Schmidt, Thomas; Tugarinov, Vitali; Kotler, Samuel A; Schwieters, Charles D; Clore, G Marius

2018-05-23

Lipid-based micellar nanoparticles promote aggregation of huntingtin exon-1 peptides. Here we characterize the interaction of two such peptides, htt NT Q  7 and htt NT Q  10 comprising the N-terminal amphiphilic domain of huntingtin followed by 7 and 10 glutamine repeats, respectively, with 8 nm lipid micelles using NMR chemical exchange saturation transfer (CEST), circular dichroism and pulsed Q-band EPR. Exchange between free and micelle-bound htt NT Q  n peptides occurs on the millisecond time scale with a K D ∼ 0.5-1 mM. Upon binding micelles, residues 1-15 adopt a helical conformation. Oxidation of Met 7 to a sulfoxide reduces the binding affinity for micelles ∼3-4-fold and increases the length of the helix by a further two residues. A structure of the bound monomer unit is calculated from the backbone chemical shifts of the micelle-bound state obtained from CEST. Pulsed Q-band EPR shows that a monomer-dimer equilibrium exists on the surface of the micelles and that the two helices of the dimer adopt a parallel orientation, thereby bringing two disordered polyQ tails into close proximity which may promote aggregation upon dissociation from the micelle surface.

Critical behavior of the extended Hubbard model with bond dimerization

NASA Astrophysics Data System (ADS)

Ejima, Satoshi; Lange, Florian; Essler, Fabian H. L.; Fehske, Holger

2018-05-01

Exploiting the matrix-product-state based density-matrix renormalization group (DMRG) technique we study the one-dimensional extended (U-V) Hubbard model with explicit bond dimerization in the half-filled band sector. In particular we investigate the nature of the quantum phase transition, taking place with growing ratio V / U between the symmetry-protected-topological and charge-density-wave insulating states. The (weak-coupling) critical line of continuous Ising transitions with central charge c = 1 / 2 terminates at a tricritical point belonging to the universality class of the dilute Ising model with c = 7 / 10 . We demonstrate that our DMRG data perfectly match with (tricritical) Ising exponents, e.g., for the order parameter β = 1 / 8 (1/24) and correlation length ν = 1 (5/9). Beyond the tricritical Ising point, in the strong-coupling regime, the quantum phase transition becomes first order.

Magnetic edge states in Aharonov-Bohm graphene quantum rings

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

Farghadan, R., E-mail: rfarghadan@kashanu.ac.ir; Heidari Semiromi, E.; Saffarzadeh, A.

2013-12-07

The effect of electron-electron interaction on the electronic structure of Aharonov-Bohm (AB) graphene quantum rings (GQRs) is explored theoretically using the single-band tight-binding Hamiltonian and the mean-field Hubbard model. The electronic states and magnetic properties of hexagonal, triangular, and circular GQRs with different sizes and zigzag edge terminations are studied. The results show that, although the AB oscillations in the all types of nanoring are affected by the interaction, the spin splitting in the AB oscillations strongly depends on the geometry and the size of graphene nanorings. We found that the total spin of hexagonal and circular rings is zeromore » and therefore, no spin splitting can be observed in the AB oscillations. However, the non-zero magnetization of the triangular rings breaks the degeneracy between spin-up and spin-down electrons, which produces spin-polarized AB oscillations.« less

The Anatomy of the Young Protostellar Outflow HH 211: Strong Evidence for CO v = 1-0 Fundamental Band Emission from Dense Gas in the Terminal Shock

NASA Astrophysics Data System (ADS)

Tappe, Achim; Forbrich, J.; Martín, S.; Lada, C. J.

2011-05-01

We present Spitzer Space Telescope 5-37 µm spectroscopic mapping observations toward the southeastern lobe of the young protostellar outflow HH 211 (part of IC 348 in Perseus, 260 pc). The terminal shock of the outflow shows a rich atomic and molecular spectrum with emission lines from OH, H2O, HCO+, CO2, H2, HD, [Fe II], [Si II], [Ne II], [S I], and [Cl I]. The spectrum also shows a rising continuum towards 5 µm, which we interpret as unresolved emission lines from highly excited rotational levels of the CO v=1-0 fundamental band. This interpretation is confirmed by a strong excess flux observed in the Spitzer IRAC 4-5 µm channel 2 image. We also observed the terminal outflow shock of this lobe with the Submillimeter Array (SMA) and detected pure rotational emission from CO 2-1, HCO+ 3-2, and HCN 3-2. The rotationally excited CO traces the collimated outflow and the terminal shock, whereas the vibrationally excited CO seen with Spitzer follows the continuation of the collimated outflow backbone in the terminal shock. The extremely high critical densities of the CO v=1-0 rovibrational lines indicate terminal shock jet densities larger than 107 cm-3. The unique combination of mid-infrared, submillimeter, and previous near-infrared observations allow us to gain detailed insights into the interaction of one of the youngest known protostellar outflows with its surrounding molecular cloud. Our results help to understand the nature of some of the so-called `green fuzzies’ (Extended Green Objects) identified by their Spitzer IRAC channel 2 excess and association with star-forming regions. They also provide a critical observational test to models of pulsed protostellar jets.

Current-voltage characteristics of molecular conductors: two versus three terminal

NASA Astrophysics Data System (ADS)

Damle, P.; Rakshit, T.; Paulsson, M.; Datta, S.

2002-09-01

This paper addresses the question of whether a ``rigid molecule'' (one which does not deform in an external field) used as the conducting channel in a standard three-terminal MOSFET configuration can offer any performance advantage relative to a standard silicon MOSFET. A self-consistent solution of coupled quantum transport and Poisson's equations shows that even for extremely small channel lengths (about 1 nm), a ``well-tempered'' molecular FET demands much the same electrostatic considerations as a ``well-tempered'' conventional MOSFET. In other words, we show that just as in a conventional MOSFET, the gate oxide thickness needs to be much smaller than the channel length (length of the molecule) for the gate control to be effective. Furthermore, we show that a rigid molecule with metallic source and drain contacts has a temperature independent subthreshold slope much larger than 60 mV/decade, because the metal-induced gap states in the channel prevent it from turning off abruptly. However, this disadvantage can be overcome by using semiconductor contacts because of their band-limited nature.

Direct evidence of the existence of Mn3+ ions in MnTiO3

NASA Astrophysics Data System (ADS)

Maurya, R. K.; Sharma, Priyamedha; Patel, Ashutosh; Bindu, R.

2017-08-01

We investigate the room temperature electronic properties of MnTiO3 synthesised by different preparation conditions. For this purpose, we prepared MnTiO3 under two different cooling rates, one is naturally cooled while the other is quenched in liq.nitrogen. The samples were studied using optical absorbance, photoemission spectroscopy and band structure calculations. We observe significant changes in the structural parameters as a result of quenching. Interestingly, in the parent compound, our combined core level, valence band and optical absorbance studies give evidence of the Mn existence in both 2+ and 3+ states. The fraction of Mn3+ ions has been found to increase on quenching MnTiO3 suggests an increase in oxygen non-stoichiometry. The increase in the fraction of the Mn3+ ions has been manifested a) as slight enhancement in the intensity of the optical absorbance in the visible region. There occurs persistent photo-resistance when the incident light is terminated after shining; b) in the behaviour of the features (close to Fermi level) in the valence band spectra. Hence, the combined analysis of the core level, valence band and optical absorbance spectra suggests that the charge carriers are hole like which further leads to the increase in the electrical conductivity of the quenched sample. The present results provide a recipe to tune the optical absorption in the visible range for its applications in optical sensors, solar cell, etc.

Analysis of novel sph (spherocytosis) alleles in mice reveals allele-specific loss of band 3 and adducin in α-spectrin–deficient red cells

PubMed Central

Robledo, Raymond F.; Lambert, Amy J.; Birkenmeier, Connie S.; Cirlan, Marius V.; Cirlan, Andreea Flavia M.; Campagna, Dean R.; Lux, Samuel E.

2010-01-01

Five spontaneous, allelic mutations in the α-spectrin gene, Spna1, have been identified in mice (spherocytosis [sph], sph1J, sph2J, sph2BC, sphDem). All cause severe hemolytic anemia. Here, analysis of 3 new alleles reveals previously unknown consequences of red blood cell (RBC) spectrin deficiency. In sph3J, a missense mutation (H2012Y) in repeat 19 introduces a cryptic splice site resulting in premature termination of translation. In sphIhj, a premature stop codon occurs (Q1853Stop) in repeat 18. Both mutations result in markedly reduced RBC membrane spectrin content, decreased band 3, and absent β-adducin. Reevaluation of available, previously described sph alleles reveals band 3 and adducin deficiency as well. In sph4J, a missense mutation occurs in the C-terminal EF hand domain (C2384Y). Notably, an equally severe hemolytic anemia occurs despite minimally decreased membrane spectrin with normal band 3 levels and present, although reduced, β-adducin. The severity of anemia in sph4J indicates that the highly conserved cysteine residue at the C-terminus of α-spectrin participates in interactions critical to membrane stability. The data reinforce the notion that a membrane bridge in addition to the classic protein 4.1-p55-glycophorin C linkage exists at the RBC junctional complex that involves interactions between spectrin, adducin, and band 3. PMID:20056793

Analysis of novel sph (spherocytosis) alleles in mice reveals allele-specific loss of band 3 and adducin in alpha-spectrin-deficient red cells.

PubMed

Robledo, Raymond F; Lambert, Amy J; Birkenmeier, Connie S; Cirlan, Marius V; Cirlan, Andreea Flavia M; Campagna, Dean R; Lux, Samuel E; Peters, Luanne L

2010-03-04

Five spontaneous, allelic mutations in the alpha-spectrin gene, Spna1, have been identified in mice (spherocytosis [sph], sph(1J), sph(2J), sph(2BC), sph(Dem)). All cause severe hemolytic anemia. Here, analysis of 3 new alleles reveals previously unknown consequences of red blood cell (RBC) spectrin deficiency. In sph(3J), a missense mutation (H2012Y) in repeat 19 introduces a cryptic splice site resulting in premature termination of translation. In sph(Ihj), a premature stop codon occurs (Q1853Stop) in repeat 18. Both mutations result in markedly reduced RBC membrane spectrin content, decreased band 3, and absent beta-adducin. Reevaluation of available, previously described sph alleles reveals band 3 and adducin deficiency as well. In sph(4J), a missense mutation occurs in the C-terminal EF hand domain (C2384Y). Notably, an equally severe hemolytic anemia occurs despite minimally decreased membrane spectrin with normal band 3 levels and present, although reduced, beta-adducin. The severity of anemia in sph(4J) indicates that the highly conserved cysteine residue at the C-terminus of alpha-spectrin participates in interactions critical to membrane stability. The data reinforce the notion that a membrane bridge in addition to the classic protein 4.1-p55-glycophorin C linkage exists at the RBC junctional complex that involves interactions between spectrin, adducin, and band 3.

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.

Advanced communication satellites worldwide - Satellites of opportunity for the ACTS mobile terminal

NASA Technical Reports Server (NTRS)

Girardey, Catherine C.

1993-01-01

Space agencies worldwide are involved in advanced satellite communication systems. This paper presents an overview of these satellites and related technologies in the U.S., Europe, and Japan. They are geostationary satellites using high frequency bands such as K/Ka (20/30 GHz) and O-band (millimeter wave), as well as optical frequencies. The similarity of these programs demonstrate a common interest to develop large capacity satellite communication systems, and shows that closer international cooperation could be set up. The ACTS Mobile Terminal (AMT) project discussed here is such an example. The AMT's compatibility with satellites other than ACTS has been studied, and a proposed common experiment is presented here. The Japanese Engineering Test Satellite ETS-VI has been identified as the best initial 'satellite of opportunity' for AMT in this preliminary assessment.

Spaceborne Ocean Intelligence Network: SOIN - Fiscal Year 08/09 Year-End Summary

DTIC Science & Technology

2009-09-01

de planification d’acquisition d’images de satellites commerciaux]) et le BT 4 (Entités océaniques d’après les images RSO). Le BT 2 est terminé à...colour assignment (r, g , or b). If a band is assigned to two colours, then two of r, g , or b are displayed next to the DN. If a band is assigned to...a DN is displayed for each r, g and b colour assignment, even if they are the same band. • Sigma-Nought Only works for RADARSAT-1 and RADARSAT-2

Analysis of the v2, v4 Infrared Hot Bands and v1 CARS Spectrum of 34S16O3

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

Barber, Jeffrey B.; Chrysostom, Engelene; Masiello, Tony

2003-04-01

High-resolution (0.0015 cm-1) infrared spectroscopy has been used to study the 34S16O3 IR-active hot bands originating from the v2 and v4 bending mode levels and terminating in the states 2v2 (l=0), v2+v4 (l=+1), and 2v4 (1=0,+2). The upper states are strongly coupled via Fermi resonance and indirect Coriolis interactions to the v1 symmetric stretching mode levels that are only directly accessible from the ground state via a Raman-active transition. A Coherent anti-Stokes Raman (CARS) spectrum of v1 for 34S16O3 is presented which is dramatically different from the corresponding one for 32S16O3. From the infrared transitions, accurate rovibrational constants are deducedmore » for all the mixed states, leading to deperturbed values for v1, a1B, and a1C of 1064.920(84), 0.000 834 5 (54), and 0.000 410(11) cm-1 respectively. The uncertainties in the last digits are shown in parentheses and represent two standard deviations. These parameters reproduce the unresolved Q-branch contour of the C ARS spectrum very well. Various other rotational and vibrational parameters have been determined, leading to values of Be= 0.349 760 6(33) cm-1 and re= 141.734 70(68) pm, values that are identical (within experimental error) to those found for 32S16O3.« less

Viral Lysogeny as a Potential Mechanism for Termination of a Red Tide Event

NASA Astrophysics Data System (ADS)

Martinez, S. B.; Kudela, R. M.; Broughton, J.

2014-12-01

Red tides are high-biomass blooms in the coastal ocean typically caused by dinoflagellates. While some red tides are harmful (via toxin production, high biomass, and oxygen depletion during decay), they also provide an important source of energy and carbon for other trophic levels. Red tides are often ephemeral, so while it is easy to identify one, what causes these events to terminate can vary. It has been hypothesized that viral lysis and parasitic infection may be important vectors of termination for these blooms. This study sought to compare the decay of one such bloom in Monterey Bay, California to in situ and mesocosm studies where bloom termination was due to viral lysis. To achieve this goal we used MODIS ocean color Level 2 data with spatial resolution of 1km; we identified and averaged RRS from 9 pixels within the northern "red tide incubator" region of Monterey Bay where a dinoflagellate bloom was identified. We applied the quasi-analytical algorithm (QAA) to derive the backscatter coefficient (bbp(λ)), absorption due to chlorophyll (aChl), and the gelbstoff absorption coefficient (ag). Separate equations were used to find the volume scattering function (β(ψ,λ) where ψ =140°) and the particle size distribution hyperbolic slope (ξ). A MODIS satellite time series of five days (during an eight-day period) confirmed optical changes similar to documented shifts in laboratory-controlled experiments examining viral lysis. As predicted from previous results, the decrease in chlorophyll - essentially the deterioration of the algal bloom - resulted in the anticipated decrease in bbp(λ) and VSF values as well as an increase in ξ. aChl and ag were also compared to the Morel 2009 band algorithm for Colored Dissolved Organic Matter (CDOM) and the OC3 band algorithm for chlorophyll concentration. Results indicate that the QAA retrievals cannot be statistically distinguished (using a paired t-test) from the Morel and OC3 band algorithms. Analyzing more bloom events would refine this method's results and would provide the potential to determine how a bloom is terminated - e.g. by viral lysis, parasitic infection, or nutrient depletion. This could in turn lead to a better understanding of bloom termination generally, perhaps leading to improved mitigation efforts for red tides and harmful algal blooms.

Land mobile satellite system requirements

NASA Astrophysics Data System (ADS)

Kiesling, J. D.

1983-05-01

A Land Mobile Satellite System (LMSS) provides voice, data and related communications services to moving vehicles and persons. Communications between the mobiles and satellite are in the 806-890 MHz band. The satellite translates these signals to a ""fixed services band'' such as 14/12 GHz band (Ku-band), and communicates in this band with fixed terminals called gateways. The gateways are located at convenient places such as telephone switches (which provide entry into the national telephone system), dispatcher headquarters, computer centers, etc. Communications are therefore principally mobile to fixed. A third communications link, also at Ku-band, is needed between the satellite and a single fixed ground station. This link provides satellite command, telemetry and ranging and also provides a network control function. The latter, through a common signalling system, receives requests and assigns channel slots, and otherwise controls, monitors and polices the network and collects billing information.

Land mobile satellite system requirements

NASA Technical Reports Server (NTRS)

Kiesling, J. D.

1983-01-01

A Land Mobile Satellite System (LMSS) provides voice, data and related communications services to moving vehicles and persons. Communications between the mobiles and satellite are in the 806-890 MHz band. The satellite translates these signals to a ""fixed services band'' such as 14/12 GHz band (Ku-band), and communicates in this band with fixed terminals called gateways. The gateways are located at convenient places such as telephone switches (which provide entry into the national telephone system), dispatcher headquarters, computer centers, etc. Communications are therefore principally mobile to fixed. A third communications link, also at Ku-band, is needed between the satellite and a single fixed ground station. This link provides satellite command, telemetry and ranging and also provides a network control function. The latter, through a common signalling system, receives requests and assigns channel slots, and otherwise controls, monitors and polices the network and collects billing information.

47 CFR 27.17 - Discontinuance of service in the 1695-1710 MHz, 1755-1780 MHz, 1915-1920 MHz, 1995-2000 MHz, 2000...

Code of Federal Regulations, 2014 CFR

2014-10-01

..., 1755-1780 MHz, 1915-1920 MHz, 1995-2000 MHz, 2000-2020 MHz, 2155-2180 MHz, and 2180-2200 MHz bands. 27... service in the 1695-1710 MHz, 1755-1780 MHz, 1915-1920 MHz, 1995-2000 MHz, 2000-2020 MHz, 2155-2180 MHz... MHz, 2000-2020 MHz, 2155-2180 MHz, and 2180-2200 MHz bands will automatically terminate, without...

Linear transmitter design for MSAT terminals

NASA Technical Reports Server (NTRS)

Wilkinson, Ross; Macleod, John; Beach, Mark; Bateman, Andrew

1990-01-01

One of the factors that will undoubtedly influence the choice of modulation format for mobile satellites, is the availability of cheap, power-efficient, linear amplifiers for mobile terminal equipment operating in the 1.5-1.7 GHz band. Transmitter linearity is not easily achieved at these frequencies, although high power (20W) class A/AB devices are becoming available. However, these components are expensive and require careful design to achieve a modest degree of linearity. In this paper an alternative approach to radio frequency (RF) power amplifier design for mobile satellite (MSAT) terminals using readily-available, power-efficient, and cheap class C devices in a feedback amplifier architecture is presented.

Interplay of Hofstadter and quantum Hall states in bilayer graphene

NASA Astrophysics Data System (ADS)

Spanton, Eric M.; Zibrov, Alexander A.; Zhou, Haoxin; Taniguchi, Takashi; Watanabe, Kenji; Young, Andrea

Electron interactions in ultraclean systems such as graphene lead to the fractional quantum Hall effect in an applied magnetic field. Long wavelength periodic potentials from a moiré pattern in aligned boron nitride-graphene heterostructures may compete with such interactions and favor spatially ordered states (e.g. Wigner crystals orcharge density waves). To investigate this competition, we studied the bulk phase diagram of asymmetrically moiré-coupled bilayer graphene via multi-terminal magnetocapacitance measurements at ultra-high magnetic fields. Two quantum numbers characterize energy gaps in this regime: t, which indexes the Bloch bands, and s, which indexes the Landau level. Similar to past experiments, we observe the conventional integer and fractional quantum Hall gaps (t = 0), integer Hofstadter gaps (integer s and integer t ≠ 0), and fractional Bloch states associated with an expanded superlattice unit cell (fractional s and integer t). Additionally, we find states with fractional values for both s and t. Measurement of the capacitance matrix shows that these states occur on the layer exposed to the strong periodic potential. We discuss the results in terms of possible fractional quantum hall states unique to periodically modulated systems.

Spectroscopic evidence for a type II Weyl semimetallic state in MoTe2

NASA Astrophysics Data System (ADS)

Huang, Lunan; McCormick, Timothy M.; Ochi, Masayuki; Zhao, Zhiying; Suzuki, Michi-To; Arita, Ryotaro; Wu, Yun; Mou, Daixiang; Cao, Huibo; Yan, Jiaqiang; Trivedi, Nandini; Kaminski, Adam

2016-11-01

In a type I Dirac or Weyl semimetal, the low-energy states are squeezed to a single point in momentum space when the chemical potential μ is tuned precisely to the Dirac/Weyl point. Recently, a type II Weyl semimetal was predicted to exist, where the Weyl states connect hole and electron bands, separated by an indirect gap. This leads to unusual energy states, where hole and electron pockets touch at the Weyl point. Here we present the discovery of a type II topological Weyl semimetal state in pure MoTe2, where two sets of Weyl points (, ) exist at the touching points of electron and hole pockets and are located at different binding energies above EF. Using angle-resolved photoemission spectroscopy, modelling, density functional theory and calculations of Berry curvature, we identify the Weyl points and demonstrate that they are connected by different sets of Fermi arcs for each of the two surface terminations. We also find new surface `track states' that form closed loops and are unique to type II Weyl semimetals. This material provides an exciting, new platform to study the properties of Weyl fermions.

Triple Play over Satellite, Ka-Band Making the Difference

NASA Astrophysics Data System (ADS)

Benoit, Guillaume; Fenech, Hector; Pezzana, Stefano

Over the last years a number of operators have been deploying satellite-based consumer internet access services to reduce the digital divide and capture the market of households not covered by ADSL, cable or wireless broadband. These operators are proposing a step change improvement in the economics of consumer service, with lower terminal costs, broadband access with monthly fees comparable to ADSL and an integrated technology simplifying the process of terminal installation, provisioning and management.

Polar Terminus

NASA Image and Video Library

2006-09-06

This MOC image shows the termination end of a group of layers in the north polar region of Mars, where they have been buried by younger, smoother-surfaced material. The layers are the banded features at the right/lower right

The effect of density-of-state tails on band-to-band tunneling: Theory and application to tunnel field effect transistors

NASA Astrophysics Data System (ADS)

Sant, S.; Schenk, A.

2017-10-01

It is demonstrated how band tail states in the semiconductor influence the performance of a Tunnel Field Effect Transistor (TFET). As a consequence of the smoothened density of states (DOS) around the band edges, the energetic overlap of conduction and valence band states occurs gradually at the onset of band-to-band tunneling (BTBT), thus degrading the sub-threshold swing (SS) of the TFET. The effect of the band tail states on the current-voltage characteristics is modelled quantum-mechanically based on the idea of zero-phonon trap-assisted tunneling between band and tail states. The latter are assumed to arise from a 3-dimensional pseudo-delta potential proposed by Vinogradov [1]. This model potential allows the derivation of analytical expressions for the generation rate covering the whole range from very strong to very weak localization of the tail states. Comparison with direct BTBT in the one-band effective mass approximation reveals the essential features of tail-to-band tunneling. Furthermore, an analytical solution for the problem of tunneling from continuum states of the disturbed DOS to states in the opposite band is found, and the differences to direct BTBT are worked out. Based on the analytical expressions, a semi-classical model is implemented in a commercial device simulator which involves numerical integration along the tunnel paths. The impact of the tail states on the device performance is analyzed for a nanowire Gate-All-Around TFET. The simulations show that tail states notably impact the transfer characteristics of a TFET. It is found that exponentially decaying band tails result in a stronger degradation of the SS than tail states with a Gaussian decay of their density. The developed model allows more realistic simulations of TFETs including their non-idealities.

A system architecture for an advanced Canadian wideband mobile satellite system

NASA Technical Reports Server (NTRS)

Takats, P.; Keelty, M.; Moody, H.

1993-01-01

In this paper, the system architecture for an advanced Canadian ka-band geostationary mobile satellite system is described, utilizing hopping spot beams to support a 256 kbps wideband service for both N-ISDN and packet-switched interconnectivity to small briefcase-size portable and mobile terminals. An assessment is given of the technical feasibility of the satellite payload and terminal design in the post year 2000 timeframe. The satellite payload includes regeneration and on-board switching to permit single hop interconnectivity between mobile terminals. The mobile terminal requires antenna tracking and platform stabilization to ensure acquisition of the satellite signal. The potential user applications targeted for this wideband service includes: home-office, multimedia, desk-top (PC) videoconferencing, digital audio broadcasting, single and multi-user personal communications.

Hydroxychloroquine binding to cytoplasmic domain of Band 3 in human erythrocytes: Novel mechanistic insights into drug structure, efficacy and toxicity.

PubMed

Nakagawa, Mizuki; Sugawara, Kotomi; Goto, Tatsufumi; Wakui, Hideki; Nunomura, Wataru

2016-05-13

Hydroxychloroquine (HCQ) is a widely used drug in the treatment of autoimmune diseases, such as arthritis and systemic lupus erythematosus. It has also been prescribed for the treatment of malaria owing to its lower toxicity compared to its closely related compound chloroquine (CQ). However, the mechanisms of action of HCQ in erythrocytes (which bind preferentially this drug) have not been documented and the reasons underlying the lower side effects of HCQ compared to CQ remain unclear. Here we show that, although the activity of erythrocyte lactate dehydrogenase (LDH), but not GAPDH, was inhibited by both HCQ and CQ in vitro, LDH activity in erythrocytes incubated with 20 mM HCQ was not significantly reduced within 5 h in contrast to CQ did. Using HCQ coupled Sepharose chromatography (HCQ-Sepharose), we identified Band 3, spectrin, ankyrin, protein 4.1R and protein 4.2 as HCQ binding proteins in human erythrocyte plasma membrane. Recombinant cytoplasmic N-terminal 43 kDa domain of Band 3 bound to HCQ-Sepharose and was eluted with 40 mM (but not 20 mM) HCQ. Band 3 transport activity was reduced by only 23% in the presence of 20 mM HCQ. Taken together, these data demonstrate that HCQ binds to the cytoplasmic N-terminal domain of Band 3 in human erythrocytes but does not inhibit dramatically its transport activity. We hypothesize that the trapping of HCQ on Band 3 contributes to the lower side effects of the drug on energy production in erythrocytes. Copyright © 2016 Elsevier Inc. All rights reserved.

W/V-Band RF Propagation Experiment Design

NASA Technical Reports Server (NTRS)

Acosta, Roberto J.; Nessel, James A.; Simons, Rainee N.; Zemba, Michael J.; Morse, Jacquelynne Rose; Budinger, James M.

2012-01-01

The utilization of frequency spectrum for space-to-ground communications applications has generally progressed from the lowest available bands capable of supporting transmission through the atmosphere to the higher bands, which have required research and technological advancement to implement. As communications needs increase and the available spectrum in the microwave frequency bands (3 30 GHz) becomes congested globally, future systems will move into the millimeter wave (mm-wave) range (30 300 GHz). While current systems are operating in the Ka-band (20 30 GHz), systems planned for the coming decades will initiate operations in the Q-Band (33 50 GHz), V-Band (50 75 GHz) and W Band (75 110 GHz) of the spectrum. These bands offer extremely broadband capabilities (contiguous allocations of 500 MHz to 1GHz or more) and an uncluttered spectrum for a wide range of applications. NASA, DoD and commercial missions that can benefit from moving into the mm-wave bands include data relay and near-Earth data communications, unmanned aircraft communications, NASA science missions, and commercial broadcast/internet services, all able to be implemented via very small terminals. NASA Glenn Research Center has a long history of performing the inherently governmental function of opening new frequency spectrum by characterizing atmospheric effects on electromagnetic propagation and collaborating with the satellite communication industry to develop specific communications technologies for use by NASA and the nation. Along these lines, there are critical issues related to W/V-band propagation that need to be thoroughly understood before design of any operational system can commence. These issues arise primarily due to the limitations imposed on W/V-band signal propagation by the Earth s atmosphere, and to the fundamental lack of understanding of these effects with regards to proper system design and fade mitigation. In this paper, The GRC RF propagation team recommends measurements that are required to assure that the risk associated with the use of mm-wave is minimized. We develop first order beacon and transponder system payload requirements and beacon terminal requirements. We will suggest and discuss a possible hardware implementation for the space segment, as well for the ground segment. A discussion on a propagation measurement campaign for taking relevant statistical data is also included.

Investigation of high spin states in 133Cs

NASA Astrophysics Data System (ADS)

Xu, Q.; Xiao, Z. G.; Zhu, S. J.; Qi, C.; Jia, H.; Qi, B.; Wang, R. S.; Cheng, W. J.; Zhang, Y.; Yi, H.; Lü, L. M.; Wang, Y. J.; Li, H. J.; Huang, Y.; Zhang, Z.; Wu, X. G.; Li, C. B.; Zheng, Y.; Chen, Q. M.; Zhou, W. K.; Li, G. S.

2018-05-01

High spin states in 133Cs nucleus have been studied with the reaction 130Te (7Li, 4n) at a beam energy of 38 MeV. The level scheme has been expanded with spin up to 31/2 \\hbar. Compared with a recent paper, ground state band and other two collective band structures at lower spin states have been confirmed. Another collective band structure at higher spin states as well as some levels and transitions are updated. Compared with the experimental data, large-scale shell model and tilted axis cranking model calculations have been carried out. The results show that the band-head configuration of yrast band based on 7/2+ ground state and the side band built on the 5/2+ state are a pair of pseudospin partner states with π \\tilde{f}_{7/2,5/2}. The negative parity band based on 1071.5 keV level originates from π h_{11/2} orbital. Another band built on 2642.9 keV level at high spin states has been proposed with oblate deformation. Other characteristics for these bands were also discussed.

Energy transition characterization of 1.18 and 1.3 {mu}m bands of bismuth fiber by spectroscopy of the transient oscillations

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

Gumenyuk, Regina; Okhotnikov, Oleg G.; Golant, Konstantin

2011-05-09

The experimental evidence of laser transition type in bismuth-doped silica fibers operating at different spectral bands is presented. Spectrally resolved transient (relaxation) oscillations studied for a Bi-doped fiber laser at room and liquid-nitrogen temperatures allow to identify the three- and four-level energy bands. 1.18 {mu}m short-wavelength band is found to be a three-level system at room temperature with highly populated terminal energy level of laser transition. The depopulation of ground level by cooling the fiber down to liquid-nitrogen temperature changes the transition to four-level type. Four-level energy transition distinguished at 1.32 {mu}m exhibits the net gain at room temperature.

77 FR 30584 - Notice of Termination of United States-Bolivia Bilateral Investment Treaty

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-23

... of Termination of United States--Bolivia Bilateral Investment Treaty AGENCY: Department of State and... delivered to the United States a notice of termination for the bilateral investment treaty between the two... to have effect except that it will continue to apply for another 10 years to covered investments...

Enabling direct silicene integration in electronics: First principles study of silicene on NiSi 2(111)

DOE PAGES

Cheng, Jian -Yih; Chan, Maria K. Y.; Lilley, Carmen M.

2016-09-26

Silicene on metal silicides poses promise for direct integration of silicene into electronic devices. The details of the metal silicide-silicene interface, however, may have significant effects on the electronic properties. In this work, the electronic properties of silicene on NiSi 2(111) and hydrogenated NiSi 2(111) (H:NiSi 2) substrates, as well as hydrogenated silicene (H:silicene) on a NiSi 2(111) substrate, were simulated using first principles methods. The preferred Si surface termination of NiSi 2 was determined through surface energy calculations, and the band structure and density of states (DOS) were calculated for the two-dimensional silicene and H:silicene layers. Hydrogenating NiSi 2more » lowered the binding energy between silicene and the substrate and resulting in partial decoupling of the electronic properties. Relaxed silicene on H:NiSi 2 showed a small band gap opening of 0.14 eV. Silicene on H:NiSi 2 also had a calculated electron effective mass of 0.08m 0 and Fermi velocity of 0.39×10 6 m/s, which are similar to the values for freestanding silicene. H:silicene on NiSi 2 retained its band structure and DOS compared to freestanding H:silicene. The band gap of H:silciene on NiSi 2 was 1.97 eV and is similar to freestanding H:silicene band gap of 2 eV. As a result, this research showed that hydrogenation may be a viable method for decoupling a silicene layer from a NiSi 2(111) substrate to tune its electronic properties.« less

47 CFR 51.709 - Rate structure for transport and termination.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 3 2010-10-01 2010-10-01 false Rate structure for transport and termination... SERVICES (CONTINUED) INTERCONNECTION Reciprocal Compensation for Transport and Termination of Telecommunications Traffic § 51.709 Rate structure for transport and termination. (a) In state proceedings, a state...

47 CFR 51.709 - Rate structure for transport and termination.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 3 2011-10-01 2011-10-01 false Rate structure for transport and termination... SERVICES (CONTINUED) INTERCONNECTION Reciprocal Compensation for Transport and Termination of Telecommunications Traffic § 51.709 Rate structure for transport and termination. (a) In state proceedings, a state...

A 30/20 GHz FSS feasibility study

NASA Technical Reports Server (NTRS)

1987-01-01

The near term feasibility of direct-to-subscriber services were determined using the 30/20 GHz Fixed Satellite Service (FSS) frequency bands. Those technologies which need to be further developed before such a system can be implemented, were identified. To determine this feasibility, dozens of potential applications were examined for their near-term viability, and the subscriber base of three promising applications were estimated. The system requirements, terminal design, and satellite architecture were all investigated to determine whether a 30/20 GHz FSS system is technically and economically feasible by mid-1990s. It was concluded that such a system is feasible, although maturation of some technologies is needed. This system would likely consist of one or two multibeam satellites serving hub/spoke networks of simple user terminals and more complex, mutli-channel terminals of the service providers. Rain compensation would be accomplished non-adaptively through the use of coding, nonuniform satellite TWT power that is a function of a beam's anticipated downlink fading, and signal regeneration of traffic to the wettest climate regions. It was estimated that a potential market of almost two million users could exist in in the mid-1990s time frame for home banking and financial services via Ka-band satellites.

Prenatal diagnosis of a de novo 9p terminal chromosomal deletion in a fetus with major congenital anomalies.

PubMed

Hou, Wen-Chien; Chen, Chih-Ping; Hwang, Kwei-Shuai; Chen, Ying-Chieh; Lai, Yu-Ju; Tien, Chau-Yang; Su, Her-Young

2014-12-01

We describe a prenatal ultrasonography diagnosis of omphalocele and symbrachydactyly in a fetus and review the literature on prenatal diagnosis of 9p terminal chromosomal deletions. A 31-year-old woman (gravida 3, para 1) was referred for genetic counseling because a fetal omphalocele had been detected. Prenatal ultrasonography at 17+ weeks of gestational age revealed a singleton female fetus with biometry equivalent to 18 weeks with an omphalocele. In addition, symbrachydactyly was also noted in the right arm; the wrist bones as well as the metacarpals were missing. A chromosomal study was arranged for a congenital anomaly involving omphalocele. We obtained Giemsa-banded chromosomes from fetal tissue cells, and an abnormal male karyotype with a terminal deletion of the short arm of chromosome 9 at band 9p13 was noted. After delivery, the fetus showed omphalocele, symbrachydactyly, trigonocephaly, sex reversal, a long philtrum, low-set ears, telecanthus, and a frontal prominence. Prenatal diagnosis of abnormal ultrasound findings with omphalocele and symbrachydactyly should include the differential diagnosis of a chromosome 9p deletion. Copyright © 2014. Published by Elsevier B.V.

ATS-6 engineering performance report. Volume 5: Propagation experiments

NASA Technical Reports Server (NTRS)

Wales, R. O. (Editor)

1981-01-01

Propagation experiments at 1550 MHz to 1650 MHz are reviewed, including the Integrated L-Band Experiments system and results, and the Mobile L-Band Terminals for Satellite Communication system. Experiments at 4 GHz to 6 GHz are reported, including the Radio Frequency Interferometer Measurements system and results, and Earth station antenna evaluations. Experiments above 10 GHz are discussed, including Comsat and ATS-6 millimeter wave propagation/experiments, and communication ATS-6 version at 20 and 30 GHz.

47 CFR 15.240 - Operation in the band 433.5-434.5 MHz.

Code of Federal Regulations, 2013 CFR

2013-10-01

... commercial and industrial areas such as ports, rail terminals and warehouses. Two-way operation is permitted... locations where the devices are installed to the FCC Office of Engineering and Technology, which shall...

47 CFR 15.240 - Operation in the band 433.5-434.5 MHz.

Code of Federal Regulations, 2012 CFR

2012-10-01

... commercial and industrial areas such as ports, rail terminals and warehouses. Two-way operation is permitted... locations where the devices are installed to the FCC Office of Engineering and Technology, which shall...

47 CFR 15.240 - Operation in the band 433.5-434.5 MHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... commercial and industrial areas such as ports, rail terminals and warehouses. Two-way operation is permitted... locations where the devices are installed to the FCC Office of Engineering and Technology, which shall...

47 CFR 15.240 - Operation in the band 433.5-434.5 MHz.

Code of Federal Regulations, 2011 CFR

2011-10-01

... commercial and industrial areas such as ports, rail terminals and warehouses. Two-way operation is permitted to interrogate and to load data into devices. Devices operated pursuant to the provisions of this...

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

Rembold, Randy Kai; Hart, Darren M.; Harris, James Mark

Sandia National Laboratories has tested, evaluated and reported on the Geotech Smart24 data acquisition system with active Fortezza crypto card data signing and authentication in SAND2008-. One test, Input Terminated Noise, allows us to characterize the self-noise of the Smart24 system. By computing the power spectral density (PSD) of the input terminated noise time series data set and correcting for the instrument response of different seismometers, the resulting spectrum can be compared to the USGS new low noise model (NLNM) of Peterson (1996), and determine the ability of the matched system of seismometer and Smart24 to be quiet enough formore » any general deployment location. Four seismometer models were evaluated: the Streckeisen STS2-Low and High Gain, Guralp CMG3T and Geotech GS13 models. Each has a unique pass-band as defined by the frequency band of the instrument corrected noise spectrum that falls below the new low-noise model.« less

US development and commercialization of a North American mobile satellite service

NASA Technical Reports Server (NTRS)

Arnold, Ray J.; Gray, Valerie; Freibaum, Jerry

1990-01-01

U.S. policies promoting applications and commercialization of space technology for the 'benefit of mankind,' and emphasis on international competitiveness, formed the basis of NASA's Mobile Satellite (MSAT) R&D and user experiments program to develop a commercial U.S. Mobile Satellite Service. Exemplifying this philosophy, the MSAT program targets the reduction of technical, regulatory, market, and financial risks that inhibit commercialization. The program strategy includes industry and user involvement in developing and demonstrating advanced technologies, regulatory advocacy, and financial incentives to industry. Approximately two decades of NASA's satellite communications development and demonstrations have contributed to the emergence of a new multi-billion dollar industry for land, aeronautical, and maritime mobile communications via satellite. NASA's R&D efforts are now evolving from the development of 'enabling' ground technologies for VHF, UHF, and L-Band mobile terminals, to Ka-Band terminals offering additional mobility and user convenience.

Public service satellite communications

NASA Technical Reports Server (NTRS)

Wolff, E. A.

1978-01-01

It is suggested that the high effective isotropic radiated power provided by high-power satellite transmitters and high-gain antennas could be used in conjunction with economical ground receivers to furnish public services in remote areas of the U.S. Applications to health care, education and public safety are mentioned. A system concept involving a communications satellite operating in the Ku-band (12-GHz down, 14-GHz up) and either 100/30 watt stationary earth terminals with 1-1.8 m antennas or mobile terminals with omnidirectional antennas is presented.

DNA Sequencing apparatus

DOEpatents

Tabor, Stanley; Richardson, Charles C.

1992-01-01

An automated DNA sequencing apparatus having a reactor for providing at least two series of DNA products formed from a single primer and a DNA strand, each DNA product of a series differing in molecular weight and having a chain terminating agent at one end; separating means for separating the DNA products to form a series bands, the intensity of substantially all nearby bands in a different series being different, band reading means for determining the position an This invention was made with government support including a grant from the U.S. Public Health Service, contract number AI-06045. The U.S. government has certain rights in the invention.

Spectroscopic evidence for a type II Weyl semimetallic state in MoTe 2

DOE PAGES

Huang, Lunan; McCormick, Timothy M.; Ochi, Masayuki; ...

2016-07-11

In a type I Dirac or Weyl semimetal, the low-energy states are squeezed to a single point in momentum space when the chemical potential μ is tuned precisely to the Dirac/Weyl point. Recently, a type II Weyl semimetal was predicted to exist, where the Weyl states connect hole and electron bands, separated by an indirect gap. This leads to unusual energy states, where hole and electron pockets touch at the Weyl point. Here we present the discovery of a type II topological Weyl semimetal state in pure MoTe 2, where two sets of Weyl points ( W±2 , W±3) existmore » at the touching points of electron and hole pockets and are located at different binding energies above E F. Using angle-resolved photoemission spectroscopy, modelling, density functional theory and calculations of Berry curvature, we identify the Weyl points and demonstrate that they are connected by different sets of Fermi arcs for each of the two surface terminations. We also find new surface ‘track states’ that form closed loops and are unique to type II Weyl semimetals. Lastly, this material provides an exciting, new platform to study the properties of Weyl fermions.« less

45 CFR 96.92 - Termination of funding.

Code of Federal Regulations, 2014 CFR

2014-10-01

... the Community Services Block Grant Act that it will terminate present or future funding of any... the record prior to terminating funding. If a review by the Secretary of the State's final decision to... of notification by the State of its final decision to terminate funding. The Department will confirm...

45 CFR 96.92 - Termination of funding.

Code of Federal Regulations, 2012 CFR

2012-10-01

... the Community Services Block Grant Act that it will terminate present or future funding of any... the record prior to terminating funding. If a review by the Secretary of the State's final decision to... of notification by the State of its final decision to terminate funding. The Department will confirm...

45 CFR 96.92 - Termination of funding.

Code of Federal Regulations, 2011 CFR

2011-10-01

... the Community Services Block Grant Act that it will terminate present or future funding of any... the record prior to terminating funding. If a review by the Secretary of the State's final decision to... of notification by the State of its final decision to terminate funding. The Department will confirm...

45 CFR 96.92 - Termination of funding.

Code of Federal Regulations, 2013 CFR

2013-10-01

... the Community Services Block Grant Act that it will terminate present or future funding of any... the record prior to terminating funding. If a review by the Secretary of the State's final decision to... of notification by the State of its final decision to terminate funding. The Department will confirm...

Performance of the NASA Beacon Receiver for the Alphasat Aldo Paraboni TDP5 Propagation Experiment

NASA Technical Reports Server (NTRS)

Nessel, James; Morse, Jacquelynne; Zemba, Michael; Riva, Carlo; Luini, Lorenzo

2015-01-01

NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have initiated a joint propagation campaign within the framework of the Alphasat propagation experiment to characterize rain attenuation, scintillation, and gaseous absorption effects of the atmosphere in the 40 gigahertz band. NASA GRC has developed and installed a K/Q-band (20/40 gigahertz) beacon receiver at the POLIMI campus in Milan, Italy, which receives the 20/40 gigahertz signals broadcast from the Alphasat Aldo Paraboni Technology Demonstration Payload (TDP) no. 5 beacon payload. The primary goal of these measurements is to develop a physical model to improve predictions of communications systems performance within the Q-band. Herein, we describe the design and preliminary performance of the NASA propagation terminal, which has been installed and operating in Milan since June 2014. The receiver is based upon a validated Fast Fourier Transform (FFT) I/Q digital design approach utilized in other operational NASA propagation terminals, but has been modified to employ power measurement via a frequency estimation technique and to coherently track and measure the amplitude of the 20/40 gigahertz beacon signals. The system consists of a 1.2-meter K-band and a 0.6-meter Q-band Cassegrain reflector employing synchronous open-loop tracking to track the inclined orbit of the Alphasat satellite. An 8 hertz sampling rate is implemented to characterize scintillation effects, with a 1-hertz measurement bandwidth dynamic range of 45 decibels. A weather station with an optical disdrometer is also installed to characterize rain drop size distribution for correlation with physical based models.

Helical image reconstruction of the outward-open human erythrocyte band 3 membrane domain in tubular crystals.

PubMed

Yamaguchi, Tomohiro; Fujii, Takashi; Abe, Yoshito; Hirai, Teruhisa; Kang, Dongchon; Namba, Keiichi; Hamasaki, Naotaka; Mitsuoka, Kaoru

2010-03-01

The C-terminal membrane domain of erythrocyte band 3 functions as an anion exchanger. Here, we report the three-dimensional (3D) structure of the membrane domain in an inhibitor-stabilized, outward-open conformation at 18A resolution. Unstained, frozen-hydrated tubular crystals containing the membrane domain of band 3 purified from human red blood cells (hB3MD) were examined using cryo-electron microscopy and iterative helical real-space reconstruction (IHRSR). The 3D image reconstruction of the tubular crystals showed the molecular packing of hB3MD dimers with dimensions of 60 x 110 A in the membrane plane and a thickness of 70A across the membrane. Immunoelectron microscopy and carboxyl-terminal digestion demonstrated that the intracellular surface of hB3MD was exposed on the outer surface of the tubular crystal. A 3D density map revealed that hB3MD consists of at least two subdomains and that the outward-open form is characterized by a large hollow area on the extracellular surface and continuous density on the intracellular surface. (c) 2009 Elsevier Inc. All rights reserved.

Ultra-High Efficiency, High-Concentration PV System Based On Spectral Division Between GaInP/GaInAs/Ge And BPC Silicon Cells

NASA Astrophysics Data System (ADS)

Benítez, P.; Mohedano, R.; Buljan, M.; Miñano, J. C.; Sun, Y.; Falicoff, W.; Vilaplana, J.; Chaves, J.; Biot, G.; López, J.

2011-12-01

A novel HCPV nonimaging concentrator concept with high concentration (>500×) is presented. It uses the combination of a commercial concentration GaInP/GaInAs/Ge 3J cell and a concentration Back-Point-Contact (BPC) concentration silicon cell for efficient spectral utilization, and external confinement techniques for recovering the 3J cell's reflection. The primary optical element (POE) is a flat Fresnel lens and the secondary optical element (SOE) is a free-form RXI-type concentrator with a band-pass filter embedded it, both POE and SOE performing Köhler integration to produce light homogenization. The band-pass filter sends the IR photons in the 900-1200 nm band to the silicon cell. Computer simulations predict that four-terminal terminal designs could achieve ˜46% added cell efficiencies using commercial 39% 3J and 26% Si cells. A first proof-of concept receiver prototype has been manufactured using a simpler optical architecture (with a lower concentration, ˜100× and lower simulated added efficiency), and experimental measurements have shown up to 39.8% 4J receiver efficiency using a 3J with peak efficiency of 36.9%.

Short stature in a mother and daughter with terminal deletion of Xp22.3

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

Schwinger, E.; Kirschstein, M.; Konermann, T.

1996-05-03

Short stature in females is often caused by homozygosity for the terminal portion of Xp due to monosomy X or a deletion. We report on a mother and daughter with short stature as sole phenotypic abnormality and deletion of bands Xp22.32-p22.33 demonstrated by classic and molecular cytogenetic analysis. In both individuals, the deleted X chromosome was late replicating. Molecular analysis suggested that the deletion is terminal and the breakpoint was localized between the STS and DXS7470 loci in Xp22.32. Chromosome analysis is often done on females with short stature to exclude Ullrich-Turner syndrome. Small deletions, terminal or interstitial, are easilymore » missed by conventional cytogenetic investigation; thus molecular analyses are useful to detect those cases. 8 refs., 3 figs.« less

Symmetry analysis of strain, electric and magnetic fields in the Bi2Se3-class of topological insulators

NASA Astrophysics Data System (ADS)

Rosdahl Brems, Mathias; Paaske, Jens; Lunde, Anders Mathias; Willatzen, Morten

2018-05-01

Based on group theoretical arguments we derive the most general Hamiltonian for the Bi2Se3-class of materials including terms to third order in the wave vector, first order in electric and magnetic fields, first order in strain and first order in both strain and wave vector. We determine analytically the effects of strain on the electronic structure of Bi2Se3. For the most experimentally relevant surface termination we analytically derive the surface state (SS) spectrum, revealing an anisotropic Dirac cone with elliptical constant energy contours giving rise to a direction-dependent group velocity. The spin-momentum locking of strained Bi2Se3 is shown to be modified. Hence, strain control can be used to manipulate the spin degree of freedom via the spin–orbit coupling. We show that for a thin film of Bi2Se3 the SS band gap induced by coupling between the opposite surfaces changes opposite to the bulk band gap under strain. Tuning the SS band gap by strain, gives new possibilities for the experimental investigation of the thickness dependent gap and optimization of optical properties relevant for, e.g., photodetector and energy harvesting applications. We finally derive analytical expressions for the effective mass tensor of the Bi2Se3 class of materials as a function of strain and electric field.

Molecular and cytogenetic characterization of a de novo partial trisomy 3p case with review

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

Conte, R.A.; Pitter, J.; Verma, R.S.

A one-year-old male infant was found to have a de novo unbalanced translocation resulting in partial trisomy for 3p, i.e. 46,XY,der(7)t(3;7)(p24.2;p22). Major clinical features included: dysmorphic ears, decreased muscle tone and episodes of seizures associated with fever. GTG- and QFQ-banding revealed additional material suggestive of chromosome 3p that was translocated to the terminal 7p. The FISH technique with two-color specific DNA probes for whole chromosomes 3 and 7 verified this finding. Other probands with the same amount of trisomic 3p2 segments as the present case had additional clinical abnormalities. Previously, identification of this so-called trisomy 3p2 syndrome was invariably basedmore » on the analysis of GTG-banded metaphase chromosomes. A review of 37 earlier cases revealed that the clinical manifestations varied with the amount of 3p2 material in the trisomic state, demonstrating increased anomalies with increased 3p2 sub-band trisomy. Phenotype to genotype correlation is best understood under conditions that can achieve respective characterization with a high degree of certainty. Presently, the FISH technique fulfills this requirement and the employment of loci probes that span 3p, when available, will ultimately increase the characterization resolution to the gene level.« less

Signal Processing Algorithms for the Terminal Doppler Weather Radar: Build 2

DTIC Science & Technology

2010-04-30

the various TDWR base data quality issues, range-velocity (RV) ambiguity was deemed to be the most severe challenge nationwide. Compared to S - band ... power is computed as PN = median(|5«| 2)/(ln 2), where s is the complex I&Q signal, k is the range gate number, and / is the pulse time index. The...frequencies to the ground-clutter band around zero, the clutter filtering also removes power from the aliased frequencies and distorts the phase response

A satellite system for multimedia personal communications at Ka-band and beyond

NASA Technical Reports Server (NTRS)

Vatalaro, F.; Losquadro, G.

1995-01-01

The main characteristics of the satellite extremely high frequency (EHF) communication of multimedia mobile services (SECOMS) system are given and the results of the preliminary analysis are included. The SECOMS provides a first generation Ka band system with coverage over Western Europe, in order to satisfy business user needs of very large bandwidths and terminal mobility. The satellite system also provides a second generation EHF enhanced system with increased capacity and enlarged coverage, to serve all of Europe and the nearby countries.

Bloch oscillating transistor-a new mesoscopic amplifier

NASA Astrophysics Data System (ADS)

Delahaye, J.; Hassel, J.; Lindell, R.; Sillanpää, M.; Paalanen, M.; Seppä, H.; Hakonen, P.

2003-05-01

Bloch oscillating transistor (BOT) is a novel, three-terminal Josephson junction device. Its operating principle utilizes the fact that Zener tunneling up to a higher band will lead to a blockade of coherent Cooper-pair tunneling, Bloch oscillation, in a suitably biased Josephson junction. The Bloch oscillation is resumed only after the junction has relaxed to the lowest band by quasiparticle tunneling. In this paper we present a simple model for the operation of the BOT and calculate its gain in terms of the interband transition rates.

Banded karyotype of the Konya wild sheep (Ovis orientalis anatolica Valenciennes, 1856) from Turkey

PubMed Central

Arslan, Atilla; Zima, Jan

2011-01-01

Abstract Thekaryotype, C-banding, and nucleoar organizer regions (NORs) of eight specimens ofKonya wild sheepfrom Turkey were examined. The complement included six large metacentric autosomes, 46 acrocentric autosomes of decreasing size, a medium-sized acrocentric X chromosome, and a small bi-armed Y chromosome (the diploid chromosome number 2n=54, the number of autosomal arms NFa=58, the number of chromosome arms NF=61). G-banding allowed reliable identification of all the chromosome pairs and the pairing of homologous elements. All the autosomes possessed distinct centromeric or pericentromeric C-positive bands. The X chromosome had a pericentromeric C-positive band, and the Y chromosome was entirely C-heterochromatic. The NORs were located in the terminal regions of the long arms of three metacentric and two acrocentric autosomes. The karyotype of the Konya wild sheep and its banding patterns are quite similar to chromosome complement reported in domestic sheep and European mouflon. PMID:24260621

Radio Frequency Compatibility Evaluation of S Band Navigation Signals for Future BeiDou

PubMed Central

Sun, Yanbo; Xue, Rui; Zhao, Danfeng; Wang, Dun

2017-01-01

With L band frequency allocations for satellite navigation getting more crowded, S band (2483.5–2500 MHz) is already allocated for navigation services, where Globalstar broadcasts downlink communications to user terminals. The Indian Regional Navigation Satellite System (IRNSS) is transmitting navigation signals and Galileo exploits some potential signals in S band. Also, several candidate S band signals based on binary offset carrier (BOC), binary phase shift keying (BPSK), continuous phase modulation (CPM) and minimum shift keying-BOC (MSK-BOC) are suggested for BeiDou system (BDS). In quite narrow S band, mutual interference among these systems is inevitable, thus the compatibility issue is particularly significant for S band signal design. To explore desired S band signals for BDS, the paper firstly describes a comprehensive compatibility evaluation methods based on effective carrier-to-noise ratio degradation for acquisition and code tracking. Then a real simulation is established using space constellations, modulation schemes and received power. Finally, the worst mutual interference of BDS candidate signals with Galileo, IRNSS and Globalstar is calculated and compared. The results indicate that CPM signal is easier to allow peaceful coexistence of other systems with minimal mutual interference in S band compared to other BDS candidates. PMID:28475142

Radio Frequency Compatibility Evaluation of S Band Navigation Signals for Future BeiDou.

PubMed

Sun, Yanbo; Xue, Rui; Zhao, Danfeng; Wang, Dun

2017-05-05

With L band frequency allocations for satellite navigation getting more crowded, S band (2483.5-2500 MHz) is already allocated for navigation services, where Globalstar broadcasts downlink communications to user terminals. The Indian Regional Navigation Satellite System (IRNSS) is transmitting navigation signals and Galileo exploits some potential signals in S band. Also, several candidate S band signals based on binary offset carrier (BOC), binary phase shift keying (BPSK), continuous phase modulation (CPM) and minimum shift keying-BOC (MSK-BOC) are suggested for BeiDou system (BDS). In quite narrow S band, mutual interference among these systems is inevitable, thus the compatibility issue is particularly significant for S band signal design. To explore desired S band signals for BDS, the paper firstly describes a comprehensive compatibility evaluation methods based on effective carrier-to-noise ratio degradation for acquisition and code tracking. Then a real simulation is established using space constellations, modulation schemes and received power. Finally, the worst mutual interference of BDS candidate signals with Galileo, IRNSS and Globalstar is calculated and compared. The results indicate that CPM signal is easier to allow peaceful coexistence of other systems with minimal mutual interference in S band compared to other BDS candidates.

The Asian monsoon over the past 640,000 years and ice age terminations.

PubMed

Cheng, Hai; Edwards, R Lawrence; Sinha, Ashish; Spötl, Christoph; Yi, Liang; Chen, Shitao; Kelly, Megan; Kathayat, Gayatri; Wang, Xianfeng; Li, Xianglei; Kong, Xinggong; Wang, Yongjin; Ning, Youfeng; Zhang, Haiwei

2016-06-30

Oxygen isotope records from Chinese caves characterize changes in both the Asian monsoon and global climate. Here, using our new speleothem data, we extend the Chinese record to cover the full uranium/thorium dating range, that is, the past 640,000 years. The record's length and temporal precision allow us to test the idea that insolation changes caused by the Earth's precession drove the terminations of each of the last seven ice ages as well as the millennia-long intervals of reduced monsoon rainfall associated with each of the terminations. On the basis of our record's timing, the terminations are separated by four or five precession cycles, supporting the idea that the '100,000-year' ice age cycle is an average of discrete numbers of precession cycles. Furthermore, the suborbital component of monsoon rainfall variability exhibits power in both the precession and obliquity bands, and is nearly in anti-phase with summer boreal insolation. These observations indicate that insolation, in part, sets the pace of the occurrence of millennial-scale events, including those associated with terminations and 'unfinished terminations'.

Status of the Direct Data Distribution (D(exp 3)) Experiment

NASA Technical Reports Server (NTRS)

Wald, Lawrence

2001-01-01

NASA Glenn Research Center's Direct Data Distribution (D3) project will demonstrate an advanced, high-performance communications system that transmits information from an advanced technology payload carried by a NASA spacecraft in low Earth orbit (LEO) to a small receiving terminal on Earth. The space-based communications package will utilize a solid-state, K-band phased-array antenna that electronically steers the radiated energy beam toward a low-cost, tracking ground terminal, thereby providing agile, vibration-free, electronic steering at reduced size and weight with increased reliability. The array-based link will also demonstrate new digital processing technology that will allow the transmission of substantially increased amounts of latency-tolerant data collected from the LEO spacecraft directly to NASA field centers, principal investigators, or into the commercial terrestrial communications network. The technologies demonstrated by D3 will facilitate NASA's transition from using Government-owned communication assets to using commercial communication services. The hardware for D3 will incorporate advanced technology components developed under the High Rate Data Delivery (HRDD) Thrust Area of NASA's Office of Aerospace Technology Space Base Program at Glenn's Communications Technology Division. The flight segment components will include the electrically steerable phased-array antenna, which is being built by the Raytheon System Corporation and utilizes monolithic microwave integrated circuit (MMIC) technology operating at 19.05 GHz; and the digital encoder/modulator chipset, which uses four-channel orthogonal frequency division multiplexing (OFDM). The encoder/modulator will use a chipset developed by SICOM, Inc., which is both bandwidth and power efficient. The ground segment components will include a low-cost, open-loop tracking ground terminal incorporating a cryoreceiver to minimize terminal size without compromising receiver capability. The project is planning to hold a critical design review in the second quarter of fiscal year 2002.

Oxygen termination of homoepitaxial diamond surface by ozone and chemical methods: An experimental and theoretical perspective

NASA Astrophysics Data System (ADS)

Navas, Javier; Araujo, Daniel; Piñero, José Carlos; Sánchez-Coronilla, Antonio; Blanco, Eduardo; Villar, Pilar; Alcántara, Rodrigo; Montserrat, Josep; Florentin, Matthieu; Eon, David; Pernot, Julien

2018-03-01

Phenomena related with the diamond surface of both power electronic and biosensor devices govern their global behaviour. In particular H- or O-terminations lead to wide variations in their characteristics. To study the origins of such aspects in greater depth, different methods to achieve oxygen terminated diamond were investigated following a multi-technique approach. DFT calculations were then performed to understand the different configurations between the C and O atoms. Three methods for O-terminating the diamond surface were performed: two physical methods with ozone at different pressures, and an acid chemical treatment. X-ray photoelectron spectroscopy, spectroscopic ellipsometry, HRTEM, and EELS were used to characterize the oxygenated surface. Periodic-DFT calculations were undertaken to understand the effect of the different ways in which the oxygen atoms are bonded to carbon atoms on the diamond surface. XPS results showed the presence of hydroxyl or ether groups, composed of simple Csbnd O bonds, and the acid treatment resulted in the highest amount of O on the diamond surface. In turn, ellipsometry showed that the different treatments led to the surface having different optical properties, such as a greater refraction index and extinction coefficient in the case of the sample subjected to acid treatment. TEM analysis showed that applying temperature treatment improved the distribution of the oxygen atoms at the interface and that this generates a thinner amount of oxygen at each position and higher interfacial coverage. Finally, DFT calculations showed both an increase in the number of preferential electron transport pathways when π bonds and ether groups appear in the system, and also the presence of states in the middle of the band gap when there are π bonds, Cdbnd C or Cdbnd O.

Conceptual communications system design in the 25.25-27.5 and 37.0-40.5 GHz frequency bands

NASA Technical Reports Server (NTRS)

Thompson, Michael W.

1993-01-01

Future space applications are likely to rely heavily on Ka-band frequencies (20-40 GHz) for communications traffic. Many space research activities are now conducted using S-band and X-band frequencies, which are becoming congested and require a degree of pre-coordination. In addition to providing relief from frequency congestion, Ka-band technologies offer potential size, weight, and power savings when compared to lower frequency bands. The use of the 37.0-37.5 and 40.0-40.5 GHz bands for future planetary missions was recently approved at the 1992 World Administrative Radio Conference (WARC-92). WARC-92 also allocated the band 25.25-27.5 GHz to the Intersatellite Service on a primary basis to accommodate Data Relay Satellite return link requirements. Intersatellite links are defined to be between artificial satellites and thus a communication link with the surface of a planetary body, such as the moon, and a relay satellite orbiting that body are not permitted in this frequency band. This report provides information about preliminary communications system concepts for forward and return links for earth-Mars and earth-lunar links using the 37.0-37.5 (return link) and 40.0-40.5 (forward link) GHz frequency bands. In this study we concentrate primarily on a conceptual system for communications between earth and a single lunar surface terminal (LST), and between earth and a single Mars surface terminal (MST). Due to large space losses, these links have the most stringent link requirements for an overall interplanetary system. The earth ground station is assumed to be the Deep Space Network (DSN) using either 34 meter or 70 meter antennas. We also develop preliminary communications concepts for a space-to-space system operating at near 26 GHz. Space-to-space applications can encompass a variety of operating conditions, and we consider several 'typical' scenarios described in more detail later in this report. Among these scenarios are vehicle-to-vehicle communications, vehicle-to-geosyncronous satellite (GEO) communications, and GEO-to-GEO communications. Additional details about both the interplanetary and space-to-space communications systems are provided in an 'expanded' final report which has been submitted to the Tracking and Communications Division (TCD) at the NASA Johnson Space Center.

Efficient Near-Infrared-Transparent Perovskite Solar Cells Enabling Direct Comparison of 4-Terminal and Monolithic Perovskite/Silicon Tandem Cells

DOE PAGES

Werner, Jeremie; Barraud, Loris; Walter, Arnaud; ...

2016-07-30

Combining market-proven silicon solar cell technology with an efficient wide band gap top cell into a tandem device is an attractive approach to reduce the cost of photovoltaic systems. For this, perovskite solar cells are promising high-efficiency top cell candidates, but their typical device size (<0.2 cm 2), is still far from standard industrial sizes. Here, we present a 1 cm 2 near-infrared transparent perovskite solar cell with 14.5% steadystate efficiency, as compared to 16.4% on 0.25 cm 2. By mechanically stacking these cells with silicon heterojunction cells, we experimentally demonstrate a 4-terminal tandem measurement with a steady-state efficiency ofmore » 25.2%, with a 0.25 cm 2 top cell. The developed top cell processing methods enable the fabrication of a 20.5% efficient and 1.43 cm 2 large monolithic perovskite/silicon heterojunction tandem solar cell, featuring a rear-side textured bottom cell to increase its near-infrared spectral response. Finally, we compare both tandem configurations to identify efficiency-limiting factors and discuss the potential for further performance improvement.« less

Model for the broadband Crab nebula spectrum with injection of a log-parabola electron distribution at the wind termination shock

NASA Astrophysics Data System (ADS)

Fraschetti, F.; Pohl, M.

2017-10-01

We develop a model of the steady-state spectrum of the Crab nebula encompassing both the radio/soft X-ray and the GeV/multi-TeV observations. By solving the transport equation for TeV electrons injected at the wind termination shock as a log-parabola momentum distribution and evolved via energy losses, we determine analytically the resulting photon differential energy spectrum. We find an impressive agreement with the observations in the synchrotron region. The predicted synchrotron self-Compton accommodates the previously unsolved origin of the broad 200 GeV peak that matches the Fermi/LAT data beyond 1 GeV with the MAGIC data. A natural interpretation of the deviation from power-law of the photon spectrum customarily fit with empirical broken power-laws is provided. This model can be applied to the radio-to- multi-TeV spectra of a variety of astrophysical outflows, including pulsar wind nebulae and supernova remnants. We also show that MeV-range energetic particle distribution at interplanetary shocks typically fit with broken-power laws or Band function can be accurately reproduced by log-parabolas.

Efficient Near-Infrared-Transparent Perovskite Solar Cells Enabling Direct Comparison of 4-Terminal and Monolithic Perovskite/Silicon Tandem Cells

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

Werner, Jeremie; Barraud, Loris; Walter, Arnaud

Combining market-proven silicon solar cell technology with an efficient wide band gap top cell into a tandem device is an attractive approach to reduce the cost of photovoltaic systems. For this, perovskite solar cells are promising high-efficiency top cell candidates, but their typical device size (<0.2 cm 2), is still far from standard industrial sizes. Here, we present a 1 cm 2 near-infrared transparent perovskite solar cell with 14.5% steadystate efficiency, as compared to 16.4% on 0.25 cm 2. By mechanically stacking these cells with silicon heterojunction cells, we experimentally demonstrate a 4-terminal tandem measurement with a steady-state efficiency ofmore » 25.2%, with a 0.25 cm 2 top cell. The developed top cell processing methods enable the fabrication of a 20.5% efficient and 1.43 cm 2 large monolithic perovskite/silicon heterojunction tandem solar cell, featuring a rear-side textured bottom cell to increase its near-infrared spectral response. Finally, we compare both tandem configurations to identify efficiency-limiting factors and discuss the potential for further performance improvement.« less

A tunable electronic beam splitter realized with crossed graphene nanoribbons

NASA Astrophysics Data System (ADS)

Brandimarte, Pedro; Engelund, Mads; Papior, Nick; Garcia-Lekue, Aran; Frederiksen, Thomas; Sánchez-Portal, Daniel

2017-03-01

Graphene nanoribbons (GNRs) are promising components in future nanoelectronics due to the large mobility of graphene electrons and their tunable electronic band gap in combination with recent experimental developments of on-surface chemistry strategies for their growth. Here, we explore a prototype 4-terminal semiconducting device formed by two crossed armchair GNRs (AGNRs) using state-of-the-art first-principles transport methods. We analyze in detail the roles of intersection angle, stacking order, inter-GNR separation, GNR width, and finite voltages on the transport characteristics. Interestingly, when the AGNRs intersect at θ =60° , electrons injected from one terminal can be split into two outgoing waves with a tunable ratio around 50% and with almost negligible back-reflection. The split electron wave is found to propagate partly straight across the intersection region in one ribbon and partly in one direction of the other ribbon, i.e., in analogy with an optical beam splitter. Our simulations further identify realistic conditions for which this semiconducting device can act as a mechanically controllable electronic beam splitter with possible applications in carbon-based quantum electronic circuits and electron optics. We rationalize our findings with a simple model suggesting that electronic beam splitters can generally be realized with crossed GNRs.

Gravity Chromatic Imaging of the Eta Car's Core

NASA Astrophysics Data System (ADS)

Sanchez-Bermudez, Joel

2018-04-01

Eta Car is one of the most massive, and intriguing, Luminous Blue Variables known. In its core resides a binary with a 5.54 years orbital period. Visible, infrared, and X-raobservations suggest that the primary star exhibits a very dense wind with a terminal velocity of about 420 km/s, while the secondary shows a much faster and less dense wind with a terminal velocity of 3000 km/s. The wind-wind collision zone at the core of Eta Car is thus a complex region that deserves a detailed study to understand the effect of the binary interaction in the evolution of the system. Here, we will present a unique imaging campaign with GRAVITY/VLTI of the Eta Car's core. The superb quality of our interferometric data, together with state-of-the-art image reconstruction techniques, allowed us to obtain, with milliarcsecond resolution, continuum and chromatic images cross the BrG and HeI lines in the Eta Car K-band spectrum (R 4000). These new data together with models of the primary wind of Eta Car has letting us to characterize the spatial distribution of the dust and gas in the inner 40 AU wind-wind collision zone of the target.

Special Effects: Antenna Wetting, Short Distance Diversity and Depolarization

NASA Technical Reports Server (NTRS)

Acosta, Roberto J.

2000-01-01

The Advanced Communication Technology Satellite (ACTS) communications system operates in the Ka frequency band. ACTS uses multiple, hopping, narrow beams and very small aperture terminal (VSAT) technology to establish a system availability of 99.5% for bit-error-rates of 5 x 10(exp -7) Or better over the continental United States. In order maintain this minimum system availability in all US rain zones, ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is to present the results of system and sub-system characterizations considering the statistical effects of system variances due to antenna wetting and depolarization effects. In addition the availability enhancements using short distance diversity in a sub-tropical rain zone are investigated.

Reward banding to determine reporting rate of recovered mourning dove bands

USGS Publications Warehouse

Tomlinson, R.E.

1968-01-01

Reward bands placed on the other leg of certain regularly banded immature mourning doves (Zenaidura macroura) were used to develop information on reporting rates of recovered dove bands. Reports from 15 widely separated sections of the United States showed considerable variation in recovery rate of doves both with and without reward bands. The overall percentages of banded doves that were reported as recovered were 9.69% for those with reward bands and 3.83% for controls. The bandreporting rate for states influenced by publicity was 66%; that for states not influenced was 32%.

Bias Selectable Dual Band AlGaN Ultra-violet Detectors

NASA Technical Reports Server (NTRS)

Yan, Feng; Miko, Laddawan; Franz, David; Guan, Bing; Stahle, Carl M.

2007-01-01

Bias selectable dual band AlGaN ultra-violet (UV) detectors, which can separate UV-A and UV-B using one detector in the same pixel by bias switching, have been designed, fabricated and characterized. A two-terminal n-p-n photo-transistor-like structure was used. When a forward bias is applied between the top electrode and the bottom electrode, the detectors can successfully detect W-A and reject UV-B. Under reverse bias, they can detect UV-B and reject UV-A. The proof of concept design shows that it is feasible to fabricate high performance dual-band UV detectors based on the current AlGaN material growth and fabrication technologies.

Feasibility Activities Completed for the Direct Data Distribution (D(sup )3) Experiment

NASA Technical Reports Server (NTRS)

Wald, Lawrence W.

2000-01-01

The Direct Data Distribution (D(sup 3)) project being designed at the NASA Glenn Research Center at Lewis Field will demonstrate a high-performance communications system that transmits information at up to 1.2 gigabits per second (Gbps) from an advanced technology payload carried by the space shuttles in low Earth orbit to small (0.9-m) autonomously tracking terminals on the Earth. The flight communications package features a solid-state, phased-array antenna operating in the commercial K-band frequency that electronically steers two independently controlled downlink beams toward low-cost tracking ground terminals. The array enables agile, vibration-free beam steering at reduced size and weight with increased reliability over traditional mechanically steered reflectors. The flight experiment will also demonstrate efficient digital modulation technology that allows transmission of substantially increased amounts of latency-tolerant data (up to 72 Gb of data per minute of contact time) with very high quality (10(exp -11) bit error rate). D(sup 3) enables transmission from low-Earth-orbit science spacecraft, the shuttles, or the International Space Station directly to NASA field centers and principle investigator sites, or directly into the commercial terrestrial telecommunications network for remote distribution and archive. The ground terminal features a cryocooled receiver for ultralow noise and a reduced antenna aperture as well as open-loop tracking for unattended operations. The D(sup 3) technology validation and service demonstration will help to facilitate NASA's transition from using Government-owned communications assets to using commercially provided services.

A first-principles study of electronic properties of H and F-terminated zigzag BNC nanoribbons

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

Alaal, Naresh; Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.; Department of Materials Engineering, Monash University, Clayton, Victoria -3800, Australia.

2016-05-06

Nanoribbons are quasi one-dimensional structures which have interesting electronic properties on the basis of their edge geometries, and width. We studied the electronic properties of hydrogen and fluorine-terminated zigzag BNC nanoribbons (BNCNRs) using a first-principles based density functional theory approach. We considered BNCNRs that were composed of an equal number of C-C and B-N dimers; one of the edges ends with an N atom and opposite edge ends with a C atom. These two edge atoms are passivated by H or F atoms. Our results suggest that hydrogen-terminated BNCNRs (H-BNCNRs) and flourine-terminated BNCNRs (F-BNCNRs) have different electronic properties. H-BNCNRs exhibitmore » intrinsic half-metallic behavior while F-BNCNRs are indirect band gap semiconductors. Chemical functionalization of BNCNRs with H and F atoms show that BNCNRs have a diverse range of electronic properties.« less

A small terminal for satellite communication systems

NASA Technical Reports Server (NTRS)

Xiong, Fuqin; Wu, Dong; Jin, Min

1994-01-01

A small portable, low-cost satellite communications terminal system incorporating a modulator/demodulator and convolutional-Viterbi coder/decoder is described. Advances in signal processing and error-correction techniques in combination with higher power and higher frequencies aboard satellites allow for more efficient use of the space segment. This makes it possible to design small economical earth stations. The Advanced Communications Technology Satellite (ACTS) was chosen to test the system. ACTS, operating at the Ka band incorporates higher power, higher frequency, frequency and spatial reuse using spot beams and polarization.

Antenna Beam Pattern Characteristics of HAPS User Terminal

NASA Astrophysics Data System (ADS)

Ku, Bon-Jun; Oh, Dae Sub; Kim, Nam; Ahn, Do-Seob

High Altitude Platform Stations (HAPS) are recently considered as a green infrastructure to provide high speed multimedia services. The critical issue of HAPS is frequency sharing with satellite systems. Regulating antenna beam pattern using adaptive antenna schemes is one of means to facilitate the sharing with a space receiver for fixed satellite services on the uplink of a HAPS system operating in U bands. In this letter, we investigate antenna beam pattern characteristics of HAPS user terminals with various values of scan angles of main beam, null position angles, and null width.

Engineering the Band Gap States of the Rutile TiO2 (110) Surface by Modulating the Active Heteroatom.

PubMed

Yu, Yaoguang; Yang, Xu; Zhao, Yanling; Zhang, Xiangbin; An, Liang; Huang, Miaoyan; Chen, Gang; Zhang, Ruiqin

2018-04-19

Introducing band gap states to TiO 2 photocatalysts is an efficient strategy for expanding the range of accessible energy available in the solar spectrum. However, few approaches are able to introduce band gap states and improve photocatalytic performance simultaneously. Introducing band gap states by creating surface disorder can incapacitate reactivity where unambiguous adsorption sites are a prerequisite. An alternative method for introduction of band gap states is demonstrated in which selected heteroatoms are implanted at preferred surface sites. Theoretical prediction and experimental verification reveal that the implanted heteroatoms not only introduce band gap states without creating surface disorder, but also function as active sites for the Cr VI reduction reaction. This promising approach may be applicable to the surfaces of other solar harvesting materials where engineered band gap states could be used to tune photophysical and -catalytic properties. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dual self-organised shear banding behaviours and enhanced ductility in phase separating Zr-based bulk metallic glasses

NASA Astrophysics Data System (ADS)

Zhang, Z. Q.; Song, K. K.; Sun, B. A.; Wang, L.; Cui, W. C.; Qin, Y. S.; Han, X. L.; Xue, Q. S.; Peng, C. X.; Sarac, B.; Spieckermann, F.; Kaban, I.; Eckert, J.

2018-07-01

The multiplication and interaction of self-organised shear bands often transform to a stick-slip behaviour of a major shear band along the primary shear plane, and ultimately the major shear band becomes runaway and terminates the plasticity of bulk metallic glasses (BMGs). Here, we examined the deformation behaviours of the nanoscale phase-separating Zr65-xCu25Al10Fex (x = 5 and 7.5 at.%) BMGs. The formation of multi-step phase separation, being mainly governed by nucleation and growth, results in the microstructural inhomogeneity on a wide range of length-scales and leads to obviously macroscopic and repeatable ductility. The good deformability can be attributed to two mechanisms for stabilizing shear banding process, i.e. the mutual interaction of multiple shear bands away from the major shear band and the delaying slip-to-failure of dense fine shear bands around the major shear band, both of which show a self-organised criticality yet with different power-law exponents. The two mechanisms could come into effect in the intermediate (stable) and later plastic deformation regime, respectively. Our findings provide a possibility to enhance the shear banding stability over the whole plastic deformation through a proper design of microstructure heterogeneities.

Laminar patterns of geniculocortical projection in the cat.

PubMed

LeVay, S; Gilbert, C D

1976-08-20

The cortical afferents from individual laminae of the dorsal lateral geniculate nucleus (LGN) were studied using both light and electron microscope autoradiography. In area 17, the A geniculate laminae (A and A1) had two main bands of projection, one extending from the bottom of IVc to the deepest cells in layer III, and one in layer VI. The C geniculate laminae projected in two dense bands to the upper and lower borders of layer IV, thus bracketing the A laminae projection, though with some overlap. In addition, the C laminae projected to the superficial half of layer I, which the A laminae did not. Conversely, while the A laminae projected to layer VI, the C laminae did not. The two sets of laminae also showed differences in the areas to which they projected. The A geniculate laminae projected to areas 17 and 18, whereas the C geniculate laminae had a more extensive projection, including areas 17, 18, 19 and other areas on the suprasylvian gyrus. The laminar organization of the projection to area 18 was similar to that found in area 17. At the electron microscopic level the geniculate terminals were found to make Gray's type 1 synapses, for the most part onto dendritic spines. Labeled terminals were found in all the projection bands seen in the light microscope. The implications of these findings on the connectivity of cells in layer IV are discussed. The presence of labeled terminals in layer VI, which contains the cells of origin of the corticogeniculate pathway, suggests that the recurrent loop to the LGN is mediated monosynaptically. Finally, the afferents from each geniculate lamina were found to be segregated into patches, about 500 mum wide, which probably form the anatomical basis for ocular dominance columns.

Induced chirality of cage metal complexes switched by their supramolecular and covalent binding.

PubMed

Kovalska, Vladyslava B; Vakarov, Serhii V; Kuperman, Marina V; Losytskyy, Mykhaylo Y; Gumienna-Kontecka, Elzbieta; Voloshin, Yan Z; Varzatskii, Oleg A

2018-01-23

An ability of the ribbed-functionalized iron(ii) clathrochelates to induce a CD output in interactions with a protein, covalent bonding or supramolecular interactions with a low-molecular-weight chiral inductor, was discovered. The interactions of CD inactive, carboxyl-terminated iron(ii) clathrochelates with serum albumin induced their molecular asymmetry, causing an appearance of strong CD signals in the range of 350-600 nm, whereas methyl ester and amide clathrochelate derivatives remained almost CD inactive. The CD spectra of carboxyl-terminated clathrochelates on supramolecular interactions or covalent bonding with (R)-(+)-1-phenylethylamine gave a substantially lower CD output than with albumin, affected by both the solvent polarity and the isomerism of clathrochelate's ribbed substituents. In supramolecular assemblies, the bands were most intensive for ortho-substituted carboxyl-terminated clathrochelates. The ortho- and meta-phenylethylamide cage complexes in tetrachloromethane inverted the signs of their CD bands compared with those in acetonitrile. It was suggested that the tris-dioximate metal clathrochelates possess a Russian doll-like molecular system. Because of the distorted TP-TAP geometry, their coordination polyhedron had no inversion centre and possessed an inherent chirality together with the equiprobability of its left(Λ)- and right(Δ)-handle twists. The selective fixation of one of these C 3 -distorted conformations resulted in the appearance of the CD signal in the range of their visible metal-to-ligand charge transfer bands. Calculations by DFT methods were used to illustrate the possible conformations of the macrobicyclic molecules, as well as the intramolecular interactions between the cage framework and optically active distal substituents responsible for the chirality induction of the metal-centred coordination polyhedra.

14 CFR 272.12 - Termination.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS ESSENTIAL AIR SERVICE TO THE FREELY ASSOCIATED STATES § 272.12 Termination. These provisions shall terminate on October 1, 1998, unless the program of essential air service to the Federated States of...

Luminescent Dinuclear Ruthenium Terpyridine Complexes with a Bis-Phenylbenzimidazole Spacer.

PubMed

Mondal, Debiprasad; Biswas, Sourav; Paul, Animesh; Baitalik, Sujoy

2017-07-17

A conjugated bis-terpyridine bridging ligand, 2-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)phenyl)-6-(2-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)phenyl)-1H-benzo[d]imidazol-6-yl)-1H-benzo[d] imidazole (tpy-BPhBzimH 2 -tpy), was designed in this work by covalent coupling of 3,3'-diaminobenzidine and two 4'-(p-formylphenyl)-2,2':6',2″-terpyridine units to synthesize a new series of bimetallic Ru(II)-terpyridine light-harvesting complexes. Photophysical and electrochemical properties were modulated by the variation of the terminal ligands in the complexes. The new compounds were thoroughly characterized by 1 H NMR spectroscopy, high-resolution mass spectrometry, and elemental analysis. Absorption spectra of the complexes consist of very strong ligand-centered π-π* and n-π* transitions in the UV, metal-to-ligand, and intraligand charge transfer bands in the visible regions. Steady-state and time-resolved emission spectral measurements indicate that the complexes exhibit moderately intense luminescence at room temperature within the spectral domain of 653-687 nm having luminescence lifetimes in the range between 6.3 and 55.2 ns, depending upon terminal tridentate ligand and solvent. Variable-temperature luminescence measurements suggest substantial increase of the energy gap between luminescent 3 metal-to-ligand charge transfer state and nonluminescent 3 metal centered in the complexes compared to the parent [Ru(tpy) 2 ] 2+ . Each of the three bimetallic complexes exhibits only one reversible couple in the positive potential window with almost no detectable splitting corresponding to simultaneous oxidation of the two remote Ru centers. All the complexes possess a number of imidazole NH protons, which became sufficiently acidic upon metal ion coordination. By utilizing these NH protons, we thoroughly studied anion recognition properties of the complexes in pure organic as well as predominantly aqueous media through multiple optical channels and spectroscopic methods. Finally computation investigations employing density functional theory (DFT) and time-dependent DFT were done to examine the electronic structures of the complexes and accurate assignment of experimentally observed optical spectral bands.

DFT study of IR and Raman spectra of phosphotrihydrazone dendrimer with terminal phenolic groups

NASA Astrophysics Data System (ADS)

Furer, V. L.; Vandyukov, A. E.; Majoral, J. P.; Caminade, A. M.; Kovalenko, V. I.

2017-09-01

FT Raman and infrared spectra of phosphotrihydrazone (S)P[N(CH3)Ndbnd CHsbnd C6H4sbnd OH]3 (G0) were recorded. This compound is a zero generation phosphorus dendrimer with terminal phenolic groups. Optimal geometry and vibrational frequencies were calculated for G0 using the density functional theory (DFT). The molecule studied has C3 symmetry. In the molecule G0, each sbnd C6H4sbnd CHdbnd Nsbnd N(CH3)sbnd P arm is flat. Optimized geometric parameters correspond to experimental data. The core of the dendrimer manifests itself as a band at 647 cm-1 in the Raman spectrum of G0 related to Pdbnd S stretching. Phenolic end functions exhibit a well-defined band at 3374 cm-1 in the experimental IR spectrum of G0. The observed frequency of the OH stretching vibrations of the phenolic groups is lower than the theoretical value due to the intermolecular Osbnd H⋯O hydrogen bond. This hydrogen bond is also responsible for the higher intensity of this band in the experimental IR spectrum compared with the theoretical value. DFT calculations suggest full assignment of normal modes. Global and local descriptors characterize the reactivity of the core and end groups.

7 CFR 247.32 - Termination of agency participation.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 247.32 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE CHILD NUTRITION PROGRAMS COMMODITY SUPPLEMENTAL FOOD PROGRAM § 247.32 Termination... the reasons for the action, and the effective date. (2) Termination by State agency. The State agency...

7 CFR 247.32 - Termination of agency participation.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 247.32 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE CHILD NUTRITION PROGRAMS COMMODITY SUPPLEMENTAL FOOD PROGRAM § 247.32 Termination... the reasons for the action, and the effective date. (2) Termination by State agency. The State agency...

System services and architecture of the TMI satellite mobile data system

NASA Technical Reports Server (NTRS)

Gokhale, D.; Agarwal, A.; Guibord, A.

1993-01-01

The North American Mobile Satellite Service (MSS) system being developed by AMSC/TMI and scheduled to go into service in early 1995 will include the provision for real time packet switched services (mobile data service - MDS) and circuit switched services (mobile telephony service - MTS). These services will utilize geostationary satellites which provide access to mobile terminals (MT's) through L-band beams. The MDS system utilizes a star topology with a centralized data hub (DH) and will support a large number of mobile terminals. The DH, which accesses the satellite via a single Ku band beam, is responsible for satellite resource management, for providing mobile users with access to public and private data networks, and for comprehensive network management of the system. This paper describes the various MDS services available for the users, the ground segment elements involved in the provisioning of these services, and a summary description of the channel types, protocol architecture, and network management capabilities provided within the system.

Inward open characterization of EmrD transporter with molecular dynamics simulation

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

Tan, Xianwei; Wang, Boxiong, E-mail: boxiong_wang@yahoo.com

EmrD is a member of the multidrug resistance exporter family. Up to now, little is known about the structural dynamics that underline the function of the EmrD protein in inward-facing open state and how the EmrD transits from an occluded state to an inward open state. For the first time the article applied the AT simulation to investigate the membrane transporter protein EmrD, and described the dynamic features of the whole protein, the domain, the helices, and the amino acid residues during an inward-open process from its occluded state. The gradual inward-open process is different from the current model ofmore » rigid-body domain motion in alternating-access mechanism. Simulation results show that the EmrD inward-open conformational fluctuation propagates from a C-terminal domain to an N-terminal domain via the linker region during the transition from its occluded state. The conformational fluctuation of the C-terminal domain is larger than that of the N-terminal domain. In addition, it is observed that the helices exposed to the surrounding membrane show a higher level of flexibility than the other regions, and the protonated E227 plays a key role in the transition from the occluded to the open state. -- Highlights: •This study described the dynamic features of the whole EmrD protein, during an inward-open process from its occluded state. •The EmrD inward-open conformational fluctuation propagates from a C-terminal domain to an N-terminal domain via the linker region during the transition from its occluded state. •The conformational fluctuation of the C-terminal domain is larger than that of the N-terminal domain. •The protonated E227 plays a key role in the transition from the occluded to the open state.« less

Shuttle Ku-band bent-pipe implementation considerations. [for Space Shuttle digital communication systems

NASA Technical Reports Server (NTRS)

Batson, B. H.; Seyl, J. W.; Huth, G. K.

1977-01-01

This paper describes an approach for relay of data-modulated subcarriers from Shuttle payloads through the Shuttle Ku-band communications subsystem (and subsequently through a tracking and data relay satellite system to a ground terminal). The novelty is that a channel originally provided for baseband digital data is shown to be suitable for this purpose; the resulting transmission scheme is referred to as a narrowband bent-pipe scheme. Test results demonstrating the validity of the narrowband bent-pipe mode are presented, and limitations on system performance are described.

INMARSAT's personal communicator system

NASA Technical Reports Server (NTRS)

Hart, Nick; Haugli, HANS-C.; Poskett, Peter; Smith, K.

1993-01-01

Inmarsat has been providing near global mobile satellite communications since 1982 and Inmarsat terminals are currently being used in more than 130 countries. The terminals have been reduced in size and cost over the years and new technology has enabled the recent introduction of briefcase sized personal telephony terminals (Inmarsat-M). This trend continues and we are likely to see Inmarsat handheld terminals by the end of the decade. These terminals are called Inmarsat-P and this paper focuses on the various elements required to support a high quality service to handheld terminals. The main system elements are: the handheld terminals; the space segment with the associated orbits; and the gateways to terrestrial networks. It is both likely and desirable that personal handheld satellite communications will be offered by more than one system provider and this competition will ensure strong emphasis on service quality and cost of ownership. The handheld terminals also have to be attractive to a large number of potential users, and this means that the terminals must be small enough to fit in a pocket. Battery lifetime is another important consideration, and this coupled with radiation safety requirements limits the maximum radiated EIRP. The terminal G/T is mainly constrained by the gain of the omnidirectional antenna and the noise figure of the RF front end (including input losses). Inmarsat has examined, with the support of industry, a number of Geosynchronous (GSO), Medium Earth Orbit (MEO) and Low Earth Orbit (LEO) satellite options for the provision of a handheld mobile satellite service. This paper describes the key satellite and orbit parameters and tradeoffs which affect the overall quality of service and the space segment costing. The paper also stresses not only the importance of using and sharing the available mobile frequency band allocations efficiently, but also the key considerations affecting the choice of feeder link bands. The design of the gateways and the terrestrial network is critical to the overall viability of the service, and this paper also examines the key technical parameters associated with the Land Earth Stations (LES), which act as gateways into the Public Switched Telephone Network (PSTN). These not only include the design tradeoffs associated with the LES, but also the different terrestrial network interface options. The paper concludes with a brief description of the satellite propagation conditions associated with the use of handheld terminals. It describes how the handheld results in a number of propagation impairments which are not common to the previous measurements associated with vehicle mounted antennas. These measurements indicate that there is a complex tradeoff between link margin and the elevation angle to the satellite which has a significant impact on the space segment requirements and costing.

INMARSAT's personal communicator system

NASA Astrophysics Data System (ADS)

Hart, Nick; Haugli, Hans-C.; Poskett, Peter; Smith, K.

Inmarsat has been providing near global mobile satellite communications since 1982 and Inmarsat terminals are currently being used in more than 130 countries. The terminals have been reduced in size and cost over the years and new technology has enabled the recent introduction of briefcase sized personal telephony terminals (Inmarsat-M). This trend continues and we are likely to see Inmarsat handheld terminals by the end of the decade. These terminals are called Inmarsat-P and this paper focuses on the various elements required to support a high quality service to handheld terminals. The main system elements are: the handheld terminals; the space segment with the associated orbits; and the gateways to terrestrial networks. It is both likely and desirable that personal handheld satellite communications will be offered by more than one system provider and this competition will ensure strong emphasis on service quality and cost of ownership. The handheld terminals also have to be attractive to a large number of potential users, and this means that the terminals must be small enough to fit in a pocket. Battery lifetime is another important consideration, and this coupled with radiation safety requirements limits the maximum radiated EIRP. The terminal G/T is mainly constrained by the gain of the omnidirectional antenna and the noise figure of the RF front end (including input losses). Inmarsat has examined, with the support of industry, a number of Geosynchronous (GSO), Medium Earth Orbit (MEO) and Low Earth Orbit (LEO) satellite options for the provision of a handheld mobile satellite service. This paper describes the key satellite and orbit parameters and tradeoffs which affect the overall quality of service and the space segment costing. The paper also stresses not only the importance of using and sharing the available mobile frequency band allocations efficiently, but also the key considerations affecting the choice of feeder link bands. The design of the gateways and the terrestrial network is critical to the overall viability of the service, and this paper also examines the key technical parameters associated with the Land Earth Stations (LES), which act as gateways into the Public Switched Telephone Network (PSTN). These not only include the design tradeoffs associated with the LES, but also the different terrestrial network interface options. The paper concludes with a brief description of the satellite propagation conditions associated with the use of handheld terminals. It describes how the handheld results in a number of propagation impairments which are not common to the previous measurements associated with vehicle mounted antennas. These measurements indicate that there is a complex tradeoff between link margin and the elevation angle to the satellite which has a significant impact on the space segment requirements and costing.

Engineering of band gap states of amorphous SiZnSnO semiconductor as a function of Si doping concentration.

PubMed

Choi, Jun Young; Heo, Keun; Cho, Kyung-Sang; Hwang, Sung Woo; Kim, Sangsig; Lee, Sang Yeol

2016-11-04

We investigated the band gap of SiZnSnO (SZTO) with different Si contents. Band gap engineering of SZTO is explained by the evolution of the electronic structure, such as changes in the band edge states and band gap. Using ultraviolet photoelectron spectroscopy (UPS), it was verified that Si atoms can modify the band gap of SZTO thin films. Carrier generation originating from oxygen vacancies can modify the band-gap states of oxide films with the addition of Si. Since it is not easy to directly derive changes in the band gap states of amorphous oxide semiconductors, no reports of the relationship between the Fermi energy level of oxide semiconductor and the device stability of oxide thin film transistors (TFTs) have been presented. The addition of Si can reduce the total density of trap states and change the band-gap properties. When 0.5 wt% Si was used to fabricate SZTO TFTs, they showed superior stability under negative bias temperature stress. We derived the band gap and Fermi energy level directly using data from UPS, Kelvin probe, and high-resolution electron energy loss spectroscopy analyses.

Engineering of band gap states of amorphous SiZnSnO semiconductor as a function of Si doping concentration

PubMed Central

Choi, Jun Young; Heo, Keun; Cho, Kyung-Sang; Hwang, Sung Woo; Kim, Sangsig; Lee, Sang Yeol

2016-01-01

We investigated the band gap of SiZnSnO (SZTO) with different Si contents. Band gap engineering of SZTO is explained by the evolution of the electronic structure, such as changes in the band edge states and band gap. Using ultraviolet photoelectron spectroscopy (UPS), it was verified that Si atoms can modify the band gap of SZTO thin films. Carrier generation originating from oxygen vacancies can modify the band-gap states of oxide films with the addition of Si. Since it is not easy to directly derive changes in the band gap states of amorphous oxide semiconductors, no reports of the relationship between the Fermi energy level of oxide semiconductor and the device stability of oxide thin film transistors (TFTs) have been presented. The addition of Si can reduce the total density of trap states and change the band-gap properties. When 0.5 wt% Si was used to fabricate SZTO TFTs, they showed superior stability under negative bias temperature stress. We derived the band gap and Fermi energy level directly using data from UPS, Kelvin probe, and high-resolution electron energy loss spectroscopy analyses. PMID:27812035

E2/M1 mixing ratios in transitions from the gamma vibrational bands to the ground state rotational bands of 102, 104, 106, 108Mo, 108, 110, 112Ru, and 112, 114, 116Pd

NASA Astrophysics Data System (ADS)

Eldridge, J. M.; Fenker, B.; Hamilton, J. H.; Goodin, C.; Zachary, C. J.; Wang, E.; Ramayya, A. V.; Daniel, A. V.; Ter-Akopian, G. M.; Oganessian, Yu. Ts.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.

2018-02-01

E2/ M1 mixing ratios have been measured for transitions from states in the γ vibrational bands ( I+_{γ}) to states in the ground state bands (I+ or [I-1]+) of the neutron rich, even-even, deformed isotopes, 102, 104, 106, 108Mo, 108, 110, 112Ru, and 112, 114, 116Pd, including from states as high as 9+_{γ}. These measurements were done using the GAMMASPHERE detector array, which, at the time of the experiment, had 101 working HPGe detectors, arranged at 64 different angles. A 62 μCi source of 252Cf was placed inside GAMMASPHERE yielding 5.7× 10^{11} γ-γ-γ and higher coincidence events. The angular correlations between the transitions from the γ-bands to the ground bands, and the pure E2 transitions within the ground band were then measured. These angular correlations yielded the mixing ratios, demonstrating that these transitions are pure or nearly pure E2, in agreement with theory. In order to correct for possible attenuation due to the lifetime of the intermediate state in these correlations, the g-factors of the intermediate states needed to be known. Therefore, the g-factors of the 2+ states in the ground state band have been measured.

Observations of banding in first-year Arctic sea ice

NASA Astrophysics Data System (ADS)

Cole, David M.; Eicken, Hajo; Frey, Karoline; Shapiro, Lewis H.

2004-08-01

Horizontal banding features, alternating dark and bright horizontal bands apparent in ice cores and stratigraphic cross sections have long been observed in first-year sea ice and are frequently associated with bands of high and low brine or gas porosity. Observations on the land-fast ice near Barrow, Alaska, in recent years have revealed particularly striking banding patterns and prompted a study of their macroscopic and microscopic characteristics. The banding patterns are quantified from photographs of full-depth sections of the ice, and examples are presented from the Chukchi Sea and Elson Lagoon. Statistics on band spacing are presented, and the growth records for three seasons are employed to estimate their time of formation. These data provide insight into the periodicity of the underlying phenomena. Micrographs are used to examine the microstructural variations associated with various banding features and to quantify the geometry of the constituent brine inclusions associated with high- and low-porosity bands. The micrography revealed that the area fraction of brine inclusions varied by a factor of nearly 3 through the more pronounced high- and low-porosity bands. Vertical micrographs obtained shortly after the materials' removal from the ice sheet showed that significantly larger inclusions form abruptly at the start of the high-porosity bands and frequently terminate abruptly at the end of the band. Crystallographic observations indicated that the high-porosity bands supported the nucleation and growth of crystals having substantially different orientations from the very well aligned columnar structure that characterized the bulk of the sheet.

Nature of the valence band states in Bi2(Ca, Sr, La)3Cu2O8

NASA Astrophysics Data System (ADS)

Wells, B. O.; Lindberg, P. A. P.; Shen, Z.-X.; Dessau, D. S.; Spicer, W. E.; Lindau, I.; Mitzi, D. B.; Kapitulnik, A.

1990-01-01

We have used photoemission spectroscopy to examine the symmetry of the occupied states of the valence band for the La doped superconductor Bi2(Ca, Sr, La)3Cu2O8. While the oxygen states near the bottom of the 7 eV wide valence band exhibit predominantly O 2pz symmetry, the states at the top of the valence band extending to the Fermi level are found to have primarily O 2px and O 2py character. We have also examined anomalous intensity enhancements in the valence band feature for photon energies near 18 eV. These enhancements, which occur at photon energies ranging from 15.8 to 18.0 eV for the different valence band features, are not consistent with either simple final state effects or direct O2s transitions to unoccupied O2p states.

Valence-band states in Bi2(Ca,Sr,La)3Cu2O8

NASA Astrophysics Data System (ADS)

Wells, B. O.; Lindberg, P. A. P.; Shen, Z.-X.; Dessau, D. S.; Spicer, W. E.; Lindau, I.; Mitzi, D. B.; Kapitulnik, A.

1989-09-01

We have used photoemission spectroscopy to examine the symmetry of the occupied states of the valence band for the La-doped superconductor Bi2(Ca,Sr,La)3Cu2O8. While the oxygen states near the bottom of the 7-eV wide valence band exhibit predominantly O 2pz symmetry, the states at the top of the valence band extending to the Fermi level are found to have primarily O 2px and O 2py character. We have also examined anomalous intensity enhancements in the valence-band features for photon energies near 18 eV. These enhancements, which occur at photon energies ranging from 15.8 to 18.0 eV for the different valence-band features, are not consistent with either simple final-state effects or direct O 2s transitions to unoccupied O 2p states.

An odorant-binding protein as a new allergen from Siberian hamster (Phodopus sungorus).

PubMed

Torres, J A; Pastor-Vargas, C; de las Heras, M; Vivanco, F; Cuesta, Javier; Sastre, J

2012-01-01

A case of anaphylaxis following a bite from a Siberian hamster (SH; Phodopus sungorus) is described. Skin prick tests with hair, urine and salivary gland extracts from SH were positive, while the tests were negative for hair extracts from other rodents. IgE immunoblotting with the patient serum revealed 3 IgE-binding bands of about 18, 21 and 23 kDa. When the patient's serum was preincubated with rabbit, mouse and gerbil hair extracts, no inhibition of the 3 SH IgE-binding bands was demonstrated. Proteins extracted from the 3 bands were analyzed by N-terminal sequencing and matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry, and peptides were sequenced. IgE-binding bands were identified as being an odorant-binding protein belonging to the lipocalin family. Analysis of the 3 IgE-binding bands found in the hair, urine and salivary glands of SH showed a new allergenic protein lacking cross-reactivity with allergens from other rodents. The 3 bands likely correspond to isoforms of a single allergen. Copyright © 2011 S. Karger AG, Basel.

Quasiparticle breakdown in a quantum spin liquid.

PubMed

Stone, Matthew B; Zaliznyak, Igor A; Hong, Tao; Broholm, Collin L; Reich, Daniel H

2006-03-09

Much of modern condensed matter physics is understood in terms of elementary excitations, or quasiparticles--fundamental quanta of energy and momentum. Various strongly interacting atomic systems are successfully treated as a collection of quasiparticles with weak or no interactions. However, there are interesting limitations to this description: in some systems the very existence of quasiparticles cannot be taken for granted. Like unstable elementary particles, quasiparticles cannot survive beyond a threshold where certain decay channels become allowed by conservation laws; their spectrum terminates at this threshold. Such quasiparticle breakdown was first predicted for an exotic state of matter--super-fluid 4He at temperatures close to absolute zero, a quantum Bose liquid where zero-point atomic motion precludes crystallization. Here we show, using neutron scattering, that quasiparticle breakdown can also occur in a quantum magnet and, by implication, in other systems with Bose quasiparticles. We have measured spin excitations in a two-dimensional quantum magnet, piperazinium hexachlorodicuprate (PHCC), in which spin-1/2 copper ions form a non-magnetic quantum spin liquid, and find remarkable similarities with excitations in superfluid 4He. We observe a threshold momentum beyond which the quasiparticle peak merges with the two-quasiparticle continuum. It then acquires a finite energy width and becomes indistinguishable from a leading-edge singularity, so that excited states are no longer quasiparticles but occupy a wide band of energy. Our findings have important ramifications for understanding excitations with gapped spectra in many condensed matter systems, ranging from band insulators to high-transition-temperature superconductors.

Origins of Persistent Photoconductivity in GaAsN Alloys

NASA Astrophysics Data System (ADS)

Field, R. L., III; Wang, Y. Q.; Kurdak, C.; Goldman, R. S.

2013-03-01

In GaAs1-xNx alloys, we observe significant persistent photoconductivity (PPC) at cryogenic temperatures for x > 0.006, with the PPC strength increasing with increasing x and decreasing upon rapid-thermal annealing (RTA). Since the RTA-induced suppression is accompanied by a reduction of the interstitial N fraction, the N-induced donor state is likely associated with N pairs. PPC is attributed to the promotion of carriers from a ground N-pair state to the conduction band edge, inducing modifications in the N-pair molecular bond configuration. When illumination is terminated, an energy barrier hinders the return of carriers to the N-pair induced complex. With the addition of thermal energy, the original N-pair configuration is restored and the N-pair induced complex is then able to accept carriers. We use PPC at cryogenic temperatures to go through a metal-insulator transition in GaAsN by increasing the carrier density with illumination. For different illumination durations we determine the minimum metallic conductivity, giving us the critical carrier density, nc, at the transition point. We then determine the effective mass, m * , using the Mott criterion nc1 / 3 aH = 0.26 where aH = (4 πɛ h2) /(e2 m *) is the Bohr radius. We use PPC to induce a metal-insulator transition in GaAsN. We will discuss the effective mass as a function of N concentration and compare to the predictions of the band anticrossing model.

Expression, purification, and DNA-binding activity of the solubilized NtrC protein of Herbaspirillum seropedicae.

PubMed

Twerdochlib, Adriana L; Chubatsu, Leda S; Souza, Emanuel M; Pedrosa, Fábio O; Steffens, M Berenice R; Yates, M Geoffrey; Rigo, Liu U

2003-07-01

NtrC is a bacterial enhancer-binding protein (EBP) that activates transcription by the sigma54 RNA polymerase holoenzyme. NtrC has a three domain structure typical of EBP family. In Herbaspirillum seropedicae, an endophytic diazotroph, NtrC regulates several operons involved in nitrogen assimilation, including glnAntrBC. In order to over-express and purify the NtrC protein, DNA fragments containing the complete structural gene for the whole protein, and for the N-terminal+Central and Central+C-terminal domains were cloned into expression vectors. The NtrC and NtrC(N-terminal+Central) proteins were over-expressed as His-tag fusion proteins upon IPTG addition, solubilized using N-lauryl-sarcosyl and purified by metal affinity chromatography. The over-expressed His-tag-NtrC(Central+C-terminal) fusion protein was partially soluble and was also purified by affinity chromatography. DNA band-shift assays showed that the NtrC protein and the Central+C-terminal domains bound specifically to the H. seropedicae glnA promoter region. The C-terminal domain is presumably necessary for DNA-protein interaction and DNA-binding does not require a phosphorylated protein.

[Quantitative changes of main components of erythrocyte membranes which define architectonics of cells under pttg gene knockout].

PubMed

Kaniuka, O P; Filiak, Ie Z; Kulachkovs'kyĭ, O R; Osyp, Iu L; Sybirna, N O

2014-01-01

A pttg gene knockout affects the functional state of erythron in mice which could be associated with structural changes in the structure of erythrocyte membranes. The pttg gene knockout causes a significant modification of fatty acids composition of erythrocyte membrane lipids by reducing the content of palmitic acid and increasing of polyunsaturated fatty acids amount by 18%. Analyzing the erythrocyte surface architectonics of mice under pttg gene knockout, it was found that on the background of reduction of the functionally complete biconcave discs population one could observe an increase of the number of transformed cells at different degeneration stages. Researches have shown that in mice with a pttg gene knockout compared with a control group of animals cytoskeletal protein--beta-spectrin was reduced by 17.03%. However, there is a reduction of membrane protein band 3 by 33.04%, simultaneously the content of anion transport protein band 4.5 increases by 35.2% and protein band 4.2 by 32.1%. The lectin blot analysis has helped to reveal changes in the structure of the carbohydrate determinants of erythrocyte membrane glycoproteins under conditions of directed pttg gene inactivation, accompanied by changes in the type of communication, which joins the terminal residue in carbohydrate determinant of glycoproteins. Thus, a significant redistribution of protein and fatty acids contents in erythrocyte membranes that manifested in the increase of the deformed shape of red blood cells is observed underpttg gene knockout.

Calculating the optical properties of defects and surfaces in wide band gap materials

NASA Astrophysics Data System (ADS)

Deák, Peter

2018-04-01

The optical properties of a material critically depend on its defects, and understanding that requires substantial and accurate input from theory. This paper describes recent developments in the electronic structure theory of defects in wide band gap materials, where the standard local or semi-local approximations of density functional theory fail. The success of the HSE06 screened hybrid functional is analyzed in case of Group-IV semiconductors and TiO2, and shown that it is the consequence of error compensation between semi-local and non-local exchange, resulting in a proper derivative discontinuity (reproduction of the band gap) and a total energy which is a linear function of the fractional occupation numbers (removing most of the electron self-interaction). This allows the calculation of electronic transitions with accuracy unseen before, as demonstrated on the single-photon emitter NV(-) center in diamond and on polaronic states in TiO2. Having a reliable tool for electronic structure calculations, theory can contribute to the understanding of complicated cases of light-matter interaction. Two examples are considered here: surface termination effects on the blinking and bleaching of the light-emission of the NV(-) center in diamond, and on the efficiency of photocatalytic water-splitting by TiO2. Finally, an outlook is presented for the application of hybrid functionals in other materials, as, e.g., ZnO, Ga2O3 or CuGaS2.

First-principles study of the covalently functionalized graphene

NASA Astrophysics Data System (ADS)

Jha, Sanjiv Kumar

Theoretical investigations of nanoscale systems, such as functionalized graphene, present major challenges to conventional computational methods employed in quantum chemistry and solid state physics. The properties of graphene can be affected by chemical functionalization. The surface functionalization of graphene offers a promising way to increase the solubility and reactivity of graphene for use in nanocomposites and chemical sensors. Covalent functionalization is an efficient way to open band-gap in graphene for applications in nanoelectronics. We apply ab initio computational methods based on density functional theory to study the covalent functionalization of graphene with benzyne (C6H4), tetracyanoethylene oxide (TCNEO), and carboxyl (COOH) groups. Our calculations are carried out using the SIESTA and Quantum-ESPRESSO electronic structure codes combined with the generalized gradient (GGA) and local density approximations (LDA) for the exchange correlation functionals and norm-conserving Troullier-Martins pseudopotentials. Calculated binding energies, densities of states (DOS), band structures, and vibrational spectra of functionalized graphene are analyzed in comparison with the available experimental data. Our calculations show that the reactions of [2 + 2] and [2 + 4] cycloaddition of C6H4 to the surface of pristine graphene are exothermic, with binding energies of --0.73 eV and --0.58 eV, respectively. Calculated band structures indicate that the [2 + 2] and [2 + 4] attachments of benzyne results in opening small band gap in graphene. The study of graphene--TCNEO interactions suggests that the reaction of cycloaddition of TCNEO to the surface of pristine graphene is endothermic. On the other hand, the reaction of cycloaddition of TCNEO is found to be exothermic for the edge of an H-terminated graphene sheet. Simulated Raman and infrared spectra of graphene functionalized with TCNEO are consistent with experimental results. The Raman (non-resonant) and infrared (IR) spectra of graphene functionalized with carboxyl (COON) groups are studied in graphene with no surface defects, di-vacancies (DV), and Stone-Wales (SW) defects. Simulated Raman and IR spectra of carboxylated graphene are consistent with available experimental results. Computed vibrational spectra of carboxylated graphene show that the presence of point defects near the functionalization site affect the Raman and IR spectroscopic signatures of the functionalized graphene.

Preliminary Results of the NASA Beacon Receiver for Alphasat Aldo Paraboni TDP5 Propagation Experiment

NASA Technical Reports Server (NTRS)

Nessel, James; Morse, Jacquelynne; Zemba, Michael; Riva, Carlo; Luini, Lorenzo

2014-01-01

NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have initiated a joint propagation campaign within the framework of the Alphasat propagation experiment to characterize rain attenuation, scintillation, and gaseous absorption effects of the atmosphere in the 40 GHz band. NASA GRC has developed and installed a K/Q-band (20/40 GHz) beacon receiver at the POLIMI campus in Milan, Italy, which receives the 20/40 GHz signals broadcast from the Alphasat Aldo Paraboni TDP#5 beacon payload. The primary goal of these measurements is to develop a physical model to improve predictions of communications systems performance within the Q-band. Herein, we describe the design and preliminary performance of the NASA propagation terminal, which has been installed and operating in Milan since May 2014. The receiver is based upon a validated Fast Fourier Transform (FFT) I/Q digital design approach utilized in other operational NASA propagation terminals, but has been modified to employ power measurement via a frequency estimation technique and to coherently track and measure the amplitude of the 20/40 GHz beacon signals. The system consists of a 1.2-m K-band and a 0.6-m Qband Cassegrain reflector employing synchronous open-loop tracking to track the inclined orbit of the Alphasat satellite. An 8 Hz sampling rate is implemented to characterize scintillation effects, with a 1-Hz measurement bandwidth dynamic range of 45 dB. A weather station with an optical disdrometer is also installed to characterize rain drop size distribution for correlation with physical based models.

A comparison of 8.415-, 32.0- and 565646-GHz deep space telemetry links

NASA Technical Reports Server (NTRS)

Dickinson, R. M.

1985-01-01

An economic and performance comparison is made of spacecraft telecommunication links at 8.415, 32.0, and 565646 GHz (0.53-micron wavelength) for the return of 3.43 x 10 to the 11th power bits from a Saturn Orbiter/Titan Probe mission in year 2000. Technical performance and costs for both ends of the links are included. Spacecraft antenna or telescope efficiencies, pointing losses, ground-based or Earth-orbiting relay terminals efficiencies, noise temperatures, recurring and nonrecurring engineering, and maintenance and operations costs are modeled. Weather effects, dc-to-RF or laser power conversion efficiencies, gravity and other environment distortions gain reductions, and the cost of pointing and tracking are analyzed. The effort is focused primarily on the microwave frequency links. There are large uncertainties in the cost results, but conclusions indicate that for a mid-1990's launch, the Ka-band system is as cost effective as X-band. The Ka-band system has a data rate advantage as compared to the X-band system for the same dc power input to the spacecraft. The magnitude of the advantage is a complex function of the weather at the DSN stations and the elevation angle of the ground antenna. A simple numerical comparison of the advantage is difficult and curves are provided. The optical frequency link is more costly based on the launch-to-orbit costs for the orbiting terminal. A more detailed study of the optical system is recommended to quantify astrometric tracking benefits and improve the accuracy of the cost estimate.

Medicaid pregnancy termination funding and racial disparities in congenital anomaly-related infant deaths.

PubMed

Hutcheon, Jennifer A; Bodnar, Lisa M; Simhan, Hyagriv N

2015-01-01

To explore whether state restrictions on Medicaid funding for pregnancy termination of anomalous fetuses could be contributing to the black-white disparity in infant death resulting from congenital anomalies. Data on deaths resulting from anomalies were obtained from U.S. vital statistics records (1983-2004) and the Nationwide Inpatient Sample (2003-2007). We conducted an ecological study using Poisson and logistic regression to explore the association between state Medicaid funding for pregnancy terminations of anomalous fetuses and infant death resulting from anomalies by calendar time, race, and individual Medicaid status. Since 1983, a gap in anomaly-related infant death has developed between states without compared with those with Medicaid funding for pregnancy termination (rate ratio in 2004 1.21, 95% confidence interval [CI] 1.18-1.24; crude risks: 146.8 compared with 121.7/100,000). Blacks were significantly more likely than whites to be on Medicaid (60.2% compared with 29.2%) and to live in a state without Medicaid funding for pregnancy termination (65.8% compared with 59.6%). The increased risk of anomaly-related death associated with lack of state Medicaid funding for pregnancy termination was most pronounced among black women on Medicaid (relative risk 1.94, 95% CI 1.52-2.36; crude risks: 245.5 compared with 129.3/100,000). States without Medicaid funding for pregnancy termination of anomalous fetuses have higher rates of infant death resulting from anomalies than those with funding, and this difference is most pronounced among black women on Medicaid. Restrictions on Medicaid funding for termination of anomalous fetuses potentially could be contributing to the black-white disparity in anomaly-related infant death. II.

Chronic myelocytic leukaemia with unusual (27 years) complete remission terminating in acute undifferentiated leukaemia: a clinical and karyotypic study.

PubMed

Najean, Y; Miclea, M; Tanzer, J; Lessard, M; Sigaux, F

1991-07-01

A case of clinically typical CML (300 x 10(6)/l leukocytes, 400 x 10(6)/l platelets, splenomegaly) is presented. After complete remission induced by busulphan, no clinical or haematological abnormalities were observed for 27 years until the development of acute leukaemia (type M1), which was rapidly fatal after a brief chemotherapy-induced remission. The cytogenetic findings were also original: no chromosome Ph1 (during remission 3 years after the onset of the disease), no translocation (banding study 5 years later), and no bcr/abl rearrangement (during the terminal phase).

Reconfigurable electronics using conducting metal-organic frameworks

DOEpatents

Allendorf, Mark D.; Talin, Albert Alec; Leonard, Francois; Stavila, Vitalie

2017-07-18

A device including a porous metal organic framework (MOF) disposed between two terminals, the device including a first state wherein the MOF is infiltrated by a guest species to form an electrical path between the terminals and a second state wherein the electrical conductivity of the MOF is less than the electrical conductivity in the first state. A method including switching a porous metal organic framework (MOF) between two terminals from a first state wherein a metal site in the MOF is infiltrated by a guest species that is capable of charge transfer to a second state wherein the MOF is less electrically conductive than in the first state.

E 2 / M 1 Mixing Ratios in Transitions From the Gamma-Vibrational-Bands to the Ground-State-Rotational-Bands of 102 , 104 , 106 , 108Mo, 108 , 110 , 112Ru, and 112 , 114 , 116Pd

NASA Astrophysics Data System (ADS)

Eldridge, Jonathan M.; Fenker, B.; Goodin, C.; Hamilton, J. H.; Wang, E. H.; Ramayya, A. V.; Daniel, A. V.; Ter-Akopian, G. M.; Luo, Y. X.; Rasmussen, J. O.; Oganesson, Yu. Ts.; Zhu, S. J.

2017-09-01

E 2 / M 1 mixing ratios have been measured for transitions from states in the γ-vibrational-bands (Iγ+) to states in the ground-state-bands (Ig+ or [I- 1 ] g +) of the neutron rich, deformed isotopes, 102 , 104 , 106 , 108Mo, 108 , 110 , 112Ru, and 112 , 114 , 116Pd, including from states as high as 9γ+. These measurements were done using the GAMMASPHERE detector array, which, at the time of the experiment, had 101 working HPGe detectors, arranged at 64 different angles. A 62 μCi source of 252Cf was placed inside GAMMASPHERE yielding 5.7 ×1011 γ - γ - γ and higher coincidence events. The angular correlation between the transitions from the γ-band to the ground band, and the pure E2 transitions within the ground band were then measured. These angular correlations yielded the mixing ratios, demonstrating that these transitions are all pure or nearly pure E2, in agreement with theory. In order to correct for possible attenuation due to the lifetime of the intermediate state in these correlations, the g-factors of the intermediate states needed to be known. Therefore, the g-factors of the 2g+ states in the ground state band have been measured. Supported by the US Department of Energy; Grant No. DE-FG0588ER40407, Contract No. DE-AC03-76SF00098.

12 CFR 211.25 - Termination of offices of foreign banks.

Code of Federal Regulations, 2010 CFR

2010-01-01

... termination of an office or the requirement for prior notice of the closing of a branch, pursuant to section... least 30 days prior to terminating the activities of any office. Notice pursuant to this paragraph (f... office, state branch, state agency, or commercial lending company subsidiary if the Board finds that: (i...

Multi-scale Visualization of Remote Sensing and Topographic Data of the Amazon Rain Forest for Environmental Monitoring of the Petroleum Industry.

NASA Astrophysics Data System (ADS)

Fonseca, L.; Miranda, F. P.; Beisl, C. H.; Souza-Fonseca, J.

2002-12-01

PETROBRAS (the Brazilian national oil company) built a pipeline to transport crude oil from the Urucu River region to a terminal in the vicinities of Coari, a city located in the right margin of the Solimoes River. The oil is then shipped by tankers to another terminal in Manaus, capital city of the Amazonas state. At the city of Coari, changes in water level between dry and wet seasons reach up to 14 meters. This strong seasonal character of the Amazonian climate gives rise to four distinct scenarios in the annual hydrological cycle: low water, high water, receding water, and rising water. These scenarios constitute the main reference for the definition of oil spill response planning in the region, since flooded forests and flooded vegetation are the most sensitive fluvial environments to oil spills. This study focuses on improving information about oil spill environmental sensitivity in Western Amazon by using 3D visualization techniques to help the analysis and interpretation of remote sensing and digital topographic data, as follows: (a) 1995 low flood and 1996 high flood JERS-1 SAR mosaics, band LHH, 100m pixel; (b) 2000 low flood and 2001 high flood RADARSAT-1 W1 images, band CHH, 30m pixel; (c) 2002 high flood airborne SAR images from the SIVAM project (System for Surveillance of the Amazon), band LHH, 3m pixel and band XHH, 6m pixel; (d) GTOPO30 digital elevation model, 30' resolution; (e) Digital elevation model derived from topographic information acquired during seismic surveys, 25m resolution; (f) panoramic views obtained from low altitude helicopter flights. The methodology applied includes image processing, cartographic conversion and generation of value-added product using 3D visualization. A semivariogram textural classification was applied to the SAR images in order to identify areas of flooded forest and flooded vegetation. The digital elevation models were color shaded to highlight subtle topographic features. Both datasets were then converted to the same cartographic projection and inserted into the Fledermaus 3D visualization environment. 3D visualization proved to be an important aid in understanding the spatial distribution pattern of the environmentally sensitive vegetation cover. The dynamics of the hydrological cycle was depicted in a basin-wide scale, revealing new geomorphic information relevant to assess the environmental risk of oil spills. Results demonstrate that pipelines constitute an environmentally saver option for oil transportation in the region when compared to fluvial tanker routes.

UV/vis and NIR light-responsive spiropyran self-assembled monolayers.

PubMed

Ivashenko, Oleksii; van Herpt, Jochem T; Feringa, Ben L; Rudolf, Petra; Browne, Wesley R

2013-04-02

Self-assembled monolayers of a 6-nitro BIPS spiropyran (SP) modified with a disulfide-terminated aliphatic chain were prepared on polycrystalline gold surfaces and characterized by UV/vis absorption, surface-enhanced Raman scattering (SERS), and X-ray photoelectron spectroscopies (XPS). The SAMs obtained are composed of the ring-closed form (i.e., spiropyran) only. Irradiation with UV light results in conversion of the monolayer to the merocyanine form (MC), manifested in the appearance of an N(+) contribution in the N 1s region of the XPS spectrum of the SAMs, the characteristic absorption band of the MC form in the visible region at 555 nm, and the C-O stretching band in the SERS spectrum. Recovery of the initial state of the monolayer was observed both thermally and after irradiation with visible light. Several switching cycles were performed and monitored by SERS spectroscopy, demonstrating the stability of the SAMs during repeated switching between SP and MC states. A key finding in the present study is that ring-opening of the surface-immobilized spiropyrans can be induced by irradiation with continuous wave NIR (785 nm) light as well as by irradiation with UV light. We demonstrate that ring-opening by irradiation at 785 nm proceeds by a two-photon absorption pathway both in the SAMs and in the solid state. Hence, spiropyran SAMs on gold can undergo reversible photochemical switching from the SP to the MC form with both UV and NIR and the reverse reaction induced by irradiation with visible light or heating. Furthermore, the observation of NIR-induced switching with a continuous wave source holds important consequences in the study of photochromic switches on surfaces using SERS and emphasizes the importance of the use of multiple complementary techniques in characterizing photoresponsive SAMs.

- and Frequency-Domain Signatures of Velocity Changing Collisions in Sub-Doppler Saturation Spectra and Pressure Broadening

NASA Astrophysics Data System (ADS)

Hall, Gregory; Xu, Hong; Forthomme, Damien; Dagdigian, Paul; Sears, Trevor

2017-06-01

We have combined experimental and theoretical approaches to the competition between elastic and inelastic collisions of CN radicals with Ar, and how this competition influences time-resolved saturation spectra. Experimentally, we have measured transient, two-color sub-Doppler saturation spectra of CN radicals with an amplitude chopped saturation laser tuned to selected Doppler offsets within rotational lines of the A-X (2-0) band, while scanning a frequency modulated probe laser across the hyperfine-resolved saturation features of corresponding rotational lines of the A-X (1-0) band. A steady-state depletion spectrum includes off-resonant contributions ascribed to velocity diffusion, and the saturation recovery rates depend on the sub-Doppler detuning. The experimental results are compared with Monte Carlo solutions to the Boltzmann equation for the collisional evolution of the velocity distributions of CN radicals, combined with a pressure-dependent and speed-dependent lifetime broadening. Velocity changing collisions are included by appropriately sampling the energy resolved differential cross sections for elastic scattering of selected rotational states of CN (X). The velocity space diffusion of Doppler tagged molecules proceeds through a series of small-angle scattering events, eventually terminating in an inelastic collision that removes the molecule from the coherently driven ensemble of interest. Collision energy-dependent total cross sections and differential cross sections for elastic scattering of selected CN rotational states with Ar were computed with Hibridon quantum scattering calculations, and used for sampling in the Monte Carlo modeling. Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-SC0012704 with the U.S. Department of Energy, Office of Science, and supported by its Division of Chemical Sciences, Geosciences and Biosciences within the Office of Basic Energy Sciences.

45 CFR 1210.3-1 - Grounds for termination.

Code of Federal Regulations, 2012 CFR

2012-10-01

... SERVICE VISTA TRAINEE DESELECTION AND VOLUNTEER EARLY TERMINATION PROCEDURES VISTA Volunteer Early Termination § 1210.3-1 Grounds for termination. ACTION may terminate or suspend a Volunteer based on the Volunteer's conduct for the following reasons: (a) Conviction of any criminal offense under Federal, State...

45 CFR 1210.3-1 - Grounds for termination.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICE VISTA TRAINEE DESELECTION AND VOLUNTEER EARLY TERMINATION PROCEDURES VISTA Volunteer Early Termination § 1210.3-1 Grounds for termination. ACTION may terminate or suspend a Volunteer based on the Volunteer's conduct for the following reasons: (a) Conviction of any criminal offense under Federal, State...

45 CFR 1210.3-1 - Grounds for termination.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICE VISTA TRAINEE DESELECTION AND VOLUNTEER EARLY TERMINATION PROCEDURES VISTA Volunteer Early Termination § 1210.3-1 Grounds for termination. ACTION may terminate or suspend a Volunteer based on the Volunteer's conduct for the following reasons: (a) Conviction of any criminal offense under Federal, State...

45 CFR 1210.3-1 - Grounds for termination.

Code of Federal Regulations, 2014 CFR

2014-10-01

... SERVICE VISTA TRAINEE DESELECTION AND VOLUNTEER EARLY TERMINATION PROCEDURES VISTA Volunteer Early Termination § 1210.3-1 Grounds for termination. ACTION may terminate or suspend a Volunteer based on the Volunteer's conduct for the following reasons: (a) Conviction of any criminal offense under Federal, State...

45 CFR 1210.3-1 - Grounds for termination.

Code of Federal Regulations, 2013 CFR

2013-10-01

... SERVICE VISTA TRAINEE DESELECTION AND VOLUNTEER EARLY TERMINATION PROCEDURES VISTA Volunteer Early Termination § 1210.3-1 Grounds for termination. ACTION may terminate or suspend a Volunteer based on the Volunteer's conduct for the following reasons: (a) Conviction of any criminal offense under Federal, State...

The cytology, isozyme, HPLC fingerprint, and interspecific hybridization studies of genus epimedium (berberidaceae).

PubMed

Wang, Lin-Jiao; Sheng, Mao-Yin

2013-01-01

104 samples from 27 accessions belonging to 12 species of genus Epimedium were studied on the basis of cytology observation, POD (i.e., peroxide) isozyme, high performance liquid chromatography (i.e., HPLC) fingerprint, and interspecific hybridization. The cytology observation showed karyotypes of twelve species studied; all are 2A symmetry type of Stebbins standard and similar to each other, and except for karyotype of E. leptorrhizum which is 2n = 2x = 8m (2SAT) + 4sm, the rest are 2n = 2x = 6m (2SAT) + 6sm. Chromosomes C-banding of barrenwort species varies, with 15 to 22 bands, consisting of centromeric bands, intercalary bands, terminal bands, and middle satellite bands. Results of POD isozyme showed that the zymographs vary greatly and sixteen bands were detected in the eleven species, and each species has its own characteristic bands different from the others. Studies on the HPLC fingerprint showed that the HPLC fingerprint of different species has characteristic peaks, divided into two regions (retention time < 10 min and retention time > 10 min). Results of interspecific hybridization showed that crosses of any combination among seven species studied are successful and the rates of grain set vary greatly. Based on these results, the system and phylogeny of this genus were inferred.

The Cytology, Isozyme, HPLC Fingerprint, and Interspecific Hybridization Studies of Genus Epimedium (Berberidaceae)

PubMed Central

Wang, Lin-Jiao; Sheng, Mao-Yin

2013-01-01

104 samples from 27 accessions belonging to 12 species of genus Epimedium were studied on the basis of cytology observation, POD (i.e., peroxide) isozyme, high performance liquid chromatography (i.e., HPLC) fingerprint, and interspecific hybridization. The cytology observation showed karyotypes of twelve species studied; all are 2A symmetry type of Stebbins standard and similar to each other, and except for karyotype of E. leptorrhizum which is 2n = 2x = 8m (2SAT) + 4sm, the rest are 2n = 2x = 6m (2SAT) + 6sm. Chromosomes C-banding of barrenwort species varies, with 15 to 22 bands, consisting of centromeric bands, intercalary bands, terminal bands, and middle satellite bands. Results of POD isozyme showed that the zymographs vary greatly and sixteen bands were detected in the eleven species, and each species has its own characteristic bands different from the others. Studies on the HPLC fingerprint showed that the HPLC fingerprint of different species has characteristic peaks, divided into two regions (retention time < 10 min and retention time > 10 min). Results of interspecific hybridization showed that crosses of any combination among seven species studied are successful and the rates of grain set vary greatly. Based on these results, the system and phylogeny of this genus were inferred. PMID:24349794

Structures and electronic states of halogen-terminated graphene nano-flakes

NASA Astrophysics Data System (ADS)

Tachikawa, Hiroto; Iyama, Tetsuji

2015-12-01

Halogen-functionalized graphenes are utilized as electronic devices and energy materials. In the present paper, the effects of halogen-termination of graphene edge on the structures and electronic states of graphene flakes have been investigated by means of density functional theory (DFT) method. It was found that the ionization potential (Ip) and electron affinity of graphene (EA) are blue-shifted by the halogen termination, while the excitation energy is red-shifted. The drastic change showed a possibility as electronic devices such as field-effect transistors. The change of electronic states caused by the halogen termination of graphene edge was discussed on the basis of the theoretical results.

Detection of prosecretory mitogen lacritin in nonprimate tears primarily as a C-terminal-like fragment.

PubMed

Laurie, Diane E; Splan, Rebecca K; Green, Kari; Still, Katherine M; McKown, Robert L; Laurie, Gordon W

2012-09-12

Lacritin is a human tear glycoprotein that promotes basal tear protein secretion in cultured rat lacrimal acinar cells and proliferation of subconfluent human corneal epithelial cells. When topically added to rabbit eyes, lacritin promotes basal tearing. Despite these activities on several species, lacritin's presence in nonprimate tears or other tissues has not been explored. Here we probed for lacritin in normal horse tears. Sequences were collected from the Ensembl genomic alignment of human LACRT gene with high-quality draft horse genome (EquCab2.0) and analyzed. Normal horse tears were collected and assayed by Western blotting, ELISA, and mass spectrometry. Newly generated rabbit antibodies, respectively, against N- and C-terminal regions of human lacritin were employed. Identity was 75% and 45%, respectively, at nucleotide and protein levels. Structural features were conserved, including a C-terminal amphipathic α-helix. Anti-C-terminal antibodies strongly detected a ∼13 kDa band in horse tears that was validated by mass spectrometry. In human tears, the same antibody detected uncleaved lacritin (∼24 kDa) strongly and C-terminal fragments of ∼13 and ∼11 kDa weakly. Anti-N-terminal antibodies were slightly reactive with a ∼24 kDa horse antigen and showed no reaction with the anti-C-terminal-reactive ∼13 kDa species. Similar respective levels of horse C-terminal versus N-terminal immunoreactivity were apparent by ELISA. Lacritin is present in horse tears, largely as a C-terminal fragment homologous to the mitogenic and bactericidal region in human lacritin, suggesting potential benefit in corneal wound repair.

Spectroscopic and molecular structure investigation of the phosphorus-containing G‧2 dendrimer with terminal aldehyde groups using DFT method

NASA Astrophysics Data System (ADS)

Furer, V. L.; Vandyukov, A. E.; Majoral, J. P.; Caminade, A. M.; Kovalenko, V. I.

2015-02-01

The FTIR and FT Raman spectra of the second generation dendrimer G‧2 built from thiophosphoryl core with terminal aldehyde groups have been recorded. The structural optimization and normal mode analysis were performed for model compound C, consisting of thiophosphoryl core, one branch with three repeated units, and four 4-oxybenzaldehyde terminal groups on the basis of the density functional theory (DFT) at the PBE/TZ2P level. The vibrational frequencies, infrared and Raman intensities for the t,g,g- and t,-g,g-conformers of the terminal groups were calculated. The t,g,g-conformer is 2.0 kcal/mol less stable compared to t,-g,g-conformer. A reliable assignment of the fundamental bands observed in the experimental IR and Raman spectra of dendrimer was achieved. For the low generations (G‧1 to G‧3) the disk form of studied dendrimer molecules is the most probable. For higher generations, the shape of dendrimer molecules will be that of a cauliflower.

Morphology and innervation of the vestibular lagena in pigeons

PubMed Central

Mridha, Zakir; Wu, Le-Qing; Dickman, J. David

2012-01-01

The morphological characteristics of the pigeon lagena were examined using histology, scanning electron microscopy, and biotinylated dextran amine (BDA) neural tracers. The lagena epithelium was observed to lie partially in a parasagittal plane, but was also U-shaped with orthogonal (lateral) directed tips. Hair cell planar polarities were oriented away from a central reversal line that ran nearly the length of the epithelium. Similar to the vertebrate utricle and saccule, three afferent classes were observed based upon their terminal innervation pattern, which include calyx, dimorph, and bouton fibers. Calyx and dimorph afferents innervated the striola region of the lagena, while bouton afferents innervated the extrastriola and a small region of the central striola known as the type II band. Calyx units had large calyceal terminal structures that innervated only type I hair cells. Dimorph afferents innervated both type I and II hair cells, with calyx and bouton terminals. Bouton afferents had the largest most complex innervation patterns and the greatest terminal areas contacting many hair cells. PMID:22387112

SEARCH FOR TWO-PHONON OCTUPOLE VIBRATIONAL BANDS IN 88, 89, 92, 93, 94, 96Sr AND 95, 96, 97, 98Zr

NASA Astrophysics Data System (ADS)

Hwang, J. K.; Hamilton, J. H.; Ramayya, A. V.; Brewer, N. T.; Wang, E. H.; Luo, Y. X.; Zhu, S. J.

2012-09-01

Several new gamma transitions were identified in 94Sr, 93Sr, 92Sr, 96Zr and 97Zr from the spontaneous fission of 252Cf. Excited states in 88, 89, 92, 94, 96Sr and 95, 96, 97, 98Zr were reanalyzed and reorganized to propose the new two-phonon octupole vibrational states and bands. The spin and parity of 6+ are assigned to a 4034.5 keV state in 94Sr and 3576.4 keV state in 98Zr. These states are proposed as the two-phonon octupole vibrational states along with the 6+ states at 3483.4 keV in 96Zr, at 3786.0 keV in 92Sr and 3604.2 keV in 96Sr. The positive parity bands in 88, 94, 96Sr and 96, 98Zr are the first two-phonon octupole vibrational bands based on a 6+ state assigned in spherical nuclei. It is thought that in 94, 96Sr and 96, 98Zr a 3- octupole vibrational phonon is weakly coupled to an one-phonon octupole vibrational band to make the two-phonon octupole vibrational band. Also, the high spin states of odd-A95Zr and 97Zr are interpreted to be generated by the neutron 2d5/2 hole and neutron 1g7/2 particle, respectively, weakly coupled to one- and two-phonon octupole vibrational bands of 96Zr. The high spin states of odd-A87Sr are interpreted to be caused by the neutron 1g9/2 hole weakly coupled to 3- and 5- states of 88Sr. New one- and two-POV bands in 95, 97Zr and 87, 89Sr are proposed, for the first time, in the present work.

Controllable spin-charge transport in strained graphene nanoribbon devices

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

Diniz, Ginetom S., E-mail: ginetom@gmail.com; Guassi, Marcos R.; Qu, Fanyao

2014-09-21

We theoretically investigate the spin-charge transport in two-terminal device of graphene nanoribbons in the presence of a uniform uniaxial strain, spin-orbit coupling, exchange field, and smooth staggered potential. We show that the direction of applied strain can efficiently tune strain-strength induced oscillation of band-gap of armchair graphene nanoribbon (AGNR). It is also found that electronic conductance in both AGNR and zigzag graphene nanoribbon (ZGNR) oscillates with Rashba spin-orbit coupling akin to the Datta-Das field effect transistor. Two distinct strain response regimes of electronic conductance as function of spin-orbit couplings magnitude are found. In the regime of small strain, conductance ofmore » ZGNR presents stronger strain dependence along the longitudinal direction of strain. Whereas for high values of strain shows larger effect for the transversal direction. Furthermore, the local density of states shows that depending on the smoothness of the staggered potential, the edge states of AGNR can either emerge or be suppressed. These emerging states can be determined experimentally by either spatially scanning tunneling microscope or by scanning tunneling spectroscopy. Our findings open up new paradigms of manipulation and control of strained graphene based nanostructure for application on novel topological quantum devices.« less

Nickel: The time-reversal symmetry conserving partner of iron on a chalcogenide topological insulator

NASA Astrophysics Data System (ADS)

Vondráček, M.; Cornils, L.; Minár, J.; Warmuth, J.; Michiardi, M.; Piamonteze, C.; Barreto, L.; Miwa, J. A.; Bianchi, M.; Hofmann, Ph.; Zhou, L.; Kamlapure, A.; Khajetoorians, A. A.; Wiesendanger, R.; Mi, J.-L.; Iversen, B.-B.; Mankovsky, S.; Borek, St.; Ebert, H.; Schüler, M.; Wehling, T.; Wiebe, J.; Honolka, J.

2016-10-01

We report on the quenching of single Ni adatom moments on Te-terminated Bi2Te2Se and Bi2Te3 topological insulator surfaces. The effect is noted as a missing x-ray magnetic circular dichroism for resonant L3 ,2 transitions into partially filled Ni 3 d states of theory-derived occupancy nd=9.2 . On the basis of a comparative study of Ni and Fe using scanning tunneling microscopy and ab initio calculations, we are able to relate the element specific moment formation to a local Stoner criterion. Our theory shows that while Fe adatoms form large spin moments of ms=2.54 μB with out-of-plane anisotropy due to a sufficiently large density of states at the Fermi energy, Ni remains well below an effective Stoner threshold for local moment formation. With the Fermi level remaining in the bulk band gap after adatom deposition, nonmagnetic Ni and preferentially out-of-plane oriented magnetic Fe with similar structural properties on Bi2Te2Se surfaces constitute a perfect platform to study the off-on effects of time-reversal symmetry breaking on topological surface states.

78 FR 16325 - Self-Regulatory Organizations; National Stock Exchange, Inc.; Notice of Filing and Immediate...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-14

...) Price Band.\\15\\ Trading for an NMS stock exits in a Limit State if, within 15 seconds of entering the...) Price Band and the NMS Stock is not in a Limit State. For example, assume the Lower Price Band for an NMS Stock is $9.50 and the Upper Price Band is $10.50, such NMS stock would be in a Straddle State if...

Unconventional superconductivity and surface pairing symmetry in half-Heusler compounds

NASA Astrophysics Data System (ADS)

Wang, Qing-Ze; Yu, Jiabin; Liu, Chao-Xing

2018-06-01

Signatures of nodal line/point superconductivity [Kim et al., Sci. Adv. 4, eaao4513 (2018), 10.1126/sciadv.aao4513; Brydon et al., Phys. Rev. Lett. 116, 177001 (2016), 10.1103/PhysRevLett.116.177001] have been observed in half-Heusler compounds, such as LnPtBi (Ln = Y, Lu). Topologically nontrivial band structures, as well as topological surface states, have also been confirmed by angular-resolved photoemission spectroscopy in these compounds [Liu et al., Nat. Commun. 7, 12924 (2016), 10.1038/ncomms12924]. In this paper, we present a systematical classification of possible gap functions of bulk states and surface states in half-Heusler compounds and the corresponding topological properties based on the representations of crystalline symmetry group. Different from all the previous studies based on the four band Luttinger model, our study starts with the six-band Kane model, which involves both four p-orbital type of Γ8 bands and two s-orbital type of Γ6 bands. Although the Γ6 bands are away from the Fermi energy, our results reveal the importance of topological surface states, which originate from the band inversion between Γ6 and Γ8 bands, in determining surface properties of these compounds in the superconducting regime by combining topological bulk state picture and nontrivial surface state picture.

24 CFR 882.511 - Lease and termination of tenancy.

Code of Federal Regulations, 2011 CFR

2011-04-01

... of applicable Federal, State or local law. (3) Other good cause. (d) Notice of termination of tenancy... based on other good cause, the date of termination must be no earlier than 30 days after the notice is... is issued pursuant to State or local law or is common practice in the locality and which satisfies...

Monolithic FET structures for high-power control component applications

NASA Astrophysics Data System (ADS)

Shifrin, Mitchell B.; Katzin, Peter J.; Ayasli, Yalcin

1989-12-01

A monolithic FET switch is described that can be integrated with other monolithic functions or used as a discrete component in a microwave integrated circuit structure. This device increases the power-handling capability of the conventional single FET switch by an order of magnitude. It does this by overcoming the breakdown voltage limitation of the FET device. The design, fabrication, and performance of two high-power control components using these circuits are described as examples of the implementation of this technology. They are an L-band terminated single-pole, single-throw (SPST) switch and an L-band limiter).

Design analysis tracking and data relay satellite simulation system

NASA Technical Reports Server (NTRS)

1974-01-01

The design and development of the equipment necessary to simulate the S-band multiple access link between user spacecraft, the Tracking and Data Relay Satellite, and a ground control terminal are discussed. The core of the S-band multiple access concept is the use of an Adaptive Ground Implemented Phased Array. The array contains thirty channels and provides the multiplexing and demultiplexing equipment required to demonstrate the ground implemented beam forming feature. The system provided will make it possible to demonstrate the performance of a desired user and ten interfering sources attempting to pass data through the multiple access system.

Suppression of proliferation and neurite extension of human neuroblastoma SH-SY5Y cells on immobilized Psathyrella velutina lectin.

PubMed

Kitamura, Noriaki; Ikekita, Masahiko; Hayakawa, Satoru; Funahashi, Hisayuki; Furukawa, Kiyoshi

2004-02-01

Glycoproteins from mammalian brain tissues contain unique N-linked oligosaccharides terminating with beta-N-acetylglucosamine residues. Lectin blot analysis of membrane glycoprotein samples from human neuroblastoma SH-SY5Y cells showed that several protein bands bind to Psathylera velutina lectin (PVL), which interacts with beta-N-acetylglucosamine-terminating oligosaccharides. No lectin positive bands were detected by digestion with jack bean beta-N-acetyl-hexosaminidase or N-glycanase before incubation with the lectin, indicating that the cells contain beta-N-acetylglucosamine-terminating N-linked oligosaccharides. When cells were cultured in dishes with different concentrations of PVL, the cell proliferation was inhibited in a dose-dependent manner. Similarly, the neurite extension, which was stimulated with nerve growth factor, was also inhibited in a manner dependent on the lectin dose. Cell proliferation and neurite extension were recovered by the addition of 10 mM N-acetylglucosamine into the medium. Immunoblot analysis of the activation of mitogen-activated protein (MAP) kinases and protein kinase C revealed that phosphorylation of 42-kDa and 44-kDa MAP kinases and 80-kDa protein kinase C are inhibited when SH-SY5Y cells are cultured in PVL-coated dishes, but are restored by the addition of the haptenic sugar into the medium, indicating that MAP kinase and protein kinase C pathways are inhibited by interaction with immobilized PVL. These results indicate that beta-N-acetylglucosamine-terminating N-linked oligosaccharides expressed on neural cells can induce intracellular signals upon binding to extracellular receptors, and are important for growth regulation of neural cells. Copyright 2003 Wiley-Liss, Inc.

Orientation of Myosin Binding Protein C in the Cardiac Muscle Sarcomere Determined by Domain-Specific Immuno-EM

PubMed Central

Lee, Kyounghwan; Harris, Samantha P.; Sadayappan, Sakthivel; Craig, Roger

2014-01-01

Myosin binding protein-C is a thick filament protein of vertebrate striated muscle. The cardiac isoform (cMyBP-C) is essential for normal cardiac function, and mutations in cMyBP-C cause cardiac muscle disease. The rod-shaped molecule is composed primarily of 11 immunoglobulin- or fibronectin-like domains, and is located at 9 sites, 43 nm apart, in each half of the A-band. To understand how cMyBP-C functions, it is important to know its structural organization in the sarcomere, as this will affect its ability to interact with other sarcomeric proteins. Several models have been proposed, in which cMyBP-C wraps around, extends radially from, or runs axially along the thick filament. Our goal was to define cMyBP-C orientation by determining the relative axial positions of different cMyBP-C domains. Immuno-electron microscopy was performed using mouse cardiac myofibrils labeled with antibodies specific to the N- and C-terminal domains and to the middle of cMyBP-C. Antibodies to all regions of the molecule, except the C-terminus, labeled at the same nine axial positions in each half A-band, consistent with a circumferential and/or radial rather than an axial orientation of the bulk of the molecule. The C-terminal antibody stripes were slightly displaced axially, demonstrating an axial orientation of the C-terminal 3 domains, with the C-terminus closer to the M-line. These results, combined with previous studies, suggest that the C-terminal domains of cMyBP-C run along the thick filament surface, while the N-terminus extends towards neighboring thin filaments. This organization provides a structural framework for understanding cMyBP-C’s modulation of cardiac muscle contraction. PMID:25451032

ACTS mobile SATCOM experiments

NASA Technical Reports Server (NTRS)

Abbe, Brian S.; Frye, Robert E.; Jedrey, Thomas C.

1993-01-01

Over the last decade, the demand for reliable mobile satellite communications (satcom) for voice, data, and video applications has increased dramatically. As consumer demand grows, the current spectrum allocation at L-band could become saturated. For this reason, NASA and the Jet Propulsion Laboratory are developing the Advanced Communications Technology Satellites (ACTS) mobile terminal (AMT) and are evaluating the feasibility of K/Ka-band (20/30 GHz) mobile satcom to meet these growing needs. U.S. industry and government, acting as co-partners, will evaluate K/Ka-band mobile satcom and develop new technologies by conducting a series of applications-oriented experiments. The ACTS and the AMT testbed will be used to conduct these mobile satcom experiments. The goals of the ACTS Mobile Experiments Program and the individual experiment configurations and objectives are further presented.

Karyotypic analysis of the cotton boll weevil, Anthonomus grandis Boheman.

PubMed

McNally, L R; Beck, M L; Biggers, C J

2000-01-01

The diploid chromosome number of the cotton boll weevil, Anthonomus grandis Boheman, is 44. Both C- and N-banding techniques of mitotic cells demonstrated constitutive heterochromatin in the p arm of the eight largest chromosomes, the p arm of the X chromosome, and the centromeric region of autosomal groups A-D. Neither the y nor the group E autosomes appeared to contain constitutive heterochromatin. Supernumerary chromosomes were not found in the boll weevil. Restriction endonuclease banding of primary spermatocytes revealed a rod-shaped Xy tetrad in which the X and y were terminally associated. The p arm of the large, submetacentric X was C-band positive. While two of the autosomal tetrads were typically ring-shaped in primary spermatocytes, the remaining 19 autosomal tetrads were rod-shaped.

Ultra-Wideband Massive MIMO Communications Using Multi-mode Antennas

NASA Astrophysics Data System (ADS)

Hoeher, P. A.; Manteuffel, D.; Doose, N.; Peitzmeier, N.

2017-09-01

An ultra-wideband system design is presented which supports wireless internet access and similar short-range applications with data rates of the order of 100 Gbps. Unlike concurrent work exploring the 60 GHz regime and beyond for this purpose, our focus is on the 6.0 -8.5 GHz frequency band. Hence, a bandwidth efficiency of about 50 bps/Hz is necessary. This sophisticated goal is targeted by employing two key enabling techniques: massive MIMO communications in conjunction with multi-mode antennas. This concept is suitable both for small-scale terminals like smartphones, as well as for powerful access points. Compared to millimeter wave and THz band communications, the 6.0 -8.5 GHz frequency band offers more robustness in NLOS scenarios and is more mature with respect to system components.

Development of the network architecture of the Canadian MSAT system

NASA Technical Reports Server (NTRS)

Davies, N. George; Shoamanesh, Alireza; Leung, Victor C. M.

1988-01-01

A description is given of the present concept for the Canadian Mobile Satellite (MSAT) System and the development of the network architecture which will accommodate the planned family of three categories of service: a mobile radio service (MRS), a mobile telephone service (MTS), and a mobile data service (MDS). The MSAT satellite will have cross-strapped L-band and Ku-band transponders to provide communications services between L-band mobile terminals and fixed base stations supporting dispatcher-type MRS, gateway stations supporting MTS interconnections to the public telephone network, data hub stations supporting the MDS, and the network control center. The currently perceived centralized architecture with demand assignment multiple access for the circuit switched MRS, MTS and permanently assigned channels for the packet switched MDS is discussed.

Development of the network architecture of the Canadian MSAT system

NASA Astrophysics Data System (ADS)

Davies, N. George; Shoamanesh, Alireza; Leung, Victor C. M.

1988-05-01

A description is given of the present concept for the Canadian Mobile Satellite (MSAT) System and the development of the network architecture which will accommodate the planned family of three categories of service: a mobile radio service (MRS), a mobile telephone service (MTS), and a mobile data service (MDS). The MSAT satellite will have cross-strapped L-band and Ku-band transponders to provide communications services between L-band mobile terminals and fixed base stations supporting dispatcher-type MRS, gateway stations supporting MTS interconnections to the public telephone network, data hub stations supporting the MDS, and the network control center. The currently perceived centralized architecture with demand assignment multiple access for the circuit switched MRS, MTS and permanently assigned channels for the packet switched MDS is discussed.

High power diode lasers for solid-state laser pumps

NASA Technical Reports Server (NTRS)

Linden, Kurt J.; Mcdonnell, Patrick N.

1994-01-01

The development and commercial application of high power diode laser arrays for use as solid-state laser pumps is described. Such solid-state laser pumps are significantly more efficient and reliable than conventional flash-lamps. This paper describes the design and fabrication of diode lasers emitting in the 780 - 900 nm spectral region, and discusses their performance and reliability. Typical measured performance parameters include electrical-to-optical power conversion efficiencies of 50 percent, narrow-band spectral emission of 2 to 3 nm FWHM, pulsed output power levels of 50 watts/bar with reliability values of over 2 billion shots to date (tests to be terminated after 10 billion shots), and reliable operation to pulse lengths of 1 ms. Pulse lengths up to 5 ms have been demonstrated at derated power levels, and CW performance at various power levels has been evaluated in a 'bar-in-groove' laser package. These high-power 1-cm stacked-bar arrays are now being manufactured for OEM use. Individual diode laser bars, ready for package-mounting by OEM customers, are being sold as commodity items. Commercial and medical applications of these laser arrays include solid-state laser pumping for metal-working, cutting, industrial measurement and control, ranging, wind-shear/atmospheric turbulence detection, X-ray generation, materials surface cleaning, microsurgery, ophthalmology, dermatology, and dental procedures.

Engineering electronic states of periodic and quasiperiodic chains by buckling

NASA Astrophysics Data System (ADS)

Mukherjee, Amrita; Nandy, Atanu; Chakrabarti, Arunava

2017-07-01

The spectrum of spinless, non-interacting electrons on a linear chain that is buckled in a non-uniform, quasiperiodic manner is investigated within a tight binding formalism. We have addressed two specific cases, viz., a perfectly periodic chain wrinkled in a quasiperiodic Fibonacci pattern, and a quasiperiodic Fibonacci chain, where the buckling also takes place in a Fibonacci pattern. The buckling brings distant neighbors in the parent chain to close proximity, which is simulated by a tunnel hopping amplitude. It is seen that, in the perfectly ordered case, increasing the strength of the tunnel hopping (that is, bending the segments more) absolutely continuous density of states is retained towards the edges of the band, while the central portion becomes fragmented and host subbands of narrowing widths containing extended, current carrying states, and multiple isolated bound states formed as a result of the bending. A switching ;on; and ;off; of the electronic transmission can thus be engineered by buckling. On the other hand, in the second example of a quasiperiodic Fibonacci chain, imparting a quasiperiodic buckling is found to generate continuous subband(s) destroying the usual multifractality of the energy spectrum. We present exact results based on a real space renormalization group analysis, that is corroborated by explicit calculation of the two terminal electronic transport.

Strain-Engineering of Graphene Based Topological Quantum Devices

NASA Astrophysics Data System (ADS)

Diniz, Ginetom S.; Guassi, Marcos R.; Qu, Fanyao

2015-03-01

We have investigated the spin-charge transport in quantum devices based on graphene nanoribbons (GNR). Our calculation is based on the surface Green's function technique, considering the presence of an uniform uniaxial strain, spin-orbit interactions (SOIs), exchange field and a smooth staggered potential. We propose the use of uniaxial strain as an efficient mechanism to tune the conductance profiles of GNR with different edge terminations. Our results show that distinct behaviors can be achieved: for armchair GNR there is a complete suppression of the conductance close to the Fermi level with the formation of a band gap that depends on the direction and strength of the strain deformation, while for zigzag GNR there is only a small conductance suppression. We also discuss the effects of SOIs and the appearance of spin-resolved conductance oscillations, and the local density of states of these GNR devices in the quantum anomalous Hall regime. Furthermore, we demonstrate that the local density of states show that depending on the smoothness of the staggered potential, the edge states of AGNR can either emerge or be suppressed. These emerging states can be probed by scanning tunneling microscope. Our findings can be potentially used in novel GNR based topological quantum devices. Supported by FAP-DF, CNPq and CAPES.

43 CFR 429.28 - What terms and conditions apply to all use authorizations?

Code of Federal Regulations, 2010 CFR

2010-10-01

... United States, terminate any use authorization if the grantee fails to comply with all applicable Federal... termination activities: (1) The grantee agrees to indemnify the United States for, and hold the United States..., maintenance, supervision, examination, inspection, or other activities of the grantee. (2) The United States...

Diamond /111/ studied by electron energy loss spectroscopy in the characteristic loss region

NASA Technical Reports Server (NTRS)

Pepper, S. V.

1982-01-01

Unoccupied surface states on diamond (111) annealed at greater than 900 C are studied by electron energy loss spectroscopy with valence band excitation. A feature found at 2.1 eV loss energy is attributed to an excitation from occupied surface states into unoccupied surface states of energy within the bulk band gap. A surface band gap of approximately 1 eV is estimated. This result supports a previous suggestion for unoccupied band gap states based on core level energy loss spectroscopy. Using the valence band excitation energy loss spectrosocpy, it is also suggested that hydrogen is removed from the as-polished diamond surface by a Menzel-Gomer-Redhead mechanism.

Warm-Up Activities of Middle and High School Band Directors Participating in State-Level Concert Band Assessments

ERIC Educational Resources Information Center

Ward, Justin P.; Hancock, Carl B.

2016-01-01

The purpose of this study was to examine the warm-ups chosen by concert band directors participating in state-level performance assessments. We observed 29 middle and high school bands and coded the frequency and duration of warm-up activities and behaviors. Results indicated that most bands rehearsed music and played scales, long tones, and…

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

Topp, Andreas; Queiroz, Raquel; Grüneis, Andreas

In this work, we present a model of the surface states of nonsymmorphic semimetals. These are derived from surface mass terms that lift the high degeneracy imposed in the band structure by the nonsymmorphic bulk symmetries. Reflecting the reduced symmetry at the surface, the bulk bands are strongly modified. This leads to the creation of two-dimensional floating bands, which are distinct from Shockley states, quantum well states or topologically protected surface states. We focus on the layered semimetal ZrSiS to clarify the origin of its surface states. We demonstrate an excellent agreement between DFT calculations and ARPES measurements and presentmore » an effective four-band model in which similar surface bands appear. Finally, we emphasize the role of the surface chemical potential by comparing the surface density of states in samples with and without potassium coating. Our findings can be extended to related compounds and generalized to other crystals with nonsymmorphic symmetries.« less

Wireless Computers: Radio and Light Communications May Bring New Freedom to Computing.

ERIC Educational Resources Information Center

Hartmann, Thom

1984-01-01

Describes systems which use wireless terminals to communicate with mainframe computers or minicomputers via radio band, discusses their limitations, and gives examples of networks using such systems. The use of communications satellites to increase their range and the possibility of using light beams to transmit data are also discussed. (MBR)

47 CFR 27.1190 - Termination of cost-sharing obligations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... relocation will sunset for all AWS entities fifteen years after the relocation sunset period for BRS relocation commences, i.e., fifteen years after the first AWS licenses are issued in any part of the 2150-2162 MHz band. AWS entrants that trigger a cost-sharing obligation prior to the sunset date must...

47 CFR 27.1190 - Termination of cost-sharing obligations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... relocation will sunset for all AWS entities fifteen years after the relocation sunset period for BRS relocation commences, i.e., fifteen years after the first AWS licenses are issued in any part of the 2150-2162 MHz band. AWS entrants that trigger a cost-sharing obligation prior to the sunset date must...

Behavioral Profiles in Phelan-McDermid Syndrome: Focus on Mental Health

ERIC Educational Resources Information Center

Shaw, Steven R.; Rahman, Amira; Sharma, Akanksha

2011-01-01

Phelan-McDermid syndrome (PMS) is a multiple congenital anomalies and intellectual disabilities syndrome associated with a deletion of chromosome 22 terminal band 13.3. The deletion is associated with severe intellectual disabilities, absent or delayed speech, behavior problems, and autism. The objective of this study was to provide a detailed…

Narrow Angle Diversity using ACTS Ka-band Signal with Two USAT Ground Stations

NASA Technical Reports Server (NTRS)

Kalu, A.; Emrich, C.; Ventre, J.; Wilson, W.; Acosta, R.

1998-01-01

Two ultra small aperture terminal (USAT) ground stations, separated by 1.2 km in a narrow angle diversity configuration, received a continuous Ka-band tone sent from Cleveland Link Evaluation Terminal (LET). The signal was transmitted to the USAT ground stations via NASA's Advanced Communications Technology Satellite (ACTS) steerable beam. Received signal power at the two sites was measured and analyzed. A dedicated datalogger at each site recorded time-of-tip data from tipping bucket rain gauges, providing rain amount and instantaneous rain rate. WSR-88D data was also obtained for the collection period. Eleven events with ground-to-satellite slant-path precipitation and resultant signal attenuation were observed during the data collection period. Fade magnitude and duration were compared at the two sites and diversity gain was calculated. These results exceeded standard diversity gain model predictions by several decibels. Rain statistics from tipping bucket data and from radar data were also compared to signal attenuation. The nature of Florida's subtropical rainfall, specifically its impact on signal attenuation at the sites, was addressed.

7 CFR 953.66 - Termination.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Termination. 953.66 Section 953.66 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... STATES Order Regulating Handling Effective Time and Termination § 953.66 Termination. (a) The Secretary...

Electric polarization control of magnetoresistance in complex oxide heterojunctions

NASA Astrophysics Data System (ADS)

Swartz, Adrian G.; Inoue, Hisashi; Hwang, Harold Y.

2016-10-01

Lorentzian magnetoresistance (L-MR) has been widely observed in three-terminal ferromagnet-nonmagnet (FM-NM) tunnel junctions. One possible explanation for this behavior is ensemble dephasing (Hanle effect) of a spin accumulation, potentially offering a powerful approach for characterizing the spin lifetime of emerging spintronics materials. However, discrepancies between the extracted spin parameters with known materials properties has cast doubt on this interpretation for most implementations. Here, we have developed a method to control band alignments in perovskite oxide heterostructures through the use of epitaxial interface dipoles, providing a highly effective method for manipulating the Schottky barrier height and contact resistance. Using these atomically engineered heterojunctions, we are able to tune key parameters relevant to various spin accumulation models, providing an experimental platform which can test their applicability. We find that the observed L-MR is inconsistent with an interpretation of spin accumulation in either the NM material or in interface states. Rather, we consider a mechanism analogous to Coulomb blockade in quantum dots, where spin-dependent tunneling through an ensemble of interfacial defect states is controlled by local and external magnetic fields.

New symmetry of the cluster model

NASA Astrophysics Data System (ADS)

Gai, Moshe

2015-10-01

A new approach to clustering in the frame of the Algebraic Cluster Model (ACM) has been developed. It predicts rotation-vibration structure with rotational band of an oblate equilateral triangular spinning top with a 𝒟3h symmetry characterized by the sequence of states: 0+, 2+, 3-, 4±, 5- with almost degenerate 4+ and 4- (parity doublet) states. Our measurement of the new 22+ and the measured of the new 5- state in 12C fit very well to the predicted (ground state) rotational band structure with the sequence of states: 0+, 2+, 3-, 4±, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a 𝒟3h symmetry was observed in triatomic molecules, and it is observed in 12C for the first time in nuclear physics. We discuss a classification of other rotation-vibration bands in 12C such as the (0+) Hoyle band and the (1-) bending mode band and suggest measurements in search of the predicted ("missing") states that may shed new light on clustering in 12C and light nuclei. In particular, the observation (or non observation) of the predicted ("missing") states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha particles composing the Hoyle state at 7.654 MeV in 12C.

Ultra-wideband ladder filter using SH(0) plate wave in thin LiNbO(3) plate and its application to tunable filter.

PubMed

Kadota, Michio; Tanaka, Shuji

2015-05-01

A cognitive radio terminal using vacant frequency bands of digital TV (DTV) channels, i.e., TV white space, strongly requires a compact tunable filter covering a wide frequency range of the DTV band (470 to 710 MHz in Japan). In this study, a T-type ladder filter using ultra-wideband shear horizontal mode plate wave resonators was fabricated, and a low peak insertion loss of 0.8 dB and an ultra-large 6 dB bandwidth of 240 MHz (41%) were measured in the DTV band. In addition, bandpass filters with different center frequencies of 502 and 653 MHz at 6 dB attenuation were numerically synthesized based on the same T-type ladder filter in conjunction with band rejection filters with different frequencies. The results suggest that the combination of the wideband T-type ladder filter and the band rejection filters connected with variable capacitors enables a tunable filter with large tunability of frequency and bandwidth as well as large rejection at the adjacent channels of an available TV white space.

Study on statistical models for land mobile satellite channel

NASA Astrophysics Data System (ADS)

Wang, Ying; Hu, Xiulin

2005-11-01

Mobile terminals in a mobile satellite communication system cause the radio propagation channel to vary with time. So it is necessary to study the channel models in order to estimate the behavior of satellite signal propagation. A lot of research work have been done on the L- and S- bands. With the development of gigabit data transmissions and multimedia applications in recent years, the Ka-band studies gain much attention. Non-geostationary satellites are also in research because of its low propagation delay and low path loss. The future satellite mobile communication systems would be integrated into the other terrestrial networks in order to enable global, seamless and ubiquitous communications. At the same time QoS-technologies are studied to satisfy users' different service classes, such as mobility and resource managements. All the above make a suitable efficient channel model face new challenges. This paper firstly introduces existed channel models and analyzes their respective characteristics. Then we focus on a general model presented by Xie YongJun, which is popular under any environment and describes difference through different parameter values. However we believe that it is better to take multi-state Markov model as category in order to adapt to different environments. So a general model based on Markov process is presented and necessary simulation is carried out.

Satellite-tagged osprey nearly sets longevity record and productivity response to initial captures

USGS Publications Warehouse

Henny, Charles J.; Martell, Mark S.

2017-01-01

We equipped adult Ospreys (Pandion haliaetus) from 24 nests in Oregon/Washington with satellite-tracked battery-powered radios, known as platform transmitter terminals (PTTs), in 1996–1999. These Ospreys from the lower Columbia River (river miles 76–286), and the Willamette Valley in western Oregon were part of a larger study of Osprey fall migration, wintering ecology, and spring migration, which included additional adults from the Upper Midwest and East Coast of the United States (Martell et al. 2001, 2014, Washburn et al. 2014). These early-generation PTTs weighed 30–35 g (Microwave Telemetry Inc., Columbia, MD U.S.A.) and utilized the ARGOS tracking system (www.argos-system.org). We placed PTTs on the birds' backs using Teflon ribbon (Bally Ribbon, Bally, PA U.S.A.) in a standard backpack configuration (Kenward 2001). With the mass of adult male Ospreys 1400 to 1500 g (Poole et al. 2002), the ratio of tag mass to body mass was 2.0 to 2.5%. Ospreys also received a standard size 8 bird band (U.S. Geological Survey) on one leg and a numbered color band on the other. For more details on trapping techniques, attachment procedures, the battery-powered units, turn-on, turn-off cycles, and tracking equipment, see Martell et al. (2001).

Investigation of the redox states of (Ru(bpy) sub 2 CN) sub 2 CN sup + : Evidence for valence delocalization of the singly oxidized complex

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

Cooper, J.B.; Vess, T.M.; Kalsbeck, W.A.

1991-05-15

A spectroelectrochemical study of both the oxidized and reduced forms of (Ru(bpy){sub 2}CN){sub 2}CN{sup +} is reported. The uv-vis spectra of the parent and reduced species indicate the complex consists of two identical chromophores, which are nearly identical with the Ru(bpy){sub 2}(CN){sub 2} chromophore, even though one ruthenium is bound to the carbon of the bridging CN while the other is nitrogen bound. Only the shift in the bridging CN stretching frequency wit reduction offers any distinction between the two following observations: (1) only two CN stretches are observed in the oxidized form, (2) the shift to higher energy ofmore » the terminal CN stretches for the bimetallic species is half of that observed upon oxidation of the monometallic complex, (3) the sharpness and solvent independence of the near-IR band is not consistent with Hush predictions for the IVT band, and (4) the separation of the oxidation waves implies a comproportionation constant for the bimetallic species of 1.38 {times} 10{sup 10} (assuming no difference in metal centers) comparable in magnitude to other delocalized systems. 40 refs., 8 figs., 2 tabs.« less

Electrical and optical properties of Si-doped Ga2O3

NASA Astrophysics Data System (ADS)

Li, Yin; Yang, Chuanghua; Wu, Liyuan; Zhang, Ru

2017-05-01

The charge densities, band structure, density of states, dielectric functions of Si-doped β-Ga2O3 have been investigated based on the density functional theory (DFT) within the hybrid functional HSE06. The heavy doping makes conduction band split out more bands and further influences the band structure. It decreases the band gap and changes from a direct gap to an indirect gap. After doping, the top of the valence bands is mainly composed by the O-2p states, Si-3p states and Ga-4p states and the bottom of the conduction bands is almost formed by the Si-3s, Si-3p and Ga-4s orbits. The anisotropic optical properties have been investigated by means of the complex dielectric function. After the heavy Si doping, the position of absorption band edges did not change much. The slope of the absorption curve descends and indicates that the absorption became more slow for Si-doped β-Ga2O3 than undoped one due to the indirect gap of Si-doped β-Ga2O3.

Structure of the low-lying positive parity states in the proton-neutron symplectic model

NASA Astrophysics Data System (ADS)

Ganev, H. G.

2018-05-01

The proton-neutron symplectic model with Sp(12, R) dynamical symmetry is applied for the simultaneous description of the microscopic structure of the low-lying states of the ground state, γ and β bands in 166 Er. For this purpose, the model Hamiltonian is diagonalized in the space of stretched states by exploiting the SUp (3) ⊗ SUn (3) symmetry-adapted basis. The theoretical predictions are compared with experiment and some other microscopic collective models, like the one-component Sp(6, R) symplectic and pseudo-SU(3) models. A good description of the energy levels of the three bands under consideration, as well as the enhanced intraband B(E2) transition strengths between the states of the ground and γ bands is obtained without the use of effective charges. The results show the presence of a good SU(3) dynamical symmetry. It is also shown that, in contrast to the Sp(6, R) case, the lowest excited bands, e.g., the β and γ bands, naturally appear together with the ground state band within a single Sp(12, R) irreducible representation.

Comparative cytogenetics of Physalaemus albifrons and Physalaemus cuvieri species groups (Anura, Leptodactylidae).

PubMed

Vittorazzi, Stenio Eder; Quinderé, Yeda Rumi Serra Douglas; Recco-Pimentel, Shirlei Maria; Tomatis, Cristian; Baldo, Diego; Lima, Janaina Reis Ferreira; Ferro, Juan Martín; Lima, Jucivaldo Dias; Lourenço, Luciana Bolsoni

2014-01-01

Recently, Physalaemus albifrons (Spix, 1824) was relocated from the Physalaemus cuvieri group to the same group as Physalaemus biligonigerus (Cope, 1861), Physalaemus marmoratus (Reinhardt & Lütken, 1862) and Physalaemus santafecinus Barrio, 1965. To contribute to the analysis of this proposition, we studied the karyotypes of Physalaemus albifrons, Physalaemus santafecinus and three species of the Physalaemus cuvieri group. The karyotype of Physalaemus santafecinus was found to be very similar to those of Physalaemus biligonigerus and Physalaemus marmoratus, which were previously described. A remarkable characteristic that these three species share is a conspicuous C-band that extends from the pericentromeric region almost to the telomere in the short arm of chromosome 3. This characteristic is not present in the Physalaemus albifrons karyotype and could be a synapomorphy of Physalaemus biligonigerus, Physalaemus marmoratus and Physalaemus santafecinus. The karyotype of Physalaemus santafecinus is also similar to those of Physalaemus marmoratus and Physalaemus biligonigerus owing to the presence of several terminal C-bands and the distal localization of the NOR in a small metacentric chromosome. In contrast, the Physalaemus albifrons karyotype has no terminal C-bands and its NOR is located interstitially in the long arm of submetacentric chromosome 8. The NOR-bearing chromosome of Physalaemus albifrons very closely resembles those found in Physalaemus albonotatus (Steindachner, 1864), Physalaemus cuqui Lobo, 1993 and some populations of Physalaemus cuvieri Fitzinger, 1826. Additionally, the Physalaemus albifrons karyotype has an interstitial C-band in chromosome 5 that has been exclusively observed in species of the Physalaemus cuvieri group. Therefore, we were not able to identify any chromosomal feature that supports the reallocation of Physalaemus albifrons.

Comparative cytogenetics of Physalaemus albifrons and Physalaemus cuvieri species groups (Anura, Leptodactylidae)

PubMed Central

Vittorazzi, Stenio Eder; Quinderé*, Yeda Rumi Serra Douglas; Recco-Pimentel, Shirlei Maria; Tomatis, Cristian; Baldo, Diego; Lima, Janaina Reis Ferreira; Ferro, Juan Martín; Lima, Jucivaldo Dias; Lourenço, Luciana Bolsoni

2014-01-01

Abstract Recently, Physalaemus albifrons (Spix, 1824) was relocated from the Physalaemus cuvieri group to the same group as Physalaemus biligonigerus (Cope, 1861), Physalaemus marmoratus (Reinhardt & Lütken, 1862) and Physalaemus santafecinus Barrio, 1965. To contribute to the analysis of this proposition, we studied the karyotypes of Physalaemus albifrons, Physalaemus santafecinus and three species of the Physalaemus cuvieri group. The karyotype of Physalaemus santafecinus was found to be very similar to those of Physalaemus biligonigerus and Physalaemus marmoratus, which were previously described. A remarkable characteristic that these three species share is a conspicuous C-band that extends from the pericentromeric region almost to the telomere in the short arm of chromosome 3. This characteristic is not present in the Physalaemus albifrons karyotype and could be a synapomorphy of Physalaemus biligonigerus, Physalaemus marmoratus and Physalaemus santafecinus. The karyotype of Physalaemus santafecinus is also similar to those of Physalaemus marmoratus and Physalaemus biligonigerus owing to the presence of several terminal C-bands and the distal localization of the NOR in a small metacentric chromosome. In contrast, the Physalaemus albifrons karyotype has no terminal C-bands and its NOR is located interstitially in the long arm of submetacentric chromosome 8. The NOR-bearing chromosome of Physalaemus albifrons very closely resembles those found in Physalaemus albonotatus (Steindachner, 1864), Physalaemus cuqui Lobo, 1993 and some populations of Physalaemus cuvieri Fitzinger, 1826. Additionally, the Physalaemus albifrons karyotype has an interstitial C-band in chromosome 5 that has been exclusively observed in species of the Physalaemus cuvieri group. Therefore, we were not able to identify any chromosomal feature that supports the reallocation of Physalaemus albifrons. PMID:25147623

Early development and segment formation in the centipede, Strigamia maritima (Geophilomorpha).

PubMed

Chipman, Ariel D; Arthur, Wallace; Akam, Michael

2004-01-01

Geophilomorph centipedes exhibit a number of unique characteristics that make them of particular developmental and evolutionary interest. Segment numbers in geophilomorphs are higher than in any other centipedes, ranging from 27 to 191. They may be constant within a species, presenting in extreme form the "counting" problem in development, or they may vary--a situation that provides us with the opportunity to study naturally occurring variation in segment numbers. All their segments are generated during embryogenesis, a situation unlike that in the more basal centipede orders, which generate only a fraction of their 15 trunk segments in the embryo and develop the rest postembryonically. Here we provide a foundation for further developmental studies of the Geophilomorpha, building on the one study that has been conducted to date, on the coastal species Strigamia maritima. Development begins with the migration of nuclei to the surface of the egg, which then condense to form an embryonic rudiment of more than 20,000 cells, covering an entire hemisphere. During early development, the embryo can be divided into two distinct areas: a large terminal disc of apparently undifferentiated tissue and the germ-band, which has a clear anteroposterior axis and differentiated segments. The germ-band forms from the anterior of the terminal disc and extends anteriorly as the disc contracts. New segments are formed at the posterior margin of the germ-band. Once the process of segmentation ends, the germ-band folds and sinks into the yolk. We note that the classic description of centipede development, by Heymons more than a century ago, contains a fundamental error in the identification of the axes and hence in the interpretation of early segmentation.

AMPA experimental communications systems

NASA Technical Reports Server (NTRS)

Beckerman, D.; Fass, S.; Keon, T.; Sielman, P.

1982-01-01

The program was conducted to demonstrate the satellite communication advantages of Adaptive Phased Array Technology. A laboratory based experiment was designed and implemented to demonstrate a low earth orbit satellite communications system. Using a 32 element, L-band phased array augmented with 4 sets of weights (2 for reception and 2 for transmission) a high speed digital processing system and operating against multiple user terminals and interferers, the AMPA system demonstrated: communications with austere user terminals, frequency reuse, communications in the face of interference, and geolocation. The program and experiment objectives are described, the system hardware and software/firmware are defined, and the test performed and the resultant test data are presented.

Standard-M mobile satellite terminal employing electronic beam squint tracking

NASA Technical Reports Server (NTRS)

Hawkins, G. J.; Beach, M. A.; Hilton, G. S.

1990-01-01

In recent years, extensive experience has been built up at the University of Bristol in the use of the Electronic Beam Squint (EBS) tracking technique, applied to large earth station facilities. The current interest in land mobile satellite terminals, using small tracking antennas, has prompted the investigation of the applicability of the EBS technique to this environment. The development of an L-band mechanically steered vehicle antenna is presented. A description of the antenna is followed by a detailed investigation of the tracking environment and its implications on the error detection capability of the system. Finally, the overall hardware configuration is described along with plans for future work.

Differential BPFs with Multiple Transmission Zeros Based on Terminated Coupled Lines

NASA Astrophysics Data System (ADS)

Niu, Yiming; Yang, Guo; Wu, Wen

2018-04-01

Differential bandpass filters (BPFs) named Filter A and Filter B based on Terminated Coupled Lines (TCLs) are proposed in this letter. The TCLs contributes to not only three poles in differential-mode (DM) for wideband filtering response but also multiple zeros in both DM and common-mode (CM) offering wide DM out-of-band rejection and good CM suppression. Fabricated filters centred at 3.5 GHz with wide DM passband and wideband CM suppression have been designed and measured. The filters improved the noise suppression capability of the communication and radiometer systems. The simulated and measured results are in good agreement.

40 CFR 35.4255 - Can my group terminate our TAG?

Code of Federal Regulations, 2010 CFR

2010-07-01

... ASSISTANCE STATE AND LOCAL ASSISTANCE Grants for Technical Assistance Grant Disputes, Termination, and... written notification explaining the reasons for the termination and the effective date. ...

Atomic and electronic structure of the CdTe(111)B–(2√3 × 4) orthogonal surface

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

Bekenev, V. L., E-mail: bekenev@ipms.kiev.ua; Zubkova, S. M.

2017-01-15

The atomic and electronic structure of four variants of Te-terminated CdTe(111)B–(2√3 × 4) orthogonal polar surface (ideal, relaxed, reconstructed, and reconstructed with subsequent relaxation) are calculated ab initio for the first time. The surface is modeled by a film composed of 12 atomic layers with a vacuum gap of ~16 Å in the layered superlattice approximation. To close Cd dangling bonds on the opposite side of the film, 24 fictitious hydrogen atoms with a charge of 1.5 electrons each are added. Ab initio calculations are performed using the Quantum Espresso program based on density functional theory. It is demonstrated thatmore » relaxation leads to splitting of the four upper layers. The band energy structures and total and layer-by-layer densities of electronic states for the four surface variants are calculated and analyzed.« less

Analyses of interactions between the marine terminal and highway operations : final report.

DOT National Transportation Integrated Search

2014-04-01

Changes in vessel sizes arriving at United States ports may influence the operating regimes and schedules at the port terminals However, the impacts to highway and rail operations outside of the port terminals because of changing port terminal operat...

Effect of U on the electronic properties of neodymium gallate (NdGaO3): theoretical and experimental studies.

PubMed

Reshak, Ali Hussain; Piasecki, M; Auluck, S; Kityk, I V; Khenata, R; Andriyevsky, B; Cobet, C; Esser, N; Majchrowski, A; Swirkowicz, M; Diduszko, R; Szyrski, W

2009-11-19

We have performed a density functional calculation for the centrosymmetric neodymium gallate using a full-potential linear augmented plane wave method with the LDA and LDA+U exchange correlation. In particular, we explored the influence of U on the band dispersion and optical transitions. Our calculations show that U = 0.55 Ry gives the best agreement with our ellipsometry data taken in the VUV spectral range with a synchrotron source. Our LDA+U (U = 0.55) calculation shows that the valence band maximum (VBM) is located at T and the conduction band minimum (CBM) is located at the center of the Brillouin zone, resulting in a wide indirect energy band gap of about 3.8 eV in excellent agreement with our experiment. The partial density of states show that the upper valence band originates predominantly from Nd-f and O-p states, with a small admixture of Nd-s/p and Ga-p B-p states, while the lower conduction band prevailingly originates from the Nd-f and Nd-d terms with a small contribution of O-p-Ga-s/p states. The Nd-f states in the upper valence band and lower conduction band have a significant influence on the energy band gap dispersion which is illustrated by our calculations. The calculated frequency dependent optical properties show a small positive uniaxial anisotropy.

Male meiosis, heterochromatin characterization and chromosomal location of rDNA in Microtomus lunifer (Berg, 1900) (Hemiptera: Reduviidae: Hammacerinae)

PubMed Central

Poggio, María Georgina; Bressa, María José; Papeschi, Alba Graciela

2011-01-01

Abstract In the present work, we analysed the male meiosis, the content and distribution of heterochromatin and the number and location of nucleolus organizing regions in Microtomus lunifer (Berg, 1900) by means of standard technique, C- and fluorescent bandings, and fluorescent in situ hybridization with an 18S rDNA probe. This species is the second one cytogenetically analysed within the Hammacerinae. Its male diploid chromosome number is 31 (2n=28+X1X2Y), including a minute pair of m-chromosomes. The diploid autosomal number and the presence of m-chromosomes are similar to those reported in Microtomus conspicillaris (Drury, 1782) (2n=28+XY). However, Microtomus lunifer has a multiple sex chromosome system X1X2Y (male) that could have originated by fragmentation of the ancestral X chromosome. Taking into account that Microtomus conspicillaris and Microtomus lunifer are the only two species within Reduviidae that possess m-chromosomes, the presence of this pair could be a synapomorphy for the species of this genus. C- and fluorescent bandings showed that the amount of heterochromatin in Microtomus lunifer was small, and only a small CMA3 bright band was observed in the largest autosomal pair at one terminal region. FISH with the 18S rDNA probe demonstrated that ribosomal genes were terminally placed on the largest autosomal pair. Our present results led us to propose that the location of rDNA genes could be associated with variants of the sex chromosome systems in relation with a kind of the sex chromosome systems within this family. Furthermore, the terminal location of NOR in the largest autosomal pair allowed us to use it as a chromosome marker and, thus, to infer that the kinetic activity of both ends is not a random process, and there is an inversion of this activity. PMID:24260616

5 CFR 870.907 - Termination and conversion.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Termination and conversion. 870.907....907 Termination and conversion. (a) Assigned insurance terminates under the conditions stated in... time the conversion policy is issued. (5) The employing office must notify each assignee of the...

5 CFR 870.907 - Termination and conversion.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 5 Administrative Personnel 2 2011-01-01 2011-01-01 false Termination and conversion. 870.907....907 Termination and conversion. (a) Assigned insurance terminates under the conditions stated in... time the conversion policy is issued. (5) The employing office must notify each assignee of the...

22 CFR 42.83 - Termination of registration.

Code of Federal Regulations, 2012 CFR

2012-04-01

....83 Foreign Relations DEPARTMENT OF STATE VISAS VISAS: DOCUMENTATION OF IMMIGRANTS UNDER THE... Termination of registration. (a) Termination following failure of applicant to apply for visa. In accordance with INA 203(g), an alien's registration for an immigrant visa shall be terminated if, within one year...

22 CFR 42.83 - Termination of registration.

Code of Federal Regulations, 2011 CFR

2011-04-01

....83 Foreign Relations DEPARTMENT OF STATE VISAS VISAS: DOCUMENTATION OF IMMIGRANTS UNDER THE... Termination of registration. (a) Termination following failure of applicant to apply for visa. In accordance with INA 203(g), an alien's registration for an immigrant visa shall be terminated if, within one year...

22 CFR 42.83 - Termination of registration.

Code of Federal Regulations, 2010 CFR

2010-04-01

....83 Foreign Relations DEPARTMENT OF STATE VISAS VISAS: DOCUMENTATION OF IMMIGRANTS UNDER THE... Termination of registration. (a) Termination following failure of applicant to apply for visa. In accordance with INA 203(g), an alien's registration for an immigrant visa shall be terminated if, within one year...

22 CFR 42.83 - Termination of registration.

Code of Federal Regulations, 2014 CFR

2014-04-01

....83 Foreign Relations DEPARTMENT OF STATE VISAS VISAS: DOCUMENTATION OF IMMIGRANTS UNDER THE... Termination of registration. (a) Termination following failure of applicant to apply for visa. In accordance with INA 203(g), an alien's registration for an immigrant visa shall be terminated if, within one year...

22 CFR 42.83 - Termination of registration.

Code of Federal Regulations, 2013 CFR

2013-04-01

....83 Foreign Relations DEPARTMENT OF STATE VISAS VISAS: DOCUMENTATION OF IMMIGRANTS UNDER THE... Termination of registration. (a) Termination following failure of applicant to apply for visa. In accordance with INA 203(g), an alien's registration for an immigrant visa shall be terminated if, within one year...

Near-Infrared Spectroscopy of Ethynyl Radical, C2H

NASA Astrophysics Data System (ADS)

Le, Anh T.; Hall, Gregory; Sears, Trevor

2016-06-01

The ethynyl radical, C_2H, is a reactive intermediate important in various combustion processes and also widely observed in the interstellar medium. In spite of extensive previous spectroscopic studies, the characterization of the near infrared transitions from the tilde{X}2Σ+ state to the mixed vibrational overtone and tilde{A}2Π states is incomplete. A strong band of C_2H at 7064 cm-1 was first observed in a neon matrix and assigned as the tilde{A}2Π(002)1 - tilde{X}2Σ+ transition by Forney et al. Subsequent theoretical work of Tarroni and Carter attributed the strong absorptions in this region to transitions terminating in two upper states, each a mixture of vibrationally excited tilde{X} states and different zero-order tilde{A}-state bending levels: a 2Σ+ symmetry combination of tilde{X}(0,20,3) and tilde{A}(0,3,0)0κ and a 2Π symmetry combination of tilde{X}(0,31,3) and tilde{A}(0,0,2)1. Transitions to them from the zero point level of the tilde{X} state are calculated to differ in energy by less than 10 cm-1 and to be within a factor of two in intensity. Diode laser transient absorption was used to record Doppler-limited spectra between 7020 and 7130 cm-1, using 193 nm photolysis of CF_3C_2H as a source of C_2H. Two interleaved, rotationally resolved bands were observed, consistent with a 2Σ - 2Σ transition at 7088 cm-1 and a 2Π - 2Σ transition at 7108 cm-1, in good accord with the Tarroni and Carter calculation. Progress on the assignment and fitting of the spectra will be reported. Acknowledgements: Work at Brookhaven National Laboratory was carried out under Contract No. DE-SC0012704 with the U.S. Department of Energy, Office of Science, and supported by its Division of Chemical Sciences, Geosciences, and Biosciences. D. Forney, M.E. Jacox, and W.E. Thompson, J. Mol. Spectrosc. 170, 178 (1995). R. Tarroni and S. Carter, Mol. Phys. 102, 2167 (2004)

Link between light-triggered Mg-banding and chamber formation in the planktic foraminifera Neogloboquadrina dutertrei

NASA Astrophysics Data System (ADS)

Fehrenbacher, Jennifer S.; Russell, Ann D.; Davis, Catherine V.; Gagnon, Alexander C.; Spero, Howard J.; Cliff, John B.; Zhu, Zihua; Martin, Pamela

2017-05-01

The relationship between seawater temperature and the average Mg/Ca ratios in planktic foraminifera is well established, providing an essential tool for reconstructing past ocean temperatures. However, many species display alternating high and low Mg-bands within their shell walls that cannot be explained by temperature alone. Recent experiments demonstrate that intrashell Mg variability in Orbulina universa, which forms a spherical terminal shell, is paced by the diurnal light/dark cycle. Whether Mg-heterogeneity is also diurnally paced in species with more complex shell morphologies is unknown. Here we show that high Mg/Ca-calcite forms at night in cultured specimens of the multi-chambered species Neogloboquadrina dutertrei. Our results demonstrate that N. dutertrei adds a significant amount of calcite, and nearly all Mg-bands, after the final chamber forms. These results have implications for interpreting patterns of calcification in N. dutertrei and suggest that diurnal Mg-banding is an intrinsic component of biomineralization in planktic foraminifera.

Saturation of side-band instabilities in a free-electron laser

NASA Astrophysics Data System (ADS)

Lin, A. T.

The efficiency of a free electron laser is intrinsically limited because the growth of the ponderomotive force produced by the interaction of the rippled magnetic field and the signal wave will eventually trap the electrons. There are a number of approaches for enhancing the efficiency of a free electron laser (FEL). One approach employs a dc field. Most of the efficiency enhancement calculations use a single-mode approximation which prohibits the side band waves to grow. In the present investigation, a particle simulation procedure is employed to demonstrate that the enhancement process is ultimately terminated by the generation of side band instabilities due to the interaction of the trapped electrons and the signal wave. The side band instability will play an important part in determining the maximum output power which can be obtained from a FEL. It is also shown that a considerable improvement in output power can still be achieved by carefully choosing the strength and the turn-on time of the dc electric field.

Quasiparticle Scattering in the Rashba Semiconductor BiTeBr: The Roles of Spin and Defect Lattice Site.

PubMed

Butler, Christopher John; Yang, Po-Ya; Sankar, Raman; Lien, Yen-Neng; Lu, Chun-I; Chang, Luo-Yueh; Chen, Chia-Hao; Wei, Ching-Ming; Chou, Fang-Cheng; Lin, Minn-Tsong

2016-09-28

Observations of quasiparticle interference have been used in recent years to examine exotic carrier behavior at the surfaces of emergent materials, connecting carrier dispersion and scattering dynamics to real-space features with atomic resolution. We observe quasiparticle interference in the strongly Rashba split 2DEG-like surface band found at the tellurium termination of BiTeBr and examine two mechanisms governing quasiparticle scattering: We confirm the suppression of spin-flip scattering by comparing measured quasiparticle interference with a spin-dependent elastic scattering model applied to the calculated spectral function. We also use atomically resolved STM maps to identify point defect lattice sites and spectro-microscopy imaging to discern their varying scattering strengths, which we understand in terms of the calculated orbital characteristics of the surface band. Defects on the Bi sublattice cause the strongest scattering of the predominantly Bi 6p derived surface band, with other defects causing nearly no scattering near the conduction band minimum.

Intensities of the Martian N2 electron-impact excited dayglow emissions

NASA Astrophysics Data System (ADS)

Fox, Jane L.; Hać, Nicholas E. F.

2013-06-01

The first N2 emissions in the Martian dayglow were detected by the SPICAM UV spectrograph on board the Mars Express spacecraft. Intensities of the (0,5) and (0,6) Vegard-Kaplan bands were found to be about one third of those predicted more than 35 years ago. The Vegard-Kaplan band system arises from the transition from the lowest N2 triplet state (A3Σu+;v') to the electronic ground state (X1Σg+;v″). It is excited in the Martian dayglow by direct electron-impact excitation of the ground N2(X) state to the A state and by excitation to higher triplet states that populate the A state by cascading. Using revised data, we compute here updated intensities of several of the bands in the N2 triplet systems and those involving the a1Πg state, the upper state of the Lyman-Birge-Hopfield bands. We find that the predicted limb intensities for the (0,5) and (0,6) Vegard-Kaplan bands are consistent with the measured values.

Computational Design of Flat-Band Material.

PubMed

Hase, I; Yanagisawa, T; Kawashima, K

2018-02-26

Quantum mechanics states that hopping integral between local orbitals makes the energy band dispersive. However, in some special cases, there are bands with no dispersion due to quantum interference. These bands are called as flat band. Many models having flat band have been proposed, and many interesting physical properties are predicted. However, no real compound having flat band has been found yet despite the 25 years of vigorous researches. We have found that some pyrochlore oxides have quasi-flat band just below the Fermi level by first principles calculation. Moreover, their valence bands are well described by a tight-binding model of pyrochlore lattice with isotropic nearest neighbor hopping integral. This model belongs to a class of Mielke model, whose ground state is known to be ferromagnetic with appropriate carrier doping and on-site repulsive Coulomb interaction. We have also performed a spin-polarized band calculation for the hole-doped system from first principles and found that the ground state is ferromagnetic for some doping region. Interestingly, these compounds do not include magnetic element, such as transition metal and rare-earth elements.

Computational Design of Flat-Band Material

NASA Astrophysics Data System (ADS)

Hase, I.; Yanagisawa, T.; Kawashima, K.

2018-02-01

Quantum mechanics states that hopping integral between local orbitals makes the energy band dispersive. However, in some special cases, there are bands with no dispersion due to quantum interference. These bands are called as flat band. Many models having flat band have been proposed, and many interesting physical properties are predicted. However, no real compound having flat band has been found yet despite the 25 years of vigorous researches. We have found that some pyrochlore oxides have quasi-flat band just below the Fermi level by first principles calculation. Moreover, their valence bands are well described by a tight-binding model of pyrochlore lattice with isotropic nearest neighbor hopping integral. This model belongs to a class of Mielke model, whose ground state is known to be ferromagnetic with appropriate carrier doping and on-site repulsive Coulomb interaction. We have also performed a spin-polarized band calculation for the hole-doped system from first principles and found that the ground state is ferromagnetic for some doping region. Interestingly, these compounds do not include magnetic element, such as transition metal and rare-earth elements.

Stability of fractional Chern insulators in the effective continuum limit of Harper-Hofstadter bands with Chern number |C |>1

NASA Astrophysics Data System (ADS)

Andrews, Bartholomew; Möller, Gunnar

2018-01-01

We study the stability of composite fermion fractional quantum Hall states in Harper-Hofstadter bands with Chern number |C |>1 . From composite fermion theory, states are predicted to be found at filling factors ν =r /(k r |C |+1 ),r ∈Z , with k =1 for bosons and k =2 for fermions. Here, we closely analyze these series in both cases, with contact interactions for bosons and nearest-neighbor interactions for (spinless) fermions. In particular, we analyze how the many-body gap scales as the bands are tuned to the effective continuum limit of Chern number |C | bands, realized near flux density nϕ=1 /|C | . Near these points, the Hofstadter model requires large magnetic unit cells that yield bands with perfectly flat dispersion and Berry curvature. We exploit the known scaling of energies in the effective continuum limit in order to maintain a fixed square aspect ratio in finite-size calculations. Based on exact diagonalization calculations of the band-projected Hamiltonian for these lattice geometries, we show that for both bosons and fermions, the vast majority of finite-size spectra yield the ground-state degeneracy predicted by composite fermion theory. For the chosen interactions, we confirm that states with filling factor ν =1 /(k |C |+1 ) are the most robust and yield a clear gap in the thermodynamic limit. For bosons with contact interactions in |C |=2 and |C |=3 bands, our data for the composite fermion states are compatible with a finite gap in the thermodynamic limit. We also report new evidence for gapped incompressible states stabilized for fermions with nearest-neighbor interactions in |C |>1 bands. For cases with a clear gap, we confirm that the thermodynamic limit commutes with the effective continuum limit within finite-size error bounds. We analyze the nature of the correlation functions for the Abelian composite fermion states and find that the correlation functions for |C |>1 states are smooth functions for positions separated by |C | sites along both axes, giving rise to |C| 2 sheets; some of which can be related by inversion symmetry. We also comment on two cases which are associated with a bosonic integer quantum Hall effect (BIQHE): For ν =2 in |C |=1 bands, we find a strong competing state with a higher ground-state degeneracy, so no clear BIQHE is found in the band-projected Hofstadter model; for ν =1 in |C |=2 bands, we present additional data confirming the existence of a BIQHE state.

Spacecraft Doppler tracking with a VLBI antenna

NASA Technical Reports Server (NTRS)

Comoretto, G.; Iess, L.; Bertotti, B.; Brenkle, J. P.; Horton, T.

1990-01-01

Preliminary results are reported from Doppler-shift measurements to the Voyager-2 spacecraft at a distance of 26 AU, obtained using the 32-m VLBI antenna at Medicina (Italy) during July and August 1988. The apparatus comprises the el-az antenna, an S-X-band receiver, a hydrogen maser to generate the reference signal, a Mark III VLBI terminal, and a digital tone extractor capable of isolating a tone of known frequency from a noisy signal and giving its phase and amplitude. A signal transmitted in S-band from the NASA Deep Space Network (DSN) station in Australia and retransmitted coherently in X-band by Voyager, was received 7 h 6 min later at Medicina and at the DSN station in Madrid. Sample data are presented graphically and shown to be of generally high quality; further in-depth analysis is under way.

Terminal zone glacial sediment transfer at a temperate overdeepened glacier system

NASA Astrophysics Data System (ADS)

Swift, D. A.; Cook, S. J.; Graham, D. J.; Midgley, N. G.; Fallick, A. E.; Storrar, R.; Toubes Rodrigo, M.; Evans, D. J. A.

2018-01-01

Continuity of sediment transfer through glacial systems is essential to maintain subglacial bedrock erosion, yet transfer at temperate glaciers with overdeepened beds, where subglacial fluvial sediment transport should be greatly limited by adverse slopes, remains poorly understood. Complex multiple transfer processes in temperate overdeepened systems has been indicated by the presence of large frontal moraine systems, supraglacial debris of mixed transport origin, thick basal ice sequences, and englacial thrusts and eskers. At Svínafellsjökull, thrusts comprising decimetre-thick debris-rich bands of stratified facies ice of basal origin, with a coarser size distribution and higher clast content than that observed in basal ice layers, contribute substantially to the transfer of subglacial material in the terminal zone. Entrainment and transfer of material occurs by simple shear along the upper surface of bands and by strain-induced deformation of stratified and firnified glacier ice below. Thrust material includes rounded and well-rounded clasts that are also striated, indicating that fluvial bedload is deposited as subglacial channels approach the overdeepening and then entrained along thrusts. Substantial transfer also occurs within basal ice, with facies type and debris content dependent on the hydrological connectedness of the adverse slope. A process model of transfer at glaciers with terminal overdeepenings is proposed, in which the geometry of the overdeepening influences spatial patterns of ice deformation, hydrology, and basal ice formation. We conclude that the significance of thrusting in maintaining sediment transfer continuity has likely been overlooked by glacier sediment budgets and glacial landscape evolution studies.

A general theory of kinetics and thermodynamics of steady-state copolymerization.

PubMed

Shu, Yao-Gen; Song, Yong-Shun; Ou-Yang, Zhong-Can; Li, Ming

2015-06-17

Kinetics of steady-state copolymerization has been investigated since the 1940s. Irreversible terminal and penultimate models were successfully applied to a number of comonomer systems, but failed for systems where depropagation is significant. Although a general mathematical treatment of the terminal model with depropagation was established in the 1980s, a penultimate model and higher-order terminal models with depropagation have not been systematically studied, since depropagation leads to hierarchically-coupled and unclosed kinetic equations which are hard to solve analytically. In this work, we propose a truncation method to solve the steady-state kinetic equations of any-order terminal models with depropagation in a unified way, by reducing them into closed steady-state equations which give the exact solution of the original kinetic equations. Based on the steady-state equations, we also derive a general thermodynamic equality in which the Shannon entropy of the copolymer sequence is explicitly introduced as part of the free energy dissipation of the whole copolymerization system.

A Quasi-Classical Model of the Hubbard Gap in Lightly Compensated Semiconductors

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

Poklonski, N. A.; Vyrko, S. A.; Kovalev, A. I.

2016-03-15

A quasi-classical method for calculating the narrowing of the Hubbard gap between the A{sup 0} and A{sup +} acceptor bands in a hole semiconductor or the D{sup 0} and D{sup –} donor bands in an electron semiconductor is suggested. This narrowing gives rise to the phenomenon of a semiconductor transition from the insulator to metal state with an increase in doping level. The major (doping) impurity can be in one of three charge states (–1, 0, or +1), while the compensating impurity can be in states (+1) or (–1). The impurity distribution over the crystal is assumed to be randommore » and the width of Hubbard bands (levels), to be much smaller than the gap between them. It is shown that narrowing of the Hubbard gap is due to the formation of electrically neutral acceptor (donor) states of the quasicontinuous band of allowed energies for holes (electrons) from excited states. This quasicontinuous band merges with the top of the valence band (v band) for acceptors or with the bottom of the conduction band (c band) for donors. In other words, the top of the v band for a p-type semiconductor or the bottom of the c band for an n-type semiconductor is shifted into the band gap. The value of this shift is determined by the maximum radius of the Bohr orbit of the excited state of an electrically neutral major impurity atom, which is no larger than half the average distance between nearest impurity atoms. As a result of the increasing dopant concentration, the both Hubbard energy levels become shallower and the gap between them narrows. Analytical formulas are derived to describe the thermally activated hopping transition of holes (electrons) between Hubbard bands. The calculated gap narrowing with increasing doping level, which manifests itself in a reduction in the activation energy ε{sub 2} is consistent with available experimental data for lightly compensated p-Si crystals doped with boron and n-Ge crystals doped with antimony.« less

The Effect of C-Terminal Helix on the Stability of FF Domain Studied by Molecular Dynamics Simulation

PubMed Central

Zhao, Liling; Cao, Zanxia; Wang, Jihua

2012-01-01

To investigate the effect of C-terminal helix on the stability of the FF domain, we studied the native domain FF3-71 from human HYPA/FBP11 and the truncated version FF3-60 with C-terminal helix being deleted by molecular dynamics simulations with GROMACS package and GROMOS 43A1 force field. The results indicated that the structures of truncated version FF3-60 were evident different from those of native partner FF3-71. Compared with FF3-71, the FF3-60 lost some native contacts and exhibited some similar structural characters to those of intermediate state. The C-terminal helix played a major role in stabilizing the FF3-71 domain. To a certain degree, the FF domain had a tendency to form an intermediate state without the C-terminal helix. In our knowledge, this was the first study to examine the role of C-terminal helix of FF domain in detail by molecular dynamics simulations, which was useful to understand the three-state folding mechanism of the small FF domain. PMID:22408419

Evolution from quasivibrational to quasirotational structure in 155Tm and yrast 27 /2- to 25 /2- energy anomaly in the A ≈150 mass region

NASA Astrophysics Data System (ADS)

Liu, L.; Wang, S. Y.; Wang, S.; Hua, H.; Zhang, S. Q.; Meng, J.; Bark, R. A.; Wyngaardt, S. M.; Qi, B.; Sun, D. P.; Liu, C.; Li, Z. Q.; Jia, H.; Li, X. Q.; Xu, C.; Li, Z. H.; Sun, J. J.; Zhu, L. H.; Jones, P.; Lawrie, E. A.; Lawrie, J. J.; Wiedeking, M.; Bucher, T. D.; Dinoko, T.; Makhathini, L.; Majola, S. N. T.; Noncolela, S. P.; Shirinda, O.; Gál, J.; Kalinka, G.; Molnár, J.; Nyakó, B. M.; Timár, J.; Juhász, K.; Arogunjo, M.

2018-04-01

Excited states in 155Tm have been populated via the reaction 144Sm(16O, p 4 n )155Tm at a beam energy of 118 MeV. The ground-state band has been extended and a new side band of the ground-state band is identified. E-GOS curves and potential energy surface calculations are employed to discuss the structure evolution of the ground-state band. The newly observed side band in 155Tm is discussed based on the spin/energy systematics. In particular, the phenomenon of seniority inversion is proposed in 155Tm, and a systematic study of this phenomenon in the A ≈150 mass region is performed.

[Calcium in the developing skeletal muscles of the chick embryo].

PubMed

Samosudova, N V; Enenko, S O; Larin, Iu S; Shungskaia, V E

1982-07-01

The osmium-pyroantimonate technique was used for the ultrastructural study of Ca2+-localization in two types of chick embryo skeletal muscles: m. pectoralis and m. soleus. In 8- and 12-day old embryos the pyroantimonate precipitate was found on plasmalemma, condensed chromatine and ribosomes and in N-lines of I-band. During myogenesis (15-, 21-day old embryos) the calcium precipitate is redistributed from the above mentioned sites to terminal cisternae and N-line of I-band. It is proposed that calcium of N-lines may be involved in the glycogenolysis, its association with the muscle contraction occurring particularly at early developmental stages.

Persistent photoconductivity due to trapping of induced charges in Sn/ZnO thin film based UV photodetector

NASA Astrophysics Data System (ADS)

Yadav, Harish Kumar; Sreenivas, K.; Gupta, Vinay

2010-05-01

Photoconductivity relaxation in rf magnetron sputtered ZnO thin films integrated with ultrathin tin metal overlayer is investigated. Charge carriers induced at the ZnO-metal interface by the tin metal overlayer compensates the surface lying trap centers and leads to the enhanced photoresponse. On termination of ultraviolet radiation, recombination of the photoexcited electrons with the valence band holes leaves the excess carriers deeply trapped at the recombination center and holds the dark conductivity level at a higher value. Equilibrium between the recombination centers and valence band, due to trapped charges, eventually stimulates the persistent photoconductivity in the Sn/ZnO photodetectors.

Advanced mobile satellite communications using COMETS satellite in MM-wave and Ka-band

NASA Technical Reports Server (NTRS)

Ohmori, Shingo; Isobe, Shunkichi; Takeuchi, Makoto; Naito, Hideyuki

1993-01-01

Early in the 21st century, the demand for personal communications using mobile, hand-held, and VSAT terminals will rapidly increase. In a future system, many different types of services should be provided with one-hop connection. The Communications Research Laboratory (CRL) has studied a future advanced mobile satellite communications system using millimeter wave and Ka band. In 1990, CRL started the Communications and Broadcasting Engineering Test Satellite (COMETS) project. The satellite has been developed in conjunction with NASDA and will be launched in 1997. This paper describes the COMETS payload configuration and the experimental system for the advanced mobile communications mission.

20. View from northeast to southwest side of scanner building ...

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

20. View from northeast to southwest side of scanner building 104 showing two waveguide termination faces (fiberglass light bands on left of photograph). - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

47 CFR 25.149 - Application requirements for ancillary terrestrial components in the Mobile-Satellite Service...

Code of Federal Regulations, 2013 CFR

2013-10-01

... be limited to certain frequencies: (i) [Resreved] (ii) In the 1626.5-1660.5 MHz/1525-1559 MHz bands... stations and mobile terminals shall comply with part 1 of this chapter, Subpart I—Procedures Implementing... will comply with the following criteria through certification: (1) Geographic and temporal coverage. (i...

Maturation trajectories of cortical resting-state networks depend on the mediating frequency band.

PubMed

Khan, Sheraz; Hashmi, Javeria A; Mamashli, Fahimeh; Michmizos, Konstantinos; Kitzbichler, Manfred G; Bharadwaj, Hari; Bekhti, Yousra; Ganesan, Santosh; Garel, Keri-Lee A; Whitfield-Gabrieli, Susan; Gollub, Randy L; Kong, Jian; Vaina, Lucia M; Rana, Kunjan D; Stufflebeam, Steven M; Hämäläinen, Matti S; Kenet, Tal

2018-07-01

The functional significance of resting state networks and their abnormal manifestations in psychiatric disorders are firmly established, as is the importance of the cortical rhythms in mediating these networks. Resting state networks are known to undergo substantial reorganization from childhood to adulthood, but whether distinct cortical rhythms, which are generated by separable neural mechanisms and are often manifested abnormally in psychiatric conditions, mediate maturation differentially, remains unknown. Using magnetoencephalography (MEG) to map frequency band specific maturation of resting state networks from age 7 to 29 in 162 participants (31 independent), we found significant changes with age in networks mediated by the beta (13-30 Hz) and gamma (31-80 Hz) bands. More specifically, gamma band mediated networks followed an expected asymptotic trajectory, but beta band mediated networks followed a linear trajectory. Network integration increased with age in gamma band mediated networks, while local segregation increased with age in beta band mediated networks. Spatially, the hubs that changed in importance with age in the beta band mediated networks had relatively little overlap with those that showed the greatest changes in the gamma band mediated networks. These findings are relevant for our understanding of the neural mechanisms of cortical maturation, in both typical and atypical development. Copyright © 2018. Published by Elsevier Inc.

Effects of thermo-order-mechanical coupling on band structures in liquid crystal nematic elastomer porous phononic crystals.

PubMed

Yang, Shuai; Liu, Ying

2018-08-01

Liquid crystal nematic elastomers are one kind of smart anisotropic and viscoelastic solids simultaneously combing the properties of rubber and liquid crystals, which is thermal sensitivity. In this paper, the wave dispersion in a liquid crystal nematic elastomer porous phononic crystal subjected to an external thermal stimulus is theoretically investigated. Firstly, an energy function is proposed to determine thermo-induced deformation in NE periodic structures. Based on this function, thermo-induced band variation in liquid crystal nematic elastomer porous phononic crystals is investigated in detail. The results show that when liquid crystal elastomer changes from nematic state to isotropic state due to the variation of the temperature, the absolute band gaps at different bands are opened or closed. There exists a threshold temperature above which the absolute band gaps are opened or closed. Larger porosity benefits the opening of the absolute band gaps. The deviation of director from the structural symmetry axis is advantageous for the absolute band gap opening in nematic state whist constrains the absolute band gap opening in isotropic state. The combination effect of temperature and director orientation provides an added degree of freedom in the intelligent tuning of the absolute band gaps in phononic crystals. Copyright © 2018 Elsevier B.V. All rights reserved.

42 CFR 403.322 - Termination of agreements for Medicare recognition of State systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 2 2010-10-01 2010-10-01 false Termination of agreements for Medicare recognition of State systems. 403.322 Section 403.322 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PROVISIONS SPECIAL PROGRAMS AND PROJECTS Recognition of State...

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.

Probing the density of trap states in the middle of the bandgap using ambipolar organic field-effect transistors

NASA Astrophysics Data System (ADS)

Häusermann, Roger; Chauvin, Sophie; Facchetti, Antonio; Chen, Zhihua; Takeya, Jun; Batlogg, Bertram

2018-04-01

The number of trap states in the band gap of organic semiconductors directly influences the charge transport as well as the threshold and turn-on voltage. Direct charge transport measurements have been used until now to probe the trap states rather close to the transport level, whereas their number in the middle of the band gap has been elusive. In this study, we use PDIF-CN2, a well known n-type semiconductor, together with vanadium pentoxide electrodes to build ambipolar field-effect transistors. Employing three different methods, we study the density of trap states in the band gap of the semiconductor. These methods give consistent results, and no pool of defect states was found. Additionally, we show first evidence that the number of trap states close to the transport level is correlated with the number of traps in the middle of the band-gap, meaning that a high number of trap states close to the transport level also implies a high number of trap states in the middle of the band gap. This points to a common origin of the trap states over a wide energy range.

Understanding of sub-band gap absorption of femtosecond-laser sulfur hyperdoped silicon using synchrotron-based techniques

PubMed Central

Limaye, Mukta V.; Chen, S. C.; Lee, C. Y.; Chen, L. Y.; Singh, Shashi B.; Shao, Y. C.; Wang, Y. F.; Hsieh, S. H.; Hsueh, H. C.; Chiou, J. W.; Chen, C. H.; Jang, L. Y.; Cheng, C. L.; Pong, W. F.; Hu, Y. F.

2015-01-01

The correlation between sub-band gap absorption and the chemical states and electronic and atomic structures of S-hyperdoped Si have been extensively studied, using synchrotron-based x-ray photoelectron spectroscopy (XPS), x-ray absorption near-edge spectroscopy (XANES), extended x-ray absorption fine structure (EXAFS), valence-band photoemission spectroscopy (VB-PES) and first-principles calculation. S 2p XPS spectra reveal that the S-hyperdoped Si with the greatest (~87%) sub-band gap absorption contains the highest concentration of S2− (monosulfide) species. Annealing S-hyperdoped Si reduces the sub-band gap absorptance and the concentration of S2− species, but significantly increases the concentration of larger S clusters [polysulfides (Sn2−, n > 2)]. The Si K-edge XANES spectra show that S hyperdoping in Si increases (decreased) the occupied (unoccupied) electronic density of states at/above the conduction-band-minimum. VB-PES spectra evidently reveal that the S-dopants not only form an impurity band deep within the band gap, giving rise to the sub-band gap absorption, but also cause the insulator-to-metal transition in S-hyperdoped Si samples. Based on the experimental results and the calculations by density functional theory, the chemical state of the S species and the formation of the S-dopant states in the band gap of Si are critical in determining the sub-band gap absorptance of hyperdoped Si samples. PMID:26098075

High-spin structures in the 139Pr nucleus

NASA Astrophysics Data System (ADS)

Yeoh, E. Y.; Zhu, S. J.; Wang, J. G.; Xiao, Z. G.; Zhang, M.; Yan, W. H.; Wang, R. S.; Xu, Q.; Wu, X. G.; He, C. Y.; Li, G. S.; Zheng, Y.; Li, C. B.; Cao, X. P.; Hu, S. P.; Yao, S. H.; Yu, B. B.

2012-06-01

Background: 139Pr is located in a transitional region of neutron number close to the N=82 shell. The study of its high-spin states and collective bands is important for systematically understanding the nuclear structural characteristics in this region.Purpose: To investigate the high-spin levels and to search for oblate bands in 139Pr.Methods: The high-spin states of 139Pr have been studied via the reaction 124Sn(19F,4n) at a beam energy of 80 MeV. The experiment was carried out at the HI-13 Tandem Accelerator at the China Institute of Atomic Energy (CIAE). The data analysis was done by using the γ-γ coincidence method.Results: The level scheme of 139Pr has been expanded with spin up to 45/2ℏ. A total of 39 new levels and 45 new transitions are identified. Four collective band structures at high-spin states have been newly established. From systematic analysis, one of the bands is proposed as a double decoupled band; two bands are proposed as oblate bands with γ˜-60∘; another band is suggested as an oblate-triaxial band with γ˜-90∘. The other characteristics for these bands are discussed.Conclusions: A new level scheme in 139Pr has been established and the collective bands at high spin have been identified. The result shows that the strong oblate shape-driving effect is caused by neutrons at the high-spin states in 139Pr.

48 CFR 49.603-1 - Fixed-price contracts-complete termination.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Contractor certifies that all contract termination inventory (including scrap) has been retained or acquired... certificate stating (i) that all subcontract termination inventory (including scrap) has been retained or... certifies that all items of termination inventory, the costs of which were used in arriving at the amount of...

48 CFR 49.603-2 - Fixed-price contracts-partial termination.

Code of Federal Regulations, 2010 CFR

2010-10-01

... certifies that all contract termination inventory (including scrap) has been retained or acquired by the... stating (i) that all subcontract termination inventory (including scrap) has been retained or acquired by... certifies that all items of termination inventory, the costs of which were used in arriving at the amount of...

48 CFR 49.603-3 - Cost-reimbursement contracts-complete termination, if settlement includes cost.

Code of Federal Regulations, 2010 CFR

2010-10-01

... following: (1) The Contractor certifies that all contract termination inventory (including scrap) has been... the Contractor a certificate stating (i) that all subcontract termination inventory (including scrap... in its proposal. (3) The Contractor certifies that all items of termination inventory, the costs of...

15 CFR 930.115 - Termination of mediation.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Termination of mediation. 930.115... MANAGEMENT FEDERAL CONSISTENCY WITH APPROVED COASTAL MANAGEMENT PROGRAMS Secretarial Mediation § 930.115 Termination of mediation. Mediation shall terminate: (a) At any time the Federal and State agencies agree to a...

The hemorrhoid laser procedure technique vs rubber band ligation: a randomized trial comparing 2 mini-invasive treatments for second- and third-degree hemorrhoids.

PubMed

Giamundo, Paolo; Salfi, Raffaele; Geraci, Maria; Tibaldi, Livio; Murru, Luisa; Valente, Marco

2011-06-01

Hemorrhoid laser procedure is a new laser procedure for outpatient treatment of hemorrhoids in which hemorrhoidal arterial flow feeding the hemorrhoidal plexus is stopped by means of Doppler-guided laser coagulation. Our aim was to compare the hemorrhoid laser procedure with rubber band ligation for outpatient treatment of symptomatic hemorrhoids with moderate mucosal prolapse. This was a randomized controlled trial with balanced allocation to hemorrhoid laser procedure or rubber band ligation, with stratification by study center. This study was conducted at 2 teaching hospitals in Italy. Patients with symptomatic grade II or grade III hemorrhoids with minimal mucosal prolapse were eligible for the study. In the hemorrhoid laser procedure operation, a Doppler probe was inserted into the anal canal through a dedicated disposable proctoscope to identify the terminal branches of superior hemorrhoidal arteries approximately 3 cm above the dentate line. Five pulsed laser shots were delivered to each identified artery through the proctoscope to close the terminal branches. The procedure was repeated for each artery through clockwise rotation of the proctoscope. Absence of a Doppler signal after treatment confirmed arterial coagulation. Rubber band ligation was performed by positioning rubber bands at the base of left lateral, right anterior, and right posterior piles. No anesthesia was given for either technique. Operative time, complications, postoperative pain (visual analog scale), postoperative downgrading of hemorrhoids, resolution of symptoms, and quality of life were evaluated. A total of 60 patients (35 women, 25 men; mean age, 46 years) entered the trial and were analyzed. No significant differences between rubber band ligation and hemorrhoid laser procedure were observed in operative time or intraoperative morbidity. The median postoperative pain score was 2.9 (range, 1-5) with rubber band ligation vs 1.1 (range, 0-2) for hemorrhoid laser procedure (P < .001). At 6 months, resolution of symptoms was observed in 16 patients (53%) with ligation vs 27 (90%) with hemorrhoid laser procedure (P < .001), and reduction of hemorrhoids by at least 1 grade was observed in 12 patients (40%) with ligation vs 24 (80%) with hemorrhoid laser procedure (P < .001). Significantly higher quality of life was seen in the hemorrhoid laser procedure group (P = .002). Follow-up was not longer than 1 year (median, 6 mo). Despite higher cost, the hemorrhoid laser procedure technique was more effective than rubber band ligation in reducing postoperative pain, resolving symptoms, and improving quality of life in patients with grade II or III hemorrhoids with incomplete mucosal prolapse.

Two regimes in the magnetic field response of superconducting MgB2

NASA Astrophysics Data System (ADS)

Kohen, A.; Giubileo, F.; Proslier, Th.; Bobba, F.; Cucolo, A. M.; Sacks, W.; Noat, Y.; Troianovski, A.; Roditchev, D.

2007-05-01

Using Scanning Tunneling Microscope at low temperature we explore the superconducting phase diagram in the π-band of the two-band superconductor MgB2. In this band the peculiar shape of the local tunneling spectra and their dynamics in the magnetic field reveal the complex character of the quasiparticle density of states (DOS). The gap in the DOS is first rapidly filled with states in raising the magnetic field up to 0.5 T and then slowly approaches the normal state value: the gap is observed up to 2 T. Such a change in the DOS dynamics suggests the existence of two terms in the DOS of the π-band: a first one, reflecting an intrinsic superconductivity in the band and a second one, originating from an inter-band coupling to the σ-band. Our findings allow a deeper understanding of the unique phase diagram of MgB2.

N2O vibration-rotation parameters derived from measurements in the 900-1090- and 1580-2380/cm regions

NASA Technical Reports Server (NTRS)

Toth, Robert A.

1987-01-01

Fourier-transform spectrometric measurements of the N2O IR spectrum in the 900-1090 and 1580-2380/cm regions were obtained at a 0.005/cm resolution, and line frequencies of eight species for several ground state bands and hot bands are analyzed to obtain values of band centers and upper-state effective rotational constants. Several bands are reported for the first time. Least-squares fits for the 0400-0000, 0420(e)-0000, and 0510-0110 bands of the (N-14)2O-16 species suggest perturbation of the high-J levels of the upper states. Resonance interactions were noted in transitions including the 1001-1000 bands of (N-14)2O-16 and N-15N-14O-16.

Electronic structure and optical properties of defect chalcopyrite HgGa2Se4

NASA Astrophysics Data System (ADS)

Gabrelian, B. V.; Lavrentyev, A. A.; Vu, Tuan V.; Parasyuk, O. V.; Khyzhun, O. Y.

2018-01-01

We report on studies from an experimental and theoretical viewpoint of the electronic structure of mercury digallium selenide, HgGa2Se4, a very promising optoelectronic material. In particular, the method of X-ray photoelectron spectroscopy (XPS) was used to evaluate binding energies of the constituent element core electrons and the shape of the valence band for pristine and Ar+-ion bombarded surfaces of HgGa2Se4 single crystal. First principles band-structure calculations were performed in the present work using the augmented plane wave + local orbitals (APW+lo). These calculations indicate that the Se 4p states are the main contributors at the top and in the upper portion of the valence band with slightly smaller contributions of the Ga 4p states in the upper portion of the band as well. Further, the central portion of the valence band is determined mainly by contributions of the Ga 4s states, and the Hg 5d states are the principal contributors to the bottom of the valence band. These theoretical data are in fair agreement when matching on a common energy scale of the X-ray emission bands giving information on the energy distribution of the Se 4p and Ga 4p states and the XPS valence-band spectrum of the HgGa2Se4 crystal. The principal optical constants are elucidated from the DFT calculations.

Detection of Prosecretory Mitogen Lacritin in Nonprimate Tears Primarily as a C-Terminal-Like Fragment

PubMed Central

Laurie, Diane E.; Splan, Rebecca K.; Green, Kari; Still, Katherine M.; McKown, Robert L.; Laurie, Gordon W.

2012-01-01

Purpose. Lacritin is a human tear glycoprotein that promotes basal tear protein secretion in cultured rat lacrimal acinar cells and proliferation of subconfluent human corneal epithelial cells. When topically added to rabbit eyes, lacritin promotes basal tearing. Despite these activities on several species, lacritin's presence in nonprimate tears or other tissues has not been explored. Here we probed for lacritin in normal horse tears. Methods. Sequences were collected from the Ensembl genomic alignment of human LACRT gene with high-quality draft horse genome (EquCab2.0) and analyzed. Normal horse tears were collected and assayed by Western blotting, ELISA, and mass spectrometry. Newly generated rabbit antibodies, respectively, against N- and C-terminal regions of human lacritin were employed. Results. Identity was 75% and 45%, respectively, at nucleotide and protein levels. Structural features were conserved, including a C-terminal amphipathic α-helix. Anti-C-terminal antibodies strongly detected a ∼13 kDa band in horse tears that was validated by mass spectrometry. In human tears, the same antibody detected uncleaved lacritin (∼24 kDa) strongly and C-terminal fragments of ∼13 and ∼11 kDa weakly. Anti-N-terminal antibodies were slightly reactive with a ∼24 kDa horse antigen and showed no reaction with the anti-C-terminal–reactive ∼13 kDa species. Similar respective levels of horse C-terminal versus N-terminal immunoreactivity were apparent by ELISA. Conclusions. Lacritin is present in horse tears, largely as a C-terminal fragment homologous to the mitogenic and bactericidal region in human lacritin, suggesting potential benefit in corneal wound repair. PMID:22871838

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.

Pressure-induced emission band separation of the hybridized local and charge transfer excited state in a TPE-based crystal.

PubMed

Liu, Xuedan; Li, Aisen; Xu, Weiqing; Ma, Zhiyong; Jia, Xinru

2018-05-08

We herein report a newly synthesized simple molecule, named TPE[double bond, length as m-dash]C4, with twisted D-A structure. TPE[double bond, length as m-dash]C4 showed two intrinsic emission bands ascribed to the locally excited (LE) state and the intramolecular charge transfer (ICT) state, respectively. In the crystal state, the LE emission band is usually observed. However, by applying hydrostatic pressure to the powder sample and the single crystal sample of TPE[double bond, length as m-dash]C4, dual-fluorescence (445 nm and 532 nm) was emerged under high pressure, owing to the pressure-induced emission band separation of the hybridized local and charge transfer excited state (HLCT). It is found that the emission of TPE[double bond, length as m-dash]C4 is generally determined by the ratio of the LE state to the ICT state. The ICT emission band is much more sensitive to the external pressure than the LE emission band. The HLCT state leads to a sample with different responsiveness to grinding and hydrostatic pressure. This study is of significance in the molecular design of such D-A type molecules and in the control of photoluminescence features by molecular structure. Such results are expected to pave a new way to further understand the relationship between the D-A molecular structure and stimuli-responsive properties.

28 CFR 51.5 - Termination of coverage (bailout).

Code of Federal Regulations, 2010 CFR

2010-07-01

... OF SECTION 5 OF THE VOTING RIGHTS ACT OF 1965, AS AMENDED General Provisions § 51.5 Termination of coverage (bailout). A covered jurisdiction or a political subdivision of a covered State may terminate the...

Time-resolved infrared and resonance Raman studies of benzil. Vibrational analysis and structures of the excited states

NASA Astrophysics Data System (ADS)

Mizuno, Misao; Iwata, Koichi; Takahashi, Hiroaki

2003-12-01

Structures of the S 1 and T 1 states of benzil are examined based on the experimental results from nanosecond time-resolved infrared spectroscopy and picosecond time-resolved Raman spectroscopy. Nanosecond time-resolved infrared spectra of the T 1 state of benzil as well as its three isotopically substituted analogues were measured in carbon tetrachloride. The observed infrared bands of T 1 benzil were assigned based on the frequency shifts on isotopic ( 18O, and deuteration) substitutions. The infrared band at 1312 cm -1 is assigned to the CO anti-symmetric stretch vibration. An infrared band that has large contribution from the central C-C stretch is not observed. Picosecond time-resolved resonance Raman spectra of the S 1 state of benzil were also measured. It has been reported that after the photoexcitation, the benzil molecule shows an ultrafast conformational change in the S 1 state. The observed resonance Raman bands are attributable to the vibrations of the relaxed form of the S 1 state. By comparing the Raman and infrared spectra of the S 0, S 1, and T 1 states of benzil, the structures of benzil in the excited states are discussed. Upon going from the S 0 state to the S 1 or T 1 state, the bond order of the CO bond decreases while that of the central C-C bond increases. Although several ground-state bands appear in both the infrared and Raman spectra, there is no band observed simultaneously in the infrared and Raman spectra of the T 1 state, except for bands attributable to the phenyl ring vibrations. We conclude that T 1 benzil has the inversion center that arises from the trans-planar structure. The spectral pattern of the resonance Raman scattering of the relaxed S 1 state is very similar to that of the T 1 state. This implies that the molecular structure of the relaxed S 1 state is similar to that of the T 1 state. The structure of the relaxed form of the S 1 state is also considered to be trans-planar.

Resonant tunneling based graphene quantum dot memristors.

PubMed

Pan, Xuan; Skafidas, Efstratios

2016-12-08

In this paper, we model two-terminal all graphene quantum dot (GQD) based resistor-type memory devices (memristors). The resistive switching is achieved by resonant electron tunneling. We show that parallel GQDs can be used to create multi-state memory circuits. The number of states can be optimised with additional voltage sources, whilst the noise margin for each state can be controlled by appropriately choosing the branch resistance. A three-terminal GQD device configuration is also studied. The addition of an isolated gate terminal can be used to add further or modify the states of the memory device. The proposed devices provide a promising route towards volatile memory devices utilizing only atomically thin two-dimensional graphene.

Experimentally demonstrate the surface state and optical topological phase transition of one dimensional hyperbolic metamaterials in Otto and KR configuration (Conference Presentation)

NASA Astrophysics Data System (ADS)

Wei, Chih Chung; Un, Leng-Wai; Yen, Ta-Jen

2017-05-01

One-dimension hyperbolic metamaterials (1DHMMs) possess marvelous and considerable applications: hyperlens, spontaneous emission engineering and nonlinear optics. Conventionally, effective medium theory, which is only valid for long wavelength limit, was used to predict and analyze the optical properties and applications. In our previous works, we considered a binary 1DHMM which consists of alternative metallic and dielectric layers, and rigorously demonstrated the existence of surface states and bulk-interface correspondence with the plasmonic band theory from the coupled surface plasmon point of view. In the plasmonic band structure, we can classify 1DHMMs into two classes: metallic-like and dielectric-like, depending on the formation of the surface states with dielectric and metallic material, respectively. Band crossing exists only when the dielectric layers are thicker than the metallic ones, which is independent from the dielectric constants. Furthermore, the 1DHMMs are all metallic-like without band crossing. On the other hand, the 1DHMMs with band crossing are metal-like before the band crossing point, while they are dielectric-like after the band crossing point. In this work, we measure the surface states formed by dielectric material and 1DHMMs with band crossing in Otto configuration. With white light source and fixed incident angle, we measure the reflectance to investigate the existence of the surface states of 1DHMMs with various thickness ratio of metallic to dielectric layers. Conclusively, our results show that the surface states of 1DHMMs exist only when the thickness ratio is larger than 0.15. The disappearance of the surface states indicates the topological phase transition of 1DHMMs. Our experimental results will benefit new applications for manipulating light on the surface of hyperbolic metamaterials.

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

Spin-polarized surface resonances accompanying topological surface state formation

PubMed Central

Jozwiak, Chris; Sobota, Jonathan A.; Gotlieb, Kenneth; Kemper, Alexander F.; Rotundu, Costel R.; Birgeneau, Robert J.; Hussain, Zahid; Lee, Dung-Hai; Shen, Zhi-Xun; Lanzara, Alessandra

2016-01-01

Topological insulators host spin-polarized surface states born out of the energetic inversion of bulk bands driven by the spin-orbit interaction. Here we discover previously unidentified consequences of band-inversion on the surface electronic structure of the topological insulator Bi2Se3. By performing simultaneous spin, time, and angle-resolved photoemission spectroscopy, we map the spin-polarized unoccupied electronic structure and identify a surface resonance which is distinct from the topological surface state, yet shares a similar spin-orbital texture with opposite orientation. Its momentum dependence and spin texture imply an intimate connection with the topological surface state. Calculations show these two distinct states can emerge from trivial Rashba-like states that change topology through the spin-orbit-induced band inversion. This work thus provides a compelling view of the coevolution of surface states through a topological phase transition, enabled by the unique capability of directly measuring the spin-polarized unoccupied band structure. PMID:27739428

Electronic Structures of Free-Standing Nanowires made from Indirect Bandgap Semiconductor Gallium Phosphide

PubMed Central

Liao, Gaohua; Luo, Ning; Chen, Ke-Qiu; Xu, H. Q.

2016-01-01

We present a theoretical study of the electronic structures of freestanding nanowires made from gallium phosphide (GaP)—a III-V semiconductor with an indirect bulk bandgap. We consider [001]-oriented GaP nanowires with square and rectangular cross sections, and [111]-oriented GaP nanowires with hexagonal cross sections. Based on tight binding models, both the band structures and wave functions of the nanowires are calculated. For the [001]-oriented GaP nanowires, the bands show anti-crossing structures, while the bands of the [111]-oriented nanowires display crossing structures. Two minima are observed in the conduction bands, while the maximum of the valence bands is always at the Γ-point. Using double group theory, we analyze the symmetry properties of the lowest conduction band states and highest valence band states of GaP nanowires with different sizes and directions. The band state wave functions of the lowest conduction bands and the highest valence bands of the nanowires are evaluated by spatial probability distributions. For practical use, we fit the confinement energies of the electrons and holes in the nanowires to obtain an empirical formula. PMID:27307081

31 CFR 215.12 - Supersession, amendment and termination provisions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... DISTRICT OF COLUMBIA, STATE, CITY AND COUNTY INCOME OR EMPLOYMENT TAXES BY FEDERAL AGENCIES Withholding... prior agreement between the Secretary of the Treasury and a State or city pursuant to 5 U.S.C. 5516...) This agreement may be terminated as to a specific State or city or county which is a party to this...

31 CFR 215.12 - Supersession, amendment and termination provisions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... DISTRICT OF COLUMBIA, STATE, CITY AND COUNTY INCOME OR EMPLOYMENT TAXES BY FEDERAL AGENCIES Withholding... prior agreement between the Secretary of the Treasury and a State or city pursuant to 5 U.S.C. 5516...) This agreement may be terminated as to a specific State or city or county which is a party to this...

Direct time-domain observation of attosecond final-state lifetimes in photoemission from solids

DOE PAGES

Tao, Z.; Chen, C.; Szilvasi, T.; ...

2016-06-01

Attosecond spectroscopic techniques have made it possible to measure differences in transport times for photoelectrons from localized core levels and delocalized valence bands in solids. Here, we report the application of attosecond pulse trains to directly and unambiguously measure the difference in lifetimes between photoelectrons born into free electron–like states and those excited into unoccupied excited states in the band structure of nickel (111). An enormous increase in lifetime of 212 ± 30 attoseconds occurs when the final state coincides with a short-lived excited state. Moreover, a strong dependence of this lifetime on emission angle is directly related to themore » final-state band dispersion as a function of electron transverse momentum. Our finding underscores the importance of the material band structure in determining photoelectron lifetimes and corresponding electron escape depths.« less

X-ray spectra and electronic structure of the Ca3Ga2Ge3О12 compound

NASA Astrophysics Data System (ADS)

Shcherba, I. D.; Kostyk, L. V.; Noga, H.; Bekenov, L. V.; Uskokovich, D.; Jatsyk, B. M.

2017-09-01

The band structure of Ca3Ga2Ge3О12 with the garnet structure has been determined for the first time by X-ray emission and photoelectron spectroscopy. It has been established that the bottom of the valence band is formed by Ge d states, which are not dominant in the chemical bonding. Strong hybridization of oxygen 2s states with 4p states of Ga and Ge revealed by the presence of an extra structure in the X-ray emission spectra has been found. The middle of the valence band has been demonstrated to be occupied by d states of Ga, while Ga and Ge 4рstates with a considerable admixture of oxygen 2p states form the top of the valence band.

Solid state safety jumper cables

DOEpatents

Kronberg, James W.

1993-01-01

Solid state jumper cables for connecting two batteries in parallel, having two bridge rectifiers for developing a reference voltage, a four-input decoder for determining which terminals are to be connected based on a comparison of the voltage at each of the four terminals to the reference voltage, and a pair of relays for effecting the correct connection depending on the determination of the decoder. No connection will be made unless only one terminal of each battery has a higher voltage than the reference voltage, indicating "positive" terminals, and one has a lower voltage than the reference voltage, indicating "negative" terminals, and that, therefore, the two high voltage terminals may be connected and the two lower voltage terminals may be connected. Current flows once the appropriate relay device is closed. The relay device is preferably a MOSFET (metal oxide semiconductor field effect transistor) combined with a series array of photodiodes that develop MOSFET gate-closing potential when the decoder output causes an LED to light.

Solid state safety jumper cables

DOEpatents

Kronberg, J.W.

1993-02-23

Solid state jumper cables for connecting two batteries in parallel, having two bridge rectifiers for developing a reference voltage, a four-input decoder for determining which terminals are to be connected based on a comparison of the voltage at each of the four terminals to the reference voltage, and a pair of relays for effecting the correct connection depending on the determination of the decoder. No connection will be made unless only one terminal of each battery has a higher voltage than the reference voltage, indicating positive'' terminals, and one has a lower voltage than the reference voltage, indicating negative'' terminals, and that, therefore, the two high voltage terminals may be connected and the two lower voltage terminals may be connected. Current flows once the appropriate relay device is closed. The relay device is preferably a MOSFET (metal oxide semiconductor field effect transistor) combined with a series array of photodiodes that develop MOSFET gate-closing potential when the decoder output causes an LED to light.

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.

ATS-6 - Television Relay Using Small Terminals Experiment

NASA Technical Reports Server (NTRS)

Miller, J. E.

1975-01-01

The Television Relay Using Small Terminals (TRUST) Experiment was designed to advance and promote the technology of broadcasting satellites. A constant envelope television FM signal was transmitted at C band to the ATS-6 earth coverage horn and retransmitted at 860 MHz through the 9-m antenna to a low-cost direct-readout ground station. The experiment demonstrated that high-quality television and audio can be received by low-cost direct-receive ground stations. Predetection bandwidths significantly less than predicted by Carson's rule can be utilized with minimal degradation of either monochrome or color pictures. Two separate techniques of dual audio channel transmission have been demonstrated to be suitable for low-cost applications.

Loss of predominant Shank3 isoforms results in hippocampus-dependent impairments in behavior and synaptic transmission.

PubMed

Kouser, Mehreen; Speed, Haley E; Dewey, Colleen M; Reimers, Jeremy M; Widman, Allie J; Gupta, Natasha; Liu, Shunan; Jaramillo, Thomas C; Bangash, Muhammad; Xiao, Bo; Worley, Paul F; Powell, Craig M

2013-11-20

The Shank3 gene encodes a scaffolding protein that anchors multiple elements of the postsynaptic density at the synapse. Previous attempts to delete the Shank3 gene have not resulted in a complete loss of the predominant naturally occurring Shank3 isoforms. We have now characterized a homozygous Shank3 mutation in mice that deletes exon 21, including the Homer binding domain. In the homozygous state, deletion of exon 21 results in loss of the major naturally occurring Shank3 protein bands detected by C-terminal and N-terminal antibodies, allowing us to more definitively examine the role of Shank3 in synaptic function and behavior. This loss of Shank3 leads to an increased localization of mGluR5 to both synaptosome and postsynaptic density-enriched fractions in the hippocampus. These mice exhibit a decrease in NMDA/AMPA excitatory postsynaptic current ratio in area CA1 of the hippocampus, reduced long-term potentiation in area CA1, and deficits in hippocampus-dependent spatial learning and memory. In addition, these mice also exhibit motor-coordination deficits, hypersensitivity to heat, novelty avoidance, altered locomotor response to novelty, and minimal social abnormalities. These data suggest that Shank3 isoforms are required for normal synaptic transmission/plasticity in the hippocampus, as well as hippocampus-dependent spatial learning and memory.

Electric Quadrupole E2- Transitions of 170-174 Yb Isotopes

NASA Astrophysics Data System (ADS)

Abu El Sheikh, Mohd Kh. M.; Okhunov, Abdurahim A.; Usmanov, Ph. N.; Hassan, Torla HJ

2017-12-01

The non-adiabatic effects which is manifested in the electric properties of low-lying states of even-even deformed nuclei are studied. A simple phenomenological model which takes into account the Coriolis mixing of {K}π ={0}n+,{2}n+ and {K}π ={1}ν + state bands. The Calculations for isotopes 170-174 Yb, are carried out. The reduced probability of electric quadrupole transitions from the states {0}ν + and {2}ν + - bands to the ground (gr) state band is calculated and non adiabatic effect is discussed. The ratio of E2- transitions RIK from {0}2+, {0}3+, {2}1+, and {2}2+ bands are calculated and compared with the experimental data.

Density-functional theory molecular dynamics simulations of a-HfO2/a-SiO2/SiGe and a-HfO2/a-SiO2/Ge with a-SiO2 and a-SiO suboxide interfacial layers

NASA Astrophysics Data System (ADS)

Chagarov, Evgueni A.; Kavrik, Mahmut S.; Fang, Ziwei; Tsai, Wilman; Kummel, Andrew C.

2018-06-01

Comprehensive Density-Functional Theory (DFT) Molecular Dynamics (MD) simulations were performed to investigate interfaces between a-HfO2 and SiGe or Ge semiconductors with fully-stoichiometric a-SiO2 or sub-oxide SiO interlayers. The electronic structure of the selected stacks was calculated with a HSE06 hybrid functional. Simulations were performed before and after hydrogen passivation of residual interlayer defects. For the SiGe substrate with Ge termination prior to H passivation, the stacks with a-SiO suboxide interlayer (a-HfO2/a-SiO/SiGe) demonstrate superior electronic properties and wider band-gaps than the stacks with fully coordinated a-SiO2 interlayers (a-HfO2/a-SiO2/SiGe). After H passivation, most of the a-HfO2/a-SiO2/SiGe defects are passivated. To investigate effect of random placement of Si and Ge atoms additional simulations with a randomized SiGe slab were performed demonstrating improvement of electronic structure. For Ge substrates, before H passivation, the stacks with a SiO suboxide interlayer (a-HfO2/a-SiO/Ge) also demonstrate wider band-gaps than the stacks with fully coordinated a-SiO2 interlayers (a-HfO2/a-SiO2/Ge). However, even for a-HfO2/a-SiO/Ge, the Fermi level is shifted close to the conduction band edge (CBM) consistent with Fermi level pinning. Again, after H passivation, most of the a-HfO2/a-SiO2/Ge defects are passivated. The stacks with fully coordinated a-SiO2 interlayers have much stronger deformation and irregularity in the semiconductor (SiGe or Ge) upper layers leading to multiple under-coordinated atoms which create band-edge states and decrease the band-gap prior to H passivation.

The localized effect of the Bi level on the valence band in the dilute bismuth GaBixAs1-x alloy

NASA Astrophysics Data System (ADS)

Zhao, Chuan-Zhen; Zhu, Min-Min; Wang, Jun; Wang, Sha-Sha; Lu, Ke-Qing

2018-05-01

The research on the temperature dependence of the band gap energy of the dilute bismuth GaBixAs1-x alloy has been done. It is found that its temperature insensitiveness is due to the enhanced localized character of the valence band state and the small decrease of the temperature coefficient for the conduction band minimum (CBM). The enhanced localized character of the valence band state is the main factor. In order to describe the localized effect of the Bi levels on the valence band, the localized energy is introduced into the Varshni's equation. It is found that the effect of the localized Bi level on the valence band becomes strong with increasing Bi content. In addition, it is found that the pressure dependence of the band gap energy of GaBixAs1-x does not seem to be influenced by the localized Bi levels. It is due to two factors. One is that the pressure dependence of the band gap energy is mainly determined by the D CBM of GaBixAs1-x. The D CBM of GaBixAs1-x is not influenced by the localized Bi levels. The other is that the small variation of the pressure coefficient for the D valence band maximum (VBM) state of GaBixAs1-x can be cancelled by the variation of the pressure coefficient for the D CBM state of GaBixAs1-x.

A survey of methods of feasible directions for the solution of optimal control problems

NASA Technical Reports Server (NTRS)

Polak, E.

1972-01-01

Three methods of feasible directions for optimal control are reviewed. These methods are an extension of the Frank-Wolfe method, a dual method devised by Pironneau and Polack, and a Zontendijk method. The categories of continuous optimal control problems are shown as: (1) fixed time problems with fixed initial state, free terminal state, and simple constraints on the control; (2) fixed time problems with inequality constraints on both the initial and the terminal state and no control constraints; (3) free time problems with inequality constraints on the initial and terminal states and simple constraints on the control; and (4) fixed time problems with inequality state space contraints and constraints on the control. The nonlinear programming algorithms are derived for each of the methods in its associated category.

Termination of aquired and natural immunological tolerance with specific complexes

PubMed Central

1975-01-01

It was possible to terminate the induced unresponsive state to bovine serum albumin (BSA) and the natural unresponsive state to autologous thyroglobulin in rabbits (RTg) by immunization with complexes composed of heterologous cross-reacting antibody and the tolerated antigens. The unresponsive state was terminated in rabbits made unresponsive by neonatal injections of BSA and then 3 mo later injected with complexes composed of BSA and guinea pig antihuman serum albumin. This termination was manifested by the presence of anti-BSA plaque-forming cells. Similarly, the natural unresponsive state was terminated in adult rabbits injected with complexes between RTg and guinea pig antibovine thyroglobulin (BTg) in that thyroid lesions and circulating anti-RTg were produced. The results can be best explained by the presence of unresponsive T cells and competent B cells, where the guinea pig gamma globulin (antibody) activates T cells specific for the guinea pig gamma globulin portion of the complexes and thus permits stimulation of B cells competent to the exposed determinants of the tolerated (BSA or RTg) portion of the complexes. The detailed mechanism for the activation of B cells in tolerant animals is discussed. PMID:1095680

Current and Future Tests of the Algebraic Cluster Model of12C

NASA Astrophysics Data System (ADS)

Gai, Moshe

2017-07-01

A new theoretical approach to clustering in the frame of the Algebraic Cluster Model (ACM) has been developed. It predicts, in12C, rotation-vibration structure with rotational bands of an oblate equilateral triangular symmetric spinning top with a D 3h symmetry characterized by the sequence of states: 0+, 2+, 3-, 4±, 5- with a degenerate 4+ and 4- (parity doublet) states. Our newly measured {2}2+ state in12C allows the first study of rotation-vibration structure in12C. The newly measured 5- state and 4- states fit very well the predicted ground state rotational band structure with the predicted sequence of states: 0+, 2+, 3-, 4±, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a D 3h symmetry is characteristic of triatomic molecules, but it is observed in the ground state rotational band of12C for the first time in a nucleus. We discuss predictions of the ACM of other rotation-vibration bands in12C such as the (0+) Hoyle band and the (1-) bending mode with prediction of (“missing 3- and 4-”) states that may shed new light on clustering in12C and light nuclei. In particular, the observation (or non observation) of the predicted (“missing”) states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha particles composing the Hoyle state at 7.6542 MeV in12C. We discuss proposed research programs at the Darmstadt S- DALINAC and at the newly constructed ELI-NP facility near Bucharest to test the predictions of the ACM in isotopes of carbon.

High-resolution infrared spectrum of triacetylene: The ν5 state revisited and new vibrational states

NASA Astrophysics Data System (ADS)

Doney, K. D.; Zhao, D.; Linnartz, H.

2015-10-01

New data are presented that follow from a high-resolution survey, from 3302 to 3352 cm-1, through expanding acetylene plasma, and covering the Csbnd H asymmetric (ν5) fundamental band of triacetylene (HC6H). Absorption signals are recorded using continuous wave cavity ring-down spectroscopy (cw-CRDS). A detailed analysis of the resulting spectra allows revisiting the molecular parameters of the ν5 fundamental band in terms of interactions with a perturbing state, which is observed for the first time. Moreover, four fully resolved hot bands (501 1011, 501 1111, 501 1311, and 101 801 1110), with band origins at 3328.5829(2), 3328.9994(2), 3328.2137(2) and 3310.8104(2) cm-1, respectively, are reported for the first time. These involve low lying bending vibrations that have been studied previously, which guarantees unambiguous identifications. Combining available data allows to derive accurate molecular parameters, both for the ground state as well as the excited states involved in the bands.

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.

Design of a K/Q-Band Beacon Receiver for the Alphasat Technology Demonstration Payload (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.

Weyl nodes in Andreev spectra of multiterminal Josephson junctions: Chern numbers, conductances, and supercurrents

NASA Astrophysics Data System (ADS)

Xie, Hong-Yi; Vavilov, Maxim G.; Levchenko, Alex

2018-02-01

We consider mesoscopic four-terminal Josephson junctions and study emergent topological properties of the Andreev subgap bands. We use symmetry-constrained analysis for Wigner-Dyson classes of scattering matrices to derive band dispersions. When the scattering matrix of the normal region connecting superconducting leads is energy independent, the determinant formula for Andreev spectrum can be reduced to a palindromic equation that admits a complete analytical solution. Band topology manifests with an appearance of the Weyl nodes which serve as monopoles of finite Berry curvature. The corresponding fluxes are quantified by Chern numbers that translate into a quantized nonlocal conductance that we compute explicitly for the time-reversal-symmetric scattering matrix. The topological regime can also be identified by supercurrents as Josephson current-phase relationships exhibit pronounced nonanalytic behavior and discontinuities near Weyl points that can be controllably accessed in experiments.

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.

Intrinsic properties of high-spin band structures in triaxial nuclei

NASA Astrophysics Data System (ADS)

Jehangir, S.; Bhat, G. H.; Sheikh, J. A.; Palit, R.; Ganai, P. A.

2017-12-01

The band structures of 68,70Ge, 128,130,132,134Ce and 132,134,136,138Nd are investigated using the triaxial projected shell model (TPSM) approach. These nuclei depict forking of the ground-state band into several s-bands and in some cases, both the lowest two observed s-bands depict neutron or proton character. It was discussed in our earlier work that this anomalous behaviour can be explained by considering γ-bands based on two-quasiparticle configurations. As the parent band and the γ-band built on it have the same intrinsic structure, g-factors of the two bands are expected to be similar. In the present work, we have undertaken a detailed investigation of g-factors for the excited band structures of the studied nuclei and the available data for a few high-spin states are shown to be in fair agreement with the predicted values.

78 FR 10643 - Self-Regulatory Organizations; New York Stock Exchange LLC; Notice of Filing and Immediate...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-14

... Band.\\14\\ Trading for an NMS stock exits a Limit State if, within 15 seconds of entering the Limit... Bid (Offer) is below (above) the Lower (Upper) Price Band and the NMS Stock is not in a Limit State...) Price Band and the NMS Stock is not in a Limit State; and (ii) trading in that NMS Stock deviates from...

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Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-14

... Band.\\14\\ Trading for an NMS stock exits a Limit State if, within 15 seconds of entering the Limit...) is below (above) the Lower (Upper) Price Band and the NMS Stock is not in a Limit State. For example...) Price Band and the NMS Stock is not in a Limit State; and (ii) trading in that NMS Stock deviates from...

SCAILET: An intelligent assistant for satellite ground terminal operations

NASA Technical Reports Server (NTRS)

Shahidi, A. K.; Crapo, J. A.; Schlegelmilch, R. F.; Reinhart, R. C.; Petrik, E. J.; Walters, J. L.; Jones, R. E.

1993-01-01

NASA Lewis Research Center has applied artificial intelligence to an advanced ground terminal. This software application is being deployed as an experimenter interface to the link evaluation terminal (LET) and was named Space Communication Artificial Intelligence for the Link Evaluation Terminal (SCAILET). The high-burst-rate (HBR) LET provides 30-GHz-transmitting and 20-GHz-receiving, 220-Mbps capability for wide band communications technology experiments with the Advanced Communication Technology Satellite (ACTS). The HBR-LET terminal consists of seven major subsystems. A minicomputer controls and monitors these subsystems through an IEEE-488 or RS-232 protocol interface. Programming scripts (test procedures defined by design engineers) configure the HBR-LET and permit data acquisition. However, the scripts are difficult to use, require a steep learning curve, are cryptic, and are hard to maintain. This discourages experimenters from utilizing the full capabilities of the HBR-LET system. An intelligent assistant module was developed as part of the SCAILET software. The intelligent assistant addresses critical experimenter needs by solving and resolving problems that are encountered during the configuring of the HBR-LET system. The intelligent assistant is a graphical user interface with an expert system running in the background. In order to further assist and familiarize an experimenter, an on-line hypertext documentation module was developed and included in the SCAILET software.

Direct Data Distribution From Low-Earth Orbit

NASA Technical Reports Server (NTRS)

Budinger, James M.; Fujikawa, Gene; Kunath, Richard R.; Nguyen, Nam T.; Romanofsky, Robert R.; Spence, Rodney L.

1997-01-01

NASA Lewis Research Center (LeRC) is developing the space and ground segment technologies necessary to demonstrate a direct data distribution (1)3) system for use in space-to-ground communication links from spacecraft in low-Earth orbit (LEO) to strategically located tracking ground terminals. The key space segment technologies include a K-band (19 GHz) MMIC-based transmit phased array antenna, and a multichannel bandwidth- and power-efficient digital encoder/modulate with an aggregate data rate of 622 Mb/s. Along with small (1.8 meter), low-cost tracking terminals on the ground, the D3 system enables affordable distribution of data to the end user or archive facility through interoperability with commercial terrestrial telecommunications networks. The D3 system is applicable to both government and commercial science and communications spacecraft in LEO. The features and benefits of the D3 system concept are described. Starting with typical orbital characteristics, a set of baseline requirements for representative applications is developed, including requirements for onboard storage and tracking terminals, and sample link budgets are presented. Characteristics of the transmit array antenna and digital encoder/modulator are described. The architecture and components of the tracking terminal are described, including technologies for the next generation terminal. Candidate flights of opportunity for risk mitigation and space demonstration of the D3 features are identified.

Spectrally resolved localized states in GaAs 1– xBi x

DOE PAGES

Christian, Theresa M.; Alberi, Kirstin; Beaton, Daniel A.; ...

2017-02-01

In this study, the role of localized states and their influence on the broader band structure remains a crucial question in understanding the band structure evolution in GaAs 1-xBi x. Here in this work, we present clear spectroscopic observations of recombination at several localized states in GaAs 1-xBi x. Sharp and recognizable photoluminescence features appear in multiple samples and redshift as a function of GaBi fraction between x = 0.16% and 0.4% at a linearized rate of 34 meV per % Bi, weaker than the redshift associated with band-to-band recombination. Interpreting these results in terms of radiative recombination between localizedmore » holes and free electrons sheds light on the relative movement of the conduction band minimum and the characteristics of localized bismuth-related trap states in GaAs 1-xBi x alloys.« less

Compton scattering studies and electronic properties of BaTiO3

NASA Astrophysics Data System (ADS)

Meena, Seema Kumari; Bapna, Komal; Heda, N. L.; Ahuja, B. L.

2018-04-01

We present the experimental momentum density of BaTiO3 measured using 20 Ci 137Cs Compton spectrometer. The experimental Compton profile (CP) has been compared with the linear combination of atomic orbitals (LCAO) based theoretical profiles for various exchange-correlation potentials. It is found that LCAO-B3PW based CP gives a better agreement with experiment than other theoretical profiles. We have also deduced the energy bands and density of states (DOS) for BaTiO3 using LCAO-B3PW scheme. The energy bands and DOS suggest an indirect band gap in the system arising due to O-2p states of valence band and Ti-3d states of conduction band. Peculiar electronic response of this system is found to be mainly due to hybridized states of Ba-5p/5s and O-2p orbitals.

Origin of band gap bowing in dilute GaAs1-xNx and GaP1-xNx alloys: A real-space view

NASA Astrophysics Data System (ADS)

Virkkala, Ville; Havu, Ville; Tuomisto, Filip; Puska, Martti J.

2013-07-01

The origin of the band gap bowing in dilute nitrogen doped gallium based III-V semiconductors is largely debated. In this paper we show the dilute GaAs1-xNx and GaP1-xNx as representative examples that the nitrogen-induced states close to the conduction band minimum propagate along the zigzag chains on the {110} planes. Thereby states originating from different N atoms interact with each other resulting in broadening of the nitrogen-induced states which narrows the band gap. Our modeling based on ab initio theoretical calculations explains the experimentally observed N concentration dependent band gap narrowing both qualitatively and quantitatively.

High-speed multicolor photometry of V834 Centaurus

NASA Technical Reports Server (NTRS)

Middleditch, John; Imamura, James N.; Wolff, Michael T.; Steiman-Cameron, Thomas Y.

1991-01-01

Results are presented of high-speed photometric observations of the Am Her object, V834 Centaurus which, during its high state, revealed the 0.3-0.9 Hz quasi-period oscillations (QPOs) with rms amplitudes of 3.3 +/-1.1 percent and 2.5 +/-0.8 percent in the V and R bands, respectively, while the U-band amplitude was consistent with zero on one night but was 2.5 +/-1.2 percent on the following night. The QPOs in the B band were always consistent with zero. The data were obtained on the nights of June 16-21, 1990, when the average V magnitude of V834 Cen was about 15.3, confirming the high-luminosity state. The dominance of the QPOs by V-band emission is in contrast to earlier studies by Larsson which found that the QPOs were dominated by emission in the B and R band, depending upon the luminosity state of V834 Cen. In all cases, the QPOs of V834 have frequencies of 0.3-0.9 Hz. It is inferred that the color of the QPOs could be highly variable between luminosity states and may be variable in the U band within the high-luminosity state.

45 CFR 1210.3-3 - Suspension.

Code of Federal Regulations, 2013 CFR

2013-10-01

... VISTA TRAINEE DESELECTION AND VOLUNTEER EARLY TERMINATION PROCEDURES VISTA Volunteer Early Termination § 1210.3-3 Suspension. (a) The ACTION State Director may suspend a Volunteer for up to 30 days in order... Volunteer. Suspension is not warranted if the State Director determines that sufficient grounds already...

45 CFR 1210.3-3 - Suspension.

Code of Federal Regulations, 2014 CFR

2014-10-01

... VISTA TRAINEE DESELECTION AND VOLUNTEER EARLY TERMINATION PROCEDURES VISTA Volunteer Early Termination § 1210.3-3 Suspension. (a) The ACTION State Director may suspend a Volunteer for up to 30 days in order... Volunteer. Suspension is not warranted if the State Director determines that sufficient grounds already...

45 CFR 1210.3-3 - Suspension.

Code of Federal Regulations, 2010 CFR

2010-10-01

... VISTA TRAINEE DESELECTION AND VOLUNTEER EARLY TERMINATION PROCEDURES VISTA Volunteer Early Termination § 1210.3-3 Suspension. (a) The ACTION State Director may suspend a Volunteer for up to 30 days in order... Volunteer. Suspension is not warranted if the State Director determines that sufficient grounds already...

45 CFR 1210.3-3 - Suspension.

Code of Federal Regulations, 2011 CFR

2011-10-01

... VISTA TRAINEE DESELECTION AND VOLUNTEER EARLY TERMINATION PROCEDURES VISTA Volunteer Early Termination § 1210.3-3 Suspension. (a) The ACTION State Director may suspend a Volunteer for up to 30 days in order... Volunteer. Suspension is not warranted if the State Director determines that sufficient grounds already...

45 CFR 1210.3-3 - Suspension.

Code of Federal Regulations, 2012 CFR

2012-10-01

... VISTA TRAINEE DESELECTION AND VOLUNTEER EARLY TERMINATION PROCEDURES VISTA Volunteer Early Termination § 1210.3-3 Suspension. (a) The ACTION State Director may suspend a Volunteer for up to 30 days in order... Volunteer. Suspension is not warranted if the State Director determines that sufficient grounds already...

46 CFR Sec. 3 - Terminal operating contract.

Code of Federal Regulations, 2011 CFR

2011-10-01

... _________, 19__, between the United States of America (herein called the “United States”), acting by and through...'s work under the provisions of this agreement the following: (1) For terminal services, an amount... first above written. (Seal) Attest: united states of america, department of transportation, maritime...

46 CFR Sec. 3 - Terminal operating contract.

Code of Federal Regulations, 2012 CFR

2012-10-01

... _________, 19__, between the United States of America (herein called the “United States”), acting by and through...'s work under the provisions of this agreement the following: (1) For terminal services, an amount... first above written. (Seal) Attest: united states of america, department of transportation, maritime...

Energies of rare-earth ion states relative to host bands in optical materials from electron photoemission spectroscopy

NASA Astrophysics Data System (ADS)

Thiel, Charles Warren

There are a vast number of applications for rare-earth-activated materials and much of today's cutting-edge optical technology and emerging innovations are enabled by their unique properties. In many of these applications, interactions between the rare-earth ion and the host material's electronic states can enhance or inhibit performance and provide mechanisms for manipulating the optical properties. Continued advances in these technologies require knowledge of the relative energies of rare-earth and crystal band states so that properties of available materials may be fully understood and new materials may be logically developed. Conventional and resonant electron photoemission techniques were used to measure 4f electron and valence band binding energies in important optical materials, including YAG, YAlO3, and LiYF4. The photoemission spectra were theoretically modeled and analyzed to accurately determine relative energies. By combining these energies with ultraviolet spectroscopy, binding energies of excited 4fN-15d and 4fN+1 states were determined. While the 4fN ground-state energies vary considerably between different trivalent ions and lie near or below the top of the valence band in optical materials, the lowest 4f N-15d states have similar energies and are near the bottom of the conduction band. As an example for YAG, the Tb3+ 4f N ground state is in the band gap at 0.7 eV above the valence band while the Lu3+ ground state is 4.7 eV below the valence band maximum; however, the lowest 4fN-15d states are 2.2 eV below the conduction band for both ions. We found that a simple model accurately describes the binding energies of the 4fN, 4fN-1 5d, and 4fN+1 states. The model's success across the entire rare-earth series indicates that measurements on two different ions in a host are sufficient to predict the energies of all rare-earth ions in that host. This information provides new insight into electron transfer transitions, luminescence quenching, and valence stability. All of these results lead to a clearer picture for the host's effect on the rare-earth ion's electron binding energies and will motivate fundamental theoretical analysis and accelerate the development of new optical materials.

Collective Band Structures in the Neutron-Rich 107,109Ru Nuclei

NASA Astrophysics Data System (ADS)

Zhu, Sheng-jiang; Gan, Cui-yun; J, Hamilton H.; A, Ramayya V.; B, Babu R. S.; M, Sakhaee; W, Ma C.; Long, Gui-lu; Deng, Jing-kang; Zhu, Ling-yan; Li, Ming; Yang, Li-ming; J, Komicki; J, Cole D.; R, Aryaeinejad; Y, Dardenne K.; M, Drigert W.; J, Rasmussen O.; M, Stoyer A.; S, Chu Y.; K, Gregorich E.; M, Mohar F.; S, Prussin G.; I, Lee Y.; N, Johnson R.; F, McGowan K.

1998-11-01

The levels in neutron-rich odd-A 107,109Ru nuclei have been investigated by using γ-γ- and γ-γ-γ-coincidence studies of the prompt γ-rays from the spontaneous fission of 252Cf. The ground state bands and the negative parity bands are identified and expanded in both nuclei. Triaxial rotor plus particle model calculations indicate the ground state bands originate from ν(d5/2 + g7/2) quasiparticle configurations and the negative parity bands are from νh11/2 orbital.

K-mixing in the doubly mid-shell nuclide 170Dy and the role of vibrational degeneracy

NASA Astrophysics Data System (ADS)

Söderström, P.-A.; Walker, P. M.; Wu, J.; Liu, H. L.; Regan, P. H.; Watanabe, H.; Doornenbal, P.; Korkulu, Z.; Lee, P.; Liu, J. J.; Lorusso, G.; Nishimura, S.; Phong, V. H.; Sumikama, T.; Xu, F. R.; Yagi, A.; Zhang, G. X.; Ahn, D. S.; Alharbi, T.; Baba, H.; Browne, F.; Bruce, A. M.; Carroll, R. J.; Chae, K. Y.; Dombradi, Zs.; Estrade, A.; Fukuda, N.; Griffin, C. J.; Ideguchi, E.; Inabe, N.; Isobe, T.; Kanaoka, H.; Kanaya, S.; Kojouharov, I.; Kondev, F. G.; Kubo, T.; Kubono, S.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lane, G. J.; Lee, E. J.; Lee, C. S.; Lotay, G.; Moon, C.-B.; Nishizuka, I.; Niţă, C. R.; Odahara, A.; Patel, Z.; Podolyák, Zs.; Roberts, O. J.; Sakurai, H.; Schaffner, H.; Shand, C. M.; Suzuki, H.; Takeda, H.; Terashima, S.; Vajta, Zs.; Valiente-Dòbon, J. J.; Xu, Z. Y.

2016-11-01

A detailed study of the structure of the doubly mid-shell nucleus 104 1 66 170 Dy has been carried out, following isomeric and β decay. We have measured the yrast band up to the spin-parity Jπ =6+ state, the K = 2γ-vibration band up to the 5+ state, a low-lying negative-parity band based on a 2- state that could be a candidate for the lowest energy octupole vibration state within this nucleus, and a candidate for the Kπ =6+ two quasi-particle isomer. This state was determined to have an excitation energy of 1643.91(23) keV and a half life of 0.99(4) μs, with a reduced hindrance for its decay to the ground-state band an order of magnitude lower than predicted by NpNn systematics. This is interpreted as being due to γ-vibrational mixing from a near degeneracy of the isomer and the 6+ state of the γ band. Furthermore, the parent nucleus 170Tb has been determined to have a half-life of 0.91 (+18-13) s with a possible spin-parity of 2-.

Time-Reversal Symmetry-Breaking Nematic Insulators near Quantum Spin Hall Phase Transitions.

PubMed

Xue, Fei; MacDonald, A H

2018-05-04

We study the phase diagram of a model quantum spin Hall system as a function of band inversion and band-coupling strength, demonstrating that when band hybridization is weak, an interaction-induced nematic insulator state emerges over a wide range of band inversion. This property is a consequence of the long-range Coulomb interaction, which favors interband phase coherence that is weakly dependent on momentum and therefore frustrated by the single-particle Hamiltonian at the band inversion point. For weak band hybridization, interactions convert the continuous gap closing topological phase transition at inversion into a pair of continuous phase transitions bounding a state with broken time-reversal and rotational symmetries. At intermediate band hybridization, the topological phase transition proceeds instead via a quantum anomalous Hall insulator state, whereas at strong hybridization interactions play no role. We comment on the implications of our findings for InAs/GaSb and HgTe/CdTe quantum spin Hall systems.

Time-Reversal Symmetry-Breaking Nematic Insulators near Quantum Spin Hall Phase Transitions

NASA Astrophysics Data System (ADS)

Xue, Fei; MacDonald, A. H.

2018-05-01

We study the phase diagram of a model quantum spin Hall system as a function of band inversion and band-coupling strength, demonstrating that when band hybridization is weak, an interaction-induced nematic insulator state emerges over a wide range of band inversion. This property is a consequence of the long-range Coulomb interaction, which favors interband phase coherence that is weakly dependent on momentum and therefore frustrated by the single-particle Hamiltonian at the band inversion point. For weak band hybridization, interactions convert the continuous gap closing topological phase transition at inversion into a pair of continuous phase transitions bounding a state with broken time-reversal and rotational symmetries. At intermediate band hybridization, the topological phase transition proceeds instead via a quantum anomalous Hall insulator state, whereas at strong hybridization interactions play no role. We comment on the implications of our findings for InAs/GaSb and HgTe/CdTe quantum spin Hall systems.

Tests of Predictions of the Algebraic Cluster Model: the Triangular D 3h Symmetry of 12C

NASA Astrophysics Data System (ADS)

Gai, Moshe

2016-07-01

A new theoretical approach to clustering in the frame of the Algebraic Cluster Model (ACM) has been developed. It predicts rotation-vibration structure with rotational band of an oblate equilateral triangular symmetric spinning top with a D 3h symmetry characterized by the sequence of states: 0+, 2+, 3-, 4±, 5- with a degenerate 4+ and 4- (parity doublet) states. Our measured new 2+ 2 in 12C allows the first study of rotation-vibration structure in 12C. The newly measured 5- state and 4- states fit very well the predicted ground state rotational band structure with the predicted sequence of states: 0+, 2+, 3-, 4±, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a D 3h symmetry is characteristic of triatomic molecules, but it is observed in the ground state rotational band of 12C for the first time in a nucleus. We discuss predictions of the ACM of other rotation-vibration bands in 12 C such as the (0+) Hoyle band and the (1-) bending mode with prediction of (“missing 3- and 4-”) states that may shed new light on clustering in 12C and light nuclei. In particular, the observation (or non observation) of the predicted (“missing”) states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha particles composing the Hoyle state at 7.6542 MeV in 12C. We discuss proposed research programs at the Darmstadt S-DALINAC and at the newly constructed ELI-NP facility near Bucharest to test the predictions of the ACM in isotopes of carbon.

Coulomb excitation of the 242mAm isomer

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

Hayes, A; Cline, D; Moody, K

2006-10-24

The {sup 242m}Am isomer, a well-known candidate for photo-depopulation research, has been studied in this first ever Coulomb excitation of a nearly pure ({approx} 98%) isomer target. Thirty new states, including a new rotational band built on a K{sup {pi}} = 6{sup -} state have been identified. Strong K-mixing results in nearly equal populations of the K{sup {pi}} = 5{sup -} and 6{sup -} states. Newly identified states have been assigned to the K{sup {pi}} = 3{sup -} rotational band, the lowest states of which are known to decay into the ground-state band. Implications regarding K-mixing and Coulomb excitation pathsmore » to the ground state are discussed.« less

Morphological and physiological analysis of type-5 and other bipolar cells in the Mouse Retina.

PubMed

Hellmer, C B; Zhou, Y; Fyk-Kolodziej, B; Hu, Z; Ichinose, T

2016-02-19

Retinal bipolar cells are second-order neurons in the visual system, which initiate multiple image feature-based neural streams. Among more than ten types of bipolar cells, type-5 cells are thought to play a role in motion detection pathways. Multiple subsets of type-5 cells have been reported; however, detailed characteristics of each subset have not yet been elucidated. Here, we found that they exhibit distinct morphological features as well as unique voltage-gated channel expression. We have conducted electrophysiological and immunohistochemical analysis of retinal bipolar cells. We defined type-5 cells by their axon terminal ramification in the inner plexiform layer between the border of ON/OFF sublaminae and the ON choline acetyltransferase (ChAT) band. We found three subsets of type-5 cells: XBCs had the widest axon terminals that stratified at a close approximation of the ON ChAT band as well as exhibiting large voltage-gated Na(+) channel activity, type-5-1 cells had compact terminals and no Na(+) channel activity, and type-5-2 cells contained umbrella-shaped terminals as well as large voltage-gated Na(+) channel activity. Hyperpolarization-activated cyclic nucleotide-gated (HCN) currents were also evoked in all type-5 bipolar cells. We found that XBCs and type-5-2 cells exhibited larger HCN currents than type-5-1 cells. Furthermore, the former two types showed stronger HCN1 expression than the latter. Our previous observations (Ichinose et al., 2014) match the current study: low temporal tuning cells that we named 5S corresponded to 5-1 in this study, while high temporal tuning 5f cells from the previous study corresponded to 5-2 cells. Taken together, we found three subsets of type-5 bipolar cells based on their morphologies and physiological features. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

X-33 Integrated Test Facility Extended Range Simulation

NASA Technical Reports Server (NTRS)

Sharma, Ashley

1998-01-01

In support of the X-33 single-stage-to-orbit program, NASA Dryden Flight Research Center was selected to provide continuous range communications of the X-33 vehicle from launch at Edwards Air Force Base, California, through landing at Malmstrom Air Force Base Montana, or at Michael Army Air Field, Utah. An extensive real-time range simulation capability is being developed to ensure successful communications with the autonomous X-33 vehicle. This paper provides an overview of various levels of simulation, integration, and test being developed to support the X-33 extended range subsystems. These subsystems include the flight termination system, L-band command uplink subsystem, and S-band telemetry downlink subsystem.

Evidence of nontermination of collective rotation near the maximum angular momentum in Rb75

NASA Astrophysics Data System (ADS)

Davies, P. J.; Afanasjev, A. V.; Wadsworth, R.; Andreoiu, C.; Austin, R. A. E.; Carpenter, M. P.; Dashdorj, D.; Finlay, P.; Freeman, S. J.; Garrett, P. E.; Görgen, A.; Greene, J.; Grinyer, G. F.; Hyland, B.; Jenkins, D. G.; Johnston-Theasby, F. L.; Joshi, P.; Macchiavelli, A. O.; Moore, F.; Mukherjee, G.; Phillips, A. A.; Reviol, W.; Sarantites, D.; Schumaker, M. A.; Seweryniak, D.; Smith, M. B.; Svensson, C. E.; Valiente-Dobon, J. J.; Ward, D.

2010-12-01

Two of the four known rotational bands in Rb75 were studied via the Ca40(Ca40,αp)Rb75 reaction at a beam energy of 165 MeV. Transitions were observed up to the maximum spin Imax of the assigned configuration in one case and one-transition short of Imax in the other. Lifetimes were determined using the residual Doppler shift attenuation method. The deduced transition quadrupole moments show a small decrease with increasing spin, but remain large at the highest spins. The results obtained are in good agreement with cranked Nilsson-Strutinsky calculations, which indicate that these rotational bands do not terminate, but remain collective at Imax.

A complex, five breakpoint intrachromosomal rearrangement ascertained through two recombinant offspring

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

Tuck-Muller, C.M.; Li, Shibo; Chen, H.

Intrachromosomal rearrangements usually result from three or fewer breaks. We report a complex intrachromosomal rearrangement resulting from five breaks in one chromosome 10 of a phenotypically normal father of two developmentally delayed children. GTG-banding analysis of the father`s rearranged chromosome 10 suggested an initial pericentric inversion followed by an insertion from the short arm into the terminal band of the long arm. To our knowledge, this rearrangement is the most complex ever reported in a single chromosome. Both children inherited a recombinant chromosome 10 with loss of the insertion and the segment distal to it. Mechanisms for both rearrangements aremore » proposed. 7 refs., 2 figs.« less

The acidic pH-induced structural changes in apo-CP43 by spectral methodologies and molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Wang, Wang; Li, Xue; Wang, Qiuying; Zhu, Xixi; Zhang, Qingyan; Du, Linfang

2018-01-01

CP43 is closely associated with the photosystem II and exists the plant thylakoid membranes. The acidic pH-induced structural changes had been investigated by fluorescence spectrum, ANS spectrum, RLS spectrum, energy transfer experiment, acrylamide fluorescence quenching assay and MD simulation. The fluorescence spectrum indicated that the structural changes in acidic pH-induced process were a four-state model, which was nature state (N), partial unfolding state (PU), refolding state (R), and molten-globule state (M), respectively. Analysis of ANS spectrum illustrated that inner hydrophobic core exposed partially to surface below pH 2.0 and inferred also that the molten-globule state existed. The RLS spectrum showed the aggregation of apo-CP43 around the pI (pH 4.5-4.0). The alterations of apo-CP43 secondary structure with different acidic treatments were confirmed by FTIR spectrum. The energy transfer experiment and quenching research demonstrated structural change at pH 4.0 was loosest. The RMSF suggested two terminals played an important function in acidic denaturation process. The distance of two terminals shown slight difference in acidic pH-induced process during the unfolding process, both N-terminal and C-terminal occupied the dominant role. However, the N-terminal accounted for the main part in the refolding process. All kinds of SASA values corresponded to spectral results. The tertiary and secondary structure by MD simulation indicated that the part transmembrane α-helix was destroyed at low pH.

A Semimetal Nanowire Rectifier: Balancing Quantum Confinement and Surface Electronegativity.

PubMed

Sanchez-Soares, Alfonso; Greer, James C

2016-12-14

For semimetal nanowires with diameters on the order of 10 nm, a semimetal-to-semiconductor transition is observed due to quantum confinement effects. Quantum confinement in a semimetal lifts the degeneracy of the conduction and valence bands in a "zero" gap semimetal or shifts energy levels with a "negative" overlap to form conduction and valence bands. For semimetal nanowires with diameters less than 10 nm, the band gap energy can be significantly larger than the thermal energy at room temperature resulting in a new class of semiconductors suitable for nanoelectronics. As a nanowire's diameter is reduced, its surface-to-volume ratio increases rapidly leading to an increased impact of surface chemistry on its electronic structure. Energy level shifts to states in the vicinity of the Fermi energy with varying surface electronegativity are shown to be comparable in magnitude to quantum confinement effects arising in nanowires with diameters of a few nanometer; these two effects can counteract one another leading to semimetallic behavior at nanowire cross sections at which confinement effects would otherwise dominate. Abruptly changing the surface terminating species along the length of a nanowire can lead to an abrupt change in the surface electronegativity. This can result in the formation of a semimetal-semiconductor junction within a monomaterial nanowire without impurity doping nor requiring the formation of a heterojunction. Using density functional theory in tandem with a Green's function approach to determine electronic structure and charge transport, respectively, current rectification is calculated for such a junction. Current rectification ratios of the order of 10 3 -10 5 are predicted at applied biases as low as 300 mV. It is concluded that rectification can be achieved at essentially molecular length scales with conventional biasing, while rivaling the performance of macroscopic semiconductor diodes.

Early segregation of layered projections from the lateral superior olivary nucleusto the central nucleus of the inferior colliculus in the neonatal cat

PubMed Central

Gabriele, Mark L.; Shahmoradian, Sarah H.; French, Christopher C.; Henkel, Craig K.we; McHaffie, John G.

2007-01-01

The central nucleus of the inferior colliculus (IC) is a laminated structure that receives multiple converging afferent projections. These projections terminate in a layered arrangement and are aligned with dendritic arbors of the predominant disc-shaped neurons, forming fibrodendritic laminae. Within this structural framework, inputs terminate in a precise manner, establishing a mosaic of partially overlapping domains that likely define functional compartments. Although several of these patterned inputs have been described in the adult, relatively little is known about their organization prior to hearing onset. The present study used the lipophilic carbocyanine dyes DiI and DiD to examine the ipsilateral and contralateral projections from the lateral superior olivary (LSO) nucleus to the IC in a developmental series of paraformaldehyde-fixed kitten tissue. By birth, the crossed and uncrossed projections had reached the IC and were distributed across the frequency axis of the central nucleus. At this earliest postnatal stage, projections already exhibited a characteristic banded arrangement similar to that described in the adult. The heaviest terminal fields of the two inputs were always complementary in nature, with the ipsilateral input appearing slightly denser. This early arrangement of interdigitating ipsilateral and contralateral LSO axonal bands that occupy adjacent sublayers supports the idea that the initial establishment of this highly organized mosaic of inputs that defines distinct synaptic domains within the IC occurs largely in the absence of auditory experience. Potential developmental mechanisms that may shape these highly ordered inputs prior to hearing onset are discussed. PMID:17850770

Topological aspect and transport property in multi-band spin-triplet chiral p-wave superconductor Sr2RuO4

NASA Astrophysics Data System (ADS)

Imai, Yoshiki; Wakabayashi, Katsunori; Sigrist, Manfred

2015-03-01

Considering the superconductor Sr2RuO4, we analyze a three-band tight-binding model with one hole-like and two electron-like Fermi surfaces corresponding to the α, β and γ bands of Sr2RuO4 by means of a self-consistent Bogoliubov-de Gennes approach for ribbonshaped system to investigate topological properties and edge states. In the superconducting phase two types of gapless edge states can be identified, one of which displays an almost flat dispersion at zero energy, while the other, originating from the γ band, has a linear dispersion and constitutes a genuine chiral edge states. Not only a charge current appears at the edges but also a spin current due to the multi-band effect in the superconducting phase. In particular, the chiral edge state from the γ band is closely tied to topological properties, and the chiral p-wave superconducting states are characterized by an integer topological number, the so-called Chern number. We show that the γ band is close to a Lifshitz transition. Since the sign of the Chern number may be very sensitive to the surface condition, we consider the effect of the surface reconstruction observed in Sr2RuO4 on the topological property and show the possibility of the hole-like Fermi surface at the surface.

Lifetime Measurements in 178Hf

PubMed Central

de Haan, R. C.; Aprahamian, A.; Börner, H. G.; Doll, C.; Jentschel, M.; Bruce, A. M.; Lesher, S. R.

2000-01-01

Lifetimes of levels from Kπ = 2+, Kπ = 4+ and several Kπ = 0+ bands have been measured in the 178Hf nucleus using the GRID technique. Lifetimes of the 2+ and 3+ levels were measured within the Kπ = 2+ γ band. A lower limit was established for the lifetime of the 4+ level of the Kπ = 4+ band. The resulting upper limits for the absolute B(E2) values exclude collective transitions from the Kπ = 4+ to the ground state band but not to the Kπ= 2+ band. Level lifetimes were also measured for several states within three separate Kπ= 0+ bands. Evidence is presented for a previously unobserved case of two excited Kπ= 0+ bands being connected via collective E2 transitions. PMID:27551596

78 FR 26384 - Indian Entities Recognized and Eligible To Receive Services From the United States Bureau of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-06

...: (Barona Group of Capitan Grande Band of Mission Indians of the Barona Reservation, California; Viejas (Baron Long) Group of Capitan Grande Band of Mission Indians of the Viejas Reservation, California... Indians of Nevada (Four constituent bands: Battle Mountain Band; Elko Band; South Fork Band and Wells Band...

Effects of B site doping on electronic structures of InNbO4 based on hybrid density functional calculations

NASA Astrophysics Data System (ADS)

Lu, M. F.; Zhou, C. P.; Li, Q. Q.; Zhang, C. L.; Shi, H. F.

2018-01-01

In order to improve the photocatalytic activity under visible-light irradiation, we adopted first principle calculations based on density functional theory (DFT) to calculate the electronic structures of B site transition metal element doped InNbO4. The results indicated that the complete hybridization of Nb 4d states and some Ti 3d states contributed to the new conduction band of Ti doped InNbO4, barely changing the position of band edge. For Cr doping, some localized Cr 3d states were introduced into the band gap. Nonetheless, the potential of localized levels was too positive to cause visible-light reaction. When it came to Cu doping, the band gap was almost same with that of InNbO4 as well as some localized Cu 3d states appeared above the top of VB. The introduction of localized energy levels benefited electrons to migrate from valence band (VB) to conduction band (CB) by absorbing lower energy photons, realizing visible-light response.

The Pseudogap in Multiband Superconductivity

NASA Astrophysics Data System (ADS)

Kristoffel, N.; Rubin, P.

2012-11-01

The pseudogap (PG) excitation is analyzed as a natural event in multiband superconductivity. It corresponds to minimal quasiparticle excitation energy of an electron band not touched by the chemical potential. The critical points of the phase diagram are determined by vanishing conditions for normal state pseudogaps (NPG). For two bands (gapped or overlapping) these are positioned on edges of the superconducting dome. Theoretical background for a three-band system with two interband pairing channels is developed. There are three independent superconducting gaps (SCG). The PG is associated with the band component possessing a bare gap which can be quenched by doping. At low doping the PG and the SCG of another band component coexist. The critical point is not fixed in respect of the transition temperature (Tc) dome background. The depletion of the PG associated states is restored here. This effect can also be indirect by the participation of these states in determining the chemical potential position. At the critical point the PG looses its normal state contribution and continues as the SCG of the same band. Illustrative examples on the doping scale have been calculated.

Ref Tek Ultra-low Power Seismic Recorder With Low-cost High Speed Internet Telemetry U An Advanced Real-time Seismological Data Acquisition System

NASA Astrophysics Data System (ADS)

Passmore, P.; Zimakov, L.; Rozhkov, M.

The 3rd Generation Seismic Recorder, Model 130-01, has been designed to be easier to use - more compact, lighter in weight, lower power, and requires less maintenance than other recorders. Not only is the hardware optimized for field deployments, soft- ware tools as well have been specially developed to support both field and base station operation. The 130's case is a clamshell design, inherently waterproof, with easy access to all user features on the top of the unit. The 130 has 6 input/output connectors, an LCD display, and a removable lid on top of the case. There are two Channel input connectors on a 6-channel unit (only one on a 3-channel unit), a Terminal connector for setup and control, a Net connector combining Ethernet and Serial PPP for network access, a 12 VDC Power connector, and a GPS receiver connector. The LCD display allows the user to monitor the status of various sub systems within the 130 without having a terminal device attached. For storing large amounts of data the IBM MicrodriveTM is offered. User setup, control and status monitoring is done either with a Personal Digital Assistant (PDA) (Palm OS compatible) using our Palm Field Controller (PFC) software or from a PC/workstation using our REF TEK Network Controller (RNC) GUI interface. StarBand VSAT is the premier two-way, always-on, high-speed satellite Internet ser- vice. StarBand means high-speed Internet without the constraints and congestion of land-based cable or telephone networks. StarBand uses a single satellite dish antenna for receiving and for sending dataUno telephone connection is needed. The hardware ° cost is much less than standard VSAT equipment with double or single hop transmis- sion. REF TEK protocol (RTP) provides end-to-end error-correcting data transmission and command/control. StarBandSs low cost VSAT provides two-way, always-on, high speed satellite Internet data availability. REF TEK and StarBand create the most ad- vanced real-time seismological data acquisition system. 1 Results of data transmission and availability is discussed. 2

Spin-split silicon states at step edges of Si(553)-Au

NASA Astrophysics Data System (ADS)

Biedermann, K.; Regensburger, S.; Fauster, Th.; Himpsel, F. J.; Erwin, S. C.

2012-06-01

The quasi-one-dimensional Si(553)-Au surface is investigated with time-resolved two-photon photoemission and laser-based photoemission. Several occupied and unoccupied states inside and outside the bulk band gap of silicon were found near the center of the surface Brillouin zone. A nondispersing unoccupied state 0.62 eV above the Fermi level with a lifetime of 125 fs matches the spin-split silicon step-edge state predicted by density functional theory calculations. Two occupied bands can be associated with the bands calculated for nonpolarized step-edge atoms.

Link between light-triggered Mg-banding and chamber formation in the planktic foraminifera Neogloboquadrina dutertrei

DOE PAGES

Fehrenbacher, Jennifer S.; Russell, Ann D.; Davis, Catherine V.; ...

2017-05-15

Mg/Ca ratios of planktic foraminifera are commonly used to reconstruct past ocean temperatures. However, intrashell Mg/Ca ratios exhibit a pattern of alternating high and low Mg-bands in many species. Whereas mechanisms controlling Mg variability are poorly constrained, recent experiments demonstrate that it is paced by the diurnal light/dark cycle in Orbulina universa, which forms a terminal shell of simple spherical geometry. It is unknown whether Mg-heterogeneity is diurnally paced in species with complex shell morphologies, or is the result of growth processes. Here, we show that high Mg/Ca-calcite also forms at night in cultured specimens of the multi-chambered planktic foraminiferamore » Neogloboquadrina dutertrei. Our results demonstrate that N. dutertrei adds a significant amount of calcite, and nearly all Mg-bands, after the final chamber forms. Furthermore, these results have implications for interpreting patterns of calcification in N. dutertrei, and possibly other foraminifera species, and suggests diurnal Mg-banding is an intrinsic component of biomineralization in planktic foraminifera.« less

Tight-binding analysis of Si and GaAs ultrathin bodies with subatomic wave-function resolution

NASA Astrophysics Data System (ADS)

Tan, Yaohua P.; Povolotskyi, Michael; Kubis, Tillmann; Boykin, Timothy B.; Klimeck, Gerhard

2015-08-01

Empirical tight-binding (ETB) methods are widely used in atomistic device simulations. Traditional ways of generating the ETB parameters rely on direct fitting to bulk experiments or theoretical electronic bands. However, ETB calculations based on existing parameters lead to unphysical results in ultrasmall structures like the As-terminated GaAs ultrathin bodies (UTBs). In this work, it is shown that more transferable ETB parameters with a short interaction range can be obtained by a process of mapping ab initio bands and wave functions to ETB models. This process enables the calibration of not only the ETB energy bands but also the ETB wave functions with corresponding ab initio calculations. Based on the mapping process, ETB models of Si and GaAs are parameterized with respect to hybrid functional calculations. Highly localized ETB basis functions are obtained. Both the ETB energy bands and wave functions with subatomic resolution of UTBs show good agreement with the corresponding hybrid functional calculations. The ETB methods can then be used to explain realistically extended devices in nonequilibrium that cannot be tackled with ab initio methods.

Preliminary Statistics from the NASA Alphasat Beacon Receiver in Milan, Italy

NASA Technical Reports Server (NTRS)

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

2015-01-01

NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have initiated a joint propagation campaign within the framework of the Alphasat propagation experiment to characterize rain attenuation, scintillation, and gaseous absorption effects of the atmosphere in the 40 GHz band. NASA GRC has developed and installed a KQ-band (20-40 GHz) beacon receiver at the POLIMI campus in Milan, Italy, which receives the 20-40 GHz signals broadcast from the Alphasat Aldo Paraboni TDP5 beacon payload. The primary goal of these measurements is to develop a physical model to improve predictions of communications systems performance within the Q-band. Herein, we provide an overview of the design and data calibration procedure, and present 6 months of preliminary statistics of the NASA propagation terminal, which has been installed and operating in Milan since May 2014. The Q-band receiver has demonstrated a dynamic range of 40 dB at an 8-Hz sampling rate. A weather station with an optical disdrometer is also installed to characterize rain drop size distribution for correlation with physical based models

Preliminary Statistics from the NASA Alphasat Beacon Receiver in Milan, Italy

NASA Technical Reports Server (NTRS)

Nessel, James; Zemba, Michael; Morse, Jacquelynne; Luini, Lorenzo; Riva, Carlo

2015-01-01

NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have initiated a joint propagation campaign within the framework of the Alphasat propagation experiment to characterize rain attenuation, scintillation, and gaseous absorption effects of the atmosphere in the 40 gigahertz band. NASA GRC has developed and installed a K/Q-band (20/40 gigahertz) beacon receiver at the POLIMI campus in Milan, Italy, which receives the 20/40 gigahertz signals broadcast from the Alphasat Aldo Paraboni TDP no. 5 beacon payload. The primary goal of these measurements is to develop a physical model to improve predictions of communications systems performance within the Q-band. Herein, we provide an overview of the design and data calibration procedure, and present 6 months of preliminary statistics of the NASA propagation terminal, which has been installed and operating in Milan since May 2014. The Q-band receiver has demonstrated a dynamic range of 40 decibels at an 8-hertz sampling rate. A weather station with an optical disdrometer is also installed to characterize rain drop size distribution for correlation with physical based models.

High-resolution infrared spectroscopy of the asymmetric NO stretch band of jet-cooled nitromethane and assignment of the lowest four torsional states

DOE PAGES

Dawadi, Mahesh B.; Degliumberto, Lou; Perry, David S.; ...

2017-08-10

We used a high-throughput CW slit-jet apparatus coupled to a high-resolution FTIR to record the asymmetric NO stretch band of nitromethane. The b-type band, including torsionally excited states with m ≤ 3, has been assigned for Ka" ≤ 10, J" ≤ 20. The ground state combination differences derived from these assigned levels were fit with the RAM36 program to give an RMS deviation of 0.0006 cm -1. The band origin is 1583.0 (±0.1) cm -1 and the torsional level spacing is nearly identical to that in the ground state. The upper state levels are split into multiplets by perturbations. Wemore » also fit a subset of the available upper state combination differences for m = 0, Ka' ≤ 7, J' ≤ 10 with the same program, but with rather poorer precision (0.01 cm -1) than for the ground state.« less

High-resolution infrared spectroscopy of the asymmetric NO stretch band of jet-cooled nitromethane and assignment of the lowest four torsional states

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

Dawadi, Mahesh B.; Degliumberto, Lou; Perry, David S.

We used a high-throughput CW slit-jet apparatus coupled to a high-resolution FTIR to record the asymmetric NO stretch band of nitromethane. The b-type band, including torsionally excited states with m ≤ 3, has been assigned for Ka" ≤ 10, J" ≤ 20. The ground state combination differences derived from these assigned levels were fit with the RAM36 program to give an RMS deviation of 0.0006 cm -1. The band origin is 1583.0 (±0.1) cm -1 and the torsional level spacing is nearly identical to that in the ground state. The upper state levels are split into multiplets by perturbations. Wemore » also fit a subset of the available upper state combination differences for m = 0, Ka' ≤ 7, J' ≤ 10 with the same program, but with rather poorer precision (0.01 cm -1) than for the ground state.« less

High-resolution infrared spectroscopy of the asymmetric NO stretch band of jet-cooled nitromethane and assignment of the lowest four torsional states

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

Dawadi, Mahesh B.; Degliumberto, Lou; Perry, David S.

A high-throughput CW slit-jet apparatus coupled to a high-resolution FTIR was used to record the asymmetric NO stretch band of nitromethane. The b-type band, including torsionally excited states with m ≤ 3, has been assigned for Ka" ≤ 10, J" ≤ 20. The ground state combination differences derived from these assigned levels were fit with the RAM36 program to give an RMS deviation of 0.0006 cm-1. The band origin is 1583.0 (+/- 0.1) cm-1 and the torsional level spacing is nearly identical to that in the ground state. The upper state levels are split into multiplets by perturbations. A subsetmore » of the available upper state combination differences for m = 0, Ka' ≤ 7, J' ≤ 10 were fit with the same program, but with rather poorer precision (0.01 cm-1) than for the ground state.« less

Spin-polarized surface resonances accompanying topological surface state formation

DOE PAGES

Jozwiak, Chris; Sobota, Jonathan A.; Gotlieb, Kenneth; ...

2016-10-14

Topological insulators host spin-polarized surface states born out of the energetic inversion of bulk bands driven by the spin-orbit interaction. Here we discover previously unidentified consequences of band-inversion on the surface electronic structure of the topological insulator Bi 2Se 3. By performing simultaneous spin, time, and angle-resolved photoemission spectroscopy, we map the spin-polarized unoccupied electronic structure and identify a surface resonance which is distinct from the topological surface state, yet shares a similar spin-orbital texture with opposite orientation. Its momentum dependence and spin texture imply an intimate connection with the topological surface state. Calculations show these two distinct states canmore » emerge from trivial Rashba-like states that change topology through the spin-orbit-induced band inversion. As a result, this work thus provides a compelling view of the coevolution of surface states through a topological phase transition, enabled by the unique capability of directly measuring the spin-polarized unoccupied band structure.« less

High-resolution infrared spectroscopy of the asymmetric NO stretch band of jet-cooled nitromethane and assignment of the lowest four torsional states

NASA Astrophysics Data System (ADS)

Dawadi, Mahesh B.; Degliumberto, Lou; Perry, David S.; Mettee, Howard D.; Sams, Robert L.

2018-01-01

A high-throughput CW slit-jet apparatus coupled to a high-resolution FTIR was used to record the asymmetric NO stretch band of nitromethane. The b-type band, including torsionally excited states with m ≤ 3, has been assigned for Ka″ ≤ 10, J″ ≤ 20. The ground state combination differences derived from these assigned levels were fit with the RAM36 program to give an RMS deviation of 0.0006 cm-1. The band origin is 1583.0 (±0.1) cm-1 and the torsional level spacing is nearly identical to that in the ground state. The upper state levels are split into multiplets by perturbations. A subset of the available upper state combination differences for m = 0, Ka‧ ≤ 7, J‧ ≤ 10 were fit with the same program, but with rather poorer precision (0.01 cm-1) than for the ground state.

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

Mitkova, Maria; Butt, Darryl; Kozicki, Michael

For many decades, various radiation detecting material have been extensively researched, to find a better material or mechanism for radiation sensing. Recently, there is a growing need for a smaller and effective material or device that can perform similar functions of bulkier Geiger counters and other measurement options, which fail the requirement for easy, cheap and accurate radiation dose measurement. Here arises the use of thin film chalcogenide glass, which has unique properties of high thermal stability along with high sensitivity towards short wavelength radiation. The unique properties of chalcogenide glasses are attributed to the lone pair p-shell electrons, whichmore » provide some distinctive optical properties when compared to crystalline material. These qualities are derived from the energy band diagram and the presence of localized states in the band gap. Chalcogenide glasses have band tail states and localized states, along with the two band states. These extra states are primarily due to the lone pair electrons as well as the amorphous structure of the glasses. The localized states between the conductance band (CB) and valence band (VB) are primarily due to the presence of the lone pair electrons, while the band tail states are attributed to the Van der Waal's forces between layers of atoms [1]. Localized states are trap locations within the band gap where electrons from the valence band can hop into, in their path towards the conduction band. Tail states on the other hand are locations near the band gap edges and are known as Urbach tail states (Eu). These states are occupied with many electrons that can participate in the various transformations due to interaction with photons. According to Y. Utsugi et. al.[2], the electron-phonon interactions are responsible for the generation of the Urbach tails. These states are responsible for setting the absorption edge for these glasses and photons with energy near the band gap affect these states. We have studied the effect of x-rays and γ-rays, on thin film chalcogenide glasses and applied them in conjunction with film incorporating a silver source in a new type of radiation sensor for which we have an US patent application [3]. In this report, we give data about our studies regarding our designed radiation sensor along with the testing and performance at various radiation doses. These studies have been preceded by materials characterization research related to the compositional and structural characteristics of the active materials used in the radiation sensor design. During the work on the project, we collected a large volume of material since every experiment was repeated many times to verify the results. We conducted a comprehensive material research, analysis and discussion with the aim to understand the nature of the occurring effects, design different structures to harness these effects, generated models to aid in the understanding the effects, built different device structures and collected data to quantify device performance. These various aspects of our investigation have been detailed in previous quarterly reports. In this report, we present our main results and emphasize on the results pertaining to the core project goals materials development, sensor design and testing and with an emphasis on classifying the appropriate material and design for the optimal application. The report has three main parts: (i) Presentation of the main data; (ii) Bulleted summary of the most important results; (iii) List of the patent, journal publications, conference proceedings and conferences participation, occurring as a result of working on the project.« less

Performance evaluation type II and type IIA box beam end terminals--volume II : appendices.

DOT National Transportation Integrated Search

2010-01-10

Two types of guide rail end terminals were constructed and evaluated according to the American Association of State Highway : and Transportation Officials (AASHTOs) Manual for Assessing Safety Hardware (MASH). The guide rail end terminals are u...

7 CFR 953.67 - Proceedings after termination.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Proceedings after termination. 953.67 Section 953.67 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing... SOUTHEASTERN STATES Order Regulating Handling Effective Time and Termination § 953.67 Proceedings after...

Indian Education Division, Nevada State Department of Education, 1960-1961 Annual Report to United States Bureau of Indian Affairs.

ERIC Educational Resources Information Center

Haglund, E. A., Comp.

Information for the second complete school year under the agreement between the Nevada Department of Education and the Bureau of Indian Affairs for the orderly and equitable termination of the Johnson-O'Malley Program in the State of Nevada is presented in this annual report. Termination, over a 5-year period, of the student transportation and…

Electronic structure and optical properties of noncentrosymmetric LiGaSe2: Experimental measurements and DFT band structure calculations

NASA Astrophysics Data System (ADS)

Lavrentyev, A. A.; Gabrelian, B. V.; Vu, V. T.; Ananchenko, L. N.; Isaenko, L. I.; Yelisseyev, A. P.; Khyzhun, O. Y.

2017-04-01

We report on measurements of X-ray photoelectron (XP) spectra for pristine and Ar+ ion-irradiated surfaces of LiGaSe2 single crystal grown by Bridgman-Stockbarger method. Electronic structure of the LiGaSe2 compound is studied from a theoretical and experimental viewpoint. In particular, total and partial densities of states of LiGaSe2 are investigated by density functional theory (DFT) calculations employing the augmented plane wave + local orbitals (APW + lo) method and they are verified by data of X-ray spectroscopy measurements. The DFT calculations indicate that the main contributors to the valence band of LiGaSe2 are the Se 4p states, which contribute mainly at the top and in the upper portion of the valence band, with also essential contributions of these states in the lower portion of the band. Other substantial contributions to the valence band of LiGaSe2 emerge from the Ga 4s and Ga 4p states contributing mainly at the lower ant upper portions of the valence band, respectively. With respect to the conduction band, the calculations indicate that its bottom is composed mainly from contributions of the unoccupied Ga s and Se p states. The present calculations are confirmed experimentally when comparing the XP valence-band spectrum of the LiGaS2 single crystal on a common energy scale with the X-ray emission bands representing the energy distribution of the Ga 4p and Se 4p states. Measurements of the fundamental absorption edges at room temperature reveal that bandgap value, Eg, of LiGaSe2 is equal to 3.47 eV and the Eg value increases up to 3.66 eV when decreasing temperature to 80 K. The main optical characteristics of the LiGaSe2 compound are clarified by the DFT calculations.

Localized Single Frequency Lasing States in a Finite Parity-Time Symmetric Resonator Chain

PubMed Central

Phang, Sendy; Vukovic, Ana; Creagh, Stephen C.; Sewell, Phillip D.; Gradoni, Gabriele; Benson, Trevor M.

2016-01-01

In this paper a practical case of a finite periodic Parity Time chain made of resonant dielectric cylinders is considered. The paper analyzes a more general case where PT symmetry is achieved by modulating both the real and imaginary part of the material refractive index along the resonator chain. The band-structure of the finite periodic PT resonator chains is compared to infinite chains in order to understand the complex interdependence of the Bloch phase and the amount of the gain/loss in the system that causes the PT symmetry to break. The results show that the type of the modulation along the unit cell can significantly affect the position of the threshold point of the PT system. In all cases the lowest threshold is achieved near the end of the Brillouin zone. In the case of finite PT-chains, and for a particular type of modulation, early PT symmetry breaking is observed and shown to be caused by the presence of termination states localized at the edges of the finite chain resulting in localized lasing and dissipative modes at each end of the chain. PMID:26848095

Use DNA solutions to model polymer entanglement in flow: simultaneous rheometric and particle-tracking velocimetric measurements

NASA Astrophysics Data System (ADS)

Boukany, Pouyan; Wang, Shi-Qing

2008-03-01

Entangled aqueous DNA solutions are ideal as a model system to examine nonlinear flow features including stress overshoot in startup shear and shear thinning phenomenon. These soft systems can be strongly entangled with 60 entanglement points per chain and a terminal relaxation time as long as 1000 s at 1 % concentration [1-2]. They allow a comparison between the steady state attained with a startup shear and that attained through an ``infinitely'' slow ramping up of the applied shear rate. Indeed, startup shear in the nonlinear (stress plateau) region causes the DNA solutions to yield inhomogeneously, resulting in permanent shear banding. However, the slowly ramped-up shear into the same final rate as applied in startup shear allowed the solutions to avoid shear inhomogeneity. Thus, we demonstrated that it is possible for the final steady states to be different depending on how an entangled system is brought into the same final experimental condition. This result implies that it is ill-defined to pursue conventional constitutive relationship in flow of entangled polymers. [1] Boukany, P. E.; Hu, T. H.; Wang, S. Q. textitMacromolecules 2007, under review. [2] Boukany, P. E.; Wang, S. Q. J. Rheol. 2007, under review.

Andreev bound states probed in three-terminal quantum dots

NASA Astrophysics Data System (ADS)

Gramich, J.; Baumgartner, A.; Schönenberger, C.

2017-11-01

Andreev bound states (ABSs) are well-defined many-body quantum states that emerge from the hybridization of individual quantum dot (QD) states with a superconductor and exhibit very rich and fundamental phenomena. We demonstrate several electron transport phenomena mediated by ABSs that form on three-terminal carbon nanotube (CNT) QDs, with one superconducting (S) contact in the center and two adjacent normal-metal (N) contacts. Three-terminal spectroscopy allows us to identify the coupling to the N contacts as the origin of the Andreev resonance (AR) linewidths and to determine the critical coupling strengths to S, for which a ground state (or quantum phase) transition in such S-QD systems can occur. In addition, we ascribe replicas of the lowest-energy ABS resonance to transitions between the ABS and odd-parity excited QD states, a process we call excited state ABS resonances. In the conductance between the two N contacts we find a characteristic pattern of positive and negative differential subgap conductance, which we explain by considering two nonlocal processes, the creation of Cooper pairs in S by electrons from both N terminals, and a transport mechanism we call resonant ABS tunneling, possible only in multiterminal QD devices. In the latter process, electrons are transferred via the ABS without effectively creating Cooper pairs in S. The three-terminal geometry also allows spectroscopy experiments with different boundary conditions, for example by leaving S floating. Surprisingly, we find that, depending on the boundary conditions and the device parameters, the experiments either show single-particle Coulomb blockade resonances, ABS characteristics, or both in the same measurements, seemingly contradicting the notion of ABSs replacing the single-particle states as eigenstates of the QD. We qualitatively explain these results as originating from the finite time scale required for the coherent oscillations between the superposition states after a single-electron tunneling event. These experiments demonstrate that three-terminal experiments on a single complex quantum object can also be useful to investigate charge dynamics otherwise not accessible due to the very high frequencies.

Topologically Nontrivial Magnon Bands in Artificial Square Spin Ices with Dzyaloshinskii-Moriya Interaction

NASA Astrophysics Data System (ADS)

Iacocca, Ezio; Heinonen, Olle

2017-09-01

Systems that exhibit topologically protected edge states are interesting both from a fundamental point of view as well as for potential applications, the latter because of the absence of backscattering and robustness to perturbations. It is desirable to be able to control and manipulate such edge states. Here, we show that artificial square ices can incorporate both features: an interfacial Dzyaloshinskii-Moriya interaction gives rise to topologically nontrivial magnon bands, and the equilibrium state of the spin ice is reconfigurable with different configurations having different magnon dispersions and topology. The topology is found to develop as odd-symmetry bulk and edge magnon bands approach each other so that constructive band inversion occurs in reciprocal space. Our results show that topologically protected bands are supported in square spin ices.

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

Sahu, Sivabrata, E-mail: siva1987@iopb.res.in; Parashar, S. K. S., E-mail: sksparashar@yahoo.com; Rout, G. C., E-mail: gcr@iopb.res.in

We address here a tight-binding theoretical model calculation for AA-stacked bi-layer graphene taking into account of a biased potential between two layers to study the density of states and the band dispersion within the total Brillouin zone. We have calculated the electronic Green’s function for electron operator corresponding to A and B sub lattices by Zubarev’s Green’s function technique from which the electronic density of states and the electron band energy dispersion are calculated. The numerically computed density of states and band energy dispersions are investigated by tuning the biased potential to exhibit the band gap by varying the differentmore » physical parameters.« less

Photoionization bands of rubidium molecule

NASA Astrophysics Data System (ADS)

Rakić, M.; Pichler, G.

2018-03-01

We studied the absorption spectrum of dense rubidium vapor generated in a T-type sapphire cell with a special emphasis on the structured photoionization continuum observed in the 200-300 nm spectral region. The photoionization spectrum has a continuous atomic contribution with a pronounced Seaton-Cooper minimum at about 250 nm and a molecular photoionization contribution with many broad bands. We discuss the possible origin of the photoionization bands as stemming from the absorption from the ground state of the Rb2 molecule to excited states of Rb2+* and to doubly excited autoionizing states of Rb2** molecule. All these photoionization bands are located above the Rb+ and Rb2+ ionization limits.

Bulk and surface electronic structures of MgO

NASA Astrophysics Data System (ADS)

Schönberger, U.; Aryasetiawan, F.

1995-09-01

The bulk electronic structure of MgO is calculated from first principles including correlation effects within the GW approximation. The band gap, the position of the 2s O band, and the valence band width are in good agreement with experiment. From the quasiparticle band structure, optical transitions corresponding to the main optical absorption peaks are identified. The energy-loss spectrum is also calculated and compared with experiment. The surface electronic structure of MgO(100) is calculated self-consistently within the local-density approximation. It is found that states observed in a recent photoemission experiment outside the bulk allowed states are close to surface states.

Structural Basis of Cerebellar Microcircuits in the Rat

PubMed Central

Cerminara, Nadia L.; Aoki, Hanako; Loft, Michaela; Apps, Richard

2013-01-01

The topography of the cerebellar cortex is described by at least three different maps, with the basic units of each map termed “microzones,” “patches,” and “bands.” These are defined, respectively, by different patterns of climbing fiber input, mossy fiber input, and Purkinje cell (PC) phenotype. Based on embryological development, the “one-map” hypothesis proposes that the basic units of each map align in the adult animal and the aim of the present study was to test this possibility. In barbiturate anesthetized adult rats, nanoinjections of bidirectional tracer (Retrobeads and biotinylated dextran amine) were made into somatotopically identified regions within the hindlimb C1 zone in copula pyramidis. Injection sites were mapped relative to PC bands defined by the molecular marker zebrin II and were correlated with the pattern of retrograde cell labeling within the inferior olive and in the basilar pontine nuclei to determine connectivity of microzones and patches, respectively, and also with the distributions of biotinylated dextran amine-labeled PC terminals in the cerebellar nuclei. Zebrin bands were found to be related to both climbing fiber and mossy fiber inputs and also to cortical representation of different parts of the ipsilateral hindpaw, indicating a precise spatial organization within cerebellar microcircuitry. This precise connectivity extends to PC terminal fields in the cerebellar nuclei and olivonuclear projections. These findings strongly support the one-map hypothesis and suggest that, at the microcircuit level of resolution, the cerebellar cortex has a common plan of spatial organization for major inputs, outputs, and PC phenotype. PMID:24133249

Angle of Attack Modulation for Mars Entry Terminal State Optimization

NASA Technical Reports Server (NTRS)

Lafleur, Jarret M.; Cerimele, Christopher J.

2009-01-01

From the perspective of atmospheric entry, descent, and landing (EDL), one of the most foreboding destinations in the solar system is Mars due in part to its exceedingly thin atmosphere. To benchmark best possible scenarios for evaluation of potential Mars EDL system designs, a study is conducted to optimize the entry-to-terminal-state portion of EDL for a variety of entry velocities and vehicle masses, focusing on the identification of potential benefits of enabling angle of attack modulation. The terminal state is envisioned as one appropriate for the initiation of terminal descent via parachute or other means. A particle swarm optimizer varies entry flight path angle, ten bank profile points, and ten angle of attack profile points to find maximum-final-altitude trajectories for a 10 30 m ellipsled at 180 different combinations of values for entry mass, entry velocity, terminal Mach number, and minimum allowable altitude. Parametric plots of maximum achievable altitude are shown, as are examples of optimized trajectories. It is shown that appreciable terminal state altitude gains (2.5-4.0 km) over pure bank angle control may be possible if angle of attack modulation is enabled for Mars entry vehicles. Gains of this magnitude could prove to be enabling for missions requiring high-altitude landing sites. Conclusions are also drawn regarding trends in the bank and angle of attack profiles that produce the optimal trajectories in this study, and directions for future work are identified.

Electronic structure and linear optical properties of ZnSe and ZnSe:Mn.

PubMed

Su, Kang; Wang, Yuhua

2010-03-01

As an important wide band-gap II-VI semiconductor, ZnSe has attracted much attention for its various applications in photo-electronic devices such as blue light-emitting diodes and blue-green diode lasers. Mn-doped ZnSe is an excellent quantum dot material. The electronic structures of the sphalerite ZnSe and ZnSe:Mn were calculated using the Vienna ab initio Simulation Package with ultra-soft pseudo potentials and Material Studio. The calculated equilibrium lattice constants agree well with the experimental values. Using the optimized equilibrium lattice constants, the densities of states and energy band structures were further calculated. By analyzing the partial densities of states, the contributions of different electron states in different atoms were estimated. The p states of Zn mostly contribute to the top of the valence band, and the s states of Zn and the s states of Se have major effects on the bottom of the conduction band. The calculated results of ZnSe:Mn show the band gap was changed from 2.48 to 1.1 eV. The calculated linear optical properties, such as refractive index and absorption spectrum, are in good agreement with experimental values.

Impact of Fe doping on the electronic structure of SrTiO3 thin films determined by resonant photoemission

NASA Astrophysics Data System (ADS)

Kubacki, J.; Kajewski, D.; Goraus, J.; Szot, K.; Koehl, A.; Lenser, Ch.; Dittmann, R.; Szade, J.

2018-04-01

Epitaxial thin films of Fe doped SrTiO3 have been studied by the use of resonant photoemission. This technique allowed us to identify contributions of the Fe and Ti originating electronic states to the valence band. Two valence states of iron Fe2+ and Fe3+, detected on the base of x-ray absorption studies spectra, appeared to form quite different contributions to the valence band of SrTiO3. The electronic states within the in-gap region can be attributed to Fe and Ti ions. The Fe2+ originating states which can be connected to the presence of oxygen vacancies form a broad band reaching binding energies of about 0.5 eV below the conduction band, while Fe3+ states form in the gap a sharp feature localized just above the top of the valence band. These structures were also confirmed by calculations performed with the use of the FP-LAPW/APW+lo method including Coulomb correlations within the d shell. It has been shown that Fe doping induced Ti originating states in the energy gap which can be related to the hybridization of Ti and Fe 3d orbitals.

Yrare low-spin positive-parity states in N = 88 66 154 Dy

NASA Astrophysics Data System (ADS)

Zimba, G. L.; Bvumbi, S. P.; Masiteng, L. P.; Jones, P.; Sharpey-Schafer, J. F.; Majola, S. N. T.; Dinoko, T. S.; Shirinda, O.; Lawrie, J. J.; Easton, J. E.; Khumalo, N. A.; Msebi, L.; Mashita, P. I.; Papka, P.; Roux, D. G.; Negi, D.

2018-04-01

Low-spin positive-parity yrare states of 66 154 Dy88 were established using the 155Gd(3He,4n) reaction at a beam energy of E_{lab} = 37.5 MeV. The AFRODITE spectrometer array at iThemba LABS was used to record γγ coincidences and measure DCO ratios and polarisation asymmetries. The K^{π}=2+ γ band has been observed up to spin 13+ in the odd spins and to 12+ in the even spins. The staggering parameter S( I) of the γ band is compared to that found in other N = 88 isotones. Different behaviour of S( I) with increasing spin is observed for each of the isotones. We conjecture that the variation in S( I) is mainly due to mixing of the even-spin states with the same spin and parity states in neighbouring rotational bands. A second K^{π}=2+ band has been established up to a spin of 12+ in the even spins. We suggest that this is a γ band based on the J^{π} = 0+ state at Ex = 660.6 keV.

First-principle calculation of the electronic structure, DOS and effective mass TlInSe2

NASA Astrophysics Data System (ADS)

Ismayilova, N. A.; Orudzhev, G. S.; Jabarov, S. H.

2017-05-01

The electronic structure, density of states (DOS), effective mass are calculated for tetragonal TlInSe2 from first principle in the framework of density functional theory (DFT). The electronic structure of TlInSe2 has been investigated by Quantum Wise within GGA. The calculated band structure by Hartwigsen-Goedecker-Hutter (HGH) pseudopotentials (psp) shows both the valence band maximum and conduction band minimum located at the T point of the Brillouin zone. Valence band maximum at the T point and the surrounding parts originate mainly from 6s states of univalent Tl ions. Bottom of the conduction band is due to the contribution of 6p-states of Tl and 5s-states of In atoms. Calculated DOS effective mass for holes and electrons are mDOS h∗ = 0.830m e, mDOS h∗ = 0.492m e, respectively. Electron effective masses are fairly isotropic, while the hole effective masses show strong anisotropy. The calculated electronic structure, density of states and DOS effective masses of TlInSe2 are in good agreement with existing theoretical and experimental results.

19 CFR 210.41 - Termination of investigation.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 19 Customs Duties 3 2010-04-01 2010-04-01 false Termination of investigation. 210.41 Section 210.41 Customs Duties UNITED STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND ENFORCEMENT Determinations and Actions Taken § 210.41 Termination of...

22 CFR 62.78 - Termination.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Termination. 62.78 Section 62.78 Foreign Relations DEPARTMENT OF STATE PUBLIC DIPLOMACY AND EXCHANGES EXCHANGE VISITOR PROGRAM Student and Exchange Visitor Information System (SEVIS) § 62.78 Termination. An exchange visitor who willfully or negligently...

Discrete-Time Local Value Iteration Adaptive Dynamic Programming: Admissibility and Termination Analysis.

PubMed

Wei, Qinglai; Liu, Derong; Lin, Qiao

In this paper, a novel local value iteration adaptive dynamic programming (ADP) algorithm is developed to solve infinite horizon optimal control problems for discrete-time nonlinear systems. The focuses of this paper are to study admissibility properties and the termination criteria of discrete-time local value iteration ADP algorithms. In the discrete-time local value iteration ADP algorithm, the iterative value functions and the iterative control laws are both updated in a given subset of the state space in each iteration, instead of the whole state space. For the first time, admissibility properties of iterative control laws are analyzed for the local value iteration ADP algorithm. New termination criteria are established, which terminate the iterative local ADP algorithm with an admissible approximate optimal control law. Finally, simulation results are given to illustrate the performance of the developed algorithm.In this paper, a novel local value iteration adaptive dynamic programming (ADP) algorithm is developed to solve infinite horizon optimal control problems for discrete-time nonlinear systems. The focuses of this paper are to study admissibility properties and the termination criteria of discrete-time local value iteration ADP algorithms. In the discrete-time local value iteration ADP algorithm, the iterative value functions and the iterative control laws are both updated in a given subset of the state space in each iteration, instead of the whole state space. For the first time, admissibility properties of iterative control laws are analyzed for the local value iteration ADP algorithm. New termination criteria are established, which terminate the iterative local ADP algorithm with an admissible approximate optimal control law. Finally, simulation results are given to illustrate the performance of the developed algorithm.

Understanding the effects of packing and chemical terminations on the optical excitations of azobenzene-functionalized self-assembled monolayers

NASA Astrophysics Data System (ADS)

Cocchi, Caterina; Draxl, Claudia

2017-10-01

In a first-principles study based on many-body perturbation theory, we analyze the optical excitations of azobenzene-functionalized self-assembled monolayers (SAMs) with increasing packing density and different terminations, considering for comparison the corresponding gas-phase molecules and dimers. Intermolecular coupling increases with the density of the chromophores independently of the functional groups. The intense π → π* resonance that triggers photo-isomerization is present in the spectra of isolated dimers and diluted SAMs, but it is almost completely washed out in tightly packed architectures. Intermolecular coupling is partially inhibited by mixing differently functionalized azobenzene derivatives, in particular when large groups are involved. In this way, the excitation band inducing the photo-isomerization process is partially preserved and the effects of dense packing partly counterbalanced. Our results suggest that a tailored design of azobenzene-functionalized SAMs which optimizes the interplay between the packing density of the chromophores and their termination can lead to significant improvements in the photo-switching efficiency of these systems.

Sight-Reading Requirements at Concert Band Festivals: A National Survey

ERIC Educational Resources Information Center

Paul, Timothy A.

2010-01-01

This study, a replication and extension of work by Norris (2004), examined sight-reading requirements at middle and high school large-group band festivals across the United States. As in the earlier investigation, answers to the following questions were solicited from all 50 states: (1) Are there ratings-based large-group band festivals? (2) Is…