Spectroscopic study of the Lambda hypernuclei by the (e,e'K +) reaction

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

Miyoshi, Toshinobu

Hypernuclear spectroscopy study via the (e,e'K +) reaction has been carried out for the first time, establishing a new technique to study Lambda hypernuclei. The high quality electron beam at Jefferson Lab made it possible to measure Lambda hypernuclear spectra with an energy resolution better than 1 MeV (FWHM). The present experiment was designed to make full use of the virtual photon flux, which peaks at very forward angles, by detecting scattered electrons at 0 degrees. Scattered positive kaons were also detected near 0 degrees, where the cross section of the kaon photo-production is maximized. This unique kinematical configuration was realized with the HyperNuclear Spectrometer System (HNSS), which consisted of the Short-Orbit Spectrometer, the Enge Split-Pole Spectrometer, and the splitter magnet. Themore » $$12\\atop{Λ}$$B mass spectrum was measured in the 12C(e,e'K +)$$12\\atop{Λ}$$ reaction with 0.9 MeV (FWHM) energy resolution. The averaged binding energy of the $$12\\atop{Λ}$$B ground state doublet was obtained to be 11.7 ± 0.1 (statistical) ± 0.3 (systematic) MeV, which is consistent with emulsion data. The general spectral structure of the 12C(e,e'K +) $$12\\atop{Λ}$$B reaction was found to be similar to that of the 12C(Λ +,K +)$$12\\atop{Λ}$$C reaction, showing characteristic peaks corresponding to sLambda and pLambda orbits, as well as a few core-excited states. The cross section of the $$12\\atop{Λ}$$B ground state doublet was derived to be 117 ± 13 (statistical) ± 14 (systematic) nb/sr. The theoretical prediction of the cross section was consistent with the present result, validating DWIA calculation for hypernuclear yields. The present study proved the effectiveness of the (e,e'K +) reaction for future Lambda hypernuclear spectroscopy studies.« less

Microwave response of high transition temperature superconducting thin films

NASA Technical Reports Server (NTRS)

Miranda, Felix Antonio

1991-01-01

We have studied the microwave response of YBa2Cu3O(7 - delta), Bi-Sr-Ca-Cu-O, and Tl-Ba-Ca-Cu-O high transition temperature superconducting (HTS) thin films by performing power transmission measurements. These measurements were carried out in the temperature range of 300 K to 20 K and at frequencies within the range of 30 to 40 GHz. Through these measurements we have determined the magnetic penetration depth (lambda), the complex conductivity (sigma(sup *) = sigma(sub 1) - j sigma(sub 2)) and the surface resistance (R(sub s)). An estimate of the intrinsic penetration depth (lambda approx. 121 nm) for the YBa2Cu3O(7 - delta) HTS has been obtained from the film thickness dependence of lambda. This value compares favorably with the best values reported so far (approx. 140 nm) in single crystals and high quality c-axis oriented thin films. Furthermore, it was observed that our technique is sensitive to the intrinsic anisotropy of lambda in this superconductor. Values of lambda are also reported for Bi-based and Tl-based thin films. We observed that for the three types of superconductors, both sigma(sub 1) and sigma(sub 2) increased when cooling the films below their transition temperature. The measured R(sub s) are in good agreement with other R(sub S) values obtained using resonant activity techniques if we assume a quadratic frequency dependence. Our analysis shows that, of the three types of HTS films studied, the YBa2Cu3O(7 - delta) thin film, deposited by laser ablation and off-axis magnetron sputtering are the most promising for microwave applications.

Product lambda-doublet ratios as an imprint of chemical reaction mechanism

PubMed Central

Jambrina, P. G.; Zanchet, A.; Aldegunde, J.; Brouard, M.; Aoiz, F. J.

2016-01-01

In the last decade, the development of theoretical methods has allowed chemists to reproduce and explain almost all of the experimental data associated with elementary atom plus diatom collisions. However, there are still a few examples where theory cannot account yet for experimental results. This is the case for the preferential population of one of the Λ-doublet states produced by chemical reactions. In particular, recent measurements of the OD(2Π) product of the O(3P)+D2 reaction have shown a clear preference for the Π(A′) Λ-doublet states, in apparent contradiction with ab initio calculations, which predict a larger reactivity on the A′′ potential energy surface. Here we present a method to calculate the Λ-doublet ratio when concurrent potential energy surfaces participate in the reaction. It accounts for the experimental Λ-doublet populations via explicit consideration of the stereodynamics of the process. Furthermore, our results demonstrate that the propensity of the Π(A′) state is a consequence of the different mechanisms of the reaction on the two concurrent potential energy surfaces PMID:27834381

Exchange and Inelastic OH(+) + H Collisions on the Doublet and Quartet Electronic States.

PubMed

Bulut, Niyazi; Lique, François; Roncero, Octavio

2015-12-17

The exchange and inelastic state-to-state cross sections for the OH(+) + H collisions are computed from wave packet calculations using the doublet and quartet ground electronic potential energy surface (PES) correlating to the open shell reactants, for collision energies in the range of 1 meV to 0.7 eV. The doublet PES presents a deep insertion well, of ≈6 eV, but the exchange reaction has a rather low probability, showing that the mechanism is not statistical. This well is also responsible of a rather high rotational energy transfer, which makes the rigid-rotor approach overestimate the cross section for low Δj transitions and for high collisonal energies. The quartet PES, with a much shallower well, also presents a low exchange reaction cross section, but the inelastic state-to-state cross sections are very well reproduced by rigid-rotor calculations. When the electronic partition is used to obtain the total state-to-state cross section, the contribution of the doublet state becomes small, and the resulting total cross sections become close to those obtained for the quartet state. Thus, the total (quartet and doublet) cross sections for this open shell system can be reproduced rather satisfactorily by those obtained with the rigid-rotor approximation on the quartet state. Finally, we compare the new OH(+)-H cross sections with OH(+)-He ones recently computed. We found significant differences, especially for transitions with large Δj showing that specific OH(+)-H calculations had to be performed to accurately analyze the OH(+) emission from interstellar molecular clouds.

Simultaneous X-ray, UV, and Optical Variations in lambda ERI (B2e)

NASA Astrophysics Data System (ADS)

Smith, M. A.; Murakami, T.; Anandarao, B.

1996-12-01

We have carried out a simultaneous observing campaign on the prototypical Be star lambda Eri using ground stations and ROSAT, ASCA, IUE, and Voyager spacecrafts during the week of February-March 1995; a smaller campaign was carried out the following September. In late February lambda Eri showed extraordinary disk-wind activity. ROSAT/HRI monitoring disclosed no large flares such as ROSAT observed in 1991 in lambda Eri. Possible low amplitude fluctuations in the 1995 data occurred at the same time with unusual activity in Hα , HeI lambda 6678, HeII lambda 1640, CIII, and the CIV doublet. The helium line activity suggests that mass ejection occurred at the base of the wind. The strong CIII and CIV lines implies that shock interactions originated in the wind flow. It is not clear that the X-ray fluctuations are directly related to the increases in wind line absorption. Within hours of the mild X-ray flux variations found by ROSAT on February 28, the Voyager UVS observed a ``ringing" that decayed over three 3-hr. cycles. The amplitude of these fluctuations was large (50%) at lambda lambda 950-1100, decreased rapidly with wavelength, and faded to nondetection above lambda 1300. Various considerations indicate that these continuum variations were not due to an instrument pathology in the UVS. Rather, they appear to be due to a time-dependent flux deficit in the lambda lambda 1250 during the minima of these cycles. We outline a scenario in which dense plasma over the star's surface is alternately heated and cooled quasi-periodically to produce the flux changes. Additional examples of this new phenomenon are needed. Amateur astronomers can make a significant contribution to the understanding of flickering in Be star light curves during their outburst phases. We also draw attention to an increase in the emission of the Hα line that occurred at about the same time the FUV ringing started. This increased emission hints that ~ 50,000K plasma near the star's surface can infuence the circumstellar disc some distance away by its increased Lyman continuum flux.

Elastic anomalies associated with two successive transitions of PrV2Al20 probed by ultrasound measurements

NASA Astrophysics Data System (ADS)

Nakanishi, Y.; Taniguchi, M.; Nakamura, M. M.; Hasegawa, J.; Ohyama, R.; Nakamura, M.; Yoshizawa, M.; Tsujimoto, M.; Nakatsuji, S.

2018-05-01

We have performed the ultrasound measurement on the non-Kramers doublet system PrV2Al20 in order to figure out the low-temperature multi-quadrupolar phase appearing at low temperatures. Elastic anomalies and their systematic magnetic field evolution were clearly observed in the temperature dependence of the elastic constant C44(T). We discuss the possible origin and implications of the rich variety of phases emerging from the simple ground state: the well-isolated non-Kramers doublet Γ3 subspace.

Bivariate- distribution for transition matrix elements in Breit-Wigner to Gaussian domains of interacting particle systems.

PubMed

Kota, V K B; Chavda, N D; Sahu, R

2006-04-01

Interacting many-particle systems with a mean-field one-body part plus a chaos generating random two-body interaction having strength lambda exhibit Poisson to Gaussian orthogonal ensemble and Breit-Wigner (BW) to Gaussian transitions in level fluctuations and strength functions with transition points marked by lambda = lambda c and lambda = lambda F, respectively; lambda F > lambda c. For these systems a theory for the matrix elements of one-body transition operators is available, as valid in the Gaussian domain, with lambda > lambda F, in terms of orbital occupation numbers, level densities, and an integral involving a bivariate Gaussian in the initial and final energies. Here we show that, using a bivariate-t distribution, the theory extends below from the Gaussian regime to the BW regime up to lambda = lambda c. This is well tested in numerical calculations for 6 spinless fermions in 12 single-particle states.

Phase transition in crystalline benzil : an infrared study of vibrational excitons.

NASA Astrophysics Data System (ADS)

Le Roy, A.; Et-Tabti, O.; Guérin, R.

1993-03-01

The molecular crystal of benzil, [C 6 H 5 CO] 2, is known to undergo a phase transition at T c = 84 K. The phase transition is from a high temperature trigonal phase with space group D 43 (P3 121) to a low temperature monoclinic phase with space group C 32 (C 2). This paper reports a study of the exciton structure of the infrared bands of benzil as a function of temperature in the vicinity of T c = 84 K. The benzil molecule belongs to the C 2 molecular point group. Group theoretical analysis of the exciton structure of infrared bands predicts two components for molecular B modes and one component for molecular A modes in the high temperature phase. Below T c all the internal modes of benzil are expected to split into two components. Our experimental results show that the A molecular modes are resolved in a doublet structure in the low temperature phase whereas only one component is observed above T c. The doublet structure of infrared bands is studied as a function of temperature in the vicinity of T c. These splittings of crystal states in the low temperature phase are found to be described by a ¦T c - T¦ β law. The temperature dependence of the doublet structure of internal B modes is also studied below and above T c.

Design of a Low Gravity Simulator for Performing Non-Equilibrium Investigations near the Lambda Transition of ^4He

NASA Technical Reports Server (NTRS)

Israelsson, U. E.; Duncan, R. V.

1993-01-01

A design is presented of a low gravity simulator where a magnetic field gradient is employed to oppose the hydrostatic pressure effects of gravity. It appears feasible to reduce the effective gravity environment of the helium in the cell by about two orders of magnitude. The corresponding shift in transition temperature with vertical height would be reduced to 12.7 nK/cm. Methods for instrumenting the simulator to perform high resolution investigations of non-equilibrium phenomena near the lambda point are presented. The advantages of using a low gravity simulator in searching for the predicted change in character of the superfluid transition from continuous to first order in the presence of a heat current are also discussed.

Technical challenges involved in supporting the Lambda Point Experiment

NASA Technical Reports Server (NTRS)

Petrac, D.; Israelsson, U.; Otth, D.; Simmons, L.; Staats, J.; Thompson, A.

1990-01-01

The Lambda Point Experiment (LPE) is one of the instruments included in the U.S. Microgravity Payload Mission 1 planned for one of the Space Shuttle flights in 1992. The objective of the experiment is to measure the heat capacity of liquid helium within a narrow interval around the transition between superfluid and normal helium (the lambda point) with an unprecedented temperature resolution of about 10 to the -10th. Multiple technical challenges are presented in the areas of structural support, safety analysis, and modal frequency tests. This paper describes the technical challenges of JPL's multidisciplinary involvement in support of these experiments in microgravity.

DNA binding site characterization by means of Rényi entropy measures on nucleotide transitions.

PubMed

Perera, A; Vallverdu, M; Claria, F; Soria, J M; Caminal, P

2008-06-01

In this work, parametric information-theory measures for the characterization of binding sites in DNA are extended with the use of transitional probabilities on the sequence. We propose the use of parametric uncertainty measures such as Rényi entropies obtained from the transition probabilities for the study of the binding sites, in addition to nucleotide frequency-based Rényi measures. Results are reported in this work comparing transition frequencies (i.e., dinucleotides) and base frequencies for Shannon and parametric Rényi entropies for a number of binding sites found in E. Coli, lambda and T7 organisms. We observe that the information provided by both approaches is not redundant. Furthermore, under the presence of noise in the binding site matrix we observe overall improved robustness of nucleotide transition-based algorithms when compared with nucleotide frequency-based method.

Thermal Conductivity Measurements of Helium 4 Near the Lambda-Transition Using a Magnetostrictive Low Gravity Simulator

NASA Technical Reports Server (NTRS)

Larson, Melora; Israelsson, Ulf E.

1995-01-01

There has been a recent increase in interest both experimentally and theoretically in the study of liquid helium very near the lambda-transition in the presence of a heat current. In traditional ground based experiments there are gravitationally induced pressure variations in any macroscopic helium sample that limit how closely the transition can be approached. We have taken advantage of the finite magnetic susceptibility of He 4 to build a magnetostrictive low gravity simulator. The simulator consists of a superconducting magnet with field profile shaped to counteract the force of gravity in a helium sample. When the magnet is operated with B x dB/dz = 21T(exp 2)/cm at the location of the cell, the gravitationally induced pressure variations will be canceled to within 1% over a volume of 0.5 cm in height and 0.5 cm in diameter. This technique for canceling the pressure variations in a long sample cell allows the lambda-transition to be studied much closer in reduced temperature and under a wider range of applied heat currents than is possible using other ground based techniques. Preliminary results using this low gravity simulator and the limitations of the magnetostrictive technique in comparison to doing space based experiments will be presented.

Laboratory detection of the C3N an C4H free radicals

NASA Technical Reports Server (NTRS)

Gottlieb, C. A.; Gottlieb, E. W.; Thaddeus, P.; Kawamura, H.

1983-01-01

The millimeter-wave spectra of the linear carbon chain free radicals C3N and C4H, first identified in IRC + 10216 and hitherto observed only in a few astronomical sources, have been detected with a Zeeman-modulated spectrometer in laboratory glow discharges through low pressure flowing mixtures of N2 + HC3N and He + HCCH, respectively. Four successive rotational transitions between 168 and 198 GHz have been measured for C3N, and five rotational transitions between 143 and 200 GHz for C4H; each is a well-resolved spin doublet owing to the unpaired electron present in both species. Precise values for the rotational, centrifugal distortion, and spin doubling constants have been obtained, which, with hyperfine constants derived from observations of the lower rotational transitions in the astronomical source TMC 1, allow all the rotational transitions of C3N and C4H at frequencies less than 300 GHz to be calculated to an absolute accuracy exceeding 1 ppm.

Alpha decay hindrance factors and reflection asymmetry in nuclei

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

Sheline, R.K.; Bossinga, B.B.

1991-07-01

All available hindrance factors of alpha transitions to low-lying negative-parity states in doubly even nuclei, to odd-{ital A} parity doublets and to doubly odd parity doublet bands, are used to study the systematics of reflection asymmetry in the {ital A}{similar to}218--230 region. Special attention is given to the polarization effect of the odd particle in increasing reflection asymmetry and therefore decreasing hindrance factors to the opposite parity states of octupole bands.

Nonstationary behavior of a high-spin molecule in a bifrequency alternating current magnetic field

NASA Astrophysics Data System (ADS)

Tokman, I. D.; Vugalter, G. A.

2002-07-01

An interaction of a high-spin molecule with a bifrequency ac magnetic field, occurring at times much shorter than the molecule relaxation times, has been considered. The molecule is subjected to a dc magnetic field perpendicular to the easy anisotropy axis of the molecule. The bifrequency ac field is a superposition of two ac fields, one of which is perpendicular to the easy anisotropy axis and causes resonant transitions between the lower states of the fundamental and first excited doublets. The other ac field is parallel to the easy anisotropy axis and has a frequency much smaller than the frequency of the first ac field. It has been shown that, first, the molecule can absorb or emit energy, depending on the frequency of the low-frequency ac field, second, the bifrequency ac magnetic field induces tunneling of the molecule magnetization with the Rabi frequency. The conditions of observation of the effects predicted are discussed.

{lambda}{sub b}{yields}p, {lambda} transition form factors from QCD light-cone sum rules

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

Wang Yuming; Lue Caidian; Shen Yuelong

2009-10-01

Light-cone sum rules for the {lambda}{sub b}{yields}p, {lambda} transition form factors are derived from the correlation functions expanded by the twist of the distribution amplitudes of the {lambda}{sub b} baryon. In terms of the {lambda}{sub b} three-quark distribution amplitude models constrained by the QCD theory, we calculate the form factors at small momentum transfers and compare the results with those estimated in the conventional light-cone sum rules (LCSR) and perturbative QCD approaches. Our results indicate that the two different versions of sum rules can lead to the consistent numbers of form factors responsible for {lambda}{sub b}{yields}p transition. The {lambda}{sub b}{yields}{lambda}more » transition form factors from LCSR with the asymptotic {lambda} baryon distribution amplitudes are found to be almost 1 order larger than those obtained in the {lambda}{sub b}-baryon LCSR, implying that the preasymptotic corrections to the baryonic distribution amplitudes are of great importance. Moreover, the SU(3) symmetry breaking effects between the form factors f{sub 1}{sup {lambda}{sub b}}{sup {yields}}{sup p} and f{sub 1}{sup {lambda}{sub b}}{sup {yields}}{sup {lambda}} are computed as 28{sub -8}{sup +14}% in the framework of {lambda}{sub b}-baryon LCSR.« less

System for testing optical fibers

DOEpatents

Davies, Terence J.; Franks, Larry A.; Nelson, Melvin A.

1981-01-01

A system for nondestructively determining the attenuation coefficient, .alpha.(.lambda.), of low-loss optical fiber wave guides. Cerenkov light pulses are generated at a plurality of locations in the fiber by a beam of charged particles. The transit times of selected spectral components and their intensities are utilized to unfold the .alpha.(.lambda.) values over the measured spectrum.

First Astronomical Use of Multiplexed Transition Edge Sensor Bolometers

NASA Technical Reports Server (NTRS)

Staguhn, J. G.; Ames, T. A.; Benford, D. J.; Chervenak, J. A.; Grossman, E. N.; Irwin, K. D.; Khan, S. A.; Maffei, B.; Moseley, S. H.; Pajot, F.

2004-01-01

We present performance results based on the first astronomical use of multiplexed superconducting bolometers. The Fabry-Perot Interferometer Bolometer Research Experiment (FIBRE) is a broadband submillimeter spectrometer that achieved first light in June 2001 at the Caltech Submillimeter Observatory (CSO). FIBRE's detectors are superconducting transition edge sensor (TES) bolometers read out by a SQUID multiplexer. The Fabry-Perot uses a low resolution grating to order sort the incoming light. A linear bolometer array consisting of 16 elements detects this dispersed light, capturing 5 orders simultaneously from one position on the sky. With tuning of the Fabry-Perot over one free spectral range, a spectrum covering Delta lambda/lambda = 1/7 at a resolution of delta lambda/lambda approx. 1/1200 can be acquired. This spectral resolution is sufficient to resolve Doppler-broadened line emission from external galaxies. FIBRE operates in the 350 m and 450 m bands. These bands cover line emission from the important star formation tracers neutral carbon (CI) and carbon monoxide (CO). We have verified that the multiplexed bolometers are photon noise limited even with the low power present in moderate resolution spectrometry.

The dynamics of the optically driven Lambda transition of the 15N-V- center in diamond.

PubMed

González, Gabriel; Leuenberger, Michael N

2010-07-09

Recent experimental results demonstrate the possibility of writing quantum information in the ground state triplet of the (15)N-V(-) center in diamond by means of an optically driven spin non-conserving two-photon Lambda transition in the presence of a strong applied electric field. Our calculations show that the hyperfine interaction in the (15)N-V(-) center is capable of mediating such a transition. We use a density matrix approach to describe the exact dynamics for the allowed optical spin non-conserving transitions between two sublevels of the ground state triplet. This approach allows us to calculate the Rabi oscillations, by means of which we obtain a Rabi frequency with an upper bound determined by the hyperfine interaction. This result is crucial for the success of implementing optically driven quantum information processing with the N-V center in diamond.

DNA binding sites characterization by means of Rényi entropy measures on nucleotide transitions.

PubMed

Perera, Alexandre; Vallverdu, Montserrat; Claria, Francesc; Soria, José Manuel; Caminal, Pere

2006-01-01

In this work, parametric information-theory measures for the characterization of binding sites in DNA are extended with the use of transitional probabilities on the sequence. We propose the use of parametric uncertainty measure such as Renyi entropies obtained from the transition probabilities for the study of the binding sites, in addition to nucleotide frequency based Renyi measures. Results are reported in this manuscript comparing transition frequencies (i.e. dinucelotides) and base frequencies for Shannon and parametric Renyi for a number of binding sites found in E. Coli, lambda and T7 organisms. We observe that, for the evaluated datasets, the information provided by both approaches is not redundant, as they evolve differently under increasing Renyi orders.

Sound velocity and absorption in a coarsening foam.

PubMed

Mujica, Nicolás; Fauve, Stéphan

2002-08-01

We present experimental measurements of sound velocity and absorption in a commercial shaving foam. We observe that both quantities evolve with time as the foam coarsens increasing its mean bubble radius . By varying the acoustic frequency we probe the foam from the large wavelength regime, lambda approximately 1500, down to the scale lambda approximately 20. Sound absorption alpha varies significantly with both the foam age and the excitation frequency. After an initial transition time of 20 min, the attenuation per wavelength, alphalambda, varies linearly with the foam age. In addition, for evolution times smaller than approximately 90 min, we observe that alphalambda scales linearly with both foam age and frequency. From these scalings we show that the thermal dissipation mechanism is the dominant one. Sound velocity c is initially frequency independent but the medium becomes slightly dispersive as the foam coarsens. We observe that sound velocity depends on the evolution of the structure of the foam, even in the large wavelength regime. After 2 h of foam coarsening, c decreases at least by a factor of 20%, due to the softening of the foam. These facts are explained by considering the liquid matrix elasticity, due to the presence of surfactant molecules. A simple model of foam structure, combined with results of Biot's theory for porous media, gives both good qualitative and quantitative agreement with our experimental results in the low frequency regime.

Gauss-Legendre quadrature method used to evaluate the spatio-temporal intensity of ultrashort pulses in the focal region of lenses.

PubMed

García-Martínez, L; Rosete-Aguilar, M; Garduño-Mejia, J

2012-01-20

We analyze the spatio-temporal intensity of sub-20 femtosecond pulses with a carrier wavelength of 810 nm along the optical axis of low numerical aperture achromatic and apochromatic doublets designed in the IR region by using the scalar diffraction theory. The diffraction integral is solved by expanding the wave number around the carrier frequency of the pulse in a Taylor series up to third order, and then the integral over the frequencies is solved by using the Gauss-Legendre quadrature method. The numerical errors in this method are negligible by taking 96 nodes and the computational time is reduced by 95% compared to the integration method by rectangles. We will show that the third-order group velocity dispersion (GVD) is not negligible for 10 fs pulses at 810 nm propagating through the low numerical aperture doublets, and its effect is more important than the propagation time difference (PTD). This last effect, however, is also significant. For sub-20 femtosecond pulses, these two effects make the use of a pulse shaper necessary to correct for second and higher-order GVD terms and also the use of apochromatic optics to correct the PTD effect. The design of an apochromatic doublet is presented in this paper and the spatio-temporal intensity of the pulse at the focal region of this doublet is compared to that given by the achromatic doublet. © 2012 Optical Society of America

Dark matter and electroweak phase transition in the mixed scalar dark matter model

NASA Astrophysics Data System (ADS)

Liu, Xuewen; Bian, Ligong

2018-03-01

We study the electroweak phase transition in the framework of the scalar singlet-doublet mixed dark matter model, in which the particle dark matter candidate is the lightest neutral Higgs that comprises the C P -even component of the inert doublet and a singlet scalar. The dark matter can be dominated by the inert doublet or singlet scalar depending on the mixing. We present several benchmark models to investigate the two situations after imposing several theoretical and experimental constraints. An additional singlet scalar and the inert doublet drive the electroweak phase transition to be strongly first order. A strong first-order electroweak phase transition and a viable dark matter candidate can be accomplished in two benchmark models simultaneously, for which a proper mass splitting among the neutral and charged Higgs masses is needed.

Characteristics and significance of doublets on needle EMG.

PubMed

Lamb, Christopher J; Rubin, Devon I

2017-04-01

Voluntary doublets are electrophysiological phenomena thought to be associated with metabolic derangements or neuromuscular conditions. We prospectively studied 232 consecutive patients examined by a single examiner during routine electromyography (EMG) to determine the frequency of doublets in individual patients, specific muscles, neuromuscular conditions, electrolyte levels, and doublet characteristics. Of 232 patients, 25 (10.7%) exhibited doublets. The mean age was 59 (52% men). Only 32 of 1,303 (2.5%) muscles exhibited doublets. Lower extremity and paraspinal groups represented 91% of muscles with doublets. Doublet frequency grouped by EMG diagnoses was: ALS (3 of 11; 27.1%), myopathy (3 of 10; 30.0%), axonal polyneuropathy (7 of 29; 24.1%), and no disease (7 of 109; 6.4%). There were no differences in serum electrolytes between doublet and matched subjects. Doublets occur in approximately 10% of patients, more commonly in lower extremity and paraspinal muscles, and are not correlated with a specific metabolic abnormality or neuromuscular condition. Muscle Nerve 55: 598-600, 2017. © 2016 Wiley Periodicals, Inc.

Magnetic penetration depth of YBa2Cu3O(7-delta) thin films determined by the power transmission method

NASA Technical Reports Server (NTRS)

Heinen, Vernon O.; Miranda, Felix A.; Bhasin, Kul B.

1992-01-01

A power transmission measurement technique was used to determine the magnetic penetration depth (lambda) of YBa2Cu3O(7-delta) superconducting thin films on LaAlO3 within the 26.5 to 40.0 GHz frequency range, and at temperatures from 20 to 300 K. Values of lambda ranging from 1100 to 2500 A were obtained at low temperatures. The anisotropy of lambda was determined from measurements of c-axis and a-axis oriented films. An estimate of the intrinsic value of lambda of 90 +/- 30 nm was obtained from the dependence of lambda on film thickness. The advantage of this technique is that it allows lambda to be determined nondestructively.

Coherent manipulation of mononuclear lanthanide-based single-molecule magnets

NASA Astrophysics Data System (ADS)

Datta, Saiti; Ghosh, Sanhita; Krzystek, Jurek; Hill, Stephen; Del Barco, Enrique; Cardona-Serra, Salvador; Coronado, Eugenio

2010-03-01

Using electron spin echo (ESE) spectroscopy, we report measurements of the longitudinal (T1) and transverse (T2) relaxation times of diluted single-crystals containing recently discovered mononuclear lanthanide-based single-molecule magnets (SMMs) encapsulated in polyoxometallate cages [AlDamen et al. J. Am. Chem. Soc. 130, 8874 -- 8875 (2008)]. This encapsulation offers the potential for preserving bulk SMM properties outside of a crystal, e.g. in molecular spintronic devices. The magnetic anisotropy in these complexes arises from the spin-orbit splitting of the ground state J multiplet of the lanthanide ion in the presence of a ligand field. At low frequencies only hyperfine-split transitions within the lowest ground state ±mJ doublet are observed. Spin relaxation times were measured for a holmium complex, and the results were compared for different hyperfine transitions and crystal dilutions. Clear Rabi oscillations were also observed, indicating that one can manipulate the spin coherently in these complexes.

Helium-4 Experiments near T-lambda in a Low-Gravity Simulator

NASA Technical Reports Server (NTRS)

Liu, Yuanming; Larson, Melora; Israelsson, Ulf

2000-01-01

We report our studies of gravity cancellation in a liquid helium sample cell along the lambda-line using a low-gravity simulator facility. The simulator consists of a superconducting magnet capable of producing B(delta-B/delta-z) = 22squareT)/cm. We have verified experimentally that the simulator can cancel gravity to about 0.01g in a cylindrical sample volume of 0.5 cm in diameter and 0.5 cm in height. This allows us to approach more closely the superfluid transition without entering the normal-superfluid two phase region induced by gravity. We also present the measurements of T-c(Q,P): depression of the superfluid transition temperature by a heat current(Q) along the lambda-line (P). The results are consistent with the Renormalization-group theory calculation. Measurements of thermal expansion coefficient in a heat current will also be discussed. The work has been carried out by JPL, California Institute of Technology under contract to NASA.

Investigation of the summation of copper-vapour laser frequencies

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

Karpukhin, Vyacheslav T; Konev, Yu B; Malikov, Mikhail M

1998-09-30

An investigation was made of the conversion of the copper-vapour laser radiation ( {lambda}{sub 1} = 0.51 {mu}m and {lambda}{sub 2} = 0.578 {mu}m) into UV radiation at the sum frequency ({lambda}{sub 3} = 0.271 {mu}m) in a DKDP crystal. The operation of this frequency converter was compared for two magnifications of the laser cavity: M = 5 and 200. The best results were obtained for M = 200 (average UV radiation power 0.75 W, conversion efficiency 12%). A study was made of the characteristics of the formation of radiation pulses representing the two lines in the laser beam asmore » a whole and in its weakly diverging core. In a low-divergence beam the yellow- and green-line pulses were emitted practically simultaneously with approximately the same peak power, which facilitated the sum-frequency generation. (nonlinear optical phenomena)« less

Broadband Direct Detection Submillimeter Spectrometer with Multiplexed Superconducting Transition Edge Thermometer Bolometers

NASA Technical Reports Server (NTRS)

Benford, D. J.; Ames, T. A.; Chervenak, J. A.; Moseley, S. H.; Shafer, R. A.; Staguhn, J. G.; Voellmer, G. M.; Pajot, F.; Rioux, C.; Phillips, T. G.;

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

Alanne, Tommi; Kainulainen, Kimmo; Helsinki Institute of Physics, University of Helsinki,P.O. Box 64, FI-00014 Helsinki

We investigate an extension of the Standard Model containing two Higgs doublets and a singlet scalar field (2HDSM). We show that the model can have a strongly first-order phase transition and give rise to the observed baryon asymmetry of the Universe, consistent with all experimental constraints. In particular, the constraints from the electron and neutron electric dipole moments are less constraining here than in pure two-Higgs-doublet model (2HDM). The two-step, first-order transition in 2HDSM, induced by the singlet field, may lead to strong supercooling and low nucleation temperatures in comparison with the critical temperature, T{sub n}≪T{sub c}, which can significantlymore » alter the usual phase-transition pattern in 2HD models with T{sub n}≈T{sub c}. Furthermore, the singlet field can be the dark matter particle. However, in models with a strong first-order transition its abundance is typically but a thousandth of the observed dark matter abundance.« less

Benchmarks of simple, generic, shaped plates for validation of low-frequency electromagnetic computational codes

NASA Technical Reports Server (NTRS)

Deshpande, M. D.; Cockrell, C. R.; Beck, F. B.; Nguyen, T. X.

1993-01-01

The validation of low-frequency measurements and electromagnetic (EM) scattering computations for several simple, generic shapes, such as an equilateral-triangular plate, an equilateral-triangular plate with a concentric equilateral-triangular hole, and diamond- and hexagonal-shaped plates, is discussed. The plates were constructed from a thin aluminum sheet with a thickness of 0.08 cm. EM scattering by the planar plates was measured in the experimental test range (ETR) facility of NASA Langley Research Center. The dimensions of the plates were selected such that, over the frequency range of interest, the dimensions were in the range of lambda0 to 3(lambda0). In addition, the triangular plate with a triangular hole was selected to study internal-hole resonances.

Multiband VLBI Observations of CTA102

NASA Technical Reports Server (NTRS)

Rantakyro, F. T.; Baath, L. B.; Dallacasa, D.; Jones, D. L.; Wehrle, A. E.

1995-01-01

The source CTA102, known to exhibit low frequency variability, has been observed at six epochs (three at lambda 32 cm, two at lambda 18 cm, and one at lambda l.3 cm) with intercontinental VLBI arrays. On the basis of the changes observed in the structure, we believe that the flux density variations at these wavelengths are due to intrinsic processes and not due to interstellar scintillation. This source exhibits behaviour suggestive of being expanding with a very high apparent transverse velocity.

Properties of nearly perfect crystals at very low temperatures

NASA Technical Reports Server (NTRS)

Weber, J.; Hamilton, J. J.

1994-01-01

Data shows that the frequency stability of 5 MHz AT-cut quartz crystal oscillators is improved by lowering the temperature to 4.3 K. The resultant level of stability is apparently not, at this point, sufficient for a clock accurate to 1 part in 10(exp 17). However, many improvements are possible in the scheme presented here. These would involve better temperature regulation, better crystal mounting and vibration isolation, and lower temperatures. Below the lambda-transition at 2.17 K the residual bubbling of the bath would be eliminated. Thus, the prospect of a successful clock built on this scheme is not ruled out.

The Higgs vacuum uplifted: revisiting the electroweak phase transition with a second Higgs doublet

NASA Astrophysics Data System (ADS)

Dorsch, G. C.; Huber, S. J.; Mimasu, K.; No, J. M.

2017-12-01

The existence of a second Higgs doublet in Nature could lead to a cosmological first order electroweak phase transition and explain the origin of the matter-antimatter asymmetry in the Universe. We explore the parameter space of such a two-Higgs-doublet-model and show that a first order electroweak phase transition strongly correlates with a significant uplifting of the Higgs vacuum w.r.t. its Standard Model value. We then obtain the spectrum and properties of the new scalars H 0, A 0 and H ± that signal such a phase transition, showing that the decay A 0 → H 0 Z at the LHC and a sizable deviation in the Higgs self-coupling λ hhh from its SM value are sensitive indicators of a strongly first order electroweak phase transition in the 2HDM.

Rotation and rotation-vibration spectroscopy of the 0+-0- inversion doublet in deuterated cyanamide.

PubMed

Kisiel, Zbigniew; Kraśnicki, Adam; Jabs, Wolfgang; Herbst, Eric; Winnewisser, Brenda P; Winnewisser, Manfred

2013-10-03

The pure rotation spectrum of deuterated cyanamide was recorded at frequencies from 118 to 649 GHz, which was complemented by measurement of its high-resolution rotation-vibration spectrum at 8-350 cm(-1). For D2NCN the analysis revealed considerable perturbations between the lowest Ka rotational energy levels in the 0(+) and 0(-) substates of the lowest inversion doublet. The final data set for D2NCN exceeded 3000 measured transitions and was successfully fitted with a Hamiltonian accounting for the 0(+) ↔ 0(-) coupling. A smaller data set, consisting only of pure rotation and rotation-vibration lines observed with microwave techniques was obtained for HDNCN, and additional transitions of this type were also measured for H2NCN. The spectroscopic data for all three isotopic species were fitted with a unified, robust Hamiltonian allowing confident prediction of spectra well into the terahertz frequency region, which is of interest to contemporary radioastronomy. The isotopic dependence of the determined inversion splitting, ΔE = 16.4964789(8), 32.089173(3), and 49.567770(6) cm(-1), for D2NCN, HDNCN, and H2NCN, respectively, is found to be in good agreement with estimates from a simple reduced quartic-quadratic double minimum potential.

Parity doublet structures in doubly-odd 216Fr

NASA Astrophysics Data System (ADS)

Pragati, Â.; Deo, A. Y.; Tandel, S. K.; Bhattacharjee, S. S.; Chakraborty, S.; Rai, S.; Wahid, S. G.; Kumar, S.; Muralithar, S.; Singh, R. P.; Bala, Indu; Garg, Ritika; Jain, A. K.

2018-04-01

Parity doublet structures are established in 216Fr, which lies at the lower boundary of enhanced octupole collectivity in the trans-lead region. The newly identified levels are established as the simplex partner of a previously reported band leading to parity doublets with small (˜55 keV) average energy splitting, a feature typical of nuclei with near-static octupole deformation. The observed levels do not follow a regular pattern of rotational bands, indicating low quadrupole collectivity. However, enhanced octupole correlations are evident from the small energy splitting and large B(E1)/B(E2) values. Staggering in E1 transition energies and B(E1)/B(E2) ratios is noted. The enhancement of octupole correlations in 216Fr is attributed to the availability of a neutron orbital with a K = 3/2 component.

Low-energy measurements of electron-photon angular correlation in electron-impact excitation of the 2/sup 1/P state of helium

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

Steph, N.C.; Golden, D.E.

1983-03-01

Electron-photon angular correlations between electrons which have excited the 2/sup 1/P state of He and photons from the 2/sup 1/P..-->..1/sup 1/S transition have been studied for 27-, 30-, 35-, and 40-eV incident electrons. Values of lambda and Vertical BarchiVertical Bar obtained from these measurements are compared to values obtained in distorted-wave and R-matrix calculations. The values of lambda and Vertical BarchiVertical Bar have been combined to examine the behavior of Vertical BarO/sub 1//sub -//sup colvertical-bar/ (lambda(1-lambda)sinVertical BarchiVertical Bar), the nonvanishing component of orientation. At 27 eV, a substantial decrease was observed in the values of lambda and Vertical BarO/sub 1//submore » -//sup colvertical-bar/, compared with their values for E> or =30 eV.« less

Absolute frequency measurement of a diode laser locked on a hyperfine component of 5S1/2-5D5/2 two-photon transitions of rubidium (lambda equals 778.1 nm, nu equals 385.3 THz)

NASA Astrophysics Data System (ADS)

Zondy, Jean-Jacques; Touahri, D.; Acef, Ouali; Hilico, L.; Abed, M.; Clairon, Andre; Millerioux, Yves P.; Felder, Raymond; de Beauvoir, Beatrice; Nez, Francois; Biraben, Francois; Julien, Lucile

1995-04-01

A frequency chain, derived from the one used to measure the absolute frequency ((nu) $= 473 THz) of the He-Ne/I2 optical standard, is currently being implemented in order to measure the frequency of a diode laser stabilized on the two-photon transition of rubidium vapor. The measurement scheme is based on the comparison of the frequency of this near-IR potential secondary standard to the 13th harmonic frequency of the R(12)-CO2/OsO4 LPTF secondary standard at (nu) equals 29.096 THz. Recent results on the frequency synthesis are reported, enabling the testing of long-term stability of this Rb-locked system with respect to the IR reference standard.

Normal modes in an overmoded circular waveguide coated with lossy material

NASA Technical Reports Server (NTRS)

Lee, C. S.; Lee, S. W.; Chuang, S. L.

1985-01-01

The normal modes in an overmoded waveguide coated with a lossy material are analyzed, particularly for their attenuation properties as a function of coating material, layer thickness, and frequency. When the coating material is not too lossy, the low-order modes are highly attenuated even with a thin layer of coating. This coated guide serves as a mode suppressor of the low-order modes, which can be particularly useful for reducing the radar cross section (RCS) of a cavity structure such as a jet inlet. When the coating material is very lossy, low-order modes fall into two distinct groups: highly and lowly attenuated modes. However, as a/lambda (a = radius of the cylinder; lambda = the free-space wavelength) increases, the separation between these two groups becomes less distinctive. The attenuation constants of most of the low-order modes become small, and decrease as a function of lambda sup 2/a sup 3.

Lamb dip CRDS of highly saturated transitions of water near 1.4 μm

NASA Astrophysics Data System (ADS)

Kassi, S.; Stoltmann, T.; Casado, M.; Daëron, M.; Campargue, A.

2018-02-01

Doppler-free saturated-absorption Lamb dips were measured at sub-Pa pressures on rovibrational lines of H216O near 7180 cm-1, using optical feedback frequency stabilized cavity ring-down spectroscopy. The saturation of the considered lines is so high that at the early stage of the ring down, the cavity loss rate remains unaffected by the absorption. By referencing the laser source to an optical frequency comb, transition frequencies are determined down to 100 Hz precision and kHz accuracy. The developed setup allows resolving highly K-type blended doublets separated by about 10 MHz (to be compared to a HWHM Doppler width on the order of 300 MHz). A comparison with the most recent spectroscopic databases is discussed. The determined K-type splittings are found to be very well predicted by the most recent variational calculations.

UVB-induced mutagenesis in hairless {lambda}lacZ-transgenic mice

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

Frijhoff, A.F.W.; Rebel, H.; Mientjes, E.J.

UVB-induced mutagenesis was studied in hairless 40.6 transgenic mice (Muta{trademark}Mouse), which contain the {lambda}gt1OlacZ shuttle vector as a target for mutagenesis. Mice were exposed at the dorsal side to either single doses of 200, 500, 800, or 1000 J/m{sup 2} UVB or to two successive irradiations of either 200 and 800 J/m{sup 2} UVB, with intervals of 1,3, or 5 days, or to 800 and 200 J/m{sup 2} UVB with a 5-day interval. At 23 days after the last exposure, lacZ mutant frequencies (MF) were determined in the epidermis. The lacZ MF increased linearly with increasing dose of UVB. Themore » mutagenic effect of two successive irradiations appeared to be additive. The UV-induced mutation spectrum was dominated by G:C{r_arrow}A:T transitions at dipyrimidine sites. DNA-sequence analysis of spontaneously mutated phages showed a diverse spectrum consisting of insertions, deletions and G:C {r_arrow} A:T transitions at CpG sites. the results indicate that the hairless {lambda}lacZ-transgenic mouse is a suitable in vivo model for studying UVB-induced mutations. 29 refs., 5 tabs.« less

The splitting and oscillator strengths for the 2S/2/S-2p/2/P/0/ doublet in lithium-like sulfur. [during Skylab observed solar flares

NASA Technical Reports Server (NTRS)

Pegg, D. J.; Forester, J. P.; Elston, S. B.; Griffin, P. M.; Peterson, R. S.; Thoe, R. S.; Vane, C. R.; Sellin, I. A.; Groeneveld, K.-O.

1977-01-01

The beam-foil technique has been used to study the 2S(2)S-2p(2)P(0) doublet in S XIV. The results confirm the doublet splitting measured aboard Skylab during solar flare events. In addition, the oscillator strengths for the resonance transitions comprising this doublet have been measured and found to agree well with recent relativistic f-value calculations.

Phase correlation of laser waves with arbitrary frequency spacing.

PubMed

Huss, A F; Lammegger, R; Neureiter, C; Korsunsky, E A; Windholz, L

2004-11-26

The theoretically predicted correlation of laser phase fluctuations in Lambda-type interaction schemes is experimentally demonstrated. We show that the mechanism of correlation in a Lambda scheme is restricted to high-frequency noise components, whereas in a double-Lambda scheme, due to the laser phase locking in a closed-loop interaction, it extends to all noise frequencies. In this case the correlation is weakly sensitive to coherence losses. Thus the double-Lambda scheme can be used to correlate electromagnetic fields with carrier frequency differences beyond the GHz regime.

Dynamic Measurements Near the Lambda-point in a Low-G Simulator on the Ground

NASA Technical Reports Server (NTRS)

Israelsson, U. E.; Strayer, D. M.; Chui, T. C. P.; Duncan, R. V.

1993-01-01

The properties of liquid helium very near the lambda-transition in the presence of a heat current has received recent theoretical and experimental attention. In this regime, gravity induced pressure effects place severe constraints on the types of experiments that can be performed. A new experiment is described which largely overcomes these difficulties by magnetostrictively canceling gravity influences in the helium sample with a suitable magnetic coil. Design limitations of the technique and a discussion of proposed experiments is presented.

Dynamic Measurements Near the Lambda-point in a Low-gravity Simulator on the Ground

NASA Technical Reports Server (NTRS)

Israelsson, U. E.; Strayer, D. M.; Chui, T. C. P.; Larson, M.; Duncan, R. V.

1993-01-01

The properties of liquid helium very near the lambda-transition in the presence of a heat current has received recent theoretical and experimental attention. In this regime, gravity induced pressure effects place severe constraints on the types of experiments that can be performed. A new experiment is described which largely overcomes these difficulties by magnetostrictively canceling gravity influences in the helium sample with a suitable magnetic coil. Design limitations of the technique and a discussion of proposed experiments is presented.

A reanalysis of the SWP-HI IUE observations of Capella

NASA Technical Reports Server (NTRS)

Wood, Brian E.; Ayres, T. R.

1995-01-01

We have reanalyzed the numerous high-resolution, far-ultraviolet observations of Capella made by the International Ultraviolet Explorer (IUE) in its 16 yr lifetime. Our purpose was to search for long-term profile variations in Capella's ultraviolet emission lines and to complement the analysis of Goddard High Resolution Spectrograph (GHRS) observations of Capella, discussed in a companion paper (Linsky et al. 1995). We implemented a state-of-the-art photometric correction and spectral extraction procedure to improve S/N and control potential sources for systematic errors. Nevertheless, we were unable to find compelling evidence for any significant long-term profile variations. Previous work has shown that the G8 primary star is only a minor contributor to the high-excitation transition region lines but is a significant contributor to the low-excitation chromospheric lines. We have found exceptions to this rule, however. We find that the G8 star is responsible for a significant portion of Capella's N V lambda lambda 1239, 1243 emission, but is not a large contributor to the S I lambda 1296, Cl I lambda 1352, and O lambda 1356 lines. We suggest possible explanations for these behaviors. We also find evidence that the He II lambda 1640 emission from the G1 star is from the transition region, while the He II lambda 1640 emission from the G8 star is chromospheric, consistent with the findings of Linsky et al. (1994). The C II lambda 1336 line shows a weak central reversal. It is blueshifted by about 9 km/s with respect to the centroid of the emission from the G1 star. While the central reversal of the C II line is blueshifted by about 9 km/s with respect to the centroid of the emission from the G1 star. While the central reversal of the C II line is blueshifted, the central reversal of the Si III lambda 1207 line discussed by Linsky et al. (1994) is not.

X-Ray Flare Characteristics in the B2e Star Lambda Eridani (ROSAT)

NASA Technical Reports Server (NTRS)

Smith, Myron A.

1997-01-01

We document the results of a simultaneous wavelength monitoring on the B2e star (lambda) Eri. This campaign was carried out from ground stations and with the ROSAT, ASCA, IUE, and Voyager 2 space platforms during a week in February-March 1995; a smaller follow-up was conducted in September 1995. During the first of these intervals (lambda) Eri exhibited extraordinary wind and disk-ejection activity. The ROSAT/HRI X-ray light curves showed no large flares such as the one the ROSAT/PSCA observed in 1991. However, possible low level fluctuations in the February-March ROSAT data occurred at the same time as unusual activity in H(alpha) He I (lambda)6678, He II (lambda)1640, and the C IV doublet. For example, the hydrogen and helium lines exhibited an emission in the blue half of their profiles, probably lasting several hours. The C IV lines showed a strong high-velocity Discrete Absorption Component (DAC) accompanied by unusually strong absorption at lower velocities. The helium line activity suggests that a mass ejection occurred at the base of the wind while the strong C III (Voyager) and C IV (IUE) lines implies that shock interactions occurred in the wind flow. It is not clear that the X-ray elevations are directly related to the strong C IV absorptions because the former changed on a much more rapid timescale than absorptions in the C IV lines. Within hours of the mild X-ray flux variations found by ROSAT on February 28, the Voyager UVS observed a "ringing" that decayed over three 3-hr. cycles. The amplitude of these fluctuations was strong (50%) at (lambda)(lambda)950-1100, decreased rapidly with wavelength, and faded to nondetection longward of (lambda)1300. Various considerations indicate that these continuum variations were not due to an instrumental pathology in the UVS. Rather, they appear to be due to a time-dependent flux deficit in the (lambda)(lambda)950-1250 region. We outline a scenario in which a dense plasma structure over the star's surface is heated and cooled quasi-periodically to produce such flux changes. Observations of new examples of this phenomenon are badly needed. Amateur astronomers can make a significant contribution to its understanding by searching for ringing in light curves of Be stars during their outburst phases. Finally we draw attention to an increase in the emission of the H(alpha) line that occurred at about the time the FUV ringing started. This increased emission hints that approximately 50,000K plasma near the star's surface can influence the circumstellar disc at approximately 12R. by its increased Lyman continuum flux.

On the use of transition matrix methods with extended ensembles.

PubMed

Escobedo, Fernando A; Abreu, Charlles R A

2006-03-14

Different extended ensemble schemes for non-Boltzmann sampling (NBS) of a selected reaction coordinate lambda were formulated so that they employ (i) "variable" sampling window schemes (that include the "successive umbrella sampling" method) to comprehensibly explore the lambda domain and (ii) transition matrix methods to iteratively obtain the underlying free-energy eta landscape (or "importance" weights) associated with lambda. The connection between "acceptance ratio" and transition matrix methods was first established to form the basis of the approach for estimating eta(lambda). The validity and performance of the different NBS schemes were then assessed using as lambda coordinate the configurational energy of the Lennard-Jones fluid. For the cases studied, it was found that the convergence rate in the estimation of eta is little affected by the use of data from high-order transitions, while it is noticeably improved by the use of a broader window of sampling in the variable window methods. Finally, it is shown how an "elastic" window of sampling can be used to effectively enact (nonuniform) preferential sampling over the lambda domain, and how to stitch the weights from separate one-dimensional NBS runs to produce a eta surface over a two-dimensional domain.

Peginterferon Lambda-1a Is Associated with a Low Incidence of Autoimmune Thyroid Disease in Chronic Hepatitis C.

PubMed

Fredlund, Paul; Hillson, Jan; Gray, Todd; Shemanski, Lynn; Dimitrova, Dessislava; Srinivasan, Subasree

2015-11-01

Peginterferon alfa (alfa) increases the risk of autoimmune disease. Peginterferon lambda-1a (Lambda) acts through a receptor with a more liver-specific distribution compared to the alfa receptor. In a phase-2b study, 525 treatment-naive patients with chronic hepatitis C virus (HCV) infection received ribavirin and Lambda interferon (120, 180, or 240 μg) or alfa interferon (180 μg) for 24 (genotypes 2 and 3) or 48 (genotypes 1 and 4) weeks. Retrospective analysis found that adverse events of MedDRA-coded thyroid dysfunction and abnormal levels of thyroid-stimulating hormone (TSH) were significantly more frequent with alfa versus Lambda (12% versus 2.6% and 15.2% versus 3.4%, respectively, both P<0.0001). Most Lambda recipients with abnormal TSH had levels below the lower limit of normal; the frequency of low and high TSH was similar in alfa recipients with abnormal TSH. Blinded review by an endocrinologist found that new-onset primary hypothyroidism or painless thyroiditis was less frequent with Lambda versus alfa (0.5% and 1.8% versus 5.3% and 7.5%, respectively, P<0.0001). Most TSH elevations reflected new-onset hypothyroidism requiring treatment, while most markedly suppressed TSH values reflected probable painless thyroiditis and resolved without sequelae. In conclusion, HCV-infected patients treated with Lambda/ribavirin experienced fewer adverse events of thyroid dysfunction compared with patients treated with alfa/ribavirin.

T(sub lambda) Depression by a Heat Current Along the lambda-Line

NASA Technical Reports Server (NTRS)

Liu, Yuanming; Larson, Melora; Iraelsson, Ulf E.

1999-01-01

We report measurements of the depression of the superfluid transition temperature by a heat current (1 less than or = Q less than or = 100 microW/sq cm) along the lambda-line (SVP less than or = P less than or = 21.6 bar). At P = 21.6 bar, measurements were also performed in a reduced gravity (0.2g). Experimental results show that the pressure dependence of the depression and the gravity effect on the measurements are small, in qualitative agreement with theoretical predictions. Keywords: superfluid helium; Lambda transition; heat current

Synthesis of a metal oxide with a room-temperature photoreversible phase transition.

PubMed

Ohkoshi, Shin-Ichi; Tsunobuchi, Yoshihide; Matsuda, Tomoyuki; Hashimoto, Kazuhito; Namai, Asuka; Hakoe, Fumiyoshi; Tokoro, Hiroko

2010-07-01

Photoinduced phase-transition materials, such as chalcogenides, spin-crossover complexes, photochromic organic compounds and charge-transfer materials, are of interest because of their application to optical data storage. Here we report a photoreversible metal-semiconductor phase transition at room temperature with a unique phase of Ti(3)O(5), lambda-Ti(3)O(5). lambda-Ti(3)O(5) nanocrystals are made by the combination of reverse-micelle and sol-gel techniques. Thermodynamic analysis suggests that the photoinduced phase transition originates from a particular state of lambda-Ti(3)O(5) trapped at a thermodynamic local energy minimum. Light irradiation causes reversible switching between this trapped state (lambda-Ti(3)O(5)) and the other energy-minimum state (beta-Ti(3)O(5)), both of which are persistent phases. This is the first demonstration of a photorewritable phenomenon at room temperature in a metal oxide. lambda-Ti(3)O(5) satisfies the operation conditions required for a practical optical storage system (operational temperature, writing data by short wavelength light and the appropriate threshold laser power).

Reynolds-number-dependent dynamical transitions on hydrodynamic synchronization modes of externally driven colloids

NASA Astrophysics Data System (ADS)

Oyama, Norihiro; Teshigawara, Kosuke; Molina, John Jairo; Yamamoto, Ryoichi; Taniguchi, Takashi

2018-03-01

The collective dynamics of externally driven Np-colloidal systems (1 ≤Np≤4 ) in a confined viscous fluid have been investigated using three-dimensional direct numerical simulations with fully resolved hydrodynamics. The dynamical modes of collective particle motion are studied by changing the particle Reynolds number as determined by the strength of the external driving force and the confining wall distance. For a system with Np=3 , we found that at a critical Reynolds number a dynamical mode transition occurs from the doublet-singlet mode to the triplet mode, which has not been reported experimentally. The dynamical mode transition was analyzed in detail from the following two viewpoints: (1) spectrum analysis of the time evolution of a tagged particle velocity and (2) the relative acceleration of the doublet cluster with respect to the singlet particle. For a system with Np=4 , we found similar dynamical mode transitions from the doublet-singlet-singlet mode to the triplet-singlet mode and further to the quartet mode.

Reynolds-number-dependent dynamical transitions on hydrodynamic synchronization modes of externally driven colloids.

PubMed

Oyama, Norihiro; Teshigawara, Kosuke; Molina, John Jairo; Yamamoto, Ryoichi; Taniguchi, Takashi

2018-03-01

The collective dynamics of externally driven N_{p}-colloidal systems (1≤N_{p}≤4) in a confined viscous fluid have been investigated using three-dimensional direct numerical simulations with fully resolved hydrodynamics. The dynamical modes of collective particle motion are studied by changing the particle Reynolds number as determined by the strength of the external driving force and the confining wall distance. For a system with N_{p}=3, we found that at a critical Reynolds number a dynamical mode transition occurs from the doublet-singlet mode to the triplet mode, which has not been reported experimentally. The dynamical mode transition was analyzed in detail from the following two viewpoints: (1) spectrum analysis of the time evolution of a tagged particle velocity and (2) the relative acceleration of the doublet cluster with respect to the singlet particle. For a system with N_{p}=4, we found similar dynamical mode transitions from the doublet-singlet-singlet mode to the triplet-singlet mode and further to the quartet mode.

Numerical investigations in the backflow region of a vacuum plume

NASA Technical Reports Server (NTRS)

Liaw, Goang-Shin

1992-01-01

The objective of this research is to numerically simulate the vacuum plume flow field in the backflow region of a low thrust nozzle exit. In space applications, the low thrust nozzles are used as a propulsion device to control the vehicle attitude, or to maneuver the vehicle flight trajectory. When the spacecraft is deployed in the orbit or cruising in a planetary mission, the vacuum plume is created behind the nozzle exit (so called backflow region), by the exhausting gas of the propulsion system or by venting internal gas to the extremely low density ambient. The low density vacuum plume flow regions cover the continuum, transitional and free molecular flow regimes, which were characterized by the Knudsen number K(sub n), K(sub n) = lambda(sub m)/L where lambda(sub m) is the mean free path of the gas molecules and L is the characteristic length of the flow field. The transitional regime is defined by 0.01 is less than or equal to K(sub n) is less than or equal to 10. The conventional Navier-Stokes equations are valid only in the flow region close to the nozzle exit since the validity of the Navier-Stokes equations fails asymptotically as the Knudsen number increases. The vacuum plume characteristics prediction is primarily a problem of transitional aerodynamics.

Detection of interstellar CH in the far-infrared

NASA Technical Reports Server (NTRS)

Stacey, Gordon J.; Lugten, J. B.; Genzel, R.

1987-01-01

The first astronomical detection of CH in the far-infrared has been made. A ground state of rotational transition was observed in absorption against the far-infrared continuum peak of Sgr B2. The lines are resolved at a velocity resolution of 62 km/s, have a line width of roughly 250 km/s, and a line center optical depth of about 0.29. The inferred total column density of CH in the ground state along the line of sight is roughly 1.6 x 10 to the 15th/sq cm. Comparison of the far-infrared profiles to the 3 GHz emission lines confirms that the ground-state Lambda-doublet levels are inverted and gives an accurate estimate of the excitation temperature. The excitation temperature of the 3264 MHz line varies from cloud to cloud along the line of sight, the levels being most inverted in the Sgr B2 molecular cloud. The large intensity of the 3264 MHz line in this cloud relative to other clouds along the line of sight may thus be primarily an excitation effect.

Structural evolution across the insulator-metal transition in oxygen-deficient BaTiO 3-δ studied using neutron total scattering and Rietveld analysis

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

Jeong, I.-K.; Lee, Seunghun; Jeong, Se-Young

2011-08-29

Oxygen-deficient BaTiO 3-δ exhibits an insulator-metal transition with increasing δ. We performed neutron total scattering measurements to study structural evolution across an insulator-metal transition in BaTiO 3-δ. Despite its significant impact on resistivity, slight oxygen reduction (δ=0.09) caused only a small disturbance on the local doublet splitting of Ti-O bond. This finding implies that local polarization is well preserved under marginal electric conduction. In the highly oxygen-deficient metallic state (δ=0.25), however, doublet splitting of the Ti-O bond became smeared. The smearing of the local Ti-O doublet is complemented with long-range structural analysis and demonstrates that the metallic conduction in themore » highly oxygen-reduced BaTiO 3-δ is due to the appearance of nonferroelectric cubic lattice.« less

Testing the renormalisation group theory of cooperative transitions at the lambda point of helium

NASA Technical Reports Server (NTRS)

Lipa, J. A.; Li, Q.; Chui, T. C. P.; Marek, D.

1988-01-01

The status of high resolution tests of the renormalization group theory of cooperative phase transitions performed near the lambda point of helium is described. The prospects for performing improved tests in space are discussed.

Transitions in eigenvalue and wavefunction structure in (1+2) -body random matrix ensembles with spin.

PubMed

Vyas, Manan; Kota, V K B; Chavda, N D

2010-03-01

Finite interacting Fermi systems with a mean-field and a chaos generating two-body interaction are modeled by one plus two-body embedded Gaussian orthogonal ensemble of random matrices with spin degree of freedom [called EGOE(1+2)-s]. Numerical calculations are used to demonstrate that, as lambda , the strength of the interaction (measured in the units of the average spacing of the single-particle levels defining the mean-field), increases, generically there is Poisson to GOE transition in level fluctuations, Breit-Wigner to Gaussian transition in strength functions (also called local density of states) and also a duality region where information entropy will be the same in both the mean-field and interaction defined basis. Spin dependence of the transition points lambda_{c} , lambdaF, and lambdad , respectively, is described using the propagator for the spectral variances and the formula for the propagator is derived. We further establish that the duality region corresponds to a region of thermalization. For this purpose we compared the single-particle entropy defined by the occupancies of the single-particle orbitals with thermodynamic entropy and information entropy for various lambda values and they are very close to each other at lambda=lambdad.

High accuracy heat capacity measurements through the lambda transition of helium with very high temperature resolution

NASA Technical Reports Server (NTRS)

Fairbanks, W. M.; Lipa, J. A.

1984-01-01

A measurement of the heat capacity singularity of helium at the lambda transition was performed with the aim of improving tests of the Renormalization Group (RG) predictions for the static thermodynamic behavior near the singularity. The goal was to approach as closely as possible to the lambda-point while making heat capacity measurements of high accuracy. To do this, a new temperature sensor capable of unprecedented resolution near the lambda-point, and two thermal control systems were used. A short description of the theoretical background and motivation is given. The initial apparatus and results are also described.

Multiple buoyancy driven flows in a vertical cylinder heated from below

NASA Technical Reports Server (NTRS)

Yamaguchi, Y.; Chang, C. J.; Brown, R. A.

1983-01-01

The structure of axisymmetric buoyancy-driven convection in a vertical cylinder heated from below is probed by finite element solution of the Boussinesq equations coupled with computed-implemented perturbation techniques for detecting and tracking multiple flows and for determining flow stability. Results are reported for fluids with Prandtl number of one and for cylinders with aspect ratio (Lambda) (defined as the height to radius of the cylinder) between 0.5 and 2.25. Extensive calculations of the neutral stability curve for the static solution and of the nonlinear motions along the bifurcating flow families show a continuous evolution of the primary cellular motion from a single toroidal cell to two and three cells nested radially in the cylinder, instead of the sharp transitions found for a cylinder with shear-free sidewalls. The smooth transitions in flow structure with Rayleigh number and lambda are explained by nonlinear connectivity between the first two bifurcating flow families formed either by a secondary bifurcation point for Lambda or = Lambda * approximately 0.80 or by a limit point for Lambda Lambda *. The transition between these two modes may be described by the theory of multiple limit point bifurcation.

Electron excitation cross sections for the 2s(2)2p(3)4S(O) -- 2s(2)2p(3)2D(O) (forbidden) and 4S(O) -- 2s2p(4) 4P (resonance) transitions in O II

NASA Technical Reports Server (NTRS)

Zuo, M.; Smith, Steven J.; Chutjian, A.; Williams, I. D.; Tayal, S. S.; Mclaughlin, Brendan M.

1995-01-01

Experimental and theoretical excitation cross sections are reported for the first forbidden transition 4S(O) -- 2S(2)2p(3) 2D(O) (lambda-lambda 3726, 3729) and the first allowed (resonance) transition 4S(O) -- 2s2p(4) 4P(lambda-833) in O II. Use is made of electron energy loss and merged-beams methods. The electron energy range covered is 3.33 (threshold) to 15 eV for the S -- D transition, and 14.9 (threshold) to 40 eV for the S -- P transition. Care was taken to assess and minimize the metastable fraction of the O II beam. An electron mirror was designed and tested to reflect inelastically backscattered electrons into the forward direction to account for the full range of polar scattering angles. Comparisons are made between present experiments and 11-state R-matrix calculations. Calculations are also presented for the 4S(O) -- 2s(2)2p(3)2P(O) (lambda-2470) transition.

THERMALLY DRIVEN ATMOSPHERIC ESCAPE: TRANSITION FROM HYDRODYNAMIC TO JEANS ESCAPE

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

Volkov, Alexey N.; Johnson, Robert E.; Tucker, Orenthal J.

2011-03-10

Thermally driven escape from planetary atmospheres changes in nature from an organized outflow (hydrodynamic escape) to escape on a molecule-by-molecule basis (Jeans escape) with increasing Jeans parameter, {lambda}, the ratio of the gravitational to thermal energy of the atmospheric molecules. This change is described here for the first time using the direct simulation Monte Carlo method. When heating is predominantly below the lower boundary of the simulation region, R{sub 0}, and well below the exobase of a single-component atmosphere, the nature of the escape process changes over a surprisingly narrow range of Jeans parameters, {lambda}{sub 0}, evaluated at R{sub 0}.more » For an atomic gas, the transition occurs over {lambda}{sub 0} {approx} 2-3, where the lower bound, {lambda}{sub 0} {approx} 2.1, corresponds to the upper limit for isentropic, supersonic outflow. For {lambda}{sub 0} > 3 escape occurs on a molecule-by-molecule basis and we show that, contrary to earlier suggestions, for {lambda}{sub 0} > {approx}6 the escape rate does not deviate significantly from the familiar Jeans rate. In a gas composed of diatomic molecules, the transition shifts to {lambda}{sub 0} {approx} 2.4-3.6 and at {lambda}{sub 0} > {approx}4 the escape rate increases a few tens of percent over that for the monatomic gas. Scaling by the Jeans parameter and the Knudsen number, these results can be applied to thermally induced escape of the major species from solar and extrasolar planets.« less

Heat capacity and thermal relaxation of bulk helium very near the lambda point

NASA Technical Reports Server (NTRS)

Lipa, John A.; Swanson, D. R.; Nissen, J. A.; Chui, T. C. P.

1994-01-01

In October 1992 a low temperature experiment was flown on the Space Shuttle in low Earth orbit. The objective of the mission was to measure the heat capacity and thermal conductivity of helium very close to the lambda point with the smearing effect of gravity removed. We report preliminary results from the experiment, and compare them with related measurements performed on the ground. The sample was s sphere of helium 3.5 cm in diameter contained within a copper calorimeter of vey high thermal conductivity. The calorimeter was attached to a pair of high resolution paramagnetic salt thermometers with noise levels in the 10(exp -10) K range and suspended from a high stability thermal isolation system. During the mission we found that the resolution of the thermometers was degraded somewhat due to the impact of charged particles. This effect limited the useful resolution of the measurements to about two nanokelvins from the lambda point. The results reported here are limited to about ten nanokelvins from the transition.

The Structural Phase Transition in Deuterated Benzil, C 14D 10O 2

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

Goosens, D. J.; Welberry, T. R.; Hagen, Mark E

2006-01-01

Neutron inelastic scattering has been used to examine the structural phase transition in deuterated benzil C{sub 14}D{sub 10}O{sub 2}. The transition in benzil, in which the unit cell goes from a trigonal P3{sub 1}21 unit cell above T{sub c} to a cell doubled P2{sub 1} unit cell below T{sub c}, leads to the emergence of a Bragg peak at the M-point of the high temperature Brillouin zone. It has previously been suggested that the softening of a transverse optic phonon at the {lambda}-point leads to the triggering of an instability at the M-point causing the transition to occur. This suggestionmore » has been investigated by measuring the phonon spectrum at the M-point for a range of temperatures above T{sub c} and the phonon dispersion relation along the {lambda}-M direction just above T{sub c}. It is found that the transverse acoustic phonon at the M-point is of lower energy than the {lambda}-point optic mode and has a softening with temperature as T approaches T{sub c} from above that is much faster than that of the {lambda}-point optic mode. This behavior is inconsistent with the view that the {lambda}-point mode is responsible for triggering the phase transition. Rather the structural phase transition in benzil appears to be driven by a conventional soft TA mode at the M-point.« less

Interplay of rare-earth and transition-metal subsystems in C u3Yb (SeO3) 2O2Cl

NASA Astrophysics Data System (ADS)

Markina, M. M.; Zakharov, K. V.; Ovchenkov, E. A.; Berdonosov, P. S.; Dolgikh, V. A.; Kuznetsova, E. S.; Olenev, A. V.; Klimin, S. A.; Kashchenko, M. A.; Budkin, I. V.; Yatsyk, I. V.; Demidov, A. A.; Zvereva, E. A.; Vasiliev, A. N.

2017-10-01

We present the synthesis and the experimental and theoretical study of the new member of the francisite family, C u3Yb (SeO3) 2O2Cl . The compound reaches an antiferromagnetic order at TN=36.7 K and experiences first-order spin-reorientation transition to weakly ferromagnetic phase at TR=8.7 K evidenced in specific heat Cp and magnetic susceptibility χ measurements. Distinctly different magnetization loops in T

A new insight into the phase transition in the early Universe with two Higgs doublets

NASA Astrophysics Data System (ADS)

Bernon, Jérémy; Bian, Ligong; Jiang, Yun

2018-05-01

We study the electroweak phase transition in the alignment limit of the CP-conserving two-Higgs-doublet model (2HDM) of Type I and Type II. The effective potential is evaluated at one-loop, where the thermal potential includes Daisy corrections and is reliably approximated by means of a sum of Bessel functions. Both 1-stage and 2-stage electroweak phase transitions are shown to be possible, depending on the pattern of the vacuum development as the Universe cools down. For the 1-stage case focused on in this paper, we analyze the properties of phase transition and discover that the field value of the electroweak symmetry breaking vacuum at the critical temperature at which the first order phase transition occurs is largely correlated with the vacuum depth of the 1-loop potential at zero temperature. We demonstrate that a strong first order electroweak phase transition (SFOEWPT) in the 2HDM is achievable and establish benchmark scenarios leading to different testable signatures at colliders. In addition, we verify that an enhanced triple Higgs coupling (including loop corrections) is a typical feature of the SFOPT driven by the additional doublet. As a result, SFOEWPT might be able to be probed at the LHC and future lepton colliders through Higgs pair production.

Efficient quantum microwave-to-optical conversion using electro-optic nanophotonic coupled resonators

NASA Astrophysics Data System (ADS)

Soltani, Mohammad; Zhang, Mian; Ryan, Colm; Ribeill, Guilhem J.; Wang, Cheng; Loncar, Marko

2017-10-01

We propose a low-noise, triply resonant, electro-optic (EO) scheme for quantum microwave-to-optical conversion based on coupled nanophotonics resonators integrated with a superconducting qubit. Our optical system features a split resonance—a doublet—with a tunable frequency splitting that matches the microwave resonance frequency of the superconducting qubit. This is in contrast to conventional approaches, where large optical resonators with free-spectral range comparable to the qubit microwave frequency are used. In our system, EO mixing between the optical pump coupled into the low-frequency doublet mode and a resonance microwave photon results in an up-converted optical photon on resonance with high-frequency doublet mode. Importantly, the down-conversion process, which is the source of noise, is suppressed in our scheme as the coupled-resonator system does not support modes at that frequency. Our device has at least an order of magnitude smaller footprint than conventional devices, resulting in large overlap between optical and microwave fields and a large photon conversion rate (g /2 π ) in the range of ˜5 -15 kHz. Owing to a large g factor and doubly resonant nature of our device, microwave-to-optical frequency conversion can be achieved with optical pump powers in the range of tens of microwatts, even with moderate values for optical Q (˜106 ) and microwave Q (˜104 ). The performance metrics of our device, with substantial improvement over the previous EO-based approaches, promise a scalable quantum microwave-to-optical conversion and networking of superconducting processors via optical fiber communication.

RE-EXAMINING HIGH ABUNDANCE SLOAN DIGITAL SKY SURVEY MASS-METALLICITY OUTLIERS: HIGH N/O, EVOLVED WOLF-RAYET GALAXIES?

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

Berg, Danielle A.; Skillman, Evan D.; Marble, Andrew R., E-mail: berg@astro.umn.edu, E-mail: skillman@astro.umn.edu, E-mail: amarble@nso.edu

We present new MMT spectroscopic observations of four dwarf galaxies representative of a larger sample observed by the Sloan Digital Sky Survey and identified by Peeples et al. as low-mass, high oxygen abundance outliers from the mass-metallicity relation. Peeples showed that these four objects (with metallicity estimates of 8.5 {<=} 12 + log(O/H) {<=} 8.8) have oxygen abundance offsets of 0.4-0.6 dex from the M{sub B} luminosity-metallicity relation. Our new observations extend the wavelength coverage to include the [O II] {lambda}{lambda}3726, 3729 doublet, which adds leverage in oxygen abundance estimates and allows measurements of N/O ratios. All four spectra aremore » low excitation, with relatively high N/O ratios (N/O {approx}> 0.10), each of which tend to bias estimates based on strong emission lines toward high oxygen abundances. These spectra all fall in a regime where the 'standard' strong-line methods for metallicity determinations are not well calibrated either empirically or by photoionization modeling. By comparing our spectra directly to photoionization models, we estimate oxygen abundances in the range of 7.9 {<=} 12 + log (O/H) {<=} 8.4, consistent with the scatter of the mass-metallicity relation. We discuss the physical nature of these galaxies that leads to their unusual spectra (and previous classification as outliers), finding their low excitation, elevated N/O, and strong Balmer absorption are consistent with the properties expected from galaxies evolving past the 'Wolf-Rayet galaxy' phase. We compare our results to the 'main' sample of Peeples and conclude that they are outliers primarily due to enrichment of nitrogen relative to oxygen and not due to unusually high oxygen abundances for their masses or luminosities.« less

Spin-Rotation Hyperfine Splittings at Moderate to High J Values in Methanol

NASA Astrophysics Data System (ADS)

Xu, Li-Hong; Hougen, Jon T.; Belov, Sergey; Golubiatnikov, G. Yu; Lapinov, Alexander; Ilyushin, V.; Alekseev, E. A.; Mescheryakov, A. A.

2015-06-01

In this talk we present a possible explanation, based on torsionally mediated proton-spin-overall-rotation interaction operators, for the surprising observation in Nizhny Novgorod several years ago of doublets in some Lamb-dip sub-millimeter-wave transitions between torsion-rotation states of E symmetry in methanol. These observed doublet splittings, some as large as 70 kHz, were later confirmed by independent Lamb-dip measurements in Kharkov. In this talk we first show the observed J-dependence of the doublet splittings for two b-type Q branches (one from each laboratory), and then focus on our theoretical explanation. The latter involves three topics: (i) group theoretically allowed terms in the spin-rotation Hamiltonian, (ii) matrix elements of these terms between the degenerate components of torsion-rotation E states, calculated using wavefunctions from an earlier global fit of torsion-rotation transitions of methanol in the vt = 0, 1, and 2 states, and (iii) least-squares fits of coefficients of these terms to about 35 experimentally resolved doublet splittings in the quantum number ranges of K = -2 to +2, J = 13 to 34, and vt = 0. Rather pleasing residuals are obtained for these doublet splittings, and a number of narrow transitions, in which no doublet splitting could be detected, are also in agreement with predictions from the theory. Some remaining disagreements between experiment and the present theoretical explanation will be mentioned. G. Yu. Golubiatnikov, S. P. Belov, A. V. Lapinov, "CH_3OH Sub-Doppler Spectroscopy," (Paper MF04) and S.P. Belov, A.V. Burenin, G.Yu. Golubiatnikov, A.V. Lapinov, "What is the Nature of the Doublets in the E-Methanol Lamb-dip Spectra?" (Paper FB07), 68th International Symposium on Molecular Spectroscopy, Columbus, Ohio, June 2013. Li-Hong Xu, J. Fisher, R.M. Lees, H.Y. Shi, J.T. Hougen, J.C. Pearson, B.J. Drouin, G.A. Blake, R. Braakman, "Torsion-Rotation Global Analysis of the First Three Torsional States (vt = 0, 1, 2) and Terahertz Database for Methanol," J. Mol. Spectrosc., 251, 305-313, (2008).

Mechanisms of Hyperbilirubinemia During Peginterferon Lambda-1a Therapy for Chronic Hepatitis C Infection: A Retrospective Investigation.

PubMed

Zwirtes, Ricardo; Narasimhan, Premkumar; Wind-Rotolo, Megan M; Xu, Dong; Hruska, Matthew W; Kishnani, Narendra; Colston, Elizabeth M; Srinivasan, Subasree

2016-11-01

The phase 2b EMERGE study compared the efficacy/safety of peginterferon lambda-1a (Lambda) and peginterferon alfa-2a (Alfa), both with ribavirin (RBV), for treatment of chronic hepatitis C virus (HCV) infection. A key safety finding was a higher frequency of hyperbilirubinemia with Lambda/RBV versus Alfa/RBV. To characterize mechanisms of hyperbilirubinemia associated with Lambda/RBV, we conducted a retrospective analysis of safety data from the HCV genotype 1 and genotype 4 cohort of the EMERGE study. Subjects were randomized to once-weekly Lambda (120/180/240 μg) or Alfa (180 μg), with daily RBV, for 48 weeks. Early-onset Lambda/RBV-related hyperbilirubinemia events (6-12 weeks) resulted mostly from RBV-induced hemolysis evidenced by sustained reticulocytosis and a predominantly unconjugated pattern of hyperbilirubinemia. The higher hyperbilirubinemia frequency with Lambda/RBV versus Alfa/RBV was attributed to bone marrow suppression known to occur with Alfa but not Lambda. Late-onset (>12 weeks) Lambda/RBV-related hyperbilirubinemia events occurred most frequently with higher Lambda doses and were associated with increased levels of hepatic transaminase and direct bilirubin fractions compared with early events. This dual pattern of hyperbilirubinemia observed while on Lambda/RBV treatment is thought to be caused by exaggerated RBV-induced hemolysis in early-onset events compared with possible direct Lambda-induced hepatocellular toxicity in late-onset events.

Emission of a pulsed purely rotational transition chemical H{sub 2}-F{sub 2} laser

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

Molevich, N E; Pichugin, S Yu

2008-04-30

The possibility of obtaining efficient emission at purely rotational transitions of HF molecules in a pulsed chemical hydrogen fluoride laser is studied theoretically. The operation of a H{sub 2}-F{sub 2} laser with a gas pressure of 1.1 atm emitting at the v, j {yields} v, j - 1 (v = 1 - 6, j = 10 - 14) transitions is simulated taking into account resonance VR processes. The total specific laser energy release calculated over all the vibrational levels is 5.5 J L{sup -1} on purely rotational transitions at {lambda}{approx}17 {mu}m (j = 14), 3.5 J L{sup -1} at {lambda}{approx}18.5more » {mu}m (j = 13), and 2.5 J L{sup -1} at {lambda}{approx}20 {mu}m (j = 12). (lasers and amplifiers)« less

GTC OSIRIS transiting exoplanet atmospheric survey: detection of sodium in XO-2b from differential long-slit spectroscopy

NASA Astrophysics Data System (ADS)

Sing, D. K.; Huitson, C. M.; Lopez-Morales, M.; Pont, F.; Désert, J.-M.; Ehrenreich, D.; Wilson, P. A.; Ballester, G. E.; Fortney, J. J.; Lecavelier des Etangs, A.; Vidal-Madjar, A.

2012-10-01

We present two transits of the hot-Jupiter exoplanet XO-2b using the Gran Telescopio Canarias (GTC). The time series observations were performed using long-slit spectroscopy of XO-2 and a nearby reference star with the Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) instrument, enabling differential spectrophotometric transit light curves capable of measuring the exoplanet's transmission spectrum. Two optical low-resolution grisms were used to cover the optical wavelength range from 3800 to 9300 Å. We find that sub-mmag-level slit losses between the target and reference star prevent full optical transmission spectra from being constructed, limiting our analysis to differential absorption depths over ˜1000 Å regions. Wider long slits or multi-object grism spectroscopy with wide masks will likely prove effective in minimizing the observed slit-loss trends. During both transits, we detect significant absorption in the planetary atmosphere of XO-2b using a 50-Å bandpass centred on the Na I doublet, with absorption depths of Δ(Rpl/R★)2 = 0.049 ± 0.017 per cent using the R500R grism and 0.047 ± 0.011 per cent using the R500B grism (combined 5.2σ significance from both transits). The sodium feature is unresolved in our low-resolution spectra, with detailed modelling also likely ruling out significant line-wing absorption over an ˜800 Å region surrounding the doublet. Combined with narrow-band photometric measurements, XO-2b is the first hot Jupiter with evidence for both sodium and potassium present in the planet's atmosphere. Based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma, and part of the large European Southern Observatory (ESO) programme 182.C-2018.

A MASSIVE RUNAWAY STAR FROM 30 DORADUS

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

Evans, C. J.; Walborn, N. R.; Massa, D.

2010-06-01

We present the first ultraviolet (UV) and multi-epoch optical spectroscopy of 30 Dor 016, a massive O2-type star on the periphery of 30 Doradus in the Large Magellanic Cloud. The UV data were obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope as part of the Servicing Mission Observatory Verification program after Servicing Mission 4, and reveal no. 016 to have one of the fastest stellar winds known. From analysis of the C IV {lambda}{lambda}1548-51 doublet we find a terminal velocity, v {sub {infinity}} = 3450 {+-} 50 km s{sup -1}. Optical spectroscopy is from the VLT-FLAMES Tarantulamore » Survey, from which we rule out a massive companion (with 2 days < P < 1 yr) to a confidence of 98%. The radial velocity of no. 016 is offset from the systemic value by -85 km s{sup -1}, suggesting that the star has traveled the 120 pc from the core of 30 Doradus as a runaway, ejected via dynamical interactions.« less

Quantum calculations for one-dimensional cooling of helium

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

Vredenbregt, E.; Doery, M.; Bergeman, T.

1993-05-01

We report theoretical velocity distributions for sub-Doppler laser cooling of metastable He*(2{sup 3}S), calculated with the Density Matrix and Monte Carlo Wavefunction approaches. For low-field (B = 50 mG) magnetic-field induced laser cooling on the 2{sup 3}S {yields} (2{sup 3}P, J = 2) transition ({lambda} = 1083 nm), we get a narrow, sub-Doppler structure, consisting of three, {approximately}1 photon recoil wide peaks, spaced {approximately}1 recoil apart. With increasing field, this three-peak structure develops into two velocity-selective resonance (VSR) peaks, each {approximately}2 recoils wide. For the 2{sup 3}S {yields} (3{sup 3}P, J = 2) transition ({lambda} 389 nm), VSR peaks aremore » predicted to appear at low field without the third, central peak, which only develops at higher field (B = 200 mG). Additional computations deal with polarization-gradient cooling. In general, we find that for one-dimensional cooling calculations, the Density Matrix method is more efficient than the Monte Carlo Wavefunction approach. Experiments are currently under way to test the results.« less

High resolution spectroscopy over 8500-8750 Å for GAIA <= 7500 K. II. A library of synthetic spectra for T_eff <= 7500 K

NASA Astrophysics Data System (ADS)

Munari, U.; Castelli, F.

2000-01-01

We present a library of synthetic spectra characterized by -2.5 <= [Z/Z_sun] <= +0.5, 4.5 <= log g<= 1.0, and Teff <= 7500 K computed at the same lambda /bigtriangleup lambda = 20000 resolving power of the observed spectra given in Paper I for 131 standard stars mapping the MKK spectral classification system. This range of parameters includes the majority of the galactic stars expected to dominate the GAIA target population, i.e. F-G-K-M type stars with metallicity ranging from that of the galactic globular clusters to Population I objects. Extension to Teff > 7500 K will be given later on in this series. The 254 synthetic spectra presented here are based on Kurucz's codes and line data and have been computed over a more extended wavelength interval (7650-8750 Ä) than that currently baselined for implementation on GAIA, i.e. the 8500-8750 Ä. This last range is dominated by the near-IR Ca II triplet and the head of the Paschen series. The more extended wavelength range allows us to investigate the behaviour of other strong near-IR spectral features (severely contaminated by telluric absorptions in ground-based observed spectra) as the K I doublet (7664, 7699 Ä), the Na I doublet (8183, 8194 Ä) and the lines of Fe I multiplet N.60 at 8327 and 8388 Ä. The synthetic spectra support our previous conclusions about the superior performance of the Paschen/Ca II 8500-8750 Ä region in meeting the GAIA requirements when compared to other near-IR intervals of similar bigtriangleup lambda = 250 Ä. Table 2 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html Figures 5-93 are only available in electronic form at the http://www.edpsciences.org The spectra are also available in electronic form at the CDS or via the personal HomePage http://ulisse.pd.astro.it/Astro/Atlases/

On the Ising character of the quantum-phase transition in LiHoF4

NASA Astrophysics Data System (ADS)

Skomski, R.

2016-05-01

It is investigated how a transverse magnetic field affects the quantum-mechanical character of LiHoF4, a system generally considered as a textbook example for an Ising-like quantum-phase transition. In small magnetic fields, the low-temperature behavior of the ions is Ising-like, involving the nearly degenerate low-lying Jz = ± 8 doublet. However, as the transverse field increases, there is a substantial admixture of states having |Jz| < 8. Near the quantum-phase-transition field, the system is distinctively non-Ising like, and all Jz eigenstates yield ground-state contributions of comparable magnitude. A classical analog to this mechanism is the micromagnetic single point in magnets with uniaxial anisotropy. Since Ho3+ has J = 8, the ion's behavior is reminiscent of the classical limit (J = ∞), but quantum corrections remain clearly visible.

Precision sizing of moving large particles using diffraction splitting of Doppler lines

NASA Astrophysics Data System (ADS)

Kononenko, Vadim L.

1999-02-01

It is shown, that the Doppler line from a single large particle moving with a constant velocity through a finite- width laser beam, undergoes a doublet-type splitting under specific observation conditions. A general requirement is that particle size 2a is not negligibly small, compared with beam diameter 2w$0. Three optical mechanisms of line splitting are considered. The first one is based on nonsymmetric diffraction of a bounded laser beam by a moving particle. The second arises from the transient geometry of diffraction. The third mechanism, of photometric nature, originates from specific time variation of total illuminance of moving particles when 2a>Lambda, the interference fringe spacing in the measuring volume. The diffraction splitting is observed when a detector is placed near one of diffraction minima corresponding to either of probing beams, and 2a equals (n0.5)Lambda for n equals 1,2. The photometric splitting is observed with an image-forming optics, when 2a equals n(Lambda) . That gives the possibility of distant particles sizing based on the Doppler line splitting phenomenon. A general theory of line splitting is developed, and used to explain the experimental observations quantitatively. The influence of the scattering angels and observation angle on the line splitting characteristics is studied analytically and numerically.

Fluctuations and All-In-All-Out Ordering in Dipole-Octupole Nd2Zr2O7

NASA Astrophysics Data System (ADS)

Lhotel, E.; Petit, S.; Guitteny, S.; Florea, O.; Ciomaga Hatnean, M.; Colin, C.; Ressouche, E.; Lees, M. R.; Balakrishnan, G.

2015-11-01

By means of neutron scattering and magnetization measurements down to 90 mK, we determine the magnetic ground state of the spin-ice candidate Nd2Zr2O7. We show that, despite ferromagnetic interactions, Nd2Zr2O7 undergoes a transition around 285 mK towards an all-in-all-out antiferromagnetic state, with a strongly reduced ordered magnetic moment. We establish the (H ,T ) phase diagram in the three directions of the applied field and reveal a metamagnetic transition around 0.1 T, associated with an unexpected shape of the magnetization curves. We propose that this behavior results from the peculiar nature of the Nd3 + doublet, a dipolar-octupolar doublet, different from the standard Kramers doublet studied to date, thus revealing the importance of multipolar correlations in the properties of pyrochlore oxides.

Spectral dynamics of square pulses in passively mode-locked fiber lasers

NASA Astrophysics Data System (ADS)

Semaan, Georges; Komarov, Andrey; Niang, Alioune; Salhi, Mohamed; Sanchez, François

2018-02-01

We investigate experimentally and numerically the spectral dynamics of square pulses generated in passively mode-locked fiber lasers under the dissipative soliton resonance. The features of the transition from the single-peak spectral profile to the doublet spectrum with increasing pump power are studied. The used master equation takes into account the gain saturation, the quadratic frequency dispersion of the gain and the refractive index, and the cubic-quintic nonlinearity of the losses and refractive index. Experimental data are obtained for an Er:Yb-doped fiber ring laser. The theoretical and experimental results are in good agreement with each other.

Coupling Between CPW and Slotline Modes in Finite Ground CPW with Unequal Ground Plane Widths

NASA Technical Reports Server (NTRS)

Ponchak, George E.; Papapolymerou, John; Williams, W. D. (Technical Monitor); Tentzeris, Emmanouil M.

2002-01-01

The coupling between the desired CPW mode and the unwanted, slotline, mode is presented for finite ground coplanar waveguides with unequal ground plane widths. Measurements, quasi-static conformal mapping, and Method of Moment analysis are performed to determine the dependence of the slotline mode excitation on the physical dimensions of the FGC line and on the frequency range of operation. Introduction: Finite ground coplanar waveguide (FGC) is often used in low cost Monolithic Microwave Integrated Circuits (MMICs) because of its many advantages over microstrip and conventional CoPlanar Waveguide (CPW). It is uniplanar, which facilitates easy connection of series and shunt elements without via holes, supports a low loss, quasi-TEM mode over a wide frequency band, and since the ground planes are electrically and physically narrow, typically less than lambda/5 wide where lambda is the guided wavelength, they reduce the circuit size and the influence of higher order modes. However, they still support the parasitic slotline mode that plagues all CPW transmission lines.

Reverberant acoustic energy in auditoria that comprise systems of coupled rooms

NASA Astrophysics Data System (ADS)

Summers, Jason Erik

A frequency-dependent model for levels and decay rates of reverberant energy in systems of coupled rooms is developed and compared with measurements conducted in a 1:10 scale model and in Bass Hall, Fort Worth, TX. Schroeder frequencies of subrooms, fSch, characteristic size of coupling apertures, a, relative to wavelength lambda, and characteristic size of room surfaces, l, relative to lambda define the frequency regions. At high frequencies [HF (f >> f Sch, a >> lambda, l >> lambda)], this work improves upon prior statistical-acoustics (SA) coupled-ODE models by incorporating geometrical-acoustics (GA) corrections for the model of decay within subrooms and the model of energy transfer between subrooms. Previous researchers developed prediction algorithms based on computational GA. Comparisons of predictions derived from beam-axis tracing with scale-model measurements indicate that systematic errors for coupled rooms result from earlier tail-correction procedures that assume constant quadratic growth of reflection density. A new algorithm is developed that uses ray tracing rather than tail correction in the late part and is shown to correct this error. At midfrequencies [MF (f >> f Sch, a ˜ lambda)], HF models are modified to account for wave effects at coupling apertures by including analytically or heuristically derived power transmission coefficients tau. This work improves upon prior SA models of this type by developing more accurate estimates of random-incidence tau. While the accuracy of the MF models is difficult to verify, scale-model measurements evidence the expected behavior. The Biot-Tolstoy-Medwin-Svensson (BTMS) time-domain edge-diffraction model is newly adapted to study transmission through apertures. Multiple-order BTMS scattering is theoretically and experimentally shown to be inaccurate due to the neglect of slope diffraction. At low frequencies (f ˜ f Sch), scale-model measurements have been qualitatively explained by application of previously developed perturbation models. Measurements newly confirm that coupling strength between three-dimensional rooms is related to unperturbed pressure distribution on the coupling surface. In Bass Hall, measurements are conducted to determine the acoustical effects of the coupled stage house on stage and in the audience area. The high-frequency predictions of statistical- and geometrical-acoustics models agree well with measured results. Predictions of the transmission coefficients of the coupling apertures agree, at least qualitatively, with the observed behavior.

Constraining neutron-star tidal Love numbers with gravitational-wave detectors

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

Flanagan, Eanna E.; Hinderer, Tanja

Ground-based gravitational wave detectors may be able to constrain the nuclear equation of state using the early, low frequency portion of the signal of detected neutron star-neutron star inspirals. In this early adiabatic regime, the influence of a neutron star's internal structure on the phase of the waveform depends only on a single parameter {lambda} of the star related to its tidal Love number, namely, the ratio of the induced quadrupole moment to the perturbing tidal gravitational field. We analyze the information obtainable from gravitational wave frequencies smaller than a cutoff frequency of 400 Hz, where corrections to the internal-structuremore » signal are less than 10%. For an inspiral of two nonspinning 1.4M{sub {center_dot}} neutron stars at a distance of 50 Megaparsecs, LIGO II detectors will be able to constrain {lambda} to {lambda}{<=}2.0x10{sup 37} g cm{sup 2} s{sup 2} with 90% confidence. Fully relativistic stellar models show that the corresponding constraint on radius R for 1.4M{sub {center_dot}} neutron stars would be R{<=}13.6 km (15.3 km) for a n=0.5 (n=1.0) polytrope with equation of state p{proportional_to}{rho}{sup 1+1/n}.« less

Vacuum-induced Autler-Townes splitting in a superconducting artificial atom

NASA Astrophysics Data System (ADS)

Peng, Z. H.; Ding, J. H.; Zhou, Y.; Ying, L. L.; Wang, Z.; Zhou, L.; Kuang, L. M.; Liu, Yu-xi; Astafiev, O. V.; Tsai, J. S.

2018-06-01

We experimentally study a vacuum-induced Autler-Townes doublet in a superconducting three-level artificial atom strongly coupled to a coplanar waveguide resonator and simultaneously to a transmission line. The Autler-Townes splitting is observed in the reflection spectrum from the three-level atom in a transition between the ground state and the second excited state when the transition between the two excited states is resonant with a resonator. By applying a driving field to the resonator, we observe a change in the regime of the Autler-Townes splitting from quantum (vacuum-induced) to classical (with many resonator photons). Furthermore, we show that the reflection of propagating microwaves in a transmission line could be controlled by different frequency microwave fields at the single-photon level in a resonator.

Rovibrational bound states of SO2 isotopologues. II: Total angular momentum J = 11-20

NASA Astrophysics Data System (ADS)

Kumar, Praveen; Poirier, Bill

2015-11-01

In a two-part series, the rovibrational bound states of SO2 are investigated in comprehensive detail, for all four stable sulfur isotopes 32-34,36S. All low-lying rovibrational energy levels-both permutation-symmetry-allowed and not allowed-are computed, for all values of total angular momentum in the range J = 0-20. The calculations have carried out using the ScalIT suite of parallel codes. The present study (Paper II) examines the J = 11-20 rovibrational levels, providing symmetry and rovibrational labels for every computed state, relying on a new lambda-doublet splitting technique to make completely unambiguous assignments. Isotope shifts are analyzed, as is the validity of ;J-shifting; as a predictor of rotational fine structure. Among other ramifications, this work will facilitate understanding of mass-independent fractionation of sulfur isotopes (S-MIF) observed in the Archean rock record-particularly as this may have arisen from self shielding. S-MIF, in turn is highly relevant in the broader context of understanding the ;oxygen revolution;.

Low Ionization Absorbing Gas Kinematics Around Z ~ 1 Galaxies

NASA Astrophysics Data System (ADS)

Churchill, C. W.; Steidel, C. C.; Vogt, S. S.

1996-12-01

Absorption profiles of the Mg II lambda lambda 2796,2803 doublet arising from gas associated with 48 ``normal'' intermediate redshift (0.4 < z < 1.7) galaxies have been resolved in QSO spectra at 6 km s(-1) resolution using HIRES on Keck I. We have found evidence for pronounced redshift evolution in the subcomponent velocity two--point correlation function, suggestive that the gas surrounding galaxies has settled over a 5--10 Gyr look--back time. Based upon a sub--sample of 15 galaxies at z<1, we found no evidence for correlations between the absorbing gas kinematics and the projected galactocentric distance of the gas, galaxy luminosities, or galaxy rest--frame colors (though trends between galaxy properties and absorption properties are apparent from a larger low resolution absorption line sample). The implication is that low ionization gas surrounding early epoch galaxies was not smoothly distributed either spatially or kinematically out to a galactocentric distance ~ 40 kpc. Directly from the profiles, we have measured the number of separate absorbing ``kinematic subsystems'' associated with each galaxy, and each subsystem's profile velocity width, asymmetry (skew), and integrated column density. The distribution in these subsystem properties with velocity is highly peaked at zero, and does not exhibit a bimodality. The lack of a bimodality is suggestive that the gas kinematics is not dominated by quasi--symmetric infall into galactic potential wells. In view of absorption line studies of local galaxies, it appears that extended regions of low ionization gas surrounding galaxies represent a dynamical and active epoch of ``normal'' galaxy evolution. The reservoirs of gas for these extended ``halos'' were probably residual infalling fragments (from earlier formation processes and on--going dynamical events) whose evolution first included a settling in velocity dispersion and then more recently a decline in number. The build up of thick and/or extended gaseous disks (in the case of spirals) may be one manifestation of this process.

Exciton Absorption in Semiconductor Quantum Wells Driven by a Strong Intersubband Pump Field

NASA Technical Reports Server (NTRS)

Liu, Ansheng; Ning, Cun-Zheng

1999-01-01

Optical interband excitonic absorption of semiconductor quantum wells (QW's) driven by a coherent pump field is investigated based on semiconductor Bloch equations. The pump field has a photon energy close to the intersubband spacing between the first two conduction subbands in the QW's. An external weak optical field probes the interband transition. The excitonic effects and pump-induced population redistribution within the conduction subbands in the QW system are included. When the density of the electron-hole pairs in the QW structure is low, the pump field induces an Autler-Townes splitting of the exciton absorption spectrum. The split size and the peak positions of the absorption doublet depend not only on the pump frequency and intensity but also on the carrier density. As the density of the electron-hole pairs is increased, the split contrast (the ratio between the maximum and minimum values) is decreased because the exciton effect is suppressed at higher densities due to the many-body screening.

Fully quantum-state resolved study of NO{sub 2} photodissociation. Correlated NO({sup 2}{Pi}{sub {Omega}}, {nu} = 0 J,A) + O({sup 3}P{sub j}) distributions

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

Sanov, A.; Bieler, C.R.; Reisler, H.

1995-09-14

Relative O({sup 3}P{sub j} = 2.1.0) spin-orbit populations correlated with specific NO[{sup 2}{Pi}{sub {Omega}} = {1/2}, 3/2; {nu} = 0; f; {Lambda} = {Pi}(A{prime}), {Pi}(A{double_prime})] product states were obtained following photolysis of NO{sub 2} at excess energies E{sup {+-}} = 390, 425, and 1054 cm{sup -1}. These fully quantum state-resolved measurements were carried out by recording spatial profiles of recoiling NO({sup 2}{Pi}{sub {Omega}}, J, {Lambda}) products using polarized radiation for photolysis and state-selective laser ionization detection. The relative O({sup 3}P{sub j}) populations correlated with each NO({sup 2}{Pi}{sub {Omega}}, J, {Lambda}) state show marked fluctuations at each excess energy as amore » function of rotational state and {Lambda}-doublet component. The relative populations also fluctuate as a function of excess energy. The O({sup 3}P{sub j}) spin-orbit population ratios, when averaged over all measurements, exhibit distributions that are colder than statistical, in agreement with previous results. In particular, we find that, on average, O({sup 3}P{sub 1}):O({sup 3}P{sub 2}) population ratios correlated with the ground NO({sup 2}{Pi}{sub {1/2}}) state are colder than the corresponding ratios correlated with the excited NO({sup 2}{Pi}{sub 3/2}) spin-orbit state. These results are in agreement with the state-specific calculations of Katigiri and Kato. 45 refs., 12 figs., 3 tabs.« less

Strength functions, entropies, and duality in weakly to strongly interacting fermionic systems.

PubMed

Angom, D; Ghosh, S; Kota, V K B

2004-01-01

We revisit statistical wave function properties of finite systems of interacting fermions in the light of strength functions and their participation ratio and information entropy. For weakly interacting fermions in a mean-field with random two-body interactions of increasing strength lambda, the strength functions F(k) (E) are well known to change, in the regime where level fluctuations follow Wigner's surmise, from Breit-Wigner to Gaussian form. We propose an ansatz for the function describing this transition which we use to investigate the participation ratio xi(2) and the information entropy S(info) during this crossover, thereby extending the known behavior valid in the Gaussian domain into much of the Breit-Wigner domain. Our method also allows us to derive the scaling law lambda(d) approximately 1/sqrt[m] ( m is number of fermions) for the duality point lambda= lambda(d), where F(k) (E), xi(2), and S(info) in both the weak ( lambda=0 ) and strong mixing ( lambda= infinity ) basis coincide. As an application, the ansatz function for strength functions is used in describing the Breit-Wigner to Gaussian transition seen in neutral atoms CeI to SmI with valence electrons changing from 4 to 8.

Observation of nuclear spin species conversion inside the 1593 cm -1 structure of H 2O trapped in argon matrices: Nitrogen impurities and the H 2O:N 2 complex

NASA Astrophysics Data System (ADS)

Pardanaud, Cédric; Vasserot, Anne-Marie; Michaut, Xavier; Abouaf-Marguin, L.

2008-02-01

We have investigated, at high resolution (0.03 cm -1), the 1593 cm -1 structure observed in the IR absorption spectrum of water trapped in solid argon doped with nitrogen. It exhibits a doublet at 1592.59 ± 0.05 and 1593.08 ± 0.05 cm -1 and a line centered at 1592.93 ± 0.05 cm -1. The central component, which increases irreversibly upon annealing and when the concentration is increased, is due to the proton acceptor submolecule of the H 2O dimer, as mentioned in the literature. The doublet is assigned to the H 2O:N 2 complex. After a fast cooling of the sample from 20 to 4 K, the low frequency line of the doublet decreases with time and the high frequency one increases, the total integrated absorption increasing slightly. The ratio of the integrated intensities between the low frequency component and the high frequency one reaches a constant limit of 0.5 ± 0.1 at infinite time. This time behavior, perfectly exponential with a time constant τ of about 680 min, is reproducible. As the nitrogen molecule cannot rotate in an argon substitutional site, and as the H 2O submolecule seems to preserve somewhat its identity, this is interpreted as nuclear spin species conversion between ortho and para states of the H 2O submolecule within the complex. The order of magnitude of the energy difference between the ortho and para lowest levels, about 5 cm -1, is too weak to imply any, even very hindered, rotational motion of H 2O, but it could be the energy range of a tunneling effect. When the temperature is increased, the two components coalesce at 25 K into a single symmetrical line pointing at 1593.3 cm -1 and the conversion time shortens dramatically. An Arrhenius plot leads to a weak activation energy of the conversion process (about 30 cm -1). A possible geometry of the complex in solid argon, different from the gas phase one, is proposed.

A Time-dependant atmospheric model of HD209458b

NASA Astrophysics Data System (ADS)

Iro, N.; Bézard, B.; Guillot, T.

2004-11-01

Charbonneau et al. (2002) conducted HST spectroscopic observations of HD209458 centered on the sodium doublet at 589.3 nm. An absorption feature was found, interpreted as an absorption from the sodium in the planet's atmosphere. However, this feature is weaker than predicted by static radiative equilibrium atmospheric models of HD209458b. We present a time-dependent radiative model of the atmosphere of HD209458b and investigate its thermal structure and chemical composition. Time-dependent temperature profiles are calculated, assuming a constant-with-height zonal wind, modelled as a solid body rotation. We predict day-night variations of the effective temperature of ˜600 K, for an equatorial rotation rate of 1 km s-1, in good agreement with the predictions by Showman & Guillot, 2002. At high altitudes (mbar pressures or less), the night temperatures are low enough to allow sodium to condense into Na2S. Synthetic transit spectra of the visible Na doublet show a much weaker sodium absorption on the morning limb than on the evening limb. The calculated dimming of the sodium feature during a planetary transit agrees with the value reported by Charbonneau et al. (2002).

Squeezing via two-photon transitions

NASA Astrophysics Data System (ADS)

Savage, C. M.; Walls, D. F.

1986-05-01

The squeezing spectrum for a cavity field mode interacting with an ensemble of three-level 'Lambda-configuration' atoms by an effective two-photon transition is calculated. The advantage of the three-level Lambda system as a squeezing medium, that is, optical nonlinearity without atomic saturation, has recently been pointed out by Reid, Walls, and Dalton. Perfect squeezing is predicted at the turning points for dispersive optical bistability and good squeezing for a range of other cases. Three-level ladder atoms interacting by an effective two-photon transition are also shown to give perfect squeezing in the dispersive limit.

Design of a dee vacuum vessel for Doublet III

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

Davis, L.G.

1983-04-01

The Doublet III tokamak is to be modified wherein the original 'doublet' plasma containment vacuum vessel will be exchanged with one of a large dee-shaped cross section. The basic dimensions of the dee vessel will allow plasmas of 1.7-m major radius, 0.7-m minor radius, and a vertical elongation of 1.8. Installation of a large dee vessel in Doublet III is made possible by the demountable toroidal field coils and the large, low-ripple volume they include. Ripple at the plasma edge will be less than one percent. The plasma parameters affecting the design of the vessel will be reviewed including plasmamore » current, power, disruption time, allowable error field, impurity control techniques, pulse length, and limiter schemes. A driving requirement for the design of the vessel is to maximize the access to the plasma for auxiliary heating (both neutral beam injection and radio frequency heating), diagnostics, developmental component and material testing, and pumping. The dee vessel is structurally designed along the same lines as the present vessel: an Inconel 625, all-welded, continuous chamber in a corrugated sandwich construction. An overview of the vessel design and its solutions to the design criteria will be presented. An overview will also be presented of the entire modification project which includes replacement of some coils, and addition of support structure, limiters and vessel armor, and power system components.« less

The onset of chromospheric activity among the A- and F- type stars

NASA Technical Reports Server (NTRS)

Simon, Theodore; Landsman, Wayne

1987-01-01

IUE observations of C II lambda1335 and C IV lambda1549 and ground-based observations of He I lambda5876 have previously discovered intense levels of chromospheric activity among early F type stars. Virtually all F dwarfs show stronger chromospheric and transition region emission than do the cooler and more deeply convective dwarf stars like the Sun. The IUE spectra and those of He lambda5876 place the onset of stellar activity along the main sequence near a color B - V = 0.28, which corresponds approximately to spectral type FO and an effective temperature of 7300 K. However, existing X-ray observations of A and F stars suggest that coronal activity may reach a peak blueward of this high temperature boundary at B - V = 0.28 before vanishing among the early and mid A-type stars. Discussed are preliminary results of a new effort to refine the location of the high temperature boundary to chromospheric activity among A- and F- type stars, making use of low dispersion short-wavelength spectra from the IUE archives from which the strengths of C IV, C II, and Lyman alpha emission have been measured.

Scalable UWB photonic generator based on the combination of doublet pulses.

PubMed

Moreno, Vanessa; Rius, Manuel; Mora, José; Muriel, Miguel A; Capmany, José

2014-06-30

We propose and experimentally demonstrate a scalable and reconfigurable optical scheme to generate high order UWB pulses. Firstly, various ultra wideband doublets are created through a process of phase-to-intensity conversion by means of a phase modulation and a dispersive media. In a second stage, doublets are combined in an optical processing unit that allows the reconfiguration of UWB high order pulses. Experimental results both in time and frequency domains are presented showing good performance related to the fractional bandwidth and spectral efficiency parameters.

HIGHLY VARIABLE EXTINCTION AND ACCRETION IN THE JET-DRIVING CLASS I-TYPE YOUNG STAR PTF 10nvg (V2492 Cyg, IRAS 20496+4354)

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

Hillenbrand, Lynne A.; Carpenter, John M.; Muirhead, Philip S.

2013-03-15

We report extensive new photometry and spectroscopy of the highly variable young stellar object PTF 10nvg (also known as IRAS 20496+4354 and V2492 Cyg), including optical and near-infrared time-series data as well as mid-infrared and millimeter data. Following the previously reported 2010 rise to R{sub PTF} {approx}<13.{sup m}5 and subsequent fade, during 2011 and 2012 the source underwent additional episodes of brightening, followed by several magnitude dimming events including prolonged faint states at R{sub PTF} {approx}> 20{sup m}. The observed high-amplitude variations are largely consistent with extinction changes ({Delta}A{sub V} up to 30 mag) having a {approx}220 day quasi-periodic signal.more » However, photometry measured when the source was near maximum brightness in mid-2010 as well as in late-2012 does not phase well to this period. Spectral evolution includes not only changes in the spectral slope but also correlated variation in the prominence of TiO/VO/CO bands and atomic line emission, as well as anti-correlated variation in forbidden line emission which, along with H{sub 2}, dominates optical and infrared spectra at faint epochs. Notably, night-to-night variations in several forbidden doublet strengths and ratios are observed. High-dispersion spectra were obtained in a variety of photometric states and reveal time-variable line profiles. Neutral and singly ionized atomic species are likely formed in an accretion flow and/or impact while the origin of zero-velocity atomic Li I {lambda}6707 in emission is unknown. Forbidden lines, including several rare species, exhibit blueshifted emission profiles and likely arise from an outflow/jet. Several of these lines are also seen spatially offset from the continuum source position, presumably in a shocked region of an extended jet. Blueshifted absorption components of the Na I D doublet, K I {lambda}{lambda}7665, 7669 doublet, and the O I 7774 triplet, as well as blueshifted absorption components seen against the broad H{alpha} and Ca II triplet emission lines, similarly are formed in the outflow. CARMA maps resolve on larger scales a spatially extended outflow in millimeter-wavelength CO. We attribute the recently observed photometric and spectroscopic behavior to rotating circumstellar disk material located at separation a Almost-Equal-To 0.7(M{sub *}/M{sub Sun }){sup 1/3} AU from the continuum source, causing the semi-periodic dimming. Occultation of the central star as well as the bright inner disk and the accretion/outflow zones renders shocked gas in the inner part of the jet amenable to observation at the faint epochs. We discuss PTF 10nvg as a source exhibiting both accretion-driven (perhaps analogous to V1647 Ori) and extinction-driven (perhaps analogous to UX Ori or GM Cep) high-amplitude variability phenomena.« less

Influence of disorder on electromagnetically induced transparency in chiral waveguide quantum electrodynamics

NASA Astrophysics Data System (ADS)

Mirza, Imran M.; Schotland, John C.

2018-05-01

We study single photon transport in a one-dimensional disordered lattice of three-level atoms coupled to an optical waveguide. In particular, we study atoms of \\Lambda-type that are capable of exhibiting electromagnetically induced transparency (EIT) and separately consider disorder in the atomic positions and transition frequencies. We mainly address the question of how preferential emission into waveguide modes (chirality) can influence the formation of spatially localized states. Our work has relevance to experimental studies of cold atoms coupled to nanoscale waveguides and has possible applications to quantum communications.

Efficient mass-selective three-photon ionization of zirconium atoms

DOEpatents

Page, Ralph H.

1994-01-01

In an AVLIS process, .sup.91 Zr is selectively removed from natural zirconium by a three-step photoionization wherein Zr atoms are irradiated by a laser beam having a wavelength .lambda..sub.1, selectively raising .sup.91 Zr atoms to an odd-parity E.sub.1 energy level in the range of 16000-19000 cm.sup.-1, are irradiated by a laser beam having a wavelength .lambda..sub.2 to raise the atoms from an E.sub.l level to an even-parity E.sub.2 energy level in the range of 35000-37000 cm.sup.-1 and are irradiated by a laser beam having a wavelength .lambda..sub.3 to cause a resonant transition of atoms from an E.sub.2 level to an autoionizing level above 53506 cm.sup.-1. .lambda..sub.3 wavelengths of 5607, 6511 or 5756 .ANG. will excite a zirconium atom from an E.sub.2 energy state of 36344 cm.sup.-1 to an autoionizing level; a .lambda..sub.3 wavelength of 5666 .ANG. will cause an autoionizing transition from an E.sub.2 level of 36068 cm.sup.-1 ; and a .lambda. .sub.3 wavelength of 5662 .ANG. will cause an ionizing resonance of an atom at an E.sub.2 level of 35904 cm.sup.-1.

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

Albrecht, Simon; Winn, Joshua N.; Marcy, Geoffrey W.

We measure the sky-projected stellar obliquities ({lambda}) in the multiple-transiting planetary systems KOI-94 and Kepler-25, using the Rossiter-McLaughlin effect. In both cases, the host stars are well aligned with the orbital planes of the planets. For KOI-94 we find {lambda} = -11 Degree-Sign {+-} 11 Degree-Sign , confirming a recent result by Hirano and coworkers. Kepler-25 was a more challenging case, because the transit depth is unusually small (0.13%). To obtain the obliquity, it was necessary to use prior knowledge of the star's projected rotation rate and apply two different analysis methods to independent wavelength regions of the spectra. Themore » two methods gave consistent results, {lambda} = 7 Degree-Sign {+-} 8 Degree-Sign and -0. Degree-Sign 5 {+-} 5. Degree-Sign 7. There are now a total of five obliquity measurements for host stars of systems of multiple-transiting planets, all of which are consistent with spin-orbit alignment. This alignment is unlikely to be the result of tidal interactions because of the relatively large orbital distances and low planetary masses in the systems. In this respect, the multiplanet host stars differ from hot-Jupiter host stars, which commonly have large spin-orbit misalignments whenever tidal interactions are weak. In particular, the weak-tide subset of hot-Jupiter hosts has obliquities consistent with an isotropic distribution (p = 0.6), but the multiplanet hosts are incompatible with such a distribution (p {approx} 10{sup -6}). This suggests that high obliquities are confined to hot-Jupiter systems, and provides further evidence that hot-Jupiter formation involves processes that tilt the planetary orbit.« less

Low temperature Mössbauer spectroscopic studies on Sm3+ doped Zn-Mn ferrites

NASA Astrophysics Data System (ADS)

Jagadeesha Angadi, V.; Kubrin, S. P.; Sarychev, D. A.; Matteppanavar, Shidaling; Rudraswamy, B.; Liu, Hsiang-Lin; Praveena, K.

2017-11-01

For the first time, we report on the low temperature Mössbauer spectroscopic study of Zn2+0.5Mn2+0.5Sm3+xFe3+2-xO4 (where x = 0.01-0.05) prepared by the modified solution combustion method using a mixture of urea and glucose as a fuel. The Mössbauer spectroscopy at room and low temperatures was applied to understand the magnetic properties of the samples. The room temperature Mössbauer spectroscopy results suggest that the occupation of the octahedral sites by Sm3+ ions leads to the distortion enhancement of 57Fe nuclei environments, which leads to an increase in quadrupole splitting Δ values of D2 and D3 doublets. The low temperature Mössbauer spectroscopy results indicate that the presence of Sm3+ ions in the octahedron sites causes the decrease in the number of Fe-O-Fe chains. The transformation of Mössbauer spectra doublets into Zeeman sextets is accompanied by a significant decrease in the magnitude IM of Mössbauer spectra intensity within the 0-1.2 mm/s velocity range normalized to its value at 300 K. This drop in the temperature dependence of IM allows one to obtain the magnetic phase transition temperature TM from the Mössbauer experiment.

Electronic structure of the BaO molecule with dipole moments and ro-vibrational calculations

NASA Astrophysics Data System (ADS)

Khatib, Mohamed; Korek, Mahmoud

2018-03-01

The twenty-three low-lying electronic states (singlet and triplet) of the BaO molecule have been studied by using an ab initio method. These electronic states have been investigated by using the Complete Active Apace Self-Consistent Field (CASSCF) followed by multi-reference configuration interaction (MRCI + Q) with Davidson correction. The potential energy curves, the internuclear distance Re, the harmonic frequency ωe, the rotational constant Be, the electronic energy with respect to the ground state Te and the static and transition dipole moment have been investigated. The Einstein spontaneous and induced emission coefficients A21 and B21ω as well as the spontaneous radiative lifetime τspon, emission wavelength λ21 and oscillator strength f21 have been calculated by using the transition dipole moment between some doublet electronic states. The calculation of the eigenvalues Ev, the rotational constant Bv, the centrifugal distortion constant Dv, and the abscissas of the turning points Rmin and Rmax have been done by using the canonical functions approach. A very good agreement is shown by comparing the values of our work to those found in the literature for many electronic states. Eighteen new electronic states have been studied here for the first time.

The nuclear structure of 223Fr

NASA Astrophysics Data System (ADS)

Kurcewicz, W.; Løvhøiden, G.; Thorsteinsen, T. F.; Borge, M. J. G.; Burke, D. G.; Cronqvist, M.; Gabelmann, H.; Gietz, H.; Hill, P.; Kaffrell, N.; Naumann, R. A.; Nybø, K.; Nyman, G.; Rogowski, J.; Isolde Collaboration

1992-03-01

The γ-rays following the β- decay of 223Rn have been investigated by means of γ-ray singles including multispectrum analysis, and γγ-coincidence measurements using Ge detectors. Multipolarities of 38 transitions in 223Fr have been established by measuring conversion electrons with a mini-orange electron spectrometer. Most of the observed transitions could be placed in a level scheme comprising 53 excited states of 223Fr. The level structure is interpreted in terms of K π = {3}/{2}± and {1}/{2}± parity doublet bands, and a second K π = {3}/{2}± higher-lying parity doublet. The experimental data are compared with the theoretical predictions of the reflection-asymmetric rotor model.

Regional Listening Forums: An Examination of the Methodologies Used by the Child Welfare League of America and Lambda Legal to Highlight the Experiences of LGBTQ Youth in Care

ERIC Educational Resources Information Center

Woronoff, Rob; Estrada, Rudy

2006-01-01

In 2002, the Child Welfare League of America (CWLA) and the Lambda Legal Defense and Education Fund began Fostering Transitions: CWLA/Lambda Joint Initiative to Support LGBTQ Youth and Adults Involved with the Child Welfare System. To document the needs of lesbian, gay, bisexual, transgender, and questioning (LGBTQ) youth, as well as identify…

A Categorification of the Crystal Isomorphism B 1,1 B + B(Lambda i) = B(Lambdasigma (i) and a Graphical Calculus for the Shifted Symmetric Functions

NASA Astrophysics Data System (ADS)

Kvinge, Henry

We prove two results at the intersection of Lie theory and the representation theory of symmetric groups, Hecke algebras, and their generalizations. The first is a categorification of the crystal isomorphism B. (1,1) tensor B1,1 ⊕ B(Lambdai ) ≅ B(Lambdasigma (i)). Here B(Lambdai and B(Lambda sigma(i)) are two affine type highest weight crystals of weight Lambdai and Lambdasigma (i) respectively, sigma is a specific map from the Dynkin indexing set I to itself, and B1,1 is a Kirillov-Reshetikhin crystal. We show that this crystal isomorphism is in fact the shadow of a richer module-theoretic phenomenon in the representation theory of Khovanov-Lauda-Rouquier algebras of classical affine type. Our second result identifies the center EndH'( 1) of Khovanov's Heisenberg category H', as the algebra of shifted symmetric functions Lambda* of Okounkov and Olshanski, i.e. End H'(1) ≅ Lambda*. This isomorphism provides us with a graphical calculus for Lambda*. It also allows us to describe EndH'(1) in terms of the transition and co-transition measure of Kerov and the noncommutative probability spaces of Biane.

Efficient mass-selective three-photon ionization of zirconium atoms

DOEpatents

Page, R.H.

1994-12-27

In an AVLIS process, [sup 91]Zr is selectively removed from natural zirconium by a three-step photoionization wherein Zr atoms are irradiated by a laser beam having a wavelength [lambda][sub 1], selectively raising [sup 91]Zr atoms to an odd-parity E[sub 1] energy level in the range of 16000--19000 cm[sup [minus]1], are irradiated by a laser beam having a wavelength [lambda][sub 2] to raise the atoms from an E[sub l] level to an even-parity E[sub 2] energy level in the range of 35000--37000 cm[sup [minus]1] and are irradiated by a laser beam having a wavelength [lambda][sub 3] to cause a resonant transition of atoms from an E[sub 2] level to an autoionizing level above 53506 cm[sup [minus]1][lambda][sub 3] wavelengths of 5607, 6511 or 5756 [angstrom] will excite a zirconium atom from an E[sub 2] energy state of 36344 cm[sup [minus]1] to an autoionizing level; a [lambda][sub 3] wavelength of 5666 [angstrom] will cause an autoionizing transition from an E[sub 2] level of 36068 cm[sup [minus]1]; and a [lambda][sub 3] wavelength of 5662 [angstrom] will cause an ionizing resonance of an atom at an E[sub 2] level of 35904 cm[sup [minus]1]. 4 figures.

Acoustic radiation from weakly wrinkled premixed flames

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

Lieuwen, Tim; Mohan, Sripathi; Rajaram, Rajesh

2006-01-01

This paper describes a theoretical analysis of acoustic radiation from weakly wrinkled (i.e., u'/S{sub L}<1) premixed flames. Specifically, it determines the transfer function relating the spectrum of the acoustic pressure oscillations, P'({omega}), to that of the turbulent velocity fluctuations in the approach flow, U'({omega}). In the weakly wrinkled limit, this transfer function is local in frequency space; i.e., velocity fluctuations at a frequency {omega} distort the flame and generate sound at the same frequency. This transfer function primarily depends upon the flame Strouhal number St (based on mean flow velocity and flame length) and the correlation length, {lambda}, of themore » flow fluctuations. For cases where the ratio of the correlation length and duct radius {lambda}/a>>1, the acoustic pressure and turbulent velocity power spectra are related by P'({omega})-{omega}{sup 2}U'({omega}) and P'({omega})-U'({omega}) for St<<1 and St>>1, respectively. For cases where {lambda}/a<<1, the transfer functions take the form P'({omega})-{omega}{sup 2}({lambda}/a){sup 2}U'({omega}) and P'({omega})-{omega}{sup 2}({lambda}/a){sup 2}({psi}-{delta}ln({lambda}/a))U'({omega}) for St<<1 and St>>1, respectively, where (PS) and {delta} are constants. The latter result demonstrates that this transfer function does not exhibit a simple power law relationship in the high frequency region of the spectra. The simultaneous dependence of this pressure-velocity transfer function upon the Strouhal number and correlation length suggests a mechanism for the experimentally observed maximum in acoustic spectra and provides some insight into the controversy in the literature over how this peak should scale with the flame Strouhal number.« less

A ring transducer system for medical ultrasound research.

PubMed

Waag, Robert C; Fedewa, Russell J

2006-10-01

An ultrasonic ring transducer system has been developed for experimental studies of scattering and imaging. The transducer consists of 2048 rectangular elements with a 2.5-MHz center frequency, a 67% -6 dB bandwidth, and a 0.23-mm pitch arranged in a 150-mm-diameter ring with a 25-mm elevation. At the center frequency, the element size is 0.30lambda x 42lambda and the pitch is 0.38lambda. The system has 128 parallel transmit channels, 16 parallel receive channels, a 2048:128 transmit multiplexer, a 2048:16 receive multiplexer, independently programmable transmit waveforms with 8-bit resolution, and receive amplifiers with time variable gain independently programmable over a 40-dB range. Receive signals are sampled at 20 MHz with 12-bit resolution. Arbitrary transmit and receive apertures can be synthesized. Calibration software minimizes system nonidealities caused by noncircularity of the ring and element-to-element response differences. Application software enables the system to be used by specification of high-level parameters in control files from which low-level hardware-dependent parameters are derived by specialized code. Use of the system is illustrated by producing focused and steered beams, synthesizing a spatially limited plane wave, measuring angular scattering, and forming b-scan images.

Rotational energy transfer of SH(X2Π, v''=0, J''=0.5-10.5) by collision with Ar: Λ-doublet resolved transition propensity.

PubMed

Tsai, Po-Yu; Lin, King-Chuen

2012-01-16

The behavior of Λ-doublet resolved rotational energy transfer (RET) by Ar collisions within the SH(X(2)Π, v''=0) state is characterized. The matrix elements of terms in the interaction potential responsible for interference effects are calculated to explain the propensity rules for collision-induced transitions within and between spin-orbit manifolds. In this manner, the physical mechanisms responsible for the F(1)-F(1), F(2)-F(2), and F(1)-F(2) transitions may be reasonably identified. As collision energy increases, the propensity for collisional population of the final e or f level is replaced by the e/f-conserving propensity. Such a change in propensity rule can be predicted in terms of energy sudden approximation at high J limit for the pure Hund's case scheme. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Echoes of the electroweak phase transition: discovering a second Higgs doublet through A0→ZH0.

PubMed

Dorsch, G C; Huber, S J; Mimasu, K; No, J M

2014-11-21

The existence of a second Higgs doublet in nature could lead to a cosmological first-order electroweak phase transition and explain the origin of the matter-antimatter asymmetry in the Universe. We obtain the spectrum and properties of the new scalars H0, A0, and H(±) that signal such a phase transition and show that the observation of the decay A0→ZH0 at LHC would be a "smoking gun" signature of these scenarios. We analyze the LHC search prospects for this decay in the ℓℓbb and ℓℓW(+)W(-) final states, arguing that current data may be sensitive to this signature in the former channel as well as there being great potential for a discovery in either channel at the very early stages of the 14 TeV run.

Prospects for measuring the 229Th isomer energy using a metallic magnetic microcalorimeter.

PubMed

Kazakov, G A; Schauer, V; Schwestka, J; Stellmer, S P; Sterba, J H; Fleischmann, A; Gastaldo, L; Pabinger, A; Enss, C; Schumm, T

2014-01-21

The Thorium-229 isotope features a nuclear isomer state with an extremely low energy. The currently most accepted energy value, 7.8±0.5 eV, was obtained from an indirect measurement using a NASA x-ray microcalorimeter with an instrumental resolution 26 eV. We study, how state-of-the-art magnetic metallic microcalorimeters with an energy resolution down to a few eV can be used to measure the isomer energy. In particular, resolving the 29.18 keV doublet in the γ-spectrum following the α-decay of Uranium-233, corresponding to the decay into the ground and isomer state, allows to measure the isomer transition energy without additional theoretical input parameters, and increase the energy accuracy. We study the possibility of resolving the 29.18 keV line as a doublet and the dependence of the attainable precision of the energy measurement on the signal and background count rates and the instrumental resolution.

Prospects for measuring the 229Th isomer energy using a metallic magnetic microcalorimeter☆

PubMed Central

Kazakov, G.A.; Schauer, V.; Schwestka, J.; Stellmer, S.P.; Sterba, J.H.; Fleischmann, A.; Gastaldo, L.; Pabinger, A.; Enss, C.; Schumm, T.

2014-01-01

The Thorium-229 isotope features a nuclear isomer state with an extremely low energy. The currently most accepted energy value, 7.8±0.5 eV, was obtained from an indirect measurement using a NASA x-ray microcalorimeter with an instrumental resolution 26 eV. We study, how state-of-the-art magnetic metallic microcalorimeters with an energy resolution down to a few eV can be used to measure the isomer energy. In particular, resolving the 29.18 keV doublet in the γ-spectrum following the α-decay of Uranium-233, corresponding to the decay into the ground and isomer state, allows to measure the isomer transition energy without additional theoretical input parameters, and increase the energy accuracy. We study the possibility of resolving the 29.18 keV line as a doublet and the dependence of the attainable precision of the energy measurement on the signal and background count rates and the instrumental resolution. PMID:25844000

Primary Dendrite Arm Spacings in Al-7Si Alloy Directionally Solidified on the International Space Station

NASA Technical Reports Server (NTRS)

Angart, Samuel; Lauer, Mark; Poirier, David; Tewari, Surendra; Rajamure, Ravi; Grugel, Richard

2015-01-01

Samples from directionally solidified Al- 7 wt. % Si have been analyzed for primary dendrite arm spacing (lambda) and radial macrosegregation. The alloy was directionally solidified (DS) aboard the ISS to determine the effect of mitigating convection on lambda and macrosegregation. Samples from terrestrial DS-experiments thermal histories are discussed for comparison. In some experiments, lambda was measured in microstructures that developed during the transition from one speed to another. To represent DS in the presence of no convection, the Hunt-Lu model was used to represent diffusion controlled growth under steady-state conditions. By sectioning cross-sections throughout the entire length of a solidified sample, lambda was measured and calculated using the model. During steady-state, there was reasonable agreement between the measured and calculated lambda's in the space-grown samples. In terrestrial samples, the differences between measured and calculated lambda's indicated that the dendritic growth was influenced by convection.

Fluctuating micro-heterogeneity in water-tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies

NASA Astrophysics Data System (ADS)

Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman

2014-05-01

Water-tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with xTBA ≈ 0.03-0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at xTBA ≈ 0.05. We note that "islands" of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak nonlinearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, xTBA ≈ 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level.

Fluctuating micro-heterogeneity in water-tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies.

PubMed

Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman

2014-05-21

Water-tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with x(TBA) ≈ 0.03-0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at x(TBA) ≈ 0.05. We note that "islands" of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak nonlinearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, x(TBA) ≈ 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level.

Comprehensive theoretical studies on the low-lying electronic states of NiF, NiCl, NiBr, and NiI.

PubMed

Zou, Wenli; Liu, Wenjian

2006-04-21

The low-lying electronic states of the nickel monohalides, i.e., NiF, NiCl, NiBr, and NiI, are investigated by using multireference second-order perturbation theory with relativistic effects taken into account. For the energetically lowest 11 lambda-S states and 26 omega states there into, the potential energy curves and corresponding spectroscopic constants (vertical and adiabatic excitation energies, equilibrium bond lengths, vibrational frequencies, and rotational constants) are reported. The calculated results are grossly in very good agreement with those solid experimental data. In particular, the ground state of NiI is shown to be different from those of NiF, NiCl, and NiBr, being in line with the recent experimental observation. Detailed analyses are provided on those states that either have not been assigned or have been incorrectly assigned by previous experiments.

The collisional drift mode in a partially ionized plasma. [in the F region

NASA Technical Reports Server (NTRS)

Hudson, M. K.; Kennel, C. F.

1974-01-01

The structure of the drift instability was examined in several density regimes. Let sub e be the total electron mean free path, k sub z the wave-vector component along the magnetic field, and the ratio of perpendicular ion diffusion to parallel electron streaming rates. At low densities (k sub z lambda 1) the drift mode is isothermal and should be treated kineticly. In the finite heat conduction regime square root of m/M k sub z Lambda sub 1) the drift instability threshold is reduced at low densities and increased at high densities as compared to the isothermal threshold. Finally, in the energy transfer limit (k sub z kambda sub e square root of m/M) the drift instability behaves adiabatically in a fully ionized plasma and isothermally in a partially ionized plasma for an ion-neutral to Coulomb collision frequency ratio.

Relationships of the internodal distance of biological tissue with its sound velocity and attenuation at high frequency in doublet mechanics

NASA Astrophysics Data System (ADS)

Cheng, Kai-Xuan; Wu, Rong-Rong; Liu, Xiao-Zhou; Liu, Jie-Hui; Gong, Xiu-Fen; Wu, Jun-Ru

2015-04-01

In view of the discrete characteristics of biological tissue, doublet mechanics has demonstrated its advantages in the mathematic description of tissue in terms of high frequency (> 10 MHz) ultrasound. In this paper, we take human breast biopsies as an example to study the influence of the internodal distance, a microscope parameter in biological tissue in doublet mechanics, on the sound velocity and attenuation by numerical simulation. The internodal distance causes the sound velocity and attenuation in biological tissue to change with the increase of frequency. The magnitude of such a change in pathological tissue is distinctly different from that in normal tissue, which can be used to differentiate pathological tissue from normal tissue and can depict the diseased tissue structure by obtaining the sound and attenuation distribution in the sample at high ultrasound frequency. A comparison of sensitivity between the doublet model and conventional continuum model is made, indicating that this is a new method of characterizing ultrasound tissue and diagnosing diseases. Project supported by the National Basic Research Program of China (Grant Nos. 2012CB921504 and 2011CB707902), the National Natural Science Foundation of China (Grant No. 11274166), the Fundamental Research Funds for the Central Universities, China (Grant Nos. 1113020403 and 1101020402), the State Key Laboratory of Acoustics, Chinese Academy of Sciences (Grant No. SKLA201401), the China Postdoctoral Science Foundation (Grant No. 2013M531313), the Priority Academic Program Development of Jiangsu Provincial Higher Education Institutions and Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry, and the Project of Interdisciplinary Center of Nanjing University, China (Grant No. NJUDC2012004).

Quadrupolar Kondo effect in uranium heavy-electron materials?

NASA Technical Reports Server (NTRS)

Cox, D. L.

1987-01-01

The possibility of an electric quadrupole Kondo effect for a non-Kramers doublet on a uranium (U) ion is a cubic metallic host is demonstrated by model calculations showing a Kondo upturn in the resistivity, universal quenching of the quadrupolar moment, and a heavy-electron anomaly in the electronic specific heat. With inclusion of excited crystal-field levels, some of the unusual magnetic-response data in the heavy-electron superconductor UBe13 may be understood. Structural phase transitions at unprecedented low temperatures may occur in U-based heavy-electron materials.

Non-Uniform Bias Enhancement of a Varactor-Tuned FSS used with a Low Profile 2.4 GHz Dipole Antenna

NASA Technical Reports Server (NTRS)

Cure, David; Weller, Thomas M.; Miranda, Felix A.

2012-01-01

In this paper a low profile antenna using a nonuniformly biased varactor-tuned frequency selective surface (FSS) is presented. The tunable FSS avoids the use of vias and has a simplified DC bias network. The voltages to the DC bias ports can be varied independently allowing adjustment in the frequency response and enhanced radiation properties. The measured data demonstrate tunability from 2.15 GHz to 2.63 GHz with peak efficiencies that range from 50% to 90% and instantaneous bandwidths of 50 MHz to 280 MHz within the tuning range. The total antenna thickness is approximately lambda/45.

Propargyl + O 2 Reaction in Helium Droplets: Entrance Channel Barrier or Not?

DOE PAGES

Moradi, Christopher P.; Morrison, Alexander M.; Klippenstein, Stephen J.; ...

2013-09-09

A combination of liquid He droplet experiments and multireference electronic structure calculations is used to probe the potential energy surface for the reaction between the propargyl radical and O 2. Infrared laser spectroscopy is used to probe the outcome of the low temperature, liquid He-mediated reaction. Bands in the spectrum are assigned to the acetylenic CH stretch (ν 1), the symmetric CH 2 stretch (ν 2), and the antisymmetric CH 2 stretch (ν 13) of the trans-acetylenic propargyl peroxy radical (•OO—CH 2—C≡CH). The observed band origins are in excellent agreement with previously reported anharmonic frequency computations for this species. Themore » Stark spectrum of the ν 1 band provides further evidence that the reaction leads only to the trans-acetylenic species. There are no other bands in the CH 2 stretching region that can be attributed to any of the other three propargyl peroxy isomers/conformers that are predicted to be minimum energy structures ( gauche-acetylenic, cis-allenic, and trans-allenic). There is also no evidence for the kinetic stabilization of a van der Waals complex between propargyl and O 2. A combination of multireference and coupled-cluster electronic structure calculations is used to probe the potential energy surface in the neighborhood of the transition state connecting reactants with the acetylenic adduct. The multireference based evaluation of the doublet-quartet splitting added to the coupled-cluster calculated quartet state energies yields what are likely the most accurate predictions for the doublet potential curve. As a result, this calculation suggests that there is no saddle point for the addition process, in agreement with the experimental observations. Other calculations suggest the possible presence of a small submerged barrier.« less

Theoretical characterization of the potential energy surface for NH + NO

NASA Technical Reports Server (NTRS)

Walch, Stephen P.

1992-01-01

The potential energy surface (PES) for NH + NO was characterized using complete active space self-consistent field (CASSCF) gradient calculations to determine the stationary point geometries and frequencies followed by CASSCF/internally contracted configuration interaction (CCI) calculations to refine the energetics. The present results are in qualitative accord with the BAC-MP4 calculations, but there are differences as large as 8 kcal/mol in the detailed energetics. Addition of NH to NO on a (2)A' surface, which correlated with N2 + OH or H + N2O products, involves barriers of 3.2 kcal/mol (trans) and 6.3 kcal/mol (cis). Experimental evidence for these barriers is found in earlier works. The (2)A' surface has no barrier to addition, but does not correlate with products. Surface crossings between the barrierless (2)A' surface and the (2)A' surface may be important. Production of N2 + OH products is predicted to occur via a planar saddle point of (2)A' symmetry. This is in accord with the preferential formation of II(A') lambda doublet levels of OH in earlier experiments. Addition of NH (1)delta to NO is found to occur on an excited state surface and is predicted to lead to N2O product as observed in earlier works.

Five-Body Cluster Structure of the Double-{Lambda} Hypernucleus {sub {Lambda}{Lambda}}{sup 11}Be

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

Hiyama, E.; Kamimura, M.; Yamamoto, Y.

2010-05-28

Energy levels of the double {Lambda} hypernucleus, {sub {Lambda}{Lambda}}{sup 11}Be are calculated within the framework of a {alpha}{alpha}n{Lambda}{Lambda} five-body model. Interactions between constituent particles are determined so as to reproduce reasonably the observed low-energy properties of the {alpha}{alpha}, {alpha}{alpha}n nuclei and the existing data for {Lambda}-binding energies of the {alpha}{Lambda}, {alpha}{alpha}{Lambda}, {alpha}n{Lambda}, and {alpha}{alpha}n{Lambda} systems. An effective {Lambda}{Lambda} interaction is constructed so as to reproduce, within the {alpha}{Lambda}{Lambda} three-body model, the B{sub {Lambda}{Lambda}}of {sub {Lambda}{Lambda}}{sup 6}He, which was extracted from the emulsion experiment, the NAGARA event. With no adjustable parameters for the {alpha}{alpha}n{Lambda}{Lambda} system, B{sub {Lambda}{Lambda}}of the ground and boundmore » excited states of {sub {Lambda}{Lambda}}{sup 11}Be are calculated with the Gaussian expansion method. The Hida event, recently observed at KEK-E373 experiment, is interpreted as an observation of the ground state of the {sub {Lambda}{Lambda}}{sup 11}Be.« less

[Excitation transfer between high-lying states in K2 in collisions with ground state K and H2 molecules].

PubMed

Shen, Xiao-Yan; Liu, Jing; Dai, Kang; Shen, Yi-Fan

2010-02-01

Pure potassium vapor or K-H2 mixture was irradiated in a glass fluorescence cell with pulses of 710 nm radiation from an OPO laser, populating K2 (1lambda(g)) state by two-photon absorption. Cross sections for 1lambda(g)-3lambda(g) transfer in K2 were determined using methods of molecular fluorescence. During the experiments with pure K vapor, the cell temperature was varied between 553 and 603 K. The K number density was determined spectroscopically by the white-light absorption measurement in the blue wing of the self-broadened resonance D2 line. The resulting fluorescence included a direct component emitted in the decay of the optically excitation and a sensitized component arising from the collisionally populated state. The decay signal of time-resolved fluorescence from1lambda(g) -->1 1sigma(u)+ transition was monitored. It was seen that just after the laser pulse the fluorescence of the photoexcited level decreased exponentially. The effective lifetimes of the 1lambda(g) state can be resolved. The plot of reciprocal of effective lifetimes of the 1lambda(g) state against K densities yielded the slope that indicated the total cross section for deactivation and the intercept that provided the radiative lifetime of the state. The radiative lifetime (20 +/- 2) ns was obtained. The cross section for deactivation of the K2(1lambda(g)) molecules by collisions with K is (2.5 +/- 0.3) x 10(-14) cm2. The time-resolved intensities of the K23lambda(g) --> 1 3sigma(u)+ (484 nm) line were measured. The radiative lifetime (16.0 +/- 3.2) ns and the total cross section (2.5 +/- 0.6) x 10(-14) cm2 for deactivation of the K2 (3lambda(g)) state can also be determined through the analogous procedure. The time-integrated intensities of 1lambda(g) --> 1 1sigma(u)+ and 3lambda(g) --> 1 3sigma(u)+ transitions were measured. The cross section (1.1 +/- 0.3) x10(-14) cm2 was obtained for K2 (1lambda(g))+ K --> K2 (3lambda(g)) + K collisions. During the experiments with K-H2 mixture, the cell temperature was kept constant at 553 K. The H2 pressure was varied between 40 and 400 Pa. The effects of K2-K collisions could not be neglected. These effects were subtracted out using the results of the pure K experiments. The cross section (2.7 +/- 1.1) x 10(-15) cm2 was obtained for K2 (1lambda(g)) + H2 --> K2 (3lambda(g))+H2 collisions. The cross section is (6.8 +/- 2.7) x 10(-15) cm2 for K2 (3lambda(g)) + H2 --> states out of K2 (3lambda(g)) + H2 collisions.

Development of torodial magnetic thermometry to study new phenomena associated with the superfluid transition in liquid sup 4 He

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

Duncan, R.V.

1988-01-01

A new type of paramagnetic susceptibility thermometry called toroidal magnetic thermometry (TMT) has been developed. These TMT thermometers have a thermal resolution of five nanoKelvin near the {sup 4}He superfluid transition temperature T{lambda} = 2.172K, making TMT roughly a factor of fifty times better in resolution than conventional germanium resistance thermometry which is commercially available. The dramatic improvement in thermal resolution provided by TMT has been used to observe new phenomena associated with the superfluid transition in pure liquid {sup 4}He. Such phenomena include a component of the thermal boundary (Kapitza) resistance R{sub K} which is singular at the superfluidmore » transition temperature T{lambda}. In addition to the boundary effects described above, these TMT thermometers have been used to detect the depression of T{lambda} be a heat current Q flowing through the liquid helium. When these values of {Delta}T{lambda}(Q) were used to calculate the depression of the superfluid density {Delta}{rho}{sub s}(Q) the results agreed well with a prediction based on the theory of Ginzburg and Pitaevskii. The calibration of the TMT thermometers provide high-resolution measurements of the a.c. paramagnetic susceptibility of their magnetic salt: Copper ammonium bromide (CAB). These calibration parameters, together with power dissipation data near the CAB Curie temperature {Tc} = 1.79K, provide information on the magnetic critical behavior of this nearly ideal Heisenberg ferromagnet. Throughout the detailed description of the TMT design, aspects of the CAB magnetic critical phenomena are discussed.« less

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

Subramaniam, S.; Marti, T.; Khorana, H.G.

Previous studies with site-specific mutants of bacteriorhodopsin have demonstrated that replacement of Asp-85 or Arg-82 affects the absorption spectrum. Between pH 5.5 and 7, the Asp-85----Glu and Arg-82----Ala mutants exist in a pH-dependent equilibrium between purple (lambda max approximately 550/540 nm) and blue (lambda max approximately 600/590 nm) forms of the pigment. Measurement of proton transport as a function of wavelength in reconstituted vesicles shows that proton-pumping activities for the above mutants reside exclusively in their respective purple species. For both mutants, formation of the blue form with decreasing pH is accompanied by loss of proton transport activity. The Asp-85----Asnmore » mutant displays a blue chromophore (lambda max approximately 588 nm), is inactive in proton translocation from pH 5 to 7.5, and shows no transition to the purple form. In contrast, the Asp-212----Asn mutant is purple (lambda max approximately 555 nm) and shows no transition to a blue chromophore with decreasing pH. The experiments suggest that (i) the pKa of the purple-to-blue transition is directly influenced by the pKa of the carboxylate at residue 85 and (ii) the relative strengths of interaction between the protonated Schiff base, Asp-85, Asp-212, and Arg-82 make a major contribution to the regulation of color and function of bacteriorhodopsin.« less

Infrared Space Observatory Observations of Far-Infrared Rotational Emission Lines of Water Vapor Toward the Supergiant Star VY Canis Majoris

NASA Technical Reports Server (NTRS)

Neufeld, David A.; Feuchtgruber, Helmut; Harwit, Martin; Melnick, Gary J.

1999-01-01

We report the detection of numerous far-infrared emission lines of water vapor toward the supergiant star VY Canis Majoris. A 29.5-45 micron grating scan of VY CMa, obtained using the Short-Wavelength Spectrometer (SWS) of the Infrared Space Observatory at a spectral resolving power lambda/delat.lambda of approximately 2000, reveals at least 41 spectral features due to water vapor that together radiate a total luminosity of approximately 25 solar luminosity . In addition to pure rotational transitions within the ground vibrational state, these features include rotational transitions within the (010) excited vibrational state. The spectrum also shows the (sup 2)product(sub 1/2) (J = 5/2) left arrow (sup 2)product(sub 3/2) (J = 3/2) OH feature near 34.6 micron in absorption. Additional SWS observations of VY CMa were carried out in the instrument's Fabry-Perot mode for three water transitions: the 7(sub 25)-6(sub 16) line at 29.8367 micron, the 4(sub 41)-3(sub 12) line at 31.7721 micron, and the 4(sub 32)-3(sub 03) line at 40.6909 micron. The higher spectral resolving power lambda/delta.lambda of approximately 30,000 thereby obtained permits the line profiles to be resolved spectrally for the first time and reveals the "P Cygni" profiles that are characteristic of emission from an outflowing envelope.

Fourier transform millimeter-wave spectroscopy of the ethyl radical in the electronic ground state.

PubMed

Kim, Eunsook; Yamamoto, Satoshi

2004-02-15

The pure rotational spectrum of the ethyl radical (C2H5) has been detected for the first time with the Fourier transform millimeter-wave spectrometer. The ethyl radical is produced by discharging the C2H5I gas diluted in Ar. The 1(01)-0(00) rotational transition of the ethyl radical is observed in the frequency range from 43,680 to 43,780 MHz. The observed spectrum shows a very complicated pattern of the fine and hyperfine structures of a doublet radical with the nuclear spins of five protons. The fine and hyperfine components are assigned with the aid of measurements of the Zeeman splittings. As a result, the 22 lines are ascribed to the transitions in the ground vibronic state (A2"). The rotational constant, the spin-rotation interaction constant, and hyperfine interaction constants are determined by the least-squares fit. The Fermi contact term of the alpha-proton is determined to be -64.1654 MHz in the gas phase, indicating that the structure of the -CH2 is essentially planar. The present rotational spectroscopic study further supports that the methyl group of the ethyl radical can be regarded as a nearly free internal rotor with a low energy barrier. A few unassigned lines still remain, which may be vibrational satellites of the internal rotation mode. Copyright 2004 American Institute of Physics

Rotational Spectrum of Sarin.

PubMed

Walker, A. R. Hight; Suenram, R. D.; Samuels, Alan; Jensen, James; Ellzy, Michael W.; Lochner, J. Michael; Zeroka, Daniel

2001-05-01

As part of an effort to examine the possibility of using molecular-beam Fourier-transform microwave spectroscopy to unambiguously detect and monitor chemical warfare agents, we report the first observation and assignment of the rotational spectrum of the nerve agent Sarin (GB) (Methylphosphonofluoridic acid 1-methyl-ethyl ester, CAS #107-44-8) at frequencies between 10 and 22 GHz. Only one of the two low-energy conformers of this organophosphorus compound (C(4)H(10)FO(2)P) was observed in the rotationally cold (T(rot)<2 K) molecular beam. The experimental asymmetric-rotor ground-state rotational constants of this conformer are A=2874.0710(9) MHz, B=1168.5776(4) MHz, C=1056.3363(4) MHz (Type A standard uncertainties are given, i.e., 1sigma), as obtained from a least-squares analysis of 74 a-, b-, and c-type rotational transitions. Several of the transitions are split into doublets due to the internal rotation of the methyl group attached to the phosphorus. The three-fold-symmetry barrier to internal rotation estimated from these splittings is 677.0(4) cm(-1). Ab initio electronic structure calculations using Hartree-Fock, density functional, and Moller-Plesset perturbation theories have also been made. The structure of the lowest-energy conformer determined from a structural optimization at the MP2/6-311G(**) level of theory is consistent with our experimental findings. Copyright 2001 Academic Press.

Rotational Spectrum of Sarin

NASA Astrophysics Data System (ADS)

Walker, A. R. Hight; Suenram, R. D.; Samuels, Alan; Jensen, James; Ellzy, Michael W.; Lochner, J. Michael; Zeroka, Daniel

2001-05-01

As part of an effort to examine the possibility of using molecular-beam Fourier-transform microwave spectroscopy to unambiguously detect and monitor chemical warfare agents, we report the first observation and assignment of the rotational spectrum of the nerve agent Sarin (GB) (Methylphosphonofluoridic acid 1-methyl-ethyl ester, CAS #107-44-8) at frequencies between 10 and 22 GHz. Only one of the two low-energy conformers of this organophosphorus compound (C4H10FO2P) was observed in the rotationally cold (Trot<2 K) molecular beam. The experimental asymmetric-rotor ground-state rotational constants of this conformer are A=2874.0710(9) MHz, B=1168.5776(4) MHz, C=1056.3363(4) MHz (Type A standard uncertainties are given, i.e., 1σ), as obtained from a least-squares analysis of 74 a-, b-, and c-type rotational transitions. Several of the transitions are split into doublets due to the internal rotation of the methyl group attached to the phosphorus. The three-fold-symmetry barrier to internal rotation estimated from these splittings is 677.0(4) cm-1. Ab initio electronic structure calculations using Hartree-Fock, density functional, and Moller-Plesset perturbation theories have also been made. The structure of the lowest-energy conformer determined from a structural optimization at the MP2/6-311G** level of theory is consistent with our experimental findings.

Off-center lithium in the fluoroperovskite KZnF sub 3

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

Toulouse, J.; Wang, X.Q.; Rousseau, M.

1991-10-01

In studying the effect of point defects on structural phase transitions in fluoroperovskites, we have characterized the Li defect in KZnF{sub 3}. The dielectric-loss measurements on KZnF{sub 3}:Li have revealed that the lithium defect possesses an electric dipole moment and therefore sits in an off-center position approximately 0.15 A from a normal K site. Complementary ultrasonic measurements of the sound velocity indicate that Li constitutes a {l angle}100{r angle} orthorhombic defect. The {delta}{ital v}/{ital v} results indicate that, similar to the KBr-KCN system, the strain ellipsoid is not an ellipsoid of revolution. The shape factors of the ellipsoid are foundmore » to be {lambda}{sub {ital a}}{minus}{lambda}{sub {ital b}}{similar to}0.013 and {lambda}{sub {ital b}}{minus}{lambda}{sub {ital c}}{similar to}0.006. This translates into two distinct relaxation processes at high and low temperatures, respectively, primarily associated with the reorientation of the major and minor axes of the ellipsoid. The dielectric-loss peak is then associated with the relaxation of the lithium defect between the three cube axes, i.e., the major-axis reorientation. The above interpretation is consistent with the large anharmonicity and anisotropy that have been found in the motion of the fluorine ions in KZnF{sub 3} and other related fluoroperovskites exhibiting a soft mode.« less

Depolymerized products of lambda-carrageenan as a potent angiogenesis inhibitor.

PubMed

Chen, Haimin; Yan, Xiaojun; Lin, Jing; Wang, Feng; Xu, Weifeng

2007-08-22

Since angiogenesis is involved in initiating and promoting several diseases such as cancer and cardiovascular events, this study was designed to evaluate the anti-angiogenesis of low-molecular-weight (LMW), highly sulfated lambda-carrageenan oligosaccharides (lambda-CO) obtained by carrageenan depolymerization, by CAM (chick chorioallantoic membrane) model and human umbilical vein endothelial cells (HUVECs). Significant inhibition of vessel growth was observed at 200 microg/pellet. A histochemistry assay also revealed a decrease of capillary plexus and connective tissue in lambda-CO treated samples. lambda-CO inhibited the viability of cells at the high concentration of 1 mg/mL, whereas it affected the cell survival slightly (>95%) at a low concentration (<250 microg/mL), and HUVEC is the most sensitive to lambda-CO among three kinds of cells. Furthermore, the inhibitory action of lambda-CO was also observed in the endothelial cell invasion and migration at relatively low concentration (150-300 microg/mL), through down-regulation of intracellular matrix metalloproteinases (MMP-2) expression on endothelial cells. Taken together, these findings demonstrate that lambda-CO is a potential angiogenesis inhibitor with combined effects of inhibiting invasion, migration, and proliferation.

Identification of Phosphorus Monoxide (X2Πr) in VY Canis Majoris: Detection of the First PO Bond in Space

NASA Astrophysics Data System (ADS)

Tenenbaum, E. D.; Woolf, N. J.; Ziurys, L. M.

2007-09-01

A new interstellar molecule, PO (X2Πr), has been detected toward the envelope of the oxygen-rich supergiant star VY Canis Majoris (VY CMa) using the Submillimeter Telescope of the Arizona Radio Observatory. The J=5.5-->4.5 and J=6.5-->5.5 rotational transitions of PO at 240 and 284 GHz were observed, each of which consisted of well-defined lambda-doublets. The line profiles are roughly parabolic in shape, analogous to PN, and suggest that this species arises from the spherical wind in VY CMa, as opposed to the collimated blue- and redshifted outflows. Comparison of line intensities indicates that PO arises from a confined source roughly 1" in extent, with a column density of Ntot ~= 2.8 × 1015 cm-2, which corresponds to a fractional abundance of f~9×10-8, relative to H2. Consequently, PO and PN have similar concentrations in VY CMa, a result not predicted by either LTE or kinetic models of circumstellar chemistry. These phosphorus compounds may arise from shock-induced reactions in this active envelope. Phosphorus monoxide is the first interstellar molecule detected that contains a PO bond, a moiety essential in biochemical compounds. It is also the first new species to be identified in an oxygen-rich, as opposed to a carbon-rich, circumstellar envelope.

A second Higgs doublet in the early universe: baryogenesis and gravitational waves

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

Dorsch, G.C.; Konstandin, T.; Huber, S.J.

We show that simple Two Higgs Doublet models might still provide a viable explanation for the matter-antimatter asymmetry of the Universe via electroweak baryogenesis, even after taking into account the recent order-of-magnitude improvement on the electron-EDM experimental bound by the ACME Collaboration. Moreover we show that, in the region of parameter space where baryogenesis may be possible, the gravitational wave spectrum generated at the end of the electroweak phase transition is within the sensitivity reach of the future space-based interferometer LISA.

An ab initio study of the low-lying doublet states of AgO and AgS

NASA Astrophysics Data System (ADS)

Bauschlicher, Charles W.; Partridge, Harry; Langhoff, Stephen R.

1990-11-01

Spectroscopic constants ( Do, re, μ e, Te) are determined for the doublet states of AgO and AgS below ≈ 30000 cm -1. valence basis sets are employed in conjunction with relativistic effective core potentials (RECPs). Electron correlation is included using the modified coupled-pair functional (MCPF) and multireferenceconfiguration interaction (MRCI) methods. The A 2Σ +-X 2Π band system is found to occur in the near infrared ( ≈ 9000 cm -1) and to be relatively weak with a radiative lifetime of 900 μs for A 2Σ + (ν = 0). The weakly bound C 2Π state (our notation), the upper state of the blue system, is found to require high levels of theoretical treatment to determine a quantitatively accurate potential. The red system is assigned as a transition from the C 2Π state to the previously unobserved A 2Σ + state. Several additional transitions are identified that should be detectable experiment A more limited study is performed for the vertical excitation spectrum of AgS. In addition, a detailed all-electron study of the X 2Π and A 2Σ + states of AgO is carried out using large atomic natural orbital (ANO) basis sets. Our best calculated Do value for AgO is significantly less than the experimental value, which suggests that there may be some systematic error in the experimental determination.

New Circumstellar Sources of PO and PN: The Increasing Role of Phosphorus Chemistry in Oxygen-rich Stars

NASA Astrophysics Data System (ADS)

Ziurys, L. M.; Schmidt, D. R.; Bernal, J. J.

2018-04-01

PO and PN have been newly identified in several oxygen-rich circumstellar envelopes, using the Submillimeter Telescope of the Arizona Radio Observatory. The J = 5 → 4 and J = 6 → 5 transitions of PN near 235 and 282 GHz, and the lambda doublets originating in the J = 5.5 → 4.5 and J = 6.5 → 5.5 lines of PO at 240 and 284 GHz, have been detected toward the shells of asymptotic giant branch (AGB) stars TX Cam and R Cas. A similar set of lines has been observed toward the supergiant NML Cyg, and new transitions of these two molecules were also measured toward the AGB star IK Tau. Along with the previous data from VY Canis Majoris (VY CMa), these spectral lines were analyzed using the non-local thermodynamic equilibrium (non-LTE) circumstellar modeling code, ESCAPADE. For the AGB stars, peak abundances found for PN and PO were f ∼ (1–2) × 10‑8 and (0.5–1) × 10‑7, respectively, while those for the supergiants were f(PN) ∼ (0.3–0.7) × 10‑8 and f(PO) ∼ (5–7) × 10‑8. PN was well modeled with a spherical radial distribution, suggesting formation near the stellar photosphere, perhaps enhanced by shocks. PO was best reproduced by a shell model, indicating a photochemical origin, except for VY CMa. Overall, the abundance of PO is a factor of 5–20 greater than that of PN. This study suggests that phosphorus-bearing molecules are common in O-rich envelopes, and that a significant amount of phosphorus (>20%) remains in the gas phase.

Torsionally mediated spin-rotation hyperfine splittings at moderate to high J values in methanol

NASA Astrophysics Data System (ADS)

Belov, S. P.; Golubiatnikov, G. Yu.; Lapinov, A. V.; Ilyushin, V. V.; Alekseev, E. A.; Mescheryakov, A. A.; Hougen, J. T.; Xu, Li-Hong

2016-07-01

This paper presents an explanation based on torsionally mediated proton-spin-overall-rotation interaction for the observation of doublet hyperfine splittings in some Lamb-dip sub-millimeter-wave transitions between ground-state torsion-rotation states of E symmetry in methanol. These unexpected doublet splittings, some as large as 70 kHz, were observed for rotational quantum numbers in the range of J = 13 to 34, and K = - 2 to +3. Because they increase nearly linearly with J for a given branch, we confined our search for an explanation to hyperfine operators containing one nuclear-spin angular momentum factor I and one overall-rotation angular momentum factor J (i.e., to spin-rotation operators) and ignored both spin-spin and spin-torsion operators, since they contain no rotational angular momentum operator. Furthermore, since traditional spin-rotation operators did not seem capable of explaining the observed splittings, we constructed totally symmetric "torsionally mediated spin-rotation operators" by multiplying the E-species spin-rotation operator by an E-species torsional-coordinate factor of the form e±niα. The resulting operator is capable of connecting the two components of a degenerate torsion-rotation E state. This has the effect of turning the hyperfine splitting pattern upside down for some nuclear-spin states, which leads to bottom-to-top and top-to-bottom hyperfine selection rules for some transitions, and thus to an explanation for the unexpectedly large observed hyperfine splittings. The constructed operator cannot contribute to hyperfine splittings in the A-species manifold because its matrix elements within the set of torsion-rotation A1 and A2 states are all zero. The theory developed here fits the observed large doublet splittings to a root-mean-square residual of less than 1 kHz and predicts unresolvable splittings for a number of transitions in which no doublet splitting was detected.

Torsionally mediated spin-rotation hyperfine splittings at moderate to high J values in methanol

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

Belov, S. P.; Golubiatnikov, G. Yu.; Lapinov, A. V.

2016-07-14

This paper presents an explanation based on torsionally mediated proton-spin–overall-rotation interaction for the observation of doublet hyperfine splittings in some Lamb-dip sub-millimeter-wave transitions between ground-state torsion-rotation states of E symmetry in methanol. These unexpected doublet splittings, some as large as 70 kHz, were observed for rotational quantum numbers in the range of J = 13 to 34, and K = − 2 to +3. Because they increase nearly linearly with J for a given branch, we confined our search for an explanation to hyperfine operators containing one nuclear-spin angular momentum factor I and one overall-rotation angular momentum factor J (i.e.,more » to spin-rotation operators) and ignored both spin-spin and spin-torsion operators, since they contain no rotational angular momentum operator. Furthermore, since traditional spin-rotation operators did not seem capable of explaining the observed splittings, we constructed totally symmetric “torsionally mediated spin-rotation operators” by multiplying the E-species spin-rotation operator by an E-species torsional-coordinate factor of the form e{sup ±niα}. The resulting operator is capable of connecting the two components of a degenerate torsion-rotation E state. This has the effect of turning the hyperfine splitting pattern upside down for some nuclear-spin states, which leads to bottom-to-top and top-to-bottom hyperfine selection rules for some transitions, and thus to an explanation for the unexpectedly large observed hyperfine splittings. The constructed operator cannot contribute to hyperfine splittings in the A-species manifold because its matrix elements within the set of torsion-rotation A{sub 1} and A{sub 2} states are all zero. The theory developed here fits the observed large doublet splittings to a root-mean-square residual of less than 1 kHz and predicts unresolvable splittings for a number of transitions in which no doublet splitting was detected.« less

Testing critical point universality along the λ-line

NASA Astrophysics Data System (ADS)

Nissen, J. A.; Swanson, D. R.; Geng, Z. K.; Dohm, V.; Israelsson, U. E.; DiPirro, M. J.; Lipa, J. A.

1998-02-01

We are currently building a prototype for a new test of critical-point universality at the lambda transition in 4He, which is to be performed in microgravity conditions. The flight experiment will measure the second-sound velocity as a function of temperature at pressures from 1 to 30 bars in the region close to the lambda line. The critical exponents and other parameters characterizing the behavior of the superfluid density will be determined from the measurements. The microgravity measurements will be quite extensive, probably taking 30 days to complete. In addition to the superfluid density, some measurements of the specific heat will be made using the low-g simulator at the Jet Propulsion Laboratory. The results of the superfluid density and specific heat measurements will be used to compare the asymptotic exponents and other universal aspects of the superfluid density with the theoretical predictions currently established by renormalization group techniques.

On the nature of the nova-like variable CD-42 deg 14462

NASA Technical Reports Server (NTRS)

Guinan, E. F.; Sion, E. M.

1981-01-01

Low dispersion long and short wavelength IUE spectra of the nova like system CD-42 deg 14462 were obtained on August 24 U.T. The short wave spectrum exhibits absorption features due to C III (lambda 1175), Lalpha 1216), NV (lambda1240), HeII (lambda 1640), SiIV (lambda1394), NIV (lambda1875) with CIV (lambda1550) as a P Cygni feature with blue shifted absorption suggesting the presence of material leaving the system. Possible interpretations of this object are discussed.

Post-translational modification and stability of low molecular weight cyclin E.

PubMed

Mull, B B; Cox, J; Bui, T; Keyomarsi, K

2009-09-03

Our laboratory has previously described the presence of five tumor-specific low molecular weight isoforms of cyclin E in both tumor cell lines and breast cancer patient biopsies. We have also shown that one of these low forms arises from an alternate start site, whereas the other four appear as two sets of doublets following cleavage through an elastase-like enzyme. However, the origin of both sets of doublets was unknown. Here, we demonstrate that the larger isoform of each doublet is the result of phosphorylation at a key degradation site. Through site-directed mutagenesis of different phosphorylation sites within the cyclin E protein, we discovered that phosphorylation of threonine 395 is responsible for generating the larger isoform of each doublet. Because phosphorylation of threonine 395 has been linked to the proteasome-mediated degradation of full length cyclin E, we examined the stability of T395A phospho-mutants in both non-tumorigenic mammary epithelial cells and tumor cells. The results revealed that the low molecular weight isoforms appear to be stable in both a tumor cell line and a non-tumor forming cell line regardless of the presence of this critical phosphorylation site. The stability of low molecular weight cyclin E may have implications for both tumorigenesis and treatment of tumors expressing them.

Compact sub-kilohertz low-frequency quantum light source based on four-wave mixing in cesium vapor

NASA Astrophysics Data System (ADS)

Ma, Rong; Liu, Wei; Qin, Zhongzhong; Su, Xiaolong; Jia, Xiaojun; Zhang, Junxiang; Gao, Jiangrui

2018-03-01

Using a nondegenerate four-wave mixing (FWM) process based on a double-{\\Lambda} scheme in hot cesium vapor, we demonstrate a compact diode-laser-pumped quantum light source for the generation of quantum correlated twin beams with a maximum squeezing of 6.5 dB. The squeezing is observed at a Fourier frequency in the audio band down to 0.7 kHz which, to the best of our knowledge, is the first observation of sub-kilohertz intensity-difference squeezing in an atomic system so far. A phase-matching condition is also investigated in our system, which confirms the spatial-multi-mode characteristics of the FWM process. Our compact low-frequency squeezed light source may find applications in quantum imaging, quantum metrology, and the transfer of optical squeezing onto a matter wave.

Detection of O VII Lambda 1522 in IUE Spectra of Planetary Nebula Nuclei and Other Hot Stars

NASA Technical Reports Server (NTRS)

Feibelman, Walter A.

1999-01-01

We present the first detection of O VII lambda 1522 emission or absorption from archival IUE spectra in 14 planetary nebula nuclei and three PG 1159-type stars. The n = 5 approaching 6 transition of O VII was determined by Kruk & Werner and observed by them in the spectrum of the very hot PG 1159-type star H1504+65 from data obtained with the Hopkins Ultraviolet Telescope (HUT). Emission-line fluxes or absorption equivalent widths as well as radial velocities for the program stars are presented. The precise rest wavelength for the 5 approaching 6 transition requires further investigation.

[In vitro anti-angiogenic action of lambda-carrageenan oligosaccharides].

PubMed

Chen, Hai-Min; Yan, Xiao-Jun; Wang, Feng; Lin, Jing; Xu, Wei-Feng

2007-06-01

This study was designed to evaluate the inhibition effect of lambda-carrageenan oligosaccharides on neovascularization in vitro by chick chorioallantoic membrane (CAM) model and human umbilical vein endothelial cell ( HUVEC). lambda-Carrageenan oligosaccharides caused a dose-dependent decrease of the vascular density of CAM, and adversely affected capillary plexus formation. At a high concentration of 1 mg x mL(-1), this compound inhibited the endothelial cell proliferation, while low concentration of lambda-carrageenan oligosaccharides (< 250 microg x mL(-1)) affected the cell survival slightly (> 95%). Different cytotoxic sensitivity of lambda-carrageenan oligosaccharides in three kinds of cells was observed, of which HUVEC is the most sensitive to this oligosaccharides. The inhibitory action of lambda-carrageenan oligosaccharides on the endothelial cell invasion and migration was also observed at relatively low concentration (150 - 300 microg x mL(-1)) through down-regulation of intracellular matrix metalloproteinases-2 (MMP-2) expression on endothelial cells. Current observations demonstrated that lambda-carrageenan oligosaccharides are potential angiogenesis inhibitor with combined effects of inhibiting invasion, migration and proliferation.

Effects of Low-frequency Current Sacral Dermatome Stimulation on Idiopathic Slow Transit Constipation

PubMed Central

Kim, Jin-Seop; Yi, Seung-Ju

2014-01-01

[Purpose] This study aimed to determine whether low-frequency current therapy can be used to reduce the symptoms of idiopathic slow transit constipation (ISTC). [Subjects] Fifteen patients (ten male and five female) with idiopathic slow transit constipation were enrolled in the present study. [Results] Bowel movements per day, bowel movements per week, and constipation assessment scale scores significantly improved after low-frequency current simulation of S2-S3. [Conclusion] Our results show that stimulation with low-frequency current of the sacral dermatomes may offer therapeutic benefits for a subject of patients with ISTC. PMID:25013277

Effects of Low-frequency Current Sacral Dermatome Stimulation on Idiopathic Slow Transit Constipation.

PubMed

Kim, Jin-Seop; Yi, Seung-Ju

2014-06-01

[Purpose] This study aimed to determine whether low-frequency current therapy can be used to reduce the symptoms of idiopathic slow transit constipation (ISTC). [Subjects] Fifteen patients (ten male and five female) with idiopathic slow transit constipation were enrolled in the present study. [Results] Bowel movements per day, bowel movements per week, and constipation assessment scale scores significantly improved after low-frequency current simulation of S2-S3. [Conclusion] Our results show that stimulation with low-frequency current of the sacral dermatomes may offer therapeutic benefits for a subject of patients with ISTC.

Crystal-field effects in fluoride crystals for optical refrigeration

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

Hehlen, Markus P

2010-01-01

The field of optical refrigeration of rare-earth-doped solids has recently seen an important breakthrough. The cooling of a YLiF{sub 4} (YLF) crystal doped with 5 mol% Yb3+ to 155 K by Seletskiy et al [NPhot] has surpassed the lowest temperatures ({approx}170 K for {approx}100 mW cooling capacity) that are practical with commercial multi-stage thermoelectric coolers (TEC) [Glaister]. This record performance has advanced laser cooling into an application relevant regime and has put first practical optical cryocoolers within reach. The result is also relevant from a material perspective since for the first time, an Yb3+-doped crystal has outperformed an Yb3+-doped glass.more » The record temperature of 208 K was held by the Yb3+-doped fluorozirconate glass ZBLAN. Advanced purification and glass fabrication methods currently under development are expected to also advance ZBLAN:Yb3+ to sub-TEC temperatures. However, recent achievements with YLF:Yb3+ illustrate that crystalline materials may have two potentially game-changing advantajes over glassy materials. First, the crystalline environment reduces the inhomogeneous broadening of the Yb3+ electronic transitions as compared to a glassy matrix. The respective sharpening of the crystal-field transitions increases the peak absorption cross section at the laser excitation wavelength and allows for more efficient pumping of the Yb3+ ions, particularly at low temperatures. Second, many detrimental impurities present in the starting materials tend to be excluded from the crystal during its slow growth process, in contrast to a glass where all impurities present in the starting materials are included in the glass when it is formed by temperature quenching a melt. The ultra high purity required for laser cooling materials [PRB] therefore may be easier to realize in crystals than in glasses. Laser cooling occurs by laser excitation of a rare-earth ion followed by anti-Stokes luminescence. Each such laser-cooling cycle extracts thermal energy from the solid and carries it away as high-entropy light, thereby cooling the material. In the ideal case, the respective laser-cooling power is given by the pump wavelength ({lambda}{sub p}), the mean fluorescence wavelength ({bar {lambda}}{sub L}), and the absorption coefficient (a{sub r}) of the pumped transition. These quantities are solely determined by crystal field interactions. On one hand, a large crystal-field splitting offers a favorably large difference of {lambda}{sub p} - {bar {lambda}}{sub L} and thus a high cooling efficiency {eta}{sub cool} = ({lambda}{sub p} - {bar {lambda}}{sub L})/{bar {lambda}}{sub L}. On the other hand, a small crystal-field splitting offers a high thermal population (n{sub i}) of the initial state of the pumped transition, giving a high pump absorption coefficient and thus high laser cooling power, particularly at low temperatures. A quantitative description of crystal-field interactions is therefore critical to the understanding and optimization of optical refrigeration. In the case of Yb3+ as the laser cooling ion, however, development of a crystal-field model is met with substantial difficulties. First, Yb3+ has only two 4/multiplets, {sup 2}F{sub 7/2} and {sup 2}F{sub 5/2}, which lead to at most 7 crystal-field levels. This makes it difficult, and in some cases impossible, to evaluate the crystal-field Hamiltonian, which has at least 4 parameters for any Yb3+ point symmety lower than cubic. Second, {sup 2}F{sub 7/2}{leftrightarrow}{sup 2}F{sub 5/2} transitions exhibit an exceptionally strong electron-phonon coupling compared to 4f transitions of other rare earths. This makes it difficult to distinguish electronic from vibronic transitions in the absorption and luminescence spectra and to reliably identify the crystal-field levels. Yb3+ crystal-field splittings reported in the literature should thus generally be viewed with caution. This paper explores the effects of crystal-field interactions on the laser cooling performance of Yb3+-doped fluoride crystals. It is shown that the total crystal-field splitting of the {sup 2}F{sub 7/2} and {sup 2}F{sub 5/2} multiplets of Yb3+ can be estimated from crystal-field splittings of other rare-earth-doped fluoride crystals. This approach takes advantage of an extensive body of experimental work from which Yb3+ doped fluoride crystals with favorable laser cooling properties might be identified. Section 2 reviews the crystal-field splitting of the 4f electronic states and introduces the crystal-field strength as a means to predict the total crystal-field splitting of the {sup 2}F{sub 7/2} and {sup 2}F{sub 5/2} multiplets. Section 3 illustrates the effect of the total {sup 2}F{sub 7/2} crystal field splitting on the laser cooling power. Finally, Section 4 compiles literature data on crystal-field splittings in fluoride crystals from which the {sup 2}F{sub 7/2} splitting is predicted.« less

High Spectral Resolution MODIS Algorithms for Ocean Chlorophyll in Case II Waters

NASA Technical Reports Server (NTRS)

Carder, Kendall L.

2004-01-01

The Case 2 chlorophyll a algorithm is based on a semi-analytical, bio-optical model of remote sensing reflectance, R(sub rs)(lambda), where R(sub rs)(lambda) is defined as the water-leaving radiance, L(sub w)(lambda), divided by the downwelling irradiance just above the sea surface, E(sub d)(lambda,0(+)). The R(sub rs)(lambda) model (Section 3) has two free variables, the absorption coefficient due to phytoplankton at 675 nm, a(sub phi)(675), and the absorption coefficient due to colored dissolved organic matter (CDOM) or gelbstoff at 400 nm, a(sub g)(400). The R(rs) model has several parameters that are fixed or can be specified based on the region and season of the MODIS scene. These control the spectral shapes of the optical constituents of the model. R(sub rs)(lambda(sub i)) values from the MODIS data processing system are placed into the model, the model is inverted, and a(sub phi)(675), a(sub g)(400) (MOD24), and chlorophyll a (MOD21, Chlor_a_3) are computed. Algorithm development is initially focused on tropical, subtropical, and summer temperate environments, and the model is parameterized in Section 4 for three different bio-optical domains: (1) high ratios of photoprotective pigments to chlorophyll and low self-shading, which for brevity, we designate as 'unpackaged'; (2) low ratios and high self-shading, which we designate as 'packaged'; and (3) a transitional or global-average type. These domains can be identified from space by comparing sea-surface temperature to nitrogen-depletion temperatures for each domain (Section 5). Algorithm errors of more than 45% are reduced to errors of less than 30% with this approach, with the greatest effect occurring at the eastern and polar boundaries of the basins. Section 6 provides an expansion of bio-optical domains into high-latitude waters. The 'fully packaged' pigment domain is introduced in this section along with a revised strategy for implementing these variable packaging domains. Chlor_a_3 values derived semi-analytically and Chlor_a_2 values derived empirically using the O Reilly et al. OC3M algorithm from MODIS Terra radiances are compared to field chlorophyll-a concentrations in Sections 7 and 8.

Generation of ultra-wideband triplet pulses based on four-wave mixing and phase-to-intensity modulation conversion.

PubMed

Li, Wei; Wang, Li Xian; Hofmann, Werner; Zhu, Ning Hua; Bimberg, Dieter

2012-08-27

We propose and demonstrate a novel scheme to generate ultra-wideband (UWB) triplet pulses based on four-wave mixing and phase-to-intensity modulation conversion. First a phase-modulated Gaussian doublet pulse is generated by four-wave mixing in a highly nonlinear fiber. Then an UWB triplet pulse is generated by generating the first-order derivative of the phase-modulated Gaussian doublet pulse using an optical filter serving as a frequency discriminator. By locating the optical signal at the linear slope of the optical filter, the phase modulated Gaussian doublet pulse is converted to an intensity-modulated UWB triplet pulse which well satisfies the Federal Communications Commission spectral mask requirements, even in the extremely power-restricted global positioning system band.

On the analysis of para-ammonia observations

NASA Technical Reports Server (NTRS)

Kuiper, T. B. H.

1994-01-01

The intensities and optical depths of the (1, 1), (2, 2), and (2, 1) inversion transitions of ammonia can be calculated quite accurately without solving the equations of statistical equilibrium. A two-temperature partition function suffices. The excitation of the K-ladders can be approximated by using a temperature obtained from a two-level model with the (2, 1) and (1, 1) levels. Distribution of populations between the ladders is described with the kinetic temperature. This enables one to compute the (1, 1) and (2, 1) inversion transition excitation temperatures and optical depths. To compute the (2, 2) brightness temperatures, the fractional population of the (2, 2) doublet is computed from the population of the (1, 1) doublet using the 'true rotation temperature,' which is calculated using a three-level model with the (2, 1), (2, 2), and (1, 1) levels. In spite of some iterative steps, the calculation is quite fast.

Electromagnetic transitions in multiple chiral doublet bands

NASA Astrophysics Data System (ADS)

Jia, Hui; Qi, Bin; Wang, Shou-Yu; Wang, Shuo; Liu, Chen

2016-12-01

Multiple chiral doublet bands (MχD) in the 80, 130 and 190 mass regions are studied by the model of γ = 90° triaxial rotor coupled with identical symmetric proton-neutron configurations. By selecting a suitable basis, the calculated wave functions are explicitly exhibited to be symmetric under the operator Â, which is defined as rotation by 90° about the 3-axis with the exchange of valance proton and neutron. We found that both M1 and E2 transitions are allowed between levels with different values of A, while they are forbidden between levels with same values of A. Such a selection rule holds true for MχD in different mass regions. Supported by National Natural Science Foundation of China (11675094, 11622540, 11545011, 11405096, 11461141001, U1432119), Shandong Natural Science Foundation (ZR2014AQ012), and Young Scholars Program of Shandong University, Weihai (2015WHWLJH01)

[Research on the emission spectrum of NO molecule's γ-band system by corona discharge].

PubMed

Zhai, Xiao-dong; Ding, Yan-jun; Peng, Zhi-min; Luo, Rui

2012-05-01

The optical emission spectrum of the gamma-band system of NO molecule, A2 sigma+ --> X2 pi(r), has been analyzed and calculated based on the energy structure of NO molecule' doublet states. By employing the theory of diatomic molecular Spectra, some key parameters of equations for the radiative transition intensity were evaluated theoretically, including the potentials of the doublet states of NO molecule's upper and lower energy levels, the electronic transition moments calculated by using r-centroid approximation method, and the Einstein coefficient of different vibrational and rotational levels. The simulated spectrum of the gamma-band system was calculated as a function of different vibrational and rotational temperature. Compared to the theoretical spectroscopy, the measured results were achieved from corona discharge experiments of NO and N2. The vibrational and rotational temperatures were determined approximately by fitting the measured spectral intensities with the calculated ones.

THE COLUMN DENSITY DISTRIBUTION AND CONTINUUM OPACITY OF THE INTERGALACTIC AND CIRCUMGALACTIC MEDIUM AT REDSHIFT (z) = 2.4

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

Rudie, Gwen C.; Steidel, Charles C.; Shapley, Alice E.

2013-06-01

We present new high-precision measurements of the opacity of the intergalactic and circumgalactic medium (IGM; CGM) at (z) = 2.4. Using Voigt profile fits to the full Ly{alpha} and Ly{beta} forests in 15 high-resolution high-S/N spectra of hyperluminous QSOs, we make the first statistically robust measurement of the frequency of absorbers with H I column densities 14{approx}< log (N{sub H{sub I}}/cm{sup -2}){approx}<17.2. We also present the first measurements of the frequency distribution of H I absorbers in the volume surrounding high-z galaxies (the CGM, 300 pkpc), finding that the incidence of absorbers in the CGM is much higher than inmore » the IGM. In agreement with Rudie et al., we find that there are fractionally more high-N{sub H{sub I}} absorbers than low-N{sub H{sub I}} absorbers in the CGM compared to the IGM, leading to a shallower power law fit to the CGM frequency distribution. We use these new measurements to calculate the total opacity of the IGM and CGM to hydrogen-ionizing photons, finding significantly higher opacity than most previous studies, especially from absorbers with log (N{sub H{sub I}}/cm{sup -2}) < 17.2. Reproducing the opacity measured in our data as well as the incidence of absorbers with log (N{sub H{sub I}}/cm{sup -2})>17.2 requires a broken power law parameterization of the frequency distribution with a break near N{sub H{sub I}} Almost-Equal-To 10{sup 15} cm{sup -2}. We compute new estimates of the mean free path ({lambda}{sub mfp}) to hydrogen-ionizing photons at z{sub em} = 2.4, finding {lambda}{sub mfp} = 147 {+-} 15 Mpc when considering only IGM opacity. If instead, we consider photons emanating from a high-z star-forming galaxy and account for the local excess opacity due to the surrounding CGM of the galaxy itself, the mean free path is reduced to {lambda}{sub mfp} = 121 {+-} 15 Mpc. These {lambda}{sub mfp} measurements are smaller than recent estimates and should inform future studies of the metagalactic UV background and of ionizing sources at z Almost-Equal-To 2-3.« less

Development of In-Fiber Reflective Bragg Gratings as Shear Stress Monitors in Aerodynamic Facilities

NASA Technical Reports Server (NTRS)

Parmar, Devendra S.; Sprinkle, Danny R.; Singh, Jag J.

1998-01-01

Bragg gratings centered at nominal wavelengths of 1290 nm and 1300 run were inscribed in a 9/125 microns germano-silicate optical fiber, using continuous wave frequency doubled Ar+ laser radiation at 244 nm. Such gratings have been used extensively as temperature and strain monitors in smart structures. They have, however, never been used for measuring aerodynamic shear stresses. As a test of their sensitivity as shear stress monitors, a Bragg fiber attached to a metal plate was subjected to laminar flows in a glass pipe. An easily measurable large flow-induced wavelength shift (Delta Lambda(sub B)) was observed in the Bragg reflected wavelength. Thereafter, the grating was calibrated by making one time, simultaneous measurements of Delta Lambda(sub B) and the coefficient of skin friction (C(sub f)) with a skin friction balance, as a function of flow rates in a subsonic wind tunnel. Onset of fan-induced transition in the tunnel flow provided a unique flow rate for correlating Delta Lambda(sub B) and (C(sub f) values needed for computing effective modulus of rigidity (N(sub eff)) of the fiber attached to the metal plate. This value Of N(sub eff) is expected to remain constant throughout the elastic stress range expected during the Bragg grating aerodynamic tests. It has been used for calculating the value of Cf at various tunnel speeds, on the basis of measured values of Bragg wavelength shifts at those speeds.

A new look at the International Duration Evaluation of Adjuvant therapy (IDEA) classification-Defining novel predictive and prognostic markers in stage III colon cancer.

PubMed

Margalit, Ofer; Mamtani, Ronac; Yang, Yu-Xiao; Reiss, Kim A; Golan, Talia; Halpern, Naama; Aderka, Dan; Giantonio, Bruce; Shacham-Shmueli, Einat; Boursi, Ben

2018-04-23

The International Duration Evaluation of Adjuvant therapy (IDEA) pooled analysis compared 3 to 6 months of adjuvant chemotherapy for stage III colon cancer. The overarching goal was to reduce chemotherapy-related toxicity, mainly oxaliplatin-induced neuropathy. Patients were classified into low-risk and high-risk groups, suggesting that low-risk patients may be offered only 3 months of treatment. We aimed to evaluate the benefit of monotherapy versus doublet chemotherapy in low and high IDEA risk groups. Using the National Cancer Database (2004-2014), we identified 56,728 low-risk and 47,557 high-risk individuals with stage III colon cancer, according to the IDEA classification. We used multivariate Cox regression to evaluate the magnitude of survival differences between IDEA risk groups, according to treatment intensity (doublet versus monotherapy). In a secondary analysis, we examined the prognostic and predictive value of subgroups of age, tumour sidedness and lymph node ratio (LNR). Low and high IDEA risk groups derived similar benefit from doublet adjuvant chemotherapy as compared with monotherapy, with hazard ratios (HRs) of 0.83 (95% confidence interval [CI] 0.79-0.86) and 0.80 (95% CI 0.78-0.83), respectively. The only subpopulations that did not benefit from doublet chemotherapy were low-risk patients older than 72 years (HR = 0.95, 95% CI 0.90-1.01) and high-risk patients older than 85 years (HR = 0.90, 95% CI 0.77-1.05). LNR and tumour sidedness were shown as additional prognostic, but not predictive, factors within the IDEA risk groups. IDEA risk classification per se does not predict for treatment benefit from doublet chemotherapy in stage III colon cancer. However, omission of oxaliplatin can be considered in IDEA low-risk patients older than 72 years. Copyright © 2018 Elsevier Ltd. All rights reserved.

Vapor deposition on doublet airfoil substrates: Control of coating thickness and microstructure

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

Rodgers, Theron M.; Zhao, Hengbei; Wadley, Haydn N. G., E-mail: haydn@virginia.edu

Gas jet assisted vapor deposition processes for depositing coatings are conducted at higher pressures than conventional physical vapor deposition methods, and have shown promise for coating complex shaped substrates including those with non-line-of-sight (NLS) regions on their surface. These regions typically receive vapor atoms at a lower rate and with a wider incident angular distribution than substrate regions in line-of-sight (LS) of the vapor source. To investigate the coating of such substrates, the thickness and microstructure variation along the inner (curved) surfaces of a model doublet airfoil containing both LS and NLS regions has been investigated. Results from atomistic simulationsmore » and experiments confirm that the coating's thickness is thinner in flux-shadowed regions than in other regions for all the coating processes investigated. They also indicated that the coatings columnar microstructure and pore volume fraction vary with surface location through the LS to NLS transition zone. A substrate rotation strategy for optimizing the thickness over the entire doublet airfoil surface was investigated, and led to the identification of a process that resulted in only small variation of coating thickness, columnar growth angle, and pore volume fraction on all doublet airfoil surfaces.« less

Magnetic ordering and crystal field effects in quasi-caged structure compound PrFe2Al8

NASA Astrophysics Data System (ADS)

Nair, Harikrishnan S.; Ghosh, Sarit K.; Ramesh Kumar, K.; Strydom, André M.

2016-04-01

The compound PrFe2Al8 possesses a three-dimensional network structure resulting from the packing of Al polyhedra centered at the transition metal element Fe and the rare earth Pr. Along the c-axis, Fe and Pr form chains which are separated from each other by the Al-network. In this paper, the magnetism and crystalline electric field effects in PrFe2Al8 are investigated through the analysis of magnetization and specific heat data. A magnetic phase transition in the Pr lattice is identified at TNPr ≈ 4 K in dc magnetization and ac susceptibility data. At 2 K, the magnetization isotherm presents a ferromagnetic saturation, however, failing to reach full spin-only ferromagnetic moment of Pr3+. Metamagnetic step-like low-field features are present in the magnetization curve at 2 K which is shown to shift upon field-cooling the material. Arrott plots centered around TPrN display "S"-like features suggestive of an inhomogeneous magnetic state. The magnetic entropy, Sm, estimated from specific heat outputs a value of R ln(2) at TN2 suggesting a doublet state for Pr3+. The magnetic specific heat is modeled by using a 9-level Schottky equation pertinent to the Pr3+ ion with J=4. Given the crystalline electric field situation of Pr3+, the inference of a doublet state from specific heat and consequent long-range magnetic order is an unexpected result.

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

Bayliss, Daniel D. R.; Sackett, Penny D.; Winn, Joshua N.

We present high-precision radial velocity observations of WASP-17 throughout the transit of its close-in giant planet, using the MIKE spectrograph on the 6.5 m Magellan Telescope at Las Campanas Observatory. By modeling the Rossiter-McLaughlin effect, we find the sky-projected spin-orbit angle to be {lambda} = 167.4 {+-} 11.2 deg. This independently confirms the previous finding that WASP-17b is on a retrograde orbit, suggesting it underwent migration via a mechanism other than just the gravitational interaction between the planet and the disk. Interestingly, our result for {lambda} differs by 45 {+-} 13 deg from the previously announced value, and we alsomore » find that the spectroscopic transit occurs 15 {+-} 5 minutes earlier than expected, based on the published ephemeris. The discrepancy in the ephemeris highlights the need for contemporaneous spectroscopic and photometric transit observations whenever possible.« less

On the luminescence of freshly introduced a-screw dislocations in low-resistance GaN

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

Medvedev, O. S., E-mail: o.s.medvedev@spbu.ru; Vyvenko, O. F.; Bondarenko, A. S.

2015-09-15

Using scanning electron microscopy in the cathodoluminescence mode, it is shown that straight segments of a-screw dislocations introduced by plastic deformation at room temperature into unintentionally doped low-resistance gallium nitride luminesce in the spectral range 3.1–3.2 eV at 70 K. The spectral composition of dislocation luminescence shows a fine doublet structure with a component width of ∼15 meV and splitting of ∼30 meV, accompanied by LO-phonon replicas. Luminescent screw dislocations move upon exposure to an electron beam and at low temperatures, but retain immobility for a long time without external excitation. Optical transitions involving the quantum-well states of a stackingmore » fault in a split-dislocation core are considered to be the most probable mechanism of the observed phenomenon.« less

Radar backscattering from snow facies of the Greenland ice sheet: Results from the AIRSAR 1991 campaign

NASA Technical Reports Server (NTRS)

Rignot, Eric; Jezek, K.; Vanzyl, J. J.; Drinkwater, Mark R.; Lou, Y. L.

1993-01-01

In June 1991, the NASA/JPL airborne SAR (AIRSAR) acquired C- (lambda = 5.6cm), L- (lambda = 24cm), and P- (lambda = 68m) band polarimetric SAR data over the Greenland ice sheet. These data are processed using version 3.55 of the AIRSAR processor which provides radiometrically and polarimetrically calibrated images. The internal calibration of the AIRSAR data is cross-checked using the radar response from corner reflectors deployed prior to flight in one of the scenes. In addition, a quantitative assessment of the noise power level at various frequencies and polarizations is made in all the scenes. Synoptic SAR data corresponding to a swath width of about 12 by 50 km in length (compared to the standard 12 x 12 km size of high-resolution scenes) are also processed and calibrated to study transitions in radar backscatter as a function of snow facies at selected frequencies and polarizations. The snow facies on the Greenland ice sheet are traditionally categorized based on differences in melting regime during the summer months. The interior of Greenland corresponds to the dry snow zone where terrain elevation is the highest and no snow melt occurs. The lowest elevation boundary of the dry snow zone is known traditionally as the dry snow line. Beneath it is the percolation zone where melting occurs in the summer and water percolates through the snow freezing at depth to form massive ice lenses and ice pipes. At the downslope margin of this zone is the wet snow line. Below it, the wet snow zone corresponds to the lowest elevations where snow remains at the end of the summer. Ablation produces enough meltwater to create areas of snow saturated with water, together with ponds and lakes. The lowest altitude zone of ablation sees enough summer melt to remove all traces of seasonal snow accumulation, such that the surface comprises bare glacier ice.

Soft x-ray emission of galliumlike rare-earth atoms produced by high-temperature low-density tokamak and high-density laser plasmas

NASA Astrophysics Data System (ADS)

Fournier, K. B.; Goldstein, W. H.; Osterheld, A.; Finkenthal, M.; Lippmann, S.; Huang, L. K.; Moos, H. W.; Spector, N.

1994-09-01

Spectra of rare-earth atoms praseodymium, Z=59, to ytterbium, Z=70, emitted from the high-temperature (1 keV) low-density (1013 cm-3) TEXT tokamak (at the Fusion Research Center, University of Texas, Austin) and high-density (1020 cm-3) laser plasmas have been recorded in the soft-x-ray range of 50-200 Å with an image intensifier detector and on photographic plates. The brightest n=4 to n=4 transitions of galliumlike ions have been identified and their emission patterns have been studied by comparison with ab initio atomic structure calculations and collisional radiative models under the respective plasma conditions. We have investigated the use of the ratios of the intensities of 4-4 transitions as indicators of plasma densities. This is possible owing to the doublet structure of the galliumlike ground state, which leads to a strong density dependence for ratios of transitions between low-lying levels. We have also used semiempirical ionization balance calculations to characterize the charge state distribution of the tokamak plasmas, in preparation for an investigation of the use of ratios of galliumlike to zinclike and copperlike emission features as indicators of whether the impurities are in coronal equilibrium or undergoing ionization.

Two-Photon/Laser-Induced Fluorescence (TP/LIF) sensor

NASA Technical Reports Server (NTRS)

Bradshaw, John D.

1994-01-01

The Two-Photon/Laser-Induced Fluorescence (TP/LIF) technique is based on the stepwise excitation of the OH transitions, X(exp 2)II, v(exp '') = 0 yields X(exp 2)II, v(exp '') = 1 (lambda = 2.9 microns) and X(exp 2)II v(exp '') = 1 yields A(exp2)Sigma, v' = 0 (lambda = 345 nm) with background free fluorescence monitoring of the A(exp 2)Sigma, v' = 0 yields X(exp 2)II, v(exp '') = 0 transition near 309 nm. This technique has awaited the advent of a suitable mid-infrared (2.9 microns) laser source. Turnable mid-IR lasers now exist that are capable of meeting the specifications required of a high sensitivity TP/LIF OH sensor.

Environmental chemistry, ecotoxicity, and fate of lambda-cyhalothrin.

PubMed

He, Li-Ming; Troiano, John; Wang, Albert; Goh, Kean

2008-01-01

Lambda-cyhalothrin is a pyrethroid insecticide used for controlling pest insects in agriculture, public health, and in construction and households. Lambda-cyhalothrin is characterized by low vapor pressure and a low Henry's law constant but by a high octanol-water partition coefficient (K(ow)) and high water-solid-organic carbon partition coefficient (K(oc)) values. Lambda-cyhalothrin is quite stable in water at pH < 8, whereas it hydrolyzes to form HCN and aldehyde under alkaline conditions. Although lambda-cyhalothrin is relatively photostable under natural irradiation, with a half-life > 3 wk, its photolysis process is fast under UV irradiation, with a half-life < 10 min. The fate of lambda-cyhalothrin in aquatic ecosystems depends on the nature of system components such as suspended solids (mineral and organic particulates) and aquatic organisms (algae, macrophytes, or aquatic animals). Lambda-cyhalothrin residues dissolved in water decrease rapidly if suspended solids and/or aquatic organisms are present because lambda-cyhalothrin molecules are strongly adsorbed by particulates and plants. Adsorbed lambda-cyhalothrin molecules show decreased degradation rates because they are less accessible to breakdown than free molecules in the water column. On the other hand, lambda-cyhalothrin adsorbed to suspended solids or bottom sediments may provide a mechanism to mitigate its acute toxicity to aquatic organisms by reducing their short-term bioavailability in the water column. The widespread use of lambda-cyhalothrin has resulted in residues in sediment, which have been found to be toxic to aquatic organisms including fish and amphipods. Mitigation measures have been used to reduce the adverse impact of lambda-cyhalothrin contributed from agricultural or urban runoff. Mitigation may be achieved by reducing the quantity of runoff and suspended solid content in runoff through wetlands, detention ponds, or vegetated ditches.

Time and force dependence of the rupture of glycoprotein IIb-IIIa-fibrinogen bonds between latex spheres.

PubMed Central

Goldsmith, H L; McIntosh, F A; Shahin, J; Frojmovic, M M

2000-01-01

We studied the shear-induced breakup of doublets of aldehyde/sulfate (A/S) latex spheres covalently linked with purified platelet GPIIb-IIIa receptor, and cross-linked by fibrinogen. Flow cytometry with fluorescein isothiocyanate-fibrinogen showed than an average of 22,500 molecules of active GPIIb-IIIa were captured per sphere, with a mean K(d) = 56 nM for fibrinogen binding. The spheres, suspended in buffered 19% Ficoll 400 containing 120 or 240 pM fibrinogen, were subjected to Couette flow in a counter-rotating cone-plate rheoscope. Doublets, formed by two-body collisions at low shear rate (G = 8 s(-1)) for < or =15 min, were subjected to shear stress from 0.6 to 2.9 Nm(-2), their rotations recorded until they broke up or were lost to view. Although breakup was time dependent, occurring mostly in the first 2 rotations after the onset of shear, the percentage of doublets broken up after 10 rotations were almost independent of normal hydrodynamic force, F(n): at 240 pN, 15.6, 16.0, and 17.0% broke up in the force range 70-150 pN, 150-230 pN, and 230-310 pN. Unexpectedly, at both [fibrinogen], the initial rate of breakup was highest in the lowest force range, and computer simulation using a stochastic model of breakup was unable to simulate the time course of breakup. When pre-sheared at low G for >15 min, no doublets broke up within 10 rotations at 70 < F(n) < 310 pN; it required >3 min shear (>1110 rotations) at F(n) = 210 pN for significant breakup to occur. Other published work has shown that binding of fibrinogen to GPIIb-IIIa immobilized on plane surfaces exhibits an initial fast reversible process with relative low affinity succeeded by transformation of GPIIb-IIIa to a stable high-affinity complex. We postulate that most doublet breakups observed within 10 rotations were from a population of young doublets having low numbers of bonds, by dissociation of the initial receptor complex relatively unresponsive to force. The remaining, older doublets with GPIIb-IIIa in the high-affinity complex were not broken up in the time or range of forces studied. PMID:10692309

Effects of tag loss on direct estimates of population growth rate

USGS Publications Warehouse

Rotella, J.J.; Hines, J.E.

2005-01-01

The temporal symmetry approach of R. Pradel can be used with capture-recapture data to produce retrospective estimates of a population's growth rate, lambda(i), and the relative contributions to lambda(i) from different components of the population. Direct estimation of lambda(i) provides an alternative to using population projection matrices to estimate asymptotic lambda and is seeing increased use. However, the robustness of direct estimates of lambda(1) to violations of several key assumptions has not yet been investigated. Here, we consider tag loss as a possible source of bias for scenarios in which the rate of tag loss is (1) the same for all marked animals in the population and (2) a function of tag age. We computed analytic approximations of the expected values for each of the parameter estimators involved in direct estimation and used those values to calculate bias and precision for each parameter estimator. Estimates of lambda(i) were robust to homogeneous rates of tag loss. When tag loss rates varied by tag age, bias occurred for some of the sampling situations evaluated, especially those with low capture probability, a high rate of tag loss, or both. For situations with low rates of tag loss and high capture probability, bias was low and often negligible. Estimates of contributions of demographic components to lambda(i) were not robust to tag loss. Tag loss reduced the precision of all estimates because tag loss results in fewer marked animals remaining available for estimation. Clearly tag loss should be prevented if possible, and should be considered in analyses of lambda(i), but tag loss does not necessarily preclude unbiased estimation of lambda(i).

Optical spectroscopy of lanthanide ions in ZnO-TeO2 glasses.

PubMed

Rolli, R; Wachtler, K; Wachtler, M; Bettinelli, M; Speghini, A; Ajò, D

2001-09-01

Zinc tellurite glasses of compositions 19ZnO-80TeO2-1Ln2O3 with Ln = Eu, Er, Nd and Tm were prepared by melt quenching. The absorption spectra were measured and from the experimental oscillator strengths of the f-->f transitions the Judd-Ofelt parameters ohm(lambda) were obtained. The values of the ohm(lambda) parameters are in the range usually observed for oxide glasses. For Nd3+ and Er3+, luminescence spectra in the near infrared were measured and the stimulated emission cross sections sigma(p) were evaluated for some laser transitions. The high values of sigma(p), especially for Nd3+, make them possible candidates for optical applications. Fluorescence line narrowing (FLN) spectra of the Eu3+ doped glass were measured at 20 K, and the energies of the Stark components of the 7F1 and 7F2 states were obtained. A crystal field analysis was carried out assuming a C2v site symmetry. The behaviour of the crystal field ratios B22/B20 and B44/B40 agrees reasonably well with the values calculated using the geometric model proposed by Brecher and Riseberg. The crystal field strength at the Eu3+ sites appears to be very low compared to other oxide glasses.

Size effects of primary/secondary twins on the atomistic deformation mechanisms in hierarchically nanotwinned metals

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

Yuan, Fuping; Wu, Xiaolei

2013-05-28

A series of large-scale molecular dynamics simulations have been performed to investigate the tensile properties of nanotwinned (NT) copper with hierarchically twinned structures (HTS). For the same grain size d and the same spacing of primary twins {lambda}{sub 1}, the average flow stress first increases as the spacing of secondary twins {lambda}{sub 2} decreases, reaching a maximum at a critical {lambda}{sub 2}, and then decreases as {lambda}{sub 2} becomes even smaller. The smaller the spacing for {lambda}{sub 1}, the smaller the critical spacing for {lambda}{sub 2}. There exists a transition in dominating deformation mechanisms, occurring at a critical spacing ofmore » {lambda}{sub 2} for which strength is maximized. Above the critical spacing of {lambda}{sub 2}, the deformation mechanisms are dominated by the two Hall-Petch type strengthening mechanisms: (a) partial dislocations emitted from grain boundaries (GBs) travel across other GBs and twin boundaries (TBs); (b) partial dislocations emitted from TBs travel across other TBs. Below the critical spacing of {lambda}{sub 2}, the deformation mechanism is dominated by the two softening mechanisms: (a) Partial dislocations emitted from boundaries of the primary twins travel parallel to the TBs of the secondary twins, leading to detwinning of the secondary twins; (b) Boundaries of the primary twins shift entirely, leading to thickening in one part of primary twins and thinning in the other part of primary twins. The present results should provide insights to design the microstructures for reinforcing the mechanical properties in the NT metals with HTS.« less

The lambda point experiment in microgravity

NASA Technical Reports Server (NTRS)

Lipa, J. A.

1988-01-01

The motivation and potential for performing very high resolution measurements of the heat capacity singularity at the lambda point of helium in microgravity conditions was briefly discussed. It is clear that tests extending deep into the asymptotic region can be performed, where the theoretical predictions take on their simplest form. This advantageous situation should lead to a major improvement in the understanding of the range of applicability of current theoretical ideas in this field. The lambda transition holds out the prospect of giving the maximum advance of any system, and with the application of cryogenic techniques, the potential of this system can be realized. The technology for the initial experiments is already developed, and results could be obtained in 1990.

The Lambda Point Experiment in Microgravity

NASA Technical Reports Server (NTRS)

Lipa, J. A.; Swanson, D. R.; Nissen, J. A.; Chui, T. C. P.

1993-01-01

In October 1992 a low temperature experiment was flown on the Space Shuttle in low earth orbit, using the JPL low temperature research facility. The objective of the mission was to measure the heat capacity and thermal relaxation of helium very close to the lambda point with the smearing effect of gravity removed.

Role of isotope mass and evidence of fluctuating zonal flows during the L–H transition in the TJ-II stellarator

NASA Astrophysics Data System (ADS)

Losada, U.; Estrada, T.; Liu, B.; van Milligen, B.; Cheng, J.; Silva, C.; Pastor, I.; Fontdecaba, J. M.; Hidalgo, C.; TJ-II team1, the

2018-07-01

Mean radial electric fields as well as low frequency Zonal Flow-like global oscillations in radial electric field have been identified during the low to high (L–H) transition in Hydrogen and Deuterium dominated plasmas in the stellarator TJ-II. No evidence of isotope effect on the L–H transition dynamics was observed in the investigated TJ-II plasma scenarios. These observations emphasize the critical role of both zero frequency (equilibrium) and low frequency varying large-scale flows for stabilizing turbulence during the triggering of the L–H transition in magnetically confined toroidal plasmas.

STS-52 Columbia, Orbiter Vehicle (OV) 102, crew insignia

NASA Technical Reports Server (NTRS)

1992-01-01

STS-52 Columbia, Orbiter Vehicle (OV) 102, crew insignia (logo), the Official insignia of the NASA STS-52 mission, features a large gold star to symbolize the crew's mission on the frontiers of space. A gold star is often used to symbolize the frontier period of the American West. The red star in the shape of the Greek letter lambda represents both the laser measurements to be taken from the Laser Geodynamic Satellite (LAGEOS II) and the Lambda Point Experiment, which is part of the United States Microgravity Payload (USMP-1). The LAGEOS II is a joint Italian United States (U.S.) satellite project intended to further our understanding of global plate tectonics. The USMP-1 is a microgravity facility which has French and U.S. experiments designed to test the theory of cooperative phase transitions and to study the solidliquid interface of a metallic alloy in the low gravity environment. The remote manipulator system (RMS) arm and maple leaf are emblematic of the Canadian payload speci

Hyper-Raman and Raman scattering from the polar modes of PbMg1/3Nb2/3O3.

PubMed

Hehlen, B; Amouri, A; Al-Zein, A; Khemakhem, H

2014-01-08

Microhyper-Raman spectroscopy of PbMg(1/3)Nb(2/3)O(3) (PMN) single crystal is performed at room temperature. The use of an optical microscope working in backscattering geometry significantly reduces the LO signal, highlighting thereby the weak contributions underneath. We clearly identify the highest frequency transverse optic mode (TO3) in addition to the previously observed soft TO-doublet at low frequency and TO2 at intermediate frequency. TO3 exhibits strong inhomogeneous broadening but perfectly fulfils the hyper-Raman cubic selection rules. The analysis shows that hyper-Raman spectroscopy is sensitive to all the vibrations of the average cubic Pm3¯m symmetry group of PMN, the three polar F1u- and the silent F2u-symmetry modes. All these vibrations can be identified in the Raman spectra alongside other vibrational bands likely arising from symmetry breaking in polar nanoregions.

Electronic structure and electron-phonon coupling in TiH$$_2$$

DOE PAGES

Shanavas, Kavungal Veedu; Lindsay, Lucas R.; Parker, David S.

2016-06-15

Calculations using first principles methods and strong coupling theory are carried out to understand the electronic structure and superconductivity in cubic and tetragonal TiHmore » $$_2$$. A large electronic density of states at the Fermi level in the cubic phase arises from Ti-$$t_{2g}$$ states and leads to a structural instability against tetragonal distortion at low temperatures. However, constraining the in-plane lattice constants diminishes the energy gain associated with the tetragonal distortion, allowing the cubic phase to be stable at low temperatures. Furthermore, calculated phonon dispersions show decoupled acoustic and optic modes arising from Ti and H vibrations, respectively and frequencies of optic modes to be rather high. The cubic phase has a large electron-phonon coupling parameter $$\\lambda$$ and critical temperature of several K. Contribution of the hydrogen sublattice to $$\\lambda$$ is found to be small in this material, which we understand from strong coupling theory to be due to the small H-$s$ DOS at the Fermi level and high energy of hydrogen modes at the tetrahedral sites.« less

Chiral geometry in multiple chiral doublet bands

NASA Astrophysics Data System (ADS)

Zhang, Hao; Chen, Qibo

2016-02-01

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

Solar wind diagnostics from Doppler-enhanced scattering

NASA Technical Reports Server (NTRS)

Noci, Giancarlo; Kohl, John L.; Withbroe, George L.

1987-01-01

Solar wind ions can attain sufficient outflow speed, w, to cause line excitation by chromospheric or transition region radiation in a nearby line. It is shown that this extends the diagnostic possibilities of a coronal EUV line to much larger values of w than would be possible if pumping were limited to radiation from the same spectral line. For the 1037.6 A coronal line of O VI, the pumping effect of the chromospheric C II 1037.0 A line is efficient for w between 100 and 250 km/s. An approximate expression for the line ratio for a doublet of the Li or Na isoelectronic sequences is derived, and the diagnostic capabilities of doublet line ratios, either by themselves or combined with the observation of other quantities, are discussed. In particular, that the determination of doublet line ratios at several heights can be sufficient to yield the solar wind velocity at those heights together with a constraint on other coronal parameters.

A comment on "Ab initio study: the potential energy curves and ro-vibrational spectrum of low-lying excited states of HCl+ cation"

NASA Astrophysics Data System (ADS)

Liu, Ya-Jun; Cheng, Xin-Lu; Chen, Hua-Jun; Cheng, Jun-Xia; Song, Xiao-Shu

2018-02-01

Since the 2Π state in HCl+ is an inverted doublet, the energy of the 2Π1/2 state is higher than the 2Π3/2. Therefore, the larger value of intensity correspond to the transition of 2Π3/2. We calculated the Einstein A coefficients and radiation lifetimes for the A2Σ+-X2Π transition. Our results are in good agreement with the experimental data and theoretical values. Then the ro-vibrational line intensities of the 1-0 band were calculated for the 2Π3/2 and 2Π1/2 states of HCl+. Employing the RKR potential, the predicted band origins for Δν=1-0 are 2569.3 and 2568.55 cm-1 for 2Π3/2 and 2Π1/2, respectively.

Anhydrous octyl-glucoside phase transition from lamellar to isotropic induced by electric and magnetic fields.

PubMed

Hashim, Rauzah; Sugimura, Akihiko; Nguan, Hock-Seng; Rahman, Matiur; Zimmermann, Herbert

2017-02-28

A static deuterium nuclear magnetic resonance ( 2 HNMR) technique (magnetic field, B = 7.05 T) was employed to monitor the thermotropic lamellar phase of the anhydrous 1:1 mixture sample of octyl-b-D-glucoside (βOG) and that of partially deuterium labelled at the alpha position on the chain, i.e.,βOG-d 2 In the absence of an electric field, the 2 H NMR spectrum of the mixture gives a typical quadrupolar doublet representing the aligned lamellar phase. Upon heating to beyond the clearing temperature at 112 °C, this splitting converts to a single line expected for an isotropic phase. Simultaneous application of magnetic and electric fields (E = 0.4 MV/m) at 85 °C in the lamellar phase, whose direction was set to be parallel or perpendicular to the magnetic field, resulted in the change of the doublet into a single line and this recovers to the initial doublet with time for both experimental geometries. This implies E- and B-field-induced phase transitions from the lamellar to an isotropic phase and a recovery to the lamellar phase again with time. Moreover, these phase transformations are accompanied by a transient current. A similar observation was made in a computational study when an electric field was applied to a water cluster system. Increasing the field strength distorts the water cluster and weakens its hydrogen bonds leading to a structural breakdown beyond a threshold field-strength. Therefore, we suggest the observed field-induced transition is likely due to a structure change of the βOG lamellar assembly caused by the field effect and not due to Joule heating.

Marginalizing Instrument Systematics in HST WFC3 Transit Light Curves

NASA Technical Reports Server (NTRS)

Wakeford, H. R.; Sing, D.K.; Deming, D.; Mandell, A.

2016-01-01

Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) infrared observations at 1.1-1.7 microns probe primarily the H2O absorption band at 1.4 microns, and have provided low-resolution transmission spectra for a wide range of exoplanets. We present the application of marginalization based on Gibson to analyze exoplanet transit light curves obtained from HST WFC3 to better determine important transit parameters such as "ramp" probability (R (sub p)) divided by "ramp" total (R (sub asterisk)), which are important for accurate detections of H2O. We approximate the evidence, often referred to as the marginal likelihood, for a grid of systematic models using the Akaike Information Criterion. We then calculate the evidence-based weight assigned to each systematic model and use the information from all tested models to calculate the final marginalized transit parameters for both the band-integrated and spectroscopic light curves to construct the transmission spectrum. We find that a majority of the highest weight models contain a correction for a linear trend in time as well as corrections related to HST orbital phase. We additionally test the dependence on the shift in spectral wavelength position over the course of the observations and find that spectroscopic wavelength shifts delta (sub lambda) times lambda) best describe the associated systematic in the spectroscopic light curves for most targets while fast scan rate observations of bright targets require an additional level of processing to produce a robust transmission spectrum. The use of marginalization allows for transparent interpretation and understanding of the instrument and the impact of each systematic evaluated statistically for each data set, expanding the ability to make true and comprehensive comparisons between exoplanet atmospheres.

First Determination of the Level Structure of an s d -Shell Hypernucleus, F19Λ

NASA Astrophysics Data System (ADS)

Yang, S. B.; Ahn, J. K.; Akazawa, Y.; Aoki, K.; Chiga, N.; Ekawa, H.; Evtoukhovitch, P.; Feliciello, A.; Fujita, M.; Hasegawa, S.; Hayakawa, S.; Hayakawa, T.; Honda, R.; Hosomi, K.; Hwang, S. H.; Ichige, N.; Ichikawa, Y.; Ikeda, M.; Imai, K.; Ishimoto, S.; Kanatsuki, S.; Kim, S. H.; Kinbara, S.; Kobayashi, K.; Koike, T.; Lee, J. Y.; Miwa, K.; Moon, T. J.; Nagae, T.; Nakada, Y.; Nakagawa, M.; Ogura, Y.; Sakaguchi, A.; Sako, H.; Sasaki, Y.; Sato, S.; Shirotori, K.; Sugimura, H.; Suto, S.; Suzuki, S.; Takahashi, T.; Tamura, H.; Tanida, K.; Togawa, Y.; Tsamalaidze, Z.; Ukai, M.; Wang, T. F.; Yamamoto, T. O.; J-PARC E13 Collaboration

2018-03-01

We report on the first observation of γ rays emitted from an s d -shell hypernucleus, F19Λ . The energy spacing between the ground state doublet, 1 /2+ and 3 /2+ states, of F19Λ is determined to be 315.5 ±0.4 (stat )-0.5+0.6(syst ) keV by measuring the γ -ray energy of the M 1 (3 /2+→1 /2+) transition. In addition, three γ -ray peaks are observed and assigned as E 2 (5 /2+→1 /2+), E 1 (1 /2-→1 /2+), and E 1 (1 /2-→3 /2+) transitions. The excitation energies of the 5 /2+ and 1 /2- states are determined to be 895.2 ±0.3 (stat )±0.5 (syst ) and 1265.6 ±1.2 (stat )-0.5+0.7(syst ) keV , respectively. It is found that the ground state doublet spacing is well described by theoretical models based on existing s - and p -shell hypernuclear data.

Syntheses and multi-NMR study of fac- and mer-OsO(3)F(2)(NCCH(3)) and the X-ray crystal structure (n = 2) and Raman spectrum (n = 0) of fac-OsO(3)F(2)(NCCH(3)).nCH(3)CN.

PubMed

Hughes, Michael J; Gerken, Michael; Mercier, Hélène P A; Schrobilgen, Gary J

2010-06-07

Dissolution of the infinite chain polymer, (OsO(3)F(2))(infinity), in CH(3)CN solvent at -40 degrees C followed by solvent removal under vacuum at -40 degrees C yielded fac-OsO(3)F(2)(NCCH(3)).nCH(3)CN (n >/= 2). Continued pumping at -40 degrees C with removal of uncoordinated CH(3)CN yielded fac-OsO(3)F(2)(NCCH(3)). Both fac-OsO(3)F(2)(NCCH(3)).nCH(3)CN and fac-OsO(3)F(2)(NCCH(3)) are yellow-brown solids and were characterized by low-temperature (-150 degrees C) Raman spectroscopy. The crystal structure (-173 degrees C) of fac-OsO(3)F(2)(NCCH(3)).2CH(3)CN consists of two co-crystallized CH(3)CN molecules and a pseudo-octahedral OsO(3)F(2).NCCH(3) molecule in which three oxygen atoms are in a facial arrangement and CH(3)CN is coordinated trans to an oxygen atom in an end-on fashion. The Os---N bond length (2.205(3) A) is among the shortest M---N adduct bonds observed for a d(0) transition metal oxide fluoride. The (19)F NMR spectrum of (OsO(3)F(2))(infinity) in CH(3)CN solvent (-40 degrees C) is a singlet (-99.6 ppm) corresponding to fac-OsO(3)F(2)(NCCH(3)). The (1)H, (15)N, (13)C, and (19)F NMR spectra of (15)N-enriched OsO(3)F(2)(NCCH(3)) were recorded in SO(2)ClF solvent (-84 degrees C). Nitrogen-15 enrichment resulted in splitting of the (19)F resonance of fac-OsO(3)F(2)((15)NCCH(3)) into a doublet ((2)J((15)N-(19)F), 21 Hz). In addition, a doublet of doublets ((2)J((19)F(ax)-(19)F(eq)), 134 Hz; (2)J((15)N-(19)F(eq)), 18 Hz) and a doublet ((2)J((19)F(ax)-(19)F(eq)), 134 Hz) were observed in the (19)F NMR spectrum that have been assigned to mer-OsO(3)F(2)((15)NCCH(3)); however, coupling of (15)N to the axial fluorine-on-osmium environment could not be resolved. The nitrogen atom of CH(3)CN is coordinated trans to a fluorine ligand in the mer-isomer. Quantum-chemical calculations at the SVWN and B3LYP levels of theory were used to calculate the energy-minimized gas-phase geometries, vibrational frequencies of fac- and mer-OsO(3)F(2)(NCCH(3)) and of CH(3)CN. The relative stabilities of the mer- and fac-isomers have been determined and are in accordance with the solution NMR assignments.

Quantum phase transition and Coulomb blockade effect in triangular quantum dots with interdot capacitive and tunnel couplings

NASA Astrophysics Data System (ADS)

Xiong, Yong-Chen; Wang, Wei-Zhong; Yang, Jun-Tao; Huang, Hai-Ming

2015-02-01

The quantum phase transition and the electronic transport in a triangular quantum dot system are investigated using the numerical renormalization group method. We concentrate on the interplay between the interdot capacitive coupling V and the interdot tunnel coupling t. For small t, three dots form a local spin doublet. As t increases, due to the competition between V and t, there exist two first-order transitions with phase sequence spin-doublet-magnetic frustration phase-orbital spin singlet. When t is absent, the evolutions of the total charge on the dots and the linear conductance are of the typical Coulomb-blockade features with increasing gate voltage. While for sufficient t, the antiferromagnetic spin correlation between dots is enhanced, and the conductance is strongly suppressed for the bonding state is almost doubly occupied. Project supported by the National Natural Science Foundation of China (Grant Nos. 10874132 and 11174228) and the Doctoral Scientific Research Foundation of HUAT (Grant No. BK201407). One of the authors (Huang Hai-Ming) supported by the Scientific Research Items Foundation of Educational Committee of Hubei Province, China (Grant No. Q20131805).

Measurements of multipolarities in 225Ra

NASA Astrophysics Data System (ADS)

Andersen, E.; Borge, M. J. G.; Burke, D. G.; Gietz, H.; Hill, P.; Kaffrell, N.; Kurcewicz, W.; Løvhøiden, G.; Mattsson, S.; Naumann, R. A.; Nybø, K.; Nyman, G.; Thorsteinsen, T. F.; Isolde Collaboration

1989-01-01

Multipolarities of 45 transitions in 225Ra have been established by investigating the radiations associated with the β - decay of 225Fr. The study includes β -, e - and γ-singles spectra, e -γ- and γγ-coincidence measurements. The conversion electrons were measured with a mini-orange electron spectrometer, and the γ-spectra with Ge detectors. The multipolarities obtained from the measured conversion coefficients support the assignments of spin-parity doublets thus giving evidence for a stable octupole deformation of this nucleus. The negative parity of the 394.2 keV level established in the present work indicates that this level is a candidate for the parity-doublet partner of the {5}/{2}+ state at 236.3 keV.

Galaxy formation in Lambda greater than 0 Friedmann models: Consequences for the number counts versus redshift test

NASA Technical Reports Server (NTRS)

Martel, Hugo

1994-01-01

We study the effect of the cosmological constant Lambda on galaxy formation using a simple spherical top-hat overdensity model. We consider models with Omega(sub 0) = 0.2, lambda(sub 0) = 0, and Omega(sub 0) = 0.2, lambda(sub 0) = 0.8 (where Omega(sub 0) is the density parameter, and lambda(sub 0) identically equal Lambda/3 H(sub 0 exp 2) where H(sub 0) is the Hubble constant). We adjust the initial power spectrum amplitude so that both models reproduce the same large-scale structures. The galaxy formation era in the lambda(sub 0) = 0 model occurs early (z approximately 6) and is very short, whereas in the lambda(sub 0) = 0.8 model the galaxy formation era starts later (z approximately 4), and last much longer, possibly all the way to the present. Consequently, galaxies at low redshift (z less than 1) are significantly more evolved in the lambda(sub 0) = 0 model than in the lambda(sub 0) = 0.8 model. This result implies that previous attempts to determine Lambda using the number counts versus redshift test are probably unreliable.

An {alpha}-cluster model for {sub {Lambda}}{sup 9}Be spectroscopy

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

Filikhin, I. N., E-mail: ifilikhin@nccu.edu; Suslov, V. M.; Vlahovic, B.

An {alpha}-cluster model is applied to study low-lying spectrum of the {sub {Lambda}}{sup 9}Be hypernucleus. The three-body {alpha}{alpha}{Lambda} problem is numerically solved by the Faddeev equations in configuration space using phenomenological pair potentials. We found a set of the potentials that reproduces experimental data for the ground state (1/2{sup +}) binding energy and excitation energy of the 5/2{sup +} and 3/2{sup +} states, simultaneously. This set includes the Ali-Bodmer potential of the version 'e' for {alpha}{alpha} and modified Tang-Herndon potential for {alpha}{Lambda} interactions. The spin-orbit {alpha}{Lambda} interaction is given by modified Scheerbaum potential. Low-lying energy levels are evaluated applying amore » variant of the analytical continuation method in the coupling constant. It is shown that the spectral properties of {sub {Lambda}}{sup 9}Be can be classified as an analog of {sup 9}Be spectrum with the exception of several 'genuine hypernuclear states'. This agrees qualitatively with previous studies. The results are compared with experimental data and new interpretation of the spectral structure is discussed.« less

An Ab Initio Study of the Low-Lying Doublet States of AgO and AgS

NASA Technical Reports Server (NTRS)

Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.

1990-01-01

Spectroscopic constants (D(sub o), r(sub e), mu(sub e), T(sub e)) are determined for the doublet states of AgO and AgS below approx. = 30000/cm. Large valence basis sets are employed in conjunction with relativistic effective core potentials (RECPs). Electron correlation is included using the modified coupled-pair functional (MCPF) and multireference configuration interaction (MRCI) methods. The A(sup 2)Sigma(sup +) - X(sup 2)Pi band system is found to occur in the near infrared (approx. = 9000/cm) and to be relatively weak with a radiative lifetime of 900 microns for A(sup 2)Sigma(sup +) (upsilon = 0). The weakly bound C(sup 2)Pi state (our notation), the upper state of the blue system, is found to require high levels of theoretical treatment to determine a quantitatively accurate potential. The red system is assigned as a transition from the C(sup 2)Pi state to the previously unobserved A(sup 2)Sigma(sup +) state. Several additional transitions are identified that should be detectable experimentally. A more limited study is performed for the vertical excitation spectrum of AgS. In addition, a detailed all-electron study of the X(sup 2)Pi and A(sup 2)Sigma(sup +) states of AgO is carried out using large atomic natural orbital (ANO) basis sets. Our best calculated D(sub o) value for AgO is significantly less than the experimental value, which suggests that there may be some systematic error in the experimental determination.

Diffractive centrosymmetric 3D-transmission phase gratings positioned at the image plane of optical systems transform lightlike 4D-WORLD as tunable resonators into spectral metrics...

NASA Astrophysics Data System (ADS)

Lauinger, Norbert

1999-08-01

Diffractive 3D phase gratings of spherical scatterers dense in hexagonal packing geometry represent adaptively tunable 4D-spatiotemporal filters with trichromatic resonance in visible spectrum. They are described in the (lambda) - chromatic and the reciprocal (nu) -aspects by reciprocal geometric translations of the lightlike Pythagoras theorem, and by the direction cosine for double cones. The most elementary resonance condition in the lightlike Pythagoras theorem is given by the transformation of the grating constants gx, gy, gz of the hexagonal 3D grating to (lambda) h1h2h3 equals (lambda) 111 with cos (alpha) equals 0.5. Through normalization of the chromaticity in the von Laue-interferences to (lambda) 111, the (nu) (lambda) equals (lambda) h1h2h3/(lambda) 111-factor of phase velocity becomes the crucial resonance factor, the 'regulating device' of the spatiotemporal interaction between 3D grating and light, space and time. In the reciprocal space equal/unequal weights and times in spectral metrics result at positions of interference maxima defined by hyperbolas and circles. A database becomes built up by optical interference for trichromatic image preprocessing, motion detection in vector space, multiple range data analysis, patchwide multiple correlations in the spatial frequency spectrum, etc.

Dynamic processes in Be star atmospheres. 2: He I 2P-nD line formation in lambda Eridani (outburst)

NASA Technical Reports Server (NTRS)

Smith, Myron A.; Hubeny, Ivan; Lanz, Thierry; Meylan, Thomas

1994-01-01

The He I lambda 6678 line of early Be stars generally shows violet (V) and red (R) emission whenever hydrogen alpha emission is present, but its use as a diagnostic has been handicapped by a poor understanding of the processes that drive it into emission. In an attempt to address this problem we obtained three series of eschelle spectra of the first two members of the singlet and triplet 2P-nD series of lambda Eri (B2e) during 1992 November 3-5 at Kitt Peak. During these observations lambda 6678 showed substantial emission variability in both the wings and central profile, providing an opportunity to compare its behavior with that of the lambda 4922, lambda 5876, and lambda 4471 lines. We found that the responses of the lines were different in several respects. Whereas the emissions in the V wings of all four lines scaled together, the R wing of the lambda 4922 line invariably responded with increased absorption whenever the R wing of lambda 6678 line showed increased emission. These same trends occurred within the central photospheric profiles. The R-wing behavior shows that much, but not all of the emission in lambda 6678 is caused by matter projected against the stellar disk. The excitation temperatures of the neighboring 2(sup 1) P transitions, lambda 6678 and lambda 4922 must be greater than and less than the photospheric continuum temperature, respectively. We have investigated departures from local thermodynamic equilibrium (LTE) for the He I spectrum in a variety of ad hoc, perturbed model atmospheres. We have found only one way to cause the source function of lambda 6678 to increase so strongly, namely, by increasing the atmospheric temperature in the line formation region to 30,000 - 40,000 K. This effect was discovered by Auer and Mihalas for O3-O4 atmospheric models, but it has not been applied to active B stars. Our models suggest that lambda 6678 emission in Be stars can be used as a sensitive monitor of localized hot spots on these stars' surfaces. The energies involved in heating the active portions of the atmosphere are too high to be produced by gravitational infall. This leaves magnetically induced flares among the few known processes on the surfaces of stars capable of sustaining this energy level.

Total enantioselectivity in the DNA binding of the dinuclear ruthenium(II) complex [[Ru(Me2bpy)2]2(mu-bpm)]4+ [bpm = 2,2'-bipyrimidine; Me2bpy = 4,4'-dimethyl-2,2'-bipyridine].

PubMed

Smith, Jayden A; Collins, J Grant; Patterson, Bradley T; Keene, F Richard

2004-05-07

The binding of the three stereoisomers (DeltaDelta-, LambdaLambda- and DeltaLambda-) of the dinuclear ruthenium(II) complex [[Ru(Me2bpy)2]2(mu-bpm)]4+ [Me2bpy = 4,4'-dimethyl-2,2'-bipyridine; bpm = 2,2'-bipyrimidine] to a tridecanucleotide containing a single adenine bulge has been studied by 1H NMR spectroscopy. The addition of the DeltaDelta-isomer to d(CCGAGAATTCCGG)2 induced significant chemical shift changes for the base and sugar resonances of the residues at the bulge site (G3A4G5/C11C10), whereas small shifts were observed upon addition of the enantiomeric LambdaLambda-form. NOESY spectra of the tridecanucleotide bound with the DeltaDelta-isomer revealed intermolecular NOE's between the metal complex and the nucleotide residues at the bulge site, while only weak NOE's were observed to terminal residues to the LambdaLambda-form. Competitive binding studies were performed where both enantiomers were simultaneously added to the tridecanucleotide, and for all ratios of the two stereoisomers the DeltaDelta-isomer remained selectively bound at the bulge site with the LambdaLambda-enantiomer localised at the terminal regions of the tridecanucleotide. The meso-diastereoisomer (DeltaLambda) was found to bind to the tridecanucleotide with characteristics intermediate between the DeltaDelta- and LambdaLambda-enantiomers of the rac form. Two distinct sets of metal complex resonances were observed, with one set having essentially the same shift as the free metal complex, whilst the other set of resonances exhibited significant shifts. The NOE data indicated that the meso-diastereoisomer does not bind as selectively as the DeltaDelta-isomer, with NOE's observed to a greater number of nucleotide residues compared to the DeltaDelta-form. This study provides a rare example of total enantioselectivity in the binding of an inert transition metal complex to DNA, produced by the shape recognition of both ruthenium(II) centres.

Low Profile Tunable Dipole Antennas Using BST Varactors for Biomedical Applications

NASA Technical Reports Server (NTRS)

Cure, David; Weller, Thomas; Price, Tony; Miranda, Felix A.

2013-01-01

In this presentation a 2.4 GHz low profile (lambda45) tunable dipole antenna is evaluated in the presence of a human core model (HCM) body phantom. The antenna uses a frequency selective surface (FSS) with interdigital barium strontium titanate (BST) varactor-tuned unit cells and its performance is compared to a similar low profile antenna that uses an FSS with semiconductor varactor diodes. The measured data of the antenna demonstrate tunability from 2.2 GHz to 2.55 GHz in free space and impedance match improvement in the presence of a HCM at different distances. This antenna has smaller size, lower cost and less weight compared to the semiconductor varactor diode counterpart.

Low Profile Tunable Dipole Antenna Using BST Varactors for Biomedical Applications

NASA Technical Reports Server (NTRS)

Cure, David; Weller, Thomas M.; Miranda, Felix A.; Price, Tony

2013-01-01

In this paper a 2.4 GHz low profile (lambda/47) tunable dipole antenna is evaluated in the presence of a human core model (HCM) body phantom. The antenna uses a frequency selective surface (FSS) with interdigital barium strontium titanate (BST) varactor-tuned unit cells and its performance is compared to a similar low profile antenna that uses an FSS with semiconductor varactor diodes. The measured data of the antenna demonstrate tunability from 2.2 GHz to 2.55 GHz in free space and impedance match improvement in the presence of a HCM at different distances. This antenna has smaller size, lower cost and less weight compared to the semiconductor varactor diode counterpart.

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

Tripathi, Anjali; Winn, Joshua N.; De Kleer, Katherine R.

We present new spectroscopic and photometric observations of the transiting exoplanetary system WASP-3. Spectra obtained during two separate transits exhibit the Rossiter-McLaughlin (RM) effect and allow us to estimate the sky-projected angle between the planetary orbital axis and the stellar rotation axis, {lambda} = 3.3{sup +2.5}{sub -4.4} deg. This alignment between the axes suggests that WASP-3b has a low orbital inclination relative to the equatorial plane of its parent star. During our first night of spectroscopic measurements, we observed an unexpected redshift briefly exceeding the expected sum of the orbital and RM velocities by 140 m s{sup -1}. This anomalymore » could represent the occultation of material erupting from the stellar photosphere, although it is more likely to be an artifact caused by moonlight scattered into the spectrograph.« less

Mass loss in HR 1040 /A0 Ia/ - Analysis of Mg II lambda 2802 and H-alpha

NASA Technical Reports Server (NTRS)

Kunasz, P. B.; Morrison, N. D.; Spressart, B.

1983-01-01

It is pointed out that International Ultraviolet Explorer (IUE) data for several early A type supergiants are now available to complement the ground-based spectroscopic data available for these bright stars. An examination of the resonance doublet of Mg II in the A type supergiants reveals that HR 1040 (HD 21389) is the only star in the observational literature in which a violet-shifted, deep absorption line is present without complete saturation. From an unsaturated profile, a good estimate of Mg(+) density can be found by means of accurate radiative transfer calculations. A relation can then be derived between mass loss rate and ionization balance. When certain velocity-related quantities can be estimated from a Mg II line profile, the H-alpha provides an estimate of the mass loss rate. The present investigation is concerned with an application of these diagnostics to HR 1040.

Assessment of resistance risk to lambda-cyhalothrin and cross-resistance to four other insecticides in the house fly, Musca domestica L. (Diptera: Muscidae).

PubMed

Abbas, Naeem; Shad, Sarfraz Ali

2015-07-01

Lambda-cyhalothrin, a sodium channel modulator insecticide, has been used frequently for the control of house flies, Musca domestica L. (Diptera: Muscidae) worldwide, including Pakistan. This experiment was performed to determine the selection and assessment of lambda-cyhalothrin resistance evolution along with four other insecticides. After 26 generations of selection, the lambda-cyhalothrin-selected population developed 445-fold resistance to lambda-cyhalothrin compared to the susceptible population. There was low cross-resistance to bifenthrin and very low cross-resistance to methomyl, imidacloprid, and fipronil in the lambda-cyhalothrin-selected population compared to the field population (G1). Realized heritability (h (2)) of resistance to lambda-cyhalothrin, bifenthrin, methomyl, imidacloprid, and fipronil was 0.07, 0.05, 0.01, 0.08, and 0.08, respectively. The projected rate of resistance development revealed that if 90 % house flies were selected, then a tenfold increase in lethal concentration 50 occurred after 17, 20, 159, 13, and 14 generations for lambda-cyhalothrin (h (2) = 0.07, slope = 2.09), bifenthrin (h (2) = 0.05, slope = 1.73), methomyl (h (2) = 0.01, slope = 2.52), imidacloprid (h (2) = 0.08, slope = 1.89), and fipronil (h (2) = 0.08, slope = 2.03), respectively. The results of our study concluded that the house fly has the potential to develop multiple insecticide resistances following continued selection pressure with lambda-cyhalothrin. This study will be helpful for assisting the development of resistance management strategies.

Experimental verification and simulation of negative index of refraction using Snell's law.

PubMed

Parazzoli, C G; Greegor, R B; Li, K; Koltenbah, B E C; Tanielian, M

2003-03-14

We report the results of a Snell's law experiment on a negative index of refraction material in free space from 12.6 to 13.2 GHz. Numerical simulations using Maxwell's equations solvers show good agreement with the experimental results, confirming the existence of negative index of refraction materials. The index of refraction is a function of frequency. At 12.6 GHz we measure and compute the real part of the index of refraction to be -1.05. The measurements and simulations of the electromagnetic field profiles were performed at distances of 14lambda and 28lambda from the sample; the fields were also computed at 100lambda.

A Randomized Study of Peginterferon Lambda-1a Compared to Peginterferon Alfa-2a in Combination with Ribavirin and Telaprevir in Patients with Genotype-1 Chronic Hepatitis C.

PubMed

Flisiak, Robert; Shiffman, Mitchell; Arenas, Juan; Cheinquer, Hugo; Nikitin, Igor; Dong, Yuping; Rana, Khurram; Srinivasan, Subasree

2016-01-01

A randomized, double-blind, multinational, phase 3 study was conducted comparing the efficacy and safety of peginterferon lambda-1a (Lambda)/ribavirin (RBV)/telaprevir (TVR) vs. peginterferon alfa-2a (Alfa)/RBV/TVR in patients with chronic hepatitis C virus (HCV) genotype-1 (GT-1) infection. Patients (treatment-naïve or relapsers on prior Alfa/RBV treatment) were randomly assigned in a 2:1 ratio to receive Lambda/RBV/TVR or Alfa/RBV/TVR. Total duration of treatment was either 24 or 48 weeks (response-guided treatment), with TVR administered for the first 12 weeks. The primary endpoint was the proportion of patients who achieved a sustained virologic response at post treatment week 12 (SVR12), which was tested for noninferiority of Lambda/RBV/TVR. A total of 838 patients were enrolled, and 617 were treated; 411 and 206 patients received Lambda/RBV/TVR and Alfa/RBV/TVR, respectively. The majority of patients were treatment-naïve, with HCV GT-1b and a high baseline viral load (≥800,000 IU/mL). Less than 10% of patients had cirrhosis (Lambda, 7.5%; Alfa, 6.8%). Lambda/RBV/TVR did not meet the criterion for noninferiority (lower bound of the treatment difference interval was -12.3%); the SVR12 in all patients (modified intent-to-treat) was 76.2% in the Lambda arm and 82.0% in the Alfa arm. Overall, the frequency of adverse events in each arm was comparable (Lambda, 91.7%; Alfa, 97.1%). As expected based on the safety profile of the 2 interferons, there were more hepatobiliary events observed in the Lambda arm and more hematologic events in the Alfa arm. In this comparison of Lambda/RBV/TVR and Alfa/RBV/TVR in patients who were treatment-naïve or had relapsed on prior Alfa/RBV treatment, Lambda failed to demonstrate noninferiority based on SVR12 results. Treatment with Lambda/RBV/TVR was associated with a higher incidence of relapse. More patients discontinued Lambda/RBV/TVR treatment during the first 4 weeks of study treatment, mainly due to hepatobiliary-related events, and more Lambda patients were lost to follow-up.

Er{sup 3+}-doped strontium lithium bismuth borate glasses for broadband 1.5 {mu}m emission - optical properties

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

Rajesh, D.; Balakrishna, A.; Ratnakaram, Y. C.

2013-02-05

Strontium lithium bismuth borate glasses (SLBiB) doped with various concentrations of Er{sup 3+} were prepared using conventional melt quench technique and investigated their optical properties. The amorphous nature of the prepared glass samples was confirmed by X-ray diffraction and SEM analysis. Optical properties were studied by measuring the optical absorption and near infrared luminescence spectra at room temperature. Judd-Ofelt (J-O) theory has been applied for the f.f transitions of Er{sup 3+} ions to evaluate J-O intensity parameters, {Omega}{lambda} ({lambda} = 2, 4 and 6). Using the J-O intensity parameters, radiative properties such as transition probabilities (A{sub R}), branching ratios ({beta})more » and radiative lifetimes ({tau}) are estimated for certain transitions. From the emission spectra, peak emission-cross sections ({sigma}{sub p}) and products of stimulated emission cross-section and full width at half maximum ({sigma}{sub p} Multiplication-Sign FWHM) were calculated for the observed emission transition, {sup 4}I{sub 13/2}{yields}{sup 4}I{sub 15/2}.« less

A New Method of High-Precision Positioning for an Indoor Pseudolite without Using the Known Point Initialization.

PubMed

Zhao, Yinzhi; Zhang, Peng; Guo, Jiming; Li, Xin; Wang, Jinling; Yang, Fei; Wang, Xinzhe

2018-06-20

Due to the great influence of multipath effect, noise, clock and error on pseudorange, the carrier phase double difference equation is widely used in high-precision indoor pseudolite positioning. The initial position is determined mostly by the known point initialization (KPI) method, and then the ambiguities can be fixed with the LAMBDA method. In this paper, a new method without using the KPI to achieve high-precision indoor pseudolite positioning is proposed. The initial coordinates can be quickly obtained to meet the accuracy requirement of the indoor LAMBDA method. The detailed processes of the method follows: Aiming at the low-cost single-frequency pseudolite system, the static differential pseudolite system (DPL) method is used to obtain the low-accuracy positioning coordinates of the rover station quickly. Then, the ambiguity function method (AFM) is used to search for the coordinates in the corresponding epoch. The real coordinates obtained by AFM can meet the initial accuracy requirement of the LAMBDA method, so that the double difference carrier phase ambiguities can be correctly fixed. Following the above steps, high-precision indoor pseudolite positioning can be realized. Several experiments, including static and dynamic tests, are conducted to verify the feasibility of the new method. According to the results of the experiments, the initial coordinates with the accuracy of decimeter level through the DPL can be obtained. For the AFM part, both a one-meter search scope and two-centimeter or four-centimeter search steps are used to ensure the precision at the centimeter level and high search efficiency. After dealing with the problem of multiple peaks caused by the ambiguity cosine function, the coordinate information of the maximum ambiguity function value (AFV) is taken as the initial value of the LAMBDA, and the ambiguities can be fixed quickly. The new method provides accuracies at the centimeter level for dynamic experiments and at the millimeter level for static ones.

Two Higgs doublets with fourth-generation fermions: Models for TeV-scale compositeness

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

Soni A.; Bar-Shalom, S.; Nandi, S.

2011-09-21

We construct a class of two Higgs doublets models with a 4th sequential generation of fermions that may effectively accommodate the low-energy characteristics and phenomenology of a dynamical electroweak symmetry breaking scenario which is triggered by the condensates of the 4th family fermions. In particular, we single out the heavy quarks by coupling the heavier Higgs doublet ({Phi}{sub h}) which possesses a much larger VEV only to them while the lighter doublet ({Phi}{sub {ell}) couples only to the light fermions. We study the constraints on these models from precision electroweak data as well as from flavor data. We also discussmore » some distinct new features that have direct consequences on the production and decays of the 4th family quarks and leptons in high-energy colliders; in particular, the conventional search strategies for t{prime} and b{prime} may need to be significantly revised.« less

Quartz Microbalance Study of 400-angstrom Thick Films near the lambda Point

NASA Technical Reports Server (NTRS)

Chan, Moses H. W.

2003-01-01

In a recent measurement we observed the thinning of an adsorbed helium film induced by the confinement of critical fluctuations a few millikelvin below the lambda point. A capacitor set-up was used to measure this Casimir effect. In this poster we will present our measurement of an adsorbed helium film of 400 angstroms near the lambda point with a quartz microbalance. For films this thick, we must take into account the non-linear dynamics of the shear waves in the fluid. In spite of the added complications, we were able to confirm the thinning of the film due to the Casimir effect and the onset of the superfluid transition. In addition, we observe a sharp anomaly at the bulk lambda point, most likely related to critical dissipation of the first sound. This work is carried out in collaboration with Rafael Garcia, Stephen Jordon and John Lazzaretti. This work is funded by NASA's Office of Biological and Physical Research under grant.

Comparative studies on the conformational change and aggregation behavior of irradiated carrageenans and agar by dynamic light scattering.

PubMed

Abad, Lucille; Okabe, Satoshi; Shibayama, Mitsuhiro; Kudo, Hisaaki; Saiki, Seiichi; Aranilla, Charito; Relleve, Lorna; de la Rosa, Alumanda

2008-01-01

The conformational associative properties of kappa-, iota-, and lambda-carrageenan and agar with irradiation dose were studied by dynamic light scattering. The random scission of the carrageenans and agar by gamma irradiation resulted in the formation of polydispersed lower molecular weight fragments. At high doses, the system moves towards uniformity. Conformational change from coil to helix was observed in all carrageenans and agar at doses up to 100 kGy. The conformational change in lambda-carrageenan may be due to the irregular and hybrid structure of this polysaccharide. Only agar and lambda-carrageenan still undergo conformational transition at a high dose of 200 kGy. Gelation is observed for kappa-, iota-carrageenan up to a dose of 50 kGy while gelation is still observed at 100 kGy for agar. Increase in the hydrodynamic radius with decreasing temperatures for the non-irradiated carrageenans follows this order: lambda-carrageenan>kappa-carrageenan>iota-carrageenan. Slight increases in hydrodynamic radius were observed with irradiation.

Possible forerunners of earthquakes in optical range

NASA Astrophysics Data System (ADS)

Malnev, V. N.; Martysh, E. V.; Koshevya, S.; Kotsarenko, A.; Siqueiros Alatorre, J.

2007-05-01

The monitoring of the electrostatic field on the eve of the strong earthquakes detect its ultra-low-frequency perturbations with a period of a few hours (10-4Hz) and a magnitude of the order of 10 V/cm. Usually this field is on the level of one V/cm. The anomalous electric field as a forerunner of the coming earthquake considerably increases a concentration of the metal ions (sodium) in the E-domain at altitudes ~120 km and the electron concentration, as well. In particular, the latter may enlarge by one order comparing with the initial electron concentration in this domain. The typical dimensions of this layer are ~ 100 km in a length and ~ 10 km in a thickness. The perturbations of this electric field form a layer with higher than usual concentration of sodium ions and atoms in the E- ionosphere and the field will heats-up electrons in this layer. Simple evaluations show the electron temperature in this layer in the presence of the seismogenic electric field is approximately about 1000-1300K at altitudes 100-120 km provided that the electric field is ~ 10-3 V/cm. It is important the cross-section of excitation of the nitrogen low vibration levels by electrons at this energy is anomalous and close to 5x10-15cm2. It happens to be that the eighth vibration level of a nitrogen molecule practically coincides with the first excited state of a sodium atom with energy ENa=2.1eV. Thus, the resonant transfer of the vibration energy of excited nitrogen with excitation of a sodium atom takes place practically in every collision. Our evaluation of the sodium doublet intensity due to the above-discussed mechanism from the ionosphere layer, mentioned above, gives 5x10-3erg/cm2s. A comparison of this quantity with the conventional intensity of the sodium doublet from this layer 7x10-4erg/cm2s shows that the suggested mechanism provides the intensity almost by one order larger than the conventional intensity of the sodium doublet. The considerable increasing in the intensity of the sodium doublet in the spectrum of the night ionosphere can be registered by monitoring the night sky over the seismic dangerous regions.

Femtosecond resolution of soft mode dynamics in structural phase transitions

NASA Technical Reports Server (NTRS)

Dougherty, Thomas P.; Wiederrecht, Gary P.; Nelson, Keith A.; Garrett, Mark H.; Jensen, Hans P.; Warde, Cardinal

1992-01-01

The microscopic pathway along which ions or molecules in a crystal move during structural phase transition can often be described in terms of a collective vibrational mode of the lattice. In many cases, this mode, called a 'soft' phonon mode because of its characteristically low frequency near the phase transition temperature, is difficult to characterize through conventional frequency-domain spectroscopies such as light or neutron scattering. A femtosecond time-domain analog of light-scattering spectroscopy called impulsive stimulated Raman scattering (ISRS) has been used to examine the soft modes of two perovskite ferroelectric crystals. The low-frequency lattice dynamics of KNbO3 and BaTiO3 are clarified in a manner that permits critical evaluation of microscopic models for their ferroelectric transitions. The results illustrate the advantages of ISRS over conventional Raman spectroscopy of low-frequency, heavily damped soft modes.

High accuracy thermal conductivity measurements near the lambda transition of helium with very high temperature resolution

NASA Technical Reports Server (NTRS)

Fairbank, William M.; Lipa, John A.

1989-01-01

Over the past few years extensive thermal conductivity measurements near the lambda point of helium were made. The original goal of measuring the thermal conductivity with a resolution of t = T/T sub lambda -1 of 3 x 10(-8) was reached, but with somewhat less accuracy than was hoped. Subtle effects in the apparatus near the transition were observed which reduced the ability to interpret the results. Nevertheless, for resolution of t is greater than or equal to 10(-7) reliable data was obtained, extending previous measurements by more than an order of magnitude. Deviations from theoretical predictions were observed for t is less than or equal to 3 x 10(-6) leading to the question of the validity of the present renormalization group analysis of transport properties, at least for the case of helium. This anomaly led to closer examination of the boundary effects in the measurements. During the experiments a totally unexpected effect in the very dilute He-3 - He-4 mixtures was observed which led to the explanation of the anomalous results. The concentration dependence of the thermal conductivity near T sub lambda in the superfluid phase was found to deviate strongly from the predictions. The results gave an independent verification of this behavior and caused reanalysis of the Khalatnikov theory of hydrodynamics of the mixtures. An alternative solution was found which is in better agreement with the experiment.

Analysis of wavelet-filtered tonic-clonic electroencephalogram recordings.

PubMed

Rosso, O A; Figliola, A; Creso, J; Serrano, E

2004-07-01

EEG signals obtained during tonic-clonic epileptic seizures can be severely contaminated by muscle and physiological noise. Heavily contaminated EEG signals are hard to analyse quantitatively and also are usually rejected for visual inspection by physicians, resulting in a considerable loss of collected information. The aim of this work was to develop a computer-based method of time series analysis for such EEGs. A method is presented for filtering those frequencies associated with muscle activity using a wavelet transform. One of the advantages of this method over traditional filtering is that wavelet filtering of some frequency bands does not modify the pattern of the remaining ones. In consequence, the dynamics associated with them do not change. After generation of a 'noise free' signal by removal of the muscle artifacts using wavelets, a dynamic analysis was performed using non-linear dynamics metric tools. The characteristic parameters evaluated (correlation dimension D2 and largest Lyapunov exponent lambda1) were compatible with those obtained in previous works. The average values obtained were: D2=4.25 and lambda1=3.27 for the pre-ictal stage; D2=4.03 and lambda1=2.68 for the tonic seizure stage; D2=4.11 and lambda1=2.46 for the clonic seizure stage.

Growth and magnetooptical properties of anisotropic TbF3 single crystals

NASA Astrophysics Data System (ADS)

Valiev, Uygun V.; Karimov, Denis N.; Burdick, Gary W.; Rakhimov, Rakhim; Pelenovich, Vasiliy O.; Fu, Dejun

2017-06-01

This paper investigates the Faraday effect and absorption and luminescence spectra of single-crystal TbF3 measured at 90 K and 300 K. The optical-quality single-phase TbF3 crystals (structural type β-YF3) were grown by the Bridgman technique. Faraday rotation angles were measured at remagnetization along the [100] crystallographic axis. Low temperature optical measurements were carried out along the [100] axis. "Quasi-doublet" sublevels with energy at 0 cm-1, 65 cm-1, and 190 cm-1, and also a singlet sublevel with energy at 114 cm-1 located in the ground 7F6 multiplet were determined from the low temperature luminescence spectra. The Van-Vleck behavior of the magnetic susceptibility χb can be satisfactorily explained by the magnetic mixing of wave functions belonging to the ground and first excited "quasi-doublet" sublevels at 0 and 65 cm-1, respectively. Analysis of the oscillation dependences of the rotation angle showed that the value of the natural birefringence (Δn ≈ 0.0186) remains nearly constant within the wavelength and temperature ranges under investigation. As the temperature decreases, we find significant increases in the oscillation amplitude of the rotation angle and in the Verdet constant V. The spectral dependences V(χ) are linear throughout the temperature range. The magnetooptical activity of TbF3 can be explained by means of the spin- and parity-allowed electric-dipole 4f → 5d transitions in the Tb3+ ions.

Fully developed turbulence and complex time singularities

NASA Astrophysics Data System (ADS)

Dombre, T.; Gagne, Y.; Hopfinger, E.

The hypothesis of Frisch and Morf (1981), relating intermittent bursts observed in high-pass-filtered turbulent-flow data to complex time singularities in the solution of the Navier-Stokes equations, is tested experimentally. Velocity signals filtered at high-pass frequency 1 kHz and low-pass frequency 6 kHz are recorded for 7 min at sampling frequency 20 kHz in a flow of mean velocity 6.1 m/s, with mesh length d = 7.5 cm, observation point x/d = 40, R sub lambda = 67, dissipation length eta = 0.5 mm, and Kolmogorov frequency fK = about 2 kHz. The results are presented in graphs, and it is shown that the exponential behavior of the energy spectrum settles well before fK, the spectra of individual bursts having exponential behavior and delta(asterisk) values consistent with the Frisch-Morf hypothesis, at least for high-amplitude events.

Switch over to the high frequency rf systems near transition

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

Brennan, J.M.; Wei, J.

1988-01-01

The purpose of this note is to point out that since bunch narrowing naturally occurs in the acceleration process in the vicinity of transition, it should be possible to switch over to the high frequency system close to transition when the bunch has narrowed enough to fit directly into the high frequency bucket. The advantage of this approach is the simplicity, no extra components or gymnastics are required of the low frequency system. The disadvantage, of course, is for protons which do not go through transition. But on the other hand, there is no shortage of intensity for protons andmore » so it should be possible to keep the phase space area low for protons, and then matching to the high frequency bucket should be easily accomplished by adiabatic compression. 3 refs., 7 figs.« less

Hierarchical versus degenerate 2HDM: The LHC run 1 legacy at the onset of run 2

NASA Astrophysics Data System (ADS)

Dorsch, G. C.; Huber, S. J.; Mimasu, K.; No, J. M.

2016-06-01

Current discussions of the allowed two-Higgs-doublet model parameter space after LHC run 1 and the prospects for run 2 are commonly phrased in the context of a quasidegenerate spectrum for the new scalars. Here, we discuss the generic situation of a two-Higgs-doublet model with a nondegenerate spectrum for the new scalars. This is highly motivated from a cosmological perspective since it naturally leads to a strongly first-order electroweak phase transition that could explain the matter-antimatter asymmetry in the Universe. While constraints from measurements of Higgs signal strengths do not change, those from searches of new scalar states get modified dramatically once a nondegenerate spectrum is considered.

Far-infrared spectrophotometer for astronomical observations

NASA Technical Reports Server (NTRS)

Moseley, H.; Silverberg, R. F.

1981-01-01

A liquid-helium-cooled far infrared spectrophotometer was built and used to make low resolution observations of the continua of several kinds of astronomical objects using the Kuiper Airborne Observatory. This instrument fills a gap in both sensitivity to continuum sources and spectral resolution between the broadband photometers with lambda/Delta lambda approximately 1 and spectrometers with lambda/Delta lambda greater than 50. While designed primarily to study planetary nebulae, the instrument permits study of the shape of the continua of many weak sources which cannot easily be observed with high resolution systems.

[Spectral emissivity of thin films].

PubMed

Zhong, D

2001-02-01

In this paper, the contribution of multiple reflections in thin film to the spectral emissivity of thin films of low absorption is discussed. The expression of emissivity of thin films derived here is related to the thin film thickness d and the optical constants n(lambda) and k(lambda). It is shown that in the special case d-->infinity the emissivity of thin films is equivalent to that of the bulk material. Realistic numerical and more precise general numerical results for the dependence of the emissivity on d, n(lambda) and k(lambda) are given.

Results of Detailed Modeling of the Narrow-Line Region of Seyfert Galaxies

NASA Technical Reports Server (NTRS)

Moore, David; Cohen, Ross D.

1996-01-01

We present model line profiles of [O II] lambda3727, [Ne III] lambda3869, [O I] lambda5007, [Fe VII] lambda6087, [Fe X] lambda6374, [O I] lambda6300, H(alpha) lambda6563, and [S 2] lambda6731. The profiles presented here illustrate explicitly the pronounced effects that collisional de-excitation, and that spatial variations in both the ionization parameter and cloud column density, have on Narrow-Line Region (NLR) model profiles. The above effects were included only qualitatively in a previous analytical treatment by Moore and Cohen. By making a direct correspondence between these model profiles and the analytical model profiles of Moore and Cohen, and by comparing with the observed profiles presented in a companion paper and also with those presented elsewhere in the literature, we strengthen some of the conclusions of Moore and Cohen. Most notably, we argue for constant ionization parameter, uniformly accelerated outflow of clouds that are individually stratified in ionization, and the interpretation of emission-line width correlations with ionization potential as a column density effect. For comparison with previous observational studies, such as our own in a companion paper, we also calculate profile parameters for some of the models, and we present and discuss the resulting line width correlations with critical density (n(sub cr)) and Ionization Potential (IP). Because the models we favor are those that produce extended profile wings as observed in high spectral resolution studies, the line width correlations of our favoured models are of particular interest. Line width correlations with n(sub cr) and/or IP result only if the width parameter is more sensitive to extended profile wings than is the Full Width at Half-Maximum (FWHM). Correlations between FWHM and n(sub cr) and/or IP result only after convolving the model profiles with a broad instrumental profile that simulates the lower spectral resolution used in early observational studies. The model in agreement with the greatest number of observational considerations has electron density decreasing outward from n(sub e) approx. equals 10(exp 6)/cu cm to n(sub e) approx. equals 10(exp 2)/cu cm and, due to collisional de-excitation effects in the lowest velocity clouds, it generates broad flat-topped profile peaks in the lines of lowest critical density (e.g., [O II] lambda3727 and [S II] lambda(lambda)6716, 6731). Because the observed profile peaks of both low and high critical density lines are often very similar, our favored model requires a contribution to NLR emission-line spectra from low-velocity, low-density, and low-ionization gas not included in the model NLR.

Low-level laser therapy of myofascial pain syndromes of patients with osteoarthritis of knee and hip joints

NASA Astrophysics Data System (ADS)

Gasparyan, Levon V.

2001-04-01

The purpose of the given research is the comparison of efficiency of conventional treatment of myofascial pain syndromes of patients with osteoarthritis (OA) of hip and knee joints and therapy with additional application of low level laser therapy (LLLT) under dynamic control of clinical picture, rheovasographic, electromyographic examinations, and parameters of peroxide lipid oxidation. The investigation was made on 143 patients with OA of hip and knee joints. Patients were randomized in 2 groups: basic group included 91 patients, receiving conventional therapy with a course of LLLT, control group included 52 patients, receiving conventional treatment only. Transcutaneous ((lambda) equals 890 nm, output peak power 5 W, frequency 80 - 3000 Hz) and intravenous ((lambda) equals 633 nm, output 2 mW in the vein) laser irradiation were used for LLLT. Studied showed, that clinical efficiency of LLLT in the complex with conventional treatment of myofascial pain syndromes at the patients with OA is connected with attenuation of pain syndrome, normalization of parameters of myofascial syndrome, normalization of the vascular tension and parameters of rheographic curves, as well as with activation of antioxidant protection system.

Spectrophotometry of Wolf-Rayet stars. I - Continuum energy distributions

NASA Technical Reports Server (NTRS)

Morris, Patrick W.; Brownsberger, Kenneth R.; Conti, Peter S.; Massey, Philip; Vacca, William D.

1993-01-01

All available low-resolution IUE spectra are assembled for Galactic, LMC, and SMC W-R stars and are merged with ground-based optical and NIR spectra in order to collate in a systematic fashion the shapes of these energy distributions over the wavelength range 0.1-1 micron. They can be consistently fitted by a power law of the form F(lambda) is approximately equal to lambda exp -alpha over the range 1500-9000 A to derive color excesses E(B-V) and spectral indices by removing the 2175-A interstellar absorption feature. The WN star color excesses derived are found to be in good agreement with those of Schmutz and Vacca (1991) and Koesterke et al. (1991). Significant heterogeneity in spectral index values was generally seen with any given subtype, but the groups consisting of the combined set of Galactic and LMC W-R stars, the separate WN and WC sequences, and the Galactic and LMC W-R stars all showed a striking and consistent Gaussian-like frequency distribution of values.

Magnetic field power density spectra during 'scatter-free' solar particle events

NASA Technical Reports Server (NTRS)

Tan, L. C.; Mason, G. M.

1993-01-01

We have examined interplanetary magnetic field power spectral density during four previously identified 3He-rich flare periods when the about 1 MeV nucleon-1 particles exhibited nearly scatter-free transport from the sun to 1 AU. Since the scattering mean free path A was large, it might be expected that interplanetary turbulence was low, yet the spectral density value was low only for one of the four periods. For the other three, however, the spectral index q of the power density spectrum was near 2.0, a value at which quasi-linear theories predict an increase in the scattering mean free path. Comparing the lambda values from the energetic particles with that computed from a recent quasi-linear theory which includes helicity and the propagation direction of waves, we find lambda(QLT)/lambda(SEP) = 0.08 +/- 0.03 for the four events. Thus, the theory fits the q-dependence of lambda; however, as found for previous quasi-linear theories, the absolute value is low.

Why anthropic reasoning cannot predict Lambda.

PubMed

Starkman, Glenn D; Trotta, Roberto

2006-11-17

We revisit anthropic arguments purporting to explain the measured value of the cosmological constant. We argue that different ways of assigning probabilities to candidate universes lead to totally different anthropic predictions. As an explicit example, we show that weighting different universes by the total number of possible observations leads to an extremely small probability for observing a value of Lambda equal to or greater than what we now measure. We conclude that anthropic reasoning within the framework of probability as frequency is ill-defined and that in the absence of a fundamental motivation for selecting one weighting scheme over another the anthropic principle cannot be used to explain the value of Lambda, nor, likely, any other physical parameters.

Modeling of heat extraction from variably fractured porous media in Enhanced Geothermal Systems

DOE PAGES

Hadgu, Teklu; Kalinina, Elena Arkadievna; Lowry, Thomas Stephen

2016-01-30

Modeling of heat extraction in Enhanced Geothermal Systems is presented. The study builds on recent studies on the use of directional wells to improve heat transfer between doublet injection and production wells. The current study focuses on the influence of fracture orientation on production temperature in deep low permeability geothermal systems, and the effects of directional drilling and separation distance between boreholes on heat extraction. The modeling results indicate that fracture orientation with respect to the well-pair plane has significant influence on reservoir thermal drawdown. As a result, the vertical well doublet is impacted significantly more than the horizontal wellmore » doublet« less

Effects of ΛΛ ‑ ΞN mixing in the decay of {}_{{\\rm{\\Lambda }}{\\rm{\\Lambda }}}{}^{6}{\\rm{H}}{\\rm{e}}

NASA Astrophysics Data System (ADS)

Maneu, J.; Parreño, A.; Ramos, A.

2018-05-01

A one-meson exchange model including the ground state of the pseudoscalar octet is used to describe the weak two-body interactions responsible for the decay of {}{{Λ }{{Λ }}}{}6{{H}}{{e}}. Strong interaction effects are taken into account by a microscopic study based on the solution of G-matrix and T-matrix equations for the initial and final interacting pairs respectively. Results for the decay induced by {{Λ }}{{Λ }}\\to {{Λ }}N({{Σ }}N) transitions are given.

Wire perturbations in the Staffman-Taylor problem

NASA Technical Reports Server (NTRS)

Hong, D. C.

1988-01-01

Zocchi et al. (1987) discovered that when two wires are symmetrically placed along the center of a Hele-Shaw cell, symmetric but narrow fingers of dimensionless width lambda less than 0.5 develop. The value of lambda decreases as the pushing velocity increases, but at a certain critical finger width the finger suddenly undergoes a transition to the asymmetrical state. A simple theory to predict this critical finger width as a function of D, the dimensionless distance between two wires is developed by assuming that the finger opens up a negative angle at the contact point.

The extended atmosphere of Lambda Pavonis at the time of the emergence of H-emissions from minimum intensity

NASA Technical Reports Server (NTRS)

Sahade, Jorge; Rovira, Marta; Ringuelet, Adela E.; Kondo, Yoji; Cidale, Lydia

1988-01-01

A study of the Be star Lambda Pavonis, particularly of the changes in the Balmer discontinuity in the interval 1949-1982, is presented. Nearly simultaneous observations carried out with the ESO 1.5 m reflector at La Silla and with the IUE satellite correspond to an epoch when the H emission is starting to increase intensity immediately after having reached its minimum strength. These observations suggest the presence of four distinct regions of line formation, with the material moving outward in the transition region.

Fine wavelength id for tunable laser local oscillators. [sensing the absorption emission spectra of atmospheric gases

NASA Technical Reports Server (NTRS)

Savage, M. G.; Augeri, R. C.

1980-01-01

A wavelength ID device which consists of an electronic show that the etalon has a finesse F 30 which is maintainable for several days. These tests also demonstrate that the etalon system is capable of resonance frequency stability during similar time periods. With currently available coatings, this level of performance is achievable over an optical bandwidth delta lambda = 3 micrometers centered at lambda = 10 micrometers.

TIBePO4 : un nouveau phosphate ferroélectrique

NASA Astrophysics Data System (ADS)

Wallez, G.; Jaulmes, S.; Elfakir, A.; Quarton, M.

1994-07-01

The thallium-beryllium monophosphate is related to the β-SiO2 tridymite structural kind. The phase II, stable at room temperature, is found to have orthorhombic symmetry mm2. It sustains a displacive transformation at 919 ^{circ}C leading to centric phase I with symmetry mmm. In the low-temperature form, the 6s^2 electron pair of TI+ cation is oriented along polar axis, inducing a significant distortion of the oxygen framework ; the ferroelectric nature of phase II is pointed out by the strong increase of the dielectric stiffness around Curie temperature. Phase transition results of bound rotations of PO4 and BeO4 tetrahedra, the rise of symmetry order leading to the loss of hybridization of the lone pair. According to the displacive transition mechanism, both thermal and dielectric properties show typical second order features. L'orthophosphate de thallium-béryllium cristallise selon le type structural " tridymite β-SiO2 déformée ". La phase II, stable à l'ambiante, présente une symétrie orthorhombique mm2 ; elle subit une transformation displacive à 919 ^circC vers la forme prototype I centrosymétrique (mmm). Dans la variété ferroélectrique, le doublet électronique 6s^2 de l'ion Tl^+, orienté selon l'axe polaire, provoque une importante déformation de la charpente oxygénée ; le caractère ferroélectrique est mis en évidence par le fort accroissement de la permittivité diélectrique au voisinage de la température de Curie. La transition procède par des rotations engrenées des tétraèdres PO4 et BeO4, l'accroissement de symétrie impliquant la déshybridation du doublet 6s^2. Observée sous ses aspects thermique et diélectrique, cette transition apparaît comme un phénomène du second ordre, conformément à son caractère displacif.

The formation of low-ionization emission in the halo of NGC 891

NASA Technical Reports Server (NTRS)

Sokolowski, James; Bland-Hawthorn, Jonathan

1993-01-01

Imaging and Spectroscopic study first revealed the presence of a diffuse ionized medium (DIM), having unusual excitation, pervading the lower halo of the edge-on spiral galaxy NGC 891. Emission from this DIM is strongest northeast of the nucleus, at radii between 2 and 8 kpc (hereafter region 1). The (N2)(lambda)6583/H(alpha) and (S2)(lambda) (lambda)6716,6731/H(alpha) ratios increase dramatically with z in region 1, from 0.6 and 0.5 respectively at z is approximately equal to 500 pc to 1.1 and 1.0 at z is approximately equal to 1 kpc, while nondetections of (O1)(lambda)6300 and (O3)(lambda)5007 emission yield upper limits of (O1)(lambda)6300/H(alpha) less than or equal to 0.05 and (O3)(lambda)5007/H(alpha) less than or equal to 0.15 for z less than 1 kpc. Previous photoionization models, using the radiation field from disk O and B stars, have been successful in reproducing the elevated (N2)(lambda)6583/H(alpha) and (S2)(lambda)(lambda)6716.6731/H(alpha) ratios observed. However, these radiation bounded models also produce significant (O3)(lambda)5007 emission, in conflict with the observed upper limit. Here, we report the results of new, matter bounded models for the photoionization of the DIM in region 1 of NGC 891.

Correlation Measurement of Lambda-anti-Lambda, Lambda-Lambda and anti-Lambda-anti-Lambda with the ATLAS detector at s=7 TeV

NASA Astrophysics Data System (ADS)

Cheng, Hok-Chuen

This thesis summaries the measurements of correlations between Lambda 0Lambda0, Lambda0Lambda 0, and Lambda0Lambda 0 hyperon pairs produced inclusively at the LHC, which are useful for a better understanding of the quark-antiquark pair production and jet fragmentation and hadronization processes. The analysis is based on hyperon pairs selected using the muon and minimum bias data samples collected at the ATLAS experiment from proton-proton collisions at a center-of-mass energy of 7 TeV in 2010. Excess Lambda0Lambda 0 are observed near the production threshold and are identified to be originated from the parton system in the string model in the MC sample, decaying either directly or through heavy strange resonances such as Sigma0 and Sigma*(1385). Dynamical correlations have been explored through a correlation function defined as the ratio of two-particle to single-particle densities. Positive correlation is observed for Lambda0Lambda0 and anticorrelation is observed for Lambda0Lambda 0 and Lambda0Lambda 0 for Q in [0,2] GeV. The structure replicates similar correlations in pp, pp, and pppp events in PYTHIA generator as predicted by the Lund string fragmentation model. Parameters of the "popcorn" mechanism implemented in the PYTHIA generator are tuned and are found to have little impact on the structure observed. The spin composition of the sample is extracted using a data-driven reference sample built by event mixing. Appropriate corrections have been made to the kinematic distributions in the reference sample by kinematic weighting to make sure that the detector effects are well modeled. A modified Pearson's chi2 test statistics is calculated for the costheta* distribution to determine the best-fitted A-value for data. The results are consistent with zero for both like-type and unlike-type hyperon pairs in Q ∈ [0,10] GeV and Q ∈ [1,10] GeV respectively. The data statistics in the range of Q ∈ [0, 1] GeV is currently too low for the estimation of the emitter size for Fermi-Dirac correlation.

Radiative lifetimes in B I using ultraviolet and vacuum-ultraviolet laser-induced fluorescence

NASA Technical Reports Server (NTRS)

O'Brian, T. R.; Lawler, J. E.

1992-01-01

Radiative lifetimes of the eight lowest even parity levels in the doublet system of B I are measured using time-resolved laser-induced fluorescence in the UV and VUV on an atomic beam of boron. The accurate lifetimes provide a base for improved determination of absolute transition probabilities in B I. The techniques described are broadly applicable to measurement of lifetimes of levels with transitions in the visible, UV, and VUV in almost any element.

Non-LTE line-blanketed model atmospheres of hot stars. 1: Hybrid complete linearization/accelerated lambda iteration method

NASA Technical Reports Server (NTRS)

Hubeny, I.; Lanz, T.

1995-01-01

A new munerical method for computing non-Local Thermodynamic Equilibrium (non-LTE) model stellar atmospheres is presented. The method, called the hybird complete linearization/accelerated lambda iretation (CL/ALI) method, combines advantages of both its constituents. Its rate of convergence is virtually as high as for the standard CL method, while the computer time per iteration is almost as low as for the standard ALI method. The method is formulated as the standard complete lineariation, the only difference being that the radiation intensity at selected frequency points is not explicity linearized; instead, it is treated by means of the ALI approach. The scheme offers a wide spectrum of options, ranging from the full CL to the full ALI method. We deonstrate that the method works optimally if the majority of frequency points are treated in the ALI mode, while the radiation intensity at a few (typically two to 30) frequency points is explicity linearized. We show how this method can be applied to calculate metal line-blanketed non-LTE model atmospheres, by using the idea of 'superlevels' and 'superlines' introduced originally by Anderson (1989). We calculate several illustrative models taking into accont several tens of thosands of lines of Fe III to Fe IV and show that the hybrid CL/ALI method provides a robust method for calculating non-LTE line-blanketed model atmospheres for a wide range of stellar parameters. The results for individual stellar types will be presented in subsequent papers in this series.

The effect of low-frequency oscillations on cardio-respiratory synchronization. Observations during rest and exercise

NASA Astrophysics Data System (ADS)

Kenwright, D. A.; Bahraminasab, A.; Stefanovska, A.; McClintock, P. V. E.

2008-10-01

We show that the transitions which occur between close orders of synchronization in the cardiorespiratory system are mainly due to modulation of the cardiac and respiratory processes by low-frequency components. The experimental evidence is derived from recordings on healthy subjects at rest and during exercise. Exercise acts as a perturbation of the system that alters the mean cardiac and respiratory frequencies and changes the amount of their modulation by low-frequency oscillations. The conclusion is supported by numerical evidence based on a model of phase-coupled oscillators, with white noise and lowfrequency noise. Both the experimental and numerical approaches confirm that low-frequency oscillations play a significant role in the transitional behavior between close orders of synchronization.

Spatial and temporal trends in fin whale vocalizations recorded in the NE Pacific Ocean between 2003-2013

PubMed Central

Weirathmueller, Michelle J.; Stafford, Kathleen M.; Wilcock, William S. D.; Hilmo, Rose S.; Dziak, Robert P.; Tréhu, Anne M.

2017-01-01

In order to study the long-term stability of fin whale (Balaenoptera physalus) singing behavior, the frequency and inter-pulse interval of fin whale 20 Hz vocalizations were observed over 10 years from 2003–2013 from bottom mounted hydrophones and seismometers in the northeast Pacific Ocean. The instrument locations extended from 40°N to 48°N and 130°W to 125°W with water depths ranging from 1500–4000 m. The inter-pulse interval (IPI) of fin whale song sequences was observed to increase at a rate of 0.54 seconds/year over the decade of observation. During the same time period, peak frequency decreased at a rate of 0.17 Hz/year. Two primary call patterns were observed. During the earlier years, the more commonly observed pattern had a single frequency and single IPI. In later years, a doublet pattern emerged, with two dominant frequencies and IPIs. Many call sequences in the intervening years appeared to represent a transitional state between the two patterns. The overall trend was consistent across the entire geographical span, although some regional differences exist. Understanding changes in acoustic behavior over long time periods is needed to help establish whether acoustic characteristics can be used to help determine population identity in a widely distributed, difficult to study species such as the fin whale. PMID:29073230

Spatial and temporal trends in fin whale vocalizations recorded in the NE Pacific Ocean between 2003-2013.

PubMed

Weirathmueller, Michelle J; Stafford, Kathleen M; Wilcock, William S D; Hilmo, Rose S; Dziak, Robert P; Tréhu, Anne M

2017-01-01

In order to study the long-term stability of fin whale (Balaenoptera physalus) singing behavior, the frequency and inter-pulse interval of fin whale 20 Hz vocalizations were observed over 10 years from 2003-2013 from bottom mounted hydrophones and seismometers in the northeast Pacific Ocean. The instrument locations extended from 40°N to 48°N and 130°W to 125°W with water depths ranging from 1500-4000 m. The inter-pulse interval (IPI) of fin whale song sequences was observed to increase at a rate of 0.54 seconds/year over the decade of observation. During the same time period, peak frequency decreased at a rate of 0.17 Hz/year. Two primary call patterns were observed. During the earlier years, the more commonly observed pattern had a single frequency and single IPI. In later years, a doublet pattern emerged, with two dominant frequencies and IPIs. Many call sequences in the intervening years appeared to represent a transitional state between the two patterns. The overall trend was consistent across the entire geographical span, although some regional differences exist. Understanding changes in acoustic behavior over long time periods is needed to help establish whether acoustic characteristics can be used to help determine population identity in a widely distributed, difficult to study species such as the fin whale.

Segregated tandem filter for enhanced conversion efficiency in a thermophotovoltaic energy conversion system

DOEpatents

Brown, Edward J.; Baldasaro, Paul F.; Dziendziel, Randolph J.

1997-01-01

A filter system to transmit short wavelength radiation and reflect long wavelength radiation for a thermophotovoltaic energy conversion cell comprises an optically transparent substrate segregation layer with at least one coherent wavelength in optical thickness; a dielectric interference filter deposited on one side of the substrate segregation layer, the interference filter being disposed toward the source of radiation, the interference filter including a plurality of alternating layers of high and low optical index materials adapted to change from transmitting to reflecting at a nominal wavelength .lambda..sub.IF approximately equal to the bandgap wavelength .lambda..sub.g of the thermophotovoltaic cell, the interference filter being adapted to transmit incident radiation from about 0.5.lambda..sub.IF to .lambda..sub.IF and reflect from .lambda..sub.IF to about 2.lambda..sub.IF ; and a high mobility plasma filter deposited on the opposite side of the substrate segregation layer, the plasma filter being adapted to start to become reflecting at a wavelength of about 1.5.lambda..sub.IF.

Somatic diversification of chicken immunoglobulin light chains by point mutations.

PubMed

Parvari, R; Ziv, E; Lantner, F; Heller, D; Schechter, I

1990-04-01

The light-chain locus of chicken has 1 functional V lambda 1 gene, 1 J gene, and 25 pseudo-V lambda-genes (where V = variable and J = joining). A major problem is which somatic mechanisms expand this extremely limited germ-line information to generate many different antibodies. Weill's group [Reynaud, C. A., Anquez, V., Grimal, H. & Weill, J. C. (1987) Cell 48, 379-388] has shown that the pseudo-V lambda-genes diversify the rearranged V lambda 1 by gene conversion. Here we demonstrate that chicken light chains are further diversified by somatic point mutations and by V lambda 1-J flexible joining. Somatic point mutations were identified in the J and 3' noncoding DNA of rearranged light-chain genes of chicken. These regions were analyzed because point mutations in V lambda 1 are obscured by gene conversion; the J and 3' noncoding DNA are presented in one copy per haploid genome and are not subject to gene conversion. In rodents point mutations occur as frequently in the V-J coding regions as in the adjacent flanking DNA. Therefore, we conclude that somatic point mutations diversify the V lambda 1 of chicken. The frequency (0-1%) and distribution of the mutations (decreasing in number with increased distance from the V lambda 1 segment) in chicken were as observed in rodents. Sequence variability at the V lambda 1-J junctions could be attributed to imprecise joining of the V lambda 1 and J genes. The modification by gene conversion of rearranged V lambda 1 genes in the bursa was similar in chicken aged 3 months (9.5%) or 3 weeks (9.1%)--i.e., gene conversion that generates the preimmune repertoire in the bursa seems to level off around 3 weeks of age. This preimmune repertoire can be further diversified by somatic point mutations that presumably lead to the formation of antibodies with increased affinity. A segment with structural features of a matrix association region [(A + T)-rich and four topoisomerase II binding sites] was identified in the middle of the J-C lambda intron (where C = constant).

The electronic structure of vanadium monochloride cation (VCl+): Tackling the complexities of transition metal species

NASA Astrophysics Data System (ADS)

DeYonker, Nathan J.; Halfen, DeWayne T.; Allen, Wesley D.; Ziurys, Lucy M.

2014-11-01

Six electronic states (X 4Σ-, A 4Π, B 4Δ, 2Φ, 2Δ, 2Σ+) of the vanadium monochloride cation (VCl+) are described using large basis set coupled cluster theory. For the two lowest quartet states (X 4Σ- and A 4Π), a focal point analysis (FPA) approach was used that conjoined a correlation-consistent family of basis sets up to aug-cc-pwCV5Z-DK with high-order coupled cluster theory through pentuple (CCSDTQP) excitations. FPA adiabatic excitation energies (T0) and spectroscopic constants (re, r0, Be, B0, bar De, He, ωe, v0, αe, ωexe) were extrapolated to the valence complete basis set Douglas-Kroll (DK) aug-cc-pV∞Z-DK CCSDT level of theory, and additional treatments accounted for higher-order valence electron correlation, core correlation, and spin-orbit coupling. Due to the delicate interplay between dynamical and static electronic correlation, single reference coupled cluster theory is able to provide the correct ground electronic state (X 4Σ-), while multireference configuration interaction theory cannot. Perturbations from the first- and second-order spin orbit coupling of low-lying states with quartet spin multiplicity reveal an immensely complex rotational spectrum relative to the isovalent species VO, VS, and TiCl. Computational data on the doublet manifold suggest that the lowest-lying doublet state (2Γ) has a Te of ˜11 200 cm-1. Overall, this study shows that laboratory and theoretical rotational spectroscopists must work more closely in tandem to better understand the bonding and structure of molecules containing transition metals.

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

Sanchis-Ojeda, Roberto; Winn, Joshua N.; Carter, Joshua A.

We present photometry of four transits of the exoplanet WASP-4b, each with a precision of approximately 500 ppm and a time sampling of 40-60 s. We have used the data to refine the estimates of the system parameters and ephemerides. During two of the transits we observed a short-lived, low-amplitude anomaly that we interpret as the occultation of a starspot by the planet. We also found evidence for a pair of similar anomalies in previously published photometry. The recurrence of these anomalies suggests that the stellar rotation axis is nearly aligned with the orbital axis, or else the starspot wouldmore » not have remained on the transit chord. By analyzing the timings of the anomalies we find the sky-projected stellar obliquity to be {lambda} = -1{sup +14}{sub -12} degrees. This result is consistent with (and more constraining than) a recent observation of the Rossiter-McLaughlin effect. It suggests that the planet migration mechanism preserved the initially low obliquity, or else that tidal evolution has realigned the system. Future applications of this method using data from the CoRoT and Kepler missions will allow spin-orbit alignment to be probed for many other exoplanets.« less

Carrier Envelope Phase Effect of a Long Duration Pulse in the Low Frequency Region

NASA Astrophysics Data System (ADS)

Zhao, Xi; Yang, Yu-Jun; Liu, Xue-Shen; Wang, Bing-Bing

2014-04-01

Using the characteristic of small energy difference between two high Rydberg states, we theoretically investigate the carrier envelope phase (CEP) effect in a bound-bound transition of an atom in a low-frequency long laser pulse with tens of optical cycles. Particularly, we first prepare a Rydberg state of a hydrogen-like atom by a laser field with the resonant frequency between this state and the ground state. Then by using a low-frequency long laser pulse interacting with this Rydberg atom, we calculate the population of another Rydberg state nearby this Rydberg state at the end of the laser pulse and find that the population changes dramatically with the CEP of the low-frequency pulse. This CEP effect is attributed to the interference between the positive-frequency and negative-frequency components in one-photon transition. These results may provide a method to measure the CEP value of a long laser pulse with low frequency.

Electronic structure and quantum spin fluctuations at the magnetic phase transition in MnSi

NASA Astrophysics Data System (ADS)

Povzner, A. A.; Volkov, A. G.; Nogovitsyna, T. A.

2018-05-01

The effect of spin fluctuations on the heat capacity and homogeneous magnetic susceptibility of the chiral magnetic MnSi in the vicinity of magnetic transition has been investigated by using the free energy functional of the coupled electron and spin subsystems and taking into account the Dzyaloshinsky-Moriya interaction. For helical ferromagnetic ordering, we found that zero-point fluctuations of the spin density are large and comparable with fluctuations of the non-uniform magnetization. The amplitude of zero-point spin fluctuations shows a sharp decrease in the region of the magnetic phase transition. It is shown that sharp decrease of the amplitude of the quantum spin fluctuations results in the lambda-like maxima of the heat capacity and the homogeneous magnetic susceptibility. Above the temperature of the lambda anomaly, the spin correlation radius becomes less than the period of the helical structure and chiral fluctuations of the local magnetization appear. It is shown that formation of a "shoulder" on the temperature dependence of the heat capacity is due to disappearance of the local magnetization. Our finding allows to explain the experimentally observed features of the magnetic phase transition of MnSi as a result of the crossover of quantum and thermodynamic phase transitions.

An assessment of bird habitat quality using population growth rates

USGS Publications Warehouse

Knutson, M.G.; Powell, L.A.; Hines, R.K.; Friberg, M.A.; Niemi, G.J.

2006-01-01

Survival and reproduction directly affect population growth rate (lambda) making lambda a fundamental parameter for assessing habitat quality. We used field data, literature review, and a computer simulation to predict annual productivity and lambda for several species of landbirds breeding in floodplain and upland forests in the Midwestern United States. We monitored 1735 nests of 27 species; 760 nests were in the uplands and 975 were in the floodplain. Each type of forest habitat (upland and floodplain) was a source habitat for some species. Despite a relatively low proportion of regional forest cover, the majority of species had stable or increasing populations in all or some habitats, including six species of conservation concern. In our search for a simple analog for lambda, we found that only adult apparent survival, juvenile survival, and annual productivity were correlated with lambda; daily nest survival and relative abundance estimated from point counts were not. Survival and annual productivity are among the most costly demographic parameters to measure and there does not seem to be a low-cost alternative. In addition, our literature search revealed that the demographic parameters needed to model annual productivity and lambda were unavailable for several species. More collective effort across North America is needed to fill the gaps in our knowledge of demographic parameters necessary to model both annual productivity and lambda. Managers can use habitat-specific predictions of annual productivity to compare habitat quality among species and habitats for purposes of evaluating management plans.

Safety and Efficacy of Pegylated Interferon Lambda, Ribavirin, and Daclatasvir in HCV and HIV-Coinfected Patients.

PubMed

Nelson, Mark; Rubio, Rafael; Lazzarin, Adriano; Romanova, Svetlana; Luetkemeyer, Annie; Conway, Brian; Molina, Jean-Michel; Xu, Dong; Srinivasan, Subasree; Portsmouth, Simon

2017-03-01

To evaluate the efficacy and safety of pegylated interferon-lambda-1a (Lambda)/ribavirin (RBV)/daclatasvir (DCV) for treatment of patients coinfected with chronic hepatitis C virus (HCV) and human immunodeficiency virus (HIV). Treatment-naive patients were assigned to cohort A [HCV genotype (GT)-2 or -3] or cohort B [HCV GT-1(a or b) or -4]. All patients received Lambda/RBV/DCV for the first 12 weeks; cohort A received Lambda/RBV for an additional 12 weeks, followed by 24 weeks of follow-up, and cohort B received response-guided therapy. The primary endpoint was the proportion of patients who achieved a sustained virologic response at post-treatment week 12 (SVR12). In cohort A (n = 104), 84.6% achieved SVR12 (95.0% in GT-2; 83.1% in GT-3). In cohort B (n = 196), 76.0% achieved SVR12 (71.7% in GT-1a; 86.0% in GT-1b; 70.7% in GT-4). Rates of discontinuation due to adverse events (AEs) (3.8% and 6.1%) and serious AEs (5.8% and 6.1%) were low in cohorts A and B, respectively. In addition, treatment with Lambda/RBV/DCV had little impact on CD4 counts. SVR12 rates with Lambda/RBV/DCV in an HCV/HIV-coinfected population ranged from 71.7% to 95.0%. Treatment was generally well tolerated, with a low proportion of patients discontinuing due to AEs. Clinical trial registration NCT01866930.

New primordial-magnetic-field limit from the latest LIGO S5 data

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

Wang, S.

Since the energy momentum tensor of a magnetic field always contains a spin-2 component in its anisotropic stress, stochastic primordial magnetic field (PMF) in the early universe must generate stochastic gravitational-wave (GW) background. This process will greatly affect the relic gravitational wave (RGW), which is one of the major scientific goals of the laser interferometer GW detections. Recently, the fifth science (S5) run of laser interferometer gravitational-wave observatory (LIGO) gave a latest upper limit {Omega}{sub GW}<6.9x10{sup -6} on the RGW background. Utilizing this upper limit, we derive new PMF limits: for a scale of galactic cluster {lambda}=1 Mpc, the amplitudemore » of PMF, that produced by the electroweak phase transition, has to be weaker than B{sub {lambda}{<=}4}x10{sup -7} G; for a scale of supercluster {lambda}=100 Mpc, the amplitude of PMF has to be weaker than B{sub {lambda}{<=}9}x10{sup -11} G. In this manner, GW observation has potential to make interesting contributions to the study of primordial magnetic field.« less

Photographic Combustion Characterization of LOX/Hydrocarbon Type Propellants

NASA Technical Reports Server (NTRS)

Judd, D. C.

1980-01-01

The advantages and limitations of using high speed photography to identify potential combustion anomalies (pops, fuel freezing, reactive stream separation (RSS), carbon formation) were demonstrated. Combustion evaluation criteria were developed for evaluating, characterizing, and screening promising low cost propellant combination(s) and injector element(s) for long life, reusable engine systems. Carbon formation and RSS mechanisms and trends were identified by using high speed color photography at speeds up to 6000 frames/sec. Single element injectors were tested with LOX/RP-1, LOX/Propane, LOX/Methane and LOX/Ammonia propellants. Tests were conducted using seven separate injector elements. Five different conventionally machined elements were tested: OFO Triplet; Rectangular Unlike Doublet (RUD); Unlike Doublet (UD); Like on Lke Doublet (LOL-EDM); and Slit Triplet.

Dynamics of neutrophil aggregation in couette flow revealed by videomicroscopy: effect of shear rate on two-body collision efficiency and doublet lifetime.

PubMed Central

Goldsmith, H L; Quinn, T A; Drury, G; Spanos, C; McIntosh, F A; Simon, S I

2001-01-01

During inflammation, neutrophil capture by vascular endothelial cells is dependent on L-selectin and beta(2)-integrin adhesion receptors. One of us (S.I.S.) previously demonstrated that homotypic neutrophil aggregation is analogous to this process in that it is also mediated by these receptors, thus providing a model for studying the dynamics of neutrophil adhesion. In the present work, we set out to confirm the hypothesis that cell-cell adhesion via selectins serves to increase the lifetimes of neutrophil doublets formed through shear-induced two-body collisions. In turn, this would facilitate the engagement of more stable beta(2)-integrin bonds and thus increase the two-body collision efficiency (fraction of collisions resulting in the formation of nonseparating doublets). To this end, suspensions of unstimulated neutrophils were subjected to a uniform shear field in a transparent counter-rotating cone and plate rheoscope, and the formation of doublets and growth of aggregates recorded using high-speed videomicroscopy. The dependence of neutrophil doublet lifetime and two-body collision-capture efficiency on shear rate, G, from 14 to 220 s(-1) was investigated. Bond formation during a two-body collision was indicated by doublets rotating well past the orientation predicted for break-up of doublets of inert spheres. A striking dependence of doublet lifetime on shear rate was observed. At low shear (G = 14 s(-1)), no collision capture occurred, and doublet lifetimes were no different from those of neutrophils pretreated with a blocking antibody to L-selectin, or in Ca(++)-depleted EDTA buffers. At G > or = 66 s(-1), doublet lifetimes increased, with increasing G reaching values twice those for the L-selectin-blocked controls. This correlated with capture efficiencies in excess of 20%, and, at G > or = 110 s(-1), led to the rapid formation of large aggregates, and this in the absence of exogenous chemotactic stimuli. Moreover, the aggregates almost completely broke up when the shear rate was reduced below 66 s(-1). Partial inhibition of aggregate formation was achieved by blocking beta(2)-integrin receptors with antibody. By direct observation of the shear-induced interactions between neutrophils, these data reveal that steady application of a threshold level of shear rate is sufficient to support homotypic neutrophil aggregation. PMID:11566775

Dynamic conductivity from audio to optical frequencies of semiconducting manganites approaching the metal-insulator transition

NASA Astrophysics Data System (ADS)

Lunkenheimer, P.; Mayr, F.; Loidl, A.

2006-07-01

We report the frequency-dependent conductivity of the manganite system La1-xSrxMnO3 (x0.2) when approaching the metal-insulator transition from the insulating side. Results from low-frequency dielectric measurements are combined with spectra in the infrared region. For low doping levels the behavior is dominated by hopping transport of localized charge carriers at low frequencies and by phononic and electronic excitations in the infrared region. For the higher Sr contents the approach of the metallic state is accompanied by the successive suppression of the hopping contribution at low frequencies and by the development of polaronic excitations in the infrared region, which finally become superimposed by a strong Drude contribution in the fully metallic state.

Hyperfine Induced Transitions as Diagnostics of Low Density Plasmas and Isotopic Abundance ratios.

NASA Astrophysics Data System (ADS)

Brage, T.; Judge, P. G.; Aboussaid, A.; Godefroid, M. R.; Jonsson, P.; Leckrone, D. S.

1996-05-01

We propose a new diagnostics of isotope abundance ratios and electron densities for low density plasmas, in the form of J = 0 -> J(') = 0 radiative transitions. These are usually viewed as being allowed only through two-photon decay, but they may also be induced by the hyperfine (HPF) interaction in atomic ions. This predicts a companion line to the E1] and M2 lines in the UV0.01 multiplet of ions isoelectronic to beryllium (e.g. C III, N IV, O V and Fe XXII) or magnesium (e.g. Si II, Ca IX, Fe XV and Ni XVII). As an example the companion line to the well known lambda lambda 1906.7,1908.7 lines in C III will be at 1909.597 Angstroms, but only present in the (13) C isotope (which has nuclear spin different from zero). We present new and accurate decay rates for the nsnp (3P^oJ) -> ns(2) (1S_{J('}=0)) transitions in ions of the Be (n=2) and Mg (n=3) isoelectronic sequences. We show that the HPF induced decay rates for the J = 0 -> J(') = 0 transitions are many orders of magnitude larger than those for the competing two-photon processes and, when present, are typically one or two orders of magnitude smaller than the decay rates of the magnetic quadrupole ( J = 2-> J(') = 0) transitions for these ions. We show that several of these HPF-induced transitions are of potential astrophysical interest, in ions of C, N, Na, Mg, Al, Si, K, Cr, Fe and Ni. We highlight those cases that may be of particular diagnostic value for determining isotopic abundance ratios and/or electron densities from UV or EUV emission line data. We present our atomic data in the form of scaling laws so that, given the isotopic nuclear spin and magnetic moment, a simple expression yields estimates for HPF induced decay rates. We examine some UV solar and nebular data in the light of these new results and suggest possible cases for future study. We could not find evidence for the existence of HPF induced lines in the spectra we examined, but we demonstrate that existing data have come close to providing interesting upper limits. For the planetary nebula SMC N2 we derive an upper limit of (13) C/(12) C of 0.1 from GHRS data obtained by Clegg. It is likely that more stringent limits could be obtained with newer data with higher sensitivities in a variety of objects.

Interferometric apparatus for ultra-high precision displacement measurement

NASA Technical Reports Server (NTRS)

Zhao, Feng (Inventor)

2004-01-01

A high-precision heterodyne interferometer measures relative displacement by creating a thermally-insensitive system generally not subject to polarization leakage. By using first and second light beams separated by a small frequency difference (.DELTA.f), beams of light at the first frequency (f.sub.0) are reflected by co-axial mirrors, the first mirror of which has a central aperture through which the light is transmitted to and reflected by the second mirror. Prior to detection, the light beams from the two mirrors are combined with light of the second and slightly different frequency. The combined light beams are separated according to the light from the mirrors. The change in phase (.DELTA..phi.) with respect to the two signals is proportional to the change in distance of Fiducial B by a factor of wavelength (.lambda.) divided by 4.pi. (.DELTA.L=.lambda..DELTA..phi.1/(4.pi.)). In a second embodiment, a polarizing beam splitting system can be used.

Vortex Loops at the Superfluid Lambda Transition: An Exact Theory?

NASA Technical Reports Server (NTRS)

Williams, Gary A.

2003-01-01

A vortex-loop theory of the superfluid lambda transition has been developed over the last decade, with many results in agreement with experiments. It is a very simple theory, consisting of just three basic equations. When it was first proposed the main uncertainty in the theory was the use Flory scaling to find the fractal dimension of the random-walking vortex loops. Recent developments in high-resolution Monte Carlo simulations have now made it possible to verify the accuracy of this Flory-scaling assumption. Although the loop theory is not yet rigorously proven to be exact, the Monte Carlo results show at the least that it is an extremely good approximation. Recent loop calculations of the critical Casimir effect in helium films in the superfluid phase T < Tc will be compared with similar perturbative RG calculations in the normal phase T > Tc; the two calculations are found to match very nicely right at Tc.

Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+64. 3.1

NASA Technical Reports Server (NTRS)

Zheng, W.; Kriss, G. A.; Wang, J. X.; Brotherton, M.; Oegerle, W. R.; Blair, W. P.; Davidsen, A. F.; Green, R. F.; Hutchings, J. B.; Kaiser, M. E.;

Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+641. 2.5

NASA Technical Reports Server (NTRS)

Zheng, W.; Kriss, G. A.; Wang, J. X.; Brotherton, M.; Oegerle, W. R.; Blair, W. P.; Davidsen, A. F.; Green, R. F.; Hutchings, J. B.; Kaiser, M. E.;

The polarization and ultraviolet spectrum of Markarian 231

NASA Technical Reports Server (NTRS)

Smith, Paul S.; Schmidt, Gary D.; Allen, Richard G.; Angel, J. R. P.

1995-01-01

Ultraviolet spectropolarimetry acquired with the Hubble Space Telescope (HST) of the peculiar Seyfert galaxy Mrk 231 is combined with new high-quality ground-based measurements to provide the first, nearly complete, record of its linear polarization from 1575 to 7900 A. The accompanying ultraviolet spectrum portrays the heavily extinguished emission-line spectrum of the active nucleus plus the emergence of a blue continuum shortward of approximately 2400 A. In addition, absorption features due to He I lambda 3188, Mg I lambda 2853, Mg II lambda 2798, and especially several resonance multiplets of Fe II are identified with a well-known optical absorption system blueshifted approximately 4600 km/s with respect to emission lines. The continuum is attributed to approximately 10(exp 5) hot, young stars surrounding the nucleus. This component dilutes the polarized nuclear light, implying that the intrinsic polarization of the active galactic nucleus (AGN) spectrum approaches 20% at 2800 A. The rapid decline in degree of polarization toward longer wavelengths is best explained by the strongly frequency-dependent scattering cross section of dust grains coupled with modest starlight dilution. Peculiar S-shaped inflections in both the degree and position angle of polarization through H alpha and other major emission lines are interpreted as effects of scattering from two regions offset in velocity by several hundred km/s. A third source of (weakly) polarized flux is required to explain a nearly 40 deg rotation in position angle between 3200 and 1800 A. The displaced absorption features, polarimetry, and optical/infrared properties of Mrk 231 all point to its classification as a low-ionization, or Mg II broad absorption line quasar, in which most, if not all, lines of sight to the active nucleus are heavily obscured by dust and low-ionization gas clouds.

Exoplanetary Spin-Orbit Alignment: Results from the Ensemble of Rossiter-McLaughlin Measurements

NASA Technical Reports Server (NTRS)

Fabrycky, Daniel C.; Winn, Joshua N.

2009-01-01

One possible diagnostic of planet formation, orbital migration, and tidal evolution is the angle between a planet's orbital axis and the spin axis of its parent star. In general, Psi cannot be measured, but for transiting planets one can measure the angle lambda between the sky projections of the two axes via the Rossiter-McLaughlin effect. In this paper we showed how to combine measurements of lambda in different systems to derive statistical constraints on Psi, using a Bayesian analysis. The results provided evidence for two distinct modes of planet migration.

Segregated tandem filter for enhanced conversion efficiency in a thermophotovoltaic energy conversion system

DOEpatents

Brown, E.J.; Baldasaro, P.F.; Dziendziel, R.J.

1997-12-23

A filter system to transmit short wavelength radiation and reflect long wavelength radiation for a thermophotovoltaic energy conversion cell comprises an optically transparent substrate segregation layer with at least one coherent wavelength in optical thickness; a dielectric interference filter deposited on one side of the substrate segregation layer, the interference filter being disposed toward the source of radiation, the interference filter including a plurality of alternating layers of high and low optical index materials adapted to change from transmitting to reflecting at a nominal wavelength {lambda}{sub IF} approximately equal to the bandgap wavelength {lambda}{sub g} of the thermophotovoltaic cell, the interference filter being adapted to transmit incident radiation from about 0.5{lambda}{sub IF} to {lambda}{sub IF} and reflect from {lambda}{sub IF} to about 2{lambda}{sub IF}; and a high mobility plasma filter deposited on the opposite side of the substrate segregation layer, the plasma filter being adapted to start to become reflecting at a wavelength of about 1.5{lambda}{sub IF}. 10 figs.

Preliminary evaluation of the acute toxicity of cypermethrin and lambda-cyhalothrin to Channa Punctatus.

PubMed

Kumar, Amit; Sharma, Bechan; Pandey, Ravi Shankar

2007-12-01

In the present study, the acute toxicity of the pyrethroid pesticides, cypermethrin and lambda-cyhalothrin was conducted for a 96 h period using Channa punctatus. The LC(50) values of cypermethrin and lambda-cyhalothrin were found to be 0.4 mg/L and 7.92 mug/L, respectively. The lambda-cyhalothrin was found to be about 50 times more toxic to the fish than cypermethrin. The behavioral pattern of C. punctatus got severely altered in each group due to pesticide treatment. The results suggested that even at low concentrations, these pyrethroid compounds may exert toxic effects, markedly modifying their behavioral pattern.

DYF-1 Is Required for Assembly of the Axoneme in Tetrahymena thermophila▿ †

PubMed Central

Dave, Drashti; Wloga, Dorota; Sharma, Neeraj; Gaertig, Jacek

2009-01-01

In most cilia, the axoneme can be subdivided into three segments: proximal (the transition zone), middle (with outer doublet microtubules), and distal (with singlet extensions of outer doublet microtubules). How the functionally distinct segments of the axoneme are assembled and maintained is not well understood. DYF-1 is a highly conserved ciliary protein containing tetratricopeptide repeats. In Caenorhabditis elegans, DYF-1 is specifically needed for assembly of the distal segment (G. Ou, O. E. Blacque, J. J. Snow, M. R. Leroux, and J. M. Scholey. Nature. 436:583-587, 2005). We show that Tetrahymena cells lacking an ortholog of DYF-1, Dyf1p, can assemble only extremely short axoneme remnants that have structural defects of diverse natures, including the absence of central pair and outer doublet microtubules and incomplete or absent B tubules on the outer microtubules. Thus, in Tetrahymena, DYF-1 is needed for either assembly or stability of the entire axoneme. Our observations support the conserved function for DYF-1 in axoneme assembly or stability but also show that the consequences of loss of DYF-1 for axoneme segments are organism specific. PMID:19581442

Planck and the reionization of the universe

NASA Astrophysics Data System (ADS)

Crill, Brendan

2016-03-01

Planck is the third-generation satellite aimed at measuring the cosmic microwave background, a relic of the hot big bang. Planck's temperature and polarization maps of the millimeter-wave sky have constrained parameters of the standard lambda-CDM model of cosmology to incredible precision, and have provided constraints on inflation in the very early universe. Planck's all-sky survey of polarization in seven frequency bands can remove contamination from nearby Galactic emission and constrain the optical depth of the reionized Universe, giving insight into the properties of the earliest star formation. The final 2016 data release from Planck will include a refined optical depth measurement using the full sensitivity of both the High Frequency and Low Frequency instruments. I present the status of the reionization measurement and discuss future prospects for further measurements of the early Universe with the CMB from Planck and future space and suborbital platforms.

Ultraviolet interstellar linear polarization. 2: The wavelength dependence

NASA Technical Reports Server (NTRS)

Clayton, Geoffrey C.; Wolff, Michael J.; Allen, R. G.; Lupie, O. L.

1995-01-01

We present new ultraviolet (UV) polarimetry of the well-studied interstellar line of sight toward HD 204827 obtained with the Faint Object Spectrograph on Hubble Space Telescope. HD 204827 is of great interest because the dust along this line of sight has extremely low values of both lambda(sub max) and R(sub V). Its far-UV extinction is very large, reflecting its small R(sub V) value. In addition, we reexamine the entire sample of 14 interstellar lines of sight for which there are now UV polarization data. We find that the previously suggested relationship between lambda(sub max) and the wavelength dependence of the polarization in the UV is strongly supported by the data for this larger sample including HD 204827. Seven stars with lambda(sub max) greater than or equal to 0.54 micron agree well with an extrapolation of the Serkowski relation into the UV while seven stars with lambda(sub max) less than or equal to 0.53 micron show polarization in excess of the Serkowski extrapolation (super-Serkowski). However, the division of the observed lines of sight into Serkowski and super-Serkowski categories is artificial. In fact, the amount of polarization in the UV is correlated with a single parameter, lambda(sub max). This may indicate that there is a mean interstellar polarization law analogous to the mean interstellar extinction law of Cardelli, Calyton, & Mathis which is based on R(sub V). The data are consistent with a linear relationship between 1/lambda(sub max) and rho(UV)/rho(sub max) but more data are needed to define the functional form. We suggest that the Serkowski and super-Serkowski designations be replaced by high and low lambda(sub max) which are more physically descriptive. At the same time, we note that all seven super-Serkowski (low lambda(sub max)) stars lie in a relatively small region of the sky between l(sup II) = 90 deg - 150 deg and b = -5 deg - 15 deg. These stars all lie in or behind a spur of the local Orion spiral arm. Similarly, most of the Serkowski (high lambda(sub max) stars lie in or near the Scorpio-Centaurus OB Association. So lines of sight covering larger areas of the sky are needed to test the universality of the lambda(sub max)/UV polarization relationship. The recent discovery of warm dust near HD 197770 suggests the possibility that a mechanism other than the traditional alignment to the Galactic magnetic field may be invoked to explain its 2175 A polarization bump.

Ultrastructural localization of the C-terminus of the 43-kd dystrophin-associated glycoprotein and its relation to dystrophin in normal murine skeletal myofiber.

PubMed Central

Wakayama, Y.; Shibuya, S.; Takeda, A.; Jimi, T.; Nakamura, Y.; Oniki, H.

1995-01-01

We used single and double immunogold labeling electron microscopy to investigate ultrastructural localization of the C terminus of the 43-kd dystrophin-associated glycoprotein (43-DAG) and its relationship to dystrophin in normal murine skeletal myofibers. Single immunolabeling localized the antibody against the C terminus of 43-DAG to the inside surface of the muscle plasma membrane and the sarcoplasmic side of plasma membrane invaginations. Double immunolabeling co-localized antibodies against dystrophin and the C terminus of 43-DAG to the same site noted in the single immunolabeling localization of 43-DAG. In particular, dystrophin and the C-terminal 43-DAG antibody signals were often observed as doublets separated by less than 30 nm. We compared these results with those obtained from double immunogold labeling with anti-dystrophin and anti-beta-spectrin, as well as anti-C-terminal 43-DAG and anti-beta-spectrin antibodies. The antibodies against dystrophin and beta-spectrin, or beta-spectrin and 43-DAG, also co-localized to similar sites in skeletal muscle fibers. Signals of doublet formations were noted but their frequency was significantly lower than the doublet frequency of antidystrophin and anti-43-DAG antibodies. The results support the presence of dystrophin and 43-DAG linkage at the inside surface of the murine skeletal muscle plasma membrane. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 PMID:7856727

Nonstationary plasma-thermo-fluid dynamics and transition in processes of deep penetration laser beam-matter interaction

NASA Astrophysics Data System (ADS)

Golubev, Vladimir S.; Banishev, Alexander F.; Azharonok, V. V.; Zabelin, Alexandre M.

1994-09-01

A qualitative analysis of the role of some hydrodynamic flows and instabilities by the process of laser beam-metal sample deep penetration interaction is presented. The forces of vapor pressure, melt surface tension and thermocapillary forces can determined a number of oscillatory and nonstationary phenomena in keyhole and weld pool. Dynamics of keyhole formation in metal plates has been studied under laser beam pulse effect ((lambda) equals 1.06 micrometers ). Velocities of the keyhole bottom motion have been determined at 0.5 X 105 - 106 W/cm2 laser power densities. Oscillatory regime of plate break- down has been found out. Small-dimensional structures with d-(lambda) period was found on the frozen cavity walls, which, in our opinion, can contribute significantly to laser beam absorption. A new form of periodic structure on the frozen pattern being a helix-shaped modulation of the keyhole walls and bottom relief has been revealed. Temperature oscillations related to capillary oscillations in the melt layer were discovered in the cavity. Interaction of the CW CO2 laser beam and the matter by beam penetration into a moving metal sample has been studied. The pulsed and thermodynamic parameters of the surface plasma were investigated by optical and spectroscopic methods. The frequencies of plasma jets pulsations (in 10 - 105 Hz range) are related to possible melt surface instabilities of the keyhole.

Exploring graphene superlattices: Magneto-optical properties

NASA Astrophysics Data System (ADS)

Duque, C. A.; Hernández-Bertrán, M. A.; Morales, A. L.; de Dios-Leyva, M.

2017-02-01

We present a detailed study of magnetic subbands, wave functions, and transition strengths for graphene superlattices (SLs) subject to a perpendicular magnetic field. It is shown that, for a weak magnetic field, the flat subbands of a SL exhibiting extra Dirac points are grouped into subsets, each of which consists of a singlet subband and a nearly degenerate doublet subband, and one nearly degenerate triplet subband. It was found that the wave functions corresponding to a singlet or to a doublet are always located around the image in real space of the central or extra Dirac points in k-space. The latter properties were explained by assuming that the electron motion is quasi-classical. Our study revealed that, for an intermediate field, the general characteristics of the wave functions are very similar to those of the pristine graphene, while for weak field, their behavior is drastically different. The latter is characterized by rapid oscillations which were understood using the solutions provided by the formalism of Luttinger-Kohn. The study on transition strengths allows us to obtain, for SLs with extra Dirac points in a weak magnetic field and different polarizations, the conditions under which transitions between multiplets are approximately allowed. It was shown that these conditions correspond to an unusual selection rule that is broken when the magnetic field intensity increases from weak to an intermediate value.

Exposure and health assessment during application of lambda-cyhalothrin for malaria vector control in Pakistan.

PubMed

Chester, G; Sabapathy, N N; Woollen, B H

1992-01-01

Icon 10 WP insecticide, a wettable powder formulation containing 10% lambda-cyhalothrin, was evaluated for possible adverse effects on the health of spraymen and villagers during treatment of dwellings for malaria vector control. Skin sensory effects and occasional coughing and sneezing in confined spaces were the only symptoms noted by the workers resulting from the handling and spraying of the insecticide. Absorption of lambda-cyhalothrin was estimated by determining its metabolites in urine and serum. The average amount of lambda-cyhalothrin absorbed by the workers per day (54 micrograms) represents less than 0.0001% (< 1 micrograms.kg-1.day-1) of the average daily amount of the substance handled. Only a small proportion of villagers showed detectable levels of lambda-cyhalothrin metabolites in their urine. Absorption of lambda-cyhalothrin from the formulation tested was therefore very low and, apart from the nuisance of skin sensory effects, there should be no risk to the health of workers or to the villagers whose dwellings are treated.

Exposure and health assessment during application of lambda-cyhalothrin for malaria vector control in Pakistan.

PubMed Central

Chester, G.; Sabapathy, N. N.; Woollen, B. H.

1992-01-01

Icon 10 WP insecticide, a wettable powder formulation containing 10% lambda-cyhalothrin, was evaluated for possible adverse effects on the health of spraymen and villagers during treatment of dwellings for malaria vector control. Skin sensory effects and occasional coughing and sneezing in confined spaces were the only symptoms noted by the workers resulting from the handling and spraying of the insecticide. Absorption of lambda-cyhalothrin was estimated by determining its metabolites in urine and serum. The average amount of lambda-cyhalothrin absorbed by the workers per day (54 micrograms) represents less than 0.0001% (< 1 micrograms.kg-1.day-1) of the average daily amount of the substance handled. Only a small proportion of villagers showed detectable levels of lambda-cyhalothrin metabolites in their urine. Absorption of lambda-cyhalothrin from the formulation tested was therefore very low and, apart from the nuisance of skin sensory effects, there should be no risk to the health of workers or to the villagers whose dwellings are treated. PMID:1464147

Two-dimensional energy spectra in high-Reynolds-number turbulent boundary layers

NASA Astrophysics Data System (ADS)

Chandran, Dileep; Baidya, Rio; Monty, Jason P.; Marusic, Ivan

2017-09-01

Here we report the measurements of two-dimensional (2-D) spectra of the streamwise velocity ($u$) in a high Reynolds number turbulent boundary layer. A novel experiment employing multiple hot-wire probes was carried out at friction Reynolds numbers ranging from 2400 to 26000. Taylor's frozen turbulence hypothesis is used to convert temporal-spanwise information into a 2-D spatial spectrum which shows the contribution of streamwise ($\\lambda_x$) and spanwise ($\\lambda_y$) length scales to the streamwise variance at a given wall height ($z$). At low Reynolds numbers, the shape of the 2-D spectra at a constant energy level shows $\\lambda_y/z \\sim (\\lambda_x/z)^{1/2}$ behaviour at larger scales, which is in agreement with the existing literature at a matched Reynolds number obtained from direct numerical simulations. However, at high Reynolds numbers, it is observed that the square-root relationship tends towards a linear relationship ($\\lambda_y \\sim \\lambda_x$) as required for self-similarity and predicted by the attached eddy hypothesis.

A NOVEL EMISSION SPECTRUM FROM A RELATIVISTIC ELECTRON MOVING IN A RANDOM MAGNETIC FIELD

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

Teraki, Yuto; Takahara, Fumio, E-mail: teraki@vega.ess.sci.osaka-u.ac.jp

2011-07-10

We numerically calculate the radiation spectrum from relativistic electrons moving in small-scale turbulent magnetic fields expected in high-energy astrophysical sources. Such a radiation spectrum is characterized by the strength parameter a = {lambda}{sub B} e|B|/mc {sup 2}, where {lambda}{sub B} is the length scale of the turbulent field. When a is much larger than the Lorentz factor of a radiating electron {gamma}, synchrotron radiation is realized, while a << 1 corresponds to the so-called jitter radiation regime. Because for 1 < a < {gamma} we cannot use either approximations, we should have recourse to the Lienard-Wiechert potential to evaluate themore » radiation spectrum, which is performed in this Letter. We generate random magnetic fields assuming Kolmogorov turbulence, inject monoenergetic electrons, solve the equation of motion, and calculate the radiation spectrum. We perform numerical calculations for several values of a with {gamma} = 10. We obtain various types of spectra ranging between jitter radiation and synchrotron radiation. For a {approx} 7, the spectrum takes a novel shape which had not been noticed up to now. It is like a synchrotron spectrum in the middle energy region, but in the low frequency region it is a broken power law and in the high frequency region an extra power-law component appears beyond the synchrotron cutoff. We give a physical explanation of these features.« less

[Modeling asthma evolution by a multi-state model].

PubMed

Boudemaghe, T; Daurès, J P

2000-06-01

There are many scores for the evaluation of asthma. However, most do not take into account the evolutionary aspects of this illness. We propose a model for the clinical course of asthma by a homogeneous Markov model process based on data provided by the A.R.I.A. (Association de Recherche en Intelligence Artificielle dans le cadre de l'asthme et des maladies respiratoires). The criterion used is the activity of the illness during the month before consultation. The activity is divided into three levels: light (state 1), mild (state 2) and severe (state 3). The model allows the evaluation of the strength of transition between states. We found that strong intensities were implicated towards state 2 (lambda(12) and lambda(32)), less towards state 1 (lambda(21) and lambda(31)), and minimum towards state 3 (lambda(23)). This results in an equilibrium distribution essentially divided between state 1 and 2 (44.6% and 51.0% respectively) with a small proportion in state 3 (4.4%). In the future, the increasing amount of available data should permit the introduction of covariables, the distinction of subgroups and the implementation of clinical studies. The interest of this model falls within the domain of the quantification of the illness as well as the representation allowed thereof, while offering a formal framework for the clinical notion of time and evolution.

Surface Temperature Measurements from a Stator Vane Doublet in a Turbine Engine Afterburner Flame Using a YAG:Tm Thermographic Phosphor

NASA Technical Reports Server (NTRS)

Eldridge, J. I.; Walker, D. G.; Gollub, S. L.; Jenkins, T. P.; Allison, S. W.

2015-01-01

Luminescence-based surface temperature measurements were obtained from a YAG:Tm-coated stator vane doublet exposed to the afterburner flame of a J85 test engine at University of Tennessee Space Institute (UTSI). The objective of the testing was to demonstrate that reliable surface temperatures based on luminescence decay of a thermographic phosphor producing short-wavelength emission could be obtained from the surface of an actual engine component in a high gas velocity, highly radiative afterburner flame environment. YAG:Tm was selected as the thermographic phosphor for its blue emission at 456 nm (1D23F4 transition) and UV emission at 365 nm (1D23H6 transition) because background thermal radiation is lower at these wavelengths, which are shorter than those of many previously used thermographic phosphors. Luminescence decay measurements were acquired using a probe designed to operate in the afterburner flame environment. The probe was mounted on the sidewall of a high-pressure turbine vane doublet from a Honeywell TECH7000 turbine engine coated with a standard electron-beam physical vapor deposited (EB-PVD) 200-m-thick TBC composed of yttria-stabilized zirconia (YSZ) onto which a 25-m-thick YAG:Tm thermographic phosphor layer was deposited by solution precursor plasma spray (SPPS). Spot temperature measurements were obtained by measuring luminescence decay times at different afterburner power settings and then converting decay time to temperature via calibration curves. Temperature measurements using the decays of the 456 and 365 nm emissions are compared. While successful afterburner environment measurements were obtained to about 1300C with the 456 nm emission, successful temperature measurements using the 365 nm emission were limited to about 1100C due to interference by autofluorescence of probe optics at short decay times.

Thermoresistant revertants of an Escherichia coli strain carrying tif-1 and ruv mutations: non-suppressibility of ruv by sfi.

PubMed Central

Otsuji, N; Iyehara-Ogawa, H

1979-01-01

Spontaneous thermoresistant revertants were isolated from Tif1 Ruv- and Tif1 Ruv+ strains of Escherichia coli K-12. They were divided into five groups; backmutants to tif+ and recA structural gene mutants accounted for at least two of these groups. Mutations with an unconditional RecA- phenyotype were detected at a higher frequency in the Tif1 Ruv- strains (65%) than in the Tif1 Ruv+ strains (25%). A third group consisted of revertants exhibiting a RecA- phenotype at low temperature. Revertants with normal recombination ability and UV resistance, but with a thermosensitive defect in propagating lambda bio11 phage, were also isolated (group 4). The alleles responsible for this property were cotransducible with the srl gene, suggesting that they are located at the recA locus. Other revertants, which might carry lex, LEXB, or zab mutations, were UV sensitive and were able to propagate lambda bio11 phage (group 5). The sfi mutation, which suppresses filamentation in the Tif1 and UV-sensitive Lon- strains, does not restore UV resistance of the Ruv- mutant. PMID:374356

The frequency dependence of the discharge properties in a capacitively coupled oxygen discharge

NASA Astrophysics Data System (ADS)

Gudmundsson, J. T.; Snorrason, D. I.; Hannesdottir, H.

2018-02-01

We use the one-dimensional object-oriented particle-in-cell Monte Carlo collision code oopd1 to explore the evolution of the charged particle density profiles, electron heating mechanism, the electron energy probability function (EEPF), and the ion energy distribution in a single frequency capacitively coupled oxygen discharge, with driving frequency in the range 12-100 MHz. At a low driving frequency and low pressure (5 and 10 mTorr), a combination of stochastic (α-mode) and drift ambipolar (DA) heating in the bulk plasma (the electronegative core) is observed and the DA-mode dominates the time averaged electron heating. As the driving frequency or pressure are increased, the heating mode transitions into a pure α-mode, where electron heating in the sheath region dominates. At low pressure (5 and 10 mTorr), this transition coincides with a sharp decrease in electronegativity. At low pressure and low driving frequency, the EEPF is concave. As the driving frequency is increased, the number of low energy electrons increases and the relative number of higher energy electrons (>10 eV) increases. At high driving frequency, the EEPF develops a convex shape or becomes bi-Maxwellian.

Study of a Flexible Low Profile Tunable Dipole Antenna Using Barium Strontium Titanate Varactors

NASA Technical Reports Server (NTRS)

Cure, David; Weller, Thomas; Miranda, Felix A.

2014-01-01

In this paper a flexible low profile dipole antenna using a frequency selective surface (FSS) with interdigital barium strontium titanate (BST) varactor-tuned unit cells is presented. The varactor chips were placed only along one dimension of the FSS to avoid the use of vias and simplify the DC bias network. The antenna uses overlapping metallic plates that resemble fish scales as a ground plane to improve the flexibility of the multi-material stack structure. The measured data of the antenna demonstrate tunability from 2.42 GHz to 2.66 GHz and 1.3 dB gain drop when using overlapping metallic plates instead of continuous ground plane. The total antenna thickness is approximately lambda/24.

From high-scale leptogenesis to low-scale one-loop neutrino mass generation

NASA Astrophysics Data System (ADS)

Zhou, Hang; Gu, Pei-Hong

2018-02-01

We show that a high-scale leptogenesis can be consistent with a low-scale one-loop neutrino mass generation. Our models are based on the SU(3)c × SU(2)L × U(1)Y × U(1) B - L gauge groups. Except a complex singlet scalar for the U(1) B - L symmetry breaking, the other new scalars and fermions (one scalar doublet, two or more real scalar singlets/triplets and three right-handed neutrinos) are odd under an unbroken Z2 discrete symmetry. The real scalar decays can produce an asymmetry stored in the new scalar doublet which subsequently decays into the standard model lepton doublets and the right-handed neutrinos. The lepton asymmetry in the standard model leptons then can be partially converted to a baryon asymmetry by the sphaleron processes. By integrating out the heavy scalar singlets/triplets, we can realize an effective theory to radiatively generate the small neutrino masses at the TeV scale. Furthermore, the lightest right-handed neutrino can serve as a dark matter candidate.

Singlet and doublet states UV-vis spectrum and electronic properties of 3-methylchrysene and 4-methylchrysene in glass matrix.

PubMed

Husain, Mudassir M; Tandon, H C; Varadwaj, Pradeep R

2008-03-01

The ultraviolet-visual spectrum of 3-methylchrysene, 4-methylchrysene and their radical cations formed by ultraviolet radiations, were measured in glass matrix at the room temperature. In the measured singlet state spectrum we were able to identify the alpha, p, beta, beta' (Clar's) or (1)L(b), (1)L(a)(1)B(b), (1)B(a) (Platt's notation) bands. The presence of alpha, beta or (1)L(b), (1)B(b) was confirmed by calculating their wavelength ratio lambda(alpha)/lambda(beta). Since matrix induces perturbation in the measured spectrum; it becomes necessary to take into account the perturbation while computing the spectrum. An effort has been made in this work to simulate the electronic spectrum in the same environment as is measured. This study presents the first calculated spectrum of these systems and their cations in glass matrix by semi empirical methods. To observe the magnitude of perturbation and hence to see the spectral shift in glass matrix, the spectrum was calculated in the free state as well. Spectral properties such as frontier orbitals gap, dipole moment, mean polarizabilities and its tensors were also computed both in glass matrix and free state using semiemperical method. The measured bands of 3-methylchrysene cation at wavelength 416.50 and 473.85 nm closely match with the available diffuse intersteallar bands (DIBs) at 417.55 and 472.64 nm, respectively. Also the observed 474.85 nm band of 4-methylchrysene cation matches the DIB at 476.00 nm.

Modified van Vaals-Bergman coaxial cable coil (lambda coil) for high-field imaging.

PubMed

Matsuzawa, H; Nakada, T

1996-03-01

An easily constructed, low-capacitive coupling volume coil based on the van Vaals-Bergman coaxial cable coil for high field imaging is described. The coil (designated "lambda coil") was constructed using two 5/4 length 50 omega coaxial cables matched to a 50 omega transmission line with LC bridge balun. The standing wave on the single 5/4 lambda length coaxial cable provides two points of current maxima in oppositional direction. Therefore, the four current elements necessary for effective B1 field generation can be obtained by two 5/4 lambda length coaxial cables arranged analogous to 1/2 lambda T-antenna. Capacitive coupling between the coil elements and conductive samples (i.e. animals) is minimized by simply retaining the shield of the coaxial cable for the area of voltage maxima. The lambda coil exhibited excellent performance as a volume coil with a high quality factor and highly homogeneous rf fields. Because of its dramatically simple architecture and excellent performance, the lambda coil configuration appears to be an economical alternative to the original van Vaals-Bergman design, especially for research facilities with a high field magnet and limited bore space.

[Verification of a decrease in the rigidity of the phage lambda DNA polymeric chain in low ionic strength aqueous solutions by testing the polymer-polymer interlink interactions].

PubMed

Arutiunian, A V; Ivanova, M A; Kurliand, D I; Kapshin, Iu S; Landa, S B; Poshekhonov, S T; Drobchenko, E A; Shevelev, I V

2011-01-01

Changes in the rigidity of the polymetric chain of phage lambda double-strand DNA have been studied by laser correlation spectroscopy. It was shown that, as the ionic strength increases, the effect of the screening of the hydrodynamic interaction of the links of the polymeric chain specific for polymeric coils arises in a DNA solution. It is assumed that the screening occurs when the threshold of the overlapping of DNA coils is achieved. The overlapping of coils is the result of a previously observed significant rise of DNA coil size from abnormally small DNA coils in low ionic strength buffers (about 10(-2) M Na+ or less) to maximum possible large coils in the 5SSC and 5SSC-like buffers. Further analysis of the far interlink interactions in linear lambda phage DNA coils in similar buffers at pH 7 and 4 confirms the earlier proposal about the role of H+ ions in the appearance of abnormally small DNA coils. The abnormal decrease in the DNA coil size in low ionic strength buffers is not a specific feature of lambda phage DNA only.

Analysis of the 2012 Ahar-Varzeghan (Iran) seismic sequence: Insights from statistical and stress transfer modeling

NASA Astrophysics Data System (ADS)

Yazdi, Pouye; Santoyo, Miguel Angel; Gaspar-Escribano, Jorge M.

2018-02-01

The 2012 Ahar-Varzeghan (Northwestern Iran) earthquake doublet and its following seismic sequence are analyzed in this paper. First, it is examined the time-varying statistical characteristics of seismic activity since the occurrence of the doublet (two large events with Mw = 6.4 and 6.2) that initiated the sequence on 11 August 2012. A power law magnitude-frequency distribution (1.9 ≤ M ≤ 6.4) is obtained, with relatively low b-values for the complete series indicating the existence of relatively large magnitudes and high-stress level in the area. The Omori-Utsu model of the aftershock population decay with time shows a moderate decrease in activity rate. An epidemic-type aftershock sequence model that separates background seismicity from triggered aftershocks is then used to describe the temporal evolution of the seismicity during the period following the occurrence of the doublet. Results for the entire series (above cutoff magnitude Mc = 1.9) indicate a relatively low productivity related to the earthquake-earthquake triggering. Indeed, the majority of these events seems to be generated by underlying transient or aseismic processes, which might be added to the tectonic loading stress. The proportion of aftershock events significantly increases when the analysis is limited to larger events (M ≥ 3.0) suggesting that the triggered large aftershocks entail a substantial portion of the energy released. In order to analyze the spatial distribution of the sequence, new source models are proposed for the two main shocks. For the first shock, the coseismic slip distribution is constrained by the available data on surface ruptures. A Coulomb failure stress transfer model produced by the first event along optimally-oriented planes allows identifying the areas with positive stress loads where the rupture of the subsequent aftershocks may have occurred. The positive Δ CFS areas are compared for two depth intervals: 3-10 km and 15-22 km overlapping over 350 relocated hypocenters, giving arguments supporting the interpretation of Δ CFS as a main mechanism for aftershock triggering in deeper zones of the upper crust.

Coexistence of magnetic fluctuations and superconductivity in the pnictide high temperature superconductor SmFeAsO1-xFx measured by muon spin rotation.

PubMed

Drew, A J; Pratt, F L; Lancaster, T; Blundell, S J; Baker, P J; Liu, R H; Wu, G; Chen, X H; Watanabe, I; Malik, V K; Dubroka, A; Kim, K W; Rössle, M; Bernhard, C

2008-08-29

Muon spin rotation experiments were performed on the pnictide high temperature superconductor SmFeAsO1-xFx with x=0.18 and 0.3. We observed an unusual enhancement of slow spin fluctuations in the vicinity of the superconducting transition which suggests that the spin fluctuations contribute to the formation of an unconventional superconducting state. An estimate of the in-plane penetration depth lambda ab(0)=190(5) nm was obtained, which confirms that the pnictide superconductors obey an Uemura-style relationship between Tc and lambda ab(0);(-2).

Influence of the photon orbital angular momentum on electric dipole transitions: negative experimental evidence.

PubMed

Giammanco, F; Perona, A; Marsili, P; Conti, F; Fidecaro, F; Gozzini, S; Lucchesini, A

2017-01-15

We describe an experiment of atomic spectroscopy devoted to ascertaining whether the orbital angular momentum (OAM) of photons has the same property of interacting with atoms or molecules as occurs for the spin angular momentum (SAM). In our experiment, rubidium vapors are excited by means of laser radiation with different combinations of OAM and SAM, particularly selected to inhibit or enhance the fluorescence according to the selection rules for the electric dipole transitions between the fundamental state and the first excited doublet. Our results clearly show that an electric-dipole-type transition is insensitive to the OAM value, and provide an original validation of a problem long debated in theoretical works.

20-Hz pulses and other vocalizations of fin whales, Balaenoptera physalus, in the Gulf of California, Mexico.

PubMed

Thompson, P O; Findley, L T; Vidal, O

1992-12-01

Low-frequency vocalizations were recorded from fin whales, Balaenoptera physalus, in the Gulf of California, Mexico, during three cruises. In March 1985, recorded 20-Hz pulses were in sequences of regular 9-s interpulse intervals. In August 1987, nearly all were in sequences of doublets with alternating 5- and 18-s interpulse intervals. No 20-Hz pulse sequences of any kind were detected in February 1987. The typical pulse modulated from 42 to 20 Hz and its median duration was 0.7 s (1985 data). Most other fin whale sounds were also short tonal pulses averaging 82, 56, and 68 Hz, respectively, for the three cruises; 89% were modulated in frequency, mostly downward. Compared to Atlantic and Pacific Ocean regions, Gulf of California 20-Hz pulses were unique in terms of frequency modulation, interpulse sound levels, and temporal patterns. Fin whales in the Gulf may represent a regional stock revealed by their sound characteristics, a phenomenon previously shown for humpback whales, birds, and fish. Regional differences in fin whale sounds were found in comparisons of Atlantic and Pacific locations.

Bottom-up approach for microstructure optimization of sound absorbing materials.

PubMed

Perrot, Camille; Chevillotte, Fabien; Panneton, Raymond

2008-08-01

Results from a numerical study examining micro-/macrorelations linking local geometry parameters to sound absorption properties are presented. For a hexagonal structure of solid fibers, the porosity phi, the thermal characteristic length Lambda('), the static viscous permeability k(0), the tortuosity alpha(infinity), the viscous characteristic length Lambda, and the sound absorption coefficient are computed. Numerical solutions of the steady Stokes and electrical equations are employed to provide k(0), alpha(infinity), and Lambda. Hybrid estimates based on direct numerical evaluation of phi, Lambda('), k(0), alpha(infinity), Lambda, and the analytical model derived by Johnson, Allard, and Champoux are used to relate varying (i) throat size, (ii) pore size, and (iii) fibers' cross-section shapes to the sound absorption spectrum. The result of this paper tends to demonstrate the important effect of throat size in the sound absorption level, cell size in the sound absorption frequency selectivity, and fibers' cross-section shape in the porous material weight reduction. In a hexagonal porous structure with solid fibers, the sound absorption level will tend to be maximized with a 48+/-10 microm throat size corresponding to an intermediate resistivity, a 13+/-8 microm fiber radius associated with relatively small interfiber distances, and convex triangular cross-section shape fibers allowing weight reduction.

Microstructural Evaluations of Baseline HSR/EPM Disk Alloys

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Garg, Anita; Ellis, David L.

2004-01-01

Six alloys representing two classes of powder metallurgy nickel-based superalloys were examined by transmission electron microscopy (TEM) and phase extraction. Alloys KM4, CH98, IN-100 and 456 are based on a Ni-18Co-12Cr composition while alloys Rene' 88 DT and SR 3 have lower Al and Co and higher Cr contents. The lambda size distributions were determined from quantitative image analysis of the TEM images. The volume fraction of lambda and carbides and the composition of the phases were determined by a combination of phase extraction and TEM. The results showed many similarities in lambda size distributions, grain boundary serrations, and grain boundary carbide frequencies between alloys KM4, CH98, 456, Rene' 88 DT and SR 3 when heat treated to give an approximate grain size of ASTM 6. The density of grain boundary carbides in KM4 was shown to substantially increase as the grain size increased. IN-100 and 456 subjected to a serration cooling heat treatment had much more complex lambda size distributions with very large intergranular and intragranular secondary lambda as well as finer than average cooling and aging lambda. The grain boundary carbides in IN-100 were similar to the other alloys, but 456 given the serration cooling heat treatment had a more variable density of grain boundary carbides. Examination of the phases extracted from the matrix showed that there were significant differences in the phase chemistries and elemental partitioning ratios between the various alloys.

The design, analysis, and testing of a low-budget wind-tunnel flutter model with active aerodynamic controls

NASA Technical Reports Server (NTRS)

Bolding, R. M.; Stearman, R. O.

1976-01-01

A low budget flutter model incorporating active aerodynamic controls for flutter suppression studies was designed as both an educational and research tool to study the interfering lifting surface flutter phenomenon in the form of a swept wing-tail configuration. A flutter suppression mechanism was demonstrated on a simple semirigid three-degree-of-freedom flutter model of this configuration employing an active stabilator control, and was then verified analytically using a doublet lattice lifting surface code and the model's measured mass, mode shapes, and frequencies in a flutter analysis. Preliminary studies were significantly encouraging to extend the analysis to the larger degree of freedom AFFDL wing-tail flutter model where additional analytical flutter suppression studies indicated significant gains in flutter margins could be achieved. The analytical and experimental design of a flutter suppression system for the AFFDL model is presented along with the results of a preliminary passive flutter test.

A fresh look at the photoelectron spectrum of bromobenzene: A third-order non-Dyson electron propagator study.

PubMed

Schneider, M; Soshnikov, D Yu; Holland, D M P; Powis, I; Antonsson, E; Patanen, M; Nicolas, C; Miron, C; Wormit, M; Dreuw, A; Trofimov, A B

2015-10-14

The valence-shell ionization spectrum of bromobenzene, as a representative halogen substituted aromatic, was studied using the non-Dyson third-order algebraic-diagrammatic construction [nD-ADC(3)] approximation for the electron propagator. This method, also referred to as IP-ADC(3), was implemented as a part of the Q-Chem program and enables large-scale calculations of the ionization spectra, where the computational effort scales as n(5) with respect to the number of molecular orbitals n. The IP-ADC(3) scheme is ideally suited for investigating low-lying ionization transitions, so fresh insight could be gained into the cationic state manifold of bromobenzene. In particular, the present IP-ADC(3) calculations with the cc-pVTZ basis reveal a whole class of low-lying low-intensity two-hole-one-particle (2h-1p) doublet and quartet states, which are relevant to various photoionization processes. The good qualitative agreement between the theoretical spectral profile for the valence-shell ionization transitions generated with the smaller cc-pVDZ basis set and the experimental photoelectron spectrum measured at a photon energy of 80 eV on the PLÉIADES beamline at the Soleil synchrotron radiation source allowed all the main features to be assigned. Some theoretical aspects of the ionization energy calculations concerning the use of various approximation schemes and basis sets are discussed.

A fresh look at the photoelectron spectrum of bromobenzene: A third-order non-Dyson electron propagator study

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

Schneider, M.; Wormit, M.; Dreuw, A.

2015-10-14

The valence-shell ionization spectrum of bromobenzene, as a representative halogen substituted aromatic, was studied using the non-Dyson third-order algebraic-diagrammatic construction [nD-ADC(3)] approximation for the electron propagator. This method, also referred to as IP-ADC(3), was implemented as a part of the Q-Chem program and enables large-scale calculations of the ionization spectra, where the computational effort scales as n{sup 5} with respect to the number of molecular orbitals n. The IP-ADC(3) scheme is ideally suited for investigating low-lying ionization transitions, so fresh insight could be gained into the cationic state manifold of bromobenzene. In particular, the present IP-ADC(3) calculations with the cc-pVTZmore » basis reveal a whole class of low-lying low-intensity two-hole-one-particle (2h-1p) doublet and quartet states, which are relevant to various photoionization processes. The good qualitative agreement between the theoretical spectral profile for the valence-shell ionization transitions generated with the smaller cc-pVDZ basis set and the experimental photoelectron spectrum measured at a photon energy of 80 eV on the PLÉIADES beamline at the Soleil synchrotron radiation source allowed all the main features to be assigned. Some theoretical aspects of the ionization energy calculations concerning the use of various approximation schemes and basis sets are discussed.« less

Spatiotemporal analysis of turbulent jets enabled by 100-kHz, 100-ms burst-mode particle image velocimetry

NASA Astrophysics Data System (ADS)

Miller, Joseph D.; Jiang, Naibo; Slipchenko, Mikhail N.; Mance, Jason G.; Meyer, Terrence R.; Roy, Sukesh; Gord, James R.

2016-12-01

100-kHz particle image velocimetry (PIV) is demonstrated using a double-pulsed, burst-mode laser with a burst duration up to 100 ms. This enables up to 10,000 time-sequential vector fields for capturing a temporal dynamic range spanning over three orders of magnitude in high-speed turbulent flows. Pulse doublets with inter-pulse spacing of 2 µs and repetition rate of 100 kHz are generated using a fiber-based oscillator and amplified through an all-diode-pumped, burst-mode amplifier. A physics-based model of pulse doublet amplification in the burst-mode amplifier is developed and used to accurately predict oscillator pulse width and pulse intensity inputs required to generate equal-energy pulse doublets at 532 nm for velocity measurements. The effect of PIV particle response and high-speed-detector limitations on the spatial and temporal resolution are estimated in subsonic turbulent jets. An effective spatial resolution of 266-275 µm and temporal resolution of 10 µs are estimated from the 8 × 8 pixel correlation window and inter-doublet time spacing, respectively. This spatiotemporal resolution is sufficient for quantitative assessment of integral time and length scales in highly turbulent jets with Reynolds numbers in the range 15,000-50,000. The temporal dynamic range of the burst-mode PIV measurement is 1200, limited by the 85-ms high-energy portion of the burst and 30-kHz high-frequency noise limit.

The Lambda Select cII Mutation Detection System.

PubMed

Besaratinia, Ahmad; Tommasi, Stella

2018-04-26

A number of transgenic animal models and mutation detection systems have been developed for mutagenicity testing of carcinogens in mammalian cells. Of these, transgenic mice and the Lambda (λ) Select cII Mutation Detection System have been employed for mutagenicity experiments by many research groups worldwide. Here, we describe a detailed protocol for the Lambda Select cII mutation assay, which can be applied to cultured cells of transgenic mice/rats or the corresponding animals treated with a chemical/physical agent of interest. The protocol consists of the following steps: (1) isolation of genomic DNA from the cells or organs/tissues of transgenic animals treated in vitro or in vivo, respectively, with a test compound; (2) recovery of the lambda shuttle vector carrying a mutational reporter gene (i.e., cII transgene) from the genomic DNA; (3) packaging of the rescued vectors into infectious bacteriophages; (4) infecting a host bacteria and culturing under selective conditions to allow propagation of the induced cII mutations; and (5) scoring the cII-mutants and DNA sequence analysis to determine the cII mutant frequency and mutation spectrum, respectively.

Hepatopancreatic intoxication of lambda cyhalothrin insecticide on albino rats

PubMed Central

Elhalwagy, Manal EA; Abd-Alrahman, Sherif H; Nahas, AA; Ziada, Reem M; Mohamady, Aziza H

2015-01-01

Background: Despite the known adverse effects of lambda cyhalothrin insecticide, little is known about its hepatopancreatic intoxication effects. The present study was carried out to elucidate sub-chronic effect of Karat 2.5% EC formulation of lambda cyhalothrin on male albino rats. Methods: To explore the effects of exposure to lambda cyhalothrin on rats and its mechanism, low (1/40 of LD50, 5 mg/kg/day) and high dose (1/4 of LD50, 50 mg/kg/day) lambda cyhalothrin were applied to rats via drinking water for 3 months. Blood samples were collected monthly, and the animals were dissected for liver and pancreas’s examination at the end of the experiment. Lambda cyhalothrin administration was associated with the elevation in lipid peroxidation marker, malondialdehyde (MDA), reduction in SH-protein a major marker for antioxidant, as well as basel paraoxonase (PON) in both treated groups throughout the experimental periods. Results: In addition, significant elevations in liver enzymes alanin amino transferase, (ALT), and aspartate amino transferase (AST), as well as plasma acetylcholinesterase (AChE) and glucose level. While, significant reduction in insulin level through the experimental periods. Results of histopathological and histochemical studies showed that lambda cyhalothrin exposure induces liver and pancreatic tissues damage and depletion in glycogen content was pronounced in liver of both treated groups. Conclusions: In conclusion subchronic intoxication with lambda cyhalothrin formulation induced remarkable changes in the examined parameters. PMID:26221269

Hepatopancreatic intoxication of lambda cyhalothrin insecticide on albino rats.

PubMed

Elhalwagy, Manal Ea; Abd-Alrahman, Sherif H; Nahas, A A; Ziada, Reem M; Mohamady, Aziza H

2015-01-01

Despite the known adverse effects of lambda cyhalothrin insecticide, little is known about its hepatopancreatic intoxication effects. The present study was carried out to elucidate sub-chronic effect of Karat 2.5% EC formulation of lambda cyhalothrin on male albino rats. To explore the effects of exposure to lambda cyhalothrin on rats and its mechanism, low (1/40 of LD50, 5 mg/kg/day) and high dose (1/4 of LD50, 50 mg/kg/day) lambda cyhalothrin were applied to rats via drinking water for 3 months. Blood samples were collected monthly, and the animals were dissected for liver and pancreas's examination at the end of the experiment. Lambda cyhalothrin administration was associated with the elevation in lipid peroxidation marker, malondialdehyde (MDA), reduction in SH-protein a major marker for antioxidant, as well as basel paraoxonase (PON) in both treated groups throughout the experimental periods. In addition, significant elevations in liver enzymes alanin amino transferase, (ALT), and aspartate amino transferase (AST), as well as plasma acetylcholinesterase (AChE) and glucose level. While, significant reduction in insulin level through the experimental periods. Results of histopathological and histochemical studies showed that lambda cyhalothrin exposure induces liver and pancreatic tissues damage and depletion in glycogen content was pronounced in liver of both treated groups. In conclusion subchronic intoxication with lambda cyhalothrin formulation induced remarkable changes in the examined parameters.

Anisotropy of the penetration depth in La2-xSrxCuO4 in underdoped and overdoped regions

NASA Astrophysics Data System (ADS)

Zaleski, A. J.; Klamut, J.

1999-12-01

We present the results of measurements of the penetration depth anisotropy in pulverized, ceramic La2-xSrxCuO4. The measurements were carried out for x = 0.08, 0.1, 0.125, 0.15 and 0.2. The powdered samples, immersed in wax, were magnetically oriented in a static magnetic field of 10 T. The penetration depth in the a-b plane, icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/>ab, and perpendicular to it, icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/>icons/Journals/Common/perp" ALT="perp" ALIGN="MIDDLE"/>, were derived from alternating-current susceptibility measurements. For underdoped samples they both vary linearly with temperature (for the low-temperature region), while for the samples from the overdoped region the measured points can be fitted by an exponential function. These results support Uemura's picture (Uemura Y J 1997 Physica C 282-287 194) of crossover from Bose-Einstein condensation to a Bardeen-Cooper-Schrieffer mechanism of superconductivity. The penetration depth values extrapolated to T = 0 may be described by a quadratic function of the strontium concentration (for both icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/>ab and icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/>icons/Journals/Common/perp" ALT="perp" ALIGN="MIDDLE"/>). The anisotropy of the penetration depth as a function of the substitution shows a similar dependence to the critical temperature Tc(x).

The wavelet response as a multiscale characterization of scattering processes at granular interfaces.

PubMed

Le Gonidec, Yves; Gibert, Dominique

2006-11-01

We perform a multiscale analysis of the backscattering properties of a complex interface between water and a layer of randomly arranged glass beads with diameter D=1 mm. An acoustical experiment is done to record the wavelet response of the interface in a large frequency range from lambda/D=0.3 to lambda/D=15. The wavelet response is a physical analog of the mathematical wavelet transform which possesses nice properties to detect and characterize abrupt changes in signals. The experimental wavelet response allows to identify five frequency domains corresponding to different backscattering properties of the complex interface. This puts quantitative limits to the validity domains of the models used to represent the interface and which are flat elastic, flat visco-elastic, rough random half-space with multiple scattering, and rough elastic from long to short wavelengths respectively. A physical explanation based on Mie scattering theory is proposed to explain the origin of the five frequency domains identified in the wavelet response.

Lifetimes and Oscillator Strengths for Ultraviolet Transitions in P II, Cl II and Cl III

NASA Technical Reports Server (NTRS)

Cheng, S.; Federman, S. R.; Schectman, R. M.; Brown, M.; Irving, R. E.; Fritts, M. C.; Gibson, N. D.

2006-01-01

Oscillator strengths for transitions in P II, Cl II and Cl III are derived from lifetimes and branching factions measured with beam-foil techniques. The focus is on the multiplets with a prominent interstellar line at 1153 A in P II which is seen in spectra of hot stars, and the lines at 1071 A in Cl II and 1011 A in Cl III whose lines are seen in spectra of diffuse interstellar clouds and the Io torus acquired with the Far Ultraviolet Spectroscopic Explorer. These data represent the first complete set of experimental f-values for the lines in the multiplets. Our results for P II (lambda)1153 agree well with Curtis semi-empirical predictions, as well as the large scale computations by Hibbert and by Tayal. The data for Cl II (lambda)1071 also agree very well with the most recent theoretical effort and with Morton s newest recommendations. For Cl III, however, our f-values are significantly larger than those given by Morton; instead, they are more consistent with recent large-scale theoretical calculations. Extensive tests provide confirmation that LS coupling rules apply to the transitions for the multiplets in Cl II and Cl III.

A recent deep earthquake doublet in light of long-term evolution of Nazca subduction

NASA Astrophysics Data System (ADS)

Zahradník, J.; Čížková, H.; Bina, C. R.; Sokos, E.; Janský, J.; Tavera, H.; Carvalho, J.

2017-03-01

Earthquake faulting at ~600 km depth remains puzzling. Here we present a new kinematic interpretation of two Mw7.6 earthquakes of November 24, 2015. In contrast to teleseismic analysis of this doublet, we use regional seismic data providing robust two-point source models, further validated by regional back-projection and rupture-stop analysis. The doublet represents segmented rupture of a ˜30-year gap in a narrow, deep fault zone, fully consistent with the stress field derived from neighbouring 1976-2015 earthquakes. Seismic observations are interpreted using a geodynamic model of regional subduction, incorporating realistic rheology and major phase transitions, yielding a model slab that is nearly vertical in the deep-earthquake zone but stagnant below 660 km, consistent with tomographic imaging. Geodynamically modelled stresses match the seismically inferred stress field, where the steeply down-dip orientation of compressive stress axes at ˜600 km arises from combined viscous and buoyant forces resisting slab penetration into the lower mantle and deformation associated with slab buckling and stagnation. Observed fault-rupture geometry, demonstrated likelihood of seismic triggering, and high model temperatures in young subducted lithosphere, together favour nanometric crystallisation (and associated grain-boundary sliding) attending high-pressure dehydration as a likely seismogenic mechanism, unless a segment of much older lithosphere is present at depth.

Effect of signal frequency on four-wave mixing through stimulated Brillouin scattering.

PubMed

Watkins, D E; Scott, A M; Ridley, K D

1990-11-15

We present measurements of the dependence of the phase-conjugate reflectivity on signal frequency for Brillouinenhanced four-wave mixing at pump intensities above the threshold instability. The measurements were made in TiC1(4) at lambda = 1 microm and are consistent with a computer model of the reflectivity. We have observed that the frequency of the conjugate beam is independent of the frequency of the input signal beam in the unstable regime.

Ab initio determination of geometries and vibrational characteristics of building blocks of organic super-conductors: TTF and its derivatives.

PubMed

Rani, P; Yadav, R A

2012-12-01

Molecular behavior of the building block {[2-(1,3-dithiole-2-ylidene)-1,3-dithiole] ≡ tetrathiafulvalene (TTF)} of organic superconductors have been investigated along with its three derivatives, namely, {[2-(1,3-dioxole-2-ylidene)-1,3-dioxole] ≡ tetraoxafulvalene (TOF)}; [2,2]-bi -[[1,3] oxathiolylidene] ≡ Der I and 2-(3H-Furan-2-ylidene)-[1,3] oxathiole ≡ Der II. The properties of the molecules such as molecular geometries, frontier MOs and vibrational spectra have been investigated by using DFT method at the B3LYP level employing 6-311++G(d,p) basis set. The geometrical parameters and atomic charges on various atomic sites of the TTF, TOF, Ders I and II suggest extended conjugation in these systems. The present calculations lead to the reassignments for of some of the fundamentals and new interpretations for some of the observed IR and Raman frequencies. One of the two modes involved in the Fermi resonance giving rise to the doublet 1555 and 1564 cm(-1) needed to be revised and another doublet 3083 and 3108 cm(-1) could be interpreted as a Fermi resonance doublet. Out of the two ν(C = C) modes under the a(1) species, the lower frequency mode is assigned to the ν(C = C) of the ring and the higher one to the ν(C = C) of the central C = C bond contrary to the assignment reported in literature. The conducting properties of these molecules depend mainly on this mode. Copyright © 2012 Elsevier B.V. All rights reserved.

Magnetooptics of the luminescent transitions in Tb3+:Gd3Ga5O12

NASA Astrophysics Data System (ADS)

Valiev, Uygun V.; Gruber, John B.; Ivanov, Igor'A.; Burdick, Gary W.; Liang, Hongbin; Zhou, Lei; Fu, Dejun; Pelenovich, Oleg V.; Pelenovich, Vasiliy O.; Lin, Zhou

2015-08-01

The spectra of the luminescence and magnetic circular polarization of luminescence in terbium-gadolinium gallium garnet Tb3+:Gd3Ga5O12 (Tb3+:GGG) were studied within the visible spectral range at temperatures T = 90 and 300 K in an external magnetic field of 0.45 T. The Zeeman effect in the luminescence "green" band associated with 4f → 4f transition 5D4 → 7F5 of Tb3+:GGG was also studied at T = 90 K in an external field of 0.55 T. Measurement of the Zeeman effect in Tb3+:GGG carried out for some doublet lines of the luminescence band 5D4 → 7F5 at T = 90 K shows that a magnetooptical effect of the intensity change of the emitted light is observed on these lines, in contrast to pure Zeeman splitting of the emission lines measured in the luminescence band 5D4 → 7F6. For the systems we have studied, the maximal value of the magnetooptical effect of the intensity change of the luminescence line at low temperatures has been achieved in paramagnetic garnet Tb0.2Y2.8Al5O12 at comparatively low magnetic fields.

Determination of Hund's coupling in 5 d oxides using resonant inelastic x-ray scattering

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

Yuan, Bo; Clancy, J. P.; Cook, A. M.

2017-06-01

We report resonant inelastic x-ray scattering (RIXS) measurements on ordered double-perovskite samples containing Re5+ and Ir5+ with 5d(2) and 5d(4) electronic configurations, respectively. In particular, the observedRIXS spectra of Ba2YReO6 and Sr2MIrO6 (M = Y, Gd) show sharp intra-t(2g) transitions, which can be quantitatively understood using a minimal "atomic" Hamiltonian incorporating spin-orbit coupling. and Hund's coupling J(H). Our analysis yields lambda = 0.38(2) eV with J(H) = 0.26(2) eV for Re5+ and lambda = 0.42(2) eV with J(H) = 0.25(4) eV for Ir5+. Our results provide sharp estimates for Hund's coupling in 5d oxides and suggest that it should bemore » treated on equal footing with spin-orbit interaction in multiorbital 5d transition-metal compounds.« less

A photon spectrometric dose-rate constant determination for the Advantage Pd-103 brachytherapy source

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

Chen, Zhe Jay; Bongiorni, Paul; Nath, Ravinder

Purpose: Although several dosimetric characterizations using Monte Carlo simulation and thermoluminescent dosimetry (TLD) have been reported for the new Advantage Pd-103 source (IsoAid, LLC, Port Richey, FL), no AAPM consensus value has been established for the dosimetric parameters of the source. The aim of this work was to perform an additional dose-rate constant ({Lambda}) determination using a recently established photon spectrometry technique (PST) that is independent of the published TLD and Monte Carlo techniques. Methods: Three Model IAPD-103A Advantage Pd-103 sources were used in this study. The relative photon energy spectrum emitted by each source along the transverse axis wasmore » measured using a high-resolution germanium spectrometer designed for low-energy photons. For each source, the dose-rate constant was determined from its emitted energy spectrum. The PST-determined dose-rate constant ({sub PST}{Lambda}) was then compared to those determined by TLD ({sub TLD}{Lambda}) and Monte Carlo ({sub MC}{Lambda}) techniques. A likely consensus {Lambda} value was estimated as the arithmetic mean of the average {Lambda} values determined by each of three different techniques. Results: The average {sub PST}{Lambda} value for the three Advantage sources was found to be (0.676{+-}0.026) cGyh{sup -1} U{sup -1}. Intersource variation in {sub PST}{Lambda} was less than 0.01%. The {sub PST}{Lambda} was within 2% of the reported {sub MC}{Lambda} values determined by PTRAN, EGSnrc, and MCNP5 codes. It was 3.4% lower than the reported {sub TLD}{Lambda}. A likely consensus {Lambda} value was estimated to be (0.688{+-}0.026) cGyh{sup -1} U{sup -1}, similar to the AAPM consensus values recommended currently for the Theragenics (Buford, GA) Model 200 (0.686{+-}0.033) cGyh{sup -1} U{sup -1}, the NASI (Chatsworth, CA) Model MED3633 (0.688{+-}0.033) cGyh{sup -1} U{sup -1}, and the Best Medical (Springfield, VA) Model 2335 (0.685{+-}0.033) cGyh{sup -1} U{sup -1} {sup 103}Pd sources. Conclusions: An independent {Lambda} determination has been performed for the Advantage Pd-103 source. The {sub PST}{Lambda} obtained in this work provides additional information needed for establishing a more accurate consensus {Lambda} value for the Advantage Pd-103 source.« less

Nuclear spin/parity dependent spectroscopy and predissociation dynamics in vOH = 2 ← 0 overtone excited Ne-H2O clusters: Theory and experiment

NASA Astrophysics Data System (ADS)

Ziemkiewicz, Michael P.; Pluetzer, Christian; Loreau, Jérôme; van der Avoird, Ad; Nesbitt, David J.

2017-12-01

Vibrationally state selective overtone spectroscopy and state- and nuclear spin-dependent predissociation dynamics of weakly bound ortho- and para-Ne-H2O complexes (D0(ortho) = 34.66 cm-1 and D0(para) = 31.67 cm-1) are reported, based on near-infrared excitation of van der Waals cluster bands correlating with vOH = 2 ← 0 overtone transitions (|02-〉 and |02+〉) out of the ortho (101) and para (000) internal rotor states of the H2O moiety. Quantum theoretical calculations for nuclear motion on a high level potential energy surface [CCSD(T)/VnZf12 (n = 3, 4)], corrected for basis set superposition error and extrapolated to the complete basis set (CBS) limit, are employed to successfully predict and assign Π-Σ, Σ-Σ, and Σ-Π infrared bands in the spectra, where Σ or Π represent approximate projections of the body-fixed H2O angular momentum along the Ne-H2O internuclear axis. IR-UV pump-probe experimental capabilities permit real-time measurements of the vibrational predissociation dynamics, which indicate facile intramolecular vibrational energy transfer from the H2O vOH = 2 overtone vibrations into the VdWs (van der Waals) dissociation coordinate on the τprediss = 15-25 ns time scale. Whereas all predicted strong transitions in the ortho-Ne-H2O complexes are readily detected and assigned, vibrationally mediated photolysis spectra for the corresponding para-Ne-H2O bands are surprisingly absent despite ab initio predictions of Q-branch intensities with S/N > 20-40. Such behavior signals the presence of highly selective nuclear spin ortho-para predissociation dynamics in the upper state, for which we offer a simple mechanism based on Ne-atom mediated intramolecular vibrational relaxation in the H2O subunit (i.e., |02±〉 → {|01±〉; v2 = 2}), which is confirmed by the ab initio energy level predictions and the nascent OH rotational (N), spin orbit (Π1/2,3/2), and lambda doublet product distributions.

Structural and magnetic properties of morphotropic phase boundary involved Tb 1-xGd xFe 2 compounds

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

Murtaza, Adil; Yang, Sen; Zhou, Chao

2016-09-01

In the present paper, structural, magnetic and magnetostrictive properties of Tb 1-xGd xFe 2 (0 <= x <= 1.0) were studied. Synchrotron x-ray diffraction (XRD) results show the non-cubic symmetry of Tb 1-xGd xFe 2 at room temperature and composition-induced crystallographic phase transition from rhombohedral phase to tetragonal phase. The Gd concentration dependent lattice parameters, lattice distortion and change of easy magnetic direction were detected by synchrotron XRD. With the Gd concentration increases, Curie temperature Tc increases while room temperature magnetization and magnetostriction coefficient lambda(111) and the anisotropy of TbFe 2 decrease. The decrease in spontaneous magnetostriction coefficient lambda(111) withmore » increasing Gd substitution can be understood on the basis of the single-ion model; the corresponding decrease of magnetostriction for Tb 1-xGd xFe 2, and the large magnetostriction value occurs on the Tb-rich side, are ascribed to decrease of lambda(111)« less

In VivoLactate Editing with Simultaneous Detection of Choline, Creatine, NAA, and Lipid Singlets at 1.5 T Using PRESS Excitation with Applications to the Study of Brain and Head and Neck Tumors

NASA Astrophysics Data System (ADS)

Star-Lack, Josh; Spielman, Daniel; Adalsteinsson, Elfar; Kurhanewicz, John; Terris, David J.; Vigneron, Daniel B.

1998-08-01

Two T2-independentJ-difference lactate editing schemes for the PRESS magnetic resonance spectroscopy localization sequence are introduced. The techniques, which allow for simultaneous acquisition of the lactate doublet (1.3 ppm) and edited singlets upfield of and including choline (3.2 ppm), exploit the dependence of the in-phase intensity of the methyl doublet upon the time interval separating two inversion (BASING) pulses applied to its coupling partner after initial excitation. Editing method 1, which allows for echo times TE =n/J(n= 1, 2, 3, …), alters the BASING carrier frequency for each of two cycles so that, for one cycle, the quartet is inverted, whereas, for the other cycle, the quartet is unaffected. Method 2, which also provides water suppression, allows for editing for TE > 1/Jby alternating, between cycles, the time interval separating the inversion pulses. Experimental results were obtained at 1.5 T using a Shinnar Le-Roux-designed maximum phase inversion pulse with a filter transition bandwidth of 55 Hz. Spectra were acquired from phantoms andin vivofrom the human brain and neck. In a neck muscle study, the lipid suppression factor, achieved partly through the use of a novel phase regularization algorithm, was measured to be over 103. Spectra acquired from a primary brain and a metastatic neck tumor demonstrated the presence of lactate and choline signals consistent with abnormal spectral patterns. The advantages and limitations of the methods are analyzed theoretically and experimentally, and significance of the results is discussed.

Low-Frequency Carbon Recombination Lines in the Orion Molecular Cloud Complex

NASA Astrophysics Data System (ADS)

Tremblay, Chenoa D.; Jordan, Christopher H.; Cunningham, Maria; Jones, Paul A.; Hurley-Walker, Natasha

2018-05-01

We detail tentative detections of low-frequency carbon radio recombination lines from within the Orion molecular cloud complex observed at 99-129 MHz. These tentative detections include one alpha transition and one beta transition over three locations and are located within the diffuse regions of dust observed in the infrared at 100 μm, the Hα emission detected in the optical, and the synchrotron radiation observed in the radio. With these observations, we are able to study the radiation mechanism transition from collisionally pumped to radiatively pumped within the H ii regions within the Orion molecular cloud complex.

STEM tomography analysis of the trypanosome transition zone.

PubMed

Trépout, Sylvain; Tassin, Anne-Marie; Marco, Sergio; Bastin, Philippe

2018-04-01

The protist Trypanosoma brucei is an emerging model for the study of cilia and flagella. Here, we used scanning transmission electron microscopy (STEM) tomography to describe the structure of the trypanosome transition zone (TZ). At the base of the TZ, nine transition fibres irradiate from the B microtubule of each doublet towards the membrane. The TZ adopts a 9 + 0 structure throughout its length of ∼300 nm and its lumen contains an electron-dense structure. The proximal portion of the TZ has an invariant length of 150 nm and is characterised by a collarette surrounding the membrane and the presence of electron-dense material between the membrane and the doublets. The distal portion exhibits more length variation (from 55 to 235 nm) and contains typical Y-links. STEM analysis revealed a more complex organisation of the Y-links compared to what was reported by conventional transmission electron microscopy. Observation of the very early phase of flagellum assembly demonstrated that the proximal portion and the collarette are assembled early during construction. The presence of the flagella connector that maintains the tip of the new flagellum to the side of the old was confirmed and additional filamentous structures making contact with the membrane of the flagellar pocket were also detected. The structure and potential functions of the TZ in trypanosomes are discussed, as well as its mode of assembly. Copyright © 2017 Elsevier Inc. All rights reserved.

RECONCILIATION OF WAITING TIME STATISTICS OF SOLAR FLARES OBSERVED IN HARD X-RAYS

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

Aschwanden, Markus J.; McTiernan, James M., E-mail: aschwanden@lmsal.co, E-mail: jimm@ssl.berkeley.ed

2010-07-10

We study the waiting time distributions of solar flares observed in hard X-rays with ISEE-3/ICE, HXRBS/SMM, WATCH/GRANAT, BATSE/CGRO, and RHESSI. Although discordant results and interpretations have been published earlier, based on relatively small ranges (<2 decades) of waiting times, we find that all observed distributions, spanning over 6 decades of waiting times ({Delta}t {approx} 10{sup -3}-10{sup 3} hr), can be reconciled with a single distribution function, N({Delta}t) {proportional_to} {lambda}{sub 0}(1 + {lambda}{sub 0{Delta}}t){sup -2}, which has a power-law slope of p {approx} 2.0 at large waiting times ({Delta}t {approx} 1-1000 hr) and flattens out at short waiting times {Delta}t {approx}

Tubulin Glutamylation Regulates Ciliary Motility by Altering Inner Dynein Arm Activity

PubMed Central

Suryavanshi, Swati; Eddé, Bernard; Fox, Laura A.; Guerrero, Stella; Hard, Robert; Hennessey, Todd; Kabi, Amrita; Malison, David; Pennock, David; Sale, Winfield S.; Wloga, Dorota; Gaertig, Jacek

2010-01-01

SUMMMARY How microtubule-associated motor proteins are regulated is not well understood. A potential mechanism for spatial regulation of motor proteins is provided by post-translational modifications of tubulin subunits that form patterns on microtubules. Glutamylation is a conserved tubulin modification [1] that is enriched in axonemes. The enzymes responsible for this PTM, glutamic acid ligases (E-ligases), belong to a family of proteins with a tubulin tyrosine ligase (TTL) homology domain (TTL-like or TTLL proteins) [2]. We show that in cilia of Tetrahymena, TTLL6 E-ligases generate glutamylation mainly on the B-tubule of outer doublet microtubules, the site of force production by ciliary dynein. Deletion of two TTLL6 paralogs caused severe deficiency in ciliary motility associated with abnormal waveform and reduced beat frequency. In isolated axonemes with a normal dynein arm composition, TTLL6 deficiency did not affect the rate of ATP-induced doublet microtubule sliding. Unexpectedly, the same TTLL6 deficiency increased the velocity of microtubule sliding in axonemes that also lack outer dynein arms, in which forces are generated by inner dynein arms. We conclude that tubulin glutamylation on the B-tubule inhibits the net force imposed on sliding doublet microtubules by inner dynein arms. PMID:20189389

Deuterated silicon nitride photonic devices for broadband optical frequency comb generation

NASA Astrophysics Data System (ADS)

Chiles, Jeff; Nader, Nima; Hickstein, Daniel D.; Yu, Su Peng; Briles, Travis Crain; Carlson, David; Jung, Hojoong; Shainline, Jeffrey M.; Diddams, Scott; Papp, Scott B.; Nam, Sae Woo; Mirin, Richard P.

2018-04-01

We report and characterize low-temperature, plasma-deposited deuterated silicon nitride thin films for nonlinear integrated photonics. With a peak processing temperature less than 300$^\\circ$C, it is back-end compatible with pre-processed CMOS substrates. We achieve microresonators with a quality factor of up to $1.6\\times 10^6 $ at 1552 nm, and $>1.2\\times 10^6$ throughout $\\lambda$ = 1510 -- 1600 nm, without annealing or stress management. We then demonstrate the immediate utility of this platform in nonlinear photonics by generating a 1 THz free spectral range, 900-nm-bandwidth modulation-instability microresonator Kerr comb and octave-spanning, supercontinuum-broadened spectra.

Theory of beam plasma discharge

NASA Technical Reports Server (NTRS)

Papadopoulos, K.

1982-01-01

The general theory of beam plasma discharge (BPD) is discussed in relation to space and laboratory beam injection situations. An important concept introduced is that even when beam plasma instabilities are excited, there are two regime of BPD with radically different observational properties. They are described here as BPD with either classical or anomalous energy depositions. For high pressures or low altitudes, the classical is expected to dominate. For high altitudes and laboratory experiments, where the axial system size is less than lambda sub en, no BPD will be triggered unless the unstable waves are near the ambient plasma frequency and their amplitudes at saturation are large enough to create suprathermal tails by collapsing.

Ipsi- and Contralateral Motor Response Using Ultrasound-induced Neurostimulation in Deeply Anesthetized Mice

NASA Astrophysics Data System (ADS)

Kamimura, Hermes; Wang, Shutao; Chen, Hong; Wang, Qi; Aurup, Christian; Fan, Kathtleen; Carneiro, Antonio; Konofagou, Elisa

Ultrasound neurostimulation has been proven capable of eliciting motor responses. However, the studies in sedated rodents presented problems with target specificity due to the use of low ultrasound frequencies (<700 kHz). Here, we show that focused ultrasound (FUS) in mega-Hz range was able to evoke motor responses in mice under deep anesthesia. Contralateral movements of the hind limbs were observed when sonications were carried out at +2 mm of Lambda and ±2 mm lateral of midline in three mice. Moreover, stimulating other regions of the somatosensory and cerebellum induced trunk and ipsilateral limb movements in all six mice.

Large magnetic penetration depth and thermal fluctuations in a superconducting Ca10(Pt3As8)[(Fe1 xPtx)2As2]5 (x = 0.097) single crystal

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

Kim J.; Nazaretski E.; Ronning, F.

2012-05-18

We have measured the temperature dependence of the absolute value of the magnetic penetration depth {lambda}(T) in a Ca{sub 10}(Pt{sub 3}As{sub 8})[(Fe{sub 1-x}Pt{sub x}){sub 2}As{sub 2}]{sub 5} (x = 0.097) single crystal using a low-temperature magnetic force microscope (MFM). We obtain {lambda}{sub ab}(0) {approx} 1000 nm via extrapolating the data to T = 0. This large {lambda} and pronounced anisotropy in this system are responsible for large thermal fluctuations and the presence of a liquid vortex phase in this low-temperature superconductor with a critical temperature of 11 K, consistent with the interpretation of the electrical transport data. The superconducting parametersmore » obtained from {lambda} and coherence length {zeta} place this compound in the extreme type II regime. Meissner responses (via MFM) at different locations across the sample are similar to each other, indicating good homogeneity of the superconducting state on a submicron scale.« less

A search for close-mass lepton doublet

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

Riles, J.K.

1989-04-01

Described is a search for a heavy charged lepton with an associated neutrino of nearly the same mass, together known as a close-mass lepton doublet. The search is conducted in e/sup +/e/sup/minus// annihilation data taken with the Mark II detector at a center-of-mass energy of 29 GeV. In order to suppress contamination from conventional two-photon reactions, the search applies a novel, radiative-tagging technique. Requiring the presence of an isolated, energetic photon allows exploration for lepton doublets with a mass splitting smaller than that previously accessible to experiment. No evidence for such a new lepton has been found, enabling limits tomore » be placed on allowed mass combinations. Mass differences as low as 250-300 MeV are excluded for charged lepton masses up to 10 GeV. 78 refs., 64 figs., 8 tabs.« less

Miniature optical planar camera based on a wide-angle metasurface doublet corrected for monochromatic aberrations

PubMed Central

Arbabi, Amir; Arbabi, Ehsan; Kamali, Seyedeh Mahsa; Horie, Yu; Han, Seunghoon; Faraon, Andrei

2016-01-01

Optical metasurfaces are two-dimensional arrays of nano-scatterers that modify optical wavefronts at subwavelength spatial resolution. They are poised to revolutionize optics by enabling complex low-cost systems where multiple metasurfaces are lithographically stacked and integrated with electronics. For imaging applications, metasurface stacks can perform sophisticated image corrections and can be directly integrated with image sensors. Here we demonstrate this concept with a miniature flat camera integrating a monolithic metasurface lens doublet corrected for monochromatic aberrations, and an image sensor. The doublet lens, which acts as a fisheye photographic objective, has a small f-number of 0.9, an angle-of-view larger than 60° × 60°, and operates at 850 nm wavelength with 70% focusing efficiency. The camera exhibits nearly diffraction-limited image quality, which indicates the potential of this technology in the development of optical systems for microscopy, photography, and computer vision. PMID:27892454

Collider signatures of flavorful Higgs bosons

DOE PAGES

Altmannshofer, Wolfgang; Eby, Joshua; Gori, Stefania; ...

2016-12-30

Motivated by our limited knowledge of the Higgs couplings to the first two generation fermions, we analyze the collider phenomenology of a class of two Higgs doublet models (2HDMs) with a nonstandard Yukawa sector. One Higgs doublet is mainly responsible for the masses of the weak gauge bosons and the third-generation fermions, while the second Higgs doublet provides mass for the lighter fermion generations. The characteristic collider signatures of this setup differ significantly from well-studied 2HDMs with natural flavor conservation, flavor alignment, or minimal flavor violation. New production mechanisms for the heavy scalar, pseudoscalar, and charged Higgs involving second-generation quarksmore » can become dominant. The most interesting decay modes include H/A → cc,tc,μμ,τμ and H ± → cb,cs,μν. As a result, searches for low-mass dimuon resonances are currently among the best probes of the heavy Higgs bosons in this setup.« less

Miniature optical planar camera based on a wide-angle metasurface doublet corrected for monochromatic aberrations

NASA Astrophysics Data System (ADS)

Arbabi, Amir; Arbabi, Ehsan; Kamali, Seyedeh Mahsa; Horie, Yu; Han, Seunghoon; Faraon, Andrei

2016-11-01

Optical metasurfaces are two-dimensional arrays of nano-scatterers that modify optical wavefronts at subwavelength spatial resolution. They are poised to revolutionize optics by enabling complex low-cost systems where multiple metasurfaces are lithographically stacked and integrated with electronics. For imaging applications, metasurface stacks can perform sophisticated image corrections and can be directly integrated with image sensors. Here we demonstrate this concept with a miniature flat camera integrating a monolithic metasurface lens doublet corrected for monochromatic aberrations, and an image sensor. The doublet lens, which acts as a fisheye photographic objective, has a small f-number of 0.9, an angle-of-view larger than 60° × 60°, and operates at 850 nm wavelength with 70% focusing efficiency. The camera exhibits nearly diffraction-limited image quality, which indicates the potential of this technology in the development of optical systems for microscopy, photography, and computer vision.

Modification of the Douglas Neumann program to improve the efficiency of predicting component interference and high lift characteristics

NASA Technical Reports Server (NTRS)

Bristow, D. R.; Grose, G. G.

1978-01-01

The Douglas Neumann method for low-speed potential flow on arbitrary three-dimensional lifting bodies was modified by substituting the combined source and doublet surface paneling based on Green's identity for the original source panels. Numerical studies show improved accuracy and stability for thin lifting surfaces, permitting reduced panel number for high-lift devices and supercritical airfoil sections. The accuracy of flow in concave corners is improved. A method of airfoil section design for a given pressure distribution, based on Green's identity, was demonstrated. The program uses panels on the body surface with constant source strength and parabolic distribution of doublet strength, and a doublet sheet on the wake. The program is written for the CDC CYBER 175 computer. Results of calculations are presented for isolated bodies, wings, wing-body combinations, and internal flow.

A new semiclassical decoupling scheme for electronic transitions in molecular collisions - Application to vibrational-to-electronic energy transfer

NASA Technical Reports Server (NTRS)

Lee, H.-W.; Lam, K. S.; Devries, P. L.; George, T. F.

1980-01-01

A new semiclassical decoupling scheme (the trajectory-based decoupling scheme) is introduced in a computational study of vibrational-to-electronic energy transfer for a simple model system that simulates collinear atom-diatom collisions. The probability of energy transfer (P) is calculated quasiclassically using the new scheme as well as quantum mechanically as a function of the atomic electronic-energy separation (lambda), with overall good agreement between the two sets of results. Classical mechanics with the new decoupling scheme is found to be capable of predicting resonance behavior whereas an earlier decoupling scheme (the coordinate-based decoupling scheme) failed. Interference effects are not exhibited in P vs lambda results.

Understanding the magnetism in noncentrosymmetric CeIrGe3: Muon spin relaxation and neutron scattering studies

NASA Astrophysics Data System (ADS)

Anand, V. K.; Hillier, A. D.; Adroja, D. T.; Khalyavin, D. D.; Manuel, P.; Andre, G.; Rols, S.; Koza, M. M.

2018-05-01

The magnetic properties of a pressure induced noncentrosymmetric heavy-fermion superconductor CeIrGe3 have been investigated by muon spin relaxation (μ SR ), powder neutron diffraction (ND), and inelastic neutron scattering (INS) techniques at ambient pressure. For completeness we have also measured the ac magnetic susceptibility χac(T ) , dc magnetic susceptibility χ (T ) , dc isothermal magnetization M (H ) , and heat capacity Cp(T ,H ) down to 2 K. CeIrGe3 is known to exhibit pressure induced superconductivity (Tc≈1.5 K) at a pressure of 20 GPa and antiferromagnetic ordering at 8.7 K, 4.7 K, and 0.7 K at ambient pressure. Our χac(T ) and χ (T ) data show an additional anomaly near 6.2 K which is also captured in Cp(T ) data. From χac(T ) , χ (T ) , and Cp(T ) measurements we infer three antiferromagnetic transitions above 2 K at TN 1=8.5 K, TN 2=6.0 K, and TN 3=4.6 K. Our μ SR study also confirms the presence of three transitions through the observation of one frequency for TN 2

Extremely high frequency electromagnetic radiation enforces bacterial effects of inhibitors and antibiotics.

PubMed

Tadevosyan, Hasmik; Kalantaryan, Vitaly; Trchounian, Armen

2008-01-01

The coherent electromagnetic radiation (EMR) of the frequency of 51.8 and 53 GHz with low intensity (the power flux density of 0.06 mW/cm(2)) affected the growth of Escherichia coli K12(lambda) under fermentation conditions: the lowering of the growth specific rate was considerably (approximately 2-fold) increased with exposure duration of 30-60 min; a significant decrease in the number of viable cells was also shown. Moreover, the enforced effects of the N,N'-dicyclohexylcarbodiimide (DCCD), inhibitor of H(+)-transporting F(0)F(1)-ATPase, on energy-dependent H(+) efflux by whole cells and of antibiotics like tetracycline and chloramphenicol on the following bacterial growth and survival were also determined after radiation. In addition, the lowering in DCCD-inhibited ATPase activity of membrane vesicles from exposed cells was defined. The results confirmed the input of membranous changes in bacterial action of low intensity extremely high frequency EMR, when the F(0)F(1)-ATPase is probably playing a key role. The radiation of bacteria might lead to changed metabolic pathways and to antibiotic resistance. It may also give bacteria with a specific role in biosphere.

Sensitivity enhancement in whole-body natural abundance 13C spectroscopy using 13C/1H double-resonance techniques at 4 tesla.

PubMed

Bomsdorf, H; Röschmann, P; Wieland, J

1991-11-01

In vivo 13C spectroscopy experiments were performed using a whole-body MR system at a static field of 4 T. The main goal of the investigations was to evaluate the sensitivity increase achievable by means of 13C/1H double-resonance techniques at 4 T. Spectra from subcutaneous fat as well as muscle glycogen from the lower leg were acquired using frequency selective proton decoupling and the polarization transfer method SINEPT. With respect to measurements on subcutaneous fat, polarization transfer turned out to be more efficient than selective decoupling. About a fourfold enhancement in spectral peak intensity for the C = C line doublet of the unsaturated fatty acid chain was obtained. Combining polarization transfer with decoupling yielded a factor of 6 in signal amplitude. In contrast to that, the signal enhancement observed in measurements on the glycogen C-1 resonance was only around twofold. The lower efficiency is explained by fast T2 relaxation of the proton transition. A T2 value of about 3 ms was derived from the experimental data. Acquisition times as low as 3 min were realized for normal level glycogen in human calf muscle, enabling a time resolution adequate for dynamic studies on muscle glycogen depletion. Aspects of RF power absorption in tissue and the generally higher efficiency make polarization transfer methods preferable to selective decoupling in whole-body 13C spectroscopy at 4 T.

The electronic structure of vanadium monochloride cation (VCl{sup +}): Tackling the complexities of transition metal species

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

DeYonker, Nathan J., E-mail: ndyonker@memphis.edu; Halfen, DeWayne T.; Ziurys, Lucy M.

Six electronic states (X {sup 4}Σ{sup −}, A {sup 4}Π, B {sup 4}Δ, {sup 2}Φ, {sup 2}Δ, {sup 2}Σ{sup +}) of the vanadium monochloride cation (VCl{sup +}) are described using large basis set coupled cluster theory. For the two lowest quartet states (X {sup 4}Σ{sup −} and A {sup 4}Π), a focal point analysis (FPA) approach was used that conjoined a correlation-consistent family of basis sets up to aug-cc-pwCV5Z-DK with high-order coupled cluster theory through pentuple (CCSDTQP) excitations. FPA adiabatic excitation energies (T{sub 0}) and spectroscopic constants (r{sub e}, r{sub 0}, B{sub e}, B{sub 0}, D{sup ¯}{sub e}, H{sub e},more » ω{sub e}, v{sub 0}, α{sub e}, ω{sub e}x{sub e}) were extrapolated to the valence complete basis set Douglas-Kroll (DK) aug-cc-pV∞Z-DK CCSDT level of theory, and additional treatments accounted for higher-order valence electron correlation, core correlation, and spin-orbit coupling. Due to the delicate interplay between dynamical and static electronic correlation, single reference coupled cluster theory is able to provide the correct ground electronic state (X {sup 4}Σ{sup −}), while multireference configuration interaction theory cannot. Perturbations from the first- and second-order spin orbit coupling of low-lying states with quartet spin multiplicity reveal an immensely complex rotational spectrum relative to the isovalent species VO, VS, and TiCl. Computational data on the doublet manifold suggest that the lowest-lying doublet state ({sup 2}Γ) has a T{sub e} of ∼11 200 cm{sup −1}. Overall, this study shows that laboratory and theoretical rotational spectroscopists must work more closely in tandem to better understand the bonding and structure of molecules containing transition metals.« less

Flexible body stability analysis of Space Shuttle ascent flight control system by using lambda matrix solution techniques

NASA Technical Reports Server (NTRS)

Bown, R. L.; Christofferson, A.; Lardas, M.; Flanders, H.

1980-01-01

A lambda matrix solution technique is being developed to perform an open loop frequency analysis of a high order dynamic system. The procedure evaluates the right and left latent vectors corresponding to the respective latent roots. The latent vectors are used to evaluate the partial fraction expansion formulation required to compute the flexible body open loop feedback gains for the Space Shuttle Digital Ascent Flight Control System. The algorithm is in the final stages of development and will be used to insure that the feedback gains meet the design specification.

Features of the low-frequency polarization response in the region of the ferroelectric phase transition in multiferroic TbMnO 3

DOE PAGES

Trepakov, V. A.; Kvyatkovskii, O. E.; Savinov, M. E.; ...

2016-10-01

The unusual behavior of the low-frequency (10 Hz–1 MHz) permittivity in single crystals of ferroelectric multiferroic TbMnO3 has been experimentally and theoretically studied in detail in the region of the narrow temperature peak of the permittivity, associated with the ferroelectric phase transition (T C ~ 27.4 K). It has been found that the ε c(ω, T) maximum sharply decreases with increasing measured field frequency, while the temperature position of the maximum is independent of frequency. It has been shown that the observed features of the polarization response can be satisfactorily described within the Landau–Khalatnikov polarization relaxation theory.

Molecules in high spin states III: the millimeter/submillimeter-wave spectrum of the MnCl radical (X (7)Sigma(+)).

PubMed

Halfen, D T; Ziurys, L M

2005-02-01

The pure rotational spectrum of the MnCl radical (X (7)Sigma(+)) has been recorded in the range 141-535 GHz using millimeter-submillimeter direct absorption spectroscopy. This work is the first time the molecule has been studied with rotational resolution in its ground electronic state. MnCl was synthesized by the reaction of manganese vapor, produced in a Broida-type oven, with Cl(2). Transitions of both chlorine isotopomers were measured, as well as lines originating in several vibrationally excited states. The presence of several spin components and manganese hyperfine interactions resulted in quite complex spectra, consisting of multiple blended features. Because 42 rotational transitions were measured for Mn(35)Cl over a wide range of frequencies with high signal-to-noise, a very accurate set of rotational, fine structure, and hyperfine constants could be determined with the aid of spectral simulations. Spectroscopic constants were also determined for Mn(37)Cl and several vibrationally excited states. The values of the spin-rotation and spin-spin parameters were found to be relatively small (gamma=11.2658 MHz and lambda=1113.10 MHz for Mn(35)Cl); in the case of lambda, excited electronic states contributing to the second-order spin-orbit interaction may be canceling each other. The Fermi contact hyperfine term was found to be large in manganese chloride with b(F)(Mn(35)Cl)=397.71 MHz, a result of the manganese 4s character mixing into the 12sigma orbital. This orbital is spsigma hybridized, and contains some Mn 4psigma character, as well. Hence, it also contributes to the dipolar constant c, which is small and positive for this radical (c=32.35 MHz for Mn(35)Cl). The hyperfine parameters in MnCl are similar to those of MnH and MnF, suggesting that the bonding in these three molecules is comparable.

Direct measurement of sub-Debye-length attraction between oppositely charged surfaces.

PubMed

Kampf, Nir; Ben-Yaakov, Dan; Andelman, David; Safran, S A; Klein, Jacob

2009-09-11

Using a surface force balance with fast video analysis, we have measured directly the attractive forces between oppositely charged solid surfaces (charge densities sigma(+), sigma(-)) across water over the entire range of interaction, in particular, at surface separations D below the Debye screening length lambda(S). At very low salt concentration we find a long-ranged attraction between the surfaces (onset ca. 100 nm), whose variation at D

Skylight and aerosol in Thailand during the dry winter season.

PubMed

Volz, F; Sheehan, L

1971-02-01

Solar and skylight measurements were made in southern Thailand from late February to early April of 1969. The aerosol optical density (basis 10) was rather large, ranging from 0.07 to 0.28 at lambda0.5 microm and varied with about lambda(-2) in the range 0.5 < lambda < 1.6 microm. The skylight scattering phase function was relatively flat and showed little spectral dependence. The log aerosol size distribution seems close to r(-4). The origin of the turbid low level air from the South China Sea and Philippine Sea poses the question of the nature of the aerosol.

Thermal phase transition with full 2-loop effective potential

NASA Astrophysics Data System (ADS)

Laine, M.; Meyer, M.; Nardini, G.

2017-07-01

Theories with extended Higgs sectors constructed in view of cosmological ramifications (gravitational wave signal, baryogenesis, dark matter) are often faced with conflicting requirements for their couplings; in particular those influencing the strength of a phase transition may be large. Large couplings compromise perturbative studies, as well as the high-temperature expansion that is invoked in dimensionally reduced lattice investigations. With the example of the inert doublet extension of the Standard Model (IDM), we show how a resummed 2-loop effective potential can be computed without a high-T expansion, and use the result to scrutinize its accuracy. With the exception of Tc, which is sensitive to contributions from heavy modes, the high-T expansion is found to perform well. 2-loop corrections weaken the transition in IDM, but they are moderate, whereby a strong transition remains an option.

Beyond [lambda][subscript max] Part 2: Predicting Molecular Color

ERIC Educational Resources Information Center

Williams, Darren L.; Flaherty, Thomas J.; Alnasleh, Bassam K.

2009-01-01

A concise roadmap for using computational chemistry programs (i.e., Gaussian 03W) to predict the color of a molecular species is presented. A color-predicting spreadsheet is available with the online material that uses transition wavelengths and peak-shape parameters to predict the visible absorbance spectrum, transmittance spectrum, chromaticity…

Possibility of the amplification of the radiation at the wave length lambda = 1776 A in recombining plasma (in Russian)

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

Gudzenko, L.I.; Evstigneev, V.V.; Yakovlenko, S.I.

1973-09-01

A calculation is made of the characteristics of the amplification of the radiation in the vaccum ultraviolet spectral range in the 2s-2p transition of Be ions in supercooled (intensely recombining) dense Be plasma. (tr-auth)

Comparing two tetraalkylammonium ionic liquids. II. Phase transitions.

PubMed

Lima, Thamires A; Paschoal, Vitor H; Faria, Luiz F O; Ribeiro, Mauro C C; Ferreira, Fabio F; Costa, Fanny N; Giles, Carlos

2016-06-14

Phase transitions of the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N1114][NTf2], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N1444][NTf2], were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) measurements, and Raman spectroscopy. XRD and Raman spectra were obtained as a function of temperature at atmospheric pressure, and also under high pressure at room temperature using a diamond anvil cell (DAC). [N1444][NTf2] experiences glass transition at low temperature, whereas [N1114][NTf2] crystallizes or not depending on the cooling rate. Both the ionic liquids exhibit glass transition under high pressure. XRD and low-frequency Raman spectra provide a consistent physical picture of structural ordering-disordering accompanying the thermal events of crystallization, glass transition, cold crystallization, pre-melting, and melting. Raman spectra in the high-frequency range of some specific cation and anion normal modes reveal conformational changes of the molecular structures along phase transitions.

Noise-Enhanced Measurement of Weak Doublet Spectra with a Fourier-Transform Spectrometer and a 1-Bit Analog-to-Digital Converter.

PubMed

Lim, M; Saloma, C

2001-04-10

We demonstrate an efficient noise dithering procedure for measuring the power spectrum of a weak spectral doublet with a Fourier-transform spectrometer in which the subthreshold interferogram is measured by a 1-bit analog-to-digital converter without oversampling. In the absence of noise, no information is obtained regarding the doublet spectrum because the modulation term s(x) of its interferogram is below the instrumental detection limit B, i.e., |s(x)| < B, for all path difference x values. Extensive numerical experiments are carried out concerning the recovery of the doublet power spectrum that is represented by s(x) = (s(0)/2)exp(-pi(2)x(2)/beta)[cos(2pif(1)x) + cos(2pif(2)x)], where s(0) is a constant, beta is the linewidth factor, and ?f? = (f(1) + f(2))/2. Different values of ?f?, s(0), and beta are considered to evaluate thoroughly the accuracy of the procedure to determine the unknown values of f(1) and f(2), the spectral linewidth, and the peak values of the spectral profiles. Our experiments show that, even for short observation times, the resonant frequencies of s(x) could be located with high accuracy over a wide range of ?f? and beta values. Signal-to-noise ratios as high as 50 are also gained for the recovered power spectra. The performance of the procedure is also analyzed with respect to another method that recovers the amplitude values of s(x) directly.

Evaluation of Shortwave Infrared Atmospheric Correction for Ocean Color Remote Sensing of Chesapeake Bay

NASA Technical Reports Server (NTRS)

Werdell, P. Jeremy; Franz, Bryan A.; Bailey, Sean W.

2010-01-01

The NASA Moderate Resolution Imaging Spectroradiometer onboard the Aqua platform (MODIS-Aqua) provides a viable data stream for operational water quality monitoring of Chesapeake Bay. Marine geophysical products from MODIS-Aqua depend on the efficacy of the atmospheric correction process, which can be problematic in coastal environments. The operational atmospheric correction algorithm for MODIS-Aqua requires an assumption of negligible near-infrared water-leaving radiance, nL(sub w)(NIR). This assumption progressively degrades with increasing turbidity and, as such, methods exist to account for non-negligible nL(sub w)(NIR) within the atmospheric correction process or to use alternate radiometric bands where the assumption is satisfied, such as those positioned within shortwave infrared (SWIR) region of the spectrum. We evaluated a decade-long time-series of nL(sub w)(lambda) from MODIS-Aqua in Chesapeake Bay derived using NIR and SWIR bands for atmospheric correction. Low signal-to-noise ratios (SNR) for the SWIR bands of MODIS-Aqua added noise errors to the derived radiances, which produced broad, flat frequency distributions of nL(sub w)(lambda) relative to those produced using the NIR bands. The SWIR approach produced an increased number of negative nL(sub w)(lambda) and decreased sample size relative to the NIR approach. Revised vicarious calibration and regional tuning of the scheme to switch between the NIR and SWIR approaches may improve retrievals in Chesapeake Bay, however, poor SNR values for the MODIS-Aqua SWIR bands remain the primary deficiency of the SWIR-based atmospheric correction approach.

Cholinergic dysfunctions and enhanced oxidative stress in the neurobehavioral toxicity of lambda-cyhalothrin in developing rats.

PubMed

Ansari, Reyaz W; Shukla, Rajendra K; Yadav, Rajesh S; Seth, Kavita; Pant, Aditya B; Singh, Dhirendra; Agrawal, Ashok K; Islam, Fakhrul; Khanna, Vinay K

2012-11-01

This study is focused on understanding the mechanism of neurobehavioral toxicity of lambda-cyhalothrin, a new generation type II synthetic pyrethroid in developing rats following their exposure from post-lactational day (PLD)22 to PLD49 and investigate whether neurobehavioral alterations are transient or persistent. Post-lactational exposure to lambda-cyhalothrin (1.0 or 3.0 mg/kg body weight, p.o.) affected grip strength and learning activity in rats on PLD50 and the persistent impairment of grip strength and learning was observed at 15 days after withdrawal of exposure on PLD65. A decrease in the binding of muscarinic-cholinergic receptors in frontocortical, hippocampal, and cerebellar membranes associated with decreased expression of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) in hippocampus was observed following exposure to lambda-cyhalothrin on PLD50 and PLD65. Exposure to lambda-cyhalothrin was also found to increase the expression of growth-associated protein-43 in hippocampus of rats on PLD50 and PLD65 as compared to controls. A significant increase in lipid peroxidation and protein carbonyl levels and decreased levels of reduced glutathione and activity of superoxide dismutase, catalase, and glutathione peroxidase in brain regions of lambda-cyhalothrin exposed rats were distinctly observed indicating increased oxidative stress. Inhibition of ChAT and AChE activity may cause down-regulation of muscarinic-cholinergic receptors consequently impairing learning activity in developing rats exposed to lambda-cyhalothrin. The data further indicate that long-term exposure to lambda-cyhalothrin at low doses may be detrimental and changes in selected behavioral and neurochemical end points may persist if exposure to lambda-cyhalothrin continues.

Wideband Array for C, X, and Ku-Band Applications with 5.3:1 Bandwidth

NASA Technical Reports Server (NTRS)

Novak, Markus H.; Volakis, John L.; Miranda, Felix A.

2015-01-01

Planar arrays that exploit strong intentional coupling between elements have allowed for very wide bandwidths in low-profile configurations. However, such designs also require complex impedance matching networks that must also be very compact. For many space applications, typically occurring at C-, X-, Ku-, and most recently at Ka-band, such designs require specialized and expensive fabrication techniques. To address this issue, a novel ultra-wideband array is presented, using a simplified feed network to reduce fabrication cost. The array operates from 3.5-18.5 GHz with VSWR less than 2.4 at broadside, and is of very low profile, having a total height of lambda/10 at the lowest frequency of operation. Validation is provided using a 64-element prototype array, fabricated using common Printed Circuit Board (PCB) technology. The low size, weight, and cost of this array make it attractive for space-borne applications.

Harmonic surface acoustic waves on gallium nitride thin films.

PubMed

Justice, Joshua; Lee, Kyoungnae; Korakakis, D

2012-08-01

SAW devices operating at the fundamental frequency and the 5th, 7th, 9th, and 11th harmonics have been designed, fabricated, and measured. Devices were fabricated on GaN thin films on sapphire substrates, which were grown via metal organic vapor phase epitaxy (MOVPE). Operating frequencies of 230, 962, 1338, 1720, and 2100 MHz were achieved with devices that had a fundamental wavelength, lambda0 = 20 μm. Gigahertz operation is realized with relatively large interdigital transducers that do not require complicated submicrometer fabrication techniques. SAW devices fabricated on the GaN/sapphire bilayer have an anisotropic propagation when the wavelength is longer than the GaN film thickness. It is shown that for GaN thin films, where kh(GaN) > 10 (k = 2pi/lambda and h(GaN) = GaN film thickness), effects of the substrate on the SAW propagation are eliminated. Bulk mode suppression at harmonic operation is also demonstrated.

Birefringence of single and bundled microtubules.

PubMed

Oldenbourg, R; Salmon, E D; Tran, P T

1998-01-01

We have measured the birefringence of microtubules (MTs) and of MT-based macromolecular assemblies in vitro and in living cells by using the new Pol-Scope. A single microtubule in aqueous suspension and imaged with a numerical aperture of 1.4 had a peak retardance of 0.07 nm. The peak retardance of a small bundle increased linearly with the number of MTs in the bundle. Axonemes (prepared from sea urchin sperm) had a peak retardance 20 times higher than that of single MTs, in accordance with the nine doublets and two singlets arrangement of parallel MTs in the axoneme. Measured filament retardance decreased when the filament was defocused or the numerical aperture of the imaging system was decreased. However, the retardance "area," which we defined as the image retardance integrated along a line perpendicular to the filament axis, proved to be independent of focus and of numerical aperture. These results are in good agreement with a theory that we developed for measuring retardances with imaging optics. Our theoretical concept is based on Wiener's theory of mixed dielectrics, which is well established for nonimaging applications. We extend its use to imaging systems by considering the coherence region defined by the optical set-up. Light scattered from within that region interferes coherently in the image point. The presence of a filament in the coherence region leads to a polarization dependent scattering cross section and to a finite retardance measured in the image point. Similar to resolution measurements, the linear dimension of the coherence region for retardance measurements is on the order lambda/(2 NA), where lambda is the wavelength of light and NA is the numerical aperture of the illumination and imaging lenses.

Birefringence of single and bundled microtubules.

PubMed Central

Oldenbourg, R; Salmon, E D; Tran, P T

1998-01-01

We have measured the birefringence of microtubules (MTs) and of MT-based macromolecular assemblies in vitro and in living cells by using the new Pol-Scope. A single microtubule in aqueous suspension and imaged with a numerical aperture of 1.4 had a peak retardance of 0.07 nm. The peak retardance of a small bundle increased linearly with the number of MTs in the bundle. Axonemes (prepared from sea urchin sperm) had a peak retardance 20 times higher than that of single MTs, in accordance with the nine doublets and two singlets arrangement of parallel MTs in the axoneme. Measured filament retardance decreased when the filament was defocused or the numerical aperture of the imaging system was decreased. However, the retardance "area," which we defined as the image retardance integrated along a line perpendicular to the filament axis, proved to be independent of focus and of numerical aperture. These results are in good agreement with a theory that we developed for measuring retardances with imaging optics. Our theoretical concept is based on Wiener's theory of mixed dielectrics, which is well established for nonimaging applications. We extend its use to imaging systems by considering the coherence region defined by the optical set-up. Light scattered from within that region interferes coherently in the image point. The presence of a filament in the coherence region leads to a polarization dependent scattering cross section and to a finite retardance measured in the image point. Similar to resolution measurements, the linear dimension of the coherence region for retardance measurements is on the order lambda/(2 NA), where lambda is the wavelength of light and NA is the numerical aperture of the illumination and imaging lenses. PMID:9449366

KECK ECHELLETTE SPECTROGRAPH AND IMAGER OBSERVATIONS OF METAL-POOR DAMPED Ly{alpha} SYSTEMS

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

Penprase, Bryan E.; Toro-Martinez, Irene; Beeler, Daniel J.

2010-09-20

We present the first results from a survey of SDSS quasars selected for strong H I damped Ly{alpha} (DLA) absorption with corresponding low equivalent width absorption from strong low-ion transitions (e.g., C II {lambda}1334 and Si II {lambda}1260). These metal-poor DLA candidates were selected from the SDSS fifth release quasar spectroscopic database, and comprise a large new sample for probing low-metallicity galaxies. Medium-resolution echellette spectra from the Keck Echellette Spectrograph and Imager spectrograph for an initial sample of 35 systems were obtained to explore the metal-poor tail of the DLA distribution and to investigate the nucleosynthetic patterns at these metallicities.more » We have estimated saturation corrections for the moderately underresolved spectra, and systems with very narrow Doppler parameters (b {<=} 5 km s{sup -1}) will likely have underestimated abundances. For those systems with Doppler parameters b > 5 km s{sup -1}, we have measured low-metallicity DLA gas with [X/H] <-2.4 for at least one of C, O, Si, or Fe. Assuming non-saturated components, we estimate that several DLA systems have [X/H] <-2.8, including five DLA systems with both low equivalent widths and low metallicity in transitions of both C II and O I. All of the measured DLA metallicities, however, exceed or are consistent with a metallicity of at least 1/1000 of solar, regardless of the effects of saturation in our spectra. Our results indicate that the metal-poor tail of galaxies at z {approx} 3 drops exponentially at [X/H] {approx}<-3. If the distribution of metallicity is Gaussian, the probability of identifying interstellar medium gas with lower abundance is extremely small, and our results suggest that DLA systems with [X/H] < -4.0 are extremely rare, and could comprise only 8 x 10{sup -7} of DLA systems. The relative abundances of species within these low-metallicity DLA systems are compared with stellar nucleosynthesis models, and are consistent with stars having masses of 30 M{sub sun} < M{sub *} < 100 M{sub sun}. The observed ratio of [C/O] for values of [O/H] <-2.5 exceeds values seen in moderate metallicity DLA systems, and also exceeds theoretical nucleosynthesis predictions for higher mass Population III stars. We also have observed a correlation between the column density N(C IV) with [Si/H] metallicity, suggestive of a trend between mass of the DLA system and its metallicity.« less

Flight data identification of six degree-of-freedom stability and control derivatives of a large crane type helicopter

NASA Technical Reports Server (NTRS)

Tomaine, R. L.

1976-01-01

Flight test data from a large 'crane' type helicopter were collected and processed for the purpose of identifying vehicle rigid body stability and control derivatives. The process consisted of using digital and Kalman filtering techniques for state estimation and Extended Kalman filtering for parameter identification, utilizing a least squares algorithm for initial derivative and variance estimates. Data were processed for indicated airspeeds from 0 m/sec to 152 m/sec. Pulse, doublet and step control inputs were investigated. Digital filter frequency did not have a major effect on the identification process, while the initial derivative estimates and the estimated variances had an appreciable effect on many derivative estimates. The major derivatives identified agreed fairly well with analytical predictions and engineering experience. Doublet control inputs provided better results than pulse or step inputs.

Intramolecular H-transfer reactions in Si 2H n (for n=3-5)

NASA Astrophysics Data System (ADS)

Ernst, M. C.; Sax, A. F.; Kalcher, J.

1993-12-01

Intramolecular rearrangement reactions for doublet Si 2H 5 and Si 2H 3, quartet Si 2H 3, and singlet Si 2H 4 have been studied. aim of the study was to characterize a series of intramolecular H-transfer reactions in silicon hydrides with vrying degrees of saturation. The transition states belonging to the reactions presented in this work possess a monobridged Si 2H moiety. Structural features of the transition states and relative barrier heights have been examined; the geometry optimizations were performed with the use of CAS-SCF wavefunctions and the barrier height estimates were obtained with single-point CI calculations.

Vortices in Long Josephson Junctions.

DTIC Science & Technology

1987-11-01

of the very low impedance vortex flow transistor and toward determination of its potential for high frequency applications. Capability for higher...version. New progress was made toward solution of the problems of high frequency testing of the very low impedance vortex flow transistor and towards... measurable transresistance ’". out to frequencies of about 10% of the theoretical transit time cutoff fre- quency. Capability for higher frequency testing

Effects of sample size on estimates of population growth rates calculated with matrix models.

PubMed

Fiske, Ian J; Bruna, Emilio M; Bolker, Benjamin M

2008-08-28

Matrix models are widely used to study the dynamics and demography of populations. An important but overlooked issue is how the number of individuals sampled influences estimates of the population growth rate (lambda) calculated with matrix models. Even unbiased estimates of vital rates do not ensure unbiased estimates of lambda-Jensen's Inequality implies that even when the estimates of the vital rates are accurate, small sample sizes lead to biased estimates of lambda due to increased sampling variance. We investigated if sampling variability and the distribution of sampling effort among size classes lead to biases in estimates of lambda. Using data from a long-term field study of plant demography, we simulated the effects of sampling variance by drawing vital rates and calculating lambda for increasingly larger populations drawn from a total population of 3842 plants. We then compared these estimates of lambda with those based on the entire population and calculated the resulting bias. Finally, we conducted a review of the literature to determine the sample sizes typically used when parameterizing matrix models used to study plant demography. We found significant bias at small sample sizes when survival was low (survival = 0.5), and that sampling with a more-realistic inverse J-shaped population structure exacerbated this bias. However our simulations also demonstrate that these biases rapidly become negligible with increasing sample sizes or as survival increases. For many of the sample sizes used in demographic studies, matrix models are probably robust to the biases resulting from sampling variance of vital rates. However, this conclusion may depend on the structure of populations or the distribution of sampling effort in ways that are unexplored. We suggest more intensive sampling of populations when individual survival is low and greater sampling of stages with high elasticities.

Liquid-air partition coefficients of 1,1-difluoroethane (HFC152a), 1,1,1-trifluoroethane (HFC143a), 1,1,1,2-tetrafluoroethane (HFC134a), 1,1,1,2,2-pentafluoroethane (HFC125) and 1,1,1,3,3-pentafluoropropane (HFC245fa).

PubMed

Ernstgård, Lena; Lind, Birger; Andersen, Melvin E; Johanson, Gunnar

2010-01-01

Blood-air and tissue-blood coefficients (lambda) are essential to characterize the uptake and disposition of volatile substances, e.g. by physiologically based pharmacokinetic (PBPK) modelling. Highly volatile chemicals, including many hydrofluorocarbons (HFC) have low solubility in liquid media. These characteristics pose challenges for determining lambda values. A modified head-space vial equilibrium method was used to determine lambda values for five widely used HFCs. The method is based on automated head-space gas chromatography and injection of equal amount of chemical in two head-space vials with identical air phase volumes but different volumes of the liquid phase. The liquids used were water (physiological saline), fresh human blood, and olive oil. The average lambda values (n = 8) were as follows: 1,1-difluoroethane (HFC152a) - 1.08 (blood-air), 1.11 (water-air) and 5.6 (oil-air); 1,1,1-trifluoroethane (HFC143a) - 0.15, 0.15 and 1.90; 1,1,1,2-tetrafluoroethane (HFC134a) - 0.36, 0.35 and 3.5; 1,1,1,2,2-pentafluoroethane (HFC125) - 0.083, 0.074 and 1.71; and 1,1,1,3,3-pentafluoropropane (HFC245fa) - 0.62, 0.58 and 12.1. The lambda values appeared to be concentration-independent in the investigated range (2-200 ppm). In spite of the low lambda values, the method errors were modest, with coefficients of variation of 9, 11 and 10% for water, blood and oil, respectively.

Terahertz Spectroscopy of CrH (X 6Σ+) and AlH (X 1Σ+)

NASA Astrophysics Data System (ADS)

Halfen, D. T.; Ziurys, L. M.

2016-12-01

New laboratory measurements of hydrides have been carried out using terahertz direct absorption spectroscopy. Spin components of the N=2≤ftarrow 1 transition of the free radical CrH (X 6Σ+) have been recorded in the range 730-734 GHz, as well as a new measurement of the J=2≤ftarrow 1 line of AlH (X 1Σ+) near 755 GHz. Both species were created in an AC discharge of H2, argon, and metal vapor. For CrH, the chromium source was Cr(CO)6, while AlH was produced from Al(CH3)3. The J=4.5≤ftarrow 3.5 and 3.5≤ftarrow 2.5 fine-structure components were recorded for CrH, each which consists of resolved proton hyperfine doublets. For AlH, the two main quadrupole components, F=4.5≤ftarrow 3.5 and 3.5≤ftarrow 2.5, of the J=2≤ftarrow 1 transition were observed as blended features. These data were analyzed with previous 1≤ftarrow 0 millimeter/submillimeter measurements with 6Σ and 1Σ Hamiltonians for chromium and aluminum hydrides, respectively, and rotational, fine-structure (CrH only), and hyperfine constants were derived. The new measurements have resulted in refined spectroscopic parameters for both species, as well as direct measurement of the respective 2≤ftarrow 1 rotational transitions. This work also resolves a 10 MHz discrepancy in the frequency of the AlH line. CrH and AlH have already been observed in the photospheres of stars via their electronic transitions. These data will facilitate their discovery at submillimeter/terahertz wavelengths in circumstellar envelopes and perhaps in diffuse clouds.

Negative refraction with low absorption using Raman transitions with magnetoelectric coupling

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

Sikes, D. E.; Yavuz, D. D.

2010-07-15

We suggest a scheme for obtaining negative refraction that does not require the simultaneous presence of an electric-dipole and a magnetic-dipole transition near the same transition frequency. The key idea of the scheme is to obtain a strong electric response by using far-off-resonant Raman transitions. We propose to use a pair of electric-dipole Raman transitions and utilize magneto-electric cross coupling to achieve a negative index of refraction without requiring negative permeability. The interference of the two Raman transitions allows tunable negative refraction with low absorption.

Octahedral deformations and cationic displacements in the ferroelectric PbHf(0.8)Ti(0.2)O(3): a neutron powder diffraction study from 10 to 770 K

PubMed

Muller; Baudour; Bedoya; Bouree; Soubeyroux; Roubin

2000-02-01

Neutron powder diffraction data, collected over the temperature range 10-770 K, have been analysed in order to make a detailed characterization of the sequence of phase transitions occurring in the Hf-rich ferroelectric PbHf(0.8)Ti(0.2)O3, titanium hafnium lead oxide. Over the whole temperature range this compound undergoes two phase transitions, which involve cationic displacements and octahedral deformations (tilt and/or distortion) leading to strongly distorted perovskite-type structures. The first transition appears around 415 K between two ferroelectric rhombohedral phases: a low-temperature nonzero-tilt phase F(RL) (space group R3c) and an intermediate zero-tilt phase FRH (space group R3m). The second one, detected around 520 K, is associated with a ferroelectric to-paraelectric transition between the FRH phase and the Pc cubic phase (space group Pm3m). From high-resolution neutron powder diffraction data (diffractometer 3T2-LLB, Saclay, France, lambda = 1.2251 A), the crystallographic structure of the three successive phases has been accurately determined at the following temperatures: T = 10 K (FRL): space group R3c, Z = 6, a(hex) = 5.7827 (1), c(hex) = 14.2702 (4) A, V(hex) = 413.26 (2) A3; T = 150 K (F(RL)): space group R3c, Z = 6, a(hex) = 5.7871 (1), C(hex) = 14.2735 (4) A, V(hex) = 413.98 (3) A3; T = 290 K (FRL): space group R3c, Z = 6, a(hex) = 5.7943 (1), C(hex) = 14.2742 (5) A, V(hex) = 415.04 (3) A3; T = 440 K (F(RH)): space group R3c, Z = 6, a(hex) = 5.8025 (1), c(hex) = 14.2648 (4) A, V(hex) = 415.94 (3) A3; T = 520 K (Pc): space group Pm3m, Z = 1, a(cub) = 4.1072 (2) A, V(cub) = 69.29 (1) A3. In addition, a neutron powder thermodiffractometry experiment, performed between 290 and 770 K (diffractometer D1B-ILL, Grenoble, France, lambda = 2.533 A), has been used to study in situ the temperature-induced phase transitions. From sequential Rietveld refinements, the temperature dependence of the cation displacements and the rotation and/or distortion of oxygen octahedra was derived.

Study of the Electro-Modulated Reflectance Spectra for MERCURY(1-X-Y)MANGANESE(X)CADMIUM(Y)TELLURIUM and Gallium Arsenide

NASA Astrophysics Data System (ADS)

Lu, Chien-Rong

The optical properties of the semimagnetic semiconducting alloy, Hg_{rm 1-x-y}Mn _{x}Cd _{y}Te, were studied by electrolyte electroreflectance (EER). The analysis of the experimental spectra was based on the theoretical lineshapes for the electroreflectance spectra in the low-field limit. The observed structures in the spectra include the E _0 and E_0 + Delta_0 transitions at the Gamma point and the E_1 and E_1 + Delta_1 transitions on the Lambda axis. The compositional variations of these transitions were compared with the predictions of the virtual crystal approximation. The physical mechanism of another type of electro -modulated spectroscopy, photoreflectance, was also investigated. The materials used in this investigation were GaAs thin films grown by molecular-beam-epitaxy (MBE). The nonuniformity of the internal modulation field in the space charge region was taken into account, for the first time, by a multilayer model. The lineshape calculated from the multilayer model provides a good fit to the experimental spectrum, and more importantly, it permits a measure of the correct transition energy from the spectrum. The temperature dependence of the periods of the Franz-Keldysh oscillations in the photoreflectance spectra indicates that the band bending near the surface decreases with decreasing temperature.

Transient nutation electron spin resonance spectroscopy on spin-correlated radical pairs: A theoretical analysis on hyperfine-induced nuclear modulations

NASA Astrophysics Data System (ADS)

Weber, Stefan; Kothe, Gerd; Norris, James R.

1997-04-01

The influence of anisotropic hyperfine interaction on transient nutation electron paramagnetic resonance (EPR) of light-induced spin-correlated radical pairs is studied theoretically using the density operator formalism. Analytical expressions for the time evolution of the transient EPR signal during selective microwave excitation of single transitions are derived for a model system comprised of a weakly coupled radical pair and one hyperfine-coupled nucleus with I=1/2. Zero-quantum electron coherence and single-quantum nuclear coherence are created as a result of the sudden light-induced generation of the radical pair state from a singlet-state precursor. Depending on the relative sizes of the nuclear Zeeman frequency and the secular and pseudo-secular parts of the hyperfine coupling, transitions between levels with different nuclear spin orientations are predicted to modulate the time-dependent EPR signal. These modulations are in addition to the well-known transient nutations and electron zero-quantum precessions. Our calculations provide insight into the mechanism of recent experimental observations of coherent nuclear modulations in the time-resolved EPR signals of doublets and radical pairs. Two distinct mechanisms of the modulations are presented for various microwave magnetic field strengths. The first modulation scheme arises from electron and nuclear coherences initiated by the laser excitation pulse and is "read out" by the weak microwave magnetic field. While the relative modulation depth of these oscillations with respect to the signal intensity is independent of the Rabi frequency, ω1, the frequencies of this coherence phenomenon are modulated by the effective microwave amplitude and determined by the nuclear Zeeman interaction and hyperfine coupling constants as well as the electron-electron spin exchange and dipolar interactions between the two radical pair halves. In a second mechanism the modulations are both created and detected by the microwave radiation. Here, the laser pulse merely defines the beginning of the microwave-induced coherent time evolution. This second mechanism appears the most consistent with current experimental observations.

Considerations on the Design of a Molecular Frequency Standard Based on the Molecular Beam Electric Resonance Method

NASA Technical Reports Server (NTRS)

Hughes, Vernon W.

1959-01-01

The use of a rotational state transition as observed by the molecular beam electric resonance method is discussed as a possible frequency standard particularly in the millimeter wavelength range. As a promising example the 100 kMc transition between the J = 0 and J = 1 rotational states of Li 6F19 is considered. The relative insensitivity of the transition frequency to external electric and magnetic fields and the low microwave power requirements appear favorable; the small fraction of the molecular beam that is in a single rotational state is a limiting factor.

Model of ultrafast demagnetization driven by spin-orbit coupling in a photoexcited antiferromagnetic insulator Cr2O3

NASA Astrophysics Data System (ADS)

Guo, Feng; Zhang, Na; Jin, Wei; Chang, Jun

2017-06-01

We theoretically study the dynamic time evolution following laser pulse pumping in an antiferromagnetic insulator Cr2O3. From the photoexcited high-spin quartet states to the long-lived low-spin doublet states, the ultrafast demagnetization processes are investigated by solving the dissipative Schrödinger equation. We find that the demagnetization times are of the order of hundreds of femtoseconds, in good agreement with recent experiments. The switching times could be strongly reduced by properly tuning the energy gaps between the multiplet energy levels of Cr3+. Furthermore, the relaxation times also depend on the hybridization of atomic orbitals in the first photoexcited state. Our results suggest that the selective manipulation of the electronic structure by engineering stress-strain or chemical substitution allows effective control of the magnetic state switching in photoexcited insulating transition-metal oxides.

A low-spin Fe(III) complex with 100-ps ligand-to-metal charge transfer photoluminescence

NASA Astrophysics Data System (ADS)

Chábera, Pavel; Liu, Yizhu; Prakash, Om; Thyrhaug, Erling; Nahhas, Amal El; Honarfar, Alireza; Essén, Sofia; Fredin, Lisa A.; Harlang, Tobias C. B.; Kjær, Kasper S.; Handrup, Karsten; Ericson, Fredric; Tatsuno, Hideyuki; Morgan, Kelsey; Schnadt, Joachim; Häggström, Lennart; Ericsson, Tore; Sobkowiak, Adam; Lidin, Sven; Huang, Ping; Styring, Stenbjörn; Uhlig, Jens; Bendix, Jesper; Lomoth, Reiner; Sundström, Villy; Persson, Petter; Wärnmark, Kenneth

2017-03-01

Transition-metal complexes are used as photosensitizers, in light-emitting diodes, for biosensing and in photocatalysis. A key feature in these applications is excitation from the ground state to a charge-transfer state; the long charge-transfer-state lifetimes typical for complexes of ruthenium and other precious metals are often essential to ensure high performance. There is much interest in replacing these scarce elements with Earth-abundant metals, with iron and copper being particularly attractive owing to their low cost and non-toxicity. But despite the exploration of innovative molecular designs, it remains a formidable scientific challenge to access Earth-abundant transition-metal complexes with long-lived charge-transfer excited states. No known iron complexes are considered photoluminescent at room temperature, and their rapid excited-state deactivation precludes their use as photosensitizers. Here we present the iron complex [Fe(btz)3]3+ (where btz is 3,3‧-dimethyl-1,1‧-bis(p-tolyl)-4,4‧-bis(1,2,3-triazol-5-ylidene)), and show that the superior σ-donor and π-acceptor electron properties of the ligand stabilize the excited state sufficiently to realize a long charge-transfer lifetime of 100 picoseconds (ps) and room-temperature photoluminescence. This species is a low-spin Fe(III) d5 complex, and emission occurs from a long-lived doublet ligand-to-metal charge-transfer (2LMCT) state that is rarely seen for transition-metal complexes. The absence of intersystem crossing, which often gives rise to large excited-state energy losses in transition-metal complexes, enables the observation of spin-allowed emission directly to the ground state and could be exploited as an increased driving force in photochemical reactions on surfaces. These findings suggest that appropriate design strategies can deliver new iron-based materials for use as light emitters and photosensitizers.

Non-Intrusive Optical Diagnostic Methods for Flowfield Characterization

NASA Technical Reports Server (NTRS)

Tabibi, Bagher M.; Terrell, Charles A.; Spraggins, Darrell; Lee, Ja. H.; Weinstein, Leonard M.

1997-01-01

Non-intrusive optical diagnostic techniques such as Electron Beam Fluorescence (EBF), Laser-Induced Fluorescence (LIF), and Focusing Schlieren (FS) have been setup for high-speed flow characterization and large flowfield visualization, respectively. Fluorescence emission from the First Negative band of N2(+) with the (0,0) vibration transition (at lambda =391.44 nm) was obtained using the EBF technique and a quenching rate of N2(+)* molecules by argon gas was reported. A very high sensitivity FS system was built and applied in the High-Speed Flow Generator (HFG) at NASA LaRC. A LIF system is available at the Advanced Propulsion Laboratory (APL) on campus and a plume exhaust velocity measurement, measuring the Doppler shift from lambda = 728.7 nm of argon gas, is under way.

Dark matter and dark energy from the solution of the strong CP problem.

PubMed

Mainini, Roberto; Bonometto, Silvio A

2004-09-17

The Peccei-Quinn (PQ) solution of the strong CP problem requires the existence of axions, which are viable candidates for dark matter. If the Nambu-Goldstone potential of the PQ model is replaced by a potential V(|Phi|) admitting a tracker solution, the scalar field |Phi| can account for dark energy, while the phase of Phi yields axion dark matter. If V is a supergravity (SUGRA) potential, the model essentially depends on a single parameter, the energy scale Lambda. Once we set Lambda approximately equal to 10(10) GeV at the quark-hadron transition, |Phi| naturally passes through values suitable to solve the strong CP problem, later growing to values providing fair amounts of dark matter and dark energy.

Spatial and seasonal changes in optical properties of autochthonous and allochthonous chromophoric dissolved organic matter in a stratified mountain lake.

PubMed

Bracchini, Luca; Dattilo, Arduino Massimo; Hull, Vincent; Loiselle, Steven Arthur; Nannicini, Luciano; Picchi, Maria Pia; Ricci, Maso; Santinelli, Chiara; Seritti, Alfredo; Tognazzi, Antonio; Rossi, Claudio

2010-03-01

In this study, we present results on seasonal and spatial changes in CDOM absorption and fluorescence (fCDOM) in a deep mountain lake (Salto Lake, Italy). A novel approach was used to describe the shape of CDOM absorption between 250-700 nm (distribution of the spectral slope, S(lambda)) and a new fluorescence ratio is used to distinguish between humic and amino acid-like components. Solar ultraviolet irradiance, dissolved organic carbon (DOC), DOM fluorescence and absorption measurements were analysed and compared to other physicochemical parameters. We show that in the UV-exposed mixed layer: (i) fluorescence by autochthonous amino acid-like CDOM, (ii) values of S(lambda) across UV-C and UV-B wavebands increased during the summer months, whereas (i) average molar absorption coefficient and (ii) fluorescence by allochthonous humic CDOM decreased. In the unexposed deep layer of the water column (and in the entire water column in winter), humic-like CDOM presented high values of molar absorption coefficients and low values of S(lambda). UV attenuation coefficients correlated with both chlorophyll a concentrations and CDOM absorption. In agreement with changes in CDOM, minimal values in UV attenuation were found in summer. The S(lambda) curve was used as a signature of the mixture between photobleached and algal-derived CDOM with respect to the unexposed chromophoric dissolved compounds in this thermal stratified lake. Furthermore, S(lambda) curves were useful to distinguish between low and high molecular weight CDOM.

Microwave spectroscopy evidence of superconducting pairing in the magnetic-field-induced metallic state of InO(x) films at zero temperature.

PubMed

Liu, Wei; Pan, LiDong; Wen, Jiajia; Kim, Minsoo; Sambandamurthy, G; Armitage, N P

2013-08-09

We investigate the field-tuned quantum phase transition in a 2D low-disorder amorphous InO(x) film in the frequency range of 0.05 to 16 GHz employing microwave spectroscopy. In the zero-temperature limit, the ac data are consistent with a scenario where this transition is from a superconductor to a metal instead of a direct transition to an insulator. The intervening metallic phase is unusual with a small but finite resistance that is much smaller than the normal state sheet resistance at the lowest measured temperatures. Moreover, it exhibits a superconducting response on short length and time scales while global superconductivity is destroyed. We present evidence that the true quantum critical point of this 2D superconductor metal transition is located at a field B(sm) far below the conventionally defined critical field B(cross) where different isotherms of magnetoresistance cross each other. The superfluid stiffness in the low-frequency limit and the superconducting fluctuation frequency from opposite sides of the transition both vanish at B≈B(sm). The lack of evidence for finite-frequency superfluid stiffness surviving B(cross) signifies that B(cross) is a crossover above which superconducting fluctuations make a vanishing contribution to dc and ac measurements.

Sexual selection on male vocal fundamental frequency in humans and other anthropoids.

PubMed

Puts, David A; Hill, Alexander K; Bailey, Drew H; Walker, Robert S; Rendall, Drew; Wheatley, John R; Welling, Lisa L M; Dawood, Khytam; Cárdenas, Rodrigo; Burriss, Robert P; Jablonski, Nina G; Shriver, Mark D; Weiss, Daniel; Lameira, Adriano R; Apicella, Coren L; Owren, Michael J; Barelli, Claudia; Glenn, Mary E; Ramos-Fernandez, Gabriel

2016-04-27

In many primates, including humans, the vocalizations of males and females differ dramatically, with male vocalizations and vocal anatomy often seeming to exaggerate apparent body size. These traits may be favoured by sexual selection because low-frequency male vocalizations intimidate rivals and/or attract females, but this hypothesis has not been systematically tested across primates, nor is it clear why competitors and potential mates should attend to vocalization frequencies. Here we show across anthropoids that sexual dimorphism in fundamental frequency (F0) increased during evolutionary transitions towards polygyny, and decreased during transitions towards monogamy. Surprisingly, humans exhibit greater F0 sexual dimorphism than any other ape. We also show that low-F0 vocalizations predict perceptions of men's dominance and attractiveness, and predict hormone profiles (low cortisol and high testosterone) related to immune function. These results suggest that low male F0 signals condition to competitors and mates, and evolved in male anthropoids in response to the intensity of mating competition. © 2016 The Author(s).

Mapping of Low-Frequency Raman Modes in CVD-Grown Transition Metal Dichalcogenides: Layer Number, Stacking Orientation and Resonant Effects

PubMed Central

O’Brien, Maria; McEvoy, Niall; Hanlon, Damien; Hallam, Toby; Coleman, Jonathan N.; Duesberg, Georg S.

2016-01-01

Layered inorganic materials, such as the transition metal dichalcogenides (TMDs), have attracted much attention due to their exceptional electronic and optical properties. Reliable synthesis and characterization of these materials must be developed if these properties are to be exploited. Herein, we present low-frequency Raman analysis of MoS2, MoSe2, WSe2 and WS2 grown by chemical vapour deposition (CVD). Raman spectra are acquired over large areas allowing changes in the position and intensity of the shear and layer-breathing modes to be visualized in maps. This allows detailed characterization of mono- and few-layered TMDs which is complementary to well-established (high-frequency) Raman and photoluminescence spectroscopy. This study presents a major stepping stone in fundamental understanding of layered materials as mapping the low-frequency modes allows the quality, symmetry, stacking configuration and layer number of 2D materials to be probed over large areas. In addition, we report on anomalous resonance effects in the low-frequency region of the WS2 Raman spectrum. PMID:26766208

Influence of driving frequency on discharge modes in the dielectric barrier discharge excited by a triangle voltage

NASA Astrophysics Data System (ADS)

Li, Xuechen; Liu, Rui; Jia, Pengying; Wu, Kaiyue; Ren, Chenhua; Yin, Zengqian

2018-01-01

A one-dimensional fluid model in atmospheric pressure argon is employed to investigate the influence of the driving frequency on dielectric barrier discharge modes excited by a triangle voltage. Results indicate that a stepped discharge mode is obtained with a low driving frequency of 35 kHz. The current amplitude increases, while its plateau duration decreases with increasing the frequency. The stepped discharge transits into a multi-pulsed mode when the frequency is increased to 80 kHz. With its further increment, the pulse number decreases, and a double-pulsed discharge is realized at 90 kHz, which finally transits to a single-pulsed discharge. Through analyzing spatial distributions of electron density, ion density, and electric field, it can be concluded that the discharge regime transits from a Townsend-like discharge to a glow discharge with increasing the frequency. The regime transition is further verified by analyzing voltage-current curves. These simulated results are consistent with the experimental phenomena.

Epitaxial VO2 thin-film-based radio-frequency switches with electrical activation

NASA Astrophysics Data System (ADS)

Lee, Jaeseong; Lee, Daesu; Cho, Sang June; Seo, Jung-Hun; Liu, Dong; Eom, Chang-Beom; Ma, Zhenqiang

2017-09-01

Vanadium dioxide (VO2) is a correlated material exhibiting a sharp insulator-to-metal phase transition (IMT) caused by temperature change and/or bias voltage. We report on the demonstration of electrically triggered radio-frequency (RF) switches based on epitaxial VO2 thin films. The highly epitaxial VO2 and SnO2 template layer was grown on a (001) TiO2 substrate by pulsed laser deposition (PLD). A resistance change of the VO2 thin films of four orders of magnitude was achieved with a relatively low threshold voltage, as low as 13 V, for an IMT phase transition. VO2 RF switches also showed high-frequency responses of insertion losses of -3 dB at the on-state and return losses of -4.3 dB at the off-state over 27 GHz. Furthermore, an intrinsic cutoff frequency of 17.4 THz was estimated for the RF switches. The study on electrical IMT dynamics revealed a phase transition time of 840 ns.

Revealing the mechanism of passive transport in lipid bilayers via phonon-mediated nanometre-scale density fluctuations

DOE PAGES

Zhernenkov, Mikhail; Bolmatov, Dima; Soloviov, Dmitry; ...

2016-05-12

We report the high resolution inelastic x-ray study of the in-plane phonon excitations in dipalmitoyl phosphatidylcholine (DPPC) above and below main transition temperature. In the L β' gel phase, we observe high frequency longitudinal phonon mode previously predicted by the molecular dynamics simulations and for the first time, we reveal low frequency weakly dispersive transverse acoustic mode which softens and exhibits a low-frequency phonon gap when the DPPC lipid transitions into the L α fluid phase. The phonon softening of the high frequency longitudinal excitations and the transformation of the transverse excitations upon the phase transition from the L β'more » to L α phase is explained within the framework of the phonon theory of liquids. These findings illustrate the importance of the collective dynamics of biomembranes and reveal that hydrocarbon tails can act as an efficient mediator in controlling the passive transport across the bilayer plane.« less

Observation of Mollow Triplets with Tunable Interactions in Double Lambda Systems of Individual Hole Spins

NASA Astrophysics Data System (ADS)

Lagoudakis, K. G.; Fischer, K. A.; Sarmiento, T.; McMahon, P. L.; Radulaski, M.; Zhang, J. L.; Kelaita, Y.; Dory, C.; Müller, K.; Vučković, J.

2017-01-01

Although individual spins in quantum dots have been studied extensively as qubits, their investigation under strong resonant driving in the scope of accessing Mollow physics is still an open question. Here, we have grown high quality positively charged quantum dots embedded in a planar microcavity that enable enhanced light-matter interactions. Under a strong magnetic field in the Voigt configuration, individual positively charged quantum dots provide a double lambda level structure. Using a combination of above-band and resonant excitation, we observe the formation of Mollow triplets on all optical transitions. We find that when the strong resonant drive power is used to tune the Mollow-triplet lines through each other, we observe anticrossings. We also demonstrate that the interaction that gives rise to the anticrossings can be controlled in strength by tuning the polarization of the resonant laser drive. Quantum-optical modeling of our system fully captures the experimentally observed spectra and provides insight on the complicated level structure that results from the strong driving of the double lambda system.

Microstructural development and segregation effects in directionally solidified nickel-based superalloy PWA 1484

NASA Astrophysics Data System (ADS)

Li, Lichun

2002-09-01

These studies were performed to investigate the effects of thermal gradient (G) and growth velocity (V) on the microstructure development and solidification behavior of directionally solidified nickel-based superalloy PWA 1484. Directional solidification (DS) experiments were conducted using a Bridgman crystal growth facility. The solidification velocity ranged from 0.00005 to 0.01 cm/sec and thermal gradients ranged from 12 to 108°C/cm. The as-cast microstructures of DS samples were characterized by using conventional metallography; chemical composition and segregation of directionally solidified samples were analyzed with energy dispersive spectroscopy in SEM. A range of aligned solidification microstructures is exhibited by the alloy when examined as-cast at room temperature: dendrites, flanged cells, cells. The microstructure transitions from cellular to dendritic as the growth velocity increases. The experimental data for PWA1484 exhibits excellent agreement with the well-known exponential equation (lambda1 ∝ G -1/2V-1/4). However, the constant of proportionality is different depending upon the solidification microstructure: (1) dendritic growth with secondary arms leads to a marked dependence of lambda1 on G-1/2 V-1/4; (2) flanged cellular growth with no secondary arms leads to much lower dependence of lambda 1 on G-1/2V -1/4. The primary dendritic arm spacing results were also compared to recent theoretical models. The model of Hunt and Lu and the model of Ma and Sahm provided excellent agreement at medium to high thermal gradients and a wide range of solidification velocities. The anomalous behavior of lambda 1 with high growth velocity V at low G is analyzed based on the samples' microstructures. Off-axis heat flows were shown to cause radial non-uniformity in the dendrite arm spacing data for low thermal gradients and large withdrawal velocities. Various precipitates including gamma', (gamma ' + gamma) eutectic pool or divorced eutectic gamma ', and metal carbides were characterized. Processing conditions (growth velocity V and thermal gradient G) exert significant influence on both morphology and size of precipitates present. Freckle defects were observed on the surface of nickel-based superalloy MM247 cylindrical samples but not on the surface of cylindrical PWA 1484 samples. The Rayleigh number (Ra) that represents liquid instability at the interface was evaluated for MM247 and PWA 1484 in terms of a recently proposed theoretical equation. The effects of segregation, sloped solid/liquid interface and the morphology of dendritic/cellular trunks on the mushy zone convective flow and freckle formation are also discussed.

Studies of Nonconventional Superfluids: Ultrasound Propagation in HELIUM-3-BORON and the Microwave Surface Impedance of the Heavy-Fermion Superconductor Uranium PLATINUM(3)

NASA Astrophysics Data System (ADS)

Zhao, Zuyu

1990-06-01

Two nonconventional superfluids, superfluid ^3He-B and the heavy fermion superconductor UPt_3 have been studied using different techniques: (1) A study of ^3He -B was performed in an acoustic sound cell with a path length of 381mum using the single-ended, c.w., acoustic impedance technique. The fundamental frequency of the x-cut quartz transducer employed in the experiments was 12.80 MHz. The following studies were performed: (a) A systematic measurement was made on the pair-breaking edge in zero magnetic field with ultrasonic frequencies of 64.3 MHz, 90.1 MHz, 141.6 MHz and 167.4 MHz, in the pressure range from 3 bar to 28 bar. The results of our measurements indirectly support the temperature scale of Greywall and the weak coupling plus (WCP) model of Rainer and Serene for the gap function. The pair-breaking edge was also measured in magnetic fields up to 1.36 kG perpendicular to the sound propagation direction and the predicted shift of the effective pair-breaking threshold (from 2 Delta(T) in zero field) by Omega = {gamma Hover 1+{1 over3}F_sp{o}{a}(2+Y) }(the renormalized Larmor frequency) has been observed. (b) The (imaginary) squashing mode was excited with sound frequencies of 141.6 MHz and 115.8 MHz. A doublet splitting (of about 0.3 MHz) of this mode was observed. This doublet splitting was found to be strongly pressure and frequency dependent, but independent of the magnetic field (at the low fields studied). Possible causes of this splitting include superfluid flow induced texture effects and finite wavevector (dispersion) effects. (c) Structure was observed with a sound frequency of 64.3 MHz in the vicinity of 2Delta(T) in a magnetic field of about 580 Gauss which is thought to be J_{z} = -1 component of the J = 1^- collective mode. (2) A surface impedance study of heavy Fermion superconductor UPt_3 was performed with an X-band microwave spectrometer (f ~eq 11.42 GHz) integrated with an Oxford 400 TLE dilution refrigerator so as to have top-loading capability. (3) Using a top loading magnetometer, measurements of the H_{cl} on UPt_3 were performed and kinks were observed along the c axis and in the basal plane. The results support a model of unconventional superconductivity by Hess, Tokuyasu and Sauls.

Cirrus Parcel Model Comparison Project. Phase 1

NASA Technical Reports Server (NTRS)

Lin, Ruei-Fong; Starr, David O'C.; DeMott, Paul J.; Cotton, Richard; Jensen, Eric; Sassen, Kenneth

2000-01-01

The Cirrus Parcel Model Comparison (CPMC) is a project of the GEWEX Cloud System Study Working Group on Cirrus Cloud Systems (GCSS WG2). The primary goal of this project is to identify cirrus model sensitivities to the state of our knowledge of nucleation and microphysics. Furthermore, the common ground of the findings may provide guidelines for models with simpler cirrus microphysics modules. We focus on the nucleation regimes of the warm (parcel starting at -40 C and 340 hPa) and cold (-60 C and 170 hPa) cases studied in the GCSS WG2 Idealized Cirrus Model Comparison Project. Nucleation and ice crystal growth were forced through an externally imposed rate of lift and consequent adiabatic cooling. The background haze particles are assumed to be lognormally-distributed H2SO4 particles. Only the homogeneous nucleation mode is allowed to form ice crystals in the HN-ONLY runs; all nucleation modes are switched on in the ALL-MODE runs. Participants were asked to run the HN-lambda-fixed runs by setting lambda = 2 (lambda is further discussed in section 2) or tailoring the nucleation rate calculation in agreement with lambda = 2 (exp 1). The depth of parcel lift (800 m) was set to assure that parcels underwent complete transition through the nucleation regime to a stage of approximate equilibrium between ice mass growth and vapor supplied by the specified updrafts.

Climate change threatens polar bear populations: a stochastic demographic analysis.

PubMed

Hunter, Christine M; Caswell, Hal; Runge, Michael C; Regehr, Eric V; Amstrup, Steve C; Stirling, Ian

2010-10-01

The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with forecasts of future sea ice conditions from IPCC general circulation models (GCMs). The matrix population models classified individuals by age and breeding status; mothers and dependent cubs were treated as units. Parameter estimates were obtained from a capture-recapture study conducted from 2001 to 2006. Candidate statistical models allowed vital rates to vary with time and as functions of a sea ice covariate. Model averaging was used to produce the vital rate estimates, and a parametric bootstrap procedure was used to quantify model selection and parameter estimation uncertainty. Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in lambda in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log lambdas, as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log lambdas approximately - 0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with "business as usual" (A1B) greenhouse gas emissions. The resulting stochastic population projections showed drastic declines in the polar bear population by the end of the 21st century. These projections were instrumental in the decision to list the polar bear as a threatened species under the U.S. Endangered Species Act.

Influence of convection on eutectic microstructure

NASA Technical Reports Server (NTRS)

Baskaran, V.; Eisa, G. F.; Wilcox, W. R.

1985-01-01

When the MnBi-Bi eutectic is directionally solidified, it forms fibers of MnBi in a matrix of bismuth. When the material solidified in space at rates of 30 and 50 cm/hr, the average fiber spacing lambda was about one half of the value obtained in cases in which the same material solidified on earth. Neither an altered temperature gradient nor a fluctuating freezing rate are apparently responsible for the change in lambda, and the possibility is studied that natural convection increases lambda on earth by perturbing the compositional field in the melt ahead of the growing solid. A theoretical analysis is conducted along with some experiments. On the basis of the theoretical results for lamellar growth, it is concluded that the spacing lambda increases with increasing stirring, especially at small freezing rates. The experiments indicate that at low growth rates the cross-sectional area of the MnBi blades increases with increased stirring and with decreased growth rate.

Dynamics of a Landau-Zener non-dissipative system with fluctuating energy levels

NASA Astrophysics Data System (ADS)

Fai, L. C.; Diffo, J. T.; Ateuafack, M. E.; Tchoffo, M.; Fouokeng, G. C.

2014-12-01

This paper considers a Landau-Zener (two-level) system influenced by a three-dimensional Gaussian and non-Gaussian coloured noise and finds a general form of the time dependent diabatic quantum bit (qubit) flip transition probabilities in the fast, intermediate and slow noise limits. The qubit flip probability is observed to mimic (for low-frequencies noise) that of the standard LZ problem. The qubit flip probability is also observed to be the measure of quantum coherence of states. The transition probability is observed to be tailored by non-Gaussian low-frequency noise and otherwise by Gaussian low-frequency coloured noise. Intermediate and fast noise limits are observed to alter the memory of the system in time and found to improve and control quantum information processing.

First report of L1014F-kdr mutation in Culex pipiens complex from Morocco.

PubMed

Bkhache, Meriem; Tmimi, Fatim-Zohra; Charafeddine, Omar; Faraj, Chafika; Failloux, Anna-Bella; Sarih, M'hammed

2016-12-16

Mosquitoes of the Culex pipiens complex, competent vectors for West Nile virus (WNV) and Rift Valley fever virus (RVFV) are widely targeted by insecticide treatments. The intensive application of chemical insecticides led to the development of resistance in many insects including Culex pipiens mosquitoes. The absence of data on resistance mechanisms in Morocco allow us to assess the levels of lambda-cyhalothrin resistance and the frequency of the mutated gene L1014F kdr in different forms of Cx. pipiens complex from three regions of Morocco. Mosquito adults were reared from immature stages collected in three different regions in Morocco (Tangier, Casablanca and Marrakech). Standard WHO insecticide susceptibility tests were conducted on adults emerged from collected larvae. Specimens were identified as belonging to the Culex pipiens complex using a multiplex PCR assay with diagnostic primers designed from the flanking region of microsatellite CQ11. Identified mosquitoes were then tested for the presence of the L1014F kdr mutation using PCR assay. Our results showed that 21% of the tested population has a resistance to lambda-cyhalothrin. The molecular identification of survivors shows that 43% belonged to the Cx. pipiens pipiens and only 9.5% to the Cx. pipiens molestus form. On the other hand, 416 specimens were screened for the L1014F kdr mutation. L1014F mutation was detected in different forms of Cx. pipiens in different sites. The frequency of L1014F mutation was similar between the Cx. pipiens pipiens form and hybrid form, while it was lower in the Cx. pipiens molestus form. The presence of the L1014F kdr allele was significantly associated with resistance to lambda-cyhalothrin in Cx. pipiens pipiens (P < 0.0001) and hybrid form (P < 0.0001). Resistance to lambda-cyhalothrin of Cx. pipiens populations appears to be largely due to the L1014F kdr mutation. To our knowledge, the frequencies of L1014F kdr mutation are examined for the first time in natural populations of the Culex pipiens complex in Morocco. These findings will provide important information to propose more adapted vector control measures towards this mosquito species, potential vector of arboviruses.

Miniature optical planar camera based on a wide-angle metasurface doublet corrected for monochromatic aberrations

DOE PAGES

Arbabi, Amir; Arbabi, Ehsan; Kamali, Seyedeh Mahsa; ...

2016-11-28

Optical metasurfaces are two-dimensional arrays of nano-scatterers that modify optical wavefronts at subwavelength spatial resolution. They are poised to revolutionize optics by enabling complex low-cost systems where multiple metasurfaces are lithographically stacked and integrated with electronics. For imaging applications, metasurface stacks can perform sophisticated image corrections and can be directly integrated with image sensors. Here we demonstrate this concept with a miniature flat camera integrating a monolithic metasurface lens doublet corrected for monochromatic aberrations, and an image sensor. The doublet lens, which acts as a fisheye photographic objective, has a small f-number of 0.9, an angle-of-view larger than 60° ×more » 60°, and operates at 850 nm wavelength with 70% focusing efficiency. The camera exhibits nearly diffraction-limited image quality, which indicates the potential of this technology in the development of optical systems for microscopy, photography, and computer vision.« less

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

Summers, D. J.; Hart, T. L.; Acosta, J. G.

We propose a novel scheme for final muon ionization cooling with quadrupole doublets followed by emittance exchange in vacuum to achieve the small beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low beta region occupied by a dense, low Z absorber. After final cooling, normalized transverse, longitudinal, and angular momentum emittances of 0.100, 2.5, and 0.200 mm-rad are exchanged into 0.025, 70, and 0.0 mm-rad. A skew quadrupole triplet transforms a round muon bunchmore » with modest angular momentum into a flat bunch with no angular momentum. Thin electrostatic septa efficiently slice the flat bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 µs, one quarter of a synchrotron oscillation period. A linear long wavelength RF bucket gives each bunch a different energy causing the bunches to drift in the ring until they merge into one bunch and can be captured in a short wavelength RF bucket with a 13% muon decay loss and a packing fraction as high as 87 %.« less

A HIRES/KECK SPECTROSCOPIC INVESTIGATION OF THE MEASUREMENT OF SODIUM IN THE ATMOSPHERE OF HD 209458b

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

Langland-Shula, Laura E.; Vogt, Steven S.; Charbonneau, David

We present high-resolution High Resolution Echelle Spectrometer (HIRES)/Keck spectra of HD 209458, and a Monte Carlo variation on the basic method used by other workers, to look for the excess in-transit absorption in the NaD doublet at 5893 A due to the extrasolar planet. The HIRES data, binned by bandpass, allow a direct comparison with previous results. We find >3{sigma} results in most test bandpasses around the NaD doublet, including relative absorption of (-108.8 {+-} 25.7) x 10{sup -5} in the 'narrow' bandpass used by other workers. This is {approx}4.7 times larger than the 'narrow' results reported by Charbonneau etmore » al. for HD 209458b. However, >2{sigma} absorption is detected in some weak Fe I and Ni I lines that were tested for comparison, raising concern about the uncertainties introduced by continuum-fitting and terrestrial atmosphere subtraction.« less

Implications of hidden gauged U (1 ) model for B anomalies

NASA Astrophysics Data System (ADS)

Fuyuto, Kaori; Li, Hao-Lin; Yu, Jiang-Hao

2018-06-01

We propose a hidden gauged U (1 )H Z' model to explain deviations from the standard model (SM) values in lepton flavor universality known as RK and RD anomalies. The Z' only interacts with the SM fermions via their mixing with vectorlike doublet fermions after the U (1 )H symmetry breaking, which leads to b →s μ μ transition through the Z' at tree level. Moreover, introducing an additional mediator, inert-Higgs doublet, yields b →c τ ν process via charged scalar contribution at tree level. Using flavio package, we scrutinize adequate sizes of the relevant Wilson coefficients to these two processes by taking various flavor observables into account. It is found that significant mixing between the vectorlike and the second generation leptons is needed for the RK anomaly. A possible explanation of the RD anomaly can also be simultaneously addressed in a motivated situation, where a single scalar operator plays a dominant role, by the successful model parameters for the RK anomaly.

Far Ultraviolet Spectroscopic Explorer Observations of the Seyfert 1.5 Galaxy NGC 5548 in a Low State

NASA Technical Reports Server (NTRS)

Brotherton, M. S.; Green, R. F.; Kriss, G. A.; Oegerle, W.; Kaiser, M. E.; Zheng, W.; Hutchings, J. B.; Fisher, Richard R. (Technical Monitor)

2001-01-01

We present far-ultraviolet spectra of the Seyfert 1.5 galaxy NGC 5548 obtained in 2000 June with the Far Ultraviolet Spectroscopic Explorer (FUSE). Our data span the observed wavelength range 915-1185 A at a resolution of approximately 20 km s(exp -1). The spectrum shows a weak continuum and emission from O VI (lambda)(lambda)1032, 1038, C III (lambda)977, and He II (lambda)1085. The FUSE data were obtained when the AGN (Active Galactic Nuclei) was in a low state, which has revealed strong, narrow O VI emission lines. We also resolve intrinsic, associated absorption lines of O VI and the Lyman series. Several distinct kinematic components are present, spanning a velocity range of approximately 0 to -1300 km s(exp -1) relative to systemic, with kinematic structure similar to that seen in previous observations of longer wavelength ultraviolet (UV) lines. We explore the relationships between the far-UV (ultraviolet) absorbers and those seen previously in the UV and X-rays. We find that the high-velocity UV absorption component is consistent with being low-ionization, contrary to some previous claims, and is consistent with its non-detection in high-resolution X-ray spectra. The intermediate velocity absorbers, at -300 to -400 km s(exp -1), show H I and O VI column densities consistent with having contributions from both a high-ionization X-ray absorber and a low-ionization UV absorber. No single far-UV absorbing component can be solely identified with the X-ray absorber.

Development of Fast, Background-Limited Transition-Edge Sensors for the Background-Limited Infrared/Sub-Millimetre Spectrograph (BLISS) for SPICA

NASA Technical Reports Server (NTRS)

Beyer, Andrew D.; Runyan, M. C.; Kenyon, M.; Echternach, P. M.; Chui, T.; Bumble, B.; Bradford, C. M.; Holmes, W. A.; Bock, J. J.

2012-01-01

We report experimental progress toward demonstrating background-limited arrays of membrane-isolated transition-edge sensors (TESs) for the Background Limited Infrared/Sub-mm Spectrograph (BLISS). BLISS is a space-borne instrument with grating spectrometers for wavelengths lambda = 35-435 microns and with R = lambda/(delta)lambda approx. 500. The goals for BLISS TESs are: noise equivalent power (NEP) = 5x10(exp -20) W/Hz(1/2) and response time t<30ms. We expect background-limited performance from bilayers TESs with T(sub c)=65mK and G=15fW/K. However, such TESs cannot be operated at 50mK unless stray power on the devices, or dark power PD, is less than 200aW. We describe criteria for measuring P? that requires accurate knowledge of TC. Ultimately, we fabricated superconducting thermistors from Ir (T(sub c) > or = 135mK) and Mo/Cu proximitized bilayers, where T(sub c) is the thermistor transition temperature. We measured the Ir TES arrays in our 50mK adiabatic demagnetization refrigerator test system, which can measure up to eight 1x32 arrays simultaneously using a time-division multiplexer, as well as our single-pixel test system which can measure down to 15mK. In our previous Ir array measurements our best reported performance was NEP=2.5x10(exp -19) W/Hz(1/2) and tapprox.5ms for straight-beam TESs. In fact, we expected NEPapprox.1.5x10(exp -19)W/Hz(1/2) for meander beam TESs, but did not achieve this previously due to 1/f noise. Here, we detail improvements toward measuring the expected NEP and demonstrate NEP=(1.3+0.2)x10(exp -19)W/Hz(1/2) in our single-pixel test system and NEP=(1.6+0.3)x10(exp -19)W/Hz(1/2) in our array test system.

Anelasticity maps for acoustic dissipation associated with phase transitions in minerals

NASA Astrophysics Data System (ADS)

Carpenter, Michael A.; Zhang, Zhiying

2011-07-01

Acoustic dissipation due to structural phase transitions in minerals could give rise to large seismic attenuation effects superimposed on the high temperature background contribution from dislocations and grain boundaries in the Earth. In addition to the possibility of a sharp peak actually at a transition point for both compressional and shear waves, significant attenuation might arise over wider temperature intervals due to the mobility of transformation twins or other defects associated with the transition. Attenuation due to structural phase transitions in quartz, pyroxenes, perovskites, stishovite and hollandite, or to spin state transitions of Fe2+ in magnesiowüstite and perovskite and the hcp/bcc transition in iron-nickel (Fe-Ni) alloy, are reviewed from this perspective. To these can be added possible loss behaviour associated with reconstructive transitions which might occur by a ledge mechanism on topotactic interfaces (orthopyroxene/clinopyroxene, olivine/spinel and perovskite/postperovskite), with impurities (Snoek effect) or with mobility of protons. There are experimental difficulties associated with measuring dissipation effects in situ at simultaneous high pressures and temperatures, so reliance is currently placed on investigation of analogue phases such as LaCoO3 for spin-state behaviour and LaAlO3 for the dynamics of ferroelastic twin walls. Similarly, it is not possible to measure loss dynamics simultaneously at the low stresses and low frequencies that pertain in seismic waves, so reliance must be placed on combining different techniques, such as dynamic mechanical analysis (low frequency, relatively high stress) and resonant ultrasound spectroscopy (high frequency, low stress), to extrapolate acoustic loss behaviour over wide frequency, temperature and stress intervals. In this context 'anelasticity maps' provide a convenient means of representing different loss mechanisms. Contouring of the inverse mechanical quality factor, Q-1, can be achieved if the appropriate constitutive laws are known. The overall approach is illustrated using the examples of spin-state transitions of Co3+ in LaCoO3 and twin mobility in single crystals of the rhombohedral phase of LaAlO3. Anelasticity maps of this type should give seismologists a clearer view of the characteristic patterns of seismic velocity and attenuation that could be used to detect (or rule out) the presence of particular phase transitions or loss behaviour in the core and mantle.

Comparing two tetraalkylammonium ionic liquids. II. Phase transitions

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

Lima, Thamires A.; Paschoal, Vitor H.; Faria, Luiz F. O.

Phase transitions of the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N{sub 1114}][NTf{sub 2}], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N{sub 1444}][NTf{sub 2}], were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) measurements, and Raman spectroscopy. XRD and Raman spectra were obtained as a function of temperature at atmospheric pressure, and also under high pressure at room temperature using a diamond anvil cell (DAC). [N{sub 1444}][NTf{sub 2}] experiences glass transition at low temperature, whereas [N{sub 1114}][NTf{sub 2}] crystallizes or not depending on the cooling rate. Both the ionic liquids exhibit glass transition under high pressure. XRD and low-frequency Raman spectra provide a consistent physical picturemore » of structural ordering-disordering accompanying the thermal events of crystallization, glass transition, cold crystallization, pre-melting, and melting. Raman spectra in the high-frequency range of some specific cation and anion normal modes reveal conformational changes of the molecular structures along phase transitions.« less

Renormalization-group constraints on Yukawa alignment in multi-Higgs-doublet models

NASA Astrophysics Data System (ADS)

Ferreira, P. M.; Lavoura, L.; Silva, João P.

2010-05-01

We write down the renormalization-group equations for the Yukawa-coupling matrices in a general multi-Higgs-doublet model. We then assume that the matrices of the Yukawa couplings of the various Higgs doublets to right-handed fermions of fixed quantum numbers are all proportional to each other. We demonstrate that, in the case of the two-Higgs-doublet model, this proportionality is preserved by the renormalization-group running only in the cases of the standard type-I, II, X, and Y models. We furthermore show that a similar result holds even when there are more than two Higgs doublets: the Yukawa-coupling matrices to fermions of a given electric charge remain proportional under the renormalization-group running if and only if there is a basis for the Higgs doublets in which all the fermions of a given electric charge couple to only one Higgs doublet.

A study of the influence of Hg(6(3)P2) population in a low-pressure discharge on mercury ion emission at 194.2 nm

NASA Technical Reports Server (NTRS)

Maleki, L.; Blasenheim, B. J.; Janik, G. R.

1990-01-01

A low-pressure mercury-argon discharge, similar to the type existing in the mercury lamp for the trapped-ion standard, is probed with a new technique of laser spectroscopy to determine the influence of the Hg(6 3P(sub 2)) population on discharge emission. The discharge is excited with inductively coupled rf power. Variations in the intensity of emission lines in the discharge were examined as lambda = 546.1 nm light from a continuous wave (CW) laser excited the Hg(6 3P(sub 2)) to (7 3S (sub 1)) transition. The spectrum of the discharge viewed in the region of laser irradiation showed increased emission in lambda = 546.1, 435.8, 404.7, 253.7, and 194.2 nm lines. Other lines in Hg I exhibited a decrease in emission. When the discharge was viewed outside the region of laser irradiation, all lines exhibited an increased emission. Based on these results, it is concluded that the dominant mechanism for the excitation of higher lying levels of mercury is the the electron-impact excitation via the 3P(sub 2) level. The depopulation of this metastable is also responsible for the observed increase in the electron temperature when the laser irradiates the discharge. It is also concluded that the 3P(sub 2) metastable level of mercury does not play a significant role in the excitation of the 3P(sub 1/2) level of mercury ion.

Electron Spectroscopy Studies of Iron, Iron Sulfides and Supported Iron Surfaces: Chemisorption of Simple Gases.

NASA Astrophysics Data System (ADS)

Lee, Yiu Chung

EELS was used to investigate the chemisorption of oxygen and carbon on iron. The EELS spectra of oxidized iron show characteristic features with strong enhancement of the interband transitions involving the Fe 3d band (4.6 and 7.5 eV) and moderate enhancement of the M(,2,3) transition doublet (54.4 and 58.2 eV). The changes in the electron energy loss structures with an overlayer of graphitic or carbidic carbon were investigated. The adsorption and growth of iron on Ni(100) has been studied using the combined techniques of LEED and EELS. Initially iron grows by a layer-by-layer mechanism for the first few layers. High iron coverages result in the observation of complex LEED patterns with satellites around the main (1 x 1) diffraction sports. This is due to the formation of b.c.c. Fe(110) crystallites arranged in domains with different orientations. EELS studies show the presence of three stages in the growth of iron on Ni(100): low-coverage, film-like and bulk-like. Auger and EELS were used to study the iron sulfide (FeS(,2), Fe(,7)S(,8) and FeS) surfaces. A characteristic M(,2,3) VV Auger doublet with a separation of 5.0 eV was observed on the sulfides. An assignment of the electron energy loss peaks was made based on the energy dependence of the loss peaks and previous photoemission results. The effect of argon ion bombardment was studied. Peaks with strong iron and sulfur character were observed. Heating the damaged sulfides results in reconstruction of the sulfide surfaces. The reactions of the sulfides with simple gases, such as H(,2), CO, CH(,4), C(,2)H(,4), NH(,3) and O(,2) were also studied. Using XPS, the chemisorption of SO(,2) on CaO(100) has been studied. The chemical state of sulfur has been identified as that of sulfate. The kinetics of SO(,2) chemisorption on CaO are discussed. The binding states of Fe and Na on CaO were determined to be Fe('2+) and Na('+) respectively. At low Fe or Na coverages (< 0.5 ML), there is a large increase in the rate of sulfate formation at low SO(,2) exposures (< 3 L). This increase is explained by the 'activation' of SO(,2) chemisorption sites by Fe or Na adatoms.

Quantum scattering studies of spin-orbit effects in the Cl({sup 2}P) + HCl {yields} ClH + Cl({sup 2}P) reaction

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

Schatz, G.C.; McCabe, P.; Connor, J.N.L.

1998-07-01

The authors present quantum scattering calculations for the Cl + HCl {yields} ClH + Cl reaction in which they include the three electronic states that correlate asymptotically to the ground state of Cl({sup 2}P) + HCl(X{sup 1}{Sigma}{sup +}). The potential surfaces and couplings are taken from the recent work of C.S. Maierle, G.C. Schatz, M.S. Gordon, P. McCabe and J.N.L. Connor, J. Chem. Soc. Farad. Trans. (1997). They are based on extensive ab initio calculations for geometries in the vicinity of the lowest energy saddle point, and on an electrostatic expansion (plus empirical dispersion and repulsion) for long range geometriesmore » including the van der Waals wells. Spin-orbit coupling has been included using a spin-orbit coupling parameter {lambda} that is assumed to be independent of nuclear geometry, and Coriolis interactions are incorporated accurately. The scattering calculations use a hyperspherical coordinate coupled channel method in full dimensionality. AJ-shifting approximation is employed to convert cumulative reaction probabilities for total angular momentum quantum number J = 1/2 into state selected and thermal rate coefficients. Two issues have been studied: (a) the influence of the magnitude of {lambda} on the fine-structure resolved cumulative probabilities and rate coefficients (the authors consider {lambda}`s that vary from 0 to {+-}100% of the true Cl value), and (b) the transition state resonance spectrum, and its variation with {lambda} and with other parameters in the calculations. Cl + HCl is a simple hydrogen transfer reaction which serves as a canonical model both for heavy-light-heavy atom reactions, and for the reactions of halogen atoms with closed shell molecules.« less

Brain electrophysiology in Sprague-Dawley rats fed low copper diets

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

Penland, J.G.; Sawler, B.G.; Klevay, L.M.

1986-03-01

Electrical activity of the brain was assessed in 38 unanesthetized male rats fed a Cu deficient diet for c.100 days after weaning. Rats were supplemented with drinking solutions containing 0, 0.75, or 2 ..mu..g Cu/ml and 10 ..mu..g Zn/ml (as sulfate and acetate, respectively). Three weeks prior to recording, dural ball electrodes were placed bilaterally 1 mm anterior to the lambda and 4 mm lateral to the midline, with a midline reference 2 mm anterior to the bregma. Cu deficiency was verified by atomic absorption spectroscopy of plasma Cu (p < .0001). The electroencephalogram revealed dietary effects on both logmore » power and arcsin percent-total power in each of four frequency bands (1-3, 4-7, 8-12, 13-18 Hz). Low dietary Cu resulted in less log power and percent-total power in the lowest frequencies, and log power evidenced lateralized effects in the higher frequencies. Rats fed the diet most deficient in Cu had lower left and higher right hemisphere power than did rats fed the more adequate Cu diets. Percent-total power was higher in the mid-range frequencies in both hemispheres for rats fed the Cu deficient diets, compared to rats supplemented with the largest amount of Cu. The findings confirm a previous experiment (unpublished) and suggest that dietary Cu influences the electrical activity of the brain in a select (i.e., frequency and location specific) rather than undifferentiated manner.« less

Study of {Lambda}-{Lambda} oscillation in quantum coherent {Lambda}{Lambda} by using J/{psi}{yields}{Lambda}{Lambda} decay

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

Kang Xianwei; Department of Physics, Henan Normal University, Xinxiang 453007; Li Haibo

2010-03-01

We discuss the possibility of searching for the {Lambda}-{Lambda} oscillations for coherent {Lambda}{Lambda} production in the J/{psi}{yields}{Lambda}{Lambda} decay process. The sensitivity of measurement of {Lambda}-{Lambda} oscillation in the external field at BES-III experiment is considered. These considerations indicate an alternative way to probe the {Delta}B=2 amplitude in addition to neutron oscillation experiments. Both coherent and time-dependent information can be used to extract the {Lambda}-{Lambda} oscillation parameter. With one year's luminosity at BES-III, we can set an upper limit of {delta}m{sub {Lambda}{Lambda}<}10{sup -15} MeV at 90% confidence level, corresponding to about 10{sup -6} s of {Lambda}-{Lambda} oscillation time.

On the persistence of spatiotemporal oscillations generated by invasion

NASA Astrophysics Data System (ADS)

Kay, A. L.; Sherratt, J. A.

1999-10-01

Many systems in biology and chemistry are oscillatory, with a stable, spatially homogeneous steady state which consists of periodic temporal oscillations in the interacting species, and such systems have been extensively studied on infinite or semi-infinite spatial domains. We consider the effect of a finite domain, with zero-flux boundary conditions, on the behaviour of solutions to oscillatory reaction-diffusion equations after invasion. We begin by considering numerical simulations of various oscillatory predatory-prey systems. We conclude that when regular spatiotemporal oscillations are left in the wake of invasion, these die out, beginning with a decrease in the spatial frequency of the oscillations at one boundary, which then propagates across the domain. The long-time solution in this case is purely temporal oscillations, corresponding to the limit cycle of the kinetics. Contrastingly, when irregular spatiotemporal oscillations are left in the wake of invasion, they persist, even in very long time simulations. To study this phenomenon in more detail, we consider the {lambda}-{omega} class of reaction-diffusion systems. Numerical simulations show that these systems also exhibit die-out of regular spatiotemporal oscillations and persistence of irregular spatiotemporal oscillations. Exploiting the mathematical simplicity of the {lambda}-{omega} form, we derive analytically an approximation to the transition fronts in r and {theta}x which occur during the die-out of the regular oscillations. We then use this approximation to describe how the die-out occurs, and to derive a measure of its rate, as a function of parameter values. We discuss applications of our results to ecology, calcium signalling and chemistry.

Compression Garments, Muscle Contractile Function, and Economy in Trail Runners.

PubMed

Vercruyssen, Fabrice; Gruet, Mathieu; Colson, Serge S; Ehrstrom, Sabine; Brisswalter, Jeanick

2017-01-01

Physiological mechanisms behind the use of compression garments (CGs) during off-road running are unknown. To investigate the influence of wearing CGs vs conventional running clothing (CON) on muscle contractile function and running economy before and after short-distance trail running. Knee-extensor neuromuscular function and running economy assessed from two 5-min treadmill runs (11 and 14 km/h) were evaluated before and after an 18.6-km short-distance trail run in 12 trained athletes wearing either CGs (stocking + short-tight) or CON. Quadriceps neuromuscular function was assessed from mechanical and EMG recording after maximal percutaneous electrical femoral-nerve stimulations (single-twitch doublets at 10 [Db 10 ] and 100 Hz [Db 100 ] delivered at rest and during maximal quadriceps voluntary contraction [MVC]). Running economy (in mL O 2 · km -1 · kg -1 ) increased after trail running independent of the clothing condition and treadmill speeds (P < .001). Similarly, MVC decreased after CON and CGs conditions (-11% and -13%, respectively, P < .001). For both clothing conditions, a significant decrease in quadriceps voluntary activation, Db 10 , Db 100 , and the low-to-high frequency doublet ratio were observed after trail running (time effect, all P < .01), without any changes in rectus femoris maximal M-wave. Wearing CGs does not reduce physiological alterations induced during short-distance trail running. Further studies should determine whether higher intensity of compression pressure during exercises of longer duration may be effective to induce any physiological benefits in experienced trail runners.

Weak-field ELF magnetic interactions: Implications for biological change during paleomagnetic reversals.

PubMed

Liboff, Abraham R

2013-12-01

Contrary to the belief that paleomagnetic reversals are not biologically significant, we find good reason to think otherwise. Attention is drawn to polarity transitions, time intervals a few thousand years long that follow the collapse of the existing geomagnetic dipole moment and precede the establishment of the new, oppositely directed moment. The geomagnetic field during transitions is reduced to a maximal mean intensity about 10% of the stable field and can exhibit low-frequency perturbations comparable to numerous laboratory-based extremely low frequency (ELF) studies reporting biological interactions, making it very likely that similar interactions must occur over the course of a polarity transition. This conclusion is strengthened by reports of medical problems that significantly correlate with intense solar winds, events that also generate ELF perturbations similar to those that can occur during polarity transitions.

Structure of the nucleon's low-lying excitations

NASA Astrophysics Data System (ADS)

Chen, Chen; El-Bennich, Bruno; Roberts, Craig D.; Schmidt, Sebastian M.; Segovia, Jorge; Wan, Shaolong

2018-02-01

A continuum approach to the three valence-quark bound-state problem in quantum field theory is used to perform a comparative study of the four lightest (I =1 /2 ,JP=1 /2±) baryon isospin doublets in order to elucidate their structural similarities and differences. Such analyses predict the presence of nonpointlike, electromagnetically active quark-quark (diquark) correlations within all baryons; and in these doublets, isoscalar-scalar, isovector-pseudovector, isoscalar-pseudoscalar, and vector diquarks can all play a role. In the two lightest (1 /2 ,1 /2+) doublets, however, scalar and pseudovector diquarks are overwhelmingly dominant. The associated rest-frame wave functions are largely S -wave in nature; and the first excited state in this 1 /2+ channel has the appearance of a radial excitation of the ground state. The two lightest (1 /2 ,1 /2-) doublets fit a different picture: accurate estimates of their masses are obtained by retaining only pseudovector diquarks; in their rest frames, the amplitudes describing their dressed-quark cores contain roughly equal fractions of even- and odd-parity diquarks; and the associated wave functions are predominantly P -wave in nature, but possess measurable S -wave components. Moreover, the first excited state in each negative-parity channel has little of the appearance of a radial excitation. In quantum field theory, all differences between positive- and negative-parity channels must owe to chiral symmetry breaking, which is overwhelmingly dynamical in the light-quark sector. Consequently, experiments that can validate the contrasts drawn herein between the structure of the four lightest (1 /2 ,1 /2±) doublets will prove valuable in testing links between emergent mass generation and observable phenomena and, plausibly, thereby revealing dynamical features of confinement.

Methods for constraining fine structure constant evolution with OH microwave transitions.

PubMed

Darling, Jeremy

2003-07-04

We investigate the constraints that OH microwave transitions in megamasers and molecular absorbers at cosmological distances may place on the evolution of the fine structure constant alpha=e(2)/ variant Planck's over 2pi c. The centimeter OH transitions are a combination of hyperfine splitting and lambda doubling that can constrain the cosmic evolution of alpha from a single species, avoiding systematic errors in alpha measurements from multiple species which may have relative velocity offsets. The most promising method compares the 18 and 6 cm OH lines, includes a calibration of systematic errors, and offers multiple determinations of alpha in a single object. Comparisons of OH lines to the HI 21 cm line and CO rotational transitions also show promise.

Superradiant phase transition in a model of three-level-Λ systems interacting with two bosonic modes

NASA Astrophysics Data System (ADS)

Hayn, Mathias; Emary, Clive; Brandes, Tobias

2012-12-01

We consider an ensemble of three-level particles in Lambda configuration interacting with two bosonic modes. The Hamiltonian has the form of a generalized Dicke model. We show that in the thermodynamic limit this model supports a superradiant quantum phase transition. Remarkably, this can be both a first- and a second-order phase transition. A connection of the phase diagram to the symmetries of the Hamiltonian is also given. In addition, we show that this model can describe atoms interacting with an electromagnetic field in which the microscopic Hamiltonian includes a diamagnetic contribution. Even though the parameters of the atomic system respect the Thomas-Reiche-Kuhn sum rule, the system still shows a superradiant phase transition.

The spectroscopic observation of the CH radical in its a4Sigma(-) state

NASA Technical Reports Server (NTRS)

Nelis, Thomas; Brown, John M.; Evenson, Kenneth M.

1988-01-01

The first spectroscopic observation of CH in the a 4Sigma(0-) state are reported. The molecule was generated in a discharge-flow system in the reaction betweeen fluorine atoms and methane or between oxygen atoms and acetylene at a total pressure of about 1 Torr. Several resonances associated with the N = 1 - 0 transitions of 4Sigma(-) CH were observed at three separate laser wavelengths, while those for the N = 2 - 1 transition were observed at two wavelengths. Each observed Zeeman component consists of a well-split doublet arising from proton hyperfine structure. The reasons for assigning the observations to CH in its a 4Sigma(-) state are discussed.

Dynamic nuclear polarization-magnetic resonance imaging at low ESR irradiation frequency for ascorbyl free radicals.

PubMed

Ito, Shinji; Hyodo, Fuminori

2016-02-19

Highly water-soluble ubiquinone-0 (CoQ0) reacts with ascorbate monoanion (Asc) to mediate the production of ascorbyl free radicals (AFR). Using aqueous reaction mixture of CoQ0 and Asc, we obtained positively enhanced dynamic nuclear polarization (DNP)-magnetic resonance (MR) images of the AFR at low frequency (ranging from 515 to 530 MHz) of electron spin resonance (ESR) irradiation. The shape of the determined DNP spectrum was similar to ESR absorption spectra with doublet spectral peaks. The relative locational relationship of spectral peaks in the DNP spectra between the AFR (520 and 525 MHz), (14)N-labeled carbamoyl-PROXYL ((14)N-CmP) (526.5 MHz), and Oxo63 (522 MHz) was different from that in the X-band ESR spectra, but were similar to that in the 300-MHz ESR spectra. The ratio of DNP enhancement to radical concentration for the AFR was higher than those for (14)N-CmP, Oxo63, and flavin semiquinone radicals. The spectroscopic DNP properties observed for the AFR were essentially the same as those for AFR mediated by pyrroloquinoline quinone. Moreover, we made a success of in vivo DNP-MR imaging of the CoQ0-mediated AFR which was administered by the subcutaneous and oral injections as an imaging probe.

Discovery and Asteroseismological Analysis of the Pulsating sdB Star PG 0014+067

NASA Astrophysics Data System (ADS)

Brassard, P.; Fontaine, G.; Billères, M.; Charpinet, S.; Liebert, James; Saffer, R. A.

2001-12-01

We report the discovery of low-amplitude, short-period, multiperiodic luminosity variations in the hot B subdwarf PG 0014+067. This star was selected as a potential target in the course of our ongoing survey to search for pulsators of the EC 14026 type. Our model atmosphere analysis of the time-averaged Multiple Mirror Telescope (MMT) optical spectrum of PG 0014+067 indicates that this star has Teff=33,550+/-380 K and logg=5.77+/-0.10, which places it right in the middle of the theoretical EC 14026 instability region in the logg-Teff plane. A standard analysis of our Canada-France-Hawaii Telescope (CFHT) light curve reveals the presence of at least 13 distinct harmonic oscillations with periods in the range 80-170 s. Fine structure (closely spaced frequency doublets) is observed in three of these oscillations, and five high-frequency peaks due to nonlinear cross frequency superpositions of the basic oscillations are also possibly seen in the Fourier spectrum. The largest oscillation has an amplitude ~=0.22% of the mean brightness of the star, making PG 0014+067 the EC 14026 star with the smallest intrinsic amplitudes so far. On the basis of the 13 observed periods, we carry out a detailed asteroseismological analysis of the data starting with an extensive search in parameter space for a model that could account for the observations. To make this search efficient, objective, and reliable, we use a newly developed period matching technique based on an optimization algorithm. This search leads to a model that can account remarkably well for the 13 observed periods in the light curve of PG 0014+067. A detailed comparison of the theoretical period spectrum of this optimal model with the distribution of the 13 observed periods leads to the realization that 10 other pulsations, with lower amplitudes than the threshold value used in our standard analysis, are probably present in the light curve of PG 0014+067. Altogether, we tentatively identify 23 distinct pulsation modes in our target star (counting the frequency doublets referred to above as single modes). These are all low-order acoustic modes with adjacent values of k and with l=0, 1, 2, and 3. They define a band of unstable periods, in close agreement with nonadiabatic pulsation theory. Furthermore, the average relative dispersion between the 23 observed periods and the periods of the corresponding 23 theoretical modes of the optimal model is only ~=0.8%, a remarkable achievement by asteroseismological standards. On the basis of our analysis, we infer that the global structural parameters of PG 0014+067 are logg=5.780+/-0.008, Teff=34,500K+/-2690 K, M*/Msolar=0.490+/-0.019, log(Menv/M*)=-4.31+/-0.22, and R/Rsolar=0.149+/-0.004. If we combine these estimates of the surface gravity, total mass, and radius with our value of the spectroscopic temperature (which is more accurately evaluated than its asteroseismological counterpart, in direct contrast to the surface gravity), we also find that PG 0014+067 has a luminosity L/Lsolar=25.5+/-2.5, has an absolute visual magnitude MV=4.48+/-0.12, and is located at a distance d=1925+/-195 pc (using V=15.9+/-0.1). If we interpret the fine structure (frequency doublets) observed in three of the 23 pulsations in terms of rotational splitting, we further find that PG 0014+067 rotates with a period of 29.2+/-0.9 hr and has a maximum rotational broadening velocity of Vsini<~6.2+/-0.4 km s-1. Based on observations gathered at the Canada-France-Hawaii Telescope, operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique de France, and the University of Hawaii.

Synthesis of C13- and N15-Labeled DNAN

DTIC Science & Technology

2014-07-24

Multiplicities are described as singlet (s), doublet (d), triplet (t), quartet (q), doublet of doublets (dd), doublet of doublet of doublets ( ddd ), multiplet...dd, 4.8Hz, 2.6Hz, 1H), 8.40 ( ddd , 8.8Hz, 2.6Hz, 1.8Hz, 1H), and 7.81 (d, 8.8Hz, 1H) ppm. 13C NMR (CDCl3): δ 147.8 (dd, 18Hz, 3Hz), 146.3 (dd, 17Hz...Dinitroanisole mp: 86-88 °C 1H NMR (CDCl3): δ 8.77 (m, 4.8Hz, 2.6Hz, 1H), 8.46 ( ddd , 9.2Hz, 2.6Hz, 1.8Hz, 1H), 7.23 (d, 9.2Hz, 1H), and 4.10 (s, 3H

Elve Doublets: The Ionospheric Fingerprints of Compact Intracloud Discharges

NASA Astrophysics Data System (ADS)

da Silva, C. L.; Marshall, R. A.; Pasko, V. P.

2015-12-01

Compact intracloud discharges (CIDs) persist to date as one of the most mysterious lightning manifestations. CIDs are known to be the strongest natural sources of radio-frequency radiation on Earth. At VHF frequencies, approximately above 30 MHz, their emitted power is ten times stronger than that of other lightning processes. The well-known strength of CIDs in VHF contrasts with the lack of substantial optical measurements. CID's VLF/LF electric field change waveforms resemble one full cycle of a distorted sine function, with the first half-cycle being (a few times) larger-amplitude and shorter-duration than the second. For this reason CIDs have been dubbed narrow bipolar events (NBEs). NBE waveshapes are strikingly similar to the largest initial breakdown pulses (IBPs) that occur during the earlier stages of a conventional lightning flash, called classic IBPs. The similarity between classic IBP and NBE far-field waveforms, combined with the fact that positive-polarity NBEs frequently appear as the first event in an otherwise regular positive intracloud discharge, may be indicative that the source of these two E-field pulse types share the same physical mechanism inside thunderclouds [da Silva and Pasko, JGR, 120, 4989-5009, 2015]. In this presentation, we introduce a novel way to investigate CIDs. We show evidence that CIDs can produce an unique ionospheric signature, named "elve doublets". These signatures are characterized by a pair of elves separated in time by 80-160 microseconds. Our analysis combines fast photometric elve data, equivalent-transmission-line models to describe the dynamics of CID source currents, and FDTD modeling of electromagnetic wave propagation in the Earth-ionosphere waveguide accounting for its nonlinear interaction with the lower ionosphere [Marshall et al., GRL, 42, 2015, doi:10.1002/2015GL064862]. We show that typical (negative-polarity) CID altitudes, between 14-22 km, explain the time delay observed in elve doublets, where the first elve in the doublet is generated by the direct EMP path and the second is generated by its ground reflection. Furthermore, we show that the relative brightness of the first and second elves is likely related to the CID orientation, and angles of 5°-20° with respect to the vertical are consistent with the observed brightness ratios.

An Improved Red Spectrum of the Methane or T Dwarf SDSS 1624+0029: The Role of the Alkali Metals.

PubMed

Liebert; Reid; Burrows; Burgasser; Kirkpatrick; Gizis

2000-04-20

A Keck II low-resolution spectrum shortward of 1 µm is presented for SDSS 1624+0029, the first field methane or T dwarf discovered in the Sloan Digital Sky Survey. Significant flux is detected down to the spectrum's short-wavelength limit of 6200 Å. The spectrum exhibits a broad absorption feature centered at 7700 Å, which we interpret as the K i lambdalambda7665, 7699 resonance doublet. The observed flux declines shortward of 7000 Å, most likely owing to the red wing of the Na i doublet. Both Cs i doublet lines are detected more strongly than in an earlier red spectrum. Neither Li i absorption nor Halpha emission are detected. An exploratory model fit to the spectrum suggests that the shape of the red spectrum can be primarily accounted for by the broad wings of the K i and Na i doublets. This behavior is consistent with the argument proffered by Burrows, Marley, & Sharp that strong alkali absorption is principally responsible for depressing T dwarf spectra shortward of 1 µm. In particular, there seems no compelling reason at this time to introduce dust or an additional opacity source in the atmosphere of the Sloan object. The width of the K i and strengths of the Cs i lines also indicate that the Sloan object is warmer than Gl 229B.

Non-resonant electromechanical energy harvesting using inter-ferroelectric phase transitions

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

Pérez Moyet, Richard; Rossetti, George A., E-mail: george.rossetti-jr@uconn.edu; Stace, Joseph

Non-resonant electromechanical energy harvesting is demonstrated under low frequency excitation (<50 Hz) using [110]{sub C}-poled lead indium niobate-lead magnesium niobate-lead titanate relaxor ferroelectric single crystals with compositions near the morphotropic phase boundary. The efficiency of power generation at the stress-induced phase transition between domain-engineered rhombohedral and orthorhombic ferroelectric states is as much as four times greater than is obtained in the linear piezoelectric regime under identical measurement conditions but during loading below the coercive stress of the phase change. The phase transition mode of electromechanical transduction holds potential for non-resonant energy harvesting from low-frequency vibrations and does not require mechanical frequencymore » up-conversion.« less

Adaptive spatial filtering using photochromic glass

NASA Astrophysics Data System (ADS)

Potton, R. J.

1999-12-01

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

DE-1 and COSMOS 1809 observations of lower hybrid waves excited by VLF whistler mode waves

NASA Technical Reports Server (NTRS)

Bell, T. F; Inan, U. S.; Lauben, D.; Sonwalkar, V. S.; Helliwell, R. A.; Sobolev, Ya. P.; Chmyrev, V. M.; Gonzalez, S.

1994-01-01

Past work demostrates that strong lower hybrid (LH) waves can be excited by electromagnetic whistler mode waves throughout large regions of the topside ionosphere and magnetosphere. The effects of the excited LH waves upon the suprathermal ion population in the topside ionosphere and magnetosphere depend upon the distribution of LH wave amplitude with wavelength lambda. The present work reports plasma wave data from the DE-1 and COSMOS 1809 spacecraft which suggests that the excited LH wave spectrum has components for which lambda less than or equal to 3.5 m when excitation occurs at a frequency roughly equal to the local lower hybrid resonance frequency. This wavelength limit is a factor of approximately 3 below that reported in past work and suggests that the excited LH waves can interact with suprathermal H(+) ions with energy less than or equal to 6 eV. This finding supports recent work concerning the heating of suprathermal ions above thunderstorm cells.

Fate of the insecticide lambda-cyhalothrin in ditch enclosures differing in vegetation density.

PubMed

Leistra, Minze; Zweers, Anton J; Warinton, Jacqui S; Crum, Steven J H; Hand, Laurence H; Beltman, Wim H J; Maund, Stephen J

2004-01-01

Use of the insecticide lambda-cyhalothrin in agriculture may result in the contamination of water bodies, for example by spray drift. Therefore, the possible exposure of aquatic organisms to this insecticide needs to be evaluated. The exposure of the organisms may be reduced by the strong sorption of the insecticide to organic materials and its susceptibility to hydrolysis at the high pH values in the natural range. In experiments done in May and August, formulated lambda-cyhalothrin was mixed with the water body of enclosures in experimental ditches containing a bottom layer and macrophytes (at different densities) or phytoplankton. Concentrations of lambda-cyhalothrin in the water body and in the sediment layer, and contents in the plant compartment, were measured by gas-liquid chromatography at various times up to 1 week after application. Various water quality parameters were also measured. Concentrations of lambda-cyhalothrin decreased rapidly in the water column: 1 day after application, 24-40% of the dose remained in the water, and by 3 days it had declined to 1.8-6.5%. At the highest plant density, lambda-cyhalothrin residue in the plant compartment reached a maximum of 50% of the dose after 1 day; at intermediate and low plant densities, this maximum was only 3-11% of the dose (after 1-2 days). The percentage of the insecticide in the ditch sediment was 12% or less of the dose and tended to be lower at higher plant densities. Alkaline hydrolysis in the water near the surface of macrophytes and phytoplankton is considered to be the main dissipation process for lambda-cyhalothrin.

Breakdown of doublet recirculation and direct line drives by far-field flow in reservoirs: implications for geothermal and hydrocarbon well placement

NASA Astrophysics Data System (ADS)

Weijermars, R.; van Harmelen, A.

2016-07-01

An important real world application of doublet flow occurs in well design of both geothermal and hydrocarbon reservoirs. A guiding principle for fluid management of injection and extraction wells is that mass balance is commonly assumed between the injected and produced fluid. Because the doublets are considered closed loops, the injection fluid is assumed to eventually reach the producer well and all the produced fluid ideally comes from stream tubes connected to the injector of the well pair making up the doublet. We show that when an aquifer background flow occurs, doublets will rarely retain closed loops of fluid recirculation. When the far-field flow rate increases relative to the doublet's strength, the area occupied by the doublet will diminish and eventually vanishes. Alternatively, rather than using a single injector (source) and single producer (sink), a linear array of multiple injectors separated by some distance from a parallel array of producers can be used in geothermal energy projects as well as in waterflooding of hydrocarbon reservoirs. Fluid flow in such an arrangement of parallel source-sink arrays is shown to be macroscopically equivalent to that of a line doublet. Again, any far-field flow that is strong enough will breach through the line doublet, which then splits into two vortices. Apart from fundamental insight into elementary flow dynamics, our new results provide practical clues that may contribute to improve the planning and design of doublets and direct line drives commonly used for flow management of groundwater, geothermal and hydrocarbon reservoirs.

Computer simulation of flagellar movement VIII: coordination of dynein by local curvature control can generate helical bending waves.

PubMed

Brokaw, Charles J

2002-10-01

Computer simulations have been carried out with a model flagellum that can bend in three dimensions. A pattern of dynein activation in which regions of dynein activity propagate along each doublet, with a phase shift of approximately 1/9 wavelength between adjacent doublets, will produce a helical bending wave. This pattern can be termed "doublet metachronism." The simulations show that doublet metachronism can arise spontaneously in a model axoneme in which activation of dyneins is controlled locally by the curvature of each outer doublet microtubule. In this model, dyneins operate both as sensors of curvature and as motors. Doublet metachronism and the chirality of the resulting helical bending pattern are regulated by the angular difference between the direction of the moment and sliding produced by dyneins on a doublet and the direction of the controlling curvature for that doublet. A flagellum that is generating a helical bending wave experiences twisting moments when it moves against external viscous resistance. At high viscosities, helical bending will be significantly modified by twist unless the twist resistance is greater than previously estimated. Spontaneous doublet metachronism must be modified or overridden in order for a flagellum to generate the planar bending waves that are required for efficient propulsion of spermatozoa. Planar bending can be achieved with the three-dimensional flagellar model by appropriate specification of the direction of the controlling curvature for each doublet. However, experimental observations indicate that this "hard-wired" solution is not appropriate for real flagella. Copyright 2002 Wiley-Liss, Inc.

Spectroscopic characterization of HD 95086 b with the Gemini Planet Imager

DOE PAGES

De Rosa, Robert J.; Rameau, Julien; Patience, Jenny; ...

2016-06-21

Here, we present new H (1.5–1.8 μm) photometric and K 1 (1.9–2.2 μm) spectroscopic observations of the young exoplanet HD 95086 b obtained with the Gemini Planet Imager. The H-band magnitude has been significantly improved relative to previous measurements, whereas the low-resolution K 1 (more » $$\\lambda /\\delta \\lambda \\approx 66$$) spectrum is featureless within the measurement uncertainties and presents a monotonically increasing pseudo-continuum consistent with a cloudy atmosphere. By combining these new measurements with literature $$L^{\\prime} $$ photometry, we compare the spectral energy distribution (SED) of the planet to other young planetary-mass companions, field brown dwarfs, and to the predictions of grids of model atmospheres. HD 95086 b is over a magnitude redder in $${K}_{1}-L^{\\prime} $$ color than 2MASS J12073346–3932539 b and HR 8799 c and d, despite having a similar $$L^{\\prime} $$ magnitude. Considering only the near-infrared measurements, HD 95086 b is most analogous to the brown dwarfs 2MASS J2244316+204343 and 2MASS J21481633+4003594, both of which are thought to have dusty atmospheres. Morphologically, the SED of HD 95086 b is best fit by low temperature ($${T}_{{\\rm{eff}}}$$ = 800–1300 K), low surface gravity spectra from models which simulate high photospheric dust content. This range of effective temperatures is consistent with field L/T transition objects, but the spectral type of HD 95086 b is poorly constrained between early L and late T due to its unusual position the color–magnitude diagram, demonstrating the difficulty in spectral typing young, low surface gravity substellar objects. As one of the reddest such objects, HD 95086 b represents an important empirical benchmark against which our current understanding of the atmospheric properties of young extrasolar planets can be tested.« less

Visibility of wavelet quantization noise

NASA Technical Reports Server (NTRS)

Watson, A. B.; Yang, G. Y.; Solomon, J. A.; Villasenor, J.

1997-01-01

The discrete wavelet transform (DWT) decomposes an image into bands that vary in spatial frequency and orientation. It is widely used for image compression. Measures of the visibility of DWT quantization errors are required to achieve optimal compression. Uniform quantization of a single band of coefficients results in an artifact that we call DWT uniform quantization noise; it is the sum of a lattice of random amplitude basis functions of the corresponding DWT synthesis filter. We measured visual detection thresholds for samples of DWT uniform quantization noise in Y, Cb, and Cr color channels. The spatial frequency of a wavelet is r 2-lambda, where r is display visual resolution in pixels/degree, and lambda is the wavelet level. Thresholds increase rapidly with wavelet spatial frequency. Thresholds also increase from Y to Cr to Cb, and with orientation from lowpass to horizontal/vertical to diagonal. We construct a mathematical model for DWT noise detection thresholds that is a function of level, orientation, and display visual resolution. This allows calculation of a "perceptually lossless" quantization matrix for which all errors are in theory below the visual threshold. The model may also be used as the basis for adaptive quantization schemes.

Repeating Deep Very Low Frequency Earthquakes: An Evidence of Transition Zone between Brittle and Ductile Zone along Plate Boundary

NASA Astrophysics Data System (ADS)

Ishihara, Y.; Yamamoto, Y.; Arai, R.

2017-12-01

Recently slow or low frequency seismic and geodetic events are focused under recognition of important role in tectonic process. The most western region of Ryukyu trench, Yaeyama Islands, is very active area of these type events. It has semiannual-like slow slip (Heki et.al., 2008; Nishimura et.al.,2014) and very frequent shallow very low frequency earthquakes near trench zone (Ando et.al.,2012; Nakamura et.al.,2014). Arai et.al.(2016) identified clear reverse phase discontinuity along plate boundary by air-gun survey, suggesting existence of low velocity layer including fluid. The subducting fluid layer is considered to control slip characteristics. On the other hand, deep low frequency earthquake and tremor observed at south-western Honshu and Shikoku of Japan are not identified well due to lack of high-quality seismic network. A broadband seismic station(ISG/PS) of Pacific21 network is operating in last 20 years that locates on occurrence potential area of low frequency earthquake. We tried to review continuous broadband record, searching low frequency earthquakes. In pilot survey, we found three very low frequency seismic events which are dominant in less than 0.1Hz component and are not listed in earthquake catalogue. Source locates about 50km depth and at transition area between slow slip event and active area of general earthquake along plate boundary. To detect small and/or hidden very low frequency earthquake, we applied matched filter analysis to continuous three components waveform data using pre-reviewed seismogram as template signal. 12 events with high correlation are picked up in last 10 years. Most events have very similar waveform, which means characteristics of repeating deep very low frequency earthquake. The event history of very low frequency earthquake is not related with one of slow slip event in this region. In Yaeyama region, low frequency earthquake, general earthquake and slow slip event occur dividing in space and have apparent independent activity. Further 3D survey around plate boundary may take us important understanding of controlling feature of seismic and geodetic slip.

Shell-model predictions for Lambda Lambda hypernuclei

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

Gal, A.; Millener, D.

2011-06-02

It is shown how the recent shell-model determination of {Lambda}N spin-dependent interaction terms in {Lambda} hypernuclei allows for a reliable deduction of {Lambda}{Lambda} separation energies in {Lambda}{Lambda} hypernuclei across the nuclear p shell. Comparison is made with the available data, highlighting {sub {Lambda}{Lambda}}{sup 11}Be and {sub {Lambda}{Lambda}}{sup 12}Be which have been suggested as possible candidates for the KEK-E373 HIDA event.

Microwave-Based Oxidation State and Soot Loading Determination on Gasoline Particulate Filters with Three-Way Catalyst Coating for Homogenously Operated Gasoline Engines.

PubMed

Dietrich, Markus; Jahn, Christoph; Lanzerath, Peter; Moos, Ralf

2015-09-02

Recently, a novel method emerged to determine the oxygen storage degree of three way catalysts (TWC) by a microwave-based method. Up to now, this method has been investigated only in lab-scale reactors or under steady state conditions. This work expands those initial studies. A TWC-coated gasoline particulate filter was investigated in a dynamic engine test bench simulating a typical European driving cycle (NEDC). It could be shown that both the oxygen storage degree and the soot loading can be monitored directly, but not simultaneously due to their competitive effects. Under normal driving conditions, no soot accumulation was observed, related to the low raw emissions and the catalytic coating of the filter. For the first time, the quality factor of the cavity resonator in addition to the resonance frequency was used, with the benefit of less cross sensitivity to inconstant temperature and water. Therefore, a temperature dependent calibration of the microwave signal was created and applied to monitor the oxidation state in transient driving cycles. The microwave measurement mirrors the oxidation state determined by lambda probes and can be highly beneficial in start-stop phases (where lambda-probes do not work) and to determine the oxygen storage capacity (OSC) without unnecessary emissions.

Microwave-Based Oxidation State and Soot Loading Determination on Gasoline Particulate Filters with Three-Way Catalyst Coating for Homogenously Operated Gasoline Engines

PubMed Central

Dietrich, Markus; Jahn, Christoph; Lanzerath, Peter; Moos, Ralf

2015-01-01

Recently, a novel method emerged to determine the oxygen storage degree of three way catalysts (TWC) by a microwave-based method. Up to now, this method has been investigated only in lab-scale reactors or under steady state conditions. This work expands those initial studies. A TWC-coated gasoline particulate filter was investigated in a dynamic engine test bench simulating a typical European driving cycle (NEDC). It could be shown that both the oxygen storage degree and the soot loading can be monitored directly, but not simultaneously due to their competitive effects. Under normal driving conditions, no soot accumulation was observed, related to the low raw emissions and the catalytic coating of the filter. For the first time, the quality factor of the cavity resonator in addition to the resonance frequency was used, with the benefit of less cross sensitivity to inconstant temperature and water. Therefore, a temperature dependent calibration of the microwave signal was created and applied to monitor the oxidation state in transient driving cycles. The microwave measurement mirrors the oxidation state determined by lambda probes and can be highly beneficial in start-stop phases (where lambda-probes do not work) and to determine the oxygen storage capacity (OSC) without unnecessary emissions. PMID:26340629

New stable tunable solid-state dye laser in the red

NASA Astrophysics Data System (ADS)

Gvishi, Raz; Reisfeld, Renata; Burshtein, Zeev; Miron, Eli

1993-08-01

A red perylene derivative was impregnated into a composite silica-gel glass, and characterized as a dye laser material. The absorption spectrum in the range 480 - 600 nm belongs to the S0 - S1 electronic transition, with a structure reflecting the perylene skeletal vibrations, of typical energy 1100 - 1200 cm-1. An additional peak between 400 and 460 nm belongs to the S0 - S2 transition. The fluorescence exhibits a mirror image relative to the S0 - S1 absorption, with a Stokes shift of about 40 nm for the 0 - 0 transition. Laser tunability was obtained in the range 605 - 630 nm using a frequency-doubled Nd:YAG laser for pumping ((lambda) equals 532 nm). This wavelength range is important for medical applications, such as photodynamic therapy of some cancer tumors. Maximum laser efficiency of approximately 2.5% was obtained at 617 nm. Maximum output was approximately 0.36 mJ/pulse at a repetition rate of 10 Hz. Minimum laser threshold obtained was 0.45 mJ/pulse. The medium losses are attributed to an excited-state singlet-singlet absorption, with an upper limit cross-section of approximately 2.5 X 10-16 cm2. The laser output was stable over more than approximately 500,000 pulses, under excitation with the green line of a copper vapor laser (510 nm), of energy density approximately 40 mJ/cm2 per pulse. Good prospects exist for a considerable enhancement in laser output efficiency.

Boundary layer transition detection on the X-15 vertical fin using surface-pressure-fluctuation measurements

NASA Technical Reports Server (NTRS)

Lewis, T. L.; Banner, R. D.

1971-01-01

A flush-mounted microphone on the vertical fin of an X-15 airplane was used to investigate boundary layer transition phenomenon during flights to peak altitudes of approximately 70,000 meters. The flight results were compared with those from wind tunnel studies, skin temperature measurements, and empirical prediction data. The Reynolds numbers determined for the end of transition were consistent with those obtained from wind tunnel studies. Maximum surface-pressure-fluctuation coefficients in the transition region were about an order of magnitude greater than those for fully developed turbulent flow. This was also consistent with wind tunnel data. It was also noted that the power-spectral-density estimates of the surface-pressure fluctuations were characterized by a shift in power from high frequencies to low frequencies as the boundary layer changed from turbulent to laminar flow. Large changes in power at the lowest frequencies appeared to mark the beginning of transition.

Recent Developments in Ground-Borne Noise and Vibration Control

NASA Astrophysics Data System (ADS)

Nelson, J. T.

1996-05-01

Vibration control provisions available to the transit designer include (among others) precision straightened rail, ballast mats, floating slabs and very soft direct fixation fasteners, in addition to rail grinding, wheel truing, and continuous welded rail. Recently, the Los Angeles Metro has developed specifications for a soft resilient direct fixation fastener to fit the same base dimensions as the standard direct fixation fastener. In San Francisco, low resonance frequency (8 Hz) floating slabs have been constructed to mitigate predicted ground vibration impacts at nearby residential structures. In Atlanta, low resonance frequency loading slabs have been constructed to maintain a low vibration environment in a medical building planned to be built over the subway structure. In Portland and Pasadena, ballast mats have been recommended to control light rail transit ground vibration impacts on housing located at typically 35 feet from the alignment. Each of these provisions are briefly described in view of recent applications at U.S. transit systems.

Collision Avoidance W-Band FMCW Radars in an Altimeter Application

DTIC Science & Technology

2006-08-01

underground mining applications. Potentially, a small low– powered downward looking aerial radar employing Frequency Modulated Continuous Wave (FMCW) ranging...frequency [1]. 3 Figure 3: Epsilon Lambda ELF 171-1A radar. Model and System block diagram [2]. 4 Figure 4: Beam limited resolution cell (after [3]). 6...Figure 5: (black curves) Projected SNR variation of clutter return with range for ELF 171-1A type system in different weather conditions. Clutter-to

Broad NE 8 lambda 774 emission from quasars in the HST-FOS snapshot survey (ABSNAP)

NASA Technical Reports Server (NTRS)

Hamann, Fred; Zuo, Lin; Tytler, David

1995-01-01

We discuss the strength and frequency of broad Ne VIII lambda 774 emission from quasars measured in the Hubble Space Telescope Faint Object Spectrograph (HST-FOS) snapshot survey (Absnap). Five sources in the survey have suitable redshifts (0.86 less than or equal to Z(sub em) less than or equal to 1.31), signal-to-noise ratios and no Lyman limit absorptions. Three of the five sources have a strong broad emission line near 774 A (rest), and the remaining two sources have a less securely measured line near this wavelength. We identify these lines with Ne VIII lambda 774 based on the measured wavelengths and theoretical estimates of various line fluxes (Hamann et al. 1995a). Secure Ne VIII detections occur in both radio-loud and radio-quiet sources. We tentatively conclude that broad Ne VIII lambda 774 emission is common in quasars, with typical strengths between approximately 25% and approximately 200% of O VI lambda 1034. These Ne VIII lambda 774 measurements imply that the broad emission line regions have a much hotter and more highly ionized component than previously recognized. They also suggest that quasar continua have substantial ionizing flux out to energies greater than 207 eV (greater than 15.2 ryd, lambda less than 60 A). Photoionization calculations using standard incident spectra indicate that the Ne VIII emission requires ionization parameters U greater than or = 5, total column densities N(sub H) greater than or = 10(sub 22)/sq cm and covering factors greater than or = 25%. The temperatures could be as high as approximately 10(exp 5) K. If the gas is instead collisionally ionized, strong Ne VIII would imply equilibrium temperatures in the range approximately 400,000 less than or approximately = T(sub e) less than or approximately = 10(exp 6) K. In either case, the highly ionized Ne VIII emission regions would appear as X-ray 'warm absorbers' if they lie along our line of sight to the X-ray continuum source.

Experimental investigation of mode transitions in asymmetric capacitively coupled radio-frequency Ne and CF4 plasmas

NASA Astrophysics Data System (ADS)

Liu, Gang-Hu; Liu, Yong-Xin; Bai, Li-Shui; Zhao, Kai; Wang, You-Nian

2018-02-01

The dependence of the electron density and the emission intensity on external parameters during the transitions of the electron power absorption mode is experimentally studied in asymmetric electropositive (neon) and electronegative (CF4) capacitively coupled radio-frequency plasmas. The spatio-temporal distribution of the emission intensity is measured with phase resolved optical emission spectroscopy and the electron density at the discharge center is measured by utilizing a floating hairpin probe. In neon discharge, the emission intensity increases almost linearly with the rf voltage at all driving frequencies covered here, while the variation of the electron density with the rf voltage behaves differently at different driving frequencies. In particular, the electron density increases linearly with the rf voltage at high driving frequencies, while at low driving frequencies the electron density increases slowly at the low-voltage side and, however, grows rapidly, when the rf voltage is higher than a certain value, indicating a transition from α to γ mode. The rf voltage, at which the mode transition occurs, increases with the decrease of the driving frequency/the working pressure. By contrast, in CF4 discharge, three different electron power absorption modes can be observed and the electron density and emission intensity do not exhibit a simple dependence on the rf voltage. In particular, the electron density exhibits a minimum at a certain rf voltage when the electron power absorption mode is switching from drift-ambipolar to the α/γ mode. A minimum can also be found in the emission intensity at a higher rf voltage when a discharge is switching into the γ mode.

Quark-lepton flavor democracy and the nonexistence of the fourth generation

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

Cvetic, G.; Kim, C.S.

1995-01-01

In the standard model with two Higgs doublets (type II), which has a consistent trend to a flavor gauge theory and its related flavor democracy in the quark and the leptonic sectors (unlike the minimal standard model) when the energy of the probes increases, we impose the mixed quark-lepton flavor democracy at high transition'' energy and assume the usual seesaw mechanism, and consequently find out that the existence of the fourth generation of fermions in this framework is practically ruled out.

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

Winn, Joshua N.; Albrecht, Simon; Johnson, John Asher

We present new radial velocity (RV) measurements of HAT-P-13, a star with two previously known companions: a transiting giant planet 'b' with an orbital period of 3 days and a more massive object 'c' on a 1.2 yr, highly eccentric orbit. For this system, dynamical considerations would lead to constraints on planet b's interior structure, if it could be shown that the orbits are coplanar and apsidally locked. By modeling the Rossiter-McLaughlin effect, we show that planet b's orbital angular momentum vector and the stellar spin vector are well aligned on the sky ({lambda} = 1.9 {+-} 8.6 deg). Themore » refined orbital solution favors a slightly eccentric orbit for planet b (e = 0.0133 {+-} 0.0041), although it is not clear whether it is apsidally locked with c's orbit ({Delta}{omega} = 36{sup +27}{sub -36} deg). We find a long-term trend in the star's RV and interpret it as evidence for an additional body 'd', which may be another planet or a low-mass star. Predictions are given for the next few inferior conjunctions of c, when transits may happen.« less

Evaluation of the lambda model for human postural control during ankle strategy.

PubMed

Micheau, Philippe; Kron, Aymeric; Bourassa, Paul

2003-09-01

An accurate modeling of human stance might be helpful in assessing postural deficit. The objective of this article is to validate a mathematical postural control model for quiet standing posture. The postural dynamics is modeled in the sagittal plane as an inverted pendulum with torque applied at the ankle joint. The torque control system is represented by the physiological lambda model. Two neurophysiological command variables of the central nervous system, designated lambda and micro, establish the dynamic threshold muscle at which motoneuron recruitment begins. Kinematic data and electromyographic signals were collected on four young males in order to measure small voluntary sway and quiet standing posture. Validation of the mathematical model was achieved through comparison of the experimental and simulated results. The mathematical model allows computation of the unmeasurable neurophysiological commands lambda and micro that control the equilibrium position and stability. Furthermore, with the model it is possible to conclude that low-amplitude body sway during quiet stance is commanded by the central nervous system.

Calculations of low-frequency radio emission by cosmic-ray-induced particle showers

NASA Astrophysics Data System (ADS)

García-Fernández, Daniel; Revenu, Benoît; Charrier, Didier; Dallier, Richard; Escudie, Antony; Martin, Lilian

2018-05-01

The radio technique for the detection of high-energy cosmic rays consists in measuring the electric field created by the particle showers created inside a medium by the primary cosmic ray. The electric field is then used to infer the properties of the primary particle. Nowadays, the radio technique is a standard, well-established technique. While most current experiments measure the field at frequencies above 20 MHz, several experiments have reported a large emission at low frequencies, below 10 MHz. The EXTASIS experiment aims at measuring again and understanding this low-frequency electric field. Since at low frequencies the standard far-field approximation for the calculation of the electric field does not necessarily hold, in order to comprehend the low-frequency emission we need to go beyond the far-field approximation. We present in this work a formula for the electric field created by a particle track inside a dielectric medium that is valid for all frequencies. We then implement this formula in the SELFAS Monte Carlo code and calculate the low-frequency electric field of the extensive air shower (EAS). We also study the electric field of a special case of the transition radiation mechanism when the EAS particles cross the air-soil boundary. We introduce the sudden death pulse, the direct emission caused by the coherent deceleration of the shower front at the boundary, as a first approximation to the whole electric field for the air-soil transition, and study its properties. We show that at frequencies larger than 20 MHz and distances larger than 100 m, the standard far-field approximation for the horizontal polarizations of the field is always accurate at the 1% level.

Measurement of the forward-backward asymmetry of $$\\Lambda$$ and $$\\bar{\\Lambda}$$ production in $$p \\bar{p}$$ collisions

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

Abazov, Victor Mukhamedovich

Here, we studymore » $$\\Lambda$$ and $$\\bar{\\Lambda}$$ production asymmetries in $$p \\bar{p} \\rightarrow \\Lambda (\\bar{\\Lambda}) X$$, $$p \\bar{p} \\rightarrow J/\\psi \\Lambda (\\bar{\\Lambda}) X$$, and $$p \\bar{p} \\rightarrow \\mu^\\pm \\Lambda (\\bar{\\Lambda}) X$$ events recorded by the D0 detector at the Fermilab Tevatron collider at $$\\sqrt{s} = 1.96$$ TeV. We find an excess of $$\\Lambda$$'s ($$\\bar{\\Lambda}$$'s) produced in the proton (antiproton) direction. This forward-backward asymmetry is measured as a function of rapidity. We confirm that the $$\\bar{\\Lambda}/\\Lambda$$ production ratio, measured by several experiments with various targets and a wide range of energies, is a universal function of "rapidity loss", i.e., the rapidity difference of the beam proton and the lambda.« less

Measurement of the forward-backward asymmetry of $$\\Lambda$$ and $$\\bar{\\Lambda}$$ production in $$p \\bar{p}$$ collisions

DOE PAGES

Abazov, Victor Mukhamedovich

2016-02-09

Here, we studymore » $$\\Lambda$$ and $$\\bar{\\Lambda}$$ production asymmetries in $$p \\bar{p} \\rightarrow \\Lambda (\\bar{\\Lambda}) X$$, $$p \\bar{p} \\rightarrow J/\\psi \\Lambda (\\bar{\\Lambda}) X$$, and $$p \\bar{p} \\rightarrow \\mu^\\pm \\Lambda (\\bar{\\Lambda}) X$$ events recorded by the D0 detector at the Fermilab Tevatron collider at $$\\sqrt{s} = 1.96$$ TeV. We find an excess of $$\\Lambda$$'s ($$\\bar{\\Lambda}$$'s) produced in the proton (antiproton) direction. This forward-backward asymmetry is measured as a function of rapidity. We confirm that the $$\\bar{\\Lambda}/\\Lambda$$ production ratio, measured by several experiments with various targets and a wide range of energies, is a universal function of "rapidity loss", i.e., the rapidity difference of the beam proton and the lambda.« less

Fast-sausage oscillations in coronal loops with smooth boundary

NASA Astrophysics Data System (ADS)

Lopin, I.; Nagorny, I.

2014-12-01

Aims: The effect of the transition layer (shell) in nonuniform coronal loops with a continuous radial density profile on the properties of fast-sausage modes are studied analytically and numerically. Methods: We modeled the coronal waveguide as a structured tube consisting of a cord and a transition region (shell) embedded within a magnetic uniform environment. The derived general dispersion relation was investigated analytically and numerically in the context of frequency, cut-off wave number, and the damping rate of fast-sausage oscillations for various values of loop parameters. Results: The frequency of the global fast-sausage mode in the loops with a diffuse (or smooth) boundary is determined mainly by the external Alfvén speed and longitudinal wave number. The damping rate of such a mode can be relatively low. The model of coronal loop with diffuse boundary can support a comparatively low-frequency, global fast-sausage mode of detectable quality without involving extremely low values of the density contrast. The effect of thin transition layer (corresponds to the loops with steep boundary) is negligible and produces small reductions of oscillation frequency and relative damping rate in comparison with the case of step-function density profile. Seismological application of obtained results gives the estimated Alfvén speed outside the flaring loop about 3.25 Mm/s.

Polarization effects in the interaction between multi-level atoms and two optical fields

NASA Astrophysics Data System (ADS)

Colín-Rodríguez, R.; Flores-Mijangos, J.; Hernández-Gómez, S.; Jáuregui, R.; López-Hernández, O.; Mojica-Casique, C.; Ponciano-Ojeda, F.; Ramírez-Martínez, F.; Sahagún, D.; Volke-Sepúlveda, K.; Jiménez-Mier, J.

2015-06-01

Polarized velocity selective spectra for rubidium atoms in a room temperature cell are presented. The experiments were performed in the lambda configuration (D2 manifold) and in the 5s\\to 5{{p}3/2}\\to 5{{d}j} ladder configuration. For the lambda configuration the effect of the probe beam intensity in the absorption and polarization spectra are compared with results of a rate equation approximation. Good overall agreement between experiment and theory is found. The results indicate different saturation rates for each of the atomic transitions. Distinctive polarization signals with hyperfine-resolved components are found for the ladder 5{{d}3/2} and 5{{d}5/2} upper states. Fluorescence detection of the 420 nm that results from the second step in the cascade decay 5{{d}j}\\to 6{{p}{{j\\prime }}}\\to 5s was used in the ladder experiments. This fluorescence was also used for the detection of the 5{{p}3/2}\\to 6{{p}3/2} electric dipole forbidden transition in atomic rubidium that occurs at 911 nm. The 6{{p}3/2} hyperfine structure was resolved in this continuous wave, non-dipole excitation.

Doublet Crater

NASA Image and Video Library

2010-12-22

This image from NASA Mars Odyssey is of a doublet crater located in Utopia Planitia, near the Elysium Volcanic region. Doublet craters are formed by simultaneous impact of a meteor that broke into two pieces prior to hitting the surface.

Analysis of grating doublets for achromatic beam-splitting

PubMed Central

Pacheco, Shaun; Milster, Tom; Liang, Rongguang

2015-01-01

Achromatic beam-splitting grating doublets are designed for both continuous phase and binary phase gratings. By analyzing the sensitivity to lateral shifts between the two grating layers, it is shown that continuous-profile grating doublets are extremely difficult to fabricate. Achromatic grating doublets that have profiles with a constant first spatial derivative are significantly more resistant to lateral shifts between grating layers, where one design case showed a 17 times improvement in performance. Therefore, binary phase, multi-level phase, and blazed grating doublets perform significantly better than continuous phase grating doublets in the presence of a lateral shift between two grating layers. By studying the sensitivity to fabrication errors in the height of both grating layers, one grating layer height can be adjusted to maintain excellent performance over a large wavelength range if the other grating layer is fabricated incorrectly. It is shown in one design case that the performance of an achromatic Dammann grating doublet can be improved by a factor of 215 if the heights of the grating layers are chosen to minimize the performance change in the presence of fabrication errors. PMID:26368261

Features of the Percolation Scheme of Vibrational Spectrum Reconstruction in the Ga1 - x Al x P Alloy

NASA Astrophysics Data System (ADS)

Kozyrev, S. P.

2018-04-01

Specific features of the properties of Ga-P lattice vibrations have been investigated using the percolation model of a mixed Ga1 - x Al x P crystal (alloy) with zero lattice mismatch between binary components of the alloy. In contrast to other two-mode alloy systems, in Ga1 - x Al x P a percolation splitting of δ 13 cm-1 is observed for the low-frequency mode of GaP-like vibrations. An additional GaP mode (one of the percolation doublet components) split from the fundamental mode is observed for the GaP-rich alloy, which coincides in frequency with the gap corresponding to the zero density of one-phonon states of the GaP crystal. The vibrational spectrum of impurity Al in the GaP crystal has been calculated using the theory of crystal lattice dynamics. Upon substitution of lighter Al for the Ga atom, the calculated spectrum includes, along with the local mode, a singularity near the gap with the zero density of phonon states of the GaP crystal, which coincides with the mode observed experimentally at a frequency of 378 cm-1 in the Ga1 - x Al x P ( x < 0.4) alloy.

Waveguide transition with vacuum window for multiband dynamic nuclear polarization systems

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

Rybalko, Oleksandr; Bowen, Sean; Zhurbenko, Vitaliy

2016-05-15

A low loss waveguide transition section and oversized microwave vacuum window covering several frequency bands (94 GHz, 140 GHz, 188 GHz) is presented. The transition is compact and was optimized for multiband Dynamic Nuclear Polarization (DNP) systems in a full-wave simulator. The window is more broadband than commercially available windows, which are usually optimized for single band operation. It is demonstrated that high-density polyethylene with urethane adhesive can be used as a low loss microwave vacuum window in multiband DNP systems. The overall assembly performance and dimensions are found using full-wave simulations. The practical aspects of the window implementation inmore » the waveguide are discussed. To verify the design and simulation results, the window is tested experimentally at the three frequencies of interest.« less

Electroencephalogram signatures of loss and recovery of consciousness from propofol

PubMed Central

Purdon, Patrick L.; Pierce, Eric T.; Mukamel, Eran A.; Prerau, Michael J.; Walsh, John L.; Wong, Kin Foon K.; Salazar-Gomez, Andres F.; Harrell, Priscilla G.; Sampson, Aaron L.; Cimenser, Aylin; Ching, ShiNung; Kopell, Nancy J.; Tavares-Stoeckel, Casie; Habeeb, Kathleen; Merhar, Rebecca; Brown, Emery N.

2013-01-01

Unconsciousness is a fundamental component of general anesthesia (GA), but anesthesiologists have no reliable ways to be certain that a patient is unconscious. To develop EEG signatures that track loss and recovery of consciousness under GA, we recorded high-density EEGs in humans during gradual induction of and emergence from unconsciousness with propofol. The subjects executed an auditory task at 4-s intervals consisting of interleaved verbal and click stimuli to identify loss and recovery of consciousness. During induction, subjects lost responsiveness to the less salient clicks before losing responsiveness to the more salient verbal stimuli; during emergence they recovered responsiveness to the verbal stimuli before recovering responsiveness to the clicks. The median frequency and bandwidth of the frontal EEG power tracked the probability of response to the verbal stimuli during the transitions in consciousness. Loss of consciousness was marked simultaneously by an increase in low-frequency EEG power (<1 Hz), the loss of spatially coherent occipital alpha oscillations (8–12 Hz), and the appearance of spatially coherent frontal alpha oscillations. These dynamics reversed with recovery of consciousness. The low-frequency phase modulated alpha amplitude in two distinct patterns. During profound unconsciousness, alpha amplitudes were maximal at low-frequency peaks, whereas during the transition into and out of unconsciousness, alpha amplitudes were maximal at low-frequency nadirs. This latter phase–amplitude relationship predicted recovery of consciousness. Our results provide insights into the mechanisms of propofol-induced unconsciousness, establish EEG signatures of this brain state that track transitions in consciousness precisely, and suggest strategies for monitoring the brain activity of patients receiving GA. PMID:23487781

Beryllium detection in the very fast nova ASASSN-16kt (V407 Lupi)

NASA Astrophysics Data System (ADS)

Izzo, L.; Molaro, P.; Bonifacio, P.; Della Valle, M.; Cano, Z.; de Ugarte Postigo, A.; Prieto, J. L.; Thöne, C.; Vanzi, L.; Zapata, A.; Fernandez, D.

2018-02-01

We present high-resolution spectroscopic observations of the fast nova ASASSN-16kt (V407 Lup). A close inspection of spectra obtained at early stages has revealed the presence of low-ionization lines, and among the others we have identified the presence of the ionised 7Be doublet in a region relatively free from possible contaminants. After studying their intensities, we have inferred that ASASSN-16kt has produced (5.9 - 7.7)× 10-9 M⊙ of 7Be. The identification of bright Ne lines may suggest that the nova progenitor is a massive (1.2 M⊙) oxygen-neon white dwarf. The high outburst frequency of oxygen-neon novae implies that they likely produce an amount of Be similar, if not larger, to that produced by carbon-oxygen novae, then confirming that classical novae are among the main factories of lithium in the Galaxy.

Coronal Structures in Cool Stars

NASA Technical Reports Server (NTRS)

Oliversen, Ronald (Technical Monitor); Dupree, Andrea K.

2005-01-01

We have extended our study of the structure of coronas in cool stars to very young stars still accreting from their surrounding disks. In addition we are pursing the connection between coronal X-rays and a powerful diagnostic line in the infrared, the He I 10830Angstrom transition of helium. Highlights of these are summarized below including publications during this reporting period and presentations. Spectroscopy of the infrared He I (lambda10830) line with KECK/NIRSPEC and IRTF/CSHELL and of the ultraviolet C III (lambda977) and O VI (lambda1032) emission with FUSE reveals that the classical T Tauri star TW Hydrae exhibits P Cygni profiles, line asymmetries, and absorption indicative of a continuous, fast (approximately 400 kilometers per second), hot (approximately 300,000 K) accelerating outflow with a mass loss rate approximately 10(exp -11)-10(exp -12) solar mass yr(sup -1) or larger. Spectra of T Tauri N appear consistent with such a wind. The source of the emission and outflow seems restricted to the stars themselves. Although the mass accretion rate is an order of magnitude less for TW Hya than for T Tau, the outflow reaches higher velocities at chromospheric temperatures in TW Hya. Winds from young stellar objects may be substantially hotter and faster than previously thought. The ultraviolet emission lines, when corrected for absorption are broad. Emission associated with the accretion flow and shock is likely to show turbulent broadening. We note that the UV line widths are significantly larger than the X-ray line widths. If the X-rays from TW Hya are generated at the accretion shock, the UV lines may not be directly associated with the shock. On the other hand, studies of X-ray emission in young star clusters, suggest that the strength of the X-ray emission is correlated with stellar rotation, thus casting doubt on an accretion origin for the X-rays. We are beginning to access the infrared spectral region where the He I 108308Angstroms transition occurs. This line is particularly useful as a diagnostic of coronal radiation since it is formed by recombination following photoionization of neutral helium by coronal X-rays. Because the lower level of the transition is metastable, infrared radiation from the stellar photosphere is absorbed which provides a diagnostic of atmospheric dynamics. This transition is useful both in young stars in the T Tauri phase and in active cool star binaries. We will investigate the influence of coronal x-rays on the strength of this transition.

THE NATURE OF A GALAXY ALONG THE SIGHT LINE TO PKS 0454+039

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

Takamiya, Marianne; Chun, Mark; Kulkarni, Varsha P.

2012-10-01

We report on the properties of a faint blue galaxy (G1) along the line of sight to the QSO PKS 0454+039 from spectroscopic and imaging data. We measured emission lines of H{alpha}, [S II] {lambda}{lambda}6716, 6732, and [N II] {lambda}6584 in the spectrum of G1 obtained with the Gemini/GMOS instrument. The spectroscopic redshift of G1 is z = 0.0715 {+-} 0.0002. From the extinction-corrected H{alpha} flux, we determine a modest star formation rate of SFR = 0.07 M{sub Sun} yr{sup -1} and a specific SFR of log (sSFR) -8.4. Using three different abundance indicators, we determine a nebular abundance 12more » + log (O/H) ranging from 7.6 to 8.2. Based on the velocity dispersion inferred from the emission line widths and the observed surface brightness profile, we estimate the virial mass of G1 to be M{sub vir} {approx} 6.7 Multiplication-Sign 10{sup 9} M{sub Sun} with an effective radius of 2.0 kpc. We estimate the stellar mass of G1 using spectral energy distribution fitting to be M{sub *} Almost-Equal-To 1.2 Multiplication-Sign 10{sup 7} M{sub Sun} and an r'-luminosity of L{sub r'} = 1.5x10{sup 8} L{sub Sun }. Overall, G1 is a faint, low-mass, low-metallicity Im/H II galaxy. We also report on the line flux limits of another source (G3) which is the most likely candidate for the absorber system at z = 0.8596. From the spectrum of the QSO itself, we report a previously undetected Mg II {lambda}{lambda}2796, 2803 absorption line system at z = 1.245.« less

Measurements of J/{psi} and {psi}(2S) decays into {lambda}{lambda}{pi}{sup 0} and {lambda}{lambda}{eta}

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

Ablikim, M.; Bai, J. Z.; Cai, X.

2007-11-01

Using 58x10{sup 6} J/{psi} and 14x10{sup 6} {psi}(2S) events collected by the BESII detector at the BEPC, branching fractions or upper limits for the decays J/{psi} and {psi}(2S){yields}{lambda}{lambda}{pi}{sup 0} and {lambda}{lambda}{eta} are measured. For the isospin violating decays, the upper limits are determined to be B(J/{psi}{yields}{lambda}{lambda}{pi}{sup 0})<6.4x10{sup -5} and B[{psi}(2S){yields}{lambda}{lambda}{pi}{sup 0}]<4.9x10{sup -5} at the 90% confidence level. The isospin conserving process J/{psi}{yields}{lambda}{lambda}{eta} is observed for the first time, and its branching fraction is measured to be B(J/{psi}{yields}{lambda}{lambda}{eta})=(2.62{+-}0.60{+-}0.44)x10{sup -4}, where the first error is statistical and the second one is systematic. No {lambda}{lambda}{eta} signal is observed in {psi}(2S) decays, and B[{psi}(2S){yields}{lambda}{lambda}{eta}]<1.2x10{supmore » -4} is set at the 90% confidence level. Branching fractions of J/{psi} decays into {sigma}{sup +}{pi}{sup -}{lambda} and {sigma}{sup -}{pi}{sup +}{lambda} are also reported, and the sum of these branching fractions is determined to be B(J/{psi}{yields}{sigma}{sup +}{pi}{sup -}{lambda}+c.c.)=(1.52{+-}0.08{+-}0.16)x10{sup -3}.« less

Measurement of the branching fraction $${\\mathcal{B}}(\\Lambda^0_b\\rightarrow \\Lambda^+_c\\pi^-\\pi^+\\pi^-)$$ at CDF

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

Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.

We report an analysis of the {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} decay in a data sample collected by the CDF II detector at the Fermilab Tevatron corresponding to 2.4 fb{sup -1} of integrated luminosity. We reconstruct the currently largest samples of the decay modes {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}(2595){sup +}{pi}{sup -} (with {Lambda}{sub c}(2595){sup +} {yields} {Lambda}{sub c}{sup +}{pi}{sup +}{pi}{sup -}), {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}(2625){sup +}{pi}{sup -} (with {Lambda}{sub c}(2625){sup +} {yields} {Lambda}{sub c}{sup +}{pi}{sup +}{pi}{sup -}), {Lambda}{sub b}{sup 0} {yields} {Sigma}{sub c}(2455){sup ++}{pi}{sup -}{pi}{sup -} (with {Sigma}{sub c}(2455){sup ++} {yields} {Lambda}{submore » c}{sup +}{pi}{sup +}), and {Lambda}{sub b}{sup 0} {yields} {Sigma}{sub c}(2455)0{pi}{sup +}{pi}{sup -} (with {Sigma}{sub c}(2455)0 {yields} {Lambda}{sub c}{sup +}{pi}{sup -}) and measure the branching fractions relative to the {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -} branching fraction. We measure the ratio {Beta}({Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -})/ {Beta}({Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -})=3.04 {+-} 0.33(stat){sub -0.55}{sup +0.70}(syst) which is used to derive {Beta}({Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -})=(26.8{sub -11.2}{sup +11.9}) x 10{sup -3}.« less

Comparative efficacy of oil solution and wettable powder of lambda-cyhalothrin to naturally occurring Ornithonyssus sylviarum infestation of chickens.

PubMed

Pan, Baoliang; Liang, Daming; Zhang, Yafeng; Wang, Hailiang; Wang, Ming

2009-10-14

The Northern Fowl Mite (NFM), Ornithonyssus sylviarum, is one of the most important and common pests of poultry. Most of available pesticides applied in the NFM control are formulated as wettable powder or emulsifiable concentrate and require to be diluted with water before use. As water has very low affinity to bird feathers, a part of the diluted pesticide will fall on the ground, on the cages, on feed bins or drift in the air upon application, which becomes a source of a potential harm to administrative workers and birds. In contrast to water, an oil solution of pesticide has a higher affinity for feathers and can stay on the feather for a longer time, and maybe provide a high efficacy and be effective for a longer, persistent period against the NFM. In the present study, the efficacy of oil solution and wettable powder of lambda-cyhalothrin to NFM in breeders was compared; the results showed that while spraying lambda-cyhalothrin wettable powder on birds could effectively control NFM, painting lambda-cyhalothrin oil solution on birds gave complete control of NFM for at least 6 weeks. In the application of lambda-cyhalothrin oil solution, no containment of pesticide to cages, feed bin and no pesticide drifting in the air was observed. These results indicated that lambda-cyhalothrin oil solution has a potential to become an effective and safe formulation to control NFM in breeders.

Origins of inert Higgs doublets

DOE PAGES

Kephart, Thomas W.; Yuan, Tzu -Chiang

2016-03-24

Here, we consider beyond the standard model embedding of inert Higgs doublet fields. We argue that inert Higgs doublets can arise naturally in grand unified theories where the necessary associated Z 2 symmetry can occur automatically. Several examples are discussed.

Doublet Pulse Coherent Laser Radar for Tracking of Resident Space Objects

DTIC Science & Technology

2014-09-01

based laser systems can be limited by the effects of tumbling, extremely accurate Doppler measurement is possible using a doublet coherent laser ...Doublet pulse coherent laser radar for tracking of resident space objects Narasimha S. Prasad *1 , Van Rudd 2 , Scott Shald 2 , Stephan...Doublet Pulse Coherent Laser Radar for Tracking of Resident Space Objects 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S

A flare event of the long-period RS Canum Venaticorum system IM Pegasi

NASA Technical Reports Server (NTRS)

Buzasi, Derek L.; Ramsey, Lawrence W.; Huenemoerder, David P.

1987-01-01

The characteristics of a flare event detected on the long-period RS CVn system IM Pegasi are reported. The low-resolution spectrum show enhancements of up to a factor of five in some emission lines. All of the ultraviolet emission lines normally visible are enhanced significantly more than the normal 30 rotational modulation. Emission fluxes of both the quiescent and flare event are used to construct models of the density and temperature variation with height. These models reveal a downward shift of the transition region during the flare. Scaled models of the quiet and flaring solar outer atmosphere are used to estimate the filling factor of the flare event at about 30 percent of the stellar surface. The pattern of line enhancements in the flare is the same as a previous event in Lambda Andromeda observed previously.

Relic gravitational waves and extended inflation

NASA Technical Reports Server (NTRS)

Turner, Michael S.; Wilczek, Frank

1990-01-01

In extended inflation, a new version of inflation where the transition from the false-vacuum phase to a radiation-dominated Universe is accomplished by bubble nucleation and percolation, bubble collisions supply a potent-and potentially detectable-source of gravitational waves. The present energy density in relic gravity waves from bubble collisions is expected to be about 10(exp -5) of closure density-many orders of magnitude greater than that of the gravity waves produced by quantum fluctuations. Their characteristic wavelength depends upon the reheating temperature T(sub RH): lambda is approximately 10(exp 4) cm (10(exp 14) GeV/T(sub RH)). If large numbers of black holes are produced, a not implausible outcome, they will evaporate producing comparable amounts of shorter wavelength waves, lambda is approximately 10(exp -6) cm (T(sub RH)/10(exp 14) GeV).

Study of B{yields}{lambda}{sub c}{lambda}{sub c} and B{yields}{lambda}{sub c}{lambda}{sub c}K

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

Cheng, H.-Y.; Hsiao, Y.-K.; Chua, C.-K.

2009-06-01

We study the doubly charmful two-body and three-body baryonic B decays B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -} and B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -}K. As pointed out before, a naive estimate of the branching ratio O(10{sup -8}) for the latter decay is too small by 3 to 4 orders of magnitude compared to experiment. Previously, it has been shown that a large enhancement for the {lambda}{sub c}{sup +}{lambda}{sub c}{sup -}K production can occur due to a charmoniumlike resonance (e.g. X(4630) discovered by Belle) with a mass near the {lambda}{sub c}{lambda}{sub c} threshold. Motivated by the BABAR's observation of a resonance in themore » {lambda}{sub c}K system with a mass of order 2930 MeV, we study in this work the contribution to B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -}K from the intermediate state {xi}{sub c}(2980) which is postulated to be a first positive-parity excited D-wave charmed baryon state. Assuming that a soft qq quark pair is produced through the {sigma} and {pi} meson exchanges in the configuration for B{yields}{xi}{sub c}(2980){lambda}{sub c} and {lambda}{sub c}{lambda}{sub c}, it is found that branching ratios of B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -}K and B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -} are of order 3.5x10{sup -4} and 5x10{sup -5}, respectively, in agreement with experiment except that the prediction for the {lambda}{sub c}{lambda}{sub c}K{sup -} is slightly smaller. In conjunction with our previous analysis, we conclude that the enormously large rate of B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -}K arises from the resonances {xi}{sub c}(2980) and X(4630)« less

MAGNETIC RELAXATION IN RARE EARTH DOPED GARNET.

DTIC Science & Technology

in resonance measurements by the constant low temperature linewidth due to two magnon scattering. In contrast, the PPI relaxation rate is independent...of two magnon scattering. The 4.5K doublet may well be related to a near crossing of energy levels which probably causes the anomalous low temperature peaks in delta H and resonance field observed by Dillon. (Author)

Mode Transitions in Magnetically Shielded Hall Effect Thrusters

NASA Technical Reports Server (NTRS)

Sekerak, Michael J.; Longmier, Benjamin W.; Gallimore, Alec D.; Huang, Wensheng; Kamhawi, Hani; Hofer, Richard R.; Jorns, Benjamin A.; Polk, James E.

2014-01-01

A mode transition study is conducted in magnetically shielded thrusters where the magnetic field magnitude is varied to induce mode transitions. Three different oscillatory modes are identified with the 20-kW NASA-300MS-2 and the 6-kW H6MS: Mode 1) global mode similar to unshielded thrusters at low magnetic fields, Mode 2) cathode oscillations at nominal magnetic fields, and Mode 3) combined spoke, cathode and breathing mode oscillations at high magnetic fields. Mode 1 exhibits large amplitude, low frequency (1-10 kHz), breathing mode type oscillations where discharge current mean value and oscillation amplitude peak. The mean discharge current is minimized while thrust-to-power and anode efficiency are maximized in Mode 2, where higher frequency (50-90 kHz), low amplitude, cathode oscillations dominate. Thrust is maximized in Mode 3 and decreases by 5-6% with decreasing magnetic field strength. The presence or absence of spokes and strong cathode oscillations do not affect each other or discharge current. Similar to unshielded thrusters, mode transitions and plasma oscillations affect magnetically shielded thruster performance and should be characterized during system development.

A study of the continuum flux and the line structure in the IUE spectrum of Beta Lyrae

NASA Technical Reports Server (NTRS)

Aydin, C.; Engin, S.; Brandi, E.; Ferrer, O. E.; Hack, M.

1988-01-01

A study of the available archival IUE images of Beta Lyrae has led to the following results: (1) for lambda in the range of 1250 - 1500 A, the eclipse depth at second conjunction is slightly larger than the eclipse depth at primary conjunction; they are equal at about 1670 A; (2) the profiles of the resonance lines of SiIV (and the same seems to be true for NV and CIV) can be described as composite, formed by the superposition of a stationary P Cygni profile that suggests a velocity of approach of -170 km/s and a broad, less strong, emission that seems to yield a velocity distribution in antiphase with the velocity curve of the B8 II component of the system; and (3) the emission lines of the intercombination doublet of semiforbidden N II at about 2140 A suggest a velocity of about -130 km/s. The interpretation of the latter composite profile appears similar to the one suggested by Sahade (1966) to describe H-alpha and He I 5876 and He I 6678, and by Batten and Sahade (1973) to describe H-alpha.

A laboratory study of the lambda 2145 A auroral mystery feature

NASA Technical Reports Server (NTRS)

Erdman, P. W.; Espy, P. J.; Zipf, E. C.

1980-01-01

The prominent emission feature near 2145 A in the ultraviolet spectrum of an aurora has been tentatively identified by Dick (1978) as the doublet lines, 2139.68 A and 2143.55 A, emitted by metastable N+(5S) ions, and dissociative excitation of N2 by electron impact with a cross section greater than or equal to 2 x 10 to the -18th sq cm has been proposed as the source of this species. A detailed laboratory study of dissociative excitation is described that suggests two alternative viewpoints of this process: (1) If the calculated radiative lifetime for the N+(5S) state (4.4 microsec) is correct, then the N+(5S) dissociative excitation cross section is less than 3 x 10 to the -21st sq cm. Thus, a new N+(5S) source mechanism would have to be found in order to account for the auroral data. (2) If dissociative excitation does form N+(5S) ions efficiently, then the laboratory and field observations imply a radiative lifetime for this state of more than 10 msec, thus suggesting that there are major errors in the lifetime computation.

NASA/FAA Tailplane Icing Program: Flight Test Report

NASA Technical Reports Server (NTRS)

Ratvasky, Thomas P.; VanZante, Judith Foss; Sim, Alex

2000-01-01

This report presents results from research flights that explored the characteristics of an ice-contaminated tailplane using various simulated ice shapes attached to the leading edge of the horizontal tailplane. A clean leading edge provided the baseline case, then three ice shapes were flown in order of increasing severity. Flight tests included both steady state and dynamic maneuvers. The steady state points were 1G wings level and steady heading sideslips. The primary dynamic maneuvers were pushovers to various G-levels; elevator doublets; and thrust transitions. These maneuvers were conducted for a full range of flap positions and aircraft angle of attack where possible. The analysis of this data set has clearly demonstrated the detrimental effects of ice contamination on aircraft stability and controllability. Paths to tailplane stall were revealed through parameter isolation and transition studies. These paths are (1) increasing ice shape severity, (2) increasing flap deflection, (3) high or low speeds, depending on whether the aircraft is in a steady state (high speed) or pushover maneuver (low speed), and (4) increasing thrust. The flight research effort was very comprehensive, but did not examine effects of tailplane design and location, or other aircraft geometry configuration effects. However, this effort provided the role of some of the parameters in promoting tailplane stall. The lessons learned will provide guidance to regulatory agencies, aircraft manufacturers, and operators on ice-contaminated tailplane stall in the effort to increase aviation safety and reduce the fatal accident rate.

Flagellar central pair assembly in Chlamydomonas reinhardtii

PubMed Central

2013-01-01

Background Most motile cilia and flagella have nine outer doublet and two central pair (CP) microtubules. Outer doublet microtubules are continuous with the triplet microtubules of the basal body, are templated by the basal body microtubules, and grow by addition of new subunits to their distal (“plus”) ends. In contrast, CP microtubules are not continuous with basal body microtubules, raising the question of how these microtubules are assembled and how their polarity is established. Methods CP assembly in Chlamydomonas reinhardtii was analyzed by electron microscopy and wide-field and super-resolution immunofluorescence microscopy. To analyze CP assembly independently from flagellar assembly, the CP-deficient katanin mutants pf15 or pf19 were mated to wild-type cells. HA-tagged tubulin and the CP-specific protein hydin were used as markers to analyze de novo CP assembly inside the formerly mutant flagella. Results In regenerating flagella, the CP and its projections assemble near the transition zone soon after the onset of outer doublet elongation. During de novo CP assembly in full-length flagella, the nascent CP was first apparent in a subdistal region of the flagellum. The developing CP replaces a fibrous core that fills the axonemal lumen of CP-deficient flagella. The fibrous core contains proteins normally associated with the C1 CP microtubule and proteins involved in intraflagellar transport (IFT). In flagella of the radial spoke-deficient mutant pf14, two pairs of CPs are frequently present with identical correct polarities. Conclusions The temporal separation of flagellar and CP assembly in dikaryons formed by mating CP-deficient gametes to wild-type gametes revealed that the formation of the CP does not require proximity to the basal body or transition zone, or to the flagellar tip. The observations on pf14 provide further support that the CP self-assembles without a template and eliminate the possibility that CP polarity is established by interaction with axonemal radial spokes. Polarity of the developing CP may be determined by the proximal-to-distal gradient of precursor molecules. IFT proteins accumulate in flagella of CP mutants; the abnormal distribution of IFT proteins may explain why these flagella are often shorter than normal. PMID:24283352

Measurement of the $$\\Lambda_b$$ cross section and the $$_{\\bar{\\Lambda}_b}$$ to $$\\Lambda_b$$ ratio with $$J/\\Psi \\Lambda$$ decays in $pp$ collisions at $$\\sqrt{s}=7$$ TeV

DOE PAGES

Chatrchyan, Serguei; et al.

2013-07-16

The Lambda(b) differential production cross section and the cross section ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Lambda(b) decays reconstructed in the exclusive final state J/Psi Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and Lambda to proton pion, using a data sample corresponding to an integrated luminosity of 1.9 inverse femtobarns. The product of the cross section times the branching ratio for Lambda(b) to J/Psi Lambda versusmore » pt(Lambda(b)) falls faster than that of b mesons. The measured value of the cross section times the branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06 +/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are statistical and systematic, respectively.« less

Oxaliplatin-Based Doublets Versus Cisplatin or Carboplatin-Based Doublets in the First-Line Treatment of Advanced Nonsmall Cell Lung Cancer.

PubMed

Yu, Jing; Xiao, Jing; Yang, Yifan; Cao, Bangwei

2015-07-01

The efficacy and toxicity of oxaliplatin-based versus carboplatin/cisplatin-based doublets in patients with previously untreated nonsmall cell lung cancer (NSCLC) have been compared.We searched published randomized controlled trials of oxaliplatin-based or carboplatin/cisplatin-based medications for NSCLC. A fixed effect model was used to analyze outcomes which were expressed as the hazard ratio for overall survival (OS) and time-to-progression (TTP), relative risk, overall response rate (ORR), disease control rate (DCR), 1-year survival, and the odds ratios for toxicity were pooled.Eight studies involving 1047 patients were included. ORR tended to favor carboplatin/cisplatin but the effect was not significantly different compared with oxaliplatin doublets (P = 0.05). The effects of OS, TTP, DCR, and 1-year survival between the 2 regimens were comparable. Oxaliplatin doublets caused less grade 3/4 leukocytopenia and neutropenia. Grades 3 to 4 nonhematological toxicities and grades 3 to 4 hematological toxicities showed little difference between oxaliplatin doublets and carboplatin/cisplatin doublets.Meta-analysis shows that the efficacy of oxaliplatin doublets is similar to that of other currently used platinum doublets. The lack of significant differences in the statistic analysis does not preclude genuine differences in clinical efficacy, because higher diversities between the studies covered differences between the 2 groups in each study. Oxaliplatin combined with a third-generation agent should be considered for use as alternative chemotherapy in patients who cannot tolerate conventional platinum-based regimens because the toxicity profile is much more favorable.

Study of the glassy magnetic behaviour and charge-ordering phase transitions in La0.75Ca0.25FeO3-δ perovskite

NASA Astrophysics Data System (ADS)

Abdel-Khalek, E. K.; Mohamed, E. A.; Salem, A. F.

2017-06-01

In this work, La0.75Ca0.25FeO3-δ perovskite sample was prepared by the coprecipitation method. The nanoparticle was found to crystallize in the orthorhombic (Pbnm) phase as confirmed by X-ray diffraction (XRD) and transmission electron microscopic (TEM). The oxygen non-stoichiometry (δ) and magnetic states of iron ions (three magnetic sextets and non-magnetic doublet) were investigated by Mössbauer spectroscopy at room temperature (RT). The shape of the magnetic hysteresis loop of the sample reveals the existence of a weak ferromagnetism at RT. The magnetization vs. temperature curves, measured in the 9 to 200 K range, showed that the sample exhibits two magnetic-phase transition temperatures at 29 K (Tg) and 120 K (TCO). The magnetization isotherms, M (H), around these magnetic-phase transition temperatures for the sample are analyzed.

High resolution infrared spectroscopy: Some new approaches and applications to planetary atmospheres

NASA Technical Reports Server (NTRS)

Mumma, M. J.

1978-01-01

The principles of spectral line formation and of techniques for retrieval of atmospheric temperature and constituent profiles are discussed. Applications to the atmospheres of Earth, Mars, Venus, and Jupiter are illustrated by results obtained with Fourier transform and infrared heterodyne spectrometers at resolving powers (lambda/delta hyperon lambda of approximately 10,000 and approximately 10 to the seventh power), respectively, showing the high complementarity of spectroscopy at these two widely different resolving powers. The principles of heterodyne spectroscopy are presented and its applications to atmospheric probing and to laboratory spectroscopy are discussed. Direct absorption spectroscopy with tuneable semiconductor lasers is discussed in terms of precision frequency-and line strength-measurements, showing substantial advances in laboratory infrared spectroscopy.

Enhanced effect of temporal variation of the fine structure constant and the strong interaction in 229Th.

PubMed

Flambaum, V V

2006-09-01

The relative effects of the variation of the fine structure constant alpha = e2/variant Planck's over 2pi c and the dimensionless strong interaction parameter m(q)/LambdaQCD are enhanced by 5-6 orders of magnitude in a very narrow ultraviolet transition between the ground and the first excited states in the 229Th nucleus. It may be possible to investigate this transition with laser spectroscopy. Such an experiment would have the potential of improving the sensitivity to temporal variation of the fundamental constants by many orders of magnitude.

A Real Space Cellular Automaton Laboratory

NASA Astrophysics Data System (ADS)

Rozier, O.; Narteau, C.

2013-12-01

Investigations in geomorphology may benefit from computer modelling approaches that rely entirely on self-organization principles. In the vast majority of numerical models, instead, points in space are characterised by a variety of physical variables (e.g. sediment transport rate, velocity, temperature) recalculated over time according to some predetermined set of laws. However, there is not always a satisfactory theoretical framework from which we can quantify the overall dynamics of the system. For these reasons, we prefer to concentrate on interaction patterns using a basic cellular automaton modelling framework, the Real Space Cellular Automaton Laboratory (ReSCAL), a powerful and versatile generator of 3D stochastic models. The objective of this software suite released under a GNU license is to develop interdisciplinary research collaboration to investigate the dynamics of complex systems. The models in ReSCAL are essentially constructed from a small number of discrete states distributed on a cellular grid. An elementary cell is a real-space representation of the physical environment and pairs of nearest neighbour cells are called doublets. Each individual physical process is associated with a set of doublet transitions and characteristic transition rates. Using a modular approach, we can simulate and combine a wide range of physical, chemical and/or anthropological processes. Here, we present different ingredients of ReSCAL leading to applications in geomorphology: dune morphodynamics and landscape evolution. We also discuss how ReSCAL can be applied and developed across many disciplines in natural and human sciences.

A HIRES/Keck Spectroscopic Investigation of the Measurement of Sodium in the Atmosphere of HD 209458b

NASA Astrophysics Data System (ADS)

Langland-Shula, Laura E.; Vogt, Steven S.; Charbonneau, David; Butler, Paul; Marcy, Geoff

2009-05-01

We present high-resolution High Resolution Echelle Spectrometer (HIRES)/Keck spectra of HD 209458, and a Monte Carlo variation on the basic method used by other workers, to look for the excess in-transit absorption in the NaD doublet at 5893 Å due to the extrasolar planet. The HIRES data, binned by bandpass, allow a direct comparison with previous results. We find >3σ results in most test bandpasses around the NaD doublet, including relative absorption of (-108.8 ± 25.7) × 10-5 in the "narrow" bandpass used by other workers. This is ≈4.7 times larger than the "narrow" results reported by Charbonneau et al. for HD 209458b. However, >2σ absorption is detected in some weak Fe I and Ni I lines that were tested for comparison, raising concern about the uncertainties introduced by continuum-fitting and terrestrial atmosphere subtraction. Based on data obtained with the W. M. Keck Observatory, which is operated by a partnership consisting of the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration.

Quantum Well Infrared Photodetectors (QWIP)

NASA Technical Reports Server (NTRS)

Levine, B. F.

1990-01-01

There has been a lot of interest in III-V long wavelength detectors in the lambda = 8 to 12 micron spectral range as alternatives to HgCdTe. Recently high performance quantum well infrared photodetectors (QWIP) have been demonstrated. They have a responsivity of R = 1.2 A/W, and a detectivity D(exp asterisk) sub lambda = 2 times 10(exp 10) cm Hz(exp 1/2)/W at 68 K for a QWIP with a cutoff wavelength of lambda sub c = 10.7 micron and a R = 1.0 A/W, and D(exp asterisk) sub lambda = 2 times 10(exp 10) cm Hz(exp 1/2)/W at T = 77 K for lambda sub c = 8.4 micron. These detectors consist of 50 periods of molecular beam epitaxy (MBE) grown layers doped n = 1 times 10(exp 18)cm(exp -3) having GaAs quantum well widths of 40 A and barrier widths of 500 A of Al sub x Ga sub 1-x As. Due to the well-established GaAs growth and processing techniques, these detectors have the potential for large, highly uniform, low cost, high performance arrays as well as monolithic integration with GaAs electronics, high speed and radiation hardness. Latest results on the transport physics, device performance and arrays are discussed.

Quantum Well Infrared Photodetectors (QWIP)

NASA Astrophysics Data System (ADS)

Levine, B. F.

1990-07-01

There has been a lot of interest in III-V long wavelength detectors in the lambda = 8 to 12 micron spectral range as alternatives to HgCdTe. Recently high performance quantum well infrared photodetectors (QWIP) have been demonstrated. They have a responsivity of R = 1.2 A/W, and a detectivity D(exp asterisk) sub lambda = 2 times 10(exp 10) cm Hz(exp 1/2)/W at 68 K for a QWIP with a cutoff wavelength of lambda sub c = 10.7 micron and a R = 1.0 A/W, and D(exp asterisk) sub lambda = 2 times 10(exp 10) cm Hz(exp 1/2)/W at T = 77 K for lambda sub c = 8.4 micron. These detectors consist of 50 periods of molecular beam epitaxy (MBE) grown layers doped n = 1 times 10(exp 18)cm(exp -3) having GaAs quantum well widths of 40 A and barrier widths of 500 A of Al sub x Ga sub 1-x As. Due to the well-established GaAs growth and processing techniques, these detectors have the potential for large, highly uniform, low cost, high performance arrays as well as monolithic integration with GaAs electronics, high speed and radiation hardness. Latest results on the transport physics, device performance and arrays are discussed.

Techniques for Solution- Assisted Optical Contacting

NASA Technical Reports Server (NTRS)

DeVine, Glenn; Ware, Brent; Wuchenich, Danielle M.; Spero, Robert E.; Klipstein, William M.; McKenzie, Kirk

2012-01-01

A document discusses a solution-assisted contacting technique for optical contacting. An optic of surface flatness Lambda/20 was successfully contacted with one of moderate surface quality, or Lambda/4. Optics used were both ultra-low expansion (ULE) glass (Lambda/4 and Lambda/20) and fused silica (Lambda/20). A stainless steel template of the intended interferometer layout was designed and constructed with three contact points per optic. The contact points were all on a common side of the template. The entire contacting jig was tilted at about 30 . Thus, when the isopropanol was applied, each optic slid due to gravity, resting on the contact points. All of the contacting was performed in a relatively dusty laboratory. A number of successful contacts were achieved where up to two or three visible pieces of dust could be seen. These were clearly visible due to refraction patterns between the optic and bench. On a number of optics, the final step of dropping isopropyl between the surfaces was repeated until a successful contact was achieved. The new procedures realized in this work represent a simplification for optical contacting in the laboratory. They will both save time and money spent during the contacting process, and research and development phases. The techniques outlined are suitable for laboratory experiments, research, and initial development stages.

Photoelectron spectrum of PrO{sup −}

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

Kafader, Jared O.; Ray, Manisha; Jarrold, Caroline Chick

The photoelectron (PE) spectrum of PrO{sup −} exhibits a short 835 ± 20 cm{sup −1} vibrational progression of doublets (210 ± 30 cm{sup −1} splitting) assigned to transitions from the 4f{sup 2} [{sup 3}H{sub 4}] σ{sub 6s}{sup 2} Ω = 4 anion ground state to the 4f{sup 2} [{sup 3}H{sub 4}] σ{sub 6s} Ω = 3.5 and 4.5 neutral states. This assignment is analogous to that of the recently reported PE spectrum of CeO{sup −}, though the 82 cm{sup −1} splitting between the 4f [{sup 2}F{sub 2.5}] σ{sub 6s} Ω = 2 and Ω = 3 CeO neutral states couldmore » not be resolved [Ray et al., J. Chem. Phys. 142, 064305 (2015)]. The origin of the transition to the Ω = 3.5 neutral ground state is 0.96 ± 0.01 eV, which is the adiabatic electron affinity of PrO. Density functional theory calculations on the anion and neutral molecules support the assignment. The appearance of multiple, irregularly spaced and low-intensity features observed ca. 1 eV above the ground state cannot be reconciled with low-lying electronic states of PrO that are accessible via one-electron detachment. However, neutral states correlated with the 4f{sup 2} [{sup 3}H{sub 4}] 5d superconfiguration are predicted to be approximately 1 eV above the 4f{sup 2} [{sup 3}H{sub 4}] σ{sub 6s} Ω = 3.5 neutral ground state, leading to the assignment of these features to shake-up transitions to the excited neutral states. Based on tentative hot band transition assignments, the term energy of the previously unobserved 4f{sup 2} [{sup 3}H{sub 4}] σ{sub 6s} Ω = 2.5 neutral state is determined to be 1840 ± 110 cm{sup −1}.« less

State Switching of the X-Ray/Radio Transitional Millisecond Pulsar

NASA Astrophysics Data System (ADS)

Shang, Lun-Hua; Zhang, Cheng-Min; Li, Di; Wang, De-Hua; Wang, Shuang-Qiang; Wang, Pei; Pan, Yuan-Yue; Yang, Yi-Yan; Zhi, Qi-Jun

2017-11-01

PSR J1023+0038 is a known transitional pulsar, which switches between the accretion-powered X-ray pulsar state and the rotation-powered radio millisecond pulsar (MSP) state. Here, we study the conditions for its state transition by ascribing ˜GHz radio pulse emission to the plasma cutoff oscillation frequency at the magnetosphere, which depends on the plasma density or accretion rate. With the accretion X-ray luminosity declining fromhigh to low state (e.g., ˜ {10}35 erg s-1 to ˜ {10}32 erg s-1), the magnetosphere boundary expands to the light cylinder, where the plasma density is low enough to permit the emission of radio waves at the several-GHz frequency band. Thus, for a sufficiently low accretion-rate state (˜ {10}32 erg s-1), the radio emission at the several-GHz band is not blocked by the plasma, and the radio pulsar can be detected in the favored “observational windows,” I.e., the L band (1-2 GHz), S band (2-4 GHz), and C band (4-8 GHz). Furthermore, to evaluate the penetration characteristics of the outgoing radio wave of low frequency, we calculate its skin depth, which is found to be a couple of centimeters for the low X-ray luminosity of {10}34{--}{10}32 erg s-1, a scale that is much shorter than the light cylinder radius of about 100 km for MSPs.

A microcontroller system for investigating the catch effect: functional electrical stimulation of the common peroneal nerve.

PubMed

Hart, D J; Taylor, P N; Chappell, P H; Wood, D E

2006-06-01

Correction of drop foot in hemiplegic gait is achieved by electrical stimulation of the common peroneal nerve with a series of pulses at a fixed frequency. However, during normal gait, the electromyographic signals from the tibialis anterior muscle indicate that muscle force is not constant but varies during the swing phase. The application of double pulses for the correction of drop foot may enhance the gait by generating greater torque at the ankle and thereby increase the efficiency of the stimulation with reduced fatigue. A flexible controller has been designed around the Odstock Drop Foot Stimulator to deliver different profiles of pulses implementing doublets and optimum series. A peripheral interface controller (PIC) microcontroller with some external circuits has been designed and tested to accommodate six profiles. Preliminary results of the measurements from a normal subject seated in a multi-moment chair (an isometric torque measurement device) indicate that profiles containing doublets and optimum spaced pulses look favourable for clinical use.

[The expression of interferon-lambda1 in CHO cell].

PubMed

Yuan, Wu-Mei; Ma, Fen-Lian; Zhang, Qian; Zheng, Wen-Zhi; Zheng, Li-Shu

2013-06-01

To construct the eukaryotic expression vector PCI-dhfr-lambda1 and PCI-dhfr-SP163-lambda1 which linked the enhancer SP163 with interferon lambda1. Then express the interferon lambda1 in CHO (dhfr-) cells. Using PCR method to introduce the restriction enzyme sites and through the fusion PCR binding the enhancer with the interferon Lambda1. After sequenced, lambda1 and SP163-lambda1 was inserted into PCI-dhfr forming the expression vector PCI-dhfr-lambda1 and PCI-dhfr-SP163-lambda1 which was constructed successfully confirming by sequencing. Then the expressing vectors were transfected into CHO (dhfr-) cells using liposome transfection method and interferon lambda1 protein was assayed with indirect immunofluorescence and Western Blot. Using cytopathic effect inhibition evaluated the antiviral activity of interferon lambda1. Successfully constructing the eukaryotic expression vectors of interferon lambda and the vectors could express interferon lambda1. The result of immunofluorescence showed the enhancer developed the expression of interferon lambda1. Detecting the interferon lambda1 in CHO (dhfr-) cells after transfecting 48 hour using Western Blot. The cytopathic effect inhibition showed the expressed interferon lambda1 has the antiviral activity. Successfully expressed the interferon lambda1 in CHO (dhfr-) cells and the protein possesses antiviral activity, which may supply a valuable basis for building the stable cell line of interferon lambda1.

Energy of the ground and 2{sup +} excited states of {sub {lambda}}{sub {lambda}}{sup 10}Be: A partial ten-body model

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

Shoeb, Mohammad; Sonika

2009-08-15

The energies of the ground and excited 2{sup +} states of {sub {lambda}}{sub {lambda}}{sup 10}Be have been calculated variationally in the Monte Carlo framework. The hypernucleus is treated as a partial ten-body problem in the {lambda}{lambda}+{alpha}{alpha} model where nucleonic degrees of freedom of {alpha}'s are taken into consideration ignoring the antisymmetrization between two {alpha}'s. The central two-body {lambda}N and {lambda}{lambda} and the three-body dispersive and two-pion exchange {lambda}NN forces, constrained by the {lambda}p scattering data and the observed ground state energies of {sub {lambda}}{sup 5}He and {sub {lambda}}{sub {lambda}}{sup 6}He, are employed. The product-type trial wave function predicts binding energymore » for the ground state considerably less than for the event reported by Danysz et al.; however, it is consistent with the value deduced assuming a {gamma} ray of 3.04 MeV must have escaped undetected in the decay of the product {sub {lambda}}{sup 9}Be* {yields} {sub {lambda}}{sup 9}Be+{gamma} of the emulsion event {sub {lambda}}{sub {lambda}}{sup 10}Be{yields} {pi}{sup -}+p+{sub {lambda}}{sup 9}Be* and for the excited 2{sup +} state closer to the value measured in the Demachi-Yanagi event. The hypernucleus {sub {lambda}}{sub {lambda}}{sup 10}Be has an oblate shape in the excited state. These results are consistent with the earlier four-body {alpha} cluster model approach where {alpha}'s are assumed to be structureless entities.« less

GALAXY CLUSTER BULK FLOWS AND COLLISION VELOCITIES IN QUMOND

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

Katz, Harley; McGaugh, Stacy; Teuben, Peter

We examine the formation of clusters of galaxies in numerical simulations of a QUMOND cosmogony with massive sterile neutrinos. Clusters formed in these exploratory simulations develop higher velocities than those found in {Lambda}CDM simulations. The bulk motions of clusters attain {approx}1000 km s{sup -1} by low redshift, comparable to observations whereas {Lambda}CDM simulated clusters tend to fall short. Similarly, high pairwise velocities are common in cluster-cluster collisions like the Bullet Cluster. There is also a propensity for the most massive clusters to be larger in QUMOND and to appear earlier than in {Lambda}CDM, potentially providing an explanation for ''pink elephants''more » like El Gordo. However, it is not obvious that the cluster mass function can be recovered.« less

Systems and methods for creation of conducting networks of magnetic particles through dynamic self-assembly process

DOEpatents

Snezhko, Oleksiy [Woodridge, IL; Aronson, Igor [Darien, IL; Kwok, Wai-Kwong [Downers Grove, IL

2011-01-25

Self-assembly of magnetic microparticles in AC magnetic fields. Excitation of the system by an AC magnetic field provides a variety of patterns that can be controlled by adjusting the frequency and the amplitude of the field. At low particle densities the low-frequency magnetic excitation favors cluster phase formation, while high frequency excitation favors chains and netlike structures. For denser configurations, an abrupt transition to the network phase was obtained.

Development of Fast, Background-Limited Transition-Edge Sensors for the Background-Limited Infrared/Sub-mm Spectrograph (BLISS) for SPICA

NASA Technical Reports Server (NTRS)

Beyer, Andrew D.; Runyan, M. C.; Kenyon, M.; Echternach, P. M .; Chui, T.; Bumble, B.; Bradford, C. M.; Holmes, W. A.; Bock, J. J.

2012-01-01

We report experimental progress toward demonstrating background-limited arrays of membrane-isolated transition-edge sensors (TESs) for the Background Limited Infrared/Sub-mm Spectrograph (BLISS). BLISS is a space-borne instrument with grating spectrometers for wavelengths lambda=35-435 micron and with R=lambda/delta lambda approximately equals 500. The goals for BLISS TESs are: noise equivalent power (NEP) = 5x10 (sup -20) W/Hz(exp 1/2) and response time tau <30ms. We expect background-limited performance from bilayers TESs with T(sub c) = 65mK and G=15fW/K. However, such TESs cannot be operated at 50mK unless stray power on the devices, or dark power P(sub D), is less than 200aW. We describe criteria for measuring P(sub D) that requires accurate knowledge of TC. Ultimately, we fabricated superconducting thermistors from Ir (T(sub c) >= 135mK) and Mo/Cu proximitized bilayers, where T(sub c) is the thermistor transition temperature. We measured the Ir TES arrays in our 50mK adiabatic demagnetization refrigerator test system, which can measure up to eight 1x32 arrays simultaneously using a time-division multiplexer, as well as our single-pixel test system which can measure down to 15mK. In our previous Ir array measurements our best reported performance was NEP=2.5x10(exp -19) W/Hz(sub 1/2) and Tau approximately equals 5ms for straight-beam TESs. In fact, we expected NEP approximately equals 1.5x10(exp -19)?W/Hz(sup 1/2) for meander beam TESs, but did not achieve this previously due to 1/f noise. Here, we detail improvements toward measuring the expected NEP and demonstrate NEP=(1.3+0.2)x10 (sup -19)W/Hz(exp 1/2) in our single-pixel test system and NEP=(1.6+/-0.3)x10(sup -19)W/Hz(sup 1/2) in our array test system.

Spectral Deconvolution of the 6196 and 6614 Å Diffuse Interstellar Bands Supports a Common-carrier Origin

NASA Astrophysics Data System (ADS)

Bernstein, L. S.; Shroll, R. M.; Galazutdinov, G. A.; Beletsky, Y.

2018-06-01

We explore the common-carrier hypothesis for the 6196 and 6614 Å diffuse interstellar bands (DIBs). The observed DIB spectra are sharpened using a spectral deconvolution algorithm. This reveals finer spectral features that provide tighter constraints on candidate carriers. We analyze a deconvolved λ6614 DIB spectrum and derive spectroscopic constants that are then used to model the λ6196 spectra. The common-carrier spectroscopic constants enable quantitative fits to the contrasting λ6196 and λ6614 spectra from two sightlines. Highlights of our analysis include (1) sharp cutoffs for the maximum values of the rotational quantum numbers, J max = K max, (2) the λ6614 DIB consisting of a doublet and a red-tail component arising from different carriers, (3) the λ6614 doublet and λ6196 DIBs sharing a common carrier, (4) the contrasting shapes of the λ6614 doublet and λ6196 DIBs arising from different vibration–rotation Coriolis coupling constants that originate from transitions from a common ground state to different upper electronic state degenerate vibrational levels, and (5) the different widths of the two DIBs arising from different effective rotational temperatures associated with principal rotational axes that are parallel and perpendicular to the highest-order symmetry axis. The analysis results suggest a puckered oblate symmetric top carrier with a dipole moment aligned with the highest-order symmetry axis. An example candidate carrier consistent with these specifications is corannulene (C20H10), or one of its symmetric ionic or dehydrogenated forms, whose rotational constants are comparable to those obtained from spectral modeling of the DIB profiles.

Three-frequency BDS precise point positioning ambiguity resolution based on raw observables

NASA Astrophysics Data System (ADS)

Li, Pan; Zhang, Xiaohong; Ge, Maorong; Schuh, Harald

2018-02-01

All BeiDou navigation satellite system (BDS) satellites are transmitting signals on three frequencies, which brings new opportunity and challenges for high-accuracy precise point positioning (PPP) with ambiguity resolution (AR). This paper proposes an effective uncalibrated phase delay (UPD) estimation and AR strategy which is based on a raw PPP model. First, triple-frequency raw PPP models are developed. The observation model and stochastic model are designed and extended to accommodate the third frequency. Then, the UPD is parameterized in raw frequency form while estimating with the high-precision and low-noise integer linear combination of float ambiguity which are derived by ambiguity decorrelation. Third, with UPD corrected, the LAMBDA method is used for resolving full or partial ambiguities which can be fixed. This method can be easily and flexibly extended for dual-, triple- or even more frequency. To verify the effectiveness and performance of triple-frequency PPP AR, tests with real BDS data from 90 stations lasting for 21 days were performed in static mode. Data were processed with three strategies: BDS triple-frequency ambiguity-float PPP, BDS triple-frequency PPP with dual-frequency (B1/B2) and three-frequency AR, respectively. Numerous experiment results showed that compared with the ambiguity-float solution, the performance in terms of convergence time and positioning biases can be significantly improved by AR. Among three groups of solutions, the triple-frequency PPP AR achieved the best performance. Compared with dual-frequency AR, additional the third frequency could apparently improve the position estimations during the initialization phase and under constraint environments when the dual-frequency PPP AR is limited by few satellite numbers.

Beauty Baryons at CDF and DO

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

Kryemadhi, Abaz

The results from Tevatron in the baryonic sector are presented. The lifetime of {lambda}b {yields} J/{psi}{lambda}, the observation of hadronic decay of {lambda}b {yields} {lambda}c{pi}, the semileptonic decays of {lambda}b {yields} {lambda}c{mu}{nu}, the hadronization of the b-baryons, and the {lambda}b decays to {lambda}b {yields} p{pi} and {lambda}b {yields} pK are discussed. These measurements paint a nice picture of our understanding of the beauty baryons.

Communication: Helium nanodroplet isolation and rovibrational spectroscopy of hydroxymethylene

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

Leavitt, Christopher M.; Moradi, Christopher P.; Stanton, John F.

Here, hydroxymethylene (HCOH) and its d 1-isotopologue (HCOD) are isolated in low temperature helium nanodroplets following pyrolysis of glyoxylic acid. Transitions identified in the infrared spectrum are assigned exclusively to the trans-conformation based on previously reported anharmonic frequency computations. For the OH(D) and CH stretches, a-and b-type transitions are observed, and when taken in conjunction with CCSD(T)/cc-pVTZ computations, lower limits to the vibrational band origins are determined. The relative intensities of the a-and b-type transitions provide the orientation of the transition dipole moment in the inertial frame. The He nanodroplet data are in excellent agreement with anharmonic frequency computations reportedmore » here and elsewhere, confirming an appreciable Ar-matrix shift of the OH and OD stretches and strong anharmonic resonance interactions in the high-frequency stretch regions of the mid-infrared.« less

Communication: Helium nanodroplet isolation and rovibrational spectroscopy of hydroxymethylene

DOE PAGES

Leavitt, Christopher M.; Moradi, Christopher P.; Stanton, John F.; ...

2014-05-05

Here, hydroxymethylene (HCOH) and its d 1-isotopologue (HCOD) are isolated in low temperature helium nanodroplets following pyrolysis of glyoxylic acid. Transitions identified in the infrared spectrum are assigned exclusively to the trans-conformation based on previously reported anharmonic frequency computations. For the OH(D) and CH stretches, a-and b-type transitions are observed, and when taken in conjunction with CCSD(T)/cc-pVTZ computations, lower limits to the vibrational band origins are determined. The relative intensities of the a-and b-type transitions provide the orientation of the transition dipole moment in the inertial frame. The He nanodroplet data are in excellent agreement with anharmonic frequency computations reportedmore » here and elsewhere, confirming an appreciable Ar-matrix shift of the OH and OD stretches and strong anharmonic resonance interactions in the high-frequency stretch regions of the mid-infrared.« less

Advanced ACTPol Low-Frequency Array: Readout and Characterization of Prototype 27 and 39 GHz Transition Edge Sensors

NASA Astrophysics Data System (ADS)

Koopman, B. J.; Cothard, N. F.; Choi, S. K.; Crowley, K. T.; Duff, S. M.; Henderson, S. W.; Ho, S. P.; Hubmayr, J.; Gallardo, P. A.; Nati, F.; Niemack, M. D.; Simon, S. M.; Staggs, S. T.; Stevens, J. R.; Vavagiakis, E. M.; Wollack, E. J.

2018-05-01

Advanced ACTPol (AdvACT) is a third-generation polarization upgrade to the Atacama Cosmology Telescope, designed to observe the cosmic microwave background (CMB). AdvACT expands on the 90 and 150 GHz transition edge sensor (TES) bolometer arrays of the ACT Polarimeter (ACTPol), adding both high-frequency (HF, 150/230 GHz) and low-frequency (LF, 27/39 GHz) multichroic arrays. The addition of the high- and low-frequency detectors allows for the characterization of synchrotron and spinning dust emission at the low frequencies and foreground emission from galactic dust and dusty star-forming galaxies at the high frequencies. The increased spectral coverage of AdvACT will enable a wide range of CMB science, such as improving constraints on dark energy, the sum of the neutrino masses, and the existence of primordial gravitational waves. The LF array will be the final AdvACT array, replacing one of the MF arrays for a single season. Prior to the fabrication of the final LF detector array, we designed and characterized prototype TES bolometers. Detector geometries in these prototypes are varied in order to inform and optimize the bolometer designs for the LF array, which requires significantly lower noise levels and saturation powers (as low as {˜ } 1 pW) than the higher-frequency detectors. Here we present results from tests of the first LF prototype TES detectors for AdvACT, including measurements of the saturation power, critical temperature, thermal conductance, and time constants. We also describe the modifications to the time-division SQUID readout architecture compared to the MF and HF arrays.

Search for b\\to u Transitions in \\Bz \\to \\Dz \\Kstarz Decays

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

Aubert, B.; Bona, M.; Karyotakis, Y.

We present a study of the decays B{sup 0} {yields} D{sup 0} K*{sup 0} and B{sup 0} {yields} {bar D}{sup 0} K*{sup 0} with K*{sup 0} {yields} K{sup +}{pi}{sup -}. The D{sup 0} and the {bar D}{sup 0} mesons are reconstructed in the final states f = K{sup +} {pi}{sup -}, K{sup +}{pi}{sup -}{pi}{sup 0}, K{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} and their charge conjugates. Using a sample of 465 million B{bar B} pairs collected with the BABAR detector at PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC, we measure the ratio R{sub ADS} {triple_bond} [{Lambda}({bar B}{sup 0} {yields} [f]{sub D}{barmore » K}*{sup 0}) + {Lambda}(B{sup 0} {yields} [{bar f}]{sub D}K*{sup 0})]/[{Lambda}({bar B}{sup 0} {yields} [{bar f}]{sub D}{bar K}*{sup 0}) + {Lambda}(B{sup 0} {yields} [f]{sub D}K*{sup 0})] for the three final states. We do not find significant evidence for a signal and set the following limits at 95% probability: R{sub ADS}(K{pi}) < 0.244, R{sub ADS}(K{pi}{pi}{sup 0}) < 0.181 and R{sub ADS}(K{pi}{pi}{pi}) < 0.391. From the combination of these three results, we find that the ratio r{sub S} between the b {yields} u and the b {yields} c amplitudes lies in the range [0.07; 0.41] at 95% probability.« less

Improved measurement of the form factors in the decay lambda+c-->lambda + nue.

PubMed

Hinson, J W; Huang, G S; Lee, J; Miller, D H; Pavlunin, V; Rangarajan, R; Sanghi, B; Shibata, E I; Shipsey, I P J; Cronin-Hennessy, D; Park, C S; Park, W; Thayer, J B; Thorndike, E H; Coan, T E; Gao, Y S; Liu, F; Stroynowski, R; Artuso, M; Boulahouache, C; Blusk, S; Dambasuren, E; Dorjkhaidav, O; Mountain, R; Muramatsu, H; Nandakumar, R; Skwarnicki, T; Stone, S; Wang, J C; Csorna, S E; Danko, I; Bonvicini, G; Cinabro, D; Dubrovin, M; McGee, S; Bornheim, A; Lipeles, E; Pappas, S P; Shapiro, A; Sun, W M; Weinstein, A J; Briere, R A; Chen, G P; Ferguson, T; Tatishvili, G; Vogel, H; Watkins, M E; Adam, N E; Alexander, J P; Berkelman, K; Boisvert, V; Cassel, D G; Duboscq, J E; Ecklund, K M; Ehrlich, R; Galik, R S; Gibbons, L; Gittelman, B; Gray, S W; Hartill, D L; Heltsley, B K; Hsu, L; Jones, C D; Kandaswamy, J; Kreinick, D L; Magerkurth, A; Mahlke-Krüger, H; Meyer, T O; Mistry, N B; Patterson, J R; Peterson, D; Pivarski, J; Richichi, S J; Riley, D; Sadoff, A J; Schwarthoff, H; Shepherd, M R; Thayer, J G; Urner, D; Wilksen, T; Warburton, A; Weinberger, M; Athar, S B; Avery, P; Breva-Newell, L; Potlia, V; Stoeck, H; Yelton, J; Benslama, K; Cawlfield, C; Eisenstein, B I; Gollin, G D; Karliner, I; Lowrey, N; Plager, C; Sedlack, C; Selen, M; Thaler, J J; Williams, J; Edwards, K W; Besson, D; Anderson, S; Frolov, V V; Gong, D T; Kubota, Y; Li, S Z; Poling, R; Smith, A; Stepaniak, C J; Urheim, J; Metreveli, Z; Seth, K K; Tomaradze, A; Zweber, P; Ahmed, S; Alam, M S; Ernst, J; Jian, L; Saleem, M; Wappler, F; Arms, K; Eckhart, E; Gan, K K; Gwon, C; Honscheid, K; Kagan, H; Kass, R; Pedlar, T K; von Toerne, E; Severini, H; Skubic, P; Dytman, S A; Mueller, J A; Nam, S; Savinov, V

2005-05-20

Using the CLEO detector at the Cornell Electron Storage Ring, we have studied the distribution of kinematic variables in the decay lambda(+)(c)lambda--> e(+)nu(e). By performing a four-dimensional maximum likelihood fit, we determine the form factor ratio, R= f(2)/f(1) = -0.31 +/- 0.05(stat) +/- 0.04(syst), the pole mass, M(pole) = [2.21 +/- 0.08(stat) +/- 0.14(syst)] GeV/c(2), and the decay asymmetry parameter of the lambda(+)(c), alpha (lambda(c)) = -0.86 +/-0.03(stat) +/- 0.02(syst), for q(2) = 0.67 (GeV/c(2))(2). We compare the angular distributions of the lambda(+)(c) and lambda(-)(c) and find no evidence for CP violation: A(lambda(c)) = (alpha(lambda(c)) + alpha (lambda(c)))/(alpha(lambda(c))-alpha(lambda(c))) = 0.00 +/- 0.03(stat) +/- 0.01(syst) +/- 0.02, where the third error is from the uncertainty in the world average of the CP-violating parameter, A(lambda), for ppi(-).

Deformation of giant vesicles in AC electric fields —Dependence of the prolate-to-oblate transition frequency on vesicle radius

NASA Astrophysics Data System (ADS)

Antonova, K.; Vitkova, V.; Mitov, M. D.

2010-02-01

The electrodeformation of giant vesicles is studied as a function of their radii and the frequency of the applied AC field. At low frequency the shape is prolate, at sufficiently high frequency it is oblate and at some frequency, fc, the shape changes from prolate to oblate. A linear dependence of the prolate-to-oblate transition inverse frequency, 1/fc, on the vesicle radius is found. The nature of this phenomenon does not change with the variation of both the solution conductivity, σ, and the type of the fluid enclosed by the lipid membrane (water, sucrose or glucose aqueous solution). When σ increases, the value of fc increases while the slope of the line 1/fc(r) decreases. For vesicles in symmetrical conditions (the same conductivity of the inner and the outer solution) a linear dependence between σ and the critical frequency, fc, is obtained for conductivities up to σ=114 μS/cm. For vesicles with sizes below a certain minimum radius, depending on the solution conductivity, no shape transition could be observed.

Evidence of nodes in the order parameter of the superconducting doped topological insulator Nb x Bi 2 Se 3 via penetration depth measurements

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

Smylie, M. P.; Claus, H.; Welp, U.

2016-11-01

The low-temperature variation of the London penetration depth lambda(T) in the candidate topological superconductor NbxBi2Se3 (x = 0.25) is reported for several crystals. The measurements were carried out by means of a tunnel-diode oscillator technique in both field orientations (H-rf || c and H-rf || ab planes). All samples exhibited power-law behavior at low temperatures (Delta lambda similar to T-2) clearly indicating the presence of point nodes in the superconducting order parameter. The results presented here are consistent with a nematic odd-parity spin-triplet E-u pairing state in NbxBi2Se3.

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

Polvonov, B. Z., E-mail: uzferfizika@mail.ru; Yuldashev, N. Kh.

The band of intrinsic (e–h) radiation emission by the subsurface potential barriers of crystal grains and the edge doublet band arising as LO-phonon replicas of the e–h band are observed in the spectra of the low-temperature (4.2 K) photoluminescence of fine-grained (with a grain size of d{sub cr} ≤ 1 µm) CdTe films. Film doping with the In impurity results in quenching of the doublet band, while heat treatment leads to activation of the intrinsic band, a short-wavelength shift of the red boundary (ΔE{sub r} = 16–29 meV) and the halfwidth modulation (Δ{sub A} = 6–17 meV) of which correlatemore » with the height of micropotential barriers and the temperature of recombining hot photocarriers.« less

Gravitational lensing limits on the cosmological constant in a flat universe

NASA Technical Reports Server (NTRS)

Turner, Edwin L.

1990-01-01

Inflationary cosmological theories predict, and some more general aesthetic criteria suggest, that the large-scale spatial curvature of the universe k should be accurately zero (i.e., flat), a condition which is satisfied when the universe's present mean density and the value of the cosmological constant Lambda have certain pairs of values. Available data on the frequency of multiple image-lensing of high-redshift quasars by galaxies suggest that the cosmological constant cannot make a dominant contribution to producing a flat universe. In particular, if the mean density of the universe is as small as the baryon density inferred from standard cosmic nucleosynthesis calculations or as determined from typical dynamical studies of galaxies and galaxy clusters, then a value of Lambda large enough to produce a k = 0 universe would result in a substantially higher frequency of multiple-image lensing of quasars than has been observed so far. Shortcomings of the available lens data and uncertainties concerning galaxy properties allow some possibility of escaping this conclusion, but systematic searches for a gravitational lenses and continuing investigations of galaxy mass distributions should soon provide decisive information. It is also noted that nonzero-curvature cosmological models can account for the observed frequency of galaxy-quasar lens systems and for a variety of other constraints.

Nonexponential London Penetration Depth of FeAs-Based Superconducting RFeAsO[subscript 0.9]F[subscript 0.1] (R=La, Nd) Single Crystals

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

Martin, C.; Tillman, M.E.; Kim, H.

2009-07-31

The superconducting penetration depth {lambda}(T) has been measured in RFeAsO{sub 0.9}F{sub 0.1} (R=La, Nd) single crystals (R-1111). In Nd-1111, we find an upturn in {lambda}(T) upon cooling and attribute it to the paramagnetism of the Nd ions, similar to the case of the electron-doped cuprate Nd-Ce-Cu-O. After the correction for paramagnetism, the London penetration depth variation is found to follow a power-law behavior, {Delta}{lambda}L(T) {proportional_to} T{sup 2} at low temperatures. The same T{sup 2} variation of {lambda}(T) was found in nonmagnetic La-1111 crystals. Analysis of the superfluid density and of penetration depth anisotropy over the full temperature range is consistentmore » with two-gap superconductivity. Based on this and on our previous work, we conclude that both the RFeAsO (1111) and BaFe{sub 2}As{sub 2} (122) families of pnictide superconductors exhibit unconventional two-gap superconductivity.« less

Observation of B{sup 0}{yields}{lambda}{lambda}K{sup 0} and B{sup 0}{yields}{lambda}{lambda}K*{sup 0} at Belle

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

Chang, Y.-W.; Wang, M.-Z.; Chao, Y.

2009-03-01

We study the charmless decays B{yields}{lambda}{lambda}h, where h stands for {pi}{sup +}, K{sup +}, K{sup 0},K*{sup +}, or K*{sup 0}, using a 605 fb{sup -1} data sample collected at the {upsilon}(4S) resonance with the Belle detector at the KEKB asymmetric energy e{sup +}e{sup -} collider. We observe B{sup 0}{yields}{lambda}{lambda}K{sup 0} and B{sup 0}{yields}{lambda}{lambda}K*{sup 0} with branching fractions of (4.76{sub -0.68}{sup +0.84}(stat){+-}0.61(syst))x10{sup -6} and (2.46{sub -0.72}{sup +0.87}{+-}0.34)x10{sup -6}, respectively. The significances of these signals in the threshold-mass enhanced mass region, M{sub {lambda}}{sub {lambda}}<2.85 GeV/c{sup 2}, are 12.4{sigma} and 9.3{sigma}, respectively. We also update the branching fraction B(B{sup +}{yields}{lambda}{lambda}K{sup +})=(3.38{sub -0.36}{sup +0.41}{+-}0.41)x10{supmore » -6} with better accuracy, and report the following measurement or 90% confidence level upper limit in the threshold-mass-enhanced region: B(B{sup +}{yields}{lambda}{lambda}K*{sup +})=(2.19{sub -0.88}{sup +1.13}{+-}0.33)x10{sup -6} with 3.7{sigma} significance; B(B{sup +}{yields}{lambda}{lambda}{pi}{sup +})<0.94x10{sup -6}. A related search for B{sup 0}{yields}{lambda}{lambda}D{sup 0} yields a branching fraction B(B{sup 0}{yields}{lambda}{lambda}D{sup 0})=(1.05{sub -0.44}{sup +0.57}{+-}0.14)x10{sup -5}. This may be compared with the large, {approx}10{sup -4}, branching fraction observed for B{sup 0}{yields}ppD{sup 0}. The M{sub {lambda}}{sub {lambda}} enhancements near threshold and related angular distributions for the observed modes are also reported.« less

Initiation of lambda DNA replication. The Escherichia coli small heat shock proteins, DnaJ and GrpE, increase DnaK's affinity for the lambda P protein.

PubMed

Osipiuk, J; Georgopoulos, C; Zylicz, M

1993-03-05

It is known that the initiation of bacteriophage lambda replication requires the orderly assembly of the lambda O.lambda P.DnaB helicase protein preprimosomal complex at the ori lambda DNA site. The DnaK, DnaJ, and GrpE heat shock proteins act together to destabilize the lambda P.DnaB complex, thus freeing DnaB and allowing it to unwind lambda DNA near the ori lambda site. The first step of this disassembly reaction is the binding of DnaK to the lambda P protein. In this report, we examined the influence of the DnaJ and GrpE proteins on the stability of the lambda P.DnaK complex. We present evidence for the existence of the following protein-protein complexes: lambda P.DnaK, lambda P.DnaJ, DnaJ.DnaK, DnaK.GrpE, and lambda P.DnaK.GrpE. Our results suggest that the presence of GrpE alone destabilizes the lambda P.DnaK complex, whereas the presence of DnaJ alone stabilizes the lambda P.DnaK complex. Using immunoprecipitation, we show that in the presence of GrpE, DnaK exhibits a higher affinity for the lambda P.DnaJ complex than it does alone. Using cross-linking with glutaraldehyde, we show that oligomeric forms of DnaK exhibit a higher affinity for lambda P than monomeric DnaK. However, in the presence of GrpE, monomeric DnaK can efficiently bind lambda P protein. These findings help explain our previous results, namely that in the GrpE-dependent lambda DNA replication system, the DnaK protein requirement can be reduced up to 10-fold.

Mössbauer Spectra of Mouse Hearts Reveal Age-dependent Changes in Mitochondrial and Ferritin Iron Levels.

PubMed

Wofford, Joshua D; Chakrabarti, Mrinmoy; Lindahl, Paul A

2017-03-31

Cardiac function requires continuous high levels of energy, and so iron, a critical player in mitochondrial respiration, is an important component of the heart. Hearts from 57 Fe-enriched mice were evaluated by Mössbauer spectroscopy. Spectra consisted of a sextet and two quadrupole doublets. One doublet was due to residual blood, whereas the other was due to [Fe 4 S 4 ] 2+ clusters and low-spin Fe II hemes, most of which were associated with mitochondrial respiration. The sextet was due to ferritin; there was no evidence of hemosiderin, a ferritin decomposition product. Iron from ferritin was nearly absent in young hearts, but increased steadily with age. EPR spectra exhibited signals similar to those of brain, liver, and human cells. No age-dependent EPR trends were apparent. Hearts from HFE -/- mice with hemochromatosis contained slightly more iron overall than controls, including more ferritin and less mitochondrial iron; these differences typify slightly older hearts, perhaps reflecting the burden due to this disease. HFE -/- livers were overloaded with ferritin but had low mitochondrial iron levels. IRP2 -/- hearts contained less ferritin than controls but normal levels of mitochondrial iron. Hearts of young mice born to an iron-deficient mother contained normal levels of mitochondrial iron and no ferritin; the heart from the mother contained low ferritin and normal levels of mitochondrial iron. High-spin Fe II ions were nearly undetectable in heart samples; these were evident in brains, livers, and human cells. Previous Mössbauer spectra of unenriched diseased human hearts lacked mitochondrial and blood doublets and included hemosiderin features. This suggests degradation of iron-containing species during sample preparation. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Calculated momentum dependence of Zhang-Rice states in transition metal oxides.

PubMed

Yin, Quan; Gordienko, Alexey; Wan, Xiangang; Savrasov, Sergey Y

2008-02-15

Using a combination of local density functional theory and cluster exact diagonalization based dynamical mean field theory, we calculate many-body electronic structures of several Mott insulating oxides including undoped high T(c) materials. The dispersions of the lowest occupied electronic states are associated with the Zhang-Rice singlets in cuprates and with doublets, triplets, quadruplets, and quintets in more general cases. Our results agree with angle resolved photoemission experiments including the decrease of the spectral weight of the Zhang-Rice band as it approaches k=0.

Quantum percolation phase transition and magnetoelectric dipole glass in hexagonal ferrites

NASA Astrophysics Data System (ADS)

Rowley, S. E.; Vojta, T.; Jones, A. T.; Guo, W.; Oliveira, J.; Morrison, F. D.; Lindfield, N.; Baggio Saitovitch, E.; Watts, B. E.; Scott, J. F.

2017-07-01

Hexagonal ferrites not only have enormous commercial impact (£2 billion/year in sales) due to applications that include ultrahigh-density memories, credit-card stripes, magnetic bar codes, small motors, and low-loss microwave devices, they also have fascinating magnetic and ferroelectric quantum properties at low temperatures. Here we report the results of tuning the magnetic ordering temperature in PbF e12 -xG axO19 to zero by chemical substitution x . The phase transition boundary is found to vary as TN˜(1-x /xc ) 2 /3 with xc very close to the calculated spin percolation threshold, which we determine by Monte Carlo simulations, indicating that the zero-temperature phase transition is geometrically driven. We find that this produces a form of compositionally tuned, insulating, ferrimagnetic quantum criticality. Close to the zero-temperature phase transition, we observe the emergence of an electric dipole glass induced by magnetoelectric coupling. The strong frequency behavior of the glass freezing temperature Tm has a Vogel-Fulcher dependence with Tm finite, or suppressed below zero in the zero-frequency limit, depending on composition x . These quantum-mechanical properties, along with the multiplicity of low-lying modes near the zero-temperature phase transition, are likely to greatly extend applications of hexaferrites into the realm of quantum and cryogenic technologies.

The first identification of C2 emission bands in comet Scorichenko-George (1989e1) spectrum

NASA Technical Reports Server (NTRS)

Churyumov, Klim I.; Chorny, G. F.

1992-01-01

Wave lengths from 360 emissions within the spectral range lambda lambda 3380-6290 A in the spectrum of the comet Scorichenko-George, obtained with the help of the TV spectral scanner of a 6-meter reflector BTA (in Special AO) have been determined. The CN, C2, C3, NH, CH, CO, Na, NH2, N2(+), CO(+), CO2(+), H2O(+), and C2(-) emissions have been identified. For the first time, it has been shown that emissions of C2(-) (the transitions 0-0, 0-1, et al.) in the cometary spectrum possibly exist. Molecular ions C2(-) column density with cross-section 1 sq cm is N = 1.44 10(exp -12) cm(exp -2) and their upper limits of gas C2(-) productivity is Q(C2(-)) = 2 10(exp 28) c(exp -1).

Estimation of Handling Qualities Parameters of the Tu-144 Supersonic Transport Aircraft from Flight Test Data

NASA Technical Reports Server (NTRS)

Curry, Timothy J.; Batterson, James G. (Technical Monitor)

2000-01-01

Low order equivalent system (LOES) models for the Tu-144 supersonic transport aircraft were identified from flight test data. The mathematical models were given in terms of transfer functions with a time delay by the military standard MIL-STD-1797A, "Flying Qualities of Piloted Aircraft," and the handling qualities were predicted from the estimated transfer function coefficients. The coefficients and the time delay in the transfer functions were estimated using a nonlinear equation error formulation in the frequency domain. Flight test data from pitch, roll, and yaw frequency sweeps at various flight conditions were used for parameter estimation. Flight test results are presented in terms of the estimated parameter values, their standard errors, and output fits in the time domain. Data from doublet maneuvers at the same flight conditions were used to assess the predictive capabilities of the identified models. The identified transfer function models fit the measured data well and demonstrated good prediction capabilities. The Tu-144 was predicted to be between level 2 and 3 for all longitudinal maneuvers and level I for all lateral maneuvers. High estimates of the equivalent time delay in the transfer function model caused the poor longitudinal rating.

Transition from Townsend to radio-frequency homogeneous dielectric barrier discharge in a roll-to-roll configuration

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

Bazinette, R.; SIAME, Université de Pau et des Pays de l'Adour, Pau; Paillol, J.

The aim of this paper is to better understand the transition from Townsend to radio-frequency homogeneous dielectric barrier discharge (DBD) at atmospheric pressure. The study is done in an Ar/NH{sub 3} Penning mixture for an electrode configuration adapted to roll-to-roll plasma surface treatment. The study was led in a frequency range running from 50 kHz up to 8.3 MHz leading to different DBD modes with a 1 mm gas gap: Glow (GDBD), Townsend (TDBD), and Radio-frequency (RF-DBD). In the frequency range between TDBD and RF-DBD, from 250 kHz to 2.3 MHz, additional discharges are observed outside the inter-electrode gas gap. Because each high voltagemore » electrode are inside a dielectric barrel, these additional discharges occur on the side of the barrel where the gap is larger. They disappear when the RF-DBD mode is attained in the 1 mm inter-electrode gas gap, i.e., for frequencies equal or higher than 3 MHz. Fast imaging and optical emission spectroscopy show that the additional discharges are radio-frequency DBDs while the inter-electrode discharge is a TDBD. The RF-DBD discharge mode is attained when electrons drift becomes low enough compared to the voltage oscillation frequency to limit electron loss at the anode. To check that the additional discharges are due to a larger gas gap and a lower voltage amplitude, the TDBD/RF-DBD transition is investigated as a function of the gas gap and the applied voltage frequency and amplitude. Results show that the increase in the frequency at constant gas gap or in the gas gap at constant frequency allows to obtain RF-DBD instead of TDBD. At low frequency and large gap, the increase in the applied voltage allows RF-DBD/TDBD transition. As a consequence, an electrode configuration allowing different gap values is a solution to successively have different discharge modes with the same applied voltage.« less

Multiple exposure routes of a pesticide exacerbate effects on a grazing mayfly.

PubMed

Pristed, Mathias Joachim Skov; Bundschuh, Mirco; Rasmussen, Jes Jessen

2016-09-01

Hydrophobic pesticides such as pyrethroid insecticides tend to occur in their soluble form mainly as transient pulses in streams. In addition, they are regularly detected in significant quantities adsorbed to stream sediments and other organic in-stream structures. Consequently, stream biota is likely subjected to pesticide exposure via multiple routes. In this study we aimed at investigating the influence of exposure routes for the pyrethroid insecticide lambda-cyhalothrin on the grazing mayfly Heptagenia sulphurea. Therefore, H. sulphurea was exposed to lambda-cyhalothrin via single- (water or biofilm) or biphasic exposure (water and biofilm) at environmentally realistic concentrations (0, 0.1, 1μgL(-1)) and exposure duration (2h) in a full factorial design (n=5). Mortality, moulting frequency, and biofilm accrual (proxy for feeding rate) were recorded subsequent to a 7 d post exposure period. Mortality significantly increased and moulting frequency significantly decreased with increasing concentrations of lambda-cyhalothrin in the water phase whereas exposure via biofilm prompted no significant effects on these endpoints (α=0.05). Effect predictions systematically underestimated and overestimated effects for mortality and moulting frequency, respectively. Similarly, mayfly feeding rate was significantly reduced by water phase exposure whereas pre-exposed biofilm did not significantly affect this variable. However, we found a significant but non-systematic interaction between water phase and biofilm exposure on mayfly feeding rate. Our results show that exposure to the same pesticide via multiple exposure routes may increase the magnitude of effects beyond the level predicted from single phase exposures which has clear implications for the aquatic risk assessment of hydrophobic pesticides. However, our results additionally reveal that interactions between pesticide exposure routes may vary between selected dependent variables. We emphasize that unravelling the underlying mechanisms causing these discrepancies in interactive effects between exposure routes is a major aspect that should receive further attention in future research. Copyright © 2016 Elsevier B.V. All rights reserved.

Physical interactions between bacteriophage and Escherichia coli proteins required for initiation of lambda DNA replication.

PubMed

Liberek, K; Osipiuk, J; Zylicz, M; Ang, D; Skorko, J; Georgopoulos, C

1990-02-25

The process of initiation of lambda DNA replication requires the assembly of the proper nucleoprotein complex at the origin of replication, ori lambda. The complex is composed of both phage and host-coded proteins. The lambda O initiator protein binds specifically to ori lambda. The lambda P initiator protein binds to both lambda O and the host-coded dnaB helicase, giving rise to an ori lambda DNA.lambda O.lambda P.dnaB structure. The dnaK and dnaJ heat shock proteins have been shown capable of dissociating this complex. The thus freed dnaB helicase unwinds the duplex DNA template at the replication fork. In this report, through cross-linking, size chromatography, and protein affinity chromatography, we document some of the protein-protein interactions occurring at ori lambda. Our results show that the dnaK protein specifically interacts with both lambda O and lambda P, and that the dnaJ protein specifically interacts with the dnaB helicase.

STS-52 Columbia, Orbiter Vehicle (OV) 102, crew insignia

NASA Image and Video Library

1999-05-24

STS052-S-001 (July 1992) --- The insignia, designed by the STS-52 crew members, features a large gold star to symbolize the crew's mission on the frontiers of space. A gold star is often used to symbolize the frontier period of the American West. The red star in the shape of the Greek letter lambda represents both the laser measurements to be taken from the Laser Geodynamic Satellite (LAGEOS II) and the Lambda Point Experiment, which is part of the United States Microgravity Payload (USMP-1). The LAGEOS II is a joint Italian\\United States satellite project intended to further our understanding of global plate tectonics. The USMP-1 is a microgravity facility which has French and United States experiments designed to test the theory of cooperative phase transitions and to study the solid\\liquid interface of a metallic alloy in the low gravity environment. The Remote Manipulator System (RMS) and maple leaf are emblematic of the Canadian payload specialist who will conduct a series of Canadian flight experiments (CANEX-2), including the Space Vision System test. The NASA insignia design for space shuttle flights is reserved for use by the astronauts and for other official use as the NASA Administrator may authorize. Public availability has been approved only in the form of illustrations by the various news media. When and if there is any change in this policy, which we do not anticipate, it will be publicly announced. Photo credit: NASA

Laser spectroscopic study of the Rydberg state structure of atomic lithium

NASA Astrophysics Data System (ADS)

Ballard, M. Kent

1998-07-01

Pulsed laser induced fluorescence spectroscopy was performed on both isotopic species of atomic lithium. Nonresonant multiphoton excitation spectra were recorded. The laser induced fluorescence of the lithium vapor was measured following excitation with a tunable, pulsed, nanosecond laser. Both two- and three-photon allowed transitions were observed resulting in four different transition series originating from the 22S and 22P levels, the latter likely originating from photodissociation products of the lithium dimer, Li2. Forty-seven identifiable transitions were assigned for 6Li. Evidence for a parity forbidden multiphoton transition is also present. For 7Li, fifty-three identifiable transitions were assigned including an additional series of parity forbidden multiphoton transitions. Laser polarization and power dependencies were measured and found to be consistent with the multiphoton transition probabilities. Due to the intense laser fields needed to produce the nonresonant multiphoton excitations, the lithium vapor was subjected to the laser induced ac Stark effect. The Autler-Townes doublets observed for the nF gets 2P transition series were found to exhibit normal asymmetry. The observed asymmetrical Autler-Townes profiles are explained in terms of the two-level and the three-level atomic systems which are based on different excitation schemes. A new computerized data acquisition system was developed as well as associated computer programs needed to analyze spectra.

Assessing the Susceptibility Status of Mosquitoes (Diptera: Culicidae) in a Dirofilariasis Focus, Northwestern Iran

PubMed Central

Ataie, Abolfazl; Moosa-Kazemi, Seyed Hassan; Vatandoost, Hassan; Yaghoobi-Ershadi, Mohammad Reza; Bakhshi, Hasan; Anjomruz, Mehdi

2015-01-01

Background: Mosquitoes are considered as the vectors of dirofilariasis and some vector borne disease in Iran. The objective of this study was to determine the susceptibility level of the vectors to various insecticides recommended by WHO for any control measures in an endemic area in northwestern Iran. Methods: Mosquito larval and adult collections were carried out using different methods provided by WHO including dipping and hand catch techniques. The susceptibility level was assessed to DDT 4%, malathion 5%, propoxur 0.1%, deltamethrin 0.05% and lambda-cyhalothrin 0.05%. Results: Totally, 749 adults and 5060 larvae of Culicidae mosquitoes were collected comprising seven species of adult and larvae, including: Anopheles claviger, An. maculipennis, An. sacharovi, Culex hortensis, Cx. pipiens, Cx. theileri and Culiseta longiaerolata. Frequency of larvae and adults of An. maculipennis was very low, so susceptibility tests on this species did not performed. Results showed that Cx. theileri, Cs. longiaerolata and Cx. pipiens were resistant to DDT 4%, lambda-cyhalothrin 0.05%, and propoxur 0.1% whereas found tolerant to deltamethrin 0.05% and malathion 5%. The LT50 and LT90 values for five insecticides were calculated. Conclusion: We suggest the same study in different parts of the world to obtain the data due to bionomic and susceptibility status of dirofilariasis vectors. This information will help the health authorities for monitoring and evaluation of control measures. PMID:26114140

Low energy theorems and the unitarity bounds in the extra U(1) superstring inspired E{sub 6} models

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

Sharma, N.K.; Saxena, Pranav; Nagawat, Ashok K.

2005-11-01

The conventional method using low energy theorems derived by Chanowitz et al. [Phys. Rev. Lett. 57, 2344 (1986);] does not seem to lead to an explicit unitarity limit in the scattering processes of longitudinally polarized gauge bosons for the high energy case in the extra U(1) superstring inspired models, commonly known as {eta} model, emanating from E{sub 6} group of superstring theory. We have made use of an alternative procedure given by Durand and Lopez [Phys. Lett. B 217, 463 (1989);], which is applicable to supersymmetric grand unified theories. Explicit unitarity bounds on the superpotential couplings (identified as Yukawa couplings)more » are obtained from both using unitarity constraints as well as using renormalization group equations (RGE) analysis at one-loop level utilizing critical couplings concepts implying divergence of scalar coupling at M{sub G}. These are found to be consistent with finiteness over the entire range M{sub Z}{<=}{radical}(s){<=}M{sub G} i.e. from grand unification scale to weak scale. For completeness, the similar approach has been made use of in other models i.e., {chi}, {psi}, and {nu} models emanating from E{sub 6} and it has been noticed that at weak scale, the unitarity bounds on Yukawa couplings do not differ among E{sub 6} extra U(1) models significantly except for the case of {chi} model in 16 representations. For the case of the E{sub 6}-{eta} model ({beta}{sub E} congruent with 9.64), the analysis using the unitarity constraints leads to the following bounds on various parameters: {lambda}{sub t(max.)}(M{sub Z})=1.294, {lambda}{sub b(max.)}(M{sub Z})=1.278, {lambda}{sub H(max.)}(M{sub Z})=0.955, {lambda}{sub D(max.)}(M{sub Z})=1.312. The analytical analysis of RGE at the one-loop level provides the following critical bounds on superpotential couplings: {lambda}{sub t,c}(M{sub Z}) congruent with 1.295, {lambda}{sub b,c}(M{sub Z}) congruent with 1.279, {lambda}{sub H,c}(M{sub Z}) congruent with 0.968, {lambda}{sub D,c}(M{sub Z}) congruent with 1.315. Thus superpotential coupling values obtained by both the approaches are in good agreement. Theoretically we have obtained bounds on physical mass parameters using the unitarity constrained superpotential couplings. The bounds are as follows: (i) Absolute upper bound on top quark mass m{sub t}{<=}225 GeV (ii) the upper bound on the lightest neutral Higgs boson mass at the tree level is m{sub H{sub 2}{sup 0}}{sup tree}{<=}169 GeV, and after the inclusion of the one-loop radiative correction it is m{sub H{sub 2}{sup 0}}{<=}229 GeV when {lambda}{sub t}{ne}{lambda}{sub b} at the grand unified theory scale. On the other hand, these are m{sub H{sub 2}{sup 0}}{sup tree}{<=}159 GeV, m{sub H{sub 2}{sup 0}}{<=}222 GeV, respectively, when {lambda}{sub t}={lambda}{sub b} at the grand unified theory scale. A plausible range on D-quark mass as a function of mass scale M{sub Z{sub 2}} is m{sub D}{approx_equal}O(3 TeV) for M{sub Z{sub 2}}{approx_equal}O(1 TeV) for the favored values of tan{beta}{<=}1. The bounds on aforesaid physical parameters in the case of {chi}, {psi}, and {nu} models in the 27 representation are almost identical with those of {eta} model and are consistent with the present day experimental precision measurements.« less

Constraints on the Lee-Wick Higgs sector

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

Carone, Christopher D.; Primulando, Reinard

2009-09-01

Lee-Wick partners to the standard model Higgs doublet may appear at a mass scale that is significantly lower than that of the remaining Lee-Wick partner states. The relevant effective theory is a two-Higgs doublet model in which one doublet has wrong-sign kinetic and mass terms. We determine bounds on this effective theory, including those from neutral B-meson mixing, b{yields}X{sub s}{gamma}, and Z{yields}bb. The results differ from those of conventional two-Higgs doublet models and lead to meaningful constraints on the Lee-Wick Higgs sector.

Doublet craters and the tidal disruption of binary asteroids

NASA Technical Reports Server (NTRS)

Melosh, H. J.; Stansberry, J. A.

1991-01-01

An evaluation is conducted of the possibility that the tidal disruption of a population of contact binary asteroids can account for terrestrial-impact 'doublet' craters. Detailed orbital integrations indicate that while such asteroids are often disrupted by tidal forces outside the Roche limit, the magnitude of the resulting separations is too small to account for the observed doublet craters. It is hypothesized that an initial population of km-scale earth-crossing objects encompassing 10-20 percent binaries must be responsible for doublet impacts, as may be verified by future observations of earth-approaching asteroids.

Photonic generation of ultra-wideband doublet pulse using a semiconductor-optical-amplifier based polarization-diversified loop.

PubMed

Luo, Bowen; Dong, Jianji; Yu, Yuan; Yang, Ting; Zhang, Xinliang

2012-06-15

We propose and demonstrate a novel scheme of ultra-wideband (UWB) doublet pulse generation using a semiconductor optical amplifier (SOA) based polarization-diversified loop (PDL) without any assistant light. In our scheme, the incoming gaussian pulse is split into two parts by the PDL, and each of them is intensity modulated by the other due to cross-gain modulation (XGM) in the SOA. Then, both parts are recombined with incoherent summation to form a UWB doublet pulse. Bi-polar UWB doublet pulse generation is demonstrated using an inverted gaussian pulse injection. Moreover, pulse amplitude modulation of UWB doublet is also experimentally demonstrated. Our scheme shows some advantages, such as simple implementation without assistant light and single optical carrier operation with good fiber dispersion tolerance.

57Fe Mössbauer study of the chainpur meteorite

NASA Astrophysics Data System (ADS)

Elewa, Nancy N.; Cobas, R.; Cadogan, J. M.

2016-12-01

The Chainpur meteorite is one of 23 ordinary chondrites classified as LL3-type (low-Fe & low-metal). It was observed as a shower of stones falling on May 9, 1907 in Uttar Pradesh, India. We report here the characterization of the Fe-bearing phases in this chondrite using 57Fe Mössbauer spectroscopy carried out at 298 K, 120 K, 50 K and 13 K. The paramagnetic doublets of olivine and pyroxene dominate the room temperature spectrum, accounting for around 70 % of the spectral area. Moreover, a doublet present with a spectral area of 5 % and assigned to a superparamagnetic Fe 3+ phase is a consequence of terrestrial weathering. On the basis of the measured 57Fe electric quadrupole splitting of the olivine component at room temperature we estimate the mean Fe:Mg ratio in this meteoritic olivine to be around 35:65 % although there is clearly a wide range of composition. The effects of magnetic ordering of the major components olivine and pyroxene are observed at 13 K.

SN 1994I in M51 and the nature of type Ibc supernovae

NASA Technical Reports Server (NTRS)

Wheeler, J. C.; Harkness, R. P.; Clocchiatti, A.; Benetti, S.; Brotherton, M. S.; Depoy, D. L.; Elias, J.

1994-01-01

Early spectra of SN 1994I in M51 (NGC 5194) are presented along with arguments that is a member of the class of helium-poor Type Ic supernovae. The issue of H and He in the spectra of Type Ib and Ic events is reexamined with the conclusion that Type Ib eject substantially less H than even transition events like SN 1993J and that Type Ic eject substantially less He than Type Ib and their optical spectra are consistent with no H or He. Type Ic show and absorption of the Si II lambda 6355 blend that characterizes Type Ia. This feature requires only a solar abundance of Si. Some Type Ic show an absorption that is probably C II lambda 6580. IR spectra are presented of SN 1990W which show the line of He I lambda 10830. The strength of this feature and the rather slow decay of the late time light curve suggest that this event could be better classified as a Type Ib. Even if trace abundances of H are present in Type Ib and of He in Type Ic the spectral differences still imply a distinctly different evolution for the progenitors of Type Ib from Type Ic and events like SN 1993J.